JP5084159B2 - Inkjet recording apparatus, inkjet recording method, and program - Google Patents

Description

  The present invention relates to an inkjet recording apparatus, an inkjet recording method, and a program for setting recording conditions for recording an image by reciprocally scanning a recording head in a main scanning direction on a predetermined recording area of a recording medium. It is about.

  The present invention can be widely applied to various ink jet recording systems that employ a so-called bidirectional multi-scan method. The present invention can be applied to, for example, a recording apparatus having functions such as a printer, a copier, and a facsimile, or a recording apparatus that is used as an output device of a multifunction peripheral including a computer or a word processor or a workstation.

  Typical recording methods of the recording apparatus include an ink jet method, a wire dot method, a heat sensitive method, a sublimation / thermal transfer method, an electrophotographic method, and a silver salt photographic method. Among them, the ink jet system has an advantage that high-quality images can be recorded on various recording media with a relatively simple configuration. Such an ink jet recording apparatus (ink jet recording apparatus) is roughly classified into a serial scan type and a full line type.

  In a serial scan type ink jet recording apparatus, an ink jet recording head capable of ejecting ink is mounted on a carriage that reciprocates in a main scanning direction that intersects a conveyance direction (sub scanning direction) of a recording medium. When recording an image, a recording scan in which the recording head is moved in the main scanning direction together with the carriage and ink is ejected from the recording head, and a conveying operation in which the recording medium is conveyed in the sub-scanning direction are repeated. Such serial scan type ink jet recording apparatuses include a unidirectional recording method and a bidirectional recording method. In the one-way recording method, recording scanning is performed by ejecting ink from the recording head only when the recording head moves in one direction. In the bidirectional recording method, when the recording head moves in either one direction or the other direction, recording scanning is performed by ejecting ink from the recording head.

  On the other hand, in a full-line type ink jet recording apparatus, a long ink jet recording head that extends over the entire width direction of a recording area of a recording medium is used. When recording an image, ink is ejected from the recording head while the recording medium is continuously conveyed in the length direction. As a result, images are continuously recorded on the recording medium.

  A recording head used in an ink jet recording apparatus is formed with a plurality of nozzles that eject ink based on an image signal. Depending on the image signal, a nozzle that does not eject ink for a long time is generated. As such, the ink in the nozzle that does not eject ink for a long time remains exposed to the air. For this reason, the ink near the discharge port of the nozzle may be dried or thickened, and some ink may be crystallized. As a countermeasure against these problems, for example, Patent Document 1 describes a method in which after a recording head is heated, ink that does not contribute to image recording is ejected from a nozzle (preliminary ejection). Patent Document 2 describes a configuration in which the number of ink ejections in preliminary ejection is set in accordance with manufacturing variations of the recording head. Patent Documents 3 and 4 describe inks outside the image recording range. A configuration for preliminary ejection is described.

  Further, when a nozzle having a low ink discharge frequency is dried and the ink density near the ink discharge port is changed, there is a possibility that the recording density of the image is uneven. Patent Documents 4 and 5 describe a method for reducing recording density unevenness due to such drying of the nozzles in a bidirectional recording type ink jet recording apparatus. That is, Patent Document 4 discloses a method of reducing an image recording ratio when an image is recorded while preliminarily ejecting ink from a recording head and then moving the recording head from a scanning start position toward a scanning end position. Is described. Further, in Patent Document 5, when an image is recorded using a high density ink and a low density ink, the number of scans for ejecting the high density ink and recording the image is the same as that for recording the image by ejecting the low density ink. A method for reducing the number of scans is described.

Japanese Patent No. 02742079 Japanese Patent No. 0320268 gazette Japanese Patent No. 0334913 JP 2004-066669 A JP 2004-066668 A

  As described in Patent Document 4, when the image recording ratio is reduced in accordance with the movement of the recording head from the scanning start position to the scanning end position after preliminary ejection, in the vicinity of the scanning end position. The recording ratio is the smallest. For this reason, the frequency of ink ejection from the nozzles decreases in the vicinity of the scanning end position, and accordingly, the number of nozzles whose ink density changes near the ejection ports increases. Depending on the type of ink, the viscosity of the nozzle may increase due to the drying of the nozzle, making it impossible to eject from the nozzle.

