JP6492787B2 - Image forming apparatus and program - Google Patents

Description

  The present invention relates to an image forming apparatus and a program.

  Patent Document 1 includes a plurality of recording elements arranged along a predetermined first direction, and drives the recording elements in accordance with input image information so as to be orthogonal to the first direction. An image forming apparatus including an image forming unit that forms an image on a recording medium that moves relative to the recording element in a second direction is disclosed. This technology includes a reading unit that reads an image formed by the image forming unit via an optical system and outputs read data. Further, in this technique, the position of the recording element corresponding to each of the recording elements in each group when the plurality of recording elements are divided into a plurality of groups so that the same number of recording elements arranged in succession are included. And a pattern having the same length extending in the second direction for specifying the formation state of the plurality of groups arranged such that the front end and the rear end of the pattern corresponding to the adjacent recording elements are connected. A detection pattern in which each stepped pattern is arranged so that ends of the stepped pattern are aligned in the first direction is more than a region where an image corresponding to the image information of the recording medium is formed. Control means for controlling the image forming means is provided in the upstream or downstream area in the second direction so that other images are not continuously formed in the surrounding area. Further, this technique includes a specifying unit that specifies a target recording element based on read data obtained by reading the detection pattern by the reading unit.

  Patent Document 2 discloses an ink jet recording apparatus having one or a plurality of full line type ink jet recording heads having a recording element array corresponding to the width of a recording medium. In this technique, a full-line type ink jet recording head configured by a plurality of recording element groups each having a nozzle row having a length shorter than the recording width, a conveying unit that conveys the recording medium, and the recording medium or conveying Reading means composed of two or more sensors for reading the surface of the means. Further, in this technique, a non-ejection detection pattern for detecting non-ejection of each nozzle is recorded on each recording element group of the recording head so as not to overlap, and the recorded recording element group Each non-ejection detection pattern is read without omission by at least one sensor of two or more sensors.

  Patent Document 3 discloses a recording apparatus that includes a recording head having recording element arrays in which recording elements are arranged in a predetermined direction, and performs recording by relatively moving the recording head and the recording medium. In this technique, a plurality of reading means are provided which are arranged in parallel with the recording element array and divide and read the area recorded by the relative movement. Further, in this technique, a coarse adjustment pattern including a first mark recorded by a plurality of recording elements corresponding to each reading unit, and a fine adjustment including a second mark corresponding to a pitch in the arrangement of the recording element arrays. There is also provided chart recording means for recording, by the recording head, a detection chart including a pattern and an individual pattern corresponding to the individual recording element in order to detect the recording state of each recording element. Further, in this technique, information on the relative positional relationship between the recording head and each reading unit is obtained based on the reading result of the coarse adjustment pattern and the fine adjustment pattern, and the individual pattern and each recording element are obtained. There is also provided an individual pattern correspondence means for determining the correspondence relationship between and. Furthermore, this technique also includes determination means for determining the recording state of each recording element based on the determined correspondence and the reading result of the individual pattern.

JP 2012-139901 A JP 2006-240141 A JP 2006-181842 A

  The present invention provides an abnormal state using a simple test image as compared with the case where a reference image is formed also at a position on a recording medium corresponding to an area outside the overlapping area of adjacent reading areas of a plurality of reading means. An object of the present invention is to provide an image forming apparatus and a program capable of accurately detecting a recording element.

In order to achieve the above object, an image forming apparatus according to claim 1 is provided by driving a plurality of recording elements arranged along a crossing direction intersecting a transporting direction of a recording medium, and driving the recording elements. Each having a reading area extending in the intersecting direction for reading an image formed on the recording medium, and provided along the intersecting direction so that adjacent end portions of the reading area overlap with the transport direction. Forming a reference image at a position on the recording medium corresponding to a predetermined position in an area where the end portions of the reading areas of the reading means and the reading areas of the reading means overlap, and in an abnormal state Forming means for forming a detection image on the recording medium by varying the timing of driving the recording elements arranged continuously in the intersecting direction for the recording elements to be detected. The present invention is applied to detection of an abnormal state with respect to detection image data obtained by reading the detection image by each of the plurality of reading units, with the reading position of each of the plurality of reading units reading the reference image as a boundary. A determining unit that determines an application range; and a detection unit that detects the recording element in an abnormal state using the detection image data in the application range determined by the determination unit, and the forming unit includes: the reference image and the detection image, formed on the recording medium so that the detection image are included the reference image in the region to be formed.

  According to a second aspect of the present invention, in the invention according to the first aspect, the determination unit is configured such that each of the read data read at each of the reading positions is read by the reading unit that has read the read data. The application range is determined so as to be included in the detection image data obtained by reading by either.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the forming means drives the recording elements arranged continuously in the intersecting direction at the same timing. The reference image is formed.

According to a fourth aspect of the present invention, in the first aspect of the invention, the recording element is an element that discharges droplets, and the forming unit forms the detection image. The reference image is placed on the recording medium by driving the recording elements so as to eject droplets of a size and by varying the timing for driving the recording elements arranged continuously in the intersecting direction. To form.

According to a fifth aspect of the present invention, in the first aspect of the present invention, the forming unit varies the timing of driving the recording elements arranged in the intersecting direction with a predetermined interval. Thus, the reference image is formed on the recording medium.

The invention according to claim 6 is the invention according to any one of claims 1 to 5 , wherein the number of the reading means is three or more.

On the other hand, in order to achieve the above object, the program according to claim 7 uses a computer as the forming means, determining means, and detecting means of the image forming apparatus according to any one of claims 1 to 6. It is for functioning.

According to the first, second, and seventh aspects of the present invention, the reference image is also formed at a position on the recording medium corresponding to the outside of the region where the adjacent end portions of the reading regions of the plurality of reading units overlap. Compared to the case, it is possible to accurately detect a recording element in an abnormal state using a simple test image.
Further, the length in the transport direction of the image used for detecting the recording element in an abnormal state can be shortened as compared with the case where the reference image and the detection image are formed at different positions in the transport direction.

According to the third aspect of the present invention, it is possible to accurately detect an abnormal recording element using a simple test image.

