JP2017108322A - Image reader and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reader capable of easily and accurately discriminating a region of an entire document in a more simplified configuration.SOLUTION: The image reader comprises: a first illumination part 52 for irradiating a document D with a light; a document background plate 70a which opposes the first illumination part 52 with the document D interposed therebetween; an image sensor 57 for receiving reflection lights from one side of the document D and a surface of the document background plate 70a; a scan drive part 53 for moving the first illumination part 52 relatively to the document D; and a read control part 58 for detecting an edge De of the document D from a shadow Ds that is generated in a region of the document background plate 70a corresponding to a peripheral edge of the document D based on information from the image sensor 57 that receives the reflection lights. In a main scan direction crossing a sub scan direction that is a direction of movement of the first illumination part 52, the first illumination part 52 has such distribution that an intensity of a main distribution light in at least one peripheral edge of the document is stronger in a document outside direction component than in a document inside direction component.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an image reading apparatus and an image forming apparatus represented by a copying machine provided with the image reading apparatus.

  Some image forming apparatuses such as copying machines and facsimiles include an image reading apparatus for reading an image drawn on the surface of a document. In general, an image reading apparatus irradiates light toward a document placed on the upper surface of a glass serving as a document table or a document passing over the glass, and receives the reflected light to read an image of the document. . Japanese Patent Application Laid-Open No. 2004-133867 discloses a related art relating to such an image reading apparatus.

  The document size detection device described in Patent Document 1 includes an exposure lamp that irradiates light toward the document, and a platen cover that faces the exposure lamp with the document interposed therebetween. The document size detecting device detects the edge of the document from the shadow generated in the area corresponding to the peripheral edge of the document on the platen cover. Thereby, the document size detecting device can easily detect the size of the document.

JP-A-6-27547

  However, in order to improve the detection accuracy of the edge of the document, it has been a problem to generate a clear shadow more effectively than the document size detection apparatus described in Patent Document 1. In order to appropriately obtain document information, it is desirable to accurately determine the entire area of the document from an image read from the document.

  SUMMARY An advantage of some aspects of the invention is that it provides an image reading apparatus and an image forming apparatus capable of easily and accurately discriminating an entire area of a document with a simpler configuration. To do.

  In order to solve the above problems, an image reading apparatus according to the present invention includes an illumination unit that emits light toward a document, a document background unit that faces the illumination unit across the document, and a document that is irradiated from the illumination unit. An image sensor that receives reflected light reflected from the surface and the surface of the document background portion, a drive unit for moving one of the document and the illumination unit relative to the other, and the light receiving the reflected light A control unit for detecting an edge of the document from a shadow generated in an area corresponding to a peripheral edge of the document in the document background based on information from the image sensor, and the illumination unit is configured to detect the document by the drive unit or With respect to the main scanning direction that intersects the sub-scanning direction that is the moving direction of the illumination unit, the intensity of the main light distribution at at least one peripheral edge of the document has a distribution in which the component outside the document is stronger than the component inside the document. And butterflies.

  According to this configuration, the illumination unit emits light whose main light distribution intensity is higher in the document outer direction component than in the document inner direction component on at least one peripheral portion of the document. A shadow representing the edge of the document is likely to occur in the corresponding area. Further, for example, when the document background portion is white, a shadow having a relatively large density difference from the document background portion is produced.

  In the image reading apparatus having the above-described configuration, the illumination unit is disposed over the entire region in the main scanning direction between the light source and the light source and the document, receives the light from the light source, and guides the light toward the document. And the light source is arranged at a position corresponding to the center of the light guide in the main scanning direction.

  In the image reading apparatus having the above-described configuration, the light guide has a diffusion unit for diffusing light of the light source in a region corresponding to an installation position of the light source.

  Further, the image reading apparatus having the above-described configuration includes a first reading unit and a second reading unit for individually reading front and back images of the document, and the illumination unit emits light toward the document by the first reading unit. The first illumination unit and a second illumination unit that emits light toward the document by the second reading unit, and the first illumination unit has an intensity of main light distribution with respect to one end side in the main scanning direction. Has a distribution in which the document outer direction component is stronger than the document inner direction component, and the second illumination unit has a main light distribution intensity in the document outer direction relative to the document inner direction component on the other end side in the main scanning direction. The component has a strong distribution, and the control unit includes one edge of the front and back sides of the document detected using the first reading unit, and the other edge of the front and back sides of the document detected using the second reading unit. Is used to discriminate the edges of the entire document.

  In the image reading apparatus having the above configuration, the light irradiation direction by the first illumination unit and the light irradiation direction by the second illumination unit are different with respect to the main scanning direction.

  In the image reading apparatus having the above configuration, the first illumination unit has a first light source, the second illumination unit has a second light source, and the first light source is arranged on one end side in the main scanning direction. The second light source is arranged on the other end side in the main scanning direction.

  Further, in the image reading apparatus having the above-described configuration, the control unit individually executes document image reading processing and edge detection processing for each of the first reading unit and the second reading unit, and one image to be executed later. An edge detection process related to the other image reading process previously executed during the execution of the reading process is executed.

  In the image reading apparatus configured as described above, the control unit detects the inclination of the detected edge of the document with respect to the main scanning direction and the sub-scanning direction, and if there is a difference between the inclinations of both the front and back edges of the document A correction process is executed.

  In the image reading apparatus having the above-described configuration, the first illumination unit includes a first reading unit and a second reading unit for individually reading front and back images of the document, and the illumination unit is disposed in the first reading unit. And a second illuminating unit arranged in the second reading unit, wherein the control unit detects the edge of the document extending in the main scanning direction and the edge of the document extending in the sub-scanning direction, and performs the first reading The edge of the whole document is discriminated using the edge extending in the main scanning direction and the sub-scanning direction of one of the front and back sides of the document detected using the scanning unit, and the other of the front and back sides of the document detected using the second reading unit The edge of the entire document is discriminated using the edges extending in the main scanning direction and the sub-scanning direction.

  According to the present invention, the image reading apparatus having the above-described configuration is provided in an image forming apparatus.

  According to the configuration of the present invention, it is possible to generate a clear shadow of the document edge effectively in a region corresponding to the document peripheral portion of the document background portion with a simpler configuration. Therefore, it is possible to easily determine the entire area of the original accurately, and information on the original can be obtained appropriately.

1 is a partial vertical sectional front view of an image forming apparatus according to a first embodiment of the present invention. 1 is a vertical sectional front view of an image reading apparatus of an image forming apparatus according to a first embodiment of the present invention. It is a side view which shows the 1st illumination part periphery of the image reader of 1st Embodiment of this invention. FIG. 5 is an explanatory diagram illustrating document area determination processing by the image reading apparatus according to the first embodiment of the present invention. It is a partial top view of the optical scanning unit of the image reading apparatus of 2nd Embodiment of this invention. It is explanatory drawing shown about the area | region discrimination | determination process of the original document by the image reading apparatus of 2nd Embodiment of this invention. It is a side view of the 1st reading part of the image reading apparatus of 3rd Embodiment of this invention. It is a side view of the 2nd reading part of the image reading apparatus of 3rd Embodiment of this invention. It is explanatory drawing shown about the area | region discrimination | determination process of the original by the image reading apparatus of 3rd Embodiment of this invention. 14 is a flowchart illustrating an example of document area determination processing by the image reading apparatus according to the fourth exemplary embodiment of the present invention. It is explanatory drawing shown about the area | region discrimination | determination process of the original by the image reading apparatus of 5th Embodiment of this invention. 18 is a flowchart illustrating an example of document area determination processing by the image reading apparatus according to the sixth embodiment of the present invention. It is explanatory drawing shown about the area | region discrimination | determination process of the original document by the image reading apparatus of 6th Embodiment of this invention. It is explanatory drawing shown about the area | region discrimination | determination process of the original by the image reading apparatus of 7th Embodiment of this invention. It is explanatory drawing shown about the area | region discrimination | determination process of the original by the image reading apparatus of 8th Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the following contents.

