JP2009069452A - Document illumination unit, image reading apparatus using the document illumination unit, and image forming apparatus - Google Patents

Abstract

A document illumination unit capable of efficiently illuminating an object to be illuminated without increasing manufacturing costs, and an image reading apparatus and an image forming apparatus using the document illumination unit.
In a document illumination unit including a light source for illuminating a document surface, the light source is a surface light source having a longitudinal direction and a short direction, and the surface light source has a light emitting surface on at least one side. And the light emitting surface is a concave surface recessed in the longitudinal direction.
[Selection] Figure 5

Description

  The present invention relates to an original illumination unit that illuminates an original surface while scanning the vicinity of the original surface, and an image reading apparatus and an image forming apparatus using the original illumination unit. The present invention relates to a document illumination unit used in a digital copying machine, a facsimile, or the like that forms an image on an image pickup device in which images are arranged and reads image information by the image pickup device.

A conventional document illumination unit, image reading apparatus, and image forming apparatus will be described below with reference to the drawings.
(Image reading device)
FIG. 1 is a schematic diagram showing a configuration of a conventional image reading apparatus.
In FIG. 1, a document 2 having an image to be read is placed in a plane on a contact glass 1 as a “document table”, and illumination means is disposed below the contact glass 1, and the illumination means is orthogonal to the drawing. Using an illumination unit composed of a tube lamp 3A (xenon lamp, halogen lamp, etc.) that is long in the direction and a reflector 3B, the "long slit-like portion in the direction orthogonal to the drawing" is illuminated.

  The reflected light from the illuminated portion of the document 2 (reflected light from the image) is reflected by the first mirror 3C provided on the first traveling body 3, and then the second mirror provided on the second traveling body 4. 4A and the third mirror 4B are sequentially reflected, pass through the image reading lens 5, and form a reduced image of the original image on the imaging surface of the line sensor 6 as a photoelectric conversion element. The first to third mirrors 3C, 4A, and 4B constitute a “reflection optical system”.

The first traveling body 3 and the second traveling body 4 are caused to travel in the direction of the arrow (to the right in the figure) by driving means (not shown). The traveling speed of the first traveling body 3 is “V”, and the traveling speed of the second traveling body 4 is “V / 2”. By this traveling, the first traveling body 3 and the second traveling body 4 are displaced to “positions indicated by broken lines” (first traveling body 3 ′, second traveling body 4 ′).
The illumination units 3 </ b> A and 3 </ b> C move integrally with the first traveling body 3 to “illuminate and scan” the entire document 2 on the contact glass 1.
Since the moving speed ratio of the first and second traveling bodies is “V: V / 2”, the “optical path length from the original scanned portion to the image reading lens” is kept unchanged.

  The line sensor 6 that is an “imaging unit” has “a photoelectric conversion element (6A, 6B, 6C) having red (R), green (G), and blue (B) filters as color separation means on one chip. A three-line CCD (three-line line sensor) arranged in three rows ”, which converts a document image into an image signal as the document 2 is illuminated and scanned. In this way, reading of the document 2 is executed, and the color image of the document 2 is read by color separation into three primary colors of red, green, and blue.

  Further, this image reading apparatus is an apparatus for reading an image in full color, and “color separation means (red, green, blue provided in the three-line CCD” provided in the image forming optical path of the image reading lens 5. Filter) ".

  As another form of the image reading apparatus, “illuminating means for illuminating the original on the contact glass in a slit shape, a line sensor, and a plurality of mirrors forming an imaging optical path from the illuminated part of the original to the line sensor; The image reading lens arranged on the image forming optical path and the reading unit integrated with each other are moved relative to the document by the driving means so as to read and scan the document. You can also

  In the “color separation”, a color separation prism or filter is selectively inserted between the image reading lens and the line sensor (CCD) separately from the above, and R (red), G (green), and B (blue). Or a “method of illuminating a document by sequentially turning on R, G, and B light sources”.

