JP2014012362A - Ink-jet recording device and recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to reduce the number of recording media to be wasted during complementing processing for a discharge failure of a nozzle in an ink-jet recording device, and to enable simple complementing processing.SOLUTION: Detection patterns concerning respective ink colors are not individually recorded chip by chip but are recorded as one pattern. Accordingly, an area in a recording medium in which the detection patterns are recorded can be diminished, and waste of the recording medium due to pattern recording can be suppressed. In particular, when the present invention is applied to second detection processing of recording the pattern between areas, in each of which an actual image is recorded, among recording activities, an effect of waste suppression becomes more prominent. Control for recording of the pattern in a portion in which a nozzle overlaps or for detection of a discharge-failure nozzle and correction thereof can be further simplified.

Description

  The present invention relates to an ink jet recording apparatus and a recording method thereof, and more particularly, to non-ejection complementation in which ejection failure of a nozzle that ejects ink is detected and recording by the nozzle is performed by another nozzle that does not cause ejection failure. Is.

  As this type of technology, Patent Document 1 discloses a long recording head formed by arranging a plurality of chips each provided with a nozzle row so that a part of the nozzles overlaps a recording region. A technique for non-ejection supplement processing in the used recording apparatus is described. More specifically, when recording a pattern for detecting a discharge failure, basically, the patterns of each of the plurality of chips are recorded in separate areas of the recording medium, and the discharge failure nozzles are recorded for each individual pattern. By performing detection, non-discharge complementation is performed.

JP 2006-192599 A

  However, in the non-ejection supplement of Patent Document 1, since the patterns of each of the plurality of chips are recorded in individual areas of the recording medium, the amount of the recording medium such as paper for recording these patterns increases accordingly. As a result, there is a problem that the number of useless recording media not involved in recording increases. In particular, in a configuration in which recording is performed on continuous paper such as roll paper, this problem occurs when a detection pattern is recorded between images to be recorded on continuous paper and non-ejection interpolation is performed based on the reading result. Becomes prominent.

  On the other hand, control is performed so that the nozzle rows of a plurality of chips are a single nozzle row, that is, in the same way as in normal recording, one pattern corresponding to the nozzle rows of a plurality of chips is recorded. Can be considered. In this case, there arises a problem that the pattern recording, the ejection failure nozzle detection, and the control for complementation of the portion where the nozzles overlap are complicated.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an ink jet recording apparatus and a recording method capable of reducing a recording medium that is wasted in a nozzle discharge failure complement process and enabling a simple complement process.

  Therefore, in the present invention, ink jet recording is performed by using a recording head provided with a plurality of nozzle groups each provided with nozzles having overlapping recording areas on the recording medium and discharging ink from the nozzles of the recording head to the recording medium. An apparatus for recording a pattern for detecting ejection failure of a nozzle using a recording head, wherein the pattern to be recorded by each overlapping nozzle is recorded in one area of a recording medium A pattern recording unit that performs the recording, and a unit that identifies a defective nozzle based on the result of detecting whether or not a defective nozzle has occurred in the recorded pattern, the pattern recorded by the overlapping nozzles If it is detected that a discharge failure has occurred, the discharge failure is detected at each of the overlapping nozzles. The defect specifying means for specifying each overlapping nozzle as having occurred, and the recording data of the image to be recorded by the nozzle specified to have the discharge failure, the image by the nozzle having no discharge failure And a correction means for correcting the recording.

  According to the above configuration, it is possible to reduce a waste recording medium and perform a simple complementing process in the nozzle ejection defect complementing process.

FIG. 2 is a perspective view schematically illustrating a configuration around a recording unit of the ink jet recording apparatus according to the first embodiment of the present invention. It is a top view of the inkjet recording device of this embodiment shown in FIG. It is a figure explaining the structure of the recording head 2 of this embodiment demonstrated in FIG. 1, FIG. It is a figure which shows the detail of the nozzle arrangement | sequence and chip | tip arrangement | sequence especially of the recording head 2 shown in FIG. It is a block diagram which shows the structure of the data processing and control of the inkjet recording device of this embodiment. 3 is a flowchart illustrating a recording operation accompanied by a non-ejection complement process of the recording apparatus according to the first embodiment of the present invention. It is a flowchart which shows the detail of the 1st detection process shown in FIG. It is a figure which shows the pattern for a test | inspection used by a 1st detection process. FIG. 9 is a diagram schematically showing a read image when the inspection pattern shown in FIG. 8 is read at a predetermined resolution. It is a flowchart which shows the recording data generation process which concerns on this embodiment. It is a flowchart which shows the detail of the 2nd detection process shown in FIG. It is a figure which shows the pattern for a test | inspection used by a 2nd detection process. It is a figure which shows the result of having read the pattern shown in FIG. 12 with predetermined resolution. (A)-(c) is a figure explaining that the number of unit nozzles which can be identified is decided according to the resolution of a reading part. (A) And (b) is a figure explaining the specification of the defective nozzle when the ejection defect arises in the pattern for detection recorded in the second detection process according to the embodiment of the present invention and the overlapping nozzle area. It is a flowchart which shows the recording operation accompanied by a non-discharge complementation process of the recording apparatus of 2nd Embodiment of this invention. It is a flowchart which shows the detail of the 2nd detection process shown in FIG. It is a figure which shows the mask ratio with respect to the nozzle of an overlapping area | region based on 2nd Embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(First embodiment)
<Device configuration>
FIG. 1 is a perspective view showing an outline of the configuration around the recording unit of the ink jet recording apparatus 200 according to the first embodiment of the present invention, mainly a recording unit 4 and a reading unit arranged adjacent to the recording unit 4. 6 is shown.

