JP2006001054A - Inkjet recorder, inkjet recording method, data generator and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording system and an inkjet recording method for recording a high quality image under highly reliable state by controlling the position and timing at which an ink drop is imparted to a recording medium preferably. <P>SOLUTION: The inkjet recording system comprises an arrangement for determining the recording position of a dot at the time of binary recording with reference to a mask pattern when multipass recording is performed. Since the recording position where ink is imparted to a recording medium and record scanning for imparting ink to the recording position can be controlled, required image quality and reliability can be attained in compliance with the purpose. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention executes a process of converting image data quantized in several stages into binary data in which dot recording / non-recording is determined, and multipass recording using a mask pattern for the binary data The present invention relates to an ink jet recording apparatus, an ink jet recording method, a data generation apparatus, and a program.

  With the recent spread of information processing equipment such as personal computers, recording devices as image forming terminals have been rapidly developed and spread. In particular, among various recording apparatuses, an ink jet recording apparatus that performs recording on a recording medium such as paper, cloth, a plastic sheet, and an OHP sheet by ejecting ink from an ejection port is a low-noise non-impact recording method. It has excellent features such as high-density and high-speed recording operations, easy compatibility with color recording, and low cost, and is now the mainstream of personal-use recording devices. ing. Furthermore, in recent years, inkjet recording apparatuses have been able to output higher-quality images by dramatically increasing the recording resolution and the accompanying reduction in recording droplets. ing.

  However, higher resolution and higher definition of recorded images increase the amount of data to be processed in the recording system. Along with this, the image processing time and the transfer time are increased, and the image output time of the entire recording system is reduced.

  In response to this problem, a configuration and a processing method for performing data processing at a resolution lower than the recording resolution of the recording apparatus have already been proposed and implemented (see, for example, Patent Document 1 and Patent Document 2). According to Patent Document 1, a recording system configured to input quinary image data at a resolution of 300 dpi from a host device to a recording device that performs binary recording with a recording resolution of, for example, 600 dpi (dot / inch; reference value). It is disclosed. Since image processing requires various and complicated processes such as luminance density conversion and quantization, even if it is executed by a host device such as a personal computer, its processing load and processing time are The number of pixels to be greatly affected. Therefore, by executing processing at a resolution lower than the recording resolution in this way, image processing can be completed in a shorter time with a smaller amount of data.

  However, in a binary recording apparatus that forms an image by dot recording / non-recording, it is necessary to perform resolution conversion for outputting image data received in 300 dpi 5 values in 600 dpi binary, At this stage, so-called dot arrangement patterning processing is applied.

  FIG. 1 is a schematic diagram for explaining the dot arrangement patterning process. The left side of the figure shows a five-value image signal input to the recording apparatus at 300 dpi, and the right side shows an output pattern in which dot recording / non-recording is associated with each image signal. Each output pattern corresponding to one pixel of 300 dpi is composed of four 600 dpi areas shown in a small grid, 2 × 2 in the horizontal direction. Each part indicates an area where no dot is recorded.

  For level 0 and level 4, only one output pattern is prepared, but for level 1 to level 3, a plurality of arrangement patterns are prepared. Japanese Patent Application Laid-Open No. 2004-151620 discloses the content of selecting and arranging these plural patterns sequentially or randomly. As a result, the dot positions to be formed are not fixed even in an image having a uniform density, and it is described that there is an effect of reducing the “rushing phenomenon” associated with the pseudo halftone process. Further, Patent Document 2 discloses a configuration and an effect in which the plurality of patterns are sequentially arranged in association with the nozzle configuration of the recording head so that the discharge frequency is not biased in the plurality of nozzles of the recording head. Yes. As described above, the dot arrangement patterning process is a process for determining the dot arrangement actually recorded on the recording medium. Therefore, not only the burden of image processing before the dot arrangement patterning process is reduced, but also by devising the arrangement method, for example, the ejection frequency of a plurality of printing elements can be made uniform, irregularities peculiar to the printing apparatus, etc. Making it inconspicuous can contribute to image quality, reliability of the recording apparatus, and the like.

  The image data binarized by the dot arrangement patterning process can be directly transferred to the drive circuit of the print head and recorded. However, in a general ink jet printing apparatus, multi-pass printing is often executed by further performing mask data conversion processing on the binary data. The multipass recording will be briefly described below.

  FIG. 2 schematically shows a recording head and a recording pattern in order to explain multipass recording. P0001 indicates a recording head. Here, for simplicity, it is assumed that the recording head has 16 recording elements (hereinafter also referred to as nozzles). As shown in the drawing, the nozzles are divided into first to fourth nozzle groups, and each nozzle group includes four nozzles. P0002 indicates a mask pattern, and an area (recordable portion) where each nozzle can perform recording is indicated in black. The patterns recorded by each nozzle group are complementary to each other. When these patterns are overlapped, recording of a region corresponding to a 4 × 4 area is completed.