(Image forming device)
FIG. 2 is a schematic diagram showing the configuration of a conventional image forming apparatus.
This image forming apparatus has an image reading apparatus 200 positioned at the upper part of the apparatus and an “image forming part” positioned at the lower part thereof. The portion of the image reading apparatus 200 is the same as that described with reference to FIG. 1, and the same reference numerals as those in FIG.

  An image signal output from the three-line line sensor (imaging means) 6 of the image reading apparatus 200 is sent to the image processing unit 1200 and processed by the image processing unit 1200 to obtain a “writing signal (yellow, magenta, cyan, Signal for writing each color of black) ”.

The image forming unit has a photoconductive photosensitive member 1100 formed in a cylindrical shape as a “latent image carrier”, and around it, a charging roller 1110 as a charging unit, a revolver type developing device 1130, a transfer belt. 1140 and a cleaning device 1150 are provided. As the charging means, a “corona charger” can be used instead of the charging roller 1110.
An optical scanning device 1170 that receives a signal for writing from the image processing unit 1200 and writes to the photosensitive member 1100 by optical scanning performs optical scanning of the photosensitive member 1100 between the charging roller 1110 and the developing device 1130. ing.

Reference numeral 1160 denotes a fixing device, reference numeral 1180 denotes a cassette, reference numeral 1190 denotes a registration roller pair, reference numeral 1220 denotes a paper feed roller, reference numeral 1210 denotes a tray, and reference numeral S denotes a transfer sheet as a “recording medium”.
When image formation is performed, the photoconductive photoreceptor 1100 is rotated at a constant speed in the clockwise direction, the surface thereof is uniformly charged by the charging roller 1110, and is subjected to exposure by optical writing of the laser beam of the optical scanning device 1170. An electrostatic latent image is formed. The formed electrostatic latent image is a so-called “negative latent image”, and the image portion is exposed.
“Image writing” is performed in the order of a yellow image, a magenta image, a cyan image, and a black image in accordance with the rotation of the photoconductor 1100, and the formed electrostatic latent image is stored in each developing unit Y ( Development with yellow toner), M (development with magenta toner), C (development with cyan toner), K (development with black toner) are sequentially reversed and visualized as a positive image. The respective color toner images are sequentially transferred onto the transfer belt 1140 by the transfer voltage application roller 114A, and the respective color toner images are superimposed on the transfer belt 1140 to form a color image.

  The cassette 1180 containing the transfer paper S is detachable from the main body of the image forming apparatus, and the uppermost sheet of the stored transfer paper S is fed by the paper feed roller 1220 when mounted as shown in the figure. The leading edge of the fed transfer paper S is caught by the registration roller pair 1190.

  The registration roller pair 1190 feeds the transfer sheet S to the transfer unit at the timing when the “color image by toner” on the transfer belt 1140 moves to the transfer position. The transferred transfer paper S is superimposed on the color image at the transfer portion, and the color image is electrostatically transferred by the action of the transfer roller 114B. The transfer roller 114B presses the transfer sheet S against the color image during transfer.

The transfer sheet S on which the color image is transferred is sent to the fixing device 1160, where the color image is fixed in the fixing device 1160, passes through a conveyance path by a guide means (not shown), and is discharged onto the tray 1210 by a pair of paper discharge rollers (not shown). The Each time each color toner image is transferred, the surface of the photoreceptor 1100 is cleaned by a cleaning device 1150 to remove residual toner, paper dust, and the like.
The configuration of the image forming unit can be changed to a well-known configuration for forming a single color image.

  A tube lamp such as a xenon lamp or a halogen lamp used in the image reading apparatus shown in FIG. 1 generally consumes a large amount of power and generates a large amount of heat, which increases the temperature of the entire apparatus. The rise in temperature in the image reading apparatus breaks the conjugate relationship of the optical system, and the focus is shifted from the photoelectric conversion element, so that no image is formed and a good image cannot be obtained.

