JP5063147B2 - Image recording apparatus and recording failure detection method using the apparatus - Google Patents

Description

  The present invention relates to an image recording technique for recording an image by fixing ink on a recording medium such as paper or film, and in particular, to detect a recording defect caused by a nozzle provided in a recording head of an image recording apparatus. It relates to the technology to do.

  In an image recording apparatus that records an image by fixing ink on a large amount of recording medium such as paper or film, an image having different contents for each page while transporting the recording medium at a high speed of several tens to several hundreds m / min. There is something to record. In such high-speed image recording, it is impossible to visually verify whether the image data sent from the host device matches the recorded image by human eyes. On the other hand, in an image recording apparatus that forms an image by ejecting ink onto a recording medium, a nozzle missing defect is likely to occur due to clogging of the nozzle that ejects ink. Therefore, in such an image recording apparatus, a technique for detecting a recording defect by electronically reading a recorded image and comparing this image with an image represented by image data from a host apparatus for each pixel. Is used.

  With regard to such a technique, for example, Patent Document 1 discloses a technique for detecting a defect of a printed matter by extracting a difference between inspection image data and reference image data. In the technique of Patent Document 1, difference image data obtained by extracting a difference between reference image data and standard image data is first created, and an edge portion of a pattern portion is masked from the difference image data. The pixel values are integrated into Thereby, in the technique of Patent Document 1, it is determined that a defect has occurred when the integrated value is equal to or higher than a predetermined level.

For example, in the technique disclosed in Patent Document 2, the line drawing part expansion process of reference image data is first performed, and then pixel values are integrated within a predetermined range in the sub-scanning direction. Next, in the technique of Patent Document 2, the pixel values of the inspection image data are integrated within a predetermined range in the sub-scanning direction. In the technique of Patent Document 2, the print defect is determined by comparing the integrated values obtained in the portion where the recording is performed with the reference image data.
JP 11-348240 A JP 2003-94627 A

  However, in the case of an image recording failure due to a nozzle failure, the range of the defective portion becomes very narrow. For this reason, in the technique disclosed in Patent Document 2 described above, when an adjacent nozzle is affected by, for example, ink bleeding, the characteristics of the lens of the imaging system, the positional relationship between the imaging pixel and the nozzle, the pixel in the defective portion The value is not completely blank and a high density value is detected. As a result, in the technique disclosed in Patent Document 2 described above, there may be a case where it is erroneously determined that printing is performed even in a portion where a nozzle defect has occurred, which leads to a decrease in detection rate.

  Further, in the technique disclosed in Patent Document 1 described above, pixel values are integrated in a predetermined rectangular area, and therefore, in the case of a nozzle failure that appears as a thin line with low density, smoothing is performed when the density around is high. Therefore, the detection is considered difficult, which leads to a deterioration in the detection rate.

Therefore, the present invention has been made in view of the above-described problems, and an object of the present invention is to provide an image recording apparatus that detects a recording defect with high accuracy and high speed with a simple configuration, and a recording defect detection method using the apparatus. To do.

In order to achieve the above-described object, an image recording apparatus according to one aspect of the present invention receives ink from each nozzle of a nozzle array formed of a plurality of nozzles based on reference image data notified from a host apparatus. In an image recording apparatus that performs a recording process on a recording medium that is being conveyed along a conveyance path by discharging, an inspection image acquisition unit that images the recording medium after the recording process is performed and acquires inspection image data; A non-ejection detection unit that collates the reference image data with the inspection image data and detects a recording failure due to non-ejection of the nozzle, and the non-ejection detection unit constitutes each of the reference image data and the inspection image data Among the three pixels adjacent in the direction of the nozzle row in the selected pixel, when the luminance of the central pixel is the highest, the luminance value of the central pixel and the pixels adjacent to the central pixel That is, the difference between the luminance value with the higher luminance is set as the post-conversion pixel value of the central pixel, and in other cases, the conversion processing for setting the post-conversion pixel value of the central pixel to zero is performed as the reference image data and the inspection image data. The first image conversion unit that generates the first conversion reference image data and the first conversion inspection image data, respectively, and the first conversion reference image data and the first conversion inspection image data are subtracted for each constituent pixel. And determining whether there is a defect in the inspection image data with respect to the reference image data based on the first difference image data, and determining the result of the nozzle failure And at least a first determination unit that obtains a detection result of recording failure due to ejection.

According to another aspect of the present invention, there is provided a recording failure detection method in which ink is ejected from each nozzle of a nozzle array formed of a plurality of nozzles based on reference image data notified from a host device. A recording failure detection method by an image recording apparatus that performs a recording process on a recording medium that is being transported along a transport path, in which a recording medium after the recording process is performed is imaged to obtain inspection image data, and a reference image Among the three pixels adjacent to each other in the direction of the nozzle row in the pixels constituting each of the data and the inspection image data, the luminance value of the center pixel and the center The reference image is a conversion process in which the difference between the luminance value of the higher luminance of the pixels on both sides of the pixel is the converted pixel value of the central pixel, and in other cases, the converted pixel value of the central pixel is zero. Data and The first conversion reference image data and the first conversion inspection image data are respectively generated by applying to the inspection image data, and the first conversion reference image data and the first conversion inspection image data are subtracted for each constituent pixel. 1st difference image data is generated, and the presence or absence of inspection image data with respect to the reference image data is determined based on the first difference image data, and the inspection image data is defective with respect to the reference image data based on the first difference image data. It is characterized in that the presence / absence of printing is determined, and the determination result is used as a detection result of recording failure due to nozzle ejection failure.

According to the present invention, accurately with a simple configuration, and high speed image recording apparatus for detecting a recording failure due to non-ejection nozzle, and can provide a record defect detection method according to the apparatus.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In the following description, the conveyance direction of the recording medium is defined as the sub-scanning direction, and the direction orthogonal to the conveyance direction is defined as the main scanning direction.

FIG. 1 shows a conceptual block configuration of an image recording apparatus according to the present invention.
FIG. 2 schematically shows an arrangement example of each component of the image recording apparatus according to the present invention.

1 and 2 are diagrams comprehensively showing image recording apparatuses according to first and second embodiments to be described later.
First, a first embodiment of an image recording apparatus for carrying out the present invention will be described.

  The image recording apparatus 1 according to the present invention discharges and fixes ink onto a recording medium (sheet) such as paper or film based on image data sent from a host apparatus 12 that transmits original information to be recorded. Thus, a recording process for recording an image and a recording defect detection process for detecting a recording defect that may occur during the recording process are performed.

