JP2020156073A - Image reading unit, image reading device, and image forming device - Google Patents

Abstract

To reduce stray light with a simple configuration.SOLUTION: An image reading unit (50) includes: a housing (51 or 52a) that holds a reading unit (59a) and has an entrance (701) through which light reflected by an object passes; and a reflection member (54) that has a reflection surface (54a) for reflecting the light which has passed through the entrance and forms an optical path which guides the reflected light from the object to the reading unit. The housing is provided with an opening that passes through from the inside to outside of the housing. The reflection member is held on the outside of the housing with respect to the opening so that at least part of the reflection surface is exposed to the outside of the housing via the opening.SELECTED DRAWING: Figure 3

Description

The present invention relates to an image reading unit that reads image information from an object, an image reading device that reads image information from a sheet, and an image forming device that forms an image on a sheet.

An image reading unit used in a document scanner or a copier reads image information from a document by irradiating the document with light, forming an image of the reflected light from the document on an image sensor, and performing photoelectric conversion. When a charge coupling element (CCD) is used as the image sensor, a plurality of reflecting members arranged in the housing of the image reading unit form a normal optical path for guiding the reflected light from the document to the image sensor while repeatedly reflecting the light. To. If there is light (stray light) that reaches the image sensor without following the normal optical path, there is a risk that noise will occur in the read image information (flare) and double image reflection (ghost) will occur.

In order to reduce stray light, conventional measures have been taken such as forming the housing black or increasing the airtightness of the housing so as not to take in light other than the reflected light from the document as much as possible. In Patent Document 1, a light-shielding portion is provided between a light guide member that irradiates light from a light source toward a document and a first reflection mirror that reflects light from a document in the vicinity of the light guide member. A configuration is described in which light that tries to enter the inside of the scanning unit is blocked without passing through the first reflection mirror.

Japanese Unexamined Patent Publication No. 2016-5090

As a method for reducing stray light, it is conceivable to arrange a light-shielding member around the reflective surface of the reflective member and block light rays deviating from the normal optical path by the light-shielding member. However, there is a concern that the cost will increase and the size of the device will increase due to the additional arrangement of the light shielding member.

Therefore, an object of the present invention is to reduce stray light with a simple configuration.

One aspect of the present invention includes an illumination unit that irradiates an object with light, a reading unit that photoelectrically converts the reflected light emitted by the illumination unit and reflected by the object, and reads image information of the object. It has a housing that holds the reading unit and has an inlet through which the light reflected by the object passes, and a reflecting surface that reflects the light that has passed through the entrance, and the reflected light from the object is transmitted to the reading unit. A reflective member that forms a guiding light path is provided, and the housing is provided with an opening that penetrates from the inside to the outside of the housing, and the reflective member has at least a part of the reflective surface of the opening. The image reading unit is held on the outside of the housing with respect to the opening so as to be exposed to the inside of the housing through the image reading unit.

According to the present invention, stray light can be reduced by a simple configuration.

The schematic diagram of the printer which concerns on embodiment of this disclosure. The schematic diagram which shows the scanner main body of an image reader. The schematic which shows the cross-sectional structure of a scanner unit. The perspective view for demonstrating the mounting method of the 2nd mirror. The perspective view which shows the 2nd mirror attached to the box frame. The schematic diagram which shows the structure of the 2nd mirror and its surroundings. The figure for making a comparison between a reference example and this embodiment. The perspective view which shows the 3rd mirror attached to the box frame. A schematic diagram (a) showing the positional relationship of the reflection regions of the second mirror and the third mirror, and a diagram (b) showing a modified example of the present embodiment. The figure which shows the arrangement relationship between a 2nd mirror and a 1st opening.

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

First, the schematic configuration of the printer 101, which is the image forming apparatus of the present embodiment, will be described with reference to FIG. As shown in FIG. 1, the printer 101 includes a printer main body 101A and an image reading device 103. The image reading device 103 arranged above the printer main body 101A includes a main body unit 30 and an ADF 1 as described in detail later, and optically scans the document D to read image information. "ADF" represents an automatic document feeder. The manuscript D is paper such as paper and envelopes, plastic film such as sheets for overhead projectors, and sheets such as cloth. The image information converted into an electric signal by the image reader 103 is transferred to the control unit 132 provided in the printer main body 101A.

