JP5972037B2 - Inkjet recording apparatus and inkjet recording method - Google Patents

Description

  The present invention relates to an ink jet recording apparatus and an ink jet recording method, and particularly to a recording technique suitable for recording a high-definition image using a recording head that discharges a small amount of ink from a recording element having a high integration density. is there.

  In an ink jet recording apparatus, in order to achieve higher resolution of recorded images and higher recording speed, the amount of ink ejected from the recording head is reduced, the ink ejection frequency is improved, and a large number of recording elements are provided. A technique for stacking and arranging higher density is required. The ink ejection frequency corresponds to the drive frequency of the recording element. In recent years, in addition to the basic four colors of cyan, magenta, yellow, and black, a technology that simultaneously uses low density inks such as light cyan, light magenta, and gray has been developed. Already provided. Using a lot of low-density ink enriches gradation expression and contributes to improvement of robustness against noise such as deviation of landing positions of ink droplets on a recording medium. By using such a technique together, in recent inkjet recording apparatuses, high-resolution and high-gradation images can be recorded at high speed, and high-quality images approaching those of silver halide photography can be output.

  On the other hand, when the ink ejection frequency is increased using a recording head having a high integration density of recording elements and capable of ejecting a small amount of ink, there is a possibility that a phenomenon referred to as “end-to-end” may occur.

  FIG. 1 is a schematic view for explaining “end-to-end”. In the recording head H, a plurality of (for example, 768) recording elements are arranged along the left-right direction in FIG. The recording element includes an ink discharge port and a discharge energy generating element that generates energy for discharging ink from the discharge port. From such recording elements of the recording head H, ink droplets are ejected toward a recording medium (not shown) positioned below in FIG. As shown in FIG. 1, the ink droplets ejected from the recording elements located in the vicinity of both ends of the recording element array in the left-right direction in FIG. 1 are curved so that their flight paths are directed toward the center of the recording element array. “End-to-end” refers to a phenomenon in which the flight path of ink droplets ejected from recording elements located in the vicinity of both ends of the recording element array is curved. Such “end-to-end” is considered to occur by the following principle. The air around the ink droplet ejected from the recording element moves in the same direction as the ink droplet, thereby forming a region in which the pressure is reduced. On the other hand, the left and right side regions in FIG. 1 that deviate from the position facing the recording head H are not depressurized, so the air in the both side regions becomes an airflow that moves toward the depressurized region as indicated by arrow A. . Due to the air flow, as shown in FIG. 1, the flight path of the ink droplets ejected from the recording elements located near both ends of the recording element array is curved. It has been confirmed that such a phenomenon of “end-of-edge” appears remarkably when the drive frequency of a large number of recording elements arranged at high density is high.

  In such a situation in which “end-to-end” occurs, the ink droplets ejected from both ends of the printing element array are not landed on the normal position of the printing medium. Therefore, in a serial scan method in which an image is recorded by repeatedly scanning the recording head and transporting the recording medium, a white streak-shaped portion having a low recording density is formed at a connecting portion of images recorded by scanning before and after the recording head. (White lines) may occur. Also, if the volume of ink droplets ejected from the recording head is increased to make it less susceptible to airflow in order to suppress the occurrence of “edge wobbling”, the ink dots formed on the recording medium become larger. As a result, the graininess of the recorded image becomes noticeable. Therefore, it becomes difficult to record a smooth high-quality image like a silver salt photograph.

  In Patent Document 1, as a countermeasure against such “end-to-end”, a mask pattern is used to lower the recording rate of a recording element positioned at the end of the recording element array and to position the recording element at the center of the recording element array. A method for increasing the recording rate of the recording element is described. Further, Patent Document 2 describes a method of using a mask pattern for measures against “end-to-end” only for a recording element array that is assumed to have a high recording duty or a recording element array that has a high recording duty. Yes. The mask pattern is a mask pattern for lowering the recording rate of the recording elements located at both ends of the recording element array.

JP 2002-96455 A JP 2005-246877 A

  It has been found that the airflow generated by the movement of the recording head and the ink ejection operation by the recording elements in the recording element array affects the recording elements in the recording element array adjacent to the recording element array. As a result of diligent examination using the inventors' simulation tools and the like, when the print duty of two print element arrays adjacent to each other is different, the landing position of the ink droplet ejected from the print element array with the lower print duty is It was found that the recording head shifted in the moving direction.

  FIGS. 2A and 2B are diagrams when recording scanning is performed in the left-right direction in FIG. 2 while ejecting ink droplets from two adjacent recording element arrays L1 and L2 in the recording head H at different recording duties. 3 is a model diagram showing an air flow between a recording head H and a recording medium P. FIG. The recording element rows L1 and L2 in which a plurality of recording elements are arranged extend in the front and back direction of the paper surface in FIGS. 2 (a) and 2 (b), respectively. At the time of the recording scan to the right as shown in FIG. 2A, the recording element row L1 having a high recording duty is located in the front in the scanning direction, and the recording element row L2 having a low recording duty is located in the rear in the scanning direction. . On the other hand, at the time of the recording scan to the left as shown in FIG. 2B, the recording element row L2 with a low recording duty is positioned in front of the scanning direction, and the recording element row L1 with a high recording duty is behind in the scanning direction. To position. In the case of FIG. 2 (a), an airflow A1 directed backward in the scanning direction while being wound up from the recording medium P in the direction of the recording head H can be confirmed immediately below the recording element array l2 having a low recording duty. On the other hand, in the case of FIG. 2B, an airflow A2 directed forward in the scanning direction while being blown down from the recording head H to the recording medium P can be confirmed immediately below the recording element array L2 having a low recording duty. Since the airflow A2 is closer to the velocity vector of the ink droplets ejected from the recording element array L2 than the airflow A1, the landing of the ink droplets ejected from the recording element array L2 is more susceptible to the airflow A2. . Accordingly, in the case of FIG. 2B, the landing positions of the ink droplets ejected from the recording element array L2 are likely to be shifted backward in the scanning direction, that is, toward the recording element array L1 having a high recording duty.