  The image recording apparatus 1 includes a mode setting unit 2, a recording unit 7, a non-ejection detection unit 9 (9A, 9B, 9C), 9 (9α, 9β), a control unit 8 including a storage unit 10, and sheet feeding. A sheet conveyance mechanism 3 including at least a section 4, a sheet support section 5, and a sheet collection section 6.

  Note that the image recording apparatus 1 includes an imaging unit 11a and an illumination unit 11b, and an inspection image acquisition unit 11 used for detecting a recording failure is connected via a connection interface. Further, a host device 12 (for example, a host computer) for notifying the image recording device 1 of original information (job information) including image data is connected to the image recording device 1 via a LAN (Local Area Network) or the like. .

  The mode setting unit 2 selects either an operation mode for performing normal recording processing or an operation mode for performing recording failure detection (non-ejection detection) from among the operation modes representing the operation state of the image recording apparatus 1. The user selection result is acquired as the operation mode setting result. The mode setting unit 2 is, for example, a switch provided on the operation panel of the image recording apparatus 1, but instead of this, for example, by driver software executed by the host apparatus 12 to enable control of the image recording apparatus 1, A user interface such as a GUI (Graphical User Interface) functioning as the mode setting unit 2 may be set from the display unit and the operation input unit of the host device 12.

  The sheet transport mechanism 3 transports the recording medium (sheet) 13. When a command for conveying the sheet 13 to the sheet conveying mechanism 3 is issued by the control unit 8, the sheet conveyance driving unit 6 b (for example, a motor) of the sheet collecting unit 6 is driven, and thereby the sheet of the sheet feeding unit 4 is driven. The sheet 13 wound around the support member 4 a is conveyed via the sheet support portion 5. The sheet support unit 5 applies a predetermined tension to the conveyed sheet 13 by the sheet tension roller pair 5a and the sheet support roller pair 5b. Note that a sheet conveyance information generation unit 6c (for example, a rotary encoder) is connected to the sheet support member 6a of the sheet collection unit 6, and a pulse signal corresponding to the conveyance amount (movement amount) of the sheet 13 is generated and controlled. The configuration is made to notify the unit 8.

  For example, the recording unit 7 supplies the recording heads 7-1 to 7-4 for each color in the order of K (black), C (cyan), M (magenta), and Y (yellow) from the upstream side of the conveyance path of the sheet 13. A plurality of nozzles of the same color are arranged in the main scanning direction so as to be arranged substantially parallel to the scanning direction. In response to a command from the control unit 8, the recording unit 7 performs sheet 13 from the plurality of nozzles of the recording heads 7-1 to 7-4 at a predetermined timing synchronized with the pulse signal generated by the sheet conveyance information generation unit 6 c. A recording process is performed by ejecting each color ink.

  The control unit 8 controls each component of the image recording apparatus 1 including control based on the non-ejection detection unit 9. The control unit 8 includes, for example, an MPU (Micro Processor Unit) having a control function and an arithmetic function, a ROM (Read Only Memory) storing a control program, a RAM (Random Access Memory) serving as an MPU work memory, and the like. And a non-volatile memory for storing setting values relating to control of the image recording apparatus 1 and a connection interface for the inspection image acquisition unit 11 described above. Here, the MPU can control each component of the image recording apparatus 1 including control based on the non-ejection detection unit 9 by executing a predetermined control program. This control program is stored in advance in the ROM. The RAM is also used as the storage unit 10 described above, and parameters and the like used for recording failure detection are stored in the nonvolatile memory.

The non-ejection detection unit 9 can also be configured as a processing circuit (hardware) controlled by the MPU.
The non-ejection detection unit 9 includes an image conversion unit 9A, a difference image generation unit 9B, and a determination unit 9C in a processing block of a program or a processing circuit. Alternatively, the non-ejection detection unit 9 includes the image defect determination unit 9α as a partial process of the image conversion unit 9A, the difference image generation unit 9B, and the determination unit 9C and the other of the determination unit 9C in the processing block of the program or the processing circuit. A non-ejection process determination unit 9β as a partial process. (Details will be described later).

  The inspection image acquisition unit 11 is used for reading the recording-processed sheet 13, and includes at least the imaging unit 11a and the illumination unit 11b as described above. In the arrangement example of each component of the image recording apparatus 1 shown in FIG. 2, the inspection image acquisition unit 11 is disposed on the downstream side of the recording unit 7, and the mode setting unit 2 detects the recording failure. Is set, the inspection image acquisition unit 11 reads the sheet 13 in the process of transporting the sheet 13 after the recording process, so that it is possible to efficiently determine the recording defect. However, instead of this, the image recording apparatus 1 can also configure the inspection image acquisition unit 11 as an external device separate from the image recording apparatus 1.

  When the mode setting unit 2 described above sets a mode for detecting a recording defect, the image recording apparatus 1 can read the recording medium 13 after the recording process by the inspection image acquisition unit 11 in the course of the conveyance.

Next, a recording failure determination method performed by the non-ejection detection unit 9 of the control unit 8 will be described.
3, 4, and 5 illustrate examples of recording defects that appear on a recording medium that has been subjected to recording processing when non-ejection due to a nozzle failure has occurred.

  Here, the 1st example shown in FIG. 3 has shown the example in which the white stripe 21 generate | occur | produced in the natural image 20 by non-ejection. In addition, the second example shown in FIG. 4 shows a case where non-ejection has occurred in the recording process of the extremely small text in which the vertical line is expressed by one pixel width. Originally, the recording is performed like the regular text image 22. What should be done is an example recorded as a bad text image 23. Further, the third example shown in FIG. 5 shows a case where non-ejection has occurred at the edge of a recorded image having a width of 2 pixels or more, and should be recorded like the regular recorded image portion 24 originally. However, the example recorded like the defect recording image part 25 is shown.

  FIG. 6 shows an enlarged view of a defective pixel and its neighboring pixels in each of these three types of defects. The recording failure when the ejection failure due to the nozzle failure occurs is classified into three types (A), (B), and (C) shown in FIG.

  (A) shows a “recording part interruption” state. In the normal state 26, pixels to be recorded continuously in the main scanning direction are interrupted in the defective state 27. Further, (B) shows the “extinction of the fine recording portion” state. In the normal state 28, one pixel to be recorded between the left and right adjacent pixels in the main scanning direction is in the defective state 29. Not recorded. Further, (C) shows the “thinning of the recording portion” state. Since the end portion of the image portion that should be continuously recorded is not recorded in the normal state 30, the width of the image portion in the defective state 31. Appears thinly.

