JP2018144356A - Inkjet recording device and inkjet recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet recording device that can suppress an influence of cockling when recording an image in a plurality of times with a plurality of times of reciprocal conveyance of a recording medium, and to provide an inkjet recording method.SOLUTION: An inkjet recording device changes a conveyance amount in a reciprocal movement of a recording medium depending on an imparting amount of ink per unit region of the recording medium.SELECTED DRAWING: Figure 9

Description

  The present invention relates to a technique for suppressing the influence of cockling (waving of a recording medium) that occurs in a recording medium during image recording in a multi-pass inkjet recording apparatus that uses a line recording head.

  The ink jet recording apparatus described in Patent Document 1 includes a set of ink jet recording heads that can eject the same ink as line recording heads that extend in the width direction of the recording medium. By reciprocating the recording medium a plurality of times with respect to the recording head, an image is recorded on the recording medium in a plurality of times. Also, by moving the recording head in the width direction of the recording medium, pixels on the same raster along the recording medium conveyance direction are recorded using a plurality of nozzles in the recording head, and the ink ejection characteristics of each nozzle are recorded. The influence of variation can be suppressed.

Japanese Patent No. 4715209

  However, in the recording apparatus described in Patent Document 1, when a large amount of ink is applied to a unit area of the recording medium, a large amount of ink is applied within a short time, so cockling occurs in the recording medium. The recording medium may come into contact with the recording head. When such contact occurs, there is a possibility that the quality of the recorded image is deteriorated and the recording head is damaged.

  An object of the present invention is to provide an ink jet recording apparatus and an ink jet recording method capable of suppressing the influence of cockling when an image is recorded in a plurality of times with a plurality of times of reciprocating conveyance of a recording medium. is there.

  The ink jet recording apparatus of the present invention is an ink jet recording apparatus that records an image on the recording medium a plurality of times by reciprocating the recording medium a plurality of times through a position facing a recording head capable of ejecting ink. The apparatus further comprises changing means for changing the reciprocating conveyance amount of the recording medium in accordance with the amount of ink applied per unit area of the recording medium.

  According to the present invention, the reciprocal conveyance amount of the recording medium is changed in accordance with the amount of ink applied per unit area of the recording medium, thereby suppressing the influence of cockling and reducing the quality of the recorded image. Head damage can be suppressed.

1 is a perspective view of a main part of a recording apparatus according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view of the recording apparatus of FIG. 1 during a recording operation. FIG. 2 is a cross-sectional view of the recording apparatus of FIG. 1 during a cleaning operation. FIG. 6 is an explanatory diagram of a configuration of a recording head. It is explanatory drawing of the structural example from which a recording head differs. 2 is a block diagram of a control system of the recording apparatus. FIG. It is explanatory drawing of the multipass recording system using a line recording head. It is explanatory drawing of the multipass recording system using a line recording head. FIG. 11 is an explanatory diagram of a recording medium conveyance amount changing operation. FIG. 11 is an explanatory diagram of a recording medium conveyance amount changing operation. It is explanatory drawing of the conveyance amount change operation | movement of a recording medium in the 2nd Embodiment of this invention. It is explanatory drawing of the conveyance amount change operation | movement of a recording medium in the 2nd Embodiment of this invention. It is explanatory drawing of the conveyance amount change operation | movement of a recording medium in the 3rd Embodiment of this invention. It is explanatory drawing of the conveyance amount change operation | movement of a recording medium in the 3rd Embodiment of this invention. It is explanatory drawing of the conveyance amount of the recording medium in the 4th and 5th embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  In this specification, “recording” is not limited to the case where significant information such as characters and figures is formed, and it does not matter whether it is significant or not. In addition, “recording” forms images, patterns, patterns, etc. on a wide range of recording media, or processes the media, regardless of whether they are manifested so that humans can perceive them visually. The case shall also be expressed. “Recording medium” refers not only to paper used in general recording apparatuses but also widely to cloth, plastic film, metal plate, glass, ceramics, wood, leather, and the like that can accept ink. Shall. Further, “ink” (sometimes referred to as “liquid”) should be interpreted widely as in the definition of “recording”. Therefore, by being applied on the recording medium, the image, pattern, pattern or the like is formed, the recording medium is processed, or the ink is processed (for example, solidification or insolubilization of the coloring material in the ink applied to the recording medium). It shall represent a liquid that can be provided. Further, the “nozzle” collectively refers to an ejection port or a liquid passage communicating with the ejection port and an element that generates energy used for ink ejection unless otherwise specified.

