阅读说明：本技术 图像形成装置及其控制方法 (Image forming apparatus and control method thereof ) 是由 野野山昌宏 神谷昌弘 酒井克英 舛田纯一 木村拓 于 2021-06-25 设计创作，主要内容包括：本发明提供能够根据信封的种类进行适当的图像形成的图像形成装置及其控制方法。图像形成装置(1)具备：图像形成部(2),在沿着规定的输送路径输送的记录媒体上形成图像并输出；信封判断部(81),判断记录媒体是否是信封；基重获取部(82),获取记录媒体的基重；决定部(83),基于信封判断部(81)的判断结果和由基重获取部(82)获取的基重,决定在记录媒体上形成图像时的控制；以及打印控制部(84),基于决定部(83)的决定结果,控制图像形成部(2)的动作。(The invention provides an image forming apparatus capable of performing proper image formation according to the type of an envelope and a control method thereof. An image forming apparatus (1) is provided with: an image forming unit (2) that forms and outputs an image on a recording medium conveyed along a predetermined conveyance path; an envelope judging section (81) for judging whether the recording medium is an envelope; a basis weight acquisition unit (82) for acquiring the basis weight of the recording medium; a determination unit (83) for determining control when forming an image on a recording medium, based on the determination result of the envelope determination unit (81) and the basis weight acquired by the basis weight acquisition unit (82); and a print control unit (84) that controls the operation of the image forming unit (2) based on the determination result of the determination unit (83).)

1. An image forming apparatus is characterized by comprising:

an image forming unit that forms and outputs an image on a recording medium conveyed along a predetermined conveyance path;

an envelope judging unit that judges whether the recording medium is an envelope;

a basis weight acquiring unit that acquires a basis weight of the recording medium;

a deciding unit that decides control when forming an image on the recording medium based on a determination result of the envelope determining unit and the basis weight acquired by the basis weight acquiring unit; and

and a control unit that controls an operation of the image forming unit based on a determination result of the determination unit.

2. The image forming apparatus according to claim 1,

when the envelope determination unit determines that the recording medium is an envelope, the determination unit selects a first control parameter when the basis weight of the envelope acquired by the basis weight acquisition unit is higher than a predetermined value, and selects a second control parameter different from the first control parameter when the basis weight of the envelope acquired by the basis weight acquisition unit is lower than the predetermined value.

3. The image forming apparatus according to claim 1 or 2,

the image forming apparatus further includes a basis weight detecting unit that is provided upstream of a position where the image forming unit performs image formation in the conveying path and detects a basis weight of the recording medium conveyed along the conveying path,

the basis weight acquisition unit acquires the basis weight detected by the basis weight detection unit.

4. The image forming apparatus according to claim 3,

the basis weight acquisition unit sets a method of detecting the basis weight of the basis weight detection unit to a first method in a case where the envelope determination unit determines that the recording medium is not an envelope, and sets a method of detecting the basis weight of the basis weight detection unit to a second method different from the first method in a case where the envelope determination unit determines that the recording medium is an envelope.

5. The image forming apparatus according to claim 3 or 4,

the basis weight detection unit is configured to include at least one of a light-transmissive sensor and a light-reflective sensor.

6. The image forming apparatus according to claim 5,

the basis weight detecting unit increases the light amount or sensitivity of the light-transmissive sensor or the light-reflective sensor when the envelope determining unit determines that the recording medium is an envelope, as compared to when the recording medium is not determined to be an envelope.

7. The image forming apparatus according to claim 3,

the basis weight acquisition unit causes the basis weight detection unit to detect a basis weight of the recording medium in a case where the envelope determination unit determines that the recording medium is an envelope.

8. The image forming apparatus according to any one of claims 3 to 7,

when the envelope determination unit determines that the recording medium is an envelope, the basis weight acquisition unit causes the basis weight detection unit to detect the basis weight at a flap portion of the envelope.

9. The image forming apparatus according to claim 8,

the image forming apparatus further includes a flap detection unit provided upstream of the basis weight detection unit in the conveyance path,

the basis weight acquiring means detects the basis weight by the basis weight detecting means in association with detection of the flap portion of the envelope by the flap detecting means.

10. The image forming apparatus according to any one of claims 3 to 7,

when the envelope determination unit determines that the recording medium is an envelope, the basis weight acquisition unit causes the basis weight detection unit to detect the basis weight at a portion where sheets other than a flap portion of the envelope overlap.

11. The image forming apparatus according to claim 1 or 2,

the basis weight acquisition unit accepts an input operation of a basis weight by a user, and acquires the basis weight input by the user as the basis weight of the recording medium.

12. The image forming apparatus according to claim 1 or 2,

the envelope determination unit accepts a selection operation by a user whether or not it is an envelope, and determines that the recording medium is an envelope if it is selected by the user.

13. The image forming apparatus according to any one of claims 1 to 11,

the image forming apparatus further includes an envelope detection unit that is provided on an upstream side of a position where the image forming unit performs image formation in the conveyance path and detects that the recording medium conveyed along the conveyance path is an envelope,

the envelope determination unit determines that the recording medium is an envelope based on the detection of the recording medium being an envelope by the envelope detection unit.

14. The image forming apparatus according to claim 13,

the envelope detection unit is composed of an ultrasonic sensor.

15. The image forming apparatus according to any one of claims 1 to 14,

the determination unit determines at least one control parameter of a transport speed of a fixing roller for fixing an image to the recording medium, presence or absence of a curve formation of the recording medium between a position where the image is transferred to the recording medium and the fixing roller, a fixing temperature of the fixing roller, and a pressure contact force of the fixing roller.

16. The image forming apparatus according to any one of claims 1 to 15,

the determining unit changes a conveying speed of a fixing roller that fixes an image to the recording medium according to the basis weight of the envelope acquired by the basis weight acquiring unit, in a case where the recording medium is determined to be an envelope by the envelope determining unit.

17. The image forming apparatus according to claim 16,

the determining unit may increase a conveying speed of the fixing roller to a normal conveying speed when the basis weight of the envelope acquired by the basis weight acquiring unit is lower than a predetermined value.

18. The image forming apparatus according to any one of claims 15 to 17,

when the envelope determination unit determines that the recording medium is an envelope, and when the basis weight of the envelope acquired by the basis weight acquisition unit is lower than a predetermined value, the determination unit determines to perform control such that: no curvature of the recording medium is formed between a position where the image is transferred to the recording medium and the fixing roller.

19. The image forming apparatus according to any one of claims 15 to 18,

the decision unit changes the fixing temperature of the fixing roller in accordance with the basis weight of the envelope acquired by the basis weight acquisition unit in a case where the recording medium is determined to be an envelope by the envelope determination unit.

20. The image forming apparatus according to claim 19,

the determining unit may set the fixing temperature of the fixing roller to be lower than a normal fixing temperature when the basis weight of the envelope acquired by the basis weight acquiring unit is lower than a predetermined value.

21. The image forming apparatus according to any one of claims 15 to 20,

the decision unit changes the pressing force of the fixing roller according to the basis weight of the envelope acquired by the basis weight acquisition unit in a case where the recording medium is determined to be an envelope by the envelope determination unit.

22. The image forming apparatus according to claim 21,

the determining unit makes the pressing force of the fixing roller weaker than a normal pressing force when the basis weight of the envelope acquired by the basis weight acquiring unit is lower than a predetermined value.

23. The image forming apparatus according to any one of claims 1 to 22,

the image forming apparatus further includes a communication unit that communicates with an external apparatus,

the basis weight acquisition unit is capable of acquiring a basis weight of the recording medium from the external apparatus via the communication unit.

24. The image forming apparatus according to claim 23,

the envelope determination unit may determine that the recording medium is an envelope when it is designated from the external apparatus via the communication unit.

25. A control method of an image forming apparatus including an image forming unit that forms and outputs an image on a recording medium conveyed along a predetermined conveyance path, the control method comprising:

an envelope judgment step of judging whether the recording medium is an envelope;

a basis weight acquiring step of acquiring a basis weight of the recording medium;

a deciding step of deciding control when forming an image on the recording medium based on the determination result in the envelope determining step and the basis weight acquired by the basis weight acquiring step; and

and a control step of controlling an operation of the image forming unit based on a determination result in the determination step.

26. The control method according to claim 25,

in the determining step, when it is determined in the envelope determining step that the recording medium is an envelope, a first control parameter is selected when the basis weight of the envelope acquired in the basis weight acquiring step is higher than a predetermined value, and a second control parameter different from the first control parameter is selected when the basis weight of the envelope acquired in the basis weight acquiring step is lower than the predetermined value.

27. The control method according to claim 25 or 26,

the control method further includes a basis weight detecting step of detecting a basis weight of the recording medium conveyed along the conveying path at a position upstream of a position where the image forming unit performs image formation in the conveying path,

in the basis weight acquiring step, the basis weight detected in the basis weight detecting step is acquired.

28. The control method according to claim 27,

in the basis weight acquiring step, when it is determined in the envelope determining step that the recording medium is not an envelope, a method of detecting the basis weight in the basis weight detecting step is set to a first method, and when it is determined in the envelope determining step that the recording medium is an envelope, a method of detecting the basis weight in the basis weight detecting step is set to a second method different from the first method.

29. The control method according to claim 27 or 28,

in the basis weight detecting step, the basis weight is detected using at least one of a light-transmitting sensor and a light-reflecting sensor.

30. The control method according to claim 29,

in the basis weight detecting step, when the recording medium is determined to be an envelope in the envelope determining step, the light amount or sensitivity of the light transmissive sensor or the light reflective sensor is increased as compared with a case where the recording medium is determined not to be an envelope.

31. The control method according to claim 27,

in the basis weight acquiring step, in a case where it is determined in the envelope determining step that the recording medium is an envelope, the basis weight of the recording medium is detected in the basis weight detecting step.

32. The control method according to any one of claims 27 to 31,

in the basis weight acquiring step, when the recording medium is determined to be an envelope in the envelope determining step, the basis weight is detected at a flap portion of the envelope in the basis weight detecting step.

33. The control method according to claim 32,

the control method further includes a flap detecting step performed at a position on an upstream side of the basis weight detecting step in the conveyance path,

in the basis weight acquiring step, the basis weight is detected in the basis weight detecting step in association with the detection of the flap portion of the envelope in the flap detecting step.

