JP2019209642A - Image formation apparatus and image formation method - Google Patents

Abstract

To provide an image formation apparatus and image formation method which can reduce the time and effort of a user that occur when performing printing to a tab included in a sheet.SOLUTION: An image formation apparatus includes: an image reading unit 7 which reads an image of a sheet conveyed along a conveyance path at a reading position on the upstream side in the conveyance direction of the sheet with respect to the image formation position in the conveyance path of the sheet passing through the image formation position; a tab detection unit 8 which detects a tab included in the sheet on the basis of the image of the sheet read at the reading position; and an image formation processing unit 91 which forms the image on the tab detected by the tab detection unit 8.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an image forming apparatus and an image forming method capable of printing on a tab included in a sheet.

  An image forming apparatus such as a copier capable of printing on a tab included in a sheet is known. For example, an image forming apparatus capable of registering tab information indicating a detection result of a tab included in a sheet and capable of printing on a tab included in the sheet based on the tab information registered in advance is known as a related technique. (See Patent Document 1).

JP 2006-142610 A

  However, in the image forming apparatus according to the related technology described above, it is necessary for the user to read the image of the sheet including the tab in advance by the image forming apparatus and register the tab information, and the user registers the tab information. It takes time and effort.

  An object of the present invention is to provide an image forming apparatus and an image forming method capable of reducing a user's trouble that occurs when printing on a tab included in a sheet.

  An image forming apparatus according to an aspect of the present invention includes an image reading unit, a tab detection unit, and an image formation processing unit. The image reading unit reads an image of a sheet conveyed along the conveyance path at a reading position upstream in the sheet conveyance direction from the image formation position in the sheet conveyance path passing through the image formation position. The tab detection unit detects a tab included in the sheet based on the image of the sheet read at the reading position. The image formation processing unit forms an image on the tab detected by the tab detection unit.

  An image forming method according to another aspect of the present invention is conveyed along the conveyance path at a reading position upstream in the sheet conveyance direction from the image formation position in the sheet conveyance path via the image formation position. Reading an image of the sheet, detecting a tab included in the sheet based on the image of the sheet read at the reading position, and forming an image on the detected tab.

  According to the present invention, an image forming apparatus and an image forming method capable of reducing a user's trouble that occurs when printing on a tab included in a sheet are realized.

FIG. 1 is a diagram illustrating a configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a configuration of an image forming unit in the image forming apparatus according to the embodiment of the present invention. FIG. 3 is a block diagram illustrating configurations of an image reading unit, a tab detection unit, a control unit, and an operation display unit in the image forming apparatus according to the embodiment of the present invention. FIG. 4 is a flowchart illustrating an example of tab print processing executed by the image forming apparatus according to the embodiment of the present invention. FIG. 5 is a flowchart illustrating an example of tab detection processing executed by the image forming apparatus according to the embodiment of the present invention. FIG. 6 is a diagram illustrating an example of image data read by the image forming apparatus according to the embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The following embodiment is an example embodying the present invention, and does not limit the technical scope of the present invention.

[Schematic Configuration of Image Forming Apparatus 10]
First, a schematic configuration of the image forming apparatus 10 according to the embodiment of the present disclosure will be described with reference to FIGS. 1 to 3. Here, FIG. 1 is a schematic cross-sectional view showing the configuration of the image forming apparatus 10. FIG. 2 is a plan view showing the configuration of the image forming unit 3. In FIG. 1, the sheet conveyance path R <b> 1 inside the housing 11 of the image forming apparatus 10 is indicated by a two-dot chain line. In FIG. 3, the flow of image data is indicated by a solid arrow line, and the flow of electrical signals is indicated by a broken arrow line.

  The image forming apparatus 10 is a printer capable of forming an image by an inkjet method. The present invention may be applied to an image forming apparatus such as a facsimile machine, a copier, and a multi-function machine capable of forming an image by an inkjet method. The present invention may also be applied to an image forming apparatus capable of forming an image by a method different from an inkjet method such as an electrophotographic method.

  As shown in FIGS. 1 and 3, the image forming apparatus 10 includes a paper feed cassette 1, a paper feed unit 2, an image forming unit 3, an ink container unit 4, a transport unit 5, a paper discharge unit 6, and an image reading unit 7. , A tab detection unit 8, a control unit 9, and an operation display unit 12.

  The sheet cassette 1 stores sheets to be printed in the image forming apparatus 10. For example, the sheets accommodated in the paper feed cassette 1 are sheet materials such as paper, coated paper, postcards, envelopes, and OHP sheets.

  In the image forming apparatus 10, the sheets accommodated in the paper feed cassette 1 are conveyed inside the housing 11 along a conveyance path R <b> 1 (see FIG. 1) that passes through image forming positions P <b> 11 to P <b> 14 by the image forming unit 3. The paper is discharged to a paper discharge tray 64 of the paper discharge unit 6.

  The paper feed unit 2 supplies the sheets stored in the paper feed cassette 1 to the transport unit 5. As shown in FIG. 1, the paper feed unit 2 includes a pickup roller 21, a transport roller 22, a transport path 23, a manual feed tray 24, a paper feed roller 25, and a registration roller 26.

  The pickup roller 21 takes out sheets one by one from the sheet feeding cassette 1. The conveyance roller 22 conveys the sheet taken out by the pickup roller 21 to the registration roller 26. The conveyance path 23 is a sheet movement path from the sheet feeding cassette 1 and the manual feed tray 24 to the conveyance unit 5. The manual feed tray 24 and the paper feed roller 25 are used for supplying sheets from the outside.

  The registration roller 26 is provided on the upstream side of the image forming positions P11 to P14 in the transport path R1. The registration roller 26 conveys the sheet toward the conveyance unit 5 every time a predetermined conveyance timing arrives. For example, the conveyance timing is a timing at which a predetermined time has elapsed since the leading edge of the sheet is detected by a sheet sensor (not shown) provided on the upstream side of the registration roller 26 in the conveyance path R1. The registration roller 26 rotates in response to a rotational driving force supplied from a motor (not shown).

  The image forming unit 3 forms an image based on the image data on a sheet supplied from the paper feeding unit 2 using ink as a developer. As shown in FIG. 1, the image forming unit 3 includes line heads 31, 32, 33, and 34 corresponding to black, cyan, magenta, and yellow colors, and a head frame 35 that supports these. The head frame 35 is supported by the casing 11 of the image forming apparatus 10. Note that the number of line heads provided in the image forming unit 3 may be one or a plurality other than four.