  Each pattern indicated by P0003 to P0006 shows a state in which an image is completed by overlapping recording scans. When each recording scan is completed, the recording medium is conveyed by the width of the nozzle group in the direction of the arrow in the figure. Therefore, the same area of the recording medium (area corresponding to the width of each nozzle group) is configured such that an image is completed only after four recording scans.

  A slight variation in the direction and amount of ink discharge inevitably occurs between the plurality of nozzles of the ink jet recording head in the manufacturing process. Further, in the serial type recording apparatus, the sub-scanning amount (paper feed) performed during each recording scan includes a structural error to some extent. Such errors and variations cause image defects such as streaks and density unevenness in a recording medium on which ink is recorded. However, by adopting the multi-pass recording as described above, it is possible to reduce the above-mentioned image adverse effects. This is because even if there are variations in the ejection characteristics and the transport amount of each nozzle, these characteristics are dispersed throughout the image and become inconspicuous.

  In FIG. 2, the description has been given by taking as an example four-pass printing in which the same image area is scanned four times. However, the multi-pass recording itself is not limited to this. Two-pass printing in which an image is completed by two recording scans or a configuration in which an image is completed by five or more recording scans may be used. As the number of multi-passes increases, the variation in ejection characteristics and transport amount of each nozzle is distributed over a wider range, so that a smoother image can be obtained. However, on the other hand, the number of recording scans of the recording head for the same image area increases, and more recording time is consumed. Therefore, in recent recording systems, there are various recording modes depending on the type and application of the recording medium, such as a mode in which the number of multipasses is small and the recording speed is important, and a mode in which the number of multipasses is important and the image quality is important. It is prepared. In this case, the mask pattern as shown in FIG. 2 is prepared for each recording mode, and is generally stored in a memory in the recording apparatus.

  FIG. 3 is a schematic diagram for explaining an example of storing mask patterns. Here, two types of masks are shown as a mask 1 and a mask 2 taking a two-pass multi-pass as an example. The two masks here represent an area of 8 areas × 8 areas, and each area corresponds to 1 bit that can be expressed by 1 or 0. The two masks are complementary to each other. The area of 0 in mask 1 is 1 in mask 2, and the area of 1 in mask 1 is 0 in mask 2. That is, the data recorded with the mask 1 is not recorded with the mask 2, and the data not recorded with the mask 1 is recorded with the mask 2.

  The image data binarized by the dot arrangement patterning process is input to the mask data conversion process as 1 (printed) or 0 (non-printed) data corresponding to each area. In the mask data conversion process, mask 1 or mask 2 is made to correspond to the input binary data, and an AND operation is performed. When the calculation result is 1, it means recording, and the recording information is transferred to the drive circuit of the recording head. On the other hand, when the calculation result is 0, even if the input data is 1 (recording), it means non-recording, and recording is not executed.

  For example, in the case of a recording head having 128 nozzles, the mask 1 can correspond to the upper half 64 nozzles, and the mask 2 can correspond to the lower half 64 nozzles. In this state, the AND process and the print scan are performed, and a 64-nozzle width sub-scan is performed between the print scans, thereby realizing a 2-pass multi-pass.

  The mask data conversion process is a process for determining at which timing (which recording scan) each dot in the array determined in the dot arrangement patterning process is to be recorded. Therefore, by devising the arrangement of the mask pattern, the number of recording dots in each recording scan performed on the recording medium is adjusted, the recording frequency of nozzles that are likely to cause problems is reduced, image quality, This can contribute to the reliability of the recording apparatus.

  By applying the dot arrangement patterning process and the mask data conversion process described above to the recording data, in recent inkjet recording apparatuses, high-definition and high-resolution recording can be performed at a relatively high speed and without any unevenness. It can be output as an image.

Japanese Patent No. 3423491 JP 2001-54956 A

  However, even if the dot arrangement patterning process and the mask data conversion process as described above are appropriately executed according to the respective purposes, a new problem may arise because both are designed independently of each other. there were.

  Even if the dot arrangement pattern is output sequentially or randomly as in Patent Document 1 and Patent Document 2, the mask pattern prepared in the mask data conversion process is a fixed pattern prepared in advance. That is, since the mask pattern arrangement is not determined after predicting the dot arrangement in each dot arrangement pattern, depending on the dot arrangement state in the dot arrangement pattern (within 300 dpi pixels), uneven printing is performed. In some cases, dots are intensively recorded by scanning, or adjacent dots are recorded by simultaneous recording scanning, resulting in image defects such as blurring.

