JP2006168111A - Inkjet recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording device which permits aquisition of good recording quality without causing bleeding or white streaks and prevents the characteristic degradation of a recording head and exhibits reliability even when the number of scans of multipass is reduced and fast recording is performed. <P>SOLUTION: The inkjet recording device uses two sets of recording heads arranged in a manner that makes recording element arrays to be symmetrical in a main scanning direction. A recording ratio setting area in the recording element array direction is divided in two or more, different recording ratios are set for the divided areas, recording is performed in different recording ratio distributions by a first recording head and a second recording head. Each recording head performs recording, switching among a plurality of recording ratio distributions at each scan. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ink jet recording apparatus that performs recording by discharging ink from a recording head to a recording material.

  With the spread of information processing equipment such as copying machines, word processors, computers, and communication equipment, one of the recording devices of these equipment is rapidly performing digital image recording using an ink jet recording head. It is popular. In such a recording apparatus, in order to improve the recording speed, a recording element array in which a plurality of recording elements are integrated and arranged uses a plurality of ink discharge ports and a plurality of liquid passages, and a plurality of arrays for color correspondence. The above-mentioned recording element array is generally used.

  However, unlike a monochrome printer that records only a character, various elements such as color development, gradation, and uniformity are required to record a color image. In particular, with regard to uniformity, slight variations in recording element units that occur due to differences in the production process of recording element arrays affect the amount of ink ejected and the direction of the ejection direction of each recording element. Causes deterioration of image quality as density unevenness of the recorded image.

  Therefore, in the conventional ink jet recording apparatus, a multi-pass recording method is applied in which all pixels to be recorded in the same recording scan are divided into a plurality of groups, and the same recording area is recorded one by one by a plurality of reciprocating recording scans. There are some (see, for example, Patent Document 1). By performing such multi-pass recording, all the recording pixels in the image area that can be recorded by one recording scan are recorded on a recording image unique to each recording element in order to record using different recording elements for each scanning. Therefore, the density unevenness of the recorded image is considerably reduced.

  By the way, at present, the resolution and color of the image have been improved, the image quality has been improved remarkably, and the discharge amount per dot has been reduced to realize a further high resolution image, while at the same time approaching a silver-edge photo. In order to realize image quality, a technique for simultaneously recording light ink with a lighter density in addition to basic four color inks (cyan, magenta, yellow, and black) has been proposed and implemented. However, there are also concerns about adverse effects caused by reducing the discharge amount per dot (dot landing position deviation, discharge stability, etc.).

  For example, when an image is formed by a recording head having 256 recording elements at each color discharge amount of 4 pl and 1200 dpi, the landing positions of the recording elements at both ends of the recording head are significantly shifted (hereinafter, this phenomenon will be referred to as the phenomenon). Inconvenience occurs in that part is called a part. FIG. 4 shows a state in which the landing position of the ink droplet greatly depends on the paper feed boundary. As shown in the figure, in a recording head with a 1200 dpi pitch and a discharge amount of 4 pl, the landing position of several dots at which recording starts is not changed, but starts to change as the carriage accelerates, and is about 50 μm.

  FIG. 5 schematically shows the ejection tendency of the recording head as viewed from the carriage direction when the dots at both ends of the recording head have already started to crawl. As shown in the figure, it is clear that the number recording elements at both ends of the recording head tend to be inclining. Such a tendency is particularly noticeable when an image is formed with a minimal dot such as 4p1. Then, the shading of the dots forms a portion that is recognized as a white stripe in terms of visual characteristics. For this reason, conventionally, it has been considered to increase the number of multipaths so that white lines are not visually noticeable. However, since the above measures hinder the speeding up, there is a disadvantage that it is not suitable for further speeding up.

  Therefore, in an inkjet recording apparatus using a multi-pass recording method, the same scanning recording area is divided at a predetermined pitch, and the recording duty determined by the thinning mask pattern is set to a different value for each divided area. Is known (see, for example, Patent Document 2). In this case, by setting the recording duty for the divided areas located at both ends of the same area formed by each main scan to a value smaller than the recording duty of the divided areas located inside the white areas, A high-resolution image can be formed at high speed while suppressing deterioration in image quality due to density unevenness or the like.

