JP5825840B2 - Inkjet recording apparatus and inkjet recording method - Google Patents

Description

  The present invention relates to an ink jet recording apparatus, an ink jet recording method, and a program that perform recording by ejecting ink from a recording head onto a recording medium.

  In a serial scan type ink jet recording apparatus that records an image with a reciprocating movement of the recording head in the main scanning direction, the recording head has a plurality of nozzles that can eject ink along a direction intersecting the main scanning direction. It is arranged. In a recording head in which a plurality of such nozzle arrays are arranged in the main scanning direction, an image is recorded by sequentially ejecting ink from the nozzle array located on the front side in the scanning direction of the recording head. The order is the order from the nozzle row located on the downstream side in the scanning direction toward the nozzle row located on the upstream side.

  In addition to the main droplet that landed on the recording medium and records an image, the ink that is ejected from the ejection ports that make up the nozzle includes a sub-droplet (satellite) that is smaller than the main droplet and a size that is even larger than the sub-droplet. And an ink mist that does not land on the recording medium. Part of the ink mist ejected from the ejection port returns to and adheres to the ejection port surface of the recording head where the ejection port is formed due to the vortex-like air current generated by the ejection of the ink. A part of the current flows toward the rear side in the scanning direction (upstream side in the scanning direction). A portion of the ink mist that has flowed to the rear side in the scanning direction may adhere to the discharge port surface of the nozzle row due to a vortex airflow generated by the nozzle row located on the rear side in the scanning direction (upstream side in the scanning direction). There is. As described above, not only the ink mist generated from the nozzle row but also the front side in the scanning direction (scanning direction) of the nozzle row is formed on the ejection port surface of the nozzle row on the rear side in the scanning direction (upstream side in the scanning direction). There is a possibility that ink mist generated from the nozzle row located on the downstream side) may adhere. In particular, ink mist generated from adjacent nozzle rows on the front side in the scanning direction (downstream side in the scanning direction) is highly likely to adhere.

  Normally, different types of ink are ejected from a plurality of nozzle arrays, and therefore, when these inks are mixed on the ejection port surface, various adverse effects may occur. For example, in an ink system that is fixed by mixing two types of ink in order to improve the fixability of the ink that has landed on the recording medium, there is a possibility that the ink may be mixed on the ejection port surface. That is, there is a possibility that the ejection portion is partially blocked by the fixing portion and the ink ejection direction is deviated or the ink cannot be ejected.

  In order to prevent such an adverse effect, Patent Document 1 adds a concave member in the scanning direction to the bottom surface of the carriage on which the recording head is mounted, so that there is no gap between the recording head and the recording medium. A configuration is described in which the air current is controlled to allow ink mist to escape to the outside of the recording head.

JP 2007-326234 A

  However, in the configuration described in Patent Document 1, since the processing of the carriage and the members are added, the configuration may be complicated and the cost may be increased. Further, since the shape of the bottom surface of the carriage is complicated, there is a possibility that the recording medium is easily jammed.

  An object of the present invention is to provide an ink jet recording apparatus, an ink jet recording method, and an ink jet recording method capable of avoiding the influence of ink mist by controlling the airflow between the recording head and the recording medium without adding any special mechanical processing. To provide a program.

The inkjet recording apparatus of the present invention includes a first ejection port array in which a plurality of ejection ports for ejecting a first type of ink are arranged in an arrangement direction, and a second type different from the first type. A plurality of ejection port arrays including at least a second ejection port array in which a plurality of ejection ports for ejecting ink are arranged in the arrangement direction are arranged side by side in a scanning direction intersecting the arrangement direction A head, scanning means for scanning the recording head relative to the unit area on the recording medium N times in the scanning direction, and N number of N of each of the plurality of ejection port arrays The recording medium is transported relative to the recording head in a transport direction intersecting the scanning direction by a distance corresponding to one of the ejection port groups, between scanning by the scanning unit. Conveying means for causing the plurality of discharges A setting means for setting a printing ratio for each of the N ejection port groups in the mouth row, and the N discharge nozzles according to the printing ratio set by the setting means in each of the N scans. Control means for controlling ink to be ejected from each of the outlet groups to the unit area, wherein the setting means is a first ejection port of the N ejection port groups. and the group, the near rather at one end of the plurality of outlet rows in the first discharge port the arrangement direction than the group, and, second outlet groups farther from the central portion of the plurality of outlet rows (I) the recording ratio of the second ejection port group in the first ejection port array is lower than the recording ratio of the first ejection port group in the first ejection port array. (Ii) the first discharge in the second discharge port array The recording ratio of the mouth group is lower than the recording ratio of the second outlet group in the second outlet array, and (iii) the first outlet group in the second outlet array The recording ratio is set such that the recording ratio is lower than the recording ratio of the first ejection port group in the first ejection port array.