(First embodiment)
1 is a perspective view of a main part of an ink jet recording apparatus (hereinafter also referred to as “recording apparatus”) 1 according to the present embodiment, FIG. 2 is a cross-sectional view of the recording apparatus 1 during a recording operation, and FIG. 3 is a cleaning operation. It is sectional drawing of the recording device 1 at the time.

  The recording apparatus 1 of this example uses a long line recording head (hereinafter also referred to as “recording head”) 2 while conveying the sheet-like recording medium 4 in the conveying direction (first direction) indicated by the arrow X. A line printer for recording images. The recording medium 4 can be conveyed in either the forward direction of the arrow X1 or the reverse direction of the arrow X2. The recording apparatus 1 uses a holder that holds a recording medium 4 such as continuous paper wound in a roll, a transport unit 7 that transports the recording medium 4 in a transport direction at a predetermined speed, and a recording medium 4 using a recording head 2. Is provided with a recording unit 3 for recording an image. The recording medium 4 is not limited to continuous roll paper, and may be a cut sheet.

  The recording apparatus 1 includes a cleaning unit 6 that cleans the nozzle surface of the recording head 2 with a wiper. Further, a cutter unit and a paper discharge tray for cutting the recording medium 4 are provided along the conveyance path of the recording medium 4 at a position downstream of the recording unit 3 in the arrow X1 direction (both not shown). . The recording unit 3 includes a recording head 2 corresponding to different ink colors. In this example, four recording heads 2 corresponding to four color inks of C (cyan), M (magenta), Y (yellow), and K (black) are provided. The number of recording heads 2 provided and the number of ink colors used for recording are not limited to this example.

  Each color ink is supplied from a corresponding ink tank (not shown) to a corresponding recording head 2 via an ink tube (not shown). The four recording heads 2 are integrally held by a head holder 5, and the head holder 5 is attached to the head holder 5 so that the distance between the four recording heads 2 and the surface of the recording medium 4 can be changed. A mechanism for moving up and down along the arrow Z direction (first movement direction) is provided. Further, the head holder 5 is provided with a mechanism for moving the head holder 5 in the arrow Y direction (second movement direction) that intersects (in the present example, orthogonal) with the conveyance direction of the recording medium 4. Yes.

  The cleaning unit 6 has four wiper units 9 corresponding to the four recording heads 2. The cleaning unit 6 is configured to slide in a direction indicated by an arrow A (third movement direction) along the conveyance direction of the recording medium 4 by a drive motor (not shown). During the recording operation of the recording apparatus 1, the cleaning unit 6 is positioned downstream of the recording unit 3 in the arrow X1 direction as shown in FIGS. On the other hand, during the cleaning operation, the cleaning unit 6 is located immediately below the recording head 2 in the recording unit 3 as shown in FIG. The cleaning unit 6 moves in the direction of arrow A (third movement direction) in FIGS. 2 and 3.

  4A and 4B are explanatory views of the recording head 2. FIG. 4A is a view of the recording head 2 viewed from the conveyance direction of the recording medium 4, and FIG. 4B is a view from below in FIG. 3 is a bottom view of the recording head 2 as viewed. FIG. As an ink jet method for discharging ink from the nozzles of the recording head 2, various methods using discharge energy generating elements such as an electrothermal conversion element (heater), a piezo element, an electrostatic element, or a MEMS element may be employed. it can. The recording head 2 is a full-line recording head in which nozzle rows 42 are formed over a range that covers the maximum width of the recording medium 4 assumed to be used. The extending direction of the nozzle row 42, that is, the arrangement direction of the nozzles capable of ejecting ink intersects with the conveyance direction indicated by the arrow X (in this example, orthogonal). A nozzle chip 41 is provided on the base substrate 40 of the recording head 2. The nozzle chip 41 has a nozzle surface on which the nozzles of the nozzle row 42 are formed, and a nozzle substrate in which ejection energy generating elements corresponding to the nozzles are embedded. In the case of this example, four nozzle rows 42 are formed in parallel.

