阅读说明：本技术 图像读取单元和图像读取装置 (Image reading unit and image reading apparatus ) 是由 大竹润 于 2020-03-13 设计创作，主要内容包括：本发明涉及图像读取单元和图像读取装置。图像读取单元包括照亮部分、读取部分、外壳和包括反射表面的反射部件。外壳设置有开口。反射部件保持在外壳的开口的外侧,使得反射表面的至少一部分通过开口露出到外壳的内侧。(The invention relates to an image reading unit and an image reading apparatus. The image reading unit includes an illuminating section, a reading section, a housing, and a reflecting member including a reflecting surface. The housing is provided with an opening. The reflective member is held outside the opening of the housing such that at least a portion of the reflective surface is exposed to the inside of the housing through the opening.)

1. An image reading unit, comprising:

an illumination section configured to illuminate an object with light;

a reading section configured to read image information of an object by photoelectrically converting reflected light from the object illuminated with light by the illuminating section;

a housing configured to hold the reading section and provided with an inlet through which light reflected by an object passes; and

a reflection member including a reflection surface for reflecting the reflected light passing through the entrance and configured to form an optical path for guiding the reflected light from the object to the image reading portion,

wherein the housing is provided with an opening, an

Wherein the reflective member is held outside the opening of the housing such that at least a portion of the reflective surface is exposed to the inside of the housing through the opening.

2. The image reading unit according to claim 1, wherein an entire area of an inner side of the opening is covered with a reflective surface as viewed from an inner side of the housing.

3. The image reading unit according to claim 1, wherein at least a part of a periphery of the opening is located inside a periphery of a reflection surface when viewed from an inside of the housing.

4. The image reading unit according to claim 1, wherein the opening and the reflection member extend in a main scanning direction,

wherein the housing is provided with a recessed portion recessed from an outer side to an inner side of the housing in a direction intersecting with a main scanning direction,

wherein the opening is formed at the bottom of the recess portion, an

Wherein the reflecting member is held by the housing in a state where the reflecting member is accommodated in the recessed portion.

5. The image reading unit according to claim 1, wherein the opening has a rectangular shape, and

wherein a reflecting surface of the reflecting member has a rectangular shape including the opening when viewed from an inside of the housing.

6. The image reading unit according to claim 1, wherein the opening has a shape such that a first portion having a first width with respect to a main scanning direction of the reading portion and a second portion having a second width narrower than the first width with respect to the main scanning direction are adjacent to each other in a direction intersecting the main scanning direction, and

wherein the reflecting surface of the reflecting member has a shape including a first portion and a second portion when viewed from the inside of the housing.

7. The image reading unit according to claim 6, wherein the reflection member is a part of a reduction optical system in which a width of the optical path with respect to the main scanning direction is narrowed when light travels along the normal optical path to the reading portion, and

wherein the reflective component and the opening are disposed such that: when light travels along the normal optical path to the reading section, the light reflected by the reflection surface at the first portion of the opening is then reflected by the reflection surface at the second portion of the opening.

8. The image reading unit according to claim 1, wherein when the opening is a first opening, the reflecting member is a first reflecting member, and a reflecting surface is a first reflecting surface, the image reading unit further comprises:

a second reflection member including a second reflection surface for reflecting light and configured to form an optical path for guiding the reflected light from the object to the image reading portion, an

A second opening provided in the housing and penetrating the housing from an inner side to an outer side of the housing,

wherein the second reflecting member is held outside the housing with respect to the second opening such that at least a part of the second reflecting surface is exposed to the inside of the housing through the second opening.

9. The image reading unit according to claim 8, wherein the first reflection member and the second reflection member are part of a reduction optical system in which a width of an optical path with respect to a main scanning direction of the reading portion is narrowed when light travels along a normal optical path to the reading portion, and are disposed such that light reflected into the first region of the first reflection surface enters the second region of the second reflection surface along the normal optical path, and

wherein, in a periphery of the second opening with respect to the main scanning direction, a portion adjacent to the second region with respect to the main scanning direction is located inside an opposite end portion of the first region with respect to the main scanning direction.

10. An image reading apparatus, comprising:

a stacking table on which sheets are stacked;

an illuminating portion configured to illuminate the sheets stacked on the stacking portion with light;

a reading section configured to read image information of an object by photoelectrically converting reflected light from the object illuminated with light by the illuminating section;

a housing configured to hold the reading section and provided with an inlet through which light reflected by an object passes; and

a reflection member including a reflection surface for reflecting the reflected light passing through the entrance and configured to form an optical path for guiding the reflected light from the object to the image reading portion,

wherein the housing is provided with an opening, an

Wherein the reflective member is held outside the opening of the housing such that at least a portion of the reflective surface is exposed to the inside of the housing through the opening.

