JP7098767B2 - Image reader and image forming device - Google Patents

Description

The present invention relates to an image reading device that irradiates a sheet with light to read an image of the sheet , and an image forming device including the image reading device.

As a configuration for illuminating a document in an image reading device, a configuration including a substrate provided with a plurality of light emitting elements and a light guide for guiding light output from the light emitting elements toward the document is known. When the light emitting element is turned on for image reading, the temperature of the light emitting element rises. When the temperature of the light emitting element rises, the temperature of the substrate provided with the light emitting element and the light guide arranged in the vicinity of the light emitting element also rises. The substrate and the light guide are made of different materials, and the substrate and the light guide have different coefficients of linear expansion. Therefore, the amount of elongation at the time of temperature rise differs between the substrate and the light guide, and the light guide warps with respect to the substrate. If the light guide warps with respect to the substrate, the positional relationship between the light emitting element and the light guide will be displaced, and as a result, the lighting efficiency may decrease and the illuminance distribution may fluctuate.

The following techniques are known to solve this problem. The substrate is a flat metal member, and the facing surface between the light guide and the substrate is configured so that the heat from the light emitting element is diffused to the flat metal member by the adhesive member. By doing so, the warp of the light guide is suppressed (Patent Document 1).

Japanese Unexamined Patent Publication No. 2013-223186

However, in the configuration of Patent Document 1, the facing surface between the substrate (metal flat member) and the light guide is fixed by the adhesive member. Therefore, if the light emitting element is continuously lit and the substrate cannot sufficiently diffuse the heat from the light emitting element, a situation may occur in which the light guide warps with respect to the substrate. In view of the above problems, it is an object of the present invention to prevent the light guide from warping with respect to the substrate.

An image reader for solving the above problems is
A lighting unit that illuminates the image surface of the sheet with light,
An image reading unit that reads an image of the sheet based on the reflected light from the sheet,
Have,
The lighting unit is
A substrate including an upper surface provided with a plurality of light emitting elements arranged in a first direction and a side surface adjacent to the upper surface and intersecting the first direction .
A light guide that guides the light emitted from the plurality of light emitting elements to the sheet, and includes a first surface facing the side surface thereof, and a light guide.
Equipped with
The side surface is a surface located at the end of the substrate in the first direction.
The light guide includes a second surface of the substrate facing the top surface and a third surface facing the bottom surface of the substrate opposite the top surface.
The second surface and the third surface are characterized by being adjacent to the first surface.

According to the present invention, it is possible to prevent the light guide from warping with respect to the substrate.

The figure explaining the image forming apparatus which concerns on Embodiment 1. Enlarged sectional view of the reading unit according to the first embodiment. A control block diagram of the image forming apparatus according to the first embodiment. Schematic configuration diagram of the lighting unit according to the first embodiment Side view of the state before mounting the board with respect to the light guide according to the first embodiment. Side view of the state after the substrate is attached to the light guide according to the first embodiment. Top view of the state before the substrate is attached to the light guide according to the first embodiment. Perspective view of the state before mounting the substrate with respect to the light guide according to the first embodiment. Side view of the state before mounting the board with respect to the light guide according to the second embodiment. Side view of the state after the substrate is attached to the light guide according to the second embodiment. Top view of the state before the substrate is attached to the light guide according to the second embodiment. Perspective view of the state before mounting the substrate with respect to the light guide according to the second embodiment.

[First Embodiment]
A description will be given with reference to FIGS. 1 to 6.

As shown in FIG. 1, the copying machine 1000, which is an image forming apparatus, includes an image reading apparatus 401 and an image forming apparatus main body 600. The image reading device 801 includes a platen glass 802, a reading unit 403, a scanning belt 804, and a motor 405. The platen glass 802 places the original. The scanning unit 403 reads an image of a document (sheet). The scanning belt 804 moves and scans the scanning unit along the platen glass, and the motor 405 drives the scanning belt. The image forming apparatus main body 600 forms an image by a known electrophotographic method. The image forming apparatus main body 600 includes an image forming unit 601 inside. The image forming unit 601 includes a photoconductor, an exposure device, a developing device, a transfer device, and a fixing device. The exposure apparatus forms an electrostatic latent image on the photoconductor based on the image information acquired by the image reader 801. The developing device develops the electrostatic latent image into a developer image with toner. The transfer device transfers the developer image to a recording medium such as a recording paper or an OHP sheet that has been conveyed. The fixing device fixes the developer image on the recording medium to the recording medium by heat or the like.