The inkjet recording method of the present invention includes a first ejection port array in which a plurality of ejection ports for ejecting a first type of ink are arranged in an arrangement direction, and a second type different from the first type. A plurality of ejection port arrays including at least a second ejection port array in which a plurality of ejection ports for ejecting ink are arranged in the arrangement direction are arranged side by side in a scanning direction intersecting the arrangement direction An ink jet recording method for recording an image on a recording medium using a head, the scanning step of scanning the recording head relative to a unit area on the recording medium N times in the scanning direction; The recording medium is moved between scans in the scanning step by a distance corresponding to one discharge port group of N discharge port groups obtained by dividing each of the plurality of discharge port arrays into N. Previous to the recording head A transporting process for transporting relatively in the transporting direction intersecting the scanning direction, a setting process for setting a recording ratio for each of the N ejection port groups of the plurality of ejection port arrays, and the N scannings A control step of controlling the unit region to discharge ink from each of the N discharge port groups according to the recording ratio set by the setting step. The setting step includes a first discharge port group of the N discharge port groups and a position closer to one end of the plurality of discharge port arrays in the arrangement direction than the first discharge port group. And the second ejection port group far from the center of the plurality of ejection port arrays , (i) the recording ratio of the second ejection port group in the first ejection port array is The first discharge in the first discharge port array (Ii) the recording ratio of the first ejection port group in the second ejection port array is lower than that of the second ejection port group in the second ejection port group. (Iii) The recording ratio of the first ejection port group in the second ejection port array is equal to the recording ratio of the first ejection port group in the first ejection port array. The recording ratio is set to be lower than that.

  According to the present invention, in the two nozzle rows, by increasing the recording ratio of one of the corresponding nozzles and decreasing the recording ratio of the other, the recording head and the recording head are less likely to adhere to the recording head. The airflow to and from the medium can be controlled. Further, it is difficult to mix the ink mist generated from one of the two nozzle rows and the ink mist generated from the other, and the occurrence of adhesion of the mixture to the recording head or the like can be suppressed.

1 is a perspective view illustrating an overall configuration of an ink jet recording apparatus according to a first embodiment of the present invention. FIG. 2 is an explanatory diagram of an arrangement form of nozzle rows in the recording head of FIG. 1. FIG. 2 is a block configuration diagram of a control system of the ink jet recording apparatus of FIG. 1. It is explanatory drawing of a multipass recording system. It is explanatory drawing of the behavior of the ink mist between a recording head and a recording medium. (A) And (b) is explanatory drawing of the mask pattern for cyan ink and clear ink in the 1st Embodiment of this invention. It is explanatory drawing of the relationship between the ink mist of a clear ink and the ink mist of a cyan ink in the 1st Embodiment of this invention. (A), (b), (c), (d) is an explanatory diagram of mask patterns for clear ink, cyan ink, magenta ink, and yellow ink in the second embodiment of the present invention. . It is explanatory drawing of the mask pattern for clear ink and cyan ink in the 3rd Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a perspective view schematically showing the overall configuration of the ink jet recording apparatus of the present invention.

  In the figure, reference numeral 11 denotes a first recording head, which has a configuration in which an ink tank in which five kinds of ink described later are sealed and a nozzle row corresponding to each ink are integrated. Reference numeral 12 denotes a second recording head, which is configured in the same manner as the first recording head 11. In these recording heads 11 and 12 (hereinafter collectively referred to as “recording head 10”), the nozzle rows corresponding to the five types of ink are arranged so as to be symmetrically arranged in the main scanning direction (arrow X direction). Has been. A carriage 3 supports the recording head 10 and reciprocates in the main scanning direction indicated by an arrow X together with the recording head 10 during an image recording operation. The carriage 3 is located at the home position P during standby such as during a non-recording operation. Reference numeral 4 denotes a pair of paper feed rollers, which rotate in the direction of the arrow while sandwiching the recording medium 7 together with the auxiliary roller 5, thereby causing the recording medium 7 to cross the main scanning direction (in this example, orthogonal). Transport in the sub-scanning direction. Reference numeral 6 denotes a paper feed roller, which feeds the recording medium 7 when the recording medium 7 is rotated.

  During the recording operation, first, the carriage 3 located at the home position P moves in the forward direction of the arrow X1. While the recording heads 11 and 12 move in the forward direction together with the carriage 3, one of the recording heads 11 and 12 discharges ink onto the recording medium 7 based on the recording data, thereby recording an image (outward recording operation). ). After the forward recording to the end of the recording medium 7 is completed, the rollers 4, 5 and 6 convey the recording medium 7 by a predetermined amount in the sub-scanning direction indicated by the arrow Y (conveying operation). Thereafter, the carriage 3 starts moving in the backward direction indicated by the arrow X2. The recording heads 11 and 12 move in the backward direction together with the carriage 3, and the other of the recording heads 11 and 12 discharges ink onto the recording medium 7 based on the recording data, thereby recording an image (return path recording operation). ). After the return path recording to the end of the recording medium 7 is completed, the rollers 4, 5, 6 convey the recording medium 7 by a predetermined amount in the sub-scanning direction indicated by the arrow Y (conveying operation). In this manner, images are sequentially recorded on the recording medium 7 by repeating the forward recording operation, the transport operation, the backward recording operation, and the transport operation. In this example, as will be described later, a multi-pass recording method is employed in which an image is recorded by scanning the recording head 10 (11, 12) a plurality of times in the same area on the recording medium 7.