  However, when multi-pass reciprocal recording as described above is performed, the priority color varies depending on the ink ejection order, and as a result, a different color may be expressed with respect to human visual characteristics. For example, each color of a four-color head is arranged from the right in the order of black, cyan, magenta, and yellow, and main scanning is performed by reciprocating in the head arrangement direction (left-right direction). In the forward scan, recording is performed simultaneously by moving in the right direction. At this time, since the recording order on the paper surface is in accordance with the arrangement order described above, for example, when a green (cyan + yellow) signal is input to a certain area, ink is absorbed in the order of cyan and yellow in each pixel. The Therefore, as already described, in this scanning, cyan absorbed earlier becomes the priority color, and green dots having a strong cyan color are formed. On the contrary, in the backward scanning after the paper feeding is performed in the sub-scanning direction, the recording is performed while moving in the direction opposite to the forward path. Therefore, the driving order is reversed, and green dots having a strong yellow tint are obtained in this scanning. By repeating the scanning as described above, green dots having a strong cyan color and green dots having a strong yellow color are recorded in accordance with the forward and backward passes of the recording heads. If paper feed is performed by the head width for each reciprocating scan, a green area with a strong cyan hue and a green area with a strong yellow hue are repeated alternately for each head width. Significant image degradation will occur in the green image that should be.

Therefore, two sets of recording heads are used in which the recording element arrays of the respective inks are arranged symmetrically in the main scanning direction so that the order in which the inks are overlapped in the forward recording and the backward recording is the same. An ink jet recording apparatus is known (see, for example, Patent Document 3). According to this, color unevenness due to the ink ejection order does not occur, and high-speed recording can be achieved without increasing the number of multipass scans.
U.S. Pat. No. 4,748,453 JP 2002-096455 A JP 2000-079681 A

  However, the above conventional example has the following problems to be solved.

  That is, the print data is divided into two sets of print heads, and the same scanning print area in both print heads is divided at a predetermined pitch, and the print duty determined by the thinning mask pattern is set to a different value for each divided area. In the inkjet recording apparatus, since the recording element group in a certain divided area is used at a high frequency and the recording element group in the other divided area has a recording ratio distribution so that the frequency of use is low, the recording element part that is frequently used. There is a tendency that the temperature of is relatively higher than the other parts. Therefore, as a result, there is a defect in that the discharge amount in the printing element array is varied and density unevenness is caused in the image.

  Furthermore, since the number of times of ejection always increases in the frequently used recording element portion as compared with the infrequently used recording element portion, the recording element and the recording element in that portion wear out, resulting in deterioration of the characteristics, and the recording head. There was a serious problem that the durability performance of the device itself was significantly lowered.

  Also, in the divided area of both heads, if the high recording duty setting area overlaps in the same area, both heads will eject a large amount of ink to the recording medium in adjacent areas. There is a problem that the boundary of ink dots are combined and mixed between other colors, or a bleeding-like state that blurs characters and ruled lines occurs, resulting in a significant deterioration in image quality. .

  Accordingly, the present invention has been made to solve the above-described problems, and causes bleeding and white streaks even when high-speed printing is performed by reducing the number of multipass scans without causing color unevenness. It is an object of the present invention to provide a highly reliable ink jet recording apparatus that can obtain excellent recording quality without causing deterioration of characteristics of a recording head.

  In order to achieve the above object, the ink jet recording apparatus of the present invention includes two sets of recording heads each having a recording element array group corresponding to each ink color used for recording, and is related to forward scanning and backward scanning of each recording head. An ink jet recording apparatus using two sets of recording heads in which the respective recording element array groups are arranged symmetrically in the main scanning direction so that the respective inks are stacked in the same order. A recording ratio setting unit configured to divide the recording ratio setting area of the element array into a plurality of parts and set a different recording ratio for each of the divided areas; and the recording ratio setting unit includes the recording element array of the first recording head. The print ratio distribution in the direction and the print ratio distribution in the print element array direction of the second print head are set to different distributions, and the print heads are recorded for each scan. An ink jet recording apparatus comprising the recording ratio setting changing means for setting by switching the ratio distribution to different recording ratios distributions.