According to the fourth and fifth aspects of the present invention, compared with the case where the reference image and the detection image are formed at different positions in the transport direction, the image used for detecting the recording element in an abnormal state is detected. The length in the transport direction can be shortened.

According to the invention described in claim 6 , the application range can be determined with high accuracy using a simple test image.

It is a schematic side view showing the main components of the ink jet recording apparatus according to each embodiment. 2 is a schematic bottom view showing a schematic configuration of a recording head according to each embodiment. FIG. It is a schematic plan view with which it uses for description of schematic structure of the image reading part which concerns on each embodiment. It is a schematic front view with which it uses for description of schematic structure of the image reading part which concerns on each embodiment. FIG. 2 is a block diagram illustrating a main configuration of an electric system of the ink jet recording apparatus according to each embodiment. It is a top view with which it uses for description of an example of the test image which concerns on 1st Embodiment. It is a flowchart which shows the flow of a process of the detection process program which concerns on 1st Embodiment. It is a graph with which it uses for description of the detection process of an edge when the edge which concerns on 1st Embodiment is detected. It is a graph with which it uses for description of the detection process of the edge when the edge which concerns on 1st Embodiment is not detected. It is a schematic diagram with which it uses for description of the position of the detected edge which concerns on 1st Embodiment. It is a schematic diagram with which it uses for description of the position of the detected edge which concerns on 1st Embodiment. It is a schematic diagram with which it uses for description of the position of the detected edge which concerns on 1st Embodiment. It is a flowchart which shows the flow of a process of the abnormal nozzle determination processing routine program which concerns on each embodiment. It is a schematic diagram with which it uses for description of the detection process of the abnormal nozzle which concerns on 1st Embodiment. It is a graph which shows an example of the average value of the light intensity for every pixel position concerning a 1st embodiment. It is a schematic diagram with which it uses for description when the position of the right and left edge which concerns on 1st Embodiment is not corrected. It is a top view with which it uses for description of an example of the test image which concerns on 2nd Embodiment. It is a flowchart which shows the flow of a process of the detection process program which concerns on 2nd Embodiment. It is an enlarged plan view with which it uses for description of an example of the test image which concerns on 2nd Embodiment. It is an enlarged plan view with which it uses for description of an example of the test image which concerns on 2nd Embodiment. It is a top view with which it uses for description of an example of the test image which concerns on 3rd Embodiment. It is a flowchart which shows the flow of a process of the detection process program which concerns on 3rd Embodiment. It is a top view with which it uses for description of an example of the test image which concerns on 4th Embodiment. It is a flowchart which shows the flow of a process of the detection process program which concerns on 4th Embodiment. It is a schematic diagram with which it uses for description of the modification of an edge detection process. It is a schematic diagram with which it uses for description of the modification of an edge detection process. It is a schematic diagram with which it uses for description of the modification of an edge detection process. It is a schematic diagram with which it uses for description of the modification of an edge detection process. It is a top view with which it uses for description of the modification of the image for a detection.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. Here, a case where the present invention is applied to an inkjet recording apparatus that records an image by ejecting ink droplets onto a recording medium will be described.

[First Embodiment]
First, the configuration of the inkjet recording apparatus 10 according to the present embodiment will be described with reference to FIGS.

  As shown in FIG. 1, the ink jet recording apparatus 10 according to the present embodiment includes a transport roller 20, a paper feed roll 30, a rotary encoder 32, a discharge roll 40, recording heads 50C, 50M, 50Y, 50K, a drying unit 60, Image reading units 70A to 70C are provided.

  The conveyance roller 20 according to the present embodiment is rotated by driving a conveyance motor 22 (see also FIG. 5) connected to the conveyance roller 20 through a mechanism such as a gear. In addition, a continuous continuous paper P as a recording medium is wound around the paper supply roll 30 according to the present embodiment, and the continuous paper P is rotated in the direction of arrow A in FIG. It is conveyed to. Further, the conveyed continuous paper P is taken up by the discharge roll 40. In the following, the direction in which the continuous paper P is transported (direction of arrow A in FIG. 1) is simply referred to as “transport direction”.

  The rotary encoder 32 according to the present embodiment is provided on the rotation shaft of the paper feed roll 30 and outputs a clock signal each time the paper feed roll 30 rotates by a predetermined angle.

  The recording heads 50C, 50M, 50Y, and 50K according to the present embodiment are provided in this order from the upstream in the transport direction along the transport direction. Hereinafter, when it is not necessary to distinguish the recording heads 50C, 50M, 50Y, and 50K, the alphabet at the end of the code is omitted.

  As shown in FIG. 2, the recording head 50 includes a plurality of nozzles 52 arranged along a crossing direction (hereinafter simply referred to as “crossing direction”) that crosses the transport direction. The nozzle 52 is an example of the recording element of the present invention. The recording heads 50C, 50M, 50Y, and 50K respectively output ink droplets corresponding to four colors of cyan (C), magenta (M), yellow (Y), and black (K) from the nozzle 52 to the continuous paper P. Dispense up.

  The drying unit 60 according to the present embodiment includes, for example, a plurality of surface emitting laser elements, and dries the ink droplets by irradiating the ink droplets ejected on the continuous paper P with a laser from the surface emitting laser element. Thus, the ink droplets are fixed on the continuous paper P. As the drying unit 60, other devices such as a heater for drying ink droplets ejected onto the continuous paper P by hot air may be applied.

  As shown in FIGS. 1 and 3, among a plurality (three in this embodiment) of image reading units 70A to 70C according to the present embodiment, the image reading units 70A and 70C are provided at the same position in the transport direction. The image reading unit 70B is provided downstream in the transport direction from the image reading units 70A and 70C. Hereinafter, when it is not necessary to distinguish between the image reading units 70A to 70C, the alphabet at the end of the code is omitted. As shown in FIG. 3, the image reading unit 70 according to the present embodiment is provided along the crossing direction so that the end regions of the adjacent reading regions overlap with the transport direction. In the following description, a range in the crossing direction of the end region of the reading region that overlaps in the transport direction is referred to as a “read overlapping range”.

