Reading device

Abstract

To provide a reading device capable of preferably determining a reading start position even if there is a joint line in a photoelectric conversion element column in a photoelectric conversion part.SOLUTION: A housing holding a document mounting board 13 provides a facing part 52. In the facing part 52, a rectangular hole 51 having a first side 53 and a second side 54, along a main scanning direction and a third side 55 and a fourth side 56, along a sub-scanning direction is formed. The third side 55 and the fourth side 56, along the sub-scanning direction of the rectangular hole 51 are arranged at a position corresponded to a center region CA in a photoelectric conversion element column 27 provided to a CIS unit in the main scanning direction. The rectangular hole 51 is read by the CIS unit, the second side 54 and the third side 55 of the rectangular hole 51 are detected, an X-coordinate of the third side 55 and a Y-coordinate of a center position of the second side 54 are determined as a coordinate at a reading start position.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a reading device. [Background technology]

[0002] In a reading device capable of reading an original by the FB (Flat Bed) method, a reading unit that reads one line along the main scanning direction is provided below the original table on which the original is placed, and is movable in the sub-scanning direction. In this type of reading device, an origin position is detected to determine the reading range of the reading unit, and after the origin detection, the reading unit is moved to a position corresponding to the reading start position at the beginning of the reading range, and reading of the original is started.

[0003] There are several methods for detecting the origin, such as providing a photosensor and detecting the origin position from the position of the reading unit when it is detected by the photosensor, or reading a mark provided on a holder that surrounds and holds the document table with the reading unit and detecting the origin position from the position of the mark that has been read. However, these methods have a problem in that the origin position varies if the positions of the photosensor and marks vary between products.

[0004] Therefore, a method has been proposed in which a rectangular hole is provided in the holder, the rectangular hole is read by a reading unit, and the reading start position is calibrated based on the positions of the sides of the rectangular hole (see, for example, Patent Document 1). The holder is made of resin, and the rectangular hole is built in when the holder is molded, so there is almost no variation in position between products. Therefore, it is possible to accurately calibrate the reading start position based on the positions of the sides of the rectangular hole. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2002-354206 A Summary of the Invention [Problem to be solved by the invention]

[0006] In recent years, a CIS (Contact Image Sensor) with a 1:1 optical system has been used in the reading unit of a reading device. In a CIS with a 1:1 optical system, the required size of the photoelectric conversion section is larger than that of a combination of a reduction optical system and a CCD module, so the photoelectric conversion section is configured by arranging multiple chips in the main scanning direction, each chip having a large number of photoelectric conversion elements arranged in the main scanning direction, while also taking yield into consideration.

[0007] Therefore, there are joints between the photoelectric conversion element rows in one line, and there are places where there are no photoelectric conversion elements. However, the size of the joints is about 1 to 2 pixels, and depending on the resolution, the reading results by the reading unit are of a quality that can eliminate the sense of incongruity caused by the joints through interpolation from the surrounding data.

[0008] However, as mentioned above, when the reading position is calibrated using the position of the rectangular hole provided in the holding section, the side of the rectangular hole extending in the sub-scanning direction is less likely to be shadowed by light from the light source of the reading unit, and the pixel width is approximately 1 to 2 pixels. Therefore, if the side extending in the sub-scanning direction overlaps with the seam of the chip of the photoelectric conversion section, the pixels on that side will disappear from the reading result, and it will be impossible to determine the reading start position in the main scanning direction.

[0009] An object of the present invention is to provide a reading device that can accurately determine the reading start position even if there is a joint between photoelectric conversion element rows in a photoelectric conversion section. [Means for solving the problem]

[0010] In order to achieve the above-mentioned object, the reading device of the present invention comprises a document table having a document placing surface on which a document is placed, a photoelectric conversion unit facing the document table from the side opposite the document placing surface and having a light source and a photoelectric conversion element array in which a plurality of photoelectric conversion elements are arranged in the main scanning direction, the reading unit moving along the document table in a sub-scanning direction perpendicular to the main scanning direction to read the document on the document placing surface, and a holding unit having a facing portion facing the document placing surface side at the periphery of the document table and holding the periphery, the facing portion having a rectangular hole formed therein having a side along the main scanning direction and a side along the sub-scanning direction, and at least one side of the rectangular hole along the sub-scanning direction is positioned in a position in the main scanning direction corresponding to the central region of the photoelectric conversion element array excluding both ends of the photoelectric conversion element array.

