JP2021074972A - Inkjet recording method and inkjet recording device - Google Patents

Abstract

To provide a serial type color inkjet recording device which records an image that has no color unevenness and makes joint streaks inconspicuous.SOLUTION: An image is recorded in a first region of a recording medium by only a first recording step and a second recording step, and an image is recorded in a second region adjacent to the first region by only the first recording step and a fourth recording step. An image is recorded in a third region adjacent to the second region by only a third recording step and the fourth recording step. At this time, in the first recording step, a recording ratio of a position adjacent to the third region in the second region is set to be lower than a recording ratio of a position adjacent to the first region in the second region. In the fourth recording step, a recording ratio of a position adjacent to the first region in the second region is set to be lower than a recording ratio of a position adjacent to the third region in the second region.SELECTED DRAWING: Figure 5

Description

The present invention relates to an inkjet recording method and an inkjet recording device.

In the serial type color inkjet recording apparatus, in bidirectional multipath recording, there has been a problem of color unevenness due to the difference in the order of applying ink to the recording medium between the outward scanning and the inbound scanning. In Patent Document 1, in two-pass bidirectional multi-pass recording, the transfer amount and the area used by the recording head are different for each recording scan while the transport direction is constant, so that the order of applying ink to the recording medium is unified. However, a recording method for suppressing color unevenness is disclosed.

On the other hand, in the serial type inkjet recording apparatus, the variation in the amount of transportation performed during each recording scan may become conspicuous as a connecting streak. Patent Document 1 discloses a method of correcting a transport amount of a recording medium when the recording medium is in a slippery condition during transport, and alleviating an image adverse effect due to a transport error.

Japanese Unexamined Patent Publication No. 2013-193302

However, the method of Patent Document 1 prepares a mode for increasing the transport amount and a mode for reducing the transport amount according to the type and size of the recording medium, and cannot cope with sudden transport variations. .. Further, when recording on a recording medium different from the predetermined recording medium, an appropriate correction amount cannot be set, and the connecting streaks may become conspicuous. That is, when performing 2-pass multi-pass recording with an inkjet recording device, it is difficult to make both color unevenness and connecting streaks inconspicuous.

The present invention has been made to solve the above problems. Therefore, the purpose is to record an image in a serial type color inkjet recording apparatus, which has no color unevenness and inconspicuous joint streaks.

Therefore, the present invention reciprocates a recording head in which a row of nozzles in which a plurality of nozzles for ejecting ink are arranged reciprocates in the scanning direction for a plurality of types of inks arranged in a scanning direction intersecting the direction of the arrangement. An inkjet recording method for recording an image on a recording medium while scanning, following the first recording step of ejecting ink while scanning the recording head in the outward path direction of the scanning direction, and the first recording step. Then, following the second recording step of ejecting ink while scanning the recording head in the return direction of the scanning direction and the second recording step, the ink is ejected while scanning the recording head in the outward path direction. Following the third recording step of ejecting and the third recording step, a fourth recording step of ejecting ink while scanning the recording head in the return path direction, the first recording step, and the first recording step. Between each of the second recording step, the third recording step, and the fourth recording step, there is a transport step of transporting the recording medium in a transport direction intersecting the scanning direction, and the recording medium. In the first region, images are recorded only by the first recording step and the second recording step, and the second region adjacent to the first region in the transport direction is the first recording step and the said. An image is recorded only by the fourth recording step, and an image is recorded in the third region adjacent to the second region in the transport direction only by the third recording step and the fourth recording step. In the first recording step, the recording rate of the position adjacent to the third region of the second region is lower than the recording rate of the position adjacent to the first region of the second region, and the fourth recording In the step, the recording rate of the position adjacent to the first region of the second region is lower than the recording rate of the position adjacent to the third region of the second region.

According to the present invention, in a serial type color inkjet recording apparatus, it is possible to record an image having no color unevenness and inconspicuous joint streaks.

It is a schematic block diagram of an inkjet recording apparatus and a recording head. It is a block diagram which shows the control structure of an inkjet recording apparatus. It is a flowchart for demonstrating a series of image processing executed by a control unit. It is a flowchart which shows the process which a control part executes in a recording process. It is a figure which shows the use state of a recording head, and the recording state of a recording medium. It is a figure which shows the state of the connecting streak when a transport error occurs. It is a figure which shows the change of the recording duty with the transfer error. It is a figure for demonstrating the recording method of 2nd Embodiment. It is a figure for demonstrating the modification of the 2nd Embodiment.