  The wiper holder 44 provided with the wiper blade 43 is moved in the arrow Y direction by the drive belt 46 while being guided by the shaft 45. Thereby, the ink and dust adhering to the nozzle surface of the recording head 2 are wiped off by the wiper blade 43.

  In the recording head 2 in FIG. 4B, one nozzle chip 41 is arranged on one base substrate 40. However, the recording head 2 may have a form in which a plurality of nozzle chips 41 are arranged on one base substrate 40 as shown in FIG. 5A, and a plurality of recording heads 2 as shown in FIG. The base substrate 40 may be connected by a support member 48.

  FIG. 6 is a block of a control system of the recording apparatus 1.

  The CPU 501 reads out and executes a program for controlling the system of the recording apparatus 1 from the ROM 502, and controls the entire system according to the program. The RAM 512 is used as a work area for developing a program. That is, the RAM 512 temporarily stores data necessary for processing executed by the CPU 501 and input data. The CPU 501 also controls the operations of the cleaning unit 6 and the transport unit 7.

  Further, the CPU 501 controls the recording operation by the recording head 2 through the drive circuit 507, the binarization circuit 508, and the image processing unit 509. An image processing unit 509 performs predetermined image processing on the input color image data to be recorded. That is, for example, the image processing unit 509 performs data conversion for mapping a color gamut reproduced by the input image data of each RGB color component into a color gamut reproduced by the recording apparatus 1. Further, based on the converted data, the image processing unit 509 performs processing for obtaining color separation data (CMYK component density data) corresponding to a combination of inks that reproduces the colors indicated by each data, and is separated into each color. Tone conversion is performed on each color separation data.

  The binarization circuit 508 performs halftone processing or the like on the multi-value density image data converted by the image processing unit 509 and then converts it to binary data (bitmap data). The drive circuit 507 ejects ink from the nozzles of the recording head 2 in accordance with the binary data obtained by the binarization circuit 508 and the like.

  The defective nozzle complementing unit 510 executes a complementary nozzle generating data generation process (hereinafter also referred to as “complementing process”). The defective nozzle detection unit 511 detects a nozzle (defective nozzle) in which the ink droplet ejection state is in a defective state among the plurality of nozzles formed in the recording head 2. At that time, the CPU 501 drives the recording head 2 via the drive circuit 507 based on the pattern data read from the ROM 502, and controls the transport unit 7 and the like related to the recording operation, so that the recording medium 4 is defective. A nozzle detection pattern is recorded. The defective nozzle is detected by the defective nozzle detection unit 511 reading the recorded pattern.

  FIG. 7 is an explanatory diagram of a multi-pass recording method using a line recording head.

  In the single-pass recording method using a line recording head, an image is recorded with one conveyance of the recording medium in one direction without moving the recording medium back and forth in the conveyance direction. In this case, in particular, in a recording area to which ink is applied densely, there is a possibility that a bleeding phenomenon occurs in which the inks of the respective colors ooze each other. This bleed phenomenon is a phenomenon in which, when ink droplets are ejected onto a recording medium within a short period of time, the inks of the respective colors are mixed and spread before being absorbed by the recording medium, resulting in image deterioration.

  On the other hand, in the multi-pass recording method using the line recording head as in the present invention, an image is recorded with a plurality of reciprocating conveyances of the recording medium in a recording area where ink is densely packed. The amount of ink decreases. Therefore, the bleed phenomenon hardly occurs.

  FIG. 7 and FIG. 8 are explanatory diagrams of an example of an 8-pass recording method that completes image recording by reciprocating a recording medium eight times as a multi-pass recording method using a line recording head. The number of passes is not limited to 8 passes, but may be 2 passes or more. 7 and 8 are explanatory diagrams of the recording operation from the 1-pass to the 18-pass in the 8-pass recording method. FIG. 7 shows that the recording head 2 moves relative to the recording medium 4. The positional relationship is represented. Actually, the recording medium 4 moves relative to the recording head 2 as shown in FIG.