Technical Field

The present invention relates to an image reading unit for reading image information from an object and an image reading apparatus for reading image information from a sheet.

Background

An image reading unit used with a document scanner or a copying machine reads image information from an original by irradiating the original with light and by photoelectrically converting an image formed on an imaging (image pickup) device with reflected light from the original into image information. In the case of using a Charge Coupled Device (CCD) as an imaging device, a normal optical path for guiding reflected light from an original to the imaging device while repeatedly reflecting the reflected light by a plurality of reflecting members provided in a housing of an image reading unit is formed. When there is light (stray light) that reaches the imaging device without traveling along a normal optical path, there is a possibility that a phenomenon of noise generation (flare) or double reflection of an image (ghost) occurs in reading image information.

In order to reduce stray light, countermeasures have been taken such that the housing is formed in black or the sealing property of the housing is enhanced so as not to take in light other than reflected light from the original as much as possible. Japanese patent application publication (JP- ｃA) 2016-.

As a method of reducing stray light, it may be considered that a light shielding member is provided in the periphery of the reflection surface of the reflection member and a light beam deviated from the normal optical path is shielded by the light shielding member. However, there is a possibility that the cost and size of the apparatus (device) are increased by additionally providing the light shielding member.

Disclosure of Invention

The main object of the present invention is to provide an image reading unit capable of reducing stray light by a simple configuration.

According to an aspect of the present invention, there is provided an image reading unit including: an illuminated portion configured to illuminate the object with light; a reading section configured to read image information of an object by photoelectrically converting reflected light from the object illuminated with light by the illuminating section; a housing configured to hold a reading portion and having an entrance through which light reflected by an object passes; and a reflection member including a reflection surface for reflecting the reflected light passing through the entrance and configured to form an optical path for guiding the reflected light from the object to the image reading portion, wherein the housing has an opening, and wherein the reflection member is held outside the opening of the housing such that at least a part of the reflection surface is exposed to an inside of the housing through the opening.

Other features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.

Drawings

FIG. 1 is a schematic diagram of a printer according to an embodiment of the present invention.

Fig. 2 is a schematic diagram showing a main body of a scanner of the image reading apparatus.

Fig. 3 is a schematic diagram showing a cross-sectional structure of the scanner unit.

Fig. 4 is a perspective view for illustrating a mounting method of the second mirror.

FIG. 5 is a perspective view showing a second mirror mounted on the cassette frame.

Fig. 6 is a schematic diagram showing the structure of the second mirror and its periphery.

Fig. 7 is a schematic diagram for comparison between a reference example and an embodiment of the present invention.

FIG. 8 is a perspective view showing a third mirror mounted on the cassette frame.

Part (a) of fig. 9 is a schematic diagram showing a positional relationship between the reflection area of the second mirror and the reflection area of the third mirror, and part (b) of fig. 9 is a schematic diagram showing a modification of the present embodiment.

Fig. 10 is a schematic view showing a positional relationship between the second mirror and the first opening.

Detailed Description

Exemplary embodiments for implementing the present invention will be described below with reference to the accompanying drawings.

A general structure of a printer 101 as an image forming apparatus of the present embodiment will be described first with reference to fig. 1. As shown in fig. 1, the printer 101 includes a printer main assembly 101A and an image reading apparatus 103. An image reading apparatus 103 provided on the printer main assembly 101A includes a main body unit 30 and an ADF (automatic document feeder) 1 as described later in detail, and reads image information by optically scanning an original D. The original D is a sheet including paper such as a sheet or an envelope, a plastic film or cloth such as a sheet for an overhead projector (OHT), or the like. The image information converted into an electric signal by the image reading apparatus 103 is transmitted to a controller 132 provided in the printer main assembly 101A.

The printer main assembly 101A includes an image forming portion 133 for forming an image on a sheet P as a recording material (medium) and a sheet feeding portion 134 for feeding the sheet P to the image forming portion 133. The sheet feeding portion 134 includes sheet accommodating portions 137a, 137b, 137c, and 137d capable of accommodating sheets different in size from each other. The sheets accommodated in each of the sheet accommodating portions are fed by the pickup roller 112, and are separated one by the feed roller 113a and the retard roller 113b, and then conveyed to the corresponding feed roller pair 131. Then, the sheet P is sequentially conveyed to a plurality of feed roller pairs 131 provided along the sheet feeding path, and then fed toward a registration roller pair 136.

Incidentally, the sheet P placed on the manual feed tray 137e by the user is fed to the inside of the printer main assembly 101A by the feed roller 138, and then fed toward the registration roller pair 136. The registration roller pair 136 not only corrects the skew movement of the sheet P by stopping the leading end of the sheet P, but also resumes the feeding of the sheet P in synchronization with the progress of the image forming action as the toner image forming process by the image forming portion 133.