  The line heads 31 to 34 are so-called line head type recording heads. That is, the image forming apparatus 10 is a so-called line head type image forming apparatus. As shown in FIG. 2, the line heads 31 to 34 are long in the width direction D2. Specifically, each of the line heads 31 to 34 has a length corresponding to the width of the maximum size sheet among the sheets that can be accommodated in the sheet feeding cassette 1 in the width direction D2. Each of the line heads 31 to 34 is fixed to the head frame 35 at a predetermined interval along the sheet conveyance direction D1 (see FIG. 2). The positions facing the line heads 31 to 34 on the transport path R1 are image forming positions P11 to P14 by the image forming unit 3.

  As shown in FIG. 2, each of the line heads 31 to 34 has a plurality of recording heads 30. The recording head 30 ejects ink toward the sheet conveyed by the conveyance unit 5. Specifically, a large number of ink ejection nozzles 30 </ b> A (see FIG. 2) having openings are provided on the surface of the recording head 30 that faces the sheet conveyed by the conveyance unit 5. The recording head 30 has a pressurizing chamber (not shown) corresponding to each nozzle 30A, a piezoelectric element (not shown) provided corresponding to each pressurizing chamber, and a communication flow communicating with each pressurizing chamber. A path (not shown) is provided. The piezoelectric element ejects ink from the nozzle 30A in response to application of a predetermined driving voltage. Specifically, the piezoelectric element discharges ink from the nozzle 30 </ b> A by pressurizing the ink stored in the pressurizing chamber.

  In the present embodiment, the line head 31 includes three recording heads 30 arranged in a staggered pattern along the width direction D2. Further, in each of the other line heads 32 to 34, similarly to the line head 31, the three recording heads 30 are arranged in a staggered manner along the width direction D <b> 2. 2 shows a state in which the image forming unit 3 is viewed from the upper side of FIG.

  The ink container unit 4 includes ink containers 41, 42, 43, and 44 that store inks corresponding to black, cyan, magenta, and yellow. The ink containers 41 to 44 are connected to line heads 31 to 34 of the same color via an ink supply unit (not shown).

  The transport unit 5 transports the sheet at the image forming positions P11 to P14 in the transport path R1. Specifically, the transport unit 5 is disposed below the line heads 31 to 34 as shown in FIG. The conveyance unit 5 conveys the sheet while facing the recording head 30. As shown in FIG. 1, the transport unit 5 includes a transport belt 51 on which a sheet is placed, stretching rollers 52 to 54 that stretch the transport belt 51, and a transport frame 55 that supports these. The gap between the conveyance belt 51 and the recording head 30 is adjusted so that, for example, the gap between the surface of the sheet and the recording head 30 during image formation is 1 mm.

  The tension roller 52 is rotationally driven by a rotational driving force supplied from a motor (not shown). Thereby, the conveyance belt 51 rotates in a direction in which the sheet can be conveyed in the conveyance direction D1 (see FIG. 1). Therefore, the sheet supplied from the paper feeding unit 2 is conveyed to the paper discharge unit 6 via the image forming positions P11 to P14 (see FIG. 1) by the rotation of the conveyance belt 51.

  The transport unit 5 is also provided with a suction unit (not shown) that sucks air from a large number of through holes formed in the transport belt 51 in order to attract the sheet to the transport belt 51. In addition, a pressure roller 56 for pressing the sheet against the conveying belt 51 and conveying the sheet is provided at a position facing the stretching roller 52.

  The paper discharge unit 6 is provided downstream of the image forming unit 3 in the transport direction D1. As shown in FIG. 1, the paper discharge unit 6 includes a drying device 61, a conveyance path 62, a paper discharge roller 63, and a paper discharge tray 64. The drying device 61 dries the ink attached to the sheet, for example, by blowing air on the sheet. The conveyance path 62 is a sheet movement path from the conveyance unit 5 to the paper discharge tray 64. The paper discharge roller 63 discharges the sheet to the paper discharge tray 64.

  As shown in FIG. 3, the control unit 9 includes control devices such as a CPU 9A, a ROM 9B, a RAM 9C, and a nonvolatile memory 9D. The CPU 9A is a processor that executes various arithmetic processes. The ROM 9B is a nonvolatile storage device in which information such as a control program for causing the CPU 9A to execute various processes is stored in advance. The RAM 9C is a volatile storage device, and is used as a temporary storage memory (working area) for various processes executed by the CPU 9A. The nonvolatile memory 9D is a nonvolatile storage device such as a flash memory and an EEPROM (registered trademark). In the control unit 9, various control programs stored in advance in the ROM 9B are executed by the CPU 9A. As a result, the image forming apparatus 10 is comprehensively controlled by the control unit 9.

  The operation display unit 12 is a display unit such as a liquid crystal display that displays various types of information according to control instructions from the control unit 9, and an operation key or a touch panel that inputs various types of information to the control unit 9 according to user operations. And so on.

  Incidentally, an image forming apparatus capable of printing on a tab included in a sheet is known. For example, an image forming apparatus that can register tab information indicating the detection result of the tab and can print on the tab based on the tab information registered in advance is known as a related art.

  However, in the image forming apparatus according to the related technology described above, it is necessary for the user to register the tab information by causing the image forming apparatus to read the image of the sheet including the tab in advance. It takes time to register.

  On the other hand, as described below, the image forming apparatus 10 according to the embodiment of the present invention can reduce the labor of the user that occurs when printing on the tab.

  The image reading unit 7 reads an image of a sheet conveyed along the conveyance path R1 at a reading position P1 (see FIG. 1) upstream of the image forming positions P11 to P14 in the conveyance path R1 in the sheet conveyance direction D1. .

  Specifically, as shown in FIGS. 1 and 3, the image reading unit 7 includes a line sensor 71 provided opposite to a sheet passing through the reading position P <b> 1 and an AFE (analog front end) circuit 72. .

  The line sensor 71 can read monochrome image data for one line along the main scanning direction, which is the same as the width direction D2, from the sheet passing through the reading position P1. For example, the line sensor 71 is an image sensor such as a CIS (contact image sensor) including a light emitting unit and a light receiving unit. The light emitting unit emits one line of light along the main scanning direction toward the reading position P1. The light receiving unit is provided so as to be able to receive light emitted from the light emitting unit and reflected by a sheet passing through the reading position P1, and outputs an analog electric signal corresponding to the amount of received light. The line sensor 71 outputs an analog electrical signal corresponding to one line of image data along the main scanning direction from the light receiving unit at a predetermined interval in accordance with a control signal input from the control unit 9. .

