Image forming apparatus and image forming method

Abstract

To provide an image forming apparatus capable of forming an image on which an inclination of an imaging portion is reflected, and an image forming method.SOLUTION: An image forming apparatus includes an image forming unit 3 that forms an image on a sheet conveyed along a predetermined conveyance path, and a line sensor 51 that is provided on an upstream side of an image forming unit 3 in a conveyance direction D11 of the sheet in the conveyance path so as to be long along a widthwise direction D12, and captures an image of the sheet. The image forming apparatus forms an image reflected with an inclination of the line sensor 51 on a specific sheet based on shape data indicating a shape of the specific sheet acquired using the line sensor 51.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus and an image forming method. [Background technology]

[0002] There is known an image forming apparatus that includes an imaging unit such as a line sensor that captures an image of a sheet being conveyed through an image forming position by an image forming unit. Also, there is known a related art image forming apparatus that can detect the inclination of the imaging unit with respect to the width direction based on the imaging result of a mark image that is elongated in the width direction perpendicular to the conveying direction of the sheet and is formed on a conveying belt used to convey the sheet (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-25697 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the image forming apparatus according to the related art, when the axis of the tension roller that stretches the conveyor belt is inclined with respect to the width direction, the mark image is inclined with respect to the width direction. Therefore, in the image forming apparatus according to the related art, when the axis of the tension roller is inclined with respect to the width direction, the inclination of the imaging unit with respect to the width direction is not reflected in the imaging result by the imaging unit.

[0005] SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus and an image forming method that are capable of forming an image that reflects the tilt of an imaging unit. [Means for solving the problem]

[0006] According to one aspect of the present invention, an image forming apparatus includes an image forming unit, an imaging unit, a conveying processing unit, an acquisition processing unit, a mask processing unit, and a formation processing unit. The image forming unit forms an image on a sheet conveyed along a predetermined conveying path. The imaging unit is disposed upstream of the image forming unit in the conveying direction of the sheet and elongated along a width direction perpendicular to the conveying direction, and images the sheet. The conveying processing unit conveys a predetermined specific sheet along the conveying path. The acquisition processing unit uses the imaging unit to acquire shape data indicating the shape of the specific sheet conveyed by the conveying processing unit. The mask processing unit uses the shape data acquired by the acquisition processing unit to mask a protruding area that protrudes from the sheet area in specific image data that is larger in size in a first direction corresponding to the conveying direction than the sheet area included in the shape data. The formation processing unit forms an image on the specific sheet that indicates a boundary between a masked area and an unmasked area that face each other along the first direction in the specific image data in which the protruding area has been masked by the mask processing unit.

[0007] An image forming method according to another aspect of the present invention is executed by an image forming apparatus including an image forming unit that forms an image on a sheet transported along a predetermined transport path, and an imaging unit that is disposed upstream of the image forming unit in the transport path in the sheet transport direction and extends elongately along a width direction perpendicular to the transport direction, and that images the sheet. The image forming method includes a transport step, an acquisition step, a masking step, and a forming step. In the transport step, a predetermined specific sheet is transported along the transport path. In the acquisition step, the imaging unit is used to acquire shape data indicating the shape of the specific sheet transported in the transport step. In the masking step, the shape data acquired in the acquisition step is used to mask a protruding area of specific image data that is larger in a first direction corresponding to the transport direction than the sheet area included in the shape data. In the forming step, an image indicating a boundary between a masked area and an unmasked area that face each other along the first direction of the specific image data in which the protruding area has been masked in the masking step is formed on the specific sheet. [Effects of the Invention]

[0008] According to the present invention, it is possible to form an image that reflects the tilt of the imaging unit. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a cross-sectional view showing the configuration of an image forming apparatus according to an embodiment of the present invention. [Figure 2] FIG. 2 is a plan view showing the configuration of the image forming section, the transport unit, and the line sensor in the image forming apparatus according to the embodiment of the present invention. [Figure 3] FIG. 3 is a block diagram showing the system configuration of the image forming apparatus according to the embodiment of the present invention. [Figure 4] FIG. 4 is a flowchart showing an example of the tilt reflection image forming process executed by the image forming apparatus according to the embodiment of the present invention. [Figure 5]FIG. 5 is a diagram showing an example of shape data acquired by the image forming apparatus according to the embodiment of the present invention. [Figure 6] FIG. 6 is a diagram showing an example of shape data acquired by the image forming apparatus according to the embodiment of the present invention. [Figure 7] FIG. 7 is a diagram showing an example of specific image data to be masked in the image forming apparatus according to the embodiment of the present invention. [Figure 8] FIG. 8 is a diagram showing an example of specific image data masked by the image forming apparatus according to the embodiment of the present invention. [Figure 9] FIG. 9 is a diagram showing an example of an image formed on a specific sheet by the image forming apparatus according to the embodiment of the present invention. [Figure 10] FIG. 10 is a diagram showing an example of an image formed on a specific sheet by the image forming apparatus according to the embodiment of the present invention. [Figure 11] FIG. 11 is a block diagram showing the system configuration of an image forming apparatus according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. Note that the following embodiment is an example of a specific embodiment of the present invention and does not limit the technical scope of the present invention.