[0011] According to this configuration, the holding portion that holds the document table has a facing portion that faces the document placement surface side of the document table, and a rectangular hole having a side along the main scanning direction and a side along the sub-scanning direction is formed in the facing portion.

[0012] The photoelectric conversion unit of the reading section has a configuration in which photoelectric conversion element rows are arranged in the main scanning direction. At least one side of the rectangular hole along the sub-scanning direction is arranged in a position corresponding to the central region of the photoelectric conversion element rows in the main scanning direction. This makes it possible to read the side that is arranged in the position corresponding to the central region of the photoelectric conversion element rows without being affected by the seam, even if there is a seam in the photoelectric conversion element rows.

[0013] Therefore, the reading start position can be accurately determined based on the positions of the sides of the rectangular hole. Effect of the Invention

[0014] According to the present invention, even if there is a joint between photoelectric conversion element rows in a photoelectric conversion section, the reading start position can be determined accurately. [Brief description of the drawings]

[0015] [Figure 1] 1 is a perspective view of a multifunction peripheral including a reading device according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a cross-sectional view diagrammatically showing the configuration of a reading device. [Diagram 3] FIG. 2 is a cross-sectional view diagrammatically showing the configuration of a CIS unit. [Figure 4] FIG. 2 is a block diagram showing an electrical configuration of the reading device. [Diagram 5] 11 is a diagram for explaining the positional relationship between a rectangular hole and a photoelectric conversion element array. FIG. [Figure 6] 13 is a flowchart showing a procedure for determining a reading range. [Figure 7A] 10 is a diagram illustrating how light hits when detecting a first side of a rectangular hole. FIG. [Figure 7B] 13 is a diagram illustrating how light hits when detecting a second side of a rectangular hole. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0017] <Reader configuration> The reading device 1 shown in Figures 1 and 2 is a device for reading a document, and includes a housing 2 (an example of a holding section) and a document cover 4 with an ADF (Auto Document Feeder) 3 integrally provided therewith.

[0018] For the purposes of the following description, the front, back, left and right of the reading device 1 are defined based on the state in which the reading device 1 is viewed from the front side. The top and bottom are defined when the reading device 1 is installed on a horizontal surface. The cross section shown in Fig. 2 is a cross section of the reading device 1 cut along a cutting line extending in the left-right direction.

[0019] The housing 2 is a resin molded product and has a substantially rectangular parallelepiped shape. A first opening 11 and a second opening 12 are provided on the top surface of the housing 2. The first opening 11 has edges extending in the front-rear and left-right directions, and is formed into a rectangular shape that is longer left-right than front-rear. The second opening 12 is formed on the left side of the first opening 11, has edges extending in the front-rear and left-right directions, and is formed into a rectangular shape that is elongated in the front-rear direction.

[0020] An original placement plate 13 (an example of an original table) is provided so as to cover the first opening 11 from below. The original placement plate 13 is a flat body made of a transparent material, for example a flat glass plate. The original placement plate 13 is surrounded by the periphery of the first opening 11 in the housing 2 and is held by the periphery.

[0021] Further, an original passing plate 14 is provided so as to cover the second opening 12 from below. The original passing plate 14 is a flat plate made of a transparent material, for example a glass plate. The original passing plate 14 is surrounded by the periphery of the second opening 12 in the housing 2, and is held by the front part, the rear part, and the left part of the periphery.

[0022] The portion between the first opening 11 and the second opening 12 in the housing 2 serves as a guide section 15, which guides the document when the document is read. The guide section 15 has a tip reference surface 15a, which is a flat surface extending in the front-rear and up-down directions, on its right end surface, and a transport guide surface 15b, which is inclined upward to the right, on its upper surface.

