Image reading device, program, and image forming system

Abstract

This invention provides an image reading device, an image forming system, an image reading method, and a program that can more reliably adjust the tilt of the read image. [Solution] The image forming system 1 is composed of an image forming unit equipped with an image reading device 500. The image reading device 500 reads the image of the paper being transported by the reading transport unit 10 with the reading scanning unit 20 while it is being transported, and controls the reading control unit to read one mark or multiple marks from an adjustment chart on which a single mark or multiple marks having a hypotenuse that changes width in the main scanning direction or sub-scanning direction and is symmetrical with respect to the center line in the main scanning direction is formed, reading one or more pixels in the sub-scanning direction and pixels equal to the width of the adjustment chart at two or more locations in the sub-scanning direction with an interval between them in the sub-scanning direction, and pixels equal to the width of the adjustment chart in the main scanning direction. The reading control unit also includes a first calculation unit that calculates the inclination in the main scanning direction and a second calculation unit that calculates the inclination in the sub-scanning direction.

Description

Technical Field

[0001] The present invention relates to an image reading device, a program, and an image forming system.

Background Art

[0002] Generally, in an image reading device, the read image may be inclined or distorted due to various causes. Therefore, conventionally, as a method for measuring and adjusting the inclination of the read image, a method using an adjustment chart is known. For example, Patent Document 1 discloses a method using an adjustment chart in which a plurality of square marks are arranged such that each side of the square is parallel or perpendicular to the vertical and horizontal sides of the paper.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the method disclosed in Patent Document 1 above, it is possible to measure the amount of inclination caused by, for example, flatness deviation of the scan rail in the image reading device, frame distortion, etc. However, in this method, it is not possible to measure the amount of angular deviation between the document conveyance direction of the document conveyance device and the main scanning direction of the image reading device. Therefore, in the conventional method, there are cases where the inclination of the read image cannot be adjusted.

[0005] An object of the present invention is to provide an image reading device, a program, and an image forming system that can more reliably adjust the inclination of a read image in view of the above problems.

Means for Solving the Problems

[0006] To achieve the above object, the invention according to claim 1 is an image reading device, wherein The image of the paper being transported by the reading and transport unit is read by the reading and scanning unit while it is being transported. A reading control unit controls the reading of one mark or multiple marks having a hypotenuse that changes width in the main scanning direction or sub-scanning direction and is symmetrical with respect to the center line in the main scanning direction, from an adjustment chart on which such one mark or multiple marks having such hypotenuses are formed, by reading lines that are one or more pixels in the sub-scanning direction and the width of the adjustment chart in the main scanning direction, at two or more locations in the sub-scanning direction with spacing between them. A first calculation unit calculates the tilt in the main scanning direction from the difference in mark widths in one reading line read by the reading control unit, A second calculation unit calculates the inclination in the sub-scanning direction from the difference in the position or width of marks on two reading lines read at intervals in the sub-scanning direction, It is characterized by being equipped with [the following features].

[0007] The invention described in claim 2 is an image reading device described in claim 1, The system is characterized by comprising a third calculation unit that calculates the amount of angular deviation between the paper transport direction of the reading transport unit and the main scanning direction of the reading scan unit from the tilt of the main scanning direction calculated by the first calculation unit and the tilt of the sub-scanning direction calculated by the second calculation unit.

[0008] The invention described in claim 3 is an image reading device described in claim 2, The system is characterized by comprising a display control unit that displays the amount of angular displacement calculated by the third calculation unit on the display unit.

[0009] The invention described in claim 4 is an image reading device described in claim 3, The reading and transporting unit has an angle adjustment mechanism that adjusts the relative angle with respect to the main scanning direction of the reading and scanning unit. It has a fourth calculation unit that calculates an adjustment amount to make the angular displacement amount zero from the angular displacement amount calculated by the third calculation unit, The system is characterized by having a display control unit that displays on the display unit an adjustment amount to make the angular deviation amount calculated by the fourth calculation unit zero.

[0010] The invention described in claim 5 is an image reading device described in claim 1, The system is characterized by comprising a correction unit that corrects the tilt in the main scanning direction and the tilt in the sub-scanning direction of the image data read by the reading scanning unit from the paper transported by the reading transport unit, using the tilt in the main scanning direction calculated by the first calculation unit and the tilt in the sub-scanning direction calculated by the second calculation unit.

