阅读说明：本技术 图像形成装置 (Image forming apparatus with a toner supply device ) 是由 市来幸裕 曽雌恭伍 下平彬 原创太 二宫洋介 于 2018-12-17 设计创作，主要内容包括：本发明的图像形成装置包括：定影部件,使保持未定影像的纸张通过进行加热及加压的辊隙部；一对搬送辊,最先夹着从定影部件的辊隙部排出的纸张予以搬送；第1引导部件,在较一对搬送辊接近定影部件的位置,从自所述辊隙部排出的纸张的第1面侧接触而引导纸张的搬送；以及第2引导部件,在较一对搬送辊接近定影部件的位置,从自所述辊隙部排出的纸张的第2面侧接触而引导纸张的搬送,第1引导部件具有凹部来作为引导部,所述凹部包含朝离开纸张的搬送路径的方向凹陷的形状,第2引导部件具有包含剖面为圆弧状的形状的弯曲部来作为引导部,且以所述弯曲部的至少一部分进入所述凹部内的状态而配置。(An image forming apparatus of the present invention includes: a fixing member for passing the sheet holding the unfixed image through a nip portion for heating and pressing; a pair of conveying rollers for conveying the paper sheet discharged from the nip portion of the fixing member; a1 st guide member that guides conveyance of the sheet by contacting the sheet discharged from the nip portion from a1 st surface side thereof at a position closer to the fixing member than the pair of conveyance rollers; and a2 nd guide member that is disposed in a position closer to the fixing member than the pair of conveying rollers and that guides conveyance of the sheet by contacting the sheet from the 2 nd surface side of the sheet discharged from the nip portion, wherein the 1 st guide member has a concave portion as a guide portion, the concave portion has a shape that is concave in a direction away from a conveyance path of the sheet, and the 2 nd guide member has a curved portion having an arc-shaped cross section as a guide portion, and is disposed in a state in which at least a part of the curved portion enters the concave portion.)

1. An image forming apparatus, comprising:

a fixing member for fixing an unfixed image by conveying a sheet holding the unfixed image through a nip portion for heating and pressing;

a pair of conveying rollers for conveying the paper sheet discharged from the nip portion of the fixing member;

a1 st guide member that is positioned closer to the fixing member than the pair of conveying rollers and guides the conveyance of the sheet by contacting the sheet discharged from the nip portion on the 1 st surface side; and

a2 nd guide member which guides the conveyance of the sheet by contacting the sheet discharged from the nip portion from the 2 nd surface side at a position closer to the fixing member than the pair of conveyance rollers,

the 1 st guide member has a recessed portion as a guide portion, the recessed portion including a shape recessed in a direction away from a conveyance path of the sheet,

the 2 nd guide member has a curved portion having an arc-shaped cross section as a guide portion, and is disposed in a state where at least a part of the curved portion is inserted into the recess.

2. The image forming apparatus according to claim 1,

the curved portion is disposed so as to face the concave portion at a distance allowing paper to pass therethrough.

3. The image forming apparatus according to claim 2,

the curved portion is disposed on an upstream side in a sheet conveying direction in the concave portion.

4. The image forming apparatus according to any one of claims 1 to 3,

the 2 nd guide member includes a rotating body having a circular cross-section and in which the curved portion is rotatably disposed.

5. The image forming apparatus according to claim 4,

the rotating body of the bending portion is disposed so that the center of rotation thereof does not enter the recess.

6. The image forming apparatus according to any one of claims 1 to 3,

the 2 nd guide member has, as a guide portion, an introduction portion that guides the sheet to the curved portion on an upstream side in a sheet conveying direction from the curved portion.

7. The image forming apparatus according to claim 6,

the introduction portion is disposed so as not to enter the recess.

8. The image forming apparatus according to claim 6,

the 1 st guide member has a guide portion as a guide portion that guides a leading end of the sheet at an end portion on an upstream side in a sheet conveying direction in the concave portion so as to contact the introduction portion of the 1 st guide member.

9. The image forming apparatus according to any one of claims 1 to 3,

the end of the concave portion on the downstream side in the sheet conveying direction is arranged on the side away from the sheet conveying path with respect to a tangent line that is tangent to the curved portion and the entrance of the nip portion of the pair of conveying rollers.

