JP2005169950A - Inkjet recording method and inkjet recording apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording method and a recording apparatus, which enable the performance of high-speed recording while reducing a color mixture and bleeding in a boundary part of ink on a recording medium. <P>SOLUTION: A plurality of nozzle arrays of a recording head, wherein the nozzle arrays for each color are arranged so as to be symmetrical along a scanning direction, is grouped so that the mutually adjacent nozzle arrays belong to difference groups and so that combinations of the nozzle arrays for the respective color, belonging to each of the different groups, can be the same as one another; in the prescribed scanning of the recording head, control is performed so that the use ratio of the nozzle array of one of the groups can be higher than that of the nozzle array of the other group; and recording is performed in a recording area by the nozzle arrays included in the groups in accordance with the use ratios. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an inkjet recording method and an inkjet recording apparatus, and more particularly to an inkjet recording method and an inkjet recording apparatus that perform recording by applying ink from a recording head to a recording medium.

  An ink jet recording apparatus is a non-impact recording apparatus that can be easily printed in color and can provide high-quality images. It is widely used as an output device for various applications such as an output device for OA equipment.

  An ink jet recording apparatus includes a recording element that discharges ink, and the recording element includes a method in which a heater near a nozzle is heated in a short time, the foam is instantaneously generated, and the ink is pushed out from the nozzle by that force. A plurality of nozzles are arranged to form a head (recording head), the heads are arranged for each color, and ink is ejected from the head for each color to achieve color printing. In recent years, the number of nozzles has been increased and the head lengthened in order to achieve high-speed printer printing.

  In recording a color image, various elements such as color developability, gradation, and uniformity of an ink image formed on a recording medium are required. In particular, with regard to uniformity, slight variations in nozzle units, such as the shape of the discharge ports that occur in the printing element array production process, affect the amount of ink discharged from each nozzle and the direction of the discharge direction, resulting in uneven image density. As a result, the image quality is degraded. That is, the performance of the recording head greatly affects the image quality.

  Therefore, as a measure against density unevenness, all pixels to be recorded in the same recording scan of the recording head for a certain band A are divided into a plurality of groups, and ink is applied to the pixels of the groups sequentially divided by a plurality of reciprocating recording scans. A multi-pass recording method for forming an image on band A by providing (See Patent Document 1). With this multi-pass printing, since printing is performed using different nozzles for each scan, the influence on the print image unique to each nozzle is reduced, and density unevenness is alleviated.

  However, when the multi-pass reciprocal recording as described above is performed and the color is expressed by the color mixture of each color ink that the recording head has, the relative order of each color nozzle row on the head with respect to the reciprocal recording direction is turned over, and the ink The order in which colors are superimposed varies depending on the order of driving, and as a result, different colors may be expressed for human visual characteristics. Therefore, when paper feeding is performed for each head width for each reciprocating scan, the color of the forward recording and the color of the backward recording appear to be different in an image that should be uniform with respect to the hue of the mixed color, Significant image degradation will occur.

  Furthermore, in recent years, further high-speed recording and high image quality are required, and in the method of recording by simply dividing a plurality of times by multipass as described above, the time cost related to recording is more than doubled, and as a recording device This situation is not very favorable.

  Therefore, two or more heads are arranged so that the recording element arrays of each ink are symmetrical in the main scanning direction so that the order of ink stacking in the forward recording and the backward recording is the same. An ink jet recording apparatus characterized by this is proposed. (See Patent Document 2 and Patent Document 3). When these recording apparatuses are used, color unevenness due to the ink ejection order does not occur, and high-speed recording can be achieved without increasing the number of multipass scans.

  However, as a result of performing high-speed recording by reducing the number of multipass scans in these recording apparatuses, the total recording duty in one scan of the recording head increases, and ink is not sufficiently fixed to the recording medium. Then, a lot of ink droplets land. In this way, when a large amount of ink droplets are ejected onto the recording medium in a relatively short time, the boundary portions of adjacent ink dots are combined to mix colors between other colors, or to squeeze characters and ruled lines. However, there is a problem that the image quality is significantly lowered. Further, the phenomenon becomes more remarkable in the recording apparatus having a plurality of head units.

  Therefore, an ink jet recording apparatus is disclosed in which a heater is provided below the platen facing the recording head, and the recording medium and the ink are dried by radiant heat to improve the fixing property of the ink to the recording medium. (See Patent Document 4).

  However, such an ink jet recording apparatus has a problem that not only the cost is inevitably increased, but the effect is reduced as the recording speed is increased.

US Pat. No. 4,748,453 Japanese Patent Laid-Open No. 2001-171151 JP 2000-079681 A Japanese Patent Laid-Open No. 10-86353

  As is clear from the above, in printing by the ink jet recording method, a method using a multi-pass is effective in order to reduce nozzle-specific variations and the like. However, there are still problems to be solved in order to improve the quality of the ink image formed on the image. In particular, it is desired to prevent or reduce the phenomenon that ink droplets that are not absorbed continue (beading phenomenon) and the phenomenon that each color oozes out at the boundary of overlapping colors (bleeding phenomenon).

  In order to prevent and reduce the beading phenomenon and the bleeding phenomenon, it is conceivable to increase the interval between the nozzle rows of each color and increase the time interval of ink ejection from each color nozzle row. By increasing the nozzle row spacing of each color, the ink that has landed first in a certain area on the recording medium is sufficiently absorbed by the recording medium, and then the next ink lands in that area. The phenomenon is reduced. However, when the interval between the nozzle rows of each color is increased in this way, the carriage on which the head is mounted becomes larger together with the recording head, and accordingly, the width of the main body becomes larger, the apparatus cost increases, and space saving is hindered. Become.