[0011] The invention described in claim 6 is a program for controlling the computer of an image reading device that reads an image of a sheet of paper being transported by a reading transport unit with a reading scanning unit while the paper is being transported, A reading control unit controls the computer to read one or more marks from an adjustment chart having multiple hypotenuses that are symmetrical with respect to the center line in the main scanning direction and whose width changes in the main scanning direction, at two or more locations in the sub-scanning direction with spacing between reading lines, where the reading line is one or more pixels in the sub-scanning direction and pixels equal to the width of the adjustment chart in the main scanning direction. A first calculation unit calculates the tilt in the main scanning direction from the difference in mark widths in one reading line read by the reading control unit. A second calculation unit calculates the inclination in the sub-scanning direction from the difference in the position or width of marks on two reading lines read at intervals in the sub-scanning direction. It is characterized by being designed to function as such.

[0012] The invention described in claim 7 relates to an image forming system, An image reading device according to any one of claims 1 to 5, An image forming unit that forms an image on paper using image data obtained by the image reading device, It is characterized by being equipped with [the following features]. [Effects of the Invention]

[0013] According to the present invention, the tilt of the read image can be adjusted more reliably. [Brief explanation of the drawing]

[0014] [Figure 1] It is an overall side sectional view of an image forming system. [Figure 2] It is a block diagram of an image forming system. [Figure 3] It is an example of an adjustment chart. [Figure 4] It is a diagram for explaining the calculation of the inclination during image reading using an adjustment chart. [Figure 5] It is a diagram showing the case where the original document to be read is normally conveyed. [Figure 6] It is a diagram showing the case where the original document to be read is conveyed in an inclined state. [Figure 7] It is a diagram showing an image read in an inclined state. [Figure 8] It is a perspective view showing the state where the reading conveyance unit of the image reading apparatus in FIG. 1 is opened. [Figure 9] It is a diagram for explaining the adjustment by the angle adjustment mechanism. [Figure 10] It is a diagram showing the correction by the correction unit. [Figure 11] It is a diagram showing an example of the display by the display unit. [Figure 12] It is a flowchart showing the angle adjustment process using an adjustment chart. [Figure 13] It is a flowchart showing the correction process by the correction unit. [Figure 14] It is a diagram showing a modified example of an adjustment chart.

Embodiments for Carrying Out the Invention

[0015] Hereinafter, an image forming system 1 according to an embodiment of the present invention will be described with reference to the drawings. However, the scope of the invention is not limited to the illustrated examples. In the following description, those having the same functions and configurations are denoted by the same reference numerals, and the description thereof is omitted.

[0016] (Image Forming System) Figure 1 is a schematic diagram showing the overall configuration of the image forming system 1. Figure 2 is a block diagram showing the main functional configuration of the image forming system 1. The image forming system 1 comprises a reading and transport unit 10, a reading and scanning unit 20, an operation and display unit 30, an image processing unit 40, an image forming unit 50, a paper transport unit 60, a fixing unit 70, a storage unit 80, a communication unit 90, and a control unit 100. Furthermore, the reading and transport unit 10, the reading and scanning unit 20, and the control unit 100 constitute the image reading device 500.

[0017] In the following, the X, Y, and Z directions refer to the directions shown in Figure 1.

[0018] (Reading and transporting unit) The reading and transport unit 10 is an automatic document feeder (ADF). The reading and transport unit 10 includes a paper feed tray 11 and paper feed rollers 12 for transporting documents D placed on the paper feed tray 11. The reading and transport unit 10 also includes contact rollers 13 for passing documents D through the platen glass 202, which is the reading area for documents, while keeping them in close contact, and guide rollers 14 for guiding the documents D transported by the paper feed rollers 12 along the contact rollers 13. The reading and transport unit 10 transports documents D placed on the paper feed tray 11 one by one to the reading area on the platen glass 202. The reading and transport unit 10 also includes transport rollers 15 for transporting documents D after scanning is complete, and an output tray 16 for discharging documents D. The reading and transport unit 10 transports documents D with its bottom surface in contact with the platen glass 202 of the reading and scanning unit 20. Furthermore, the reading and transporting unit 10 is rotatably connected to the housing of the image forming unit 50 by a hinge portion 19 (see Figure 8). Furthermore, the reading and transport unit 10 is equipped with an angle adjustment mechanism 17, which will be described later.

[0019] (Reading and scanning unit) The scanning unit 20 operates to read the image formed on the original document D. For example, a color slit-scan type scanner is used for the scanning unit 20. The scanning unit 20 is equipped with an array of image sensors 201. The scanning unit 20 performs the reading by reading the surface of the original document D and outputting an image reading signal when the original document D is inverted in a U-shape by the contact roller 13. For example, a 3-line color CCD (Charge Coupled Device) imaging device is used for the image sensor 201.