  Therefore, a new illumination light source that replaces a tube lamp such as a xenon lamp has been required. An LED is an example of an illumination light source that consumes less power and generates heat. However, since an LED is a point light source, diffusion, condensing, and an accompanying optical system are required. For example, Patent Document 1 discloses an illumination unit that arranges LEDs in a line and illuminates a document through a light guide. As another known technique, Patent Document 2 discloses an illumination unit in which a long lens system is arranged in front of arranged LEDs to increase the concentration of illumination in a direction orthogonal to the LED arrangement. ing. However, there is a problem of adjustment and cost associated with an increase in the size of an optical system using these LEDs and an increase in the number of parts.

  Then, the illumination unit using the organic electroluminescence (Organic EL) which replaces LED is proposed. In Patent Document 3, two surface light sources are arranged close to each other to illuminate a document surface, a space is provided between the two surface light sources, and document surface information is read from the space.

  However, in the above prior art, the illumination light from the surface light source is the brightest on the center of the light emitting surface, and the position from which the document information is read is at the end of the light emitting surface. The amount of light actually used to read the document information is hardly used, and is a small amount of the amount of light emitted from the light emitting surface, and the illumination efficiency is very poor.

  Further, as a conventional technique for increasing illumination efficiency, Patent Document 4 aims to increase the amount of illumination light at a position where document information is read by arranging a reflective member on a surface light source. Further, Patent Document 5 aims to illuminate a document surface by forming a large number of microprisms on the light emitting surface of a surface light source and enhancing the orientation of the light emitting direction.

  However, in general, it can be assumed that the light emitting surface has a Lambertian light distribution, and considering the amount of light applied to the original surface, it becomes darker in inverse proportion to the square of the distance to the original surface. Therefore, in the configuration according to the invention described in Patent Document 4 in which the reflecting member is arranged between the light emitting surface and the document reading position, the light emission surface is arranged away from the document reading position, so that the illuminance on the surface of the document is likely to be dark and the reflection is reflected. When the configuration is such that light is collected on the member, adjustment is difficult because the illuminance of the document surface is generated by adjusting the position of the reflecting member. Furthermore, the illumination system itself becomes large and it is difficult to reduce the size of the illumination unit.

  Further, in Patent Document 5, when a large number of minute prisms are formed, the manufacturing cost becomes high. Further, since the illumination unit is separated from the document surface by forming the prisms, the illuminance on the document surface becomes dark and efficient. It becomes difficult to illuminate.

  On the other hand, in Patent Document 6, an illumination unit in which a surface emitting light source is directly arranged on a contact glass is presented. However, since the illumination unit is integrated with the contact glass, the illumination unit scans under the contact glass. It cannot be used in an image reading apparatus having a simple structure.

JP 2006-025303 A JP-A-2005-278132 JP 2000-115470 A JP 2007-13913 A Japanese Patent Laid-Open No. 6-217083 JP 2006-60528 A

Accordingly, the present invention has been made in view of the above problems, and an original illuminating unit capable of efficiently illuminating an original without increasing manufacturing costs, and an image reading apparatus and an image forming apparatus using the same. It is a first object to provide
In addition to the above object, the present invention provides a document illumination unit capable of easily correcting a change in the amount of light caused by the angle of view of the lens when document information is reduced and imaged on a line sensor by an imaging lens. A second object of the present invention is to provide an image reading apparatus and an image forming apparatus using the above.

  In order to solve the above problems, a document illumination unit according to the present invention, an image reading apparatus using the document illumination unit, and an image forming apparatus are specifically described in the technical items (1) to (6) below. Has characteristics.

(1): In a document illuminating unit including a light source that illuminates a document surface, the light source is a surface light source having a longitudinal direction and a short direction, and the surface light source has a light emitting surface on at least one side. And the light emitting surface is a concave surface recessed in the longitudinal direction.
According to the configuration (1), it is possible to illuminate from a position relatively close to the document surface without specially increasing the document illumination unit, and the document surface can be illuminated brightly. Miniaturization of the image reading apparatus can be achieved.