  In this case, among the recording ratio setting areas in each head, an area having a high recording ratio is different in each head, so that a large amount of ink is not injected into a specific area, and bleeding and High-speed recording can be achieved by reducing color mixing as much as possible.

  Further, among the recording ratio setting areas in each head, the area having a high recording ratio is set to be different for each scanning, thereby causing variations in temperature distribution and characteristics in the recording element array. In addition, not only density unevenness does not occur, but also wear deterioration of the recording element group does not concentrate in a specific area, so that the life of the recording head can be increased.

  Further, according to the present invention, the print heads having the print element array groups corresponding to the respective ink colors used for printing are configured in two sets, and the order in which the respective inks are stacked is the same regardless of the forward scan and the backward scan of each print head. As described above, an ink jet recording apparatus using two sets of recording heads in which each recording element array group is arranged symmetrically in the main scanning direction, and the recording ratio of each recording element array in the same scanning recording area of both heads A setting area is divided into a plurality of areas, and each of the divided areas has a mask pattern setting means for setting the recording ratio determined by the mask pattern to a different value, and the mask pattern setting means includes a first recording head A first mask pattern for setting a recording ratio distribution in the recording element array direction and a second mask pattern for setting a recording ratio distribution in the second recording element array direction. Sets the recording ratio of the mask pattern with different distributions, an ink jet recording apparatus comprising the mask pattern setting changing means for setting the switching to the plurality of mask patterns different for each scan.

  As a result, it is possible to easily generate image data having a complementary relationship between the heads, and to easily change the recording ratio distribution in the recording element array direction for each scan and the recording ratio in each divided area. This is good.

  As described above, according to the present invention, it is possible to obtain excellent recording quality without causing density unevenness and white streaks even in the case of performing high-speed recording by reducing the number of multipass scans, In addition, a highly reliable ink jet recording apparatus can be realized without deteriorating the characteristics of the recording head. That is, in the present invention, the recording ratio setting area in the recording element array direction is divided into a plurality of areas, a different recording ratio is set for each of the divided areas, and recording is performed by the first recording head and the second recording head. Since recording is performed with recording ratio distributions having different recording ratio distributions in the element array direction, and each recording head performs recording by switching a plurality of recording ratio distributions for each scan, the high recording ratio areas in both heads are different areas. Thus, it is possible to achieve high-reliability and high-speed recording without minimizing density unevenness and without causing partial deterioration of characteristics in the printing element array.

  1 to 2 are diagrams for explaining a configuration example of an ink jet recording apparatus capable of ejecting ink using the above-described liquid ejection principle.

  FIG. 1 is a diagram showing a configuration of a recording unit of an ink jet recording apparatus of the present invention.

  Reference numeral 401 denotes a first recording head, which includes ink tanks filled with color inks of six colors (Bk, L-Cy, Cy, Mg, L-Mg, Ye) and six recording element arrays corresponding to the respective ink tanks. Is composed of an integrated multi-recording head. A second recording head 402 has the same configuration as the first recording head 401, and is a recording head for recording ink of six colors (Ye, L-Mg, Mg, Cy, L-Cy, Bk). The arrangement is symmetrical with the arrangement of the recording heads 401.

  A carriage 403 supports the first recording head 401 and the second recording head 402 and moves them together with recording. The carriage 403 is at the home position position ◎ shown in the figure during standby such as a non-recording state. Reference numeral 404 denotes a paper feed roller that rotates in the direction of the arrow in the figure while holding the recording medium 407 together with the auxiliary roller 405 and feeds the recording medium 407 in the Y direction as needed. Reference numeral 406 denotes a paper feed roller that feeds the recording medium 407 and plays a role of suppressing the recording medium 407 in the same manner as the paper feed roller 404 and the auxiliary roller 405.

  A basic reciprocal recording operation in the above configuration will be described.