34. The control method according to any one of claims 27 to 31,

in the basis weight acquiring step, when the recording medium is determined to be an envelope in the envelope determining step, the basis weight is detected in a portion where sheets other than a flap portion of the envelope overlap in the basis weight detecting step.

35. The control method according to claim 25 or 26,

in the basis weight acquisition step, an input operation of a basis weight by a user is accepted, and the basis weight input by the user is acquired as the basis weight of the recording medium.

36. The control method according to claim 25 or 26,

in the envelope judging step, a selection operation by a user whether or not it is an envelope is accepted, and in a case where it is selected by the user to be an envelope, it is judged that the recording medium is an envelope.

37. The control method according to any one of claims 25 to 35,

the control method further includes an envelope detection step of detecting that the recording medium conveyed along the conveyance path is an envelope at a position on an upstream side of a position where the image forming unit performs image formation in the conveyance path,

in the envelope judging step, it is judged that the recording medium is an envelope based on the detection that the recording medium is an envelope in the envelope detecting step.

38. The control method according to claim 37,

in the envelope detecting step, the envelope detecting is performed by an ultrasonic sensor.

39. The control method according to any one of claims 25 to 38,

in the determining step, at least one control parameter is determined from among a transport speed of a fixing roller for fixing an image to the recording medium, presence or absence of a curve formation of the recording medium between a position where the image is transferred to the recording medium and the fixing roller, a fixing temperature of the fixing roller, and a pressure contact force of the fixing roller.

40. The control method according to any one of claims 25 to 39,

in the determining step, when the recording medium is determined to be an envelope in the envelope determining step, a conveying speed of a fixing roller that fixes an image to the recording medium is changed in accordance with the basis weight of the envelope acquired in the basis weight acquiring step.

41. The control method according to claim 40,

in the determining step, when the basis weight of the envelope acquired in the basis weight acquiring step is lower than a predetermined value, the conveying speed of the fixing roller is made higher than a normal conveying speed.

42. The control method according to any one of claims 39 to 41,

in the determining step, when the envelope determining step determines that the recording medium is an envelope, and when the basis weight of the envelope acquired in the basis weight acquiring step is lower than a predetermined value, it is determined to perform control such that: no curvature of the recording medium is formed between a position where the image is transferred to the recording medium and the fixing roller.

43. The control method according to any one of claims 39 to 42,

in the deciding step, in a case where it is determined in the envelope determining step that the recording medium is an envelope, the fixing temperature of the fixing roller is changed in accordance with the basis weight of the envelope acquired in the basis weight acquiring step.

44. The control method according to claim 43,

in the determining step, when the basis weight of the envelope acquired in the basis weight acquiring step is lower than a predetermined value, the fixing temperature of the fixing roller is set lower than a normal fixing temperature.

45. The control method according to any one of claims 39 to 44,

in the deciding step, in a case where it is determined in the envelope determining step that the recording medium is an envelope, the pressing force of the fixing roller is changed in accordance with the basis weight of the envelope acquired in the basis weight acquiring step.

46. The control method according to claim 45,

in the determining step, when the basis weight of the envelope acquired in the basis weight acquiring step is lower than a predetermined value, the pressure contact force of the fixing roller is made weaker than a normal pressure contact force.

47. The control method according to any one of claims 25 to 46,

the image forming apparatus further includes a communication unit that communicates with an external apparatus,

in the basis weight acquiring step, the basis weight of the recording medium can be acquired from the external apparatus via the communication unit.

48. The control method according to claim 47,

in the envelope determination step, it is possible to determine that the recording medium is an envelope when it is designated from the external apparatus via the communication unit.

Technical Field

The present invention relates to an image forming apparatus and a control method thereof, and more particularly to a technique for forming an image suitable for an envelope when a recording medium to be subjected to image formation is an envelope.

Background

Conventionally, in an image forming apparatus such as a printer or an MFP (multi function Peripherals), there is known an apparatus that measures the thickness of a sheet such as a printing sheet, and performs setting related to the sheet based on the measured thickness to form an image (for example, patent document 1). Further, an image forming apparatus capable of forming an image on an envelope is also known (for example, patent document 2).

In recent years, the types of envelopes used as targets for image formation in image forming apparatuses have been increasing, and there are envelopes of various thicknesses depending on the types of envelopes. When an envelope is used as a recording medium to be subjected to image formation in an image forming apparatus, there is a problem that wrinkles are likely to occur when the envelope passes through a fixing device, as compared with a sheet such as a normal printing sheet. Therefore, when the image forming apparatus forms an image on an envelope as a recording medium, control different from that for forming an image on a sheet is performed, thereby suppressing wrinkles from occurring on the envelope.

However, in the conventional image forming apparatus, if the recording medium is an envelope, the image forming is performed by uniformly applying a predetermined setting value for the envelope. That is, in the case of using an envelope having a small thickness and in the case of using an envelope having a large thickness, the conventional image forming apparatus performs image formation by applying the same setting values.

However, in general, an envelope having a small thickness has a characteristic that wrinkles are more likely to be generated when passing through a fixing device than an envelope having a large thickness. Therefore, in the conventional image forming apparatus, when an image is formed on an envelope having a small thickness as a recording medium, wrinkles may be generated in the envelope, which may result in a problem that the quality of a printed product is deteriorated.

Patent document 1: japanese patent laid-open publication No. 2018-10056

Patent document 2: japanese patent laid-open publication No. 2017-211634

Disclosure of Invention

The present invention has been made to solve the above-described problems, and an object thereof is to provide an image forming apparatus capable of performing appropriate image formation according to the type of an envelope, and a control method thereof.

In order to achieve the above object, the present invention according to a first aspect provides an image forming apparatus including: an image forming unit that forms and outputs an image on a recording medium conveyed along a predetermined conveyance path; an envelope judging unit for judging whether the recording medium is an envelope; a basis weight acquiring unit for acquiring the basis weight of the recording medium; a determining unit configured to determine control for forming an image on the recording medium based on the determination result of the envelope determining unit and the basis weight acquired by the basis weight acquiring unit; and a control unit that controls an operation of the image forming unit based on a determination result of the determination unit.

An invention according to a second aspect is the image forming apparatus according to the first aspect, wherein when the envelope determining unit determines that the recording medium is an envelope, the determining unit selects a first control parameter when the basis weight of the envelope acquired by the basis weight acquiring unit is higher than a predetermined value, and selects a second control parameter different from the first control parameter when the basis weight of the envelope acquired by the basis weight acquiring unit is lower than the predetermined value.

A third aspect of the present invention is the image forming apparatus according to the first or second aspect, further comprising a basis weight detecting unit that is provided upstream of a position where the image forming unit forms an image in the conveying path and detects a basis weight of the recording medium conveyed along the conveying path, wherein the basis weight acquiring unit acquires the basis weight detected by the basis weight detecting unit.

An invention according to a fourth aspect is the image forming apparatus according to the third aspect, wherein the basis weight acquiring unit sets a method of detecting the basis weight of the basis weight detecting unit to a first method when the envelope judging unit judges that the recording medium is not an envelope, and sets a method of detecting the basis weight of the basis weight detecting unit to a second method different from the first method when the envelope judging unit judges that the recording medium is an envelope.

An invention according to a fifth aspect is the image forming apparatus according to the third or fourth aspect, wherein the basis weight detecting means is configured to include at least one of a light transmissive sensor and a light reflective sensor.

An invention according to a sixth aspect is the image forming apparatus according to the fifth aspect, wherein the basis weight detecting means increases a light amount or sensitivity of the light transmissive sensor or the light reflective sensor when the envelope determining means determines that the recording medium is an envelope, as compared with a case where the recording medium is determined not to be an envelope.

An invention according to a seventh aspect is the image forming apparatus according to the third aspect, wherein the basis weight acquiring unit causes the basis weight detecting unit to detect the basis weight of the recording medium when the envelope determining unit determines that the recording medium is an envelope.

An eighth aspect of the invention is the image forming apparatus according to any of the third to seventh aspects, wherein the basis weight acquiring means causes the basis weight detecting means to detect a basis weight at a flap portion of an envelope when the envelope determining means determines that the recording medium is an envelope.

An invention according to a ninth aspect is the image forming apparatus according to the eighth aspect, further comprising a flap detecting unit provided upstream of the basis weight detecting unit in the conveyance path, wherein the basis weight acquiring unit causes the basis weight detecting unit to detect a basis weight as the flap portion of the envelope is detected by the flap detecting unit.

An invention according to a tenth aspect is the image forming apparatus according to any of the third to seventh aspects, wherein the basis weight acquiring unit causes the basis weight detecting unit to detect the basis weight at a portion where sheets other than a flap portion of an envelope overlap each other, when the envelope determining unit determines that the recording medium is an envelope.

An eleventh aspect of the invention is the image forming apparatus according to the first or second aspect, wherein the basis weight acquiring unit receives an input operation of a basis weight by a user, and acquires the basis weight input by the user as the basis weight of the recording medium.

An invention according to a twelfth aspect is the image forming apparatus according to the first or second aspect, wherein the envelope determination unit accepts a selection operation by a user as to whether or not the recording medium is an envelope, and determines that the recording medium is an envelope when the envelope is selected by the user.

An invention according to a thirteenth aspect is the image forming apparatus according to any of the first to eleventh aspects, further comprising an envelope detecting unit that is provided upstream of a position where the image forming unit forms the image on the transport path and detects that the recording medium transported along the transport path is an envelope, wherein the envelope determining unit determines that the recording medium is an envelope based on the detection by the envelope detecting unit that the recording medium is an envelope.

An invention according to a fourteenth aspect is the image forming apparatus according to the thirteenth aspect, wherein the envelope detecting means is configured by an ultrasonic sensor.

An invention according to a fifteenth aspect is the image forming apparatus according to any one of the first to fourteenth aspects, wherein the determining unit determines at least one control parameter of a transport speed of a fixing roller for fixing the image to the recording medium, a presence or absence of a curve formation of the recording medium between a position where the image is transferred to the recording medium and the fixing roller, a fixing temperature of the fixing roller, and a pressure contact force of the fixing roller.

An invention according to a sixteenth aspect is the image forming apparatus according to any one of the first to fifteenth aspects, wherein the determining unit changes a conveying speed of a fixing roller that fixes the image to the recording medium in accordance with the basis weight of the envelope acquired by the basis weight acquiring unit, when the envelope determining unit determines that the recording medium is an envelope.