[0020] The image sensor 201 includes three reading sensors for detecting red (R), green (G), and blue (B) light, each composed of multiple photodetector arrays arranged in the main scanning direction. The reading unit 20 uses the image sensor 201 to simultaneously read R, G, and B color light information by dividing the pixels at different positions in the sub-scanning direction, which is orthogonal to the main scanning direction.

[0021] The original document D, scanned by the scanning unit 20, is transported by the transport roller 15 and ejected into the output tray 16.

[0022] The scanning unit 20 includes, in addition to the image sensor 201, a platen glass 202, a contact glass 203 (ADF glass), a light source 204, mirrors 205a, 205b, 205c, an imaging optical unit 206, and an optical drive unit (not shown). The light source operates to irradiate the original document D with light. The optical drive unit operates to move the original document D or the image sensor 201 relative to it in the sub-scanning direction. The sub-scanning direction is the direction perpendicular to the main scanning direction, when the arrangement direction of the multiple light-receiving elements constituting the image sensor 201 is defined as the main scanning direction. In Figure 1, the X direction is the main scanning direction, and the Y direction is the sub-scanning direction. In this way, the original document D placed on the paper feed tray 11 of the scanning transport unit 10 is transported by the aforementioned paper feed roller 12, contact roller 13, guide roller 14, and transport roller 15. Next, the optical system of the scanning unit 20 scans and exposes an image of one side of the original document D, and the incident light reflecting the image reading is read by the image sensor 201. The image sensor 201 converts the read incident light into photoelectric power according to the amount of light. The photoelectrically converted analog image reading signal is converted into digital original document image data via the control unit 100. The scanning unit 20 outputs the document image data obtained through the above process to the control unit 100.

[0023] (Operation display) The operation display unit 30 is composed of, for example, a liquid crystal display (LCD) with a touch panel. The operation display unit 30 functions as both an operation unit 31 and a display unit 32.

[0024] {Operation section} The operation unit 31 is equipped with various operation keys such as a numeric keypad and a start key. The operation unit 31 receives various input operations from the user and outputs operation signals to the control unit 100.

[0025] {Display section} The display unit 32 displays various operation screens, image status displays, or the operating status of each function, etc., in accordance with the display control signals input from the control unit 100.

[0026] (Image processing unit) The image processing unit 40 includes circuits and other components that perform digital image processing on the input image data according to initial settings or user settings. For example, under the control of the control unit 100, the image processing unit 40 performs gradation correction based on gradation correction data (gradation correction table). The image processing unit 40 also applies various correction processes such as color correction and shading correction, as well as compression processing, to the image data. The image data that has undergone these processes is input to the image forming unit 50.

[0027] (Image forming section) The image forming unit 50 includes image forming units 51Y, 51M, 51C, 51K and an intermediate transfer unit, etc.

[0028] {Image forming unit} The image forming units 51Y, 51M, 51C, and 51K form images using colored toners for the Y, M, C, and K components based on the input image data. The image forming units 51Y, 51M, 51C, and 51K have similar configurations. Therefore, for the convenience of illustration and explanation, common components are indicated by the same reference numeral, and when distinguishing them, Y, M, C, or K is added to the reference numeral. In Figure 1, only the components of the image forming unit 51Y for the Y component are labeled. Reference numerals are omitted for the components of the other image forming units 51M, 51C, and 51K.

[0029] The image forming unit 51 includes an exposure device 511, a developing device 512, a photoreceptor drum 513, a charging device 514, and a drum cleaning device 515, etc. Each device constituting the image forming unit 51 has the X direction as its axial direction.

[0030] [Exposure equipment] The exposure apparatus 511 is composed of, for example, a semiconductor laser. The exposure apparatus 511 scans and exposes a charged photoreceptor drum 513 to form a latent image.

[0031] [Developing equipment] The developing device 512 is a two-component developing device. The developing device 512 visualizes the electrostatic latent image by depositing toner of each color component onto the surface of the photoreceptor drum 513 to form a toner image. The developing roller 512A of the developing device 512 carries the developer while rotating and supplies the toner contained in the developer to the photoreceptor drum 513, thereby forming a toner image on the surface of the photoreceptor drum 513.