(2) The document illumination unit according to (1), wherein the light emitting surface is continuously curved in the longitudinal direction.
According to the configuration (2), since the energy conversion efficiency is higher than that of a conventional tube lamp such as xenon, it is possible to reduce the power consumption in the document illumination unit.

(3): The light emitting surface includes a plurality of light emitting surfaces in the longitudinal direction, and the plurality of light emitting surfaces are arranged so as to form a concave surface recessed in the longitudinal direction. ).
According to the configuration of (3) above, since the energy conversion efficiency is higher than that of a conventional tube lamp such as xenon, it is possible to reduce power consumption in the document illumination unit.

(4): The document illumination unit according to any one of (1) to (3), wherein the surface emitting source includes a substrate and an organic electroluminescence layer formed on the substrate. It is.
According to the configuration of (4) above, the amount of light at the end of the document illumination unit can be increased from the center, and when document information is reduced and imaged by the imaging lens, the end is closer to the end than the center. It is possible to suppress a decrease in the amount of light and easily reduce the difference in the amount of light between the center portion and the end portion on the line sensor.

(5): An image reading apparatus comprising the document illumination unit described in any one of (1) to (4) above.
According to the configuration of (5) above, by using the original illumination unit of the present invention for an image reading apparatus, it is possible to efficiently correct fluctuations in the amount of light caused by the imaging lens and the like, and to reduce the power consumption of the image reading apparatus. This can be reduced, and is advantageous for downsizing the apparatus.

(6): An image forming apparatus comprising the image reading apparatus according to (5).
With configuration (6) above, the power consumption of the image forming apparatus can be reduced by using the image reading apparatus of the present invention.

  According to the document illumination unit and the image reading apparatus and the image forming apparatus using the illumination unit according to the present invention, it is possible to efficiently illuminate the document without increasing the manufacturing cost.

The basic configuration of the document illumination unit, the image reading apparatus using the illumination unit, and the image forming apparatus will be described below.
The embodiments described below are preferred embodiments of the present invention, and thus various technically preferable limitations are given. However, the scope of the present invention is particularly limited in the following description. Unless otherwise stated, the present invention is not limited to these embodiments.

(Original lighting unit)
[First Embodiment]
FIG. 3 is a schematic cross-sectional view in the lateral direction showing the configuration of the first embodiment of the document illumination unit according to the present invention.
FIG. 4 is a schematic perspective view showing the configuration of the first embodiment of the document illumination unit according to the present invention.
The document illumination unit shown in FIG. 3 is a surface emitting device in which an organic electroluminescence layer including a cathode layer 101, an electron transport layer 102, a light emitting layer 103, a hole transport layer 104, and an anode layer 105 is sequentially laminated on a substrate 100. A source 106; In addition to the above configuration, the surface light emitting source may further include a protective layer that protects each layer from environmental loads such as mechanical load and humidity.
FIG. 3 shows a contact glass 1 and a document (document surface) 2 for explaining the function of the document illumination unit of the present invention. These are necessary as components in the illumination unit of the present invention. It is not a thing.

The surface-emitting source 106 having the above-described layer structure has at least one light-emitting surface and has a concave shape that is recessed in the longitudinal direction and the longitudinal direction perpendicular to each other as shown in FIG.
When the document illumination unit of the present embodiment is mounted on an image reading apparatus or an image forming apparatus, the longitudinal direction corresponds to the main scanning direction, and the lateral direction corresponds to the sub-scanning direction, and the document illumination unit is near the document surface. The original is illuminated by scanning.

  The substrate 100 can be made of a known material, but is preferably made of a plastic that is deformable and has excellent mechanical strength and productivity.

  Typical materials used for the electron transport layer 102 are oxadiazole derivatives, triazole derivatives, and the like.