An invention according to a seventeenth aspect is the image forming apparatus according to the sixteenth aspect, wherein the determining unit increases the conveying speed of the fixing roller to a higher speed than a normal conveying speed when the basis weight of the envelope acquired by the basis weight acquiring unit is lower than a predetermined value.

An eighteenth aspect of the invention is summarized as the image forming apparatus according to any of the fifteenth to seventeenth aspects of the invention, wherein the determining unit determines to perform the following control when the envelope determining unit determines that the recording medium is an envelope and when the basis weight of the envelope acquired by the basis weight acquiring unit is lower than a predetermined value: the recording medium is not bent between the position where the image is transferred to the recording medium and the fixing roller.

An invention according to a nineteenth aspect is the image forming apparatus according to any of the fifteenth to eighteenth aspects, wherein the determining unit changes the fixing temperature of the fixing roller in accordance with the basis weight of the envelope acquired by the basis weight acquiring unit when the envelope determining unit determines that the recording medium is an envelope.

An invention according to a twentieth aspect is the image forming apparatus according to the nineteenth aspect, wherein the determining unit lowers the fixing temperature of the fixing roller below a normal fixing temperature when the basis weight of the envelope acquired by the basis weight acquiring unit is lower than a predetermined value.

A twenty-first invention is characterized in that, in the image forming apparatus according to any one of the fifteenth to the twentieth inventions, the determining means changes the pressing force of the fixing roller in accordance with the basis weight of the envelope acquired by the basis weight acquiring means when the envelope determining means determines that the recording medium is an envelope.

An invention according to a twenty-second aspect is the image forming apparatus according to the twenty-first aspect, wherein the determining unit makes the pressure contact force of the fixing roller weaker than a normal pressure contact force when the basis weight of the envelope acquired by the basis weight acquiring unit is lower than a predetermined value.

A twenty-third aspect of the present invention is the image forming apparatus according to any one of the first to twenty-second aspects, further comprising a communication unit that communicates with an external apparatus, wherein the basis weight acquisition unit is capable of acquiring the basis weight of the recording medium from the external apparatus via the communication unit.

An invention according to a twenty-fourth aspect is the image forming apparatus according to the twenty-third aspect, wherein the envelope determination unit is configured to determine that the recording medium is an envelope when it is designated from the external apparatus via the communication unit that the recording medium is an envelope.

A twenty-fifth aspect of the present invention provides a control method for an image forming apparatus including an image forming unit that forms and outputs an image on a recording medium conveyed along a predetermined conveyance path, the control method comprising: an envelope judging step of judging whether the recording medium is an envelope; a basis weight acquiring step of acquiring a basis weight of the recording medium; a determining step of determining control for forming an image on the recording medium based on the determination result in the envelope determining step and the basis weight obtained in the basis weight obtaining step; and a control step of controlling an operation of the image forming unit based on a determination result in the determination step.

According to the present invention, when it is determined that the recording medium is an envelope, image formation on the envelope can be performed by determining control according to the basis weight of the envelope. That is, even when an image is formed on either one of a thin envelope and a thick envelope, the image can be formed without causing wrinkles on the envelope, and the quality of a printed product can be prevented from being degraded.

Drawings

Fig. 1 is a diagram showing an example of an external configuration of an image forming apparatus.

Fig. 2 is a diagram showing an example of the internal structure of the image forming section.

Fig. 3 is a diagram showing a configuration example of an envelope detection sensor.

Fig. 4 is a diagram showing a configuration example of the basis weight detection sensor.

Fig. 5 is a diagram showing a configuration example of the bending detection sensor.

Fig. 6 is a block diagram showing a configuration example of a control mechanism of the image forming apparatus.

Fig. 7 is a diagram illustrating operations of the envelope detection sensor and the basis weight detection sensor.

Fig. 8 is a diagram illustrating a conveyance method of an envelope.

Fig. 9 is a diagram showing an example of the reference information.

Fig. 10 is a flowchart showing an example of a processing procedure performed by the controller.

Fig. 11 is a flowchart showing an example of a detailed processing procedure of the envelope control determination processing.

Fig. 12 is a diagram showing an example of an operation screen displayed on the operation panel.

Fig. 13 is a diagram showing a configuration example of an image forming apparatus according to a third embodiment.

Description of reference numerals: 1 … image forming apparatus; 2 … image forming section (image forming unit); 9 … recording medium; 12 … fixing part; 33 … conveying path; 40 … envelope detection sensors (envelope detection unit, flap detection unit); a 50 … basis weight detection sensor (basis weight detection unit); 60 … bend detection sensor; 81 … envelope judging section (envelope judging means); 82 … basis weight acquisition section (basis weight acquisition unit); 83 … determination unit (determination means); 84 … print control section (control unit).

Detailed Description

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the embodiments described below, the same reference numerals are assigned to the elements that are common to each other, and overlapping description thereof will be omitted.

(first embodiment)

Fig. 1 is a diagram showing an image forming apparatus 1 according to an embodiment of the present invention. The image forming apparatus 1 shown in fig. 1 is configured as, for example, an mfp (multifunction peripherals) having a plurality of functions such as a copy function, a scan function, and a print function. Focusing on the printing function, the image forming apparatus 1 is a type of apparatus that performs image formation in an electrophotographic system and is an apparatus capable of forming a color image in a tandem system. The image forming apparatus 1 includes an image forming unit 2 at a center portion of an apparatus main body. The image forming section 2 includes a paper feed tray 3 in a lower portion thereof, and can accommodate a recording medium such as a sheet or an envelope in the paper feed tray 3. The image forming unit 2 includes an openable and closable manual feed tray 4 on a side surface of the apparatus main body. The image forming apparatus 1 feeds a recording medium placed on the paper feed tray 3 or the manual feed tray 4 one by one, forms an image on the recording medium, and discharges the recording medium to the paper discharge tray 5 provided at the upper portion.

The image forming apparatus 1 includes an image reading unit 6 on an upper portion of the apparatus main body. For example, when the copy function or the scan function is selected, the image reading unit 6 reads an image of a document. That is, the image reading section 6 optically reads a document set by a user and generates image data.

The image forming apparatus 1 further includes an operation panel 7 serving as a user interface on the front side of the apparatus main body. The image forming apparatus 1 displays various operation screens that can be operated by the user on the operation panel 7, and receives the operation by the user.

Fig. 2 is a diagram showing an example of the internal structure of the image forming unit 2 in the image forming apparatus 1. Fig. 2 shows a state where the manual feed tray 4 is opened. As shown in fig. 2, a plurality of recording media 9 can be accommodated in the paper feed tray 3. Further, a plurality of recording media 9 may be placed on the manual feed tray 4. The image forming unit 2 is configured to: the recording medium 9 stored in the paper feed tray 3 or the recording medium 9 placed on the manual feed tray 4 is conveyed, and when the recording medium 9 passes through a predetermined position, an image is formed on the recording medium 9, and the image is fixed and discharged to the paper discharge tray 5. As the recording medium 9, a sheet such as printing paper can be used. The envelope 15 can also be used as the recording medium 9.

The image forming apparatus 1 includes a controller 8 that controls an image forming operation in a unified manner inside the apparatus main body. The controller 8 controls operations of the respective units provided in the image forming unit 2, thereby controlling an image forming operation on the recording medium 9.

The image forming unit 2 includes: an image forming unit 10 that forms an image and transfers the image to a recording medium 9; a transport mechanism 11 for transporting the recording medium 9; and a fixing unit 12 for fixing the image transferred to the recording medium 9.

The image forming unit 10 includes: a plurality of toner image generating units 20 provided to generate toner images of respective color components of Y (yellow), M (magenta), C (cyan), and K (black); a plurality of exposure portions 21 for exposing the image carriers (photosensitive drums) provided in the respective toner image generating portions 20; an intermediate transfer belt 22 that primarily transfers the toner image generated in the toner image generating section 20; and a secondary transfer roller 23 for secondary-transferring the toner image primarily transferred to the intermediate transfer belt 22 to the recording medium 9.

The image forming unit 10 forms electrostatic latent images corresponding to respective color components on the image carrier of each toner image generating portion 20 by driving the plurality of toner image generating portions 20 and the plurality of exposure portions 21 based on image data to be printed, and generates toner images on the surfaces of the image carrier by developing the electrostatic latent images with the toners of the respective color components. The image forming unit 10 sequentially primarily transfers the toner images of the respective color components generated by the respective plural toner image generating portions 20 to the intermediate transfer belt 22 that is circularly moved in the direction of the arrow F1, thereby generating a color image on the surface of the intermediate transfer belt 22 with the toners of the respective color components superimposed thereon. The image forming unit 10 secondarily transfers the color image to the surface of the recording medium 9 conveyed by the conveying mechanism 11 when the color image on the intermediate transfer belt 22 passes through the position of the secondary transfer roller 23.

When the image data to be printed is a monochrome image, the image forming unit 10 operates only the toner image generating portion 20 corresponding to the K color. In this case, the image forming unit 10 secondarily transfers the monochrome image to the recording medium 9 when the recording medium 9 passes the position of the secondary transfer roller 23 after primarily transferring the monochrome image to the intermediate transfer belt 22.

The transport mechanism 11 feeds the recording medium 9 from either the paper feed tray or the manual feed tray 4, and transports the recording medium 9 along the predetermined transport path 33 in the direction of arrow F2. The conveyance mechanism 11 includes: a pickup roller 31a that feeds out the recording medium 9 from the paper feed tray 3 toward the conveyance path 33; and a paper feed roller 32a for feeding the recording medium 9 fed by the pickup roller 31a to the conveyance path 33. The paper feed roller 32a has a function of feeding only the uppermost 1 recording medium 9 to the downstream conveyance path 33 when a plurality of recording media 9 are fed by the pickup roller 31 a. Further, the conveying mechanism 11 includes: a pickup roller 31b for feeding the recording medium 9 from the manual tray 4 toward the conveyance path 33; and a paper feed roller 32b for feeding the recording medium 9 fed by the pickup roller 31b to the conveyance path 33. The paper feed roller 32b has a function of feeding only the uppermost 1 recording medium 9 to the downstream conveyance path 33 when a plurality of recording media 9 are fed by the pickup roller 31 b.

The conveying mechanism 11 includes a registration roller 34 on the upstream side of the secondary transfer roller 23. The registration rollers 34 temporarily stop the conveyance of the recording medium 9 in a state where the leading ends of the recording medium 9 fed by the feed rollers 32a and 32b are aligned. The registration roller 34 feeds the recording medium 9 to the position of the secondary transfer roller 23 at an estimated timing at which the image (color image or monochrome image) formed on the intermediate transfer belt 22 by the image forming unit 10 moves to the position of the secondary transfer roller 23.