[0032] [Photoconductor drum] The photoreceptor drum 513 is, for example, an aluminum conductive cylindrical body (aluminum tube) with a drum diameter of 80 mm. The photoreceptor drum 513 is a negatively charged organic photoconductor (OPC). The photoreceptor drum 513 has three types of layers sequentially laminated on its circumferential surface. These three types of layers are the undercoat layer (UCL), the charge generation layer (CGL), and the charge transport layer (CTL).

[0033] The control unit 100 rotates the photoreceptor drum 513 at a constant peripheral speed by controlling the drive current supplied to a drive motor (not shown) that rotates the photoreceptor drum 513.

[0034] [Charging device] The charging device 514 uniformly charges the surface of the photoconductive photoreceptor drum 513 to a negative polarity.

[0035] [Drum cleaning device] The drum cleaning device 515 includes a drum cleaning blade and a lubricant application brush 515A, etc. The drum cleaning device 515 removes residual toner remaining on the surface of the photoreceptor drum 513 after primary transfer. The drum cleaning blade is slid against the surface of the photoreceptor drum 513. The lubricant application brush 515A applies lubricant to the photoreceptor drum 513 in order to improve the release properties between the photoreceptor drum 513 and the toner and to suppress the reduction of the photoreceptor film thickness.

[0036] (Intermediate transfer unit) The intermediate transfer unit 52 includes an intermediate transfer belt 521, a primary transfer roller 522, a plurality of support rollers 523, a secondary transfer roller 524, and a belt cleaning device 526, etc.

[0037] [Intermediate transfer belt] The intermediate transfer belt 521 is an endless belt and is stretched in a loop shape over a plurality of support rollers 523. At least one of the plurality of support rollers 523 is a drive roller, and the others are driven rollers. In particular, it is preferable that the roller 523A, which is located downstream in the belt travel direction from the primary transfer roller 522 for the K component, is a drive roller. This makes it easier to maintain a constant belt travel speed in the primary transfer section. As the drive roller 523A rotates, the intermediate transfer belt 521 travels at a constant speed in the direction of arrow W.

[0038] [Primary Transfer Roller] The primary transfer roller 522 is positioned on the inner circumferential side of the intermediate transfer belt 521, facing the photoreceptor drum 513 for each color component. By pressing the primary transfer roller 522 against the photoreceptor drum 513 with the intermediate transfer belt 521 in between, a primary transfer nip is formed for transferring the toner image from the photoreceptor drum 513 to the intermediate transfer belt 521.

[0039] [Secondary transfer roller] The secondary transfer roller 524 is positioned on the outer circumferential surface side of the intermediate transfer belt 521, opposite the backup roller 523B which is located downstream of the drive roller 523A in the belt travel direction. By pressing the secondary transfer roller 524 against the backup roller 523B with the intermediate transfer belt 521 in between, a secondary transfer nip is formed for transferring the toner image from the intermediate transfer belt 521 to the paper S.

[0040] As the intermediate transfer belt 521 passes over the primary transfer nip, the toner image on the photoreceptor drum 513 is sequentially transferred onto the intermediate transfer belt 521. Specifically, a primary transfer bias is applied to the primary transfer roller 522, and a charge of the opposite polarity to the toner is applied to the back side of the intermediate transfer belt 521. Through this operation, the toner image is electrostatically transferred to the intermediate transfer belt 521.

[0041] Subsequently, as the paper S passes through the secondary transfer nip, the toner image on the intermediate transfer belt 521 is transferred to the paper S. Specifically, a secondary transfer bias is applied to the secondary transfer roller 524, and a charge with the opposite polarity to the toner is applied to the back side of the paper S, thereby electrostatically transferring the toner image to the paper S. The paper S, on which the toner image has been transferred, is then transported toward the fuser unit 70.

[0042] [Belt cleaning device] The belt cleaning device 526 has a belt cleaning blade or the like that slides against the surface of the intermediate transfer belt 521, and removes any remaining transfer toner on the surface of the intermediate transfer belt 521 after secondary transfer. Alternatively, instead of a secondary transfer roller, a so-called belt-type secondary transfer unit may be used, in which the secondary transfer belt is stretched in a loop between a plurality of support rollers including a secondary transfer roller.

[0043] (Paper transport section) The paper transport unit 60 includes a paper feeding unit 61, a paper discharge unit 62, and a transport path unit 63, etc. The three paper feeding tray units 61a to 61c that make up the paper feeding unit 61 contain paper S (standard paper, special paper, etc.) identified based on basis weight, size, etc., according to pre-set types. The transport path unit 63 has multiple transport roller pairs, such as registration roller pairs 63a.

