JP2014144537A - Ink jet recording device and ink jet recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet recording device in which even when the multipath number m is not a multiple of the number of the column thinning n, the number of discharge of each domain in a recording head is made as equal as possible, and the image defects can be mitigated which is due to generation of an air current.SOLUTION: In a dot arrangement pattern which corresponds with the level value of an image data and determines recording or non-recording of the dot, a different pattern is set up for every unit domain such that the number of discharge per every unit domain of the recording head is not exceed a predetermined number of times. Thereby, the number of discharge in each domain of the recording head is made uniform, and the image defects can be mitigated which is due to generation of an air current.

Description

  The present invention relates to a serial type ink jet recording apparatus and a recording method thereof. In particular, the present invention relates to a recording method when using both column thinning and multi-pass recording.

  In a serial type ink jet recording apparatus, an image is recorded with a predetermined resolution by moving a recording head having a plurality of recording elements for ejecting ink at a constant speed relative to a recording medium. In such an ink jet recording head, an optimum driving frequency for normally ejecting ink from a recording element and an appropriate moving speed of a carriage on which the recording head is mounted are usually set in advance. However, when the image recording resolution is high or when a given power supply capacity is small, there is a case where the driving frequency and the carriage speed cannot be matched.

  Patent Document 1 and Patent Document 2 disclose column thinning methods that can solve the above problems. In the column thinning, the recording for all the pixels is completed by performing scanning n times to record a plurality of pixels arranged in the moving direction of the recording head every n pixels (every n columns). In this way, since it is only necessary to record dots at a cycle of n pixels in one recording scan, it is possible to suppress the driving frequency of the recording head, power consumption per unit time, and improve the carriage speed. I can do it. That is, by appropriately setting the value of n, it is possible to adjust the driving frequency, carriage movement speed, power consumption per unit, and the like to an appropriate range.

  In addition, in the ink jet recording apparatus, a multipass recording method is useful in addition to the column thinning. The multi-pass recording method is a recording method in which an area that can be recorded by one recording scan by the recording head is recorded stepwise by m recording scans. More specifically, the unit region is obtained by repeating the recording scan according to the mask pattern in which the recording is permitted or not permitted for each pixel and the transport operation of the recording medium at a distance shorter than the recording width of the recording head. Are recorded stepwise by m recording scans. In such multi-pass printing, a line that can be printed by one printing element can be shared and printed by a plurality of printing elements, so that there is a single line of discharge characteristics of each printing element and a connecting stripe that occurs between printing scans. The image quality can be improved without being concentrated.

  In recent years, in order to obtain both the above-described column thinning effect and multipass recording effect, a recording method using both of them has been put into practical use.

  FIGS. 1A and 1B are diagrams showing a case where an image is recorded while using two-column thinning (n = 2) and 4-pass multi-pass printing (m = 4). Here, for simplicity, the case where the recording head 1 has 16 recording elements is shown. In FIG. 1A, each square indicates one pixel area, and the recording data 10 indicates a state in which one dot is recorded (black) for all pixels.

  In the mask pattern 11, an allowable pixel (black) that allows dot recording on each recording element of the recording head 1 and a non-permissible pixel (white) that is not allowed are defined. In the case of 4-pass multi-pass printing, the printing element of the printing head can be considered divided into four areas, and in the areas A to D, the ratio of printing allowable pixels is 50%.

  In the column thinning patterns 12a and 12b, a column (black) to be recorded in the scanning and a column (white) not to be recorded are determined, and these two patterns are alternately switched every recording scan. In the odd scan, the column thinning pattern 12a is set, and only the odd columns are recorded, and in the even scan, the column thinning pattern 12b is set, and only the even columns are recorded.

  When actual recording scanning is performed, the recording head 1 records dots according to the logical product of the recording data 10, the mask pattern 11, and the set column thinning pattern 12a (or 12b). As a result, dots are recorded according to the dot pattern 13a in the odd scan, and dots are recorded according to the dot pattern 13b in the even scan.

  FIG. 1B is a diagram illustrating a state in which an image is formed by repeating the recording scan of the recording head 1 and the conveying operation of the recording medium according to the dot pattern 13a and the dot pattern 13b. The dot patterns 14a to 14f indicate the dot patterns in the individual scans and their relative positions.

  When attention is paid to the image area X of the recording medium, dots are recorded in the order of the area D of the dot pattern 14a, the area C of the dot pattern 14b, the area B of the dot pattern 14c, and the area A of the dot pattern 14d. A 100% image Xi is completed. When attention is paid to the image area Y that is continuous with this, dots are recorded in the order of the area D of the dot pattern 14b, the area C of the dot pattern 14c, the area B of the dot pattern 14d, and the area A of the dot pattern 14e. 100% of the image Yi is completed.

  As described above, even when column thinning and multi-pass recording are used in combination, normal recording can be performed while obtaining the respective effects. In other words, when column thinning and multi-pass printing are used together, an appropriate mask pattern 11 is prepared in advance so that such printing can be performed normally.

  In the case shown in FIGS. 1A and 1B, the area A and the area C need to have a complementary relationship with each other with a recording allowance of 50%, and the areas B and D are also recorded respectively. It is necessary to have a complementary relationship with an allowable rate of 50%. As described above, when the column thinning and the multi-pass printing are used in combination, the mask pattern needs to have a 100% complementary relationship between a plurality of areas in which the same column is recorded. Therefore, in order to make the recording allowance ratios of the respective areas equal as in general multi-pass recording, it is desirable that the multi-pass number m is a multiple of the column thinning number n.