  On the other hand, if the time interval for ejecting ink from each color nozzle row is increased, the ink that has landed first on the recording medium is sufficiently absorbed before the next ink is landed. The phenomenon can be reduced, but high-speed recording cannot be performed.

  The present invention has been made in view of such problems, and an object of the present invention is to perform ink jet recording capable of high-speed recording while reducing color mixing and bleeding at the ink boundary on the recording medium. It is to provide a method and ink jet recording apparatus recording.

  In order to achieve such an object, the present invention scans a recording area of a recording medium with a recording head in which nozzle rows of each color corresponding to each color of ink are arranged in the scanning direction. In the ink jet recording method, the grouping step of performing grouping so that the nozzle rows adjacent to each other belong to different groups when dividing the plurality of nozzle rows of the recording head into a plurality of groups, In a predetermined scanning, a control step of controlling the usage ratio of the nozzle rows in one group among the plurality of groups to be higher than the usage ratio of the nozzle rows in the other group, and the control in the predetermined scanning Recorded in the recording area by the nozzle rows included in the plurality of groups in accordance with the used ratio. Characterized in that it comprises a recording step of performing.

  The present invention also provides an inkjet recording apparatus that records an image by scanning a recording area of a recording medium with a recording head arranged so that nozzle rows of each color corresponding to the ink of each color are symmetrical along the scanning direction. In the recording method, when dividing the plurality of nozzle arrays of the recording head into a plurality of groups, the nozzle arrays adjacent to each other belong to different groups, and the combinations of the color nozzle arrays belonging to the different groups are the same. In the grouping step for performing grouping and the predetermined scan of the recording head, control is performed such that the nozzle row usage ratio in one group is higher than the nozzle row usage ratio in the other group among the plurality of groups. A control step, and in accordance with the controlled usage ratio in the predetermined scan. Characterized in that it comprises a recording step for recording into the recording region by the nozzle rows included in the plurality of groups Te.

  Further, the present invention provides a recording head in which nozzle rows corresponding to ink of each color are arranged in the scanning direction so that the order of color overlap is the same in the forward scanning and the backward scanning with respect to the recording area of the recording medium. In an ink jet recording method for recording an image by scanning, in dividing the plurality of nozzle rows of the recording head into a plurality of groups including at least two groups, grouping is performed so that adjacent nozzle rows belong to different groups. In the grouping step of performing the recording and the predetermined scan of the recording head, control is performed so that the nozzle row usage ratio in one of the at least two groups is higher than the nozzle row usage ratio in the other group. Control step, and the predetermined scan in accordance with the controlled usage ratio. The nozzle arrays included in the group, characterized in that it comprises a recording step for recording into the recording region.

  The present invention also provides an inkjet recording apparatus that records an image by scanning a recording area of a recording medium with a recording head arranged so that nozzle rows of each color corresponding to the ink of each color are symmetrical along the scanning direction. In the recording apparatus, when dividing the plurality of nozzle arrays of the recording head into a plurality of groups, the nozzle arrays adjacent to each other belong to different groups, and the combinations of the color nozzle arrays belonging to the different groups are the same. Grouping means for performing grouping and control so that the nozzle row usage ratio in one of the plurality of groups is higher than the nozzle row usage ratio in the other group in a predetermined scan of the recording head And a control means for performing the control according to the controlled usage ratio in the predetermined scan. Characterized in that it comprises a recording means for performing recording to the recording area by the nozzle rows included in the plurality of groups Te.

  The first mask pattern of the present invention can be a usage ratio determination mask pattern described later, and the second mask pattern can be a recording rate determination mask pattern described later.

  Furthermore, the “recording medium” of the present invention can accept not only paper used in a general recording apparatus but also a wide range of inks such as cloth, plastic film and the like.

  According to the present invention, since the recording medium can sufficiently absorb the ink ejected from each nozzle row in a relatively short time, a high-quality image with reduced beading and bleeding can be formed.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(First embodiment)
In this embodiment, multi-pass printing is performed by a twin head that uses two print heads, and image data is thinned out in order from the top nozzle row of these two print heads so that the usage ratio becomes higher and lower. A thinning pattern for processing is created, and an image is formed in each scan of the recording head according to the thinning pattern.

FIG. 1 is a diagram illustrating a configuration of a recording unit of the ink jet recording apparatus according to the present embodiment.
Reference numeral 401 denotes a first recording head, and color inks of six colors (K (black), Lc (light cyan), C (cyan), Lm (light magenta), M (magenta), Y (yellow))) are respectively used. It is configured to include a multi-recording head in which an enclosed ink tank and six nozzle rows corresponding to each are integrated. Reference numeral 402 denotes a second recording head having the same configuration as that of the first recording head 401, and six nozzle array arrangements corresponding to six colors (Y, M, Lm, C, Lc, K) are recorded in the recording head 401. It is symmetrical with the arrangement of.

  Reference numeral 403 denotes a carriage that supports the first recording head 401 and the second recording head 402 and moves them in the X direction (main scanning direction) together with recording. The carriage 403 is in a home position position (a position indicated by の) in the drawing at the time of standby such as a non-recording state. Reference numeral 404 denotes a paper feed roller that rotates in the direction of the arrow in the figure while holding the recording medium 407 together with the auxiliary roller 405, and feeds the recording medium 407 in the Y direction (sub-scanning direction) as needed. Reference numeral 406 denotes a paper feed roller that feeds the recording medium 407 and plays a role of suppressing the recording medium 407 in the same manner as the paper feed roller 404 and the auxiliary roller 405.

