JP2018144355A - Inkjet recording device and inkjet recording method - Google Patents

Abstract

An object of the present invention is to suppress the influence of an air flow generated by a suction-type platen during recording on the leading end and trailing end of a recording medium, thereby improving the quality of a recorded image and suppressing adhesion of floating ink droplets to the recording medium. about.
In consideration of the influence of an air flow generated by a suction-type platen, a mask pattern used at the time of recording on the front end portion and the rear end portion of the recording medium is made different.
[Selection] Figure 10

Description

  The present invention relates to a so-called multi-pass inkjet recording apparatus and inkjet recording method.

  A multi-pass recording apparatus that records an image on a predetermined area of a recording medium with a plurality of scans of an ink jet print head is based on print data thinned out by a mask pattern for each scan of the print head. Ink is ejected from the recording head. Patent Document 1 describes a multipass recording apparatus that records an image using two recording heads on a recording medium that is conveyed while being attracted to a suction platen. In this recording apparatus, an image is recorded on the edge of the recording medium by the other recording head after the image is recorded by one recording head. The mask pattern used at that time is set so that the recording rate by the former recording head (corresponding to the thinning rate of recording data) is smaller than the recording rate by the latter recording head.

JP 2013-91207 A

  In a recording apparatus using a suction-type platen as in the cited document 1, at the time of recording on the leading end portion and the trailing end portion of the recording medium in the conveyance direction of the recording medium, it is in the vicinity of the suction opening of the platen for sucking the recording medium. The front and rear end portions of the recording medium are positioned. In such a state, an air flow is likely to be generated between the recording head and the recording medium, and the landing position of the ink droplets ejected from the recording head is disturbed by the air flow, and the recording medium of the recording medium due to the attachment of the floating ink droplets is disturbed. Contamination may occur.

  It is an object of the present invention to improve the quality of a recorded image by suppressing the influence of an air flow generated by a suction type platen during recording on the leading end portion and the trailing end portion of the recording medium, and to attach floating ink droplets to the recording medium. It is to suppress.

  The inkjet apparatus according to the present invention includes a transport unit configured to transport a recording medium in a predetermined transport direction while sucking the recording medium to the platen, and a plurality of discharge ports capable of ejecting ink, and the transport direction at a position facing the platen. In order to record an image on a predetermined area of the recording medium with a plurality of N times of scanning of the recording head and the recording head movable in the intersecting scanning directions, the N times of the recording head with respect to the predetermined area Control means for ejecting ink from the ejection ports based on recording data thinned out at a predetermined thinning rate by a mask pattern for each scanning of the mask pattern, wherein the mask pattern is transported A first mask pattern for thinning out recording data of an image recorded on the leading end of the recording medium in the direction, and in the transport direction A second mask pattern for thinning out recording data of an image recorded on the rear end portion of the recording medium, and the first scan of the N scans of the recording head with respect to the front end portion The first sum of the thinning rates of the first mask pattern in a predetermined number M (M ≦ N−1) of scans that are continuous from the first scan and include the first scan is calculated as follows. Of the N scans, the second mask pattern is less than a third sum of the thinning rates in the predetermined number M of scans that are continuous from the first scan and include the first scan, Of the N scans of the recording head with respect to the leading end, the second thinning rate of the first mask pattern in the predetermined number M of scans that continues to the Nth scan and includes the Nth scan. Total continuously until the N-th scanning and greater than the fourth sum of the thinning rate of the second mask pattern in a scanning of the predetermined number of times M that comprises the scanning of the N-th, and wherein the.

  According to the present invention, the effect of the airflow generated by the suction platen during recording on the front end portion and the rear end portion of the recording medium is made different by using different mask patterns for recording on the front end portion and the rear end portion of the recording medium. It can be kept small. As a result, the quality of the recorded image can be improved, and adhesion of floating ink droplets to the recording medium can be suppressed.

1 is a perspective view of an ink jet recording apparatus according to a first embodiment of the present invention. FIG. 2 is a side sectional view of the ink jet recording apparatus of FIG. 1. FIG. 2 is a block diagram of a control system in the ink jet recording apparatus of FIG. 1. FIG. 2 is a top view of a platen in the ink jet recording apparatus of FIG. 1. It is an enlarged view of the V circle part of FIG. It is explanatory drawing of the airflow produced at the time of recording with respect to the front-end | tip part of a recording medium. It is explanatory drawing of an example of the mask pattern used for a multipass system. It is explanatory drawing of the recording operation | movement with respect to the front-end | tip part and rear-end part of a recording medium. It is explanatory drawing of the airflow produced at the time of recording with respect to the front-end | tip part and rear-end part of a recording medium. It is explanatory drawing of the mask pattern used in the 1st Embodiment of this invention. FIG. 3 is an explanatory diagram of a nozzle group of a recording head according to the first embodiment of the present invention. It is explanatory drawing of the relationship between the recording operation | movement with respect to the front-end | tip part and rear-end part of a recording medium, and a recording rate. It is explanatory drawing of the recording process and mask pattern in 2nd Embodiment of this invention. It is explanatory drawing of the recording process and mask pattern in 3rd Embodiment of this invention. It is explanatory drawing of the recording process and mask pattern in 4th Embodiment of this invention. It is explanatory drawing of the recording process and mask pattern in 5th Embodiment of this invention. It is explanatory drawing of the recording process and mask pattern in 6th Embodiment of this invention. It is explanatory drawing of the recording process and mask pattern in 7th Embodiment of this invention. It is explanatory drawing of the recording process and mask pattern in 8th Embodiment of this invention.

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

(First embodiment)
[Schematic configuration of the entire device]
First, a schematic configuration of the ink jet recording apparatus 1 according to the present embodiment will be described with reference to FIGS. 1 and 2.

  In the inkjet recording apparatus 1, a pressure plate 3 of a supply device (paper supply device) 2 that supplies a recording medium such as paper is rotatably supported by a frame body 4 of the supply device 2, and a recording medium is stacked on the upper surface thereof. . When the recording medium is supplied, the sheet feeding roller 6 is rotated by the sheet feeding motor 5 as a driving source, and the pressure plate 3 is rotated toward the sheet feeding roller 6 by the pressure plate spring 7 to be stacked on the pressure plate 3. Is pressed against the paper feed roller 6. Further, by rotating the paper feed roller 6, only the recording medium positioned at the top of the stacked recording media is separated and fed. The recording medium fed in this way is fed to the transport roller 8 by further rotation of the paper feed roller 6. The front end of the recording medium is released from a position where the sensor lever 9 faces the sheet sensor 10 by pressing and rotating the sensor lever 9 disposed between the paper feed roller 6 and the conveyance roller 8. Thereby, the sheet sensor 10 detects the leading edge of the recording medium. Further, when the rear end of the recording medium passes the position of the sensor lever 9, the sensor lever 9 enters a position facing the sheet sensor 10. Thereby, the sheet sensor 10 detects the trailing edge of the recording medium.