  FIGS. 2A and 2B are diagrams showing the recording allowance rates of individual areas when such a condition is satisfied. FIG. 2A shows a case where 4-pass multi-pass printing is performed by two-column thinning as described in FIGS. 1A and 1B. The multipass number m = 4 is a multiple of the column thinning number n = 2, and the recording allowance of each area is 50%. On the other hand, FIG. 2B shows a case where 4-pass multi-pass printing is performed with 4-column thinning. The multipass number m = 4 is a multiple of the column thinning number n = 4. In this case, since each of the areas A to D records a different column, the recording allowable rate is 100% in all the areas.

JP 2002-29097 A JP 2004-1560 A

  However, in recent years, the use of output materials and the types of recording media have been diversified, and recording apparatuses have been required to have recording modes corresponding to various conditions. Under such circumstances, even if it is necessary to use both column thinning and multipass printing, depending on the required image quality and throughput, a recording method in which the multipass number m is always a multiple of the column thinning number n is appropriate. It may not be.

  However, even if the multi-pass number m is not a multiple of the column thinning number n, if a mask pattern having a 100% complementary relationship between a plurality of areas that record the same column is prepared, the complementary relationship Is maintained and normal recording can be performed. However, in this case, since the number of scans required to complete the recording of each column data differs between columns, the recording allowable ratio of each area of the mask pattern cannot be made uniform.

  On the other hand, in the situation where the size and density of ink droplets are being promoted for higher image quality as in recent years, an air current is generated between the recording medium and the recording head, and this air current is generated by the dots. It may affect the landing position. It has been confirmed that such airflow is likely to appear when a large number of small droplets are ejected at high frequency and high density. Therefore, in multi-pass printing, it is desirable to make the number of ejections as uniform as possible in the entire region in order to prevent the region ejected with high frequency and high density from appearing.

  That is, when the multipass number m is not a multiple of the column thinning number n, it is difficult to avoid the adverse effects of the image due to the airflow when the recording allowable ratio of each area of the mask pattern cannot be made uniform.

  The present invention has been made to solve the above problems. Therefore, even if the multipass number m is not a multiple of the column thinning number n, the purpose is to make the number of ejections of each area in the recording head as uniform as possible and to mitigate image problems caused by the generation of airflow. It is an object of the present invention to provide an ink jet recording apparatus capable of performing the above.

  To this end, the present invention provides a recording scan in which a recording head in which a plurality of recording elements that eject ink are arranged in a first direction is moved in a second direction that intersects the first direction; By alternately performing a transport operation for transporting a recording medium in one direction, and performing m recording scans in each of m regions obtained by dividing a plurality of the recording elements into m in the first direction, An inkjet recording apparatus that records a unit area of the recording medium, wherein dot recording and non-recording with respect to each pixel is performed by referring to a dot arrangement pattern determined in association with a level value of image data. Dot arrangement patterning means for converting the image data of the area into binary dot data, the dot data, and a dot for each pixel of the plurality of printing elements in the printing scan. Means for generating print data of each print scan by logical product with a mask pattern in which the print allowance and non-allowance of print are determined, and the print data in n columns (n is 2 or more) in the second direction. (N × n) column, (N × n + 1) column,... (N × n + (n−1)) column ( N is a positive integer), so that the recording medium is executed by different recording scans, and each time the recording scan is completed, the recording medium is moved to the first area by a distance corresponding to the width of the unit area. And m is an integer that is larger than n and not a multiple, and the dot arrangement patterning unit is configured so that the recording head performs recording in each recording scan. Vomiting As the number does not exceed the predetermined number, and sets the dot arrangement pattern different for each of the unit areas.

  According to the present invention, even if the multi-pass number m is not a multiple of the column thinning number n, by preparing an appropriate mask pattern and dot arrangement pattern, the number of ejections can be made uniform in each area of the recording head, It is possible to mitigate image damage caused by the occurrence.

(A) And (b) is the figure which showed the case where an image is recorded, using two-column thinning and 4-pass multipass printing together. (A) And (b) is the figure which showed the recording tolerance of each area | region of a recording head. It is a perspective view for demonstrating the structure of the recording part of an inkjet recording device. It is a block diagram for demonstrating the structure of control in a recording device. It is a block diagram for demonstrating the flow of an image data conversion process. It is a figure which shows the conventional common dot arrangement pattern. (A) And (b) is the figure which showed the mask pattern and the recording tolerance. (A) And (b) is the figure which showed the state which records an image, using 2 column thinning | decimation and 5-pass multipass printing together. It is a figure which shows the dot arrangement pattern referred in 1st Embodiment. (A) And (b) is the figure which showed the recording state of 1st Embodiment. (A) And (b) is the figure which showed the recording state of the conventional method. (A) And (b) is a figure which shows the mask pattern and recording tolerance of 1st Embodiment. (A) And (b) is the figure which showed the state which records an image, using 4 column thinning | decimation and 7-pass multipass printing together. (A) And (b) is a dot arrangement pattern figure which can be used in a 2nd embodiment. (A) And (b) is the figure which showed the recording state of 2nd Embodiment. (A) And (b) is a comparison figure of 2nd Embodiment.

(First embodiment)
FIG. 3 is a perspective view for explaining a configuration of a recording unit of a color ink jet recording apparatus 100 (hereinafter also simply referred to as a recording apparatus) applicable in the present invention. The ink tanks 205 to 208 contain black (K), cyan (C), magenta (M), and yellow (Y) inks, and supply the ink to the corresponding recording heads 201 to 204. . In each of the recording heads 201 to 204, a plurality of recording elements for ejecting ink according to image data are arranged in the Y direction (first direction).

