Image forming device and detecting method

Abstract

To provide an image forming device and a detecting method which can detect an amount of deviation between a position of an image forming part and a position of an imaging part.SOLUTION: An image forming device forms, on a sheet, an image on which an amount of deviation of a position P2 of a line sensor 51 in a width direction D12 from a position P1 of an image forming part 3 in the width direction D12 is reflected; conveys the sheet having the image formed thereon along a sheet conveyance path again; and detects the amount of deviation of the position P2 of the line sensor 51 from the position P1 of the image forming part 3, using an imaged result of the sheet having the image formed thereon by the line sensor 51.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus and a detection 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 formation position by an image forming unit (see, for example, Patent Document 1). There is also known an image forming apparatus that adjusts the position of an image formed on the sheet in a width direction perpendicular to the conveyance direction of the sheet based on the imaging result of the imaging unit. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-148849 Summary of the Invention [Problem to be solved by the invention]

[0004] In the image forming apparatus, the center position of the image forming unit in the width direction may not coincide with the center position of the image capturing unit in the width direction, and in this case, even if the position of the image to be formed on the sheet is adjusted based on the image capturing result by the capturing unit, the image cannot be formed at the center of the sheet in the width direction.

[0005] SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus and a detection method that can detect the amount of misalignment between the position of an image forming unit and the position 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 output unit, a first conveying processing unit, a first acquisition processing unit, a first adjustment processing unit, a formation processing unit, a second conveying processing unit, a second acquisition processing unit, a second adjustment processing unit, a mask processing unit, and a detection processing unit. The image forming unit forms an image on a sheet conveyed along a predetermined conveying path. The output unit includes an imaging unit provided on the conveying path upstream of the image forming unit in a sheet conveying direction and elongated along a width direction perpendicular to the conveying direction, and outputs shape data indicating a shape of the sheet imaged by the imaging unit. The first conveying processing unit conveys a detection sheet along the conveying path. The first acquisition processing unit uses the output unit to acquire the shape data indicating the shape of the detection sheet conveyed by the first conveying processing unit. The first adjustment processing unit adjusts the position of a first image in first image data including a predetermined first image in the specific direction based on the positional relationship in the specific direction corresponding to the width direction between a sheet area in the shape data acquired by the first acquisition processing unit and a predetermined first reference position in the shape data. The formation processing unit forms an image on the detection sheet based on the first image data adjusted by the first adjustment processing unit using the image forming unit. The second conveying processing unit conveys the detection sheet along the conveying path after image formation by the formation processing unit. The second acquisition processing unit acquires the shape data indicating the shape of the detection sheet conveyed by the second conveying processing unit using the output unit. The second adjustment processing unit adjusts the position of a second image in second image data including a second image larger in size in the specific direction than the first image, based on the positional relationship in the specific direction between a sheet area in the shape data acquired by the second acquisition processing unit and the first reference position.The mask processing unit masks an area outside a region that overlaps with a sheet area of the shape data in the second image data when the shape data is overlaid on the second image data so that a predetermined second reference position in the second image data adjusted by the second adjustment processing unit and the first reference position in the shape data acquired by the second acquisition processing unit coincide with each other. The detection processing unit detects a deviation amount of the imaging unit with respect to the image forming unit in the width direction based on a positional relationship in the specific direction between the second image in the second image data and a mask region masked by the mask processing unit included in the second image.

[0007] A detection 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 output unit that includes an imaging unit that is elongated along a width direction perpendicular to the transport direction and upstream of the image forming unit in the transport path in the sheet transport direction, and outputs shape data indicating the shape of the sheet imaged by the imaging unit. The detection method includes a first transport step, a first acquisition step, a first adjustment step, a formation step, a second transport step, a second acquisition step, a second adjustment step, a mask step, and a detection step. In the first transport step, a detection sheet is transported along the transport path. In the first acquisition step, the output unit is used to acquire the shape data indicating the shape of the detection sheet transported in the first transport step. In the first adjusting step, a position of a first image in first image data including a predetermined first image in the specific direction is adjusted based on a positional relationship in the specific direction corresponding to the width direction between a sheet area in the shape data acquired in the first acquiring step and a predetermined first reference position in the shape data. In the forming step, the image forming unit is used to form an image on the detection sheet based on the first image data adjusted in the first adjusting step. In the second conveying step, the detection sheet after image formation in the forming step is conveyed along the conveying path. In the second acquiring step, the output unit is used to acquire the shape data indicating the shape of the detection sheet conveyed in the second conveying step. In the second adjusting step, a position of a second image in second image data including a second image larger in size in the specific direction than the first image is adjusted based on a positional relationship in the specific direction between a sheet area in the shape data acquired in the second acquiring step and the first reference position.In the masking step, an area outside an area that overlaps with a sheet area of the shape data in the second image data when the shape data is superimposed on the second image data so that a predetermined second reference position in the second image data adjusted in the second adjusting step and the first reference position in the shape data acquired in the second acquiring step coincide is masked. In the detecting step, an amount of deviation of the imaging unit with respect to the image forming unit in the width direction is detected based on a positional relationship in the specific direction between the second image in the second image data and a mask area masked in the masking step that is included in the second image. [Effects of the Invention]