  The first to sixth passes are reciprocating conveyance (conveyance in the directions of arrows X1 and X2) of the recording medium 4 for recording the leading edge of the image. When the unit transport amount of the recording medium 4 is X, the reciprocal transport amount in the first pass and the second pass is X, and the reciprocal transport amount in the third pass and the fourth pass is 2X. The reciprocating conveyance amount is 3X. At the end of the sixth pass, the images of the sixth pass, the fourth pass, and the second pass are recorded in the areas A1, A2, and A3 of the recording medium 4, respectively. Thereafter, the reciprocal conveyance amount of the recording medium 4 accompanied with the image recording is 4X. That is, the reciprocal transport amount at the time of the 7th pass and the 8th pass is 4X, and the image of the area A1 of the recording medium 4 is completed when the 8th pass is completed. Although the transport amount for 9 passes is 5X, it includes the transport amount C for transport (also referred to as “empty transport”) that does not involve image recording with respect to the area A1, and thus the transport amount of the recording medium 4 that accompanies image recording. Is 4X. The carry amount for 10 passes is 4X. After the 11th pass, the image is completed in the areas A1, A2, A3,... Of the recording medium 4 by repeating the operation similarly to the 9th pass and the 10th pass.

  In a single-pass recording method using a line recording head, in order to obtain a multi-pass effect by recording pixels on a recording line along the recording medium conveyance direction using different nozzles, the same color ink is ejected. It is necessary to provide a plurality of nozzle rows. In the multi-pass printing method as in this example, a high-quality image can be recorded by the multi-pass effect by arranging at least one nozzle row for ejecting the same color ink. That is, it is possible to achieve a high quality of the recorded image by using a line recording head having an inexpensive configuration.

  In this embodiment, as shown in FIGS. 9 and 10, the conveyance amount of the recording medium is changed according to the recording duty of the image. The recording duty corresponds to the amount of ink applied per unit area of the recording medium, and can be obtained from the recording data of the image. 9 and 10 are explanatory views of the recording operation from the (N + 1) th pass to the (N + 18) th pass in the 8-pass recording method in which the recording medium is moved back and forth eight times to complete the image recording, as in FIGS. It is. The number of passes is not limited to 8 passes, but may be 2 passes or more. FIG. 9 shows the positional relationship between the recording head 2 and the recording medium 2 that move relative to the recording medium 4. Actually, the recording medium 4 moves relative to the recording head 2 as shown in FIG.

  The area A10 of the recording medium 4 is, for example, a recording area having a high recording duty such that the amount of ink applied per unit area is equal to or greater than a predetermined amount and the recording duty is 150%. The conveyance amount of the medium 4 is 0.5X. That is, during the N + 1 pass and the N + 2 pass, the same operation as the 9th pass and the 10th pass in FIGS. 7 and 8 is repeated as usual. In the N + 3 pass, the carry amount is changed to 4.5X (= 3.5X + C) and the first pass image is recorded in the area A10. In the N + 4 pass, the carry amount is changed to 3.5X. The second pass image is recorded in area A10. In the N + 5 pass, the carry amount is changed to 4X (= 3X + C) and the third pass image is recorded in the area A10. In the N + 6 pass, the carry amount is changed to 3X and the fourth pass is made in the area A10. Record images. In the N + 7 pass, the carry amount is changed to 3.5X (= 2.5X + C) and the image of the fifth pass is recorded in the area A10. In the N + 8 pass, the carry amount is changed to 2.5X. The sixth pass image is recorded in area A10. In the N + 9 pass, the carry amount is changed to 3.5X (= 2.5X + C), and the seventh pass image is recorded in the area A10. In the N + 10 pass, the carry amount is changed to 2.5X. The eighth pass image is recorded in area A10.

  Thereafter, areas where the amount of ink applied per unit area is less than a predetermined amount are sequentially recorded. That is, in the N + 11 pass to the N + 16 pass, the transport amount is 3X (= 2.5X + 0.5C), 2.5X, 3.5X (= 3X + 0.5C), 3X, 4X (= 3.5X + 0.5C), 3. Switch to 5X and record images sequentially. In the N + 17 and N + 18 passes, the transport amount is set to 4.5X (= 4X + 0.5C) and 4X, and the transport amount of the recording medium 4 accompanied by image recording is returned to the normal 4X. As described above, when the area A10 having a high recording duty exists, the reciprocal conveyance amount of the recording medium 4 is gradually reduced from the normal conveyance amount, and the area A10 is idlely conveyed (0.5C) in the N + 11 pass. After that, it becomes longer in steps and returns to the normal transport amount.

