WO2015146470A1

WO2015146470A1 - Image reading apparatus and image forming apparatus comprising same

Info

Publication number: WO2015146470A1
Application number: PCT/JP2015/055692
Authority: WO
Inventors: 佳彦黒津
Original assignee: 京セラドキュメントソリューションズ株式会社
Priority date: 2014-03-28
Filing date: 2015-02-26
Publication date: 2015-10-01

Abstract

An image reading apparatus (13), which reads the image of a source document, comprises: an image capture element (9) that converts a light to an electric signal; a source document reading plane (R) on which the source document is put or along which the source document passes; an illumination unit (5) that is placed below the source document reading plane and that irradiates an illumination light onto the source document on the source document reading plane; and an optical system (8) that causes a reflected light from the source document to form an image on the image capture element. The illumination unit (5) includes: a planar organic EL light emitter (6) that is long in the main scan direction for the source document and that has a light emission plane (6F) for emitting the illumination light and a back plane (6B) opposite to the light emission plane; and a frame member (50) that has a mounting plane opposed to the source document reading plane and that supports the organic EL light emitter in such a manner that the back plane of the organic EL light emitter lies on the mounting plane of the frame member.

Description

Image reading apparatus and image forming apparatus having the same

The present invention relates to an image reading apparatus that optically reads an image of a document, and an image forming apparatus including the image reading apparatus.

In recent years, an illumination unit using an LED (Light Emitting Diode) instead of a xenon lamp or the like has begun to be adopted as a light source of an image reading apparatus that optically reads an image of a document. As such an illumination unit, a type in which a large number of LED chips are arranged in the main scanning direction and a type using a high-intensity LED module and a light guide are known. In the latter type, an LED module is disposed at an end in the main scanning direction, illumination light is incident on one end of the light guide, and the illumination light is emitted from the peripheral surface of the light guide (see, for example, Patent Document 1). ). This configuration has the advantage that the light source itself is simple and low in cost.

However, since the high-intensity LED module generates heat appropriately with light emission, it is necessary to arrange a heat dissipation mechanism such as a heat sink on the LED mounting board. Further, the light guide that guides the illumination light from one end to the other in the main scanning direction requires extremely fine processing in order to make the amount of illumination light constant in the main scanning direction. Furthermore, since the light guide body thermally expands due to the heat generated by the LED module, a structural measure to avoid warping of the light guide body based on the thermal expansion is also required. These complicate the structure of the lighting unit and increase the cost.

JP 2008-216409 A

An object of the present invention is to provide an image reading apparatus having an illumination unit having a structure as simple as possible, and an image forming apparatus including the image reading apparatus.

An image reading apparatus according to an aspect of the present invention is an image reading apparatus that reads an image of a document, an image sensor that converts light into an electrical signal, and a document reading surface on which the document is placed or passed. An illumination unit that is disposed below the document reading surface and irradiates illumination light on the document on the document reading surface; and an optical system that forms an image of reflected light from the document on the image sensor, The illumination unit has a light emitting surface that emits the illumination light and a back surface opposite to the light emitting surface, and has a flat organic EL light emitter that is long in the main scanning direction of the document and a mounting surface that faces the document reading surface. And a frame member that holds the organic EL light emitter along the back surface along the mounting surface.

An image forming apparatus according to another aspect of the present invention includes the above image reading apparatus and an image forming unit that forms an image on a sheet based on image data output from the image reading apparatus.

According to the image reading apparatus or the image forming apparatus, the illumination system of the image reading apparatus can be constructed with a simple configuration in which the organic EL light emitter is disposed along the attachment surface facing the document reading surface. it can. The organic EL illuminator itself emits surface light and hardly generates heat due to light emission, so that it is not necessary to apply a heat sink or a light guide. Therefore, according to the present invention, it is possible to provide an image reading apparatus having an illumination unit with a simple structure, and an image forming apparatus including the image reading apparatus.

The objects, features and advantages of the present invention will become more apparent from the following detailed description and the accompanying drawings.