  For example, consider a case where two adjacent dots included in the same pixel of 300 dpi are recorded by 4-pass multi-pass printing. At this time, there are four possible relative timings at which the two dots are recorded. That is, the timing when two are recorded by the same recording scan, the timing when recorded by two consecutive recording scans, the timing when recorded by two recording scans sandwiching one recording scan, and two more times This is the timing for recording in two recording scans including the recording scan. These four timings change the time difference at which two drops of ink land on the recording medium, and this time difference greatly affects the ink absorption state on the recording medium. When two dots are recorded in the same recording scan, two drops of ink are landed on the recording medium almost simultaneously. Therefore, two drops are mixed and absorbed by the recording medium at the same time. On the other hand, when two drops are recorded after several recording scans, the second drop of ink is landed after the first drop of ink has already been absorbed by the recording medium. Therefore, the two drops are absorbed by the recording medium independently without mixing. Such a difference in absorption state is confirmed as a difference in color developability such as density and hue on the surface of the recording medium.

  That is, in the conventional configuration, the recording order for each area is not managed even between pixels to which the same image signal is given, so the density and hue expressed in the area are uniformly expressed. There wasn't. This may be confirmed as unevenness.

  As described above, the position and timing at which each ink droplet is applied to the recording medium greatly affects the image. Here, unevenness is taken as an example, but problems such as streaks may occur. In addition, the position and timing at which ink droplets are applied prescribes the recording element that performs ejection and the ejection timing, so if it has a biased tendency, the reliability of the recording apparatus or recording head is impaired. There is also. Therefore, in order to maintain the image quality and the reliability of the recording apparatus, it can be said that the position and timing at which the ink droplets are applied to the recording medium are preferably controlled to have a predetermined tendency.

  However, in the conventional configuration in which the dot arrangement pattern prepared in advance and the mask data are combined, these are not sufficiently controlled.

  The present invention has been made to solve such problems, and the object of the present invention is to control the position and timing at which ink droplets are applied to a recording medium in a preferable state, thereby achieving high quality. It is to provide an ink jet recording apparatus, an ink jet recording method, a data generation apparatus, and a program capable of recording a reliable image in a highly reliable state.

  Therefore, in the present invention, a recording head having a plurality of recording elements arranged at a density corresponding to the recording resolution P is used, and recording is performed by ejecting ink from the plurality of recording elements while scanning the recording head in a predetermined direction. In an inkjet recording apparatus that performs main scanning and sub-scanning that transports a recording medium in a direction that intersects with the recording main scanning, and that an image is formed by arranging dots formed on the recording medium at a resolution P. Dot arrangement means for converting image data having a multi-value level L (L> 2) at a resolution K (K <P) into binary image data in which a dot recording position is determined at the recording resolution P; Binary image data obtained from the dot arrangement means so that an image to be recorded in the same image area of the medium is completed step by step by a plurality of recording main scans. Generating means for generating ink ejection / non-ejection data in each recording scan for each of the recording elements by taking a logical product with a predetermined mask pattern; and ink generated by the generating means Recording means for ejecting ink from the plurality of recording elements in accordance with the ejection / non-ejection data, and the dot placement means records dots at the recording resolution P by referring to the mask pattern. The position is determined.

  Also, a recording main scan that uses a recording head having a plurality of recording elements arranged at a density corresponding to the recording resolution P, and ejects ink from the plurality of recording elements while moving and scanning the recording head in a predetermined direction; In an inkjet recording method in which an image is formed by performing a sub-scan that transports a recording medium in a direction crossing the main recording scan and arranging dots formed on the recording medium at a resolution P, the resolution K (K < A dot arrangement step of converting image data having a multi-value level L (L> 2) in P) into binary image data in which the dot recording position at the recording resolution P is determined, and the same image area of the recording medium The binary image data obtained in the dot placement step is determined in advance so that an image to be recorded in a step is completed in stages by a plurality of recording main scans. By generating a logical product with the mask pattern, a generation process for generating ink ejection / non-ejection data in each print scan for each of the printing elements, and an ink ejection / non-ejection of the ink generated in the generation process A recording step of ejecting ink from the plurality of recording elements in accordance with the data, wherein the dot placement step determines a dot recording position at the recording resolution P by referring to the mask pattern. Features.

  Furthermore, using a recording head having a plurality of recording elements arranged at a density corresponding to the recording resolution P, a recording main scan for discharging ink from the plurality of recording elements while moving and scanning the recording head in a predetermined direction; Data used for an inkjet recording apparatus in which an image is formed by arranging dots formed on the recording medium at a resolution P by performing a sub-scan that conveys the recording medium in a direction crossing the main recording scan. A data generation device for converting image data having a multilevel L (L> 2) at a resolution K (K <P) into binary image data in which a dot recording position is determined at a recording resolution P The dot placement means and the dot placement means so that an image to be recorded in the same image area of the recording medium is completed in stages by the plurality of recording main scans. Generating means for generating ink ejection / non-ejection data in each printing scan for each of the printing elements by taking a logical product of the binary image data obtained from the above and a predetermined mask pattern The dot placement means determines a dot recording position at the recording resolution P by referring to the mask pattern.