  The pinch roller 12 is urged against the conveying roller 8 by the pinch roller spring 11 via the pinch roller shaft 25 and the pinch roller holder 26. The pinch roller 12 is in contact with the conveyance roller 8 on the downstream side in the recording medium conveyance direction from the apex (the highest point) of the conveyance roller 8. In this way, the recording medium is conveyed while being sucked by the suction-type platen 14 by the pinch roller 12 coming into contact with the conveyance roller 8 at a position deviated to the downstream side in the conveyance direction from the apex of the conveyance roller 8. .

  After the leading edge of the recording medium is detected by the sheet sensor 10, the recording medium is conveyed by a predetermined amount by the paper feed roller 6. As a result, the leading edge of the recording medium abuts on a conveyance roller nip formed between the conveyance roller 8 and the pinch roller 12. The recording medium is further conveyed by the paper feed roller 6 and the leading end portion of the recording medium is curved, whereby the leading end of the recording medium is pressed against the conveying roller nip, and the skew of the recording medium is corrected.

  The conveyance roller nip is positioned a predetermined distance above the upper surface of the platen 14, and the rotation center of the pinch roller 12 is offset downstream of the perpendicular passing through the rotation center of the conveyance roller 8 in the recording medium conveyance direction. That is, the common tangent line at the conveyance roller nip between the conveyance roller 8 and the pinch roller 12 intersects the upper surface of the platen 14. With such a configuration, the recording medium is pressed against the upper surface of the platen 14, and the facing distance between the recording surface of the recording head 13 and the recording medium is kept constant.

  After the image recording position adjustment operation (registration operation) is completed, the recording medium is conveyed onto the platen 14 by the conveying roller 8, and is opposed to the ink discharge port forming surface 28 of the recording head 13 by the upper surface of the platen 14. Supported in position. The conveyance roller 8 is rotated via a timing belt 16 by a conveyance motor 15 which is a driving source. By ejecting ink droplets from the ejection ports of the recording head 13 mounted on the carriage 17 while the carriage 17 moves in the scanning direction that intersects (in this example, “orthogonal”) with the conveyance direction of the recording medium. The image is recorded on the recording medium sucked on the upper surface of the platen 14. The recording head 13 is formed with a plurality of ejection openings capable of ejecting ink, and these ejection openings extend in a direction intersecting with the scanning direction (in this example, “orthogonal”). Form a row. The carriage 17 is supported by a guide shaft 18 and a guide rail 19 so as to be movable in a direction crossing the recording medium conveyance direction, and is driven by a carriage motor 20 via a timing belt 21.

[Data processor configuration]
FIG. 3 is a block diagram showing the configuration of the control system in the inkjet recording apparatus 1 of the present embodiment. The control system of this example includes an image data input unit 31, an operation unit 32, a CPU 33 that performs various processes, a storage medium 34 that stores various data, a RAM 35, an image data processing unit 36, an image recording unit 37 that performs image output, and A bus line 38 for transferring various data is included. The recording information storage memory of the storage medium 34 includes an information storage unit 34a related to the type of the recording medium, an information storage unit 34b related to ink used for recording, an information storage unit 34c related to the environment such as temperature and humidity during recording, and the like. A storage unit 34d for various control program groups is included.

  The image data processing unit 36 creates binary ink ejection data (data corresponding to ink ejection and non-ejection) from the input multivalued image data. Based on the binary ejection data, the image recording unit 37 ejects ink from an ink ejection port corresponding to the ejection data, thereby forming dots on the recording medium. The bus line 38 transmits address signals, data, control signals, and the like in the recording apparatus.

  The image data input unit 31 inputs multi-value image data from an image input device such as a scanner and a digital camera, and multi-value image data stored in a hard disk of a personal computer. The operation unit 32 includes various keys for instructing the setting of various parameters and the start of recording. The CPU 33 controls the entire recording apparatus according to various programs in the storage medium. The storage medium 34 stores programs such as a control program and an error processing program for operating the recording apparatus. All operations of the recording apparatus in the present embodiment are operations according to this program. As the storage medium 34 for storing such a program, ROM, FD, CD-ROM, HD, memory card, magneto-optical disk, or the like can be used. The RAM 35 is used as a work area for various programs in the storage medium 34, a temporary save area for error processing, and a work area for image processing. The RAM 35 can also be used for copying various tables in the storage medium 34, changing the contents of the tables, and advancing image processing while referring to the changed tables.

[Configuration of platen]
4 is a plan view of the platen 14, and FIG. 5 is an enlarged perspective view of a V circle portion of the platen 14 in FIG. On the support surface of the platen 14 that supports the recording medium, a plurality of suction islands 41 (41a to 41l) that are shifted in the width direction of the recording medium are formed. A recess is formed in the suction island 41, and a suction hole 42 is formed in the recess. The suction holes 42 in the plurality of suction islands 41 are connected to a suction fan (not shown) through the inside of the casing of the platen 14. The recording medium is supported so as to be transported in a state of being attracted to the support surface of the platen 14 by the negative suction force acting in the recess of the suction island 41 through the suction hole 42.

  An edgeless groove 43 is formed around the suction island 41 in the platen 14, and an ink absorber is spread in the edgeless groove 43. When recording an image on a recording medium without borders, ink is ejected to a region slightly larger than the size of the recording medium in order to record the image without leaving a margin on at least one side of the recording medium. . At that time, the ink ejected from the edge of the recording medium is absorbed by the ink absorber in the marginless groove 43.

[Relationship between platen and airflow]
When the platen 14 as in this example is employed, an air flow may be generated around the platen 14 and the recording medium due to the negative pressure of the suction fan.

  FIG. 6 is an explanatory diagram of airflow generated during an image recording operation on the recording medium W. Although the recording medium W is adsorbed by the suction island 41, the rib (the supporting surface of the recording medium) around the concave portion of the suction island 41 and the surface of the recording medium are not completely in close contact with each other, and a slight gap therebetween. An airflow F1 is generated through which the external air flows into the suction island 41 in a negative pressure state. As shown in FIG. 6, the air flow F <b> 1 bypasses the end W <b> 1 of the recording medium W and generates an air flow F <b> 2 in the space between the upper surface of the recording medium W and the recording head 13.

  There are two main effects of these airflows on the recording medium. One is that the ink droplet ejected from the ejection port of the recording head 13 receives the force of the airflow based on the recording data, and the landing position of the ink droplet on the recording medium W may deviate from the original landing position. It is. When the landing position is shifted as described above, the image quality may be deteriorated. The other is that floating ink droplets (small ink droplets that are secondary generated when ink droplets are ejected from the ejection port and float without landing on the recording medium) flow into the gap 44 on the airflow. At this time, a part of the recording medium may adhere to the back surface (the lower surface in FIG. 6) of the recording medium. Thus, when a part of floating ink droplet adheres to a recording medium, a recording medium will be contaminated. An end W1 of the recording medium W in FIG. 6 is a leading end portion in the conveyance direction (arrow A direction) of the recording medium W. However, a similar airflow is generated at the other end of the recording medium W.