  The AFE circuit 72 is an electronic circuit that converts an analog electrical signal output from the light receiving unit of the line sensor 71 into a digital electrical signal (image data). For example, the AFE circuit 72 converts an analog electrical signal output from the light receiving unit into image data expressed in 256 gradations with pixel densities from 0 to 255. In the following, it is assumed that the density value 0 is the darkest (darkest) and the density value 255 is the lightest (lightest). The AFE circuit 72 outputs the converted image data to the tab detection unit 8.

  The tab detection unit 8 detects the tab included in the sheet based on the image of the sheet read at the reading position P1. The tab detection unit 8 is configured by an electronic circuit such as an integrated circuit (ASIC, DSP). Note that the CPU 9A of the control unit 9 may function as the tab detection unit 8 by executing the control program stored in the ROM 9B.

  Specifically, the tab detection unit 8 detects the tab based on an image of a sheet conveyed in a posture in which the protruding direction of the tab faces the upstream side of the conveyance direction D1. In the image forming apparatus 10, when printing is performed on the tab, the sheet including the tab is placed on the manual feed tray 24 in a posture in which the protruding direction of the tab faces the upstream side in the transport direction D1.

  As shown in FIG. 3, the tab detection unit 8 includes a binarization unit 81, a fourth detection unit 82, a fifth detection unit 83, a first detection unit 84, a second detection unit 85, and a third detection unit 86. Is provided.

  The binarization unit 81 executes binarization processing for binarizing each pixel included in the image data for one line in the main scanning direction output from the image reading unit 7 to a value indicating the presence or absence of a sheet. To do. Specifically, when the density value of the pixel is equal to or less than a first threshold value, the binarization unit 81 converts the density value of the pixel to 0 indicating the absence of the sheet. On the other hand, if the density value of the pixel exceeds the first threshold value, the binarization unit 81 converts the density value of the pixel to 1 indicating the presence of the sheet. For example, the first threshold is 100. The first threshold value may be arbitrarily determined within a range in which the presence / absence of a sheet can be determined.

  The image data binarized by the binarization unit 81 is input to the fourth detection unit 82, the fifth detection unit 83, the first detection unit 84, the second detection unit 85, and the third detection unit 86. The fourth detection unit 82, the fifth detection unit 83, the first detection unit 84, the second detection unit 85, and the third detection unit 86 execute processing based on the image data after binarization by the binarization unit 81. To do.

  Note that the tab detection unit 8 may not include the binarization unit 81. In this case, the fourth detection unit 82, the fifth detection unit 83, the first detection unit 84, the second detection unit 85, and the third detection unit 86 are one line in the main scanning direction output from the image reading unit 7. The processing based on the minute image data may be executed.

  Based on the image data for one line in the main scanning direction output from the binarization unit 81, the fourth detection unit 82 is configured such that the leading end in the conveyance direction D1 of the sheet conveyed by the sheet feeding unit 2 is the reading position. The third timing passing through P1 is detected.

  Specifically, the fourth detection unit 82 performs the third timing when the number of pixels having a density value of 1 included in the image data for one line in the main scanning direction exceeds a predetermined second threshold. Is detected. For example, the second threshold value is determined in advance for each sheet size conveyed by the sheet feeding unit 2. For example, when the sheet conveyed by the sheet feeding unit 2 is an A4 size sheet placed on the manual feed tray 24 in a posture in which the longitudinal direction is orthogonal to the conveyance direction D1, the second threshold value is the A4 size sheet. This is a half of the number of pixels corresponding to the length in the longitudinal direction (width direction D2) of the sheet. The second threshold may be determined based on the minimum sheet size that can be printed by the image forming apparatus 10.

  When the fourth detection unit 82 detects the third timing, the fourth detection unit 82 notifies the fifth detection unit 83 to that effect.

  The fifth detection unit 83 detects the image data for one line in the main scanning direction output from the binarization unit 81 after the third timing is detected by the fourth detection unit 82 in the sheet width direction D2. Detect the length.

  For example, the fifth detection unit 83 counts the number of image data input from the binarization unit 81 after the fourth detection unit 82 notifies the detection of the third timing. Then, the fifth detection unit 83 detects the length in the width direction D2 of the sheet based on the image data for one line in the main scanning direction input at a timing when the count number exceeds a predetermined reference value. To do. Specifically, the fifth detection unit 83 detects the number of pixels having a density value of 1 included in the image data for one line in the main scanning direction as a value indicating the length in the sheet width direction D2. The fifth detector 83 detects a sheet based on the image data when the third timing is detected based on the image data for one line in the main scanning direction output from the binarizer 81. The length in the width direction D2 may be detected.

  When the fifth detection unit 83 detects the length of the sheet in the width direction D2, the fifth detection unit 83 notifies the first detection unit 84 of the detection result.

  The tab detection unit 8 may not include the fourth detection unit 82. In this case, the fifth detection unit 83, for example, an image for one line in the main scanning direction that is output from the binarization unit 81 after a predetermined time has elapsed since the start of conveyance of the sheet by the registration roller 26. The length of the sheet in the width direction D2 may be detected based on the data.

  The first detection unit 84 detects the tab based on the image data for one line in the main scanning direction output from the binarization unit 81 after the fifth detection unit 83 detects the length in the sheet width direction D2. The first timing at which the front end portion in the transport direction D1 passes the reading position P1 is detected. The leading end of the tab in the conveyance direction D1 is a boundary between the tab region and other regions in the sheet including the tab.

  Specifically, the first detection unit 84 has a predetermined difference between the detection result of the fifth detection unit 83 and the number of pixels having a density value of 1 included in the image data for one line in the main scanning direction. The first timing is detected when the third threshold value is exceeded. For example, the value is one half or two thirds of the detection result by the fifth detection unit 83.

  When the first detection unit 84 detects the first timing, the first detection unit 84 notifies the control unit 9, the second detection unit 85, and the third detection unit 86 to that effect.

  The tab detection unit 8 may not include the fourth detection unit 82 and the fifth detection unit 83. In this case, the first detection unit 84, for example, the number of pixels corresponding to the length in the longitudinal direction of the sheet predetermined for each size of the sheet conveyed by the sheet feeding unit 2 and one line in the main scanning direction. The first timing may be detected when the difference between the density value included in the image data for 1 minute and the number of pixels of 1 exceeds the third threshold value.

  The second detection unit 85 performs the tab transport direction D1 based on the image data for one line in the main scanning direction output from the binarization unit 81 after the first timing is detected by the first detection unit 84. The second timing at which the rear end portion passes through the reading position P1 is detected.

  Specifically, the second detection unit 85 performs the second detection when the number of pixels whose density value is 1 included in the image data for one line in the main scanning direction is equal to or less than a predetermined fourth threshold value. Detect timing. For example, the fourth threshold is zero. The fourth threshold value is a density value included in the image data when the first timing is detected based on the image data for one line in the main scanning direction output from the binarization unit 81. May be determined based on the number of pixels of one.