The printer main body 101A has an image forming unit 133 that forms an image on the sheet P that is a recording medium, and a sheet feeding unit 134 that feeds the sheet P to the image forming unit 133. The sheet feeding unit 134 includes sheet storage units 137a, 137b, 137c, and 137d that can store sheets of different sizes. The sheets stored in each sheet storage unit are fed out by the pickup roller 112, separated one by one by the feed roller 113a and the retard roller 113b, and delivered to the corresponding transfer roller pair 131. Then, the sheet P is transferred to the registration roller pair 136 by being sequentially delivered to the plurality of transfer roller pairs 131 arranged along the sheet transfer path.

The sheet P placed on the bypass tray 137e by the user is fed to the inside of the printer main body 101A by the feeding roller 138, and is conveyed to the registration roller pair 136. The registration roller pair 136 stops the tip of the sheet P to correct the skew, and restarts the transfer of the sheet P in accordance with the progress of the image forming operation, which is the process of forming the toner image by the image forming unit 133.

The image forming unit 133 that forms an image on the sheet P is an electrophotographic image forming unit including a photosensitive drum 121 that is a photoconductor. The photosensitive drum 121 is rotatable along the transport direction of the sheet P, and around the photosensitive drum 121, a charging device 118, an exposure device 123, a developing device 124, a transfer charging device 125, a separation charging device 126, and a cleaner 127 are provided. Is placed. The charger 118 uniformly charges the surface of the photosensitive drum 121, and the exposure device 123 exposes the photosensitive drum 121 based on the image information input from the image reading device 103 or the like to form an electrostatic latent image on the drum. To do.

The developing device 124 contains a developer containing toner, and develops an electrostatic latent image into a toner image by supplying charged toner to the photosensitive drum 121. The toner image supported on the photosensitive drum 121 is transferred to the sheet P conveyed from the registration roller pair 136 by the bias electric field formed by the transfer charger 125. The sheet P to which the toner image is transferred is separated from the photosensitive drum 121 by the bias electric field formed by the separation charger, and is conveyed toward the fixing portion 129 by the pre-fixing conveying portion 128. Adhesions such as transfer residual toner remaining on the photosensitive drum 121 without being transferred to the sheet P are removed by the cleaner 127, and the photosensitive drum 121 prepares for the next image-forming operation.

The sheet P transported to the fixing portion 129 undergoes a fixing process including pressurization and heating of the toner image while being sandwiched between the roller pairs and conveyed. As a result, the toner melts and then sticks, so that the image is fixed on the sheet P. When the image output is completed, the sheet P from which the fixed image is obtained is discharged to the discharge tray 130 protruding outward from the printer main body 101A via the discharge roller pair 116. When an image is formed on the back surface of the sheet P in double-sided printing, the front surface and the back surface of the sheet P that has passed through the fixing portion 129 are exchanged by the reversing portion 139, and the sheet P is conveyed to the registration roller pair 136 by the double-sided conveying portion 140. To. Then, the sheet P whose image is formed again by the image forming unit 133 is discharged to the discharge tray 130.

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

(Image reader)
Next, the configuration of the image reading device 103 will be described with reference to FIGS. 1 to 3. As shown in FIG. 1, the ADF 1 conveys the document D placed on the document feeding tray 2 toward the document ejection tray 3. The ADF1 can be opened and closed with respect to the main body unit 30, and the main body unit 30 is fixed to the printer main body 101A.

As shown in FIG. 2, the main body unit 30 has a frame 30a that also serves as an exterior member, and a platen glass 31 and a platen glass 31a are arranged on the upper surface of the frame 30a. The platen glass 31 is the mounting table of the present embodiment. Inside the frame 30a, a scanner unit 50, which is an image reading unit of the present embodiment, is held. The scanner unit 50 is configured to be movable in parallel with the platen glass 31 by a wire or belt (not shown) driven by a motor.

As shown in FIG. 3, the scanner unit 50 is a CCD (Charge Coupled Devices, charge-coupled device) type image reading unit. The scanner unit 50 includes a box frame 51, a lighting 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. There is. On the CCD substrate 59, CCD59a, which is an example of an image pickup device, is arranged along the main scanning direction. The lighting unit 52 is the lighting unit of the present embodiment, and the CCD 59a is the reading unit of the present embodiment. Although the CCD59a is illustrated here as an example of the image pickup device, an image pickup device using CMOS (complementary metal oxide film semiconductor) can also be used.