[Multipass recording method]
FIG. 7 is an explanatory diagram of a general multi-pass recording method. For convenience of explanation, the number of nozzles corresponding to ink per color is 16, and the recording mode is a four-pass recording mode in which an image of a predetermined area of the recording medium is completed by four passes (scanning). The 16 nozzles are divided into four nozzle groups corresponding to the fourth pass region from the first pass region. Each nozzle group includes four nozzles. Multi-pass mask patterns P1, P2, P3, and P4 corresponding to the respective areas are set in advance. In these mask patterns, pixels that can be recorded by ejecting ink from the nozzles are shown in black. Yes. The mask patterns corresponding to the four nozzle groups are in a complementary relationship with each other, and all of them can be recorded by superimposing them.

  First, in the first pass, 25% of pixels can be recorded by the mask pattern P1, and in the second pass thereafter, an additional 25% of pixels can be recorded by the mask pattern P2. Similarly, in the third pass and the fourth pass, 25% of pixels can be recorded, and finally 100% of pixels can be recorded. In general, the mask patterns are arranged so as to be dispersed so that the recordable pixels are not adjacent to each other. The recording medium is conveyed in the conveying direction indicated by the arrow A in FIG. 7 by the length corresponding to the width of the nozzle group (the length corresponding to 4 nozzles in FIG. 7) between the passes. Actual ink ejection is performed based on ejection data created by a logical product (AND operation) of a mask pattern and print data. Thus, an image is recorded based on the image data thinned out using the mask pattern every four scans. By adopting such a multi-pass method, the same area of the recording medium is recorded by a plurality of nozzle groups in a plurality of passes. For this reason, it is possible to suppress the occurrence of density unevenness and streaks in the recorded image by suppressing the influence of the variation in the ink ejection performance specific to each nozzle and the variation in the conveyance accuracy of the recording medium.

[Multi-pass recording for the front and rear edges of the recording medium]
FIG. 8 is an explanatory diagram in the case where an image is recorded on the recording areas at the leading end and the trailing end of the recording medium W by the multipass recording method. In this example, the number of nozzles corresponding to ink per color is 128, and the recording mode is a 4-pass recording mode.

  FIG. 8A shows the positional relationship between the recording area at the leading end of the recording medium W, the used nozzles in the nozzle row 46 of the recording head 13. First, after the supply operation of the recording medium W is completed, the recording medium W is transported to a position where the suction island 41 of the platen 14 is completely covered by the recording medium W. Thereby, the negative pressure suction force by the suction fan is used to suppress the leading edge of the recording medium W from being lifted and to prevent contact with the recording head 13. In the case of this example, by such initial conveyance of the recording medium W, a distance L0 of 24 nozzles is provided upstream in the conveyance direction from the downstream end of the nozzle row 46 in the conveyance direction (arrow Y direction). The leading end of the recording area in the recording medium W is transported to the shifted position. The image recording operation starts from this position. At the time of recording on the recording area at the leading end of the recording medium W, the transport amount L1 of the recording medium W between passes is made smaller than the transport amount L2 during normal recording. Specifically, the transport amount L1 between passes from the first pass to the fourth pass is a length of 8 nozzles, and the transport amount L2 between passes during normal printing is a length of 32 nozzles. . From the first scan to the fourth scan, the number of nozzles to be used is increased by 32 nozzles (24 nozzles upstream in the transport direction and 8 nozzles downstream in the transport direction), while the image data is thinned out by the mask pattern. Record an image based on it. After the fifth scan, an image is recorded using all 128 nozzles, and the conveyance amount of the recording medium is L2, which is the length of the usual 32 nozzles.

  FIG. 8B shows the positional relationship between the recording area at the rear end of the recording medium W, the used nozzles in the nozzle row 46 of the recording head 13. From the time when the recording area at the rear end of the recording medium W passes the position of the upstream end in the transport direction of the nozzle row 46, the transport amount of the recording medium between passes is the same as in the case of FIG. Is reduced to a length L1 corresponding to 8 nozzles, which is 1/4 of the normal transport amount L2. Further, while reducing the number of nozzles to be used by 32 nozzles (8 nozzles upstream in the transport direction and 24 nozzles downstream in the transport direction), an image is recorded based on the image data thinned out by the mask pattern. The nozzles used in the final N-th scan are 2 nozzles, which are the total of 24 nozzles in the third nozzle group and 8 nozzles in the fourth nozzle group, and the final fourth pass printing is performed by these.

[Influence of airflow during recording on the leading and trailing edges of the recording medium]
FIG. 9 is a diagram for explaining the influence of the airflow around the platen 14 generated by the suction fan during multi-pass recording with respect to the recording area at the front and rear end portions of the recording medium W. FIG. 9 is a side view of the recording head 13 and the platen 14 viewed from the width direction of the recording medium W. The arrow in the figure indicates the air current, and the thickness of the arrow qualitatively indicates the strength of the air current.

  FIG. 9A is an explanatory diagram in the case where the recording area at the leading end of the recording medium W is recorded by the 4-pass recording method as shown in FIG. 8A, and at the time of the first scan in FIG. 8A. To represents the airflow during the fourth scan. The leading end of the recording medium W is at a position closest to the platen 14 at the time of the first scan, and from the platen 14 as the recording medium W is sequentially conveyed to become the second scan, the third scan, and the fourth scan. Move away. During recording on the recording area at the leading end of the recording medium W, the air flow F2 toward the leading end of the recording medium W becomes stronger as the leading end of the recording medium W is closer to the platen 14. That is, the airflow F2 during the first scan is the largest, and the airflow F2 during the second to fourth scans gradually decreases. For this reason, the influence of the airflow F2 on the ink droplets ejected from the nozzle row 46 is greatest during the first scan and gradually decreases during the second to fourth scans. Therefore, when recording on the recording area at the tip, the ink droplets ejected during the first half of the scan are more strongly affected by the airflow. As the influence of the airflow increases, the landing position of the ink droplet shifts, the floating ink droplet 45 (see FIG. 6) flows into the gap 44, and adheres to the recording medium W.

  FIG. 9B is an explanatory diagram in the case where the recording area at the rear end portion of the recording medium W is recorded by the 4-pass recording method as shown in FIG. 8B, and the number (N) in FIG. -3) The air flow generated from the scan to the Nth scan is shown. During these four scans, the rear end of the recording medium W is at the position farthest from the platen 14 during the (N-3) th scan, and the (N-2) th scan, the (N-1) th scan, As the Nth scan is reached, the platen 14 is approached. During recording on the recording area at the rear end of the recording medium W, the air flow F3 toward the rear end of the recording medium W becomes stronger as the rear end of the recording medium W approaches the platen 14. That is, the airflow F2 during the first scan is the largest, and the airflow F2 during the second to fourth scans gradually decreases. Therefore, contrary to the case of FIG. 9A, the influence of the air flow F3 on the ink droplets ejected from the nozzle row 46 gradually increases as it proceeds from the (N-3) th scan to the Nth scan. . Accordingly, during recording on the recording area at the rear end, the ink droplets ejected during the latter half of the scan are more strongly affected by the airflow. As the influence of the airflow increases, the landing position of the ink droplet shifts, the floating ink droplet 45 (see FIG. 6) flows into the gap 44, and adheres to the recording medium W.