[0008] According to the present invention, it is possible to detect the amount of deviation between the position of the image forming unit and the position 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 a reference position setting process executed in 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 first acquisition processing unit of the image forming apparatus according to the embodiment of the present invention. [Figure 6] FIG. 6 is a diagram showing an example of first image data before adjustment by the first adjustment processing unit of the image forming apparatus according to the embodiment of the present invention. [Figure 7]FIG. 7 is a diagram showing an example of the first image data after adjustment by the first adjustment processing unit of the image forming apparatus according to the embodiment of the present invention. [Figure 8] FIG. 8 is a diagram showing an example of an image formed on a detection sheet by a formation processing unit of an image forming apparatus according to an embodiment of the present invention. [Figure 9] FIG. 9 is a diagram showing an example of shape data acquired by the second acquisition processing unit of the image forming apparatus according to the embodiment of the present invention. [Figure 10] FIG. 10 is a diagram showing an example of second image data before adjustment by the second adjustment processing unit of the image forming apparatus according to the embodiment of the present invention. [Figure 11] FIG. 11 is a diagram showing an example of second image data after adjustment by the second adjustment processing unit of the image forming apparatus according to the embodiment of the present invention. [Figure 12] FIG. 12 is a diagram showing an example of second image data after adjustment by the second adjustment processing unit of the image forming apparatus according to the embodiment of the present invention. [Figure 13] FIG. 13 is a diagram showing an example of the second image data after masking by the mask processing unit of the image forming apparatus according to the 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 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 shape reading unit 5 outputs shape data X10 (see FIG. 5) that indicates the shape of the sheet imaged by the line sensor 51. The shape data X10 is data that is composed of a plurality of line data output from the AFE circuit 52 while the shape reading unit 5 is reading the shape of the sheet. The shape reading unit 5 is an example of an output unit of the present invention.

[0032] 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.

[0033] 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.

[0034] 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 adjusts the position of the image to be printed in the second direction D22 in the image data input to the image forming unit 3 based on the image data input from the shape reading unit 5. The second direction D22 corresponds to the width direction D12. This makes it possible to form the image to be printed at the center of the sheet in the width direction D12, even if the sheet transported along the sheet transport path R11 is misaligned in the width direction D12. Furthermore, the image processing unit 8 masks, based on the image data input from the shape reading unit 5, the 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 suppresses ink ejection on the outside of the sheet. The image processing unit 8 is configured with electronic circuits such as integrated circuits (ASIC, DSP).

[0035] Incidentally, an image forming apparatus is known that adjusts the position of an image formed on a sheet in the width direction D12 based on the imaging result obtained by the line sensor 51.

[0036] In the image forming apparatus described above, the center position P1 (see FIG. 2) of the image forming unit 3 in the width direction D12 may not coincide with the center position P2 (see FIG. 2) of the line sensor 51 in the width direction D12. In other words, the line sensor 51 may be misaligned in the width direction D12 with respect to the image forming unit 3. In this case, even if the position of the image to be formed on the sheet is adjusted based on the imaging result by the line sensor 51, the image cannot be formed at the center of the sheet in the width direction D12.

[0037] In contrast to this, the image forming apparatus 100 according to the embodiment of the present invention is capable of detecting the amount of deviation between the position P1 of the image forming unit 3 and the position P2 of the line sensor 51, as will be described below.

[0038] 3, the control unit 7 includes a first transfer processing unit 64, a forming processing unit 65, and a second transfer processing unit 66. Specifically, the CPU 61 of the control unit 7 executes the control program stored in the ROM 62 to function as the first transfer processing unit 64, the forming processing unit 65, and the second transfer processing unit 66. Note that the first transfer processing unit 64, the forming processing unit 65, and the second transfer processing unit 66 may be realized by electronic circuits.

[0039] 3, the image processing unit 8 includes a first acquisition processing unit 71, a first adjustment processing unit 72, a second acquisition processing unit 73, a second adjustment processing unit 74, a mask processing unit 75, a detection processing unit 76, and a setting processing unit 77. The CPU 61 of the control unit 7 may function as each of the above-mentioned processing units by executing the control program stored in the ROM 62.