FIG. 1 is a cross-sectional view illustrating a schematic configuration of an image reading apparatus and an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a perspective view showing an illumination unit according to an embodiment of the present invention. FIG. 3 is a partially enlarged perspective view of the illumination unit. 4 is a cross-sectional view taken along line IV-IV in FIG. FIG. 5A is a plan view showing an example of a light emitting surface shape of an organic EL light emitter. FIG. 5B is a graph showing a light amount distribution after passing through the imaging lens. FIG. 5C is a graph showing a preferable light amount distribution of the light source. FIG. 6A is a plan view showing an example of a light emitting surface shape of an organic EL light emitter applicable to the present invention. FIG. 6B is a plan view showing another example of the light emitting surface shape. FIG. 6C is a plan view showing another example of the light emitting surface shape. FIG. 6D is a plan view showing another example of the light emitting surface shape. FIG. 6E is a plan view showing another example of the light emitting surface shape. FIG. 7 is a plan view showing an organic EL light emitter provided with a cover member. FIG. 8A is a plan view showing an organic EL light emitter held by a claw member. 8B is a cross-sectional view taken along line VIIIB-VIIIB in FIG. 8A. FIG. 9A is a cross-sectional view showing an embodiment including an attachment surface having a concave shape in the sub-scanning direction. FIG. 9B is a cross-sectional view showing an embodiment including an attachment surface having a concave shape in the sub-scanning direction. FIG. 10A is a cross-sectional view showing an embodiment including an attachment surface having a concave shape in the main scanning direction. FIG. 10B is a cross-sectional view showing an embodiment including an attachment surface having a concave shape in the main scanning direction. It is a schematic diagram which shows the modification of an illumination unit.

Hereinafter, embodiments of the present invention will be described in detail based on the drawings. FIG. 1 is a cross-sectional view showing a schematic configuration of an image forming apparatus 1 according to an embodiment of the present invention. In the present embodiment, as the image forming apparatus 1, an in-body discharge type monochrome copying machine including a scanner device 13 (image reading device) is illustrated. The apparatus to which the present invention is applied is not limited to the present embodiment, and may be, for example, a color copying machine, a scanner apparatus, a facsimile apparatus, or a multifunction apparatus.

The image forming apparatus 1 includes a substantially rectangular parallelepiped main body housing 10 and an automatic document feeder 11 disposed on the upper surface of the main body housing 10. The main body housing 10 is a housing that houses various devices that perform image forming processing on sheets. The automatic document feeder 11 automatically conveys a document sheet to be copied via an image reading position set on the upper surface of the main body housing 10 (upper surface of the second contact glass 132). A document sheet conveying device 12 is incorporated in the left side of the automatic document feeder 11.

A scanner device 13 for optically reading an image of a document sheet is accommodated in the upper part of the main body housing 10. The scanner device 13 will be described in detail later. Below the scanner device 13, an in-body sheet discharge unit 14 that can store a sheet after image formation is provided. A paper feed cassette 15 that accommodates a sheet on which image forming processing is performed is detachably attached to the lower portion of the main body housing 10. A manual feed tray 16 is attached to the right side wall of the main body housing 10.

The main body housing 10 includes a first discharge port 141 and a second discharge port 142 that open toward the space of the in-body discharge unit 14. A sheet discharged from the first discharge port 141 is received by the in-body discharge tray 143. A sub discharge tray 144 is mounted above the in-body discharge tray 143. A sheet discharged from the second discharge port 142 is stacked on the sub discharge tray 144, or a sheet to be printed on both sides is temporarily discharged for switchback conveyance.

In the main body housing 10, in addition to the scanner device 13 and the paper feed cassette 15 described above, an image forming unit 20, a fixing unit 30, and a sheet conveyance path are accommodated. The image forming unit 20 forms an image on a sheet based on the image data output from the scanner device 13. The image forming unit 20 includes a photosensitive drum 21, and a charger 22, an exposure device 23, a developing device 24, a transfer roller 25, and a cleaning device 26 disposed around the photosensitive drum 21. The photosensitive drum 21 rotates around its axis and includes a peripheral surface on which an electrostatic latent image and a toner image are formed. The charger 22 uniformly charges the peripheral surface of the photosensitive drum 21. The exposure device 23 irradiates the peripheral surface of the photosensitive drum 21 with laser light in order to form an electrostatic latent image. The developing device 24 supplies toner to the peripheral surface of the photosensitive drum 21 in order to develop the electrostatic latent image formed on the photosensitive drum 21. The transfer roller 25 forms a transfer nip portion with the photosensitive drum 21 and transfers the toner image on the photosensitive drum 21 to a sheet. The cleaning device 26 cleans the peripheral surface of the photosensitive drum 21 after the toner image is transferred. A toner container 27 for supplying toner to the developing device 24 is disposed adjacent to the developing device 24.