  4, the image reading unit 70 according to the present embodiment is a line sensor including, for example, a CCD (Charge Coupled Device) image sensor 72, a lens 74, and the like, and is formed on the continuous paper P. The read image is read at a predetermined resolution for each line extending in the crossing direction along the transport direction. The image reading unit 70 outputs luminance data indicating the light intensity of each pixel according to the density of the read image. As described above, in this embodiment, a CCD sensor is applied as the image reading unit 70. However, the present invention is not limited to this, and a CIS (Contact Image Sensor) sensor may be applied.

  Next, with reference to FIG. 5, the configuration of the main part of the electrical system of the inkjet recording apparatus 10 according to the present embodiment will be described.

  As shown in FIG. 5, the inkjet recording apparatus 10 according to the present embodiment stores a CPU (Central Processing Unit) 80 that controls the overall operation of the inkjet recording apparatus 10, various programs, various parameters, and the like. A ROM (Read Only Memory) 82 is provided. The inkjet recording apparatus 10 also includes a RAM (Random Access Memory) 84 used as a work area when the CPU 80 executes various programs, and a nonvolatile storage unit 86 such as a flash memory.

  In addition, the inkjet recording apparatus 10 includes a communication line I / F (Interface) unit 88 that transmits and receives communication data to and from an external apparatus. In addition, the inkjet recording apparatus 10 includes an operation display unit 90 that receives an instruction from the user to the inkjet recording apparatus 10 and notifies the user of various types of information regarding the operation status of the inkjet recording apparatus 10. The operation display unit 90 includes, for example, a display button that realizes reception of an operation instruction by executing a program, a touch panel display on which various information is displayed, and hardware keys such as a numeric keypad and a start button.

  The CPU 80, the ROM 82, the RAM 84, the storage unit 86, the conveyance motor 22, the rotary encoder 32, and the recording head 50 are connected to each other via a bus 92 such as an address bus, a data bus, and a control bus. In addition to these units, the drying unit 60, the image reading unit 70, the communication line I / F unit 88, and the operation display unit 90 are also connected to each other via a bus 92. In addition, a conveyance roller 20 is connected to the conveyance motor 22.

  With the above configuration, the inkjet recording apparatus 10 according to the present embodiment performs access to the ROM 82, RAM 84, and storage unit 86 and transmission / reception of communication data via the communication line I / F unit 88 by the CPU 80. In the inkjet recording apparatus 10, the CPU 80 acquires various data via the operation display unit 90 and displays various information on the operation display unit 90. In the inkjet recording apparatus 10, the CPU 80 receives the clock signal output from the rotary encoder 32 and controls the recording head 50, the drying unit 60, and the image reading unit 70 based on the clock signal. In the inkjet recording apparatus 10, the CPU 80 controls the rotation of the conveyance roller 20 via the conveyance motor 22 and acquires the luminance data output from the image reading unit 70.

  Incidentally, the ink jet recording apparatus 10 according to the present embodiment is equipped with an abnormal nozzle detection function for detecting a nozzle 52 (hereinafter simply referred to as “abnormal nozzle”) in an abnormal state. Then, the inkjet recording apparatus 10 forms a test image for detecting an abnormal nozzle on the continuous paper P in order to realize an abnormal nozzle detection function. The abnormal state of the nozzle 52 mentioned here includes, for example, a non-ejection abnormality in which ink droplets are not ejected, a fine line abnormality in which the ejection amount of ink droplets is decreased, and a misregistration abnormality in which the landing positions of ink droplets are shifted. . Hereinafter, in order to avoid complications, only the case of detecting an abnormal nozzle of the recording head 50K will be described, but the same applies to the recording heads 50C, 50M, and 50Y corresponding to other colors. In this embodiment, the CPU 80 assigns nozzle numbers to the nozzles 52 in order from 1, 2,.

  Next, referring to FIG. 6, a test image in the inkjet recording apparatus 10 according to the present embodiment will be described. 6 is an enlarged view of the portion surrounded by the dashed rectangle at the upper part of FIG. 6. In the following, a case will be described in which all the nozzles 52 at positions corresponding to the width in the cross direction of the image forming area determined according to the size of the continuous paper P are set as detection targets for abnormal states. Hereinafter, the nozzle 52 that is the detection target is referred to as a “detection target nozzle”.

  As shown in FIG. 6, the test image T according to the present embodiment includes a reference image K1 and a detection image K2 formed upstream in the transport direction of the reference image K1. The reference image K1 according to the present embodiment has a predetermined number or more (seven in the present embodiment) of continuously arranged nozzles among the nozzles 52 located in the range corresponding to the reading overlap range. It is an image formed by driving 52 at the same timing. As described above, in the present embodiment, the reference image K1 is formed downstream in the conveyance direction of the detection image K2. However, the present invention is not limited to this, and the reference image K1 is formed upstream in the conveyance direction of the detection image K2. May be.

  In the detection image K <b> 2 according to the present embodiment, the detection target nozzles are arranged with a predetermined number (15 in the present embodiment, 15 as an example) of nozzles 52 apart from each other in the intersecting direction. This is an image formed by dividing a plurality of nozzles 52 into a plurality of nozzles 52 group and ejecting ink droplets for each nozzle 52 group. The detection image K2 is shifted by the number of nozzles 52 determined in advance in the intersecting direction (1 in this embodiment as an example) at different timings for each of the nozzle 52 groups. Formed in position. Hereinafter, in order to simplify and clarify the description, as illustrated in FIG. 6, each stepped portion in the detection image K2 formed in a stepped shape is referred to as a “stepped image K3”.

  Therefore, the first stage image of the detection image K2 shown in FIG. 6 is 16n + 1 (n = 0, 1, 2,...) With reference to the nozzle 52 at the position corresponding to the left end of the test image T in FIG. This is an image formed by the nozzle 52 of (.). Similarly, the second-stage image of the detection image K2 shown in FIG. 6 is 16n + 2 (n = 0, 1, 2,...) On the basis of the nozzle 52 at the position corresponding to the left end portion. It is an image formed by the nozzle 52. Further, the length of each straight line L1 formed by each nozzle 52 in the detection image K2 in the transport direction is set to a length that can be read by the image reading unit 70 a plurality of times. In the present embodiment, image information indicating the test image T described above (hereinafter referred to as “test image information”) is stored in the storage unit 86 in advance.