  Furthermore, a recording main scan using a recording head having a plurality of recording elements arranged at a density corresponding to the recording resolution P, and ejecting ink from the plurality of recording elements while moving and scanning the recording head in a predetermined direction; Data used in an ink jet recording apparatus in which an image is formed by performing sub-scanning for transporting the recording medium in a direction crossing the main recording scanning and arranging dots formed on the recording medium at a resolution P. By referring to a mask pattern used for generating an image to be recorded in the same image area of the recording medium in stages by a plurality of recording main scans, a resolution K (K <P) and image data having a multilevel L (L> 2) are binary image data in which the dot recording position at the recording resolution P is determined. A binary image data obtained in the first step, and a first step to convert, and an image to be recorded in the same image area of the recording medium in a stepwise manner by a plurality of recording main scans; And a second step of generating ink ejection / non-ejection data in each printing scan for each of the printing elements by taking a logical product with the mask pattern. .

  According to the present invention, the recording position where ink is applied to the recording medium and the recording scanning where ink is applied to the recording position can be controlled according to the purpose, so that desired image quality and reliability can be obtained. I can do it.

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

(First embodiment)
FIG. 4 is a block diagram for explaining the flow of image data conversion processing in the inkjet recording system of the present embodiment. The ink jet recording apparatus applied in the present embodiment performs recording with inks of four colors of cyan, magenta, yellow, and black. For this purpose, a recording head J0010 that discharges these four colors of ink is prepared. The recording system of this embodiment is configured by a recording device and a personal computer (PC) as a host device.

  There are an application and a printer driver as programs that operate in the operating system of the host device, and the application J0001 executes processing for creating image data to be recorded by the recording device. At the time of actual recording, image data created by the application is passed to the printer driver.

  Assume that the printer driver in this embodiment includes a pre-stage process J0002, a post-stage process J0003, a γ correction J0004, a halftoning J0005, and a print data creation J0006. Here, each process will be briefly described. The pre-stage process J0002 performs color gamut mapping. Thereby, data conversion for mapping the color gamut reproduced by the image data R, G, B of the sRGB standard into the color gamut reproduced by the recording apparatus is performed. Specifically, luminance signals expressed in 8 bits of R, G, and B configured with a pixel density of 300 dpi are used, and each color uses 8-bit data of R, G, and B by using a three-dimensional LUT. Convert to

  The post-stage process J0003 is a process for obtaining the color separation data Y, M, C, and K corresponding to the combination of inks that reproduce the color represented by the data based on the data R, G, and B on which the color gamut is mapped. Do. Here, similarly to the pre-processing, it is assumed that interpolation calculation is performed in combination with a three-dimensional LUT.

  The γ correction J0004 performs gradation value conversion for each color data of the color separation data obtained by the post-processing J0003. Specifically, by using a one-dimensional LUT corresponding to the gradation characteristics of each color ink of the recording apparatus, conversion is performed so that the color separation data is linearly associated with the gradation characteristics of the recording apparatus.

  Halftoning J0005 performs quantization by converting 8-bit color separation data Y, M, C, and K configured with a pixel density of 300 dpi into 4-bit data configured with a pixel density of 300 dpi. In the present embodiment, 256-level 8-bit data is converted into 5-level 4-bit data using a multi-level error diffusion method. This 4-bit data is data serving as an index for indicating an arrangement pattern in the dot arrangement patterning process in the printing apparatus.

  At the end of the processing performed by the printer driver, print data is created by adding print control information to the print image data containing the 4-bit index data as described above by print data creation processing J0006.

  The printing apparatus performs a dot arrangement patterning process J0007 and a mask data conversion process J0008 on the input print data.

  In the dot arrangement patterning process of this embodiment, a 2 × 2 dot arrangement pattern in which dot recording / non-recording is determined is assigned to 4-bit data configured with a pixel density of 300 dpi, and 1 bit of 600 dpi. Convert to binary data. In this embodiment, the dot arrangement pattern shown in FIG. 1 is applied. However, 300 dpi level 1 to level 3 are not dealt with in a random or sequential order as in the prior art, but by referring to a predetermined mask pattern applied in the mask data conversion process J0008, One of the plurality of arrangement patterns is selected.

  FIG. 5 is a flowchart for explaining a process of selecting one of a plurality of arrangement patterns by referring to a mask pattern.

  When this process is started, first, in step S301, a recording mode to be executed by the recording apparatus is set. In step S302, a mask pattern corresponding to the set recording mode is stored in the memory.

  In step S303, data for one pixel output from the halftoning J0005 is acquired.

  In the subsequent step S304, the position of the mask pattern corresponding to the one pixel is confirmed, and one of a plurality of dot arrangement patterns is selected according to the recording / non-recording arrangement state of the mask pattern in that region.

  In step S305, it is determined whether or not the above processing has been completed for all input pixels from the host device. If it is determined that the process has been completed, the process ends. On the other hand, if it is determined that the process has not been completed, the process returns to step S303, and the process for the next pixel is continued.