The image forming portion 133 for forming an image on the sheet P is an electrophotographic type image forming unit having a photosensitive drum 121 as a photosensitive member. The photosensitive drum 121 is rotatable in the feeding direction of the sheet P, and, at the periphery of the photosensitive drum 121, a charger 118, an exposure device 123, a developing device 124, a transfer charger 125, a separation charger 126, and a cleaner 127 are provided. The charger 118 charges the surface of the photosensitive drum 121, and the exposure device 123 exposes the photosensitive drum 121 based on image information input from the image reading apparatus 103 or the like, so that an electrostatic latent image is formed on the photosensitive drum 121.

The developing device 124 contains a developer containing toner, and develops the electrostatic latent image into a toner image by supplying the charged toner to the photosensitive drum 121. The toner image carried on the photosensitive drum 121 is transferred onto the sheet P fed from the registration roller pair 136 by a bias electric field formed by the transfer belt 125. The sheet P on which the toner image is transferred is separated from the photosensitive drum 121 by a bias electric field formed by a separation charger 126, and then fed toward a fixing portion 129 by a predetermined fixing feeding portion 128. Incidentally, the deposition matter such as transfer residual toner and the like remaining on the photosensitive drum 121 without being transferred to the sheet P is removed by the cleaner 127, and the photosensitive drum 121 is prepared for the subsequent image forming action.

The sheet P fed to the fixing portion 129 is subjected to a fixing process including pressurization and heating while being nipped and pressurized by the roller pair. As a result, the image is fixed on the sheet P by the fusion and subsequent fixing of the toner on the sheet P. Upon completion of the image output, the sheet P having obtained the fixed image is discharged by the discharge roller pair 116 onto a discharge tray 130 projecting to the outside of the printer main assembly 101A. In the case of forming an image on the rear surface of the sheet P in the duplex printing, the sheet P passing through the fixing portion 129 is turned upside down by the reversing portion 139, and is fed toward the registration roller pair 136 through the feeding path 140 for the duplex printing. Then, the sheet P on which the image is formed again by the image forming portion 133 is discharged onto the discharge tray 130.

The image forming portion 133 is an example of an image forming means, and, for example, an ink jet type image forming unit or an offset type printing mechanism may also be used as the image forming means.

(image reading apparatus)

The structure of the image reading apparatus 103 will be described below with reference to FIGS. 1 to 3. As shown in fig. 1, the ADF 1 feeds an original D set on an original feeding tray 2 toward an original discharge tray 3. The ADF 1 is openable with respect to the main body unit 30, and the main body unit 30 is fixed to the printer main body assembly 101A.

As shown in fig. 2, the main body unit 30 includes a frame 30a also serving as a housing member, and, at an upper surface of the frame 30a, an original supporting platen glass 31 and a platen glass 31a are provided. In the present embodiment, the original support platen glass 31 is a stacking table. Within the frame 30a, a scanner unit 50 is held. The scanner unit 50 is configured to be movable in parallel with the original support platen glass 31 by a not-shown wire or belt driven by a motor.

The scanner unit 50 is a CCD (charge coupled device) type image reading unit shown in fig. 3. The scanner unit 50 includes a cassette frame 51, an illumination unit 52, a first mirror 53, a second mirror 54, a third mirror 55, a fourth mirror 56, a fifth mirror 57, a lens unit 58, and a CCD substrate 59. On the CCD substrate 59, a CCD59a as an example of an imaging (image pickup) device is arranged in the main scanning direction. The illuminating unit 52 is an illuminating portion in the present embodiment, and the CCD59a is a reading portion in the present embodiment. Incidentally, in the present embodiment, the CCD59a is used as an example of an imaging device, but an imaging device using CMOS (complementary metal oxide semiconductor) may also be used.

The illumination unit 52 is mounted above the cartridge frame 51 of the scanner unit 50. The lighting unit 52 includes a lighting frame 52, a light emitting element (e.g., a light emitting diode) not shown, and two light guide units 60L and 60R. The light L1 and the light L2 emitted by the light emitting elements irradiate the original D as an object subjected to reading of image information in a state where they are uniformly diffused in the main scanning direction by the light guiding units 60L and 60R. The illumination frame 52a, which constitutes a housing (frame) of the scanner unit 50 in cooperation with the cartridge frame 51, has an entrance (opening) 701. The entrance 701 that allows reflected light to enter the scanner unit 50 from the subject is not limited to the opening of the housing, and may be constituted by a transparent member such as glass.

The position where the light emitted from the light guide units 60L and 60R is concentrated on the reading surface is referred to as "original irradiation (illumination) position F". The sub-scanning direction is a direction perpendicular to the main scanning direction, and, in the present embodiment, is a moving direction of the scanner unit 50 when the scanner unit 50 moves below the original support platen glass 31. Further, the reading surface refers to an imaginary (virtual) plane extending at a predetermined height (object point position of the optical system) at which the scanner unit 50 can perform reading of image information with high accuracy with respect to a height direction (depth of field direction) perpendicular to the main scanning direction and the sub-scanning direction. The reading surface in the present embodiment corresponds to, for example, the lower surface of the original D in a state where the original D is kept stationary on the original support platen glass 31.