  The recording unit 4 is configured in a substantially closed space by a housing frame 107, and the recording head 2 is attached to a holder 106. In addition to the position of the recording operation, the holder 106 faces the recording surface of the recording medium 3 such as a position for performing preliminary ejection, a position for wiping the nozzle surface of the recording head, and a position for capping to suppress drying of the nozzle surface. In this case, it can be moved by a driving mechanism. Further, the holder 106 can move in a relative position in a direction X substantially perpendicular to the conveyance direction of the recording medium 3, and this is caused by the difference between the recordable width of the recording head and the maximum width of the conveyance paper. The deviation in the number of discharges between the used nozzle and the unused nozzle can be averaged. The holder 106 can be driven by rotating the pulley 105 attached to the belt 104 by driving the pulse motor 103 while the belt 104 is fixed to the holder 106 by the attaching portion 108. The driving of the pulse motor 103 is controlled based on data including information on the size of the recording medium and the accumulated number of nozzle discharges of the recording head 2 from an external information terminal (not shown) during recording. Thus, the recording head 2 can be moved so that the number of ejections of the plurality of nozzles is averaged to determine the position of the recording head, and the recording head is fixed to the moving position by a fixing mechanism (not shown).

  The recording heads 2 are four recording heads that discharge cyan (C), magenta (M), yellow (Y), and black (Bk) inks, respectively. Each of these recording heads has an array of nozzle rows, which will be described later with reference to FIGS.

  FIG. 2 is a plan view of the ink jet recording apparatus of the present embodiment shown in FIG. As shown in FIG. 2, four recording heads 2 are mounted in the approximate center of the apparatus. As described above with reference to FIG. 1, the recording head 2 is attached to a holder (not shown in FIG. 2). The recording medium 3 is conveyed in the substantially central part of the apparatus. The recording head width (the length of the nozzle array range in the direction perpendicular to the conveyance direction of the recording medium 3) is 12 inches. If recording is possible with this recording head width, the recording medium 3 having a plurality of types of widths can be conveyed.

  When normal recording is performed with the ink jet recording apparatus described above with reference to FIGS. 1 and 2, a plurality of continuous recording media 3 fed from the roll paper supply unit are transported (not shown) arranged above and below the transport path. It is conveyed in the direction of the arrow shown in FIG. 1 by the rotation of the roller. During this conveyance, the recording unit performs recording by ejecting ink from the recording head 2 for each of the four color inks, and then the recording medium is cut to a predetermined length by a cutting unit (not shown), and then the outside of the apparatus. The paper is discharged to a predetermined paper discharge tray. As will be described later, the recording apparatus according to the present embodiment detects ejection failure for each nozzle of the recording head 2 and performs non-ejection supplementation in which recording by this nozzle is performed by other normal nozzles. At that time, a discharge failure detection pattern is recorded on the recording medium 3 and is read by the reading unit 6. In the present embodiment, the reading unit 6 includes a scanner. An image such as a pattern read by the reading unit 6 is analyzed by a CPU 201 that is a control unit of the recording apparatus 200 of the present embodiment, which will be described later with reference to FIG.

  FIG. 3 is a diagram illustrating the configuration of the recording head 2 according to the present embodiment described with reference to FIGS. 1 and 2. A plurality of chips 21 are arranged in the recording head 2, and each chip 21 is provided with four nozzle rows as a nozzle group. The arrangement of the chips 21 is arranged such that each nozzle group overlaps the recording area with the nozzle group of the chip whose end area is adjacent. The recording medium is conveyed in the direction indicated by the arrow in the drawing with respect to the recording head 2 having this chip arrangement. The recording head 2 having the above configuration is used for each of the four color inks as described above. In FIG. 3, only eight chips are shown for simplification of illustration, but more chips are actually arranged.

  FIG. 4 is a diagram showing details of the nozzle arrangement and the chip arrangement of the recording head 2 shown in FIG. 3, and shows only two adjacent chips. In each chip 21, the four nozzle rows NA1, NA2, NA3, NA4 are 24 nozzles n1, n2,... Along the direction intersecting the recording medium conveyance direction indicated by the arrows at intervals equivalent to 600 dpi. .., N17,..., N-24 are arranged. In FIG. 4, for the sake of simplification, 24 nozzles are shown, and eight nozzles in the overlapping range described below are used. However, in actuality, a larger number of nozzles are arranged. Yes.