The transport mechanism 11 further includes a discharge roller 37, and the discharge roller 37 discharges the recording medium 9 on which the fixing process of the image is performed in the fixing unit 12 onto the discharge tray 5. The discharge roller 37 discharges the recording medium 9 on which the image is formed from the discharge port 38 onto the discharge tray 5.

The fixing unit 12 is provided downstream of the position of the secondary transfer roller 23 where the image is secondarily transferred to the recording medium 9. The fixing unit 12 performs a fixing process for fixing the image transferred to the recording medium 9. The fixing unit 12 includes a pair of fixing rollers 35 and 36. One fixing roller 35 of the pair of fixing rollers 35 and 36 is a roller heated by a heater described later, and performs a heat treatment on the recording medium 9. The other fixing roller 36 is disposed opposite to the fixing roller 35, and is pressed against the surface of the fixing roller 35 to apply pressure treatment to the recording medium 9. The pressure contact force of the fixing roller 36 with respect to the fixing roller 35 can be adjusted. In this way, the fixing unit 12 applies heat treatment and pressure treatment when the recording medium 9 passes through the nip portion between the pair of fixing rollers 35 and 36, thereby fixing the image to the recording medium 9.

The image forming apparatus 1 further includes an envelope detection sensor 40, a basis weight detection sensor 50, and a loop detection sensor 60 in the conveyance path 33 for conveying the recording medium 9.

The envelope detection sensor 40 is a sensor that is provided between the paper feed rollers 32a and 32b and the registration roller 34 in the conveyance path 33 and detects whether or not the recording medium 9 fed by the paper feed rollers 32a and 32b is an envelope 15.

Fig. 3 is a diagram showing a configuration example of the envelope detection sensor 40. The envelope detection sensor 40 is constituted by an ultrasonic sensor, for example. As shown in fig. 3 (a), the envelope detection sensor 40 includes an ultrasonic wave transmitting unit 41 and an ultrasonic wave receiving unit 42 which are provided at positions facing each other across the conveyance path 33 of the recording medium 9. The ultrasonic wave transmitter 41 transmits an ultrasonic wave of a predetermined frequency to the ultrasonic wave receiver 42. When the recording medium 9 conveyed along the conveying path 33 is an envelope 15, a hollow portion 16 is provided inside a portion where 2 sheets overlap. Therefore, the ultrasonic wave transmitted from the ultrasonic wave transmitting unit 41 is attenuated in the hollow portion 16 of the envelope 15, and is received by the ultrasonic wave receiving unit 42. In contrast, when the recording medium 9 is not an envelope 15 but 1 sheet, the attenuation amount of the ultrasonic wave transmitted from the ultrasonic wave transmitting unit 41 is smaller than that of the envelope 15. Therefore, the envelope detection sensor 40 can detect whether the recording medium 9 is an envelope 15 by detecting whether the attenuation amount of the ultrasonic wave emitted from the ultrasonic wave transmission unit 41 is equal to or greater than a predetermined value.

Fig. 3 (b) shows a detailed configuration example of the envelope detection sensor 40. The ultrasonic transmission unit 41 includes a drive circuit 43 and a transmission element 44. The drive circuit 43 drives the transmission element 44 to cause the transmission element 44 to transmit ultrasonic waves of a predetermined frequency (for example, 300 kHz). The ultrasonic wave is received by the ultrasonic wave receiving unit 42 via the recording medium 9 conveyed through the conveying path 33.

The ultrasonic receiving unit 42 includes a receiving element 45, a resonance circuit 46, an amplification circuit 47, and a rectification circuit 48. The receiving element 45 is an element that receives ultrasonic waves, and outputs an electric signal corresponding to the received ultrasonic waves. The resonance circuit 46 applies filtering of a predetermined frequency (for example, 300kHz) to the electric signal output from the receiving element 45, and extracts a signal component of the ultrasonic wave transmitted from the ultrasonic wave transmitting unit 41. The amplifier circuit 47 amplifies the signal component of the ultrasonic wave and outputs the amplified signal component to the rectifier circuit 48. The rectifier circuit 48 rectifies the amplified signal, thereby generating and outputting an analog voltage signal corresponding to the intensity of the ultrasonic wave received by the receiver 45. The analog voltage signal has a value smaller than a predetermined value if the recording medium 9 is an envelope 15, and has a value equal to or larger than the predetermined value if the recording medium 9 is not the envelope 15. Therefore, the analog voltage signal output from the rectifier circuit 48 is a signal indicating whether or not the recording medium 9 is an envelope 15.

The envelope detection sensor 40 also functions as a flap detection unit that detects a flap portion of the envelope 15 when the recording medium 9 is the envelope 15. The envelope 15 has a portion where 2 sheets overlap and a tongue portion where 2 sheets do not overlap. When the tongue-sealing portion is located on the front end side or the rear end side in the conveyance direction of the recording medium 9, the envelope detection sensor 40 can detect the tongue-sealing portion in front of or behind a portion where 2 sheets overlap.

The basis weight detection sensor 50 is a sensor that is provided between the paper feed rollers 32a and 32b and the registration roller 34 in the conveyance path 33 and detects the basis weight of the recording medium 9 fed by the paper feed rollers 32a and 32 b. The basis weight detection sensor 50 of the present embodiment is provided on the downstream side of the envelope detection sensor 40 in the conveyance path 33.

Fig. 4 is a diagram showing a configuration example of the basis weight detection sensor 50. The basis weight detection sensor 50 includes a light-transmitting sensor and a light-reflecting sensor. That is, the basis weight detection sensor 50 includes a first light source 51 that irradiates the first light toward the conveyance path 33, a second light source 52 that irradiates the second light toward the conveyance path 33, and a light receiving element 53. The first light source 51 is a light source of a light reflection type sensor. The second light source 52 is a light source of a light transmission type sensor. The light receiving element 53 also serves as a light receiving element for both the light transmission sensor and the light reflection sensor.

The first light source 51 is disposed on the same side as the light receiving element 53 with respect to the conveyance path 33, and irradiates the conveyance path 33 with the first light. When the recording medium 9 passes through the irradiation region of the first light, the first light is reflected by the surface of the recording medium 9, and the reflected light is incident on the light receiving element 53 and is detected.

The second light source 52 is disposed on the opposite side of the first light source 51 and the light receiving element 53 with respect to the conveyance path 33, and irradiates the conveyance path 33 with the second light. When the recording medium 9 passes through the irradiation region of the second light, the second light passes through the recording medium 9, and the light passing through is detected by the light receiving element 53.

The basis weight (weight per unit area) of the recording medium 9 varies depending on the thickness of the recording medium 9. Therefore, the larger the basis weight of the recording medium 9 is, the smaller the transmission amount of the light emitted from the second light source 52 is. The transmission amount of light emitted from the second light source 52 also changes according to the color tone of the recording medium 9. Therefore, the basis weight detection sensor 50 detects the basis weight of the recording medium 9 by measuring the transmitted light amount of the light irradiated from the second light source 52, and detects the color tone of the recording medium 9 by measuring the reflected light of the light irradiated from the first light source 51. The basis weight detection sensor 50 corrects the basis weight based on the amount of transmitted light in accordance with the color tone of the recording medium 9, thereby detecting the basis weight of the recording medium 9 from which the influence of the color tone is excluded.

Next, the loop detection sensor 60 is disposed between the position where the image is secondarily transferred to the recording medium 9 and the fixing rollers 35, 36. The curvature detection sensor 60 is a sensor that detects the curvature of the recording medium 9 formed by the bending of the recording medium 9 between the position of the secondary transfer roller 23 and the fixing rollers 35 and 36.

Fig. 5 is a diagram showing a configuration example of the bending detection sensor 60. In a case where no curve is formed in the recording medium 9 between the position of the secondary transfer roller 23 and the fixing rollers 35, 36, the recording medium 9 passes through a path L1 indicated by a broken line in the figure. In contrast, when the recording medium 9 is bent between the position of the secondary transfer roller 23 and the fixing rollers 35 and 36, the recording medium 9 passes through a path L2 indicated by a solid line in the figure. The bending detection sensor 60 can detect the magnitude of the bending. The curvature of the recording medium 9 is formed only in one direction in which the curvature detection sensor 60 is disposed. For example, the warp detection sensor 60 is configured to include an actuator 61 that is displaced while coming into contact with a warp of the recording medium 9 as the warp is formed, and to detect the size of the warp of the recording medium 9 based on the position of the actuator 61.

Next, a control mechanism in the image forming apparatus 1 will be explained. Fig. 6 is a block diagram showing an example of a control mechanism of the image forming apparatus 1. As shown in fig. 6, the image forming apparatus 1 is configured such that the controller 8 controls the operation of the image forming section 2 described above. The controller 8 includes a CPU70 and a memory 71, and the CPU70 operates the image forming unit 2 by reading and executing the program 78 stored in the memory 71. Further, the controller 8 is connected to the operation panel 7 and the communication unit 72.

The operation panel 7 includes a display unit 7a and an operation unit 7 b. The display unit 7a is configured by, for example, a color liquid crystal display, and displays various operation screens that can be operated by the user. The operation unit 7b is configured by a touch panel key or the like, and receives an operation by the user. The controller 8 can acquire information input by the user via the operation panel 7, and can also control the image forming unit 2 based on the information input by the user.

The communication unit 72 communicates with an external device via a network such as a LAN. For example, the controller 8 can acquire image data to be printed from an external apparatus via the communication unit 72. The controller 8 can also acquire information for controlling the image forming unit 2 via the communication unit 72.

The image forming section 2 includes a conveying roller driving section 73, a fixing roller driving section 74, a fixing roller pressing force adjusting section 75, and a heater 76.

The conveyance roller driving unit 73 is configured by, for example, a motor that rotationally drives various rollers for conveying the recording medium 9 along the conveyance path 33. The conveying roller driving portion 73 drives a plurality of rollers including the pickup rollers 31a and 31b, the paper feed rollers 32a and 32b, the registration roller 34, the secondary transfer roller 23, and the discharge roller 37. The driving force of the conveying roller driving unit 73 is transmitted to the various rollers via an electromagnetic clutch. Therefore, for example, the drive of the registration roller 34 is stopped at the timing when the leading end of the recording medium 9 reaches the registration roller 34, and the registration roller 34 is driven again at the timing when the image primarily transferred to the intermediate transfer belt 22 reaches the predetermined position, whereby the recording medium 9 can be supplied to the secondary transfer roller 23 at an appropriate timing.