  In the present invention, the first recording head 401 and the second recording head 402 each have 1280 nozzles arranged in the paper feed direction for the six colors K, Lc, C, Lm, M, and Y. And The number of nozzles included in the nozzle row corresponding to each color is not limited to 1280, and can be changed as appropriate according to the size of the apparatus, recording conditions, and the like.

A basic reciprocal recording operation in the above configuration will be described.
The carriage 403 at the home position ◎ during standby is scanned by the plurality of nozzles of the first recording head 401 and the second recording head 402 while scanning (scanning) in the X direction by a recording start command in the forward scanning of the recording head. According to the recording data, ink is ejected onto the recording medium 407 for recording. When the recording of the recording data to the end of the recording medium 407 is completed, the carriage 403 scans in the X direction toward the home position position ◎ in the backward scanning, and the first recording head 401 and the first recording head as in the forward scanning. Recording is performed on the recording medium 407 by ejecting ink with the two recording heads 402. When the carriage 403 returns to the home position ◎, the paper feed roller 404 rotates in the direction of the arrow, thereby feeding the paper by a predetermined width in the Y direction and starting recording in the X direction again. Recording of recording data is realized by repeating such a reciprocating scanning operation and a paper feeding operation.

FIG. 2 is a diagram illustrating a configuration of the recording head according to the present embodiment.
In FIG. 2, the first recording head 401 is arranged on the front side in the forward scanning direction, and nozzle rows from which ink of each color is ejected are arranged in the order of K, Lc, C, Lm, M, and Y from the top. In addition, a second recording head 402 is arranged on the rear side in the forward scanning direction, and nozzles for ejecting ink of each color are Y, M, Lm, C, Lc, and K symmetrically with respect to the first recording head 401. Arranged in order.

  As described above, when the twin head is used, since the recording is performed by sharing the pixels, the speed of the carriage 403 can be increased.

  In this embodiment, six colors of inks K, Lc, C, Lm, M, and Y are used. However, the number of inks is not limited to this, and may be three colors, four colors, or the like. Further, the hue of the ink to be used is not limited to this. For example, an ink having a hue different from the above may be used, such as red or flesh-colored ink. Further, regarding the arrangement of the nozzle rows of the respective colors, any arrangement can be used as long as the arrangement is symmetrical between the first recording head and the second recording head.

FIG. 6 is a schematic block diagram of a control system of the ink jet recording apparatus according to the present invention.
In FIG. 6, an input / output interface 301 is an interface for exchanging information such as data and commands between the inkjet recording apparatus and a host computer 300 which is a supply source of image data. The CPU 309 executes control processing of the operation of the ink jet recording apparatus, data processing, and the like. The ROM 303 stores programs such as those processing procedures, and the RAM 304 is used as a work area or the like for executing these processes. Ink ejection from the first recording head 401 and the second recording head 402 is performed by the CPU 309 using the driving data (image data) and the driving control signal (heat pulse signal) of the heating elements (not shown) of the respective heads as the first head. This is performed by supplying the driver 307 and the second head driver 308. The CPU 309 controls a driving motor 306 for driving the carriage 403 in the main scanning direction and for conveying the recording medium 407 in the sub scanning direction via the motor driver 305.

  Next, the control of the recording operation of the first recording head 401 and the second recording head 402 according to this embodiment will be described in detail. In the present embodiment, the recording operation of each recording head is controlled by a thinning process using a mask pattern described later.

FIG. 3 is a block diagram showing the configuration of the printhead control block according to this embodiment.
Note that the ink jet recording apparatus according to the present embodiment not only performs reciprocal recording by dispersing recording dots in the first recording head 401 and the second recording head 402, but also multi-scans the same region to form an image multiple times. The pass recording method is adopted. As described above, multi-pass printing is a printing method that suppresses density unevenness due to slight differences in the ink ejection amount and ejection direction for each nozzle by forming an image using a single band using a plurality of nozzles.

  In this embodiment, among the multi-pass printing methods, each nozzle used in the same pass is used to allocate image data corresponding to a predetermined area (for example, one band) to be printed in a plurality of passes to each pass. A method of thinning out image data according to a mask pattern (for example, use ratio determination mask patterns 501 and 502 shown in FIG. 4) that defines a column use ratio (also referred to as “use ratio determination mask thinning method” in this specification); A method of thinning out image data in accordance with a mask pattern (for example, recording rate determination mask patterns 503 to 506 shown in FIG. 5) that determines the recording rate in each pass (also referred to as “recording rate determination mask thinning method” in this specification) The multi-pass recording method is used.

  In this specification, the “use ratio” defined by the use ratio determination mask pattern refers to a plurality of use ratio determination masks used to determine the use ratio of each nozzle row, as described with reference to FIG. It can be said that this is the ratio of the number of recording pixels of the use ratio determining mask pattern corresponding to each nozzle row to the total number of recording pixels (655360) of the patterns 501 and 502. For example, the total number of recording pixels of the usage ratio determination mask patterns 501 and 502 is 655360 (= 1280 × 512), and the number of recording pixels of the usage ratio determination mask pattern 501 is 491520. Therefore, the usage ratio of the usage ratio determination mask pattern 501 is 75 (= 491520/655360 × 100)%. On the other hand, the recording rate of the usage ratio determination mask pattern 502 is 25 (= 163840/655360 × 100)%.

