Image reading device and image forming apparatus

Abstract

To improve the accuracy of skew correction.SOLUTION: An image reading device comprises: a conveying unit that conveys a document along a conveyance path; a skimming glass that forms part of the conveyance path; a reading unit having a light source that irradiates the document with light, and a reading part that reads an image of the document conveyed through the conveyance path as reflected light through the skimming glass; and a platen member 306 that is arranged opposite to the skimming glass at a reading position of the reading unit and forms the conveyance path together with the skimming glass. An opposite surface of the platen member 306 opposite to the skimming glass has an uneven surface part 320 with a shape in which projections 322 are arranged regularly and continuously.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present invention relates to an image reading device that reads an image on a sheet-like document, and an image forming apparatus to which the image reading device is applied. [Background technology]

[0002] Conventionally, an image reading device has been developed that detects the amount of skew of a document conveyed from a document conveying device using a reading sensor that reads the image of the document and performs skew correction by image processing (see Patent Document 1). In this image reading device, when the leading edge of the document passes through a platen member (opposing member) provided on the opposite side of the reading sensor, the leading edge of the document projected onto the platen member and its guide is read. At the same time, the amount of skew of the document is detected by reading the brightness change of the shadow formed on the platen member by illuminating the leading edge of the document with the illumination of the reading device.

[0003] From the viewpoint of image processing, if a predetermined luminance change does not occur within the region where the image is read, or if a luminance change occurs before the leading edge of the document, there is a possibility that an area other than the leading edge of the document will be detected. In such a case, the amount of skew cannot be detected correctly, and there is a risk that skew correction cannot be performed correctly. Therefore, it is conceivable to form a random uneven shape on the surface of the platen member, and to easily diffuse the reflection of the illumination light when it is reflected by the platen member, thereby making it possible to read the leading edge of the document with high accuracy. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2010-118911 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the image reading device described in the above-mentioned Patent Document 1, even if a random uneven shape is formed on the surface of the platen member, there is a possibility that some parts may generate specular reflection depending on the condition of the surface. In such parts, the accuracy of detecting the shadow of the leading edge of the document may decrease, which may decrease the accuracy of document skew correction.

[0006] SUMMARY OF THE DISCLOSURE An object of the present invention is to provide an image reading device and an image forming device that are capable of improving the accuracy of skew correction. [Means for solving the problem]

[0007] One aspect of the present invention is an image reading device comprising a reading unit having a transport section which transports a document along a transport path, a transparent member which forms part of the transport path, a light source which irradiates light toward the document, and a reading section which reads an image of the document transported by the transport section through the transparent member as reflected light, and an opposing member which is arranged opposite the transparent member at a reading position of the reading unit and which forms the transport path together with the transparent member, wherein the opposing surface of the opposing member which faces the transparent member has an uneven surface portion having a shape in which convex portions are arranged in a regular, continuous pattern.

[0008] Another aspect of the present invention is an image reading device comprising a reading unit having a transport section which transports an original document along a transport path, a transparent member which forms part of the transport path, a light source which irradiates light toward the original document, and a reading section which reads an image of the original document transported by the transport section through the transparent member as reflected light, and an opposing member which is arranged opposite the transparent member at a reading position of the reading unit and which forms the transport path together with the transparent member, wherein the opposing surface of the opposing member which faces the transparent member has an uneven surface portion having a shape in which recesses are arranged in a regular, continuous pattern.

[0009] Another aspect of the present invention is an image reading device comprising a reading unit having a transport section which transports a document along a transport path, a transparent member which forms part of the transport path, a light source which irradiates light toward the document, and a reading section which reads an image of the document transported by the transport section through the transparent member as reflected light, and an opposing member which is arranged opposite the transparent member at a reading position of the reading unit and which forms the transport path together with the transparent member, wherein the opposing surface of the opposing member which faces the transparent member has an uneven surface portion in which convex portions and concave portions are arranged in a regular, continuous pattern.

[0010] Another aspect of the present invention is an image forming apparatus comprising the above-mentioned image reading device that reads an image of a document, and an image forming unit that forms an image on a sheet based on the image information read by the image reading device. Effect of the Invention

[0011] According to the present invention, the accuracy of skew correction can be improved. [Brief description of the drawings]

