Reader

Abstract

To provide a reading device capable of preferably determining a reading range by a reading device.SOLUTION: An original platen 6 is made of a transparent material, and includes a mounting surface onto which an original is mounted is provided to an upper surface. In a lower side of the original platen 6, a CIS unit having a plurality of light reception elements arranged to a main scanning direction is movably provided to a sub-scanning direction. In a top plate 5 of a housing 2 covering a circumference of the original platen 6, an opening 4 including a rear end edge 8 extended to the main scanning direction and a left end edge 9 extended to the sub-scanning direction is provided to a back surface 31 which is an opposite surface opposite to the CIS unit. The back surface 31 of the cover includes a coloring part 35 that is colored along the rear end edge 8, and is colored along the left end edge 9. The coloring part 35 and a circumference part of the coloring part 35 are read by the CIS unit, and from a reading result, a position of a reference point as an intersection point of the rear end edge 8 and the left end edge 9 is detected, and a reading range of the original is determined on the basis of the position of the reference point.SELECTED DRAWING: Figure 3

Description

Technical Field

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

Background Art

[0002] Conventionally, a reading device for reading a document by the FB (Flat Bed) method has been provided.

[0003] In an FB method reading device, a reading device for reading one line along the main scanning direction is provided so as to be reciprocally movable in the sub-scanning direction orthogonal to the main scanning direction below a document table made of transparent glass. When reading a document placed on the document table, the reading range by the reading device is determined, and while the reading device is moved in the sub-scanning direction within the reading range, the document on the document table is read line by line by the reading device.

[0004] Before determining the reading range, an origin position serving as a reference when determining the reading range is detected. For example, a black-and-white pattern in which a white area and a black area are adjacent in the main scanning direction and the sub-scanning direction is provided on the lower surface of a cover surrounding the periphery of the document table, and the black-and-white pattern is read by the reading device. Then, from the reading result of the black-and-white pattern, the position of the intersection of the boundary line between the white area and the black area adjacent in the main scanning direction and the boundary line between the white area and the black area adjacent in the sub-scanning direction is detected as the origin position.

[0005] In a configuration in which the black-and-white pattern is formed of a tape having white and black areas, the tape is manually attached to the lower surface of the cover. Therefore, the tape may be attached while being displaced from the normal position, and in that case, the origin position is displaced from the designed position. If the origin position is displaced from the designed position, the reading range is not correctly determined.

[0006] Therefore, a method has been proposed in which a recess is provided on the underside of the cover, having edges (edges) aligned with the main scanning direction and the sub-scanning direction, and the recess and its surrounding area are read by a reading device. From the reading results, the positions of the edges of the recess aligned with the main scanning direction and the edges aligned with the sub-scanning direction are detected, and the reading range, which is determined based on the origin position, is corrected according to the reference position (see, for example, Patent Document 1). Since the recess is created during the molding of the cover, there is almost no variation in the reference position between products. Therefore, the reading range can be corrected with high accuracy. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2021-164077 [Overview of the project] [Problems that the invention aims to solve]

[0008] However, if the cover is a dark color such as black, there may be little difference between the amount of reflected light in the recess and the amount of reflected light in the surrounding area, making it difficult to accurately detect the position of the edge of the recess, and thus potentially preventing accurate correction of the reading range.

[0009] The object of the present invention is to provide a reading device that can accurately determine the reading range by the reading device. [Means for solving the problem]

[0010] To achieve the above objective, a reading device according to one aspect of the present invention comprises a document tray made of a transparent material and having a mounting surface on which a document is placed, a cover that covers the periphery of the document tray from the mounting surface side, a reading unit having a plurality of light-receiving elements arranged in a main scanning direction parallel to the mounting surface on the side of the document tray opposite to the mounting surface, and movable in a sub-scanning direction parallel to the mounting surface and perpendicular to the main scanning direction, and reading the document by receiving light reflected from the document to be read with the light-receiving elements, and a control unit, the cover is a reading unit The device has a reference section on the opposite surface facing the section, which has a first edge extending in the sub-scanning direction and a second edge extending in the main scanning direction, and a colored section around the reference section which is colored along the first edge and along the second edge. The control unit causes the reading unit to read the colored section and the surrounding area of ​​the colored section, detects a first position of the first edge in the main scanning direction and a second position of the second edge in the sub-scanning direction from the reading results, and determines the reading range of the document by the reading unit based on the first and second positions.