  Further, in this specification, the “recording rate” defined by the recording rate determination mask pattern is a plurality of recordings used for recording a predetermined area in a plurality of passes, as described with reference to FIG. It can be said that it is the ratio of the number of recording pixels of the recording rate determination mask pattern corresponding to each pass to the total number of recording pixels (655360) of the rate determination mask patterns 503 to 506. For example, the total number of recording pixels of the recording rate determination mask patterns 503 to 506 is 655360 (= 1280 × 512), and the number of recording pixels of the recording rate determination mask pattern 503 is 163840. Therefore, the recording rate of the recording rate determination mask pattern 503 is 25 (= 163840/655360 × 100)%. Similarly, the recording rate of each of the recording rate determination mask patterns 504 to 506 is 25 (= 163840/655360 × 100)%.

  The “recording pixel” refers to a portion indicated by black in the mask pattern of FIGS. 4 and 5 and is a pixel that allows recording (ink ejection). If the image data corresponding to this recording pixel is data indicating ink ejection, recording is performed, and if it is data indicating non-ejection, recording is not performed. Further, the “non-recording pixel” refers to a portion shown in white in the mask pattern of FIGS. 4 and 5 and is a pixel that does not allow recording regardless of image data. Accordingly, even if the image data corresponding to the non-recording pixels is data indicating ink ejection, no recording is performed.

  Here, in the present embodiment, recording is performed by 4-pass reciprocal recording. In the present embodiment, the number of recording passes is not limited to the above.

  Reference numeral 101 denotes a memory unit that temporarily stores recording data subjected to image processing for recording. In addition, 2-bit data indicating the number of recording passes of the recording head is also stored. Further, a usage ratio determination mask pattern used in the usage ratio determination mask thinning method and a recording ratio determination mask pattern used in the recording rate determination mask thinning method are also stored.

  Reference numeral 102 denotes a memory output control unit, which performs read processing of print data based on the relative position on the print medium for each ink in the print head. Reference numeral 103 denotes a multi-pass / double-head data generation unit, which generates first print head pass data and second print head pass data by thinning out image data according to the number of print passes. Reference numeral 104 denotes a first recording head control unit that generates various control signals for driving the first recording head 401. Reference numeral 105 denotes a second recording head controller, which generates various control signals for driving the second recording head 402. The first recording head 401 ejects ink onto the recording medium according to the first recording head pass data. The second recording head 402 ejects ink onto the recording medium according to the second recording head pass data. Reference numeral 108 denotes a control unit that monitors the state of each unit based on the number of recording passes and performs various controls relating to recording head driving.

  The “number of recording passes” in the present embodiment is the number of scans that the recording head moves while recording from one end of the recording medium to the other end, which is necessary to complete the recording of a certain band. For example, the number of recording passes is 4 or the 4-pass reciprocal recording means that the recording head is reciprocated twice to complete recording on a certain area on the recording medium, that is, two forward scans and two reciprocal scans. This means that backward scanning is performed.

  Further, in this embodiment, the recording medium is fed at the end of one reciprocating operation, rather than performing the backward feeding by performing paper feeding after the end of recording in the reciprocating operation of the recording head. Is. Therefore, when the number of recording passes is N, the conveyance control is performed so as to perform 2 / N band feeding of the effective number of nozzles of the recording head. As described later in each scan, if recording is performed with different usage ratios in adjacent nozzle rows, there is a concern that color unevenness may occur due to the change in the order of ink that lands on each band. As described above, this concern is solved by closing the path without feeding the paper between the forward pass recording and the backward pass recording, and carrying out the paper feed when the reciprocating scanning is finished.

First, the basic recording head control operation of the entire recording head control block will be described.
The memory unit 101 stores recording data binarized by the control system for each ink color. Based on the recording area control from the control unit 108, the memory output control unit 102 performs binary recording stored in the memory unit 101 for each scan in accordance with the relative position of the nozzle row corresponding to each ink color on the recording medium. Data is read out and output to the multipath / double head data generation unit 103. In the multi-pass / double-head data generation unit 103, the first recording head pass data for the first recording head 401 is used in accordance with the number of recording passes by using both the usage ratio determination mask thinning method and the recording rate determination mask thinning method. And the second recording head pass data for the second recording head 402 are generated and output to the first recording head control unit 104 and the second recording head control unit 105, respectively. Details of a method for generating pass data for each print head will be described later.

  In the present embodiment, the use ratio determination mask patterns 501 and 502 shown in FIG. 4 stored in the memory unit 101 are used, and the thinning process is performed using the recording rate determination mask patterns 503, 504, 505, and 506 shown in FIG. To perform 4-pass reciprocal recording of the recorded information.

  FIG. 4 is a diagram illustrating an example of a usage ratio determination mask pattern according to the present embodiment, and FIG. 5 is a diagram illustrating an example of a recording rate determination mask pattern in 4-pass reciprocal recording according to the present embodiment.

  In this embodiment, the use ratio determination mask patterns 501 and 502 and the recording rate determination mask patterns 503, 504, 505, and 506 each have a recording density of 1200 dpi and 1280 pixels in the sub-scanning (direction in which a plurality of rasters are arranged). , A region corresponding to a total of 655360 pixels of 512 pixels in the main scanning (direction in which a plurality of columns are arranged) is provided.

  In this embodiment, 1280 pixels are set in the sub-scanning direction and 512 pixels are set in the main scanning direction. However, the number of pixels is not limited to this number, and the number of pixels in each direction can be appropriately determined according to the recording head to be used.

  Hereinafter, the usage ratio determination mask pattern will be described in detail with reference to FIG. 4, and the recording rate determination mask pattern will be described in detail with reference to FIG.