The conveyance roller driving unit 73 sets a system speed designated by the controller 8 and drives various rollers when starting the paper feeding operation of the recording medium 9. The system speed is a conveyance speed when the recording medium 9 is conveyed along the conveyance path 33. After the recording medium 9 starts to be conveyed, the conveying roller driving unit 73 can instruct the controller 8 to change the system speed, and can change the conveying speed of the recording medium 9 according to the system speed. For example, the conveying roller driving section 73 can change the system speed in accordance with the thickness of the recording medium 9 detected by the controller 8.

The fixing roller driving section 74 is a driving section such as a motor for rotationally driving the fixing rollers 35 and 36. That is, the fixing rollers 35 and 36 are rotationally driven by a drive source different from various rollers for conveying the recording medium 9 along the conveying path 33. Therefore, the conveyance speed of the recording medium 9 by the fixing rollers 35 and 36 can be set to the same speed as the conveyance speed of the recording medium 9 by the various rollers or to a speed different from the conveyance speed of the recording medium 9 by the various rollers.

The fixing roller pressing force adjusting portion 75 adjusts the pressing force of the fixing roller 36 against the fixing roller 35 in the fixing portion 12. For example, the fixing roller pressing force adjusting portion 75 presses and biases the fixing roller 36 toward the fixing roller 35, and adjusts the pressing force to adjust the pressing force.

The heater 76 is a heat source that heats the fixing roller 35 of the fixing section 12. The heater 76 is driven by the controller 8, and heats the fixing roller 35 to maintain a predetermined fixing temperature. The fixing temperature differs depending on the type of the recording medium 9.

The controller 8 is configured to control the conveying roller driving section 73, the fixing roller driving section 74, the fixing roller pressing force adjusting section 75, and the heater 76 based on the detection results of the envelope detection sensor 40, the basis weight detection sensor 50, and the curl detection sensor 60 provided in the image forming section 2. Although not shown in fig. 6, the controller 8 naturally controls the operation of the image forming unit 10. The detailed configuration and operation of the controller 8 will be described below.

As shown in fig. 6, the CPU70 of the controller 8 functions as an envelope determination section 81, a basis weight acquisition section 82, a determination section 83, and a print control section 84 by executing the program 78.

The print control section 84 drives the image forming section 2 to control an image forming operation on the recording medium 9. The print control unit 84 starts a printing operation for driving the image forming unit 2 to form an image on the recording medium 9 when execution of a print job is instructed via the communication unit 72 or when execution of a print job is instructed via the operation panel 7. With the start of the printing operation, the print control unit 84 drives the transport roller drive unit 73 to feed the recording medium 9 from a tray designated by the user out of the paper feed tray 3 and the manual tray 4, and transports the recording medium 9 along the transport path 33. At this time, the print control unit 84 sets a system speed corresponding to the plain paper and starts the conveyance of the recording medium 9, assuming that the recording medium 9 is plain paper, for example. Further, the print control section 84 starts the operation of generating the toner image in the image forming unit 10 in accordance with the start of the conveyance of the recording medium 9. Then, the print control section 84 can appropriately change the control when forming an image on the recording medium 9 based on the determination result of the determination section 83.

The envelope determination section 81 is a processing section that determines whether or not the recording medium 9 conveyed in the conveyance path 33 is an envelope. When the print control section 84 starts the conveyance of the recording medium 9, the envelope determination section 81 operates as follows: the envelope detection sensor 40 is driven to detect whether the recording medium 9 is an envelope 15 when the recording medium 9 passes the position of the envelope detection sensor 40. The envelope determining section 81 acquires the detection result output from the envelope detection sensor 40, and determines whether or not the recording medium 9 is an envelope based on the detection result.

The basis weight acquiring unit 82 is a processing unit that acquires the basis weight of the recording medium 9 conveyed in the conveying path 33. When the print control section 84 starts the conveyance of the recording medium 9, the basis weight acquiring section 82 operates as follows: the basis weight detection sensor 50 is driven to detect the basis weight of the recording medium 9 when the recording medium 9 passes through the position of the basis weight detection sensor 50. The basis weight acquisition unit 82 acquires the basis weight detection result output from the basis weight detection sensor 50. For example, when the envelope determination section 81 determines that the recording medium 9 is an envelope 15, the basis weight acquisition section 82 acquires the basis weight of the envelope 15 detected by the basis weight detection sensor 50. When the envelope determination unit 81 determines that the recording medium 9 is not an envelope 15 but 1 sheet, the basis weight acquisition unit 82 acquires the basis weight of 1 sheet detected by the basis weight detection sensor 50.

When the recording medium 9 is an envelope 15, the basis weight detected by the basis weight detection sensor 50 at a portion where 2 sheets overlap is different from the basis weight detected at a tongue-out portion where 2 sheets do not overlap. This is because the transmitted light amount of the light emitted from the second light source 52 is reduced in the portion where 2 sheets overlap as compared with the tongue sealing portion, and the reflected light amount of the light emitted from the first light source 51 may be changed in the portion where 2 sheets overlap and the tongue sealing portion due to a slight difference in color tone. Therefore, the basis weight acquisition section 82 drives the basis weight detection sensor 50 so that the basis weight is detected at any one of the portion where 2 sheets overlap and the flap portion.

Fig. 7 is a diagram illustrating operations of the envelope detection sensor 40 and the basis weight detection sensor 50. The envelope detection sensor 40 is disposed upstream of the basis weight detection sensor 50 in the conveyance path 33 for conveying the recording medium 9. Therefore, as shown in fig. 7 (a), the recording medium 9 conveyed in the direction of the arrow F2 along the conveying path 33 passes first through the position of the envelope detection sensor 40 and then through the position of the basis weight detection sensor 50. The conveying speed of the recording medium 9 is known, and the distance between the envelope detection sensor 40 and the basis weight detection sensor 50 is also known. Therefore, the timing at which the same portion as the portion detected by the envelope detection sensor 40 passes through the position of the basis weight detection sensor 50 can be predicted. For example, as shown in fig. 7 (b), when the envelope detection sensor 40 detects a portion 17 where 2 sheets of the envelope 15 overlap, the same portion 17 as that portion passes through the position of the basis weight detection sensor 50 after a predetermined time has elapsed. Therefore, the basis weight acquiring unit 82 can detect the basis weight of the portion 17 of the envelope 15 where 2 sheets overlap, as shown in fig. 7 (c), by causing the basis weight detecting sensor 50 to perform the operation of detecting the basis weight after a predetermined time has elapsed since the envelope detecting sensor 40 detected the portion 17 of the envelope 15 where 2 sheets overlap.

As shown in fig. 7 (c), when the envelope detection sensor 40 detects the flap 18 of the envelope 15, the flap 18 passes through the position of the basis weight detection sensor 50 after a predetermined time has elapsed. Therefore, the basis weight acquiring section 82 can detect the basis weight of the flap portion 18 of the envelope 15 as shown in fig. 7 (d) by causing the basis weight detecting sensor 50 to perform the basis weight detecting operation after a predetermined time has elapsed from the detection of the flap portion 18 of the envelope 15 by the envelope detecting sensor 40.

The basis weight detection sensor 50 can detect the basis weight in the same manner as in the case where the recording medium 9 is 1 sheet when detecting the basis weight of the flap portion 18 of the envelope 15. However, when the basis weight detection sensor 50 detects the basis weight of the portion 17 of the envelope 15 where 2 sheets overlap, a decrease in the amount of transmitted light of the light irradiated from the second light source 52 and a change in the amount of reflected light of the light irradiated from the first light source 51 occur, and therefore the basis weight may not be detected appropriately. Therefore, the basis weight acquiring unit 82 preferably detects the basis weight by a method different from the basis weight detecting method in the case where the recording medium 9 is 1 sheet, when the basis weight of the portion 17 where 2 sheets of the envelope 15 overlap is detected by the basis weight detecting sensor 50. That is, the basis weight acquiring section 82 sets the method of detecting the basis weight of the basis weight detecting sensor 50 to the first method when the envelope judging section 81 judges that the recording medium 9 is not an envelope 15, and the basis weight acquiring section 82 sets the method of detecting the basis weight of the basis weight detecting sensor 50 to the second method different from the first method when the envelope judging section 81 judges that the recording medium 9 is an envelope 15. Specifically, when the envelope determination unit 81 determines that the recording medium 9 is an envelope 15, the basis weight acquisition unit 82 performs the basis weight detection by a second method of increasing the light quantity or sensitivity of the light transmission sensor or the light reflection sensor in the basis weight detection sensor 50, as compared with the first method when the recording medium 9 is determined not to be an envelope 15. This reduces the influence of a decrease in the amount of transmitted light of the light emitted from the second light source 52 and a change in the amount of reflected light of the light emitted from the first light source 51, and thus the basis weight of the envelope 15 can be appropriately detected.

In addition, when the basis weight detection sensor 50 detects the basis weight of the flap portion 18 of the envelope 15, it is not necessary to switch the method of detecting the basis weight as described above, and therefore the processing load of the controller 8 is reduced. However, when the recording medium 9 is an envelope 15, it is assumed that it is difficult to detect the basis weight in the flap 18 because of the type or direction of the envelope 15 conveyed in the conveyance path 33. Fig. 8 is a diagram illustrating a plurality of kinds of envelopes 15 conveyed in the conveying direction F2. For example, as shown in fig. 8 (a), when the tongue 18 of the envelope 15 is positioned on the rear end side in the conveyance direction F2, the tongue 18 always passes through the detection position of the basis weight detection sensor 50. Therefore, when the envelope 15 is conveyed in the direction shown in fig. 8 (a), the basis weight detection sensor 50 can detect the basis weight of the flap portion 18 of the envelope 15. Similarly, when the flap portion 18 of the envelope 15 is positioned on the leading end side in the conveyance direction F2, the flap portion 18 always passes through the detection position of the basis weight detection sensor 50, and therefore the basis weight detection sensor 50 can detect the basis weight of the flap portion 18 of the envelope 15.