[0011] In this configuration, the document tray is made of a transparent material and has a surface on which the document is placed. On the side of the document tray opposite to the surface on which the document is placed, a reading unit is provided that has multiple light-receiving elements arranged in the main scanning direction and is movable in the sub-scanning direction. The cover that surrounds the document tray from the surface on which the document is placed has a reference section on the side facing the reading unit, which has a first edge extending in the sub-scanning direction and a second edge extending in the main scanning direction. The side facing the cover has a colored portion that is colored along the first edge and colored along the second edge. As a result, the reflectivity of the colored portion and the portion adjacent to the colored portion are different.

[0012] To determine the reading range of the document by the reading unit, the reading unit reads the colored portion and the surrounding portion of the colored portion. From the reading results, a first position in the main scanning direction of the first edge and a second position in the sub-scanning direction of the second edge are detected. Since the reflectivity of the colored portion and the portion adjacent to the colored portion are different, the first and second positions can be accurately detected from the reading results of the colored portion and the surrounding portion of the colored portion. As a result, the reading range of the document can be accurately determined by the reading unit based on the first and second positions.

[0013] A reading device according to another aspect of the present invention comprises a document tray made of a transparent material and having a mounting surface on which a document is placed; a cover that covers the peripheral part of the document tray from the mounting surface side; and a reading unit that is movable in a sub-scanning direction parallel to the mounting surface and perpendicular to the main scanning direction, and has a plurality of light-receiving elements arranged in a main scanning direction parallel to the mounting surface on the side of the document tray opposite to the mounting surface, and reads the document to be read by receiving light reflected from the document to be read with the light-receiving elements, the cover having a reference portion on the opposing surface facing the reading unit that has a first edge extending in the sub-scanning direction and a second edge extending in the main scanning direction, and a colored portion around the reference portion that is colored along the first edge and colored with a different color from the cover along the second edge.

[0014] In this reading device, the colored portion and the portion surrounding the colored portion are read by the reading unit, and the first position in the main scanning direction of the first edge and the second position in the sub-scanning direction of the second edge are detected from the reading result. This allows for accurate detection of the first and second positions, similar to a reading device relating to one aspect of the present invention. As a result, the reading range of the document by the reading unit can be accurately determined based on the first and second positions. [Effects of the Invention]

[0015] According to the present invention, the reading range by the reading device can be determined effectively. [Brief explanation of the drawing]

[0016] [Figure 1]It is a perspective view of a reading device according to an embodiment of the present invention. [Figure 2] It is a cross-sectional view schematically showing the internal configuration of the reading device. [Figure 3] It is a view of the top plate of the housing of the reading device and the document table seen from below. [Figure 4] It is a block diagram showing the electrical configuration of the reading device. [Figure 5] It is a diagram for explaining the deviation of the detected home position with respect to the design home position. [Figure 6] It is a flowchart showing the flow of correction value acquisition processing. [Figure 7] It is a diagram for explaining the search for a reference point. [Figure 8] It is a flowchart showing the flow of reading range determination processing. [Figure 9] It is a diagram for explaining the search for a reference point in a configuration where the colored portion is colored with a color.

Embodiments for Carrying Out the Invention

[0017] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0018] <Configuration of the Reading Device> The reading device 1 shown in FIG. 1 is a device that reads a document by the FB (Flatbed) method. The reading device 1 may be used, for example, in a multi-function peripheral (MFP) having a plurality of functions such as a reading function and a printing function together with a printing device (not shown) that prints an image related to image data on a paper. In this case, the reading device 1 is arranged stacked on the printing device.

[0019] The scanner 1 comprises a roughly rectangular prism-shaped housing 2 and a document cover 3 that opens and closes the top surface of the housing 2. The document cover 3 is pivotably mounted on an axis extending along one end edge of the housing 2. By pivoting, the document cover 3 opens and closes between a state in which it is lifted relative to the top surface of the housing 2, opening the top surface of the housing 2, and a state in which it is lowered relative to the top surface of the housing 2, covering the top surface of the housing 2.

[0020] In the reading device 1, the side of the document cover 3 with its pivot axis is the rear side, and the opposite side is the front side. For the purposes of the following explanation, the front, back, left, and right directions of the reading device 1 are defined based on how it looks when viewed from the front. The up and down directions are defined with the reading device 1 installed on a horizontal plane.

[0021] The top panel 5 of the housing 2 has a rectangular opening 4 with edges extending in the front-to-back and left-to-right directions. Inside the housing 2, a document tray 6 made of transparent glass is provided to close the opening 4 from below. The top panel 5 is an example of a cover, covering the periphery of the document tray 6 from above and supporting its edges. Note that the document tray 6 is not limited to a glass plate; it may be made of a transparent plate other than glass, such as a transparent resin plate.