  In this embodiment, in step S304, a dot arrangement pattern is selected based on the following four conditions. The first condition is that the adjacent areas are recorded by different recording scans in the dot arrangement pattern (in one pixel of 300 dpi). The second condition is that dots recorded in the dot arrangement pattern (in one pixel of 300 dpi) are recorded by different recording scans. The third condition is that dots are allocated to each printing scan in accordance with the printing ratio in each printing scan set in the mask data conversion process. The fourth condition is that when attention is paid to an area of 8 areas × 4 areas of a binary image, dots are allocated to each printing scan according to the printing ratio in each printing scan set in the mask data conversion process. It is. The third and fourth conditions are, for example, for any level of gradation value when performing 4-pass multi-pass printing using a mask having a printing rate of 25% for each printing scan. This also means that the number of dots printed in each printing scan is 25% of the total number of dots within a predetermined area. The priorities of the above four conditions are set in the order of conditions 1, 2, 3, and 4.

  An example of setting a dot arrangement pattern when performing 4-pass multi-pass printing according to the above method will be described.

  FIGS. 6A and 6B show examples of mask patterns applied in the present embodiment. Here, for the sake of simplicity, an area of 8 horizontal areas × 4 vertical areas is shown. In FIG. 6A, the mask 1 corresponds to a first pass mask for a predetermined image area of the recording medium. Similarly, the mask 2 indicates the second pass mask, the mask 3 indicates the third pass mask, and the mask 4 indicates the fourth pass mask. These masks are stored in a memory in the recording apparatus. FIG. 6B shows by numbers the number of scanning scans for each area corresponding to the mask.

  FIG. 7 shows an example of the gradation value of each 300 dpi pixel input to the dot arrangement patterning process. The numbers shown in each of the pixels 512 to 519 represent the gradation value given to each pixel.

  FIG. 8 shows a dot arrangement pattern determined corresponding to each pixel according to the flowchart shown in FIG. Each signal value given to 512 to 519 in FIG. 7 is converted into a pattern of 601 to 608 configured by 2 × 2 areas of 600 dpi.

  For example, in the pixel 512 of FIG. Referring to FIG. 1, there are four types of patterns that express gradation value 1. Here, if the pattern 101 is selected, this pattern is arranged at 601 in FIG. Referring to FIG. 6, dots are recorded in the area in the first pass (first recording scan).

  When 513 in FIG. 7 is the next pixel, the gradation value of the pixel is 2. Referring to FIG. 1, there are six types of patterns expressing the gradation value 2. According to FIG. 6B, the number of passes in which each area corresponding to this area is recorded is the second pass, the first pass, the first pass, and the fourth pass from the upper left. In the adjacent area 601, since it is determined that the first pass is recorded in the upper left area, the pattern 102 in FIG. 1 is obtained by adding the above conditions 1 to 4 in addition to the above information. Is selected and placed at 602 in FIG.

  Furthermore, when 514 in FIG. 7 is the next pixel, the gradation value of the pixel is 3. Referring to FIG. 1, there are four types of patterns that represent the gradation value 3. According to FIG. 6B, the number of passes in which each area corresponding to this area is recorded is the third pass, the first pass, the second pass, and the second pass from the upper left. In the areas 602 and 601, the positions and the number of passes where dots are already recorded are already determined. In addition to the above information, the pattern 103 in FIG. , Arranged at 603 in FIG.

  As described above, the dot arrangement pattern is determined for each pixel in step S304 in FIG. 5 while taking various conditions into consideration. When determining the dot arrangement pattern, all the conditions 1 to 4 may not be satisfied. In this case, even if a certain condition is not satisfied, this embodiment is effective if the dot arrangement pattern is selected so as to satisfy as many conditions as possible according to the priority order of the conditions.

  FIG. 9 is a diagram showing a result of AND processing using the masks 1 to 4 shown in FIG. 6 for the dot data FIG. 8 created according to the above-described process. According to the figure, adjacent dots are not recorded in the same recording scan, that is, the first condition is completely satisfied. In each printing scan, one dot or less is recorded in one dot arrangement pattern (one pixel of 300 dpi), and the second condition is also satisfied. Further, the number of dots to be recorded in each recording scan is equally divided into 5 dots, and the recording ratio of mask 1 to mask 4 (same ratio 25%) is maintained. This also satisfies the fourth condition.

  As described above, in this embodiment, in order to express the density given to each pixel, it is possible to express the same density by referring to the mask applied in the mask data conversion process, and to arrange each other in the array. By selecting one from a plurality of different dot arrangement patterns, the final dot arrangement is determined. Thereby, the number of recording dots between each recording scan is allocated almost evenly between adjacent dots, within each pixel (within 300 dpi 1 pixel), and within a predetermined area (within 8 × 4 pixels), so that the density in each pixel can be set. Stabilization and density unevenness can be suppressed. In addition, the dot arrangement pattern is also created randomly on the spot according to the input data and mask pattern. Therefore, a unique texture or streak is generated compared to the case where the dot arrangement pattern is sequentially arranged according to a predetermined rule. There are few concerns.