  The conveyance roller 103 rotates together with the auxiliary roller 104 while sandwiching the recording medium (recording paper) 107 to convey the recording medium 107 in the Y direction, and also has a role of holding the recording medium 107. The carriage 106 is configured to be capable of reciprocating in the X direction (second direction) intersecting the Y direction with the ink tanks 205 to 208 and the recording heads 201 to 204 mounted thereon. At a timing when the recording heads 201 to 204 are not performing a recording operation, the carriage 106 is controlled to stand by at a home position h indicated by a dotted line in the drawing.

  When a recording command is input, the carriage 106 waiting at the home position h moves in the X direction in the figure, and the recording head discharges ink according to the recording data while the carriage 106 is moving, thereby recording medium An image for one scan is recorded in 107. When such one recording scan is completed, the transport roller 103 rotates and transports the recording medium 107 in the Y direction by a distance corresponding to the recording width of the recording head. Images are sequentially formed on the recording medium 107 by alternately repeating the recording scanning by the recording head and the conveying operation of the recording medium. The recording scan may be performed only by the forward scan in the X direction, or may be performed by both the forward scan and the backward scan.

  FIG. 4 is a block diagram for explaining a control configuration in the recording apparatus 100 shown in FIG. The recording device 100 is connected to a data supply device such as a host device 1200 via an interface 400. Various data transmitted from the data supply device, control signals related to recording, and the like are input to the recording control unit 500 of the recording device 100. The recording control unit 500 has a CPU 500b (which may be an ASIC) as a calculation means in addition to a memory 500a for storing a control program, a mask pattern to be described later, and the like, and motor drivers 403 and 404 and a head driver according to an input control signal. 405 is controlled. The recording control unit 500 also performs processing of input image data, processing of a signal input from a head type signal generation circuit 405 described later, and the like.

  The motor driver 403 drives the carry motor 401 to rotate the carry roller 103. The motor driver 404 drives the carriage motor 402 to reciprocate the carriage 106 in the X direction. The head driver 405 is a driver for driving individual recording elements in the recording heads 201 to 204, and a plurality of head drivers 405 are provided corresponding to the number of recording heads.

  FIG. 5 is a block diagram for explaining the flow of image data conversion processing in the present embodiment. Each process illustrated in FIG. 5 is configured by the recording apparatus 100 and the host apparatus 1200.

  There are applications and printer drivers as programs that operate in the operating system of the host device, and the application J01 creates image data to be recorded by the recording device. At the time of actual recording, image data having a resolution of 600 ppi created by the application is passed to the printer driver.

  As the process, the printer driver executes a pre-stage process J02, a post-stage process J03, a γ correction J04, a halftoning J05, and a print data creation process J06. Here, each process will be briefly described. The pre-stage process J02 performs color gamut mapping, and the color gamut reproduced by the image data R, G, B of the sRGB standard is reproduced by the recording apparatus. Conversion into R, G, B data for mapping within the color gamut. Specifically, data in which R, G, and B are each expressed in 8 bits is converted into 8-bit data of R, G, and B having different contents by using a three-dimensional LUT.

  The post-stage process J03 is a process for obtaining the color separation data C, M, Y, K corresponding to the combination of inks that reproduce the color represented by the data R, G, B based on the data R, G, B on which the color gamut is mapped. I 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 J04 performs gradation value conversion for each color data of the color separation data obtained by the post-processing J03. 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.

  The following processing is performed for each recording color of the recording apparatus. In this embodiment, since the recording apparatus has four recording colors C, M, Y, and K, four processes are performed in order four times or in parallel.

  Halftoning J05 performs a process of quantizing 600 ppi 8-bit CMYK data into 600 ppi 4-bit CMYK data. In the present embodiment, multi-valued error diffusion is used to convert 600-ppi 256-gradation 8-bit data into 600-ppi 9-gradation 4-bit data. 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 4-bit CMYK data by print data creation processing J06.

  The recording apparatus 100 that has received the print data performs a dot arrangement patterning process J07 and a mask data conversion process J08 on the received CMYK data. In this embodiment, the dot arrangement patterning process and the mask data conversion process are executed under the control of a CPU that constitutes a control unit of the printing apparatus using a dedicated hardware circuit for the dot arrangement patterning process and the mask data conversion process.

  The dot arrangement patterning process J07 in the present embodiment will be described below. In the halftoning described above, the number of levels is reduced from 256-value multi-value density information (8-bit data) of 600 ppi to 9-value gradation value information (4-bit data). However, information that can be actually recorded by the ink jet recording apparatus of the present embodiment is binary information indicating whether or not to record ink. In the dot arrangement patterning process, it plays a role of reducing the multi-value level of 0 to 8 to a binary level that determines the presence or absence of dots. Specifically, dot recording (1) or non-recording (0) for each pixel corresponds to a level from among a plurality of dot arrangement patterns prepared in association with levels 0 to 8, respectively. One dot arrangement pattern is selected. This is output as binary dot data corresponding to the recording resolution.

  FIG. 6 is a diagram showing a conventional general dot arrangement pattern referred to in the dot arrangement patterning process j07. Level 0 to level 8 shown on the left of the figure indicate level values output from the halftoning J05. On the other hand, each area composed of 2 vertical areas × 4 horizontal areas arranged on the right side corresponds to one pixel area of 600 ppi (pixels / inch) after halftoning. Each area of 2 × 4 corresponds to a minimum unit in which recording or non-recording of dots is defined in the recording apparatus, and corresponds to 1200 dpi (dots / inch) in the vertical direction and 2400 dpi in the horizontal direction. One such area has an area of about 20 μm in length and about 10 μm in width, and one 4 pl ink droplet is recorded in each area, so that the paper surface is sufficiently filled with dots. ing.