  When the second detection unit 85 detects the second timing, the second detection unit 85 notifies the third detection unit 86 to that effect. In addition, when the second detection unit 85 detects the second timing, the second detection unit 85 may notify the control unit 9 and the third detection unit 86 to that effect.

  The third detection unit 86, based on the image data for one line in the main scanning direction output from the binarization unit 81 after the detection of the first timing by the first detection unit 84, the width direction D2 of the tab. Detect the positions of both ends in.

  Specifically, the third detection unit 86, when the second timing is not detected based on the image data for one line in the main scanning direction output from the binarization unit 81, the image data and the first A determination process is performed for determining the maximum size of print characters that can print predetermined heading information in a printable area defined based on the number of output image data by the binarization unit 81 since the detection of one timing. To do.

  Here, the printable area corresponds to the number of pixels having a density value of 1 included in the image data output from the binarization unit 81 in the main scanning direction, and has a length in the transport direction D1. This is a rectangular area corresponding to a value obtained by adding 1 to the number of image data output by the binarization unit 81 from the time of detection of the first timing.

  The heading information is a line of character information printed on the tab detected by the tab detection unit 8. In the image forming apparatus 10, the heading information composed of one or more characters arranged along the main scanning direction is printed on the tab detected by the tab detection unit 8. The heading information is input to the image forming apparatus 10 by the user in advance.

  Specifically, in the determination process, the length in the transport direction D1 in the printable area and the length in the main scanning direction in the printable area are divided by the number of characters included in the heading information. Among these, a square area having one side as the smaller side is determined to be the maximum size of the printed character. The number of characters included in the heading information is notified from the control unit 9 in advance when printing on the tab.

  Then, if the character size determined by the determination process does not decrease from the previous determination result, the third detection unit 86 determines both ends in the tab width direction D2 based on the image data used for the determination process. Position information indicating the position of the part is acquired. For example, the third detection unit 86 acquires, as the position information, information indicating the position of each pixel having the density value 1 adjacent to the pixel having the density value 0 among the pixels included in the image data used for the determination process. To do. And the 3rd detection part 86 performs the storage process which stores the acquired positional information and the size information which shows the character size determined by the said determination process in the memory | storage part 861 (refer FIG. 3). For example, the storage unit 861 is a storage device such as a register, and includes a storage area that can store a set of the position information and the size information. In the storage process, the position information and the size information are stored in the storage unit 861 by being overwritten.

  On the other hand, when the character size determined by the determination processing is smaller than the previous determination result, the third detection unit 86 has the latest storage timing in the storage unit 861 stored in the storage unit 861. An output process for outputting the information and the size information is executed.

  The third detection unit 86 executes the output process when the second timing is detected based on the image data for one line in the main scanning direction output from the binarization unit 81. Note that the third detection unit 86 outputs empty data in the output process when the position information and the size information are not stored in the storage unit 861.

  Note that the storage process may be a process of storing only the position information in the storage unit 861. The output process may be a process for outputting only the position information.

  Further, the third detection unit 86 may not execute the determination process. In this case, the third detection unit 86 acquires based on the image data when the second timing is not detected based on the image data for one line in the main scanning direction output from the binarization unit 81. The position information may be stored in the storage unit 861. That is, the storage process may be a process of storing only the position information in the storage unit 861. The output process may be a process for outputting only the position information.

  In addition, when the first timing is detected based on the image data for one line in the main scanning direction output from the binarization unit 81, the third detection unit 86 is configured based on the image data. You may detect the position of the both ends in the width direction D2 of a tab. In addition, the third detection unit 86 is for one line in the main scanning direction output from the binarization unit 81 after a predetermined time has elapsed after the detection of the first timing by the first detection unit 84. Based on the image data, the positions of both ends in the width direction D2 of the tab may be detected.

  The storage unit 861 may be capable of storing a plurality of sets of the position information and the size information. In this case, the third detection unit 86 outputs the position information and the size information in a set different from the set of the position information and the size information whose storage timing to the storage unit 861 is the latest in the output process. May be.

  On the other hand, the control unit 9 includes an image formation processing unit 91 as shown in FIG. Specifically, the control unit 9 executes the control program stored in the ROM 9B using the CPU 9A. Thereby, the control unit 9 functions as the image formation processing unit 91.

  The image formation processing unit 91 prints the heading information on the tab detected by the tab detection unit 8.

  Specifically, based on the position information and the size information output from the third detection unit 86, the image formation processing unit 91 determines that the heading information composed of characters of the size indicated by the size information is the position. Print data arranged based on the information is generated. Then, the image formation processing unit 91 inputs the print data to the image forming unit 3 at a timing when a predetermined time has elapsed since the first detection unit 84 detected the first timing.

  Note that the image formation processing unit 91 includes the first timing detected by the first detection unit 84, the second timing detected by the second detection unit 85, and the position information output from the third detection unit 86. Based on the above, a process for demarcating the tab area and a process for determining the maximum size of print characters that can print the heading information in the area may be executed.

[Tab print processing]
Hereinafter, an example of a tab print processing procedure executed by the control unit 9 in the image forming apparatus 10 will be described with reference to FIG. Here, steps S11, S12,... Represent the numbers of processing procedures (steps) executed by the control unit 9. The tab printing process is executed when an operation input for instructing the execution of the tab printing process is performed on the operation display unit 12.

<Step S11>
First, in step S11, the control unit 9 causes the operation display unit 12 to display an input screen used for inputting the heading information, inputting the size of the sheet including the tab to be printed, and executing the printing process.

  Note that the image forming apparatus 10 may detect the size of the sheet based on the position of the side cursor that adjusts the position in the width direction D2 of the sheet placed on the manual feed tray 24. In this case, the input screen may not include an image such as an input field used for inputting the sheet size.

<Step S12>
In step S12, the control unit 9 determines whether or not the execution operation has been performed in a state where the heading information and the sheet size are input on the input screen.

  If the control unit 9 determines that the execution operation has been performed in a state where the heading information and the sheet size are input (Yes in S12), the process proceeds to step S13. If the execution operation is not performed in the state where the heading information and the sheet size are input (No side in S12), the control unit 9 inputs the heading information and the sheet size in step S12. In this state, it waits for the execution operation to be performed.

<Step S13>
In step S <b> 13, the control unit 9 controls the sheet feeding unit 2 to convey the sheet placed on the manual feed tray 24.