[0012] [Figure 1] 1 is a cross-sectional view showing an image forming apparatus according to an embodiment. [Diagram 2] 1 is a perspective view showing an automatic document reading device according to an embodiment; [Diagram 3] 1 is a cross-sectional view showing an automatic document reading apparatus according to an embodiment. [Figure 4] FIG. 2 is a cross-sectional view showing a reading unit according to the embodiment. [Diagram 5] 4A and 4B are cross-sectional views showing irradiation and reflection from a lighting unit according to an embodiment. [Figure 6] 1A and 1B are cross-sectional views showing a platen member according to an embodiment, in which (a) is a surface having random projections and recesses, (b) is a surface having random projections and recesses with some flat surfaces, and (c) is a surface having a projection and recess portion according to this embodiment. [Figure 7]7A and 7B are explanatory diagrams for reading the leading edge of a document using the platen member shown in FIG. 6A, where (a) is a plan view and (b) is a graph showing the reading level versus the main scanning position. [Figure 8] 7A and 7B are explanatory diagrams when the platen member shown in FIG. 6B is used to read the leading edge of a document, where (a) is a plan view and (b) is a graph showing the read level versus the main scanning position. [Figure 9] 9A and 9B are diagrams showing the concave-convex surface portion of the platen member according to the embodiment, in which (a) is a perspective view and (b) is a cross-sectional view taken along line AA in FIG. 9A. [Figure 10] 6 is a graph showing the relationship between the height of projections and recesses of a mold when molding the platen member according to the embodiment and the height of projections and recesses of a molded product. [Figure 11] 11 is a graph showing the relationship between the position in the main scanning direction and the height of the convex portions relative to the pitch of the convex portions when molding the platen member according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, exemplary embodiments of the present invention will be described with reference to the drawings.

[0014] 1 is a schematic diagram of an automatic document reading device 101, which is an example of an image reading device according to an embodiment of the present disclosure, and an image forming device 10 including the automatic document reading device 101. First, a schematic configuration of the image forming device 10 will be described.

[0015] [Image forming equipment] The image forming apparatus 10 of this embodiment is a tandem intermediate transfer type copying machine that outputs a full color image onto a recording material by electrophotography. The image forming apparatus 10 has an image forming section 12 and a control section 30. The image forming section 12 has image forming stations PY, PM, PC, and PK that respectively form toner images of yellow (Y), magenta (M), cyan (C), and black (K), an intermediate transfer unit 70, and a fixing device 14. The image forming section 12 forms an image on a sheet S based on image information read by an automatic document reader 101.

[0016] When the image forming apparatus 10 performs an image forming operation, each of the image forming stations PY to PK creates a single-color toner image by an electrophotographic process. The image forming stations PY to PK have the same configuration except for the color of the toner, so here, the yellow image forming station PY will be described. The photosensitive drum 1 as an image carrier is rotated in a predetermined rotation direction R1, and the charger 2 uniformly charges the surface of the photosensitive drum 1. The exposure device 3 scans the photosensitive drum 1 with a laser beam modulated based on data obtained by decomposing the image data into color components, and writes an electrostatic latent image on the drum surface. This latent image is developed with a developer supplied from the development device 4 and visualized as a toner image.

[0017] In the intermediate transfer unit 70, an intermediate transfer belt 7 as an intermediate transfer body is wound around a drive roller 71, a secondary transfer inner roller 72, and a tension roller 73. When an image forming operation is started, the intermediate transfer belt 7 is rotated by the drive roller 71 in a rotation direction R2 in which it rotates together with the photosensitive drum 1. The toner images formed in each image forming station PY to PK and carried on the photosensitive drum 1 are primarily transferred from the photosensitive drum 1 to the intermediate transfer belt 7 at the primary transfer portion N1 by a bias electric field formed by the primary transfer roller 5. At this time, the toner images of each color are transferred in multiple layers so that they overlap each other, thereby forming a full-color toner image on the surface of the intermediate transfer belt 7. In addition, any deposits such as transfer residual toner remaining on the photosensitive drum 1 without being transferred to the intermediate transfer belt 7 are removed by the drum cleaner 6 of each station.

[0018] A secondary transfer roller 8 is disposed at a position facing the secondary transfer inner roller 72 with the intermediate transfer belt 7 interposed therebetween, and a secondary transfer portion N2 is formed as a nip portion between the secondary transfer roller 8 and the intermediate transfer belt 7. The toner image carried on the intermediate transfer belt 7 is secondarily transferred, at the secondary transfer portion N2, onto a sheet S, which is a recording material transported one by one toward the secondary transfer portion N2. Adherents such as transfer residual toner that remain on the intermediate transfer belt 7 without being transferred to the sheet S are removed by a belt cleaner 75.

[0019] The sheet S onto which the toner image has been transferred in the secondary transfer portion N2 is sent to the fixing device 14 via a conveyor belt 13. The fixing device 14 has a pair of rotating bodies that sandwich and convey the sheet S, and a heat source such as a halogen lamp that heats the toner image on the recording material, and heats and pressurizes the toner image while conveying the sheet S with the pair of rotating bodies. This causes the toner to melt and then become fixed, resulting in an image fixed on the sheet S.