[0011] [Configuration of image forming apparatus 100] First, the configuration of an image forming apparatus 100 according to an embodiment of the present invention will be described with reference to Figures 1 to 3. In Figure 1, a sheet transport path R11 is indicated by a two-dot chain line.

[0012] Image forming apparatus 100 is a printer capable of forming an image on a sheet using an inkjet method. The present invention may also be applied to a fax machine, a copier, or a multifunction peripheral capable of forming an image on a sheet using an inkjet method. The present invention may also be applied to an image forming apparatus capable of forming an image on a sheet using a method other than the inkjet method, such as an electrophotographic method.

[0013] 1, the image forming apparatus 100 includes a housing 1, a sheet conveying section 2, an image forming section 3, a conveying unit 4, and a shape reading section 5. The image forming apparatus 100 also includes an operation display section 6, a control section 7, and an image processing section 8 shown in FIG.

[0014] The housing 1 houses each component of the image forming apparatus 100. A paper feed cassette 11 (see FIG. 1) is removably provided in the housing 1. The paper feed cassette 11 stores sheets on which images are to be formed. A paper output tray 12 (see FIG. 1) is provided on the outer surface of the housing 1. Sheets on which images are formed by the image forming unit 3 are discharged to the paper output tray 12. Inside the housing 1, the sheets stored in the paper feed cassette 11 are transported along a sheet transport path R11 (see FIG. 1) that passes through an image formation position by the image forming unit 3 and reaches the paper output tray 12.

[0015] The sheet transport unit 2 transports sheets stored in the paper feed cassette 11 along a sheet transport path R11 (see FIG. 1). As shown in FIG. 1, the sheet transport unit 2 includes a pickup roller 21 and multiple transport rollers 22. The pickup roller 21 picks up the top sheet of the stack of sheets stored in the paper feed cassette 11 and sends the sheet to the sheet transport path R11. The multiple transport rollers 22 are arranged side by side along the sheet transport path R11. Each transport roller 22 transports the sheet along the sheet transport path R11. Each transport roller 22 transports the sheet in a transport direction D11 (see FIG. 1) from the paper feed cassette 11 to the paper output tray 12.

[0016] The image forming unit 3 forms an image on a sheet transported along a sheet transport path R11 (see FIG. 1) (one example of a transport path of the present invention). As shown in FIG. 1, the image forming unit 3 includes line heads 31 to 34 and a head frame 35.

[0017] 2, each of the line heads 31 to 34 is elongated in a width direction D12 perpendicular to the conveying direction D11. Specifically, each of the line heads 31 to 34 has a length in the width direction D12 corresponding to the width of the largest size sheet that can be accommodated in the paper feed cassette 11. The line heads 31 to 34 are arranged side by side at equal intervals along the conveying direction D11.

[0018] As shown in FIG. 2, each of the line heads 31 to 34 has a plurality of recording heads 30. Each of the recording heads 30 ejects ink toward a sheet transported by the transport unit 4. Each of the recording heads 30 provided in the line head 31 ejects black ink. Each of the recording heads 30 provided in the line head 32 ejects cyan ink. Each of the recording heads 30 provided in the line head 33 ejects magenta ink. Each of the recording heads 30 provided in the line head 34 ejects yellow ink.

[0019] Each of the recording heads 30 includes a plurality of nozzles 30A (see FIG. 2) that eject ink. The plurality of nozzles 30A are provided on the surface of the recording head 30 that faces the sheet transported by the transport unit 4.

[0020] Each recording head 30 also includes a pressure chamber (not shown), a piezoelectric element (not shown), and an individual flow path (not shown) corresponding to each nozzle 30A. The pressure chamber communicates with the nozzle 30A and stores ink. The piezoelectric element ejects ink from the nozzle 30A in response to application of a predetermined drive voltage. The individual flow path is an ink flow path provided between the pressure chamber and a common flow path (not shown) shared by the multiple nozzles 30A. A plurality of the individual flow paths corresponding to the multiple nozzles 30A are connected to the common flow path. The common flow path is connected to an ink supply unit (not shown) that supplies ink to each of the pressure chambers.

[0021] 2, the line head 31 includes three recording heads 30 arranged in a staggered pattern along the width direction D12. Similarly to the line head 31, each of the other line heads 32 to 34 also includes three recording heads 30 arranged in a staggered pattern along the width direction D12.

[0022] The head frame 35 supports the line heads 31 to 34. The head frame 35 is supported by the housing 1. The number of line heads provided in the image forming unit 3 does not have to be four. Also, the number of recording heads 30 provided in each of the line heads 31 to 34 does not have to be three.

