JP6914667B2 - Inkjet recording device - Google Patents

Description

The present invention relates to a recording method in a full-line inkjet recording apparatus.

In a full-line inkjet recording device, a recording medium is placed at a predetermined speed in a direction intersecting the arrangement direction of the nozzles with respect to a recording head in which nozzles for ejecting ink are arranged by a distance corresponding to the width of the recording medium. The image is recorded by transporting with. However, in this case, a plurality of dots arranged in the transport direction on the recording medium are all recorded by the same nozzle. For this reason, the pixel strings recorded by the nozzles having a discharge amount larger than the average or the nozzles having a discharge amount smaller than the average may appear as white streaks or black streaks, which may deteriorate the image quality.

Patent Document 1 discloses a recording method including a step of moving the recording head in the nozzle alignment direction and a step of reciprocating the recording medium a plurality of times in the transport direction while ejecting ink from the recording head. According to the method of Patent Document 1, since the dots recorded by the same nozzle are not arranged in a row in the transport direction of the recording medium, it is possible to reduce the density unevenness according to the ejection characteristics of each nozzle.

Japanese Unexamined Patent Publication No. 2006-096022

By the way, in a full-line type inkjet recording head, there may be a discharge amount distribution that appears gently over the entire recording head, such as a tendency that the discharge amount at the end of the recording head is smaller than that at the center. However, since Patent Document 1 does not assume such a large cycle discharge amount distribution, it is possible to alleviate streaks and density unevenness due to variations in the discharge characteristics of individual nozzles, but it is repeated at a relatively large cycle. It was not possible to reduce the uneven concentration.

The present invention has been made to solve the above problems. Therefore, the purpose is to output a uniform image in which not only the density unevenness caused by the variation in the ejection characteristics of the individual nozzles but also the density unevenness due to the relatively large period due to the discharge amount distribution is suppressed. It is to provide a possible full-line inkjet recording apparatus.

Therefore, the present invention conveys the recording medium in a direction intersecting the predetermined direction with respect to a recording head in which a plurality of nozzles for ejecting ink are arranged in a predetermined direction by a distance corresponding to the width of the recording medium. In an inkjet recording apparatus that records an image on the recording medium by performing a transfer operation, a predetermined number of transfer operations in which the head positions of the recording heads in different predetermined directions are performed to obtain a unit area of the recording medium. The control means includes a control means for stepwisely completing the image, in which the distance between the head positions in the predetermined direction for the predetermined number of transfer operations is the discharge amount distribution of the recording head in the predetermined direction. The head position is set for each of the plurality of transport operations so that the distance is a distance obtained by dividing the cycle or a multiple thereof by the predetermined number or a fraction thereof and is not a multiple of the cycle of the discharge amount distribution. It is characterized by.

According to the present invention, it is possible to output a uniform image in which density unevenness with a relatively large period due to a discharge amount distribution is suppressed.

(A) and (b) are schematic views of a full-line inkjet recording apparatus. (A) to (c) are detailed views of a recording head. It is a block diagram which shows the structure of the control in an inkjet recording apparatus. It is a figure explaining the multi-feed recording. It is a figure which shows the discharge amount distribution of a chip. It is a figure which shows the density distribution of the image which is output when the multi-feed recording is performed. (A) and (b) are diagrams showing another example of performing multifeed recording. (A) and (b) are diagrams showing the multifeed recording of the first embodiment. It is a figure which shows the preferable combination of the multifeed number M and the head position. (A) and (b) are diagrams of the recording head used in the second embodiment. It is a figure which shows the multi-feed recording adopted in 3rd Embodiment.

(First Embodiment)
1A and 1B are schematic views of a recording unit in a full-line inkjet recording apparatus that can be used in the present invention. The two sets of transport roller pairs 104 transport the recording medium S in the ± x direction while niping the recording medium S. In the recording medium S, a smooth surface is maintained in the region located between the two sets of transport roller pairs 104, and the recording head 101 is arranged at a position facing the smooth surface. The recording head 101 extends in the y direction intersecting the x direction by a distance corresponding to the width of the recording medium S, and ejects ink from the ejection port surface 201 in the −z direction. On the other hand, the recording head 101 is supported by a guide shaft 107 extending in the y direction, and can move in the ± y direction along the guide shaft 107 while maintaining a parallel relationship with the recording medium S. ..