[0022] The upper surface of the document tray 6 is formed as a flat surface 7 on which the document is placed. On the surface 7, a rectangular area exposed from the opening 4 is set as the document placement area, and the document is positioned so that one corner is aligned with the left rear corner where the rear edge 8 and left edge 9 of the opening 4 intersect, and is in contact with the rear edge 8 and left edge 9.

[0023] As shown in Figure 2, a CIS (Contact Image Sensor) unit 11 (an example of a reading unit) and a moving mechanism 12 are provided on the underside of the document tray 6.

[0024] The CIS unit 11 incorporates a light source 21, a rod lens array 22, and an image sensor 23. The light source 21 includes three LEDs (Light Emitting Diodes) of R (red), G (green), and B (blue). The illumination of the light source 21 is controlled by pulse width modulation. The rod lens array 22 comprises a number of rod lenses aligned in the main scanning direction. The main scanning direction coincides with the front-to-back direction. The rod lenses are refractive index distribution type lenses with effective 1:1 magnification. The image sensor 23 is, for example, a linear image sensor with a configuration in which multiple photodetectors are arranged at equal pitch in the main scanning direction.

[0025] Light from the light source 21 is reflected from the surface of the object to be read, such as a document, on the document table 6, and the reflected light passes through the rod lens array 22 and enters the image sensor 23. When light enters the image sensor 23, each light-receiving element of the image sensor 23 outputs a voltage through photoelectric conversion. The voltage output from each light-receiving element is amplified by the gain adjustment circuit and then converted into a digital pixel value by the A / D conversion circuit. The A / D conversion circuit has, for example, an 8-bit (0 to 255) resolution and converts the voltage (electrical signal) output from the image sensor 23 into a digital pixel value for each RGB color. For example, voltages below the lower limit reference voltage (lower limit value) are uniformly converted to "0", voltages above the upper limit reference voltage (upper limit value) are uniformly converted to "255", and voltages within the range from the lower limit value to the upper limit value are converted into a pixel value according to the magnitude of the voltage. The voltage output from each light-receiving element is converted into a pixel value, thereby enabling the CIS unit 11 to read one line of the object to be read in the main scanning direction.

[0026] The moving mechanism 12 is a mechanism that moves the CIS unit 11 in a sub-scanning direction perpendicular to the main scanning direction. The sub-scanning direction coincides with the left-right direction. The moving mechanism 12 comprises a carriage 24 that supports the CIS unit 11, a motor 25 consisting of a stepping motor that can rotate in both forward and reverse directions, a drive pulley 26 that is rotationally driven by the motor 25, a driven pulley 27 that is paired with the drive pulley 26, and a belt 28 wrapped around the drive pulley 26 and the driven pulley 27. The drive pulley 26 is positioned at the right end of the housing 2 so that its axis of rotation extends in the front-rear direction. The driven pulley 27 is positioned at the left end of the housing 2 so that its axis of rotation extends in the front-rear direction at the same height as the axis of rotation of the drive pulley 26. The carriage 24 is attached to the belt 28. The rotation of the drive pulley 26 causes the belt 28 to move, and as the belt 28 moves, the carriage 24 moves along a guide mechanism (not shown) in a sub-scanning direction that coincides with the left-right direction.

[0027] When scanning a document, the document cover 3 is positioned in the open position, and the document is placed on the mounting surface 7 of the document table 6. After the document is placed on the document table 6, the document cover 3 is closed, and the back of the document is covered from above by the document cover 3. A document holder 29 made of a sheet of white resin is elastically supported on the inner surface of the document cover 3. The document holder 29 is roughly rectangular in shape, smaller than the opening 4, specifically, it is a rectangle with rounded corners. When the document cover 3 is closed, the document holder 29 does not ride up on the periphery of the opening 4 of the housing 2, but is positioned within the opening 4 with a gap between it and the corner edges of the opening 4, and presses the document against the document table 6.

[0028] After the document is placed on the placement surface 7, when the reading device 1 receives an instruction to start reading, the reading range for the CIS unit 11 is determined. Then, the CIS unit 11 is moved by the movement mechanism 12 from left to right in the sub-scanning direction, and in synchronization with this movement, the CIS unit 11 reads the document line by line.