  As described in Patent Document 5, when an image is recorded using high density ink and low density ink, the recording speed is reduced by the amount of low density ink used.

  Some serial scan type inkjet recording apparatuses employ a multi-pass recording method in which an image in a predetermined recording area is completed by a plurality of recording scans of a recording head. In this case, in the plurality of recording scans, it may take several seconds between the previous recording scan and the subsequent recording scan. In particular, when the image data increases with the increase in the resolution and the number of colors of the recorded image, it takes time for communication and data processing, and the time interval in the preceding and subsequent recording scans becomes longer. In addition, for example, an inkjet recording apparatus for a large-sized recording medium such as a 44 inch width or a 60 inch width differs from an A4 or A3 size recording medium inkjet recording apparatus in that the time required for one recording scan is as follows. It tends to be long. In this way, when the time interval between the preceding and following recording scans is long, when a plurality of recording scans are performed on a predetermined recording area on the recording medium, the ink that has landed during the first recording scan has considerably dried. Therefore, ink is landed by the subsequent recording scan. When the ink that has landed first occupies an area factor greater than a predetermined value on the recording medium, the ink that lands later becomes difficult to be absorbed by the recording medium by drying. As described above, the phenomenon that the absorbability of the ink that has landed later is impaired due to the drying of the ink that has landed first is also referred to as a “sealing problem”. Such a sealing problem is particularly noticeable when ink having a high absorption speed with respect to the recording medium is landed first.

  An object of the present invention is to provide an ink jet recording apparatus, an ink jet recording method, and a program capable of recording a high quality image while minimizing the adverse effect of the drying of the nozzles of the recording head on the quality of the recorded image. is there.

The ink jet recording apparatus of the present invention reciprocally scans a recording head capable of ejecting ink from a plurality of nozzles in a main scanning direction on a predetermined recording area of a recording medium, thereby generating an image corresponding to image data. In the ink jet recording apparatus for recording in the recording area, recording of the first area from the forward scanning start position side of the recording head to a predetermined first position in the middle of the recording area is permitted, and the first position To the first scanning by the forward scanning based on the recording data obtained by the first mask that divides the image data so as not to allow the recording in the downstream area in the forward scanning direction, and the recovery of the recording head. Recording in the second area from the scanning start position side to a predetermined second position in the middle of the recording area is allowed, and downstream from the second position in the backward scanning direction. Dividing the image data so as not to allow recording in a region and obtaining a second recording by reverse scanning based on the recording data obtained by a second mask complementary to the first mask; It is characterized by performing .

In the ink jet recording method of the present invention, an image corresponding to image data is obtained by reciprocally scanning a recording head capable of ejecting ink from a plurality of nozzles in a main scanning direction on a predetermined recording area of a recording medium. In the ink jet recording method for recording in the recording area, recording in the first area from the forward scanning start position side of the recording head to a predetermined first position in the middle of the recording area is permitted, and the first position To the first scanning by the forward scanning based on the recording data obtained by the first mask that divides the image data so as not to allow the recording in the downstream area in the forward scanning direction, and the recovery of the recording head. Recording in the second area from the scanning start position side to a predetermined second position in the middle of the recording area is allowed, and downstream from the second position in the backward scanning direction. Dividing the image data so as not to allow recording in a region and obtaining a second recording by reverse scanning based on the recording data obtained by a second mask complementary to the first mask; It is characterized by performing .

The program according to the present invention records an image corresponding to image data by reciprocally scanning a recording head capable of ejecting ink from a plurality of nozzles in a main scanning direction on a predetermined recording area of a recording medium. A program for recording in an area, wherein recording of a first area from a forward scan start position side of the recording head to a predetermined first position in the middle of the recording area is permitted, and the first position To the first scanning by the forward scanning based on the recording data obtained by the first mask that divides the image data so as not to allow the recording in the downstream area in the forward scanning direction, and the recovery of the recording head. Recording in the second area from the scanning start position side to a predetermined second position in the middle of the recording area is allowed, and recording in the downstream area from the second position in the backward scanning direction is allowed. The image data is divided so as not, and the first mask are complementary obtained by the second mask, perform a second recording by backward scanning based on recording data, a step of performing a computer It is characterized by making it.