  In the multi-pass recording method of the present embodiment, in consideration of the influence of the air flow at the time of recording at the leading and trailing ends of such a recording medium, the deviation of the landing position of the ink droplet, the flow of the floating ink droplet 45 into the gap 44 is performed. Further, the occurrence of adhesion to the recording medium W is suppressed.

[Multipass recording method of this embodiment]
FIG. 10 is an explanatory diagram of a mask pattern used in the multipass printing method of the present embodiment. A mask pattern PA1, PA2, PA3, PA4 in FIG. 10A is an example of a mask pattern used for recording an image on a recording area at the leading end of the recording medium. ) Is 10%, 20%, 30% and 40%. Mask patterns PB1, PB2, PB3, and PB4 in FIG. 10B are examples of mask patterns used during normal recording on other recording areas except for the front and rear end portions of the recording medium. Both are 25%. Mask patterns PC1, PC2, PC3, and PC4 in FIG. 10C are examples of mask patterns used for recording an image on the recording area at the rear end of the recording medium, and their recording rates are 40% and 30%. %, 20% and 10%.

  Hereinafter, the recording operation for the front end portion of the recording medium using the mask pattern of FIG. 10, the normal recording operation for the intermediate portion of the recording medium, and the recording operation for the rear end portion of the recording medium will be specifically described. In this example, as in the case of FIG. 8, the image is recorded in the 4-pass recording mode using the recording head 13. The 128 nozzles in the recording head 13 are divided into first, second, third, and fourth nozzle groups G10, G20, G30, and G40 every 32 nozzles. The first nozzle group G10 is divided into four groups G11, G12, G13, and G14 each having eight nozzles, and the second nozzle group G20 is divided into four groups G21, G22, G23, and G24 each having eight nozzles. It is done. Similarly, the third and fourth nozzle groups G30 and G40 are divided into four groups of eight nozzles.

(Recording operation for the tip of the recording medium)
FIG. 12A is an explanatory diagram of an image recording operation with respect to the recording area at the leading end of the recording medium W. The positional relationship between the recording medium and the recording head and the conveyance amount of the recording medium between passes are shown in FIG. The same as in the case of (a). In this example, borderless recording is performed on the recording medium W using a mask pattern as shown in FIG.

  As will be described later, with respect to the first unit recording area (first recording area) from the front end of the recording medium, the mask of FIG. 10A having a recording rate of 10%, 20%, 30%, and 40%. A set of patterns PA1, PA2, PA3, PA4 is used. Also, for the first pass, second pass, third pass, and fourth pass recording for the second unit recording area (second recording area) from the leading edge of the recording medium, the recording rate is 15%, 25%, 30 %, 30%, and a set of mask patterns (not shown) that are complementary to each other is used. For the first pass, second pass, third pass, and fourth pass recording for the third unit recording area (third recording area) from the leading edge of the recording medium, the recording rate is 20%, 25%, 25%, A set of 30% mask patterns (not shown) that are complementary to each other is used. Further, in the recording of the first pass, the second pass, the third pass, and the fourth pass after the fourth unit recording area from the front end of the recording medium, the recording rate is equal to 25% as shown in FIG. A set of mask patterns PB1, PB2, PB3, PB4 is used.

  In the first scan, an image of the first pass is recorded by the nozzle groups G32, G33, G34, and G41 using the mask pattern PA1 having a recording rate of 10% in the first recording area. In the second scan, an image of the second pass is recorded by the nozzle groups G33, G34, G41, and G42 using the mask pattern PA2 with a recording rate of 20% in the first recording area. At the same time, for the second recording area, the first pass is performed by the nozzle groups G23, G24, G31, and G32 using a mask pattern (not shown) having a recording rate of 15% that is intermediate between the recording rates of the mask patterns PA1 and PA2. Record images.

  In the third scan, an image of the third pass is recorded by the nozzle groups G34, G41, G42, and G43 using the mask pattern PA3 with a recording rate of 20% in the first recording area. At the same time, a second pass image is recorded by the nozzle groups G24, G31, G32, and G33 using a mask pattern (not shown) having a recording rate of 25% in the second recording area. At the same time, the first pass image is recorded by the nozzle groups G14, G21, G22, and G23 in the third recording area using a mask pattern (not shown) having a recording rate of 20%.

  In the fourth scan, an image of the fourth pass is recorded by the nozzle groups G41, G42, G43, and G44 using the mask pattern PA4 with a recording rate of 40% in the first recording area. At the same time, an image of the third pass is recorded by the nozzle groups G31, G32, G33, and G34 using a mask pattern (not shown) having a recording rate of 30% in the second recording area. At the same time, the second pass image is recorded by the nozzle groups G21, G22, G23, and G24 using a mask pattern (not shown) having a recording rate of 25% in the third recording area. At the same time, an image of the first pass is recorded by the nozzle groups G11, G12, G13, and G14 using the mask pattern PB1 having a recording rate of 25% in the fourth recording area.

  In the fifth scan, a fourth pass image is recorded by the nozzle groups G41, G42, G43, and G44 using a mask pattern (not shown) having a recording rate of 30% in the second recording area. At the same time, a third pass image is recorded by the nozzle groups G31, G32, G33, and G34 using a mask pattern (not shown) having a recording rate of 25% in the third recording area. At the same time, the second pass image is recorded by the nozzle groups G21, G22, G23, and G24 using the mask pattern PB2 having a recording rate of 25% in the fourth recording area. At the same time, the first pass image is recorded by the nozzle groups G11, G12, G13, and G14 using the mask pattern PB1 having a recording rate of 25% in the fifth recording area.

  In the sixth scan, a fourth pass image is recorded by the nozzle groups G41, G42, G43, and G44 using a mask pattern (not shown) having a recording rate of 30% in the third recording area. At the same time, an image of the third pass is recorded by the nozzle groups G31, G32, G33, and G34 using a mask pattern PB3 (not shown) having a recording rate of 25% in the fourth recording area. At the same time, the second pass image is recorded by the nozzle groups G21, G22, G23, and G24 using the mask pattern PB2 having a recording rate of 25% in the fifth recording area. At the same time, the image of the first pass is recorded by the nozzle groups G11, G12, G13, and G14 using the mask pattern PB1 having a recording rate of 25% in the sixth recording area.

  In the seventh scan, an image of the fourth pass is recorded by the nozzle groups G41, G42, G43, and G44 using the mask pattern PB4 having a recording rate of 25% in the fourth recording area. At the same time, an image of the third pass is recorded by the nozzle groups G31, G32, G33, and G34 using a mask pattern PB3 (not shown) having a recording rate of 25% in the fifth recording area. At the same time, the second pass image is recorded by the nozzle groups G21, G22, G23, and G24 using the mask pattern PB2 having a recording rate of 25% in the sixth recording area. At the same time, the image of the first pass is recorded by the nozzle groups G11, G12, G13, and G14 using the mask pattern PB1 having a recording rate of 25% in the seventh recording area.

  From the eighth scan to the N-6th scan, the same recording operation as the seventh scan is repeated.