[0029] <Black and white pattern> To determine the reading range by the CIS unit 11, a black and white pattern 32 is provided on the back surface 31 of the top plate 5 of the housing 2, which faces the CIS unit 11, at a distance from the left edge 9 of the opening 4, as shown in Figure 3. The black and white pattern 32 is formed as a rectangular tape and is attached to the back surface 31 of the top plate 5 of the housing 2 so as to extend in the front-to-back direction, which coincides with the main scanning direction. In the black and white pattern 32, the rectangular areas at the front right and rear right corners are designated as black areas 33, and the remaining area is designated as a white area 34. As a result, in the area along the right edge of the black and white pattern 32, the white area 34 is sandwiched between two black areas 33, and each black area 33 and white area 34 are continuous. In the area along the front edge and the area along the rear edge, the white area 34 is adjacent to the left of the black area 33, and the black area 33 and white area 34 are continuous.

[0030] <Colored part> Furthermore, the casing 2 and the document cover 3 are made of black resin. Therefore, the color of the underside 31 of the top panel 5 of the casing 2 is black, and in Figure 3, the black color of the underside 31 is indicated by hatching. Also, the color of the surface of the document cover 3 that faces the document tray 6 is black.

[0031] On the back surface 31, a colored portion 35 is provided adjacent to the left rear corner of the opening 4. The colored portion 35 is formed by coloring the back surface 31 white along the rear edge 8 (an example of a first edge) and the left edge 9 (an example of a second edge) of the opening 4, which are examples of reference portions. More specifically, the colored portion 35 has an L-shape, consisting of a first portion 41 formed by coloring a rectangular area along the rear edge 8 of the opening 4 white, a second portion 42 formed by coloring a rectangular area along the left edge 9 of the opening 4 white, and a third portion 43 formed by coloring a rectangular area connecting the first portion 41 and the second portion 42 white. The method for forming the colored portion 35 is, for example, a printing method such as silk screen printing or pad printing.

[0032] <Electrical Configuration> As shown in Figure 4, the reader device 1 includes a CPU (Central Processing Unit) 51, a non-volatile memory 52 (an example of a storage unit) such as flash memory or E2PROM that can be rewritten, and a volatile memory 53 such as SDRAM. The CPU 51, non-volatile memory 52, and volatile memory 53 are connected to a bus 54 for data communication.

[0033] The CPU 51 (an example of a control unit) controls each part of the reader 1, including the CIS unit 11 and the moving mechanism 12, by executing programs for various processes. The non-volatile memory 52 stores programs executed by the CPU 51 and various data. The volatile memory 53 is used as a work area when the CPU 51 executes programs.

[0034] <Correction value acquisition process> The reading range by the CIS unit 11 is represented by coordinates in a Cartesian coordinate system, as shown in Figure 5. The coordinate origin is the home position HP, which is the left front corner of the black region 33 at the rear of the black and white pattern 32, i.e., the intersection of the boundary lines BL1 and BL2 between the rear black region 33 and the white region 34. The direction from rear to front in the main scanning direction is defined as the positive direction of the X axis, and the direction from left to right in the sub-scanning direction is defined as the positive direction of the Y axis.

[0035] The black and white pattern 32 is manually attached to the underside 31 of the top panel 5 of the housing 2. As a result, the black and white pattern 32 may be attached off-center from its correct position, causing the home position HP to deviate from the designed home position HPR. The reading range by the CIS unit 11 is set to a range with a predetermined length in the main scanning direction (X direction) and sub-scanning direction (Y direction) from the reading start point SP, which is the intersection of the rear edge 8 and the left edge 9 of the opening 4 formed in the top panel 5 of the housing 2. Since the opening 4 is formed during the resin molding of the housing 2 (top panel 5), it does not deviate significantly from its designed position. Therefore, the positional relationship between the designed home position HPR and the reading start point SP is constant. Consequently, if the home position HP coincides with the designed home position HPR, the CPU 51 can accurately determine the coordinates of the reading start point SP with the home position HP as the coordinate origin from the positional relationship between the designed home position HPR and the reading start point SP, and accurately determine the reading range by the CIS unit 11. However, if the home position HP deviates from the designed home position HPR, the CPU 51 cannot accurately determine the coordinates of the reading start point SP with the home position HP as the coordinate origin from the positional relationship between the designed home position HPR and the reading start point SP, and the reading range by the CIS unit 11 cannot be accurately determined. In order for the reading range to be accurately determined, the amount of deviation (ΔX, ΔY) of the home position HP from the designed home position HPR needs to be obtained as a correction value.