  As described above, the difference in recording duty between the adjacent recording element arrays L1 and L2 affects the landing position of the ink droplets ejected from these recording element arrays. In particular, as shown in FIG. 2B, when the recording element row L2 having a low recording duty is positioned in front of the scanning direction, the ink droplets ejected from the recording element row L2 are attracted to the rear side in the scanning direction. This may cause the landing position to shift. In particular, in a multi-pass printing method, when a gradation mask that changes the recording rate in the direction of the printing element array is used, the recording rate at the center of the printing element array becomes high, so that the discharge from the center is performed. The influence of the airflow generated by the ink that is applied tends to increase. Specifically, the deviation of the landing positions of the ink droplets ejected from the central part of the adjacent recording element arrays is likely to increase due to the air flow. By using the gradation mask, it is possible to suppress the occurrence of white streaks in the multi-pass printing method, but on the other hand, the influence of the deviation of the landing position of the ink droplets ejected from the central portion of the printing element array on the printed image becomes large. Further, when no other recording element array is provided for ejecting ink of the same color as the ink ejected from the recording element array having a low recording duty, the deviation of the landing position of the ink affects the recorded image. The impact will be greater. The same applies to the case where there is no other recording element array that ejects different amounts of ink ejected from the recording element array having a low recording duty.

  Further, in order to suppress the influence of the airflow as described above, when the distance between the adjacent recording element arrays is increased, the recording head and the ink jet recording apparatus are increased in size, contrary to the increase in the density of the recording elements. There is a risk that

  An object of the present invention is to provide an ink jet recording apparatus and an ink jet recording method capable of recording a high-definition image while suppressing the influence of an air flow between adjacent recording element arrays in a multi-pass recording method. .

The inkjet recording apparatus of the present invention includes a first ejection port array in which a plurality of ejection ports for ejecting a first color ink are arranged in a predetermined direction, and a second color ink different from the first color. a second ejection outlet array in which a plurality of discharge ports are arranged in the predetermined direction for ejecting said a second color and similar colors, a third color is a color that the second color and different concentrations A plurality of ejection port arrays for ejecting ink of a plurality of colors including at least a third ejection port array in which a plurality of ejection ports for ejecting ink are arranged in the predetermined direction are the first ejection ports. A recording head arranged in the intersecting direction so that the array and the second ejection port array are adjacent to each other in the intersecting direction intersecting the predetermined direction; and the recording head with respect to a unit area on the recording medium Scanning means for scanning in the intersecting direction a plurality of times, and an image to be recorded in the unit area A plurality of mask patterns for determining a recording rate at each position of each of the plurality of ejection port arrays; and a first acquisition unit that acquires image data corresponding to the image data; the image data acquired by the first acquisition unit; And generating means for generating recording data used for ejecting ink to the unit area in each of the plurality of scans by the scanning means, and the recording head being scanned by the scanning means Control means for controlling the ink to be ejected based on the recording data generated by the generating means, wherein the first ejection ports are arranged in the plurality of ejection port arrays. There is no ejection port array that ejects ink of the same color as the first color other than the ejection port array, and the generation unit includes (i) the first acquisition unit. The first color ink corresponding to the first color ink based on the image data corresponding to the first color ink and the first mask pattern of the plurality of mask patterns. It generates recording data, (ii) and the image data corresponding to the ink of said acquired by the first acquisition means second color, of the plurality of mask patterns, the predetermined said discharge port array direction of the difference between the recording rate in the recording rate and the central portion of the end portion is rather smaller than the first mask pattern, and the predetermined direction wherein the recording rate at the central portion of the first mask pattern of the discharge port array a low There second mask patterns than, based on, and generates the recording data corresponding to the ink of the second color.

  According to the present invention, recording is performed according to at least one of the type of ink ejected from the recording element array and the recording duty, and the type of ink ejected from the recording element array adjacent to the recording element array. Different mask patterns are used to thin out data. Thereby, the influence of the airflow between the recording element arrays adjacent to each other can be suppressed, and a high-definition image can be recorded more.

FIG. 10 is a schematic diagram for explaining the phenomenon of “edge shift” in which the ink ejection direction changes. (A) And (b) is explanatory drawing of the airflow produced when the printing duty of two adjacent printing element rows differs at the time of the printing scan in one direction and another direction, respectively. FIG. 2 is a block diagram for explaining a configuration of a control system of the ink jet recording apparatus according to the first embodiment of the present invention. FIG. 3 is a perspective view of a recording head used in the first embodiment of the present invention. FIG. 5 is a configuration diagram of a recording element array in the recording head of FIG. 4. It is a block diagram for demonstrating the recording system comprised in the 1st Embodiment of this invention. It is a block diagram for demonstrating the structure of the mask control part in FIG. (A) And (b) is explanatory drawing of the distribution of the recording rate by the mask patterns A and B respectively used in the 1st Embodiment of this invention. It is a flowchart for demonstrating the determination process of the mask pattern in the 2nd Embodiment of this invention. It is a block diagram which shows roughly a process process to the recording data in the 2nd Embodiment of this invention. It is a block diagram for demonstrating the structure of the mask control part in FIG. It is explanatory drawing of the average recording duty for every several printing element row | line | column in the 2nd Embodiment of this invention. It is a block diagram of the ink discharge port in the recording head used in the 3rd Embodiment of this invention. It is a flowchart for demonstrating the determination process of the mask pattern in the 3rd Embodiment of this invention. (A) and (b) show the amount of deviation of the landing position of the main droplet of ink that occurs when the mask patterns applied to two adjacent printing element arrays are not different during forward scanning and backward scanning, respectively. It is explanatory drawing. FIG. 7 is an explanatory diagram of a deviation amount of an ink satellite landing position that occurs when a mask pattern applied to two adjacent printing element arrays is not changed during forward scanning. (A) and (b) are explanations of the amount of deviation of the landing position of the main droplet of ink that occurs when the mask patterns applied to two adjacent printing element arrays are different during forward scanning and backward scanning, respectively. FIG. FIG. 7 is an explanatory diagram of a deviation amount of an ink satellite landing position that occurs when different mask patterns are applied to two adjacent printing element arrays during forward scanning. 1 is a perspective view of a main part of an ink jet recording apparatus to which the present invention is applicable.

(First embodiment)
FIG. 19 is a perspective view for explaining a configuration example of the ink jet recording apparatus 30 applied to the first embodiment.