  Next, the operation of the inkjet recording apparatus 10 according to the present embodiment will be described with reference to FIG. FIG. 7 is a flowchart showing the flow of processing of a detection processing program executed by the CPU 80 when an instruction input for instructing execution is input via the operation display unit 90 by the user. The detection processing program is installed in the ROM 82 in advance. In this embodiment, the timing at which the instruction input for instructing the start of execution is input as the timing for executing the detection processing program. However, the present invention is not limited to this. For example, other timings such as a timing when an image having a predetermined number of pages is formed may be applied as the timing for executing the detection processing program.

  In step 200 of FIG. 7, the CPU 80 specifies a range of nozzle numbers for image formation based on the size of the image forming area with respect to the crossing direction of the continuous paper P determined according to the size of the continuous paper P, and also stores the storage unit 86. Read test image information from. In the next step 202, the CPU 80 continuously prints the test image T by driving the recording head 50K, the conveyance motor 22 and other parts related to the conveyance of the continuous paper P based on the test image information read out in the process of the step 200. Form on paper P.

  In the next step 204, the CPU 80 reads the test image T by driving the image reading unit 70 and the parts related to the conveyance of the continuous paper P such as the conveyance motor 22, and obtains the luminance data of the reference image K1 and the detection image K2. Get each. Hereinafter, the luminance data of the reference image K1 is referred to as “reference image data”, and the luminance data of the detection image K2 is referred to as “detection image data”. Further, in the following, for convenience of explanation, the image data of the reference image data and the detection image data is arranged in a two-dimensional matrix shape in which the vertical direction corresponds to the transport direction and the horizontal direction corresponds to the cross direction. A case where the CPU 80 acquires the obtained pixel data will be described. However, the present invention is not limited thereto, and pixel data in which the image data of the reference image data and the detection image data are arranged in a one-dimensional manner may be used.

  In the next step 206, the CPU 80 applies the detection image data acquired by the processing of the above step 204 for each pixel of the image sensor 72 (for each pixel position in the horizontal direction (crossing direction) of the corresponding detection image data). In addition, the sum of the light intensities in a predetermined number of rows in the vertical direction (conveyance direction) with respect to the central pixel of the detection image data is derived. Then, the CPU 80 derives an average value of the light intensity for each pixel position by dividing the derived sum value by the number of rows. Then, the CPU 80 derives a moving average value for each number of pixels corresponding to the interval in the intersecting direction of the adjacent straight lines L1 in the left-right direction in the derived average value of the light intensity for each pixel position. Specifically, as an example, when the resolution of the recording head 50 is 1200 dpi (dots per inch) and the resolution of the image reading unit 70 is 600 dpi, the CPU 80 derives a moving average value of light intensity for every 8 pixels. In the present embodiment, the number of times necessary for reading the straight line L1 by the image reading unit 70 is applied as the predetermined number of rows. However, the present invention is not limited to this. For example, as the predetermined number of lines, all the numbers of lines in the vertical direction of the detection image data may be applied. In this case, the moving average value need not be derived.

  In the next step 208, the CPU 80 detects the left and right edges (ends) of the detection image data based on the moving average value for each pixel position derived by the processing in step 206. Here, the processing of step 208 will be described in detail with reference to FIGS. 8A and 8B. 8A and 8B, the horizontal axis indicates the pixel position, and the vertical axis indicates the moving average value of the light intensity. In the present embodiment, as an example, the light intensity takes a discrete value in increments of 1 from 0 to 255 (8-bit configuration). The larger the value, the closer to white, and the smaller the value, the closer to black. It is supposed to be.

  When detecting the left edge of the detection image data, the CPU 80 is predetermined in advance to the left from the pixel position corresponding to the central pixel position of the detection image data with respect to the moving average value for each pixel position. A portion where pixels having the threshold value Y1 or more continue for a predetermined number of pixels G1 or more is detected, and the pixel position of the pixel having the threshold value Y1 or more first is determined as the left edge. As an example, as shown in FIG. 8A, the detection image data obtained by reading by the image reading unit 70A includes a blank portion at one end portion (the left end portion shown in FIG. 3) in the intersecting direction of the continuous paper P. In addition, there is a portion in which pixels having a threshold value Y1 or more continue for the number of pixels G1 or more. Accordingly, in this case, the pixel position P1 shown in FIG. 8A is determined as the left edge. Note that a threshold set by the user via the operation display unit 90 may be applied as the threshold Y1, and for example, the maximum value of the average value of the light intensity for each pixel position derived by the process of step 206 described above. An average value with the minimum value may be applied. Further, as the pixel number G1, a value set by the user via the operation display unit 90 may be applied. For example, the pixel number corresponding to the interval in the intersecting direction of the straight lines L1 adjacent to the intersecting direction may be applied. Also good.

  On the other hand, when detecting the right edge of the detection image data, the CPU 80 sets a threshold value to the right from the pixel position corresponding to the central pixel position of the detection image data with respect to the moving average value for each pixel position. A portion where pixels that are Y1 or more continue for the number of pixels G1 or more is detected, and the pixel position of the pixel that first becomes the threshold Y1 or more is determined as the right edge. As an example, as shown in FIG. 8B, the detection image data obtained by reading by the image reading units 70A and 70B has a blank portion at the other end (the right end shown in FIG. 3) in the crossing direction of the continuous paper P. Since it is not included, there is no portion in which pixels equal to or greater than the threshold Y1 continue for the number of pixels G1 or more. Therefore, in this case, the right edge is not detected.

  In the next step 210, the CPU 80 performs all the rows in the vertical direction for each pixel of the image sensor 72 (for each pixel position in the horizontal direction of the corresponding reference image data) with respect to the reference image data acquired by the processing in step 204. The sum of the light intensity of the numbers is derived. Further, the CPU 80 derives an average value of the light intensity for each pixel position by dividing the derived sum value by the total number of rows. Then, the CPU 80 identifies the pixel position of the reference image K1 in the reference image data by detecting a portion where pixels less than the threshold Y1 continue in the left-right direction based on the derived average value for each pixel position.