  Eight nozzles n17,..., N24 and nozzles n1,..., N8 in the nozzle rows of two adjacent chips 21 are nozzles in the overlapping range between chips (between nozzle groups).

  As described above, the recording apparatus according to the present embodiment described with reference to FIGS. 1 to 4 has been described by taking an example of using four colors of inks of C, M, Y, and K. However, application of the present invention is applicable to these inks. Of course, it is not limited to the form using. For example, a form using more ink such as light cyan, light magenta, light gray, red, and green may be used.

  FIG. 5 is a block diagram mainly showing a data processing and control configuration of the ink jet recording apparatus of the present embodiment described above. The ink jet recording apparatus 200 of the present embodiment performs recording based on image data and recording control signals sent from a host device 211 such as a PC. The recording apparatus 200 includes a CPU 201, a ROM 202, a RAM 203, and a hard disk drive 204 as a storage area.

  The image processing unit 207 performs predetermined image processing on the image data from the host device 211. The operation unit 206 includes a mouse, a keyboard, and the like, and performs various inputs from the user. The engine control unit 208 controls the recording operation by the recording mechanism described with reference to FIGS. The scanner control unit 209 controls image reading of the scanner that constitutes the reading unit 6. Further, the external interface 205 exchanges data and signals with the host device 211 and the like. Processing of these units is controlled by the CPU 201. That is, the CPU 201 performs the above-described control by loading a program stored in the ROM 202 or the hard disk into the RAM 203 as a work memory and executing the program. Note that information indicating the state of the recording head is stored in a storage device such as the memory of the ROM 202 and RAM 203 and a hard disk. This information may be any information as long as it indicates the nozzle state.

  FIG. 6 is a flowchart showing a recording process accompanied by a non-ejection complement process in the recording apparatus of the present embodiment having the above-described configuration.

  First, before describing the entire recording process, a process for detecting defective nozzles for non-discharge complementation will be described. In the present embodiment, the first detection process is executed as maintenance of the recording apparatus before performing actual image recording, which is normal recording. This detection process specifies a defective nozzle (defect identification) in units of nozzles. Thereby, non-discharge complementation can be performed with high accuracy as maintenance before recording. Specifically, the test pattern is recorded, and the ejection failure nozzle is specified from the read result. Thereafter, actual image recording is started, and at this time, correction processing of recording data is performed based on the information on the specified defective nozzle so as not to cause an image defect due to the defective ejection nozzle.

  In the present embodiment, the second detection process is executed when a predetermined number of actual image recordings have been performed. In the present embodiment, an inspection pattern is recorded between images during actual image recording, and a defective ejection nozzle is specified from the read result. At that time, in order to reduce the load of defect detection and correction processing, the nozzle group including the defective nozzle is specified for each nozzle group including a plurality of nozzles. Then, in subsequent real image recording, recording data correction processing corresponding to the specified defective nozzle group is performed.

  In the present embodiment, the present invention is applied to the second detection process. That is, with respect to the recording of the inspection pattern, the portion of the inspection pattern recorded by the overlapping nozzles between adjacent chips (between nozzle groups) is recorded by one nozzle group as in the case of normal actual image recording. Record as you did. Further, in specifying the ejection failure nozzle based on the reading result of the test pattern, the subsequent correction processing is performed assuming that ejection failure has occurred in the specific nozzles of both nozzle groups.

  The recording process including the above first and second detection processes will be described with reference to FIG.

  First, in step S301, a first detection process before recording an actual image is performed. The first detection process is a process for detecting whether or not the nozzle is a discharge failure nozzle in units of nozzles.

<First detection process>
FIG. 7 is a flowchart for explaining the first detection process in detail.

  First, in step S601, an inspection pattern (inspection image) and nozzle state information are read from the ROM 202. In step S602, recording data of an inspection pattern is generated based on the inspection image and nozzle state information read in step S601. In step S603, an inspection pattern is recorded based on the recording data generated in step S602.

  FIG. 8 is a diagram illustrating an inspection pattern used in the first detection process. This pattern is recorded in an individual area of the recording medium for each of the plurality of chips 21 of the recording head described above with reference to FIG.

  In FIG. 8, when the horizontal direction is the X axis and the vertical direction is the Y axis, the test pattern is recorded so that four dots are arranged in the X direction for each nozzle in the nozzle rows AN1, AN2, AN3, and AN4. Further, recording is performed by shifting in the X direction so that the recording areas do not overlap each nozzle row. In the figure, reference numeral 602 denotes a detection mark for associating the pattern position with the nozzle portion. By using this mark, it is possible to identify the pattern and the nozzle that performed the recording. In the example illustrated in FIG. 8, the region 601 is a region in which ink is not ejected from the corresponding ejection failure nozzle of the nozzle row NA4 in the recording head of a certain ink color and is recorded as a white stripe.

  FIG. 8 shows an example in which 12 dots are recorded in the Y direction. However, the number of nozzles in the Y direction of each chip shown in FIG. The number is also 24. For simplicity of illustration, twelve are shown.