  The recording head 20 capable of ejecting ink is detachably mounted on a carriage 31 movable in the main scanning direction indicated by an arrow X, and the recording medium P intersects the main scanning direction by two transport roller pairs 33 and 34 ( In the case of this example, the sheet is conveyed in the sub-scanning direction of an arrow Y that is orthogonal. The carriage 31 is guided so as to be movable in the main scanning direction by a guide shaft 34 and the like, and is reciprocated in the main scanning direction by a moving mechanism constituted by a carriage motor, a belt and the like which will be described later.

  FIG. 3 is a block diagram for explaining the configuration of the control system of the recording apparatus 30 of FIG. The CPU 2 controls the operation of the entire recording apparatus including the recording operation in accordance with an input signal (including an image signal) from the external host device 1 connected via the interface 6. A processing program executed by the CPU 2 is stored in the ROM 3, and the RAM 4 is used as a work area for temporarily storing an image signal being processed. The recording head 20 is driven by the recording head driver 5, and the carriage motor 8 for moving the carriage 31 is driven by the motor driver 7. The motor driver 9 drives a conveyance motor 10 for operating the conveyance roller pairs 33 and 34, and the motor driver 11 drives a paper feed motor 12 for feeding the recording medium P.

  FIG. 4 is a schematic perspective view of the recording head 20. Two recording element substrates 21 (21A, 21B) on which a plurality of recording elements are formed are provided on a support base 22, and these recording elements form a recording element array as will be described later. Multiple sequences are arranged. The recording element ejects ink supplied from an ink supply unit (not shown) as ink droplets in the Z direction based on the drive signal. The recording element includes an ink ejection port and an ejection energy generation element for ejecting the ink supplied from the ink supply unit from the ejection port, and when a drive pulse is applied to the ejection energy generation element, Ink is ejected from the ejection port. As the discharge energy generating element, an electrothermal conversion element (heater), a piezoelectric element, or the like can be used. When the electrothermal conversion element is used, the ink is foamed by the heat generation, and the ink can be ejected from the ejection port using the foaming energy. A drive signal for generating a drive pulse is input to the recording element substrate 21 via the contact terminal substrate 23, the sheet wiring substrate 24, and the like.

  FIG. 5 is an explanatory diagram of a plurality of recording element arrays provided in the recording head 20. On the recording element substrate 21A, recording element arrays for ejecting four types of inks of light cyan (LC), magenta (M), yellow (Ye), and light magenta (LM) intersect the main scanning direction (this example). In this case, it is formed so as to extend in an orthogonal direction. On the other hand, on the recording element substrate 21B, recording element arrays for ejecting four types of ink of cyan (C), black (Bk), light gray (LGy), and gray (Gy) intersect the main scanning direction ( In the case of this example, it is formed so as to extend in a direction orthogonal to each other.

  In FIG. 3, the CPU 2 controls the recording head driver 5 based on the image signal input from the host device 1 and ejects ink from the recording elements of the recording head 20. At the same time, the carriage motor driver 7 is controlled to drive the carriage motor 8 to move the carriage 31 together with the recording head 20 in the main scanning direction. As described above, the ink for one recording scan is recorded on the recording medium P by ejecting ink from the recording head 20 while moving the recording head 20. Images are sequentially recorded on the recording medium P by alternately performing such a single recording scan and a predetermined amount of conveyance of the recording medium P by the driving force of the conveyance motor 10.

  FIG. 6 is an explanatory diagram of a recording system including the host device 1 and the recording device 30. The host device 1 includes an application 41 and a printer driver 42. The application 41 performs recording control of the recording apparatus 30, control of the transport mechanism of the recording medium P, movement control of the carriage 31, and the like via the printer driver 42 based on the input information.

  In the printer driver 42, the color correction unit 43 performs color correction on the image signal input from the application 41 according to the image characteristics to be output, and converts the image signal into a different signal. The color conversion unit 44 converts the input RGB signal into a signal corresponding to the ink color used by the recording apparatus 30 to output. In this example, a total of eight colors of cyan (C), magenta (M), yellow (Ye), black (Bk), light cyan (LC), light magenta (LM), gray (Gy), and light gray (LGy). Can be used. The halftoning unit 45 performs pseudo halftone processing (halftoning processing) such as error diffusion on the input multilevel signal for each ink color, and the recording device 30 performs a recording operation on the multilevel signal. The number of gradations to be realized, that is, a binary signal per 1 bit is converted.

  The recording mode control unit 46 in the printer driver 42 sets each parameter used in the color correction unit 43, the color conversion unit 44, and the halftoning unit 45 according to the designation contents of the recording medium and recording quality on the user interface of the printer driver 42. . Further, the recording mode control unit 46 transfers the recording mode information to the recording device 30 as a control command.

  The print buffer 47 provided in the printing apparatus 30 receives binary print data that has been halftoned by the printer driver 42, and print data for one scan corresponds to each print element in the print head 20. It is transferred to the mask controller 50. As will be described later, the mask control unit 50 selects an appropriate pattern from a plurality of mask (gradation mask) patterns prepared for multi-pass printing based on printing mode information transferred from the printer driver 42. Choose one. Then, using the selected mask pattern, mask processing is performed on the input binary recording data. The binary print data thinned out by the mask process is transferred to the print head driver 5 and converted into an electrical signal for driving each print element of the print head 20. The electrical signal generated by the recording head driver 5 is transferred to each recording element of the recording head 20 at a predetermined timing, whereby each recording element ejects ink according to the electrical signal. In this way, the recording head 20 ejects ink based on the recording data thinned out for each scanning by the mask process in the multi-pass method in which the unit recording area on the recording medium is scanned a plurality of times.

  Such a recording system including the host device 1 and the recording device 30 may constitute one recording device, and at least a part of the mask control unit 50 may be provided on the host device 1 side. .

  FIG. 7 is a block diagram showing the mask control unit 50 in more detail. The first selector 51 determines whether the recording quality, which is one of the recording mode information transferred from the printer driver 42, is “clean” or “standard”, that is, whether it is “clean mode”. The recording data is divided according to whether it is the “standard mode”. In the “clean mode”, binary print data corresponding to ink for all eight colors is transferred to the first mask controller 52. On the other hand, in the “standard mode”, the second selector 53 divides the print data according to the ink attributes. In the “standard mode”, the number of passes in the multi-pass printing method is smaller than in the “clean mode”, and the printing duty per printing scan (one pass) is high. It is assumed that is likely to occur. Accordingly, determining whether the recording mode is “clean mode” or “standard mode” indirectly determines the recording duty.