The materials used for the light emitting layer 103 are generally classified into a thin film material deposited by a low molecular compound and a polymer thin film material. The light emitting layer made of a low molecular compound is further roughly classified into an aromatic ring compound, a heterocyclic compound, and a special element-containing compound. Examples of aromatic ring compounds include distyrylbenzene derivatives, which are representative compounds of blue light-emitting materials, and examples of heterocyclic compounds include organic phosphors based on metal complexes of 8-hydroxyquinoline aluminum complexes (Alq complexes). Etc. are known. In addition, as a special element-containing compound, a mixed ligand complex in which one of hydroxyquinolines is substituted with triphenylsilanol (Si compound) and coordinated is a blue-green light emitting layer. It is used.
Moreover, white light can be obtained by color-converting the light emitted from one light emitting layer with a phosphor placed in the next layer. Alternatively, white light can be obtained by stacking a plurality of light-emitting layers that emit light of different wavelengths. In the present invention, a white light source obtained by various other methods can also be used.

  Typical materials used for the hole transport layer 104 are phthalocyanine compounds such as copper phthalocyanine, aromatic amine compounds, and the like.

  The anode layer 105 is preferably a transparent electrode such as indium tin oxide (ITO). Since electrons are injected from the cathode, a metal having a small work function such as magnesium is used as the electrode material. In that case, it is often co-deposited with a small amount of silver to increase adhesion. Other electrodes include m and an organic electrode made of a conjugated polymer. The transparent electrode can also be formed by surface treatment with an acid.

  The cathode layer 101 can be a transparent electrode like the anode layer, and a metal electrode can also be used. By using the metal electrode, light emitted from the light emitting layer can be reflected by the metal surface and extracted to the anode layer side instead of the substrate side, and the object to be illuminated can be illuminated more brightly.

  The surface light source 106 is organic electroluminescence (organic EL), and emits light from the anode layer 15 (light emitting surface) side which is a transparent electrode.

FIG. 5 is a schematic longitudinal sectional view showing the configuration of the first embodiment of the document illumination unit according to the present invention.
In the present embodiment, the surface light emitting source 106 has a concave shape that is continuously curved, and irradiates an opposing document surface position. According to the above configuration, as shown in FIG. 5, the distance from the longitudinal center position to the document surface position is a1, the distance from the longitudinal left end position to the document surface position is b1, and the longitudinal right end position to the document surface. When the distance to the position is c1, the relations a1> b1 and a1> c1 are established.

  That is, when the surface emitting source 106 is mounted on an image reading apparatus or an image forming apparatus, the end in the main scanning direction is closer to the document surface than the center in the main scanning direction (longitudinal direction). It is characterized by being. By adopting a configuration in which the end portion in the main scanning direction is closer to the document surface than the central portion in the main scanning direction, it is possible to change the illumination light amount at the center portion and the light amount at the end portion of the document illumination unit. Become.

  For example, when combined with the imaging lens of the reduction optical system used in the image reading apparatus shown in FIG. 1, in the case of such an imaging lens, when the signal light reflected by the document is incident on the lens, the peripheral light amount Will be lower. Therefore, by using the configuration as shown in FIG. 5, the illuminance at the end portion in the main scanning direction can be increased more than the center portion in the main scanning direction, and the end portion is more than the center portion of the document reading position. Can be high. Therefore, it is possible to satisfactorily correct a decrease in the amount of light on the imaging surface due to the incident angle to the imaging lens.

The surface light source 106 in the present embodiment has a concave shape that is continuously curved in the longitudinal direction and a planar shape in the short direction, but the light emitting surface in the short direction. The shape may be any shape, and may be a curved shape in the short direction.
Further, the concave shape in the longitudinal direction may take any form as long as the configuration can correct the decrease in the light amount. For example, a configuration of a light emitting surface in which a plane and a curved surface are combined may be used, or a configuration in which light emitting surfaces are discontinuously arranged with a gap in the longitudinal direction may be used. can do.