  FIG. 2 shows the arrangement relationship of the nozzle rows in the recording head 10. Each of the recording heads 11 and 12 is provided with a plurality of nozzle rows so as to be aligned in the scanning direction of the recording head.

  In the forward direction of the arrow X1, the first recording head 11 is positioned upstream and the second recording head 12 is positioned downstream thereof. The first recording head 11 has a clear ink, a cyan ink (C), a magenta ink (M), a yellow ink (Y), and a black ink (Bk) from the upstream side to the downstream side in the forward direction of the arrow X1. Are arranged in a nozzle array. In these nozzle arrays, a plurality of nozzles capable of ejecting ink are arranged in a direction intersecting (in the present example, orthogonal) with the main scanning direction. The nozzle is configured such that ink can be ejected from the ejection port using an ejection energy generating element such as an electrothermal conversion element (heater) or a piezo element. When the electrothermal conversion element is used, the ink is foamed by the heat generation, and the ink can be ejected from the ejection port using the foaming energy.

  In contrast to the first recording head 11, the second recording head 12 has a black ink (Bk), a yellow ink (Y), a magenta ink (M), and cyan from the upstream side toward the downstream side in the forward direction. Nozzle rows that eject ink (C) and clear ink are arranged. During the forward recording operation, the five types of ink are ejected from one of the first and second recording heads 11 and 12, and during the backward recording operation, the five types of ink from the other of the first and second recording heads 11, 12. Is discharged. This makes it possible to make the discharge order of the five types of ink the same in the forward recording operation and the backward recording operation, and to prevent color unevenness of the recorded image caused by the different discharge order. In the case of the main body, the first recording head 11 is used during the forward recording operation, and the second recording head 12 is used during the backward reading operation.

The clear ink is a transparent ink, and in the case of this example, four color inks of C, M, Y, and Bk including a color material (colored inks including Bk are referred to as color inks). It has the property of being fixed by mixing with any one of them. By mixing the clear ink and the color ink on the recording medium, a recorded matter having excellent weather resistance and scratch resistance can be produced. The clear ink can exert its effect to the maximum by landing on the recording medium before the color ink. Therefore, the nozzle rows that discharge clear ink are arranged on both the left and right sides in FIG. 2 so that the clear ink can be discharged before the color ink during the recording operation.
FIG. 3 is a schematic block diagram of the control system of the ink jet recording apparatus of the present invention. The recording apparatus receives recording information from the host computer 30 as a control signal. The recording information is temporarily stored in the input / output interface 21 in the recording apparatus, and at the same time, converted into data that can be processed in the recording apparatus, and then input to the CPU 22 that also serves as a recording head drive signal supply means. . Based on the control program stored in the ROM 23, the CPU 22 processes the data input to the CPU 22 using peripheral units such as the RAM 24 and converts it into data to be recorded (image data).

  The CPU 22 also supplies motor drive data for a drive motor 26 that conveys the recording medium 7 and moves the recording head 10 in synchronization with the image data in order to record the image data at a desired position on the recording medium 7. Generate. The image data and the motor drive data are output to the recording heads 11 and 12 and the drive motor 26 via the head drivers 27 and 28 and the motor driver 25, respectively. Thereby, an image is recorded at a controlled timing.

  The recording apparatus employs a multi-pass recording method in which an image is recorded by scanning the recording head 10 a plurality of times for the same recording area on the recording medium 7 as an image recording method. In the multi-pass recording method, since one recording line along the main scanning direction is recorded by ink ejected from a plurality of nozzles, the density due to a difference in ink ejection amount for each nozzle or a slight difference in ink ejection direction. Generation of unevenness can be suppressed.

  The multi-pass recording method will be described with reference to FIG. In the recording head 10 of this example, each of the five nozzle rows L that eject the five types of ink is formed by first and second nozzle rows L1 and L2. In the first nozzle row L1, a plurality of nozzles N are arranged at a predetermined pitch P along a direction intersecting with the main scanning direction (orthogonal in this example). Similarly, the second nozzle row L1 is also arranged in the second nozzle row L1. A plurality of nozzles N are arranged at a predetermined pitch P. The nozzles N of these nozzle rows L1, L2 are shifted by a half pitch (P / 2). As a result, the nozzle row L forms a nozzle row in which a plurality of nozzles N are arranged at (P / 2).