[0020] In parallel with this process, a transport operation is performed in which the sheet S is fed and transported toward the secondary transfer portion N2. The image forming apparatus 10 has a plurality of feeding cassettes 11 for storing the sheets S in the lower portion of the apparatus main body 19, and feeds the sheets S one by one from one of the feeding cassettes 11. As the sheet S, a variety of sheets of different sizes and materials can be used, including paper such as plain paper and thick paper, sheet materials with a surface treatment such as plastic film, cloth, and coated paper, and sheet materials with special shapes such as envelopes and index paper.

[0021] The sheets S stacked in the feed cassette 11 are fed out of the feed cassette 11 by the feed roller 17, and sent to the registration roller 15. The registration roller 15 sends the sheet S toward the secondary transfer portion N2 in synchronization with the start of the formation of toner images by the image forming stations PY to PK. The sheet S, on which an image is formed by passing through the secondary transfer portion N2 and the fixing device 14, is conveyed through a discharge path inside the image forming apparatus, and is discharged to a discharge tray 16 provided on the side of the apparatus main body 19.

[0022] The control unit 30 has a CPU, RAM, and ROM, and controls each unit in the image forming apparatus 10. The CPU outputs an output signal to each electric component to operate the electric component at the desired timing and with the required amount of control based on the detection signals input from each sensor and the information stored in the ROM. Therefore, it is the CPU that actually controls the electric components. The ROM and RAM store information data required for controlling each unit, and the CPU reads the information data stored in the ROM and writes it to the RAM. Note that the control unit 30 also controls the automatic document reader 101.

[0023] Instead of the above configuration, the image forming unit 12 may be, for example, a direct transfer type electrophotographic mechanism that directly transfers a toner image formed on a photoreceptor to the sheet S without using an intermediate transfer body. Also, the image forming unit 12 is not limited to the electrophotographic type, and may be, for example, an inkjet type printing unit or an offset printing mechanism.

[0024] [Automatic document reader] Next, the configuration of an automatic document reading device 101, which is an image reading device according to this embodiment, will be described with reference to Fig. 2 and Fig. 3. Fig. 2 is a perspective view of the automatic document reading device 101 according to this embodiment, and Fig. 3 is a schematic diagram showing the cross-sectional configuration thereof.

[0025] The automatic document reading device 101 includes an ADF 102 (Auto Document Feeder) that transports documents, and a reader 103 that reads image information from a moving document transported by the ADF 102 and a stationary document placed on a document table glass 314. The ADF 102 is connected to the reader 103 fixed to the top of the device body 19 of the image forming device 10 via an opening / closing hinge provided on the rear side of the top surface of the reader 103 so as to be able to open and close freely.

[0026] The reader 103 has a platen glass 314, a reading unit 311 for the front side, and a reading movement guide 316. The reading unit 311 will be described later. The reader 103 performs a fixed reading operation of scanning the front side of a document placed on the platen glass 314, which is a transparent member, through the platen glass 314 while moving the reading unit 311 along the reading movement guide 316 using a motor. In this case, the reading unit 311 obtains a line image in the main scanning direction (alignment direction of the CCD 408) line by line, and integrates the line images in the movement direction of the reading unit 311, which is the sub-scanning direction, to obtain image data of the entire document.

[0027] The reader 103 is also provided with a front side flow reading glass 313, which is a transparent member separate from the document table glass 314. When the automatic document reader 101 performs a flow reading operation in which image data is read while conveying documents one by one by the ADF 102, the reading unit 311 scans the front side (first surface) of the document through the flow reading glass 313 and reads the image data of the front side. The flow reading glass 313 is an example of a transparent member forming a part of the conveying path. In this case as well, the reading unit 311 obtains line images in the main scanning direction line by line, and integrates the line images with respect to the document conveying direction DF, which is the sub-scanning direction, to obtain image data of the entire front side of the document. In addition, in FIG. 3, the position X1 of the reading unit 311 is the flow reading position, and the position X2 is the reading end position of fixed reading.

[0028] The ADF 102 includes a document tray 200, a pickup roller 300, a pair of separation rollers 302, a pair of pull-out rollers 303, a pair of upstream lead rollers 305, a pair of intermediate lead rollers 307, a pair of downstream lead rollers 309, a pair of discharge rollers 310, and a discharge tray 201. The document tray 200 is a loading section capable of loading a plurality of documents D, which are sheets to be read. The pickup roller 300 contacts the upper surface of the document stack loaded on the document tray 200, and sends the topmost document toward the pair of separation rollers 302. The pair of separation rollers 302 has a conveying roller and a separation roller that form a separation nip, and conveys the documents sent by the pickup roller 300 while separating them one by one. The separation roller that separates the document D is connected to a shaft fixed to the frame of the ADF 102, for example, via a torque limiter, and separates the document D by applying a frictional force to the document D in the separation nip.