FIG. 2 is an enlarged cross-sectional view of the reading unit 403. The reading unit 403 includes a lighting unit 501, a planar mirror 502, 503, 504, 505, 506, a lens unit 507, and a photoelectric conversion element 508. The illumination unit 501 irradiates the image surface of the document with light, and the flat mirrors 502 to 506 guide the diffused light (reflected light) from the document to the lens unit 507. The lens unit 507 forms an image of the light guided by the planar mirror on the photoelectric conversion element 508. The photoelectric conversion element 508 is a reading sensor such as a CCD. The lighting unit 501 includes a light guide 101, a plurality of LEDs (light emitting elements) 102, and a substrate 103. The light guide 101 has a positioning surface 201 for positioning the substrate 103, and a plurality of flexible arms 202 (pressing portions) for pressing the substrate 103 toward the positioning surface 201. The substrate 103 of the lighting unit 501 is fixed to the frame of the reading unit 403. Details of the lighting unit 501 will be described later. As will be described later, a plurality of arms 202 are provided as arms 202a, 202b, and 202c in the longitudinal direction, but when distinction is unnecessary, the arm 202 will be described.

When reading the image of the original, the original is placed on the platen glass 802, and the LED 102 is turned on to irradiate the original with light. The scanning belt 804 is driven by the motor 405 in a state of being irradiated with light, and the scanning unit 403 is scanned along the platen glass 802. The light emitted to the document is diffused on the surface of the document, and the diffused light is guided to the lens unit 507 by the plane mirrors 502 to 506 and formed into an image on the photoelectric conversion element 508. The photoelectric conversion element 508 electrically reads the formed light to generate an electric signal (image signal), whereby the image of the original can be read.

FIG. 3 shows a control block diagram of the copying machine 1000. The image reading device control unit 700 controls the reading unit control unit 701 and the motor 405. The reading unit control unit 701 controls the LED 102 and the photoelectric conversion element 508. The image forming apparatus main body control unit 702 controls the image forming unit 601. The reading unit control unit 701 sends an image signal generated by the photoelectric conversion element 508 to the image reading device control unit 700. The image reading device control unit 700 sends an image signal to the image forming device main body control unit 702, and the image forming device main body control unit 702 controls the image forming unit 601 based on the image signal to form an image on the recording medium. ..

(Structure of lighting unit)
The details of the lighting unit 501 will be described with reference to FIGS. 4 to 6.

FIG. 4 is a perspective view showing a schematic configuration of the lighting unit 501. As shown in FIG. 4, the lighting unit 501 includes a light guide 101, an LED 102, and a substrate 103. The LEDs 102 are arranged in a row along the longitudinal direction of the substrate 103. The light guide 101 has an incident surface 104 on which the light from the LED 102 is incident, and an emitting surface 105 that emits the light guided by the light guide 101 and irradiates the document to be read by the image reading device.

5A and 5B are side views of the lighting unit described with reference to FIG. FIG. 5A shows a state before the substrate 103 is attached to the light guide 101, and FIG. 5B shows a state after the substrate 103 is attached to the light guide 101.

The positioning surface 201 is provided so as to extend from the light guide 101. The positioning surface 201 comes into contact with the LED mounting surface 103a (first surface) of the substrate 103, and positions the substrate 103 with respect to the light guide 101. The arm 202 is flexibly provided on the lower surface of the light guide, and presses the lower surface of the substrate 103 (the second surface opposite to the first surface) toward the positioning surface 201. A plurality of positioning surfaces 201 and arms 202 are provided over the longitudinal direction of the light guide 101 and the substrate 103. The arm 202 presses at a position between the LEDs 102 adjacent to the substrate 103 in the longitudinal direction of the substrate 103. The positioning surface 201 abuts on the substrate 103 on a plane substantially parallel to the substrate 103. The area where the positioning surface 201 and the substrate 103 abut is larger than the area where the substrate 103 and the arm 202 abut, so that stable positioning can be performed.