[0040] The first conveying processing unit 64 executes a first conveying process to convey the detection sheet SH11 (see FIG. 8) along the sheet conveying path R11. For example, the detection sheet SH11 is a blank sheet of A4 portrait size. Note that the detection sheet SH11 may be a sheet of any size.

[0041] For example, the first conveyance processing unit 64 displays a first guide screen on the operation display unit 6 in response to a predetermined user operation on the operation display unit 6. The first guide screen includes a message urging the user to place the detection sheet SH11 in the paper feed cassette 11. The first guide screen also includes a first execution key used to perform the first conveyance processing.

[0042] The first conveyance processing unit 64 executes the first conveyance process when the user operates the first execution key. In the first conveyance process, the sheet conveyance unit 2 and the conveyance unit 4 are used to convey the detection sheet SH11 placed in the paper feed cassette 11 along the sheet conveyance path R11.

[0043] The first acquisition processing unit 71 executes a first acquisition process to acquire shape data X11 (see FIG. 5) using the shape reading unit 5. The shape data X11 is shape data X10 (see FIG. 5) that indicates the shape of the detection sheet SH11 transported by the first transport processing unit 64.

[0044] For example, when the leading edge of the detection sheet SH11 is detected by a sheet sensor (not shown) located upstream of the line sensor 51 in the sheet conveying path R11 (see FIG. 1) in the conveying direction D11, the first acquisition processing unit 71 starts reading the shape of the detection sheet SH11 using the shape reading unit 5. This causes the AFE circuit 52 to output the line data at the imaging cycle. Furthermore, the first acquisition processing unit 71 ends reading the shape of the detection sheet SH11 using the shape reading unit 5 when a predetermined time has elapsed since the sheet sensor detected the trailing edge of the detection sheet SH11. The predetermined time is set so that reading the shape of the detection sheet SH11 using the shape reading unit 5 ends after the trailing edge of the detection sheet SH11 passes a position facing the line sensor 51. The first acquisition processing unit 71 then acquires each of the line data output from the AFE circuit 52 while the shape reading unit 5 is reading the shape of the detection sheet SH11.

[0045] FIG. 5 shows an example of shape data X11. The shape data X11 shown in FIG. 5 is data acquired by the first acquisition processing unit 71 when the position P1 (see FIG. 2) of the image forming unit 3 and the position P2 (see FIG. 2) of the line sensor 51 do not match and the detection sheet SH11 is not misaligned in the width direction D12. The image forming unit 3 is disposed at the center of the sheet transport path R11 in the width direction D12. The shape data X11 includes a sheet area X21 indicating the detection sheet SH11. The sheet area X21 is an area formed by pixels indicating the presence of a sheet. The outside of the sheet area X21 in the shape data X11 is formed by pixels indicating the absence of a sheet. The first direction D21 shown in FIG. 5 corresponds to the transport direction D11.

[0046] When the position P1 (see FIG. 2) of the image forming unit 3 and the position P2 (see FIG. 2) of the line sensor 51 do not match, the sheet area X21 is disposed at a position shifted in the second direction D22 from a predetermined first reference position P11 (see FIG. 5) in the shape data X10, as shown in FIG. 5. Note that in FIG. 5, the center of the sheet area X21 is indicated by a white circle. The first reference position P11 is a position corresponding to the position P2 of the line sensor 51. Specifically, the first reference position P11 is the center position in the first direction D21 and the center position in the second direction D22 in the shape data X10.

[0047] The first adjustment processing unit 72 performs a first adjustment process to adjust the position of the first image Y21 in the first image data Y11 (see FIG. 6) including a predetermined first image Y21 in the second direction D22 based on the positional relationship in the second direction D22 (an example of a specific direction of the present invention) corresponding to the width direction D12 between the sheet area X21 (see FIG. 5) in the shape data X11 acquired by the first acquisition processing unit 71 and the first reference position P11 (see FIG. 5) in the shape data X10.

[0048] Here, the first image data Y11 is image data in bitmap format, and is image data including a plurality of pixel rows along the second direction D22. The length (number of pixels) of each pixel row corresponds to the image formation range in the width direction D12 of the image forming unit 3. In other words, the center of each pixel row corresponds to the center position P1 (see FIG. 2) of the image forming unit 3 in the width direction D12.

[0049] Specifically, the first adjustment processing unit 72 acquires the amount and direction of displacement of the seat area X21 relative to the first reference position P11 along the second direction D22, based on coordinate information of the center of the seat area X21 and coordinate information of the first reference position P11 in the shape data X11 acquired by the first acquisition processing unit 71. Then, the first adjustment processing unit 72 moves the first image Y21 by the acquired amount of displacement in the acquired direction of displacement.