The fixing unit 30 includes a fixing roller 31 with a built-in heat source, and a pressure roller 32 that forms a fixing nip portion together with the fixing roller 31. The fixing unit 30 performs a fixing process by heating and pressurizing the sheet on which the toner image is transferred in the transfer nip portion in the fixing nip portion. The fixed sheet is discharged from the first discharge port 141 or the second discharge port 142 toward the in-body discharge unit 14.

The sheet conveyance path includes a main conveyance path P1 extending in the vertical direction from the vicinity of the lower part of the main body housing 10 to the vicinity of the upper part via the image forming unit 20 and the fixing unit 30. Near the downstream end of the main transport path P1, a first discharge transport path P2 that leads the sheet to the first discharge port 141 is branched. A second discharge conveyance path P3 that guides the sheet to the second discharge port 142 is connected to the most downstream end (upper end) of the main conveyance path P1. Further, a reverse conveyance path P4 that reverses and conveys the sheet during duplex printing extends from the most downstream end of the main conveyance path P1 to the vicinity of the upstream end.

The paper feed cassette 15 includes a sheet storage unit 151 that stores a sheet bundle. A pickup roller 152 that feeds out the uppermost sheet of the sheet bundle one by one and a paper feed roller pair 153 that feeds the sheet to the upstream end of the main transport path P1 are provided near the upper right of the sheet storage unit 151. Yes. The sheet placed on the manual feed tray 16 is sent out to the upstream end of the main transport path P1 by the manual feed roller 161. A registration roller pair 154 that feeds the sheet to the transfer nip portion at a predetermined timing is disposed upstream of the image forming unit 20 in the main conveyance path P1.

When a single-sided printing process is performed on a sheet, the sheet is sent out from the sheet storage unit 151 or the manual feed tray 16 to the main conveyance path P1, and the transfer process of the toner image is transferred to the sheet in the image forming unit 20 in the fixing unit 30. A fixing process for fixing the toner to the sheet is performed. Thereafter, the sheet is discharged from the first discharge port 141 onto the in-body discharge tray 143 through the first discharge conveyance path P2. On the other hand, when the double-sided printing process is performed on the sheet, after the transfer process and the fixing process are performed on one side of the sheet, the sheet passes through the second discharge conveyance path P3 and is then discharged from the second discharge port 142 to the sub discharge. A part is discharged onto the paper tray 144. Thereafter, the sheet is conveyed in a switchback manner, and returned to the vicinity of the upstream end of the main conveyance path P1 through the reverse conveyance path P4. Thereafter, a transfer process and a fixing process are performed on the other surface of the sheet, and the sheet is discharged from the first discharge port 141 onto the in-body discharge tray 143 through the first discharge conveyance path P2. .

Subsequently, the scanner device 13 will be described in detail. The scanner device 13 includes a scanner housing 130, and a first contact glass 131 for manual reading and a second contact glass 132 for automatic reading that are fitted on the upper surface of the scanner housing 130. The upper surface of the first contact glass 131 serves as a document reading surface of a document sheet placed by the user. The upper surface of the second contact glass 132 serves as a document reading surface through which a document sheet automatically fed from the automatic document feeder 11 passes.

The scanner device 13 includes an illumination unit 5, a mirror unit 73, a condenser lens unit 8 (optical system), and an image sensor 9 housed in a scanner housing 130. The illumination unit 5 irradiates the original sheet on the original reading surface with illumination light. The illumination unit 5 includes an organic EL light emitter 6 as a light source that emits the illumination light toward the document reading position, a reflector 71 that directs the illumination light toward the document reading position, and a document irradiated with the illumination light. A first reflection mirror 72 that reflects light reflected from the sheet is mounted. The mirror unit 73 is equipped with a second reflecting mirror 731 and a third reflecting mirror 732 in order to reverse the optical path of the reflected light.