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

(First Embodiment)
1A and 1B are schematic configuration diagrams of an inkjet recording apparatus 300 and a recording head 100 that can be used in the present embodiment. As shown in FIG. 1A, the inkjet recording apparatus 300 has two sets of roller pairs, one is a transport roller pair composed of a transport roller 210 and an auxiliary roller 209, and the other is a discharge roller pair composed of a discharge roller 212 and an auxiliary roller 211. I have. The recording medium P is sandwiched between these two sets of rollers to maintain a smooth surface, and is intermittently conveyed in the conveying direction (y direction).

A carriage 213 that can move in the main scanning direction (± x direction) intersecting the transport direction is provided between the transport roller pair and the discharge roller pair. The carriage 213 is equipped with an ink tank 205 to 208 that supplies ink to each of the recording head 100 and the nozzle rows 101 to 104 arranged on the recording head 100. Before the recording command is input, the carriage 213 is waiting at the home position h indicated by the broken line in the figure. When the recording command is input, the carriage 213 starts the recording operation while moving in the x direction in the figure.

When the recording head 100 ejects ink while moving in the x direction, an image for one band is recorded on the recording medium P. When the recording of such an image for one band is completed, the transfer roller 210 and the discharge roller 212 rotate, and the recording medium P is conveyed in the + y direction by a distance corresponding to one band. By alternately repeating the recording main scanning and the conveying operation as described above, images are sequentially formed on the recording medium P.

FIG. 1B is a view of the recording head 100 mounted on the carriage 213 as viewed from the nozzle surface side. A nozzle row 101 for ejecting black ink (K), a nozzle row 102 for ejecting cyan ink (C), a nozzle row 103 for ejecting magenta ink (M), and yellow ink (Y) are ejected to the recording head 100. The nozzle rows 104 are arranged in this order. In each of the nozzle rows 101 to 104, 1280 nozzles are arranged in the y direction at a pitch of 1200 dpi. That is, while the carriage 213 moves in the ± x direction, the individual nozzle rows 101 to 104 eject ink, so that a color image of a band of 1280 pixels is recorded on the recording medium P. At this time, when the carriage 213 ejects ink while moving in the outward direction (+ x direction), black (K), cyan (C), magenta (M), and yellow (Y) are placed on the recording medium P in this order. Ink is applied. On the contrary, when the carriage 213 ejects ink while moving in the return direction (-x direction), the recording medium P is in the order of yellow (Y), magenta (M), cyan (C), and black (K). Ink is applied with.

The ink tanks 205 to 208 and the recording head 100 of the present embodiment are configured to be mounted on the carriage 213 so as to be separable from each other, but the present invention is not limited thereto. That is, a cartridge in which the ink tanks 205 to 208 and the recording head 100 are integrated may be mounted on the carriage 213. Further, one recording head in which one nozzle row and one ink tank are integrated may be used as one recording head, and a plurality of colors of such a recording head may be individually mounted on the carriage 213.

FIG. 2 is a block diagram showing a control configuration of the inkjet recording device 300 of the present embodiment. The inkjet recording device 300 is connected to a data supply device such as a host computer (hereinafter, host PC) 303 via an interface 302. The inkjet recording device 300 mainly includes a control unit 301, a transfer motor driver 304, a carriage motor driver 305, a head driver 306, a transfer motor 307, a carriage motor 308, and a recording head 100.

The control unit 301 has a ROM for storing the program and a RAM used as a work area, and controls the entire device. The transfer motor driver 304 drives the transfer motor 307 to rotate the transfer roller 210 and the discharge roller 212. The carriage motor driver 305 drives the carriage motor 308 and controls the reciprocating scanning of the carriage 213. The head driver 306 drives the recording head 100 according to the recording data.

When printing the image generated by the host PC 303, the print job including the image data and various commands is input to the control unit 301 via the interface 302. The control unit 301 develops the received image data, performs predetermined image processing, and generates recorded data that can be recorded by the inkjet recording device 300. Then, the transfer motor driver 304, the carriage motor driver 305, and the head driver 306 are controlled to record an image on a recording medium.