[0050] FIG. 6 shows an example of the first image data Y11 before adjustment by the first adjustment processing unit 72. For example, as shown in FIG. 6, the first image Y21 is a long linear or strip-shaped image in the first direction D21. For example, the first image Y21 is an image colored black. The first image Y21 is disposed at the center of the first image data Y11 in the second direction D22. The area outside the first image Y21 in the first image data Y11 is a colorless area. In other words, the area outside the first image Y21 in the first image data Y11 is formed by white pixels.

[0051] 7 also shows an example of first image data Y11 after adjustment by the first adjustment processing unit 72. In FIG. 7, the first image Y21 before adjustment (before movement) by the first adjustment processing unit 72 is shown by a dashed line.

[0052] The formation processing unit 65 uses the image forming unit 3 to perform a formation process for forming an image based on the first image data Y11 (see FIG. 7) adjusted by the first adjustment processing unit 72 on the detection sheet SH11.

[0053] For example, the formation processing unit 65 inputs a plurality of pixel rows along the second direction D22 included in the first image data Y11 adjusted by the first adjustment processing unit 72 to the image forming unit 3 in order along the first direction D21, starting with the pixel row furthest downstream in the first direction D21. 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 first image Y21 is formed on the detection sheet SH11. As a result, in the image forming unit 3, each time a pixel row is input, the ink ejection by the line head 31 is controlled based on the input pixel row, and the first image Y21 is formed on the detection sheet SH11.

[0054] FIG. 8 shows an example of a first image Y21 formed on the detection sheet SH11 by the formation processing unit 65. The first image Y21 shown in FIG. 8 is an image formed on the detection sheet SH11 based on the first image data Y11 shown in FIG. 7. If the position P1 (see FIG. 2) of the image forming unit 3 does not match the position P2 (see FIG. 2) of the line sensor 51, as shown in FIG. 8, the first image Y21 is positioned at a position shifted in the width direction D12 from the center of the detection sheet SH11. Note that in FIG. 8, the center of the detection sheet SH11 is indicated by a white circle.

[0055] Here, when the position P1 of the image forming unit 3 and the position P2 of the line sensor 51 are aligned, the first image Y21 is positioned at the center of the detection sheet SH11 regardless of whether the detection sheet SH11 is misaligned in the width direction D12. In other words, the amount and direction of misalignment of the first image Y21 in the width direction D12 relative to the center of the detection sheet SH11 on the detection sheet SH11 output by the formation process reflect the amount and direction of misalignment of the line sensor 51 in the width direction D12 relative to the image forming unit 3.

[0056] The second conveying processing section 66 performs a second conveying process of conveying the detection sheet SH11 (see FIG. 8) after image formation by the formation processing section 65 along the sheet conveying path R11.

[0057] For example, when the formation process is executed, the second conveyance processing unit 66 displays a second guide screen on the operation display unit 6. The second guide screen includes a message urging the user to place the detection sheet SH11 after image formation that has been discharged to the discharge tray 12 in the paper feed cassette 11. The second guide screen also includes a second execution key that is used to execute the second conveyance process.

[0058] Then, when the second execution key is operated by the user, the second conveyance processing unit 66 executes the second conveyance process. In the second conveyance process, the sheet conveyance unit 2 and the conveyance unit 4 are used to convey the detection sheet SH11 after image formation that is placed in the paper feed cassette 11 along the sheet conveyance path R11.

[0059] The second acquisition processing unit 73 executes a second acquisition process to acquire shape data X12 (see FIG. 9) using the shape reading unit 5. The shape data X12 is shape data X10 (see FIG. 9) that indicates the shape of the detection sheet SH11 (see FIG. 8) transported by the second transport processing unit 66.

[0060] For example, when the leading edge of the detection sheet SH11 is detected by the sheet sensor, the second acquisition processing unit 73 starts reading the shape of the detection sheet SH11 by the shape reading unit 5. Furthermore, when the specific time has elapsed since the rear edge of the detection sheet SH11 was detected by the sheet sensor, the second acquisition processing unit 73 ends reading the shape of the detection sheet SH11 by the shape reading unit 5. Then, the second acquisition processing unit 73 acquires each of the line data output from the AFE circuit 52 while the shape reading unit 5 is reading the shape of the detection sheet SH11.

[0061] An example of the shape data X12 is shown in Fig. 9. The shape data X12 shown in Fig. 9 is data acquired by the second acquisition processing unit 73 when the position P1 (see Fig. 2) of the image forming unit 3 does not match the position P2 (see Fig. 2) of the line sensor 51 and the detection sheet SH11 is not misaligned in the width direction D12. The shape data X12 includes a sheet area X22 indicating the detection sheet SH11. The sheet area X22 includes the first image Y21.