[0044] The paper sheets S stored in the paper feed tray units 61a to 61c are fed out one sheet at a time from the top and transported to the image forming unit 50 by the transport path unit 63. At this time, the registration roller unit, where the registration roller pair 63a is arranged, corrects the tilt of the fed paper sheets S and adjusts the transport timing. Then, in the image forming unit 50, the toner image from the intermediate transfer belt 521 is transferred to one side of the paper sheets S all at once, and a fixing process is performed in the fixing unit 70. The image formed paper sheets S are then discharged from the machine by the paper discharge unit 62, which is equipped with a paper discharge roller 62a.

[0045] (Fixing part) The fixing unit 70 heats and pressurizes the paper S, which has been transported with the toner image secondarily transferred to it, using a fixing nip to fix the toner image to the paper S.

[0046] (Storage part) The storage unit 80 is composed of, for example, a non-volatile semiconductor memory such as so-called flash memory or a hard disk drive. The storage unit 80 stores various data, including various setting information related to the image forming unit 50.

[0047] (Communications Department) The communication unit 90 is composed of, for example, a communication control card such as a LAN (Local Area Network) card. The communication unit 90 transmits and receives various types of data to and from external devices, such as personal computers, that are connected to a communication network such as a LAN or WAN (Wide Area Network).

[0048] (Control Unit) The control unit 100 includes a CPU (Central Processing Unit), ROM (Read Only Memory), and RAM (Random Access Memory), etc. The CPU reads a program corresponding to the processing content from the ROM and loads it into the RAM. The CPU then works in cooperation with the loaded program to centrally control the operation of each part of the image forming system 1. The control unit 100 functions as a reading control unit, a first calculation unit, a second calculation unit, a third calculation unit, a fourth calculation unit, a display control unit, and a correction unit, all for the purpose of adjustment using an adjustment chart. The adjustment chart, as shown in Figure 3, is formed with four right-angled isosceles triangles that are symmetrical with respect to the center of the main scanning direction. These formed marks have a hypotenuse that changes in width in the main scanning direction or sub-scanning direction and is symmetrical with respect to the center line of the main scanning direction, allowing for the adjustments described later.

[0049] (Reading control unit) As shown in Figure 4, the control unit 100 controls the reading and scanning unit 20 to scan two locations on the mark M formed on the adjustment chart A, which is transported in the sub-scanning direction (Y direction) by the reading and transporting unit 10, in a line-like manner in the main scanning direction (X direction) with a width of 1 pixel in the Y direction. These two locations are the first image cropping position P1 and the second image cropping position P2. The reading and scanning unit 20 acquires a cropped image (first image) L1 of one line (reading line) by scanning at the first image cropping position P1. The reading and scanning unit 20 outputs the acquired image data to the control unit 100. Next, the reading and scanning unit 20 acquires a cropped image (second image) L2 of one line (reading line) by scanning at the second image cropping position P2. The reading and scanning unit 20 outputs the acquired image data to the control unit 100. Image 1, L1, contains two black line images obtained by scanning over mark M. Let their lengths be a and b, respectively, and let E be the distance between the centers of the two line images. Also, let d be the distance from the edge in the X direction to the line image. In the second image L2, there are also two black line images obtained by scanning over mark M. Let c be the distance from the edge in the X direction to the nearest line image. Let e ​​be the length of the nearest line image from the edge in the X direction. Furthermore, let F be the distance between the cropping position P1 of the first image and the cropping position P2 of the second image.

[0050] (First Calculation Unit) The control unit 100 calculates the tilt in the main scanning direction based on the image data acquired by the reading and scanning unit 20. Specifically, based on a, b, and E in Figure 4, the angle α is calculated using the following formula (1). Formula (1): Angle (α)=(ab) / E*100(%)

[0051] (Second Calculation Department) The control unit 100 calculates the inclination in the sub-scanning direction based on the image data acquired by the reading scanning unit 20. Specifically, based on c, d, and F in Figure 4, the angle β is calculated using the following equation (2). Formula (2): Angle (β)=(cd) / F*100(%)