  In FIG. 6, the Y direction is the direction in which the ejection openings of the recording head are arranged, and the arrangement density of the areas and the arrangement density of the ejection openings coincide with each other at a value of 1200 dpi. The X direction indicates the scanning direction of the recording head, and in this embodiment, the recording head records dots at a density of 2400 dpi. In the figure, the area filled with a circle indicates the area where dots are recorded, and as the number of levels increases, the number of dots to be recorded increases by one. (4K) to (4K + 3) indicate pixel positions in the horizontal direction from the left end of the input image by substituting an integer of 0 or more for K. Each of the patterns shown below indicates that a plurality of different patterns are prepared according to the pixel position even at the same input level. That is, even when the same level is input, four types of dot arrangement patterns shown in (4K) to (4K + 3) are cyclically assigned on the recording medium. In addition, such a configuration has various effects such as distributing the number of ejections between the nozzles located in the upper stage and the nozzles located in the lower stage of the dot arrangement pattern and various noises peculiar to the printing apparatus. Effects can be obtained.

  In the present embodiment, the density information of the original image is finally reflected in such a form, and the dot arrangement to be recorded on the recording medium is determined when the dot arrangement patterning process is completed.

  Next, the mask data conversion process J08 in this embodiment will be described. In the mask data conversion process J08, a logical product operation is performed between the dot data output from the dot arrangement patterning process J07 and a mask pattern prepared in advance to generate binary print data in the multipass print scan. To do. The mask pattern in this embodiment will be described in detail later.

  The binary data output from the mask data conversion process J08 is sent to the head driver J09, and ejection data is generated for each printing scan according to a predetermined column thinning drive. Thereafter, the recording head J10 performs an ejection operation according to the ejection data divided for each column in this way, and records an image of each scan.

  Hereinafter, multi-pass printing using column thinning according to the present embodiment will be described. In this embodiment, the column thinning number n = 2 and the multipath number m = 5. That is, the multipath number m is not a multiple of the column thinning number n.

  FIGS. 7A and 7B are diagrams showing the mask pattern used in the present embodiment and the recording allowance for each area. In the mask pattern of FIG. 7A, the allowed pixels that allow dot recording are shown in black, and the non-permitted pixels that are not allowed are shown in white. In the case of 5-pass multi-pass printing, the printing element of the printing head can be divided into m divided areas, that is, divided into five areas A to E, and the unit area of the printing medium is divided into areas A to E. An image is completed by five (m) recording scans.

  In this embodiment, since the odd-numbered column recording scan and the even-numbered column recording scan are alternately performed, if the odd-numbered column of the unit area is recorded in the areas A, C, and E, the even-numbered column of the unit area is the area B. And recorded in area D. On the contrary, if even-numbered columns in the unit area are recorded in the areas A, C, and E, the odd-numbered columns in the unit area are recorded in the areas B and D. As described above, since the recording of one column is completed by the combination of the area A, the area C, and the area E, the mask patterns in these areas have a complementary relationship with each other, and the sum of the recording allowances is 100%. It is necessary. On the other hand, the areas B and D are also required to have a complementary relationship with each other and have a sum of recording allowances of 100%.

  In this example, as shown in FIG. 7A, the arrangement of the print permitting pixels maintains a complementary relationship for each of the combination of region A, region C and region E, and combination of region B and region D. Further, as shown in FIG. 7B, the recording allowance ratios of the areas A to E are 33%, 50%, 33%, 50%, and 33%, and the areas A, C, and E The combination of the recording allowances is 100% both in the combination of regions B and D.

  8A and 8B show the recording state in this embodiment in which an image is recorded while using two-column thinning (n = 2) and 5-pass multi-pass printing (m = 5) in the same manner as in FIG. It is the figure shown in. The mask pattern 81 is equivalent to the mask pattern shown in FIG.

  When performing actual recording scanning, the recording head records dots according to the result of the logical product of the recording data 80, the mask pattern 81, and the set column thinning pattern 83a (or 83b). As a result, dots are recorded according to the dot pattern 83a in the odd scan, and dots are recorded according to the dot pattern 83b in the even scan.

  FIG. 8B is a diagram illustrating a state in which an image is formed by repeating the recording scan of the recording head 1 and the conveying operation of the recording medium according to the dot pattern 83a and the dot pattern 83b. The dot patterns 84a to 84f indicate the dot patterns in the individual scans and their relative positions.

  When attention is paid to the image area X of the recording medium, this area includes an area E of the dot pattern 84a, an area D of the dot pattern 84b, an area C of the dot pattern 84c, an area B of the dot pattern 84d, an area A of the dot pattern 84e, Dots are recorded in this order. As a result, 100% of the image Xi is completed. When attention is paid to the image area Y that is continuous with this, this area includes the area E of the dot pattern 84b, the area D of the dot pattern 84c, the area C of the dot pattern 84d, the area B of the dot pattern 84e, and the area A of the dot pattern 84f. Dots are recorded in this order. As a result, 100% of the image Yi is completed.

  As described above, even when the multipass number m is not a multiple of the column thinning number n, a mask pattern having a 100% complementary relationship between a plurality of areas that record the same column as in this embodiment. By using this, normal recording can be performed.

  However, as described in the section of the problem, in the situation where the droplet size and the density of the ink droplets are promoted in order to further improve the image quality, in the regions B and D where the recording allowance rate is relatively high. There is concern about the generation of air current. Specifically, referring again to FIG. 7 (b), the recording allowances of areas A, C, and E are 33%, whereas the recording allowances of areas B and D are as high as 50%. The number of ejections in each printing scan is also greater in regions B and D than regions A, C, and E, and airflow is likely to occur.