FIG. 6A is a top view of the lighting unit before the light guide 101 and the substrate 103 are combined, and FIG. 6B is a perspective view. As shown in FIGS. 6A and 6B, the substrate 103 includes notches 301, 302, and 303. The cutout portions 301, 302, and 303 are provided so as to correspond to the arms 202a, 202b, and 202c in the longitudinal direction, respectively. The notch 302 (center notch) is provided at a substantially central portion in the longitudinal direction of the substrate 103. The cutout portions 301 and 303 (end notch portions) are provided on the end portion side in the longitudinal direction with respect to the notch portion 302. The arm 202b (center pressing portion) is provided at a substantially central portion in the longitudinal direction of the light guide. The arms 202a and 202c (end pressing portions) are provided on the end side in the longitudinal direction with respect to the arm 202b. The gap between the central notch 302 and the central arm 202b is narrower than the gap between the notches 301 (303) at both ends and the arm 202a (202c). The width of the central notch 302 is sized so that it fits with a very small gap with respect to the width of the central arm 202b, and the widths of the notches 301 and 303 at both ends are the width of the arm 202a. , The size is such that it fits with a large gap with respect to the width of 202c.

The case where the substrate 103 is attached to the light guide 101 will be described. From the state of FIG. 5A, the substrate 103 is pressed against the light guide 101 and inserted. At that time, the arm 202 collides with the substrate 103, but since the arm 202 has flexibility, the substrate 103 can be made to enter the light guide 101. The bent arm 202 presses the lower surface of the substrate 103 toward the positioning surface 201. In the process of inserting the substrate 103, the arm 202b enters the notch 302 in the center of the substrate. Since the arm 202 and the notch 302 at the center are sized to fit with a very small gap, the positions of the light guide 101 and the substrate 103 in the longitudinal direction are determined. Further, when the substrate 103 is further inserted, the inner surfaces 301a, 302a, 303a of the cutout portions 301, 302, 303 come into contact with the abutting surfaces 104a, 104b, 104c of the light guide 101, respectively. Then, the position of the substrate 103 in the insertion direction is determined. Since the positioning and fixing can be performed without using the adhesive as described above, the step of holding the adhesive for a certain period of time until it obtains a predetermined strength becomes unnecessary. When the substrate and the light guide are bonded to each other using a conventional adhesive, it takes time to obtain a predetermined adhesive force after the substrate and the light guide are bonded to each other. Therefore, when the substrate or the light guide is a single item and has a warp, the bonded interface may be peeled off unless pressure is applied after the bonding and the light guide is held for a predetermined time, resulting in poor assembly workability. According to this embodiment, it is possible to improve the assembly workability.

The light guide 101 is generally made of a transparent resin. On the other hand, the substrate 103 is formed of a substrate made of a metal such as aluminum in order to dissipate heat generated from the LED 102. The coefficient of linear expansion of the light guide 101 is larger than that of the substrate 103. When the LED 102 is continuously lit, the temperature of the light guide 101 and the substrate 103 rises and thermally expands, but the resin light guide 101 expands more than the metal substrate 103. As shown in FIG. 6A, the position of the light guide 101 in the longitudinal direction with respect to the substrate 103 is determined by the fitting of the arm 202b provided in the center and the notch 302. On the other hand, the arms 202a and 202c at the ends and the notched portions 301 and 303 have a gap. Therefore, even if the light guide 101 and the substrate 103 thermally expand due to the heat generated by the LED 102, the light guide 101 thermally expands toward both ends of the substrate 103 with respect to the central portion. Although the substrate 103 is in contact with the positioning surface 201 and the arm 202 of the light guide 101, it is not fixed, so that it can slide and extend by the difference in the amount of thermal expansion. As a result, it is possible to prevent the light guide 101 or the substrate 103 from being warped due to the difference in the amount of thermal expansion, and to prevent a decrease in the amount of light due to a deviation in the relative position between the LED 102 and the light guide 101 and the occurrence of unevenness in the amount of light. Can be done.