  As described above, the images of the first pass, the second pass, the third pass, and the fourth pass in the first print area are mask patterns PA1, PA2, PA3 having a print rate of 10%, 20%, 30%, and 40%. Record using PA4. Also, the images of the first pass, the second pass, the third pass, and the fourth pass in the second recording area are recorded using a mask pattern (not shown) having a recording rate of 15%, 25%, 30%, and 30%. . In addition, the images of the first pass, the second pass, the third pass, and the fourth pass in the third recording area are recorded using a mask pattern (not shown) having a recording rate of 20%, 25%, 25%, and 30%. .

  As described above, in the recording area at the leading end of the recording medium, the influence of the airflow is relatively large when the first pass image is recorded, and the influence of the airflow is relatively small when the fourth pass image is recorded. In the present embodiment, with respect to the recording area at the leading end of the recording medium, the recording rate at the time of recording the images of the first pass and the second pass, which are relatively large in the influence of the air current, is reduced, and the influence of the air current is relatively small. Increases the recording rate at the time of recording the third and fourth pass images. Therefore, the average degree of influence of the airflow received by all the ink droplets ejected from the recording head is compared with the case where all of the recording rates at the time of recording the images of the first pass to the fourth pass are set to 25%. It can be kept small. As a result, it is possible to improve the quality of an image recorded in the recording area at the leading end of the recording medium, and it is possible to suppress the occurrence of dirt on the recording medium due to the adhesion of floating ink droplets.

(Recording operation for the rear end of the recording medium)
FIG. 12B is an explanatory diagram of an image recording operation with respect to the recording area at the rear end of the recording medium W. The positional relationship between the recording medium and the recording head, and the conveyance amount of the recording medium between passes are shown in FIG. This is the same as in the case of 8 (b). In this example, borderless recording is performed on the recording medium W using a mask pattern as shown in FIG.

  As will be described later, for the first unit recording area (Nth recording area) from the rear end of the recording medium, the recording rate is 40%, 30%, 20%, 10% in FIG. A set of mask patterns PA1, PA2, PA3, PA4 is used. The recording rate is 30% and 30% for the first pass, the second pass, the third pass, and the fourth pass with respect to the second unit recording area (N-1th recording area) from the rear end of the recording medium. %, 25%, and 15%, and sets of mask patterns (not shown) that are complementary to each other are used. For the first pass, second pass, third pass, and fourth pass recording for the third unit recording area (N-3th recording area) from the rear end of the recording medium, the recording rate is 30%, 25%, A set of mask patterns (not shown) having a complementary relationship of 25% and 20% is used. In addition, the recording rate is uniform for the first pass, the second pass, the third pass, and the fourth pass for the recording from the rear end of the recording medium to the third unit recording area (the N-3th recording area). A set of mask patterns PB1, PB2, PB3, and PB4 shown in FIG.

  Up to the N-5th scan, images are recorded by the nozzle groups G10, G20, G30, and G40 using the mask patterns PB1, PB2, PB3, and PB4 as in the seventh scan of FIG.

  In the N-4th scan, an image of the first pass is recorded by the first group G10 using a mask pattern (not shown) having a recording rate of 30% in the N-1th recording area. At the same time, a second pass image is recorded by the second nozzle group G20 using the mask pattern PB2 having a recording rate of 25% in the N-2th recording area. At the same time, an image of the third pass is recorded by the third nozzle group G30 using the mask pattern PB3 having a recording rate of 25% in the N-3th recording area. At the same time, a fourth pass image is recorded by the fourth nozzle group G40 using the mask pattern PB4 having a recording rate of 25% in the N-4th recording area.

  In the N-3th scan, an image of the first pass is recorded by the first slip group G10 using the mask pattern PC1 with a recording rate of 40% in the Nth recording area. At the same time, a second pass image is recorded by the second nozzle group G20 using a mask pattern (not shown) having a recording rate of 30% in the N-1th recording area. At the same time, the image of the third pass is recorded by the third nozzle group G30 using the mask pattern PB3 having a recording rate of 25% in the N-2th recording area. At the same time, an image for the fourth pass is recorded by the fourth nozzle group G40 using the mask pattern PB4 having a recording rate of 25% in the N-3th recording area.

  In the N-2th scan, an image of the second pass is recorded by the group of slips G12, G13, G14, G21 using the mask pattern PC2 with a recording rate of 30% in the Nth recording area. At the same time, an image of the third pass is recorded by the nozzle groups G22, G23, G24, and G31 using a mask pattern (not shown) having a recording rate of 25% in the N-1th recording area. At the same time, a fourth pass image is recorded by the nozzle groups G32, G33, G34, and G41 using a mask pattern (not shown) having a recording rate of 20% in the N-2th recording area.

  In the (N-1) th scan, an image of the third pass is recorded by the slip groups G13, G14, G21, and G22 using the mask pattern PC3 with a recording rate of 20% in the Nth recording area. At the same time, the fourth pass image is recorded by the nozzle groups G23, G24, G31, and G32 using a mask pattern (not shown) having a recording rate of 15% in the N-1th recording area. In the final Nth scan, an image of the fourth pass is recorded in the Nth recording area by using the mask group PC4 with a recording rate of 10% by the nozzle groups G14, G21, G22, and G23.

  As described above, the images of the first pass, the second pass, the third pass, and the fourth pass in the Nth recording area are mask patterns PC1, PC2, PC3 with a printing rate of 40%, 30%, 20%, and 10%. Record using PC4. Further, the images of the first pass, the second pass, the third pass, and the fourth pass in the N-1th recording area use a mask pattern (not shown) having a printing rate of 30%, 30%, 25%, and 15%. Record. In addition, the images of the first pass, the second pass, the third pass, and the fourth pass in the N-2th recording area use a mask pattern (not shown) with a printing rate of 30%, 25%, 25%, and 20%. Record.

  As described above, in the area at the rear end of the recording medium, the influence of the air current is relatively large when recording the fourth pass image, contrary to the case of the front end area. The influence of airflow during image recording is relatively small. In the present embodiment, with respect to the recording area at the tip of the recording medium, the recording rate at the time of recording the images of the third pass and the fourth pass that are relatively affected by the airflow is reduced, and the effect of the airflow is relatively increased. Increases the recording rate at the time of recording the first pass and second pass images. Therefore, the average degree of influence of the airflow received by all the ink droplets ejected from the recording head is compared with the case where all of the recording rates at the time of recording the images of the first pass to the fourth pass are set to 25%. It can be kept small. As a result, the quality of the image recorded in the recording area at the rear end of the recording medium can be improved, and the occurrence of contamination of the recording medium due to adhesion of floating ink droplets can be suppressed.

(Recording operation to the center of the recording medium)
From the seventh scan in FIG. 12A to the N-6th scan in FIG. 12B, the recording rate is equal to 25 in the recording from the first pass to the fourth pass with respect to the central recording area of the recording medium. % Mask patterns PB1 to PB4 shown in FIG. 10B are used. When recording at the central portion of the recording medium, unlike the recording at the front and rear end portions of the recording medium, there is no change in air flow, so there is no need to change the recording rate. The recording rate 25% of the mask pattern PB1 is an intermediate value between the recording rate of the mask pattern PA1 and the recording rate of the mask pattern PC1, and the recording rate of 25% of the mask pattern PB2 is the recording rate of the mask pattern PA2. This is an intermediate value from the recording rate of PC2. Similarly, the recording rate 25% of the mask pattern PB3 is an intermediate value between the recording rate of the mask pattern PA3 and the recording rate of the mask pattern PC3, and the recording rate of 25% of the mask pattern PB4 is the recording rate of the mask pattern PA4. And an intermediate value between the recording rate of the mask pattern PC4. By using such a mask pattern, it is possible to suppress an abrupt change in the recording rate and suppress the occurrence of density unevenness and streak-like defects in the recorded image that accompany switching of the mask pattern.