<First Embodiment>
First, the image output operation of the image forming apparatus according to the embodiment of the present invention will be described while explaining the outline of the structure with reference to FIG. FIG. 1 is an example of a partial vertical sectional front view of an image forming apparatus. In the figure, a two-dot chain line with an arrow indicates a sheet conveyance path and a conveyance direction.

  As shown in FIG. 1, the image forming apparatus 1 is a so-called tandem color copier, and includes an image reading device 40 for reading an image of a document, and a printing unit 3 for printing the read image on a transfer material such as paper. And an operation unit 4 for inputting printing conditions and displaying an operation status, and a main control unit 5.

  The image reading device 40 includes an optical scanning unit 50 and a document conveying unit 70 and is provided on the upper portion of the image forming apparatus 1. The image reading device 40 reads an image of one original placed on the upper surface of the optical scanning unit 50, and uses the optical scanning unit 50 and the original conveying unit 70 to output images of a plurality of originals one by one. Can be read automatically. The original image is separated into three colors, red (R), green (G), and blue (B), and is converted into an electrical signal by an image sensor described later. Thereby, the image reading apparatus 40 obtains image data for each color of red (R), green (G), and blue (B). Details of the configuration of the image reading device 40 will be described later.

  The image data for each color obtained from the original by the image reading device 40 is subjected to various processes in the main control unit 5, and the reproduction colors of yellow (Y), magenta (M), cyan (C), and black (K) are reproduced. It is converted into image data and stored in a memory (not shown) inside the main controller 5. The image data for each reproduction color stored in the memory is subjected to a process for correcting misregistration, and then is scanned for each scanning line in synchronism with the conveyance of the sheet in order to perform optical scanning on the photosensitive drum 21 which is an image carrier. Is read out.

  The printing unit 3 forms an image by an electrophotographic method, and transfers the image to a sheet or the like. The printing unit 3 includes an intermediate transfer belt 11 in which an intermediate transfer member is formed as an endless belt. The intermediate transfer belt 11 is wound around a driving roller 12, a tension roller 13 and a driven roller 14. A tension is applied to the intermediate transfer belt 11 by urging the tension roller 13 upward in FIG. 1 by a spring (not shown). The intermediate transfer belt 11 is rotated by the driving roller 12 counterclockwise in FIG.

  The driving roller 12 is pressed and brought into contact with the secondary transfer roller 15 facing the intermediate transfer belt 11. At the position of the driven roller 14, an intermediate transfer cleaning unit 16 provided so as to face the driven roller 14 with the intermediate transfer belt 11 interposed therebetween contacts the outer peripheral surface of the intermediate transfer belt 11. The intermediate transfer cleaning unit 16 scrapes and cleans toner remaining on the outer peripheral surface of the intermediate transfer belt 11 after the secondary transfer.

  Below the intermediate transfer belt 11, image forming units 20Y, 20M, 20C, and 20K corresponding to reproduction colors of yellow (Y), magenta (M), cyan (C), and black (K) are provided. In this description, the description of the identification symbols “Y”, “M”, “C”, and “K” is omitted unless it is particularly limited, and is generically referred to as “image forming unit 20”, for example. Sometimes. The four image forming units 20 are arranged in a line along the rotation direction of the intermediate transfer belt 11 from the upstream side to the downstream side in the rotation direction. The four image forming units 20 have the same configuration, and include a charging unit, an exposure unit, a developing unit, a cleaning unit, and a primary transfer unit around the photosensitive drum 21 that rotates clockwise in FIG. .

  Above the intermediate transfer belt 11, toner bottles 31 and toner hoppers 32 corresponding to the four image forming units 20 of the respective reproduction colors are provided. The developing unit and the toner hopper 32 are provided with a toner remaining amount detection unit (not shown) that detects the amount of toner inside each. Further, a toner replenishing device (not shown) is provided between the developing unit and the toner hopper 32 and between the toner hopper 32 and the toner bottle 31. When a decrease in the toner amount inside the developing unit is detected by the remaining amount detecting unit, the replenishing device is driven to replenish toner from the toner hopper 32 to the developing unit. Further, when the remaining amount detection unit detects a decrease in the toner amount inside the toner hopper 32, the replenishing device is driven to replenish the toner from the toner bottle 31 to the toner hopper 32. The toner bottle 31 is detachably attached to the apparatus main body, and can be replaced with a new one as appropriate.

  A sheet feeding device 91 is provided below the four image forming units 20, and the sheet P is accommodated therein. The paper P accommodated in the paper feeding device 91 is sent out to the paper transport path Q in order from the uppermost paper by the supply unit 92. It is also possible to supply the paper to the paper transport path Q using the manual paper feed unit 93. The paper P sent out from the paper supply device 91 or the manual paper supply unit 93 to the paper transport path Q reaches the position of the registration roller pair 94. Then, the registration roller pair 94 corrects the skew feeding of the paper P (skewing correction) and synchronizes with the rotation of the intermediate transfer belt 11 so as to contact the intermediate transfer belt 11 and the secondary transfer roller 15 (secondary transfer). The paper P is sent out toward the nip portion.

  In the image forming unit 20, an electrostatic latent image is formed on the surface of the photosensitive drum 21 by the charging unit and the exposure unit, and the electrostatic latent image is visualized as a toner image by the developing unit. The toner image formed on the surface of the photosensitive drum 21 is primarily transferred to the outer peripheral surface of the intermediate transfer belt 11 at a position where the photosensitive drum 21 faces the primary transfer roller with the intermediate transfer belt 11 interposed therebetween. The toner images of the image forming units 20 are sequentially transferred to the intermediate transfer belt 11 at a predetermined timing along with the rotation of the intermediate transfer belt 11, so that yellow, magenta, cyan, black on the outer peripheral surface of the intermediate transfer belt 11. A color toner image is formed by superimposing the four color toner images.

  The color toner image primarily transferred to the outer peripheral surface of the intermediate transfer belt 11 is formed on the paper P sent in synchronization by the registration roller pair 94 with the intermediate transfer belt 11 and the secondary transfer roller 15 in contact with each other. The secondary transfer nip is transferred.

  A fixing portion 95 is provided above the secondary transfer nip portion. The paper P on which the unfixed toner image has been transferred at the secondary transfer nip is sent to the fixing unit 95 and is sandwiched between the heating roller and the pressure roller, and the toner image is heated and pressurized to be fused on the paper P. Is done. The paper P that has passed through the fixing unit 95 is discharged to a paper discharge unit 96 provided above the intermediate transfer belt 11.