<Step S14>
In step S <b> 14, the control unit 9 instructs the image reading unit 7 to read a sheet image, and instructs the tab detection unit 8 to execute tab detection processing described later. In addition, the control unit 9 notifies the third detection unit 86 of the tab detection unit 8 of the number of characters included in the heading information input on the input screen. Further, the control unit 9 notifies the fourth detection unit 82 of the tab detection unit 8 of the second threshold value corresponding to the size of the sheet input on the input screen.

<Step S15>
In step S <b> 15, the control unit 9 determines whether or not a notification that the first timing has been detected is received from the first detection unit 84 of the tab detection unit 8.

  Here, if the control part 9 judges that the notification of having detected the said 1st timing was received from the 1st detection part 84 (Yes side of S15), a process will be transferred to step S16. If the notification that the first timing is detected is not received from the first detection unit 84 (No in S15), the control unit 9 detects the first timing from the first detection unit 84 in step S15. Wait for the notification to be made.

<Step S16>
In step S <b> 16, the control unit 9 determines whether or not the position information and the size information are input from the third detection unit 86 of the tab detection unit 8.

  If the control unit 9 determines that the position information and the size information are input from the third detection unit 86 (Yes in S16), the control unit 9 shifts the process to step S17. In addition, if the position information and the size information are not input from the third detection unit 86 (No side of S16), the control unit 9 transmits the position information and the size from the third detection unit 86 in step S16. Wait for information to be entered.

<Step S17>
In step S17, the control unit 9 determines whether an error is detected. For example, the control unit 9 detects an error when the time from the reception of the notification in step S15 to the input of the position information or the like in step S16 is shorter than a predetermined time. In addition, the control unit 9 detects an error when one or both of the position information and the size information input in step S16 is abnormal data such as empty data.

  Here, if the control part 9 judges that the error was detected (Yes side of S17), it will transfer a process to step S171. If no error is detected (No in S17), the control unit 9 shifts the process to step S18.

<Step S171>
In step S171, the control unit 9 notifies that the detection of the tab has failed. For example, the control unit 9 causes the operation display unit 12 to display a message indicating that the tab detection has failed. Moreover, the control part 9 may light a predetermined warning lamp with the display of the said message.

<Step S18>
In step S18, the control unit 9 generates the print data based on the heading information input on the input screen, the position information input in step S16, and the size information.

<Step S19>
In step S <b> 19, the control unit 9 inputs the print data generated in step S <b> 19 to the image forming unit 3 at a timing when a predetermined time has elapsed since the notification was received in step S <b> 15. Here, the processes of step S18 and step S19 are executed by the image forming processor 91 of the controller 9.

[Tab detection processing]
Next, an example of the procedure of the tab detection process executed by the tab detection unit 8 in the image forming apparatus 10 will be described with reference to FIG.

<Step S21>
First, in step S <b> 21, the tab detection unit 8 determines whether image data for one line in the main scanning direction is input from the image reading unit 7.

  If the tab detection unit 8 determines that image data has been input from the image reading unit 7 (Yes in S21), the tab detection unit 8 shifts the processing to step S22. If no image data is input from the image reading unit 7 (No in S21), the tab detection unit 8 waits for input of image data from the image reading unit 7 in step S21.

<Step S22>
In step S <b> 22, the tab detection unit 8 performs the binarization process on the image data for one line in the main scanning direction input from the image reading unit 7. Here, the process of step S <b> 22 is executed by the binarization unit 81 of the tab detection unit 8.

<Step S23>
In step S23, the tab detection unit 8 determines whether or not the third timing has been detected based on the image data after the binarization process executed in the immediately preceding step S22. Here, the process of detecting the third timing is executed by the fourth detection unit 82 of the tab detection unit 8.

  If the tab detection unit 8 determines that the third timing has been detected (Yes in S23), the process proceeds to step S24. If the third timing is not detected (No in S23), the tab detection unit 8 shifts the process to step S21.

<Step S24>
In step S24, the tab detection unit 8 determines whether image data for one line in the main scanning direction has been input from the image reading unit 7 as in step S21.

  If the tab detection unit 8 determines that image data has been input from the image reading unit 7 (Yes in S24), the tab detection unit 8 shifts the processing to step S25. If no image data is input from the image reading unit 7 (No in S24), the tab detection unit 8 waits for input of image data from the image reading unit 7 in step S24.

<Step S25>
In step S25, the tab detection unit 8 performs the binarization process on the image data for one line in the main scanning direction input from the image reading unit 7, as in step S22.

<Step S26>
In step S26, the tab detection unit 8 determines whether the number of image data input from the image reading unit 7 after the detection of the third timing in step S23 exceeds the reference value.

  If the tab detection unit 8 determines that the number of input image data exceeds the reference value (Yes in S26), the tab detection unit 8 shifts the process to step S27. If the number of input image data does not exceed the reference value (No in S26), the tab detection unit 8 shifts the process to step S24.

<Step S27>
In step S27, the tab detection unit 8 detects the length in the width direction D2 of the sheet conveyed by the sheet feeding unit 2 based on the image data after the binarization process executed in the immediately preceding step S25. . Here, the process of step S <b> 27 is executed by the fifth detection unit 83 of the tab detection unit 8.

<Step S28>
In step S28, the tab detection unit 8 determines whether image data for one line in the main scanning direction has been input from the image reading unit 7 as in step S21.

  If the tab detection unit 8 determines that image data has been input from the image reading unit 7 (Yes in S28), the tab detection unit 8 shifts the processing to step S29. If no image data is input from the image reading unit 7 (No side in S28), the tab detection unit 8 waits for input of image data from the image reading unit 7 in step S28.

<Step S29>
In step S29, the tab detection unit 8 performs the binarization process on the image data for one line in the main scanning direction input from the image reading unit 7, as in step S22.

<Step S30>
In step S30, the tab detection unit 8 determines whether or not the first timing has been detected based on the image data after the binarization process executed in the immediately preceding step S29.

  Here, if the tab detection unit 8 determines that the first timing has been detected (Yes side of S30), the tab detection unit 8 shifts the processing to step S31. If the first timing is not detected (No side in S30), the tab detection unit 8 shifts the process to step S28.

<Step S31>
In step S31, the tab detection unit 8 notifies the control unit 9 of the detection of the first timing. Here, the process of detecting the first timing in step S30 and the process of step S31 are executed by the first detection unit 84 of the tab detection unit 8.

<Step S32>
In step S32, the tab detection unit 8 determines whether image data for one line in the main scanning direction has been input from the image reading unit 7 as in step S21.

  If the tab detection unit 8 determines that image data has been input from the image reading unit 7 (Yes in S32), the tab detection unit 8 shifts the process to step S33. If no image data is input from the image reading unit 7 (No in S32), the tab detection unit 8 waits for input of image data from the image reading unit 7 in step S32.