  In the “standard mode”, the recording data for each ink color is divided according to the attribute of the ink. The attribute of the ink is an attribute indicating whether or not the ink is the dominant color, and binary corresponding to the dominant colors of cyan (C), magenta (M), yellow (Ye), and black (Bk). Is transferred to the first mask control unit 52. Recording data corresponding to four colors of light cyan (LC), light magenta (LM), gray (Gy), and light gray (LGy), which are not dominant colors, is stored in the third selector 54 as information on adjacent printing element arrays. Divided based on.

  The third selector 54 selects four colors that are not dominant colors depending on whether dark ink or light ink of the same color as the ink ejected from the adjacent printing element array is in the ink used in the printing apparatus. Separate the recording data corresponding to the ink. Hereinafter, recording element arrays corresponding to four colors of ink that are not dominant colors are also referred to as “main recording element arrays”, and recording element arrays adjacent thereto are also referred to as “adjacent recording element arrays”. When the ink used in the recording apparatus includes dark ink or light ink having the same color as the ink ejected from the adjacent recording element array, the binary recording data corresponding to the recording element array is the first mask. It is transferred to the control unit 52. On the other hand, when there is no dark ink or light ink having the same color as the ink ejected from the adjacent recording element array in the ink used in the recording apparatus, the binary recording data corresponding to this recording element array is 2 is transferred to the mask controller 55.

  In the case of this example, the yellow (Ye) ink is the only ink that does not use dark or light inks of similar colors. Also, as shown in FIG. 5, among the recording element arrays that eject four colors of ink that are not the dominant colors, the recording element array adjacent to the recording element array that ejects yellow (Ye) ink is light magenta (LM). ). Eventually, only binary recording data corresponding to light magenta (LM) is transferred to the second mask controller 55.

  The first mask control unit 52 stores a first mask pattern (mask pattern A), and the second mask control unit 55 stores a second mask pattern (mask pattern B). The first and second mask control units 52 and 55 mask the print data using the respective mask patterns, and transfer the print data after the mask process to the print head driver 5. Binary print data corresponding to the dominant colors cyan (C), magenta (M), yellow (Ye), and black (Bk) ink is masked using the mask pattern A. Binary print data corresponding to light cyan (LC), gray (Gy), and light gray (LGy) inks that are not dominant colors are masked using the mask pattern A. The recording data corresponding to light magenta (LM) ink that is not the dominant color is masked using the mask pattern B.

  FIG. 8 is an explanatory diagram of two mask patterns A and B for 4-pass multi-pass printing used in this example. In the mask pattern A, the recording rate by the recording element located at the end of the printing element array is about 10%, and the recording rate by the recording element located at the center is 40%. On the other hand, in the mask pattern B, the recording rate by the recording element located at the end of the printing element array is about 15%, and the recording rate by the recording element located at the center is 35%. With respect to the recording rate of the recording element located at the end of the recording element array, when the value in the mask pattern A is a predetermined value, the mask pattern B has a value larger than the predetermined value. In this specification, the “recording rate” is the ratio of the number of dots allowed for printing determined by the mask pattern. Specifically, printing is allowed for the total number of dots corresponding to the area of the mask pattern. This is the ratio of the number of dots to be recorded (number of printable dots). Further, the recording element and the recording rate may have a 1: 1 relationship or a plurality of 1: 1 relationship.

  Like the mask pattern A, the mask pattern B has a low recording rate at the end of the printing element array and a high recording rate at the center, but the mask pattern A does not have a large difference in recording rate. A mask pattern having a large difference in recording rate, such as the mask pattern A, reduces the recording rate at the end of the recording element array, and thus suppresses “end-to-end” due to the air current as described above. However, since the recording duty at the central portion of the recording element array is high, the influence of the airflow on the recording element array adjacent to the recording element array is increased.

  Here, a description will be given of the relationship between the print duty difference between the print element arrays adjacent to each other and the landing position deviation of the ink in the main scanning direction of the print element arrays. The following landing position deviation data is obtained by a simulation tool.

  Of the recording element arrays adjacent to each other in the recording head of FIG. 5, the recording duty of the light magenta (LM) recording element array is 50%, and the yellow (Ye) recording element array is 42.5%. Assume that multi-pass recording is performed. Here, it is assumed that the recording data of these recording element arrays are all masked using the mask pattern A (the end portion 10%, the central portion 40%) in FIG. The recording duty per scan at the center of the light magenta (LM) recording element array (hereinafter also referred to as “recording element array LM”) is (50/4) × (40/25) = 20%. On the other hand, the recording duty per scan at the center of the yellow (Ye) printing element array (hereinafter also referred to as “recording element array Ye”) is (12.5 / 4) × (40/25) = 5%. It becomes. In these equations, (40/25) means the ratio of the central recording rate (40%) to the average recording rate (25%) in the 4-pass recording method. When the reciprocating scanning is performed under such a recording duty difference condition, the landing position deviation in the scanning direction of the ink droplets ejected from the yellow (Ye) recording element array is shown in FIGS. It occurred as follows. The vertical axis in these figures is a numerical value of the amount of deviation (deviation amount) of the landing position when the scanning direction of the recording head is positive.

  FIGS. 15A and 15B show yellow (Ye) ink droplets (main droplets) ejected from the recording element array Ye when the recording head is moved forward and backward in the direction of the arrow X1 and X2, respectively. ) Shows landing position deviation. At the time of forward scanning, as shown in FIG. 15A, the landing position of yellow (Ye) ink droplets ejected from the central portion of the recording element array Ye is in the direction opposite to the scanning direction, that is, in the recording element array LM. The direction shifted by about 3 μm. On the other hand, during backward scanning, as shown in FIG. 15B, there is no specific deviation in the landing positions of yellow (Ye) ink droplets ejected from the entire area of the printing element array Ye. FIG. 16 shows the landing position deviation of a small droplet (satellite) of yellow (Ye) ink ejected from the printing element array Ye during forward scanning. A satellite is a small droplet of ink ejected after an ink droplet (main droplet), and landed after the ink droplet. The satellite is slow in discharge speed and small in mass, and thus is easily affected by air current, and the displacement of its landing position reaches nearly 10 μm.

  From these data, the relationship between the scanning direction described with reference to FIGS. 2A and 2B and the deviation of the landing position of the ink droplet was proved. That is, as shown in FIG. 2B, when a printing element row (printing element row Ye) with a low printing duty is positioned in front of the scanning direction, ink droplets ejected from the printing element row have a high printing duty. It has been proved that it is attracted to the recording element array LM side (rear side in the scanning direction).