10. The image forming apparatus according to any one of claims 1 to 3,

the 1 st guide member and the 2 nd guide member are continuous over the entire width direction intersecting the sheet conveying direction.

Technical Field

The present invention relates to an image forming apparatus.

Background

Conventionally, as an image forming apparatus having a function of suppressing deformation such as buckling (deformation such as bending or warping) or wrinkling of a sheet after passing through a fixing member, for example, image forming apparatuses described in patent documents 1 to 3 below are known.

Patent document 1 describes an image forming apparatus including a fixing device provided at a position where a recording material is conveyed from below to above against gravity, the fixing device including: a heating member such as a fixing roller (roll) having a heating source provided therein and rotatable; a pressure member such as a pressure roller which is rotatably disposed in pressure contact with the heating member to form a fixing nip (nip); and a paper discharge guide member that guides the recording material discharged from the fixing nip portion between the heating member and the pressing member to the outside of the apparatus, the paper discharge guide member having a guide surface that intersects a tangent line of the heating member at a most downstream point of the fixing nip portion and forms an obtuse angle with the intersection angle of the tangent line.

Patent document 2 describes an image forming apparatus including a paper feeding device, an image forming member, a fixing member, and a discharge member for discharging a sheet fixed by the fixing member from an apparatus main body, wherein a discharge direction regulating member for regulating a discharge direction of the sheet is provided in a discharge guide portion of the discharge member after a fixing roller pair of the fixing member, and the direction of the sheet discharged from the fixing roller pair is corrected.

Further, patent document 2 shows: the restricting direction of the discharge direction restricting member is upward or downward with respect to a tangential direction of the nip portion of the fixing roller pair.

Patent document 3 describes an image forming apparatus including a fixing device that guides a recording sheet (sheet) having a toner (toner) image transferred thereto and conveyed in a longitudinal direction to a discharge roller by a pair of guide members after the sheet passes through a nip portion formed between a heating rotary body and a pressing rotary body to be fixed, wherein, in a cross section perpendicular to an axis of the heating rotary body, a straight line connecting the axes of the heating rotary body and the pressing rotary body is La, a perpendicular line to the straight line is Lb, a point on a guide surface of the guide member disposed on the heating rotary body side of the pair of guide members, which is closest to the pressing rotary body side in a direction parallel to the straight line La, is P, a tangent line, which is tangent to an outer peripheral contour of the heating rotary body at a point P, which is closer to the nip portion is Lc, and a distance from the point P to the straight line La is D, the distance D is 1.6 times or more and less than 2.4 times the diameter of the heating rotor, and the tangent line Lc is inclined toward the heating rotor side with respect to the perpendicular line Lb, and the angle formed by the tangent line Lc and the perpendicular line Lb is 2.2 degrees or more and less than 6.5 degrees.

[ Prior art documents ]

[ patent document ]

Patent document 1: japanese patent laid-open No. 2006-133377

Patent document 2: japanese patent laid-open No. 2007-178580

Patent document 3: japanese patent laid-open publication No. 2011-180230

Disclosure of Invention

[ problems to be solved by the invention ]

The invention provides an image forming apparatus, which can correct distortion generated at least at the front end of paper discharged from a nip part of a fixing component by a structure without a driving source.

[ means for solving problems ]

An image forming apparatus of the present invention (A1) includes: a fixing member for fixing an unfixed image by conveying a sheet holding the unfixed image through a nip portion for heating and pressing;

a pair of conveying rollers for conveying the paper sheet discharged from the nip portion of the fixing member;

a1 st guide member that is positioned closer to the fixing member than the pair of conveying rollers and guides the conveyance of the sheet by contacting the sheet discharged from the nip portion on the 1 st surface side; and

a2 nd guide member which guides the conveyance of the sheet by contacting the sheet discharged from the nip portion from the 2 nd surface side at a position closer to the fixing member than the pair of conveyance rollers,

the 1 st guide member has a recessed portion as a guide portion, the recessed portion including a shape recessed in a direction away from a conveyance path of the sheet,

the 2 nd guide member has a curved portion having an arc-shaped cross section as a guide portion, and is disposed in a state where at least a part of the curved portion is inserted into the recess.