<Step S33>
In step S33, the tab detection unit 8 executes the binarization process on the image data for one line in the main scanning direction input from the image reading unit 7, as in step S22.

<Step S34>
In step S34, the tab detection unit 8 determines whether or not the second timing has been detected based on the image data after the binarization process executed in the immediately preceding step S33. Here, the process of detecting the second timing is executed by the second detection unit 85 of the tab detection unit 8.

  Here, if the tab detection unit 8 determines that the second timing has been detected (Yes in S34), the tab detection unit 8 shifts the processing to step S39. If the second timing has not been detected (No in S34), the tab detection unit 8 shifts the process to step S35.

<Step S35>
In step S35, the tab detection unit 8 executes the determination process based on the image data after the binarization process executed in the immediately preceding step S33.

<Step S36>
In step S36, the tab detection unit 8 determines whether the character size determined by the determination process executed in step S35 is smaller than the previous determination result.

  Specifically, the tab detection unit 8 determines the determination process when the character size determined by the determination process executed in step S35 is smaller than the character size indicated by the size information stored in the storage unit 861. It is determined that the character size determined by is decreased from the previous determination result. Note that if the size information is not stored in the storage unit 861, the tab detection unit 8 determines that the character size determined by the determination process executed in step S35 is not smaller than the previous determination result. to decide.

  If the tab detection unit 8 determines that the character size determined by the determination process has decreased from the previous determination result (Yes in S36), the tab detection unit 8 shifts the process to step S39. If the character size determined by the determination process is not smaller than the previous determination result (No in S36), the tab detection unit 8 shifts the process to step S37.

<Step S37>
In step S37, the tab detection unit 8 acquires the position information based on the image data after the binarization process executed in the immediately preceding step S33.

<Step S38>
In step S38, the tab detection unit 8 stores the size information indicating the character size determined by the determination process executed in step S35 and the position information acquired in step S37 in the storage unit 861. Execute the process.

<Step S39>
In step S <b> 39, the tab detection unit 8 executes the output process of outputting the position information and the size information stored in the storage unit 861 to the control unit 9. Here, the process of step S35-step S39 is performed by the 3rd detection part 86 of the tab detection part 8. FIG.

  Next, the operation of the tab detection unit 8 will be described with reference to FIG. Here, FIG. 6 is a diagram illustrating a part of the image data after the binarization process that is read from the sheet including the tab by the image reading unit 7 and is output by the binarization unit 81.

  Specifically, FIG. 6 shows line data L1 to L12. Here, each of the line data L1 to L12 is image data for one line in the main scanning direction. In FIG. 6, each pixel included in the image data is indicated by 1 indicating the presence of the sheet or 0 indicating the absence of the sheet. In FIG. 6, a thick line is drawn between a pixel having a pixel value of 0 and a pixel having a pixel value of 1 in order to make it easier to grasp the outline of the sheet.

  In the following description, it is assumed that there are 100 pixels between the pixel position X1 and the pixel position X8 in the main scanning direction (width direction D2) shown in FIG. In other words, it is assumed that the length in the main scanning direction in the sheet shown in FIG. 6 is the length of 100 pixels. Further, it is assumed that the reference value, the second threshold value, the third threshold value, and the fourth threshold value are 1, 50, 50, and 0, respectively. Further, it is assumed that the number of characters included in the heading information is 3.

  First, the fourth detection unit 82 executes a process for detecting the third timing.

  Specifically, when the line data L1 is input from the binarization unit 81, the fourth detection unit 82 counts the number of pixels whose density value is 1 included in the line data L1, and the number of the pixels is It is determined whether or not the second threshold value is exceeded. As shown in FIG. 6, the number of pixels having a density value of 1 included in the line data L1 is zero. Therefore, the fourth detection unit 82 determines that the number of pixels having a density value of 1 included in the line data L1 does not exceed the second threshold value. In this case, the fourth detection unit 82 does not detect the third timing.

  Further, when the line data L2 is input from the binarization unit 81, the fourth detection unit 82 counts the number of pixels whose density value is 1 included in the line data L2, and the number of the pixels is the first number. It is determined whether or not 2 threshold values are exceeded. As shown in FIG. 6, the number of pixels having a density value of 1 included in the line data L2 is 100. Therefore, the fourth detection unit 82 determines that the number of pixels having a density value of 1 included in the line data L2 exceeds the second threshold value. In this case, the fourth detection unit 82 detects the third timing. The fourth detection unit 82 notifies the fifth detection unit 83 of the detection of the third timing.

  Next, the fifth detection unit 83 detects the length of the sheet in the width direction D2.

  Specifically, when the fifth detection unit 83 is notified of the detection of the third timing by the fourth detection unit 82, the count value of the number of input image data (hereinafter referred to as “first count value”). Is set to 0. In addition, when the line data L3 is input from the binarization unit 81, the fifth detection unit 83 counts up the first count value and determines whether the first count value exceeds the reference value. To do. At this time, the first count value is 1. Therefore, the fifth detection unit 83 determines that the first count value does not exceed the reference value. In this case, the fifth detection unit 83 does not detect the length of the sheet in the width direction D2.

  In addition, when the line data L4 is input from the binarization unit 81, the fifth detection unit 83 counts up the first count value and determines whether the first count value exceeds the reference value. To do. At this time, the first count value is 2. Therefore, the fifth detection unit 83 determines that the first count value exceeds the reference value. In this case, the fifth detection unit 83 detects the length of the sheet in the width direction D2 based on the line data L4. As shown in FIG. 6, the number of pixels having a density value of 1 included in the line data L4 is 100. Therefore, the fifth detection unit 83 determines that the length of the sheet in the width direction D2 is the length of 100 pixels. Then, the fifth detection unit 83 notifies the first detection unit 84 of the detected length of the sheet in the width direction D2.

  Next, the first detection unit 84 executes a process for detecting the first timing.

  Specifically, when the line data L5 is input from the binarization unit 81, the first detection unit 84 counts the number of pixels whose density value is 1 included in the line data L5, and the fifth detection unit 83. It is determined whether or not the difference between the width of the sheet detected by the above and the number of the pixels exceeds the third threshold value. As shown in FIG. 6, the number of pixels having a density value of 1 included in the line data L5 is 100. Therefore, the first detection unit 84 determines that the difference between the sheet width detected by the fifth detection unit 83 and the number of pixels having a density value included in the line data L5 does not exceed the third threshold value. . In this case, the first detector 84 does not detect the first timing.