The illumination unit 5 reciprocates in the left-right direction (sub-scanning direction) along the lower surfaces of the first and second contact glasses 131 and 132 (below the document reading surface). The mirror unit 73 reciprocates in the left-right direction with a movement amount ½ that of the illumination unit 5. When the document sheet is automatically fed from the automatic document feeder 11, the illumination unit 5 moves immediately below the second contact glass 132 and becomes stationary. In this stationary state, illumination light is emitted from the organic EL light emitter 6 toward the document sheet. On the other hand, when the document sheet is placed on the first contact glass 131, the illumination unit 5 moves to the right according to the size of the document sheet from directly below the left end of the first contact glass 131. During this movement, illumination light is emitted from the organic EL light emitter 6 toward the document sheet. The mirror unit 73 follows the lighting unit 5 and moves to the right by a movement amount that is ½ of that of the lighting unit 5.

The organic EL light emitter 6 irradiates the original sheet with linear illumination light that is long in the main scanning direction. The organic EL light emitter 6 is disposed to face the first and

second contact glasses

131 and 132 with a predetermined angle. The normal line of the light emitting surface of the organic EL light emitter 6 substantially intersects the original reading position so that the illumination light emitted from the organic EL light emitter 6 is oriented to the original reading position. The reflection plate 71 is disposed substantially symmetrically with the organic EL light emitter 6 with a vertical plane including the image reading position interposed therebetween. Part of the diffused light of the illumination light is reflected by the reflecting plate 71 and travels toward the document reading position. The first reflecting mirror 72 reflects the reflected light of the illumination light emitted from the organic EL light emitter 6 toward the document sheet so as to be directed toward the second reflecting mirror 731 of the mirror unit 73.

The second reflection mirror 731 reflects the reflected light reflected toward the left by the first reflection mirror 72 toward the third reflection mirror 732. The third reflection mirror 732 reflects the reflected light to the right so as to go to the condenser lens unit 8. The condensing lens unit 8 forms an optical image of the reflected light reflected by the third reflecting mirror 732 on the imaging surface of the imaging element 9. The image sensor 9 is composed of a CCD (charge coupled device) or the like, and receives the reflected light and photoelectrically converts it into an analog electric signal. The analog electrical signal is converted into a digital electrical signal by an A / D conversion circuit (not shown), and then input to the exposure device 23 as image data.

Next, the lighting unit 5 will be described in detail. 2 is a perspective view of the illumination unit 5, FIG. 3 is an enlarged perspective view of the end of the illumination unit 5 in the main scanning direction, and FIG. 4 is a sectional view taken along line IV-IV in FIG. The illumination unit 5 includes the organic EL light emitter 6 and the reflection plate 71 (reflector) described above, and a frame member 50 that holds them.

An organic EL (Electro-Luminescence) light emitter 6 includes a thin light-emitting layer made of an organic compound, and an anode and a cathode disposed with the light-emitting layer sandwiched therebetween, and has a flat plate shape that is long in the main scanning direction of the original sheet. It is a light emitting body for illumination having flexibility. The organic EL light emitter 6 includes a light emitting surface 6F that emits illumination light and a back surface 6B opposite to the light emitting surface 6F, and is held by the frame member 50 so that the light emitting surface 6F faces the document reading position RA of the document reading surface R. ing. The reflection plate 71 is an elongated flat plate member having a mirror surface that reflects illumination light and having substantially the same length as the organic EL light emitter 6 in the main scanning direction. The reflecting plate 71 is held by the frame member 50 so that the normal line of the reflecting plate 71 is generally directed to the document reading position RA.

The frame member 50 is made of a sheet metal working member, and has a horizontal plate 501 that is long in the front-rear direction (main scanning direction), a first holding unit 51 and a second holding unit 52 that are erected upward from the horizontal plate 501, And a slit 53 that is long in the front-rear direction and is perforated in the plate 501. Engaging portions 502 formed of bent portions are provided at both ends of the horizontal plate 501 in the main scanning direction. To the engaging portion 502, pulleys for smoothly moving the frame member 50 (illumination unit 5) in the sub-scanning direction are attached.