The lighting unit 52 is attached to the upper part of the box frame 51 of the scanner unit 50. The illumination unit 52 includes an illumination frame 52a, a light emitting element (for example, a light emitting diode) (not shown), and two light guide units 60L and 60R. The lights L1 and L2 emitted by the light emitting element are irradiated to the document D as an object for reading image information in a state of being uniformly diffused in the main scanning direction by the light guide units 60L and 60R. The illumination frame 52a that constitutes the housing (frame) of the scanner unit 50 together with the box frame 51 includes an inlet (opening) 701. The inlet 701 that receives the reflected light from the object inside the scanner unit 50 is not limited to the opening of the housing, and may be made of 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 the "document irradiation position F". However, the sub-scanning direction is a direction perpendicular to the main scanning direction, and in the present embodiment, it is a moving direction when the scanner unit 50 moves below the platen glass 31. Further, the reading surface is a predetermined height (in which the scanner unit 50 can read image information with high accuracy in the height direction (depth of field direction) perpendicular to the main scanning direction and the sub-scanning direction). It is a virtual plane that extends over the object point position of the optical system. The reading surface in the present embodiment corresponds to, for example, the lower surface of the document D in a state of being stationary on the platen glass.

The light reflected by the document D travels inside the scanner unit 50 through the entrance (opening) 701. The light that travels inside the scanner unit 50 through the inlet 701 is reflected by the mirrors 53 to 57. The five mirrors 53 to 57 and the lens unit 58 form an optical path that guides the reflected light from the document D to the CCD substrate 59. As the mirrors 53 to 57, which are examples of the reflective members, for example, those mirrors formed by forming a vapor-deposited aluminum film on a support such as glass to form a reflective surface are used. The reflected light (light ray L3) reflected by the document D at the document 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. Then, an image is formed on the CCD 59a.

The CCD59a receives the light ray L3 and photoelectrically converts it into an electric signal representing an image of the original D. The image information of the document D read by the CCD 59a is transmitted to the control unit 132 of the printer main body 101A and used for image formation by the image forming unit 133.

Hereinafter, among the scattered light reflected by the document D, the CCD 59a is traced from the document irradiation position F to 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. The path of light leading to is called the "regular optical path". The light beam L3 illustrated in FIG. 3 is a light beam representing a light beam that reaches the CCD59a by following a normal optical path from the document irradiation position F. Further, the light that reaches the CCD 59a by a path deviating from the normal optical path is regarded as stray light. An example of such stray light is a light beam that enters the inside of the scanner unit 50 from a portion other than the entrance 701 (the opening between the light guide units 60R and 60L) of the scanner unit 50 facing the document irradiation position F. Further, light rays scattered by the box frame 51 outside the reflection region of any of the mirrors after passing through the opening of the scanner unit 50 facing the document irradiation position F can also become stray light.

The space inside the box frame 51 is covered by the lighting frame 52a of the lighting unit 52 at the upper part and by the lower cover 63 at the lower part. Further, when viewed in the main scanning direction, the CCD 59a is arranged in a space surrounded by a recess provided in the box frame 51 and a substrate main body 59b of the CCD substrate 59.

Further, the box frame 51 is provided with a first opening 51b and a second opening 51d, which will be described later, and each opening is closed by a second mirror 54 and a third mirror 55, respectively. Therefore, the second mirror 54 and the third mirror 55 of the present embodiment, together with the box frame 51, the lighting frame 52a of the lighting unit 52, the lower cover 63, and the substrate body 59b, have an outer shell that separates the inside and the outside of the scanner unit 50. It constitutes a part of. The inside of the scanner unit 50 is a space in which a normal optical path and a reading unit are housed. However, the configuration of the illustrated housing is only an example, and the shape and arrangement can be changed as appropriate.

The image reading device 103 configured in this way has a scanning mode in which the document D is scanned while the document D is fed by the ADF1 and a fixed reading mode in which the document D placed on the platen glass 31 is scanned. , The image information is read from the sheet as the document D.

The scanning mode is selected when the apparatus detects the document D placed on the document feeding tray 2, or when the user explicitly instructs the printer body 101A by the operation panel or the like. In this case, with the scanner unit 50 below the platen glass 31a, the ADF1, which is an example of the transport device, feeds the documents D placed on the document feed tray 2 one by one, and the scanner unit 50 transports the documents D. Image information is read from the original D. That is, in the scanning mode, the document D is scanned by transporting the document D to the scanner unit 50 whose position is fixed in the sub-scanning direction.