  Further, when the line data L6 is input from the binarization unit 81, the first detection unit 84 counts the number of pixels whose density value is 1 included in the line data L6, and the fifth detection unit 83 detects the number of pixels. It is determined whether or not the difference between the width of the applied sheet and the number of the pixels exceeds the third threshold value. As shown in FIG. 6, the number of pixels having a density value of 1 included in the line data L6 is 14. Therefore, the first detection unit 84 determines that the difference between the sheet width detected by the fifth detection unit 83 and the number of pixels having a density value included in the line data L5 exceeds the third threshold. In this case, the first detection unit 84 detects the first timing. The first detection unit 84 notifies the control unit 9, the second detection unit 85, and the third detection unit 86 of the detection of the first timing.

  Next, a process for detecting the second timing is executed by the second detection unit 85, and a process for detecting the positions of both ends in the width direction D2 of the tab is executed by the third detection unit 86. .

  Specifically, when the line data L7 is input from the binarization unit 81, the second detection unit 85 counts the number of pixels whose density value is 1 included in the line data L7, and the number of the pixels is It is determined whether it is equal to or less than the fourth threshold value. As shown in FIG. 6, the number of pixels having a density value of 1 included in the line data L7 is 14. Therefore, the second detection unit 85 determines that the number of pixels having a density value of 1 included in the line data L7 is not less than or equal to the fourth threshold value. In this case, the second detection unit 85 does not detect the second timing. Then, the second detection unit 85 notifies the third detection unit 86 that the second timing has not been detected.

  On the other hand, when the third detector 86 is notified of the detection of the first timing from the first detector 84, the count value of the number of input image data (hereinafter referred to as “second count value”) is set to 1. Set to. Further, when the line data L7 is input from the binarization unit 81, the third detection unit 86 counts up the second count value. And if the 3rd detection part 86 is notified from the 2nd detection part 85 that the said 2nd timing is not detected, the line data L7, the said 2nd count value, and the character contained in the said heading information The determination process is executed based on the number of characters. In this determination processing, the length in the width direction D2 is 14 pixels (the number of pixels whose density value is 1 included in the line data L7), and the length in the transport direction D1 is 2 pixels (the second count value). Printable area A1 (see FIG. 6) is defined. In FIG. 6, the printable area A1 is shown as an area surrounded by a one-dot chain line. Further, in this determination process, it is determined that a square region having one side of the length of two pixels is the maximum size of the print character. The third detection unit 86 determines whether or not the character size determined by the determination process is smaller than the previous determination result based on the size information stored in the storage unit 861 after the determination process is executed. Judging. At this time, the size information is not stored in the storage unit 861. Therefore, the third detection unit 86 determines that the character size determined by the determination process does not decrease from the previous determination result, and executes the storage process. In this storage processing, the position information having the pixel position X2 and the pixel position X7 as the positions of both ends in the width direction D2 of the tab, and a square area having a length of two pixels as one side are set as the character size. The size information is stored in the storage unit 861.

  Further, when the line data L8 is input from the binarization unit 81, the second detection unit 85 counts the number of pixels whose density value is 1 included in the line data L8, and the number of the pixels is the first number. It is determined whether or not the threshold value is 4 or less. As shown in FIG. 6, the number of pixels having a density value of 1 included in the line data L8 is twelve. Therefore, the second detection unit 85 determines that the number of pixels having a density value of 1 included in the line data L8 is not less than or equal to the fourth threshold value. In this case, the second detection unit 85 does not detect the second timing. Then, the second detection unit 85 notifies the third detection unit 86 that the second timing has not been detected.

  On the other hand, when the line data L8 is input from the binarization unit 81, the third detection unit 86 counts up the second count value. And if the 3rd detection part 86 is notified from the 2nd detection part 85 that the said 2nd timing is not detected, line data L8, the said 2nd count value, and the character contained in the said heading information The determination process is executed based on the number of characters. In this determination process, the length in the width direction D2 is 12 pixels (the number of pixels whose density value is 1 included in the line data L8), and the length in the transport direction D1 is 3 pixels (the second count value). The printable area) is defined. Further, in this determination process, it is determined that a square area having a length of three pixels on one side is the maximum size of the print character. The third detection unit 86 determines whether or not the character size determined by the determination process is smaller than the previous determination result based on the size information stored in the storage unit 861 after the determination process is executed. Judging. At this time, the character size indicated by the size information stored in the storage unit 861 is a square area having a side corresponding to the length of two pixels. Therefore, the third detection unit 86 determines that the character size determined by the determination process does not decrease from the previous determination result, and executes the storage process. In this storage process, the position information having the pixel position X3 and the pixel position X6 as the positions of both ends in the width direction D2 of the tab, and a square area having a length of three pixels as one side are set as the character size. The size information is stored in the storage unit 861.

  In addition, when the line data L9 is input from the binarization unit 81, the second detection unit 85 counts the number of pixels whose density value is 1 included in the line data L9, and the number of pixels is the first number. It is determined whether or not the threshold value is 4 or less. As shown in FIG. 6, the number of pixels having a density value of 1 included in the line data L9 is 12. Therefore, the second detection unit 85 determines that the number of pixels having a density value of 1 included in the line data L9 is not less than or equal to the fourth threshold value. In this case, the second detection unit 85 does not detect the second timing. Then, the second detection unit 85 notifies the third detection unit 86 that the second timing has not been detected.

  On the other hand, when the line data L9 is input from the binarization unit 81, the third detection unit 86 counts up the second count value. And if the 3rd detection part 86 is notified from the 2nd detection part 85 that the said 2nd timing is not detected, line data L9, the said 2nd count value, and the character contained in the said heading information The determination process is executed based on the number of characters. In this determination processing, the length in the width direction D2 is 12 pixels (the number of pixels whose density value is 1 included in the line data L9), and the length in the transport direction D1 is 4 pixels (the second count value). Printable area A2 (see FIG. 6) is defined. In FIG. 6, the printable area A2 is shown as an area surrounded by a two-dot chain line. Further, in this determination process, it is determined that a square area having a length of four pixels as one side is the maximum size of the print character. The third detection unit 86 determines whether or not the character size determined by the determination process is smaller than the previous determination result based on the size information stored in the storage unit 861 after the determination process is executed. Judging. At this time, the character size indicated by the size information stored in the storage unit 861 is a square region having a length of three pixels as one side. Therefore, the third detection unit 86 determines that the character size determined by the determination process does not decrease from the previous determination result, and executes the storage process. In this storing process, the position information having the pixel position X3 and the pixel position X6 as the positions of both ends in the width direction D2 of the tab, and a square area having a length of four pixels as one side are set as the character size. The size information is stored in the storage unit 861.