[0029] The pull-out roller pair 303, the lead upstream roller pair 305, the lead intermediate roller pair 307, the lead downstream roller pair 309, and the discharge roller pair 310 are arranged along a conveying path curved in a U-shape from the document tray 200 toward the discharge tray 201 arranged below it. These roller pairs constitute a conveying section 330 that conveys the document D along the conveying path via the reading position. The pull-out roller pair 303 holds the document that has passed through the separation nip and conveys it toward the lead upstream roller pair 305. The lead upstream roller pair 305 conveys the document through a position where the reading unit 311 scans the surface of the document through a flow reading glass 313. The reading unit 311 and the flow reading glass 313 are arranged between the lead upstream roller pair 305 and the lead intermediate roller pair 307 with respect to the conveying direction DF of the document D on the conveying path inside the ADF 102.

[0030] Here, the ADF 102 of the present embodiment includes a reading unit 312 for the back side that reads image data from the back side (second surface) of the document, and a back side flow reading glass 315 that is a transparent member. The reading unit 312 will be described later. The reading unit 312 and the flow reading glass 315 are disposed between the lead intermediate roller pair 307 and the lead downstream roller pair 309 in the transport direction DF in the transport path inside the ADF 102. In the flow reading operation, the document D is transported through a position where the reading unit 312 scans the back side of the document D through the flow reading glass 315. The flow reading glass 315 is an example of a transparent member that forms a part of the transport path. In this case, the reading unit 312 obtains line images in the main scanning direction line by line, and the line images are integrated in the transport direction DF of the document D, which is the sub-scanning direction, to obtain image data of the entire back side of the document D. That is, the reading unit 312 can scan the back side of the document D at the back side reading position and read the image data on the back side in parallel with the reading unit 311 reading the image data on the front side.

[0031] The document D that has passed the back-side reading position is transported by the downstream lead roller pair 309 toward the discharge roller pair 310. The discharge roller pair 310 discharges the document D, from which image data has been read, onto the discharge tray 201. When multiple documents D are loaded on the document tray 200, the automatic document reader 101 repeats a series of operations including feeding, separating, transporting, reading image data from the front and / or back side, and discharging the documents D until the skim-reading operation of the final document is completed.

[0032] [Reading unit] Next, the reading units 311 and 312 will be described with reference to Figures 3 and 4. Figure 3 is a cross-sectional view of the reading units 311 and 312 and their surrounding configuration. Note that the reading units 311 and 312 have the same configuration, with only differences in installation position and orientation, so only the reading unit 311 will be described, and the reading unit 312 will be given the same reference numeral and a detailed description will be omitted.

[0033] The reading unit 311 is an integrated scanning optical unit of the CCD (Charge Coupled Devices) type. The reading unit 311 has a box frame 410, an illumination unit 400, a first mirror 402, a second mirror 403, a third mirror 404, a fourth mirror 405, a fifth mirror 406, a lens unit 407, and a CCD 408. The illumination unit 400 is attached to the upper part of the box frame 410. The illumination unit 400 has a first illumination section 41 and a second illumination section 42. In the reading unit 311, the first illumination section 41 irradiates light toward the document D from the upstream side of the transport direction DF, and the second illumination section 42 irradiates light from the downstream side of the transport direction DF. In the reading unit 312, the first illumination section 41 irradiates light toward the original D from the downstream side in the transport direction DF, and the second illumination section 42 irradiates light from the upstream side in the transport direction DF. The illumination unit 400 is an example of a light source that irradiates light toward the original D. Note that other image sensor units may be used as the reading units 311 and 312. For example, a CIS type may be applied instead of the CCD type.

[0034] As shown in Fig. 4, illumination light is emitted from an illumination unit 400 mounted on the reading unit 311, and illuminates the platen member 306 and the front surface of the original D through a flow reading glass 313. The light reflected from the platen member 306 and the original D is incident on a CCD 408 through the flow reading glass 313 and a mirror and a lens provided in the reading unit 311, and image information of the front surface of the original D is acquired. Meanwhile, illumination light is emitted from an illumination unit 400 mounted on the reading unit 312, and illuminates the platen member 308 and the back surface of the original D through a flow reading glass 315. The light reflected from the platen member 308 and the original D is incident on the CCD 408 through the flow reading glass 315 and a mirror and a lens provided in the reading unit 312, and image information of the back surface of the original D is acquired. The CCD 408 is an example of a reading unit that reads an image of the original D conveyed by the conveying unit 330 through the flow reading glasses 313 and 315 as reflected light.