  In step S604, conditions for reading the recorded pattern by the reading unit 6 are set. In the present embodiment, the reading resolution of the reading unit 6 is selected and set from a plurality of conditions (modes) different from each other. In this step S604, in order to detect and specify a defective nozzle in units of nozzles, a reading resolution equivalent to the nozzle resolution is set. In this embodiment, the nozzle resolution of the nozzle array of the recording head 2 is 600 dpi, and the reading resolution in step S604 is 600 dpi, which is equal to the nozzle resolution. Here, since the purpose is to identify defective nozzles in units of nozzles, the resolution is not limited to this as long as defective nozzles can be identified.

  Next, in step S605, the inspection pattern recorded in step S603 is read based on the reading conditions determined in step S604.

  FIG. 9 is a diagram schematically showing a read image when the inspection pattern shown in FIG. 8 is read at a predetermined resolution. In FIG. 9, reference numeral 701 denotes an image in which a streak portion due to a defective nozzle is read, and reference numeral 702 denotes an image in which a detection mark is read. When reading with a scanner, the same signal value is output in units of one pixel at a predetermined resolution.

  Referring to FIG. 7 again, in the next step S606, the inspection pattern read in step S605 is analyzed to detect a defective nozzle. In this step, since the nozzle resolution and the reading resolution are the same, it is possible to detect defective nozzle information by simply detecting a white missing area or a color uneven area. In the example shown in FIG. 9, an analysis result is obtained that the fourth nozzle n4 in the nozzle array NA4 is a defective nozzle among the four nozzle arrays.

  In order to further improve the analysis accuracy, a process of averaging the read images in the X direction for each nozzle row and performing histogram analysis in the Y direction may be performed. Any analysis method may be used as long as a defective nozzle can be identified in units of nozzles.

  Next, in step S607, information on the defective nozzle analyzed in step S606 is updated. In this embodiment, the information on the defective nozzles is stored in the ROM 202. However, the information on the defective nozzles may be stored in a storage device included in the inkjet printer 200. Absent.

  As described above, the processing in steps S601 to S607 is the first detection processing in step S301 in FIG. As described above, the purpose of this process is to identify defective nozzles in units of nozzles, so that the processing load is high and may take time. For this reason, it is preferable to perform it at the time of the maintenance operation with a relatively long time. Note that the timing of performing the first detection process may be performed before actual image recording or may be performed in an initial state when the apparatus is started up. Moreover, an operator or a user may perform it at arbitrary timings. Since the processing load is high, it is preferable that the recording is not performed by the apparatus, that is, in a state where there is no recording instruction.

  Referring again to FIG. 6, in the next step S302, image data for actual image recording is input. The image data is input from the host device 211 via the interface 205 and stored on the hard disk by the HDD 204. In the present embodiment, the resolution of the input image is 300 dpi.

  In step S303, recording data is generated based on the input image data. The input image data generally has a data format such as sRGB. For this reason, recording data corresponding to each device is generated.

<Recording data generation processing>
FIG. 10 is a flowchart showing recording data generation processing according to the present embodiment.

  First, in step S801, color processing A is performed to convert an RGB original image signal obtained by an image input device such as a digital camera or a scanner or computer processing into an R'G'B 'signal. The color processing A is processing for converting the original image signal RGB into an image signal R′G′B ′ adapted to the color reproduction range of the recording apparatus. In step S802, color processing B is performed to convert the R'G'B 'signal into a signal corresponding to each color ink. In this embodiment, since an image is recorded with four colors of ink, the converted signals are density signals C1, M1, Y1, and K1 corresponding to cyan, magenta, yellow, and black. In the present embodiment, the color processing B uses a three-dimensional lookup table with inputs (R, G, B) and outputs (C, M, Y, K). At this time, for input values that deviate from the grid points, the output values are obtained by interpolation from the output values of the surrounding grid points.

  In step S803, gamma correction using a correction table is performed to convert density signals C1, M1, Y1, and K1 into C2, M2, Y2, and K2. In step S804, the density signals C2, M2, Y2, and K2 after gamma correction are quantized (binarized), and recording signals C3, M3, Y3, and K3 to be transferred to the recording head 2 are generated. As this quantization method, an error diffusion method or a dither method is used.

  Referring to FIG. 6 again, in the next step S304, the print data distribution process to each nozzle row is performed based on the print data generated in step S303 and the information on the ejection failure nozzles stored in the ROM 202. Note that the information on defective nozzles stored in the ROM 202 stores not only the above-described first detection process but also information on defective nozzles specified in the second detection process described later. That is, as will be described later, in the second detection process, if a discharge failure occurs in the nozzle of one chip among the nozzles in which the recording areas between adjacent chips overlap, the corresponding nozzle of both chips It is also assumed that there is a defect in the corresponding nozzle area. The nozzles of both chips are stored in the ROM 202 as defective nozzle information.

  In this embodiment, since there are four nozzle rows of the same color, it is possible to perform ejection with four nozzles on the same pixel on the recording medium. However, when there are defective nozzles among the four nozzles, ejection is performed with the remaining three nozzles excluding the defective nozzles. Therefore, data to be distributed to each nozzle is determined based on the recording data and defective nozzle information. In the present embodiment, the sorting is performed in order so that the three nozzles are equally used.