[0052] (Third Calculation Department) The control unit 100 calculates the amount of angular misalignment (angle γ) between the paper transport direction of the reading transport unit 10 and the main scanning direction of the reading scanning unit 20 from the tilt in the main scanning direction (angle α) and the tilt in the sub-scanning direction (angle β). Specifically, angle γ is calculated based on angles α and β using the following equation (3). Formula (3): Angle (γ) = Angle (α) - Angle (β) (%) The process of reading a document D and obtaining image data illustrates how angles α, β, and γ appear, using the process of reading a document like the one in Figure 5 at an angle as shown in Figure 6 and obtaining the image data shown in Figure 7. Figure 5 is a document with marks formed perpendicular or parallel to the leading edge, side edge, and trailing edge of the paper. Figure 6 shows the case where a document being transported in the transport direction L7 is read at the reading line L3. The extension of the leading edge of the document L5 is tilted by angle α with respect to the reading line L3. Corresponding to this tilt, the perpendicular line L6 to the extension of the leading edge of the document is tilted by angle α with respect to the perpendicular line L4 to the reading line. Also, the perpendicular line L6 to the extension of the leading edge of the document is tilted by angle β with respect to the transport direction L7. Here, it can be seen that angle γ, which represents the amount of angular deviation, is obtained by subtracting angle β from angle α, as shown in the left part of Figure 6. Figure 7 shows the image data obtained when the document is read at an angle as shown in Figure 6. As shown in Figure 6, when a document is scanned while tilted, the resulting image data shows the marks formed on the document tilted by an angle α in the main scanning direction and by an angle β in the sub-scanning direction. If we consider the case where the document is scanned after an adjustment of angle γ in Figure 6, it can be seen that the tilt of the marks in the resulting image data becomes smaller.

[0053] (Fourth Calculation Section) The control unit 100 calculates an adjustment amount to bring the angular misalignment (angle γ) to zero based on the angular misalignment (angle γ). The control unit 100 performs this calculation based on the relationship between the angular misalignment (angle γ) and the adjustment scale movement amount in the angle adjustment mechanism 17 (described later) of the reading transport unit 10 and the reading scanning unit 20, which has been measured in advance. The control unit 100 displays the adjustment amount on the display unit 32. More specifically, the control unit 100 calculates the adjustment amount from data that has been compiled into a table showing the relationship between the amount of angular displacement (angle γ) and the amount of adjustment scale movement in the angle adjustment mechanism 17 (described later) of the reading transport unit 10 and the reading scanning unit 20. Alternatively, the control unit 100 may create an approximation formula from the above relationship and calculate the adjustment amount from the created approximation formula.

[0054] (Angle adjustment mechanism) The angle adjustment mechanism 17 is provided on one of the two hinges that connect the reading transport unit 10 and the reading scanning unit 20, as shown in Figure 8. The user can adjust the angle between the reading transport unit 10 and the reading scanning unit 20 by adjusting the tightness of the screw shown in Figure 9 on the angle adjustment mechanism 17. The scale provided on the angle adjustment mechanism 17 corresponds to the adjustment amount, and the user can make adjustments to make the angle deviation (angle γ) zero.

[0055] (Correction section) As shown in Figure 10, the control unit 100 corrects the document image data based on the tilt in the main scanning direction (angle α) and the tilt in the sub-scanning direction (angle β). Specifically, the control unit 100 corrects the tilt in the main scanning direction by angle α and the tilt in the sub-scanning direction by angle β of the document image data read by the reading and transporting unit 20 from the adjustment chart transported by the reading and transporting unit 10.

[0056] (Display Control Unit) The control unit 100 outputs the angular displacement amount (angle γ) and the adjustment amount to the display unit 32. An example of output to the display unit 32 is shown in Figure 11.

[0057] Figure 12 is a flowchart showing the angle adjustment process using an adjustment chart. This process is implemented through software processing involving the cooperation of the CPU in the control unit and a program stored in ROM.

[0058] The control unit 100 instructs the reading transport unit 10 and the reading scanning unit 20 to read the adjustment chart. As a reading control unit, the control unit 100 controls the reading transport unit 10 and the reading scanning unit 20 to read marks formed on the adjustment chart at two locations (first image cropping position P1 and second image cropping position P2). At this time, the control unit 100 controls the reading transport unit 10 and the reading scanning unit 20 to read these two locations with a gap in the sub-scanning direction, where the reading line consists of one or more pixels in the sub-scanning direction and pixels equal to the width of the adjustment chart in the main scanning direction. The control unit 100 acquires image data from two locations on the adjustment chart A during the above process (step S1).

[0059] The control unit 100, as a first calculation unit, calculates the tilt in the main scanning direction from the image data and obtains the tilt in the main scanning direction (angle α) (step S2).

[0060] The control unit 100, acting as a second calculation unit, calculates the inclination in the sub-scanning direction from the image data and obtains the inclination (angle β) in the sub-scanning direction (step S3).