(Second Embodiment)
In the configuration of the first embodiment, the present embodiment further controls the recording operation for the recording area at the front and rear end portions in accordance with the suction force of the suction fan for the platen 14.

  FIG. 13A is a flowchart for explaining control according to the suction force of the suction fan for the platen 14. Upon receiving the recording job, the CPU 33 of the recording apparatus 1 first acquires a mask pattern (mask pattern for normal area) used for recording in the intermediate portion of the recording medium (step S1), and stores it in the memory. Thereafter, the CPU 33 obtains information on whether or not the suction fan for the platen 14 is operating during the execution of the recording job, and determines whether or not the suction fan is driven during the recording operation (whether the suction fan is ON or OFF). (Step S2). When the suction fan is driven (ON) during the recording operation, the execution flag of the control (mask pattern switching control) for switching the mask pattern at the time of recording the leading and trailing ends of the recording medium is set to ON (step S3), the process proceeds to step S4. In step 4, information on the strength of the suction force of the suction fan is acquired. In the case of this example, the number of rotations corresponding to the strength of the suction force of the suction fan is acquired. The CPU 33 refers to a mask pattern table prepared in advance, and a mask pattern for the front and rear end regions (mask pattern for the recording region at the front end portion and the rear end portion) corresponding to the acquired rotation speed of the suction fan. Is stored in the memory (step S5).

  FIG. 13B is an explanatory diagram of the relationship between the number of rotations of the suction fan and the corresponding mask pattern. As the number of rotations of the suction fan increases, such as 50%, 70%, and 100%, the influence of the airflow on the recording area at the front and rear end portions of the recording medium increases. Therefore, the mask pattern for the leading end of the recording medium decreases the recording rate used when recording the image of the first pass as the rotational speed of the suction fan increases, so that the recording rate from the first pass to the fourth pass is reduced. Increase the difference. On the other hand, the mask pattern for the rear end of the recording medium decreases the recording rate used when recording the image of the fourth pass as the rotational speed of the suction fan increases, and the recording rate from the first pass to the fourth pass Increase the difference.

  Thus, after preparing the mask pattern used for recording operation, recording operation is started (step S7). On the other hand, if it is determined in step S2 that the suction fan is not driven (OFF) during the recording operation, the mask pattern switching control execution flag is set to OFF (step S6), and then the recording operation is started (step S6). Step S7).

  In step 7, a recording operation corresponding to ON / OFF of the execution flag of the mask pattern switching control is performed. That is, when the execution flag of the mask pattern switching control is set to ON, the first embodiment uses the mask patterns for the normal area and the front and rear end areas stored in the memory in steps S1 and S5. The same recording operation as in the case of is performed. On the other hand, when the execution flag of the mask pattern switching control is set to OFF, the mask pattern is not switched during the recording of the front and rear ends. Therefore, an image is recorded on all recording areas including the normal area and the front and rear end areas using the mask pattern for the normal area stored in the memory in step S1.

(Third embodiment)
In this embodiment, in the configuration of the first embodiment, the recording operation for the recording area at the front and rear end portions is further performed in accordance with the recording mode for recording with margins or without margins on the recording medium. Control.

  FIG. 14A is a flowchart for explaining the control according to the recording form (recording with margin / recording without margin). Description of steps (S1, S2, S3, S6, S7) similar to those in FIG. 13 described above will be omitted. In this embodiment, the CPU 33 determines in step S21 whether the recording form of the recording job is bordered recording or borderless recording. Then, the CPU 33 refers to a mask pattern table prepared in advance, and obtains a mask pattern for the front and rear end areas (mask pattern for the recording areas of the front end portion and the rear end portion) corresponding to the determined recording form. Then, it is stored in the memory (step S22).

  FIG. 14B is an explanatory diagram of the relationship between the recording form (recording with margin / recording without margin) and the corresponding mask pattern. In the case of borderless recording, a stronger airflow is affected in the borderless recording area at the front and rear end portions of the recording medium. For this reason, the mask pattern for the front end in the case of borderless recording has a smaller recording rate that is used when recording the first pass image than the mask pattern for the front end in the case of bordered recording. Increase the difference in recording rate from pass 4 to pass 4. On the other hand, the mask pattern for the rear end in the case of borderless recording has a lower recording rate used for recording the image of the fourth pass than the mask pattern for the rear end in the case of bordered recording. The difference in the recording rate from the first pass to the fourth pass is increased.

(Fourth embodiment)
In the present embodiment, in the configuration of the first embodiment, the recording operation for the recording area at the front and rear end portions is further controlled according to the recording duty at the front and rear end portions of the recording medium, which is the target area for mask pattern switching control. To do. The recording duty corresponds to the amount of ink ejected per unit area.

  FIG. 15A is a flowchart for explaining the control according to the recording duty at the front and rear end portions. Description of steps (S1, S2, S3, S6, S7) similar to those in FIG. 13 described above will be omitted. In the present embodiment, the CPU 33 calculates the recording duty at the front and rear ends based on the image recording data in step S31. When an image is recorded using a plurality of colors of ink, the recording duty for each ink color is summed. Then, the CPU 33 refers to a mask pattern table prepared in advance, obtains a mask pattern for the front and rear end region corresponding to the calculated recording duty of the front and rear end, and stores it in the memory (step S32). ).

  FIG. 15B is an explanatory diagram of the relationship between the recording duty at the front and rear end portions and the corresponding mask pattern. As the recording duty at the front and rear ends increases, the amount of floating ink droplets 45 increases, and the recording medium is more likely to be stained. Therefore, the mask pattern for the leading end of the recording medium has a smaller recording rate used when recording the first pass image as the recording duty of the leading end is higher, and the recording rate from the first pass to the fourth pass is reduced. Increase the difference. On the other hand, the mask pattern for the rear end of the recording medium decreases the recording rate used when recording the image of the fourth pass as the recording duty of the front end increases, and the recording rate from the first pass to the fourth pass Increase the difference.

(Fifth embodiment)
In the present embodiment, in the configuration of the first embodiment, the recording operation for the recording area at the front and rear end portions is further controlled in accordance with the facing distance between the recording medium and the recording head during the recording operation.

  FIG. 16A is a flowchart for explaining control according to the facing distance between the recording medium and the recording head. Description of steps (S1, S2, S3, S6, S7) similar to those in FIG. 13 described above will be omitted. In this embodiment, CPU33 acquires the information regarding the opposing space | interval of a recording medium and a recording head in step S41. For example, when the thickness of the recording medium is constant, the information regarding the facing distance is information regarding the height of the recording head facing the recording medium. Then, the CPU 33 refers to a mask pattern table prepared in advance, obtains a mask pattern for the leading and trailing edge areas corresponding to the facing distance between the recording medium and the recording head, and stores it in the memory (step S42). ).