  Note that the recording data correction processing method for complementing defective nozzles is not limited to this. For example, in the case of using a recording head in which each nozzle row has one color, a method of complementing by using nozzles around the defective nozzle, for example, one adjacent nozzle or two adjacent nozzles on both sides may be used. In addition, when recording is performed using so-called multi-pass recording, in which recording is completed by a plurality of relative scans of the recording head with respect to a predetermined area of the recording medium, pixels that should be recorded by defective nozzles in other scans A method may be used in which the recording is complemented so that the nozzles are not defective in scanning. That is, the correction method is limited to the method described here as long as the correction method corrects the pixels to be recorded with the specified defective nozzle (or defective nozzle group) so as to record with the other non-defective nozzle (or nozzle group). It is not something.

  Next, in step S305, ink is ejected from the recording head based on the recording data distributed to each nozzle row in step S304.

  In step S306, it is determined whether the number of recorded sheets (number of pages) has reached a predetermined number. If the number is less than the predetermined number, the process returns to step S302 again, and the subsequent processes are repeated. If the predetermined number has been reached, the process proceeds to step S307. In the present embodiment, the number of hits is 30. The number of recorded sheets is not limited to this, and the number of recorded sheets may be arbitrarily set by an operator. In addition, since there are various paper sizes for recorded materials and some devices can record multiple paper sizes, not only the number of recordings but also the time from the start of recording and the number of dots counted by counting the number of ejected dots. May be determined.

  In step S307, a second detection process is performed. In the second detection process, defective nozzle detection is specified in units of a plurality of nozzles.

<Second detection process>
FIG. 11 is a flowchart illustrating in detail the second detection process shown in FIG.

  In step S1001, an inspection pattern image is input. In step S1002, inspection pattern recording data is generated based on the input inspection image data. In step S1003, an inspection pattern is recorded based on the recording data generated in step S1002.

  FIG. 12 is a diagram illustrating an inspection pattern used in the first detection process. This pattern is different from the pattern recorded in the first detection process, in which one pattern is recorded for one recording head 2 (see FIG. 15A). That is, a pattern for each chip is not recorded in an individual area of the recording medium 3, but recording by a nozzle range in which recording areas between a plurality of chips overlap is recorded by one nozzle row as in normal recording. It will be the same as that of the pattern. Accordingly, in the pattern shown in FIG. 12, the number of dots in the Y direction is the number in which the nozzles of eight chips are arranged in the Y direction including the overlapping range in the arrangement of the chips 21 shown in FIG. For simplification of illustration, twelve are shown. Further, in the generation of print data corresponding to the overlapping range of nozzles of the detection pattern used for the second detection, a mask is used as in normal printing, and corresponding nozzle rows of the two overlapping nozzle groups ( The recording data is distributed to the nozzles NA1, NA2, NA3, NA4). As this mask, for example, the same mask used for normal recording can be used, for example, the nozzles of two nozzle rows are equally used.

  In the example shown in FIG. 12, the white streaks in the area 1101 are a result of the ejection failure of the corresponding nozzles in the nozzle array NA2 of the recording head of a certain ink color while recording 30 sheets. It is. In the second detection process, since the inspection pattern is recorded in a state after the data is distributed to the nozzles that are not defective and corrected based on the information on the defective nozzles in the first detection process, the first detection process is performed. White streaks are not generated by the nozzles detected in the processing.

  Referring to FIG. 11 again, in the next step S1004, one of a plurality of reading conditions (reading modes) is selected and set. In the present embodiment, the reading resolution is 300 dpi. This is a resolution lower than the resolution (600 dpi) of the nozzle arrangement.

  In step S1005, the inspection pattern is read based on the reading conditions set in step S1004. FIG. 13 is a diagram showing a result of reading the pattern shown in FIG. 12 with a predetermined resolution. As shown in FIG. 13, the reading result indicates that the density of the area 1101 is lower than that of the other areas, and there is a defective nozzle among the plurality of nozzles that record this area.

  FIGS. 14A to 14C are diagrams illustrating that the number of unit nozzles that can be identified is determined according to the resolution of the reading unit. The dots formed by ink ejection on the recording medium and the reading of the scanner The relationship with the pixel is shown. FIG. 14A shows a state in which dots are formed in the upper left, upper right, and lower left areas in a 2 × 2 area obtained by dividing pixels of 300 dpi resolution on the recording medium. That is, since the resolution of the nozzle array is 600 dpi, one nozzle corresponds to the 600 dpi area and the ink is landed. That is, four ink dots can be arranged in a 300 dpi square area.