  Among these three types of recording failure examples, the “recording portion narrowed” state shown in FIG. 5 (that is, FIG. 6C) is difficult to visually discriminate, and the recording after the recording process is performed. There are almost no errors in the recorded characters that the user who sees the medium misidentifies, and there is no disturbance in the recorded image that causes discomfort. Therefore, here, the “recording portion narrowing” state is not detected, and only the “recording portion interruption” and “thin recording portion disappearance” states are detected as recording failures.

Next, detection of non-ejection due to nozzle failure based on the above-described recording failure determination will be described with reference to FIG.
FIG. 7 is a process block diagram illustrating an outline of the non-ejection detection process.

  In FIG. 7, an image conversion unit 9A including a conversion process A40, a conversion process B41, a conversion process C42, and a conversion process D43, a difference image generation unit 9B including a difference extraction process A44 and a difference extraction process B45, a determination process A46, A determination unit 9C including a determination process B47 and a logical sum process 48 is shown.

  In FIG. 7, the image conversion unit 9 </ b> A, the difference image generation unit 9 </ b> B, the image defect determination unit 9 </ b> α including the determination process A <b> 46 and the determination process B <b> 47, the non-ejection process determination unit 9 </ b> β including the logical sum process 48, It is shown.

  In FIG. 7, conversion processing A40 and conversion processing B41, difference extraction processing A44, and determination processing A46 are processing for detecting the “recording unit interruption” state shown in FIG. 3 (that is, FIG. 6A). Corresponding to Further, the conversion process C42, the conversion process D43, the difference extraction process B45, and the determination process B47 are processes for detecting the “extinction of the fine recording portion” state shown in FIG. 4 (that is, FIG. 6B). Correspond.

  First, the conversion process A40 and the conversion process C42 are respectively performed on the reference image data input from the host apparatus 12 to the image recording apparatus 1 to generate two conversion reference image data A and B. On the other hand, the conversion processing B41 and the conversion processing D43 are respectively performed on the inspection image data (recorded image data on the recording medium 13) acquired by the imaging unit 11a of the inspection image acquisition unit 11, and two conversion inspection image data A are obtained. And B are generated.

  Next, a difference extraction process A44 is performed for the conversion reference image data A and the conversion inspection image data A, and a difference extraction process B45 is performed for the conversion reference image data B and the conversion inspection image data B, respectively. Subtraction processing is performed, and difference image data A and difference image data B are generated. The difference image data A and B are subjected to determination processing in determination processing A46 and determination processing B47, respectively. Here, when a determination result indicating that there is a non-ejection is obtained, non-ejection nozzle information A or B for specifying a non-ejection nozzle is generated by the determination process A 46 or the determination process B 47 and output to the host device 12. The Further, the logical sum of the two determination results output from the determination processing A 46 and the determination processing B 47 is obtained by the logical sum processing 48, and the final determination result of the recording failure is output to the host device 12.

In the following description, “a pixel on both sides” of the pixel of interest is defined as a pixel on both sides in the main scanning direction with respect to the pixel of interest unless otherwise specified.
Next, a method for detecting the “recording unit interruption” state realized by the conversion processing A40 and conversion processing B41, the difference extraction processing A44, and the determination processing A46 shown in FIG. 7 will be described with reference to FIG. .

  8A is an example of reference image data input from the host device 12 to the image recording apparatus 1, and FIG. 8B is an example of inspection image data acquired by the imaging unit 11 a of the inspection image acquisition unit 11. is there. However, in the example of the inspection image data in (B), the “discontinuation of the recording portion” state occurs because non-ejection due to nozzle failure occurs in the sixth nozzle counted in the main scanning direction. An example is shown.

  These data constitute a reference image to be recorded and an image (inspection image) recorded on the recording medium 13 by the image recording apparatus 1 executing a recording process for recording the reference image. The brightness of each pixel is represented by 256 gradation values from “0” to “255”. This numerical value indicates that the larger the pixel is, the higher the luminance (that is, brighter), and the smaller the numerical value indicates that the pixel has the lower luminance (that is, darker).

First, the conversion process A40 shown in FIG. 7 will be described.
The conversion process A40 converts the reference image data (A) in FIG. 8 into conversion reference image data A shown in (C). This conversion will be described. First, attention is paid to one of the pixels in which the luminance value is arranged as the reference image data, and further, the luminance values of pixels adjacent to the target pixel are referred to. Then, the higher luminance is selected from the luminance values of the adjacent pixels, and the selected luminance value is subtracted from the luminance value of the target pixel. However, when the sign of the value of the subtraction result is negative, “0” is set as the calculation result. In other words, the conversion processing A40 is the center pixel of the three pixels adjacent in the direction of the nozzle row in the pixels constituting each of the reference image data and the inspection image data. When the luminance of the pixel of interest (ie, the target pixel) is the highest, the difference between the luminance value of the central pixel and the luminance value of the higher luminance of the pixels adjacent to the central pixel is used as the post-conversion pixel value of the central pixel. In other cases, conversion is performed in which the converted pixel value of the central pixel is zero (“0”).

  Among the reference image data in (A), the conversion reference image data A in (C) is obtained by obtaining this calculation result for all the pixels excluding the pixels at both ends in the main scanning direction and arranging them in the pixel arrangement order. is there. Each value indicated in the conversion reference image data A represents how bright the target pixel is with respect to the pixels on both sides thereof (how high the brightness is). It shows that the pixels on both sides are extremely bright.

Next, the conversion process B41 shown in FIG. 7 will be described.
The conversion process B41 converts the inspection image data (B) in FIG. 8 into the converted inspection image data A shown in (D). The conversion method performed by the conversion process B41 is exactly the same as the conversion process A40. Therefore, each value shown in the converted inspection image data A shown in (D) represents how bright the target pixel is with respect to the adjacent pixels (how high the brightness is), and the value is large. This indicates that the target pixel is extremely bright with respect to the pixels on both sides.

Next, the difference extraction process A44 shown in FIG. 7 will be described.
The difference extraction process A44 performs an operation of subtracting the conversion reference image data A (C) for each pixel from the conversion inspection image data A (D) in FIG. However, when the sign of the value of the subtraction result is negative, “0” is set as the calculation result. The difference image data A in (E) is obtained by obtaining the calculation results and arranging them according to the arrangement order of the pixels.

  Referring to the difference image data A, it can be seen that the value of the fifth pixel counted in the main scanning direction is significantly larger than the values of the other pixels. Here, a pixel having a large numerical value indicates that the inspection image has an extremely bright relationship with respect to both adjacent pixels, but the reference image does not have such a relationship. It is clear that Therefore, it is presumed that the nozzle that should eject ink to this pixel (that is, the sixth nozzle in the main scanning direction in the example of FIG. 8) is highly likely to have a defective ink non-ejection. be able to.