  According to the present invention, in the so-called bidirectional multi-scan method, the recording ratio is set according to the scanning position of the recording head, and the width of the recording area is limited according to the recording ratio. Accordingly, when there is a possibility that drying of the nozzles of the recording head may adversely affect ink ejection, it is possible to record an image only during a time when the adverse effect is small. As a result, it is possible to record a high-quality image while minimizing the adverse effect of drying of the nozzles of the recording head on the quality of the recorded image.

  In addition, the recording ratio can be easily set by using a plurality of masks having different thinning rates of image data. In addition, by using a mask corresponding to the size in which the nozzle array is divided into a plurality of blocks, it is not necessary to prepare a large mask corresponding to the entire area of the nozzle array, and recording is performed even on a recording medium of a large size. The memory size can be reduced even when the operation is performed.

  In addition, at least one of a plurality of scans on a predetermined recording area, the recording ratio is constant, and the width of the recording area is not limited, so that the recording result is obtained by forward scanning and backward scanning. When there is a color difference in the color difference, the color difference can be kept small. At that time, when a specific nozzle of a plurality of nozzle arrays is used as a nozzle array that performs recording at a constant recording ratio, recovery processing is performed only for the specific nozzle, and then the constant recording is performed. A recording scan based on the ratio may be performed. The recovery process prevents the nozzle from being dried. The recovery process may be, for example, a process of ejecting ink that does not contribute to image recording on a recording medium.

  In addition, by providing a plurality of nozzle rows corresponding to at least one specific ink among a plurality of nozzle rows corresponding to a plurality of different inks, it is possible to equalize the frequency of ink use.

  In addition, when there is a possibility that a color difference may occur in the recording results of forward scanning and sub-scanning by positioning nozzle arrays corresponding to other inks among a plurality of nozzle arrays corresponding to specific ink, the color difference Can be kept small. That is, when there is a possibility that a color difference may occur due to a difference in the application order of a plurality of different inks in the print results of the forward scan and the backward scan, the application order of the plurality of inks can be set so as to reduce the color difference.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a perspective view for explaining a schematic configuration of a serial scan type inkjet recording apparatus to which the present invention is applicable.

  In the recording apparatus 50 of this example, a carriage 53 is guided by guide shafts 51 and 52 so as to be movable in the main scanning direction indicated by an arrow X. The carriage 53 is reciprocated in the main scanning direction by a driving force transmission mechanism such as a carriage motor and a belt for transmitting the driving force. An ink jet recording head 10 (see FIG. 2) and an ink tank 54 that supplies ink to the recording head 10 are mounted on the carriage 53. The recording head 10 and the ink tank 54 may constitute an ink jet cartridge. After the paper P as a recording medium is inserted from the insertion port 55 provided at the front end of the apparatus, the transport direction is reversed, and then the paper P is transported in the sub-scanning direction indicated by the arrow Y by the feed roller 56. The recording apparatus 50 performs sub-scanning of the paper P by a distance corresponding to the recording operation for moving the recording head 10 in the main scanning direction and ejecting ink toward the recording area of the paper P on the platen 57. Repeat the transport operation to transport in the direction. As a result, images are sequentially recorded on the paper P. These recording operations and transport operations may be alternately repeated once, or a plurality of recording operations and one transport operation may be alternately repeated.

  A plurality of nozzles capable of ejecting ink are formed in the recording head 10, and these nozzles form a nozzle row aligned along the sub-scanning direction. When an image is recorded using a plurality of different types of ink, a nozzle row is formed for each ink type. The nozzle is configured to eject ink from the ejection port using ejection energy generating means such as an electrothermal transducer (heater) or a piezo element. When the electrothermal converter is used, the ink can be foamed by the heat generation, and the ink can be ejected from the ink ejection port of the nozzle using the foaming energy.