  In the present embodiment, in order to suppress the deviation of the landing position of yellow (Ye) ink droplets, the mask pattern applied to the recording data of the recording element array LM is the mask pattern B (end portion 15) of FIG. %, Central part 35%). When the printing duty of the printing element array LM is 50% and 4-pass multipass printing is executed, the printing duty per scan at the center of the printing element array LM is (50/4) × (35 /25)=17.5%. As a result, the difference between the recording duty (17.5%) at the center of the recording element array LM and the recording duty (5%) at the center of the recording element array Ye is reduced. As a result, the displacement of the landing positions of the yellow (Ye) ink droplets ejected from the recording element array Ye can be suppressed as small as shown in FIGS.

  FIG. 17A shows the deviation of the landing positions of yellow (Ye) ink droplets when the recording head is scanned in the forward direction of the arrow X1. As in the case of FIG. 15A, although the ink droplets ejected from the central portion of the recording element array Ye are displaced in the direction of the recording element array LM, the displacement amount is about 1 μm, and FIG. It is halved compared with the case of a). On the other hand, when the recording head is scanned in the backward direction of the arrow X2, as shown in FIG. 17B, no specific landing position deviation appears across the entire area of the recording element array Ye. FIG. 18 shows the deviation of the landing position of the yellow (Ye) satellite when the recording head is scanned in the forward direction, and the landing position deviation is suppressed to less than 5 μm.

  In the present embodiment, the dominant colors cyan (C), magenta (M), yellow (Ye), and black (Bk) inks are likely to be affected by the “edge shift” in the image. A mask pattern A having a large difference in recording rate is applied to the recording data. For each of the other four color inks other than the dominant color, depending on whether or not the recording element array that discharges dark ink or light ink of the same color system as the ink discharged from the other recording element array is adjacent, Mask pattern A or mask pattern B is applied. Regarding yellow (Ye) ink, there is no dark ink and light ink of the same color system. For this reason, yellow (Ye) ink is easily affected by ink ejected from adjacent recording element arrays, and when the landing position is shifted in the scanning direction, there is no ink of a similar color that complements the landing position. The effect on the final recorded image is increased. Therefore, in the present embodiment, as described above, the mask pattern B is applied to the printing element row LM adjacent to the printing element row Ye that ejects yellow (Ye) ink. As a result, the recording rate of the central portion of the recording element array LM is reduced, the influence of the recording element array LM on the yellow (Ye) ink is reduced, and the landing position shift of the yellow (Ye) ink is reduced. Make it difficult to occur. In this case, the risk of “swinging edge” with respect to light magenta (LM) ink increases. However, it was confirmed that the influence on the final recorded image can be reduced by applying the mask pattern A to the recording element array that ejects magenta (M) ink of the same color as that.

  In this way, by selectively using a gradation mask whose recording rate changes in the direction of the recording element array, it is possible to prevent ink droplets ejected from the center of the recording element array while preventing the occurrence of white streaks in the recorded image. The deviation of the landing position can be kept small. As a result, a high-definition image can be recorded using a recording head that discharges a small amount of ink droplets from a recording element having a high integration density.

(Second Embodiment)
Next, a second embodiment of the present invention will be described.
FIG. 9 is a flowchart for explaining a mask pattern determination process applied to each printing element array. When this process is started, first, a predetermined amount of recording data is input in step S1. In the next step S2, it is determined whether or not recording data for one page has been input. If one page of recording data has not been input, the process returns to step S1, and at that time, the recording duty for each ink color is counted based on the input recording data, and the recording duty is set to Dn (n = 0 to 7). ). Such steps S1, S2, and S3 are repeated until one page of recording data is input.

  If it is determined in step S2 that one page of recording data has been input, the process proceeds to step S4, and the variable n is set to zero. In the present embodiment, the variable n is an identification number (hereinafter also referred to as “color number”) prepared for each type of ink color. In this example, n is an integer of 0 to 7. In step S5, it is determined whether the color number n is smaller than 7. Thereby, it is determined whether or not the processing for all the recording data of the ink for eight colors is completed. When the processing is completed, this processing is terminated.

On the other hand, if it is determined in step S5 that n <7, the process proceeds to step S6, and it is determined whether or not the value of the recording duty Dn corresponding to the color number n is greater than or equal to a predetermined threshold Th. Than the recording duty Dn is the threshold Th, that is, when it is judged less than the predetermined value, it is determined that the influence of air current applied to the adjacent recording element array is small, the process proceeds to step S9. In this step S9, as a mask pattern to be applied, the recording rate of the recording element located at the end of the printing element array is set to 20%, and the recording rate of the recording element located at the center is set to 80%. The mask pattern A in (a) is selected.

When the recording duty Dn is not less than the threshold value Th (Dn ≧ Th), that is, not less than the predetermined value, the process proceeds to step S7. In step S7, it is determined whether or not the ink used in the printing apparatus includes dark ink or light ink having the same color as the ink ejected from the adjacent printing element array. Hereinafter, a recording element array in which the recording duty Dn is equal to or greater than the threshold Th (Dn ≧ Th) is also referred to as “main recording element array”, and a recording element array adjacent thereto is also referred to as “adjacent recording element array”. If there is no dark ink or light ink of the same color system as the ink ejected from the adjacent recording element array in the ink used in the recording apparatus, when the adjacent recording element array is affected by the air current, the final recorded image is obtained. Is determined to have a large influence, the process proceeds to step S8. In step S8, as a mask pattern to be applied to the recording element array, the recording rate of the recording element positioned at the end of the recording element array is 30%, and the recording rate of the recording element positioned at the center is 70%. The set mask pattern B in FIG. 8B is selected.

  On the other hand, when the ink used in the recording apparatus includes dark ink or light ink of the same color as the ink ejected from the adjacent recording element array, the final recording is performed even if the adjacent recording element array is affected by the air current. It is determined that the effect on the actual recorded image is slight, and the process proceeds to step S9. In step S9, the mask pattern A shown in FIG. 8A is selected as a mask pattern to be applied to the printing element array.

  After selecting the mask pattern to be applied to the print data of the ink of color number n, the color number n is incremented in step S10, and then the process returns to step S5 to select the mask pattern to be applied to the print data of the next color number of ink. To do. This processing is completed by performing the above processing for all eight colors of ink.