  The operation unit 4 is provided on the upper front side of the image forming apparatus 1. The operation unit 4 inputs settings such as printing conditions such as the type and size of paper P used for printing by the user, enlargement / reduction, and presence / absence of double-sided printing, and settings such as a fax number and a sender name in facsimile transmission. Accept. The operation unit 4 also serves as a notifying unit for notifying the user of, for example, displaying the state of the device, precautions, and an error message on the display unit 4W.

  Further, the image forming apparatus 1 is provided with a main control unit 5 composed of a CPU (not shown), an image processing unit, and other electronic parts (not shown) for overall operation control. The main control unit 5 uses a central processing unit (CPU) and an image processing unit to control components such as the image reading device 40 and the printing unit 3 based on programs and data stored in a memory and input. Image forming operation and printing operation are realized.

  Next, the configuration and operation of the image reading device 40 of the image forming apparatus 1 will be described with reference to FIG. FIG. 2 is a vertical sectional front view of the image reading device 40. Note that the vertical direction, the horizontal direction, and the paper depth direction in FIG. 2 indicate the vertical direction, the horizontal direction, and the front-rear direction of the image forming apparatus 1 and the image reading apparatus 40, respectively. Also, the arrow X shown in FIG. 2 indicates the main scanning direction, the arrow Y indicates the sub-scanning direction, and the same applies to the following drawings.

  As shown in FIG. 2, the image reading apparatus 40 includes an optical scanning unit 50 provided on the upper portion of the image forming apparatus main body, and a document conveying unit 70 placed on the upper surface of the apparatus main body.

  The optical scanning unit 50 includes a contact glass 51, a first illumination unit 52, a scanning drive unit 53, a wire 54, a winding drum 55, a lens 56, an image sensor 57, and a reading control unit 58.

  The contact glass 51 is provided on the upper surface of the optical scanning unit 50. The contact glass 51 is composed of a relatively thin flat plate-like transparent glass. The optical scanning unit 50 is scanned in the front-rear direction (main scanning direction, arrow X direction in FIG. 2) and left and right so that the entire surface of the document D can be optically scanned at once. It forms a rectangular shape extending widely in the direction (sub-scanning direction, arrow Y direction in FIG. 2). When the images of the document D are individually read one by one, the document D is placed on the upper surface of the contact glass 51 with the reading surface facing downward.

  The first illumination unit 52 is disposed immediately below the contact glass 51. The first illumination unit 52 irradiates light toward the reading surface of the document D, that is, upward. Details of the configuration of the first illumination unit 52 will be described later.

  The scanning drive unit 53 is provided below the contact glass 51 and includes a first moving body 53A and a second moving body 53B.

  The first moving body 53A of the scan driving unit 53 supports the first illumination unit 52 and includes a first mirror 59a. The first mirror 59a receives the reflected light of the first illumination unit 52 reflected by the reading surface of the document D, and is further set to have a predetermined inclination to change the direction substantially horizontally at an angle of 90 degrees. Placed in.

  The second moving body 53B of the scan driving unit 53 includes a second mirror 59b and a third mirror 59c. The second mirror 59b receives light reflected by the first mirror 59a of the first moving body 53A, and is further set to have a predetermined inclination so as to be turned substantially vertically downward at an angle of 90 degrees. Arranged at approximately the same height. The third mirror 59c is disposed substantially directly below the second mirror 59b in order to receive the light reflected by the second mirror 59b and to change the direction substantially horizontally at an angle of 90 degrees.

  In addition, each mirror provided in the first moving body 53A and the second moving body 53B extends in substantially the same length as the contact glass 51 in the main scanning direction (front-rear direction of the optical scanning unit 50) like the first illumination unit 52. It is composed of an elongated shape.

  The wire 54 is connected to the first moving body 53A and the second moving body 53B and is wound around the winding drum 55. When the winding drum 55 is rotated by a motor (not shown), the first moving body 53A and the second moving body 53B reciprocate in the sub-scanning direction (the left-right direction of the optical scanning unit 50) in parallel with the upper surface of the contact glass 51. . As a result, the reading line (irradiation position by the first illumination unit 52) can be moved in the sub-scanning direction, and an image on the entire reading surface of the document D placed on the upper surface of the contact glass 51 can be read. it can.

  The lens 56 and the image sensor 57 are provided below the optical scanning unit 50. The reflected light from the reading surface of the document D, which is reflected by the third mirror 59c of the second moving body 53B, enters the lens 56 and is condensed. The lens 56 forms an image of the reflected light on the surface of the image sensor 57 provided on the downstream side of the optical path. As a result, the image reading apparatus 40 can read the image of the reading surface of the document D on the contact glass 51 as image data using the image sensor 57.

  Note that the image sensor 57 includes a plurality of CCDs (Charge Coupled Devices), which are solid-state imaging devices, in a straight line in the main scanning direction which is the front-rear direction of the image reading device 40, that is, in the depth direction of the drawing (arrow X direction) in FIG. It is arranged in a line. The image sensor 57 photoelectrically converts incident light into an electrical signal and outputs it as image information. Then, the reading controller 58 scans the reading surface of the document D in the main scanning direction by the image sensor 57, drives the scanning driving unit 53, and scans the first illumination unit 52 in the sub-scanning direction. By executing the processing, it is possible to obtain an image of the document D as image data.

  The reading control unit 58 includes an IC such as a processing circuit and a memory, and other electronic components, and is a control unit that receives an instruction from the main control unit 5 and controls the operation of the optical scanning unit 50. The reading control unit 58 drives and controls the scanning driving unit 53 based on a control command from the main control unit 5 and executes image processing on an output signal from the image sensor 57 to output image data. In this way, the reading control unit 58 realizes an image reading operation.

  The document transport unit 70 is provided above the contact glass 51 so as to face the contact glass 51. The document transport unit 70 is a unit having a rectangular parallelepiped shape that covers the entire surface of the contact glass 51. The document transport unit 70 is swingably attached to the optical scanning unit 50 around two support shafts (not shown) provided on the back side of the optical scanning unit 50 and extending substantially horizontally in the left-right direction. As a result, the document conveying unit 70 swings up and down with its front side portion as a free end, and can be opened and closed with respect to the contact glass 51. FIG. 2 shows a state in which the contact glass 51 is closed by the document conveying unit 70.

  A document background plate 70a, which is a document background portion, is provided on the outer bottom surface of the document transport unit 70 and facing the contact glass 51 when closed. The document background plate 70 a is white and has a position and size that covers the entire area of the contact glass 51. When the portion of the contact glass 51 is closed by the document conveying unit 70, the document background plate 70a is in close contact with the contact glass 51 so as to uniformly press the entire surface thereof and holds the document D so as not to move.

  The document transport unit 70 includes a paper feed tray 71, a paper discharge tray 72, and a transport drive unit 73 in addition to the document background plate 70a.

  The paper feed tray 71 is a document placement portion disposed on the upper portion of the document transport unit 70. Documents can be stacked and stacked on the sheet feed tray 71 from above. The paper feed tray 71 has an inclination that descends from upstream to downstream in the document conveyance direction (left-right direction of the document conveyance unit 70), that is, from right to left in FIG.

  The paper feed tray 71 includes two alignment plates 71a provided on the upper surface thereof and extending in the document transport direction and upward. Each of the two alignment plates 71a is movable in a direction intersecting with the document conveying direction, and is in contact with both ends of the document in the width direction, which is a direction intersecting with the document conveying direction. Is held at a proper paper feed position.