[0023] The reading device 1 is capable of reading documents by both the FB method and the ADF method. The upper surface of the document placement plate 13 is a document placement surface 16 on which the document is placed when the document is read by the FB method. The guide portion 15 functions as a guide for determining the position of the document on the document placement surface 16, and the document is placed in a state in which the left edge of the document abuts against the leading edge reference surface 15a of the guide portion 15 from the right side, and the rear edge of the document abuts against the rear reference surface 11a facing the front side of the first opening 11. The upper surface of the document passing plate 14 is a document passing surface 17 through which the document passes when the document is read by the ADF method. The guide portion 15 functions as a guide for guiding the transport of the document, and after the document passes through the document passing surface 17, it is transported along the transport guide surface 15b of the guide portion 15.

[0024] A CIS (Contact Image Sensor) unit 21 is provided within the housing 2 below the document placement plate 13 and the document passing plate 14 so as to be movable in the sub-scanning direction, which is the left-right direction, by a CIS unit moving section 28, which will be described later. The CIS unit 21 (an example of a reading section) includes a light source 22, a light guide 23, a rod lens array 24, and a photoelectric conversion section 25, as shown in FIG.

[0025] The light source 22 includes three light emitting diodes (LEDs) of red, green and blue colors.

[0026] The light guide 23 is a member that propagates light from the light source 22, is made of a transparent material, and extends, for example, in front of the light source 22 in the main scanning direction, which is the front-rear direction perpendicular to the sub-scanning direction.

[0027] The rod lens array 24 is made up of gradient index lenses and includes a large number of rod lenses aligned in the main scanning direction. The rod lens array 24 is shifted in the left-right direction from the light guide 23, and is disposed, for example, on the left side of the light guide 23.

[0028] The photoelectric conversion section 25 includes a predetermined number (for example, 12) of sensor IC chips 26. The sensor IC chips 26 are arranged in a line in the main scanning direction. Each sensor IC chip 26 includes a photoelectric conversion element array 27. The photoelectric conversion element array 27 is configured by arranging a plurality of photoelectric conversion elements in a line at equal pitch in the main scanning direction. Each photoelectric conversion element outputs a charge according to the amount of received light as an electrical signal for one pixel. The CIS unit 21 is equipped with a gain adjustment circuit, an A / D conversion circuit, and the like. The voltage output from each photoelectric conversion element is amplified by the gain adjustment circuit and then converted by the A / D conversion circuit into pixel data (pixel value), which is a digital value. The A / D conversion circuit has, for example, a resolution of 8 bits (0 to 255) and uniformly converts voltages below a lower limit reference voltage (lower limit value) to "0", converts voltages above an upper limit reference voltage (upper limit value) to "255", and converts voltages in the range from the lower limit value to the upper limit value into pixel data according to the magnitude of the voltage.

[0029] Light from light source 22 is irradiated onto the object to be read through light guide 23, and the light reflected from the object to be read passes through rod lens array 24 and enters photoelectric conversion unit 25. Photoelectric conversion is performed in each photoelectric conversion element of photoelectric conversion unit 25, an electrical signal is output from each photoelectric conversion element, and the electrical signal is converted into pixel data, thereby achieving reading of one line in the main scanning direction by CIS unit 21.

[0030] 2, the ADF 3 (an example of a document feeder) includes a supply tray 31 and a discharge tray 32. The supply tray 31 and the discharge tray 32 are provided in a vertically overlapping state with a gap therebetween. A transport path 33 is formed within the ADF 3, one end of which opens on one end of the supply tray 31 in the sub-scanning direction, turns back while curving in a U-shape, passes over the document passing surface 17, and the other end opens between the supply tray 31 and the discharge tray 32. Also, within the ADF 3, a supply roller 34, a separation roller 35, a transport roller 36, a reversing roller 37, and a discharge roller 38 are provided in this order from the supply tray 31 side along the transport path 33.

[0031] The document cover 4 is provided so as to be able to open and close between an open position and a closed position. When the document cover 4 is in the closed position, the document cover 4 covers the entire upper surface of the housing 2. The document cover 4 is displaced to the open position by lifting the front side from the closed position. When the document cover 4 is in the open position, the entire upper surface of the housing 2 is exposed.