  FIG. 10 is a block diagram schematically showing recording data processing steps in the present embodiment. Portions similar to those in the configuration of FIG. 6 described above are denoted by the same reference numerals and description thereof is omitted. A recording duty detection unit 48 counts the recording duty (Dn) for each ink color with respect to the recording data input to the print buffer 47. The processing corresponds to the processing from S1 to S3 in FIG. The recording duty (Dn) detected by the recording duty detector 48 is transferred to the mask controller 50 as information for selecting a mask pattern as described above.

  FIG. 11 is a block diagram for explaining the processing contents of the mask control unit 50 in the present embodiment. The first selector 61 divides the recording data for each printing element array depending on whether the recording duty Dn for each printing element array is equal to or greater than the threshold Th. The recording data of the recording element array with Dn <Th is transferred to the first mask control unit 52. The recording data of the recording element array with Dn ≧ Th is divided by the second selector 62. That is, the second selector 62 determines whether the ink used in the recording apparatus includes dark ink or light ink having the same color as the ink ejected from the adjacent recording element array. When the ink used in the recording apparatus includes dark ink or light ink having the same color as the ink ejected from the adjacent recording element array, the recording data of the recording element array is transferred to the first mask control unit 52. Is done. On the other hand, if there is not, the recording data of this recording element array is transferred to the second mask controller 55.

  FIG. 12 is an explanatory diagram of an example of the relationship between the recording duty Dn and the threshold Th for each printing element array. In the case of this example, the recording duty Dn corresponding to the three color inks of light cyan (LC), light magenta (LM), and gray (Gy) exceeds the threshold Th. Therefore, the mask pattern A shown in FIG. 8A is applied to print data of a print element array that ejects ink other than these.

  When the recording element array for light cyan (LC) is the main recording element array, the ink ejected by the adjacent recording element array adjacent thereto is magenta (M) ink. Among the inks used in the recording apparatus, there is light magenta (LM) of the same color as the magenta (M). Therefore, for the recording data of the recording element array for light cyan (LC), FIG. ) Mask pattern A is applied. Further, when the gray (Gy) recording element array is the main recording element array, the ink ejected by the adjacent recording element array adjacent thereto is light gray (LG) ink. Among the inks used in the printing apparatus, there is black (Bk) of the same color as the light gray (LG). Therefore, for the print data of the gray (Gy) print element array, FIG. ) Mask pattern A is applied. In this case, it may be determined that the ink used in the printing apparatus (including the ink ejected from the printing element array) includes a gray (Gy) similar in color to the light gray (LG). Further, when the light magenta (LM) recording element array is the main recording element array, the inks ejected by the adjacent recording element arrays adjacent thereto are yellow (Ye) and cyan (C) inks. Among the inks used in the recording apparatus, although there is light cyan (LC) similar in color to cyan (C), there is no ink similar in color to yellow (Ye). Therefore, the mask pattern B in FIG. 8B is applied to the recording data of the light magenta (LM) recording element array.

  Eventually, in the case of this example, the mask pattern B is applied only to the light magenta (LM) printing element array, and the mask pattern A is applied to the other seven printing element arrays. .

(Third embodiment)
FIG. 13 is an explanatory diagram of a printing element array (also referred to as “nozzle array”) in the recording head used in the present embodiment.

  In the case of this example, a printing element array for ejecting yellow (Ye), magenta (M), cyan (C), and black (Bk) ink is formed. The recording element that ejects black (Bk) ink ejects large ink droplets from a relatively large ejection port 71, and forms recording element arrays (large nozzle arrays) Bk-L1 and Bk-L2. A plurality of lines are arranged at a predetermined pitch P. The recording elements in the recording element array Bk-L1 and the recording elements in the recording element array Bk-L2 are shifted by a half pitch (P / 2). Similarly, a plurality of recording elements that discharge yellow (Ye) large ink droplets from a relatively large discharge port 72 are arranged so as to form recording element arrays Ye-L1 and Ye-L2 (large nozzle arrays). . Similarly, printing elements that discharge large ink droplets of cyan (C) and magenta (M) from relatively large discharge ports 73 and 75 are printing element rows C-L1 and C-L2 as large nozzle rows, respectively. A plurality of M-L1 and M-L2 (large nozzle rows) are arranged. However, the printing element arrays C-L1 and C-L2 are formed apart from each other in the main scanning direction, and the printing element arrays M-L1 and M-L2 are also formed apart from each other in the main scanning direction.

  Similarly, the recording elements that eject cyan (C) and magenta (M) small ink droplets from the relatively small ejection openings 74 are the recording element arrays C-S1, C-S2, and M-S1, M-S2 (small). A plurality of nozzle arrays). However, the printing element arrays C-S1 and C-S2 are formed apart from each other in the main scanning direction, and the recording element arrays M-S1 and MS-S2 are also formed apart from each other in the main scanning direction.

  The recording element arrays C-L1, C-S1, M-L1, and M-S1 and the recording element arrays C-L2, C-S2, M-L2, and M-S2 are the recording element arrays Ye-L1 and Ye-L2. They are arranged symmetrically on one side (arrow X1 direction side) and the other side (arrow X2 direction side). The black (K) and yellow (Y) printing element arrays Bk-L1, Bk-L2 and Ye-L1, Ye-L2 are all large nozzle arrays that eject large ink droplets. On the other hand, the recording element arrays for cyan (C) and magenta (M) include a large nozzle array and a small nozzle array that eject large ink droplets and small ink droplets, respectively, and these nozzle arrays are yellow (Y). Are arranged symmetrically with respect to the recording element array.

FIG. 14 is a flowchart for explaining a mask pattern determination process applied to each printing element array in the present embodiment. The same parts as those in the process of FIG. 9 described above are denoted by the same reference numerals, and the description thereof is omitted. Similarly to the above-described second embodiment, a recording element array whose recording duty Dn is equal to or greater than the threshold Th (Dn ≧ Th) is referred to as “main recording element array”, and a recording element array adjacent thereto is referred to as “adjacent recording element” It is also called “column”.