[0035] The platen members 306 and 308 are disposed opposite the flow reading glasses 313 and 315 at the reading positions of the reading units 311 and 312, and are an example of opposing members that form a transport path together with the flow reading glasses 313 and 315. When reading the original D, the platen members 306 and 308 are configured to retract so that the original transport path widens in the direction Y perpendicular to the original D in accordance with the thickness of the original D. This prevents image defects caused by a decrease in the original transport speed due to a thick original D.

[0036] [Configuration for reading the leading edge of the manuscript] Next, the configuration for reading the leading edge of a document is shown in Fig. 5. Illumination light L1 emitted from an illumination unit 400 mounted on the reading unit 311 is reflected by the platen member 306 and the document D, generating diffuse reflection light L2 and specular reflection light L3. The diffuse reflection light L2 and specular reflection light L3 are read by a CCD 408 through a reading line 401 to read an image. At this time, as shown in Fig. 6(a), a specular reflection prevention shape is provided so that the specular reflection light L3 is not read toward the CCD 408 due to the surface properties of the platen member 317.

[0037] [Skew Correction] Next, skew correction during image reading will be described with reference to Fig. 3 to Fig. 7. Here, in this embodiment, the control of skew correction is executed by the control unit 30 provided in the image forming apparatus 10, but the present invention is not limited to this, and the automatic document reading apparatus 101 or an external device may have a control unit and the control unit may execute the skew correction. That is, the control unit 30 can execute skew correction based on the image of the document D read by the CCD 408, and the control unit 30 may be installed anywhere.

[0038] 3, the document D read by the reading units 311 and 312 is read without aligning the leading edge of the document D, so there is a risk that the document D may be skewed before passing through the flow-reading glasses 313 and 315, and the read document may be read crooked. For this reason, the amount of skew of the transported document is detected from the read image, and the inclination (skew) of the image is corrected using the result.

[0039] Fig. 7(a) is a diagram showing the leading edge of an image when the surface of the platen member 317 is white and has a random anti-regular reflection surface as shown in Fig. 6(a), and a white skewed original D is read. For this image, as shown in Fig. 7(b), the reading levels of main scanning positions W1, W2, and W3, which are predetermined positions in the main scanning direction, are sampled for each sub-scanning line. Here, although three predetermined positions are shown in Fig. 7(b), positions may be set to two or more main scanning positions and less than the maximum number of pixels to be read in the main scanning direction.

[0040] FIG. 7(b) is a diagram showing image reading levels at main scanning positions W1, W2, and W3 in FIG. 7(a). When detecting the leading edge of the document D, a predetermined reading level is set as a brightness threshold TH, and the main scanning position that first exceeds the brightness threshold TH is detected as the leading edge of the document or a shadow SH (see FIG. 5). The leading edge position at main scanning position W1 is P1, the leading edge position at main scanning position W2 is P2, and the leading edge position at main scanning position W3 is P3. If the document is inclined as shown in FIG. 7(a), the leading edge position of the document at each main scanning position is different. Using these main scanning positions W1, W2, and W3 and the leading edges P1, P2, and P3 at each main scanning position, the boundary line G1 between the platen member 317 and the document D can be calculated, and the inclination of the document D can be obtained.

[0041] 6(a) is actually formed, a possible approach is to form a fine uneven shape by, for example, honing or embossing the surface of a mold that forms the paper passing surface of the platen member 317. By manufacturing the platen member 317 using this mold, it is possible to easily diffuse the reflection of illumination light when it is reflected by the platen member 317. In other words, it becomes possible to read the leading edge of the document while preventing the reading level when reading reflected light by the reading units 311 and 312 from being inadvertently changed by the specularly reflected light from the platen member 317.

[0042] However, conventional honing and texturing processes are surface processing methods that involve spraying glass beads or the like onto the mold surface, or etching the surface with chemicals. As a result, the shape of the unevenness on the mold surface is irregular, making it difficult to control the depth of the unevenness and the density of the unevenness. As a result, there are places on the platen member 317 that do not have an uneven shape, and slight differences in the molding conditions (temperature, pressure, etc.) of the mold can prevent the unevenness from being transferred to the part surface, making it impossible to form the unevenness.

[0043] A case where the specular reflection prevention surface of the platen member 318 is partially flat as shown in FIG. 6(b) will be described. In this case, as shown in FIG. 8(a), when a white skewed original D is read by specular reflection light from the flat surface of the specular reflection prevention surface of the platen member 318, there is a risk that the specular reflection light from the platen member 318 will be read before the leading edge of the image is actually read. When the reading levels of the predetermined main scanning positions W1, W2, and W3 of this image are sampled for each sub-scanning line, the luminance of the portion where the specular reflection light is read exceeds the luminance threshold TH as shown in FIG. 8(b). This may cause the main scanning positions detected as the leading edge of the original to be erroneously detected as P11, P12, and P13 at the main scanning positions W1, W2, and W3. As a result, the skew of the leading edge of the original is calculated as shown in G2 in FIG. 8(a), and the skew of the original D is erroneously detected, so that the skew correction accuracy is reduced and it may not be possible to correctly correct the skew of the original D.