Next, the determination process A46 shown in FIG. 7 will be described.
In the determination process A46, first, the values constituting the difference image data A of (E) arranged according to the arrangement of each pixel are integrated in the sub-scanning direction (the sum in the sub-scanning direction is obtained). . The calculated difference image data (F) is obtained by obtaining the calculation results and arranging them according to the arrangement order of the pixels. Next, the determination process A46 compares the values of the integrated image data with a predetermined threshold value (eg, “500” in the example of FIG. 8). Here, when a value larger than this threshold value is present in the integrated image data, it is determined that an ink non-ejection defect has occurred in a nozzle that should eject ink to the pixel corresponding to that value. I will give you. On the other hand, when a value larger than this threshold does not exist in the integrated image data, it is determined that no ink ejection failure has occurred.

As described above, the “recording unit interruption” state is detected by the conversion process A40, the conversion process B41, the difference extraction process A44, and the determination process A46.
Next, with reference to FIG. 9, a method for detecting the “extinction of the fine recording portion” state, which is realized by the conversion processing C42 and the conversion processing D43, the difference extraction processing B45, and the determination processing B47 shown in FIG. To do.

  9A is an example of reference image data input from the host device 12 to the image recording apparatus 1, and FIG. 9B is an example of inspection image data acquired by the imaging unit 11 a of the inspection image acquisition unit 11. is there. However, in the example of the inspection image data in (B), when the non-ejection due to the nozzle failure occurs in the seventh nozzle counted in the main scanning direction, the “extinction of the fine recording portion” state occurs. An example is shown.

  Similar to the data shown in FIG. 8, these data are recorded on the recording medium 13 as a result of the image recording apparatus 1 executing the recording process for recording the reference image to be recorded and the reference image. The brightness of each pixel constituting each of the inspection image) is represented by 256 gradation values from “0” to “255”. Similarly to the value shown in FIG. 8, the numerical value indicates that the pixel has higher luminance (that is, brighter), and the smaller value indicates that the pixel has lower luminance (that is, darker). ing.

First, the conversion process C42 shown in FIG. 7 will be described.
The conversion process C42 converts the reference image data (A) in FIG. 9 into conversion reference image data B shown in (C). This conversion will be described. First, attention is paid to one of the pixels in which the luminance value is arranged as the reference image data, and further, the luminance values of pixels adjacent to the target pixel are referred to. Up to this point, the process is the same as the conversion process A40 shown in FIG. However, the conversion process C42 is different from the conversion process A40 in that the lower one of the luminance values of the adjacent pixels is selected and an operation of subtracting the luminance value of the target pixel from the selected luminance value is performed. . However, when the sign of the value of the subtraction result is negative, “0” is set as the calculation result. In other words, the content of this processing by the conversion processing C42 is that the conversion processing C42 is the pixel at the center of the three pixels adjacent in the direction of the nozzle row in the pixels constituting each of the reference image data and the inspection image data. When the luminance of the pixel of interest (ie, the target pixel) is the lowest, the difference between the luminance value of the central pixel and the lower luminance value of the pixels adjacent to the central pixel is used as the converted pixel value of the central pixel. In other cases, conversion is performed in which the converted pixel value of the central pixel is zero (“0”).

  Among the reference image data in (A), the conversion reference image data B in (C) is obtained by obtaining this calculation result for all the pixels except the pixels at both ends in the main scanning direction and arranging them in the pixel arrangement order. is there. Each value shown in the conversion reference image data B represents how dark the target pixel is with respect to the adjacent pixels (how low the brightness is). This indicates that the pixels on both sides are extremely dark.

Next, the conversion process D43 shown in FIG. 7 will be described.
The conversion process D43 converts the inspection image data (B) in FIG. 9 into the converted inspection image data B shown in (D). The conversion method performed by the conversion process D43 is exactly the same as the conversion process C42. Therefore, each value shown in the converted inspection image data B shown in (D) represents how dark the target pixel is with respect to the adjacent pixels (how low the brightness is), and the value is large. As shown, the pixel of interest is extremely dark with respect to the pixels on both sides.

Next, the difference extraction process B45 shown in FIG. 7 will be described.
The difference extraction processing B45 performs an operation of subtracting the converted inspection image data B of (D) from the conversion reference image data B of (C) in FIG. 9 for each pixel. However, when the sign of the value of the subtraction result is negative, “0” is set as the calculation result. The difference image data B of (E) is obtained by obtaining the calculation results and arranging them according to the pixel arrangement order.

  Referring to the difference image data B, it can be seen that the value of the sixth pixel counted in the main scanning direction is significantly larger than the values of the other pixels. Here, a pixel having a large numerical value indicates a pixel that has an extremely dark relationship with the adjacent pixels in the reference image but does not have such a relationship in the inspection image. It is clear that Accordingly, it is presumed that the nozzle that should eject ink to this pixel (that is, the sixth nozzle in the main scanning direction in the example of FIG. 9) is highly likely to have a defective ink non-ejection. be able to.

Next, the determination process B47 shown in FIG. 7 will be described.
The determination method performed by the determination process B47 is exactly the same as the determination process A46. That is, in the determination process B47, first, the values constituting the difference image data B of (E) arranged according to the arrangement of each pixel are integrated in the sub-scanning direction (the sum in the sub-scanning direction is obtained). I do. The calculated difference image data (F) is obtained by obtaining the calculation results and arranging them according to the arrangement order of the pixels. Next, the determination process B47 compares the values of the integrated image data with a predetermined threshold value (eg, “500” in the example of FIG. 8). Here, when a value larger than this threshold value is present in the integrated image data, it is determined that an ink non-ejection defect has occurred in a nozzle that should eject ink to the pixel corresponding to that value. I will give you. On the other hand, when a value larger than this threshold does not exist in the integrated image data, it is determined that no ink ejection failure has occurred.

As described above, the detection of the “extinction of the fine recording portion” state is performed by the conversion process C42, the conversion process D43, the difference extraction process B45, and the determination process B47.
Next, the non-ejection detection process according to the first embodiment will be described with reference to FIG.

FIG. 10 is a flowchart showing the processing contents of the non-ejection detection processing according to the first embodiment.
In the description of the figure, for example, the MPU of the control unit 8 reads out and executes a control program stored in the ROM, and functions as the non-ejection detection unit 9 for performing this non-ejection detection process. And

First, in step SA1, the control unit 8 performs a process of receiving the reference image data from the host device 12.
Next, in step SA2, the control unit 8 executes the conversion process A40 described above on the reference image data received in step SA1 to generate conversion reference image data A, and stores it in a predetermined storage area MA1 of the storage unit 10. Process to memorize.