On the other hand, the fixed reading mode is selected when the apparatus detects the document D placed on the platen glass 31 or when the user explicitly instructs the printer body 101A by the operation panel or the like. In the fixed reading mode, the user first opens the ADF1 to place the document D on the platen glass 31, and closes the ADF1 to position the document D on the platen glass 31. Then, the scanner unit 50 reads the image information from the document D placed on the platen glass 31 while moving along the platen glass 31. That is, in the fixed reading mode, the scanner unit 50 scans the document D while moving in the sub-scanning direction with respect to the document whose position is fixed.

The scanner unit 50 may be mounted on an image reading device capable of executing only one of the scanning mode and the fixed reading mode. Further, the scanner unit 50 may be additionally arranged inside the ADF1 so that the image information can be read by the two scanner units from both sides of the document conveyed by the ADF1.

(2nd mirror)
Hereinafter, the mounting structure of the mirror arranged in the scanner unit 50 will be described. First, the second mirror 54, which is an example of the reflective member, will be described. As shown in FIG. 4, the box frame 51 includes a first opening 51b on one side wall portion 51a in the sub-scanning direction. The first opening 51b is a hole penetrating 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, when viewed from the sub-scanning direction, the opening width of the first opening 51b in the main scanning direction is larger than the opening width in the height direction.

The second mirror 54 is attached to the box frame 51 from the outside of the box frame 51 so as to cover the entire area of the rectangular first opening 51b. In the present embodiment, the second mirror 54 is fixed to the box frame 51 at both ends in the main scanning direction by fixing members 61, 61 which are metal leaf springs. The same fixing method is used for other mirrors (53, 55, 56, 57). However, the method of attaching the reflective member is not limited to this, and the second mirror 54 may be fixed to the box frame 51 using, for example, an adhesive.

As shown in FIG. 5, the reflecting surface 54a of the second mirror 54 is exposed to the inside of the scanner unit 50 through the first opening 51b. The first opening 51b is set so that the light ray L3 following the normal optical path reaches the reflection surface 54a of the second mirror 54, but the light ray L4 deviating from the normal optical path does not reach the reflection surface 54a. That is, the light ray L3 is reflected by the reflecting surface 54a and reaches the third mirror 55, but the light ray L4 is absorbed by the black box frame 51 and does not reach the third mirror 55. The box frame 51 is made of a member that blocks light. Therefore, the portion of the box frame 51 surrounding the first opening 51b has a light-shielding function that blocks the light rays L4 deviating from the normal optical path and does not allow the light rays L4 to reach the CCD 59a.

Further, as shown in FIGS. 5 and 6, the second mirror 54 is arranged so as to cover the entire inner region of the first opening 51b with the reflecting surface 54a when viewed from the inside of the scanner unit 50. Specifically, the reflecting surface 54a of the second mirror 54 has a rectangular shape including the rectangular first opening 51b.

With this configuration, even when the light ray L5 is incident from the outside of the scanner unit 50 toward the first opening 51b, the light ray L5 is reflected to the outside of the scanner unit 50 by the reflecting surface 54a of the second mirror 54. That is, since the light ray L5 does not enter the inside of the scanner unit 50, it does not reach the CCD 59a. Further, since the reflective surface 54a is surrounded by the peripheral edge of the first opening 51b when viewed from the inside of the scanner unit 50, the light rays coming from the outside of the scanner unit 50 toward the periphery of the first opening 51b are black. It is absorbed by the box frame 51. Therefore, in a configuration in which the first opening 51b is provided in the housing of the scanner unit 50 and the second mirror 54 is attached from the outside of the housing, it is possible to prevent stray light from entering through the first opening 51b. it can. That is, by using a part of the housing of the scanner unit 50 to block stray light in the vicinity of the reflective member, it is possible to reduce stray light with a simple configuration.

Further, in the present embodiment, at least a part of the peripheral edge of the first opening 51b when viewed from the inside of the scanner unit 50 is located inside the peripheral edge of the reflecting surface 54a (that is, the first opening 51b is formed). The peripheral wall is configured to overlap the reflective surface 54a). That is, the peripheral wall that is a part of the box frame 51 that forms the first opening 51b overlaps with the reflecting surface 54a of the second mirror 54 when viewed from the inside of the scanner unit 50. Here, the peripheral wall forming the first opening 51b is composed of an upper rib 201, a lower rib 202, a first side wall 203, and a second side wall 204 as shown in FIGS. 3 to 6. The upper rib 201 and the lower rib 202 are upper and lower peripheral walls in the height direction of the first opening 51b, respectively, and extend along the longitudinal direction (main scanning direction) of the second mirror 54. The first side wall 203 and the second side wall 204 are peripheral walls on one side and the other side in the longitudinal direction of the first opening 51b, respectively, and are along the height direction at positions corresponding to the longitudinal ends of the second mirror 54. Is extending.