  In the next step 212, the CPU 80 determines whether or not the left edge has been detected by the processing in step 208 described above. When this determination is a negative determination, the CPU 80 proceeds to the process of step 214, and when this determination is a positive determination, the CPU 80 proceeds to the process of step 216.

  In step 214, the CPU 80 determines the left edge of the detection image data based on the pixel position specified by the processing in step 210. Specifically, the CPU 80 does not include the staircase image K3 at the pixel position of the detection image data corresponding to the specified pixel position, and determines the right pixel position of the specified pixel position as the left edge.

  In step 216, the CPU 80 determines whether or not the right edge has been detected by the processing in step 208 described above. When this determination is a negative determination, the CPU 80 proceeds to the process of step 218, whereas when this determination is a positive determination, the CPU 80 proceeds to the process of step 220.

  In step 218, the CPU 80 determines the right edge of the detection image data based on the pixel position specified by the processing in step 210. Specifically, the CPU 80 determines the pixel position including the staircase image K3 of the pixel position of the detection image data corresponding to the specified pixel position as the right edge.

  In step 214, the CPU 80 may determine a pixel position including the staircase image K3 of the pixel position of the detection image data corresponding to the specified pixel position as the left edge. In this case, in step 218, the CPU 80 does not include the staircase image K3 of the pixel position of the detection image data corresponding to the specified pixel position, and uses the pixel position on the left of the specified pixel position as the right edge. decide.

  In step 220, the CPU 80 corrects the positions of the left and right edges of the detection image data determined by the above processing for each stage of the detection image K2 based on the resolution of the recording head 50 and the resolution of the image reading unit 70. . Specifically, as an example, when the resolution of the recording head 50 is 1200 dpi and the resolution of the image reading unit 70 is 600 dpi, the CPU 80 adjusts the left and right edges of the detection image data in accordance with the shape of the detection image K2. The position is corrected by one pixel every two stages.

  In step 222, the CPU 80 calculates the sum of the light intensities of a predetermined number of columns on the right side from the left edge determined by the processing of step 208 or step 214 in the detection image data acquired by the processing of step 204. Derived for each pixel position in the vertical direction. Then, the CPU 80 derives an average value of the light intensity for each pixel position by dividing the derived sum value by the number of columns. In the present embodiment, the number of columns including one staircase image K3 is applied as the predetermined number of columns. Similarly, the CPU 80 derives the average value for the light intensity of a predetermined number of columns on the left side from the right edge determined by the processing in step 208 or step 218.

  In the next step 224, similarly to the processing in step 208, the CPU 80 uses the average value derived by the processing in step 222 and the threshold value Y1, and the upper and lower edges corresponding to the left edge of the detection image data. And the upper and lower edges corresponding to the right edge are determined.

  9A to 9C schematically show the top, bottom, left, and right edges determined by the above processing. 9A shows a test image T read by the image reading unit 70A, FIG. 9B shows a test image T read by the image reading unit 70B, and FIG. 9C shows a test image read by the image reading unit 70C. T is shown. 9A to 9C, the upper, lower, left, and right broken lines constituting the parallelogram indicate the determined upper, lower, left, and right edges, respectively.

  In the next step 226, the CPU 80 determines that the difference between the position of the upper and lower edges corresponding to the left edge detected by the processing in step 224 and the position of the upper and lower edges corresponding to the right edge is a predetermined threshold value. It is judged whether it is less than. That is, the CPU 80 determines whether the image reading unit 70 and the continuous paper P are not inclined relative to the transport direction. When this determination is a negative determination, the CPU 80 proceeds to the process of step 228, while when this determination is a positive determination, the CPU 80 proceeds to the process of step 230.

  In step 228, the above processing is performed so that the difference between the position of the upper and lower edges corresponding to the left edge detected by the processing in step 224 and the position of the upper and lower edges corresponding to the right edge is eliminated or reduced. The image data for detection in the range inside the upper, lower, left, and right edges determined by (hereinafter referred to as “applicable range”) is corrected. As this correction processing, conventionally known image processing such as image rotation processing may be applied, and detailed description thereof is omitted here.

  In step 230, the CPU 80 executes an abnormal nozzle determination processing routine program for the image data for detection in the application range. Then, the CPU 80 ends the detection processing program after the abnormal nozzle determination processing routine program ends.

  Hereinafter, the abnormal nozzle determination processing routine program according to the present embodiment will be described with reference to FIG. FIG. 10 is a flowchart showing the flow of processing of the abnormal nozzle determination processing routine program. This program is also installed in the ROM 82 in advance.

  In step 300 of FIG. 10, based on the nozzle number acquired by the process of step 200, the resolution of the recording head 50, the resolution of the image reading unit 70, and the determined positions of the left and right edges, the detection image K2 for each application range. Each of the minimum nozzle numbers of the nozzles 52 forming the nozzles is specified.

  In the next step 302, the CPU 80 derives an average value of light intensity corresponding to each stage in the conveyance direction of the detection image K2 for each pixel position in the left-right direction. As an example, FIG. 12 shows the average value of the light intensity derived for each pixel position in the left-right direction for the third stage of the detection image K2 shown in FIG. 11 (the stage indicated by the broken line in FIG. 11). The vertical axis in FIG. 12 indicates the average value of the light intensity, the horizontal axis indicates the pixel position in the left-right direction, and the numbers on the horizontal axis indicate the pixel numbers starting from the pixel at the left edge of the application range. .

  In the next step 304, the CPU 80 detects the interval between the downwardly convex peak values (the interval D shown in FIG. 12) in the average value derived by the processing in step 302 based on the resolution of the image reading unit 70. It converts into the space | interval for every adjacent straight line L1 of the image K2. Then, the CPU 80 derives a difference between the converted interval and the actual interval between the corresponding nozzles 52, and when the difference is equal to or greater than a predetermined threshold A, or equal to or less than a predetermined threshold B. In this case, it is determined that the nozzle 52 at the corresponding position is an abnormal nozzle. Further, the CPU 80 identifies the nozzle number corresponding to the abnormal nozzle based on the position of the nozzle 52 determined to be an abnormal nozzle and the nozzle number acquired by the processing in step 300, and stores the nozzle number in the storage unit. 86.