The light reflected by the original D travels toward the inside of the scanner unit 50 through an entrance (opening) 701. Light traveling through the entrance 701 to the inside of the scanner unit 50 is reflected by the mirrors 53 to 57. Five (first to fifth) mirrors 53 to 57 and a lens unit 58 form an optical path for guiding reflected light from the original D to a CCD substrate 59. As the respective mirrors 53 to 57 as examples of the reflecting member, for example, mirrors each having a reflecting surface prepared by forming an aluminum deposition film on a supporting member such as glass are used. The reflected light (light beam L3) reflected by the original D at the original irradiation position F passes through the first mirror 53, the second mirror 54, the third mirror 55, the fourth mirror 56, the fifth mirror 57, and the lens unit 58, and is focused as an image on the CCD59 a.

The CCD59a receives the light beam L3, and photoelectrically converts the light beam L3 into an electric signal representing an image of the original D. The image information read by the CCD59a is transferred to the controller 132, and is used for image formation by the image forming portion 133.

Hereinafter, the path of the scattered light reflected by document D through first mirror 53, second mirror 54, third mirror 55, fourth mirror 56, fifth mirror 57, and lens unit 58 and reaching CCD59a is referred to as a "normal optical path". The light beam L3 shown in fig. 3 is a light beam representing one light (light beam) which is sent from the original irradiation position F and reaches the CCD59a through the normal optical path. Further, light reaching the CCD59a along a path deviated from the normal optical path is referred to as stray light. Examples of stray light include a light beam that enters the inside of the scanner unit 50 through a portion other than the inlet 701 of the scanner unit 50 (the opening between the light guide units 60R and 60L) that opposes the original irradiation position F. Further, a light beam that passes through the opening of the scanner unit 50 opposite to the original irradiation position F and is scattered by the cassette frame 51 by deviating from the reflection region of any of the mirrors may cause stray light.

The space inside the cartridge frame 51 is covered at the upper portion thereof with the lighting frame 52a of the lighting unit 52, and at the lower portion thereof with the lower cover 63. Further, as seen in the main scanning direction, the CCD59a is disposed in a space defined by a concave portion provided on the cartridge frame 51 and the substrate main body 59b of the CCD substrate 59.

Further, the cartridge frame 51 is a reflection area having a first opening 51b and a second opening 51d which are described later and closed by a second mirror 54 and a third mirror 55, respectively. Therefore, the second mirror 54 and the third mirror 55 in the present embodiment constitute a part of a housing that divides the inside and the outside of the scanner unit 50 in cooperation with the cartridge frame 51, the lighting frame 52a of the lighting unit 52, the lower cover 63, and the substrate main body 59 b. Inside the scanner unit 50 is a space that accommodates a normal optical path and a reading portion. However, the structure of the housing shown is merely an example, and the shape and arrangement of the housing may be changed as appropriate.

The image reading apparatus 103 thus configured reads image information from a sheet as the original D in a translation reading (passing) mode in which the original image is scanned while the original D is fed by the ADF 1 and in a fixed reading mode in which the original placed on the original support platen glass 31 is scanned.

In a case where the image reading apparatus detects the original D set on the original feeding tray 2, or in a case where the user explicitly provides an instruction through an operation panel or the like of the printer main assembly 101A, the panning reading mode is selected. In this case, the ADF 1 feeds the originals D set on the original feeding tray 2 one by one in a state where the scanner unit 50 is located below the platen glass 31a, and then the scanner unit 50 reads image information from the fed original D. That is, in the translational reading mode, the original D is scanned by being fed in the sub-scanning direction with respect to the scanner unit 50 whose position is fixed.

On the other hand, in a case where the image reading apparatus detects the original D placed on the original supporting platen glass 31, or in a case where the user explicitly provides an instruction through an operation panel or the like of the printer main assembly 101A, the fixed reading mode is selected. In the case of the fixed reading mode, first, the user opens the ADF 1 and sets an original on the original support platen glass 31 and closes the ADF 1 so that the original is positioned with respect to the original support platen glass 31. Then, the scanner unit 50 reads image information from the original D placed on the original support platen glass 31 while moving along the original support platen glass 31. That is, in the fixed reading mode, the scanner unit 50 scans the original D while moving in the sub-scanning direction with respect to the original D whose position is fixed.

Incidentally, the scanner unit 50 may also be mounted in an image reading apparatus capable of performing an action in only one of the translational reading mode and the fixed reading mode. Further, by additionally providing the scanner unit 50 inside the ADF 1, image information can also be read by two scanner units from both sides (surfaces) of the original D fed by the ADF 1.