FIG. 3 is a flowchart for explaining a series of image processing executed by the control unit 301 when a print job is received. When this process is started, the control unit 301 first performs a color adjustment process (S401).

The color adjustment process is a process for associating a standard color space such as S-RGB that can be expressed by the host PC with a color space that can be expressed by the recording device 300. Specifically, the control unit 301 refers to a LUT or the like stored in the ROM in advance, and converts the RGB 8-bit pixel value of each pixel into another value of the RGB 8-bit pixel value.

In S402, the control unit 301 performs a color conversion process. The color conversion process is a process of converting a color space represented by RGB into a color space represented by the ink color CMYK used by the recording device 300. Specifically, the control unit 301 refers to a LUT or the like stored in the ROM in advance, and converts the RGB 8-bit pixel value of each pixel into the CMYK 8-bit pixel value.

In S403, the control unit 301 performs gamma correction processing. The gamma correction process is a process of performing signal value conversion so that the pixel value (density value) represented by each of CMYK and the density value represented by the recording medium have a linear relationship. Specifically, the control unit 301 refers to a LUT or the like stored in the ROM in advance, and sets the 8-bit pixel value of each of the C, M, Y, and K pixels of each pixel to another value of C, M, Y. , K is converted into an 8-bit pixel value.

In S404, the control unit 301 performs the quantization process. The quantization process converts an 8-bit (0 to 255) pixel value for each of C, M, Y, and K into a binary value indicating dot recording (1) or non-recording (0). As a method of quantization processing, an error diffusion method, a dither method, or the like can be adopted.

In S405, the control unit 301 performs the distribution process. The distribution process is a process for distributing the pixels defined as the recording (1) by the quantization process of S404 to a plurality of recording scans in multipath recording. The control unit 301 uses the mask pattern stored in the ROM in advance to determine whether to record the dot of the pixel defined as the recording (1) in the first pass or the second pass. The mask pattern of the present embodiment is prepared separately for the outward scan and the return scan, and in each scan, a pixel (1) that allows dot recording and a pixel (0) that does not allow dot recording for each nozzle are provided. It is predetermined.

The control unit 301 performs a logical product operation between such a mask pattern and the quantization data generated by the quantization process of S404, so that the recording head 100 actually records dots in each recording scan. Is determined and saved in the buffer as recorded data.

In S406, the control unit 301 performs the recording process according to the recorded data generated in S405.

FIG. 4 is a flowchart showing a process executed by the control unit 301 in the recording process of S406. When this process is started, the control unit 301 first feeds the recording medium P in S500 and aligns the recording medium P with respect to the recording head 100 in the y direction.

In S501, the control unit 301 performs an outward recording scan while moving in the + x direction. In S502, the control unit 301 conveys the recording medium by 160 pixels in the + y direction. In S503, the control unit 301 performs recording scanning in the return direction while moving in the −x direction. In S504, the control unit 301 conveys the recording medium by 800 pixels in the + y direction.

In S505, the control unit 301 determines whether or not recording is completed for all the recorded data generated in S404. If No, the control unit 301 returns to S501 and performs the next recording scan, that is, the recording scan in the outward direction based on the recorded data that has not been recorded yet. On the other hand, in the case of Yes in S404, the control unit 301 proceeds to S506 and ejects the recording medium P. This is the end of this process.

5 (a) and 5 (b) are diagrams showing the usage state of the nozzle rows 101 to 104 in each recording scan and the recording state of the recording medium. In the present embodiment, the 1280 nozzles arranged in the nozzle rows 101 to 104 are divided into eight nozzle groups of 160 each and managed. In FIG. 5A, such eight nozzle groups are shown as nozzle groups N1 to N8 from the downstream side (+ y direction side) in the transport direction. Further, in the figure, the width of each nozzle group in the y direction is shown as D. The nozzle group used for recording in each recording scan is indicated by diagonal lines.

In the present embodiment, in the odd-numbered recording scan performed in S501 of FIG. 4, the two nozzle groups N1 and N2 are not used, and the remaining six nozzle groups N3 to N8 are used for recording. In the even-numbered recording scan performed in S503 of FIG. 4, the two nozzle groups N7 and N8 are not used for recording, and the remaining six nozzle groups N1 to N6 are used for recording. The mask pattern for outbound scanning corresponding to the nozzle groups N3 to N7 and the mask pattern for inbound scanning corresponding to the nozzle groups N2 to N6 have a complementary relationship with each other. Images of the first region and the third region are recorded. Further, the mask pattern for outward scanning corresponding to the nozzle group N8 and the mask pattern for returning scanning corresponding to the nozzle group N1 have a complementary relationship with each other, and these two mask patterns provide a second region. Image is recorded.