[0036] For example, before the reading device 1 leaves the factory, the CPU 51 performs a correction value acquisition process to obtain correction values ​​(ΔX, ΔY).

[0037] The flow of the correction value acquisition process is shown in Figure 6. In the correction value acquisition process, the CPU 51 detects the home position HP (S11). In detecting the home position HP, the CPU 51 causes the CIS unit 11 to read the grayscale pattern 32. From the image read by the CIS unit 11, the CPU 51 searches for a position where the pixel values ​​of adjacent pixels in the X direction (main scanning direction) change across the grayscale determination threshold. When a corresponding position is found, the CPU 51 determines that this position is the position of boundary line BL1 in the main scanning direction (an example of the fourth position). The CPU 51 also searches for a position where the pixel values ​​of adjacent pixels in the Y direction (sub-scanning direction) change across the grayscale determination threshold. When a corresponding position is found, the CPU 51 determines that this position is the position of boundary line BL2 in the sub-scanning direction (an example of the third position). This achieves the detection of the home position HP, which is the intersection of boundary lines BL1 and BL2. The CPU 51 then sets up an XY Cartesian coordinate system with the home position HP as the coordinate origin.

[0038] The CPU 51 causes the CIS unit 11 to read a predetermined target area and stores the data of the read image read by the CIS unit 11 in the volatile memory 53 (S12). The target area is set to include the colored portion 35 and its surrounding area.

[0039] As shown in Figure 7, the CPU 51 sets the intersection of the rear edge 8 and the left edge 9 of the opening 4 formed in the top plate 5 of the housing 2 as the reference point KP, and detects the reference point KP from the data of the read image of the target area stored in the volatile memory 53 (S13).

[0040] Specifically, the CPU 51 detects the X-coordinate (position in the X-direction) of the rear edge 8 of the aperture 4. It sets a rectangular search range that includes the portion of the rear edge 8 facing the R-surface 61 of the left rear corner of the document holder 29, and sets the search origin TG1 at a position within this search range, spaced on the negative side of the X-axis relative to the rear edge 8. The CPU 51 then sequentially checks the pixel values ​​of each RGB color of each pixel that are continuous on the positive side of the X-axis from the search origin TG1. For each pixel, it converts the pixel value of each color to a Y-component (luminance) value according to a predetermined conversion formula. For example, the CPU 51 converts the pixel values ​​of each RGB color to Y-component values ​​by adding the R-color pixel value multiplied by 0.299, the G-color pixel value multiplied by 0.587, and the B-color pixel value multiplied by 0.114.

[0041] The CPU 51 determines whether the Y component value of each pixel is greater than a threshold. Since the first portion 41 of the colored portion 35 is colored white, the Y component value of each pixel obtained by the CIS unit 11 reading the first portion 41 is greater than the threshold. On the other hand, a gap is always created between the rear edge 8 of the aperture 4 and the R surface 61 of the document holder 29, and since the document cover 3 is made of black resin, reflected light does not enter the light-receiving element of the CIS unit 11 that is facing the gap. Therefore, the Y component value of each pixel obtained by the CIS unit 11 reading the gap between the rear edge 8 and the R surface 61 is less than or equal to the threshold. When the CPU 51 first finds a pixel whose Y component value is less than or equal to the threshold, it determines that pixel to be a candidate pixel of the rear edge 8.

[0042] The CPU 51 shifts its position by a predetermined distance in the positive direction of the Y-axis from the search origin TG1, and repeatedly determines candidate pixels for the trailing edge 8. As a result, the CPU 51 determines multiple candidate pixels for the trailing edge 8. Then, the CPU 51 detects the average value of the X coordinates of the multiple candidate pixels for the trailing edge 8 as the X coordinate of the trailing edge 8 (an example of the first position), that is, the X coordinate of the reference point KP.

[0043] Furthermore, in order to detect the Y coordinate (position in the Y direction) of the left edge 9 of the aperture 4, the CPU 51 sets a rectangular area as the search range, which includes the portion of the left rear corner of the document holder 29 facing the R surface 61, and sets the search origin TG2 at a position within that search range that is spaced on the negative side of the Y axis relative to the rear edge 8. Then, the CPU 51 sequentially checks the pixel values ​​of each pixel that is continuous on the positive side of the Y axis from the search origin TG2, and for each pixel, converts the pixel value of each color to the value of the Y component (luminance) according to a predetermined conversion formula. The conversion formula is the same as the conversion formula used to detect the X coordinate of the reference point KP.