(second mirror)

The mounting structure of the mirror disposed in the scanner unit 50 will be described. First, the second mirror 54 as an example of the reflecting member will be described. As shown in fig. 4, at one side wall portion 51a with respect to the sub-scanning direction, the cartridge frame 51 is provided with a first opening 51 b. The first opening 51b is a hole penetrating the scanner unit 50 from the inside to the outside of the scanner unit 50, and is formed in a rectangular shape extending in the main scanning direction. That is, as seen in the sub-scanning direction, the opening width of the first opening 51b with respect to the main scanning direction is larger than the opening width of the first opening 51b with respect to the height direction.

The second mirror 54 is mounted to the cartridge frame 51 from the outside of the cartridge frame 51 to close the entire area of the rectangular first opening 51 b. In the present embodiment, the second mirror 54 is fixed to the cartridge frame 51 at opposite ends with respect to the main scanning direction by fixing members 61 and 61 that are leaf springs made of metal. Similar fixing methods are also used for the other mirrors (53, 55, 56, 57). However, the reflecting member mounting method is not limited to this, and, for example, the second mirror 54 may also be fixed to the cartridge frame 51 with an adhesive.

As shown in fig. 5, the reflection surface 54a of the second mirror 54 is exposed to the inside of the scanner unit 50 through the first opening 51 b. Through the first opening 51b, the light beam L3 traveling along the normal optical path reaches the reflection surface 54a of the second mirror 54, but the light beam L4 deviated from the normal optical path is configured not to reach the reflection surface 54 a. That is, the light beam L3 is reflected by the reflection surface 54a and reaches the third mirror 55, but the light beam L4 is absorbed by the black cartridge frame 51 and does not reach the third mirror 55. Incidentally, the cartridge frame 51 is constituted by a light shielding member. Therefore, the portion surrounding the first opening 51b of the cartridge frame 51 has a light shielding function, so that the light beam L4 deviated from the normal optical path is not allowed to reach the CCD59 a.

Further, as shown in fig. 5 and 6, the second mirror 54 is disposed so as to cover the entire area of the inner side of the first opening 51b by the reflection surface 54a when viewed from the inner side of the scanner unit 50. Specifically, the reflective surface 54a of the second mirror 54 has a rectangular shape including a rectangular first opening 51 b.

When such a configuration is adopted, even in the case where the light beam L5 enters the first opening 51b from the outside of the scanner unit 50, the light beam L5 is reflected to the outside of the scanner unit 50 by the reflection surface 54a of the second mirror 54. That is, the light beam L5 does not enter the inside of the scanner unit 50, and therefore does not reach the CCD59 a. Further, the reflection surface 54a is surrounded by the periphery of the first opening 51b as viewed from the inside of the scanner unit 50, and therefore, the light beam traveling from the outside of the scanner unit 50 to the periphery of the first opening 51b is absorbed by the black cartridge frame 51. Therefore, in a configuration in which the housing of the scanner unit 50 is provided with the first opening 51b and the second mirror 54 is mounted to the scanner unit 50 from the outside of the housing, stray light is prevented from entering the inside of the scanner unit 50 through the first opening 51 b. That is, a part of the housing of the scanner unit 50 is used as a portion for shielding stray light near the reflection member, whereby the stray light can be reduced with a simple configuration.

Further, in the present embodiment, a configuration is adopted in which at least a part of the periphery of the first opening 51b is configured to be located inside the periphery of the reflection surface 54a when viewed from the inside of the scanner unit 50 (i.e., the peripheral wall forming the periphery of the first opening 51b overlaps with the reflection surface 54 a). That is, when viewed from the inside of the scanner unit 50, the peripheral wall that defines the first opening 51b and is a part of the cartridge frame 51 overlaps the reflection surface 54a of the second mirror 54. Here, as shown in fig. 3 to 6, the peripheral wall defining the first opening 51b is constituted by an upper rib 201, a lower rib 202, a first side wall 203, and a second side wall 204. The upper rib 201 and the lower rib 202 are an upper peripheral wall and a lower peripheral wall of the first opening 51b with respect to the height direction, respectively, and extend in the long side direction (main scanning direction) of the second mirror 54. The first side wall 203 and the second side wall 204 are one side peripheral wall and the other side peripheral wall of the first opening 51b with respect to the long side direction, respectively, and extend in the height direction at positions corresponding to the ends of the second mirror 54 with respect to the long side direction.