  FIG. 16B is an explanatory diagram of the relationship between the facing distance between the recording medium and the recording head and the corresponding mask pattern. As the facing distance between the recording medium and the recording head is larger, the ejected ink droplets are more strongly affected by the air flow, and the recording quality of the image may be degraded. In the case of this example, the height of the recording head corresponds to the facing distance between the recording medium and the recording head. For this reason, the mask pattern for the leading end of the recording medium in this example reduces the recording rate used when recording the image of the first pass as the height of the recording head increases. Increase the difference in recording rate. On the other hand, the mask pattern for the rear end of the recording medium decreases the recording rate used when recording the image of the fourth pass as the height of the recording head increases, thereby increasing the recording rate from the first pass to the fourth pass. Increase the difference.

(Sixth embodiment)
In the present embodiment, in the configuration of the first embodiment, the recording area of the front and rear end portions is further determined depending on whether or not the recording image for the front and rear end portions of the recording medium includes fine lines such as characters or ruled lines. Controls the recording operation for.

  FIG. 17A is a flowchart for explaining the control of the recording operation in the present embodiment. Description of steps (S1, S2, S3, S6, S7) similar to those in FIG. 13 described above will be omitted. In the present embodiment, the CPU 33 determines whether or not an attribute indicating that a character or a ruled line is included in the image data recorded on the front and rear end portions of the recording medium in step S51. Then, the CPU 33 refers to the mask pattern table prepared in advance, and determines the multi-pass mask for the front and rear end areas (mask pattern for the recording areas of the front end portion and the rear end portion) corresponding to the determined attribute information. It is acquired and stored in the memory (step S52).

  FIG. 17B is an explanatory diagram of the relationship between the presence / absence of a fine line attribute (character / thin line attribute) such as a character or ruled line, and a mask pattern. When characters or ruled lines are included in the recorded image for the leading and trailing edges of the recording medium, the ink droplets are easily affected by the air flow, and the characters are crushed or the ruled lines are disturbed due to the disorder of the ink droplet landing positions. There is a fear. For this reason, the mask pattern for the leading end of the recording medium in this example has a character / thin line attribute included in the image data recorded on the leading end of the recording medium. The recording rate to be used is reduced to increase the difference in recording rate from the first pass to the fourth pass. On the other hand, the mask pattern for the rear end portion of the recording medium is used when the image of the fourth pass is recorded when the image data recorded on the rear end portion of the recording medium includes the character / thin line attribute. The recording rate is decreased to increase the recording rate difference from the first pass to the fourth pass.

(Seventh embodiment)
In the present embodiment, in the configuration of the first embodiment, the recording operation for the recording area at the front and rear end portions is further controlled according to a recording mode that can be set by a user or the like.

  FIG. 18A is a flowchart for explaining the control of the recording operation in the present embodiment. Description of steps (S1, S2, S3, S6, S7) similar to those in FIG. 13 described above will be omitted. In the present embodiment, in step S61, the CPU 33 acquires information related to the set recording mode and selectively uses a mask pattern corresponding to the recording mode. That is, the CPU 33 refers to a mask pattern table prepared in advance to obtain a multi-pass mask for the front and rear end areas corresponding to the recording mode (mask pattern for the recording areas of the front end portion and the rear end portion), It is stored in the memory (step S62).

  FIG. 18B is an explanatory diagram of the relationship between the recording mode and the mask pattern. When a recording mode such as a recording mode for line drawing (line drawing mode) is selected for recording an image containing a lot of fine lines or characters, another recording mode such as a recording mode for photos (photo mode) is selected. In contrast, the ink droplets are more susceptible to airflow. For this reason, in the line drawing mode, the characters are crushed or the fine lines such as ruled lines are likely to be disturbed due to the disordered landing positions of the ink droplets. When the line drawing mode is selected, the mask pattern for the leading end of the recording medium has a smaller recording rate used when recording the first pass image than when the photo mode is selected. The difference in the recording rate from the first pass to the fourth pass is increased. On the other hand, the mask pattern for the trailing edge of the recording medium has a lower recording rate when recording the fourth pass image when the line drawing mode is selected than when the photo mode is selected. The difference in the recording rate from the first pass to the fourth pass is increased.

(Eighth embodiment)
In the configuration of the first embodiment, the present embodiment further controls the recording operation for the recording area at the front and rear end portions according to the type of the recording medium.

  FIG. 19A is a flowchart for explaining the control of the recording operation in the present embodiment. Description of steps (S1, S2, S3, S6, S7) similar to those in FIG. 13 described above will be omitted. In the present embodiment, the CPU 33 acquires information regarding the type of the recording medium in step S71. Then, the CPU 33 refers to a mask pattern table prepared in advance and obtains a multi-pass mask for the front and rear end areas (mask pattern for the recording areas of the front end portion and the rear end portion) corresponding to the type of the recording medium. Then, it is stored in the memory (step S72).

  FIG. 19B is an explanatory diagram of the relationship between the type of recording medium and the mask pattern. A recording medium that is as rigid as fine art paper and is less likely to be attracted to the platen 14 has a gap 44 (see FIG. 6) between the suction island 41 of the platen 14 and the recording medium when the recording medium is conveyed. It becomes large and the recording medium is likely to become dirty. Therefore, the mask pattern for the leading end of the recording medium has a lower recording rate when recording the first pass image when using fine art paper than when using glossy paper with lower rigidity. Thus, the difference in recording rate from the first pass to the fourth pass is increased. On the other hand, the mask pattern for the rear end portion of the recording medium has a smaller recording rate used for recording the fourth pass image when fine art paper is used than when glossy paper is used. The difference in recording rate from the first to the fourth pass is increased. The type of the recording medium may be selected by the user, or may be automatically determined by a sensor or the like.

(Other embodiments)
In the present invention, the recording rate of the mask pattern (recording data thinning rate) used at the time of recording on the leading end portion and the trailing end portion of the recording medium is not limited to the above-described example. When an image is recorded on the recording medium by a plurality of N scans, the thinning rate of the mask pattern (first mask pattern) used when recording the front end portion and the mask pattern (second mask) used when recording the rear end portion The pattern) thinning rate should be in the following relationship. For convenience of explanation, the first, second, third, and fourth totals A1, A2, B1, and B2 of the thinning rate are defined as follows.

  A1: Of the N scans of the recording head with respect to the leading end, the first mask pattern is thinned out in a predetermined number M (M ≦ N−1) of scans that are continued from the first scan and include the first scan. Total of rates.

  A2: The total of the thinning ratios of the first mask patterns in a predetermined number M of scans that are continuous up to the Nth scan among the N scans of the recording head with respect to the leading end portion and include the Nth scan.

  B1: Total of thinning ratios of the second mask pattern in a predetermined number M of scans that are continued from the first scan and include the first scan among the N scans of the recording head with respect to the rear end.