[0062] When the position P1 (see FIG. 2) of the image forming unit 3 and the position P2 (see FIG. 2) of the line sensor 51 do not match, the sheet area X22 is disposed at a position shifted in the second direction D22 from the first reference position P11 (see FIG. 9) in the shape data X10, as shown in FIG. 9. In FIG. 9, the center of the sheet area X22 is indicated by a white circle.

[0063] The second adjustment processing unit 74 performs a second adjustment process to adjust the position of the second image Y22 in the second direction D22 in the second image data Y12 (see Figure 10) including the second image Y22 that is larger in size in the second direction D22 than the first image Y21, based on the positional relationship in the second direction D22 between the sheet area X22 (see Figure 9) in the shape data X12 acquired by the second acquisition processing unit 73 and the first reference position P11 (see Figure 9).

[0064] Specifically, the second adjustment processing unit 74 acquires the amount and direction of displacement of the seat area X22 relative to the first reference position P11 along the second direction D22, based on coordinate information of the center of the seat area X22 and coordinate information of the first reference position P11 in the shape data X12 acquired by the second acquisition processing unit 73. Then, the second adjustment processing unit 74 moves the second image Y22 by the acquired amount of displacement in the acquired direction of displacement.

[0065] FIG. 10 shows an example of the second image data Y12 before adjustment by the second adjustment processing unit 74. For example, as shown in FIG. 10, the second image Y22 is a strip-shaped or rectangular image that is long in the first direction D21. For example, the second image Y22 is an image colored black. The second image Y22 is positioned at the center of the second image data Y12 in the second direction D22. The outside of the second image Y22 in the second image data Y12 is a colorless area. In other words, the outside of the second image Y22 in the second image data Y12 is formed by white pixels.

[0066] Fig. 11 shows an example of the second image data Y12 after adjustment by the second adjustment processing unit 74. Note that the second image Y22 is hatched in Fig. 10 and Fig. 11. In Fig. 11, the second image Y22 before adjustment (before movement) by the second adjustment processing unit 74 is shown by a dashed line.

[0067] The mask processing unit 75 performs masking processing to mask the outside of an area in the second image data Y12 that overlaps with the sheet area X22 of the shape data X12 when the shape data X12 is superimposed on the second image data Y12 so that a predetermined second reference position P12 (see FIG. 11) in the second image data Y12 (see FIG. 11) adjusted by the second adjustment processing unit 74 coincides with the first reference position P11 (see FIG. 9) in the shape data X12 acquired by the second acquisition processing unit 73. The second reference position P12 is a position corresponding to the position P1 of the image forming unit 3. Specifically, the second reference position P12 is a center position in the first direction D21 and a center position in the second direction D22 in the second image data Y12.

[0068] For example, the mask processing unit 75 replaces the pixels to be masked in the second image Y22 with white pixels.

[0069] For example, the mask processing unit 75 records the positions (coordinate information) of the masked pixels in the second image Y22.

[0070] Fig. 12 shows an example of the second image data Y12 after adjustment by the second adjustment processing unit 74. In Fig. 12, the sheet area X22 of the shape data X12 and the first image Y21 to be overlaid on the second image data Y12 are shown by two-dot chain lines.

[0071] Fig. 13 also shows an example of second image data Y12 masked by the mask processing unit 75. In Fig. 13, a mask area Y23 of the second image Y22 masked by the mask processing unit 75 is shown by a dashed line.

[0072] By the masking process, the positional relationship (see FIG. 8) between the first image Y21 on the detection sheet SH11 output by the forming process and the center of the detection sheet SH11 is reflected in the second image data Y12 after the masking process.

[0073] The detection processing unit 76 performs a detection process to detect the amount of deviation of the line sensor 51 relative to the image forming unit 3 in the width direction D12 based on the positional relationship in the second direction D22 between the second image Y22 (see Figure 13) in the second image data Y12 after the masking process and the mask area Y23 (see Figure 13) masked by the masking processing unit 75 included in the second image Y22.

[0074] For example, the detection processing unit 76 acquires the central position P13 (see Figure 13) of the second image Y22 in the second image data Y12 after the mask processing based on the coordinate information of the second reference position P12 in the second image data Y12 and the amount and direction of movement of the second image Y22 by the second adjustment processing unit 74.

[0075] The detection processing unit 76 also acquires a central position P14 (see FIG. 13) of the mask area Y23 in the second image data Y12 after the masking process, based on the results of recording the positions of the masked pixels by the masking processing unit 75. For example, the detection processing unit 76 acquires coordinate information of the central position P14 based on coordinate information of each of a pair of corners that sandwich the central position P14 in the rectangular mask area Y23.