[0023] The image forming unit 3 forms an image on a sheet based on image data input from the image processing unit 8. Specifically, the image forming unit 3 controls the ejection of ink from each of the line heads 31 to 34 based on the image data input from the image processing unit 8.

[0024] As shown in FIG. 1, the transport unit 4 is disposed below the line heads 31 to 34. The transport unit 4 transports a sheet while facing the recording head 30. For example, the transport unit 4 transports the sheet by a predetermined transport distance each time the recording head 30 ejects ink. The transport unit 4 also stops transporting the sheet while the recording head 30 is ejecting ink. As shown in FIG. 1, the transport unit 4 includes a transport belt 41 on which the sheet is placed, a first tension roller 42, a second tension roller 43, and a third tension roller 44 that tension the transport belt 41, and a transport frame 45 that supports these. The gap between the transport belt 41 and the recording head 30 is adjusted so that the gap between the surface of the sheet and the recording head 30 during image formation is a predetermined distance (for example, 1 mm).

[0025] The first tension roller 42 is rotationally driven by a rotational driving force supplied from a motor (not shown). As a result, the conveyor belt 41 rotates in a direction that allows the sheet to be conveyed in the conveying direction D11 (see FIG. 1). The conveying unit 4 is also provided with a suction unit (not shown) that sucks air through a number of through holes formed in the conveyor belt 41 to attract the sheet to the conveyor belt 41.

[0026] The shape reading unit 5 reads the shape of the sheet being conveyed along the sheet conveying path R11.

[0027] As shown in FIG. 3, the shape reading unit 5 includes a line sensor 51 and an AFE (analog front end) circuit 52.

[0028] As shown in FIG. 1, the line sensor 51 is provided on the sheet transport path R11 upstream of the image forming unit 3 in the sheet transport direction D11. The line sensor 51 is also provided above the transport belt 41. As shown in FIG. 2, the line sensor 51 is provided elongated along the width direction D12 perpendicular to the transport direction D11. The line sensor 51 captures an image of the sheet transported along the sheet transport path R11. The line sensor 51 is an example of an imaging unit of the present invention.

[0029] For example, the line sensor 51 is a CIS (contact image sensor). The line sensor 51 includes multiple imaging elements arranged side by side in the width direction D12 (see FIG. 2). Each of the imaging elements includes a light-emitting unit and a light-receiving unit. The light-emitting unit emits light toward the conveyor belt 41. The light-receiving unit is configured to receive light emitted from the light-emitting unit and reflected by the conveyor belt 41 or the conveyed sheet, and outputs an analog electrical signal corresponding to the amount of received light. The line sensor 51 captures an image of the sheet conveyed along the sheet conveyance path R11 at a predetermined imaging cycle. Specifically, the line sensor 51 outputs an analog electrical signal corresponding to an image of the object (sheet and conveyor belt 41) facing the line sensor 51 at the imaging cycle. The outer circumferential surface of the conveyor belt 41 is colored, such as black, to suppress reflection of light emitted from the light-emitting unit compared to the background color (white) of the sheet.

[0030] The AFE circuit 52 is an electronic circuit that performs predetermined processing on the analog electrical signal output from the line sensor 51. Specifically, the AFE circuit 52 includes a signal conversion unit that converts the analog electrical signal output from the line sensor 51 into a digital electrical signal (image data). The AFE circuit 52 also includes a binarization unit that performs binarization processing on the image data output from the signal conversion unit. The binarization processing is a process of binarizing each pixel included in the image data output from the signal conversion unit into a value that indicates the presence or absence of a sheet. The image data binarized by the binarization unit (hereinafter referred to as "line data") is input to the image processing unit 8.

[0031] The operation display unit 6 is a user interface of the image forming apparatus 100. The operation display unit 6 includes a display unit and an operation unit. The display unit displays various information in response to control instructions from the control unit 7. For example, the display unit is a flat panel display such as a liquid crystal display. The operation unit inputs various information to the control unit 7 in response to user operations. For example, the operation unit includes operation keys and a touch panel.

[0032] The control unit 7 performs overall control of the image forming apparatus 100. As shown in FIG. 3, the control unit 7 includes a CPU 61, a ROM 62, and a RAM 63. The CPU 61 is a processor that executes various types of arithmetic processing. The ROM 62 is a non-volatile storage device that stores in advance information such as control programs for causing the CPU 61 to execute various types of processing. The RAM 63 is a volatile or non-volatile storage device that is used as a temporary storage memory (work area) for the various types of processing executed by the CPU 61. The CPU 61 performs overall control of the image forming apparatus 100 by executing the various control programs that are stored in advance in the ROM 62.

[0033] The image processing unit 8 adjusts the image data input to the image forming unit 3, i.e., the image data used to form an image on a sheet, based on the image data input from the shape reading unit 5. For example, the image processing unit 8 masks, based on the image data input from the shape reading unit 5, a portion of the image data input to the image forming unit 3 that is used to form an image on the outside of the sheet transported along the sheet transport path R11. This prevents ink from being ejected onto the outside of the sheet. The image processing unit 8 is composed of electronic circuits such as integrated circuits (ASIC, DSP).