  For example, the recording duty is set to 100% when the ink droplets of 600 dots per inch are ejected onto the recording medium at a recording resolution of 600 dpi. Then, the recording duty in the predetermined area, for example, the degree of the recording duty in the recording area of 128 dots × 128 dots is determined, and the conveyance amount of the recording medium is changed according to the determination result. The degree of the recording duty is determined for each predetermined area, and the conveyance amount of the recording medium can be changed when the duty of one area exceeds a predetermined threshold. Also, average the recording duty for each of multiple areas, average out the recording duty of some areas (maximum and minimum recording duty), or combine them to average the recording duty, The value may be compared with a predetermined threshold.

  The recording duty can be obtained by counting the number of ink droplets that are ejected into a predetermined area based on the recording data. In this example, the number of ink droplets of all colors that are driven into a predetermined area is counted. However, the number of ink droplets that are ejected into a predetermined area may be counted in units of ink colors, or may be counted in units of two or more ink colors, or a combination thereof. The timing of such counting is, for example, before the start of conveyance of the recording medium, when the conveyance direction of the recording medium is reversed, before recording of an image, or between recording on the previous recording medium and recording on the next recording medium. (Also referred to as “between pages”).

  Although multi-pass printing reduces the amount of ink droplets deposited per unit time, there is a risk of a cockling phenomenon in which the recording medium undulates in an area where the recording duty is high. The portion where the undulation is caused by the cockling phenomenon may come into contact with the recording head, leading to a decrease in the quality of the recorded image and damage to the recording head. It takes some time from when ink droplets are ejected to the recording medium until the recording medium undulates due to the cockling phenomenon. Therefore, for an area with a high recording duty that is likely to cause a cockling phenomenon, it is effective to complete a recording image for that area in a short time and shorten the period facing the recording head.

  In this embodiment, the reciprocating conveyance amount of the recording medium 4 from the first pass recording (N + 3 pass) to the eighth pass recording (N + 10 pass) with respect to the area A10 having a high recording duty is shortened. That is, at the time of recording on the area A10, the switching interval between the forward conveyance and the backward conveyance of the recording medium is shortened. In this example, the conveyance amount of the recording medium 4 is shortened from the pass (N + 2 pass) before the first pass (N + 3 pass).

  Thus, by shortening the time required to record an image on the area A10, the image recording on the area A10 can be ended before the area A10 may come into contact with the recording head 2 due to the cockling phenomenon. As a result, even if the recording medium is deformed by the cockling phenomenon, contact between the recording medium and the recording head can be avoided, and deterioration of the recording image and damage to the recording head can be suppressed. If there is an area with a high image duty, the conveyance amount of the recording medium may be shortened from the start of image recording for that area. In this case, although the throughput is reduced, the same effect can be obtained. Further, by shifting the head holder 5 in the arrow Y direction while the recording medium conveyance direction is reversed, the pixels on the recording line along the recording medium conveyance direction are recorded using a plurality of different nozzles. It is possible to suppress the influence of variation in the ink ejection characteristics at each time.

(Second Embodiment)
FIG. 11 and FIG. 12 are explanatory diagrams of a recording method according to the second embodiment of the present invention, and an image is recorded by an 8-pass recording method as in the above-described embodiment. In this example, the area A20 with a high recording duty has a recording duty higher than that of the area A10 in the first embodiment, and the conveyance amount of the recording medium is changed when the area A20 is recorded. The recording duty of the area A20 is, for example, 250%.

  For the area A20, the conveyance amount of the recording medium 4 is set to 0.25X. That is, during the N + 1 pass and the N + 2 pass, the same operation as the 9th pass and the 10th pass in FIGS. 7 and 8 is repeated as usual. In the N + 3 pass, the carry amount is changed to 3.25X (= 2.25X + C), and the first pass image is recorded in the area A20. In the N + 4 pass, the carry amount is changed to 3.25X. The second pass image is recorded in area A20. In the N + 5 pass, the carry amount is changed to 3.5X (= 2.5X + C) and the third pass image is recorded in the area A20. In the N + 6 pass, the carry amount is changed to 2.5X. The fourth pass image is recorded in the area A20. In the N + 7 pass, the carry amount is changed to 2.75X (= 1.75X + C), and the fifth pass image is recorded in the area A20. In the N + 8 pass, the carry amount is changed to 1.75X. The sixth pass image is recorded in area A20. In the N + 9 pass, the carry amount is changed to 2X (= X + C) and the seventh pass image is recorded in the area A20. In the N + 10 pass, the carry amount is changed to 5X and the eighth pass in the area A20. Record images.