  During the standby, the carriage 403 at the home position position ◎ scans in the X direction by a recording start command, and the recording medium 407 according to the recording data by the plurality of nozzles of the first recording head 401 and the second recording head 402. Ink is ejected onto the recording. When the recording of the recording data to the end of the recording medium 407 is completed, the carriage 403 returns to the original home position position ◎. As the paper feed roller 404 rotates in the direction of the arrow, the paper is fed by a predetermined width in the Y direction, and recording in the X direction is started again. Recording data is recorded by repeating the scanning operation and the paper feeding operation.

  Here, the first recording head 401 and the second recording head 402 have the first recording head 401 arranged on the front side in the forward scanning direction, and the nozzles from which the inks of the respective colors are ejected are Bk, L-Cy, Cy, Mg from the top. , L-Mg, Ye. In addition, a second recording head 402 is disposed on the rear side, and the nozzles from which inks of various colors are ejected are symmetrical to the first recording head 401 in the order of Ye, L-Mg, Mg, Cy, L-Cy, and Bk. Arrange. This is shown in FIG.

  FIG. 3 is a schematic block diagram of the control system of such a recording apparatus. The recording apparatus receives recording information as a control signal from the host computer 300. The recording information is temporarily stored in the input / output interface 301 in the recording apparatus, and at the same time, converted into data that can be processed in the recording apparatus, and input to the CPU 302 that also serves as a recording head drive signal supply unit. The CPU 302 processes the data input to the CPU 302 using peripheral units such as the RAM 304 based on a control program stored in the ROM 303, and converts the data into data (image data) to be recorded.

  Further, the CPU 302 generates drive data for a drive motor 306 that moves the recording medium 407 and the recording heads 401 and 402 in synchronization with the image data in order to record the image data at an appropriate position on the recording medium 407. The image data and the motor drive data are transmitted to the recording heads 401 and 402 and the drive motor 306 via the head driver 307 and the motor driver 305, respectively, so that an image is formed at a controlled timing.

  The ink jet recording apparatus according to the present invention not only performs reciprocal recording by dispersing recording dots on the first recording head 401 and the second recording head 402, but also multi-pass recording system that forms an image by scanning the same region a plurality of times. Is adopted. As described above, multi-pass printing is a printing method that suppresses density unevenness due to slight differences in the ejection amount and ejection direction of ink for each nozzle by forming an image using a plurality of nozzles for one line. In particular, in the first embodiment, among the multi-pass printing methods, the random mask thinning method for generating print data by eliminating the regularity of the used nozzles and randomly thinning the data, and the print data by thinning the print dots The multi-pass recording method is used in combination with the data thinning method for generating the image. The number of recording passes is assumed to be 4-pass recording.

  Details of a method for generating print data for each print head will be described later.

  First, a first embodiment according to the characteristic configuration of the present invention will be described.

  In this embodiment, random mask patterns (see FIG. 6) of A and B stored in the RAM 304 are used, and thinning processing is performed by a staggered pattern (FIG. 7A) and an inverted staggered pattern (FIG. 7B). To perform four-pass reciprocal printing of recording data. The random mask patterns A and B and the zigzag / inverted zigzag pattern were each prepared with a recording density of 1200 dpi and a recording area of 655360 pixels in total of 1280 pixels in the raster direction and 512 pixels in the column direction. That is, as shown in FIG. 7, the ratio of recording pixels to the recording area (hereinafter referred to as “printing duty”) is opposite to a pattern (FIG. 7-a) that is exactly a staggered pattern for each vertical and horizontal pixel. Using a pattern that forms a staggered pattern (FIG. 7B), the print pixels are distributed to 50% duty print pixels. Further, a random mask A (FIG. 6A) in which 1280 pixels in the raster direction are divided into eight and the recording duty of each divided region is set to a different value, and the recording duty of the divided region of the random mask pattern A A random mask pattern B (FIG. 6B) set to a different value was also created. The random mask patterns A and B are complementary masks such that the recording duty in each divided area is 100% when sub-scanning is performed every 320 pixels, as shown in FIG. The recording duty in each divided area is (10%, 20%, 30%, 40%, 40%, 30%, 20%, 10%), (10%, 40%, 30%, 20%, 20%, The recording duty is 30%, 40%, 10%).