An image forming apparatus according to the invention (a2) is the image forming apparatus according to the invention a1, wherein the curved portion is disposed so as to face the concave portion at a distance allowing a sheet to pass therethrough.

An image forming apparatus of the present invention (A3) is the image forming apparatus of the invention a2, wherein the curved portion is disposed on a sheet conveyance direction upstream side in the concave portion.

An image forming apparatus of the invention (a4) is the image forming apparatus according to any one of the inventions a1 to A3, wherein the 2 nd guide member includes a rotating body having a circular cross-sectional shape in which the curved portion is rotatably disposed.

An image forming apparatus according to invention (a5) is the image forming apparatus according to invention a4, wherein the rotating body of the bending portion is disposed such that a rotation center thereof does not enter the concave portion.

An image forming apparatus of the present invention (a6) is the image forming apparatus of any one of inventions a1 to a5, wherein the 2 nd guide member has, as a guide portion, an introduction portion that guides the sheet to the curved portion on an upstream side in a sheet conveying direction from the curved portion.

An image forming apparatus according to invention (a7) is the image forming apparatus according to invention a6, wherein the introduction portion is disposed so as not to enter the recess.

An image forming apparatus of the present invention (A8) is the image forming apparatus according to the invention a6 or a7, wherein the 1 st guide member has a guide portion as a guide portion that guides the leading end of the sheet at an end portion on the upstream side in the sheet conveying direction in the concave portion so as to be in contact with the introduction portion of the 1 st guide member.

An image forming apparatus according to the invention (a9) is the image forming apparatus according to any one of the inventions a1 to A8, wherein an end portion on a downstream side in a sheet conveying direction in the concave portion is disposed on a side away from a sheet conveying path with respect to a tangent line that is tangent to the curved portion and an entrance of the nip portion of the pair of conveying rollers.

An image forming apparatus according to the present invention (a10) is the image forming apparatus according to any one of the inventions a1 to a9, wherein the 1 st guide member and the 2 nd guide member are provided so as to be continuous over an entire region in a width direction intersecting a sheet conveying direction.

[ Effect of the invention ]

According to the image forming apparatus of the invention a1, the distortion generated at least at the leading end portion of the sheet discharged from the nip portion of the fixing member can be corrected by the configuration without the driving source.

According to the image forming apparatus of the invention a2, the paper transport performance is ensured compared to the case where the curved portion of the 2 nd guide member is disposed in contact with the concave portion of the 1 st guide member.

According to the image forming apparatus of the invention a3, it is possible to appropriately correct the distortion generated at least at the leading end portion of the sheet, as compared to the case where the curved portion of the 2 nd guide member is disposed so as to be offset to the downstream side in the sheet conveyance direction in the concave portion of the 1 st guide member.

According to the image forming apparatus of a4 of the present invention, it is possible to improve the sheet carrying performance and reduce the load on the sheet, compared to the case where the bending portion does not include the rotatable rotating body.

According to the image forming apparatus of the invention a5, it is possible to suppress the occurrence of a sheet conveyance failure compared to the case where the rotation center of the rotating body of the bending portion is disposed so as to enter the concave portion of the 1 st guide member.

According to the image forming apparatus of the invention a6, the leading end portion of the paper can be reliably guided to the curved portion and corrected for distortion.

According to the image forming apparatus of a7 of the present invention, the distortion generated at the leading end of the paper can be reliably corrected by the bending portion instead of the introducing portion.

According to the image forming apparatus of the invention A8, the leading end portion of the paper can be reliably guided to the curved portion via the guide portion to correct the twist.

According to the image forming apparatus of the invention a9, the paper sheet after passing through the curved portion of the 2 nd guide member can be prevented from being twisted again.

According to the image forming apparatus of the invention a10, it is possible to perform uniform twist correction in the width direction of the sheet.

Drawings

Fig. 1 is a schematic diagram showing the entire image forming apparatus according to embodiment 1.

Fig. 2 is a schematic diagram showing a part (mainly, a fixing unit and a distortion correction unit) of the image forming apparatus of fig. 1.