  A home position is set at the left end in FIG. At the home position, there is provided a recovery system unit (recovery processing means) 58 that faces the ejection port formation surface of the recording head 10 mounted on the carriage 53. The recovery system unit 58 includes a cap capable of capping the discharge port of the recording head 10 and a suction pump capable of introducing a negative pressure into the cap. By introducing negative pressure into the cap covering the ejection port, ink is sucked and discharged from the ejection port, and a recovery process (also referred to as “suction recovery process”) is performed to maintain a good ink ejection state of the recording head 10. Can do. Also, a recovery process (also referred to as “discharge recovery process”) may be performed to maintain a good ink discharge state of the recording head 10 by discharging ink that does not contribute to the image from the discharge port toward the inside of the cap. it can.

  FIG. 2 is a schematic block configuration diagram of a control system of the recording apparatus 50.

  In FIG. 2, the CPU 100 executes control processing of the operation of the recording apparatus 50, data processing, and the like. The ROM 101 stores programs such as those processing procedures, and the RAM 102 is used as a work area for executing these processes. The CPU 100 controls ejection energy generating means such as an electrothermal converter in the recording head 10 via the head driver 10A. Further, the CPU 100 controls a carriage motor 103 for driving the carriage 53 in the main scanning direction via the motor driver 103A and at the same time P. The F motor 104 is controlled via the motor driver 104A.

  FIG. 3 is a basic block diagram of an image data processing system in a recording system to which the recording apparatus 50 of this example can be applied.

  The recording system J0011 of this example includes a host device 200 and a recording device 50. The host device 200 generates image data to be recorded (image data), sets a UI (user interface) for generating the data, and the like. The recording device 50 records an image on the paper P based on the image data generated by the host device 200. The recording apparatus 50 of this example performs recording using 10 color inks. The ten color inks are cyan (C), light cyan (Lc), magenta (M), light magenta (Lm), yellow (Y), red (R), green (G), first black (K1), Second black (K2) and gray (Gray) ink. As the recording head 10, a recording head that discharges these 10 colors of ink is used. As these 10-color inks, pigment inks containing pigments as colorants can be used.

  Examples of programs that operate on the operating system of the host device 200 include applications and printer drivers. The application J0001 executes processing for creating image data to be recorded by the recording device 50. This image data or data before editing or the like can be taken into a host device 200 such as a personal computer (PC) via various media. For example, the host device 200 can capture image data in JPEG format captured by a digital camera using a CF card. The host device 200 can also capture TIFF format image data read by a scanner and image data stored in a CD-ROM. Furthermore, the host device 200 can also fetch data on the web via the Internet. These captured data are displayed on the monitor of the host device 200, and edited, processed, and the like by the application J0001, thereby creating, for example, sRGB standard image data R, G, and B. On the UI screen displayed on the monitor of the host device 200, the user sets the type of recording medium used for recording, the quality of recording, and the like, and instructs the execution of recording. In response to this recording instruction, the image data R, G, and B are transferred to the printer driver.

  The printer driver processing includes pre-processing J0002, post-processing J0003, γ correction J0004, halftoning J0005, and print data creation J0006. Hereinafter, these processes J0002 to J0006 will be described.

(A) Pre-stage process In the pre-stage process J0002, color gamut mapping is performed. In this example, data conversion is performed to map the color gamut reproduced by the image data R, G, B of the sRGB standard into the color gamut reproduced by the recording device 50. Specifically, by using a three-dimensional LUT (look-up table), 256-color image data R, G, and B in which R, G, and B are each expressed by 8 bits are used for the color of the recording apparatus 50. Convert to 8-bit data R, G, B in the area.

(B) Subsequent processing In the post-processing J0003, Y, M, Lm, C, Lc, K1, K2, R, R, G, B based on the 8-bit data R, G, B to which the color gamut was mapped in the pre-processing J0002. G, Gray color separation data, that is, 10 color separation data (8 bits) is obtained. The 10 color separation data (8 bits) corresponds to a combination of inks that reproduce the colors represented by the 8-bit data R, G, and B. The post-stage process J0003 in this example performs an interpolation operation using a three-dimensional LUT as in the pre-stage process J0002.

(C) γ Processing The γ correction J0004 performs density value (gradation value) conversion for each color data of the color separation data obtained by the post-processing J0003. Specifically, by using a one-dimensional LUT corresponding to the gradation characteristics of each color ink of the recording apparatus 50, conversion is performed so that the color separation data is linearly associated with the gradation characteristics of the recording apparatus 50.