  A document push-up unit 71 b is provided on the downstream side of the sheet feed tray 71 in the document transport direction. The push-up portion 71b has a shape along the document placement surface of the paper feed tray 71, is provided at the upstream end of the push-up portion 71b, is centered on a support shaft (not shown) extending in the document width direction, and has a downstream end as a free end. It is provided so as to be rotatable within. The push-up unit 71b is rotated around a support shaft by a motor (not shown) or the like at the time of document supply, so that the downstream end of the document stacked on the sheet feed tray 71 contacts a supply roller 75 disposed above the document feed tray 71. So that it is biased upward.

  The conveyance driving unit 73 includes a document supply port 74 and a supply roller 75 at the downstream end of the sheet feeding tray 71 in the document conveyance direction. The supply roller 75 separates the originals stacked on the paper feed tray 71 one by one from the uppermost original, and supplies the originals to the inside of the conveyance driving unit 73 for conveyance. A document conveyance path 76 extends toward the inside of the conveyance drive unit 73 on the downstream side of the document supply port 74.

  A registration roller pair 77 is provided in the document conveyance path 76. The registration roller pair 77 corrects skew feeding of the original (skew correction), and then sends the original further downstream in the conveyance direction. Further, conveyance rollers 78 are provided at various locations on the document conveyance path 76.

  The document conveyance path 76 downstream of the registration roller pair 77 in the document conveyance direction reaches the bottom surface of the document conveyance unit 70, and a first reading unit 79 is provided at this position. The document fed into the first reading unit 79 is further moved down on the document conveyance path 76, that is, while moving the position of the first reading unit 79 from the left to the right in FIG. The image data of the first surface, which is the lower surface, is read by the provided optical scanning unit 50. When the first reading unit 79 reads an image of a document, the first moving body 53A of the scan driving unit 53 that supports the first illumination unit 52 moves below the first reading unit 79 and uses the image sensor 57. Then, the image data of the lower side (first side) of the document is read.

  A second reading unit 80 is provided downstream of the first reading unit 79 in the document conveying direction of the document conveying path 76. The second reading unit 80 includes a contact glass 81, a second illumination unit 82, an image sensor 83, and a document background plate 80a. When it is necessary to read the image data on both sides of the document, the document sent to the second reading unit 80 is further on the document conveyance path 76, that is, the position of the second reading unit 80 in FIG. During the movement to the right, the image data of the second surface, which is the upper surface, is read by the second reading unit 80 provided above the right.

  A document discharge port 84 is provided at the downstream end of the document transport path 76. The document whose image data has been read is discharged from the document discharge port 84 to the discharge tray 72. The paper discharge tray 72 is provided immediately below the paper feed tray 71, and these trays are configured in two upper and lower stages. The document discharged to the discharge tray 72 can be taken out from the front side of the document transport unit 70.

  The paper feed tray 71 and the paper discharge tray 72 are opposite to each other in the document conveyance direction, that is, in FIG. 2, the paper feed tray 71 sends out the original toward the left, and the discharge tray 72 removes the original from the left. Configured to receive. Thereby, the document conveyance path 76 extending from the document supply port 74 to the document discharge port 84 is provided in a configuration in which a U-shaped curved configuration is inclined in the horizontal direction as shown in FIG. A conveyance control unit (not shown) controls the conveyance of the document.

  The conveyance control unit includes an IC such as a processing circuit and a memory, and other electronic components, and receives an instruction from the main control unit 5 to control the operation of the document conveyance unit 70. The transport control unit drives the push-up unit 71b and the supply roller 75 to separate the documents placed on the paper feed tray 71 one by one based on a control command from the main control unit 5 and supplies them to the transport drive unit 73. To do. Further, the conveyance control unit drives the registration roller pair 77 and the conveyance roller 78 to read the image data by the first reading unit 79 and the second reading unit 80, and then discharges the image data to the paper discharge tray 72. In this way, the conveyance control unit realizes a document conveyance operation.

  Next, a detailed configuration around the first illumination unit 52 of the image reading apparatus 40 and a document area determination process will be described with reference to FIGS. 3 and 4. FIG. 3 is a side view showing the vicinity of the first illumination unit 52. FIG. 4 is an explanatory diagram showing document area determination processing by the image reading device 40. 3 shows the periphery of the first illumination unit 52 along the sub-scanning direction of the image reading device 40 (the horizontal direction of the image reading device 40, the arrow Y direction in FIG. 3). 3 schematically shows the intensity distribution of the illumination light in the main scanning direction (the front-rear direction of the image reading device 40, the arrow X direction in FIG. 3).

  As shown in FIG. 3, the first illumination unit 52 of the optical scanning unit 50 includes an LED (light emitting diode) 52a and a light guide 52b, which are light sources. Both the LED 52 a and the light guide 52 b are disposed below the contact glass 51.

  The LED 52a is arranged at the center of the length of the contact glass 51 in the main scanning direction (arrow X direction in FIG. 3). The LED 52a emits light toward the reading surface of the document D, that is, upward.

  The light guide 52b is disposed above the LED 52a and between the contact glass 51 and below the lower surface of the contact glass 51. The light guide 52b has an elongated cylindrical shape or a quadrangular prism shape extending substantially the same length as the contact glass 51 over the entire region in the main scanning direction. The LED 52a is disposed at a position corresponding to the center of the light guide 52b in the main scanning direction. A concave portion 52c, a prism portion 52d, and a diffusion portion 52e are formed in the light guide 52b.

  The recess 52c is disposed below the center of the length of the light guide 52b in the main scanning direction, and faces the LED 52a. When viewed from the sub-scanning direction (the arrow Y direction (the depth direction on the paper) in FIG. 3), the concave portion 52c is recessed upward so as to be separated from the LED 52a, and has a wedge shape (inverted V shape).

  The prism portion 52d is formed over the entire area of the lower surface facing the LED 52a of the light guide 52b. The prism portion 52d is configured to totally reflect the light of the LED 52a that has entered the light guide 52b upward.

  The diffusion part 52e is substantially in the center of the length of the upper surface of the light guide 52b in the main scanning direction, is opposed to the lower surface of the contact glass 51, and is formed in a region corresponding to the installation positions of the LEDs 52a and the recesses 52c. The diffusion part 52e is configured to diffuse the light of the LED 52a that enters the light guide 52b and is emitted upward from the diffusion part 52e over the entire region in the main scanning direction.

  The light guide 52b having such a configuration receives the light of the LED 52a at the position of the concave portion 52c on the lower surface, emits the light from the upper surface toward the document D, and irradiates the entire document D.

  Then, as shown in the upper part of FIG. 3, the first illumination unit 52 increases in intensity of irradiation light with respect to the document D as it goes from the central portion (dotted line) to the peripheral portion in the main scanning direction. Have a distribution. Further, around the edge De of the document D, light whose main light distribution intensity is stronger in the document outer direction component than the document inner direction component is irradiated.

  The image reading device 40 realizes an image reading operation of reading an image of one document D placed on the upper surface of the contact glass 51 using the first illumination unit 52 having the above configuration. At this time, the reading control unit 58 is based on the information from the image sensor 57 and the edge extending in the sub-scanning direction of the document D from the shadow Ds extending in the sub-scanning direction generated in the region corresponding to the peripheral edge of the document D on the document background plate 70a De is detected (see FIG. 4).