Although not shown in the figure, the recording device is also provided with a maintenance unit for performing maintenance on the recording head 101. Maintenance includes a preliminary ejection operation that ejects ink from the recording head 101 unrelated to the image, a purging operation that forcibly ejects ink from the recording head 101, and a wiping operation that wipes off ink adhering to the ejection port surface. Can be mentioned.

2 (a) to 2 (c) are detailed views of the recording head 101. FIG. 2A is a view of the recording head 101 viewed from the discharge port surface 201 side, FIG. 2B is a sectional view taken along line IIB-IIB of FIG. 2A, and FIG. 2C is a view of FIG. 2A. ) Is a cross-sectional view taken along the line IIC-IIC.

In the recording head 101 of the present embodiment, four chips 200 of the same type are arranged so as to be continuous in the y direction while alternately shifting in the x direction as shown in the figure. A plurality of discharge ports 30 are arranged at a constant pitch d on each of the chips 200, and the positions of the four chips 200 are adjusted in the y direction so that the arrangement pitch d is maintained between the chips. In this way, by laminating a plurality of chips of the same type to form one recording head 101, the yield at the time of manufacturing can be improved as compared with the case where a long recording head in which a large number of discharge ports are arranged is manufactured at once. It can be improved.

As shown in FIGS. 2 (b) and 2 (c), each chip 200 is configured by laminating a support member 31, a substrate 32, and a flow path member 33 in this order. The support member 31 and the substrate 32 are formed with ink supply ports 34 for commonly supplying ink received from an ink cartridge (not shown) to the plurality of ejection ports 30, and the flow path member 33 has a plurality of ink supply ports 34. A flow path 36 for individually guiding the ink is formed in the discharge port 30. A partition wall 37 is formed between the flow paths 36 adjacent to each other in the y direction.

On the surface of the substrate 32, a heater 35 (electric heat conversion element) as an energy generating element is arranged at a position facing each discharge port 30. When performing the ejection operation, a voltage pulse is applied to the heater 35 according to the ejection data, and the ink supplied from the flow path 36 is ejected from the ejection port 30. The substrate 32 is made of a material having high thermal conductivity, and the heat generated by the individual heaters 35 easily spreads over the entire chip 200.

FIG. 3 is a block diagram showing a control configuration in an inkjet recording device. Each block (mechanism) is connected to each other via a main bus line 405, and the CPU 400 controls the entire recording device while using the RAM 402 as a work area according to programs and parameters stored in the ROM 401.

For example, the image processing unit 404 performs predetermined image processing on the image data received from the image input unit 403 under the instruction of the CPU 400, and generates ejection data that can be ejected by the recording head 101. The head drive control unit 414 drives the recording head 101 according to the ejection data generated by the image processing unit 404, and ejects ink from the individual ejection ports 30. During such a discharge operation, the transfer control unit 417 drives the transfer motor 409 under the instruction of the CPU 400 to transfer the recording medium S in the + x direction or the −x direction at a predetermined speed. The head movement control unit 415 moves the recording head 101 in the ± y direction by a predetermined amount at a predetermined timing during the recording operation under the instruction of the CPU 400.

The maintenance control unit 407 executes maintenance processing on the recording head 101 under the instruction of the CPU 400. The operation unit 406 receives a command from the user and displays the status of the recording device under the instruction of the CPU 400.

FIG. 4 is a diagram illustrating multi-feed recording in which an image is recorded by reciprocating a recording medium a plurality of times in a transport direction (x direction). In the multi-feed recording, a step of causing the recording head 101 to execute the ejection operation while conveying the recording medium S in the + x direction and a step of causing the recording head 101 to execute the ejection operation while conveying the recording medium S in the −x direction. Repeat alternately. At this time, the CPU 400 causes the recording head 101 to perform the ejection operation according to a part of the dot data that can be recorded in any of the transport operations, and the unit area P of the recording medium is in the + x direction and the −x direction. An image is formed stepwise by a plurality of transport operations. FIG. 4 shows a case where an image of a unit area is formed by five transfer operations. Hereinafter, a step of forming an image focusing on a unit region having a unit width F in the x direction will be described step by step.