(D) Halftoning Halftoning J0005 converts each of 8-bit color separation data Y, M, Lm, C, Lc, K1, K2, R, G, and Gray that have been subjected to γ correction into 4-bit data. Quantize for. In this example, 256-bit 8-bit data is converted into 9-gradation 4-bit data using an error diffusion method. This 4-bit data is data serving as an index for indicating the arrangement pattern in the dot arrangement patterning process of the recording apparatus 50.

(E) Recording Data Creation Processing At the end of the processing performed by the printer driver, recording data created by adding recording control information to the recording image data containing the 4-bit index data is recorded by the recording data creation processing J0006. create. The recording data generated in this way is supplied to the recording device 50.

  The recording apparatus 50 performs a dot arrangement patterning process J0007 and a mask data conversion process J0008 for the recording.

(F) Dot Arrangement Patterning In the halftoning J0005 described above, the number of gradation levels is reduced from 256-value multi-value density information (8-bit data) to 9-value gradation value information (4-bit data). However, the data that can be actually recorded by the recording apparatus 50 is binary data (1 bit data) indicating whether or not to record ink dots. Therefore, in the dot arrangement patterning process J0007, for each pixel expressed by 4-bit data of gradation levels 0 to 8 output from the halftoning J0005, the gradation value (level 0 to 8) of that pixel is supported. The assigned dot arrangement pattern is assigned. As a result, whether or not ink dots are recorded (dot on / off) is defined in each of a plurality of areas in one pixel, and 1 bit of “1” or “0” is set for each area in one pixel. Binary data is arranged. Here, “1” is binary data indicating dot recording, and “0” is binary data indicating non-recording. In this specification, “pixel” is a minimum unit that can express gradation, and is an image process of multi-bit multi-value data (processes such as the preceding stage, the latter stage, γ correction, and halftoning). This is the smallest unit of interest.

  At the stage where such dot arrangement patterning processing J0007 is completed, all dot arrangement patterns for the recording medium are determined.

(G) Mask data conversion process The dot arrangement patterning process J0007 described above determines the presence or absence of dots for each area on the recording medium. Therefore, a desired image can be recorded by inputting binary data indicating the dot arrangement to the head driver (head driving circuit) 10A of the recording head 10. In that case, an image can be recorded by a so-called one-pass recording method or multi-pass recording method. In the 1-pass printing method, recording in the same scanning area on the recording medium is completed by one scan, and in the multi-pass printing system, printing in the same scanning area on the printing medium is performed by a plurality of scans. Completed. Furthermore, as a recording method, one-way recording in which an image is recorded only when the recording head 10 moves in one direction, or bidirectional recording in which an image is recorded when the recording head 10 moves in both directions can be adopted. .

  In this example, the pre-processing J0002, the post-processing J0003, the γ processing J0004, the halftoning J0005, and the print data creation J0006 are executed by the host device 200. The dot arrangement patterning process J0007 and the mask data conversion process J0008 are executed by the recording apparatus 50. However, the present invention is not limited to this form. For example, a part of the processes J0002 to J0006 executed by the host apparatus 200 may be executed by the recording apparatus 50, or all processes may be executed by the host apparatus 200. Good. Alternatively, the processing J0002 to J0008 may be executed by the recording device 50.

  FIG. 4 is an explanatory diagram of a recording operation in the bidirectional 8-pass recording method.

  In the recording head 10, nozzles capable of ejecting ink are arranged in a line along the sub-scanning direction of the arrow Y. In this example, for convenience of explanation, the nozzle rows 10K, 10C, 10M, and the like that are capable of ejecting ink of four colors of black (BK), cyan (C), magenta (M), and yellow (Y) are applied to the recording head 10. Assume that 10Y is formed. The number of nozzle rows and the arrangement order in the recording head 10 are not particularly limited.