  Since the first illumination unit 52 irradiates light around the edge De of the document D, the intensity of the main light distribution is stronger in the document outer direction component than in the document inner direction component, so that the document background plate as shown at the left end of FIG. The shadow Ds of the edge De of the document D is likely to occur in an area corresponding to the peripheral edge of the document D of 70a. The reading control unit 58 detects the edge De from the shadow Ds on the peripheral edge of the document D, and complements the two edges De in the sub-scanning direction to accurately determine the area Da of the entire document D.

  In the above embodiment, the first illumination unit 52 has the detailed configuration shown in FIG. 3, but the configuration of FIG. 3 may be applied to the second illumination unit 82 of the second reading unit 80. . The second reading unit 80 includes a document background plate 80a, a contact glass 81, and a second illumination unit 82 including an LED that is a light source and a light guide. Both the LED and the light guide are arranged above the contact glass 81. Then, the conveyance driving unit 73 moves the document D relative to the second illumination unit 82. The reading control unit 58 is generated in an area corresponding to the peripheral portion of the document D on the document background plate 80a based on the information from the image sensor 83 that has received the reflected light reflected on one surface of the document D and the surface of the document background plate 80a. The edge De of the document D is detected from the shadow Ds.

Second Embodiment
Next, an image reading apparatus according to a second embodiment of the present invention will be described with reference to FIGS. FIG. 5 is a partial top view of the optical scanning unit of the image reading apparatus. FIG. 6 is an explanatory diagram showing document area determination processing by the image reading apparatus. Since the basic configuration of this embodiment is the same as that of the first embodiment described above, the same reference numerals or the same names as those in the first embodiment are assigned to the same constituent elements as those of the first embodiment, and the description thereof is omitted. May be omitted.

  In the image reading apparatus 40 of the second embodiment, as shown in FIG. 5, the optical scanning unit 50 includes a document width direction scale 60 and a document conveyance direction scale 61 on the upper surface.

  The document width direction scale 60 is disposed adjacent to the left end portion of the contact glass 51 and has a plate shape extending along the main scanning direction (the arrow X direction in FIG. 5). The document transport direction scale 61 is disposed adjacent to the end portion on the back side of the contact glass 51 and has a plate shape extending along the sub-scanning direction (the arrow Y direction in FIG. 5). The document width direction scale 60 and the document conveyance direction scale 61 are arranged adjacent to each other on the left rear side of the contact glass 51 so as to be orthogonal to each other.

  The document D is based on a reference point A that is an intersection of the document width direction scale 60 and the document conveyance direction scale 61 on the upper surface of the contact glass 51, and the edge thereof contacts the document width direction scale 60 and the document conveyance direction scale 61. It is placed according to.

  Based on information from the image sensor 57, the reading control unit 58 detects an edge De extending in the sub-scanning direction of the document D from a shadow Ds generated in a region corresponding to the peripheral portion of the document D on the document background plate 70a. (See FIG. 6). Here, no shadow is generated in a region corresponding to an edge extending in the sub-scanning direction of the document D adjacent to the document transport direction scale 61 in FIG. In this case, the reading control unit 58 detects that the edge De extending in the sub-scanning direction of the document D on the document transport direction scale 61 side coincides with the end of the document transport direction scale 61 adjacent to the document D. Then, the reading control unit 58 accurately discriminates the area Da of the entire document D by complementing the two edges De in the sub-scanning direction.

<Third Embodiment>
Next, an image reading apparatus according to a third embodiment of the present invention will be described with reference to FIGS. 7 to 9 in addition to FIG. 7 and 8 are side views of the first reading unit and the second reading unit of the image reading apparatus. FIG. 9 is an explanatory diagram showing document area determination processing by the image reading apparatus. 7 and 8 are views of the first reading unit and the second reading unit along the sub-scanning direction of the image reading device (the direction indicated by the arrow X in FIG. 2, the left-right direction of the image reading device). . In addition, since the basic configuration of this embodiment is the same as that of the first embodiment described above, the same reference numerals or the same names as those in the first embodiment are assigned to the same components as those of the first embodiment, and the description thereof is omitted. May be omitted.

  The image reading apparatus 40 according to the third embodiment performs an image reading operation that automatically reads images on both the front and back sides of the document D transported inside the document transport unit 70 by one transport. Therefore, the image reading apparatus 40 shown in FIG. 2 moves the first illumination unit 52 below the first reading unit 79 of the document conveying unit 70. Thus, the document background plate 79a provided in the first reading unit 79 is used for image reading of the document. In the image reading device 40, the first reading unit 79 emits light toward the first surface of the document D, and the second reading unit 80 directs light toward the second surface of the document D. Using the second illuminating unit 82 that irradiates, images on both the front and back sides of the document D are automatically read in one transport.

  As shown in FIG. 7, the image reading device 40 includes an LED 52 a and a light guide 52 b in which the first illumination unit 52 of the optical scanning unit 50 is a light source. Both the LED 52 a and the light guide 52 b are disposed below the contact glass 51.

  The LED 52a is disposed outside one end (for example, the back side) of the light guide 52b having an elongated cylindrical shape or a quadrangular prism shape extending in the main scanning direction (the arrow X direction in FIG. 7). The LED 52a has its optical axis substantially parallel to the main scanning direction, and irradiates light toward the side end face of the light guide 52b.

  The light guide 52b is disposed, for example, in front of the LED 52a and below the lower surface of the contact glass 51. The prism portion 52d is formed over the entire area of the lower surface of the light guide 52b.

  Since the LED 52a is disposed on the rear surface side of the light guide 52b, for example, the light emitted from the upper surface of the light guide 52b toward the first surface (lower surface) of the document D has a main directivity direction shown in FIG. The image reading device 40 faces forward as indicated by the broken arrow. In other words, the first illumination unit 52 has a distribution in which the intensity of the main light distribution is stronger in the document outer direction component than in the document inner direction component on one end (front) side in the main scanning direction. Therefore, the shadow Ds of the edge of the document D is likely to occur in a region corresponding to the peripheral portion of the document D on the document background plate 79a on the opposite side of the LED 52a, that is, on the front side (see FIG. 7).

  In the image reading apparatus 40, as shown in FIG. 8, the second reading unit 80 of the document conveying unit 70 includes a document background plate 80a, a contact glass 81, an LED 82a that is a light source, and a light guide 82b. And an illumination unit 82. Both the LED 82 a and the light guide 82 b are disposed above the contact glass 81.

  The LED 82a is disposed on the outer side of one end (for example, the front side) of the light guide 82b having an elongated cylindrical shape or a quadrangular prism shape extending in the main scanning direction (the arrow X direction in FIG. 8). The LED 82a has its optical axis substantially parallel to the main scanning direction, and irradiates light toward the side end face of the light guide 82b.

  For example, the light guide 82b is disposed behind the LED 82a and above the upper surface of the contact glass 81. A prism portion 83d is formed over the entire area of the upper surface of the light guide 82b.

  Since the LED 82a is arranged on the front side of the light guide 52b, for example, the main directing direction of light emitted from the lower surface of the light guide 82b toward the second surface (upper surface) of the document D is shown in FIG. The image reading device 40 faces backward as indicated by the broken arrow. That is, the second illumination unit 82 has a distribution in which the intensity of the main light distribution is stronger in the document outer direction component than in the document inner direction component on one end (back surface) side in the main scanning direction. Therefore, the shadow Ds of the edge of the document D is likely to occur in a region corresponding to the peripheral portion of the document D on the document background plate 80a on the opposite side of the LED 82a, that is, on the back side (see FIG. 8).