  The second embodiment of the present invention will be described below. Also in the present embodiment, FIG. 4 can be applied to the image processing steps as in the first embodiment. In the dot arrangement patterning process J0007, a process of converting 300 dpi quinary data into 600 dpi binary data. Shall be performed. Further, the mask for four passes shown in FIG. 6 is applied to the mask pattern in the mask data processing as in the first embodiment.

  Furthermore, the process of selecting one of a plurality of arrangement patterns in the dot arrangement patterning process can also refer to the flowchart of FIG. 5 as in the first embodiment. However, in the present embodiment, the conditions that serve as guidelines when selecting in step S304 are slightly different from those in the first embodiment.

  Hereinafter, four conditions in the present embodiment will be described. The first condition is that the adjacent areas are recorded by printing scans that are as different as possible in the dot arrangement pattern (in one pixel of 300 dpi). The second condition is that dots recorded in the dot arrangement pattern (in one pixel of 300 dpi) are recorded by different recording scans. The third condition is that data is evenly allocated to even-numbered rasters and odd-numbered rasters. The raster indicates a series of areas arranged in the main scanning direction of the recording head. Even-numbered rasters are recorded by even-numbered nozzles and odd-numbered rasters are recorded by odd-numbered nozzles. That is, by satisfying the third condition, the number of ejections of the odd-numbered nozzle and the even-numbered nozzle can be made uniform. The fourth condition is that even between dot arrangement patterns (between 300 dpi pixels), adjacent areas are recorded by recording scans that are as different as possible. The priorities of the above four conditions are set in the order of conditions 1, 2, 3, and 4.

  Here, the purpose of evenly allocating data between the even raster and the odd raster will be described.

  FIG. 12 is a view showing one color ejection port array having an ink jet recording head applied in the present embodiment. In the figure, the horizontal direction indicates the recording scanning direction, and the vertical direction indicates the sub-scanning direction. One discharge port array is formed by arranging a plurality of discharge port arrays in the Y direction at a predetermined pitch Py. Further, such discharge port arrays are arranged at a distance of Px in the horizontal direction in a state where they are shifted from each other by Py / 2 in the vertical direction. By using the recording head having such a configuration, dots are recorded on the recording medium at a pitch of Py / 2 in the longitudinal direction by moving and scanning in the X direction while ejecting ink from each ejection port at a predetermined frequency. I can do it. That is, in the recording head, even if the ejection openings are not arranged in a line at the recording resolution pitch, the two lines arranged at a pitch twice the recording resolution are arranged so as to be shifted from each other by a half pitch, thereby achieving a desired recording resolution. This makes it possible to record the images. Such a configuration is applied to a recording head that achieves a particularly high recording resolution.

  In the above configuration, each of the two nozzle arrays is classified into a nozzle array (odd nozzle) for recording odd rasters and a print nozzle array (even nozzles) for even rasters. It has been confirmed that deviations in the number of recordings between the odd-numbered raster and the even-numbered raster cause a difference in ejection frequency between the odd-numbered nozzle row and the even-numbered nozzle row, which affects the ejection state between the nozzle rows. ing. In such a situation, the discharge state of the entire recording head also becomes unstable.

  Therefore, when applying the recording head configured as shown in FIG. 12, it is important to make the ejection frequency in each row as uniform as possible.

  FIG. 10 shows 8 areas in a state in which the dot arrangement pattern is determined according to the four conditions of this embodiment for each pixel of 300 dpi having the gradation value shown in FIG. 7 as in the first embodiment. 4 areas are shown. The input data shown in FIG. 7 and the mask pattern shown in FIG. 6 are the same as those in the first embodiment, but the applied conditions are different from those in the first embodiment. Different from that shown in FIG.

  FIG. 11 is a diagram showing a result of applying AND processing to the dot data FIG. 10 of the present embodiment using the masks 1 to 4 shown in FIG. In the first embodiment, the contents for equalizing the number of print data between the print scans are taken into consideration as the third and fourth conditions, but this is not a condition in the present embodiment. Therefore, the number of recording dots in each recording scan shown in FIG. 11 is not equal to 7 dots, 4 dots, 5 dots, and 4 dots from the first pass. However, referring to FIG. 9 again, in the first embodiment, the number of recording dots of the odd raster is 11 dots, the number of recording dots of the even raster is 9 dots, and the even raster and the odd raster are unequal. On the other hand, in the present embodiment, even-numbered rasters and odd-numbered rasters are equally distributed by 10 dots.