  Such a nozzle row L is divided into a plurality of nozzle groups according to the multi-pass printing method. In the case of a multi-pass recording method in which an image is recorded on the same area on the recording medium 7 by four scans of the recording head, that is, a 4-pass recording method, the first nozzle group G1 is used as shown in FIG. The fourth nozzle group G4 is divided into four. First, printing in the first pass is performed using the nozzles of the first nozzle group G1, and after the printing is finished, the recording medium 7 is conveyed in the sub-scanning direction by the length of the first nozzle group G1. Next, after the second pass printing is performed using the nozzles of the second nozzle group G2, the recording medium 7 is conveyed in the sub-scanning direction by the length of the second nozzle group G2. The third pass and the fourth pass are recorded in the same manner. Therefore, an image is recorded in the same area on the recording medium 7 in such four passes. Therefore, the image data is thinned into four by the four mask patterns M1, M2, M3, and M4, and the image is recorded by four passes based on the thinned image data. Mask patterns M1 to M4 in FIG. 4 are mask patterns for cyan ink, which will be described later. Each nozzle group is divided into two nozzle group portions, and the mask pattern thinning rate is set for each nozzle group portion. Is set.

  Next, the behavior of ink mist generated when ink is ejected will be described with reference to FIG. In order to simplify the explanation, FIG. 5 shows a state in which the first recording head 11 ejects ink from the two nozzle arrays LA and LB while moving in the backward direction of the arrow X2. The nozzle row LA is a nozzle row for discharging clear ink, and the nozzle row LB is a nozzle row for discharging cyan ink. During the backward recording, the nozzle row LA is located on the downstream side (left side in FIG. 5) of the backward direction of the arrow X2 along which the first recording head 11 moves, and the nozzle row LB on the upstream side (right side in FIG. 5). Is located.

  When ink is ejected from these nozzle arrays LA and LB, airflows A2 and B2 from the recording head 11 toward the recording medium 7 are generated. The airflows A2 and B2 spread toward the upstream side and the downstream side in the scanning direction after hitting the recording medium 7, the airflows A1 and B1 spreading downstream are spiral, and the airflows A3 and B3 spreading upstream are It flows upstream (right side in FIG. 5). Most of the clear ink ink mist generated from the nozzle array LA rides on the air currents A1 and A3 and does not land on the recording medium 7. Part of the ink mist riding on the airflow A1 adheres to the ejection port surface FA of the recording head 11. The discharge port surface FA is a surface on which nozzle discharge ports in the nozzle row LA are formed. The ink mist riding on the airflow A3 flows toward the nozzle row LB. Since the surface of the recording head 11 facing the recording medium 7 has a flat shape, the airflow A3 between the recording head and the recording medium is rectified, and the ink mist flowing on the airflow A3 is not disturbed. The form is flowed as it is in the nozzle row LB flow without being destroyed.

  When cyan ink is ejected from the nozzle row LB, the ink mist of the cyan ink exhibits the same behavior as the ink mist of the clear ink. The discharge port surface FB is a surface on which nozzle discharge ports in the nozzle row LB are formed. The airflow B1 includes ink mist of clear ink that flows on the airflow A3. Therefore, the ink mist of the clear ink and the ink mist of the cyan ink are mixedly attached to the ejection port surface FB. As described above, since the clear ink and the cyan ink adhere to each other when they are mixed, there is a possibility that the adhered matter accumulates on the ejection port surface FB, and the nozzles in the nozzle row LB cannot properly eject the ink.

  FIG. 6 is an explanatory diagram of mask patterns corresponding to the nozzle rows LA and LB. In the cyan ink nozzle row LB in FIG. 6A, for the nozzles located near the end in the vertical direction in the same figure, the recording ratio by the recording data thinned out by the corresponding mask pattern is set low. ing. The ink ejected from the nozzles located at the end of the nozzle row has a phenomenon that the ejection direction is inclined toward the center of the nozzle row due to the influence of the air flow caused by the ink ejection (also referred to as “end deflection”), The ink landing position may shift. In order to prevent such end deviation, the cyan ink nozzle row LB is set to have a low recording ratio due to the nozzles located closer to the ends, and in order to compensate for this, recording using the nozzles located closer to the center is performed. The ratio is set high.

  Specifically, as shown in FIG. 6A, mask patterns M1, M2, M3, and M4 corresponding to the first nozzle group G1 to the fourth nozzle group G4 of the nozzle row LB are used. The first nozzle group G1 is divided into two nozzle group parts G1A and G1B. Similarly, the second nozzle group G2 to the fourth nozzle group G4 are also divided into two nozzle group portions. The recording ratio by the recording data thinned out by the mask pattern M1 is 10% for the recording data corresponding to the nozzle group part G1A, and 20% for the recording data corresponding to the nozzle group part G1B. Similarly, the recording ratios based on the recording data thinned out by the mask patterns M2, M3, and M4 are set to two different values corresponding to two nozzle group portions, respectively. In the 4-pass printing method, the areas recorded by the nozzle group portions G1A, G2A, G3A, and G4A are the same area, so the total of the recording ratios corresponding to them is 100% (= 10 + 30 + 40 + 20 (%)). Similarly, the sum of the recording ratios corresponding to the areas recorded by the nozzle group parts G1B, G2B, G3B, G4B is 100% (= 20 + 40 + 30 + 10 (%)).