Each of the upper rib 201, the lower rib 202, the first scanning unit 203, and the second sidewall 204 protrudes from the inner surface of the concave portion 51 u. Further, each of the upper rib 201, the lower rib 202, the first side wall 203, and the second side wall 204 overlaps with the reflection surface 54a of the second mirror 54 when viewed from the inside of the scanner unit 50 in the direction perpendicular to the reflection surface 54 a. Fig. 10 is a schematic view of the second mirror 54 viewed from the inside of the scanner unit 50. In fig. 10, a broken line indicates the outer periphery of the reflecting surface 54a of the second mirror 54. In fig. 10, a solid line indicates the periphery of the first opening 51 b.

By adopting such a configuration, stray light entering the inside of the scanner unit 50 through the gap between the reflection surface 54a and the cartridge frame 51 can be effectively suppressed. Incidentally, the reflection surface 54a may appropriately contact the outer surface of the cartridge frame 51 at the periphery of the first opening 51b, but when stray light can be sufficiently shielded in a slight gap between the reflection surface 54a and the cartridge frame 51, the gap is allowed.

As shown in fig. 3 and 6, the cartridge frame 51 has a recessed portion 51u constituting a mounting portion of the second mirror 54. The recessed portion 51y has a recessed shape such that the recessed portion 51u is recessed from the outside to the inside (i.e., from left to right in the drawing) with respect to a direction intersecting the main scanning direction (particularly, the sub-scanning direction). The first opening 51b is formed at the bottom of the recess portion 51 u. Further, the second mirror 54 is accommodated in the concave portion 51u in a state where the second mirror 54 is mounted in the cartridge frame 51.

As shown in the upper reference example of fig. 7, it is also conceivable that the entire second mirror 54 is provided inside the housing of the scanner unit 50, but in such a configuration, the scanner unit 50 is enlarged as compared with the present embodiment. That is, in this reference example, it is necessary that one side wall portion 51a with respect to the sub-scanning direction covers the entirety of the second mirror 54 when viewed in the sub-scanning direction, and therefore, the side wall portion 51a and the second mirror 54 are in a positional relationship such that they are arranged in the sub-scanning direction when viewed in the main scanning direction. Therefore, when the side wall portion 51a is brought close to the other side wall portion, it is necessary to move the second mirror 54 as well, but the change in the position of the second mirror 54 is accompanied by a change in the normal optical path, and therefore, by shortening the normal optical path, for example, an influence occurs such that a desired depth of field or the like cannot be obtained. For this reason, in some cases, it is difficult to change the position of the side wall portion 51a for simple downsizing.

On the other hand, as shown in the lower part of fig. 7, in the present embodiment, the second mirror 54 constitutes a side surface portion of the scanner unit 50 with respect to the sub-scanning direction in cooperation with the side wall portion 51 a. Therefore, the position of the side wall portion 51a can be changed without changing the position of the second mirror 54, and even when a configuration including the same normal optical path as that in the reference example is employed, the width of the scanner unit 50 with respect to the sub-scanning direction can be reduced. In the present embodiment shown in the lower part of fig. 7, the side wall portion 51a is shifted toward the center side of the scanner unit 50 by Δ W with respect to the sub-scanning direction, as compared with the reference example. When the scanner unit 50 is downsized, it becomes possible to reduce material costs and achieve an improvement in durability and a reduction in power consumption due to a reduction in load of a drive system for moving the scanner unit 50. Further, the required space for disposing the scanner unit 50 in the ADF 1 and the main body unit 30 becomes small, and therefore, it also leads to a reduction in the size of the image reading apparatus.

Incidentally, in a configuration in which the second mirror 54 is mounted in the first opening 51b provided in the housing of the scanner unit 50 from the outside of the first opening 51b, the second mirror 54 is accommodated in the recessed portion 51u of the housing to also effectively suppress stray light. That is, as shown in fig. 6, a part L6 of the light beam traveling toward the opposing portion between the reflection surface 54a of the second mirror 54 and the cartridge frame 51 is blocked by the peripheral wall of the recessed portion 51u or the side wall portion 51a at the periphery thereof.

(third mirror)

The third mirror 55 as another example of the reflection member will be described below. As shown in fig. 8, the cartridge frame 51 is provided with a second opening 51d at the other side wall portion 51c on the other side (opposite to the first opening 51 b) with respect to the sub-scanning direction. The second opening 51d is a hole penetrating the scanner unit 50 from the inside to the outside of the scanner unit 50. As seen in the sub-scanning direction, the opening width of the second opening 51d with respect to the main scanning direction is larger than the opening width of the second opening 51d with respect to the height direction.