Each of the upper rib 201, the lower rib 202, the first side wall 203, and the second side wall 204 protrudes from the inner surface of the recess 51u. Further, each of the upper rib 201, the lower rib 202, the first side wall 203, and the second side wall 204 overlaps the reflecting surface 54a when viewed from the inside of the scanner unit 50 in the direction perpendicular to the reflecting surface 54a of the second mirror 54. ing. FIG. 10 is a view of the second mirror 54 viewed from the inside of the scanner unit 50. In FIG. 10, the dotted line indicates the outer edge of the reflecting surface 54a of the second mirror 54. In FIG. 10, the solid line shows the peripheral edge of the first opening 51b.

With such a configuration, stray light that enters through the gap between the reflecting surface 54a and the box frame 51 can be effectively suppressed. It is preferable that the reflective surface 54a is in contact with the outer surface of the box frame 51 around the first opening 51b, but the reflective surface 54a and the box frame 51 are included as long as the stray light can be sufficiently shielded. Small gaps between them are acceptable.

As shown in FIGS. 3 and 6, the box frame 51 is provided with a recess 51u which is a mounting portion of the second mirror 54. The recess 51u has a concave shape that is recessed from the outside to the inside of the scanner unit 50 (that is, from left to right in the figure) in a direction intersecting the main scanning direction (particularly, in the sub-scanning direction in the present embodiment). is there. The first opening 51b is formed at the bottom of the recess 51u. Further, the second mirror 54 is housed in the recess 51u with the second mirror 54 attached to the box frame 51.

As shown in the upper part of FIG. 7 as a reference example, it is conceivable that the entire second mirror 54 is arranged inside the housing of the scanner unit 50, but in such a configuration, the scanner is compared with the present embodiment. The unit 50 becomes large. That is, in this reference example, since the side wall portion 51a on one side in the sub-scanning direction needs to cover the entire second mirror 54 when viewed from the sub-scanning direction, the side wall portion 51a is viewed from the main scanning direction. The second mirror 54 and the second mirror 54 are aligned in the sub-scanning direction. Therefore, when the side wall portion 51a is brought closer to the other side wall portion, the second mirror 54 also needs to be moved, but since the position change of the second mirror 54 involves the change of the normal optical path, for example, the normal optical path becomes shorter. This causes an effect that the desired depth of field cannot be obtained. Therefore, it may be difficult to change the position of the side wall portion 51a simply for the purpose of miniaturization.

On the other hand, as shown in the lower part of FIG. 7, in the present embodiment, the second mirror 54 and the side wall portion 51a form a side surface portion of the scanner unit 50 in the sub-scanning direction. Therefore, the position of the side wall portion 51a can be changed without changing the position of the second mirror 54, and even if the configuration has the same normal optical path as the reference example, the width of the scanner unit 50 in the sub-scanning direction. Can be made smaller. In the illustrated example, the side wall portion 51a is closer to the center side of the scanner unit 50 in the sub-scanning direction by ΔW than in the reference example. When the scanner unit 50 is miniaturized, it is possible to reduce the material cost, improve the durability by reducing the load of the drive system for moving the scanner unit 50, and reduce the power consumption. Further, since the required space for arranging the scanner unit 50 in the ADF 1 and the main body unit 30 becomes smaller, it leads to the miniaturization of the image reading device.

In a configuration in which the second mirror 54 is attached to the first opening 51b provided in the housing of the scanner unit 50 from the outside, accommodating the second mirror 54 in the recess 51u of the housing suppresses stray light. It is also effective in doing so. That is, as shown in FIG. 6, a part L6 of the light beam directed to the opposite portion between the reflecting surface 54a of the second mirror 54 and the box frame 51 is blocked by the peripheral wall of the recess 51u or the side wall portion 51a around the recess 51u.

(3rd mirror)
Next, the third mirror 55, which is another example of the reflective member, will be described. As shown in FIG. 8, the box frame 51 has a second opening 51d on the side wall 51c on the other side (opposite to the first opening 51b) in the sub-scanning direction. The second opening 51d is a hole penetrating from the inside to the outside of the scanner unit 50. When viewed from the sub-scanning direction, the opening width of the second opening 51d in the main scanning direction is larger than the opening width in the height direction.