  Since a total of 13 recording element arrays are formed in the recording head as shown in FIG. 13, n is an integer from 0 to 11. In step S5A, it is determined whether the color number n is smaller than 11. Thus, it is determined whether or not the processing for all the recording data of the 13 recording element arrays has been completed, and when this processing is completed, this processing is terminated. In step S7A, it is determined whether or not the ink ejected from the adjacent recording element array is ink that should be ejected as large and small ink droplets. When the ink ejected by the adjacent recording element array is ink to be ejected as large and small ink droplets, the mask pattern A is selected as the mask pattern applied to the recording element array. On the other hand, if this is not the case, the mask pattern B is selected as the mask pattern applied to this printing element array.

  For example, when the printing duty of all printing element arrays corresponding to cyan (C) and magenta (M) inks does not exceed the threshold Th, three printing element arrays C-L1, M-S1, and M- The mask pattern A is applied to S2. This is because the ink ejected from the recording element arrays Bk-L2, Te-L1, and Ye-L2 adjacent to the recording element arrays is not ink that should be ejected as large and small ink droplets. Further, the mask pattern A is applied to recording element arrays other than the recording element arrays C-L1, M-S1, and M-S2.

(Other embodiments)
In the present invention, the mask pattern applied to the recording element array is such that when the recording element array is “main recording element array” and the adjacent recording element array is “adjacent recording element array”, those recording element arrays And selected according to the ink discharge conditions in the adjacent recording element array. That is, in the first embodiment, the mask pattern applied to the recording element array according to the recording mode, the type of ink ejected from the recording element array, and the type of ink ejected from the adjacent recording element array. Select. In the second and third embodiments, a mask pattern to be applied to the recording element array is selected according to the recording duty of the recording element array and the type of ink ejected from the adjacent recording element array.

  As described above, according to the present invention, at least one of the type of ink ejected from the recording element array and the recording duty of the recording element array, and the type of ink ejected from the adjacent recording element array, Different mask patterns are applied to this printing element array. The selection conditions for the mask pattern to be applied to the printing element array include various conditions such as the printing mode, the type of ink ejected from the printing element array and the adjacent printing element array, and the printing duty of the printing element array. Can be combined. The combination of these conditions is not specified only in the above-described embodiment.

  The present invention can be widely applied to the multi-pass recording method, and the number of passes is not limited to the above-described four passes.

2 CPU
20 recording head 50 mask control unit 51 first selector 52 first mask control unit 53 second selector 54 third selector 55 second mask control unit

Claims (9)