[Second Embodiment]
The second embodiment has the same configuration as the first embodiment except that the fixing method between the substrate 103 and the light guide 101 is different. Therefore, the same reference numerals are given to the same points as in the first embodiment, and the description thereof will be omitted.

7A and 7B are side views of the lighting unit 501. FIG. 7A shows a state before the substrate 103 is attached to the light guide 101, and FIG. 7B shows a state after the substrate 103 is attached to the light guide 101.

The positioning surface 401 is provided on the lower surface of the light guide 101. The positioning surface 401 comes into contact with the LED mounting surface 103a (first surface) of the substrate 103, and positions the substrate 103 with respect to the light guide 101. The arm 402 includes the convex portion 402z and is provided on the lower surface of the light guide with flexibility. As will be described later, a plurality of arms 402 are provided as arms 402a, 402b, and 402c in the longitudinal direction, but when distinction is unnecessary, the arm 402 will be described. The convex portion 402z presses the lower surface of the substrate 103 (the second surface opposite to the first surface) toward the positioning surface 401. A plurality of positioning surfaces 401 and convex portions 402z are provided over the longitudinal direction of the light guide 101 and the substrate 103. The arm 402 presses at a position between the LEDs 102 adjacent to the substrate 103 in the longitudinal direction of the substrate 103. The positioning surface 401 abuts on the substrate 103 on a plane substantially parallel to the substrate 103. The area where the positioning surface 401 and the substrate 103 abut is larger than the area where the substrate 103 and the convex portion 402z abut, so that stable positioning can be performed.

FIG. 8A is a top view of the lighting unit before the light guide 101 and the substrate 103 are combined, and FIG. 8B is a perspective view.

As shown in FIGS. 8A and 8B, the substrate 103 includes notches 301, 302, and 303. The cutout portions 301, 302, and 303 are provided so as to correspond to the arms 402a, 402b, and 402c in the longitudinal direction, respectively. The notch 302 (center notch) is provided at a substantially central portion in the longitudinal direction of the substrate 103. The cutout portions 301 and 303 (end notch portions) are provided on the end portion side in the longitudinal direction with respect to the notch portion 302. The convex portion 402z (center pressing portion) of the arm 402b is provided at a substantially central portion in the longitudinal direction of the light guide. The convex portion 402z (end pressing portion) of the arms 402a and 402c is provided on the end side in the longitudinal direction with respect to the arm 402b.

The case where the substrate 103 is attached to the light guide 101 will be described. From the state of FIG. 7A, the substrate 103 is pressed against the light guide 101 and inserted. At that time, the convex portion 402z of the arm 402 collides with the substrate 103, but since the arm 402 has flexibility, the substrate 103 can enter. The bent arm 402 presses the lower surface of the substrate 103 toward the positioning surface 401. In the process of inserting the substrate 103, the arm 202 enters the notch 302 in the center of the substrate. Since the arm 202 and the notch 302 at the center are sized to fit with a very small gap, the positions of the light guide 101 and the substrate 103 in the longitudinal direction are determined. Further, as the substrate 103 is further inserted, the inner surfaces 301a, 302a, and 303a of the cutout portions 301, 302, and 303 come into contact with the abutting surface 404 of the light guide 101, respectively (see FIGS. 7B and 8A). Then, the position of the substrate 103 in the insertion direction is determined. Since the positioning and fixing can be performed without using the adhesive as described above, the same effect as that of the first embodiment can be obtained.

(Modification example)
The above embodiment can be modified and applied as follows.

As shown in FIG. 5A, the configuration in which the positioning surface 201 of the light guide 101 abuts on the LED mounting surface 103a side of the substrate 103 has been described, but the present invention is not limited thereto. Even in a configuration in which the LED non-mounting surface 103b side and the positioning surface 201 are brought into contact with each other and the LED mounting surface 103a side is pressed by the flexible arm 202, the effect of preventing warpage due to thermal expansion when the temperature rises can be obtained. However, since the relative position accuracy between the incident surface 104 of the light guide 101 and the LED 102 may be disadvantageous due to the dimensional tolerance of the thickness of the substrate 103, positioning should be performed on the LED mounting surface 103a side of the substrate 103. desirable.