  Thereafter, in the N + 11 pass to the N + 16 pass, the transport amount is 2X (= 1.75X + 0.25C), 1.75X, 2.75X (= 2.5X + 0.25C), 2.5X, 3.5X (= 3.25X + 0). .25C) and switch to 3.25X to record images sequentially. In the N + 17 and N + 18 passes, the transport amount is set to 4.25X (= 4X + 0.25C) and 4X, and the transport amount of the recording medium 4 accompanied by image recording is returned to the normal 4X. As described above, when the area A20 having a high recording duty exists, the reciprocating conveyance amount of the recording medium 4 is gradually reduced from the normal conveyance amount, and the area A20 is idlely conveyed (0.25C) in the N + 11 pass. After that, it becomes longer in steps and returns to the normal transport amount.

  As the recording duty becomes higher as in the area A20, the deformation of the recording medium due to the cockling phenomenon occurs significantly more rapidly. As in the present embodiment, by shortening the conveyance amount of the recording medium, a recording image for the area A20 having a high recording duty that is likely to cause a cockling phenomenon is completed in a shorter time, and the period facing the recording head is increased. It can be made shorter. As a result, it is possible to more reliably suppress the deterioration of the recorded image due to the contact between the recording medium and the recording head and the occurrence of damage to the recording head. FIG. 11B is an explanatory diagram of the relationship between the recording duty and the conveyance amount of the recording medium in the 8-pass recording method. As described above, the conveyance amount at the time of recording in the area where the recording duty is less than 100% is X, and the recording duty is 100% or more and less than 200% at the time of recording in the area A10 as in the first embodiment. The carry amount is 0.5X. Further, as in the second embodiment, the conveyance amount at the time of recording in the area A20 in which the recording duty is 200% or more and 300 or less is 0.25X. Depending on the number of passes of the multi-pass printing method such as 4-pass or 6-pass, the relationship between the print duty and the carry amount differs.

(Third embodiment)
FIG. 13 and FIG. 14 are explanatory diagrams of a recording method according to the third embodiment of the present invention, and an image is recorded by an 8-pass recording method as in the above-described embodiment. In this example, the area A20 with a high recording duty has a recording duty of 250% as in the second embodiment, and the unit transport amount of the recording medium is changed from X to 0.5X before recording to the area A20. To do.

  FIG. 9 is an explanatory diagram for shortening the conveyance amount of the recording medium from the front approaching the area where the image duty is high as compared with the first embodiment. As in the first embodiment, the method relates to the 8-pass printing method. The area where the image duty is high is 250% duty as in the first embodiment, and the feed amount is changed from X to 0.5X from the front of the image.

  Specifically, in the N + 1 pass and N + 2 pass, the same operations as those in the 9th pass and the 10th pass in FIGS. 7 and 8 are repeated as usual. In N + 3 pass, the carry amount is changed to 4.5X (= 3.5X + C), in N + 4 pass, the carry amount is changed to 3.5X, in N + 5 pass, the carry amount is changed to 4X (= 3X + C), and in N + 6 pass Change the carry amount to 3X. During the N + 7 pass, the carry amount is changed to 3.5X (= 2.5X + C), and during the N + 8 pass, the carry amount is changed to 2.5X. At N + 9 pass, the carry amount is changed to 3X (= 2X + C) and the first pass image is recorded in area A20. At N + 10 pass, the carry amount is changed to 2X and the second pass image is recorded in area A20. To do. During the N + 11 pass, the carry amount is changed to 2.5X (= 2X + 0.5C) and the third pass image is recorded in the area A20, and during the N + 12 pass, the carry amount is changed to 2X and the fourth pass is made in the area A20. Record images. . During the N + 13 pass, the carry amount is 2.5X (= 2X + 0.5C), and the fifth pass image is recorded in the area A20. In the N + 12 pass, the carry amount is 2X and the sixth pass image is recorded in the area A20. Similarly, at N + 15 pass, the carry amount is 2.5X (= 2X + 0.5C) and the seventh pass image is recorded in area A20. At N + 16 pass, the carry amount is 2X and the eighth pass image is printed in area A20. Record. Thereafter, the transport amount is changed to 3X (= 2.5X + 0.5C) at the time of N + 17 passes, and the transport amount is changed to 2.5X at the time of N + 18 passes.