  However, even if such a recording position shift occurs, if the image density is sufficiently low such that the dot arrangement is sparse, or if the image density is sufficiently high such that adjacent dots overlap, No white streak is seen at the border. Such white streaks are easily confirmed at an image density of about 50% duty whether or not the paper surface is just covered with dots. In the case of the recording apparatus of the present embodiment, the density of level 4 in the dot arrangement pattern shown in FIG. 6 corresponds to a density of about 50% duty where white lines are most noticeable.

  In the present embodiment, in order to avoid such white stripes, a characteristic dot arrangement pattern is prepared so that there is no region where the number of ejections is particularly large.

  FIG. 9 is a diagram showing a dot arrangement pattern referred to in the dot arrangement patterning process J07 in the present embodiment. Also in this embodiment, basically, the dot arrangement pattern shown in FIG. 6 is used. However, a special dot arrangement pattern as shown in FIG. 9 is used for level 4 that is most likely to be affected by airflow fluctuations.

  In the present embodiment, group A and group B are prepared as dot arrangement patterns used at level 4. Comparing these, in group A, the number of dots in odd columns is set smaller than that in even columns, whereas in group B, the number of dots in even columns is set smaller than in odd columns.

  If an odd column is recorded in each unit area by a recording allowance of 33% by area A, area C and area E, an even column in that unit area has a recording allowance ratio of 50% by area B and area D. Is recorded. That is, there is a concern that the unit area has airflow in an area where even columns are recorded. Therefore, in this embodiment, for such a unit region, dot arrangement pattern processing is executed using the B group dot arrangement pattern in order to reduce even-numbered column dots.

  On the other hand, in the unit area where even columns are recorded by the areas A, C and E at a recording allowance of 33%, the odd columns are recorded by the areas B and D at a recording allowance ratio of 50%. That is, there is a concern that the unit area may have airflow in an area where odd columns are recorded. Therefore, for such a unit area, in order to reduce the number of odd-numbered columns, dot arrangement pattern processing is executed using the dot arrangement pattern of group A.

  FIGS. 10A and 10B are views showing the recording state at level 4 of the present embodiment using the dot arrangement pattern shown in FIG. 9 as in FIG. FIGS. 11A and 11B are diagrams showing a recording state at level 4 when the dot arrangement pattern shown in FIG. 6 is used.

  In the present embodiment, since the image data (level 4) is converted according to the dot arrangement pattern shown in FIG. 9, the print data 20 is obtained in the dot arrangement patterning process. On the other hand, when the image data (level 4) is converted according to the dot arrangement pattern shown in FIG.

  Mask patterns 21 and 31 are the mask patterns shown in FIGS. 7A and 7B. Also, the column thinning patterns 22a and 22b and the column thinning patterns 32a and 32b are equivalent to the column thinning patterns 12a and 12b shown in the first embodiment.

  Referring to FIG. 10A, when actual print scanning is performed in the present embodiment, the print head performs a logical product result of the print data 20, the mask pattern 21, and the set column thinning pattern 22a (or 22b). Follow the steps to record dots. As a result, dots are recorded according to the dot pattern 23a in the odd scan, and dots are recorded according to the dot pattern 23b in the even scan.

  On the other hand, referring to FIG. 11A, when performing an actual recording scan using the dot arrangement pattern of FIG. 6, the recording head uses the recording data 30, the mask pattern 31, and the set column thinning pattern 32a (or According to the result of the logical product of 32b), dots are recorded. As a result, dots are recorded according to the dot pattern 33a in the odd scan, and dots are recorded according to the dot pattern 33b in the even scan.

  Here, the dot pattern 23a for odd scanning and the dot pattern 23b for even scanning in this embodiment are compared with the dot pattern 33a for odd scanning and the dot pattern 33b for even scanning when the dot arrangement pattern of FIG. 6 is used.

  When the dot arrangement pattern of FIG. 6 is used, it can be seen that the number of dots in the region B and the region D is larger than the number of dots in the other regions in both the odd-scan dot pattern 33a and the even-scan dot pattern 33b. . This is because, in the dot arrangement pattern of FIG. 6, the print data is evenly distributed to the odd-numbered columns and even-numbered columns, so that the mask pattern print allowance in each area is directly reflected in the number of print dots in each area. This is because that.

  On the other hand, in the case of the present embodiment, it can be seen that the number of dots in each region is substantially equal in both the odd-scan dot pattern 23a and the even-scan dot pattern 23b. This is because, for each unit area, the recording data distributed to the columns recorded in the areas B and D having a high recording allowance rate is suppressed, and the corresponding recording data is recorded in the areas A, C, and E. This is because a dot arrangement pattern that is distributed among the two is set.

  Describing with reference to FIG. 10B, for the image region X, even columns are recorded in regions B and D having a high recording allowance rate. Therefore, the dot arrangement patterning process using the B group dot arrangement pattern in which the print data of even-numbered columns is suppressed to be small is performed on the image region X. As a result, even if the recording allowance ratio of the mask patterns in the areas B and D of the recording head is higher than those in the areas A, C and E, these areas are not obtained in the dot pattern obtained from the logical product of the dot arrangement pattern and the mask pattern. The number of discharges can be made almost uniform.

  On the other hand, for the image area Y adjacent to the image area X, since the odd columns are recorded in the areas B and D of the recording head, the dots of the A group in which the recording data of the odd columns are suppressed in the image area Y are small. A dot arrangement patterning process using the arrangement pattern is performed. As a result, the number of ejections can be made substantially uniform between the regions A, C, and E and the regions B and D in the region.