  The usage ratio determination mask pattern is a mask pattern for determining the usage ratio of the same color nozzle row in the same scan. With this mask pattern, the recording pixels are allocated to the same color nozzle row of the first recording head 401 and the second recording head 402 in each scan, and the use ratio in each scan is determined. In FIG. 4, reference numeral 501 denotes a mask pattern having a usage ratio of 75%. In each scan, the nozzle array that ejects ink according to the image data thinned out by the usage ratio determination mask pattern 501 covers the entire predetermined recording area. It is used at a ratio of 75%. On the other hand, reference numeral 502 denotes a mask pattern having a usage ratio of 25%. In each scan, the nozzle array that ejects ink according to the image data thinned out by the usage ratio determination mask pattern 502 is 25% of the entire recording medium. It is used in the ratio. These use ratio determining mask patterns 501 and 502 have a complementary relationship in which the recording / non-recording portions are inverted from each other. Note that white portions in the use ratio determination mask patterns 501 and 502 are mask portions (non-recording pixels), and are pixels that do not permit ink ejection. On the other hand, the black portion is a pixel (recording pixel) that permits ink ejection.

  The recording rate determination mask pattern is a mask pattern for performing mask processing at a predetermined recording ratio on image data so as to complete an image by a plurality of scans. In this embodiment, since recording is performed by 4-pass reciprocal recording, the recording rate is set to 25%. In FIG. 5, white portions in the recording rate determination mask patterns 503, 504, 505, and 506 are mask portions, and are portions where ink ejection is not permitted. On the other hand, the black portion is a portion that permits ink ejection. Therefore, since the recording rate is 25%, each black portion in the recording rate determination mask patterns 503, 504, 505, and 506 is 25% of the entire area of the mask pattern. Using such a recording rate determination mask pattern, mask processing is performed on the binary-developed image data, and recording is performed at a recording rate of 25% in each scan. The four recording rate determination mask patterns are in a complementary relationship, and the nozzles are used as evenly as possible.

  In this embodiment, a recording rate determination mask pattern with a recording rate of 25% is used. However, a recording rate determination mask pattern with a recording rate corresponding to the number of recording passes can be used. For example, if the number of recording passes is 8, it is preferable to use a recording rate determination mask pattern with a recording rate of 12.5%.

  Next, the flow until recording is completed for a certain band of the recording medium (band corresponding to the length in the sub-scanning direction of the nozzle array used in the recording head) by the four-pass reciprocal recording is applied to the pass data used in each scanning. This will be described together with a description of the thinning process.

  Image processing is performed by an image processing unit (not shown), which is expanded into binary images of the respective colors K, Lc, C, Lm, M, and Y, and image data corresponding to the respective colors is generated. The ink jet recording apparatus sends a signal to the motor driver 305, operates each drive motor 306, conveys the recording medium to a predetermined position, and enters a recording standby state.

  Next, recording is performed by scanning in the main scanning direction of the recording head. In this embodiment, since 4-pass reciprocal recording is performed, the recording head is used to complete recording in a certain band on the recording medium 407. It is necessary to scan four times. At this time, paper feeding is not performed between the recording by the first scanning (first pass forward recording) and the recording by the second scanning (second pass backward recording) with respect to a certain band. The paper is fed by a length corresponding to ½ of the number of nozzles of the recording head between the second pass printing and the third scan printing (third pass forward printing). Also, the paper is not fed between the third pass forward recording and the recording by the fourth scan (fourth pass backward recording), and when the fourth pass backward recording is completed, the number of nozzles of the recording head is reached. The paper is fed for the remaining half of the length, and recording of a certain band is also completed. Recording is performed by repeating this operation. In each scan, image data is masked according to a thinning pattern to be described later, and recording is performed by a recording head.

First Pass Outward Recording First, in performing the first pass forward recording, the first recording head 401 of the first recording head 401 and the second recording head 402 is selected by the multi-pass / double head data generation unit 103. For the ejection data corresponding to the nozzle rows of K, C, M, and Y, Lm, and Lc of the second recording head 402, data thinning processing is performed using the recording rate determination mask pattern 503 and the usage ratio determination mask pattern 501. The ejection data corresponding to the remaining nozzle arrays Lc, Lm, and Y of the first recording head 401 and M, C, and K nozzle arrays of the second recording head 402 include a recording rate determination mask pattern 503 and Data thinning processing is performed using the usage ratio determination mask pattern 502, and each discharge data is created. That is, the ejection data of each nozzle row is created by the logical product of the usage ratio determination mask pattern, the recording rate determination mask pattern, and the image data, and ink is ejected by supplying this data to the driver.

Second pass return recording When the first pass forward recording is completed, the recording medium is not conveyed in the return pass recording. Among the first recording head 401 and the second recording head 402, the discharge data corresponding to the nozzle rows of K, C, M of the second recording head 402 and Y, Lm, Lc of the first recording head 401 include Data thinning processing is performed with the recording rate determination mask pattern 504 and the usage ratio determination mask pattern 501, and the remaining nozzle rows, Lc, Lm, Y of the second recording head 402 and M, C, of the first recording head 401, For the ejection data corresponding to each nozzle row of K, the data thinning process is performed by the recording rate determination mask pattern 504 and the usage ratio determination mask pattern 502, and the respective ejection data To create. That is, the ejection data of each nozzle row is created by the logical product of the usage ratio determination mask pattern, the recording rate determination mask pattern, and the image data, and ink is ejected by supplying this data to the driver. At this point, 50% of the recording band of 1280 nozzles has been recorded.

When the second pass backward recording of the recording medium is completed, the CPU 309 of the ink jet recording apparatus sends a signal to the motor driver 305 to drive the drive motor 306, thereby causing the recording medium 407 to be ½ of the number of nozzles of the recording head. Minutes (in this embodiment, 640 nozzles) are conveyed.