  On the other hand, in the nozzle array LA for clear ink in FIG. 6B, the recording ratio is set low for the nozzles located near the center, and in order to compensate for this, the recording ratio by the nozzles located near the ends is set. Is set high. Since the recording ratio of the nozzles located near the end of the nozzle row LA is high, there is a possibility that the landing position of the clear ink may be shifted due to the phenomenon of the end deflection described above. However, since the clear ink is transparent and the landing accuracy of the clear ink is not required to be as high as that of the color ink, the influence of the end deviation is extremely small.

  Specifically, as shown in FIG. 6B, mask patterns M11, M12, M13, and M14 corresponding to the first nozzle group G11 to the fourth nozzle group G14 of the nozzle array LA are used. The recording ratio by the recording data thinned out by the mask patterns M11, M12, M13, and M14 is different by two according to the nozzle group, similarly to the mask pattern for the nozzle LB in FIG. Is set to a value. The sum of the recording ratios corresponding to the areas recorded by the nozzle group portions G11A, G21A, G13A, and G14A is 100% (= 40 + 20 + 10 + 30 (%)). Similarly, the sum of the recording ratios corresponding to the areas recorded by the nozzle group portions G11B, G12B, G13B, and G14B is 100% (= 30 + 10 + 20 + 40 (%)).

  As described above, the recording ratio by the recording data thinned out by the mask patterns M1 to M4 for the nozzle LB in FIG. 6A is set to be low at both ends of the nozzle row LB and high at the center. The distribution of the recording ratio has a mountain shape. On the contrary, the recording ratio by the recording data thinned out by the mask patterns M11 to M14 for the nozzle LA in FIG. 6B is set to be high at both ends of the nozzle row LA and low at the center. The distribution of the recording ratio has a valley shape. As described above, the distribution shape of the recording ratio by the mask pattern for the nozzle LB and the distribution shape of the recording ratio by the mask pattern for the nozzle LA are opposite to each other so that the valley portion and the mountain portion correspond to each other. It has become.

  In the following, the effect obtained by making the distribution of the recording ratio in the opposite shape will be described.

  Two factors are related to the adhesion of ink mist to the ejection port surface of the recording head. The first is the amount of ink mist generated, and the second is the degree of ease with which the ink mist adheres to the ejection port surface. These two factors are greatly related to the recording ratio. The amount of ink mist generated increases as the recording ratio increases, and decreases as the recording ratio decreases. Further, the degree of easy ink mist adhesion to the ejection port surface increases as the recording ratio increases, and decreases as the recording ratio decreases. That is, as the recording ratio decreases, the spiral airflows A1 and B1 in FIG. 5 weaken, and naturally the rising airflow toward the discharge port surfaces FA and FB also weakens, so that the ink mist adheres to the discharge port surfaces FA and FB. It becomes difficult to do.

  FIG. 7 is an explanatory diagram of the relationship between these two elements and the recording ratio based on the mask pattern. In the nozzle arrays LA and LB, a group of nozzles positioned near the upper and lower ends in FIG. 6 is referred to as an “end nozzle group”, and a group of nozzles positioned near the center in the vertical direction in FIG. To do.

  Since the mask pattern for cyan ink has a mountain shape, the recording ratio of the central nozzle group in the nozzle row LB is high, and a large amount of ink mist is generated from the central nozzle group, which easily adheres to the ejection port surface FB. . On the other hand, since the mask pattern for clear ink has a valley shape, the recording ratio by the central nozzle group in the nozzle array LA is low, and the amount of ink mist generated from the central nozzle group is small. Thus, since the ink mist of the clear ink discharged from the central nozzle group of the nozzle row LA is small, the amount of the ink mist adhering to the discharge port surface FB on the nozzle row LB side is reduced. On the contrary, there is much ink mist of the clear ink ejected from the end nozzle group of the nozzle row LA. However, the ink mist of the clear ink hardly adheres to the discharge port surface FB on the nozzle row LB side because the spiral airflow B1 generated by the cyan ink discharged from the end nozzle group of the nozzle row LB is weak.

  As a result, it is possible to reduce the amount of the clear ink ink mist that is ejected from the nozzle array LA to the ejection port surface FB on the nozzle array LB side. Therefore, it is difficult for the fixed matter in which the clear ink and the cyan ink are mixed to be generated on the discharge port surface FB, and the ink discharge state of the nozzle row LB can be maintained well while avoiding the influence of the end deviation. it can.