The first holding unit 51 is provided to hold the organic EL light emitter 6. As shown in FIG. 4, the first holding portion 51 is a frame frame disposed on the right side of the horizontal plate 501, and forms a first inclined surface that forms an attachment surface 54 S for holding the organic EL light emitter 6. A portion 54 is provided. The attachment surface 54S is a plane inclined substantially 45 degrees with respect to the horizontal plane in the sub-scanning section, and faces the document reading surface R (document reading position RA). The organic EL light emitter 6 is attached to the first inclined surface portion 54 so that the back surface 6B thereof is along the attachment surface 54S. Note that a bonding member 54A is interposed between the back surface 6B and the attachment surface 54S, and the organic EL light emitter 6 is firmly held on the attachment surface 54S. The joining member 54A is, for example, a double-sided tape or an organic adhesive layer.

The second holding part 52 is provided for holding the reflection plate 71. The second holding portion 52 is a drawing processed portion disposed on the left side of the horizontal plate 501, and includes a second inclined surface portion 55 that forms a support surface 55 S (the other attachment surface) for holding the reflecting plate 71. Have. The support surface 55S is a plane that is inclined at approximately 45 degrees with respect to the horizontal plane in the sub-scan section, and faces the document reading surface R (document reading position RA). The support surface 55S is substantially at a height position with respect to the attachment surface 54S, and the inclination directions are opposite to each other. In the sub-scanning cross section, the horizontal plate 501, the support surface 55 S, and the attachment surface 54 S form a generally mortar-shaped recess. The reflection plate 71 is held by the second inclined surface portion 55 with the back surface thereof being in close contact with the support surface 55S.

The slit portion 53 is a slit for guiding reflected light from the original sheet to the lower side of the horizontal plate 501. FIG. 4 shows the optical paths of the illumination lights L1 and L2 and the reflected light L3. The illumination light L1 emitted from the light emitting surface 6F of the organic EL light emitter 6 goes to the document reading position RA. On the other hand, the diffuse illumination light L2 emitted from the light emitting surface 6F is reflected by the reflecting plate 71 and travels toward the document reading position RA. These illumination lights L1 and L2 are reflected by the original sheet placed or passed at the original reading position RA, and become reflected light L3 and travel vertically downward. The reflected light L3 passes through the slit portion 53 and is reflected by a first reflecting mirror 72 (not shown in FIG. 4).

In the present embodiment, the organic EL light emitter 6 includes a central portion 61 having a relatively narrow width of the light emitting surface 6F and a pair of end portions 62 having a relatively wide width of the light emitting surface 6F. That is, the area per unit length in the main scanning direction of the light emitting surface 6F is set to be larger at the end 62 than at the central portion 61 in the main scanning direction. As a result, the end 62 has a larger light emitting surface 6F, and the amount of emitted light is greater at the end 62 than at the center 61. Hereinafter, the significance of such a configuration will be described.

FIG. 5A is a plan view showing the shape of the light emitting surface 6F of the organic EL light emitting body 601 applicable to the present invention. The organic EL light emitter 601 includes a rectangular light emitting surface 6F having a uniform width over the entire length in the main scanning direction. In this case, the amount of light emitted from the light emitting surface is substantially uniform from the end to the center in the main scanning direction. In the present invention, it is of course possible to assemble such an organic EL light emitting body 601 to the illumination unit 5. However, from the viewpoint of allowing light with a uniform light amount to enter the image sensor 9 over the entire length in the main scanning direction, as shown in FIG. 2, the organic EL light emitter 6 having the wide end 62 is used. Is desirable.

FIG. 5B is a graph showing a light amount distribution after passing through the condenser lens unit 8 when the organic EL light-emitting body 601 is used as a light source. As shown in this graph, in the configuration in which the reflected light from the document sheet is imaged onto the image sensor 9 by the lens optical system, the light quantity at the end in the main scanning direction tends to decrease due to the characteristics of the lens. This is because less light passes through the lens near the + end and − end of the scanning width in the main scanning direction. Therefore, even if the light source itself emits illumination light with a uniform light amount over the entire length of the scanning width, when the reflected light passes through the condenser lens unit 8, the light amounts near the + end and − end are centered. It will be lower than the vicinity. When such light enters the image sensor 9, there is a concern that the exposure of the end portion in the main scanning direction becomes insufficient.