  As shown in FIG. 9, the reading control unit 58 relates to the first surface of the document D from one shadow Ds generated in the region corresponding to the peripheral edge of the document D on the document background plate 79a and extending in the sub-scanning direction. One edge De extending in the sub-scanning direction is detected. Further, the reading control unit 58 in the sub-scanning direction of the document D from the one shadow Ds extending in the sub-scanning direction generated in the region corresponding to the peripheral portion of the document D on the document background plate 80a with respect to the second surface of the document D. One extending edge De is detected. Then, the reading control unit 58 derives two edges De for the entire document D by superimposing the image data on the first surface of the document D and the image data on the second surface of the document D. Then, the reading control unit 58 accurately discriminates the area Da of the entire document D by complementing the two edges De in the sub-scanning direction.

<Fourth embodiment>
Next, an image reading apparatus according to a fourth embodiment of the present invention will be described with reference to FIG. FIG. 10 is a flowchart illustrating an example of document area determination processing by the image reading apparatus. Since the basic configuration of this embodiment is the same as that of the first and third embodiments described above, the same reference numerals or the same names as those in the previous embodiment are assigned to the components common to those embodiments. The description may be omitted.

  When the area determination process for the document D is started by the image reading device 40 of the fourth embodiment (start in FIG. 10), the image on the first surface of the document D is read in step # 101. At this time, the reading control unit 58 reads the image on the first surface by irradiating the first surface of the document D with light using the first illumination unit 52 in the first reading unit 79.

  In step # 102, the detection of the edge De on the first surface of the document D and the reading of the image on the second surface of the document D are executed in parallel processing. At this time, the reading control unit 58, on the other hand, relates to the first surface of the document D from one shadow Ds extending in the sub-scanning direction generated in the region corresponding to the peripheral portion of the document D on the document background plate 79a. One edge De extending in the sub-scanning direction is detected. On the other hand, with respect to the second surface of the document D, the reading control unit 58 irradiates light toward the second surface of the document D by using the second illumination unit 82 in the second reading unit 80. Read the image.

  In step # 103, the edge De of the second surface of the document D is detected. At this time, the reading control unit 58 makes one edge De extending in the sub-scanning direction of the document D from one shadow Ds extending in the sub-scanning direction generated in an area corresponding to the peripheral edge of the document D on the document background plate 80a. To detect.

  In step # 104, the area Da of the entire document D is determined by complementing the two edges De in the sub-scanning direction. Then, the area determination process for the document D is terminated (END in FIG. 10).

  In this way, the reading control unit 58 of the image reading apparatus 40 individually executes the image reading process and the edge detection process of the document D relating to each of the first reading unit 79 and the second reading unit 80, and executes them later. The edge detection process related to the image reading process on the first surface, which is executed first during the image reading process on the second surface, is executed.

<Fifth Embodiment>
Next, an image reading apparatus according to a fifth embodiment of the present invention will be described with reference to FIG. FIG. 11 is an explanatory diagram showing document area determination processing by the image reading apparatus. Since the basic configuration of this embodiment is the same as that of the first and third embodiments described above, the same reference numerals or the same names as those in the previous embodiment are assigned to the components common to those embodiments. The description may be omitted.

  As shown in FIG. 11, the image reading apparatus 40 of the fifth embodiment is configured so that the first reading unit 79 uses the first surface of the document D even when the document D is inclined with respect to the main scanning direction and the sub-scanning direction. The first illumination unit 52 that emits light toward the second side and the second illumination unit 82 that emits light toward the second surface of the document D by the second reading unit 80, and the inside of the document conveyance unit 70 An image reading operation for automatically reading the images on the front and back sides of the conveyed document D by one conveyance is realized.

  At this time, as shown in FIG. 11, the reading control unit 58 is inclined at one position extending in the sub-scanning direction generated in the region corresponding to the peripheral portion of the document D on the document background plate 79a with respect to the first surface of the document D tilted. One inclined edge De extending in the sub-scanning direction of the document D from the shadow Ds is detected. Further, the reading control unit 58 relates to the second surface of the document D which has been tilted, from one tilted shadow Ds extending in the sub-scanning direction generated in a region corresponding to the peripheral portion of the document D on the document background plate 80a. One inclined edge De extending in the sub-scanning direction is detected. Then, the reading control unit 58 derives two inclined edges De with respect to the entire document D by superimposing the image data on the first surface of the document D and the image data on the second surface of the document D. . Then, the reading control unit 58 accurately discriminates the area Da of the entire inclined document D by complementing the two inclined edges De in the sub-scanning direction.

<Sixth Embodiment>
Next, an image reading apparatus according to a sixth embodiment of the present invention will be described with reference to FIGS. FIG. 12 is a flowchart illustrating an example of document area determination processing by the image reading apparatus. FIG. 13 is an explanatory diagram showing document area determination processing by the image reading apparatus. Since the basic configuration of this embodiment is the same as that of the first, third, and fifth embodiments described above, the same reference numerals or the same names as before are used for the components common to those embodiments. A description thereof may be omitted.

  When the area determination process for the document D is started by the image reading device 40 of the sixth embodiment (start of FIG. 12), the image on the first surface of the document D is read in step # 201. In step # 202, the edge De of the first surface of the document D is detected, and the inclination of the edge De with respect to the main scanning direction or the sub-scanning direction is determined.

  In step # 203, the image on the second side of the document D is read. In step # 204, the edge De of the second surface of the document D is detected, and the inclination of the edge De with respect to the main scanning direction or the sub-scanning direction is determined.

  In step # 205, the reading control unit 58 determines whether or not there is a difference between the inclination of the edge De of the first surface of the document D and the inclination of the edge De of the second surface. For this determination, a predetermined threshold value may be set in advance, and when this threshold value is exceeded, it may be determined that there is a difference between the two slopes, or it may be determined whether or not there is a perfect match. If there is a difference between the two slopes (see FIG. 13), the process proceeds to step # 206. If there is no difference between the inclinations, the process proceeds to step # 207.

  In step # 206, the reading control unit 58 executes an inclination correction process for the edge De of the document D (see FIG. 13). In the tilt correction process, a process of matching the tilt of one edge De on the front and back sides of the document D with the other edge De or a process of matching both edges De in the sub-scanning direction is executed. In this embodiment, for example, an inclination correction process for matching the inclination of the edge De of the second surface of the document D with the inclination of the edge De of the first surface is executed. More specifically, regarding the tilt correction, for example, a process of rotating the image data around the center of the edge De in the axial direction is executed.

  In step # 207, the image data relating to the first and second surfaces of the document D are superimposed, and the region Da of the entire document D is discriminated by complementing the two edges De in the sub-scanning direction. Is done. Then, the area determination process for the document D is terminated (END in FIG. 12).

<Seventh embodiment>
Next, an image reading apparatus according to a seventh embodiment of the present invention will be described with reference to FIG. FIG. 14 is an explanatory diagram showing document area determination processing by the image reading apparatus. Since the basic configuration of this embodiment is the same as that of the first and third embodiments described above, the same reference numerals or the same names as those in the previous embodiment are assigned to the components common to those embodiments. The description may be omitted.