  In the recording operation based on the input image signal, first, the paper (recording medium) P is conveyed to the position (1) in the figure. Then, while moving the recording head 10 in the arrow X1 direction (forward direction), the first line image is recorded on the area P1 of the paper P by the nozzles in the range of 1/8 from the lower end of the nozzle row. Thereafter, the paper P is conveyed to the position (2). Then, while moving the recording head 10 in the direction of the arrow X2 (reverse direction), the image of the second line is recorded in the region P1 by the nozzle in the range of 2/8 from the lower end of the nozzle row, and from the lower end of the nozzle row. The image of the first line is recorded in the region P2 by the nozzle in the range of 1/8. Here, the second line means that the recording scan for the same recording area is the second time. In the case of the 8-pass recording system as in this example, 1, 2, 3,... -The 8th line image will be recorded. When the image of the seventh line is recorded by repeating such bi-directional recording scanning, the sheet P is conveyed to the position (7), and then the area is set by the nozzle in the range of 7/8 from the lower end of the nozzle row. An image is recorded in the area from P1 to P7. When the image of the next eighth line is recorded, after the sheet P is conveyed to the position (8), the image is recorded in the areas P1 to P8 by the nozzles in the entire range of the nozzle row. Thereby, the image of the area P1 is completed. Thereafter, when the paper P is conveyed to the position (9), the image of the region P2 is completed by recording the image from the region P2 to P9 by the nozzles in the entire range of the nozzle row. Thereafter, by repeating the same recording scan, the images of the regions P3, P4.

  In the case of this example, when the first scan, the odd number of the third time,..., The forward scan (direction X1 in the figure) is performed, and when the second, fourth,. Is a recording scan in the backward direction (X2 direction in the figure). The ink ejection order is yellow (Y), magenta (M), cyan (C), and black (BK) in the forward recording scan, and black (inversely) in the backward recording scan. BK), cyan (C), magenta (M), and yellow (Y). When the ink ejection order is changed, a color difference may occur in the recorded image. As a countermeasure, a configuration has been proposed in which nozzle rows for each color are provided in contrast to the main scanning direction to match the ejection order of each color ink in the forward and backward printing scans. However, even in such a configuration, the first line is recorded by either forward or backward recording scans due to variations in manufacturing of the recording head and variations in the mounting position and mounting accuracy of the recording head. Depending on the color, uneven color may occur. As a countermeasure, it is effective to increase the number of superimposed images, that is, to increase the number of recording scans for a predetermined recording area, such as 8 passes or more. As another countermeasure, when an image recorded by forward and backward printing scans is known in advance where there is a possibility that a color difference may occur, image data conversion is performed so as to suppress the color difference. It is effective to optimize the color conversion profile for use. The present embodiment is an application example in a case where such a color conversion profile is optimized.

  FIG. 5 is a diagram for explaining an example of processing of recording data in the bidirectional 8-pass recording method of this example, and FIG. 6 is an explanatory diagram of a specific recording ratio in that case.

  FIG. 5 is an explanatory diagram of data processing when uniform black image recording data (multi-value) D1 is input. A black image can be recorded by black (BK) ink, or by overlapping yellow (Y), magenta (M), and cyan (C) inks.

  In this example, ink is ejected in the order of yellow (Y), magenta (M), and cyan (C) in the forward recording scan, and cyan (C) in the reverse recording scan. ), Magenta (M) and yellow (Y) inks are sequentially ejected. Such a difference in ink ejection order may cause a color difference in the black image. In order to suppress the color difference, the multi-value data D2-1 for forward scanning and the backward scanning multi-value data D2-1 are used to suppress the color difference. Multi-value data D2-2 is generated. The multi-value data D2-1 is data necessary for recording a black image corresponding to the recording data D1 by overlaying ink in the order of yellow (Y), magenta (M), and cyan (C), that is, recording data D1. Is data required when printing is performed only by forward scanning. On the other hand, the multi-value data D2-2 is data necessary for recording a black image corresponding to the recording data D1 by overlaying ink in the order of cyan (C), magenta (M), and yellow (Y), that is, recording. This data is necessary when the data D1 is recorded only by backward scanning.