FIG. 5C is a graph showing a preferable light amount distribution as a light source of the illumination unit 5. This graph has a light amount distribution in which the light amount near the + end and − end in the main scanning direction is higher than that near the center. If the light source has such a light amount distribution, it is possible to compensate for the decrease in the light amount at the end when the condenser lens unit 8 passes. Accordingly, the amount of light incident on the image sensor 9 can be made uniform over the entire length in the main scanning direction.

In the present embodiment, an organic EL light emitter is used as a light source. An organic EL light emitter, generally emitting uniform light per unit area, the amount of light emission depends on the area of the light emitting surface. Therefore, in the light amount distribution as shown in FIG. 5C, by adjusting the area of the light emitting surface, specifically, the area of the light emitting surface near the + end and − end in the main scanning direction is made larger than that near the center. Therefore, it can be easily obtained.

6A to 6E are plan views showing various examples of the light emitting surface shape of the organic EL light emitter that can obtain the light quantity distribution as shown in FIG. 5C. FIG. 6A shows the planar shape of the light emitting surface 6F of the organic EL light emitter 6 illustrated in FIGS. The organic EL light emitter 6 can compensate for the light amount decrease at the end when the condenser lens unit 8 passes through the central portion 61 having a width (standard width) that can emit a light amount necessary for exposure. A pair of end portions 62 having such an increased width (increased width), and tapered portions 621 provided between the central portion 61 and the end portion 62, respectively. Naturally, the area per unit length in the main scanning direction is larger at the end portion 62 than at the central portion 61. In the taper portion 621, the area per unit length increases with increasing toward the + or − off-axis direction in the main scanning direction.

6B includes a central portion 61A having the standard width and a rectangular end portion 62A having the increased width. The organic EL illuminator 602 does not have the tapered portion 621 as in the organic EL illuminator 6 described above, and the boundary between the central portion 61A and the end portion 62A has a step based on the difference in width. ing. The organic EL light emitter 603 of FIG. 6C includes a central portion 61B having the standard width, and an end portion 62B whose area per unit length increases toward the + or − off-axis direction in the main scanning direction. It has. The end portion 62B has a trapezoidal shape, and the upper base is the same width as the central portion 61B, and the lower base is wider than the central portion 61B.

FIG. 6D shows the organic EL light-emitting body 604 in a state in which the central portion and the end portion are not integrated, but are separated. The organic EL light emitter 604 has a central portion 61C made of the first light emitter having the standard width and a pair of end portions 62C made of the second light emitter having the increased width.

FIG. 6E shows an organic EL light emitting body 605 using two kinds of light emitting bodies having different light emission amounts in a state where the central portion and the end portion are separated. The organic EL light emitter 605 has the standard width and a central portion 61D made of a first light emitter that emits a light beam having a predetermined first light emission amount, the standard width, and the first width. And a pair of end portions 62D made of a second light emitter that emits a light beam having a second light emission amount larger than the light emission amount. According to the organic EL light emitter 605, it is possible to obtain a light amount distribution in which the light emission amount at the end portion is increased while the width of the light emitting surface is the same at the end portion and the central portion.

As another embodiment, a light amount distribution as shown in FIG. 5C may be obtained by covering part of the light emitting surface of the organic EL light emitter. The organic EL light emitter 606 shown in FIG. 7 includes a cover member 63 that covers a part of the light emitting surface. The light emitting surface of the organic EL light emitter 606 has a rectangular shape that is long in the main scanning direction, and the width thereof is longer than the standard width. The cover member 63 covers the vicinity of both sides of the light emitting surface in the main scanning direction (near the edges of the two long sides) except for the vicinity of the end in the main scanning direction.

As the cover member 63, a light shielding tape or film, a light shielding paint, a light shielding plate, or the like can be used. By covering a part of the light emitting surface with the cover member 63, the central portion 61E having the standard width and the pair of end portions 62E having the increased width can be formed. With such an organic EL light emitter 606, a light emitting area difference can be provided between the central portion and the end portion in the main scanning direction of the light emitting surface while using a simple rectangular organic EL light emitter. .