[0044] Therefore, in this embodiment, the surface of the platen member 306 (308) is provided with an uneven surface portion 320 that can stably transfer the surface shape under the molding conditions and has a periodic continuous uneven shape, thereby suppressing the deterioration of the skew correction accuracy due to the regular reflection light. Here, as shown in FIG. 9(a), the facing surface 321 of the platen member 306 (308) facing the flow reading glass 313 (315) has an uneven surface portion 320 in a shape in which convex portions 322 are regularly and continuously arranged. That is, the facing surface 321 is subjected to a regular reflection prevention treatment that prevents the illumination light irradiated from the illumination unit 400 to the platen member 306 from being regularly reflected into the reading unit 311. The uneven surface portion 320 is provided to face the entire reading range of the reading unit 311 in the width direction of the document D.

[0045] Here, in the present embodiment, the uneven surface portion 320 is defined as a collection of protruding portions 322 protruding from the opposing surface 321, and the uneven surface portion 320 is defined as a collection of the protruding portions 322. However, the definition of the uneven surface portion 320 is not limited to this, and may vary depending on how the opposing surface 321 is taken. For example, as shown in FIG. 9(b), the uneven surface portion 320 may be defined as a shape in which recesses recessed from the opposing surface 321A are regularly and continuously arranged. Furthermore, the uneven surface portion 320 may be defined as a shape in which protruding portions and recesses are regularly and continuously arranged on the opposing surface 321B.

[0046] In this embodiment, the uneven surface portion 320 is composed of a surface 322a inclined with respect to the opposing surface 321, and does not have a surface parallel to the opposing surface 321. This makes it possible to prevent specular reflection light from occurring. Also, as shown in FIG. 9(a), the convex portion 322 is formed in a straight line when viewed from a direction perpendicular to the opposing surface 321. Note that the convex portion 322 can be formed in other shapes, such as a curved shape or a zigzag shape, when viewed from a direction perpendicular to the opposing surface 321, but is preferably a simple straight line from the viewpoint of accuracy during molding using a mold described later.

[0047] 9(b), in a cross section cut at a plane (AA) intersecting (perpendicular to) the direction DC in which the apexes 322b of the convex portions 322 continue, the apexes 322b of the convex portions 322 have an arc shape. Similarly, the bottoms 322c between the convex portions 322 also have an arc shape in cross section at the cut plane AA. This makes it possible to extremely reduce the area of ​​the uneven surface portion 320 that generates light rays toward the CCD 408, so that almost no regular reflection light is generated, and it is possible for the uneven surface portion 320 to have no surface that is substantially parallel to the opposing surface 321.

[0048] The direction DC in which the vertices of the convex portion 322 are continuous and the transport direction DF form an angle of 10 degrees or more and 80 degrees or less. That is, the direction DC and the main scanning direction W of the reading unit 311 form an angle of 10 degrees or more and 80 degrees or less. Here, if the angle between the direction DC and the transport direction DF is less than 10 degrees or more than 80 degrees, there is a risk that the light ray irradiated from the illumination unit 400 arranged on the upstream and downstream sides of the transport direction DF is reflected by the inclined surface 322a, causing specular reflection. According to this embodiment, even if the light ray irradiated from the illumination unit 400 is reflected by the inclined surface 322a, it is possible to prevent the light ray from being reflected as specular reflection into the reading unit 311. Furthermore, in this embodiment, the angle between the direction DC and the transport direction DF is set to 45 degrees, and it is possible to effectively prevent the light ray from the illumination unit 400 from being reflected as specular reflection into the reading unit 311.

[0049] The size of the uneven surface portion 320 is determined based on the resolution of the CCD 408. Hereinafter, the pitch p1 of the convex portion 322 means the pitch in a cross section cut by a plane (AA) intersecting (orthogonal to) the direction DC in which the vertices 322b of the convex portion 322 continue. If the pitch p1 is too large compared to the resolution of the CCD 408, the uneven surface portion 320 will be read as a striped pattern, so it is necessary to make it smaller than that. In addition, when the range of the pitch p1 is set, the range of the height h1 is also set accordingly, as will be described in detail later. In this embodiment, the height h1 is 50 μm or less, and the pitch p1 is 130 μm or less. In this embodiment, the uneven surface portion 320 is white.