  Here, a distribution method for the thinning pattern used in each head for 4-pass reciprocal printing will be described. Among the first recording head and the second recording head, when the recording head is in the forward scan, the first recording head performs a data thinning process using a staggered pattern (FIG. 7A), and a random mask pattern A (FIG. 6). A thinning pattern (1) in which only the portion where the recording pixels overlap with a) are printed pixels is subjected to data thinning processing by reverse zigzag pattern (FIG. 7B) in the case of backward scanning, and random mask pattern B (FIG. The thinning pattern (2) is used in which only the portions where the recording pixels overlap with 6-b) are printed pixels. On the other hand, in the second recording head, the thinning pattern (2) is used when the recording head is in the forward scanning, and the thinning pattern (1) is used in the backward scanning, so that the area can be recorded by one scanning. Can be distributed to the first recording head and the second recording head every four scans. FIG. 8 is a flowchart for explaining the print data generation processing for the first print head by the CPU 302 in the control system in the printing apparatus. When a print image is input from the input / output interface (step S1001), −1 is first added to n, and it is determined whether it is a forward scanning pass or a backward scanning pass (step S1003). n is a variable representing the scanning direction, and represents the scanning direction by its sign, and 1 is written in the initial value. Among the reciprocating scans, when the main scan is the forward scan (when n is negative), the input image is multiplied by the staggered mask pattern (step S1004-b), and then the input image is multiplied by the random mask pattern A. (Step 1005-b). In the case of backward scanning (when n is positive), the input image is multiplied by the reverse zigzag pattern (step S1004-a), and then the random mask pattern B is multiplied (step S1005-a). At this point, the print image thinning process ends, and print data to be printed in each scanning direction is completed (S1006). When the recording data is output to the first recording head controller, the recording data is transferred to the recording head at an appropriate timing and recording is performed. Finally, when the recording data generation of all the image data has been completed, the recording data generation processing of the first recording head is ended, and when the image data remains, the process returns to step S1002 and n is set to -1. Then, the recording data generation process is performed again.

  Similarly, FIG. 9 is a flowchart for explaining the second print head print data generation process. The second recording head determines the scanning direction of the recording head according to whether the scanning direction variable is positive or negative, and in the case of forward scanning, after multiplying the input image by the inverted staggered pattern (S1004-b), the random mask pattern B is obtained. In the case of multiplication (S1005-b) and backward scanning, the input image is multiplied by the staggered pattern (S1004-a), and then the random mask pattern A is multiplied (S1005-a).

  When 4-pass reciprocal printing is performed with the recording data, the image data is masked by the random mask pattern A at the head recording head and the random mask pattern B at the recording head at the rear side in each scan. Random mask patterns that are complementary to each other in pass scanning have a relationship that complements image data without causing color unevenness or the like without always changing the order of ink ejection. In this case, since each random mask pattern is printed and shifted by 320 pixels between each scan, each of the random mask patterns is complemented by 4-pass printing, and each of them is complemented by a staggered / reverse staggered pattern. In order to achieve a general relationship, printing is performed by thinning out by 50%.

  FIG. 11A is a list of evaluation results for evaluating the effects of the present invention. In the conventional example, a recording area of 1280 pixels is divided into eight, and a random mask pattern in which each recording duty is always (10%, 20%, 30%, 40%, 40%, 30%, 20%, 10%). The four-pass printing by two heads is completed by performing the data thinning process with the staggered pattern in the first recording head and the reverse staggered pattern in the second recording head regardless of the scanning direction.