  As described above, the conveyance amount of the recording medium accompanying image recording (excluding empty conveyance) is switched from 4X to 3.5X (N + 3, N + 4 passes), and thereafter 3X (N + 5, N + 6 passes), 2.5X (N + 7). , N + 8 paths) and 2X (N + 9 to N + 16 paths) sequentially. Then, after the recording in the area A20 is completed, the conveyance amount of the recording medium accompanied by the image recording (excluding the empty conveyance) is 2.5X (N + 17, N + 18 passes), 3X, 3 as in the first embodiment. .., 5X, 4X, and then return to the steady conveyance amount 4X.

(Fourth embodiment)
FIG. 15A is an explanatory diagram of an embodiment in which the conveyance amount (excluding empty conveyance) of the recording medium that accompanies image recording is changed according to the environmental temperature and humidity. In an environment of temperature and humidity (20 ° C./50%), an area where the recording duty is 50%, an area A10 of 150% as in the first embodiment, and an area of 250% as in the second embodiment The conveyance amount at the time of recording of A20 is X, 0.5X, and 0.25X. Further, in an environment of temperature and humidity (10 ° C./20%), the conveyance amount during recording in the area where the recording duty is 50%, the area A10 where the recording duty is 150%, and the area A20 where the recording duty is 250% is 1.2 × 0. Change to 6X and 0.3X. Further, in the environment of temperature and humidity (30 ° C./80%), the conveyance amount during recording in the area where the recording duty is 50%, the area A10 where the recording duty is 150%, and the area A20 where the recording duty is 250% is 0.8X, 0. Change to 4X and 0.2X.

  In an environment where the temperature is high and the humidity is high, the cockling phenomenon of the recording medium occurs more remarkably. Therefore, deformation of the area of the recording medium having a high recording duty occurs in a shorter time. For this reason, in an environment where the temperature and humidity are high, it is effective to shorten the transport amount during recording with respect to the area of the recording medium having a high recording duty. On the contrary, in an environment where the temperature and humidity are low, the conveyance amount of the recording medium is increased. As described above, the coefficient relating the reference transport amount X and the transport amount at the time of recording in the area of the recording medium having a high recording duty is decreased as the temperature and humidity are higher, and is increased as the temperature and humidity are lower. Such coefficients are not limited to the values shown in FIG. 15A because the optimum values differ depending on the number of passes of the recording method.

(Fifth embodiment)
FIG. 15B is an explanatory diagram of an embodiment in which the conveyance amount (excluding empty conveyance) of the recording medium that accompanies image recording is changed according to the type and thickness of the recording medium. When the recording medium is thin coated paper, conveyance during recording is performed in an area where the recording duty is 50%, an area A10 of 150% as in the first embodiment, and an area A20 of 250% as in the second embodiment. The amounts are X, 0.5X, and 0.25X. When the recording medium is thick coated paper, the conveyance amount during recording in the area where the recording duty is 50%, 150% area A10, and 250% area A20 is 1.2X, 0.6X, and Change to 0.3X. When the recording medium is plain paper, the conveyance amounts during recording in the area where the recording duty is 50%, the area A10 where the recording duty is 150%, and the area A20 where the recording duty is 250% are 0.8X, 0.4X, and 0. Change to 2X.

  When the recording medium is the same type of coated paper, the thinner it is, the more noticeable the cockling phenomenon occurs, and the deformation of the area of the recording medium having a high recording duty occurs in a shorter time. Therefore, the thinner the recording medium is, the more effective it is to shorten the transport amount during recording with respect to the area of the recording medium having a high recording duty. The reason why the cockling phenomenon becomes more noticeable as the recording medium is thinner is that the moisture content of the ink per unit volume of the recording medium increases and deformation tends to occur. Further, the plain paper has a more noticeable cockling phenomenon than the coated paper, and the deformation of the plain paper area having a high recording duty occurs in a shorter time. For this reason, it is effective to reduce the conveyance amount at the time of recording for the plain paper area having a high recording duty. Since plain paper has lower rigidity than coated paper, deformation due to cockling phenomenon is also large. In addition, this difference in rigidity is partly due to the fact that the coated paper has an ink receiving layer and the plain paper has no ink receiving layer. Further, the coefficient relating the reference transport amount X and the transport amount at the time of recording in the area of the recording medium having a high recording duty is changed according to the type and thickness of the recording medium. Such a coefficient is not limited to the value shown in FIG. 15B because the optimum value differs depending on the number of passes of the recording method.