The third mirror 55 is attached to the outside of the housing of the scanner unit 50 with respect to the second opening 51d. The method of attaching the third mirror 55 is the same as that of the second mirror, and the third mirror 55 is fixed to the box frame 51 by, for example, a fixing member using a metal leaf spring. Similar to the second mirror 54, when viewed from the inside of the scanner unit 50, the entire opening region of the second opening 51d is covered by the reflecting surface 55a of the third mirror 55. Therefore, even when a light beam is incident from the outside of the scanner unit 50 toward the second opening 51d, it is reflected to the outside of the scanner unit 50 by the reflecting surface 55a of the third mirror 55, so that it does not become stray light. Further, as shown in FIG. 3, the box frame 51 is provided with a recess 51v as a mounting portion of the third mirror 55, and the second opening 51d is formed at the bottom of the recess 51v, and the third The point that the mirror 55 is housed in the recess 51v is the same as that of the second mirror 54.

As shown in FIGS. 3 and 8, the box frame 51 includes 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 form a peripheral wall of the second opening 51d. It has. The first upper rib 301 and the second upper rib 302 are the upper peripheral wall in the height direction of the second opening 51d, and the lower rib 303 is the lower peripheral wall in the height direction of the second opening 51d. Also extends along the longitudinal direction (main scanning direction) of the third mirror 55. The first side wall 304 and the second side wall 305 are peripheral walls on one side and the other side in the longitudinal direction of the second opening 51d, respectively, and are along the height direction at positions corresponding to the longitudinal ends of the third mirror 55. Is extending. The first upper rib 301 and the second upper rib 302 are provided on both sides of the second reflection region 552 (see FIG. 9A) of the third mirror 55, which will be described later in the longitudinal direction.

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 protrudes from the inner surface of the recess 51v. Further, 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 is viewed from the inside of the scanner unit 50 in a direction perpendicular to the reflection surface 55a of the third mirror 55. It overlaps with the reflective surface 55a.

Here, as shown in FIG. 8, the opening shape of the second opening 51d has a convex shape (T-shaped upside down) in which two portions having different widths in the main scanning direction are adjacent to each other. ing. That is, the width of the upper region (second portion) in the main scanning direction as compared with the width (first width) of the lower region (first portion) of the second opening 51d in FIG. 8 in the main scanning direction. (Second width) is set small. The reflecting surface 55a of the third mirror 55 has a rectangular shape having a size that covers the entire convex opening region.

In the present embodiment, as shown in FIGS. 3 and 8, the light ray L3 following the normal optical path is reflected twice between the second mirror 54 and the third mirror 55, respectively. Further, in the present embodiment, a reduction optical system is adopted, and the width of the normal optical path in the main scanning direction is reduced as it approaches the lens unit 58.

That is, as shown in FIG. 9A, the first reflection region 541 of the second mirror 54, the first reflection region 551 of the third mirror 55, the second reflection region 542 of the second mirror 54, and the third mirror 54. The width of the second reflection region 552 of the mirror 55 in the main scanning direction becomes narrower in this order. However, the first reflection region 541 of the second mirror 54 is a region of the reflection surface 54a on which the reflected light reflected by the first mirror 53 follows the normal optical path. The first reflection region 551 of the third mirror 55 is a region of the reflection surface 55a on which the first reflection light reflected by the second mirror 54 follows the normal optical path. The second reflection region 542 of the second mirror 54 is a region of the reflection surface 54a on which the reflected light reflected for the first time by the third mirror 55 follows the normal optical path. The second reflection region 552 of the third mirror 55 is a region of the reflection surface 55a on which the reflected light reflected for the second time by the second mirror 54 follows the normal optical path.

As shown in FIG. 3, the path from the second mirror 54 to the third mirror 55 for the second time in the normal optical path passes above the path from the second mirror 54 to the third mirror 55 for the first time. Therefore, by making the second opening 51d convex, narrowing the width of the upper region and widening the lower region, the reflection region of light following the normal optical path is secured, and the reflection surface 55a is unnecessary. It is possible to cover up various areas.