[Second Embodiment]
FIG. 6 is a schematic longitudinal sectional view showing the configuration of the second embodiment of the document illumination unit according to the present invention.
In the present embodiment, the surface light source 106 has three light emission planes in the longitudinal direction, and the three light emission planes have a concave shape arranged so as to form a concave surface in the longitudinal direction. Irradiate.
In FIG. 5, the light emitting plane located at the center is arranged in parallel with the document surface, and the light emitting planes located on the left and right sides are arranged at an angle so as to approach the document surface as it reaches the end.
According to the above configuration, as shown in FIG. 6, the distance from the longitudinal center position to the document surface position is a2, the distance from the longitudinal left edge position to the document surface position is b2, and the longitudinal right edge position to the document surface. When the distance to the position is c2, the relationship of a2> b2 and a2> c2 is established.

  According to the present embodiment, the illuminance at the central portion in the main scanning direction and the end portion in the main scanning direction can be changed by changing the distance from the light emitting point to the top of the document in the same manner as described in the first embodiment. Thus, it is possible to change the amount of light at the central portion in the main scanning direction and the end portion in the main scanning direction of the document illumination unit.

[Third Embodiment]
FIG. 7 is a schematic longitudinal sectional view showing the configuration of the third embodiment of the document illumination unit according to the present invention.
In the present embodiment, the surface light source 106 has five light emission planes in the longitudinal direction, and the five light emission planes have a concave shape arranged so as to form a concave surface in the longitudinal direction. Irradiate.
All the light emission planes are arranged parallel to the document surface, and the light emission plane located at the center in FIG. 6 is arranged farthest from the document surface, and is arranged so as to be closer to the document surface as it approaches both ends. This is a so-called stepped configuration.
According to the above configuration, as shown in FIG. 6, the distance from the longitudinal center position to the document surface position is a3, the distance from the longitudinal left end position to the document surface position is b3, and the longitudinal direction right end position to the document surface. When the distance to the position is c3, the relationship of a3> b3 and a3> c3 is established.
According to the present embodiment, the illuminance at the central portion in the main scanning direction and the end portion in the main scanning direction can be changed by changing the distance from the light emitting point to the top of the document in the same manner as described in the first embodiment. Thus, it is possible to change the amount of light at the central portion in the main scanning direction and the end portion in the main scanning direction of the document illumination unit.

  In the first to third embodiments, in order to correct the decrease in the peripheral light amount due to the reduction type imaging lens, the one that increases the peripheral light amount of the illumination unit has been presented. It is also possible to increase the amount of light at the center in the scanning direction.

(Image reading device)
FIG. 8 is a schematic cross-sectional view showing the configuration of the first embodiment of the reading unit in the image reading apparatus of the present invention.
The reading unit in the image reading apparatus according to the present invention is configured by a housing 11 having an equal magnification imaging element 14 typified by a SELFOC lens array and a C-MOS disposed on the electric circuit board 12 or a photoelectric conversion element such as a CCD. The line sensor 13 and the original illumination units 15a and 15b of the present invention, and the entire reading unit scans the vicinity of the contact glass 2 in the horizontal direction in FIG. The document information is read while photoelectrically converting the reflected light of the original with a line sensor.
Although not shown, the document illumination units 15a and 15b have a concave shape curved in a direction perpendicular to the drawing. Further, as shown in the drawing, the document illumination units 15a and 15b in the present embodiment both have a concave shape curved in the short direction.

FIG. 9 is a schematic sectional view showing the configuration of the second embodiment of the reading unit in the image reading apparatus of the present invention.
In the second embodiment of the reading unit, the reflecting mirrors 27a, b, c and the imaging lens 24, the line sensor 26 using the CCD, the electric circuit 25, and the position adjustment and fixing of the line sensor and the electric circuit are provided in the housings 21 and 22, respectively. And a document illumination unit 28a, b of the present invention. The reading unit illuminates the original 2 placed on the contact glass with the illumination unit while scanning the vicinity of the contact glass 2 in the horizontal direction in the figure, and reflects the reflected light from the original with a reflection mirror to form an imaging lens. The image is reduced and imaged, and the original information is read while photoelectrically converting the line sensor.
Although not shown, the document illumination units 28a and 28b have a concave shape curved in a direction perpendicular to the drawing. Further, as shown in the drawing, the document illumination units 28a and 28b in the present embodiment both have a concave shape curved in the short direction.