In the first transport operation, the CPU 400 transports the recording medium S in the + x direction by a distance corresponding to the 3rd floor. During this transfer, the CPU 400 causes the recording head 101 to perform a discharge operation according to 20% of the dot data corresponding to the unit area. As a result, about 20% of the images are recorded in the unit area.

In the second transport operation, the CPU 400 transports the recording medium S in the −x direction by a distance corresponding to 2F. During this transfer, the CPU 400 causes the recording head 101 to perform a discharge operation according to 20% of the dot data not recorded in the first transfer operation among the dot data corresponding to the unit area. As a result, about 40% of the images are recorded in the unit area.

In the third transport operation, the CPU 400 transports the recording medium S again in the + x direction by a distance corresponding to the 3rd floor. During this transfer, the CPU 400 causes the recording head 101 to perform a discharge operation according to 20% of the dot data not recorded in the first and second transfer operations among the dot data corresponding to the unit area. As a result, about 60% of the images are recorded in the unit area.

In the fourth transport operation, the CPU 400 transports the recording medium S again in the −x direction by a distance corresponding to the 2nd floor. During this transfer, the CPU 400 causes the recording head 101 to perform a discharge operation according to 20% of the dot data not recorded in the first to third transfer operations among the dot data corresponding to the unit area. As a result, about 80% of the images are recorded in the unit area.

In the fifth transport operation, the CPU 400 transports the recording medium S again in the + x direction by a distance corresponding to the 3rd floor. During this transfer, the CPU 400 causes the recording head 101 to perform a discharge operation according to 20% of the dot data not recorded in the first to fourth transfer operations among the dot data corresponding to the unit area. As a result, a 100% image is recorded in the unit area, and the image in the area is completed.

Then, by alternately repeating the transfer operation of 3F in the + x direction and the transfer operation of 2F in the −x direction, the images of the plurality of unit regions arranged in the x direction are obtained from the 3F in the + x direction. It is completed one by one each time the transport operation is performed. By performing the multi-feed recording as described above, the image can be recorded stepwise while promoting the fixing of the ink in the unit area, so that the bleeding of the image can be suppressed and the color development and the density can be improved.

Next, the discharge amount distribution of the recording head, which is an object of the present invention, will be described. FIG. 5 is a diagram showing a discharge amount distribution of the chip 200. The horizontal axis indicates the position of the nozzle in the y direction, and the vertical axis indicates the discharge amount of each nozzle. In an inkjet recording head that converts heat energy into ejection energy as used in this embodiment, the nozzle closer to the end of the chip tends to release heat more easily, so that the ink temperature is lower than that in the center and the ejection amount tends to be smaller. There is. That is, the discharge amount distribution of the recording head follows the temperature distribution of the recording head, and the state as shown in FIG. 5 tends to occur.

FIG. 6 shows the density distribution of the image output when the multifeed recording described in FIG. 4 is performed using the recording head 101 configured by connecting the chips 200 as shown in FIG. 5 in the y direction. It is a figure. Here, the case where the discharge operation is performed evenly with all the nozzles is shown. The horizontal axis indicates the pixel position in the y direction in the image recorded on the recording medium S, and the vertical axis indicates the density corresponding to each pixel position. When the chip 200 as shown in FIG. 5 is used, the discharge amount of the nozzle at the end of the chip is small, so that the concentration becomes low at the position corresponding to the joint of the chips 200. Therefore, the concentration distribution having the period L as shown in FIG. 6 appears repeatedly in the y direction, and is easily recognized as uneven density when visually observed.

7 (a) and 7 (b) are views showing a case where the multi-feed recording is performed while switching the position of the recording head 101 in the y direction at two points. Hereinafter, the recording process in the case of this example will be specifically described.

First, the CPU 400 fixes the recording head 101 in the first position. After that, 20% of the dot data is recorded while the recording medium S is transported in the + x direction by a distance corresponding to the 3rd floor (first transport operation). As a result, about 20% of the images are recorded in the unit area.