When transport of the third pass outbound recording medium 407 is completed, the multi-pass / double head data generation unit 103 performs the first pass head 401 and the second print head 402 to perform the third pass forward recording. Among these, the ejection ratio data corresponding to the nozzle rows of K, C, and M of the first recording head 401 and Y, Lm, and Lc of the second recording head 402 include the recording rate determination mask pattern 505 and the usage ratio determination mask pattern 501. In the discharge data corresponding to the nozzle rows Lc, Lm, and Y of the first recording head 401 and the nozzle rows M, C, and K of the second recording head 402, which are the remaining nozzle rows, Data thinning processing is performed by the recording rate determination mask pattern 505 and the usage ratio determination mask pattern 502, and each discharge data is created. That is, the ejection data of each nozzle row is created by the logical product of the usage ratio determination mask pattern, the recording rate determination mask pattern, and the image data, and ink is ejected by supplying this data to the driver.

When the forward pass recording of the fourth pass is completed, the multipass / double head data generation unit 103 does not carry the recording medium in the return pass recording and performs the fourth pass return pass. Among the first recording head 401 and the second recording head 402, the discharge data corresponding to the nozzle rows of K, C, M of the second recording head 402 and Y, Lm, Lc of the first recording head 401 include Data thinning processing is performed using the recording rate determination mask pattern 506 and the usage ratio determination mask pattern 501, and the remaining nozzle rows, Lc, Lm, Y of the second recording head 402 and M, C, of the first recording head 401, For the ejection data corresponding to each nozzle row of K, data thinning processing is performed by the recording rate determination mask pattern 506 and the usage ratio determination mask pattern 502, and the respective ejection data To create. That is, the ejection data of each nozzle row is created by the logical product of the usage ratio determination mask pattern, the recording rate determination mask pattern, and the image data, and ink is ejected by supplying this data to the driver. At this time, the remaining 50% recording is completed, and a desired image is formed on the band corresponding to the length of the recording head in the sub-scanning direction.

  As described above, when four-pass reciprocal recording is performed on the image data to be recorded, the first recording head 401 is the leading side in the scanning direction among the two recording heads in the forward scanning (see FIG. 2). In the backward scanning, the second recording head 402 is at the head side.

  In the case of the forward scan of the print head, the use ratio of each nozzle row is higher, lower, higher than the nozzle row on the head side of each of the two print heads in the scanning direction by performing the thinning process described above. Low, high, low. Also, in the case of the backward scan of the print head, the use ratio of each nozzle row is higher and lower than the nozzle row on the head side of each of the two print heads in the scanning direction by performing the thinning process described above. High, low, high, low.

  That is, in each scan, by making a difference in the usage ratio of the adjacent nozzle rows, there is a difference in the ink ejection amount from the adjacent nozzle rows when viewed from the recording medium in the scanning direction. That is, the amount of ink applied from the nozzle row with a high usage ratio increases, and the amount of ink applied from the nozzle row with a low usage ratio decreases. Therefore, from the viewpoint of the recording medium, a small amount of ink is applied from the low usage ratio nozzle array after the ink is applied from the high usage ratio nozzle array. Thus, there is a room for sufficiently absorbing the ink applied from the ink. In addition, after ink is applied from the nozzle row with a low usage ratio, a large amount of ink is applied from the nozzle row with a high usage ratio, but since a small amount of ink is applied from the nozzle row with a low usage ratio, Also in this case, the ink is sufficiently absorbed by the recording medium before the next ink landing. Therefore, the same effect as increasing the interval between the nozzle rows is produced, and the occurrence of beading and bleeding can be suppressed.

  In the present embodiment, the usage ratio determination mask pattern 501 having a usage ratio of 75% and the usage ratio determination mask pattern 502 having a usage ratio of 25% are used, that is, use for distributing the use of each nozzle row. Since the ratio is 3: 1, the usage ratio of each nozzle row from the head nozzle row of the first recording head 401 is 75% for the nozzle rows of K, C, M, and Lc, Lm, Y No. of nozzle rows are used at a rate of 25%. On the other hand, in the second recording head 402, the usage ratio of each nozzle row from the head nozzle row is 75% for the Y, Lm, and Lc nozzle rows, and the nozzle row for the M, C, and K nozzle rows. Is used at a rate of 25%. Therefore, in the case of forward scanning, a nozzle row with a high use ratio (first print head: K, C, M, second print head: Y, Lm, Lc) has a nozzle row with a low use ratio (first print head: Lc, Lm, Y, second recording head: M, C, K) is used three times more.

  Also in the case of forward scanning, as in the forward scanning described above, nozzle rows with high usage ratios (second recording heads: K, C, M, first recording heads: Y, Lm, Lc) have low usage ratios. It is used three times more than the nozzle row (second recording head: Lc, Lm, Y, first recording head: M, C, K).

  In this embodiment, when each thinning pattern is created, the usage ratio determination mask patterns 501 and 502 and the recording rate determination mask patterns 503, 504, 505, and 506 are the scanning distance of the recording head, that is, the length of the recording medium 407. Accordingly, a similar mask pattern may be repeatedly used as appropriate, and the scanning distance (recording width) of the recording head may be any distance.

  In the present embodiment, the nozzle array on the head side with respect to the scanning direction of the recording head (for example, in the forward scanning, the first recording head: K, C, M, the second recording head: Y, Lm, Lc) is used. The ratio is 75% and the usage ratio of the other nozzle row (for example, in the forward scan, the first recording head: Lc, Lm, Y, the second recording head: M, C, K) is 25%. The value may be selected as appropriate depending on the characteristics, print mode, type of print medium, etc., and the value is always high when the use ratio of the nozzle array on the top side is high in the scanning direction and the total use ratio reaches 100%. But you can. At this time, the usage ratio determination mask patterns to be used are complementary to each other. It is also possible to set the total use ratio of the use ratio determining mask pattern to be more than 100%.