[0076] Then, the detection processing unit 76 acquires the amount of deviation of the line sensor 51 relative to the image forming unit 3 in the width direction D12, which is the amount of deviation of the center position P14 of the acquired mask area Y23 relative to the center position P13 of the acquired second image Y22. The detection processing unit 76 also acquires the direction opposite to the direction of deviation of the center position P14 of the acquired mask area Y23 relative to the center position P13 of the acquired second image Y22, as the direction of deviation of the line sensor 51 relative to the image forming unit 3.

[0077] The setting processing unit 77 sets a first reference position P11 (see FIG. 5) based on the detection result by the detection processing unit .

[0078] Specifically, the setting processing unit 77 moves the first reference position P11 in the direction of deviation of the mask area Y23 acquired by the detection processing unit 76 from the second image Y22 by the amount of deviation of the mask area Y23 acquired by the detection processing unit 76 from the second image Y22.

[0079] [Reference position setting process] 4, the detection method of the present invention will be described below along with an example of the procedure of the reference position setting process executed by the control unit 7 and the 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 reference position setting process is executed when a user operation to instruct execution of the reference position setting process is accepted on the operation display unit 6.

[0080] <Step S11> First, in step S11, the control unit 7 causes the first guide screen to be displayed on the operation display unit 6. The process of step S11 is executed by the first transfer processing unit 64 of the control unit 7.

[0081] <Step S12> In step S12, the control unit 7 determines whether or not a user operation on the first execution key included in the first guide screen has been accepted.

[0082] Here, if the control unit 7 determines that the user's operation on the first execution key has been accepted (Yes in S12), it shifts the process to step S13. On the other hand, if the user's operation on the first execution key has not been accepted (No in S12), the control unit 7 waits for the user's operation on the first execution key in step S12.

[0083] <Step S13> In step S13, the control unit 7 executes the first conveying process to convey the detection sheet SH11 (see FIG. 8) along the sheet conveying path R11. The process of step S13 is an example of the first conveying step of the present invention, and is executed by the first conveying process unit 64 of the control unit 7.

[0084] <Step S14> In step S14, the image processing unit 8 executes the first acquisition process to acquire the shape data X11 (see FIG. 5) using the shape reading unit 5. The process of step S14 is an example of the first acquisition step of the present invention, and is executed by the first acquisition processing unit 71 of the image processing unit 8.

[0085] <Step S15> In step S15, the image processing unit 8 executes the first adjustment process to adjust the position of the first image Y21 in the first image data Y11 (see FIG. 6) in the second direction D22 based on the positional relationship in the second direction D22 between the sheet area X21 in the shape data X11 (see FIG. 5) in the shape data X10 acquired in the process of step S14 (see FIG. 5). The process of step S15 is an example of the first adjustment step of the present invention, and is executed by the first adjustment processing unit 72 of the image processing unit 8.

[0086] <Step S16> In step S16, the control unit 7 executes the forming process of forming an image based on the first image data Y11 (see FIG. 7) adjusted in the process of step S15 on the detection sheet SH11 using the image forming unit 3. The process of step S16 is an example of a forming step of the present invention, and is executed by the formation processing unit 65 of the control unit 7.

[0087] <Step S17> In step S17, the control unit 7 causes the second guide screen to be displayed on the operation display unit 6. The process of step S17 is executed by the second transfer processing unit 66 of the control unit 7.

[0088] <Step S18> In step S18, the control unit 7 determines whether or not the user's operation on the second execution key included in the second guide screen has been accepted.

[0089] Here, if the control unit 7 determines that the user's operation on the second execution key has been accepted (Yes in S18), it shifts the process to step S19. On the other hand, if the user's operation on the second execution key has not been accepted (No in S18), the control unit 7 waits for the user's operation on the second execution key in step S18.

[0090] <Step S19> In step S19, the control unit 7 executes the second conveying process of conveying the detection sheet SH11 (see FIG. 8) after image formation in the process of step S16 along the sheet conveying path R11. The process of step S19 is an example of the second conveying step of the present invention, and is executed by the second conveying processing unit 66 of the control unit 7.

[0091] <Step S20> In step S20, the image processing unit 8 executes the second acquisition process to acquire the shape data X12 (see FIG. 9) using the shape reading unit 5. The process of step S20 is an example of the second acquisition step of the present invention, and is executed by the second acquisition processing unit 73 of the image processing unit 8.