Fig. 3 is a schematic view showing a state in which the distortion correcting unit of fig. 2 is viewed from the direction indicated by the arrow B except for a part of the 2 nd guide member.

Fig. 4 is an enlarged schematic view of the configuration of the distortion correction unit shown in fig. 2.

Fig. 5 is a schematic diagram showing another configuration of the distortion correction unit.

Fig. 6(a) to 6(D) are schematic diagrams showing another configuration example of the recess of the 1 st guide member in the distortion correcting portion.

Fig. 7 is a schematic diagram showing an operation state when the plain paper twisted by the fixing unit is introduced into the twist correcting unit.

Fig. 8 is a schematic diagram showing an operation state when correction is applied to the normal paper having a twist in the twist correcting section.

Fig. 9 is a schematic view showing another operation state in the skew correcting section when correcting action is applied to the plain paper having the skew.

Fig. 10 is a schematic view showing still another operation state in the skew correcting section when the correction action is applied to the plain paper having the skew.

Fig. 11 is a schematic view showing an enlarged view of a structural part and the like of the distortion correcting portion, which provides a correcting effect.

Fig. 12 is a schematic diagram showing another configuration example of the 2 nd guide member in the distortion correcting portion.

Fig. 13 is a schematic diagram showing the entire image forming apparatus according to embodiment 2.

Fig. 14 is a schematic diagram showing a part (mainly, a fixing unit and a distortion correction unit) of the image forming apparatus shown in fig. 13.

Fig. 15 is a schematic diagram showing another configuration example of the fixing unit and the distortion correcting unit.

Fig. 16 is a schematic diagram showing an operation state when the normal paper having the distortion is introduced into the distortion correcting portion of fig. 15 and an operation state when the correction is applied.

Fig. 17(a) is a schematic diagram illustrating a fixing unit of a type 1 nip and a sheet discharged from the fixing unit and subjected to image distortion, and fig. 17(B) is a schematic diagram illustrating a fixing unit of a type 2 nip and a sheet discharged from the fixing unit and subjected to image distortion.

[ description of symbols ]

1: image forming apparatus with a toner supply device

5: fixing unit (an example of a fixing member)

9: paper sheet

9 a: watch (one example of single side)

9 b: back side (one example of the opposite side)

45: conveying roller (an example of a pair of conveying rollers)

46: discharge roller (an example of a pair of conveying rollers)

61: 1 st guide member

62: concave part

63: guide part

65: 2 nd guide member

66: bending part

67: roller (one example of rotatable rotating body)

68: introduction part

C: direction of paper conveyance

D2: direction away from 2 nd guide member

FN: roll gap part

MT: toner image (an example of an undetermined image)

S: space(s)

O1: center of rotation

TNs: entrance of the roll gap part

TL: tangent line

Detailed Description

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

[ embodiment 1]

Fig. 1 and 2 show an image forming apparatus 1 according to embodiment 1. Fig. 1 shows the overall configuration of the image forming apparatus 1, and fig. 2 shows the configuration of a part (mainly, a fixing unit and a distortion correction unit) of the image forming apparatus 1.

Arrows denoted by reference numeral X, Y, Z in the drawings indicate directions of the width, height, and depth of a three-dimensional space assumed in the drawings. In fig. 1, 2, and the like, the circle of the portion where the X, Y directional arrows intersect indicates that the Z direction is directed vertically downward in the drawing.

< integral Structure of image Forming apparatus >

The image forming apparatus 1 is configured as a printer (printer) that forms an image based on image information input from the outside on a sheet 9, for example.

As shown in fig. 1, the image forming apparatus 1 includes, in an internal space of a housing 10, the following parts: an image forming section 2 for forming an unfixed image based on image information and transferring the unfixed image to a sheet 9; a paper feeding unit 4 for storing paper 9 supplied to the image forming unit 2; a fixing section 5 for fixing the unfixed image transferred by the image forming section 2 to a sheet 9; and a skew correction unit 6 that corrects a skew generated in the sheet 9 discharged from the fixing unit 5. A chain line of one dot in fig. 1 and the like indicates a main conveyance path when the sheet 9 is conveyed in the housing 10.