The third mirror 55 is mounted to the outside of the scanner unit 50 with respect to the second opening 51d, the mounting method of the third mirror 55 is similar to that of the second mirror 55, and the third mirror 55 is similar to the second mirror 55, and the third mirror 55 is mounted to the cassette frame 51 by using a fixing member such as a plate spring made of metal. Similarly to the case of the second mirror 54, the entire opening area of the second opening 51d is covered with the reflection surface 55a of the third mirror 55 as viewed from the inside of the scanner unit 50. Therefore, even in the case where the light beam enters the second opening 51d from the outside of the scanner unit 50, the light beam is reflected to the outside of the scanner unit 50 by the reflection surface 55a of the third mirror 55, and therefore, the light beam does not cause stray light. Further, as shown in fig. 3, the cartridge frame 51 is provided with a recessed portion 51v as a mounting portion of the third mirror 55, and the third mirror 55 is similar to the second mirror in that: a second opening 51d is formed at the bottom of the concave portion 51v and a third mirror 55 is accommodated in the concave portion 51 v.

As shown in fig. 3 and 8, the cartridge frame 51 is provided with a first upper rib 301, a second upper rib 302, a lower rib 303, a first side wall 304, and a second side wall 305 that constitute the peripheral wall of the second opening 51 d. The first upper rib 301 and the second upper rib 302 are upper peripheral walls of the second opening 51d with respect to the height direction, and the lower rib 303 is a lower peripheral wall of the second opening 51d with respect to the height direction. Each of these ribs extends in the long side direction (main scanning direction) of the third mirror 55. The first side wall 304 and the second side wall 305 are one side peripheral wall and the other side peripheral wall of the second opening 51d with respect to the long side direction, respectively, and extend in the height direction at positions corresponding to the ends of the third mirror 55 with respect to the long side direction. Incidentally, the first upper rib 301 and the second upper rib 302 are provided on both sides of a reflection area 552 (part (a) of fig. 9) of a third mirror 55 described later with respect to the long side direction.

Each of the first upper rib 301, the second upper rib 302, the lower rib 303, the first scanner unit 304, and the second side wall 305 protrudes from the inner surface of the recessed portion 51 u. Also, each of the first upper rib 301, the second upper rib 302, the lower rib 303, the first side wall 304, and the second side wall 305 overlaps with the reflection surface 55a of the third mirror 55 when viewed from the inside of the scanner unit 50 in the direction perpendicular to the reflection surface 55 a.

Here, as shown in fig. 8, the opening shape of the second opening 51d is a protruding shape (reverse T shape) such that two portions different in width with respect to the main scanning direction are adjacent to each other. That is, the width (second width) with respect to the main scanning direction of the upper region (second portion) of the second opening 51d is set to a small value compared to the width (first width) with respect to the main scanning direction of the lower region (first portion) of the second opening 51d in fig. 8. The reflective surface 55a of the third mirror 55 has a rectangular shape having a size including the entire protruded opening area.

In the present embodiment, as shown in fig. 3 and 8, the light beam L3 traveling along the normal optical path is reflected twice between the second mirror 54 and the third mirror 55. Further, in the present embodiment, a reducing optical system is employed such that the width of the normal optical path with respect to the main scanning direction is reduced when the light beam approaches the lens unit 58.

That is, as shown in part (a) of fig. 9, the widths with respect to the main scanning direction of the first reflection area 541 of the second mirror 54, the first reflection area 551 of the third mirror 55, the second reflection area 542 of the second mirror 54, and the second reflection area 552 of the third mirror 55 become narrower in order. However, the first reflection area 541 of the second mirror 54 is an area of the reflection surface 54a on which the reflected light reflected by the first mirror through the normal light route is incident. First reflection region 551 of third mirror 55 is a region of reflection surface 55a on which reflected light once reflected by second mirror 54 through the normal optical path is incident. Second reflection area 542 of second mirror 54 is an area on which reflected light of reflection surface 54a reflected once by normal light route third mirror 55 is incident. Second reflection area 552 of third mirror 55 is an area of reflection surface 55a on which reflected light reflected twice by second mirror 54 through the normal optical path is incident.

As shown in fig. 3, in the normal optical path, the path of the light beam traveling from second mirror 54 to third mirror 55 for the second time is above the path of the light beam traveling from second mirror 54 to third mirror 55 for the first time. Therefore, the second opening 51d is formed in a protruding shape such that its width in the upper region is narrow and its width in the lower region is wide, so that it becomes possible to cover and hide an unnecessary region of the reflection surface 55a while securing a reflection region of light traveling along a normal optical path.

That is, as shown in fig. 8, the light beam L3a reflected by the second mirror 54 for the first time and traveling along the normal optical path and the light beam L3b reflected by the second mirror 54 for the second time are incident on the reflection surface 55a of the third mirror 55 and are reflected by the reflection surface 55a of the third mirror 55. On the other hand, the light beam L4 entering a position deviated from the normal optical path with respect to the main scanning direction is absorbed by the black cartridge frame 51 and is not reflected by the third mirror 55, and therefore does not reach the CCD59 a. Therefore, in a configuration in which light beams traveling along a normal optical path in different regions (551 and 552 of part (a) of fig. 9) of one reflection surface are reflected twice, it is desirable to reduce the width of the normal optical path in the reduction optical system so that the shape of the opening exposing the reflection surface is as small as possible. As a result, potential stray light deviating from the normal optical path can be effectively blocked.