  FIG. 14B shows the result of reading the dot pattern shown in FIG. 14A with a reading resolution of 600 dpi. When the reading resolution is 600 dpi, one of the 600 dpi areas is read as one pixel. In this case, 4 pixels are included in the read image for 300 dpi pixels. In the case of FIG. 14B, the density of the upper left, upper right, and lower left pixels is 1 and the density of the lower right pixels is 0. On the other hand, FIG. 14C shows the result of reading the dot pattern shown in FIG. 14A with a reading resolution of 300 dpi. When the reading resolution is 300 dpi, a 300 dpi pixel is read as one pixel. That is, when the reading resolution is lower than the nozzle resolution, reading data of one pixel is obtained for a plurality of dots. That is, the density of 3 dots included in the four areas is averaged, and the read data is obtained with the density of 0.75. As a result, as shown in FIG. 13, in the reading result of the area recorded by the nozzle group including the defective nozzle, a density lower than the area of the other nozzle group is detected. As described above, when the reading resolution is lower than the nozzle resolution, it is possible to determine whether or not a defective nozzle is included in units of a plurality of nozzles, but it is not possible to specify which nozzle is a defective nozzle.

  The present embodiment relates to a form in which the dot recording resolution and the nozzle arrangement resolution in the recording medium conveyance direction are the same. However, it is needless to say that the relationship between the nozzle array resolution and the reading resolution is important and does not depend on the dot recording resolution in the transport direction.

  Referring to FIG. 11 again, in the next step S1006, a defective nozzle is specified based on the inspection pattern image read in step S1005. At this time, since the reading resolution is lower than the nozzle arrangement resolution in this embodiment, it is difficult to identify a defective nozzle in nozzle units as described above. For this reason, the region including a plurality of nozzles is specified as one unit (nozzle group).

  Next, in step S1007, it is determined which region in the chip the nozzle group of the defective nozzle is. In the embodiment of the present invention, as described above, the nozzles in which the recording areas overlap between adjacent chips perform mask processing to record the detection pattern using one of the nozzles. Do. For this reason, when an ejection failure nozzle is detected in this overlapping range of nozzles, it is difficult to specify which chip has the defective nozzle between the two chips.

  Therefore, in this embodiment, when it is determined in step S1007 that the ejection failure nozzle is in the overlapping region, in step S1008, the nozzle group corresponding to each of the two chips of the nozzle group specified in step S1006 is determined. . That is, it is not specified which of the two chips has a defective nozzle, and the corresponding nozzle group is determined for each of the two chips of the specified nozzle group.

  FIGS. 15A and 15B are diagrams for explaining identification of defective nozzles when ejection defects occur in the areas of overlapping nozzles and detection patterns recorded in the second detection process according to the embodiment of the present invention. is there.

  In FIG. 15A, as described above, the nozzle row including the overlapping nozzle range between the adjacent chips (21-0 to 21-3) in the Bk, Y, M, and C ink recording heads. Thus, a linear pattern is recorded. In the example shown in the figure, the cyan (C) pattern has white streaks, and as a result, the nozzles in an area having an overlapping range between the chip 21-3 and the chip 21-2 of the ink color C recording head. It is specified that there is a discharge failure in (nozzle group). Specifically, it is detected that there is a defective nozzle (nozzle group) in the nozzle array NA1 in the overlapping range between the chip 21-3 and the chip 21-2. In this case, it is assumed that the corresponding nozzles (nozzle groups) of both the chips 21-3 and 21-2 are defective in ejection.

  As described above with reference to FIGS. 15A and 15B, according to the present embodiment, one pattern is not recorded for each chip for each ink color, and one pattern is not recorded. Record as. Thereby, the area on the recording medium on which the detection pattern is recorded can be reduced, and waste of the recording medium for pattern recording can be suppressed. In particular, by applying the present invention to the second detection process for recording a pattern between areas where an actual image is recorded during the recording operation, the effect of suppressing waste becomes more prominent.

  Further, according to the present embodiment, it is possible to simplify the pattern recording, the ejection failure nozzle detection, and the control for the correction of the portion where the nozzles overlap.

  In the present embodiment, the threshold value is set in two stages so that one nozzle is defective in ejection in a pixel whose density is halved, and the white area is determined in two nozzles as ejection failure. Further, when it is specified that the defective nozzle is surely included, the specified pixel can be further enlarged. In the present embodiment, in step S1009 in FIG. 11, the six nozzles of the nozzle array NA1 of the chip 21-3 and the six nozzles of the nozzle array NA1 of the chip 21-2 are determined to be nozzle groups that are defective in ejection. The degree of enlargement and designation may be arbitrarily designated. If not, the process proceeds to step S1010.

  In step S1010, information on a plurality of nozzles determined to be defective nozzles in steps S1006 to S1009 is updated. The defective nozzle information may be stored in the same area as the nozzle determined to be a defective nozzle in the first detection process, or may be stored in another area.

  The above-described second detection process is a case where a defective nozzle is detected during printing and a correction process is performed, and a reduction in the load on these processes is required. In the present embodiment, the defective nozzles are specified for each of the two chips, assuming that the defective nozzles are generated in both of the two chips without specifying the chip on which the test pattern is recorded. This makes it possible to detect defective nozzles during printing while reducing the processing load. When the recording continues over a plurality of sheets, the correction process is performed at the timing when the information is updated in the second detection process, so that a prompt feedback to the correction process is possible.