[0032] When reading an original using the FB method, the original cover 4 is opened to the open position, and the original is placed on the original placement surface 16. Thereafter, the original cover 4 is closed to the closed position, and the original is covered from above by the original cover 4. Then, in response to a command to execute scanning, the CIS unit 21 is moved by the CIS unit movement section 28 from the origin position to a position corresponding to the reading start position at the beginning of the reading range, and while being moved from that position in the sub-scanning direction, the CIS unit 21 reads the original on the original placement surface 16 line by line in the sub-scanning direction, thereby accomplishing reading of the original.

[0033] On the other hand, when reading an original using the ADF method, the original is placed on the supply tray 31 of the ADF 3. The CIS unit 21 is stopped at a position facing the original passing plate 14 from below. Thereafter, in response to a command to execute scanning, the supply rollers 34 start transporting the original. The original is separated into individual sheets by the separation rollers 35, and is transported along the transport path 33 by the transport rollers 36 and the reversal rollers 37. As the original passes through the original passing surface 17, the CIS unit 21 reads the original line by line in order, thereby completing the reading of the original.

[0034] 4, the reader 1 includes a CPU (Central Processing Unit) 41, a data-rewritable non-volatile memory 42 such as a flash memory or an E2PROM, and a volatile memory 43 such as an SDRAM. The CPU 41, the non-volatile memory 42, and the volatile memory 43 are connected to a bus 44 for data communication.

[0035] The CPU 41 (an example of a control unit) executes programs for various processes to control each part of the reading device 1 including the ADF 3, the CIS unit 21, and the CIS unit moving unit 28. The CIS unit moving unit 28 is made up of a moving guide, a motor, a drive mechanism, etc. (not shown). The non-volatile memory 42 stores programs executed by the CPU 41 and various data. The volatile memory 43 is used as a work area when the CPU 41 executes the programs.

[0036] <Determining the reading range> As described above, when starting to read an original using the FB method, the CIS unit 21 is moved to a position corresponding to the read start position. The read start position is the leading position of the reading range of the original by the CIS unit 21, and in order for the CIS unit 21 to read the entire original that is abutted against the leading edge reference surface 15a or the rear reference surface 11a, it is necessary to precisely match the read start position with the position of the rear reference surface 11a in the main scanning direction and with the position of the leading edge reference surface 15a in the sub-scanning direction.

[0037] In order to determine the reading start position, as shown in Fig. 3, a rectangular hole 51 is formed in the guide section 15. Specifically, as shown in Fig. 2, the guide section 15 has a facing section 52 that faces the left end of the document placement plate 13 from above. In this facing section 52, as shown in Fig. 5, a rectangular hole 51 with each side of 5 mm and a depth of 0.5 mm is formed as a recess recessed upward at a position corresponding to within the region in the document placement surface 16 where the document is placed in the main scanning direction and corresponding to the photoelectric conversion element row 27 closest to the light source 22 among the photoelectric conversion element rows 27 of the CIS unit 21, that is, the photoelectric conversion element row 27 arranged at the rearmost side (hereinafter, this photoelectric conversion element row 27 is referred to as "photoelectric conversion element row 27A").

[0038] Depending on the design of the light guide 23, it is possible to make the center of the reading range in the main scanning direction brighter. In that case, the rectangular hole 51 can be arranged so as to correspond to the position of the photoelectric conversion element row 27 that corresponds to the position designed to be the brightest.

[0039] The rectangular hole 51 has a first side 53 and a second side 54 along the main scanning direction at the left end and the right end, respectively, and a third side 55 and a fourth side 56 along the sub-scanning direction at the rear end and the front end, respectively. The distance between the third side 55 and the fourth side 56 along the sub-scanning direction is shorter than the length of the photoelectric conversion element array 27 in the main scanning direction, and the third side 55 and the fourth side 56 are arranged at a position corresponding to the central area CA of the photoelectric conversion element array 27A. Therefore, the position corresponding to the photoelectric conversion element array 27A is, in other words, a position where the third side 55 and the fourth side 56 of the rectangular hole 51 can face the central area CA of the photoelectric conversion element array 27A in the up-down direction. The central area CA is, for example, an area obtained by removing an area of ​​1 mm from each end of the photoelectric conversion element array 27A in the main scanning direction.

[0040] The CPU 41 determines the reading start position according to the procedure (flow of processing) shown in FIG.