  Next, in step SA3, the control unit 8 executes the conversion process C42 described above on the reference image data received in step SA1 to generate conversion reference image data B, and stores it in a predetermined storage area MA2 of the storage unit 10. Process to memorize.

Next, in step SA4, the control unit 8 performs a process of receiving the inspection image data acquired by the imaging unit 11a from the inspection image acquisition unit 11.
Next, in step SA5, the control unit 8 executes the conversion process B41 described above on the inspection image data received in step SA4 to generate the converted inspection image data A, and stores it in a predetermined storage area MA3 of the storage unit 10. Process to memorize.

  Next, in step SA6, the control unit 8 generates the converted inspection image data B by executing the conversion process D43 described above on the inspection image data received in step SA4, and stores it in a predetermined storage area MA4 of the storage unit 10. Process to memorize.

  Next, in step SA7, the control unit 8 reads out the conversion reference image data A stored in the storage area MA1 of the storage unit 10 and the conversion inspection image data A stored in the storage area MA3. The difference extraction process A44 described above is executed on the data to generate the difference image data A.

Next, in Steps SA8 and SA9, the control unit 8 performs the above-described determination process A46 on the generated difference image data A.
That is, in step SA8, the control unit 8 performs a process of generating integrated difference image data by integrating each value constituting the generated difference image data A in the paper transport direction (that is, the sub-scanning direction). In step SA9, the control unit 8 compares each value of the integrated difference image data with a predetermined threshold value A. Here, the control unit 8 advances the process to step SA10 when any of the values of the accumulated difference image data is larger than the threshold A (when the result of the determination process in step SA9 is Yes), and integrates the accumulated difference image data. When none of the values of the difference image data is larger than the threshold A (when the result of the determination process in step SA9 is No), the process proceeds to step SA12.

  In step SA10, the control unit 8 determines the coordinates in the main scanning direction of the pixel whose accumulated difference image data value is larger than the threshold value A as the ink non-ejection in the “non-ejection nozzle information A” (“recording unit interruption” state). As information for specifying a nozzle in which a defect is detected, a process of storing the nozzle in a predetermined storage area of the storage unit 10 is performed. In step SA11, the control unit 8 sets “Fail” as “determination result A”, which is flag information indicating the result of failure detection in the “recording unit interruption” state, and sets the “recording unit interruption” state. A process indicating that a defect is detected is performed, and then the process proceeds to step SA13.

  On the other hand, in step SA12, the control unit 8 sets the flag information “determination result A” to “Pass” and performs a process indicating that no defect in the “recording unit interruption” state has been detected.

  Next, in step SA13, the control unit 8 reads out the conversion reference image data B stored in the storage area MA2 of the storage unit 10 and the conversion inspection image data B stored in the storage area MA4, and these The difference extraction process B45 described above is executed on the data to generate the difference image data B.

Next, the control part 8 performs the determination process B47 mentioned above with respect to the produced | generated difference image data B in step SA14 and SA15.
That is, in step SA14, the control unit 8 performs a process of generating integrated difference image data by integrating each value constituting the generated difference image data B in the paper transport direction (that is, the sub-scanning direction). In step SA15, the control unit 8 compares each value of the accumulated difference image data with a predetermined threshold value B. Here, the control unit 8 advances the process to step SA16 when any of the values of the accumulated difference image data is larger than the threshold value B (when the result of the determination process in step SA15 is Yes), and integrates the accumulated difference image data. When none of the values of the difference image data is larger than the threshold value B (when the result of the determination process in step SA15 is No), the process proceeds to step SA18.

  In step SA16, the control unit 8 determines the coordinates in the main scanning direction of the pixel whose accumulated difference image data value is larger than the threshold value B as the ink non-ejection in the “non-ejection nozzle information B” (“extinction of fine recording portion” state). (Information for specifying the nozzle in which the defect is detected) is stored in a predetermined storage area of the storage unit 10. In step SA17, the control unit 8 sets “Fail” as “determination result B”, which is flag information indicating the result of defect detection in the “annihilation of the fine recording unit” state, and sets “deletion of the fine recording unit”. The process indicating that a defect in the state has been detected is performed, and thereafter, the process proceeds to step SA19.

  On the other hand, in step SA18, the control unit 8 sets the flag information “determination result B” to “Pass”, and performs a process indicating that no defect in the “fine recording unit disappeared” state is detected.

  Next, in step SA19, the control unit 8 performs a logical sum process 48 on the “determination result A” and the “determination result B” which are flag information, and flag information indicating the detection result of the ink non-ejection defect. A process of setting the result of the logical sum in “judgment result” is performed. Accordingly, in the “determination result”, if any one of the “recording portion interruption” state and the “thin recording portion disappearance” state is detected, “Fail” is set and the ink non-ejection failure is detected. Is detected, and if neither of these defects is detected, “Pass” is set to indicate that no ink ejection failure has been detected.

Next, the control unit 8 performs a process of outputting the “determination result” to the host device 12 in step SA20.
Next, in step SA21, the control unit 8 performs a process of determining whether or not the “determination result” is set to “Fail”, that is, whether or not an ink non-ejection defect is detected. Here, only when the “determination result” is set to “Fail” (only when the determination result is Yes), the control unit 8 stores the storage unit 10 in step SA10 or SA16 described above in step SA22. A process of outputting coordinates stored in a predetermined storage area (that is, “non-ejection nozzle information A” or “non-ejection nozzle information B”) to the host apparatus 12 is performed.

  Next, in step SA23, the control unit 8 performs a process of determining whether or not the recording process in the image recording apparatus 1 has been completed. Here, when it is determined that the recording process has ended (when the determination result is Yes), the control unit 8 ends the non-ejection detection process. On the other hand, when it is determined that the recording process has not yet ended (when the determination result is No), the control unit 8 returns the process to step SA4 and repeats the processes after step SA4.

  The above processing is the non-ejection detection processing. The control unit 8 functions as the non-ejection detection unit 9 by executing this process, and the image recording apparatus 1 can detect the non-ejection defect and specify the defective nozzle.

  As described above, according to the first embodiment, the detection means specialized for each of a plurality of characteristics that can be caused by the defective image due to the non-ejection of the nozzle among the image recording defects is combined. As a result, it is possible to detect a recording failure due to nozzle non-ejection at high speed with a simple configuration with high accuracy.

  In the first embodiment described above, the logical sum of the “judgment result A” and the “judgment result B” is obtained by the logical sum process 48, and the “judgment result” that is the result of the logical sum is not ejected. Is output to the host device 12 as a result of detection of a failure. Instead, in the first embodiment, both the “determination result A” and the “determination result B” are output to the host device 12 as the detection result of the ink non-ejection defect without obtaining the logical sum. It may be.