  That is, according to the present embodiment, for each ink color, the detection pattern is recorded as one pattern without being recorded individually for each chip. Thereby, the area on the recording medium on which the detection pattern is recorded can be reduced, and waste of the recording medium for pattern recording can be suppressed. In addition, according to the present embodiment, the defective nozzles are identified in the portion where the nozzles overlap according to the usage ratio of the nozzles, so that the control for complementation can be simplified.

  Referring to FIG. 6 again, finally, in step S308, it is determined whether or not the recording of the actual image is completed. If the recording has not ended, the process returns to the process of step S302, the actual image is input again, and the correction process and recording are performed. The correction information at this time is recorded using the nozzle information obtained in the second detection process. As a result, low-load defect detection and correction processing corresponding to a defective nozzle newly generated during recording can be performed.

  In this embodiment, the determination information processing result of the first detection process and the second detection process is stored in the same storage area. However, in practice, a certain amount of time is required when updating the information in the storage area. Therefore, it becomes necessary to accurately control the information update timing. It is also possible to add a configuration that holds multiple storage areas, prepares a second storage area separately from the currently referenced storage area, and changes the reference destination as soon as information is written to the second storage area is there. As a result, it is possible to further simplify the processing.

  In the present embodiment, the reading resolution of the second detection process is set to half the nozzle resolution, and it is determined that the nozzle is a defective nozzle in units of two nozzles. As the reading resolution of the second detection process is lowered, the amount of information processing can be reduced by a power, but the detection accuracy may be lowered. Therefore, the reading resolution of the second detection process may be arbitrarily set depending on the information processing capability of the apparatus. In that case, it is possible to realize a form in which the amount of information processing is further reduced by adding a mechanism for changing the number of nozzles that collectively perform defect detection / correction using the ratio between the reading resolution and the nozzle resolution. .

  In this embodiment, an example of a print head having a plurality of nozzle rows of the same color has been shown. However, as described above, an example of a print head having one nozzle row for each color may be used, and a correction method may be used. The correction may be performed using adjacent nozzles, or in the case of multi-pass printing, the correction may be performed using another scan.

  Even when it is determined as defective in the second detection process, the actual image may be recorded in a state where there is a defective nozzle depending on the distance between the recording head and the reading device and the frequency of insertion of the inspection pattern. is there. For this reason, when it is determined to be defective in the second detection process, a configuration in which the convenience is further improved can be realized by adding a configuration for recording the actual image recorded before recording the test pattern. is there.

(Second Embodiment)
In the second embodiment of the present invention, in the area where the recording area of the nozzles overlaps between the chips, the defective nozzle is selected according to the mask ratio between the two chips in the mask process when recording the detection pattern. It is related with the form which identifies.

  FIG. 16 is a flowchart illustrating a recording operation involving a non-ejection complement process of the recording apparatus according to the second embodiment of the present invention. In FIG. 16, steps S1401 to S1406 are the same as the processing of the first embodiment shown in FIG. 6, and detailed description thereof is omitted.

  In step S1407, a second detection process is performed. In the second detection process of the present embodiment, when the detection pattern is recorded, the mask process is performed on the print data corresponding to the nozzles in the area where the print areas of the nozzles overlap between the chips as in the first embodiment. I do. In determining the defective nozzle, the defective nozzle is specified according to the mask ratio between the two chips.

  FIG. 17 is a flowchart showing details of the second detection process shown in FIG. The processing of steps S1501 to S1505 is the same as the processing of the first embodiment shown in FIG. 11, and detailed description thereof is omitted.

  In step S1506, a defective nozzle is specified based on the inspection pattern image read in step S1505. At this time, as in the first embodiment, the specifying process is performed using a region including a plurality of nozzles as one unit (nozzle group). In step S1507, it is determined which area in the chip is the defective nozzle detection area. Next, in step S1508, when generating the recording data of the nozzles in the area where the nozzles of two adjacent chips overlap, the defective nozzle (nozzle group) is specified according to the mask ratio between the two chips. Do.

  FIG. 18 is a diagram illustrating the mask ratio with respect to the nozzles in the overlapping region of the present embodiment. Here, the mask ratio can be defined as a nozzle use ratio when a predetermined amount of image is recorded. In the example shown in FIG. 18, the 9th to 16th nozzles of one chip among the 1st to 24th nozzles are nozzles in which the recording areas do not overlap, and therefore the mask ratio is 100%. On the other hand, nozzles 1 to 8 and 17 to 24 are nozzles in a range where the recording areas overlap, and the mask ratio between the nozzles where the recording areas overlap is 17 in one chip as shown in the figure. The first nozzle is 100%, the 24th nozzle is 0%, and there is a linear relationship between them. On the other chip, the first nozzle is 0%, the eighth nozzle is 100%, and the relationship is linear between them. It will change to. In the present embodiment, since the reading resolution is half of the nozzle resolution, defective nozzles are identified in units of two nozzles, so only odd-numbered nozzle numbers are shown.