  Further, when the line data L10 is input from the binarization unit 81, the second detection unit 85 counts the number of pixels whose density value is 1 included in the line data L10, and the number of the pixels is the first number. It is determined whether or not the threshold value is 4 or less. As shown in FIG. 6, the number of pixels having a density value of 1 included in the line data L10 is ten. Therefore, the second detection unit 85 determines that the number of pixels having a density value of 1 included in the line data L10 is not less than or equal to the fourth threshold value. In this case, the second detection unit 85 does not detect the second timing. Then, the second detection unit 85 notifies the third detection unit 86 that the second timing has not been detected.

  On the other hand, when the line data L10 is input from the binarization unit 81, the third detection unit 86 counts up the second count value. And if the 3rd detection part 86 is notified from the 2nd detection part 85 that the said 2nd timing is not detected, line data L10, the said 2nd count value, and the character contained in the said headline information The determination process is executed based on the number of characters. In this determination processing, the length in the width direction D2 is 10 pixels (the number of pixels whose density value is 1 included in the line data L10), and the length in the transport direction D1 is 5 pixels (the second count value). The printable area) is defined. Further, in this determination process, it is determined that a square area having a length of three pixels as one side is the maximum size of a print character. The third detection unit 86 determines whether or not the character size determined by the determination process is smaller than the previous determination result based on the size information stored in the storage unit 861 after the determination process is executed. Judging. At this time, the character size indicated by the size information stored in the storage unit 861 is a square area having a length of four pixels as one side. Therefore, the third detection unit 86 determines that the character size determined by the determination process is smaller than the previous determination result, and executes the output process. By this output processing, the position information stored in the storage unit 861 with the pixel position X3 and the pixel position X6 as the positions of both ends in the width direction D2 of the tab, and the length of four pixels are defined as one side. The size information in which the square area is set to the character size is output to the control unit 9.

  Note that the second detection unit 85 may not execute the process of detecting the second timing after the output process is executed by the third detection unit 86.

  As described above, in the image forming apparatus 10, the tab included in the sheet is detected based on the image data read from the sheet conveyed by the sheet feeding unit 2, and is input in advance to the detected tab. The heading information is printed. Therefore, it is possible to reduce the user's trouble that occurs when printing on the tab.

  Further, in the image forming apparatus 10, the tab included in the sheet is detected in a simplified shape within a range necessary for printing the heading information. Specifically, in the image forming apparatus 10, the tab is detected as a long rectangular region along the width direction D2. Thereby, the structure of the tab detection part 8 can be simplified.

  In the image forming apparatus 10, the position of both ends of the printable area in the width direction D <b> 2 is indicated at the timing when the aspect ratio of the printable area is closest to the aspect ratio of the character string included in the heading information. The position information is output to the control unit 9. For this reason, when the tab is a trapezoidal region, the position information acquired immediately before the second timing is detected is output to the control unit 9 and printed on the tab. It is possible to increase the character size. In addition, the position information acquired immediately after the first timing is detected is printed on the tab when the tab is a trapezoidal area as compared with the configuration in which the position information is output to the control unit 9. It is possible to prevent characters from protruding from the tab.

  Note that the tab detection unit 8 may detect the tab based on an image of a sheet conveyed in a posture in which the protruding direction of the tab faces the downstream side of the conveyance direction D1. In this case, the tab detection unit 8 may not include the fourth detection unit 82 and the fifth detection unit 83. The first detection unit 84 detects the first timing based on the number of pixels having a density value of 1 included in the image data for one line in the main scanning direction output from the binarization unit 81. It's okay. The second detection unit 85 has a density value of 1 included in the image data for one line in the main scanning direction output from the binarization unit 81 after the first timing is detected by the first detection unit 84. The second timing may be detected based on the number of pixels.

DESCRIPTION OF SYMBOLS 1 Paper feed cassette 2 Paper feed part 3 Image formation part 4 Ink container part 5 Conveyance unit 6 Paper discharge part 7 Image reading part 8 Tab detection part 9 Control part 10 Image forming apparatus 71 Line sensor 72 AFE circuit 81 Binarization part 82 4th detection part 83 5th detection part 84 1st detection part 85 2nd detection part 86 3rd detection part 91 Image formation process part

Claims (7)

An image reading unit that reads an image of a sheet conveyed along the conveyance path at a reading position upstream in the sheet conveyance direction from the image formation position in the sheet conveyance path passing through the image formation position;
A tab detection unit for detecting a tab included in the sheet based on the image of the sheet read at the reading position;
An image forming processor that forms an image on the tab detected by the tab detector;
An image forming apparatus comprising: The image reading unit outputs image data for one line along the width direction of the sheet orthogonal to the conveyance direction at predetermined intervals,
The tab detector is
A first detection unit that detects a first timing at which a tip portion of the tab in the transport direction passes the reading position based on the image data output from the image reading unit;
Based on the image data output from the image reading unit after the first timing is detected by the first detection unit, a second timing at which a rear end portion in the transport direction of the tab passes the reading position is detected. A second detector that
A third detection unit for detecting positions of both ends of the tab in the width direction based on the image data output from the image reading unit at the time of detection of the first timing by the first detection unit or after detection; ,including,
The image forming apparatus according to claim 1. If the second timing is not detected based on the image data output from the image reading unit, the third detection unit is positioned at both ends in the width direction of the tab acquired based on the image data. When the second timing is detected based on the image data output from the image reading unit, the storage stored in the storage unit is executed. Execute the output process to output the position information that is the latest storage timing in the unit,
The image forming apparatus according to claim 2. The third detection unit, when the second timing is not detected based on the image data output from the image reading unit, the image data and the image by the image reading unit from the time of detection of the first timing. A determination process for determining a maximum size of a print character that can print predetermined heading information in a printable area defined based on the number of data outputs is executed, and the character size determined by the determination process is the immediately preceding character size. If the determination result does not decrease, the storage process is executed, and if the character size determined by the determination process is smaller than the previous determination result, the output process is executed.
The image forming apparatus according to claim 3. The storage process is a process of storing size information indicating a character size determined by the determination process together with the position information in the storage unit,
The output process is a process of outputting the position information and the size information with the latest storage timing stored in the storage unit.
The image forming apparatus according to claim 4. The tab detector is
A binarization unit that binarizes each pixel included in the image data output from the image reading unit;
The first detection unit, the second detection unit, and the third detection unit execute processing based on the image data after binarization by the binarization unit,
The image forming apparatus according to claim 2. Reading an image of a sheet conveyed along the conveyance path at a reading position upstream in the sheet conveyance direction from the image formation position in the sheet conveyance path passing through the image formation position;
Detecting a tab included in the sheet based on an image of the sheet read at the reading position;
Forming an image on the detected tab;
An image forming method comprising:

Images