  The evaluation items are variation in ejection amount, density unevenness due to the amount of ink applied, white stripes due to edge deviation, and the durability of the head. Evaluations other than the lifespan were performed on solid images with 100% duty printing for each color, and after evaluating each color, the average of the evaluation results for 6 colors was taken. The evaluation points are ◎, ○, △, ×, XX, where ◎ to ○ are visually indistinguishable levels, △ is a conspicuous level at a clear viewing distance of 30 cm, and XX to XX are clear. The level was conspicuous at a distance of 1 m. Regarding the durable life, when 100% duty printing is repeated, the maximum number of ejections of the recording element at the time when a sudden characteristic deterioration (non-ejection, density unevenness, uneven stripes, etc.) occurs compared to the initial printing, Comparison was made with the maximum number of ejections when printing was performed with a uniform recording duty in each divided area (the recording duty of each divided area was 25%). For example, if the maximum number of ejections until the characteristic deterioration occurs when printing is performed with a uniform recording duty in each divided area is 100, if the maximum number of ejections in the conventional example is 70, 70. The evaluation result is an evaluation that the evaluation is higher as the value approaches 100.

  Regarding white stripes, both the mask pattern in the present embodiment and the mask pattern used in the conventional example have a lower recording duty at both ends of the divided region of the printing element array than that of other divided regions. Since it is set to a value, white streaks due to edge twisting tend to be inconspicuous. However, in the thinning pattern using the random mask pattern B among the mask patterns in the present embodiment, the recording area at the end and the high duty recording area are adjacent (10% to 40%), and there is a step in the recording duty. Therefore, the level was slightly lower than that of the conventional example.

  Regarding the density unevenness, the mask pattern in this embodiment replaces the recording duty for each scan, and the high duty recording area (here, the 40% recording ratio area in the random mask) is different in both heads. Since the mask pattern is set in such a manner, there is an effect of reducing the concentration of the locally applied ink amount and uniforming the discharge amount variation in the printing element array, and it does not occur at all. On the other hand, in the conventional example, the central portion of the printing element array always performs high-duty printing, so the temperature rises locally and the discharge amount is enlarged compared to the end portion. In addition, since the high duty recording area is the same area of the same scanning area in both heads, density unevenness is visually noticeable, and the x level is discriminable with a clear visual distance of about 1 m. .

  Further, in the conventional example, since the frequency of using the central portion of the printing element array is always high, partial deterioration in the printing element array is caused and as a result, the life of the recording head is shortened, resulting in 62.5. It was. According to the present embodiment, since the recording duty of each divided area is changed for each scanning, a long life of 83.3 can be achieved without deteriorating the specific recording element.

  In this embodiment, the recording duty of the mask pattern A is (10%, 20%, 30%, 40%, 40%, 30%, 20%, 10%), and the recording duty of the mask pattern B is ( 10%, 40%, 30%, 20%, 20%, 30%, 40%, 10%). However, the values may be selected appropriately depending on the characteristics of the recording head, the printing mode, the recording medium, etc. In this case, the high recording duty area may be set to a different divided area for each scanning.

  In this embodiment, the recording data is thinned out with the random mask pattern and the zigzag / reverse zigzag mask pattern that are complementary in 4-pass printing, and control is performed so that both heads complement each other. A random mask pattern in a complementary relationship may be prepared at the head, and an optimal mask pattern suitable for the control and the memory capacity of the main body may be used.

  In the present embodiment, in the 4-pass printing, the same control as that described in the first embodiment is performed except that the high duty recording area is always an adjacent area among the divided areas in the printing element array direction. Will be described.

  In this embodiment, a random mask pattern (see FIG. 10) stored in the RAM 304 is used, and thinning processing is performed using a staggered pattern (FIG. 7a) and an inverted staggered pattern (FIG. 7b). Is performed to perform 4-pass printing of recorded information. The random mask patterns A and B and the zigzag / inverted zigzag pattern were each prepared with a recording density of 1200 dpi and a recording area of 655360 pixels in total of 1280 pixels in the raster direction and 512 pixels in the column direction. Random mask patterns A and B are obtained by dividing 1280 pixels in the raster direction into 8 parts, the recording duty of each divided area is set to a different value, and the area having a high duty among the divided areas is set to a different area. Has been. The random mask patterns A and B are complementary masks such that the recording duty in each divided area is 100% when sub-scanning is performed every 320 pixels, as shown in FIG. The recording duty in each divided area is (10%, 40%, 40%, 30%, 30%, 20%, 20%, 10%), (10%, 20%, 20%, 30%, 30%, The recording duty is 40%, 40%, 10%).