(Second Embodiment)
In the first embodiment, the recording ratio of the mask pattern corresponding to the center or end of the nozzle row is set to be the highest. That is, the mask pattern is set so that the recording ratio is targeted around the center of the nozzle row. However, as shown in FIG. 8, the position of the nozzle corresponding to the mask pattern having the highest recording ratio may be set for each type of ink.

  FIG. 8A shows the distribution of the recording ratio in the nozzle row L (S) that discharges clear ink, and the recording ratio by the nozzles corresponding to a part of the mask pattern M23 and a part of the mask pattern M24 is set to the lowest. Has been. FIG. 8B shows the distribution of the recording ratio in the nozzle row L (C) that discharges cyan ink, and the recording ratio by the nozzles corresponding to a part of the mask pattern M33 and a part of the mask pattern M34 is set to be the highest. Has been. FIG. 8C shows the distribution of the printing ratio in the nozzle row L (M) that ejects magenta ink, and the printing ratio by the nozzles corresponding to a part of the mask pattern M42 and a part of the mask pattern M43 is set to the highest. Has been. FIG. 8D shows the distribution of the recording ratio in the nozzle row L (Y) that discharges yellow ink, and the recording ratio by the nozzles corresponding to a part of the mask pattern M51 and a part of the mask pattern M52 is set to be the highest. Has been. Occurrence of color unevenness can be prevented by shifting the peak position where the recording ratio becomes maximum for each type of ink. The distribution shape of the recording ratio of the nozzle array for clear ink ejection is opposite to the distribution ratio of the recording ratio of the nozzle array for cyan ink ejection adjacent to the nozzle array on the upstream side in the scanning direction. . The reason for this is to suppress the adhesion of the clear ink ink mist to the cyan ink ejection nozzle row to which the clear ink ink mist is most likely to adhere, as in the embodiment described above.

  In this example, as in the above-described embodiment, from the downstream side to the upstream side in the scanning direction, the nozzle row for clear ink, the nozzle row for cyan ink, the nozzle row for magenta ink, and for yellow ink The nozzle row and the black ink nozzle row are adjacent to each other in sequence. The recording ratio of the clear ink nozzle row L (S) is a valley-shaped distribution shape, and the recording ratio of the cyan ink nozzle row L (C) is a mountain-shaped distribution shape, which are in reverse shapes. ing. Further, in the case of this example, the nozzle group portions G21A and G24B having the former maximum recording ratio (40%) correspond to the nozzle group portions 31A and 34B having the latter minimum recording ratio (10%). The former nozzle group portions G23B and G24A having the minimum recording ratio (10%) correspond to the nozzle group portions 33B and 34A having the latter maximum recording ratio (40%). Further, the nozzle group portions G21B and G22A having the second highest recording ratio (30%) correspond to the nozzle group portions 31B and 32A having the second lowest recording ratio (20%). Further, the nozzle group portions G22B and G23A having the second lowest recording ratio (20%) correspond to the nozzle group portions 32B and 33A having the second highest recording ratio (30%).

  Further, regarding the nozzle rows L (C) and L (M) for cyan ink and magenta ink, the positions of the nozzles of the maximum recording ratio (40%) are shifted from each other, and the minimum recording ratio ( The positions of the nozzles of 10%) are all located closer to the end in consideration of the end deviation. That is, the nozzle group portions G33B and G34B having the maximum recording ratio of the former and the nozzle group portions G42B and G43A having the maximum recording ratio are shifted, and the nozzle group portions G31A and G31A having the minimum recording ratio are arranged at both ends. G34B, G41A, and G44B are located.

  Further, regarding the nozzle rows L (M) and L (Y) for magenta ink and yellow ink, the positions of the nozzles having the maximum recording ratio (40%) are shifted from each other. Further, the positions of the nozzles having the minimum recording ratio (10%) are all located closer to the end portion in consideration of the end deviation. That is, the nozzle group portions G42B and 43A with the former maximum recording ratio and the nozzle group portions 51B and 52A with the latter maximum recording ratio are shifted, and the nozzle group portions G41A and G41A with the minimum recording ratio are located at both ends. G44B, G51A, and G54B are located.

  The relationship between the nozzle rows for yellow ink and black ink is the relationship between the nozzle rows L (C) and L (M) for cyan ink and magenta ink, and the nozzle row L for magenta ink and yellow ink. The relationship can be the same as the relationship between (M) and L (Y).

  In this way, by relating the recording ratios of the three nozzle rows adjacent in the transport direction, the nozzle row on the downstream side in the transport direction affects the upstream nozzle row while avoiding the influence of the end deviation of the color ink. The influence of ink mist can be suppressed small.

(Third embodiment)
In the embodiment described above, the nozzle row is divided into a plurality of regions (nozzle group and nozzle group portion), and the recording ratio is set stepwise for each region. In the present embodiment, the recording ratio is set without dividing the nozzle row into a plurality of regions.