  Furthermore, in this embodiment, the nozzle array used for printing in each scan is divided into two groups, a group used at a rate of 75% and a group used at a rate of 25%. It may be divided into two or more groups depending on the number, the length and type of the recording medium, and the like. At that time, the same number of usage ratio determination mask patterns as the divided groups are prepared, and these mask patterns are complementary to each other. Further, when creating a thinning pattern, the thinning process is preferably performed so that adjacent nozzle rows have different usage ratios.

  As described above, according to the present embodiment, in the image formation by the four-pass reciprocal recording, the usage ratio of the nozzle array to be used for each scan of the recording head is changed in order from the nozzle array on the head side in the scanning direction. Since the thinning pattern is created by performing thinning processing on the image data so as to be high and low, and recording is performed according to the thinning pattern, the boundary between adjacent ink dots is combined and mixed between other colors. The image quality is also reduced, and it becomes possible to record a high-quality image at a high speed in which the occurrence of bleeding that blurs characters and ruled lines is suppressed. In addition, since the occurrence of beading and bleeding can be suppressed without increasing the space between the nozzle rows, it is possible to suppress an increase in the size of the apparatus and the associated cost increase.

(Second Embodiment)
In this embodiment, multi-pass printing is performed by a single print head.
For example, when four colors of inks of K, C, M, and Y are used, the configuration of the recording head is such that the nozzle rows are arranged in C, M, Y, K, Y, M, and C from the head in the forward scanning direction. . At this time, K is not subjected to the distribution process using the use ratio determination mask pattern, and the same effect as in the first embodiment can be obtained by performing the thinning process for the other colors as in the first embodiment. can get.

  The hue of the ink to be used and the number of the inks are not limited to the above. Further, the arrangement of the nozzle rows for each color is not limited to the form in which the nozzle rows for each color are arranged so as to be symmetrical with respect to K. For example, the nozzle arrays may be arranged in the order of K, C, M, Y, M, and C along the main scanning direction. At this time, the distribution process by the use ratio determination mask pattern is not performed for K and Y. Since K is not frequently used at the same time as other colors, K is excluded, focusing only on the color nozzle rows, and the usage ratio of a plurality of color nozzle rows arranged along the scanning direction is used for each scan. What is necessary is just to set so that it may be in order of high, low, high, low ... (or low, high, low, high ...) from the head side.

(Third embodiment)
In the first and second embodiments, the form in which a plurality of nozzles of the same color are present has been described. However, the present invention can also be applied to a form in which a plurality of nozzles of the same color are not present. For example, the present invention can be applied to a form using only the first recording head described above.

  In the case of this form, first, when dividing the plurality of nozzle rows (K, Lc, C, Lm, M, Y) of the first recording head into a plurality of groups, the adjacent nozzle rows belong to different groups. Perform grouping. That is, K, C, and M are set as the first group, and Lc, Lm, and Y are set as the second group.

  Next, in a predetermined scan (for example, forward scan) of the recording head, the usage ratio (for example, 75%) of the nozzle rows in one group (for example, the first group) is the other group (for example, the second group). The nozzle array is controlled to be higher than the usage ratio (for example, 25%). If this control is performed using the mask patterns shown in FIGS. 4 and 5, the following is obtained. However, description of the transport operation is omitted here.

  First, in the first pass (first forward scan), the recording rate determination mask pattern 503 and the use ratio determination mask pattern 501 are applied to the first group, and the recording rate determination mask pattern is applied to the second group. 503 and a use ratio determination mask pattern 502 are applied. When the usage ratio in this forward scan is 100%, the usage ratio of the first group is 75% and the usage ratio of the second group is 25%.

  Next, in the second pass (first return scan), the recording rate determination mask pattern 503 and the use ratio determination mask pattern 502 are applied to the first group, and the recording rate determination mask is applied to the second group. A pattern 503 and a use ratio determination mask pattern 501 are applied. If the usage ratio in this backward scanning is 100%, the usage ratio of the first group is 25% and the usage ratio of the second group is 75%.

  Next, in the third pass (second forward scanning), the recording rate determination mask pattern 504 and the usage ratio determination mask pattern 501 are applied to the first group, and the recording rate determination mask is applied to the second group. A pattern 504 and a use ratio determination mask pattern 502 are applied.

  Next, in the fourth pass (second return scan), the recording rate determination mask pattern 504 and the usage ratio determination mask pattern 502 are applied to the first group, and the recording rate determination mask is applied to the second group. A pattern 504 and a use ratio determination mask pattern 501 are applied.

  Next, in the fifth pass (third outbound scan), the recording rate determination mask pattern 505 and the usage ratio determination mask pattern 501 are applied to the first group, and the recording rate determination mask is applied to the second group. A pattern 505 and a use ratio determination mask pattern 502 are applied.

  Next, in the sixth pass (third return scan), the recording rate determination mask pattern 505 and the usage ratio determination mask pattern 502 are applied to the first group, and the recording rate determination mask is applied to the second group. A pattern 505 and a use ratio determination mask pattern 501 are applied.

  Next, in the seventh pass (fourth outbound scan), the recording rate determination mask pattern 506 and the usage ratio determination mask pattern 501 are applied to the first group, and the recording rate determination mask is applied to the second group. A pattern 506 and a use ratio determination mask pattern 502 are applied.