[0050] [Example] Here, FIG. 10 shows the transferability when the uneven surface portion 320 of the shape of this embodiment is formed using synthetic resins of PC (polycarbonate) and ABS (acrylonitrile-butadiene-styrene) as an example of the platen member 306. When a fine shape is formed using such a synthetic resin, if the pitch p1 of the convex portion 322 is narrow, there is a limit to the uneven height h1 that can be transferred to the molded product due to the uneven height of the mold. If the uneven height h1 of the molded product is low compared to the uneven height of the mold, the triangular shape provided on the mold is not transferred, and the approximately flat shape portion increases. If the magnitude of the regular reflection light reflected by the approximately flat shape portion increases, the regular reflection light when the platen member 306 is read becomes stronger and is resolved as a bright spot, so that the brightness threshold TH is exceeded and the bright spot is erroneously detected as the leading edge of the document. Therefore, it is necessary to determine the maximum pitch of the convex portion 322 according to the optical system and reading resolution of the device so that the read regular reflection light is not resolved.

[0051] In this embodiment, if pitch p1 is made larger than 145 μm, the uneven surface portion 320 will be read as a striped pattern, so pitch p1 is set to 145 μm or less. Then, from FIG. 10, the maximum height of the mold to be transferred is determined from pitch p1 of the protrusions 322. By forming the shape determined in this way on the mold that molds the platen member 306, it is possible to obtain an uneven shape that has stable transferability against changes in molding conditions.

[0052] In this embodiment, by setting the pitch p1 of the convex portions 322 to 145 μm or less, it is possible to prevent the regular reflection light from being resolved, so the pitch p1 was set to 105 μm, which is an even shorter interval from that. In this embodiment, the height h1 of the convex portions 322 of the molded product was set to 30 μm so that the width of the untransferred surface generated per one convex portion 322 of the molded product would be small based on the pitch p1 determined here and the height of the mold irregularities in FIG.

[0053] As shown in Fig. 10, since the transferability differs depending on the pitch p1, even if the same height h1 of the protrusions 322 is molded, the width of the plane of the uneven surface shape will be different as shown by E1 and E2 in Fig. 11, so it is preferable to make the uneven height large. Specifically, the height h1 is preferably 10 µm or more and 50 µm or less, and the pitch p1 is preferably 50 µm or more and 145 µm or less.

[0054] Here, as shown in FIG. 11, when the pitch p1 is set to 105 μm, a plane parallel to the opposing surface 321 is slightly generated at the apex 322b of the convex portion 322. In contrast, in this embodiment, the apex 322b is arranged in a continuous shape 452 inclined by θ with respect to the document conveying direction DF. This allows the direction of the illumination light reflected from the uneven surface portion 320 to be twisted from the main scanning direction, making it possible to make it difficult for the regular reflection light to go toward the reading unit 311. In this embodiment, the inclination of θ=45 degrees makes the reflected light inclined with respect to both the main scanning direction and the sub-scanning direction. With this shape, the illumination light emitted from the illumination unit 400 is reflected by the platen member 306 as shown in FIG. 6(c), making it possible to make it difficult for the regular reflection light L3 of the illumination light reflected by the platen member 306 to be reflected toward the CCD 408.

[0055] As described above, according to the automatic document reader 101 of this embodiment, the uneven surface portion 320 is formed on the platen members 306, 308, so that the specularly reflected light from the platen members 306, 308 is less likely to travel toward the CCD 408. This makes it possible to suppress the occurrence of luminance changes due to specularly reflected components from the platen members 306, 308, prevents erroneous detection of the leading edge of the document, and improves the accuracy of skew correction.

[0056] In the above-described embodiment, the uneven surface portion 320 has both the apex 322b and the bottom 322c in an arc shape, but the present invention is not limited to this. For example, the uneven surface portion may have a shape in which the convex portions are continuously arranged in a triangular cross section. In this case, the apex and the bottom portion both have a shape with an acute angle in cross section, and do not have a surface parallel to the opposing surface. Alternatively, the uneven surface portion may have a shape in which the convex portions are continuously arranged in a semicircular cross section. In this case, the apex is in an arc shape, and the bottom portion has a shape with an acute angle in cross section, and does not have a surface parallel to the opposing surface. [Explanation of symbols]

[0057] 10...image forming apparatus, 12...image forming section, 30...control section, 101...automatic document reader (image reading device), 306, 308...platen member (opposing member), 311, 312...reading unit, 313, 315...slide reading glass (transparent member), 320...uneven surface section, 322...convex section, 322a...inclined surface, 322b...vertex, 330...transport section, 400...illumination unit (light source), 408...CCD (reading section), D...document, DF...transport direction