  As described above, in this embodiment, in order to express the density given to each pixel, it is possible to express the same density by referring to the mask applied in the mask data conversion process, and to arrange each other in the array. By selecting one from a plurality of different dot arrangement patterns, the final dot arrangement is determined. As a result, adjacent dots within each pixel (within 300 dpi per pixel) and between each pixel can be recorded by recording scans that are as different as possible, and at the same time, the number of recorded dots can be allocated almost evenly between even rasters and odd rasters. . Therefore, it is possible to stabilize the image quality by suppressing the blur between each area, and also to maintain the reliability of the recording head by stabilizing the ejection frequency between the even nozzle rows and the odd nozzle rows. It becomes.

  Although the two embodiments have been described above as examples, the present invention is not limited to these embodiments, and can be implemented in various forms without departing from the gist thereof. For example, in the dot arrangement patterning process of the above-described embodiment, 300 dpi 5-value input pixels are converted to 600 dpi binary data composed of 2 × 2 areas. However, the present invention is not limited to this form. Any dot arrangement pattern of any size may be prepared as long as it is a conversion process adaptable to the output resolution of the printing apparatus with respect to the gradation value and resolution of the output data after halftoning.

  In the above embodiment, the dot arrangement pattern is selected based on the four conditions in step S304, but this condition is not limited to four. It is also possible to determine priorities by combining various conditions according to the status of the recording system.

  Furthermore, in the above embodiment, the recording system including the host device and the recording device has been described with reference to FIG. 4, but the present invention is not limited to such a configuration. A system consisting of a plurality of devices (for example, a host computer, interface device, reader, printer, etc.) or a device consisting of a single device (for example, a copier, a facsimile device, etc.) The effects of the present invention can be obtained if the configuration includes dot arrangement patterning processing and mask data conversion processing in the processing.

  Another object of the present invention is to supply a storage medium storing software program codes for realizing the functions of the above-described embodiments to a system or apparatus, and the computer (or CPU or MPU) of the system or apparatus stores the storage medium. Needless to say, this can also be achieved by reading and executing the program code stored in. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the program itself or the storage medium storing the program code constitutes the present invention.

  As a storage medium for supplying the program code, for example, a floppy (registered trademark) disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD-R, magnetic tape, nonvolatile memory card, ROM, or the like is used. I can do it. Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also an OS (operating system) running on the computer based on the instruction of the program code. A case where part of actual processing is performed and the functions of the above-described embodiments are realized by the processing is also included.

  Further, after the program code read from the storage medium is written to a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, the function expansion is performed based on the instruction of the program code. This includes a case where the CPU or the like provided in the board or the function expansion unit performs part or all of the actual processing, and the functions of the above-described embodiments are realized by the processing.

  As another program supply method, a client computer browser is used to connect to an Internet homepage, and the computer program of the present invention itself or a compressed file including an automatic installation function is downloaded from the homepage to a recording medium such as a hard disk. Can also be supplied. It can also be realized by dividing the program code constituting the program of the present invention into a plurality of files and downloading each file from a different homepage. That is, a WWW server that allows a plurality of users to download a program file for realizing the functional processing of the present invention on a computer is also included in the scope of the present invention.

It is a schematic diagram for demonstrating a dot arrangement patterning process. FIG. 6 is a schematic diagram illustrating a recording head and a recording pattern when performing multi-pass recording. It is a schematic diagram for demonstrating the example of storing a mask pattern. It is a block diagram for demonstrating the flow of the image data conversion process in the inkjet recording system of embodiment applicable to this invention. It is a flow chart for explaining the process of selecting one of a plurality of arrangement patterns by referring to a mask pattern. (A) And (b) is the figure which showed an example of the mask pattern applied by embodiment of this invention. It is the figure which showed the example of the gradation value of each pixel input into a dot arrangement patterning process. It is the figure which showed the dot arrangement pattern determined corresponding to each pixel according to the flowchart shown in FIG. It is the figure which showed the result of having performed the AND process using the mask of FIG. 6 with respect to the created dot data. It is the figure which showed the area | region of 8 area x 4 area of the state in which the dot arrangement pattern was determined. It is the figure which showed the result of having performed the AND process using the mask of FIG. 6 with respect to the created dot data. FIG. 6 is a diagram illustrating a one-color ejection port array having an ink jet recording head applied in a second embodiment of the present invention.