[0044] The CPU 51 determines whether the Y component value of each pixel is greater than a threshold. Since the second portion 42 of the colored portion 35 is colored white, the Y component value of each pixel obtained by the CIS unit 11 reading the second portion 42 is greater than the threshold. On the other hand, a gap always occurs between the left edge 9 of the aperture 4 and the R surface 61 of the document holder 29, and since the document cover 3 is made of black resin, reflected light does not enter the light-receiving element of the CIS unit 11 that is facing the gap. Therefore, the Y component value of each pixel obtained by the CIS unit 11 reading the gap between the left edge 9 and the R surface 61 is less than or equal to the threshold. When the CPU 51 first finds a pixel whose Y component value is less than or equal to the threshold, it determines that pixel to be a candidate pixel for the left edge 9.

[0045] The CPU 51 shifts its position by a predetermined distance in the positive direction of the X-axis from the search origin TG2, and repeatedly determines candidate pixels for the left edge 9. As a result, the CPU 51 determines multiple candidate pixels for the left edge 9. Then, the CPU 51 detects the average of the Y coordinates of the multiple candidate pixels for the left edge 9 as the Y coordinate of the left edge 9, that is, the Y coordinate of the reference point KP.

[0046] Subsequently, the CPU 51 subtracts the X-coordinate of the design reference point KP from the X-coordinate of the detected reference point KP, and determines the resulting value as the correction value ΔX in the X direction (S14). The CPU 51 also subtracts the Y-coordinate of the design reference point KP from the Y-coordinate of the detected reference point KP, and determines the resulting value as the correction value ΔY in the Y direction (S14). The X and Y coordinates of the design reference point KP are the X and Y coordinates of the reference point KP in an XY Cartesian coordinate system with the design home position HPR as the coordinate origin, respectively, and are known and stored in the non-volatile memory 52. ​​The CPU 51 stores the determined correction values ​​(ΔX, ΔY) in the non-volatile memory 52.

[0047] <Reading range determination process> When a reading start command is input to the reading device 1, the CPU 51 performs the reading range determination process shown in Figure 8 to determine the reading range by the CIS unit 11.

[0048] In the reading range determination process, the CPU 51 reads the X and Y coordinates of the designed reading start point SP from the non-volatile memory 52. ​​The X and Y coordinates of the designed reading start point SP are the same as the X and Y coordinates of the reference point KP, respectively, and are stored in the non-volatile memory 52. ​​The CPU 51 also reads the correction values ​​(ΔX, ΔY) from the non-volatile memory 52. ​​The CPU 51 then determines the X coordinate of the reading start point SP by adding the correction value ΔX to the X coordinate of the designed reading start point SP, and determines the Y coordinate of the reading start point SP by adding the correction value ΔY to the Y coordinate of the designed reading start point SP (S21).

[0049] Subsequently, the CPU 51 determines the reading range to be a range having a predetermined length in both the main scanning direction and the sub-scanning direction from the reading start point SP (S22).

[0050] <Effects> As described above, the document tray 6 is made of a transparent material and has a mounting surface 7 on which a document is placed. On the side of the document tray 6 opposite to the mounting surface 7, a CIS unit 11 having a plurality of light-receiving elements arranged in the main scanning direction is provided so as to be movable in the sub-scanning direction. The top plate 5 of the housing 2 that covers the periphery of the document tray 6 from the mounting surface 7 side has an opening 4 on its back surface 31, which is the surface facing the CIS unit 11, having a rear edge 8 extending in the main scanning direction and a left edge 9 extending in the sub-scanning direction. The back surface 31 of the top plate 5 has a colored portion 35 that is colored along the rear edge 8 and along the left edge 9. As a result, the reflectivity of the colored portion 35 is different from that of the portion adjacent to the colored portion 35.

[0051] In order to determine the reading range of the document by the CIS unit 11, the black and white pattern 32 is read by the CIS unit 11. Then, from the reading result, the position of the boundary line BL1 between adjacent black areas 33 and white areas 34 in the main scanning direction and the position of the boundary line BL2 between adjacent black areas 33 and white areas 34 in the sub-scanning direction are detected.