FIG. 5B is a diagram showing the recording rate of each nozzle in each recording scan. The recording rate indicates the ratio of the pixels in which the dots are actually recorded in the scanning among the pixels in which the dot recording (1) is determined in S405. Specifically, such a recording rate is determined by the mask pattern used in S404.

The first and third recording scans of FIG. 5B correspond to the recording scans in the outward direction performed in S501 of FIG. The recording rates of the nozzle group N1 and the nozzle group N2 are set to 0%, and the recording rates of the nozzle groups N3 to N7 are set to 50%. Regarding the nozzle group N8, the recording rate of the nozzles on the downstream side in the transport direction, that is, the nozzles adjacent to the nozzle group N7 is set to 100%, and the recording rate of the nozzle on the most upstream side in the transport direction is set to 0%. Further, the recording rate of the nozzle between them is set to gradually decrease from 100% to 0%. Here, only the first and third recording scans are shown, but the odd-numbered recording scans performed in the outbound scan are performed at the same recording rate as the first and third recording scans.

The second and fourth recording scans of FIG. 5B correspond to the recording scans in the return direction performed in S503 of FIG. In the nozzle group N1, the recording rate of the nozzle on the most downstream side in the transport direction is set to 0%, and the recording rate of the nozzle on the upstream side in the transport direction, that is, the nozzle adjacent to the nozzle group N2 is set to 100%. Further, the recording rate of the nozzle between them is set to gradually increase from 0% to 100%. On the other hand, the recording rate of the nozzle groups N3 to N7 is set to 50%, and the recording rate of the nozzle groups N8 is set to 0%. Here, only the second and fourth recording scans are shown, but the even-numbered recording scans, which are the return scans, are all performed at the same recording rate as the second and fourth recording scans.

Here, attention is paid to each area of the recording medium. The first region shown in FIGS. 5A and 5B is a region in which an image is completed by a first recording scan which is an outward scan and a second recording scan which is a return scan. For example, when recording an image of 100% green formed by a mixture of cyan and yellow, 50% cyan ink is applied to the region in the first recording scan, and then 50% yellow ink is applied to the region. .. Then, in the second recording scan performed after the first transport operation, 50% of the yellow ink is applied to the region and then 50% of the cyan ink is applied. That is, the order of applying ink in the first region is cyan → yellow → yellow → cyan.

In the second region, an image is completed by a first recording scan, which is an outward scan, and a fourth recording scan, which is a return scan. The order of applying ink in the second region is the same as in the first region, in the order of cyan → yellow → yellow → cyan.

In the third region, an image is completed by a third recording scan, which is an outward scan, and a fourth recording scan, which is a return scan. The order of applying ink in the third region is also the same as in the first region and the second region, in the order of cyan → yellow → yellow → cyan.

Hereinafter, in the recording medium P, regions such as the first and third regions having a width of 5D and regions such as a second region having a width D are alternately arranged in the y direction. That is, in any region of the recording medium, the order of applying ink is unified in the order of cyan → yellow → yellow → cyan, and color unevenness does not occur.

By the way, in the transport operation performed in S502 or S504, if an error is included in the transport amount, streaks and density unevenness may be conspicuous in the image. FIG. 6 is a diagram showing the state of the connecting streaks when a transport error occurs. In the case of 1-pass recording, if the transport amount of the transport operation is larger than the specified value, a blank area in which ink is not applied is generated between the recording areas of each recording scan, and this becomes a white streak and becomes conspicuous. On the other hand, if the transport amount of the transport operation is smaller than the specified value, a region where ink is additionally applied is generated between the recording regions of each recording scan, and this becomes a black streak and becomes conspicuous.

On the other hand, in the case of 2-pass recording, if the transport amount of the transport operation is larger than the specified value, a region where the amount of ink applied is smaller than that of the periphery is generated, which is not as noticeable as the white streaks of 1-pass recording, but the density is low. It will be recognized as a streak. Further, when the transport amount in the transport operation is smaller than the specified value, the amount of ink applied is larger than that in the periphery, and although it is not as noticeable as the black streaks in 1-pass recording, it is recognized as a streak with high density. In general, such an error in the transport amount tends to increase as the transport amount increases.