Explanation of symbols

101, 102, 103 Dot arrangement pattern 512 to 519 One pixel area of 300 dpi 601 to 608 Selected dot arrangement pattern 801 to 808 Selected dot arrangement pattern J0001 Application J0002 First stage J0003 Second stage J0004 γ correction J0005 Halftoning J0006 Creation J0007 Dot arrangement patterning process J0008 Mask data conversion process J0009 Head drive circuit J0010 Recording head

Claims (9)

A recording main scan using a recording head having a plurality of recording elements arranged at a density corresponding to the recording resolution P, and ejecting ink from the plurality of recording elements while scanning the recording head in a predetermined direction; In an ink jet recording apparatus in which an image is formed by performing sub-scanning for transporting a recording medium in a direction intersecting with scanning and arranging dots formed on the recording medium at a resolution P.
Dot arrangement means for converting image data having a multi-value level L (L> 2) at a resolution K (K <P) into binary image data in which a dot recording position is determined at the recording resolution P;
Binary image data obtained from the dot arrangement means and a predetermined mask pattern so that an image to be recorded in the same image area of the recording medium is completed in stages by the plurality of recording main scans. And generating means for generating ink ejection / non-ejection data in each printing scan for each of the printing elements,
Recording means for ejecting ink from the plurality of recording elements in accordance with ink ejection / non-ejection data generated by the generating means,
The dot placement means determines the dot recording position at the recording resolution P by referring to the mask pattern.   The dot arrangement means refers to the mask pattern for each of the image data having a resolution K (K <P) and a multi-level L (L> 2), so that the dot arrangement in the M × N matrix is performed. 2. The ink jet recording apparatus according to claim 1, wherein one is selected from a plurality of dot arrangement patterns whose arrangement is determined.   The dot arrangement means refers to the mask pattern so that a plurality of dots included in the M × N matrix are recorded by the different recording main scans. The inkjet recording apparatus according to claim 2, wherein one is selected.   The dot placement means refers to the recording pattern by referring to the mask pattern so that images in the same image area are completed step by step by a plurality of recording main scans in which approximately the same number of dots are recorded. The ink jet recording apparatus according to claim 1, wherein a recording position of dots at a resolution P is determined.   The recording head has a plurality of recording element arrays each composed of a plurality of recording elements, and the dot placement means is configured to use the mask pattern so that the ejection frequency between the plurality of recording element arrays is substantially equal. The inkjet recording apparatus according to claim 1, wherein a dot recording position at the recording resolution P is determined by referring to FIG.   3. The inkjet according to 1 or 2, wherein the dot arrangement unit determines a dot recording position at the recording resolution P based on the reference to the mask pattern and a plurality of prioritized conditions. Recording device. A recording main scan that uses a recording head having a plurality of recording elements arranged at a density corresponding to the recording resolution P, ejects ink from the plurality of recording elements while moving and scanning the recording head in a predetermined direction, and the recording In the ink jet recording method in which an image is formed by performing sub-scanning in which a recording medium is conveyed in a direction crossing main scanning, and dots formed on the recording medium are arranged at a resolution P.
A dot arrangement step of converting image data having a multilevel L (L> 2) at a resolution K (K <P) into binary image data in which a dot recording position is determined at the recording resolution P;
Binary image data obtained in the dot placement step and a predetermined mask pattern so that an image to be recorded in the same image area of the recording medium is completed in stages by the plurality of recording main scans. A generating step of generating ink ejection / non-ejection data in each printing scan for each of the printing elements by taking a logical product with
A recording step of ejecting ink from the plurality of recording elements in accordance with ink ejection / non-ejection data generated in the generation step,
In the ink jet recording method, the dot placement step determines a dot recording position at the recording resolution P by referring to the mask pattern. A recording main scan that uses a recording head having a plurality of recording elements arranged at a density corresponding to the recording resolution P, ejects ink from the plurality of recording elements while moving and scanning the recording head in a predetermined direction, and the recording Data for generating data used in an ink jet recording apparatus in which an image is formed by performing sub-scanning for transporting a recording medium in a direction crossing main scanning and arranging dots formed on the recording medium at resolution P A generating device,
Dot arrangement means for converting image data having a multi-value level L (L> 2) at a resolution K (K <P) into binary image data in which a dot recording position is determined at the recording resolution P;
Binary image data obtained from the dot arrangement means and a predetermined mask pattern so that an image to be recorded in the same image area of the recording medium is completed in stages by the plurality of recording main scans. And generating means for generating ink ejection / non-ejection data in each printing scan for each of the printing elements,
The dot generation means determines a dot recording position at the recording resolution P by referring to the mask pattern. A recording main scan that uses a recording head having a plurality of recording elements arranged at a density corresponding to the recording resolution P, ejects ink from the plurality of recording elements while moving and scanning the recording head in a predetermined direction, and the recording In order to generate data used in an ink jet recording apparatus in which an image is formed by performing sub-scanning that transports a recording medium in a direction crossing main scanning and arranging dots formed on the recording medium at a resolution P The program of
By referring to a mask pattern used to complete an image to be recorded in the same image area of the recording medium in stages by a plurality of recording main scans, a multilevel L (with a resolution K (K <P)) A first step of converting image data having L> 2) into binary image data in which a dot recording position is determined at a recording resolution P;
The logic of the binary image data obtained in the first step and the mask pattern so that an image to be recorded in the same image area of the recording medium is completed in stages by a plurality of recording main scans. A second step of generating ink ejection / non-ejection data in each printing scan for each of the printing elements by taking a product;
A program that causes a computer to execute.

Images