  From such multi-value data D2-1 and D2-2, binarized color separation data D3-1 and D3-2 are generated. These data D3-1 and D3-2 correspond to binary data of Y, M, and C subjected to the dot arrangement patterning process (J007) in FIG. Therefore, if a black image recorded only by the forward scan based on the data D3-1 and a black image recorded only by the backward scan based on the data D3-2 are compared, the color difference between them is extremely severe. Small.

  Next, such data D3-1 and D3-2 are subjected to mask processing (corresponding to mask data conversion processing (J0008) in FIG. 3). In this example, the data D3-1 is thinned out at an equal rate of 25% by a random mask (25% uniform mask) to generate four thinned data. As is well known, the random mask is a mask for thinning out the data corresponding to the nozzles so as to have randomness for each printing scan. Specifically, 25% of data corresponding to each nozzle is thinned out. The four data thinned out at a rate of 25% by the random mask are in a complementary relationship such that the sum of them becomes data D3-1, and is for forward scanning (first, third, fifth and seventh scanning). Used as original data. Similarly, with respect to the data D3-2, the same random mask (25% uniform mask) is used to thin out the data at an equal rate of 25%, thereby generating four thinned data. These four data are in a complementary relationship such that the sum of them becomes data D3-1, and is used as original data for backward scanning (second, fourth, sixth, and eighth scanning).

  The random mask in this example has a size corresponding to 1280 × 1040 (pixels), and 1280 (pixels) corresponds to the number of nozzles forming the nozzle row. Moreover, as such a random mask, in addition to the uniform mask as in this example, as previously proposed, a gradation shape or a trapezoidal shape that reduces the recording ratio by the nozzles located at both ends of the nozzle row Can also be used.

  In the present embodiment, each recording area of the data D3-1 and D3-2 is divided into three areas (0, 1, 2) in the main scanning direction, and data corresponding to each area is prepared in advance. Further thin out using a mask. In FIG. 5, the left side of the recording area of data D3-1 and D3-2 is area 0, the center is area 1 and the right side is area 2, and in order to thin out data corresponding to these areas, A fixed mask is selected one by one. The fixed mask of this example has a size corresponding to 4 × 4 (pixels), and three types of fixed masks (0, 1, 2) for forward scanning and three types of fixed masks (0 for backward scanning). , 1, 2). In FIG. 5, the black portion of the fixed mask means that a dot is formed if there is data, and the white portion means that no dot is formed even if there is data. The forward scanning fixed mask 0 and the backward scanning fixed mask 0 are complementary to each other, and when they are overlapped, all the pixels are filled. Similarly, fixed masks 1 and 1 for forward scanning and backward scanning are also in a complementary relationship with each other, and fixed masks 2 and 2 for forward scanning and backward scanning are also in a complementary relationship with each other. In the case of this example, the forward scanning and backward scanning fixed masks 0 and 0 have a complementary relationship of 100% and 0%, and the forward scanning and backward scanning fixed masks 1 and 1 are 50% and 50%. The fixed masks 2 and 2 for forward scanning and backward scanning have a complementary relationship of 0% and 100%.

  In the recording area of the data D3-1, the data in the areas 0, 1, and 2 are thinned using the forward scanning fixed masks 0, 1, and 2, respectively, and in the recording area of the data D3-2, the areas 0, 1 , 2 is thinned out using fixed masks 0, 1, 2 for backward scanning.

  As a result, as shown in a square frame A in FIG. 5, 100% of the image is recorded in the left area 0 only by the forward scans of the first, third, and fifth scans. In this case, 100% of the image is recorded only by the second, fourth, sixth, and eighth scans. For the central region 1, 50% of images are formed by four forward scans and four reverse scans. By using the fixed mask in this way, the recording ratio between the forward scanning and the backward scanning changes in the areas 0, 1, and 2 in the main scanning direction, and as a result, the black image corresponding to the recording data D1 becomes high quality. Can be recorded.