  As described above, according to the present embodiment, even if the multipass number m is not a multiple of the column thinning number n, the number of times of ejection in each area of the print head is prepared by preparing an appropriate mask pattern and dot arrangement pattern. Can be made uniform, and the adverse effects of the image due to the generation of airflow can be reduced.

(Second Embodiment)
Also in the present embodiment, as in the first embodiment, the image processing shown in FIG. 5 is executed using the ink jet recording apparatus shown in FIGS. In the first embodiment, the case where the column thinning number n = 2 and the multipath number m = 5 has been described, but in this embodiment, the case where the column thinning number n = 4 and the multipass number m = 7 will be described. Also in this embodiment, the multipass number m is not a multiple of the column thinning number n.

  FIGS. 12A and 12B are diagrams showing the mask pattern used in this embodiment and the recording allowance for each area in the same manner as FIGS. 7A and 7B. In the case of 7-pass multi-pass printing, the printing element of the printing head can be divided into seven areas A to G, and the unit area of the printing medium is an image formed by seven printing scans in the areas A to G. Completed.

  In this embodiment, since 4 columns are thinned out, if the 4N column of the unit area is recorded in the areas A and E, the (4N + 1) column of the unit area is recorded as the areas B and F, and the (4N + 2) column is recorded. Are recorded in areas C and G, and the (4N + 3) column is recorded in area D. If the (4N + 1) column of the unit area is recorded in the areas A and E, the (4N + 2) column of the unit area is recorded in the areas B and F, the (4N + 3) column is recorded in the areas C and G, The 4N column is recorded in area D. If the (4N + 2) column of the unit area is recorded as areas A and E, the (4N + 3) column of the unit area is recorded as areas B and F, the 4N column is recorded as areas C and G, and (4N + 1) ) The column is recorded in area D. Further, if the (4N + 3) column of the unit area is recorded in the areas A and E, the 4N column of the unit area is recorded in the areas B and F, the (4N + 1) column is recorded in the areas C and G, and (4N + 2 ) The column is recorded in area D.

  In this way, in each unit area, three of the 4N to (4N + 3) columns are recorded by any combination of area A and area E, area B and area F, and area C and area G. One column is recorded only by the area D. Therefore, for each combination of region A and region E, region B and region F, region C and region G, a mask pattern is required which has a complementary relationship with each other and the sum of recording allowances is 100%. For D, a mask pattern having a recording allowance rate of 100% is required.

  FIGS. 13A and 13B are diagrams showing a recording state in the present embodiment in which an image is recorded while using 4-column thinning (n = 4) and 7-pass multi-pass recording (m = 7) in combination. is there. The mask pattern 131 is the mask pattern shown in FIG.

  When performing actual recording scanning, the recording head records dots according to the result of the logical product of the recording data 130, the mask pattern 131, and any of the set column thinning patterns 132a to 132d. As a result, dots are recorded in accordance with the dot pattern 133a in (4N + 1) scanning, in accordance with the dot pattern 133b in (4N + 2) scanning, in accordance with the dot pattern 133c in (4N + 3) scanning, and in accordance with the dot pattern 133d in 4N scanning.

  FIG. 13B is a diagram illustrating a state in which an image is formed by repeating each recording scan of the recording head and the conveyance operation of the recording medium according to the dot patterns 133a to 133d. The dot patterns 134a to 134h indicate the dot patterns in the individual scans and their relative positions.

  Here, attention is paid to the image region X. In this area, dots G are arranged in the order of the area G of the pattern 134a, the area F of the pattern 134b, the area E of the pattern 134c, the area D of the pattern 134d, the area C of the pattern 134e, the area B of the pattern 134f, and the area A of the pattern 134g. It is recorded. As a result, a 100% image Xi is completed. Further, attention is paid to an image area Y that is continuous with the image area Y. In this area, dots G are arranged in the order of the area G of the pattern 134b, the area F of the pattern 134c, the area E of the pattern 134d, the area D of the pattern 134e, the area C of the pattern 134f, the area B of the pattern 134g, and the area A of the pattern 134h. It is recorded. As a result, a 100% image Yi is completed.

  As described above, according to the present embodiment, even when the multipass number m = 7 column thinning number n = 4, a mask having a 100% complementary relationship between a plurality of areas in which the same column is recorded. By using the pattern 131, normal recording can be performed.

  FIGS. 14A and 14B are diagrams illustrating examples of dot arrangement patterns that can be used in the dot arrangement patterning process J07. Here, a dot arrangement pattern of level 5 is illustrated as a gradation that is easily affected by airflow fluctuation. FIG. 14A shows an example in which dots are evenly distributed in four columns in a 4K to 4K + 3 dot arrangement pattern. On the other hand, FIG. 14B shows a characteristic dot arrangement pattern used in this embodiment.

  In the present embodiment (FIG. 14B), four groups A to D are prepared as the dot arrangement pattern used at level 5. As can be seen by comparing these, the number of dots in the second column ((4N + 2) column) is suppressed lower than the other columns in the group A, and the first column ((4N) +1 column) in the group B. The number is kept lower than other columns. In Group C, the number of dots in the fourth column (4N column) is kept lower than in the other columns, and in Group D, the number of dots in the third column ((4N) +3 columns) is lower than in the other columns. It is suppressed.