[0092] <Step S21> In step S21, the image processing unit 8 executes the second adjustment process to adjust the position of the second image Y22 in the second image data Y12 (see FIG. 10) in the second direction D22, based on the positional relationship in the second direction D22 between the sheet area X22 (see FIG. 9) in the shape data X12 acquired in the process of step S20 and the first reference position P11 (see FIG. 9). The process of step S21 is an example of the second adjustment step of the present invention, and is executed by the second adjustment processing unit 74 of the image processing unit 8.

[0093] <Step S22> In step S22, the image processing unit 8 executes the masking process to mask the outside of the area in the second image data Y12 that overlaps with the sheet area X22 of the shape data X12 when the shape data X12 is superimposed on the second image data Y12 so that the second reference position P12 (see FIG. 11) in the second image data Y12 (see FIG. 11) adjusted in the process of step S21 coincides with the first reference position P11 (see FIG. 9) in the shape data X12 (see FIG. 9) acquired in the process of step S20. The process of step S22 is an example of a masking step of the present invention and is executed by the mask processing unit 75 of the image processing unit 8.

[0094] <Step S23> In step S23, the image processing unit 8 executes the detection process to detect the amount of deviation of the line sensor 51 in the width direction D12 relative to the image forming unit 3, based on the positional relationship in the second direction D22 between a second image Y22 (see FIG. 13) in the second image data Y12 after the mask process and a mask area Y23 (see FIG. 13) included in the second image Y22. The process of step S23 is an example of a detection step of the present invention, and is executed by the detection processing unit 76 of the image processing unit 8.

[0095] <Step S24> In step S24, the image processing unit 8 sets a first reference position P11 (see FIG. 5) based on the detection result of the process in step S23. The process in step S24 is executed by the setting processing unit 77 of the image processing unit 8.

[0096] In this way, the image forming apparatus 100 can detect the amount of deviation between the position P1 of the image forming unit 3 and the position P2 of the line sensor 51.

[0097] The first reference position P11 does not have to be the center position in the first direction D21 in the shape data X10. In this case, the second reference position P12 does not have to be the center position in the first direction D21 in the second image data Y12.

[0098] [Notes on the Invention] The following will provide an outline 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.

[0099] <Appendix 1> an output unit that outputs shape data representing the shape of the sheet imaged by the image capturing unit, a first conveyance processing unit that conveys the detection sheet along the conveyance path; a first acquisition processing unit that acquires the shape data representing the shape of the detection sheet conveyed by the first conveyance processing unit using the output unit; a first adjustment processing unit that adjusts the position of the first image in first image data including a predetermined first image in the specific direction based on a positional relationship in the specific direction corresponding to the width direction between a sheet area in the shape data acquired by the first acquisition processing unit and a predetermined first reference position in the shape data; a formation processing unit that forms an image on the detection sheet based on the first image data adjusted by the first adjustment processing unit using the image forming unit; and a second conveyance processing unit that conveys the detection sheet along the conveyance path after image formation by the formation processing unit. a second adjustment processing unit that adjusts the position of the second image in the specific direction based on the positional relationship in the specific direction between the sheet area in the shape data acquired by the second acquisition processing unit and the first reference position; a mask processing unit that masks the outside of an area that overlaps with the sheet area of the shape data in the second image data when the shape data is overlaid on the second image data so that a predetermined second reference position in the second image data adjusted by the second adjustment processing unit coincides with the first reference position in the shape data acquired by the second acquisition processing unit; and a detection processing unit that detects the amount of deviation of the imaging unit relative to the image forming unit in the width direction based on the positional relationship in the specific direction between the second image in the second image data and a mask area masked by the mask processing unit included in the second image.

[0100] <Appendix 2> 2. The image forming apparatus according to claim 1, further comprising: a setting processing unit that sets the first reference position based on a detection result by the detection processing unit.

[0101] <Appendix 3> The image forming apparatus according to claim 1 or 2, wherein the mask processing unit records the positions of the masked pixels in the second image, and the detection processing unit acquires the position of the mask area in the second image data based on the recording result of the positions of the masked pixels.

[0102] <Appendix 4> a first adjusting step of adjusting a position of a first image in first image data including a predetermined first image in a specific direction corresponding to the width direction, based on a positional relationship in the specific direction corresponding to the width direction between a sheet area in the shape data acquired in the first acquiring step and a predetermined first reference position in the shape data; a forming step of forming an image on the detection sheet based on the first image data adjusted in the first adjusting step, using the image forming unit; and a second conveying step of conveying the detection sheet after image formation along the conveying path; a second acquiring step of acquiring, using the output unit, the shape data indicating the shape of the detection sheet conveyed by the second conveying step; a second adjusting step of adjusting, in the specific direction, a position of the second image in second image data including a second image having a size larger than the first image in the specific direction, based on a positional relationship in the specific direction between a sheet area in the shape data acquired by the second acquiring step and the first reference position; a masking step of masking an area outside of a region overlapping with the sheet area of the shape data in the second image data when the shape data is superimposed on the second image data so that a predetermined second reference position in the second image data adjusted by the second adjusting step coincides with the first reference position in the shape data acquired by the second acquiring step; andand a detection step of detecting a deviation amount of the imaging unit relative to the image forming unit in the width direction. [Explanation of symbols]