  In step 304, the CPU 80 may perform the abnormal nozzle determination process without regard to the peak value whose light intensity is equal to or greater than a predetermined threshold value among the peak values protruding downward. Good. As a threshold value in this case, a threshold value set by the user via the operation display unit 90 may be applied. For example, an average value between the maximum value and the minimum value of the average value derived by the processing in step 302 is used. You may apply. In step 304, the CPU 80 performs quadratic interpolation on the average value derived for each pixel position by the processing in step 302 to obtain an approximate curve, and then derives a downwardly convex peak value. Also good.

  In step 304, the CPU 80 determines the abnormal nozzle based on the interval between the adjacent straight lines L1 of the detection image K2, but the present invention is not limited to this. For example, the CPU 80 may determine an abnormal nozzle on the basis of the position in the intersecting direction of the downwardly convex peak value based on the position in the intersecting direction of the nozzle number specified by the processing in step 300.

  In step 306, the CPU 80 determines whether an abnormal nozzle is detected by determining whether the nozzle number of the abnormal nozzle is stored in the storage unit 86. If this determination is affirmative, the CPU 80 proceeds to step 308.

  In step 308, the CPU 80 reads out the nozzle number of the abnormal nozzle from the storage unit 86 and displays the nozzle number on the operation display unit 90 for notification. In step 308, the CPU 80 may perform maintenance processing such as cleaning processing on the nozzle number, for example. In step 308, the CPU 80 may set the parameters of the nozzle 52 so that the size of the ink droplets ejected from the nozzle 52 adjacent to the nozzle of the nozzle number becomes larger than usual.

  On the other hand, if the determination in step 306 is negative, the CPU 80 ends the abnormal nozzle determination processing routine program without executing the processing in step 308.

  In the present embodiment, as described above, the positions of the left and right edges are corrected for each stage of the detection image K2 by the processing of step 220 described above. If this correction is not performed, the left and right edges may be determined as positions in the middle of the staircase image K3, as indicated by the broken lines in FIG. FIG. 13 schematically shows a test image T read by the image reading unit 70B as an example. On the other hand, in the present embodiment, as shown in FIGS. 9A to 9C, the application range is determined according to the shape of the detection image K2.

[Second Embodiment]
In the first embodiment, the case where the reference image K1 and the detection image K2 are formed at different positions in the transport direction has been described. On the other hand, in the second embodiment, a case will be described in which the reference image K1 is included in an area where the detection image K2 is formed. The configuration of the ink jet recording apparatus 10 according to the present embodiment is the same as that of the ink jet recording apparatus 10 according to the first embodiment (see FIGS. 1 to 4), and thus the description thereof is omitted here. To do.

  First, a test image in the inkjet recording apparatus 10 according to the present embodiment will be described with reference to FIG. In the present embodiment, a case will be described in which all the nozzles 52 at positions corresponding to the width in the cross direction of the image forming area determined according to the size of the continuous paper P are set as detection target nozzles.

  As shown in FIG. 14, in the test image T according to the present embodiment, the reference image K1 is included in the region where the detection image K2 is formed. Specifically, the reference image K1 according to the present embodiment is formed at a position included in one staircase image K3 within the reading overlap range (the position of the upper end in the example shown in FIG. 14).

  Next, the operation of the inkjet recording apparatus 10 according to the present embodiment will be described with reference to FIG. FIG. 15 is a flowchart showing a processing flow of the detection processing program executed by the CPU 80 when an instruction input for instructing execution is input via the operation display unit 90 by the user. The detection processing program is installed in the ROM 82 in advance. Further, steps in FIG. 15 that execute the same processing as in FIG. 7 are denoted by the same step numbers as in FIG.

  In step 204A of FIG. 15, the CPU 80 reads the detection image K2 (test image T) by driving the image reading unit 70 and the parts related to the conveyance of the continuous paper P such as the conveyance motor 22, and obtained by reading. Image data for detection is acquired.

  In step 210A of FIG. 15, the CPU 80 adds the light intensity of the total number of rows in the vertical direction for each pixel position in the horizontal direction of the detection image data with respect to the detection image data acquired by the processing in step 204A. Is derived. Further, the CPU 80 derives an average value of the light intensity for each pixel position by dividing the derived total value by the total number of rows. Then, the CPU 80 identifies the pixel position of the reference image K1 in the detection image data by detecting a portion where pixels less than the threshold Y1 continue in the left-right direction based on the derived average value for each pixel position.

  In the present embodiment, an abnormal nozzle is not accurately detected for the nozzle 52 used for forming the staircase image K3 including the reference image K1. Therefore, in the present embodiment, the process of forming the test image T and detecting the abnormal nozzle is performed twice. Then, for the test image T formed for the second time, as shown in FIG. 16A, the reference image K1 is formed at a position in the crossing direction different from the reference image K1 formed for the first time shown in FIG. As shown in FIG. 16B, the test image T formed second time is different from the reference image K1 formed first time in that not only the position in the cross direction but also the position in the transport direction is different from the reference image K1. It may be formed. 16A and 16B corresponds to the broken-line rectangle in the lower center portion shown in FIG.

  As described above, in the present embodiment, the length of the test image T in the transport direction is shorter than that in the first embodiment. This is effective when a test image T is formed in the margin between pages of the continuous paper P to detect abnormal nozzles.

[Third Embodiment]
Also in the third embodiment, the case where the reference image K1 is included in the region where the detection image K2 is formed will be described. The configuration of the ink jet recording apparatus 10 according to the present embodiment is the same as that of the ink jet recording apparatus 10 according to the first embodiment (see FIGS. 1 to 4), and thus the description thereof is omitted here. To do.

  First, a test image in the inkjet recording apparatus 10 according to the present embodiment will be described with reference to FIG. In the present embodiment, a case will be described in which all the nozzles 52 at positions corresponding to the width in the cross direction of the image forming area determined according to the size of the continuous paper P are set as detection target nozzles.