  If a (4N + 2) column is recorded in the area D in a certain unit area, the dot arrangement pattern of the A group is used for such a unit area in order to reduce (4N + 2) column dots. Execute dot arrangement pattern processing. Further, if (4N + 1) columns are recorded in the area D, for such a unit area, in order to reduce the dots in the (4N + 1) columns, the dot arrangement pattern processing is performed using the B group dot arrangement pattern. Run. Further, if the (4N) column is recorded in the area D, the dot arrangement pattern processing is performed using the dot arrangement pattern of the C group for such a unit area in order to reduce the dots in the (4N) column. Run. Further, if the (4N + 3) column is recorded in the area D, for such a unit area, in order to reduce the dots in the (4N + 3) column, the dot arrangement pattern processing is performed using the D arrangement dot arrangement pattern. Run.

  FIGS. 15A and 15B are views showing the recording state when the dot arrangement pattern of the present embodiment shown in FIG. 14B is used, as in FIG. FIGS. 16A and 16B are diagrams showing a recording state when a dot arrangement pattern in which dots are evenly arranged in all the columns shown in FIG. 14A is used.

  In the present embodiment, since the image data (level 5) is converted according to the dot arrangement pattern shown in FIG. 14B, the print data 150 is obtained in the dot arrangement patterning process. On the other hand, when the image data (level 5) is converted according to the dot arrangement pattern shown in FIG.

  Mask patterns 151 and 161 are equivalent to the mask patterns shown in FIGS. The column thinning patterns 152a to 152d and the column thinning patterns 162a to 162d are also equivalent to the column thinning patterns 132a to 132d described with reference to FIG.

  Referring to FIG. 15A, in the case where an actual recording scan is performed in this embodiment, the recording head includes the recording data 150, the mask pattern 151, and any of the set column thinning patterns 152a to 152d. According to the result of the logical product, dots are recorded. As a result, dots are recorded according to the dot pattern 153a in (4N + 1) scanning, according to the dot pattern 153b in (4N + 2) scanning, according to the dot pattern 153c in (4N + 3) scanning, and according to the dot pattern 153d in 4N scanning.

  On the other hand, refer to FIG. When the actual print scanning is performed using the dot arrangement pattern of FIG. 14A, the print head performs a logical product of the print data 160, the mask pattern 161, and any of the set column thinning patterns 162a to 162d. According to the result of, dots are recorded. As a result, dots are printed according to the dot pattern 163a in (4N + 1) scanning, according to the dot pattern 163b in (4N + 2) scanning, according to the dot pattern 163c in (4N + 3) scanning, and according to the dot pattern 163d in 4N scanning.

  Here, the dot patterns 153a to 153d of each column in this embodiment are compared with the dot patterns 163a to 163d of each column when the dot arrangement pattern of FIG. 14A is used.

  When the dot arrangement pattern of FIG. 14A is used, it can be seen that all of the dot patterns 163a to 163d have a larger number of dots in the region D than in other regions. This is because, in the dot arrangement pattern of FIG. 14A, the print data is evenly distributed to all the columns, so the mask pattern print allowance in each area is directly reflected in the number of print dots in each area. It is.

  On the other hand, in the case of the present embodiment using the dot arrangement pattern of FIG. 14B, it can be seen that in any of the dot patterns 153a to 153d, the number of dots in the region D is equal to the number of dots in the other regions. This is because, for each unit area, a dot arrangement pattern is set in advance so that the recording data of the column recorded in the area D having a high recording allowance rate is distributed as little as possible.

  FIG. 15B is a diagram illustrating a state in which an image is formed by repeating each recording scan of the recording head and a recording medium conveyance operation according to the dot patterns 153a to 153d. The dot patterns 134a to 134h indicate the dot patterns in the individual scans and their relative positions. Explaining with reference to the figure, in the image area X, 4N columns are recorded in the area D having a high recording allowance rate by the dot pattern 154d. Therefore, the dot arrangement patterning process using the dot arrangement pattern of the C group in which the recording data distributed to the 4N columns is reduced is performed on the image area X. As a result, even if the recording allowance of the mask pattern in the area D is higher than that in the other areas, the number of ejections between these areas is almost equal in the dot pattern obtained from the logical product of the dot arrangement pattern and the mask pattern. I can do it.

  On the other hand, for the image area Y adjacent to the image area X, (4N + 1) columns are recorded in the area D by the dot pattern 154e. Therefore, the dot arrangement patterning process using the B group dot arrangement pattern in which the print data distributed to the (4N + 1) columns is suppressed is performed on the image area Y. As a result, even if the recording allowance of the mask pattern in the area D is higher than that in the other areas, the number of ejections between these areas is almost equal in the dot pattern obtained from the logical product of the dot arrangement pattern and the mask pattern. I can do it.

  As described above, according to the present embodiment, even if the multipass number m is not a multiple of the column thinning number n, the number of times of ejection in each area of the print head is prepared by preparing an appropriate mask pattern and dot arrangement pattern. Can be made uniform, and the adverse effects of the image due to the generation of airflow can be reduced.

  In the above two embodiments, the case where 5-pass multi-pass printing (m = 5) is performed by 2-column thinning (n = 2) and the case where 7-pass multi-pass printing is performed by 4-column thinning have been described as examples. However, the present invention is not limited to such combinations. In general, when m and n are integers of 2 or more, when multi-pass printing of m passes is performed by column thinning every n columns, (N × n) columns, (N × n + 1) columns, ... ( N × n + (n−1)) columns are recorded with different recording scans. At this time, among the (N × n) columns (N × n + (n−1)) columns, the number of recording scans for recording a predetermined column is larger than the number of recording scans of other columns. In a small unit area, there is a concern about the generation of airflow in the recording scan for recording the column. Therefore, in such a unit area, if the number of ejections in the recording scan for recording the column can be suppressed by setting a dot arrangement pattern in which the number of recording pixels in the predetermined column is suppressed low, The same effect as the embodiment can be obtained.