  In FIG. 9, the dotted line indicates the recording ratio set by the mask pattern for cyan ink, and the solid line indicates the recording ratio set by the mask pattern for clear ink. The horizontal axis in FIG. 8 shows a plurality of nozzles arranged along the nozzle row. In this example, a total of 1280 nozzles having nozzle numbers 1 to 1280 are arranged. The recording ratio using cyan ink is the same as in the above-described embodiment, in order to avoid the influence of the end deviation, the recording ratio of the nozzles located at both ends of the nozzle array is lowered, and in order to complement it, The recording ratio of the nozzle located at the center is set high. However, the distribution of the recording ratio is represented by a curve, and is a distribution shape that smoothly changes instead of the step-like distribution shape as in the above-described embodiment. That is, the recording ratio is set so as to gradually increase from the both ends of the nozzle row toward the center. As a result, it is possible to prevent the occurrence of streak-like image defects that are likely to occur due to the nozzles at the connecting portions where the recording ratio changes stepwise. The recording ratio with clear ink has a distribution shape opposite to the recording ratio with cyan ink. The recording ratio is set so as to gradually decrease from both ends of the nozzle row toward the center.

(Other embodiments)
The distribution shape of the recording ratio may be a shape including a plurality of peak portions or a plurality of valley portions. In addition, in at least two nozzle rows of the plurality of nozzle rows provided in the print head, if there is a correspondence between the peak portion of one print ratio distribution shape and the valley portion of the other print ratio distribution shape Good. The two nozzle rows may eject different inks, may eject the same ink, and may not necessarily be adjacent in the scanning direction.

3 Carriage 7 Recording medium 10 Recording head 22 CPU
LA Clear ink ejection nozzle row LB Cyan ink ejection nozzle row M1, M2, M3, M4 Mask pattern for cyan ink M11, M12, M13, M14 Mask pattern for clear ink

Claims (18)