[0041] When determining the reading start position, the CPU 41 moves the CIS unit 21 to a position at least on one side in the sub-scanning direction (for example, the left side) of the rectangular hole 51. After that, the CPU 41 moves the CIS unit 21 from that position to the other side in the sub-scanning direction (for example, the right side) and causes the CIS unit 21 to read the range where the facing portion 52 where the rectangular hole 51 is formed is located.

[0042] Then, the CPU 41 detects a first side 53 of the rectangular hole 51 along the main scanning direction from the data read by the CIS unit 21 (S1). Taking advantage of the fact that there are no figures or shapes that would cause density changes other than the rectangular hole 51 in the area where the facing portion 52 exists, edge enhancement processing using a Sobel filter or the like is used for detection. Then, it is determined that the first side 53 to the fourth side 56 are located where it is determined that an edge exists through the edge enhancement processing.

[0043] The reason why first side 53 is detected instead of second side 54 is that, when viewed along the direction in which light from light guide 23 travels, first side 53 is the side that connects from facing portion 52 to rectangular hole 51, as shown in FIG. 7A, and therefore the left side of first side 53 in the figure becomes a shadow area of ​​the light from light guide 23, resulting in a large density difference between the reflected light from facing portion 52 and the shadow area of ​​rectangular hole 51. In edge enhancement processing, the greater the density difference, the more reliable the detection, so as shown in Fig. 7B, the second side 54 has a smaller density difference than the first side 53 because the light from the light guide 23 reflected by the bottom surface of the rectangular hole 51 and the light reflected by the facing portion 52 are adjacent to each other. Therefore, the first side 53 is detected.

[0044] The CPU 41 also detects a third side 55 of the rectangular hole 51 along the sub-scanning direction from the data read by the CIS unit 21 (S2). The third side 55 and the fourth side 56 are parallel to the direction of travel of the light from the light guide 23, so there is not much difference in the size of the shadow area; however, the third side 55 is closer to the light source 22 in the main scanning direction and is illuminated more brightly by the light from the light source 22 than the fourth side 56, so the density difference is larger than that of the fourth side 56, and detection can be performed more accurately.

[0045] Thereafter, CPU 41 determines the X coordinate of third side 55, with the main scanning direction defined as the X direction and the sub-scanning direction defined as the Y direction, and determines the coordinate of the reading start position in the main scanning direction from the distance to the X coordinate of rear reference surface 11a, which is determined by design (S3). Also, CPU 41 determines the Y coordinate of the center position of first side 53, and determines the coordinate of the reading start position in the sub-scanning direction from the distance to the Y coordinate of front end reference surface 15a, which is determined by design (S3).

[0046] Standard coordinates of the reading start position are stored in advance as standard position coordinates (Xtyp, Ytyp) in the non-volatile memory 42. The CPU 41 calculates the difference Δ(X, Y) between the coordinates (X, Y) of the reading start position obtained from the reading result and the standard position coordinates (Xtyp, Ytyp) stored in the non-volatile memory 42 (S4).

[0047] Then, the CPU 41 adjusts the position of the reading range of the document when the standard position coordinates (Xtyp, Ytyp) are set as the reading start position by the difference Δ(X, Y), and determines the reading range after the position adjustment as the reading range of the document (S5).

[0048] <Action and effect> As described above, the housing 2 that holds the document placement plate 13 is provided with a facing portion 52 that faces the document placement surface 16 of the document placement plate 13, and the facing portion 52 is formed with a rectangular hole 51 having a first side 53 and a second side 54 along the main scanning direction and a third side 55 and a fourth side 56 along the sub-scanning direction. The housing 2 is a resin molded product. Therefore, there is almost no variation between products in the positional relationship between the front reference surface 15a and the rear reference surface 11a that define the document placement position, i.e., the range that needs to be read, and the rectangular hole 51.

[0049] The photoelectric conversion section 25 of the CIS unit 21 has a configuration in which photoelectric conversion element arrays 27 are arranged in the main scanning direction. A third side 55 and a fourth side 56 along the sub-scanning direction of the rectangular hole 51 are arranged in positions in the main scanning direction corresponding to a central area CA of the photoelectric conversion element array 27. As a result, even if there is a seam G (see FIG. 5) in the photoelectric conversion element array 27, the third side 55 and the fourth side 56 arranged in positions corresponding to the central area CA of the photoelectric conversion element array 27 can be read without being affected by the seam G.