  In the embodiment described above, specific gradations such as level 4 and level 5 have been described as examples. However, gradations that are affected by the generation of airflow are not limited to specific levels. For example, when the adverse effect is conspicuous in a relatively wide range such as level 3 to level 5, it is possible to prepare the characteristic dot arrangement pattern as described above in all of level 3 to level 5.

  Also, the dot arrangement patterns shown in FIGS. 6, 9 and 14A and 14B are examples, and other arrangements are possible. At this time, in each group, the degree of deviation in the number of dots between columns for reducing the number of dots in a specific column can be adjusted according to the state of airflow and how the problem is conspicuous.

  Further, the dot arrangement pattern and the mask pattern as described above may be prepared independently for each ink color. When the conspicuousness other than the image due to the airflow differs depending on the ink color, the degree of deviation of the number of dots between the columns in the dot arrangement pattern may be varied depending on the ink color.

  In the above embodiment, the dot arrangement pattern of 8 pixels × 4 pixels is prepared because it is quantized to 9 values in halftoning J05. For example, it is quantized to 5 values and a 2 × 2 dot arrangement pattern is prepared. Even in this case, the above method can be adopted.

  In the above description, FIG. 5 is used to describe the processing up to print data creation processing in the host device and the processing after the dot arrangement patterning processing in the recording device. However, the present invention is limited to such a form. Is not to be done. The recording apparatus of the present invention may be in a form capable of executing all the processes shown in FIG. In addition, the entire system including the host apparatus corresponds to the recording apparatus of the present invention as long as the process up to the mask data conversion process is performed by the host apparatus and the recording apparatus performs column thinning according to the received binary data. .

A1 recorder
A2 control unit
A3 CPU
A7 Recording head
A34 Dot recording position determination unit
A36 Used nozzle row determination unit
A37 used squeeze column change
A38 Image output unit
A41 Discharge characteristics acquisition unit
A45 Nozzle row distribution pattern storage unit
A51 Used nozzle row information storage unit
A52 Discharge defective nozzle information storage unit
A53 Allowable distribution rate storage unit
A54 Complement table determination unit
A55 Complement table storage

Claims (4)

A recording scan in which a recording head in which a plurality of recording elements for ejecting ink are arranged in a first direction is moved in a second direction intersecting the first direction; and a recording medium in the first direction A unit region of the recording medium by performing m recording scans in each of m regions obtained by alternately dividing a plurality of the recording elements in the first direction. An inkjet recording apparatus for recording
Dot recording and non-recording for each pixel is a dot arrangement pattern for converting the image data of the unit area into binary dot data by referring to the dot arrangement pattern determined in association with the level value of the image data And
Means for generating print data of each print scan by a logical product of the dot data and a mask pattern in which dot print permission and non-permission for each pixel of the plurality of print elements in the print scan are determined;
The recording scan in which ink is ejected from the plurality of recording elements while thinning out the recording data every n columns (n is an integer of 2 or more) in the second direction is performed in (N × n) columns, (N × n + 1) columns ... (N × n + (n−1)) columns (N is a positive integer) printing means for printing so as to be printed by different printing scans;
Means for transporting the recording medium in the first direction by a distance corresponding to the width of the unit area each time the recording scan is completed;
With
M is an integer larger than n and not a multiple;
The dot arrangement patterning unit sets the different dot arrangement pattern for each unit region so that the number of ejections to the unit region on which the recording head performs recording does not exceed a predetermined number in each recording scan. An ink jet recording apparatus.   The dot arrangement patterning means includes the recording scan for recording a predetermined column among the (N × n) columns, (N × n + 1) columns,... (N × n + (n−1)) columns. In the unit area where the number of recording pixels is smaller than the number of recording scans for recording other columns, the number of recording pixels of the predetermined column is suppressed to be lower than the recording pixels of the other columns. The inkjet recording apparatus according to claim 1, wherein a dot arrangement pattern is set.   In each area of the mask pattern corresponding to the m areas, (N × n) columns, (N × n + 1) columns (N × n + (n−1)) for the same unit area. 3. The ink jet recording apparatus according to claim 1, wherein, in the columns (N is a positive integer), areas in which the same column is recorded have a complementary relationship with each other. A recording scan in which a recording head in which a plurality of recording elements for ejecting ink are arranged in a first direction is moved in a second direction intersecting the first direction; and a recording medium in the first direction A unit region of the recording medium by performing m recording scans in each of m regions obtained by alternately dividing a plurality of the recording elements in the first direction. An ink jet recording method for recording
Dot recording and non-recording for each pixel is a dot arrangement pattern for converting the image data of the unit area into binary dot data by referring to the dot arrangement pattern determined in association with the level value of the image data Conversion process,
Generating print data of each print scan by a logical product of the dot data and a mask pattern in which dot print permission and non-permission for each pixel of the plurality of print elements in the print scan are determined;
The recording scan in which ink is ejected from the plurality of recording elements while thinning out the recording data every n columns (n is an integer of 2 or more) in the second direction is performed in (N × n) columns, (N × (n + 1) column ... (N × n + (n−1)) column (N is a positive integer), and a recording process to be executed so as to be recorded by different recording scans;
Transporting the recording medium in the first direction by a distance corresponding to the width of the unit area each time the recording scan is completed;
Have
M is an integer larger than n and not a multiple;
The dot arrangement patterning step sets the different dot arrangement pattern for each unit region so that the number of ejections to the unit region on which the recording head performs recording does not exceed a predetermined number in each recording scan. An inkjet recording method characterized by the above.

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