DESCRIPTION OF SYMBOLS 1 Inkjet recording device 2 Recording head 4 Recording medium

Claims (14)

An inkjet recording apparatus that records an image on the recording medium in a plurality of times by reciprocally conveying the recording medium a plurality of times through a position facing a recording head capable of ejecting ink,
An ink jet recording apparatus comprising: changing means for changing a reciprocating conveyance amount of the recording medium according to an ink application amount per unit area of the recording medium.   The reciprocating conveyance amount for recording an image in a plurality of times in the recording area is shorter in a recording area of the recording medium having a higher ink application amount per unit area. The ink jet recording apparatus described.   The reciprocating transport amount for recording an image in a plurality of times in a recording area of the recording medium in which the amount of ink applied per unit area is a predetermined amount or more is determined by the amount of ink applied per unit area. 2. The ink jet recording apparatus according to claim 1, wherein the reciprocal conveyance amount is shorter than the reciprocal conveyance amount when an image is recorded in a plurality of times in a recording area of the recording medium less than a fixed amount.   The reciprocating conveyance amount for recording an image in a plurality of times in a recording area of the recording medium in which the amount of ink applied per unit area is a predetermined amount or more is set before the image is recorded in the recording area, or 4. The ink jet recording apparatus according to claim 3, wherein the recording time is shortened from when the image is recorded in the recording area.   The reciprocating conveyance amount for recording an image in a plurality of times in a recording area of the recording medium in which the amount of ink applied per unit area is a predetermined amount or more is set before the image is recorded in the recording area, or The ink jet recording apparatus according to claim 3 or 4, wherein the recording time is shortened step by step from the time when an image is recorded in the recording area.   The reciprocating conveyance amount for recording an image in a plurality of times in a recording area of the recording medium in which the amount of ink applied per unit area is a predetermined amount or more is set before the image is recorded in the recording area, or 6. The inkjet recording apparatus according to claim 3, wherein after the image is recorded in the recording area, the image is shortened stepwise and then lengthened stepwise.   7. The reciprocating conveyance amount for recording an image in a plurality of times in a recording area of the recording medium is shorter as at least one of environmental temperature and humidity is higher. 2. An ink jet recording apparatus according to item 1.   The reciprocating conveyance amount for recording an image in a plurality of times in a recording area of the recording medium is shorter as the recording medium is more easily deformed by application of ink. 8. The ink jet recording apparatus according to any one of 7 above.   9. The ink jet recording apparatus according to claim 8, wherein the reciprocal conveyance amount for recording an image in a plurality of times in a recording area of the recording medium is different depending on a type of the recording medium.   10. The recording medium for plain paper has a shorter reciprocal conveyance amount for recording an image in a plurality of times in a recording area of the recording medium than the recording medium for coated paper. 2. An ink jet recording apparatus according to 1.   9. The ink jet recording apparatus according to claim 8, wherein the thicker the recording medium, the shorter the reciprocal conveyance amount for recording an image in a plurality of times in the recording area of the recording medium.   The recording medium that does not include an ink receiving layer has a shorter reciprocal conveyance amount for recording an image in a plurality of times in a recording area of the recording medium than the recording medium that includes an ink receiving layer. An ink jet recording apparatus according to claim 8.   The inkjet recording apparatus according to claim 1, further comprising a moving unit that moves the recording head in a direction that intersects a conveyance direction of the recording medium. An inkjet recording method for recording an image on the recording medium a plurality of times by reciprocating the recording medium a plurality of times through a position facing a recording head capable of ejecting ink,
An ink jet recording method comprising: changing a reciprocating conveyance amount of the recording medium according to an ink application amount per unit area of the recording medium.

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