Although the configuration in which the arm 202b provided in the central portion of the light guide 101 and the notch portion 302 provided in the substrate are fitted to each other for positioning in the longitudinal direction has been described, the present invention is not limited to this. The effect of the present invention can also be obtained by a configuration in which the arm 202a (or 202c) at the end and the notch 301 (or 303) are positioned in the longitudinal direction. However, when the distance in the longitudinal direction from the positioning portion, which is the reference of thermal expansion, to the end portion is short, the difference in the amount of thermal expansion between the substrate 103 and the light guide 101 can be reduced. Therefore, in order to reduce the relative positional deviation between the light guide 101 and the LED 102, a configuration in which the light guide 101 is positioned at the center is suitable.

The configuration in which metal is used to dissipate the heat generated by the LED 102 as the material of the substrate 103 has been described, but the present invention is not limited to this. It is also possible to use a material other than metal for the substrate 103, for example, a resin material such as glass epoxy used for a general electric substrate. In this case, the difference in the coefficient of linear expansion between the light guide 101 made of the transparent resin and the substrate 103 is smaller than that in the case of using a metal for the substrate. However, since a difference in the amount of thermal expansion between the light guide 101 and the substrate 103 occurs, the present invention is effective in order to prevent warpage when the temperature rises.

The positioning surface 201 and the arm 202 are arranged in a staggered manner in the longitudinal direction (a configuration in which they do not overlap in the longitudinal direction), but the present invention is not limited to this. The reason why the positioning surface 201 and the arm 202 are staggered in this way is that the light guide 101 is generally made of resin and therefore simplifies the configuration of the mold used for injection molding. For mounting the light guide 101 and the substrate 103, a configuration in which the positioning surface 201 and the arm 202 face each other can be adopted. The configuration in which the document is placed on the platen glass 802 and the scanning unit 403 is scanned to read the document has been described, but the present invention is not limited thereto. The present invention is also effective in a configuration in which the reading unit 403 is stopped and the originals are relatively moved and read by the automatic document transfer device.

Although the description has been given in the configuration of the electrophotographic copying machine 1000, the present invention is not limited to this. The image reading device of the present embodiment may be applied to an inkjet printer or the like that ejects ink to form an image on paper. The present invention can also be applied to an image reader that does not form an image on a recording medium, such as a scanner.

101 Light Guide 102 LED
102 Board 103a LED mounting surface 103b LED non-mounting surface 103 Board 201 Positioning surface 202 Arm 401 Image reading device 403 Reading unit 501 Lighting unit 508 Photoelectric conversion element 600 Image forming device main body 601 Image forming unit 1000 Copier

Claims (5)

A lighting unit that illuminates the image surface of the sheet with light,
An image reading unit that reads an image of the sheet based on the reflected light from the sheet,
Have,
The lighting unit is
A substrate including an upper surface provided with a plurality of light emitting elements arranged in a first direction and a side surface adjacent to the upper surface and intersecting the first direction .
A light guide that guides the light emitted from the plurality of light emitting elements to the sheet, and includes a first surface facing the side surface thereof, and a light guide.
Equipped with
The side surface is a surface located at the end of the substrate in the first direction.
The light guide includes a second surface of the substrate facing the top surface and a third surface facing the bottom surface of the substrate opposite the top surface.
An image reading device, wherein the second surface and the third surface are surfaces adjacent to the first surface. The image reading device according to claim 1 , wherein the first surface extends from the second surface in a second direction intersecting the upper surface. The image reading device according to claim 1 or 2 , wherein the third surface is a flexible arm, and the substrate is pressed toward the second surface by bending the arm. The image reading device according to any one of claims 1 to 3 , wherein the substrate is a metal and the light guide is a resin. The image reading device according to claims 1 to 4 ,
An image forming unit that forms an image based on an image obtained by the image reading device, and an image forming unit.
An image forming apparatus comprising.

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