Incidentally, the configuration in which it is desired to reduce the width of the normal optical path in the reduction optical system to set the shape of the opening is not limited to being applied to the same opening, but may be applied to the relationship between the first opening 51b and the second opening 51 d. That is, as shown in part (a) of fig. 9, in the present embodiment, the width with respect to the main scanning direction is narrower in the first reflection region 551 of the third mirror 55 than in the first reflection region 541 of the second mirror 54. Further, of the peripheries of the second openings 51d, the portions d1 and d1 adjacent to the reflective regions 551 in the main scanning direction are disposed inside the first reflective regions 541 of the second mirror 54 with respect to the main scanning direction. As a result, incident light outside the deflection region 551 with respect to the main scanning direction can be effectively blocked.

Similarly, the width with respect to the main scanning direction is narrower in second reflection area 552 of third mirror 55 than in second reflection area 542 of second mirror 54. Further, of the peripheries of the second openings 51d, the portions d2 and d2 adjacent to the reflective area 552 in the main scanning direction are disposed within the second reflective area 542 of the second mirror 54 with respect to the main scanning direction. As a result, incident light outside the deflection reflective area 552 with respect to the main scanning direction can be effectively blocked.

When the second mirror 54 is the first reflecting member in the present embodiment, the third mirror 55 is the second reflecting member in the present embodiment. In this case, the reflection surface 54a is a first reflection surface, and the reflection surface 55a is a second reflection surface. When the first reflection region 541 of the second mirror 54 is the first region in the present embodiment, the first reflection region 551 of the third mirror 55 is the second region disposed downstream of the first region in the reduction optical system in the present embodiment. Further, second reflective areas 542 and 552 of second mirror 54 and third mirror 55 are other examples of the first area and the second area, respectively.

(other embodiments)

In the above-described embodiment, the openings corresponding to the second mirror and the third mirror are provided in the housing of the scanner unit 50, but an opening corresponding to another reflecting member may be disposed. For example, an opening corresponding to at least one of first mirror 53, fourth mirror 56, and fifth mirror 57 is provided, and the reflective surface of the mirror mounted to the housing of scanner unit 50 from the outside of the housing may also be exposed to the inside of the housing through the opening. Further, in the above-described embodiment, the present invention can also be implemented in a form in which the opening corresponding to either one of the second mirror 54 and the third mirror 55 is omitted. Also, in these embodiments, a constitution is adopted in which the reflecting surface is surrounded by the periphery of the opening when viewed from the inside of the housing, so that stray light can be reduced by a simple structure.

Incidentally, in the above-described embodiment, the description is made by using a constitution in which the entire area of the first opening 51b is covered with the reflective surface 54a of the second mirror 54 and the entire area of the second opening 51d is covered with the reflective surface 55a of the third mirror 55 when seen from the inside of the housing. However, for example, as shown in part (b) of fig. 9, the first opening 51b and the second mirror 54 may also be in a positional relationship such that a part (51e) of the reflection area of the first opening 51b protrudes to the outside of the reflection surface 54a of the second mirror 54. In this case, for example, after the second mirror 54 is mounted to the cartridge frame 51, a gap between the protruding portion 51e of the opening area and the reflection surface 54a is filled with a member 62 such as rubber, thereby ensuring light shielding properties at the first opening 51 b. Even in this case, the first opening 51b is provided so as to surround the reflection surface 54a when viewed from the inside of the housing, so that a light shielding function can be imparted to the housing of the image reading unit at least in a portion other than the protruding portion 51 e.

Further, as for the reflecting member held outside the housing with respect to the opening, a light shielding layer may be formed of a paint or a coating film having high light shielding performance against visible light beams on the surface of the reflecting member opposite to the reflecting surface. In this case, unlike the above-described embodiment, most of the light beam L5 (fig. 6) traveling from the outside of the scanner unit 50 toward the opening is absorbed or reflected by the light shielding layer and does not reach the reflection surface. However, with this configuration, stray light can also be reduced with a simple structure.

Further, in the above-described embodiment, the image reading apparatus 103 assembled with the image forming apparatus is described, but the present invention is also applicable to an image reading apparatus that can be used alone. Further, the image reading unit explained in the above-described embodiments is not limited to an image reading unit for reading image information from a sheet as an original, but may also be applied as an apparatus for reading image information for another purpose. For example, the image reading unit may be used as a device for reading an image formed on a recording material in order to adjust the density of the image and to adjust the position and distortion of the image. Further, the image reading unit is also suitable for apparatuses that read and use image information, such as an authentication apparatus for banknotes and an apparatus for automatically sorting packages in a distribution warehouse.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.