[0034] Incidentally, an image forming device capable of detecting the inclination of a line sensor 51 relative to the width direction D12 based on the imaging results of a mark image formed on a conveying belt 41 that is long in the width direction D12 by the line sensor 51 is known as related technology.

[0035] However, in the image forming apparatus according to the related art described above, when the axis of the tension roller that stretches the conveyor belt 41 is inclined with respect to the width direction D12, the mark image is inclined with respect to the width direction D12. Therefore, in the image forming apparatus according to the related art described above, when the axis of the tension roller is inclined with respect to the width direction D12, the inclination of the line sensor 51 with respect to the width direction D12 is not reflected in the imaging result by the line sensor 51.

[0036] In contrast to this, the image forming apparatus 100 according to the embodiment of the present invention is capable of forming an image that reflects the inclination of the line sensor 51, as will be described below.

[0037] 3, the control unit 7 includes a transport processing unit 64 and a formation processing unit 65. Specifically, the CPU 61 of the control unit 7 executes the control program stored in the ROM 62 to function as the transport processing unit 64 and the formation processing unit 65. Note that the transport processing unit 64 and the formation processing unit 65 may be realized by electronic circuits.

[0038] 3, the image processing unit 8 includes an acquisition processing unit 71 and a mask processing unit 72. The CPU 61 of the control unit 7 may execute the control program stored in the ROM 62 to function as each of the above-mentioned processing units.

[0039] The conveying processing unit 64 performs a conveying process to convey a predetermined specific sheet SH10 (see FIG. 9) along the sheet conveying path R11. Here, the specific sheet SH10 is a sheet of a predetermined size. For example, the specific sheet SH10 is a sheet that is long in the width direction D12.

[0040] For example, the conveyance processing unit 64 displays a guide screen on the operation display unit 6 in response to a predetermined user operation on the operation display unit 6. The guide screen includes a message urging the user to place the specific sheet SH10 in the paper feed cassette 11. The guide screen also includes an execution key used to perform the conveyance processing.

[0041] Then, when the user operates the execution key, the conveying processing unit 64 executes the conveying process. In the conveying process, the sheet conveying unit 2 and the conveying unit 4 are used to convey the specific sheet SH10 along the sheet conveying path R11.

[0042] The acquisition processing unit 71 uses the line sensor 51 to acquire shape data X10 (see FIG. 5) that indicates the shape of the specific sheet SH10 conveyed by the conveyance processing unit 64.

[0043] For example, when the leading edge of the specific sheet SH10 is detected by a sheet sensor (not shown) provided upstream of the line sensor 51 in the sheet conveying path R11 (see FIG. 1) in the conveying direction D11, the acquisition processing unit 71 causes the shape reading unit 5 to start reading the shape of the specific sheet SH10. This causes the shape reading unit 5 to output the line data at the imaging cycle. Furthermore, the acquisition processing unit 71 causes the shape reading unit 5 to end reading the shape of the specific sheet SH10 when a predetermined time has elapsed since the sheet sensor detected the trailing edge of the specific sheet SH10. The specific time is set so that reading of the shape of the specific sheet SH10 by the shape reading unit 5 ends after the trailing edge of the specific sheet SH10 passes a position facing the line sensor 51. The acquisition processing unit 71 then acquires each of the line data output from the shape reading unit 5 while the shape reading unit 5 is reading the shape of the specific sheet SH10. That is, the shape data X10 is data configured from a plurality of line data output from the shape reading unit 5 while the shape reading unit 5 is reading the shape of the specific sheet SH10.

[0044] An example of shape data X10 is shown in Fig. 5. The shape data X10 shown in Fig. 5 is shape data X10 acquired by the acquisition processing unit 71 when a specific sheet SH10 is tilted with respect to the width direction D12 and the line sensor 51 is not tilted with respect to the width direction D12. The shape data X10 includes a sheet area X11 indicating the specific sheet SH10. The sheet area X11 is an area formed by pixels indicating the presence of a sheet. The outside of the sheet area X11 in the shape data X10 is formed by pixels indicating the absence of a sheet.

[0045] 6 shows another example of the shape data X10. The shape data X10 shown in FIG. 6 is the shape data X10 acquired by the acquisition processing unit 71 when the specific sheet SH10 is not tilted with respect to the width direction D12 and the line sensor 51 is tilted with respect to the width direction D12 as shown in FIG. 2. The first direction D13 shown in FIGS. 5 and 6 corresponds to the conveying direction D11 (see FIG. 2). The second direction D14 shown in FIGS. 5 and 6 corresponds to the width direction D12 (see FIG. 2).