That is, as shown in FIG. 8, the light ray L3a reflected by the second mirror 54 for the first time and following the normal optical path and the light ray L3b reflected by the second mirror 54 and following the normal optical path for the second time are both. It is reflected by being incident on the reflecting surface 55a of the third mirror 55. On the other hand, the light ray L4 incident at a position deviating from the normal optical path in the main scanning direction does not reach the CCD 59a because it is absorbed by the black box frame 51 and is not reflected by the third mirror 55. In this way, the shape of the opening where the reflecting surface is exposed is reduced in the configuration in which the light rays following the normal optical path are reflected a plurality of times to different regions (551 and 552 in FIG. 9A) of one reflecting surface. The width of the normal optical path in the optical system is expected to be reduced to the minimum necessary. This makes it possible to effectively block potential stray light that deviates from the normal optical path.

The point of setting the shape of the opening in anticipation of the reduction of the width of the normal optical path in the reduction optical system is not limited to the same opening, but also applies to the relationship between the first opening 51b and the second opening 51d. Will be done. That is, as shown in FIG. 9A, in the present embodiment, the width of the first reflection region 551 of the third mirror 55 in the main scanning direction is wider than that of the first reflection region 541 of the second mirror 54. Becomes narrower. Then, in the peripheral edge of the second opening 51d, the portions d1 and d1 aligned with the reflection region 551 in the main scanning direction are arranged inside the range of the first reflection region 541 of the second mirror 54 with respect to the main scanning direction. .. As a result, it is possible to effectively block the light incident on the outside of the reflection region 551 with respect to the main scanning direction.

Similarly, the width of the second reflection region 552 of the third mirror 55 in the main scanning direction is narrower than that of the second reflection region 542 of the second mirror 54. Then, in the peripheral edge of the second opening 51d, the portions d2 and d2 aligned with the reflection region 552 in the main scanning direction are arranged inside the range of the second reflection region 542 of the second mirror 54 with respect to the main scanning direction. .. As a result, it is possible to effectively block the light incident on the outside of the reflection region 552 with respect to the main scanning direction.

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

(Other embodiments)
In the above embodiment, the openings corresponding to the second mirror 54 and the third mirror 55 are provided in the housing of the scanner unit 50, but the openings corresponding to other reflective members may be arranged. For example, an opening corresponding to at least one of the first mirror 53, the fourth mirror 56, and the fifth mirror 57 is provided, and the reflective surface of the mirror attached from the outside of the housing of the scanner unit 50 passes through the opening. It may be exposed inside the housing. Further, in the above embodiment, it is also possible to carry out the present technique 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 examples, when viewed from the inside of the housing, the reflective surface is configured to be surrounded by the peripheral edge of the opening, so that stray light can be reduced with a simple configuration.

In the above embodiment, when viewed from the inside of the housing, the entire area of the first opening 51b is covered by the reflection surface 54a of the second mirror 54, and the entire area of the second opening 51d is the third mirror 55. It has been described as being covered by the reflective surface 55a. However, for example, as shown in FIG. 9B, the positional relationship may be such that a part (51e) of the opening region of the first opening 51b projects to the outside of the reflecting surface 54a of the second mirror 54. In this case, for example, after the second mirror 54 is attached to the box frame, the light-shielding property of the first opening 51b is ensured by filling the gap between the protruding portion 51e of the opening region and the reflecting surface 54a with a member 62 such as rubber. Will be done. Even in this case, since the first opening 51b is provided so as to surround the reflective surface 54a when viewed from the inside of the housing, the housing of the image reading unit is provided with a light-shielding function at least in a portion other than the protruding portion 51e. You can have it.

Further, with respect to the reflective member held on the outside of the housing with respect to the opening, a light-shielding layer may be formed on the surface opposite to the reflective surface with a paint or a coating having a high light-shielding property against visible light. In this case, most of the light rays L5 (see FIG. 6) coming from the outside of the scanner unit 50 toward the opening are absorbed or reflected by the light-shielding layer and do not reach the reflecting surface unlike the above-described embodiment. However, even with such a configuration, it is possible to reduce stray light with a simple configuration.

Further, in the above embodiment, the image reading device 103 assembled to the image forming device has been described, but the present technology can also be applied to an image reading device that can be used independently. Further, the image reading unit described in the above embodiment is not limited to reading image information from a sheet as a document, and can also be applied as a device for reading image information for other purposes. For example, in an image forming apparatus, it can be used as an apparatus for reading an image formed on a recording medium in order to adjust the image density, the position of the image, and the distortion. It can also be applied to devices that read and use image information other than image forming devices, such as devices for determining the authenticity of banknotes and devices for automating cargo sorting in distribution warehouses.