Next, the CPU 400 moves the recording head 101 to the second position. After that, while transporting the recording medium S by a distance corresponding to 2F in the −x direction, 20% of the dot data that was not recorded in the first transport operation is recorded (second transport operation). As a result, about 40% of the images are recorded in the unit area.

Next, the CPU 400 returns the recording head 101 to the first position. After that, while transporting the recording medium S by a distance corresponding to the 3rd floor in the + x direction, 20% of the dot data that was not recorded in the first and second transport operations is recorded (third transport operation). As a result, about 60% of the images are recorded in the unit area.

Next, the CPU 400 moves the recording head 101 to the second position again. After that, while transporting the recording medium S by a distance corresponding to the 2nd floor in the + x direction, 20% of the dot data that was not recorded in the first to third transport operations is recorded (fourth transport operation). As a result, about 80% of the images are recorded in the unit area.

Further, the CPU 400 returns the recording head 101 to the first position. After that, while transporting the recording medium S by a distance corresponding to the 3rd floor in the + x direction, 20% of the dot data that was not recorded in the first to fourth transport operations is recorded (fifth transport operation). As a result, about 100% of the images are recorded in the unit area, and the image of the unit area is completed. After that, the recording of the unit area is sequentially completed each time the sixth transfer operation and the seventh transfer operation proceed.

According to the multi-feed recording of this example, the pixel positions extending in the x direction on the recording medium S are arranged with dots recorded by two different nozzles arranged on the recording head 101. Therefore, the dots recorded by one nozzle do not extend in the x direction, and even if there is a nozzle with poor ejection, the influence on the image can be mitigated. However, even if such multi-feed recording is simply performed, it is not possible to reduce the density unevenness having a relatively large period due to the discharge amount distribution of the recording head, which is a problem of the present invention.

FIG. 7B is a diagram showing the concentration distribution when the distance between the first position and the second position in the y direction is 3/16 of the chip length L in the same manner as in FIG. According to the multi-feed recording of this example, the nozzle located at the end of the chip records one pixel line extending in the x direction together with the nozzles separated by 3 L / 16. Therefore, the density of the pixel position recorded by the nozzle located at the end of the chip is not as low as in the case of FIG.

However, the pixel positions with low density due to the nozzle at the end of the chip appear alternately at a relatively short interval of 3L / 16 and a relatively long interval of 13L / 16, as shown in FIG. 7 (b). .. Therefore, as a result, as in FIG. 6, a concentration distribution having a period L appears repeatedly in the y direction, and is recognized as uneven density when visually observed.

In this way, even when multifeed recording is performed while moving the recording heads at a plurality of recording positions, a relatively large period due to the discharge amount distribution of the recording heads depends on the relative distances of the plurality of recording positions. Concentration unevenness may not be reduced. In view of such a situation, it is effective for the present inventors to adjust the position of the recording head in each transport operation based on the cycle of the discharge amount distribution of the recording head 101 when performing multifeed recording. I decided that there was.

8 (a) and 8 (b) are diagrams showing the multi-feed recording adopted in the present embodiment and its effect. The multi-feed recording described here is executed by the CPU 400 according to the programs and parameters stored in the ROM 401. In the present embodiment, the image of the unit area is recorded by the transfer operation five times while switching the position of the recording head 101 in the y direction at five points. Hereinafter, the multifeed recording process of the present embodiment will be specifically described.

First, the CPU 400 positions the recording head 101 at the first position. Then, 20% of the dot data is recorded while the recording medium S is transported in the + x direction by a distance corresponding to the 3rd floor (first transport operation). As a result, about 20% of the images are recorded in the unit area.

Next, the CPU 400 moves the recording head 101 to the second position in the + y direction by L / 5 from the first position. After that, while transporting the recording medium S by a distance corresponding to 2F in the −x direction, 20% of the dot data that was not recorded in the first transport operation is recorded (second transport operation). As a result, about 40% of the images are recorded in the unit area.

Next, the CPU 400 moves the recording head 101 to the third position in the + y direction by L / 5 from the second position. After that, while transporting the recording medium S by a distance corresponding to the 3rd floor in the + x direction, 20% of the dot data that was not recorded in the first and second transport operations is recorded (third transport operation). As a result, about 60% of the images are recorded in the unit area.