It is one of preferred embodiments that the cover member 63 as described above also serves as a claw member for holding the organic EL light emitter 607 on the frame member 50. 8A is a plan view showing the organic EL light emitter 607 held by the claw member 541 (holding member), and FIG. 8B is a sectional view taken along line VIIIB-VIIIB in FIG. 8A. In this embodiment, a claw member 541 made of a hook-shaped protrusion is provided on the first inclined surface portion 54 A provided in the first holding portion 51 of the frame member 50. The claw members 541 are erected in pairs on the attachment surface 54AS of the first slope portion 54A with an interval corresponding to the width of the organic EL light emitter 607.

The pair of claw members 541 covers the vicinity of both sides in the sub-scanning direction of the light emitting surface of the organic EL light emitting body 607 except for the vicinity of the end in the main scanning direction, and holds the organic EL light emitting body 607 at the portion. is doing. By covering a part of the light emitting surface with the claw member 541, a central portion 61F having the standard width and a pair of end portions 62F having the increased width are formed. According to this embodiment, since the claw member 541 also serves as the cover member when the light emitting surface has the light emitting area difference, the number of parts can be reduced.

Since the organic EL light emitter is generally flexible, the organic EL light emitter can be assembled along a curved surface. FIG. 9A illustrates a preferred embodiment that takes advantage of this merit. The organic EL light emitter 608 is attached to the first inclined surface portion 54B having an attachment surface in a curved state in the cross section in the sub-scanning direction.

The first inclined surface portion 54B is an arc surface having a concave shape toward the document reading surface R in the cross section in the sub-scanning direction. The organic EL light emitter 608 is attached to the attachment surface of the first slope portion 54B along the concave shape. According to this embodiment, the organic EL light emitter 608 is held by the frame member 50 in a form having a concave shape toward the document reading surface R in the cross section in the sub-scanning direction. Therefore, the illumination light emitted from the organic EL light emitter 608 can be condensed toward the document reading position RA that is a target point. This contributes to increasing the amount of illumination light at the document reading position RA.

FIG. 9B is illustrated as another embodiment for providing a light collecting effect. In this embodiment, the first slope portion 54C having a concave surface formed by bending is used in the cross section in the sub-scanning direction. The first inclined surface portion 54C is formed by bending the flat plate member at two locations along a bending line extending in the main scanning direction, and has three inclined surface portions 54C1, 54C2, and 54C3 having different inclination angles with respect to the document reading surface R. . The organic EL

light emitters

609, 610, and 611 are attached with the surfaces of the slope portions 54C1, 54C2, and 54C3 as attachment surfaces. Also in such an aspect, the illumination light emitted from the three organic EL

light emitters

609, 610, and 611 can be concentrated toward the document reading position RA.

FIG. 10A and FIG. 10B are cross-sectional views showing an embodiment including an attachment surface having a concave shape in the main scanning direction. These embodiments are also embodiments capable of obtaining a preferable light amount distribution shown in FIG. 5C. In FIG. 10A, the first inclined surface portion 54D having a mounting surface includes a central flat portion 54D1, an end flat portion 54D2, and a curved portion 54D3 between them.

In the cross section in the main scanning direction, the attachment surface of the first inclined surface portion 54D has a distance to the document reading surface R. The central flat portion 54D1 is a predetermined distance d1, and the end flat portion 54D2 is a distance d2 shorter than the distance d1. It is. That is, the attachment surface is a surface having a concave shape with a distance from the document reading surface R that is shorter at the end than at the center in the main scanning direction. The organic EL light emitter 612 is attached to the attachment surface of the first slope portion 54D along the concave shape. According to this embodiment, in the light amount distribution of the illumination light emitted from the organic EL light emitter 612 in the main scanning direction, the light amount at the end is increased by the amount closer to the document reading surface R at the end than at the center. be able to. Therefore, it is possible to create a desirable light amount distribution without making the light emitting area different between the end portion and the central portion.

In the embodiment shown in FIG. 10B, the first inclined surface portion 54E having the attachment surface includes a central flat portion 54E1 and end inclined portions 54E2 extending from both ends of the central flat portion 54E1. In the cross section in the main scanning direction, the attachment surface of the first slope portion 54E has a constant distance to the document reading surface R at a predetermined distance d1 in the central flat portion 54E1. On the other hand, in the end inclined portion 54E2, the distance from the distance d21 to the distance d22 is gradually shortened toward the off-axis. The organic EL light emitter 613 is attached to the attachment surface having such a concave shape. Even in this embodiment, similarly, in the light amount distribution of the illumination light, the end portion can be made larger than the center portion.