  Finally, in the eighth pass (fourth return scan), the recording rate determination mask pattern 506 and the use ratio determination mask pattern 502 are applied to the first group, and the recording rate determination mask is applied to the second group. A pattern 506 and a use ratio determination mask pattern 501 are applied.

  By controlling the usage ratio of the adjacent nozzle rows in the same pass as described above, it becomes possible to avoid both the usage ratios of the adjacent nozzle rows in the same pass from being increased. Occurrence can be suppressed.

1 is a diagram illustrating a configuration of a recording unit of an ink jet recording apparatus according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a configuration of a recording head according to an embodiment of the invention. FIG. 2 is a block diagram illustrating a configuration of a recording head control block according to an embodiment of the present invention. It is a figure which shows an example of the usage-ratio determination mask pattern which concerns on one Embodiment of this invention. It is a figure which shows an example of the recording rate determination mask pattern in the 4-pass reciprocal recording which concerns on one Embodiment of this invention. 1 is a schematic block diagram of a control system of an ink jet recording apparatus according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Memory part 102 Output control part 103 Multipass / double head data generation part 104 1st recording head control part 105 2nd recording head control part 401,402 Recording head 501,502 Usage ratio determination mask pattern 503,504,505,506 Recording rate determination mask pattern

Claims (11)

In an inkjet recording method for recording an image by causing a recording head in which nozzle rows of each color corresponding to ink of each color are arranged along a scanning direction to scan a recording area of a recording medium,
In dividing the plurality of nozzle rows of the recording head into a plurality of groups, a grouping step of performing grouping so that adjacent nozzle rows belong to different groups;
A control step of controlling the use ratio of the nozzle rows in one group among the plurality of groups to be higher than the use ratio of the nozzle rows in the other group in the predetermined scan of the recording head;
And a recording step of performing recording on the recording region by the nozzle rows included in the plurality of groups in accordance with the controlled use ratio in the predetermined scanning.   The inkjet recording method according to claim 1, wherein each color nozzle row belonging to the one group is not included in the other group. In an ink jet recording method for recording an image by scanning a recording area of a recording medium with a recording head arranged so that nozzle rows of each color corresponding to ink of each color are symmetrical along the scanning direction.
When dividing the plurality of nozzle rows of the recording head into a plurality of groups, grouping is performed so that adjacent nozzle rows belong to different groups and the combinations of the color nozzle rows belonging to the different groups are the same. Grouping process,
A control step of controlling the use ratio of the nozzle rows in one group among the plurality of groups to be higher than the use ratio of the nozzle rows in the other group in the predetermined scan of the recording head;
And a recording step of performing recording on the recording region by the nozzle rows included in the plurality of groups in accordance with the controlled use ratio in the predetermined scanning. An image is obtained by scanning a recording area of a recording medium with a recording head in which nozzle rows corresponding to ink of each color are arranged in the scanning direction so that the order of color overlap is the same in the forward scanning and the backward scanning. In an inkjet recording method for recording,
A grouping step of performing grouping so that the nozzle rows adjacent to each other belong to different groups when dividing the plurality of nozzle rows of the recording head into a plurality of groups including at least two groups;
A control step of controlling the nozzle row usage ratio in one of the at least two groups to be higher than the nozzle row usage ratio in the other group in a predetermined scan of the recording head;
And a recording step of performing recording on the recording area by means of nozzle rows included in the plurality of groups in accordance with the controlled use ratio in the predetermined scanning.   5. The ink jet recording method according to claim 4, wherein the grouping step performs grouping so that the combinations of the color nozzle rows belonging to the different groups are the same.   6. The control process according to claim 1, wherein, in the plurality of groups, control is performed so that the usage ratio of a group having a head nozzle row of forward scanning of the recording head is increased. The ink jet recording method described in 1.   In the control step, in the forward scan as the predetermined scan, the usage ratio of the nozzle rows in the one group is defined as N, the usage ratio of the nozzle rows in the other group is defined as M (M <N), and 7. The use ratio of the nozzle rows in the one group is determined as M, and the use ratio of the nozzle rows in the other group is determined as N in the reverse scan different from the scan in the above-described scanning. The inkjet recording method as described.   In the control step, as a first mask pattern for determining a use ratio of nozzle rows of the same color in the same scan, a first mask pattern having a different use ratio is set for the same color nozzle rows of the different groups. 6. The control according to claim 3, wherein the use ratio of the nozzle rows belonging to the one group is controlled to be higher than the use ratio of the nozzle rows belonging to the other group. Inkjet recording method.   9. The recording process according to claim 8, wherein recording is performed based on ejection data obtained by performing thinning processing using the first mask pattern on image data corresponding to each of the plurality of groups. The ink jet recording method described in 1.   The recording step completes recording in the recording area by a plurality of scans using the first mask pattern, and the ejection data is recorded in the recording area for each scan. The inkjet recording method according to claim 9, wherein the inkjet recording method is generated by performing a thinning process on the image data using the second mask pattern to be allocated and the first mask pattern. In an inkjet recording apparatus that records an image by scanning a recording area of a recording medium with a recording head arranged so that nozzle rows of each color corresponding to ink of each color are symmetrical along the scanning direction.
When dividing the plurality of nozzle rows of the recording head into a plurality of groups, grouping is performed so that adjacent nozzle rows belong to different groups and the combinations of the color nozzle rows belonging to the different groups are the same. Grouping means,
Control means for controlling the use ratio of the nozzle rows in one group among the plurality of groups to be higher than the use ratio of the nozzle rows in the other group in the predetermined scan of the recording head;
An ink jet recording apparatus comprising: a recording unit configured to perform recording on the recording region by a nozzle row included in the plurality of groups according to the controlled usage ratio in the predetermined scanning.

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