Here, the image information is information related to an image, such as characters, figures, photographs, and patterns. The frame 10 is a structure formed into a desired shape by various support members, exterior materials, and the like. The frame 10 has a discharge housing portion 12 and a paper discharge port 13 formed in a part of an upper surface portion thereof, the discharge housing portion 12 houses the paper 9, which is discharged after an image is formed, in a state of being overlapped, and the paper discharge port 13 discharges the paper 9 toward the discharge housing portion 12.

The image forming portion 2 is a portion in which the following devices relating to the electrophotographic method are disposed around a photosensitive drum (drum)21, which is an example of a photosensitive member that rotates in the direction indicated by an arrow, for example.

The machine is a machine such as: a charging device 22 for charging the outer peripheral surface (image formable surface) of the photosensitive drum 21; an exposure device 23 that forms an electrostatic latent image by exposing the outer peripheral surface of the photosensitive drum 21 based on image information; a developing device 24 that develops the electrostatic latent image formed on the outer peripheral surface of the photosensitive drum 21 with a developer (toner); a transfer device 25 for transferring an unfixed image (toner image) formed on the outer peripheral surface of the photosensitive drum 21 to the sheet 9; and a cleaning device 26 for removing and cleaning the excess materials such as toner and paper dust adhering to the outer peripheral surface of the photosensitive drum 21. In the image forming section 2, a portion where the photosensitive drum 21 contacts or faces the transfer device 25 is a transfer position TP where the sheet 9 passes to transfer an unfixed image, i.e., a toner image.

The paper feed section 4 is a part configured by arranging devices such as a cassette (cassette)41 and a feeder 43. The paper feed unit 4 is provided in the housing 10 at a lower position than the image forming unit 2.

The receiving cassette 41 is a receiving member which has a loading plate 42 for loading and receiving a plurality of sheets 9 in a desired direction and is attached so as to be capable of being pulled out to the outside of the frame 10. The feeding device 43 is a device that feeds the sheets 9 loaded on the loading plate 42 of the storage cassette 41 one by one from above by a plurality of rollers or the like.

As shown in fig. 1 and 2, the fixing section 5 is a part (fixing member) in which devices such as a rotating body 51 for heating and a rotating body 52 for pressurizing are disposed in an internal space of a housing (not shown) in which an inlet and an outlet for the sheet 9 are provided. The fixing unit 5 is provided inside the housing 10 at a position above the transfer position TP of the image forming unit 2.

The heating rotary body 51 is a part of a fixing member including a roller type rotating in a direction indicated by an arrow. The heating rotor 51 receives rotational power from a not-shown driving device and rotates in a direction indicated by an arrow, and is heated by, for example, a heat source 53 disposed inside thereof so as to be maintained at a desired temperature. The pressure rotating member 52 is a part of a fixing member including a roller type that is driven to rotate by contacting the heating rotating member 51 under a desired pressure.

In the fixing unit 5, a portion where the heating rotating body 51 and the pressing rotating body 52 are in contact is configured as a nip portion (fixing processing portion) FN for heating and pressing the sheet 9 on which the toner image of the unfixed image is transferred in order to perform the fixing processing.

The fixing unit 5 discharges the paper 9 after fixing from the nip portion FN in a substantially direction (for example, a direction opposite to the direction of gravity (upward in the vertical direction) and included in a range of ± 45 ° with respect to the direction of gravity). Hereinafter, the fixing unit 5 of the type that performs the above-described discharge may be referred to as an "discharge-type fixing unit 5A".

As shown in fig. 1, in the image forming apparatus 1, a paper feed conveyance path Rt1 is provided between the paper feed section 4 and the image forming section 2, and the paper feed conveyance path Rt1 conveys the paper 9 positioned in the paper feed section 4 to supply it to the transfer position TP of the image forming section 2. The paper feed conveyance path Rt1 is configured by arranging a pair of conveyance rollers 44 that nip and convey the paper 9, a guide member, not shown, that secures a conveyance space for the paper 9 and guides conveyance of the paper 9, and the like.