  The image reading apparatus 40 according to the seventh embodiment copes with the possibility that the area Da of the entire document D cannot be accurately determined due to the positional deviation between the front and back surfaces (first surface and second surface) of the document D. .

  For this reason, as shown in FIG. 14, the reading control unit 58 has two locations extending in the main scanning direction generated in the area corresponding to the peripheral edge of the document D from the image data relating to the first surface and the second surface of the document D. A shadow Dh is detected. Then, the length and inclination of the document D in the sub-scanning direction are detected using the detected one shadow Ds extending in the sub-scanning direction, and the document is further detected using the two shadows Dh extending in the main scanning direction. The length of D in the main scanning direction is determined.

  The reading control unit 58 could not detect from the information of the detected shadow Ds extending in the sub-scanning direction, the length and inclination of the document D in the sub-scanning direction, and the length of the document D in the main scanning direction. The other shadow extending in the scanning direction is estimated, and two edges De extending in the sub-scanning direction are derived. Then, the reading control unit 58 accurately discriminates the area Da of the entire tilted document D by complementing the two edges De in the sub-scanning direction.

<Eighth Embodiment>
Next, an image reading apparatus according to an eighth embodiment of the present invention will be described with reference to FIG. FIG. 15 is an explanatory diagram showing document area determination processing by the image reading apparatus. The basic configuration of this embodiment is the same as that of the first, third, fifth, sixth, and seventh embodiments described above. The same reference numerals or the same names may be attached and the description thereof may be omitted.

  The image reading apparatus 40 according to the eighth embodiment may not be able to accurately determine the area Da of the entire document D due to the positional deviation between the front and back surfaces (first surface and second surface) of the document D. Furthermore, this corresponds to a case where the document D is tilted.

  For this reason, as shown in FIG. 15, the reading control unit 58 has two locations extending in the main scanning direction generated in the area corresponding to the peripheral edge of the document D from the image data relating to the first and second surfaces of the document D. A shadow Dh is detected. Then, the length and inclination of the document D in the sub-scanning direction are detected using the detected one shadow Ds extending in the sub-scanning direction, and the document is further detected using the two shadows Dh extending in the main scanning direction. The length of D in the main scanning direction is determined.

  The reading control unit 58 could not detect from the information of the detected shadow Ds extending in the sub-scanning direction, the length and inclination of the document D in the sub-scanning direction, and the length of the document D in the main scanning direction. The other shadow extending in the scanning direction is estimated, and two edges De extending in the sub-scanning direction are derived. Then, the reading control unit 58 accurately discriminates the area Da of the entire tilted document D by complementing the two edges De in the sub-scanning direction.

  As in the above embodiment, the image reading apparatus 40 includes the first illumination unit 52 that irradiates light toward the document D, the document background plate 70a that faces the first illumination unit 52 across the document D, and the first illumination unit 52. In order to move the first illumination unit 52 relative to the document D and the image sensor 57 that receives the reflected light irradiated from one illumination unit 52 and reflected from one surface of the document D and the surface of the document background plate 70a. In order to detect the edge De of the document D from the shadow Ds generated in the region corresponding to the peripheral portion of the document D on the document background plate 70a based on the information from the scanning drive unit 53 and the image sensor 57 that has received the reflected light. Read control unit 58. In the first illuminating unit 52, the main light distribution intensity at the peripheral portion of the document D is higher than the component in the document inner direction in the main scanning direction that intersects the sub-scanning direction that is the moving direction of the first illuminating unit 52 by the scanning driving unit 53. Also has a strong distribution in the document outer direction component.

  According to this configuration, since the intensity of the main light distribution at the peripheral portion of the document D is stronger in the document outer direction component than the component in the document inner direction, the edge of the document D in the region corresponding to the peripheral portion of the document D on the document background plate 70a. It becomes possible to easily generate a shadow Ds representing De. Further, by making the document background plate 70a white, a shadow Ds having a relatively large density difference from the document background plate 70a can be obtained. Accordingly, the area Da of the entire document D can be easily accurately determined with a simpler configuration, and information on the document D can be obtained appropriately.

  The first illumination unit 52 includes an LED 52a that is a light source, a light guide 52b that is disposed over the entire region in the main scanning direction between the LED 52a and the document D, receives the light from the LED 52a, and emits the light toward the document D. Is provided. And LED52a is arrange | positioned in the position corresponding to the center of the main scanning direction of the light guide 52b.

  According to this configuration, the main light beam out of the light emitted from the LED 52a is emitted from the center of the light guide 52b in the main scanning direction. Thereby, it is possible to clearly generate the shadow Ds of the document D extending in the sub-scanning direction at both ends of the document D in the main scanning direction.

  Moreover, the light guide 52b has the diffusion part 52e for diffusing the light of LED52a in the area | region corresponding to the installation position of LED52a.

  According to this configuration, the light of the LED 52a that enters the light guide 52b and is emitted upward from the diffusion portion 52e can be diffused over the entire region in the main scanning direction. As a result, the entire document D can be irradiated with light, and information on the document D can be obtained appropriately.

  Further, in the third embodiment, the image reading device 40 includes the first reading unit 79 and the second reading unit 80 for individually reading the front and back images of the document D, and the illumination unit applies the document to the document by the first reading unit 79. A first illumination unit 52 that emits light toward the screen and a second illumination unit 82 that emits light toward the document by the second reading unit 80 are included. The first illumination unit 52 has a distribution in which the intensity of the main light distribution is stronger in the component in the document outer direction than the component in the document inner direction with respect to one end (front) side in the main scanning direction. Regarding the other end side (back side) of the direction, the intensity of the main light distribution has a distribution in which the document outside direction component is stronger than the document inside direction component. The reading control unit 58 detects the edge De of the first and second surfaces of the document D detected using the first reading unit 79 and the edge of the second and second surfaces of the document D detected using the second reading unit 80. The edge De of the entire document D is determined using De.

  According to this configuration, the first illumination unit 52 emits light whose main light distribution intensity is higher in the document outer direction component than in the document inner direction component at the front side peripheral portion of the document D in the main scanning direction. It is possible to easily generate a shadow Ds representing the edge De of the document D in an area corresponding to the peripheral portion of the document D on the document background plate 79a. Further, since the second illumination unit 82 emits light whose main light distribution intensity is stronger in the document outer direction component than in the document inner direction component at the rear side peripheral portion of the document D with respect to the main scanning direction, the document background plate on the rear side. It is possible to easily generate a shadow Ds representing the edge De of the document D in an area corresponding to the peripheral edge of the document D of 80a. Therefore, it is possible to accurately determine the area Da of the entire document D easily by using the edges De on the front and back surfaces of the document D with a simpler configuration, and the information on the document D can be obtained appropriately. .

  Further, with respect to the main scanning direction, the light irradiation direction by the first illumination unit 52 and the light irradiation direction by the second illumination unit 82 are different.

  Furthermore, the 1st illumination part 52 has LED52a, the 2nd illumination part 82 has LED82a, LED52a is arrange | positioned at the edge part side of the back surface of a main scanning direction, LED82a is the edge part side of the front surface of a main scanning direction Placed in.