[0061] The control unit 100, acting as a third calculation unit, calculates the amount of angular displacement from the tilt in the main scanning direction and the tilt in the sub-scanning direction, and obtains the amount of angular displacement (angle γ) (step S4).

[0062] The control unit 100 determines whether the acquired angular displacement amount is within the reference range (step S5).

[0063] If the amount of angular deviation is within the reference range (step S5; YES), the control unit 100 stores the tilt in the main scanning direction, the tilt in the sub-scanning direction, and the amount of angular deviation in the storage unit 80 (step S6), and terminates the process.

[0064] If the amount of angular deviation is not within the reference range (step S5; NO), the control unit 100, as a fourth calculation unit, calculates an adjustment amount to make the angular deviation zero from the amount of angular deviation and obtains the adjustment amount (step S7). The control unit 100 performs this calculation based on the amount of angular deviation and the amount of adjustment scale movement of the angle adjustment mechanism 17 relative to the previously measured amount of angular deviation. The control unit 100, as a display control unit, controls the display unit 32 to display the amount of angular deviation and the adjustment amount (step S8). The user adjusts the angle adjustment mechanism 17 based on the adjustment amount and presses the adjustment completion button on the operation unit. The control unit 100 determines whether the adjustment is complete via the operation unit 31 (step S9). If the adjustment is complete (step S9; YES), the control unit 100 proceeds to step S1.

[0065] Figure 13 is a flowchart showing the correction process performed by the correction unit. This process is realized through software processing involving the cooperation of the CPU of the control unit 100 and the program stored in ROM.

[0066] The control unit 100 obtains the tilt in the main scanning direction and the tilt in the sub-scanning direction from the storage unit 80 (step S21).

[0067] The control unit 100 causes the reading transport unit 10 and the reading scanning unit 20 to read the document and acquire document image data (step S22).

[0068] The control unit 100 corrects the document image data based on the tilt in the main scanning direction and the tilt in the sub-scanning direction, and acquires the corrected document image data (step S23). Specifically, the control unit corrects the document image data so that the main scanning direction is rotated by the tilt in the main scanning direction, and the sub-scanning direction is rotated by the tilt in the sub-scanning direction (step S24).

[0069] The control unit 100 finishes processing the correction of the original image data.

[0070] As described above, according to this embodiment, by reading an adjustment chart with the image reading device 500, which has marks formed on it such that the width changes in the main scanning direction or sub-scanning direction as shown in Figure 3 and which have multiple hypotenuses that are symmetrical with respect to the center line of the main scanning direction, the tilt in the main scanning direction and the tilt in the sub-scanning direction can be obtained. Furthermore, from the tilt in the main scanning direction and the tilt in the sub-scanning direction, the amount of angular misalignment between the paper transport direction of the reading transport unit 10 and the main scanning direction of the reading scanning unit 20, and the corresponding adjustment amount of the angle adjustment mechanism 17 of the reading transport unit 10 and the reading scanning unit 20 can be obtained. Using this adjustment amount, the angle adjustment mechanism 17 of the reading transport unit 10 and the reading scanning unit 20 can be adjusted so that the angle misalignment between the document transport direction of the reading transport unit 10 and the main scanning direction of the reading scanning unit 20 becomes smaller. In addition, by obtaining the tilt in the main scanning direction and the tilt in the sub-scanning direction, image data in which the tilt in the main scanning direction and the tilt in the sub-scanning direction of the scanned document image data have been corrected can be obtained.

[0071] [Differentiation] Figure 14 shows examples of adjustment charts that can be used as modified examples. Adjustment chart (1) has one mark in the shape of a rectangle with a rhombus-shaped hole, formed symmetrically with respect to the center line of the main scanning direction and the center line of the sub-scanning direction. The width of the mark changes in each scanning direction due to the rhombus-shaped hole, and four hypotenuses that are symmetrical with respect to the main scanning direction are created, allowing for adjustments similar to those in this embodiment. Adjustment chart (2) has four congruent rhombus-shaped marks, formed symmetrically with respect to the center line of the main scanning direction and the center line of the sub-scanning direction. Because the four rhombus-shaped marks are formed symmetrically with respect to the center line of the main scanning direction, the width of the marks changes in each scanning direction, and 16 hypotenuses that are symmetrical with respect to the main scanning direction are created by the sides of each rhombus, allowing for adjustments similar to those in this embodiment. Adjustment chart (3) has four congruent marks in the shape of a square with a quarter circle with a radius equal to one side of the square removed, formed symmetrically with respect to the center line of the main scanning direction and the center line of the sub-scanning direction. The arc-shaped hypotenuses change the width of the marks in each scanning direction, and since there are four arc-shaped hypotenuses that are symmetrical with respect to the main scanning direction, adjustments similar to those in this embodiment can be made.The adjustment chart in (4) is formed so that four congruent right-angled isosceles triangle marks are symmetrical with respect to the center line of the main scanning direction, and so that two marks on the same side of the center line of the main scanning direction have the same orientation.The arc-shaped hypotenuses change the width of the marks in each scanning direction, and since there are four hypotenuses that are symmetrical with respect to the main scanning direction, adjustments similar to those in this embodiment can be made.