  Similar to the first embodiment, a thinning pattern (3) (not shown) in which only the overlapped portion of the staggered pattern and the random mask pattern A is printed during forward scanning of the first recording head and backward scanning of the second recording head. And a thinning pattern (4) (not shown) in which only the overlapped portion of the reverse zigzag pattern and the random mask pattern B is printed at the time of backward scanning of the first recording head and at the time of forward scanning of the second recording head. use. When four-pass printing is performed with the recording data thinned out by the thinning pattern, sub-scans of 320 pixels are performed between each scan, so that the image data masked by each of the random mask patterns A and B is 4 The relationship is such that it is complemented by pass recording, and printing is performed by thinning out by 50% so that each has a complementary relationship with a staggered / reverse staggered pattern.

  FIG. 11B is a list of evaluation results obtained by evaluating the effects in the present example with the same evaluation contents as those in the first example. In the conventional example, a 1280 pixel recording area is divided into 8 and a random mask pattern in which each recording duty is (10%, 20%, 30%, 40%, 40%, 30%, 20%, 10%) is used. Regardless of the scanning direction, 4-pass printing with 2 heads is completed by performing data thinning processing with a staggered pattern in the first recording head and a reverse staggered pattern with the second recording head.

  Regarding white stripes, both the mask pattern in the present embodiment and the mask pattern used in the conventional example have a lower recording duty at both ends of the divided region of the printing element array than that of other divided regions. Since it is set to a value, white streaks due to edge twisting tend to be inconspicuous. In both mask patterns, the recording duty at the end was 10%, both of which were ◎ level.

  Concerning density unevenness, the mask pattern in this embodiment switches the recording duty for each scan, and the area printed at 40% duty is printed alternately at 20% duty. This has the effect of greatly reducing and uniforming the discharge amount variation in the printing element array, and does not occur at all. On the other hand, in the conventional example, since the central portion of the printing element array always performs 40% duty printing, the temperature rises locally, and the discharge amount is enlarged compared to the end portion, causing density unevenness. The x level was discriminable at a clear vision distance of about 1 m.

  Further, in the conventional example, since the frequency of using the central portion of the printing element array is always high, it causes partial deterioration in the printing head, resulting in shortening the life of the printing head, resulting in 62.5. . According to the present embodiment, since the recording duty of each divided area is changed for each scan, it is possible to achieve a long life of 83.3 without deteriorating the specific recording element.

  Note that the recording duty used in this embodiment may be appropriately changed depending on the characteristics of the recording head, the width of the recording element array, the recording medium, and the like. If it is set to such a value, there is no particular limitation.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an external perspective view for explaining an embodiment of an ink jet recording apparatus of the present invention. FIG. 3 is an explanatory diagram illustrating a configuration of a recording head used in the first embodiment of the present invention. FIG. 2 is a block diagram illustrating a configuration of a recording head control block according to the first embodiment of the present invention. FIG. 4 is an explanatory diagram viewed from a plane direction of a phenomenon that ink dots are generated at an end portion of a recording head. FIG. 3 is an explanatory diagram of a phenomenon that ink dots are generated at an end portion of a recording head when viewed from the front of the recording head. It is a schematic diagram which shows the random mask pattern used for the 1st Embodiment of this invention. It is a schematic diagram which shows the zigzag / reverse zigzag pattern used in the first embodiment of the present invention. 3 is a flowchart showing a flow of generating print data for the first print head in the first embodiment of the present invention. 3 is a flowchart illustrating a recording data generation flow for a second recording head according to the first embodiment of the present invention. It is a schematic diagram which shows the random mask pattern used for the 2nd Embodiment of this invention. It is the table | surface which showed the list of the result of having evaluated the effect in the 1st, 2nd embodiment in this invention.