  Further, in the first embodiment described above, the flag information of “determination result” and the non-ejection nozzle information A or the non-ejection nozzle information B are output to the host device 12 and the information is displayed on the host device 12. Etc. to notify the user. Instead, in the first embodiment, the image recording apparatus 1 is provided with a display unit, the detection result of the non-ejection failure indicated by the “determination result”, the non-ejection nozzle information A or the non-ejection nozzle information. The information may be notified to the user by displaying both or one of B on the display unit.

Next, a second embodiment of the image apparatus for carrying out the present invention will be described.
The block configuration and arrangement configuration of the image recording apparatus according to the second embodiment are the same as those according to the first embodiment shown in FIGS. In addition, the recording failure determination method and the outline of the non-ejection detection process performed by the non-ejection detection unit 9 of the control unit 8 in the second embodiment are the same as those according to the first embodiment.

FIG. 11 will be described.
FIG. 11 is a flowchart showing the processing contents of the non-ejection detection processing according to the second embodiment.

  In the description of the figure, for example, the MPU of the control unit 8 reads and executes a control program stored in the ROM, thereby functioning as the non-discharge detection unit 9 for performing the non-discharge detection process. Shall.

The non-ejection detection process shown in FIG. 11 is a process suitable when the reference image data covers a plurality of pages having different recording contents for each page.
In FIG. 11, the flowchart of (A) shows the process for receiving the reference image data from the host device 12, and the flowchart of (B) shows the reception and recording failure of the inspection image data from the inspection image acquisition unit 11. Shows the process for detection and detection. Note that the control unit 8 executes these two processes independently in parallel.

First, the process in FIG. 11A will be described.
First, in step SB1, the control unit 8 performs a process of receiving the reference image data for one page from the host device 12.

  Next, in step SB2, the control unit 8 executes the conversion process A40 described above on the reference image data received in step SB1 to generate conversion reference image data A, and stores it in a predetermined storage area MB1 of the storage unit 10. Process to memorize. The storage area MB1 has a storage capacity capable of storing the conversion reference image data A over a plurality of pages, and the control unit 8 stores the conversion reference image data A in the order of generation for each page. Remember me.

  Next, in step SB3, the control unit 8 generates the conversion reference image data B by executing the conversion process C42 described above on the reference image data received in step SB1, and stores it in a predetermined storage area MB2 of the storage unit 10. Process to memorize. The storage area MB2 also has a storage capacity capable of storing the conversion reference image data B over a plurality of pages, and the control unit 8 stores the conversion reference image data B in the order of generation for each page. Remember me.

  Next, in step SB4, the control unit 8 performs a process of determining whether or not the upper level apparatus 12 has prepared the reference image data of the next page following the one received in step SB1 executed most recently. Here, when the control unit 8 determines that the reference image data of the next page is prepared (when the determination result is Yes), the control unit 8 returns the process to step SB1, and repeats the processes after step SB1. On the other hand, when it is determined that the reference image data for the next page is not prepared (when the determination result is No), the control unit 8 advances the process to step SB5.

  Next, in step SB5, the control unit 8 performs a process for determining whether or not the recording process in the image recording apparatus 1 has been completed. Here, when it is determined that the recording process has been completed (when the determination result is Yes), the control unit 8 ends the process (A). On the other hand, when it is determined that the recording process has not yet ended (when the determination result is No), the control unit 8 returns the process to step SB4 and repeats the processes after step SB4.

Next, the process in FIG. 11B will be described.
First, in step SB6, the control unit 8 performs a process of receiving the inspection image data acquired by the imaging unit 11a from the inspection image acquisition unit 11.

  Next, in step SB7, the control unit 8 generates the converted inspection image data A by executing the conversion process B41 described above on the inspection image data received in step SB6, and stores it in a predetermined storage area MB3 of the storage unit 10. Process to memorize.

  Next, in step SB8, the control unit 8 generates the converted inspection image data B by executing the conversion process D43 described above on the inspection image data received in step SB6, and stores it in a predetermined storage area MB4 of the storage unit 10. Process to memorize.

  Next, in step SB9, the control unit 8 reads all the conversion reference image data A stored in the storage area MA1 of the storage unit 10 and the conversion inspection image data A stored in the storage area MA3. The above-described difference extraction processing A44 is executed on these data to generate the difference image data A.

Next, the control part 8 performs the determination process A46 mentioned above with respect to the produced | generated difference image data A in step SB10 and SB11.
That is, in step SB10, the control unit 8 performs a process of generating integrated difference image data by integrating the values constituting the generated difference image data A in the paper transport direction (that is, the sub-scanning direction). In step SB11, the control unit 8 compares each value of the accumulated difference image data with a predetermined threshold value A. Here, the control unit 8 advances the process to step SB12 when any of the values of the accumulated difference image data is greater than the threshold A (when the result of the determination process in step SB11 is Yes), and integrates the accumulated difference image data. When none of the values of the difference image data is larger than the threshold A (when the result of the determination process in Step SB11 is No), the process proceeds to Step SB14.

  Next, in step SB12, the control unit 8 sets the coordinates in the main scanning direction of the pixel whose accumulated difference image data value is larger than the threshold A as “non-ejection nozzle information A” in a predetermined storage area of the storage unit 10. Process to memorize. In step SB13, the control unit 8 sets “Fail” as “determination result A”, which is flag information indicating the result of failure detection in the “recording unit interruption” state, and sets the “recording unit interruption” state. The process which shows that the defect of this was detected is performed, and a process is advanced to step SB15 after that.

  On the other hand, in step SB14, the control unit 8 sets the flag information “determination result A” to “Pass”, and performs a process indicating that no defect in the “recording unit interruption” state has been detected.

  Next, in step SB15, the control unit 8 reads out all the conversion reference image data B stored in the storage area MA2 of the storage unit 10 and the converted inspection image data B stored in the storage area MA4. The difference extraction process B45 described above is executed on these data to generate the difference image data B.

  The subsequent processing from step SB16 to step SB25 is the same as the processing from step SA14 to step SA23 in the non-ejection detection processing in the first embodiment shown in the flowchart in FIG.

  The above processing is the non-ejection detection processing. The control unit 8 functions as the non-ejection detection unit 9 by executing this process, and the image recording apparatus 1 can detect the non-ejection defect and specify the defective nozzle.

  As described above, according to the second embodiment, even if the reference image data covers a plurality of pages having different recording contents for each page, as in the first embodiment described above, an image recording failure is detected. Above all, in particular, by combining detection means specialized for each of a plurality of features that may have image defects due to nozzle non-ejection, recording failure due to nozzle non-ejection at high speed with a simple configuration is possible. Can be detected.