Next, the CPU 400 moves the recording head 101 to the fourth position in the + y direction by L / 5 from the third position. After that, while transporting the recording medium S by a distance corresponding to the 2nd floor in the −x direction, 20% of the dot data that was not recorded in the first to third transport operations is recorded (fourth transport operation). As a result, about 80% of the images are recorded in the unit area.

Next, the CPU 400 moves the recording head 101 to the fifth position in the + y direction by L / 5 from the fourth position. After that, while transporting the recording medium S by a distance corresponding to the 3rd floor in the + x direction, 20% of the dot data that was not recorded in the first to fourth transport operations is recorded (fifth transport operation). As a result, about 100% of the images are recorded in the unit area, and the image of the unit area is completed.

Then, in the subsequent sixth transfer operation, the CPU 400 moves the recording head 101 to the first position again. After that, while sequentially moving the recording head 101 to the first to fifth positions, the transfer operation in the + x direction for the 3rd floor and the transfer operation in the −x direction for the 2nd floor are alternately repeated to arrange the recording heads 101 in the x direction. The recording of the unit area will be completed in sequence.

FIG. 8B is a diagram showing the concentration distribution in the case of performing the multifeed recording of the present embodiment in the same manner as in FIGS. 6 and 7 (b). According to the multi-feed recording of the present embodiment, the pixel positions extending in the x direction on the recording medium S are arranged with dots recorded by five different nozzles arranged on the recording head 101. Therefore, the decrease in concentration caused by the nozzle located at the end of the chip is further alleviated as compared with the case of FIG. 7B. Further, the pixel positions having a low density due to the nozzle at the end of the chip appear periodically at relatively short regular intervals (L / 5). Therefore, as compared with the cases of FIGS. 6 and 7 (b) having a period (L), the density unevenness is repeated at a high frequency, and it becomes difficult to visually perceive it.

As described above, according to the present embodiment, each transport operation is performed by shifting the period L of the concentration distribution of the recording head 101 by the distance (L / 5) divided by the number of multifeeds (5). The position of the recording head 101 is set. Therefore, the period in which the low density region appears can be unified over the entire area of the recording head 101 (L / 5), and the density unevenness itself can be visually inconspicuous.

By the way, the configuration for regularly arranging the pixel positions having a low density in a cycle shorter than the chip cycle L is not limited to the recording method shown in FIG. 8A.

FIG. 9 is a diagram showing a suitable combination of a predetermined number of multifeed numbers M and head positions. Here, the number of multifeeds M determines the number of head positions P that can be set for each of 2, 3, 4, 5, 6, 7, and 8, the interval W between these head positions, and the head position in each transfer operation. Illustrate.

For example, when the number of multifeeds M = 4, the number of head positions P may be such that the chip length L is P = L / M = L / 4, but P = L / 2. When P = L / 4, the low concentration region appears in the L / 4 cycle, and when P = L / 2, the low concentration region appears in the L / 2 cycle. Then, in both cases, it is possible to obtain the effect of "setting the period in which the low-concentration region appears to a constant value smaller than L". However, when P = L / 2, the number of movements of the recording head can be suppressed to a small value, and high-speed output of an image becomes possible. Therefore, utilizing such a feature, the CPU 400 may set P = L / 2 when the high-speed recording mode is set, and P = L / 4 when the high-quality recording mode is set. As described above, when the number of multifeeds M has a divisor, the number of head positions P can be set by the number of divisors, not limited to M = 4. On the other hand, when the number of multifeeds M is a prime number, the number of head positions P is limited to P = L / M.

Further, when the number of multifeeds M has a divisor, the head positions corresponding to each transfer operation can be set in various orders even if the number of head positions P is the same. For example, when the number of multifeeds M = 4 and the number of head positions P = 2, the recording head may alternately move the first position and the second position for each transfer operation, but the transfer at the first position is performed. After repeating the operation twice, the recording at the second position may be repeated twice. In the latter case, the recording time can be shortened because the number of times the head is moved is small, but in either case, the unit area of the recording medium is the transfer operation at the first position and the transfer operation at the second position. It is done twice. In other words, the order of the head positions is not particularly limited as long as the head positions and the number of times in the plurality of transfer operations for recording the unit area are unified among all the unit areas.