The first ejection port array in which a plurality of ejection ports that eject ink of the first color are arranged in a predetermined direction, and the plurality of ejection ports that eject ink of a second color different from the first color are A second ejection port array arranged in a predetermined direction and a plurality of ejection ports that eject ink of a third color that is the same color as the second color and has a density different from that of the second color A plurality of ejection port arrays for ejecting ink of a plurality of colors including at least a third ejection port array arranged in the predetermined direction, the first ejection port array and the second ejection port Recording heads arranged side by side in the intersecting direction so that the rows are adjacent to the intersecting direction intersecting the predetermined direction;
Scanning means for causing the recording head to scan the unit area on the recording medium a plurality of times in the intersecting direction;
First acquisition means for acquiring image data corresponding to an image to be recorded in the unit area;
The plurality of scans by the scanning unit based on the image data acquired by the first acquisition unit and a plurality of mask patterns that respectively define recording rates at respective positions of the plurality of ejection port arrays. Generating means for generating recording data used for ejecting ink to the unit area in each of
Control means for controlling to eject ink from the recording head being scanned by the scanning means based on the recording data generated by the generating means, and an ink jet recording apparatus comprising:
In the plurality of ejection port arrays, there is no ejection port array that ejects ink of the same color as the first color other than the first ejection port array,
The generation unit is based on (i) the image data corresponding to the first color ink acquired by the first acquisition unit, and a first mask pattern of the plurality of mask patterns. Generating the recording data corresponding to the first color ink, and (ii) the image data corresponding to the second color ink acquired by the first acquisition unit; of the mask pattern, rather smaller than the predetermined direction of the mask pattern difference of the recording rate is the first in the recording rate and the central portion of the end portion of the discharge port array, and the predetermined direction of the discharge port array Lee that of the low There second mask pattern than the recording rate is the first mask pattern at the center, based on, and generates the recording data corresponding to the ink of the second color Kujetto recording device. A second obtaining unit for obtaining information relating to the ejection amount of the second color ink on the recording medium;
(Ii-1) When the ink discharge amount indicated by the information acquired by the second acquisition unit is greater than a predetermined threshold, the generation unit is configured to acquire the second acquired by the first acquisition unit. Generating the recording data corresponding to the second color ink based on the image data corresponding to the second color ink and the second mask pattern of the plurality of mask patterns; ii-2) When the ink discharge amount indicated by the information acquired by the second acquisition unit is less than the predetermined threshold, the second color ink acquired by the first acquisition unit The recording data corresponding to the ink of the second color is generated based on the corresponding image data and the first mask pattern of the plurality of mask patterns. The ink-jet recording apparatus according to Motomeko 1. A first recording mode for performing recording by causing the scanning unit to scan the unit area a first number of times by the scanning unit; and the first recording mode for the unit region by the scanning unit. Among a plurality of recording modes including a second recording mode in which recording is performed by scanning a second number greater than the number of times, one recording mode is performed as a recording mode executed when recording on the recording medium. A determination means for determining;
The generation means corresponds to (ii-1) the second color ink acquired by the first acquisition means when the determination means determines that the first recording mode is to be executed. Generating the recording data corresponding to the ink of the second color based on the image data to be performed and the second mask pattern of the plurality of mask patterns, and (ii-2) the determination When the second recording mode is determined as the recording mode to be executed by the means, the image data corresponding to the second color ink acquired by the first acquisition means, and the plurality of mask patterns said first mask pattern out, on the basis of, inkjet according to claim 1, characterized in that to generate the recording data corresponding to the ink of the second color Door recording device. The third color is a color having a higher density than the second color,
The generating unit is based on the image data corresponding to the ink of the third color acquired by the first acquiring unit, and the first mask pattern of the plurality of mask patterns. The inkjet recording apparatus according to claim 1, wherein the recording data corresponding to the third color ink is generated. The recording rate in the predetermined direction of the end portion of the second of the discharge port array in the mask pattern is higher than the recording rate in the predetermined direction of the end portion of the ejection opening array of said first mask in the pattern The ink jet recording apparatus according to claim 1, wherein:   6. The scanning unit according to claim 1, wherein the scanning unit scans the recording head in a direction from the second ejection port array side toward the first ejection port array side along at least the intersecting direction. The ink jet recording apparatus according to any one of the above. For a plurality of the ejection port arrays configured by having ejection port arrays in which a plurality of ejection ports for ejecting the same color ink are arranged in a predetermined direction, one for each color , the plurality of ejection port arrays Recording heads arranged side by side in a crossing direction crossing a predetermined direction;
Scanning means for causing the recording head to scan the unit area on the recording medium a plurality of times in the intersecting direction;
First acquisition means for acquiring image data corresponding to each of the plurality of color inks corresponding to the image to be recorded in the unit area;
A plurality of mask patterns for determining a recording rate at each position of the plurality of ejection port arrays for each of the image data corresponding to each of the plurality of colors of ink acquired by the first acquisition unit Selecting means for selecting one of the mask patterns from
Based on the image data corresponding to each of the plurality of color inks acquired by the first acquisition unit, and the mask pattern corresponding to each of the plurality of color inks selected by the selection unit. Generating means for generating recording data corresponding to each of the plurality of color inks used for ejecting ink to the unit region in each of the plurality of scans by the scanning means;
Control means for controlling to eject ink from the recording head being scanned by the scanning means based on the recording data generated by the generating means, and an ink jet recording apparatus comprising:
The selection means (i) relates to one ejection port array, and the other ejection port arrays adjacent in the intersecting direction include the other ejection port arrays other than the other ejection port arrays. In the case where there is an ejection port array that ejects ink of the same color as the color of ink ejected from the ejection port array, the image data corresponding to the ink ejected from the one ejection port array A first mask pattern is selected from among a plurality of mask patterns, and (ii) with respect to one of the plurality of discharge port arrays, the other discharge port arrays adjacent in the intersecting direction are included in the plurality of discharge port arrays. In the case where there is no ejection port array that ejects ink of the same color as the color of ink ejected from the other ejection port array other than the other ejection port array, ejection is performed from the one ejection port array. The image data corresponding to ink Of the number of the mask pattern, the difference between the recording rate in the recording rate and the central portion in the predetermined direction of the end portion of the discharge port array rather smaller than the first mask pattern, and wherein said discharge port array an ink jet recording apparatus characterized by recording rate in the central portion in a predetermined direction to select a low There second mask pattern than the first mask pattern. The first ejection port array in which a plurality of ejection ports that eject ink of the first color are arranged in a predetermined direction, and the plurality of ejection ports that eject ink of a second color different from the first color are A second ejection port array arranged in a predetermined direction and a plurality of ejection ports that eject ink of a third color that is the same color as the second color and has a density different from that of the second color A plurality of ejection port arrays for ejecting ink of a plurality of colors including at least a third ejection port array arranged in the predetermined direction, the first ejection port array and the second ejection port A scanning step of causing the recording heads arranged in the cross direction to scan a plurality of times in the cross direction with respect to the unit area on the print medium so that the columns are adjacent to the cross direction crossing the predetermined direction;
A first acquisition step of acquiring image data corresponding to an image to be recorded in the unit area;
The plurality of scans in the scanning step based on the image data acquired in the first acquisition step and a plurality of mask patterns that respectively define recording rates at respective positions of the plurality of ejection port arrays. Generating a recording data used for ejecting ink to the unit area in each of the above,
A control step of controlling to eject ink from the recording head being scanned in the scanning step based on the recording data generated in the generation step,
In the plurality of ejection port arrays, there is no ejection port array that ejects ink of the same color as the first color other than the first ejection port array,
The generation step is based on (i) the image data corresponding to the first color ink acquired in the first acquisition step, and a first mask pattern of the plurality of mask patterns. Generating the recording data corresponding to the first color ink, and (ii) the image data corresponding to the second color ink acquired in the first acquisition step; of the mask pattern, rather smaller than the predetermined direction of the mask pattern difference of the recording rate is the first in the recording rate and the central portion of the end portion of the discharge port array, and the predetermined direction of the discharge port array Lee that of the low There second mask pattern than the recording rate is the first mask pattern at the center, based on, and generates the recording data corresponding to the ink of the second color Kujetto recording method. For a plurality of the ejection port arrays configured by having ejection port arrays in which a plurality of ejection ports for ejecting the same color ink are arranged in a predetermined direction, one for each color , the plurality of ejection port arrays A scanning step of scanning the recording heads arranged side by side in the intersecting direction intersecting the predetermined direction a plurality of times in the intersecting direction with respect to the unit area on the recording medium;
A first acquisition step of acquiring image data corresponding to each of the plurality of color inks corresponding to the image to be recorded in the unit region;
A plurality of mask patterns for determining a recording rate at each position of the plurality of ejection port arrays for each of the image data corresponding to each of the plurality of color inks acquired in the first acquisition step. A selection step of selecting one of the mask patterns from
Based on the image data corresponding to each of the plurality of color inks acquired in the first acquisition step, and the mask pattern corresponding to each of the plurality of color inks selected in the selection step. A generation step of generating recording data corresponding to each of the plurality of color inks used to eject ink to the unit region in each of the plurality of scans in the scanning step;
A control step of controlling to eject ink from the recording head being scanned in the scanning step based on the recording data generated in the generation step,
The selection step (i) relates to one discharge port array, and the other discharge port arrays adjacent in the intersecting direction include other ones in the plurality of discharge port arrays in addition to the other discharge port arrays. In the case where there is an ejection port array that ejects ink of the same color as the color of ink ejected from the ejection port array, the image data corresponding to the ink ejected from the one ejection port array A first mask pattern is selected from among a plurality of mask patterns, and (ii) with respect to one of the plurality of discharge port arrays, the other discharge port arrays adjacent in the intersecting direction are included in the plurality of discharge port arrays. In the case where there is no ejection port array that ejects ink of the same color as the color of ink ejected from the other ejection port array other than the other ejection port array, ejection is performed from the one ejection port array. The image data corresponding to ink Of the number of the mask pattern, the difference between the recording rate in the recording rate and the central portion in the predetermined direction of the end portion of the discharge port array rather smaller than the first mask pattern, and wherein said discharge port array an ink jet recording method characterized by recording rate in the central portion in a predetermined direction to select a second mask pattern have lower than the first mask pattern.

Images