[0050] Then, the CIS unit 21 reads the rectangular hole 51, detects the first side 53 and the third side 55 of the rectangular hole 51, and determines the coordinates of the reading start position based on the X coordinate of the third side 55 and the Y coordinate of the center position of the first side 53. Therefore, the reading start position can be accurately determined based on the positions of the sides of the rectangular hole 51.

[0051] The rectangular hole 51 is formed on the underside of the facing portion 52 that comes into contact with the document placement plate 13 (document placement surface 16). Therefore, by reading the rectangular hole 51 under the same conditions as when reading the document, it is possible to achieve focused reading. As a result, the third side 55 and the fourth side 56 of the rectangular hole 51 can be read well.

[0052] Moreover, rectangular hole 51 is formed at a position in the main scanning direction corresponding to the area on document placement surface 16 where the document is placed. The area where the document is placed is an area that is read by CIS unit 21 under good reading conditions such as shading correction, so by forming rectangular hole 51 at a position corresponding to that area, rectangular hole 51 can be read with high accuracy. As a result, the reading start position can be determined more satisfactorily.

[0053] Furthermore, rectangular hole 51 is formed in guide section 15 between document placement surface 16 and document passing surface 17. Since the origin position, which is the home position of CIS unit 21, is provided between document placement surface 16 and document passing surface 17, the time required to move CIS unit 21 from the origin position to read rectangular hole 51 can be shortened.

[0054] Additionally, the third side 55 and the fourth side 56 of the rectangular hole 51 are disposed at positions corresponding to the central area CA of the photoelectric conversion element array 27A. This makes it possible to prevent the third side 55 and the fourth side 56 from overlapping with the joint G of the photoelectric conversion element array 27 or from straddling two photoelectric conversion element arrays.

[0055] Furthermore, since the central area CA is set to an area excluding an area of ​​1 mm from each end of the photoelectric conversion element array 27A, even if assembly tolerances and component tolerances of the CIS unit 21 and the like overlap, it is possible to reliably prevent the third side 55 and the fourth side 56 from overlapping with the seam G of the photoelectric conversion element array 27.

[0056] <Modification> Although one embodiment of the present invention has been described above, the present invention can be embodied in other forms.

[0057] For example, even if both the third side 55 and the fourth side 56 of the rectangular hole 51 are not positioned at a position corresponding to the central area CA of the photoelectric conversion element array 27A, it is sufficient that at least the third side 55, which is to be detected when determining the reading start position, is positioned at a position corresponding to the central area CA.

[0058] In addition, various design modifications can be made to the above-described configuration within the scope of the claims. [Explanation of symbols]

[0059] 1: Reading device 2: Housing 13: Manuscript placement board 15: Guide section 16: Document placement surface 17: Original passage surface 21:CIS Unit 22:Light source 23: Light guide 25: Photoelectric conversion unit 27, 27A: Photoelectric conversion element array 41: CPU 51: Rectangular hole 52: Facing part 53: First side 54: Side 2 55: Third side 56: Side 4 CA: central area

Claims

1. a document table having a document placement surface on which a document is placed; a reading section that faces the document table from the side opposite to the document placement surface side, has a light source, and a photoelectric conversion section configured by arranging a photoelectric conversion element array, in the main scanning direction, in which a plurality of photoelectric conversion elements are arranged, and moves along the document table in a sub-scanning direction perpendicular to the main scanning direction to read the document on the document placement surface; a holding section having a peripheral portion of the document table, the holding section having a facing portion facing the document placement surface side and holding the peripheral portion, a rectangular hole having a side along the main scanning direction and a side along the sub-scanning direction is formed in the facing portion, at least one side of the rectangular hole along the sub-scanning direction is disposed at a position corresponding to a central region of the photoelectric conversion element array excluding both ends in the main scanning direction, the reading unit includes a light guide extending in the main scanning direction and guiding light from the light source in the main scanning direction; the light source is disposed on one side of the light guide in the main scanning direction, The rectangular hole is formed at a position corresponding to the photoelectric conversion element row closest to the light source.