  In FIG. 18, for example, when the 19th nozzle of the chip 1 is a defective nozzle for the nozzle row NA2, the masks of the 19th and 20th nozzle groups of the chip 1 and the 3rd and 4th nozzle groups of the chip 2 are masked. Compare ratios. Then, the 19th and 20th nozzle groups of the chip 1 with the higher mask ratio are specified as defective nozzles. This is because the higher the mask ratio, the greater the influence on defective image generation when defective nozzles occur.

  In step S1510, as in the first embodiment, information on a plurality of nozzles determined to be defective nozzles is updated. In the above example, in the second detection process, the 19th and 20th nozzle groups of the nozzle array NA2 of the chip 1 are determined as defective nozzles.

  As described above, according to the second embodiment of the present invention, in the nozzle range where the recording area overlaps, the chip where the defective nozzle test pattern is recorded is not specified, and two chips overlap. In the recording area, the defective nozzle is specified according to the mask ratio for two chips. This makes it possible to perform defect detection / correction processing in a short time in a situation where low-load correction processing is required during recording, and shorten the length of the detection pattern required for strict nozzle identification. It becomes possible to suppress.

2 Recording Head 3 Recording Medium 6 Reading Section 21 Chip 200 Inkjet Recording Device 201 CPU
209 Scanner control unit

Claims (4)

An inkjet recording apparatus that performs recording by ejecting ink from a nozzle of a recording head to a recording medium using a recording head provided with a plurality of nozzle groups each provided with a nozzle having overlapping recording areas for the recording medium,
Pattern recording means for recording a pattern for detecting ejection failure of a nozzle using a recording head, wherein the pattern to be recorded by each of the overlapping nozzles is recorded in one area of a recording medium; ,
Based on the result of detecting whether or not there is a nozzle ejection failure in the recorded pattern, the means for identifying the ejection failure nozzle, the ejection failure occurred in the pattern recorded by the overlapping nozzles When it is detected that there is a discharge failure in each of the overlapping nozzles, a failure specifying means for specifying each of the overlapping nozzles,
Correction means for correcting recording data of an image to be recorded by a nozzle identified as having a discharge failure, so as to record the image by a nozzle having no discharge failure;
An ink jet recording apparatus comprising: An inkjet recording apparatus that performs recording by ejecting ink from a nozzle of a recording head to a recording medium using a recording head provided with a plurality of nozzle groups each provided with a nozzle having overlapping recording areas for the recording medium,
Pattern recording means for recording a pattern for detecting ejection failure of a nozzle using a recording head, wherein the pattern to be recorded by each of the overlapping nozzles is recorded in one area of a recording medium; ,
Based on the result of detecting whether or not there is a nozzle ejection failure in the recorded pattern, the means for identifying the ejection failure nozzle, the ejection failure occurred in the pattern recorded by the overlapping nozzles If it is detected that there is a discharge failure in one of the overlapping nozzles according to the usage ratio of the nozzle when a predetermined amount of image is recorded by the overlapping nozzle, the overlap is detected. A failure identification means for identifying one of the nozzles to perform,
Correction means for correcting recording data of an image to be recorded by a nozzle identified as having a discharge failure, so as to record the image by a nozzle having no discharge failure;
An ink jet recording apparatus comprising: A recording method for performing recording by ejecting ink from a nozzle of a recording head to a recording medium using a recording head provided with a plurality of nozzle groups each provided with a nozzle having overlapping recording areas for the recording medium,
A pattern recording step of recording a pattern for detecting ejection failure of a nozzle using a recording head, wherein the pattern to be recorded by each of the overlapping nozzles is recorded in one area of a recording medium; ,
Based on the result of detecting whether or not there is a nozzle discharge failure in the recorded pattern, the step of identifying a nozzle with a discharge failure is detected, and a discharge failure occurs in the pattern recorded by the overlapping nozzles. When it is detected that there is a discharge failure in each of the overlapping nozzles, a failure specifying step of specifying each of the overlapping nozzles,
A correction process for correcting the recording data of an image to be recorded by a nozzle identified as having a discharge failure so as to record the image by a nozzle having no discharge failure;
A recording method characterized by comprising: A recording method for performing recording by ejecting ink from a nozzle of a recording head to a recording medium using a recording head provided with a plurality of nozzle groups each provided with a nozzle having overlapping recording areas for the recording medium,
A pattern recording step of recording a pattern for detecting ejection failure of a nozzle using a recording head, wherein the pattern to be recorded by each of the overlapping nozzles is recorded in one area of a recording medium; ,
Based on the result of detecting whether or not there is a nozzle discharge failure in the recorded pattern, the step of identifying a nozzle with a discharge failure is detected, and a discharge failure occurs in the pattern recorded by the overlapping nozzles. If it is detected that there is a discharge failure in one of the overlapping nozzles according to the usage ratio of the nozzle when a predetermined amount of image is recorded by the overlapping nozzle, the overlap is detected. A defect identification step for identifying one of the nozzles to perform;
A correction process for correcting the recording data of an image to be recorded by a nozzle identified as having a discharge failure so as to record the image by a nozzle having no discharge failure;
A recording method characterized by comprising:

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