[0046] 5, when the specific sheet SH10 is inclined with respect to the width direction D12, the leading edge and trailing edge of the sheet area X11 in the first direction D13 become non-parallel to the second direction D14. Also, as shown in FIG. 6, when the line sensor 51 is inclined with respect to the width direction D12, the leading edge and trailing edge of the sheet area X11 in the first direction D13 become non-parallel to the second direction D14. In other words, both the amount of inclination of the specific sheet SH10 with respect to the width direction D12 and the amount of inclination of the line sensor 51 with respect to the width direction D12 are reflected in the amount of inclination of the leading edge and trailing edge of the sheet area X11 in the first direction D13 with respect to the second direction D14, which is included in the shape data X10.

[0047] The mask processing unit 72 uses the shape data X10 (see Figure 5) acquired by the acquisition processing unit 71 to perform masking processing to mask the protruding area of specific image data Y10 (see Figure 7) that is larger in size in the first direction D13 corresponding to the conveying direction D11 than the sheet area X11.

[0048] For example, when the shape data X10 is superimposed on the specific image data Y10 so that the first reference position in the specific image data Y10 coincides with the second reference position in the shape data X10, the mask processing unit 72 determines the area outside the area that overlaps with the sheet area X11 in the specific image data Y10 as the protruding area.

[0049] For example, the first reference position is the center in the first direction D13 and the center in the second direction D14 in the specified image data Y10, and the second reference position is the center in the first direction D13 and the center in the second direction D14 in the shape data X10.

[0050] For example, the specified image data Y10 is data of the same size as the shape data X10. Note that the specified image data Y10 may be data of a different size from the shape data X10.

[0051] For example, if a pixel in the protruding area in the specified image data Y10 is a pixel of a color other than white, the mask processing unit 72 replaces the pixel with a white pixel to mask the protruding area.

[0052] For example, the mask processing unit 72 performs the masking process on a plurality of pixel rows along the second direction D14 included in the specified image data Y10, in order along the first direction D13, starting from the pixel row that is furthest downstream in the first direction D13. Specifically, each time the acquisition processing unit 71 acquires the line data, the mask processing unit 72 determines the protruding area included in the pixel row based on the acquired line data, and masks the determined protruding area.

[0053] FIG. 7 shows an example of the specific image data Y10. In FIG. 7, the area of the specific image data Y10 that overlaps with the sheet area X11 is indicated by a two-dot chain line. The specific image data Y10 has a colored area Y11. The colored area Y11 is positioned so as to overlap with the end of the specific image data Y10 in the sheet area X11 along the fourth direction D22 (an example of the second direction of the present invention) along the first direction D13, based on the distance between the sheet sensor and the line sensor 51 in the sheet transport path R11 (see FIG. 1) and the sheet transport speed. The fourth direction D22 is the direction opposite to the first direction D13. The colored area Y11 is formed in a long strip shape in the second direction D14. The colored area Y11 has a pair of protrusions that protrude downstream in the first direction D13 from both ends of the strip in the second direction D14. The colored area Y11 is an image of a size that fits inside the specific sheet SH10. The colored area Y11 is disposed in the center of the specific image data Y10 in the second direction D14. For example, the colored area Y11 is a black-colored area. The area outside the colored area Y11 in the specific image data Y10 is a colorless area. In other words, the area outside the colored area Y11 in the specific image data Y10 is formed by white pixels. The colored area Y11 may be disposed in a position overlapping with the end of the specific image data Y10 on the side of the sheet area X11 in the third direction D21 (another example of the second direction of the present invention), which is opposite to the fourth direction D22. The colored area Y11 may also occupy the entire specific image data Y10. The color of the colored area Y11 is not limited to black, and may be any color other than white.

[0054] Fig. 8 also shows an example of specific image data Y10 in which the protruding region has been masked by the mask processing unit 72. In Fig. 8, a masked region Y12 of the colored region Y11 that has been masked by the mask processing unit 72 is shown by a dotted line. In Fig. 8, a non-masked region Y13 of the colored region Y11 that has not been masked by the mask processing unit 72 is shown by a solid line.

[0055] 7 and 8, the mask processing unit 72 masks the protruding area in the specified image data Y10, so that the shape of the end portion of the sheet area X11 on the fourth direction D22 side (see FIGS. 5 and 6) appears as the boundary between the masked area Y12 and the non-masked area Y13. That is, the end portion Y14 (see FIG. 8) on the fourth direction D22 side of the non-masked area Y13 has the same shape as the end portion of the sheet area X11 on the fourth direction D22 side. Therefore, the amount of tilt of the end portion Y14 with respect to the second direction D14 reflects both the amount of tilt of the specified sheet SH10 with respect to the width direction D12 and the amount of tilt of the line sensor 51 with respect to the width direction D12.

[0056] The forming processing unit 65 forms on a specific sheet SH10 an image showing the boundary between the masked area and the non-masked area that face each other along the first direction D13 from the specific image data Y10 (see Figure 8) in which the protruding area has been masked by the mask processing unit 72.