2. 2. The reading device according to claim 1, A control unit, The control unit causes the reading unit to read the rectangular hole to detect a position of at least one side of the rectangular hole, and determines a start position for reading the document by the reading unit based on the detected position.

3. 3. The reading device according to claim 2, The control unit detects the sub-scanning direction position of at least one side of the rectangular hole along the main scanning direction and the main scanning direction position of at least one side along the sub-scanning direction, determines the reading start position in the main scanning direction based on the main scanning direction position, and determines the reading start position in the sub-scanning direction based on the sub-scanning direction position, of the reading device.

4. a document table having a document placement surface on which a document is placed; a reading section that faces the document table from the side opposite to the document placement surface side, has a light source, and a photoelectric conversion section configured by arranging a photoelectric conversion element array, in the main scanning direction, in which a plurality of photoelectric conversion elements are arranged, and moves along the document table in a sub-scanning direction perpendicular to the main scanning direction to read the document on the document placement surface; a holding section having a facing section on a peripheral edge of the document table, the facing section facing the document placement surface side and holding the peripheral edge; A control unit, a rectangular hole having a side along the main scanning direction and a side along the sub-scanning direction is formed in the facing portion, The control unit causes the reading unit to read the rectangular hole to detect the sub-scanning direction position of at least one side of the rectangular hole along the main scanning direction and the main scanning direction position of at least one side along the sub-scanning direction, determines a start position in the main scanning direction from which the reading unit will start reading the document based on the main scanning direction position, and determines a start position in the sub-scanning direction from which the reading unit will start reading the document based on the sub-scanning direction position.

5. The reading device according to any one of claims 2 to 4, The control unit detects the position of a side of the rectangular hole along the main scanning direction that connects the facing portion to the rectangular hole along the traveling direction of light from the light source in the sub-scanning direction.

6. The reading device according to any one of claims 1 to 5, The rectangular hole is formed in a region of the facing portion that comes into contact with the document table.

7. The reading device according to any one of claims 1 to 6, The rectangular hole is formed in a position in the main scanning direction that corresponds to an area of ​​the document placement surface where a document is placed.

8. The reading device according to any one of claims 1 to 7, an original passing surface is provided at a position on one side of the original placement surface in the main scanning direction such that the reading unit can face the original placement surface from the opposite side; a document feed unit that feeds a document onto the document passing surface and transports the document on the document passing surface in the sub-scanning direction, The rectangular hole is formed at a position between the document placement surface and the document passing surface.

9. The reading device according to any one of claims 1 to 8, A reading device, wherein a distance between two sides of the rectangular hole along the sub-scanning direction is shorter than a length of the photoelectric conversion element array.

10. The reading device according to any one of claims 1 to 9, at least one side of the rectangular hole along the sub-scanning direction is disposed at a position corresponding to a central region of the photoelectric conversion element array excluding both ends in the main scanning direction, a reading device, wherein two sides of the rectangular hole along the sub-scanning direction are disposed at positions corresponding to the central region of the photoelectric conversion element array in the main scanning direction.

11. A reading device according to any one of claims 1 to 3 and 10, The central region is a region excluding a region of 1 mm from each end of the photoelectric conversion element array.

12. a document table having a document placement surface on which a document is placed; a reading section that faces the document table from the side opposite to the document placement surface side, has a light source, and a photoelectric conversion section configured by arranging a plurality of photoelectric conversion element rows in the main scanning direction, each row being made up of a plurality of photoelectric conversion elements arranged in the main scanning direction, and moves along the document table in a sub-scanning direction perpendicular to the main scanning direction to read the document on the document placement surface; a facing portion facing the document table, a hole having two sides aligned along the sub-scanning direction is formed in the facing portion, the reading unit includes a light guide extending in the main scanning direction, the light guide is configured to guide light from the light source in the main scanning direction; the light source is disposed at one end of the light guide in the main scanning direction, the hole is formed at a position corresponding to the photoelectric conversion element row that is closest to the light source among the plurality of photoelectric conversion element rows, a reading device, wherein two sides of the hole along the sub-scanning direction are disposed in a position corresponding to a central region of the photoelectric conversion element array excluding both ends in the main scanning direction.

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