[0103] 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 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 First transport processing section 65 Formation Processing Section 66 Second transport processing section 71 First acquisition processing unit 72 First adjustment processing section 73 Second acquisition processing unit 74 Second adjustment processing section 75 Mask processing section 76 Detection processing section 77 Setting 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 output unit that includes an imaging unit that is provided elongated along a width direction perpendicular to the conveyance direction on the upstream side of the image forming unit in the conveyance path in the conveyance direction of the sheet, and that outputs shape data that indicates the shape of the sheet imaged by the imaging unit; a first conveying processing unit that conveys the detection sheet along the conveying path; a first acquisition processing unit that acquires the shape data indicating the shape of the detection sheet conveyed by the first conveying processing unit using the output unit; a first adjustment processing unit that adjusts a position of a first image in first image data including a predetermined first image, based on a positional relationship in the specific direction corresponding to the width direction between a sheet area in the shape data acquired by the first acquisition processing unit and a predetermined first reference position in the shape data; a forming processing unit that uses the image forming unit to form, on the detection sheet, an image based on the first image data adjusted by the first adjustment processing unit; a second conveying processing unit that conveys the detection sheet along the conveying path after the image formation by the formation processing unit; a second acquisition processing unit that acquires the shape data indicating the shape of the detection sheet conveyed by the second conveying processing unit using the output unit; a second adjustment processing unit that adjusts a position of the second image in the specific direction in second image data including a second image having a size larger in the specific direction than the first image, based on a positional relationship in the specific direction between a sheet area in the shape data acquired by the second acquisition processing unit and the first reference position; a masking processing unit that masks an area outside a region that overlaps with a sheet area of the shape data in the second image data when the shape data is superimposed on the second image data so that a predetermined second reference position in the second image data adjusted by the second adjustment processing unit and the first reference position in the shape data acquired by the second acquisition processing unit coincide; a detection processing unit that detects a deviation amount of the imaging unit with respect to the image forming unit in the width direction based on a positional relationship in the specific direction between the second image in the second image data and a mask area masked by the mask processing unit included in the second image; An image forming apparatus comprising:

2. a setting processing unit that sets the first reference position based on a detection result by the detection processing unit, The image forming apparatus according to claim 1 .

3. the mask processing unit records the positions of the masked pixels in the second image; the detection processing unit acquires the position of the mask region in the second image data based on the recording result of the positions of the masked pixels.

3. The image forming apparatus according to claim 1.

4. A detection method executed in an image forming apparatus including: an image forming unit that forms an image on a sheet transported along a predetermined transport path; and an image capturing unit that is provided elongated along a width direction perpendicular to the transport direction on an upstream side of the image forming unit in the transport path in the transport direction of the sheet, and an output unit that outputs shape data that indicates the shape of the sheet captured by the image capturing unit, a first conveying step of conveying the detection sheet along the conveying path; a first obtaining step of obtaining the shape data indicating the shape of the detection sheet conveyed in the first conveying step using the output unit; a first adjustment step of adjusting a position of the first image in first image data including a predetermined first image in the specific direction based on a positional relationship in the specific direction corresponding to the width direction between a sheet area in the shape data acquired in the first acquisition step and a predetermined first reference position in the shape data; a forming step of forming, on the detection sheet, an image based on the first image data adjusted in the first adjusting step, using the image forming unit; a second conveying step of conveying the detection sheet after image formation in the forming step along the conveying path; a second obtaining step of obtaining the shape data indicating the shape of the detection sheet conveyed by the second conveying step using the output unit; a second adjustment step of adjusting a position of the second image in the specific direction in second image data including a second image having a size larger in the specific direction than the first image, based on a positional relationship in the specific direction between a sheet area in the shape data acquired by the second acquisition step and the first reference position; a masking step of masking an area outside an area of the shape data in the second image data that overlaps with a sheet area when the shape data is superimposed on the second image data so that a predetermined second reference position in the second image data adjusted in the second adjusting step and the first reference position in the shape data acquired in the second acquiring step coincide; a detection step of detecting a deviation amount of the imaging unit with respect to the image forming unit in the width direction based on a positional relationship in the specific direction between the second image in the second image data and a mask area masked by the masking step included in the second image; A detection method comprising:

Images