On the other hand, as shown in fig. 8 (b), when the flap 18 of the envelope 15 is located at the end in the direction orthogonal to the conveying direction F2, the flap 18 does not necessarily pass through the detection position of the basis weight detection sensor 50. Therefore, when the envelope 15 is conveyed in the direction shown in fig. 8 (b), the basis weight detection sensor 50 may not detect the basis weight of the flap portion 18 of the envelope 15. In such a case, the envelope detection sensor 40 cannot detect the flap portion 18 of the envelope 15, and therefore the basis weight acquisition section 82 preferably causes the basis weight detection sensor 50 to detect the basis weight of the portion 17 of the envelope 15 where 2 sheets overlap.

Next, the determination unit 83 is a processing unit that determines control when forming an image on the recording medium 9 based on the determination result of the envelope determination unit 81 and the basis weight acquired by the basis weight acquisition unit 82. The determination unit 83 reads the reference information 79 stored in the memory 71 in advance, and determines control based on the reference information 79.

Fig. 9 is a diagram showing an example of the reference information 79. The reference information 79 is information in which a system speed Vs, a fixing roller speed Vt, the presence or absence of the loop control, a fixing temperature T, and a fixing roller pressing force FP are defined in advance for each type of the recording medium 9.

For example, in the case where the recording medium 9 is a sheet and the sheet is plain paper, the first velocity V1 is defined as the system velocity Vs in the reference information 79. The first speed V1 is, for example, 200 mm/s. Further, it is defined that the fixing roller speed Vt is set to a speed equal to the system speed Vs, the curve control is "present", the fixing temperature T is set to the first temperature T1, and the fixing roller pressing force FP is set to the first pressing force FP 1. The curl control is control for feeding the recording medium 9 to the fixing unit 12 in a state where the curl of the recording medium 9 is formed on the upstream side of the fixing unit 12. The first temperature T1 is, for example, 170 ℃. The first pressure contact force FP1 is a standard pressure contact force (normal pressure contact force) when an image is formed on the recording medium 9 in the image forming apparatus 1.

In the case where the recording medium 9 is a sheet and the sheet is a thin paper, the first velocity V1 is defined as the system velocity Vs in the reference information 79 in the same manner as in the case of plain paper. Further, it is defined that the fixing roller speed Vt is set to a speed equal to the system speed Vs, the curve control is "present", the fixing temperature T is set to the second temperature T2, and the fixing roller pressing force FP is set to the second pressing force FP 2. The second temperature T2 is, for example, 150 ℃. In addition, the second crimping force FP2 is a crimping force smaller than the first crimping force FP 1. That is, in the case of thin paper, since it is thinner than plain paper, the fixing temperature T can be lowered and the pressure contact force FP of the fixing roller 36 can also be reduced.

In the case where the recording medium 9 is a sheet and the sheet is thick paper, the reference information 79 defines a second speed V2 lower than the first speed V1 as the system speed Vs. Further, it is defined that the fixing roller speed Vt is set to a speed equal to the system speed Vs, the curve control is "present", the fixing temperature T is set to the second temperature T2, and the fixing roller pressing force FP is set to the third pressing force FP 3. The second speed V2 is, for example, 100 mm/s. In addition, the third crimping force FP3 is a crimping force larger than the first crimping force FP 1. That is, in the case of thick paper, the system speed Vs is reduced to properly transfer the image to the sheet, so the fixing temperature T can be reduced as in the case of thin paper. However, in order to appropriately fix the image to the thick paper, the pressure contact force FP of the fixing roller 36 is preferably made larger than the normal pressure contact force.

On the other hand, when the recording medium 9 is an envelope 15 and is a thin envelope, the first velocity V1 is defined as the system velocity Vs in the reference information 79. Further, a speed at which the fixing roller speed Vt is about several percent faster than the system speed Vs, a bend control is set to none, the fixing temperature T is set to a temperature lower than the first temperature T1, and the fixing roller pressing force FP is set to a pressing force smaller than the first pressing force FP1 are defined.

In the case of a thin envelope, if a bend is formed on the upstream side of the fixing unit 12, wrinkles are likely to be generated when the envelope passes through the fixing unit 12. In particular, if the thin envelope is distorted, wrinkles are conspicuously generated. This phenomenon is caused by the fixing portion 12 directly fixing the envelope 15 by the deflection generated at the portion 17 where 2 sheets overlap. Therefore, in the case of a thin envelope, it is defined that the conveyance speed (fixing roller speed Vt) of the fixing rollers 35 and 36 is set to a slightly higher speed than the system speed Vs so that no curve is formed on the upstream side of the fixing portion 12. However, if the fixing rollers 35 and 36 pull the thin envelope excessively, the image secondarily transferred to the thin envelope by the secondary transfer roller 23 may be disturbed, and therefore, the speed difference between the fixing roller speed Vt and the system speed Vs is preferably suppressed to several% or less. Further, if no curve is formed on the upstream side of the fixing section 12, the fixing roller speed Vt may be set to a speed equal to the system speed Vs.

In addition, since the thin envelope is thicker than the thin paper, the fixing temperature T is higher as compared with the case of the thin paper. However, the fixing roller pressing force FP may be the same pressing force as in the case of thin paper.

When the recording medium 9 is an envelope 15 and is a thick envelope, the reference information 79 defines the second speed V2 as the system speed Vs. Further, it is defined that the fixing roller speed Vt is set to a speed equal to the system speed Vs, the curve control is "present", the fixing temperature T is set to a temperature lower than the first temperature T1, and the fixing roller pressing force FP is set to the same normal pressing force as the first pressing force FP 1.

In the case of a thick envelope, the system speed Vs is reduced to appropriately transfer the image to the sheet, and therefore the fixing temperature T can be reduced as in the case of a thin envelope. However, the fixing temperature T in the case of a thick envelope may be lower than the fixing temperature T in the case of a thin envelope. In order to appropriately fix the image to the thick envelope, the pressure contact force FP of the fixing roller 36 is preferably larger than that of the thin envelope, and is therefore defined to be the same as the normal pressure contact force.

In the example of fig. 9, only two types of envelopes, namely, a thin envelope and a thick envelope, are shown as an example of the envelope 15, but reference information 79 in which specific control contents are defined for 3 or more types of envelopes depending on the thickness of the envelope 15 may be used.

The determination unit 83 determines control for forming an image on the recording medium 9 based on the reference information 79. For example, when the envelope determination section 81 determines that the recording medium 9 is an envelope 15, the determination section 83 determines the thickness of the envelope 15 based on the basis weight of the envelope 15 acquired by the basis weight acquisition section 82, and determines whether the envelope 15 is a thin envelope or a thick envelope. As a result, in the case of a thin envelope, the determination unit 83 determines the system speed Vs, the fixing roller speed Vt, the loop control "none", the fixing temperature T, and the fixing roller pressure FP suitable for the thin envelope by referring to the field of the thin envelope of the reference information 79. When it is determined that the envelope is a thick envelope, the determination unit 83 refers to the field of the thick envelope in the reference information 79, and determines the system speed Vs, the fixing roller speed Vt, the curl control "present", the fixing temperature T, and the fixing roller pressure FP which are suitable for the thick envelope. Then, the determination unit 83 outputs the determination result to the print control unit 84.

In addition, when the envelope determination section 81 determines that the recording medium 9 is 1 sheet, the determination section 83 determines control corresponding to the type of sheet based on the reference information 79 and notifies the print control section 84 of the determined control.

The determination by the determination unit 83 is performed at the latest before the leading end of the recording medium 9 is fed to the downstream side of the registration roller 34. That is, the determination unit 83 determines the control after the end of the recording medium 9 reaches the registration rollers 34, or the end of the recording medium 9 reaches the registration rollers 34 and the conveyance of the recording medium 9 by the registration rollers 34 is temporarily stopped.

The print control section 84 stops the conveyance of the recording medium 9 temporarily at a timing when the leading end of the recording medium 9 reaches the registration roller 34 after the conveyance of the recording medium 9 is started. Then, the print control section 84 again drives the registration roller 34 to feed the leading end of the recording medium 9 toward the secondary transfer roller 23, with an estimation of the timing at which the image primarily transferred to the intermediate transfer belt 22 in the image forming unit 10 reaches the position of the secondary transfer roller 23. At this time, the print control section 84 performs control reflecting the determination result of the determination section 83. For example, when the determination unit 83 determines to decrease the system speed Vs, the print control unit 84 decreases the system speed Vs and decreases the transport speed of the recording medium 9 when the registration rollers 34 are driven again. The print control unit 84 sets the transport speed of the fixing rollers 35 and 36 to the recording medium 9 to the fixing roller speed Vt determined by the determination unit 83, and rotationally drives the fixing rollers 35 and 36. The print control section 84 performs control of forming the loop of the recording medium 9 on the upstream side of the fixing section 12 and control of not forming the loop, based on the presence or absence of the loop control determined by the determination section 83. For example, in the case of a thin envelope, since the bend control is determined to be "none", the print control section 84 performs speed adjustment of the system speed Vs and the fixing roller speed Vt so that the bend detection sensor 60 cannot detect the bend of the recording medium 9. The print control unit 84 drives the heater 76 to set the fixing temperature T of the fixing unit 12 to the temperature determined by the determination unit 83, and drives the fixing roller pressing force adjustment unit 75 to adjust the pressing force of the fixing roller 36 to the value determined by the determination unit 83.

For example, when the recording medium 9 is an envelope 15, the print control section 84 can switch control when the envelope 15 performs image formation, according to the thickness of the envelope 15. In other words, the print control section 84 controls to select an optimum control parameter corresponding to the thickness of the envelope 15 to perform image formation on the envelope 15. Therefore, when the thick envelope passes through the fixing section 12, image formation suitable for the thick envelope is performed in a state where the first control parameter suitable for the thick envelope is applied, whereas when the thin envelope passes through the fixing section 12, image formation suitable for the thin envelope is performed in a state where the second control parameter suitable for the thin envelope is applied, and the control parameter different from that in the case of the thick envelope. Therefore, in the image forming apparatus 1 of the present embodiment, even when an image is formed on an envelope 15 having a small thickness as the recording medium 9, for example, wrinkles are prevented from occurring in the envelope 15, and a reduction in the quality of a printed product can be prevented.

Next, fig. 10 is a flowchart showing an example of a processing procedure performed by the controller 8. This processing is processing performed by the CPU70 executing the program 78. In addition, this processing is processing started when the user instructs execution of a print job.