Although various embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. For example, in FIG. 4, the attachment surface 54S of the first slope portion 54 and the support surface 55S (attachment surface) of the second slope portion 55 are provided in a pair in the sub-scanning direction across the reading position RA, and are attached to the attachment surface 54S. Shows an example in which the organic EL luminous body 6 is attached and the reflecting plate 71 is attached to the support surface 55S. Instead of this, a plurality of organic EL light emitters 6 may be arranged in the sub-scanning direction across the reading position RA.

FIG. 11 is a schematic diagram showing a modification of the lighting unit 5. In this embodiment, two first inclined surface portions 54 having attachment surfaces are arranged to face each other across the reading position RA in the sub-scanning direction. The organic EL light emitter 6 is attached to each of these two attachment surfaces. According to this embodiment, the amount of illumination light can be increased.

As described above, according to the scanner device 13 (image reading device) according to the present invention, the scanner device has a simple configuration in which the organic EL light emitter 6 is disposed along the attachment surface 54S facing the document reading surface R. Thirteen illumination systems can be constructed. The organic EL light-emitting body 6 has an advantage that it itself emits surface light and hardly generates heat due to light emission, so that it is not necessary to apply a heat sink or a light guide.

Claims

An image reading apparatus for reading an image of a document,
An image sensor that converts light into an electrical signal;
A document reading surface on which the document is placed or passed;
An illumination unit that is disposed below the document reading surface and irradiates the document on the document reading surface with illumination light;
An optical system that focuses reflected light from the original on the image sensor,
The lighting unit is:
A flat organic EL light emitter having a light emitting surface for emitting the illumination light and a back surface opposite to the light emitting surface, and being long in a main scanning direction of the original;
A frame member that has an attachment surface facing the document reading surface, and holds the organic EL light emitter along the back surface with the attachment surface;
An image reading apparatus comprising:
The image reading apparatus according to claim 1,
The organic EL illuminator is an image reading apparatus in which an area per unit length in the main scanning direction of the light emitting surface is set to be larger at an end portion than at a central portion in the main scanning direction.
The image reading apparatus according to claim 2,
The light emitting surface has a long rectangular shape in the main scanning direction,
An image reading apparatus, further comprising: a cover member that covers the vicinity of the side of the light emitting surface in the sub-scanning direction perpendicular to the main scanning direction, except for the vicinity of the end in the main scanning direction.
The image reading apparatus according to claim 3.
The frame member includes a holding member that holds the organic EL light emitter on the attachment surface,
The image reading apparatus, wherein the holding member also serves as the cover member.
The image reading apparatus according to claim 1, further comprising:
An image reading apparatus comprising a bonding member interposed between a back surface of the organic EL light emitter and the mounting surface.
The image reading apparatus according to claim 1,
The organic EL light emitter has flexibility,
The attachment surface is a surface having a concave shape toward the document reading surface in a cross section in the sub-scanning direction orthogonal to the main scanning direction,
The organic EL light emitter is attached to the attachment surface along the concave shape.
The image reading apparatus according to claim 1,
The organic EL light emitter has flexibility,
The attachment surface is a surface having a concave shape in which the distance from the document reading surface in the cross section in the main scanning direction is shorter at the end than at the center in the main scanning direction;
The organic EL light emitter is attached to the attachment surface along the concave shape.
The image reading apparatus according to claim 1,
The attachment surfaces are provided in a pair in the sub-scanning direction across the reading position of the image of the document on the document reading surface,
An image reading apparatus in which the organic EL light emitter is held on each mounting surface.
The image reading apparatus according to claim 1,
The attachment surfaces are provided in a pair in the sub-scanning direction across the reading position of the image of the document on the document reading surface,
The image reading apparatus, wherein the organic EL light emitter is held on one of the mounting surfaces, and a reflector that holds the illumination light toward the reading position is held on the other mounting surface.
An image reading apparatus according to claim 1;
An image forming unit that forms an image on a sheet based on image data output from the image reading device;
An image forming apparatus comprising: