JP2019093678A - Inkjet recording device and inkjet recording method - Google Patents

Abstract

To acquire information on a plurality of image defects from an identical image data and control recording operation so as to relax each of the image defects.SOLUTION: An inkjet recording device generates attribute data including information on a first factor and information on a second factor for each pixel based on a pixel signal included in each pixel of image data, and determines a mode of relative scanning for recording a corresponding pixel based on the information on the first factor and the information on the second factor.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an ink jet recording apparatus and an ink jet recording method in which an image is recorded by discharging ink onto a recording medium while scanning a recording head.

  Patent Document 1 discloses a configuration in which image data is analyzed in pixel units, and a printing operation is performed using a special dot arrangement pattern in a region where color unevenness caused by the application order of color ink is concerned. . By adopting the method of Patent Document 1, even in the area where color unevenness is a concern, it is possible to arrange the application order of the color ink so as to make the color unevenness inconspicuous.

JP 2012-223970 A

  In the ink jet recording apparatus, in addition to color unevenness, various image defects such as time difference unevenness have been problems.

  However, in Patent Document 1, only information on color unevenness is acquired from image data, and only measures for color unevenness are taken. That is, it has not been possible to take measures against other image defects that can be analyzed from image data.

  The present invention has been made to solve the above problems. Therefore, the purpose is to obtain information on a plurality of image defects from the same image data and to control the recording operation so that the respective image defects can be alleviated.

  Therefore, the present invention is an ink jet recording apparatus for recording an image on the recording medium by relatively scanning the recording medium with a recording head in which ejection openings for ejecting ink according to the image data are arrayed. Generation means for generating, for each pixel, attribute data including information on a first element and information on a second element based on pixel signals of individual pixels, information on the first element, and information on the second element And recording operation determination means for determining the form of the relative scan for recording the corresponding pixel.

  According to the present invention, it is possible to obtain information on a plurality of image defects from the same image data and control the recording operation so as to alleviate each image defect.

FIG. 2 is a diagram illustrating the configuration of a recording unit of a color inkjet recording apparatus. FIG. 3 is a block diagram showing a control configuration of the inkjet recording apparatus. It is a figure which shows the outline | summary of 2-pass bidirectional | two-way recording. It is a figure which shows the relationship between the time difference of 1st and 2nd recording scanning, and color development. 7 is a flowchart for explaining recording operation determination processing. It is a figure which shows the preservation | save state of image data and attribute data. It is a figure which shows the content of an attribute data table, and the structure of attribute data. It is a figure which shows the table which a recording control part refers. FIG. 7 is a diagram showing a recording operation for each unit area. It is a figure which shows another example of the preservation | save state of image data and attribute data. FIG. 14 is a diagram illustrating another example of the recording operation for each unit area. It is a figure which shows the content of an attribute data table, and the structure of attribute data.

First Embodiment
FIGS. 1A and 1B are diagrams showing the configuration of the recording unit of the color ink jet recording apparatus 1 to which the present invention can be applied. FIG. 1A is a perspective view of the recording unit, and FIG. 1B shows an arrangement configuration of the discharge ports 202 in the recording head 201.

  As shown in FIG. 1A, the recording medium S is nipped by two roller pairs of a sheet feeding roller pair 104, a roller pair formed of a conveying roller 102 and an auxiliary roller 103, and the smoothness is maintained. It is done. The feed roller pair 104 and the conveyance roller 102 rotate while supporting the recording medium S, and convey the recording medium S in the Y direction.

  A carriage 105 capable of reciprocating in the X direction is disposed between the two roller pairs, and the ink tanks 106 to 109 and the recording head 201 are detachably mounted on the carriage 105. The ink tanks 106 to 109 contain four colors of ink (black K, cyan C, magenta M, and yellow Y), respectively, and are mounted on the carriage 105 and connected to the recording head 201, and are connected to the recording head 201. These inks are supplied.

  As shown in FIG. 1B, the print head 201 is provided with four rows of ejection openings corresponding to each of the four colors of ink. Each ejection port 202 ejects ink in the -Z direction in the drawing according to ejection data. In the present embodiment, 1280 ejection openings are arranged in one row in the Y direction at 1200 dpi pitch for each color.

  Based on the above configuration, while the carriage 105 relatively scans in the forward direction or backward direction at a predetermined speed, the recording head 201 ejects the ink according to the ejection data to record an image of one band on the recording medium. Be done. An image is formed on the recording medium by intermittently repeating the recording scan (relative scan) of one band by the recording head 201 and the conveyance operation of the distance corresponding to one band by the conveyance roller 102.

  When waiting for a print command or performing maintenance processing on the recording head 201, the carriage 105 stands by at a home position h indicated by a dotted line in the drawing.

  In the above example, the ink tanks 106 to 109 and the recording head 201 are configured to be separately detachable from the carriage 105. However, the ink tanks 106 to 109 and the recording head 201 are integrally configured as a cartridge. It is good.

  FIGS. 2A and 2B are block diagrams showing the configuration of control in the inkjet recording apparatus 1. The recording control unit 301 mainly includes a memory 308 and a data processing unit 309 in addition to the CPU 307 as a calculation unit. The recording control unit 301 controls the entire apparatus in accordance with various programs and parameters stored in the memory 308. An attribute data table or the like, which will be described later, which is used for characteristic processing of the present invention, is also stored in the memory 308.

  The conveyance motor driver 302 drives a conveyance motor 304 for rotating the conveyance roller 102 and the paper feed roller 104 under the instruction of the recording control unit 301. The carriage motor driver 303 drives a carriage motor 305 for moving the carriage 105 under the instruction of the recording control unit 301. The head driver 306 drives the recording head 201 to perform a discharge operation under the instruction of the recording control unit 301.

  For example, the recording control unit 301 causes the data processing unit 309 to perform predetermined image processing on image data received from the host PC 500 via the interface 310 according to a program stored in the memory 308. As a result, discharge data that can be printed by the print head 201 is generated. Then, the recording control unit 301 drives various drivers while sequentially calling the temporarily stored ejection data based on the recording mode designated by the print job received from the host PC 500 and the program stored in the memory 308. And execute the recording operation.

  FIG. 2B is a block diagram for explaining the software configuration of data processing that the recording control unit 301 causes the data processing unit 309 to execute. When a print job is input from the host PC 500, the recording control unit 301 stores image data to be recorded in the reception buffer 401. The image processing unit 406 performs predetermined image processing on the image data stored in the reception buffer 401, and generates discharge data that can be recorded by the recording head 201. The details will be described below.

  In the present embodiment, the image data received from the host PC 500 is configured such that 8-bit luminance data (256 gradations) of red R, green G, and blue B are associated with each pixel of 600 dpi. . The image processing unit 406 performs predetermined image processing on these 600 dpi RGB multilevel data, and converts binary data indicating recording (1) or non-recording (0) corresponding to the recording resolution (1200 dpi) into black and cyan. , Magenta and yellow respectively.

  On the other hand, the attribute data generation unit 402 generates attribute data of each pixel while referring to the attribute data table 405 based on the 600 dpi image data stored in the reception buffer 401, and provides the generated attribute data to the attribute data integration unit 403. The attribute data integration unit 403 integrates the attribute data of each pixel according to a predetermined rule, and provides the obtained calculation result to the recording operation determination unit 404. The recording operation determination unit 404 determines the recording operation for each unit area of the recording medium based on the calculation result received from the attribute data integration unit 403. The attribute data, the contents of the attribute data table 405 to which the attribute data generation unit 402 refers, the integration method in the attribute data integration unit 403, and the determination of the recording method in the recording operation determination unit 404 will be described in detail later.

  FIG. 3 is a view showing an outline of two-pass bidirectional printing generally adopted by the ink jet printing apparatus. The two-pass bidirectional printing is a printing method for completing an image of a unit area of the printing medium S by two printing scans of the forward pass and the backward pass of the print head 201. In each recording scan, the recording head 201 performs the discharge operation in accordance with about half of the discharge data that can be recorded in one recording scan, and the conveyance motor 304 performs about half the recording head 201 between each recording scan. The recording medium S is conveyed in the Y direction by the distance (640 pixels).

  According to such two-pass bidirectional printing, for example, the image of the first unit area shown in the figure is completed by the first printing scan as the forward scanning and the second printing scan as the backward scanning. The image of the second unit area is completed by the second recording scan, which is a backward scanning, and the third recording scan, which is an outward scanning. The image of the third unit area is the fourth print scan of the forward scan, and the fourth print scan of the backward scan is the fourth print scan of the backward scan. Each is completed by a recording scan. That is, odd-numbered unit areas such as the first unit area and the third unit area are first subjected to forward scan and then backward scan to complete the image, and the second unit area and the fourth unit area. The even-numbered unit areas are first subjected to backward scan and then forward scan to complete the image.

  Here, referring to FIG. 1B again, in the forward scanning, the ink is applied to the recording medium S in the order of black → yellow → magenta → cyan. On the other hand, in the backward scanning, the ink is applied to the recording medium S in the order of cyan → magenta → yellow → black. And, such a difference in the application order of the ink may cause color difference in the image represented by the recording medium S, and may be recognized as color unevenness.

  However, such color unevenness has a color that is visually noticeable and a color that is less noticeable, and such a degree of conspicuousness can be predicted by analyzing image data. For example, in the case of a primary color using only one of black, cyan, magenta, and yellow, the order of application of the ink does not change between the forward scan and the backward scan, so that color unevenness does not occur. In addition, it can be said that color unevenness is less noticeable even when the bias of the ink color to be used is large or when the lightness is high and the application amount of the ink itself is small. On the contrary, in an image with low lightness (high density) using inks of two or more colors, it can be said that color unevenness is noticeable.

  In this embodiment, based on the RGB data of each pixel stored in the reception buffer 401, it is analyzed for each pixel whether or not the color unevenness is a noticeable color. Then, in the pixel area determined to be a color in which color unevenness is likely to be noticeable, two recording scans are unified to forward scanning, and the occurrence of color unevenness is suppressed.

  On the other hand, in the case of two-pass bidirectional printing, in addition to color unevenness, there may be a problem of image defects such as time difference unevenness. The time difference unevenness is a phenomenon that occurs because the time difference between the first recording scan and the second recording scan with respect to the unit area is not uniform throughout the image, and an image using only one type of ink may be recognized. is there.

  Here, attention is focused on the left end region surrounded by the broken line in FIG. In the left end area, in the first unit area, the carriage 105 reciprocates substantially once between the first recording scan (first recording scan) and the second recording scan (second recording scan). That is, the time difference between the first printing scan (first printing scan) and the second printing scan (second printing scan) is relatively large. On the other hand, in the left end area, in the second unit area, the carriage 105 performs only scanning without changing the direction between the first recording scan (first recording scan) and the second recording scan (second recording scan). It is. Therefore, the time difference between the first printing scan (second printing scan) and the second printing scan (third printing scan) is relatively small.

  In the case of the ink jet recording apparatus, the larger the time difference between the first recording scan and the second recording scan, the more likely the ink applied in the second recording scan is likely to remain on the surface of the recording medium and contribute to coloring. Therefore, for example, the first, third, and fifth unit areas having a large time difference between the first recording scan and the second recording scan, and the second and fourth unit areas having a small time difference between the first recording scan and the second recording scan. In the unit area, a difference appears in color development, which may be recognized as time difference unevenness. Also in the right end region surrounded by the broken line in FIG. 3, the same phenomenon occurs only when the magnitude relation of the time difference is reversed to that of the left end.

  Such time difference unevenness also has a color that is visually noticeable and a color that is less noticeable as in the case of color unevenness. Generally, regardless of the number of ink colors used, it can be said that the larger the ink application amount, the more noticeable. In addition, in the central area where ink is always applied in the middle of the carriage 105 scan, the time difference between the first recording scan and the second recording scan is almost uniform in any unit area, so that time difference unevenness hardly appears. That is, even with respect to the time difference unevenness, the conspicuousness can be predicted to some extent by analyzing the image data.

  Even for such time difference unevenness, the time difference between the first recording scan and the two recording scans can be made uniform between adjacent unit areas by switching to unidirectional recording, so that the phenomenon becomes inconspicuous. Can do. Further, with regard to the time difference unevenness, even in the case of bi-directional recording, the phenomenon can be made inconspicuous by providing a predetermined waiting time between the first and second recording scans.

  FIG. 4 is a view showing the relationship between the time difference between the first recording scan and the second recording scan on the recording medium and the color development (density). It can be seen that the larger the time difference, the higher the coloration (density) of the image. This is because the ink applied in the second printing scan tends to remain on the surface as the time difference is larger. However, it is also understood that the color development (density) approaches a constant value as the time difference increases, and the difference in time difference does not significantly affect color development if a time difference of a certain level or more is provided.

  For example, the width (length in the X direction) of the unit area is 42 inches, the scanning speed of the carriage 105 is 40 inches / second, and the reversal time of the carriage 105 is 0.2 seconds. At this time, in the left end area, the time difference between the first recording scan (first recording scan) and the second recording scan (second recording scan) in the first unit area is approximately 2.3 seconds (= 42/40 × 2 + 0). .2). The time difference between the first printing scan (second printing scan) and the second printing scan (third printing scan) in the second unit region is approximately 0.2 seconds. In FIG. 3, the color difference between the first unit area and the second unit area in such a left end area is indicated by ΔE1.

  Here, it is assumed that a waiting time of 0.25 seconds is provided between the first printing scan and the second printing scan. In this case, in the left end area, the time difference between the first recording scan (first recording scan) and the second recording scan (second recording scan) in the first unit area is about 2.55 seconds (= 42/40 ×). 2+ 0.2 + 0.25). In addition, the time difference between the first printing scan (second printing scan) and the second printing scan (third printing scan) in the second unit area is about 0.45 seconds (= 0.2 + 0.25). . In FIG. 3, the color difference between the first unit area and the second unit area in the left end area in such a case is indicated by ΔE2. When ΔE1 and ΔE2 are compared, it is apparent that ΔE2 is smaller, and it is possible to make the time difference uneven less noticeable by providing the standby time.

  As described above, in order to make the time difference unevenness inconspicuous, a method of aligning the first recording scan and the second recording scan in unidirectional recording, and between the first recording scan and the second recording scan Any method of providing a predetermined waiting time can be employed. However, under the above conditions, when the time required to complete an image of one unit area is compared by the former method and the latter method, it is apparent that the latter is shorter.

  When the first recording scan and the second recording scan are aligned to unidirectional recording, the time required to complete the image of the unit area is 3.55 seconds (= 42/40 × 3 + 0.2 × 2). Become. On the other hand, when a waiting time of 0.25 seconds is provided between the first recording scan and the second recording scan, the time required to complete the image of the unit area is 2.55 seconds (= 42 /). 40 × 2 + 0.2 + 0.25). For this reason, in the present embodiment, when color unevenness does not occur and only time difference unevenness occurs, bidirectional recording is performed without a switch to unidirectional recording, and a standby time of 0.45 seconds is interposed to achieve throughput. Try not to reduce it as much as possible.

  FIG. 5 is a flowchart for explaining the recording operation determination process executed by the recording control unit 301 when a print job is input from the host PC 500. Hereinafter, the recording operation determination processing will be described along the flowchart of FIG. 5 with reference to the block diagram of FIG.

  When the present process is started, the recording control unit 301 first expands the received image data in the reception buffer 401 in step S701. In the subsequent step S702, the recording control unit 301 acquires attribute data of each pixel using the attribute data generation unit 402, and stores the acquired attribute data in a memory different from the reception buffer 401 in step S703.

  FIGS. 6A and 6B are diagrams showing an example of the image data expanded in the reception buffer 401 in step S701 and the storage state of the attribute data in step S703. As described above, in the image data of the present embodiment, each pixel P has 8-bit luminance data (0 to 255) of RGB as a pixel signal, and the recording control unit 301 As shown in FIG. 6A, management is performed for each unit area (640 pixels wide). Here, luminance data of (RGB) = (128, 128, 128) is input to the first unit area, the second unit area, and the entire area of the fifth unit area, and the third unit area and the fourth unit area are input. The case where luminance data of (RGB) = (0, 0, 255) is input to the entire area of FIG.

  Refer again to FIG. 2 (b). The attribute data generation unit 402 generates attribute data corresponding to the luminance data of each pixel P shown in FIG. 6A by referring to the attribute data table 405.

  FIGS. 7A and 7B are diagrams for explaining the storage contents of the attribute data table 405 and the configuration of the attribute data. In the attribute data table 405, as shown in FIG. 7A, a combination of RGB signal values and 2-bit attribute data are stored in association with each other. Here, the argument for the RGB signal value is 0 to 63 is A, the argument for 64 to 127 is B, the argument for 128 to 191 is C, and the argument for 192 to 255 is D. There is. For example, in the case of (RGB) = (128, 128, 128), the arguments are (C, C, C), and the attribute data is “00”. When (RGB) = (0, 0, 255), the arguments are (A, A, D), and the attribute data is “10”.