  In the second embodiment, both the “determination result A” and the “determination result B” are output to the host device 12 as the detection result of the ink non-ejection defect without obtaining the logical sum. May be. Also in the second embodiment, the image recording apparatus 1 is provided with a display unit, and the detection result of the ink non-ejection failure indicated by the “determination result” and the nozzle where the ink non-ejection failure is detected are provided. The information may be configured to be notified to the user by displaying both or one of the specified information on the display unit.

  If the reference image is not a single color but a color image, the non-ejection detection process outlined in FIG. 7 may be modified as shown in FIG. 12 and executed by the control unit 8. Good.

Next, the modification shown in FIG. 12 will be described.
Assume that the reference image data is color image data represented by three primary colors of light of R (red), G (green), and B (blue) as shown in FIG. When recording the reference image data, the image recording apparatus 1 converts the image data into KCMY four-color data and performs a recording process on the recording medium 13 with four-color inks. On the other hand, the imaging unit 11a of the inspection image acquisition unit 11 captures a recorded image on the recording medium 13 and outputs inspection image data. This inspection image data is also RGB color image data.

  The reference image data input from the host device 12 to the image recording apparatus 1 is subjected to RGB division processing A50 by the control unit 8 as shown in FIG. 12, and is divided into three single-color reference image data for each color of RGB. Is done. Further, the inspection image data acquired by the imaging unit 11a of the inspection image acquisition unit 11 is subjected to RGB division processing B51 by the control unit 8, and is divided into three single-color inspection image data of each RGB color.

In this modification, non-ejection detection processing similar to that shown in FIG. 7 is performed for each color on each of the three monochrome reference image data and monochrome inspection image data obtained in this way.
The conversion process RA52, the conversion process RB53, the difference extraction process RA64, and the determination process RA70 are processes for detecting the “recording portion interruption” state in the R color inspection image data. And the determination result RA are generated. Further, the conversion process RC58, the conversion process RD59, the difference extraction process RB67, and the determination process RB73 are processes for detecting the “extinction of the fine recording portion” state in the R color inspection image data. Nozzle information RB and determination result RB are generated.

  The conversion process GA54, the conversion process GB55, the difference extraction process GA65, and the determination process GA71 are processes for detecting a “recording part breakage” state in the G color inspection image data. And the determination result GA are generated. Further, the conversion process GC60, the conversion process GD61, the difference extraction process GB68, and the determination process GB74 are processes for detecting an “extinction of the fine recording portion” state in the G color inspection image data. Nozzle information GB and determination result GB are generated.

  The conversion process BA56, the conversion process BB57, the difference extraction process BA66, and the determination process BA72 are processes for detecting the “recording portion interruption” state in the B color inspection image data. And the determination result BA are generated. Further, the conversion process BC62, the conversion process BD63, the difference extraction process BB69, and the determination process BB75 are processes for detecting an “extinction of the fine recording portion” state in the B color inspection image data. Nozzle information BB and determination result BB are generated.

  The color determination process A76 is a process for specifying which color ink is detected to have a “recording unit break” defect. In this processing, a complementary color relationship between the three colors of CMY and the three colors of RGB is used. That is, the color determination process A76 determines that a non-ejection has occurred in the C color ink nozzles when, for example, a defect in the “recording portion interruption” state is detected in the R color inspection image data. Similarly, in the case where a defect is detected in the G color inspection image data, the color determination process A76 determines that a non-ejection has occurred in the M color ink nozzle, and the B color inspection image data is defective. Is detected, it is determined that non-ejection has occurred in the Y-color ink nozzle. The color determination process A76 determines that a non-ejection has occurred in the K ink nozzles when a defect is detected in the inspection image data of all RGB colors.

  The color determination process B77 is a process for specifying which color ink has been detected to be defective in the “extinction of fine recording portion” state. The contents of this process are the same as those of the color determination process A76. That is, when a defect is detected in the R color inspection image data, the color determination process B77 determines that a non-ejection has occurred in the C color ink nozzle, and the defect is detected in the G color inspection image data. If it has been detected, it is determined that non-ejection has occurred in the M color ink nozzle, and if a defect has been detected in the B color inspection image data, non-ejection has occurred in the Y color ink nozzle. Judge that you are doing. The color determination process B77 determines that a non-ejection has occurred in the K ink nozzles when a defect is detected in the inspection image data of all RGB colors.

  Thereafter, in this modification, the logical sum of the two determination results output from the color determination processing A76 and the color determination processing B77 is obtained by the logical sum processing 78, and the final recording failure determination result is sent to the host device 12. The output point is the same as the logical sum processing 48 in FIG.

  As described above, in this modification, the non-ejection detection process is modified as shown in FIG. 12, so that even if the reference image is a color image, image recording failure due to non-ejection of nozzles is further improved. It becomes possible to detect reliably.

  As mentioned above, although each embodiment of the present invention was described, the present invention is not limited to the embodiment mentioned above, and various improvement and change are possible within the range which does not deviate from the gist of the present invention. For example, some components may be deleted from the overall configuration shown in each embodiment of the present invention described above, and different components in each embodiment may be appropriately combined.

1 is a diagram illustrating a conceptual block configuration of an image recording apparatus according to the present invention. It is a figure which shows typically the example of arrangement | positioning of each component of the image recording device which concerns on this invention. FIG. 10 is a diagram illustrating a first example of a recording failure that appears on a recording medium that has been subjected to recording processing when non-ejection due to a nozzle failure occurs. FIG. 9 is a diagram illustrating a second example of a recording failure that appears on a recording medium that has been subjected to recording processing when non-ejection due to a nozzle failure occurs. FIG. 10 is a diagram illustrating a third example of a recording failure that appears on a recording medium that has been subjected to recording processing when non-ejection due to a nozzle failure occurs. It is the figure which expanded the non-ejection defect by nozzle failure, and the pixel of the both sides. It is a process block diagram which shows the outline | summary of a non-ejection detection process. It is explanatory drawing of the method of detecting the "recording part interruption" state. It is explanatory drawing of the method of detecting the "disappearance of a fine recording part" state. It is a flowchart which shows the processing content of the non-ejection detection process which concerns on 1st embodiment of this invention. It is a flowchart which shows the processing content of the non-ejection detection process in 2nd embodiment of this invention. It is a process block diagram which shows the outline | summary of the modification of a non-ejection detection process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image recording apparatus 2 Mode setting part 3 Sheet conveyance mechanism 4 Sheet feeding part 4a, 6a Sheet support member 5 Sheet support part 5a Sheet tension roller pair 5b Sheet support roller pair 6 Sheet collection | recovery part 6b Sheet conveyance drive part 6c Sheet conveyance information Generation unit 7 Recording unit 7-1, 7-2, 7-3, 7-4 Recording head 8 Control unit 9 Non-ejection detection unit
(9A image conversion unit, 9B difference image generation unit, 9C determination unit)
9 Non-ejection detector
(9α image defect determination unit, 9β non-ejection determination unit)
DESCRIPTION OF SYMBOLS 10 Memory | storage part 11 Test | inspection image acquisition part 11a Imaging part 11b Illumination part 12 Host apparatus 13 Recording medium (sheet)
DESCRIPTION OF SYMBOLS 20 Natural image 21 White stripe | line 22 Regular text image 23 Defective text image 24 Regular recording image part 25 Defective recording image part 26, 28, 30 Magnified image 27, 29, 31 Magnified image 40, 41, 42 of a bad state 43, 52, 53, 54, 55, 56, 57, 58, 59,
60, 61, 62, 63 Conversion processing 44, 45, 64, 65, 66, 67, 68, 69 Difference extraction processing 46, 47, 70, 71, 72, 73, 74, 75 Determination processing 48, 78 Logical sum processing 50, 51 RGB division processing 76, 77 Color determination processing