Further, a discharge conveyance path Rt2 is provided between the fixing section 5 and the discharge accommodating section 12, and the conveyance path Rt2 discharges the fixed paper 9 to the discharge accommodating section 12. The discharge conveyance path Rt2 is configured by arranging a pair of discharge rollers 46, which nip the conveyed sheet 9 in front of the sheet discharge port 13 formed in a wall surface of the housing 10 constituting a part of the discharge storage section 12, and a guide member, not shown, which guides the conveyance of the sheet 9 by securing a conveyance space for the sheet 9. The discharge conveyance path Rt2 is a conveyance path that curves upward from the fixing unit 5 in the direction in which the pair of discharge rollers 46 are located, and forms a conveyance path.

< image Forming action >

Then, the image forming apparatus 1 performs the following basic image forming operation.

First, when a control unit (not shown) receives an instruction to request an image forming operation from an external connection device or the like, the image forming apparatus 1 starts up necessary portions of the image forming unit 2, the paper feeding unit 4, the fixing unit 5, and the like at a predetermined timing.

In the image forming unit 2, as shown in fig. 1, the photosensitive drum 21 is rotated in a direction indicated by an arrow, the charging device 22 charges the outer peripheral surface of the photosensitive drum 21 to a desired potential, and the exposure device 23 irradiates the charged outer peripheral surface of the photosensitive drum 21 with light (dotted arrow) corresponding to an image signal subjected to image processing to form an electrostatic latent image. Then, the developing device 24 supplies toner as a developer containing a desired color (for example, black) and causes it to adhere by electrostatic action, thereby developing the electrostatic latent image. Thereby, a toner image of a desired color corresponding to the electrostatic latent image is formed on the outer peripheral surface of the photosensitive drum 21.

On the other hand, in the paper feed section 4, the paper 9 accommodated in the accommodating cassette 41 is fed by the feeding device 43 toward the transfer position TP in the image forming section 2 in accordance with the timing of the image forming operation in the image forming section 2. At this time, in the paper feeding section 4, the paper 9 fed from the storage cassette 41 by the feeding device 43 is fed to the conveying roller 44 as a registration roller (registration roller) in the paper feeding and conveying path Rt1, and then is conveyed to the transfer position TP at a desired timing by the conveying roller 44.

In the image forming portion 2, the transfer device 25 transfers the toner image formed on the photosensitive drum 21 to the sheet 9 fed from the sheet feeding portion 4 at the transfer position TP. In the image forming section 2, the cleaning device 26 removes and cleans the excess material adhering to the outer peripheral surface of the photoreceptor drum 21 after transfer or the like.

Then, the paper 9 on which the toner image is transferred in the image forming unit 2 is discharged from the transfer position TP and sent to the fixing unit 5. In the fixing section 5, the sheet 9 holding the toner image is introduced and passes through the nip portion FN. Thus, the toner image on the paper 9 is heated and melted under pressure in the nip portion FN, and then fixed to the paper 9.

Finally, the paper 9 after the fixing is discharged from the fixing section 5, and then is conveyed through the discharge conveyance path Rt2 and is stored in the discharge storage section 12. At this time, the paper 9 discharged from the fixing unit 5 after fixing is sent to the discharge roller 46 through the discharge conveyance path Rt2, and then is sent out of the housing 10 through the paper discharge port 13 by the discharge roller 46, and is stored in the discharge storage unit 12 so as to fall.

By performing the above series of operations, an image of a desired color is formed on one side of one sheet of paper 9, and the basic image forming operation is ended.

In the image forming apparatus 1, when a command requesting an image forming operation for a plurality of sheets of paper 9 is issued, the series of operations is repeated a plurality of times in the same manner.

< distortion at fixing >

In the image forming apparatus 1 described above, as illustrated in fig. 17 a, distortion (for example, also referred to as "inverse image distortion") that is curved and deformed so as to warp toward the back surface 9b side opposite to the surface 9a on which the image TI is located immediately after the fixing process of the unfixed image (toner image) MT may occur in the sheet 9 discharged from the nip portion FN of the fixing unit (fixing member) 5.

The distortion at this time tends to occur when, for example, a fixing member forming the nip portion FN1 where the pressing rotary member 52 serving as the fixing portion 5 falls into the surface of the heating rotary member 51 is applied and plain paper is used as the paper sheet 9.