  The attribute data of this embodiment is configured by 2 bits as shown in FIG. 7 (b). The upper bit is used to indicate the degree of color unevenness, and is “1” when color unevenness is a concern, and “0” otherwise. On the other hand, the lower bit is used to indicate the degree of time difference unevenness, and becomes “1” when time difference unevenness is concerned, and becomes “0” otherwise. For example, in the case of (RGB) = (128, 128, 128), the attribute data set with reference to FIG. 7A is "00", but there is no concern about color unevenness or time difference unevenness. Means. On the other hand, in the case of (RGB) = (0, 0, 255), the attribute data is “10”, which means that color unevenness is concerned and time difference unevenness is not concerned.

  The attribute data generation unit 402 refers to the attribute data table 405 shown in FIG. 7A and generates 2-bit attribute data corresponding to luminance data (RGB) of each pixel. Then, as shown in FIG. 6B, in a state of being associated with each pixel, it is stored in a memory different from the reception buffer 401.

  It returns to the flowchart of FIG. In step S704, the recording control unit 301 divides the image area into a plurality of integration unit areas 600, and in step S705, sets a determination area for each of color unevenness and time difference unevenness. The integration unit area 600 and the determination area will be described with reference to FIG. 6 (b) and FIG.

  In the present embodiment, the integration unit area 600 corresponds to the minimum area in which color unevenness and time difference unevenness can be visually recognized, and is a minimum unit for determining color unevenness and time difference unevenness. Specifically, an integration unit area 600 is a 768000 pixel area of 640 vertical pixels and 1200 horizontal pixels. On the other hand, the determination area is an integration unit area at a position where color unevenness and time difference unevenness can occur, and is set individually for color unevenness and time difference unevenness. In the present embodiment, since there is a concern that color unevenness is recognized in all image areas, the recording control unit 301 sets all integration unit areas as determination areas. On the other hand, with regard to time difference unevenness, there is a concern that is recognized in the left end region and the right end region, but a concern that is recognized in the center region is low. Therefore, the recording control unit 301 determines only the integration regions included in the left end region and the right end region Set Specifically, the integration unit area included in approximately 10 inches at both ends is set as the determination area (see FIG. 3).

  It returns to the flowchart of FIG. In step S706, the recording control unit 301 sets one of the plurality of integration unit areas as an integration unit area to be processed. In step S 707, it is determined whether the integration unit area to be processed is set as the color unevenness determination area. In the case of the present embodiment, since all the integration unit areas are included in the determination area, the process proceeds to step S 708.

  In step S 708, the recording control unit 301 searches all pixels included in the integration unit area to be processed, and counts the number C 1 of pixels in which the upper bit of the attribute data is “1”. Then, in the subsequent step S709, the recording control unit 301 determines whether the count value C1 is larger than a predetermined threshold T1. The threshold value T1 is not particularly limited, but when 76 or more pixels included in the integration unit area have more than one pixel whose upper bit of attribute data is "1", color unevenness of the area is recognized. It may be a value that indicates whether it will be If it is determined that C1> T1 in step S708, the recording control unit 301 proceeds to step S710, and turns on the upper bit flag of the unit area including the integration unit area to be processed. On the other hand, if C1 <T1, the process jumps to step S711. The upper bit flag is set to OFF by default.

  In step S711, the recording control unit 301 determines whether the integration unit area to be processed is set as the time difference unevenness determination area. If the time difference unevenness determination area is not set, the process directly jumps to step S715. On the other hand, if the integration unit area to be processed is set as the time difference unevenness determination area, the process proceeds to step S712.

  In step S712, the recording control unit 301 searches for all the pixels included in the integration unit area to be processed, and counts the number C2 of pixels in which the lower bit of the attribute data is “1”. Then, in step S713, the recording control unit 301 determines whether the count value C2 is larger than a predetermined threshold value T2. The threshold value T2 is not particularly limited, but when 76 or more pixels included in the integration unit area have more than one pixel whose lower bit of attribute data is "1", the time difference unevenness of the area is recognized. It may be a value that indicates whether it will be In step S711, if C2> T2, the recording control unit 301 proceeds to step S714, and turns on the lower bit flag of the unit area including the integration unit area to be processed. On the other hand, if C2 <T2, the process jumps to step S715. The lower bit flag is set to OFF by default.

  In step S715, it is determined whether the determination process of steps S707 to S714 has been performed for all integration unit areas. If it is determined that the integration unit area for which the determination process has not been performed still remains, the process returns to step S706 to perform the determination process on the next integration unit area. If it is determined that the determination process has been performed for all integration unit areas, the process proceeds to step S716.