When this processing is started, the controller 8 starts execution of the print job (step S1). Along with this, the controller 8 sets the system speed Vs to the first speed V1 (step S2). That is, since it is not known at this point of time whether or not the recording medium 9 is an envelope 15, the controller 8 sets the system speed Vs to the first speed V1 on the assumption that the recording medium 9 is plain paper. Then, the controller 8 starts an operation of feeding and conveying the recording medium 9 from one of the paper feed tray 3 and the manual feed tray 4 to the conveyance path 33 by driving the conveyance roller driving portion 73 (step S3).

When the conveyance of the recording medium 9 is started, the controller 8 determines whether or not the envelope detection sensor 40 detects the recording medium 9 (step S4). If the envelope detection sensor 40 detects the recording medium 9 (yes in step S4), the controller 8 determines whether the recording medium 9 is an envelope 15 based on the detection result of the envelope detection sensor 40 (step S5).

If the recording medium 9 is the envelope 15 (yes in step S5), the controller 8 sets the second method as the detection method of the basis weight detection sensor 50 (step S6). For example, as described above, the controller 8 sets the envelope 15 in a state in which the basis weight can be detected in the portion 17 where 2 sheets of the envelope 15 overlap by increasing the light amount of the first light source 51 and the second light source 52 to be higher than the normal light amount (light amount when the basis weight of 1 sheet is detected) or increasing the sensitivity of the light receiving element 53 to be higher than the normal sensitivity (sensitivity when the basis weight of 1 sheet is detected). Then, the controller 8 drives the basis weight detection sensor 50 to acquire the basis weight of the envelope 15 from the basis weight detection sensor 50 (step S7). If the basis weight of the envelope 15 can be acquired, the controller 8 executes an envelope control determination process (step S8).

Fig. 11 is a flowchart showing an example of a detailed processing procedure of the envelope control determination processing (step S8). When the controller 8 starts this processing, it determines whether or not the basis weight of the envelope 15 detected by the basis weight detection sensor 50 is equal to or greater than a predetermined value (step S20). As a result, when the basis weight of the envelope 15 is equal to or greater than the predetermined value (yes in step S20), the controller 8 determines that the envelope is a thick envelope (step S21). If it is determined that the packet is a thick packet, the controller 8 sets the change system speed Vs based on the reference information 79 (step S22). Then, the controller 8 changes the setting of the fixing roller speed Vt based on the reference information 79 (step S23), and also changes the setting of the fixing temperature T (step S24).

On the other hand, if the basis weight of the envelope 15 is smaller than the predetermined value (no in step S20), the controller 8 determines that it is a thin envelope (step S25). If it is determined that the envelope is thin, the controller 8 sets and changes the fixing roller speed Vt based on the reference information 79 (step S26). That is, when the basis weight of the envelope 15 is less than the predetermined value, the controller 8 makes the conveyance speed of the envelope 15 by the fixing rollers 35 and 36 higher than the normal conveyance speed (first speed v 1). Further, the controller 8 changes the setting so that the bending control is not performed (step S27). Further, the controller 8 changes the setting of the fixing temperature T based on the reference information 79 (step S28). That is, when the basis weight of the envelope 15 is less than the predetermined value, the controller 8 sets the fixing temperature T of the fixing roller 35 to a temperature lower than the normal fixing temperature (first temperature T1). Further, the controller 8 changes the setting of the pressing force of the fixing roller 36 (step S29). That is, when the basis weight of the envelope 15 is less than the predetermined value, the controller 8 sets the pressing force FP of the fixing roller 36 to a force weaker than the normal pressing force (first pressing force FP 1). The envelope control determination process is thus ended.

Returning to the flowchart of fig. 10, the controller 8 switches the control of the subsequent image forming operation to the control determined in the envelope control determination process (step S8) (step S9). Then, the controller 8 applies the switched control to control the subsequent image forming operation. Thus, if the recording medium 9 is an envelope 15, control according to the thickness of the envelope 15 can be performed, and degradation of the quality of the printed product can be suppressed.

In addition, when the recording medium 9 is not an envelope 15 but 1 sheet (no in step S5), the controller 8 sets the first method as the detection method of the basis weight detection sensor 50 (step S10). For example, the controller 8 sets the light amounts of the first light source 51 and the second light source 52 to the normal light amounts, and sets the sensitivity of the light receiving element 53 to the normal sensitivity, thereby setting the state in which the basis weight of 1 sheet can be appropriately detected. Then, the controller 8 drives the basis weight detection sensor 50 to acquire the basis weight of the sheet from the basis weight detection sensor 50 (step S11). If the basis weight of the envelope 15 can be acquired, the controller 8 executes the sheet control determination process (step S12). The sheet control determination process is a process of determining control when forming an image on a sheet based on the reference information 79, as in the case of the envelope control determination process. When the sheet control determination process is performed, the controller 8 determines whether or not control for switching the image forming operation is necessary (step S13). When the execution of the print job is started, the setting is made on the assumption of plain paper as a default. Therefore, when the sheet is thin paper or thick paper other than plain paper, control needs to be switched. If it is determined that it is necessary to switch the control of the image forming operation (yes at step S13), the controller 8 switches the control of the subsequent image forming operation to the control determined in the sheet control determination process (step S12) (step S14). Then, the controller 8 applies the switched control to control the subsequent image forming operation. Thus, the image forming apparatus 1 performs image formation suitable for thin paper and thick paper.

On the other hand, if it is determined that the control for switching the image forming operation is not necessary (no in step S13), the controller 8 controls the subsequent image forming operation without switching the control for the image forming operation. Thereby, the image forming apparatus 1 performs image formation suitable for plain paper.

Then, the controller 8 stands by until the execution of the print job ends (step S15). When the execution of the print job is completed (yes in step S15), the controller 8 ends all the processing.

As described above, the image forming apparatus 1 of the present embodiment includes: an image forming section 2 for forming and outputting an image on the recording medium 9 conveyed along a predetermined conveyance path 33; an envelope judging section 81 for judging whether the recording medium 9 is an envelope 15; a basis weight acquiring unit 82 for acquiring the basis weight of the recording medium 9; a determination unit 83 for determining control for forming an image on the recording medium 9 based on the determination result of the envelope determination unit 81 and the basis weight acquired by the basis weight acquisition unit 82; and a print control section 84 for controlling the operation of the image forming section 2 based on the determination result of the determination section 83. Therefore, even when an image is formed using the envelope 15 as the recording medium 9, the image forming apparatus 1 can perform image formation with an optimum operation according to the basis weight of the envelope 15. Specifically, when a thick envelope is subjected to image formation, image formation can be performed with an optimum operation corresponding to the thick envelope, and when a thin envelope is subjected to image formation, image formation can be performed with an optimum operation corresponding to the thin envelope, and generation of wrinkles in the thin envelope can be suppressed, whereby a high-quality printed product can be output.

In the present embodiment, the case where the basis weight acquisition unit 82 causes the basis weight detection sensor 50 to detect the basis weight when it is determined that the recording medium 9 is the envelope 15 and when it is determined that the recording medium 9 is not the envelope 15 is exemplified. However, the basis weight acquiring unit 82 is not limited to this, and may cause the basis weight detecting sensor 50 to detect the basis weight of the envelope 15 only when the recording medium 9 is determined to be the envelope 15. When the recording medium 9 is the envelope 15, the basis weight of the envelope 15 is detected, and thus the image forming apparatus 1 can perform image formation in an optimum operation according to the basis weight of the envelope 15.

In the flowchart shown in fig. 10, a case is exemplified in which the method of detecting the basis weight of the basis weight detection sensor 50 is set to the first method when it is determined that the recording medium 9 is not an envelope 15, and the method of detecting the basis weight of the basis weight detection sensor 50 is set to the second method different from the first method when it is determined that the recording medium 9 is an envelope 15. However, this is processing assuming that the basis weight is detected at the portion 17 of the envelope 15 where 2 sheets overlap. On the other hand, if the basis weight detection sensor 50 is caused to detect the basis weight at the flap portion 18 of the envelope 15 when it is determined that the recording medium 9 is the envelope 15, it is not necessary to set the method for detecting the basis weight of the basis weight detection sensor 50 to the second method, and the basis weight may be detected by the first method similarly to the case where the recording medium 9 is a sheet. Therefore, the time required to switch the detection method of the basis weight detection sensor 50 can be omitted, and thus efficient processing can be achieved.

In addition, in the present embodiment, the following case is exemplified: the determination unit 83 determines a plurality of control parameters including the conveyance speed of the fixing rollers 35 and 36 for fixing the image to the recording medium 9, the presence or absence of the formation of a curve in the recording medium 9 between the position where the image is transferred to the recording medium 9 and the fixing rollers 35 and 36, the fixing temperature of the fixing roller 35, and the pressure contact force of the fixing roller 36, based on the determination result of the envelope determination unit 81 and the basis weight acquired by the basis weight acquisition unit 82. However, the present invention is not limited to this, and the determination unit 83 may determine at least one control parameter among the plurality of control parameters.

In the present embodiment, the basis weight detection sensor 50 includes a light-transmissive sensor and a light-reflective sensor. However, the basis weight of the recording medium 9 can be detected by only one of the light transmission sensor and the light reflection sensor. Therefore, the basis weight detection sensor 50 is not necessarily provided with both the light transmissive sensor and the light reflective sensor, and may be provided with only one of them.

(second embodiment)

Next, a second embodiment of the present invention will be explained. In the first embodiment described above, the following case is exemplified: the envelope determination section 81 determines whether or not the recording medium 9 is an envelope 15 based on the detection result of the envelope detection sensor 40, and the basis weight acquisition section 82 acquires the basis weight detected by the basis weight detection sensor 50. In contrast, in the present embodiment, a mode in which the user inputs information on the type of the recording medium 9 and the basis weight of the recording medium 9 into the operation panel 7 will be described. The configuration of the image forming apparatus 1 according to the present embodiment is the same as that described in the first embodiment.

In the present embodiment, the envelope determining section 81 and the basis weight acquiring section 82 function in the controller 8 before the image forming apparatus 1 starts execution of a print job. That is, when the user operates the operation panel 7 to perform a setting operation related to a print job, the envelope determining section 81 and the basis weight acquiring section 82 function separately. The controller 8 displays an operation screen on the operation panel 7, through which the user can input the type of the recording medium 9 and the basis weight of the recording medium 9.