Claims

1. a conveying unit that conveys the document along a conveying path; a transparent member forming a part of the transport path; a reading unit including a light source that irradiates light onto a document, and a reading unit that reads an image of the document conveyed by the conveying unit through the transparent member as reflected light of the light irradiated from the light source; an opposing member that is disposed opposite the transparent member in an opposing direction at the reading position of the reading unit and that forms the transport path together with the transparent member; the opposing member faces the transparent member, has a shape in which a plurality of convex portions are regularly and continuously arranged when viewed in the opposing direction, and has an uneven surface portion that is read by the reading portion of the reading unit; An image reading device characterized by:

2. the uneven surface portion is composed of a plurality of surfaces inclined with respect to an imaginary plane that intersects with the opposing direction and faces the transparent member; 2. The image reading device according to claim 1, wherein:

3. The plurality of protrusions are formed so as to extend linearly when viewed in the opposing direction.

2. The image reading device according to claim 1, wherein:

4. The linear shape is a straight line.

4. The image reading device according to claim 3, wherein:

5. The plurality of protrusions are arranged parallel to each other, 5. The image reading device according to claim 4, wherein:

6. In a cross section obtained by cutting the uneven surface portion with a plane along the opposing direction, each of the plurality of convex portions has an arc-shaped vertex.

2. The image reading device according to claim 1, wherein:

7. At least one of the plurality of convex portions extends linearly along a first direction, and the first direction and the main scanning direction of the reading unit form an angle of 10 degrees or more and 80 degrees or less.

7. The image reading device according to claim 6, wherein:

8. The first direction and the main scanning direction of the reading unit form an angle of 45 degrees.

8. The image reading device according to claim 7, wherein:

9. The size of each of the plurality of convex portions is determined based on the resolution of the reading unit.

2. The image reading device according to claim 1, wherein:

10. The plurality of protrusions each have a height of 10 μm or more and 50 μm or less, and a pitch of 10 μm or more and 145 μm or less.

2. The image reading device according to claim 1, wherein:

11. The reading unit reads an image of the document and has a reading range extending in a width direction intersecting a conveying direction of the document, the concave-convex surface portion is provided facing the reading range of the reading unit; 2. The image reading device according to claim 1, wherein:

12. The uneven surface portion is white.

2. The image reading device according to claim 1, wherein:

13. The image reading device further includes a control unit that corrects skew of the document based on the image of the document read by the reading unit.

2. The image reading device according to claim 1, wherein:

14. The scanner further includes a control unit that corrects skew of the document based on a shadow of the document projected onto the uneven surface portion read by the reading unit.

2. The image reading device according to claim 1, wherein:

15. The control unit corrects the skew of the document by correcting the inclination of the image of the document read by the reading unit.

14. The image reading device according to claim 13,

16. A conveying section that conveys a document along a conveying path; a transparent member forming a part of the transport path; a reading unit including a light source that irradiates light onto a document, and a reading unit that reads an image of the document conveyed by the conveying unit through the transparent member as reflected light of the light irradiated from the light source; an opposing member that is disposed opposite the transparent member in an opposing direction at the reading position of the reading unit and that forms the transport path together with the transparent member; the opposing member faces the transparent member, has a shape in which a plurality of recesses are regularly and continuously arranged when viewed in the opposing direction, and has an uneven surface portion that is read by the reading section of the reading unit; An image reading device characterized by:

17. The plurality of recesses are formed so as to extend linearly when viewed in the opposing direction.

17. The image reading device according to claim 16,

18. In a cross section of the uneven surface portion cut by a plane along the opposing direction, each of the plurality of recesses has an arc-shaped bottom.

18. The image reading device according to claim 17,

19. A conveying section that conveys a document along a conveying path; a transparent member forming a part of the transport path; a reading unit including a light source that irradiates light onto a document, and a reading unit that reads an image of the document conveyed by the conveying unit through the transparent member as reflected light of the light irradiated from the light source; an opposing member that is disposed opposite the transparent member in an opposing direction at the reading position of the reading unit and that forms the transport path together with the transparent member; the opposing member faces the transparent member, has a shape in which a plurality of convex portions and a plurality of concave portions are regularly and continuously arranged when viewed in the opposing direction, and has an uneven surface portion that is read by the reading unit of the reading unit; An image reading device characterized by:

20. The plurality of protrusions are formed so as to extend linearly when viewed in the opposing direction, The plurality of recesses are formed to extend linearly when viewed in the opposing direction.

20. The image reading device according to claim 19,

21. In a cross section obtained by cutting the uneven surface portion with a plane along the opposing direction, each of the plurality of convex portions has an arc-shaped vertex, In a cross section of the uneven surface portion cut along a plane along the opposing direction, each of the plurality of recesses has an arc-shaped bottom.

20. The image reading device according to claim 19,

22. An image reading device according to any one of claims 1 to 21 that reads an image of a document; an image forming unit that forms an image on a sheet based on the image information read by the image reading device, An image forming apparatus characterized by:

Images