  In step S716, the recording control unit 301 confirms the upper bit flag and the lower bit flag, and determines the recording operation for each unit area.

  FIG. 8 shows a table to which the recording control unit 301 refers in step S716. This table stores the correspondence between the combination of the upper bit flag that is ON when color unevenness is a concern, the lower bit flag that is ON when time difference unevenness is a concern, and the recording operation of the unit area. It is done. For example, for a unit area in which neither the upper bit flag nor the lower bit flag is OFF, that is, neither color unevenness nor time difference unevenness is concerned, bidirectional recording without waiting time is set. For a unit area in which the upper bit flag is OFF and the lower bit flag is ON, that is, there is no concern about color unevenness, however, bi-directional recording with a waiting time is set for unit areas where time difference unevenness is a concern. When the upper bit flag is ON and the lower bit flag is OFF, ie, unit areas in which color unevenness is concerned but time difference unevenness is not concerned, unidirectional recording without standby time is set. For unit areas in which the upper bit flag and the lower bit flag are both ON, that is, color unevenness and time difference unevenness are also concerned, unidirectional recording without standby time is set.

  FIG. 9 is a diagram showing the recording operation for the first to fifth unit areas when the image data as shown in FIG. 6A is input. When image data as shown in FIG. 6A is input, the setting states of the upper bit flag and the lower bit flag of each unit area are as shown on the right of FIG. 6B, and the recording control unit 301 The recording operation of each unit area is determined based on the table shown in FIG. In the first unit area, the second unit area, and the fifth unit area in which neither color unevenness nor time difference unevenness is concerned, an image is recorded by default recording operation, that is, two-pass bidirectional recording. On the other hand, in the second unit area and the third unit area where color unevenness is concerned but time difference unevenness is not concerned, an image is recorded by 2-pass unidirectional printing. As a result, it is possible to output a uniform image in which color unevenness and time difference unevenness are not noticeable over the entire image area.

  FIGS. 10A and 10B are diagrams showing another example of image data input to the ink jet recording apparatus of the present embodiment and attribute data corresponding to the image data. Here, luminance data of (RGB) = (128, 128, 128) is input to the first unit area, the second unit area, and the entire area of the fifth unit area, and the third unit area and the fourth unit area are input. A case is shown in which luminance data of (RGB) = (32, 32, 32) is input to the entire area of.

  In the case of such image data, the attribute data generation unit 402 refers to the attribute data table 405 shown in FIG. 7A, and for the first unit area, the second unit area, and the fifth unit area, all pixels Attribute data "00" is generated. In addition, attribute data “01” is generated for all pixels in the third unit area and the fourth unit area. The upper bit flag and the lower bit flag in each unit area are set as shown on the right side of FIG. 10 (b).

  FIG. 11 is a diagram showing the recording operation for the first unit area to the fifth unit area when the image data as shown in FIG. 10A is input. In the first unit area, the second unit area, and the fifth unit area in which neither color unevenness nor time difference unevenness is concerned, an image is recorded by two-pass bidirectional printing. On the other hand, in the second unit area and the third unit area where color unevenness is not a concern but time difference unevenness is a concern, the image is a 2-pass bidirectional printing in which a waiting time of 0.45 seconds is provided between two printing scans. Is recorded. As a result, it is possible to output a uniform image in which color unevenness and time difference unevenness are not noticeable over the entire image area.

  In the above, the case where pixel data of the same signal value is input to all the pixels for the unit area has been described as an example, but such image data is, of course, only an example. In the present embodiment, the flag for the upper bit of the unit area is set to ON in step S710 if there is even one of the plurality of integration unit areas included in the unit area that has the count value C1 exceeding the threshold T1. And measures against color unevenness are applied to the entire unit area. Similarly, if there is even one of the plurality of integration unit areas included in the unit area that has the count value C2 exceeding the threshold T2, the lower bit flag of the unit area is set to ON, and the unit area Measures against uneven time are taken for the whole. That is, even if any image data is input, if there is a portion where color unevenness or time difference unevenness is concerned, neither the color unevenness nor time difference unevenness in the portion is noticeable. The recording operation of the entire unit area including the portion is set.

  As described above, according to the present embodiment, the concern about color unevenness and time difference unevenness may be determined from the same image data, and the recording operation may be controlled around the unit area so that the respective image defects can be alleviated. it can.