  By using the original illumination unit of the present invention for the present reading unit, it is possible to perform illumination that is small and bright, has low power consumption, and has no illumination unevenness, and the illumination unit of the present invention changes the light quantity between the center and the periphery. Therefore, it is possible to appropriately correct the occurrence of a difference in the amount of imaging light on the line sensor between the center and the periphery of the imaging lens.

  Although not shown, the document illumination unit of the present invention can also be used in the conventional image reading apparatus shown in FIG.

(Image forming device)
Similarly, although not shown, by applying the original illumination unit or the image reading apparatus of the present invention to the conventional image forming apparatus shown in FIG. 2, a small and low power consumption image forming apparatus can be obtained. .

It is the schematic which shows the structure of the conventional image reading apparatus. It is the schematic which shows the structure of the conventional image forming apparatus. FIG. 3 is a schematic cross-sectional view in the short-side direction showing the configuration of the first embodiment of the document illumination unit according to the present invention. It is a schematic perspective view which shows the structure of 1st Embodiment in the original document illumination unit which concerns on this invention. 1 is a schematic longitudinal sectional view showing the configuration of a first embodiment of a document illumination unit according to the present invention. FIG. 5 is a schematic longitudinal sectional view showing a configuration of a second embodiment of a document illumination unit according to the present invention. It is a longitudinal cross-sectional schematic diagram which shows the structure of 3rd Embodiment in the original illumination unit which concerns on this invention. 1 is a schematic cross-sectional view illustrating a configuration of a reading unit according to a first embodiment in an image reading apparatus of the present invention. It is a schematic sectional drawing which shows the structure of 2nd Embodiment of the reading unit in the image reading apparatus of this invention.

Explanation of symbols

1 Contact glass 2 Original 3 First traveling body 3A LED
3B reflector 3C first mirror 4 second traveling body 4A second mirror 4B third mirror 5 image reading lens 6 line sensor 6A, 6B, 6C photoelectric conversion element 11 housing 12 electric circuit board 13 line sensor 13
14 Equal-magnification imaging elements 15a, 15b Illumination unit 21 Housing 22 Housing 23 Holding mechanism 24 Imaging lens 25 Electrical circuit 26 Line sensor 27a, 27b, 27c Reflection mirror 28a, 28b Illumination unit 100 Substrate 101 Cathode layer 102 Electron transport layer 103 Light emitting layer 104 Hole transport layer 105 Anode layer 106 Sheet-like light source 200 Image reader 1100 Photoreceptor 1110 Charging roller 1130 Developing device 1140 Transfer belt 1150 Cleaning device 1160 Fixing device 1170 Optical scanning device 1180 Cassette 1190 Registration roller pair 1200 Image processing Section 1210 Tray 1220 Paper feeding roller S Transfer paper (recording medium)

Claims (6)

In a document illumination unit having a light source that illuminates the document surface,
The light emitting source is a surface light emitting source having a longitudinal direction and a lateral direction,
The surface emitting source has a light emitting surface on at least one side,
The document illumination unit, wherein the light emitting surface is a concave surface recessed in the longitudinal direction.   The document illumination unit according to claim 1, wherein the light emitting surface is continuously curved in the longitudinal direction. The light emitting surface comprises a plurality of light emitting surfaces in the longitudinal direction,
2. The document illumination unit according to claim 1, wherein the plurality of light emitting surfaces are arranged so as to form a concave surface recessed in the longitudinal direction.   4. The document illumination unit according to claim 1, wherein the surface emitting source includes a substrate and an organic electroluminescence layer formed on the substrate. 5.   An image reading apparatus comprising the document illumination unit according to claim 1.   An image forming apparatus comprising the image reading apparatus according to claim 5.

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