Further, although a specific example is not shown in FIG. 9, the interval W of the head positions between the transfer operations is a multiple of the chip length L as a divisor of the multifeed number M unless the value is a multiple of L. It may be a divided value. Even in this case, the low-density portions of the image recorded in each transport operation can be arranged at a plurality of locations in the y direction at equal intervals in a cycle smaller than L.

As described above, according to the present embodiment, each transport operation is performed while shifting the recording head by the distance obtained by dividing the period L of the concentration distribution of the recording head or an integral multiple thereof by the number of multifeeds M or a divisor thereof. I do. As a result, the cycle in which the low density region appears can be unified into a short cycle over the entire area of the recording head 101, and the density unevenness can be visually inconspicuous.

(Second Embodiment)
Also in this embodiment, the inkjet recording apparatus described with reference to FIGS. 1 and 3 is used. 10 (a) and 10 (b) are a detailed view of the recording head used in the present embodiment and a diagram showing a discharge amount distribution. As shown in FIG. 10A, in this embodiment, in addition to the first recording head 101 used in the first embodiment, a second recording head 150 is also used. The second recording head 150 has the same width in the y direction as the first recording head 101, and is arranged at a position deviated in the x direction. Further, in the second recording head 150, a second chip 250 different from the first chip 200 arranged in the first recording head 101 is arranged. The chip length of the second chip 250 is half (L / 2) of the chip length L of the first chip 200, and eight second chips 250 are alternately arranged in the x direction on the second recording head 150. It is arranged so as to be continuous in the y direction while shifting to. The first head 101 and the second head 150 may be configured to eject the same type of ink or may be configured to eject different types of ink.

FIG. 10B is a diagram comparing the discharge amount distributions of the first recording head 101 and the second recording head 150. Both the first chip 200 and the second chip 250 have a common tendency that the discharge amount of the nozzle near the end of the chip is smaller than that of the other chips. Therefore, in the image taken by the second recording head 150, twice as many regions with low density appear in half the cycle as compared with the image taken by the first recording head 101.

In this way, when there are a plurality of discharge amount distribution cycles, the head movement distance, that is, the interval W performed between the individual transfer operations is the value obtained by dividing the common multiple of each cycle by a divisor of the multifeed number M. , It may be set to a value that does not become an integral multiple of each cycle. For example, in the case of the present embodiment, the common multiples are L, 2L, and 3L, so when the number of multifeeds is M = 4, W = L / 4, 3L / 4, 5L / 4, and the like can be set. At this time, intervals that match the cycle of the original discharge amount distribution, such as W = 2L / 4 = L / 2 and 4L / 4 = L, are excluded. This is because if the interval is set as described above, the effect of the multifeed recording of the present invention of dispersing the low density region in the y direction cannot be obtained.

(Third Embodiment)
Also in this embodiment, the inkjet recording apparatus and recording head described with reference to FIGS. 1 to 3 are used. In the first embodiment, the multi-feed recording in which the image of the unit region is formed by the transfer operation five times (odd number times) has been described. On the other hand, in the present embodiment, the multi-feed recording in which the image of the unit region is formed by the transport operation four times (even number of times) will be described.

FIG. 11 is a diagram showing a multi-feed recording adopted in this embodiment. Hereinafter, a step of forming an image by paying attention to a unit region having a unit width F in the x direction will be described.

First, the CPU 400 transports the recording medium S in the + x direction by a distance corresponding to the 3rd floor (first transport operation). At this time, while the first distance F (0 to F) is conveyed, the CPU 400 moves the recording head 101 to the first position without causing the recording head 101 to perform the ejection operation. Then, while the subsequent distances 2F (F to 3F) are conveyed, the CPU 400 keeps the recording head 101 fixed at the first position and follows the recording head 101 according to 25% of the dot data corresponding to the unit area. To perform the discharge operation. As a result, about 25% of the images are recorded in the unit area.

Next, the CPU 400 moves the recording head 101 to the second position in the + y direction by L / 4 from the first position. Then, while the recording medium S is conveyed in the −x direction by a distance corresponding to 2F, 25% of the dot data that was not recorded in the first transfer operation is recorded (second transfer operation). As a result, about 50% of the images are recorded in the unit area.