Second Embodiment
Also in the present embodiment, as in the first embodiment, the recording control unit 301 executes the recording operation determination process according to the flowchart shown in FIG. 5 using the ink jet recording apparatus shown in FIGS. The present embodiment differs from the first embodiment in the attribute data and the contents of the attribute data table.

  FIGS. 12A and 12B are diagrams showing the configuration of the attribute data table 405 to which the attribute data generation unit 402 refers in step S702 in FIG. 5, and the attribute data. As shown in FIG. 12A, the attribute data table 405 of this embodiment also stores combinations of RGB signal values and 2-bit attribute data in association with each other as in the first embodiment.

  The attribute data of this embodiment is constituted by 2 bits as in the first embodiment, but the contents indicated by the upper bits and the lower bits are different from those of the first embodiment. In the first embodiment, the upper bits and the lower bits are associated with different image defects, but in the present embodiment, they are associated with different elements constituting the recording operation. Specifically, the upper bit (first element) of the attribute data corresponds to the recording scan direction, and "0" is set when two-way recording is recommended, and "1" is set when one-term recording is recommended. . The lower bit (second element) corresponds to the presence or absence of the waiting time before the start of scanning, and is set to "0" when the waiting time is not provided and "1" when the waiting time is provided.

  For this reason, in the attribute table of the present embodiment shown in FIG. 12A, the recording operation (scanning direction and waiting time) is made to make the RGB arguments and images of the RGB values inconspicuous in color unevenness and time difference unevenness. ) Are stored in association with each other. For example, with respect to RGB values (for example, (A, B, A)) in which both color unevenness and time difference unevenness are concerned, the attribute is “11” in FIG. 7A described in the first embodiment. In contrast to this, in the present embodiment, it is "10". This is because, in the case of an image (A, B, A) in which both color unevenness and time difference unevenness are concerned, if unidirectional recording is adopted, both color unevenness and time difference unevenness become noticeable even without providing a waiting time. It is because it can be eliminated.

  The other steps are the same as in the first embodiment. If the recording control unit 301 determines that the count value C1 is larger than the threshold T1 (S709), the upper bit flag is set to ON (S710), and if it is determined that the count C2 is larger than the threshold T2 (S713), the lower bits The flag is set to ON (S714). Then, in step S716, the recording control unit 301 determines the recording operation for each unit area based on the table shown in FIG. 8 as in the first embodiment.

  Also in the embodiment described above, as a result, the same recording operation as that of the first embodiment can be realized. That is, when the image data of FIG. 6A is input, the image is recorded by the recording operation shown in FIG. When the image data of FIG. 10A is input, the image is recorded by the recording operation shown in FIG. That is, also in the present embodiment, as in the first embodiment, the recording operation can be controlled for each unit area based on the same image data so as to alleviate both color unevenness and time difference unevenness.

  In the embodiment described above, the recording operation determination process for a plurality of unit areas has been described in the content of performing one print job unit, using the flowchart of FIG. 5. However, the recording operation determination process can also be performed for each unit area. For example, when image data for one unit area is expanded in the reception buffer, the processing in steps S702 to S716 is performed on the unit area, and when image data for the next one unit area is expanded, the unit The same process may be performed again on the area.

  Further, the size of the integration unit area, the determination area, the standby time, and the threshold values T1 and T2 are not limited to the values shown in the above embodiment. The appearance of color unevenness and time difference unevenness varies depending on various factors such as the type and size of the recording medium, the physical properties of the ink, the recording resolution, and the carriage speed. It is preferable that the above-mentioned values be appropriately adjusted in accordance with the above-mentioned various factors in order to make color unevenness and time difference unevenness hardly noticeable.

  Furthermore, the image defects that the present invention eliminates are not limited to color unevenness and time difference unevenness. The present invention can be applied for the purpose of suppressing image defects other than color unevenness and time difference unevenness if analysis of image data can predict the appearance and adjust the degree of appearance by recording operation. In this case, for example, one of the upper bit and the lower bit may be used for an image defect different from color unevenness or time difference unevenness, or the third bit may be newly added because of the third image defect. good.

  Further, the elements for switching the recording operation are not limited to two, the recording direction and the waiting time. For example, the carriage speed or the conveyance speed may be changed instead of the waiting time. Also, the dither pattern or index pattern used in the quantization process may be switched, or the mask pattern used in multi-pass printing or the number of multi-passes (the number of printing scans for a unit area) may be switched.