  As shown in FIG. 17, in the test image T according to the present embodiment, the reference image K1 is included in the region where the detection image K2 is formed. Specifically, the reference image K1 according to the present embodiment is a staircase image K3 formed by ejecting ink droplets having a size larger than that of other staircase images K3.

  Next, with reference to FIG. 18, the operation of the ink jet recording apparatus 10 according to the present embodiment will be described. FIG. 18 is a flowchart showing a flow of processing of a detection processing program executed by the CPU 80 when an instruction input for instructing execution is input via the operation display unit 90 by the user. The detection processing program is installed in the ROM 82 in advance. In addition, steps in FIG. 18 that execute the same processing as in FIG. 15 are denoted by the same step numbers as in FIG.

  In step 210B of FIG. 18, the CPU 80 adds the light intensity of the total number of rows in the vertical direction for each pixel position in the horizontal direction of the detection image data with respect to the detection image data acquired by the processing in step 204A. Is derived. Further, the CPU 80 derives an average value of the light intensity for each pixel position by dividing the derived total value by the total number of rows. Then, the CPU 80 identifies the pixel position of the reference image K1 in the detection image data by detecting a portion where pixels less than the threshold Y2 continue in the left-right direction based on the derived average value for each pixel position. Note that a threshold set by the user via the operation display unit 90 may be applied as the threshold Y2. For example, the average for each pixel position derived for the staircase image K3 other than the reference image K1 of the detection image K2. A value smaller than the value (that is, a value close to black) may be applied.

  In the present embodiment, an abnormal nozzle is not accurately detected for the nozzle 52 used to form the reference image K1. Therefore, in the present embodiment, the process of forming the test image T and detecting the abnormal nozzle is performed twice. Then, for the test image T to be formed at the second time, the reference image K1 is formed at a position in the cross direction different from the reference image K1 formed at the first time.

[Fourth Embodiment]
Also in the fourth embodiment, the case where the reference image K1 is included in the region where the detection image K2 is formed will be described. The configuration of the ink jet recording apparatus 10 according to the present embodiment is the same as that of the ink jet recording apparatus 10 according to the first embodiment (see FIGS. 1 to 4), and thus the description thereof is omitted here. To do.

  First, a test image in the inkjet recording apparatus 10 according to the present embodiment will be described with reference to FIG. In the present embodiment, a case will be described in which all the nozzles 52 at positions corresponding to the width in the cross direction of the image forming area determined according to the size of the continuous paper P are set as detection target nozzles.

  As shown in FIG. 19, in the test image T according to the present embodiment, the reference image K1 is included in the region where the detection image K2 is formed. Specifically, the reference image K1 according to the present embodiment is a staircase image K3 that is formed by driving the nozzles 52 with a predetermined interval in the intersecting direction. FIG. 19 shows a state in which the reference image K1 is formed by every other nozzle 52.

  Next, with reference to FIG. 20, the operation of the inkjet recording apparatus 10 according to the present embodiment will be described. FIG. 20 is a flowchart showing a flow of processing of a detection processing program executed by the CPU 80 when an instruction input for instructing execution is input via the operation display unit 90 by the user. The detection processing program is installed in the ROM 82 in advance. Further, steps in FIG. 20 that execute the same processing as in FIG. 15 are denoted by the same step numbers as in FIG.

  In step 210C of FIG. 20, the CPU 80 adds the light intensity values of the total number of rows in the vertical direction for each pixel position in the horizontal direction of the detection image data with respect to the detection image data acquired by the processing in step 204A. Is derived. Further, the CPU 80 derives an average value of the light intensity for each pixel position by dividing the derived total value by the total number of rows. Then, the CPU 80 identifies a pixel position of the reference image K1 in the detection image data by detecting a portion where pixels having a threshold value Y3 or more continue in the left-right direction based on the derived average value for each pixel position. Note that a threshold set by the user via the operation display unit 90 may be applied as the threshold Y3. For example, the average for each pixel position derived for the staircase image K3 other than the reference image K1 of the detection image K2. A value larger than the value (that is, a value close to white) may be applied.

  In the present embodiment, an abnormal nozzle is not accurately detected for the nozzle 52 used to form the reference image K1. Therefore, in the present embodiment, the process of forming the test image T and detecting the abnormal nozzle is performed twice. Then, for the test image T to be formed at the second time, the reference image K1 is formed at a position in the cross direction different from the reference image K1 formed at the first time.

  Although each embodiment has been described above, the technical scope of the present invention is not limited to the scope described in each embodiment. Various modifications or improvements can be added to the above-described embodiments without departing from the gist of the invention, and embodiments to which the modifications or improvements are added are also included in the technical scope of the present invention.

  In addition, each of the above embodiments does not limit the invention according to the claims (claims), and all combinations of features described in each embodiment are indispensable for solving means of the invention. Not necessarily. Each embodiment described above includes inventions at various stages, and various inventions are extracted by combining a plurality of disclosed constituent elements. Even if several constituent requirements are deleted from all the constituent requirements shown in the respective embodiments, the configuration from which these several constituent requirements are deleted can be extracted as an invention as long as the effect is obtained.

  For example, although cases have been described with the above embodiments where an abnormal nozzle determination processing routine program is executed for image data for detection in the determined application range, the present invention is not limited to this. For example, the processing of step 300 and step 302 of the abnormal nozzle determination processing routine program is performed on the entire range of the detection image data obtained by reading by the image reading unit 70. And it is good also as a form performed in the application range which determined the process of step 304 of an abnormal nozzle determination processing routine program.

  In the first embodiment and the second embodiment, the case where a rectangle is applied as the shape of the reference image K1 has been described. However, the present invention is not limited to this. For example, another shape such as a triangle or a circle may be applied as the shape of the reference image K1. Further, a special shape mark may be applied as the reference image K1.

  In each of the above embodiments, the case where the abnormal nozzle is detected by correcting the inclination of the detection image K2 by image processing such as image rotation processing has been described, but the present invention is not limited to this. . For example, the threshold used in the process of step 304 is corrected as the difference between the position of the upper and lower edges corresponding to the left edge detected by the process of step 224 and the position of the upper and lower edges corresponding to the right edge increases. Thus, an abnormal nozzle may be detected.