Next, the CPU 400 conveys the recording medium S again in the + x direction by a distance corresponding to the 3rd floor. At this time, while the first distance F is conveyed, the CPU 400 moves the recording head 101 to the third position in the + y direction by L / 4 from the second position without performing the ejection operation. Then, while the subsequent distance 2F is conveyed, the CPU 400 does not record in the first and second transfer operations of the dot data corresponding to the unit area in a state where the recording head 101 is fixed at the third position 25. The recording head 101 is made to perform the ejection operation according to the dot data of%. As a result, about 75% of the images are recorded in the unit area.

Further, the CPU 400 moves the recording head 101 to the fourth position in the + y direction by L / 4 from the third position. Then, while the recording medium S is conveyed in the −x direction by a distance corresponding to the 2nd floor, 25% of the dot data that was not recorded in the first to third transfer operations is recorded (fourth transfer operation). As a result, about 100% of the images are recorded in the unit area, and the image of the unit area is completed.

Then, in the subsequent fifth transport operation, the CPU 400 moves the recording head 101 to the first position again while transporting the recording medium S in the + x direction by a distance corresponding to the 3rd floor, and the recording head 101 has 25% dot data. The discharge operation is performed accordingly. After that, while sequentially moving the recording head 101 to the first to fourth positions, the transfer operation in the + x direction for the 3rd floor and the transfer operation in the −x direction for the 2nd floor are alternately repeated to arrange the recording heads 101 in the x direction. The recording of the unit area will be completed in sequence.

According to the multi-feed recording of the present embodiment, the pixel positions extending in the x direction on the recording medium S are arranged with dots recorded by four different nozzles arranged on the recording head 101. Therefore, the decrease in density caused by the nozzle located at the end of the chip is alleviated as compared with the case of FIG. 7B, and a uniform image can be obtained.

Further, in the case of multi-feed recording of an even number of times as in the present embodiment, a transfer process without a discharge operation occurs as in the first transfer operation and the third transfer operation, and the recording head is moved during this period. be able to. Therefore, the image output can be completed at a higher speed than in the first embodiment (multi-feed recording of an odd number of times), which requires a step of moving the recording head in advance for each transfer operation.

(Other embodiments)
In the above embodiment, the case where the period of the discharge amount distribution is equal to the chip length has been described as an example, but the discharge amount distribution in the recording head does not always appear in the cycle of the chip length. The discharge amount distribution in the recording head also depends on the wiring configuration and the flow path configuration in the recording head. For example, when a plurality of nozzles arranged in a chip are divided into a plurality of blocks and individual wiring is prepared for each block, a discharge amount distribution with one block as a cycle may occur. Therefore, in such a case, it is preferable to set the interval W of the multifeed recording based on the block length instead of the chip length.

Further, for example, referring to FIG. 2 again, when one or more beams are provided in the middle of the substrate 32 at equal intervals in the y direction for the purpose of suppressing the temperature at the center of the chip, heat conduction is cut off at the beam portion. Therefore, the nozzle in the vicinity of the beam tends to have a small discharge amount. Therefore, in such a case, it is preferable to set the interval W of the multifeed recording based on the beam interval instead of the chip length.

In any case, by setting the movement interval W of the recording head in the multi-feed recording based on the period L of the discharge amount distribution in the recording head to be used, the concentration unevenness having a relatively large cycle due to the discharge amount distribution can be suppressed. It is possible to output a uniform image.

30 Nozzle 101 Recording head 400 CPU
414 Head drive control unit 415 Head movement control unit 417 Conveyance control unit
S Recording medium

Claims (12)