[0057] For example, the formation processing unit 65 forms, on the specified sheet SH10, the non-mask area Y13 (see FIG. 8) of the color area Y11 included in the specified image data Y10.

[0058] For example, the formation processing unit 65 inputs the plurality of pixel rows along the second direction D14 included in the specific image data Y10 in which the protrusion area has been masked to the image forming unit 3 in order along the first direction D13, starting from the pixel row furthest downstream in the first direction D13. The formation processing unit 65 also starts inputting each of the pixel rows to the image forming unit 3 at a predetermined input timing. The input timing is set so that the entire non-masked area Y13 is formed on the specific sheet SH10. As a result, in the image forming unit 3, each time the pixel row is input, the ink ejection by the line head 31 is controlled based on the input pixel row, and the non-masked area Y13 is formed on the specific sheet SH10.

[0059] Fig. 9 shows an example of a non-mask area Y13 formed on a specific sheet SH10 by the forming processing unit 65. Specifically, Fig. 9 shows the non-mask area Y13 formed on a specific sheet SH10 by the forming processing unit 65 when the specific sheet SH10 is inclined with respect to the width direction D12 and the line sensor 51 is not inclined with respect to the width direction D12.

[0060] 10 shows another example of the non-mask area Y13 formed on the specified sheet SH10 by the forming processing unit 65. Specifically, Fig. 10 shows the non-mask area Y13 formed on the specified sheet SH10 by the forming processing unit 65 when the specified sheet SH10 is not tilted with respect to the width direction D12 and the line sensor 51 is tilted with respect to the width direction D12.

[0061] As described above, the amount of inclination of the end Y14 in the non-mask region Y13 with respect to the second direction D14 reflects both the amount of inclination of the specified sheet SH10 with respect to the width direction D12 and the amount of inclination of the line sensor 51 with respect to the width direction D12. Meanwhile, the amount of inclination of the end SH11 (see FIGS. 9 and 10) upstream in the conveyance direction D11 of the specified sheet SH10 on which the non-mask region Y13 is formed with respect to the width direction D12 is the same as the amount of inclination of the specified sheet SH10 with respect to the width direction D12. In other words, the amount of inclination of the end Y14 with respect to the end SH11 reflects only the amount of inclination of the line sensor 51 with respect to the width direction D12. Therefore, a worker adjusting the posture of the line sensor 51 can recognize the amount of inclination of the line sensor 51 with respect to the width direction D12 by measuring the amount of inclination of the end Y14 with respect to the end SH11 of the specified sheet SH10 on which the non-mask region Y13 is formed.

[0062] [Tilt Reflection Image Formation Processing] 4, the image forming method of the present invention will be described below along with an example of the procedure of the tilt-reflecting image forming process executed by the control unit 7 and image processing unit 8 in the image forming apparatus 100. Here, steps S11, S12, etc. represent the numbers of the processing procedures (steps) executed by the control unit 7 or the image processing unit 8. The tilt-reflecting image forming process is executed when the user's operation on the execution key on the guidance screen is accepted.

[0063] <Step S11> First, in step S11, the control unit 7 executes the conveying process for conveying the specific sheet SH10 along the sheet conveying path R11. The process of step S11 is an example of a conveying step of the present invention, and is executed by the conveying process unit 64 of the control unit 7.

[0064] <Step S12> In step S12, the image processing unit 8 acquires shape data X10 (see FIG. 5) indicating the shape of the specific sheet SH10 to be conveyed in the conveying process, using the line sensor 51. The process of step S12 is an example of an acquisition step of the present invention, and is executed by the acquisition processing unit 71 of the image processing unit 8.

[0065] Specifically, when the leading edge of the specific sheet SH10 is detected by the sheet sensor, the image processing unit 8 causes the shape reading unit 5 to start reading the shape of the specific sheet SH10. Furthermore, when the specific time has elapsed since the rear edge of the specific sheet SH10 was detected by the sheet sensor, the image processing unit 8 causes the shape reading unit 5 to end reading the shape of the specific sheet SH10. Then, the image processing unit 8 acquires each of the line data output from the shape reading unit 5 while the shape reading unit 5 is reading the shape of the specific sheet SH10.

[0066] <Step S13> In step S13, the image processing unit 8 performs the masking process to mask the protruding area of the specific image data Y10 (see FIG. 7) that protrudes from the sheet area X11, using the shape data X10 acquired in the process of step S12. The process of step S13 is an example of a masking step of the present invention, and is performed by the mask processing unit 72 of the image processing unit 8.

[0067] Specifically, the image processing unit 8 performs the masking process on the plurality of pixel rows along the second direction D14 included in the specified image data Y10, in order along the first direction D13, starting from the pixel row that is furthest downstream in the first direction D13. More specifically, each time the line data is acquired in the process of step S12, the image processing unit 8 determines the protruding area included in the pixel row based on the acquired line data, and masks the determined protruding area.