  According to these configurations, the LED 52a of the first illumination unit 52 is disposed on the back side of the light guide 52b, so that the light guide 52b is received from the LED 52a and is directed from the upper surface to the first surface (lower surface) of the document D. The main directing direction of the emitted light is the front direction of the image reading device 40. Thereby, with respect to the first illumination unit 52, the distribution of the main light distribution intensity in the front side peripheral portion of the document D can be made stronger in the document outer direction component than in the document inner direction component. Further, the LED 82a of the second illumination unit 82 is arranged on the front side of the light guide 82b, so that the light guide 82b receives from the LED 82a and is emitted from the lower surface toward the second surface (upper surface) of the document D. The main directing direction of the image reading device 40 is directed backward. Thereby, with respect to the second illumination unit 82, the intensity of the main light distribution at the rear side peripheral edge of the document D can be distributed so that the document outer direction component is stronger than the document inner direction component.

  In the fourth embodiment, the reading control unit 58 individually executes the image reading process and the edge detection process of the document D with respect to each of the first reading unit 79 and the second reading unit 80, and the one to be executed later. An edge detection process related to the other image reading process executed earlier during the image reading process is executed.

  According to this configuration, part of the image reading process and the edge detection process related to the front and back of the document D can be performed in parallel, and the area Da of the entire document D can be quickly determined. As a result, it is possible to improve the productivity for reading an image of a document.

  In the sixth embodiment, when the reading control unit 58 detects the inclination of the edge De of the document D with respect to the main scanning direction and the sub-scanning direction, and there is a difference in the inclination of the edge De on both the front and back sides of the document D. The tilt correction process is executed.

  According to this configuration, the edge De of the document D can be detected corresponding to the tilted document D. Thereby, even when the document D is inclined, the area Da of the entire document D can be accurately determined.

  In the seventh embodiment, the image reading device 40 includes the first reading unit 79 and the second reading unit 80 for individually reading the front and back images D of the document D, and the illumination unit is disposed in the first reading unit 79. The first illumination unit 52 and the second illumination unit 82 disposed in the second reading unit 80 are included. The reading control unit 58 detects the edge De of the document D extending in the main scanning direction and the edge De of the document D extending in the sub-scanning direction, and detects one of the front and back sides of the document D detected using the first reading unit 79. The edge De of the entire document D is discriminated using the edge De extending in the main scanning direction and the sub-scanning direction, and the other main scanning direction and sub-scanning of the front and back of the document D detected using the second reading unit 80 are detected. The edge De of the entire document D is determined using the edge De extending in the direction.

  According to this configuration, the edge De of the entire document D can be individually determined for each of the front and back sides of the document D.

  Furthermore, in the embodiment, the image reading apparatus 40 having the above configuration is provided in the image forming apparatus 1.

  According to this configuration, the image forming apparatus 1 can easily determine the area Da of the entire document D accurately with a simpler configuration, and information on the document D can be obtained appropriately.

  Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the invention.

  For example, the parallel processing of image reading and edge detection related to the front and back surfaces of the document D described in the fourth embodiment is used in combination with other embodiments that determine the area Da of the entire document D from the images of the front and back surfaces of the document D. It is possible.

  In the above-described embodiment, the image forming apparatus 1 is an image forming apparatus for color printing in which a toner image is transferred onto the paper P using the intermediate transfer belt 11. However, the image forming apparatus 1 is not limited to such a model. An image forming apparatus that does not use a transfer belt or an image forming apparatus for monochrome printing may be used.

  The present invention can be used in an image reading apparatus and an image forming apparatus.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 40 Image reader 50 Optical scanning unit 51 Contact glass 52 1st illumination part 52a LED (light source)
52b Light guide 52e Diffusion part 53 Scan drive part (drive part)
57 Image sensor
58 Reading control unit (control unit)
70 Document transport unit 70a Document background plate (document background portion)
73 Conveyance drive unit (drive unit)
79 First reading section 79a Document background plate (document background section)
80 Second reading section 80a Document background plate (document background section)
81 Contact glass 82 2nd illumination part 82a LED (light source)
82b Light guide 83 Image sensor (imaging device)

Claims (10)

An illumination unit that emits light toward the document;
A document background portion facing the illumination unit across the document;
An image sensor that receives reflected light that is irradiated from the illumination unit and reflected from one surface of the document and the surface of the document background;
A drive unit for moving one of the original or the illumination unit relative to the other;
A control unit for detecting an edge of the document from a shadow generated in an area corresponding to a peripheral portion of the document in the document background portion based on information from the imaging element that has received the reflected light;
With
The illumination unit has a main light distribution intensity in at least one peripheral portion of the document that is higher than a component in the document inward direction with respect to a main scanning direction that intersects a sub-scanning direction that is a moving direction of the document by the driving unit or the illumination unit. An image reading apparatus characterized in that a document outer direction component has a strong distribution. The illumination unit includes a light source, and a light guide that is disposed over the entire region in the main scanning direction between the light source and the document, receives light from the light source, and emits the light toward the document.
The image reading apparatus according to claim 1, wherein the light source is disposed at a position corresponding to a center of the light guide in a main scanning direction.   The image reading apparatus according to claim 2, wherein the light guide has a diffusion unit for diffusing light of the light source in a region corresponding to an installation position of the light source. A first reading unit and a second reading unit for individually reading the front and back images of the document;
The illumination unit includes a first illumination unit that emits light toward the document by the first reading unit, and a second illumination unit that emits light toward the document by the second reading unit,
The first illumination unit has a distribution in which the intensity of the main light distribution is stronger in the document outer direction component than in the document inner direction component on one end side in the main scanning direction,
The second illumination unit has a distribution in which the intensity of the main light distribution is stronger in the document outer direction component than in the document inner direction component with respect to the other end side in the main scanning direction.
The control unit uses one edge of the front and back sides of the document detected using the first reading unit and the other edge of the front and back sides of the document detected using the second reading unit. The image reading apparatus according to claim 1, wherein:   The image reading apparatus according to claim 4, wherein the light irradiation direction by the first illumination unit is different from the light irradiation direction by the second illumination unit with respect to the main scanning direction.   The first illumination unit includes a first light source, the second illumination unit includes a second light source, the first light source is disposed on one end side in the main scanning direction, and the second light source is the other in the main scanning direction. The image reading apparatus according to claim 5, wherein the image reading apparatus is disposed on an end side of the image reading apparatus.   The control unit individually executes the document image reading process and the edge detection process for each of the first reading unit and the second reading unit, and is executed first during one of the image reading processes to be executed later. The image reading apparatus according to claim 4, wherein an edge detection process related to the other image reading process is executed.   The control unit detects the inclination of the detected document edge with respect to the main scanning direction and the sub-scanning direction, and executes an inclination correction process when there is a difference in the inclination of both the front and back edges of the document. The image reading apparatus according to claim 4. A first reading unit and a second reading unit for individually reading the front and back images of the document;
The illumination unit includes a first illumination unit disposed in the first reading unit and a second illumination unit disposed in the second reading unit,
The control unit detects an edge of the document extending in the main scanning direction and an edge of the document extending in the sub-scanning direction, and detects one of the main scanning direction and the sub-surface of the document detected using the first reading unit. The edges of the entire document are discriminated by using the edges extending in the scanning direction, and the edges of the entire document are detected by using the edges extending in the other main scanning direction and the sub-scanning direction of the document detected using the second reading unit. The image reading apparatus according to claim 1, wherein an edge is discriminated.   An image forming apparatus comprising the image reading apparatus according to claim 1.