Explanation of symbols

401, 402 Recording head 403 Carriage 404 Paper feed roller 405 Auxiliary roller 406 Paper feed roller 407 Recording medium 300 Host computer 301 Input / output interface 302 CPU
303 ROM
304 RAM
305 Motor driver 307 Head driver

Claims (11)

  The recording heads having recording element array groups corresponding to the respective ink colors used for recording are configured in two sets, and the respective recording heads are stacked in the same order regardless of the forward scanning and backward scanning of each recording head. An ink jet recording apparatus using two sets of recording heads in which element array groups are arranged symmetrically in the main scanning direction, wherein the recording ratio setting area of each recording element array in each head is divided into a plurality of parts. Recording ratio setting means for setting a different recording ratio for each area, and the recording ratio setting means includes a recording ratio distribution in the recording element array direction of the first recording head, and a recording element of the second recording head. An ink jet recording apparatus, wherein the recording ratio is set to a distribution different from the recording ratio distribution in the column direction.   The recording ratio distribution in the recording element array direction of the first recording head and the recording ratio distribution in the recording element array direction of the second recording head differ in the recording ratio distribution in the recording element array direction of each recording head for each scan. 2. An ink jet recording apparatus according to claim 1, further comprising recording ratio setting changing means for switching and setting to a plurality of recording ratio distributions.   The recording ratio setting changing means sets the recording ratio distribution in the recording element array direction of the first recording head and the recording ratio distribution in the recording element array direction of the second recording head by switching for each scanning. The ink jet recording apparatus according to claim 1 or 2.   The recording ratio setting means includes a recording ratio distribution in a recording element array direction of the first recording head and a recording element array of the second recording head in an area having a high recording ratio in the recording ratio setting area of the recording element array group. 4. The ink jet recording apparatus according to claim 1, wherein different regions are set depending on the recording ratio distribution in the direction.   The recording ratio setting means is located inside the recording ratios for the divided areas located at both ends of the recording ratio setting area in the recording element array direction of the first recording head and the second recording head. The ink jet recording apparatus according to claim 1, wherein the ink recording apparatus is set to a value smaller than a recording ratio with respect to the divided area.   The recording heads having recording element array groups corresponding to the respective ink colors used for recording are configured in two sets, and the respective recording heads are stacked in the same order regardless of the forward scanning and backward scanning of each recording head. An ink jet recording apparatus using two sets of recording heads in which element array groups are arranged symmetrically in the main scanning direction, wherein a plurality of recording ratio setting areas of the recording element arrays in the same scanning recording area of both heads are provided. A mask pattern setting unit configured to divide and set the recording ratio determined by the mask pattern to be a different value for each of the divided areas, and the mask pattern setting unit includes a recording element array direction of the first recording head The first mask pattern for setting the recording ratio distribution in the second and the second mask pattern for setting the recording ratio distribution in the second recording element array direction An ink jet recording apparatus characterized by setting the recording ratios of different distributions.   A mask pattern for setting a mask pattern for setting the recording ratio distribution of the first recording head and a mask pattern for setting the recording ratio distribution of the second recording head by switching to a plurality of different mask patterns for each scanning. 7. An ink jet recording apparatus according to claim 6, further comprising setting changing means.   The mask pattern setting changing unit records a first mask pattern for setting a recording ratio distribution in the recording element arrangement direction of the first recording head and a distribution different from the first recording ratio distribution on the second recording head. 8. An ink jet recording apparatus according to claim 6, further comprising a replacement means for alternately using the second mask pattern for setting the ratio every scanning.   The mask pattern setting means sets a region set to a high recording duty among the divided regions in the same scanning recording region to a region different between the first mask pattern and the second mask pattern. The ink jet recording apparatus according to claim 6, wherein:   The mask pattern setting means sets the recording duty of the divided areas located at both ends of the divided areas in the same scanning recording area to a value smaller than the recording duty of the divided areas located inside thereof. 10. An ink jet recording apparatus according to claim 6,   7. The ink jet recording apparatus according to claim 1, wherein the recording head generates bubbles in the ink by heat energy and discharges ink by the energy generated by the bubbles.

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