See FIG. 5A again. According to the recording method of the present embodiment, the connecting portion between the first region and the second region is formed by the second recording scan and the fourth recording scan, and the transport operation of the transport amount D is performed between these two recording scans. An intervening transfer operation with a transfer amount of 5D. Further, the connecting portion between the second region and the third region is formed by the first recording scan and the third recording scan, and the transport operation of the transport amount D and the transport operation of the transport amount 5D are performed between these two recording scans. Intervene. That is, in the two-pass bidirectional multipath recording of the present embodiment, the number of transfer operations performed between the two recording scans is larger than that of the conventional general two-pass bidirectional multipath recording. Moreover, a transfer operation with a large transfer amount is included. Therefore, even if the color unevenness is alleviated by unifying the application order of the inks, there is a possibility that the joint streaks become conspicuous.

Under such a situation, in the present embodiment, the recording rate of the nozzle group N8 in the recording scan in the outward direction and the recording rate of the nozzle group N1 in the recording scan in the returning direction are characterized. Specifically, while maintaining a complementary relationship between the nozzle group N8 in the outward direction and the nozzle group N1 in the return direction, the recording rate gradually changes from 0% to 100% from the end in each nozzle group. A mask pattern is used (see FIG. 5B).

FIG. 7 is a diagram showing a change in recording duty due to a transfer error when a uniform image having a recording duty of 100% is recorded by the recording method of the present embodiment. When no transport error occurs, in the pixel group included in the second region, dots according to the mask pattern of the outward scan and dots according to the mask pattern of the return scan are complementarily arranged, and the recording duty is 100%. It becomes.

On the other hand, when the transport amount is larger than the standard, the dots according to the mask pattern of the outward scan and the dots according to the mask pattern of the return scan are arranged at positions separated in the y direction, and the entire second region is formed. The recording duty of is slightly lower than 100%. However, local white streaks as shown in FIG. 6 do not occur, and the image can be visually recognized as a uniform image. On the other hand, when the amount of transportation is smaller than the standard, the dots according to the mask pattern of the outward scan and the dots according to the mask pattern used in the return scan are arranged at overlapping positions in the y direction in the entire second region. The recording duty is slightly higher than 100%. However, local black streaks as shown in FIG. 6 do not occur, and the image can be visually recognized as a uniform image.

As described above, in the present embodiment, since the recording rate of the nozzle at the position where the joint portion is formed is suppressed to be lower than the others, it is possible to make the joint streaks inconspicuous due to a transport error. As a result, it is possible to record an image in which there is no color unevenness and the joint streaks are not conspicuous even in the case of performing two-pass bidirectional multipath.

(Second embodiment)
Also in this embodiment, two-pass bidirectional multipath recording is performed using the inkjet recording apparatus shown in FIGS. 1 and 2. Further, image processing and recording processing are performed according to the flowcharts shown in FIGS. 3 and 5. In addition, in the present embodiment, density unevenness due to variation in time difference between recording scans in multipath recording is also reduced. Hereinafter, the density unevenness due to the variation in the time difference will be briefly described.

See FIG. 5B again. In the case of the first embodiment, the image is completed by the first recording scan and the second recording scan in the first region, and the image is completed by the third recording scan and the fourth recording scan in the third region. That is, in the first region and the third region, an image is completed by two consecutive recording scans. On the other hand, in the second region, the image is completed by the first recording scan and the fourth recording scan, that is, by two non-consecutive recording scans.

Generally, in an inkjet recording apparatus, when the same image area of a recording medium is recorded by two recording scans, the density of the area may be affected by the time elapsed between these two recording scans. Are known. Such a phenomenon varies depending on the type of recording medium. For example, the longer the time elapsed between the first recording scan and the second recording scan, the higher the density of the region may be. That is, in the cases of FIGS. 5A and 5B, the density of the second region tends to be higher than that of the first region and the third region, which may be perceived as uneven density. On the other hand, in the present embodiment, the density unevenness is made inconspicuous by giving a bias to the outbound scan and the inbound scan without equalizing the recording rates.