[0072] In addition to the usual meaning, "calculation" in the above embodiment also means retrieving the necessary value from data that includes the correspondence between two or more parameters, which is stored in the memory unit beforehand. For example, "calculation" by the fourth calculation unit means, in addition to the usual meaning, retrieving the necessary value from data that includes the correspondence between specific angles and adjustment amounts, which is stored in the memory unit beforehand. In addition, the calculation of the inclination in the sub-scanning direction by the second calculation unit in the above embodiment may be performed by the following formula (4) based on a, e, and F in Figure 4. Formula (4): Angle (β)=(ae) / F*100(%) In addition to its usual meaning, the term "hypotenuse" in the context of adjustment charts also refers to a line among the marks formed on the adjustment chart that is neither parallel nor perpendicular to the vertical or horizontal edges of the paper. Hypotenuses include not only straight lines but also curves. For example, the hypotenuse of the adjustment chart in Figure 14 (3) is a circular arc, and therefore a curve. [Explanation of Symbols]

[0073] 1. Image forming system 10 Reading and transport unit 17 Angle adjustment mechanism 20 Reading and scanning unit 50 Image forming unit 100 Control Unit A Adjustment Chart M mark S paper

Claims

1. An image reading device that reads the image of a sheet of paper being transported by a reading and transport unit using a reading and scanning unit while the paper is being transported, A reading control unit controls the reading of one mark or multiple marks having a single A first calculation unit calculates the tilt in the main scanning direction from the difference in mark widths in one reading line read by the reading control unit, A second calculation unit calculates the inclination in the sub-scanning direction from the difference in the position or width of marks on two reading lines read at intervals in the sub-scanning direction, An image reading device equipped with [a specific feature].

2. The image reading device according to claim 1, further comprising a third calculation unit that calculates the amount of angular deviation between the paper transport direction of the reading transport unit and the main scanning direction of the reading scanning unit from the tilt of the main scanning direction calculated by the first calculation unit and the tilt of the sub-scanning direction calculated by the second calculation unit.

3. The image reading device according to claim 2, further comprising a display control unit that displays the amount of angular displacement calculated by the third calculation unit on a display unit.

4. The reading and transporting unit includes an angle adjustment mechanism that adjusts the relative angle with respect to the main scanning direction of the reading and scanning unit, It has a fourth calculation unit that calculates an adjustment amount to make the angular displacement amount zero from the angular displacement amount calculated by the third calculation unit, The image reading device according to claim 3, wherein the display control unit displays on the display unit an adjustment amount to make the angular displacement amount calculated by the fourth calculation unit zero.

5. The image reading device according to claim 1, further comprising a correction unit that corrects the tilt in the main scanning direction and the tilt in the sub-scanning direction of image data read by the reading scanning unit from paper transported by the reading transport unit, using the tilt in the main scanning direction calculated by the first calculation unit and the tilt in the sub-scanning direction calculated by the second calculation unit.

6. The computer of the image reading device, which reads the image of the paper being transported by the reading and transport unit while it is being transported, A reading control unit controls the reading of one or more marks from an adjustment chart, each mark having multiple hypotenuses that are symmetrical with respect to the center line in the main scanning direction and whose width changes in the main scanning direction, by reading lines that are one or more pixels in the sub-scanning direction and the width of the adjustment chart in the main scanning direction, at two or more locations with spacing in the sub-scanning direction. A first calculation unit calculates the tilt in the main scanning direction from the difference in mark widths in one reading line read by the reading control unit. A second calculation unit calculates the inclination in the sub-scanning direction from the difference in the position or width of marks on two reading lines read at intervals in the sub-scanning direction. A program that makes it function as such.

7. An image reading device according to any one of claims 1 to 5, An image forming unit that forms an image on paper using image data obtained by the image reading device, An image forming system comprising the following features.

Images