[0052] Furthermore, the CIS unit 11 reads the colored portion 35 and the surrounding portion of the colored portion 35. An XY Cartesian coordinate system is then set with the home position HP, located at the positions of boundary line BL1 and boundary line BL2, as the coordinate origin. From the reading results, the X coordinate representing the position of the rear edge 8 in the main scanning direction and the Y coordinate representing the position of the left edge 9 in the sub-scanning direction are detected. Since the reflectivity of the colored portion 35 and the portion adjacent to the colored portion 35 are different, the X coordinate of the rear edge 8 and the Y coordinate of the left edge 9, that is, the X and Y coordinates of the reference point KP, which is the intersection of the rear edge 8 and the left edge 9, can be detected with high accuracy from the reading results of the colored portion 35 and the surrounding portion of the colored portion 35.

[0053] The X-coordinate of the detected reference point KP is subtracted from the X-coordinate of the design reference point KP, and the resulting value is determined as the correction value ΔX in the X direction. Similarly, the Y-coordinate of the design reference point KP is subtracted from the Y-coordinate of the detected reference point KP, and the resulting value is determined as the correction value ΔY in the Y direction. Then, the X-coordinate of the design reading start point SP is determined by adding the correction value ΔX to the X-coordinate of the design reading start point SP, and the Y-coordinate of the design reading start point SP is determined by adding the correction value ΔY to the Y-coordinate of the design reading start point SP. The reading range of the document by the CIS unit 11 is determined to be a range having a predetermined length from the reading start point SP in both the main scanning direction and the sub-scanning direction.

[0054] Since the X and Y coordinates of the reference point KP can be detected with high accuracy, the reading range of the document by the CIS unit 11 can be accurately determined based on the X and Y coordinates of the reference point KP.

[0055] <Variation> Although one embodiment of the present invention has been described above, the present invention can also be implemented in other forms.

[0056] For example, in the embodiment described above, the color of the back surface 31 of the top plate 5 of the housing 2 was black, the color of the document holder 29 was white, and the colored portion 35 was the same white as the document holder 29. However, the color of the colored portion 35 does not have to be the same white as the document holder 29, as long as it is a different color from the color of the back surface 31.

[0057] If the colored portion 35 is colored with a color other than white or black, when detecting the X coordinate of the reference point KP, the search area is defined as a rectangular area including the R-surface 61 of the left rear corner of the document holder 29 at the rear edge 8, and the portion that extends linearly to the right from that R-surface 61, as shown in Figure 9.

[0058] The CPU 51 sequentially checks the pixel values ​​of each RGB color at each pixel that is continuous on the positive side of the X-axis from the search origin TG1, and for each pixel, converts the pixel value of each color to the Cb component (chrominance) value and the Cr component (chrominance) value according to a predetermined conversion formula. For example, the CPU 51 converts the pixel values ​​of each RGB color to the Cb component value by adding the value obtained by multiplying the R color pixel value by -0.16874, the G color pixel value by -0.33126, and the B color pixel value by 0.50000. It also converts the pixel values ​​of each RGB color to the Cr component value by adding the value obtained by multiplying the R color pixel value by 0.50000, the G color pixel value by -0.41869, and the B color pixel value by -0081. The CPU 51 adds the squared values ​​of the Cb component and the Cr component, and takes the square root of the sum as the absolute values ​​of the Cb and Cr components. Then, when the CPU 51 first finds a pixel in which the absolute values ​​of the Cb and Cr components are less than or equal to a threshold, it determines that pixel to be a candidate pixel for the trailing edge 8.

[0059] Furthermore, when detecting the Y coordinate of the reference point KP, the search range is defined as a rectangular area including the R-surface 61 at the left rear corner of the document holder 29 at the left edge 9, and the portion extending linearly forward from that R-surface 61, as well as the portion opposite to it. The CPU 51 sequentially checks the pixel values ​​of each pixel that is continuous on the positive side of the Y axis from the search origin TG2, and for each pixel, converts the pixel values ​​of each color to the values ​​of the Cb component (chrominance) and Cr component (chrominance) according to a predetermined conversion formula. The conversion formula is the same as the one used to detect the X coordinate of the reference point KP. Then, when the CPU 51 first finds a pixel whose absolute values ​​of the Cb component and Cr component are below a threshold, it determines that pixel to be a candidate pixel for the left edge 9.

[0060] The method for determining the X-coordinate of the reference point KP using the X-coordinate of the candidate pixel at the rear edge 8, and the method for determining the Y-coordinate of the reference point KP using the Y-coordinate of the candidate pixel at the left edge 9, is the same as the method described above.