By performing a transport operation of transporting the recording medium in a direction intersecting the predetermined direction with respect to a recording head in which a plurality of nozzles for ejecting ink are arranged in a predetermined direction by a distance corresponding to the width of the recording medium. In an inkjet recording apparatus that records an image on the recording medium,
A control means for stepwisely completing an image of a unit region of the recording medium by a predetermined number of transfer operations in which the head positions of the recording heads in the predetermined directions are different from each other.
In the control means, the interval between the head positions in the predetermined direction for the predetermined number of transport operations is the predetermined number or a divisor thereof, which is the period of the discharge amount distribution in the predetermined direction of the recording head or a multiple thereof. An inkjet recording apparatus, characterized in that the head position is set for each of the plurality of transport operations so that the distance is divided by the above and is not a multiple of the period of the discharge amount distribution. When there are a plurality of cycles of the discharge amount distribution, the control means performs each of the plurality of transport operations so that the interval is a distance obtained by dividing the common multiple of the plurality of cycles by the predetermined number or a divisor thereof. The inkjet recording apparatus according to claim 1 , wherein the head position is set. The control means is characterized in that the head position is set for each of the high-speed recording mode and the high-quality recording mode so that the interval in the high-speed recording mode is larger than the interval in the high-quality recording mode. The inkjet recording apparatus according to claim 1 or 2. The predetermined number is an odd number, and the control means moves the recording head to the set head position before executing each of the predetermined number of transport operations, according to claims 1 to 3 . The inkjet recording apparatus according to any one item. The predetermined number is an even number, and the control means includes, in the transport operation of the predetermined number, a transport operation of moving the recording head to the set head position while transporting the recording medium. The inkjet recording apparatus according to any one of claims 1 to 3. By performing a transport operation of transporting the recording medium in a direction intersecting the predetermined direction with respect to a recording head in which a plurality of nozzles for ejecting ink are arranged in a predetermined direction by a distance corresponding to the width of the recording medium. In an inkjet recording apparatus that records an image on the recording medium,
A control means for stepwisely completing an image of a unit region of the recording medium by a predetermined number of transfer operations in which the head positions of the recording heads in the predetermined directions are different from each other.
The predetermined number is an even number
The control means sets the head position for each of the plurality of transport operations to a position corresponding to the cycle of the discharge amount distribution in the predetermined direction of the recording head, and during the predetermined number of transport operations, the control means sets the head position. An inkjet recording apparatus including a transport operation in which the recording head is moved to a set head position while transporting the recording medium. The inkjet recording apparatus according to any one of claims 1 to 6 , wherein the period of the discharge amount distribution corresponds to the length of the chips arranged in the recording head in the predetermined direction. The inkjet recording apparatus according to any one of claims 1 to 6 , wherein the period of the discharge amount distribution corresponds to the period of the temperature distribution of the recording head in the predetermined direction. The inkjet recording apparatus according to any one of claims 1 to 6 , wherein the period of the discharge amount distribution corresponds to the period of the wiring configuration formed on the recording head. The recording head according to any one of claims 1 to 9 , wherein the recording head discharges ink by applying a voltage to an electric heat conversion element arranged corresponding to each of the plurality of nozzles. The inkjet recording apparatus described. By performing a transport operation of transporting the recording medium in a direction intersecting the predetermined direction with respect to a recording head in which a plurality of nozzles for ejecting ink are arranged in a predetermined direction by a distance corresponding to the width of the recording medium. In the inkjet recording method for recording an image on the recording medium,
It has a control step of stepwisely completing an image of a unit region of the recording medium by a predetermined number of transfer operations in which the head positions of the recording heads in the predetermined directions are different.
In the control step, the interval between the head positions in the predetermined direction for the predetermined number of transfer operations is the predetermined number or a divisor thereof, which is the cycle of the discharge amount distribution in the predetermined direction of the recording head or a multiple thereof. An inkjet recording method, characterized in that the head position is set for each of the plurality of transport operations so that the distance is divided by the above and is not a multiple of the period of the discharge amount distribution. By performing a transport operation of transporting the recording medium in a direction intersecting the predetermined direction with respect to a recording head in which a plurality of nozzles for ejecting ink are arranged in a predetermined direction by a distance corresponding to the width of the recording medium. In the inkjet recording method for recording an image on the recording medium,
It has a control step of stepwisely completing an image of a unit region of the recording medium by a predetermined number of transfer operations in which the head positions of the recording heads in the predetermined directions are different.
The predetermined number is an even number
In the control step, the head position for each of the plurality of transfer operations is set to a position corresponding to the cycle of the discharge amount distribution in the predetermined direction of the recording head, and the predetermined number of transfer operations are performed. An inkjet recording method comprising a transport operation of moving the recording head to a set head position while transporting the recording medium.

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