  B2: Sum of thinning rates of the second mask pattern in a predetermined number M of scans that are continuous up to the Nth scan out of N scans of the recording head with respect to the rear end portion and include the Nth scan.

  The first total A1 of the thinning rates is smaller than the third total B1 (A1 <B1), and the second total A2 of the thinning rates is larger than the fourth B2 (A2> B2). The first and second mask patterns should be at least such that the former thinning rate in the first scan is smaller than the latter thinning rate, and the former thinning rate in the Nth scan is larger than the latter thinning rate. . This is because the influence of the airflow is greatly affected in the first scan at the time of recording the front end portion and the Nth scan at the time of recording the rear end portion. Further, in the first and second mask patterns, the first sum A1 of the thinning rate is smaller than the second sum A2 (A1 <A2), and the third sum B1 of the thinning rate is smaller than the fourth B2. Is also large (B1> B2). The first mask pattern tends to increase the decimation rate from the first scan to the Nth scan, and the second mask pattern tends to decrease the decimation rate from the first scan to the Nth scan. It is desirable to be.

  The mask pattern includes a mask pattern having a recording rate of 0% in a predetermined pass. Further, a mask pattern having a different recording rate may be assigned to each ink color. The multipath method is not limited to the four-pass method, and may be any even-pass method or odd-pass method. In the case of an even path method in which N is an even number, the predetermined number M may be N / 2 as in the above-described embodiment. In the case of an odd-numbered path system where N is an odd number, the thinning rate in the intermediate path may be added to both the total thinning rates A1 (B1) and A2 (B2), or may not be added to both. Good. In other words, in the case of an odd-numbered path system where N is an odd number, the predetermined number M may be either (N−1) / 2 or (N + 1) / 2.

DESCRIPTION OF SYMBOLS 1 Inkjet recording device 13 Recording head 14 Platen 42 Suction hole

Claims (16)

Conveying means for conveying the recording medium in a predetermined conveying direction while sucking the platen;
A plurality of ejection openings capable of ejecting ink, and a recording head movable in a scanning direction intersecting the transport direction at a position facing the platen;
In order to record an image on a predetermined area of the recording medium with a plurality of N times of scanning of the recording head, a predetermined thinning rate is determined by a mask pattern every N times of scanning of the recording head with respect to the predetermined area. Control means for ejecting ink from the ejection ports based on the recording data thinned out at
An inkjet recording apparatus comprising:
The mask pattern includes a first mask pattern for thinning out recording data of an image recorded on the front end portion of the recording medium in the transport direction, and an image recorded on the rear end portion of the recording medium in the transport direction. A second mask pattern for thinning out the recording data of
Of the N scans of the recording head with respect to the leading end, the first mask pattern in a predetermined number M (M ≦ N−1) of scans that is continuous from the first scan and includes the first scan. The first total of the thinning-out ratios of the recording heads in the N times of scanning of the recording head with respect to the rear end portion is continuous from the first scanning and includes the first scanning. Less than a third sum of the thinning rates of the second mask pattern;
Of the N scans of the recording head with respect to the leading end, the thinning rate of the first mask pattern in the predetermined number M of scans that continues to the Nth scan and includes the Nth scan. The sum of 2 is larger than the fourth sum of the thinning rates of the second mask pattern in the predetermined number M of scans that continues to the Nth scan and includes the Nth scan.
An ink jet recording apparatus. The thinning rate of the first mask pattern is such that the first sum is smaller than the second sum.
The thinning rate of the second mask pattern is such that the third sum is greater than the fourth sum.
The inkjet recording apparatus according to claim 1.   3. The ink jet recording apparatus according to claim 1, wherein when N is an even number, the predetermined number of times M is N / 2.   3. The ink jet recording apparatus according to claim 1, wherein when N is an odd number, the predetermined number of times M is either (N−1) / 2 or (N + 1) / 2. 4. In the first mask pattern, the thinning rate in the N-th scan from the first scan of the recording head to the tip portion tends to increase.
5. The method according to claim 1, wherein the thinning rate of the second mask pattern in the Nth scan from the first scan of the recording head to the rear end portion tends to decrease. 2. An ink jet recording apparatus according to 1.   6. The device according to claim 1, wherein at least one of the first and second mask patterns includes a plurality of mask patterns that are different in the thinning rate and can be selectively used. The ink jet recording apparatus described.   The ink jet recording apparatus according to claim 6, wherein the plurality of mask patterns are selectively used according to a plurality of recording modes that can be set in the ink jet recording apparatus.   8. The inkjet recording apparatus according to claim 7, wherein the plurality of recording modes include at least one of a bordered recording mode, a borderless recording mode, a line drawing recording mode, and a photographic recording mode.   The inkjet recording apparatus according to claim 6, wherein the plurality of mask patterns are selectively used according to a suction force with which the platen sucks the recording medium.   The inkjet recording apparatus according to claim 6, wherein the plurality of mask patterns are selectively used according to an amount of ink ejected per unit area of the recording medium.   The ink jet recording apparatus according to claim 6, wherein the plurality of mask patterns are selectively used according to a facing distance between the recording medium and the recording head.   The inkjet recording apparatus according to claim 6, wherein the plurality of mask patterns are selectively used according to a type of a recorded image.   The inkjet recording apparatus according to claim 12, wherein one of the types of the recorded image is an image including characters and fine lines.   The inkjet recording apparatus according to claim 6, wherein the plurality of mask patterns are selectively used according to a type of the recording medium.   The control unit changes a conveyance amount of the recording medium by the conveyance unit when recording an image on at least one of the leading end portion and the trailing end portion of the recording medium. 14. The inkjet recording apparatus according to any one of items 14. A conveying step of conveying the recording medium in a predetermined conveying direction while sucking the recording medium to the platen;
A plurality of ejection openings capable of ejecting ink are formed, and a recording head that is movable in a scanning direction intersecting the transport direction at a position facing the platen is used, with a plurality of N scans of the recording head. In order to record an image in a predetermined area of the recording medium, the discharge port is formed based on recording data thinned out at a predetermined thinning rate by a mask pattern every N scans of the recording head with respect to the predetermined area. A recording step of ejecting ink from,
An inkjet recording method comprising:
The mask pattern includes a first mask pattern for thinning out recording data of an image recorded on the front end portion of the recording medium in the transport direction, and an image recorded on the rear end portion of the recording medium in the transport direction. A second mask pattern for thinning out the recording data of
Of the N scans of the recording head with respect to the leading end, the first mask pattern in a predetermined number M (M ≦ N−1) of scans that is continuous from the first scan and includes the first scan. The first total of the thinning-out ratios of the recording heads in the N times of scanning of the recording head with respect to the rear end portion is continuous from the first scanning and includes the first scanning. Less than a third sum of the thinning rates of the second mask pattern;
Of the N scans of the recording head with respect to the leading end, the thinning rate of the first mask pattern in the predetermined number M of scans that continues to the Nth scan and includes the Nth scan. The sum of 2 is larger than the fourth sum of the thinning rates of the second mask pattern in the predetermined number M of scans that continues to the Nth scan and includes the Nth scan.
An ink jet recording method.

Images