[0068] <Step S14> In step S14, the control unit 7 forms, on the specified sheet SH10, an unmasked area Y13 (see FIG. 8) included in the specified image data Y10 in which the protruding area has been masked in the process of step S13. The process of step S14 is an example of a forming step of the present invention, and is executed by the forming processing unit 65 of the control unit 7.

[0069] Specifically, the control unit 7 inputs the plurality of pixel rows along the second direction D14 included in the specific image data Y10 in which the protruding area has been masked, to the image forming unit 3 in order along the first direction D13, starting from the pixel row furthest downstream in the first direction D13. The control unit 7 also starts inputting each of the pixel rows to the image forming unit 3 at the input timing. As a result, in the image forming unit 3, each time the pixel row is input, the ink ejection by the line head 31 is controlled based on the input pixel row, and an unmasked area Y13 is formed on the specific sheet SH10.

[0070] In this way, the image forming apparatus 100 acquires shape data X10 that indicates the shape of the specified sheet SH10 being transported along the sheet transport path R11. The acquired shape data X10 is then used to mask the protruding area of the specified image data Y10 that protrudes from the sheet area X11. An unmasked area Y13 included in the specified image data Y10 with the protruding area masked is then formed on the specified sheet SH10. This allows the formation of an image that reflects the tilt of the line sensor 51.

[0071] Furthermore, in the image forming apparatus 100, the colored region Y11 (see FIG. 7) is positioned so as to overlap the end (trailing end) of the sheet region X11 in the fourth direction D22 in the specific image data Y10. As a result, compared to a configuration in which the colored region Y11 is positioned so as to overlap the end (leading end) of the sheet region X11 in the third direction D21 in the specific image data Y10, the non-masked region Y13 (see FIG. 8) is formed based on the imaging results of the specific sheet SH10 that is not clamped by the transport rollers 22A (see FIG. 1), making it possible to form an image that reflects the inclination of the line sensor 51 with higher accuracy. Note that the transport roller 22A is the transport roller 22 that is closest to the line sensor 51 among the transport rollers 22 located upstream of the line sensor 51 in the sheet transport path R11 in the transport direction D11.

[0072] The control unit 7 may include a reading processing unit 66, a detection processing unit 67, and an adjustment processing unit 68 shown in FIG.

[0073] The reading processing unit 66 reads the image formed on the specified sheet SH10 by the forming processing unit 65. For example, the reading processing unit 66 uses a scanner connected to the image forming apparatus 100 to read the non-mask area Y13 formed on the specified sheet SH10.

[0074] The detection processing unit 67 detects the amount of tilt of the line sensor 51 with respect to the width direction D12 based on the image read by the reading processing unit 66. For example, the detection processing unit 67 calculates the tilt angle of the end Y14 (see FIG. 10) of the non-mask area Y13 with respect to the end SH11 (see FIG. 10) of the specific sheet SH10, and obtains the calculated tilt angle as the amount of tilt of the line sensor 51 with respect to the width direction D12.

[0075] The adjustment processing unit 68 adjusts the attitude of the line sensor 51 based on the amount of tilt detected by the detection processing unit 67. Specifically, the adjustment processing unit 68 adjusts the attitude of the line sensor 51 using an adjustment mechanism (not shown) that can adjust the attitude of the line sensor 51.

[0076] This allows the attitude of the line sensor 51 to be adjusted automatically.

[0077] [Notes on the Invention] The following is a summary of the invention extracted from the above-described embodiment. Note that the configurations and processing functions described in the following supplementary notes can be selected and combined as desired.

[0078] <Appendix 1> an imaging unit that is disposed upstream of the image forming unit in the sheet conveying direction on the conveying path and extends longitudinally along a width direction perpendicular to the conveying direction, and that images the sheet; a conveying processing unit that conveys a predetermined specific sheet along the conveying path; an acquisition processing unit that uses the imaging unit to acquire shape data indicating the shape of the specific sheet conveyed by the conveying processing unit; a masking processing unit that uses the shape data acquired by the acquisition processing unit to mask an overflow area that extends beyond the sheet area in specific image data that is larger in size in a first direction corresponding to the conveying direction than the sheet area included in the shape data; and a forming processing unit that forms an image on the specific sheet that indicates the boundary between a masked area and a non-masked area that face each other along the first direction in the specific image data in which the overflow area has been masked by the masking processing unit.

[0079] <Appendix 2> The image forming apparatus described in Appendix 1, wherein the mask processing unit determines the area outside the area in the specific image data that overlaps with the sheet area when the shape data is overlaid on the specific image data so that a first reference position in the specific image data and a second reference position in the shape data coincide as the protruding area, and the specific image data has a colored area positioned at a position that overlaps with the end of the sheet area on the second direction side along the first direction.

[0080] <Appendix 3> 3. The image forming apparatus according to claim 2, wherein the second direction is opposite to the first direction.