Claims (6)

An image recording apparatus that performs recording processing on a recording medium that is being transported along a transport path by causing ink to be ejected from each nozzle of a nozzle array that is formed of a plurality of nozzles based on reference image data notified from a host device In
An inspection image acquisition unit for acquiring inspection image data by imaging the recording medium after the recording process is performed;
A non-ejection detection unit that compares the reference image data with the inspection image data and detects a recording failure due to non-ejection of the nozzles,
The non-ejection detector is
Of the three pixels adjacent in the direction of the nozzle row in the pixels constituting each of the reference image data and the inspection image data, when the luminance of the central pixel is the highest, The difference between the luminance value and the higher luminance value of the pixels adjacent to the central pixel is set as the converted pixel value of the central pixel, and in other cases, the converted pixel value of the central pixel is set to zero. A first image conversion unit that generates first conversion reference image data and first conversion inspection image data by performing conversion processing on the reference image data and the inspection image data, respectively;
A first difference image generation unit that generates first difference image data by performing subtraction for each constituent pixel between the first conversion reference image data and the first conversion inspection image data;
A first determination unit that determines whether there is a defect in the inspection image data with respect to the reference image data based on the first difference image data, and sets the determination result as a detection result of a recording defect due to non-ejection of the nozzles; An image recording apparatus comprising: The non-ejection detection unit further includes
Of the three pixels adjacent in the direction of the nozzle row in the pixels constituting each of the reference image data and the inspection image data, if the luminance of the central pixel is the lowest, The difference between the luminance value and the lower luminance value of the pixels adjacent to the central pixel is the converted pixel value of the central pixel. In other cases, the converted pixel value of the central pixel is zero. A second image conversion unit that generates second conversion reference image data and second conversion inspection image data by performing conversion processing on the reference image data and the inspection image data, respectively ;
A second difference image generation unit that generates second difference image data by performing subtraction for each constituent pixel between the second conversion reference image data and the second conversion inspection image data;
A second determination unit that determines whether there is a defect in the inspection image data with respect to the reference image data based on the second difference image data;
The logical sum of the determination result of the defect of the inspection image data by the first determination unit and the determination result of the defect of the inspection image data by the second determination unit is set as the detection result of the recording defect due to non-ejection of the nozzles. the image recording apparatus according to claim 1, wherein comprising at least a non-ejection determining portion, it is characterized. The first difference image generation unit generates the first difference image data by performing a subtraction for each constituent pixel of the first conversion parity check image data from said first conversion reference image data,
The first determination unit, by comparing the result of integrating the converted difference pixel value of each pixel constituting the first difference image data in a direction perpendicular to the nozzle row and a predetermined threshold, the reference the relative image data determines the presence or absence of defects of the test image data, that the image recording apparatus according to claim 1 or 2, characterized in. An image recording apparatus that performs recording processing on a recording medium that is being transported along a transport path by causing ink to be ejected from each nozzle of a nozzle array that is formed of a plurality of nozzles based on reference image data notified from a host device A recording failure detection method by
Imaging the recording medium after the recording process is performed to obtain inspection image data,
Of the three pixels adjacent in the direction of the nozzle row in the pixels constituting each of the reference image data and the inspection image data, when the luminance of the central pixel is the highest, The difference between the luminance value and the higher luminance value of the pixels adjacent to the central pixel is set as the converted pixel value of the central pixel, and in other cases, the converted pixel value of the central pixel is set to zero. First conversion reference image data and first conversion inspection image data are generated by performing conversion processing on the reference image data and the inspection image data,
The first difference image data is generated by performing subtraction for each constituent pixel between the first conversion reference image data and the first conversion inspection image data,
Determining whether there is a defect in the inspection image data with respect to the reference image data based on the first difference image data;
It is determined whether or not the inspection image data is defective with respect to the reference image data based on the first difference image data, and the determination result is a detection result of a recording defect due to non-ejection of the nozzles. Recording failure detection method. The recording failure detection method further includes:
Of the three pixels adjacent in the direction of the nozzle row in the pixels constituting each of the reference image data and the inspection image data, if the luminance of the central pixel is the lowest, The difference between the luminance value and the lower luminance value of the pixels adjacent to the central pixel is the converted pixel value of the central pixel. In other cases, the converted pixel value of the central pixel is zero. Second conversion reference image data and second conversion inspection image data are generated by performing conversion processing on the reference image data and the inspection image data ,
The second difference image data is generated by performing subtraction for each constituent pixel between the second conversion reference image data and the second conversion inspection image data,
Determining the presence or absence of defects in the inspection image data relative to the reference image data based on the second difference image data;
Recording the logical sum of the defect determination result of the inspection image data based on the first difference image data and the defect determination result of the inspection image data based on the second difference image data by non-ejection of the nozzles The recording defect detection method according to claim 4 , wherein the determination result is a defect. In the generation of the first difference image, the first difference image data is generated by subtracting the first conversion inspection image data for each constituent pixel from the first conversion reference image data,
Whether the inspection image data is defective or not with respect to the reference image data based on the first difference image data is determined by converting the converted difference pixel value of each pixel constituting the first difference image data into the nozzle row. 6. The recording defect detection method according to claim 4, wherein the recording failure detection method is performed by comparing the result of integration in a direction perpendicular to a predetermined threshold value.