  In any case, by analyzing the received image data, attribute data in which plural types of image defect information are stored can be generated, and the recording operation can be appropriately adjusted based on the attribute data. It can function effectively.

(Other embodiments)
The present invention supplies a program that implements one or more functions of the above-described embodiments to a system or apparatus via a network or storage medium, and one or more processors in a computer of the system or apparatus read and execute the program. Can also be realized. It can also be implemented by a circuit (eg, an ASIC) that implements one or more functions.

Reference Signs List 1 inkjet recording apparatus 201 recording head 202 discharge port 301 recording control unit 402 attribute data generation unit 404 recording operation determination unit S recording medium

Claims (12)

An inkjet recording apparatus that records an image on a recording medium by causing a recording head relative to a recording medium to scan a recording head having ejection openings arranged to eject ink according to image data.
Generation means for generating, for each pixel, attribute data including information on a first element and information on a second element based on pixel signals of individual pixels of the image data;
An ink jet recording apparatus comprising: recording operation determining means for determining the form of the relative scan for recording the corresponding pixel based on the information on the first element and the information on the second element. The images of the same unit area of the recording medium are recorded by the same plurality of relative scans by the recording head,
The recording operation determining means determines, for each of the unit areas, a direction of relative scanning of the recording head relative to the recording medium and a standby time until starting the relative scanning as the form of the relative scanning. The inkjet recording apparatus according to claim 1, wherein   The recording operation determining means determines the direction of the relative scan according to the information of the first element for each of the unit areas, and determines the waiting time according to the information of the second element. The inkjet recording device as described in 2. The attribute data is 2-bit data in which each of the first element and the second element indicates a value of 1 or 0,
The recording operation determination means compares, with respect to each of the integration unit areas formed by dividing the unit area into a plurality of units, the number of pixels in which the first element indicates 1 with a first threshold, and the second element 4. The inkjet recording according to claim 3, wherein the direction of the relative scanning with respect to the unit area and the waiting time are set based on the result of comparing the number of pixels indicating 1 with a second threshold. apparatus.   The first element corresponds to color unevenness that occurs due to the application order of ink of different colors to the unit area, and the second element corresponds to time difference unevenness due to the time difference of the plurality of relative scans to the unit area The ink jet recording apparatus according to any one of claims 2 to 4, wherein:   6. The attribute data generation method according to claim 1, wherein the generation unit generates the attribute data by referring to a table in which the pixel signal of the pixel and the attribute data are stored in association with each other. An inkjet recording device according to item 1. An ink jet recording method for recording an image on a recording medium by causing a recording head to relatively scan a recording medium having a recording head in which discharge ports for discharging ink are arranged according to image data.
Generating, for each pixel, attribute data including information on a first element and information on a second element based on pixel signals of individual pixels of the image data;
An ink jet recording method comprising a recording operation determining step of determining a form of the relative scanning for recording a corresponding pixel based on the information on the first element and the information on the second element. The images of the same unit area of the recording medium are recorded by the same plurality of relative scans by the recording head,
The recording operation determining step is characterized in that the direction of relative scanning of the recording head with respect to the recording medium and the waiting time until starting the relative scanning are determined as the form of the relative scanning for each of the unit areas. The inkjet recording method according to claim 7, wherein   The recording operation determination step determines the direction of the relative scan according to the information of the first element for each of the unit areas, and determines the waiting time according to the information of the second element. 8. The ink jet recording method according to 8. The attribute data is 2-bit data in which each of the first element and the second element indicates a value of 1 or 0,
The recording operation determination step compares the number of pixels in which the first element indicates 1 with a first threshold value for each of the integration unit areas obtained by dividing the unit area into a plurality, and the second element 10. The inkjet recording according to claim 9, wherein the direction of the relative scanning with respect to the unit area and the waiting time are set based on the result of comparing the number of pixels indicating 1 with a second threshold value. Method.   The first element corresponds to color unevenness that occurs due to the application order of ink of different colors to the unit area, and the second element corresponds to time difference unevenness due to the time difference of the plurality of relative scans to the unit area The ink jet recording method according to any one of claims 8 to 10, wherein:   12. The attribute data generation method according to any one of claims 7 to 11, wherein the generation step generates the attribute data by referring to a table in which the pixel signal of the pixel and the attribute data are associated and stored. The inkjet recording method according to item 1.

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