[0081] <Appendix 4> An image forming apparatus as described in any one of Appendices 1 to 3, comprising a reading processing unit that reads the image formed on the specific sheet by the forming processing unit, and a detection processing unit that detects the amount of inclination of the imaging unit with respect to the width direction based on the image read by the reading processing unit.

[0082] <Appendix 5> 5. The image forming apparatus according to claim 4, further comprising an adjustment processing unit that adjusts the attitude of the imaging unit based on the amount of tilt detected by the detection processing unit.

[0083] <Appendix 6> An image forming method performed by an image forming device having an image forming unit that forms an image on a sheet transported along a predetermined transport path, and an imaging unit that is arranged upstream of the image forming unit in the transport path in the transport direction of the sheet and extends longitudinally along a width direction perpendicular to the transport direction, and that images the sheet, the image forming method including: a transporting step of transporting a predetermined specific sheet along the transport path; an acquisition step of using the imaging unit to acquire shape data indicating the shape of the specific sheet transported by the transporting step; a masking step of using the shape data acquired by the acquisition step to mask an overflow area that extends beyond the sheet area in specific image data that is larger in size in a first direction corresponding to the transport direction than the sheet area included in the shape data; and a forming step of forming on the specific sheet an image that indicates the boundary between a masked area and a non-masked area that face each other along the first direction in the specific image data in which the overflow area has been masked by the masking step. [Explanation of symbols]

[0084] 1 chassis 2 Sheet transport section 3 Image forming unit 4 Transport unit 5 Shape reading unit 6 Operation display section 7 Control Unit 8 Image processing section 11 Paper cassette 12 Paper output tray 21 Pickup roller 22 Transport roller 30 Recording head 30A nozzle 31 Line Head 32 Line Head 33 Line Head 34 Line Head 35 Head Frame 41 Conveyor belt 42 First tension roller 43 Second tension roller 44 Third tension roller 45 Transport frame 51 Line Sensor 52 AFE circuit 61 CPU 62 ROM 63 RAM 64 Transport processing section 65 Formation Processing Section 66 Reading processing section 67 Detection processing section 68 Adjustment processing section 71 Acquisition processing unit 72 Mask processing section 100 Image forming device

Claims

1. an image forming unit that forms an image on a sheet that is conveyed along a predetermined conveying path; an imaging unit that is provided on the conveying path upstream of the image forming unit in the sheet conveying direction and elongated along a width direction perpendicular to the conveying direction, and that images the sheet; a conveyance processing unit that conveys a predetermined specific sheet along the conveyance path; an acquisition processing unit that acquires shape data indicating a shape of the specific sheet conveyed by the conveyance processing unit using the imaging unit; a mask processing unit that uses the shape data acquired by the acquisition processing unit to mask a protruding area of specific image data that is larger in size in a first direction corresponding to the conveying direction than a sheet area included in the shape data, the protruding area being outside the sheet area; a forming processing unit that forms, on the specific sheet, an image that indicates a boundary between a masked area and a non-masked area that face each other along the first direction, of the specific image data in which the protruding area has been masked by the mask processing unit; An image forming apparatus comprising:

2. the mask processing unit determines, as the protruding area, an area outside an area in the specific image data that overlaps with the sheet area when the shape data is superimposed on the specific image data so that a first reference position in the specific image data and a second reference position in the shape data coincide with each other; the specific image data has a colored area arranged at a position overlapping an end of the sheet area on a second direction side along the first direction, The image forming apparatus according to claim 1 .

3. The second direction is opposite to the first direction. The image forming apparatus according to claim 2 .

4. a reading processing unit that reads the image formed on the specific sheet by the forming processing unit; a detection processing unit that detects an amount of tilt of the imaging unit with respect to the width direction based on the image read by the reading processing unit; 4. The image forming apparatus according to claim 1, further comprising:

5. an adjustment processing unit that adjusts the attitude of the imaging unit based on the tilt amount detected by the detection processing unit; The image forming apparatus according to claim 4 .

6. An image forming method executed by an image forming apparatus including: an image forming unit that forms an image on a sheet conveyed along a predetermined conveying path; and an imaging unit that is provided on the conveying path upstream of the image forming unit in a conveying direction of the sheet and elongated along a width direction perpendicular to the conveying direction, and that images the sheet, a conveying step of conveying a predetermined specific sheet along the conveying path; an acquiring step of acquiring shape data indicating a shape of the specific sheet conveyed by the conveying step using the imaging unit; a masking step of masking, using the shape data acquired by the acquiring step, a protruding area of specific image data that is larger in size in a first direction corresponding to the conveying direction than a sheet area included in the shape data, the protruding area being protruding from the sheet area; a forming step of forming, on the specific sheet, an image showing a boundary between a masked area and a non-masked area that face each other along the first direction, of the specific image data in which the protruding area has been masked by the masking step; An image forming method comprising:

Images