FIG. 8 is a diagram for explaining the recording method of the present embodiment. The difference from FIG. 5B described in the first embodiment is the recording rate in each recording scan. In the present embodiment, the recording rates of the nozzle groups N3 to N7 are set to 80% in the first and third recording scans, that is, the outbound scans. For the nozzle group N8, the recording rate of the nozzles on the downstream side in the transport direction, that is, the nozzles adjacent to the nozzle group N7 is set to 100%, and the recording rate of the nozzle on the most upstream side in the transport direction is set to 50%. .. Then, the recording rate of the nozzle between them is set to gradually decrease from 100% to 50%.

On the other hand, in the second and fourth recording scans, that is, the return scans, the recording rates of the nozzle groups N3 to N7 are set to 20%. For the nozzle group N2, the recording rate of the nozzles on the downstream side in the transport direction, that is, the nozzles adjacent to the nozzle group N3 is set to 50%, and the recording rate of the nozzle on the most upstream side in the transport direction is set to 0%. .. Further, the recording rate of the nozzle between them is set to gradually decrease from 50% to 0%.

Also in this embodiment, the order of applying ink is unified in the order of cyan → yellow → yellow → cyan in all areas on the recording medium, and the same effect as in the first embodiment, that is, color unevenness is suppressed. The effect of reducing joint streaks can be obtained. On top of that, according to the present embodiment, since almost 80% of the ink is applied in the first recording scan in any region, the time elapsed until the remaining 20% is applied is the density of the image. It is possible to suppress the influence on. As a result, in addition to color unevenness and connecting streaks, density unevenness due to variation in time difference between recording scans can be reduced.

FIG. 9 is a diagram showing a modified example of the recording method of the present embodiment. In this modified example, the recording rate of the outward scanning and the recording rate of the returning scanning are reversed from the example of FIG. That is, the recording rate of the nozzle groups N3 to N7 in the outward scanning is set to 20%, and the recording rate of the nozzle groups N2 to N6 in the returning scanning is set to 80%. Even in such a form, as in the case of FIG. 8, in addition to color unevenness and connecting streaks, density unevenness due to variation in time difference between recording scans can be reduced.

(Other embodiments)
In the first and second embodiments, the recording rates of the nozzle group N8 for outward scanning and the nozzle group N1 for returning scanning are changed with a uniform inclination, but the recording rates may be changed stepwise.

Further, in the above embodiment, all the steps of the image processing described in the flowchart of FIG. 4 are performed by the control unit 301 of the recording device, but some steps may be performed by the host PC. For example, the host PC 303 may perform the process from the color adjustment process of S401 to the quantization process of S404, and the recording device 300 may perform only the distribution process of S405 and the recording process of S406.

Further, in the above, the nozzles arranged in the nozzle rows 101 to 104 are equally divided into eight nozzle groups, but the number N of such nozzle groups can be changed. However, in order to realize the above embodiment, the number N of the nozzle groups is required to be an integer of 5 or more. When divided into N nozzle groups, after the outward scan, the distance corresponding to one nozzle group is conveyed, and after the return scan, the distance corresponding to (N-3) of the nozzle group is conveyed. Just do it.

Further, the type of ink, the number of nozzles, and the recording resolution described in the above embodiment are examples, and any of them can be changed as appropriate. For example, as the ink, in addition to cyan, magenta, yellow, and black, inks such as light cyan, light magenta, and gray may be used.

The present invention supplies a program that realizes one or more functions of the above-described embodiment to a system or device via a network or storage medium, and one or more processors in the computer of the system or device reads and executes the program. It can also be realized by the processing to be performed. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

100 Recording Head 101-104 Nozzle Row
P Recording medium

Claims (11)