A first ejection port array in which a plurality of ejection ports for ejecting the first type of ink are arranged in the arrangement direction, and a plurality of inks for ejecting a second type of ink different from the first type A recording head in which a plurality of discharge port arrays including at least a second discharge port array in which the discharge ports are arranged in the arrangement direction are arranged side by side in a scanning direction intersecting the arrangement direction;
Scanning means for scanning the recording head relative to the unit area on the recording medium N times in the scanning direction;
The recording medium is scanned between the scans by the scanning means by a distance corresponding to one discharge port group among N discharge port groups obtained by dividing each of the plurality of discharge port arrays into N. Transport means for transporting the recording head relative to a transport direction intersecting the scanning direction;
Setting means for setting a recording ratio for each of the N discharge port groups of the plurality of discharge port arrays;
Control means for controlling each of the N ejection openings to eject ink from each of the N ejection orifice groups in accordance with the recording ratio set by the setting means in each of the N scans. A recording device,
The setting means, said the first outlet group of the N outlet groups, rather close to one end of the first discharge opening the plurality of outlet rows in the array direction than the group And (i) a recording ratio of the second discharge port group in the first discharge port row is the second discharge port group far from the center of the plurality of discharge port rows . (Ii) the recording ratio of the first ejection port group in the second ejection port group is lower than the recording rate of the first ejection port group in one ejection port array. (Iii) the recording ratio of the first ejection port group in the second ejection port group is lower than the recording rate of the second ejection port group in the ejection port array. An ink jet recording apparatus, wherein the recording ratio is set to be lower than a recording ratio of the first ejection port group in the row.   The setting means is configured such that the recording ratio of the second ejection port group in the first ejection port array is lower than the recording ratio of the second ejection port group in the second ejection port array. The inkjet recording apparatus according to claim 1, wherein the recording ratio is set. The setting means is configured such that a position in the arrangement direction is the second position with respect to a plurality of discharge port groups between the first discharge port group and the second discharge port group in the first discharge port row. so that the closer to the discharge port groups low printing ratio, the ink jet recording apparatus according to claim 1 or 2, characterized in that for setting the recording ratios. The setting means is configured such that a position in the arrangement direction is the second position with respect to a plurality of discharge port groups between the first discharge port group and the second discharge port group in the second discharge port row. 4. The ink jet recording apparatus according to claim 1, wherein the recording ratio is set so that the recording ratio is higher as it is closer to the ejection port group. 5. The N of the discharge port groups, said proximal rather the other end of said plurality of discharge port arrays at a first of said array direction than the outlet groups, and further from the central portion of the plurality of outlet rows A third discharge port group;
(I) the recording ratio of the third ejection port group in the first ejection port array is greater than the recording ratio of the first ejection port group in the first ejection port array; (Ii) The recording ratio of the first ejection port group in the second ejection port array is lower than the recording ratio of the third ejection port group in the second ejection port array. The inkjet recording apparatus according to any one of claims 1 to 4, wherein the recording ratio is set as described above.   The setting means is configured such that the recording ratio of the third ejection port group in the first ejection port array is lower than the recording ratio of the third ejection port group in the second ejection port array. The inkjet recording apparatus according to claim 5, wherein the recording ratio is set. The plurality of ejection port arrays includes a third ejection port array in which a plurality of ejection ports for ejecting a third type of ink different from the first and second types of ink are arranged in the arrangement direction. In addition,
The N discharge port groups further include a fourth discharge port group farther from the one end of the plurality of discharge port arrays in the arrangement direction than the second discharge port group,
The setting means includes: (i) a recording ratio of the second ejection port group in the third ejection port array is greater than a recording ratio of the fourth ejection port group in the third ejection port array. (Ii) The recording ratio of the fourth ejection port group in the second ejection port array is lower than the recording ratio of the second ejection port group in the second ejection port array. (Iii) The recording ratio of the fourth outlet group in the second outlet array is lower than the recording ratio of the fourth outlet group in the third outlet array. The ink jet recording apparatus according to claim 1, wherein the recording ratio is set.   (I) the recording ratio of the first ejection port group in the third ejection port array is greater than the recording ratio of the first ejection port group in the first ejection port array; (Ii) The recording ratio of the fourth ejection port group in the first ejection port array is lower than the recording ratio of the fourth ejection port group in the third ejection port array. The inkjet recording apparatus according to claim 7, wherein the recording ratio is set as described above. Said first outlet group is located in the central portion in the arrangement direction of the plurality of ejection ports in the column, said second outlet group is of one in the direction of arrangement of said plurality of outlet rows The ink jet recording apparatus according to claim 1, wherein the ink jet recording apparatus is located at an end portion.   In the setting means, the sum of the recording ratios in each of the N ejection port groups in the first ejection port array is substantially 100%, and each of the N ejection port groups in the second ejection port array is performed. The inkjet recording apparatus according to any one of claims 1 to 9, wherein the recording ratio is set so that a sum of recording ratios is approximately 100%.   The setting means sets the recording ratio so that the sum of the recording ratio of the first ejection port array and the recording ratio of the second ejection port array is substantially equal to each other in each of the N ejection port groups. The inkjet recording apparatus according to claim 1, wherein the inkjet recording apparatus is set. Based on the data corresponding to the image to be recorded in the unit area and the N mask patterns corresponding to each of the N ejection port groups, the ink of the controller by the control means in each of the N scans. It further has a generating means for generating N pieces of print data used when performing ejection,
The inkjet recording according to any one of claims 1 to 11, wherein the setting unit sets the recording ratio based on a thinning rate in each of the N mask patterns. apparatus. The first type of ink is an ink containing a color material,
The inkjet recording apparatus according to claim 1, wherein the second type of ink is an ink that does not contain a color material. The first type of ink is an ink containing a first color material,
The second type of ink is an ink that does not contain a coloring material,
9. The ink jet recording apparatus according to claim 7, wherein the third type of ink is an ink containing a second color material different from the first color material.   The inkjet recording apparatus according to claim 1, wherein the first ejection port array is disposed upstream of the second ejection port array in the scanning direction. .   The first and second ejection port arrays are arranged at positions adjacent to each other in the scanning direction in the plurality of ejection port arrays. Inkjet recording apparatus. A first ejection port array in which a plurality of ejection ports for ejecting the first type of ink are arranged in the arrangement direction, and a plurality of inks for ejecting a second type of ink different from the first type A plurality of ejection port arrays including at least a second ejection port array in which the ejection ports are arranged in the arrangement direction are arranged on a recording medium using a recording head in which the ejection ports are arranged in a scanning direction intersecting the arrangement direction. An inkjet recording method for recording an image, comprising:
A scanning step of causing the recording head to scan N times relative to the unit area on the recording medium in the scanning direction;
The recording medium is moved between scans in the scanning step by a distance corresponding to one discharge port group of N discharge port groups obtained by dividing each of the plurality of discharge port arrays into N. A transport step of transporting the recording head in a transport direction that intersects the scanning direction;
A setting step of setting a recording ratio for each of the N discharge port groups of the plurality of discharge port arrays;
A control step of controlling each of the N scans to discharge ink to each of the unit areas from each of the N discharge port groups according to the recording ratio set by the setting step. A recording method,
Said setting step, the N and the first outlet group of the outlet groups, near rather in said array direction than the first outlet group in one end portion of said plurality of discharge port arrays And (i) a recording ratio of the second discharge port group in the first discharge port row is the second discharge port group far from the center of the plurality of discharge port rows . (Ii) the recording ratio of the first ejection port group in the second ejection port group is lower than the recording rate of the first ejection port group in one ejection port array. (Iii) the recording ratio of the first ejection port group in the second ejection port group is lower than the recording rate of the second ejection port group in the ejection port array. An ink jet recording method, wherein the recording ratio is set to be lower than a recording ratio of the first ejection port group in the row.   A program for causing a computer of an ink jet recording apparatus to function in order to execute the ink jet recording method according to claim 17.

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