1 ... Conveyor device (ADF) / 31 ... Mounting table (Original table glass) / 50 ... Image reading unit (scanner unit) / 51 ... Housing (box frame) / 51b ... Opening, first opening / 51d ... Opening Part, 2nd opening / 51u, 51v ... Recessed part / 52 ... Lighting part (lighting unit) / 54 ... Reflective member, 1st reflective member (2nd mirror) / 54a ... Reflective surface, 1st reflective surface / 541, 542 ... 1st region (reflection region) / 55 ... Reflective member, 2nd reflective member (3rd mirror) / 551, 552 ... 2nd region (reflection region) / 55a ... Reflective surface, 2nd reflective surface / 59a ... Reading unit (CCD) / 101 ... Image forming device (printer) / 103 ... Image reading device / 133 ... Image forming means (image forming unit) / 701 ... Entrance

Claims (11)

A lighting unit that irradiates an object with light,
A reading unit that reads the image information of the object by photoelectrically converting the reflected light that is irradiated by the illumination unit and reflected by the object.
A housing that holds the reading unit and has an inlet through which light reflected by the object passes.
A reflecting member having a reflecting surface that reflects light that has passed through the inlet and forming an optical path that guides the reflected light from the object to the reading unit is provided.
The housing is provided with an opening that penetrates from the inside to the outside of the housing.
The reflective member is held on the outside of the housing with respect to the opening so that at least a part of the reflective surface is exposed inside the housing through the opening.
An image reading unit characterized by this. When viewed from the inside of the housing, the entire area inside the opening is covered with the reflective surface.
The image reading unit according to claim 1. When viewed from the inside of the housing, at least a part of the peripheral edge of the opening is located inside the peripheral edge of the reflective surface.
The image reading unit according to claim 1 or 2. The opening and the reflective member extend along the main scanning direction of the reading unit.
The housing is provided with a recess recessed from the outside to the inside of the housing in a direction intersecting the main scanning direction.
The opening is formed at the bottom of the recess and
The reflective member is held in the housing in a state of being housed in the recess.
The image reading unit according to any one of claims 1 to 3. The opening is rectangular
The reflective surface of the reflective member has a rectangular shape including the opening when viewed from the inside of the housing.
The image reading unit according to any one of claims 1 to 4. The opening has a first portion having a first width in the main scanning direction of the reading unit and a second portion having a second width narrower than the first width in the main scanning direction. The shape is adjacent to the direction that intersects the directions,
The reflective surface of the reflective member has a shape including the first portion and the second portion when viewed from the inside of the housing.
The image reading unit according to any one of claims 1 to 4. The reflective member is a part of a reduction optical system configured so that the width of the optical path in the main scanning direction is narrowed when heading toward the reading unit along a regular optical path.
When the reflective member and the opening are directed toward the reading along a regular optical path, the light reflected by the reflective surface at the first portion of the opening is then subjected to the first portion of the opening. Two parts are arranged so as to be reflected by the reflecting surface.
The image reading unit according to claim 6. When the opening is the first opening, the reflective member is the first reflective member, and the reflective surface is the first reflective surface,
A second reflecting member having a second reflecting surface that reflects light and forming an optical path that guides the reflected light from the object to the reading unit.
A second opening provided in the housing and penetrating from the inside to the outside of the housing is further provided.
The second reflective member is provided on the outside of the housing with respect to the second opening so that at least a part of the second reflective surface is exposed inside the housing through the second opening. Retained,
The image reading unit according to any one of claims 1 to 7. The first reflecting member and the second reflecting member are one of reduction optical systems configured so that the width of the optical path in the main scanning direction of the reading unit is narrowed when heading toward the reading unit along a regular optical path. It is a part, and is arranged so that the light reflected in the first region of the first reflecting surface along the normal optical path is incident on the second region of the second reflecting surface.
Within the peripheral edge of the second opening in the main scanning direction, the portion aligned with the second region in the main scanning direction is located inside both ends of the first region in the main scanning direction.
The image reading unit according to claim 8. At least one of the transport device for transporting the sheet and the mounting table on which the sheet is placed,
The image reading unit according to any one of claims 1 to 9 for reading image information from a sheet.
An image reader characterized by this. The image reading unit according to any one of claims 1 to 9,
An image forming means for forming an image on a sheet,
An image forming apparatus characterized in that.

Images