A recording medium in which a nozzle array in which a plurality of nozzles for ejecting ink are arranged reciprocates a recording head arranged in a scanning direction intersecting the direction of the arrangement for a plurality of types of ink while reciprocally scanning in the scanning direction. An inkjet recording method for recording images
A first recording step of ejecting ink while scanning the recording head in the outward direction of the scanning direction,
Following the first recording step, a second recording step of ejecting ink while scanning the recording head in the return direction of the scanning direction.
Following the second recording step, a third recording step of ejecting ink while scanning the recording head in the outward direction direction.
Following the third recording step, a fourth recording step of ejecting ink while scanning the recording head in the return direction,
A transport step of transporting the recording medium in a transport direction intersecting the scanning direction between each of the first recording step, the second recording step, the third recording step, and the fourth recording step. And have
An image is recorded in the first region of the recording medium only by the first recording step and the second recording step, and the second region adjacent to the first region in the transport direction is the first region. An image is recorded only by the recording step and the fourth recording step, and an image is recorded in the third region adjacent to the second region in the transport direction only by the third recording step and the fourth recording step. Recorded,
In the first recording step, the recording rate of the position adjacent to the third region of the second region is lower than the recording rate of the position adjacent to the first region of the second region.
In the fourth recording step, the recording rate of the position adjacent to the first region of the second region is lower than the recording rate of the position adjacent to the third region of the second region. Inkjet recording method. The recording rate of the first recording step with respect to the first region is higher than the recording rate of the second recording step with respect to the first region, and the recording rate of the third recording step with respect to the third region is The inkjet recording method according to claim 1, wherein the recording rate for the third region of the fourth recording step is higher than that of the third region. The recording rate of the first recording step with respect to the first region is lower than the recording rate of the second recording step with respect to the first region, and the recording rate of the third recording step with respect to the third region is The inkjet recording method according to claim 1, wherein the recording rate for the third region of the fourth recording step is lower than that of the third region. The recording rate of the second region in the first recording step gradually increases from the position adjacent to the third region to the position adjacent to the first region.
Any of claims 1 to 3, wherein the recording rate of the second region of the fourth recording step gradually increases from a position adjacent to the first region to a position adjacent to the third region. The inkjet recording method according to claim 1. The claim is characterized in that the recording rate is set by a mask pattern that defines pixels that allow and do not allow dot recording for individual nozzles for each of the outbound scanning and the inbound scanning. Item 4. The inkjet recording method according to any one of Items 1 to 4. The inkjet recording method according to any one of claims 1 to 5, wherein the plurality of types of inks include cyan ink, magenta ink, yellow ink, and black ink. A row of nozzles in which a plurality of ink ejecting nozzles are arranged alternates recording heads arranged in a scanning direction intersecting the direction of the arrangement for a plurality of types of ink in the outward path direction and the return path direction in the scanning direction. Scanning means to scan
A transport means for transporting the recording medium to the recording head in a transport direction intersecting the scanning direction between the scan in the outward direction and the scan in the return direction.
A setting means for setting the recording rate of the plurality of nozzles arranged in the plurality of nozzle rows for each of the scanning in the outward direction and the scanning in the return direction.
It is an inkjet recording apparatus that completes an image of the same image area of the recording medium by one scanning in the outward direction accompanied by ink ejection and one scanning in the returning direction accompanied by ink ejection. hand,
In each of the nozzle rows, the plurality of nozzles arranged are equally divided into N (N is an integer of 5 or more) nozzle groups.
After scanning in the outward direction, the transport means transports the recording medium in the transport direction by a distance corresponding to one of the nozzle groups, and after the recording scan in the return direction, the nozzle group The recording medium is transported in the transport direction by a distance corresponding to (N-3) of the recording media.
The setting means is
In the recording scan in the outward direction, the two nozzle groups from the downstream side in the transport direction do not discharge, and in the nozzle group on the most upstream side in the transport direction, the recording rate of the nozzle on the upstream side is the nozzle on the downstream side. In the recording scan in the return direction, the two nozzle groups from the upstream side in the transport direction do not record, and the nozzle group on the most downstream side in the transport direction is the nozzle on the downstream side. So that the recording rate of is lower than the recording rate of the nozzle on the upstream side
An inkjet recording apparatus characterized in that the recording rate of ink of the plurality of nozzles is set. The inkjet recording apparatus according to claim 7, wherein the recording rate of the nozzle row in the recording scan in the outward direction is higher than the recording rate of the nozzle row in the recording scan in the return direction. The inkjet recording apparatus according to claim 7, wherein the recording rate of the nozzle row in the recording scan in the outward direction is lower than the recording rate of the nozzle row in the recording scan in the return direction. The claim is characterized in that the recording rate is set by a mask pattern that defines pixels that allow and do not allow dot recording for individual nozzles for each of the outbound scanning and the inbound scanning. Item 6. The inkjet recording apparatus according to any one of Items 7 to 9. The inkjet recording apparatus according to any one of claims 7 to 10, wherein the plurality of types of inks include cyan ink, magenta ink, yellow ink, and black ink.

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