  In each of the above embodiments, the case where three image reading units 70 are provided has been described. However, the present invention is not limited to this. For example, two or four or more image reading units 70 may be provided.

  Although not specifically mentioned in the above embodiments, when the left and right edges of the detection image data are detected, after the test image T is read by the image reading unit 70, the resolution and image reading of the recording head 50 are read. The detection image data may be used in which the pixel position in the left-right direction of the detection image data is corrected based on the resolution of the unit 70. Specifically, as an example, when the resolution of the recording head 50 is 1200 dpi and the resolution of the image reading unit 70 is 600 dpi, the pixel positions in the left-right direction of the detection image data corresponding to the third and subsequent stages of the detection image K2 Is corrected to the left position by one pixel every two stages. As an example, FIGS. 21A to 21D are schematic diagrams of detection image data after correction of detection image data obtained by reading by the image reading unit 70 in this embodiment.

  21A shows detection image data after correction in the first embodiment, and FIG. 21B shows detection image data after correction in the second embodiment. FIG. 21C shows detection image data after correction in the third embodiment, and FIG. 21D shows detection image data after correction in the fourth embodiment. 21A to 21D indicate the applicable range. In this embodiment, the processing in step 220 in the detection processing program is not necessary.

  In each of the above embodiments, the case where a line sensor is applied as the image reading unit 70 has been described. However, the present invention is not limited to this. For example, an area sensor may be applied as the image reading unit 70.

  In each of the above embodiments, the detection image K2 is formed in a staircase pattern, but the present invention is not limited to this. For example, as shown in FIG. 22, the detection image K2 may be formed in a zigzag pattern.

  Further, although not particularly mentioned in each of the above embodiments, the presence or absence of an abnormal nozzle may be determined before specifying the nozzle number of the abnormal nozzle. In this case, for example, a mode in which a determination process for determining the presence or absence of an abnormal nozzle is performed between step 302 and step 304 of the abnormal nozzle determination process routine program. In addition, as the determination processing of this embodiment, there is a form in which it is determined that there is an abnormal nozzle when the number of the peak values protruding downward is different from the number of nozzles 52 used for forming the corresponding detection image K2. Illustrated. For the non-ejection abnormality, the presence or absence of an abnormal nozzle is determined by this determination.

  In each of the above embodiments, the case where one long head is applied as the recording head 50 has been described, but the present invention is not limited to this. For example, the recording head 50 may be configured by applying a plurality of short heads arranged in the crossing direction.

  In each of the above embodiments, the case where the present invention is applied to an ink jet recording apparatus has been described. However, the present invention is not limited to this. For example, the present invention may be applied to another image forming apparatus such as an LED (Light Emitting Diode) printer.

  In each of the above embodiments, the case where the continuous paper P is applied as the recording medium has been described. However, the present invention is not limited to this. For example, a standard cut sheet such as A4 or A3 may be applied as the recording medium. Further, the material of the recording medium is not limited to paper, and a recording medium of another material may be used.

  In each of the above embodiments, the case where various programs are installed in the ROM 82 in advance has been described. However, the present invention is not limited to this. For example, various programs may be provided by being stored in a storage medium such as a CD-ROM (Compact Disk Read Only Memory) or provided via a network.

  Further, although cases have been described with the above embodiments where detection processing is implemented by a software configuration using a computer by executing a program, the present invention is not limited to this. For example, the detection process may be realized by a hardware configuration or a combination of a hardware configuration and a software configuration.

  In addition, the configuration (see FIGS. 1 to 5) of the ink jet recording apparatus 10 described in the above embodiments is merely an example, and unnecessary portions may be deleted or new ones may be used without departing from the gist of the present invention. Needless to say, you can add parts.

  In addition, the flow of processing of various programs described in the above embodiments (see FIGS. 7, 10, 15, 18, and 20) is an example, and is not necessary within the scope of the present invention. It goes without saying that simple steps may be deleted, new steps may be added, and the processing order may be changed.

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 50 Recording head 52 Nozzle 70 Image reading part 80 CPU
82 ROM
K1 Reference image K2 Detection image P Continuous paper

Claims (7)

A plurality of recording elements arranged along a crossing direction that intersects the transport direction of the recording medium;
Each of the reading elements extends in the intersecting direction for reading an image formed on the recording medium by driving the recording element, and adjacent ends of the reading areas overlap with the transport direction. A plurality of reading means provided along the crossing direction;
The recording element that forms a reference image at a position on the recording medium corresponding to a predetermined position in a region where the end portions of the reading regions of the plurality of reading units overlap, and is a detection target of an abnormal state Forming means for forming an image for detection on the recording medium by varying the timing of driving the recording elements arranged continuously in the intersecting direction;
The present invention is applied to detection of an abnormal state with respect to detection image data obtained by reading the detection image by each of the plurality of reading units, with the reading position of each of the plurality of reading units reading the reference image as a boundary. A determination means for determining the scope of application;
Detecting means for detecting the recording element in an abnormal state using the image data for detection in the application range determined by the determining means;
Equipped with a,
The image forming apparatus forms the reference image and the detection image on the recording medium so that the reference image is included in a region where the detection image is formed . The determination unit includes the application range such that each of the read data read at each of the reading positions is included in the detection image data obtained by reading by any of the reading units that read the read data. The image forming apparatus according to claim 1. It said forming means, the image forming apparatus according to claim 1 or claim 2, wherein forming said reference image by driving said recording elements arranged in succession in the cross direction at the same timing. The recording element is an element that discharges droplets;
The forming means drives the recording elements so as to eject droplets having a size different from that for forming the detection image, and drives the recording elements arranged continuously in the intersecting direction. by varying the timing, an image forming apparatus according to claim 1, wherein forming the reference image on the recording medium. It said forming means, by varying the timing for driving the recording elements arranged in the intersecting direction to open the predetermined intervals, an image of claim 1, wherein forming the reference image on the recording medium Forming equipment. The number of reading means, an image forming apparatus according to any one of claims 1 to 5, which is three or more. A program for causing a computer to function as a forming unit, a determining unit, and a detecting unit of the image forming apparatus according to any one of claims 1 to 6 .

Images