Fig. 12 is a diagram showing an example of an operation screen displayed on the display unit 7a of the operation panel 7. Fig. 12 (a) shows a screen G1 for selecting the type of recording medium 9. For example, the envelope determination section 81 causes the display section 7a of the operation panel 7 to display a screen G1 shown in fig. 12 (a), and receives an operation by the user. On the screen G1, a plurality of buttons B1, B2, B3, and B4 corresponding to the type of the recording medium 9 are displayed. When the user performs a print job setting operation on the operation panel 7, the screen G1 is displayed, and one of the buttons B1 to B4 is selected and operated, whereby the type of the recording medium 9 can be specified to the image forming apparatus 1. Fig. 12 (a) illustrates a case where the user selects the button B4 of the envelope.

The envelope determination unit 81 of the present embodiment receives the user's selection operation on the screen G1 described above. When the user selects the envelope button B4 on the screen G1, the envelope determination unit 81 determines that the recording medium 9 is an envelope. Therefore, in the present embodiment, it is possible to determine whether the recording medium 9 is an envelope before execution of a print job is started in the image forming apparatus 1.

Fig. 12 (b) shows a screen G2 displayed when the user selects an envelope. Panel G2 is a panel that inputs the basis weight of the envelope. A basis weight display field R1 for displaying the basis weight of the envelope is provided on the screen G2, and a button group B5 for inputting a numerical value by the user is displayed at a position below the basis weight display field R1. When an envelope is selected as the recording medium 9, the user can manually input the basis weight of the envelope used for image formation by himself/herself by performing an operation on the screen G2.

The basis weight acquiring unit 82 of the present embodiment receives the user operation on the screen G2 described above. Further, the basis weight acquiring section 82 acquires the basis weight input to the screen G2 by the user as the basis weight of the envelope used in image formation. Therefore, in the present embodiment, the basis weight of the envelope can be acquired before the execution of the print job is started in the image forming apparatus 1.

However, it is sometimes difficult for the user to grasp the basis weight of the envelope used as the recording medium 9 by himself or herself. Therefore, instead of the screen G2 shown in fig. 12 (b), the controller 8 may cause the display unit 7a to display the screen G3 shown in fig. 12 (c). A screen G3 shown in fig. 12 c is a screen for displaying a list of a plurality of types of envelope images (thumbnail images) B7, B8, B9, and B10 registered in advance in the image forming apparatus 1. Each of the envelope images B7 to B10 has a function as a button that can be selected and operated by the user. Therefore, even when the user does not know the basis weight of the envelope used for image formation, the user can specify and select the envelope used for image formation from the plurality of envelope images B7 to B10 displayed on the screen G3. For example, the memory 71 of the controller 8 stores envelope information in which an envelope image registered in advance in the image forming apparatus 1 is associated with the basis weight of an envelope, and when the user selects one envelope image, the basis weight of the envelope corresponding to the envelope image can be acquired. That is, the basis weight acquiring unit 82 receives a user operation on the screen G3, and acquires the basis weight of an envelope used for image formation by referring to the envelope information based on the envelope image selected by the user. In this case, the basis weight of the envelope can be acquired before the execution of the print job is started in the image forming apparatus 1.

In this way, the image forming apparatus 1 of the present embodiment can determine whether the recording medium 9 is an envelope based on information input by the user before the execution of the print job is started, and can acquire the basis weight of the envelope even if the recording medium 9 is an envelope. Therefore, when the image forming apparatus 1 starts execution of a print job based on an instruction from the user to execute the print job, it is possible to initially set various control parameters corresponding to the basis weight of the envelope without changing the system speed Vs or the like after the conveyance operation of the envelope serving as the recording medium 9 is started.

Further, in the image forming apparatus 1 of the present embodiment, similarly to the first embodiment, when the recording medium 9 is an envelope, image formation corresponding to the basis weight of the envelope is possible, and therefore, even if the recording medium 9 is a thin envelope having a small thickness, image formation can be performed without causing wrinkles in the envelope.

The present embodiment is the same as the first embodiment except for the above points. For example, as described in the first embodiment, the image forming apparatus 1 may be configured such that the envelope detection sensor 40 and the basis weight detection sensor 50 are arranged along the conveyance path 33 of the recording medium 9. Therefore, when the user does not specify the type of the recording medium 9 or does not specify the basis weight of the envelope before the execution of the print job, the image forming apparatus 1 performs the operation described in the first embodiment, and thereby can perform an appropriate image forming operation according to the basis weight of the envelope even if the recording medium 9 is the envelope.

The image forming apparatus 1 according to the present embodiment may not include the envelope detection sensor 40 and the basis weight detection sensor 50.

(third embodiment)

Next, a third embodiment of the present invention will be explained. In the present embodiment, a mode in which the image forming apparatus 1 acquires information on the recording medium 9 including the basis weight from an external apparatus will be described. The configuration of the image forming apparatus 1 according to the present embodiment is the same as that described in the first embodiment.

Fig. 13 is a diagram showing a configuration example of an image forming apparatus 1 according to a third embodiment. The image forming apparatus 1 is connected to an external information processing apparatus 101 via a network 100 such as a LAN. The information processing apparatus 101 is configured by, for example, a Personal Computer (PC) or the like, and can communicate with the image forming apparatus 1 via the network 100. In the present embodiment, an image forming system is constructed by the image forming apparatus 1 and the information processing apparatus 101. The image forming system may include apparatuses other than the image forming apparatus 1 and the information processing apparatus 101.

The information processing apparatus 101 includes a recording medium measuring apparatus 110. The recording medium measuring device 110 has an outer shape of a substantially "コ" shape in which the upper case 111 and the lower case 112 are arranged to face each other with a predetermined gap in the vertical direction. The gap between the upper case 111 and the lower case 112 is an insertion space 113 into which the recording medium 9 can be inserted. The upper case 111 and the lower case 112 have the same structure as the envelope detection sensor 40 and the basis weight detection sensor 50 described in the first embodiment. That is, in the first embodiment, the envelope detection sensor 40 and the basis weight detection sensor 50 are disposed in a state of being nipped between the conveyance paths 33 of the recording medium 9, but in the present embodiment, the envelope detection sensor 40 and the basis weight detection sensor 50 are disposed in a state of being nipped between the insertion spaces 113. Therefore, the recording medium measuring device 110 can detect whether the recording medium 9 is an envelope or not and can also detect the basis weight of the recording medium 9 by operating the envelope detection sensor 40 and the basis weight detection sensor 50 in a state where the recording medium 9 is inserted into the insertion space 113.

The user instructs the information processing apparatus 101 to start the detection by operating the recording medium 9 used in the image forming apparatus 1 while inserting the recording medium into the insertion space 113 of the recording medium measuring apparatus 110, and thereby starts the measuring operation of the recording medium 9 in the recording medium measuring apparatus 110. That is, the recording medium measuring device 110 starts the following operations: it is detected whether the recording medium 9 inserted into the insertion space 113 is an envelope, and the basis weight of the recording medium 9 is detected. When the measurement operation is completed, the recording medium measurement device 110 outputs the detection result of whether or not the recording medium 9 is an envelope and the basis weight of the recording medium 9 to the information processing device 101.

The information processing apparatus 101 receives the detection result of whether the recording medium 9 is an envelope or not and the basis weight of the recording medium 9 from the recording medium measuring apparatus 110, and generates information on the recording medium 9 based on these pieces of information. At this time, if it is detected that the recording medium 9 is an envelope, the information processing apparatus 101 converts the basis weight of the recording medium 9 into the basis weight of the envelope. Then, the information processing apparatus 101 transmits information related to the recording medium 9 to the image forming apparatus 1.

When receiving information on the recording medium 9 via the communication unit 72, the image forming apparatus 1 stores the information in the memory 71 as information on the recording medium 9 newly set on the paper feed tray 3 or the manual feed tray 4. Therefore, the image forming apparatus 1 can register information relating to the recording medium 9 in advance before the execution of the print job is started.

The recording medium measuring device 110 may not include the envelope detection sensor 40. In this case, the information processing apparatus 101 can recognize that the recording medium 9 is an envelope by receiving an envelope specifying operation by the user, and can convert the basis weight of the recording medium 9 into the basis weight of the envelope.

Therefore, the envelope determining unit 81 of the present embodiment can determine whether or not the recording medium 9 is an envelope based on the information on the recording medium 9 received from the outside via the communication unit 72. The basis weight acquiring unit 82 can acquire the basis weight of the recording medium 9 based on information on the recording medium 9 received from the outside via the communication unit 72. Therefore, in the image forming apparatus 1, similarly to the second embodiment, when the recording medium 9 is an envelope, image formation corresponding to the basis weight of the envelope is possible, and even if the recording medium 9 is a thin envelope having a small thickness, image formation can be performed without causing wrinkles in the envelope.

In the above description, the recording medium measuring device 110 transmits the information on the recording medium 9 to the image forming apparatus 1 via the information processing device 101, but the present invention is not limited to this, and when the recording medium measuring device 110 can directly communicate with the image forming apparatus 1, the information on the recording medium 9 may be directly transmitted from the recording medium measuring device 110 to the image forming apparatus 1 without via the information processing device 101.

The present embodiment is the same as the first embodiment except for the above points. For example, as described in the first embodiment, the image forming apparatus 1 may be configured such that the envelope detection sensor 40 and the basis weight detection sensor 50 are arranged along the conveyance path 33 of the recording medium 9. Therefore, when the information on the recording medium 9 is not stored in the memory 71 before the execution of the print job, the image forming apparatus 1 can perform the image forming operation appropriately according to the basis weight of the envelope even if the recording medium 9 is an envelope by performing the operation described in the first embodiment.

The image forming apparatus 1 according to the present embodiment may not include the envelope detection sensor 40 and the basis weight detection sensor 50.

(modification example)

Several preferred embodiments of the present invention have been described above. However, the present invention is not limited to the description of the above embodiments, and various modifications can be applied.

For example, in the above-described embodiment, the case where the image forming apparatus 1 is configured as an MFP is exemplified. However, the image forming apparatus 1 is not limited to being configured as an MFP. That is, the image forming apparatus 1 may be a printer having only a printing function.

In the above-described embodiment, the case where the program 78 executed by the controller 8 of the image forming apparatus 1 is stored in the memory 71 in advance is exemplified. However, the program 78 may be installed or updated in the image forming apparatus 1 by being downloaded from the outside via the communication section 72. In this case, the program 78 can be downloaded to the image forming apparatus 1 via a network and provided. The program 78 may be provided in a state of being recorded on a computer-readable recording medium such as a CD-ROM or a USB memory.