[0061] Furthermore, in the above-described embodiment, the colored portion 35 was assumed to be L-shaped, having a first portion 41 formed by coloring a rectangular area along the rear edge 8 of the opening 4 white, a second portion 42 formed by coloring a rectangular area along the left edge 9 of the opening 4 white, and a third portion 43 formed by coloring a rectangular area connecting the first portion 41 and the second portion 42 white. The shape of the colored portion 35 is not limited to this. For example, the colored portion 35 may have a first portion 41 formed by coloring a rectangular area along the rear edge 8 of the opening 4 white, and a second portion 42 formed by coloring a rectangular area along the left edge 9 of the opening 4 white, with the first portion 41 and the second portion 42 not connected by the third portion 43.

[0062] In the embodiment described above, the CPU 51 is said to execute each process, but the reading device 1 may be provided with multiple CPUs, and the multiple CPUs may cooperate to execute each process.

[0063] Furthermore, various design modifications can be made to the aforementioned configuration within the scope of the matters described in the patent claims. [Explanation of symbols]

[0064] 1: Reader 4:Aperture 5: Top plate 6: Manuscript stand 7: Mounting surface 8: Rear edge 9: Left edge 11: CIS Unit 29: Manuscript holding 31: Back side 32: Black and white pattern 33: Black Area 34: White area 35: Colored part 51:CPU 52: Non-volatile memory BL1: Boundary Line BL2: Boundary line HP: Home Position KP: Reference point ΔX: Correction value ΔY: Correction value

Claims

1. A document tray made of transparent material and having a surface on which a document is placed, A cover that covers the area around the document tray from the side of the mounting surface described above, A reading unit is provided that has a plurality of light-receiving elements arranged in a main scanning direction parallel to the aforementioned surface on the side opposite to the aforementioned surface relative to the document table, and is movable in a sub-scanning direction parallel to the aforementioned surface and perpendicular to the main scanning direction, and receives light reflected from the object to be read with the light-receiving elements to read the object, Memory unit and, It comprises a control unit and, The cover has, on the surface facing the reading unit, a reference portion having a first edge extending in the sub-scanning direction and a second edge extending in the main scanning direction; a colored portion around the reference portion, which is colored along the first edge and along the second edge; and a black and white pattern provided spaced apart from the document glass in the sub-scanning direction, which has a white region and a black region adjacent to the white region in the sub-scanning direction. The white region is adjacent to the black region in the main scanning direction and the sub-scanning direction. The aforementioned storage unit stores the design coordinates of the reference point. The control unit, The reading unit is made to read the colored portion and the surrounding portion of the colored portion, and from the reading results, the first position of the first edge in the main scanning direction and the second position of the second edge in the sub-scanning direction are detected. The reading unit is made to read the black and white pattern, and from the reading result, the position of the boundary between the white region and the black region adjacent to each other in the sub-scanning direction is detected as the third position, and the fourth position of the boundary between the white region and the black region adjacent to each other in the main scanning direction is detected. A reading device that determines the reading range of the original document by the reading unit by using the point at the third and fourth position as the origin of the coordinates, determining the coordinates of the point at the first and second position, using the difference between the determined coordinates and the design coordinates of the reference point stored in the memory unit as a correction value, and correcting the reading range by the reading unit, which is set based on the position of the origin of the design coordinates, with the correction value.

2. A reading device according to claim 1, A reading device in which the colored portion is colored in a different color from the color of the opposing surface of the cover.

3. A reading device according to claim 2, The aforementioned colored portion is colored white. The color of the opposite surface of the cover is black in the reading device.

4. A reading device according to any one of claims 1 to 3, The first and second edges of the reference portion form part of an opening in the cover for exposing the front surface of the document holder of the reading device.

5. A reading device according to claim 4, The document holder is provided on the document surface side of the document tray and is displaceable between an open position that opens the document surface and a closed position that presses the document toward the document surface, The colored portion is colored the same color as the surface of the document holder that presses against the document. The control unit is a reading device that causes the reading unit to read the colored portion and the surrounding portion, with the area outside the document holder in the closed position on the document table being considered the surrounding portion.

6. A reading device according to claim 4, The document holder is provided on the document surface side of the document tray and is displaceable between an open position that opens the document surface and a closed position that presses the document toward the document surface, The colored portion is colored with a different color from the color of the surface of the document holder that presses against the document. The control unit is a reading device that causes the reading unit to read the colored portion and the surrounding portion, including at least the portion of the document holder facing the closed position on the document table in the peripheral portion.

7. A reading device according to claim 1, The first edge and the second edge of the reference portion intersect, A reading device in which the portion along the first edge and the portion along the second edge of the colored portion are connected to each other to form an L-shape.

Images