In the case of Patent Document 5 described above, the recording ratio for forward scanning and backward scanning is reduced in the main scanning direction. However, in the case of this embodiment, the recording area is limited so as to record the areas 0 and 1 narrower than the entire areas 0, 1 and 2 in the main scanning direction during the forward scanning, and the main scanning direction is limited during the backward scanning. The recording area is limited so that the areas 1 and 2 narrower than the entire areas 0, 1 and 2 in the scanning direction are recorded. In the case of the present embodiment, recovery processing of the recording head 10 such as preliminary ejection is performed between forward scanning and backward scanning. Therefore, at the time of forward scanning after the recovery processing of the recording head 10, the recording ratio decreases from 25% to 12.5% and further to 0%. Similarly, at the time of backward scanning after the recovery processing of the recording head 10, the recording ratio is decreased from 25% to 12.5% and further to 0%. When the recovery system unit (recovery processing means) 58 is used for the recovery process, it may be provided not only at the left end in FIG. Further, the recovery process may be a process of discharging (preliminary discharge) ink that does not contribute to image recording onto a recording medium.

  As a result, it is possible to shorten the period in which the nozzle is in the recording state, that is, the period in which the nozzle is opened to the atmosphere while in the recording state, thereby reducing the exposure time of the nozzle that must guarantee the recording operation. That is, the period during which the recording ratio is 0% is a period in which the recording operation is not performed, and the nozzle exposure time in that period does not affect the recording operation. The recording area during the reciprocating operation of the recording head 10 is limited to exclude the period in which the recording ratio is 0%. Hereinafter, the means for limiting the recording area in this way is also referred to as a first means.

  6 uses a uniform mask that evenly thins out each of the data D3-1 and D3-2 by 25% as a random mask, and the fixed masks 0, 1, and 2 appear in the rectangular frame A in FIG. 2 is an explanatory diagram of a recording ratio when an image is recorded using 2. FIG. As described above, since the image of the area 0 is completed by four forward scans, at the time of each forward scan, an image is recorded on the basis of the data thinned by 25% by the random mask. The recording ratio is 25%. Further, as described above, since the image of region 2 is completed by four backward scans, at the time of each backward scan, an image is recorded based on data that is thinned by 25% by a random mask, The recording ratio is 25%. The image in area 1 is thinned out by the staggered pattern forward scanning fixed mask 1 and the backward scanning fixed mask 1 and recorded by a total of 8 scans of forward scanning and backward scanning. The extracted data will be further thinned by half. Therefore, for the area 1, the recording ratio by one scanning is 12.5%.

  When an image is recorded in this way, all the areas 0 are recorded by forward scanning, and all the areas 2 are recorded by backward scanning. When a black image is recorded in the areas 0 and 2 by superimposing Y, M, and C inks, the ink overlapping order in the areas 0 and 2 is reversed. Conventionally, there is a possibility that the color may change due to such a difference in the order of ink stacking. However, in the present embodiment, as described above, since the data D2-1 and D2-2 are generated using the color conversion profiles for forward scanning and backward scanning, the color difference between the recorded images in the areas 0 and 2 is reduced. Can be suppressed. Furthermore, since the region 1 exists between these regions 0 and 2, the color difference between the regions 0 and 2 can be made more difficult to visually recognize, and visual image deterioration can be suppressed.

  Further, by setting the recording ratio as in the present embodiment, the above-mentioned “sealing problem”, that is, the ink that has landed on the recording medium so as to occupy a large area factor is dried, and ink that subsequently lands The phenomenon which impairs the absorptivity of can be suppressed. Further, particularly when a high density image is continuously recorded on a recording medium having a large width, when the temperature of the nozzle tends to increase and the amount of ink discharged tends to increase, both sides of the recording medium in the width direction are used. It is possible to suppress the density difference of recorded images that is likely to occur.

  In the present embodiment, for the sake of convenience, the description is given as if the areas obtained by dividing the recording area into three equal parts in the main scanning direction are areas 0, 1, and 2. However, these areas 0, 1, and 2 need not be uniform in the main scanning direction. The number of such areas 0, 1, and 2 is not limited to three, and the recording area may be set to be divided into two equal parts in the main scanning direction, or may be set to four or more. In either case, the same effect can be obtained. Also, by increasing the number of such areas set, it is possible to gradually mix areas where density differences occur, which is preferable when density differences are likely to occur on both sides in the width direction of the recording medium.

  In this example, the case of recording a black image in which Y, M, and C inks are superimposed has been described. However, it goes without saying that the same applies to recording various images such as color and single color.

(Second Embodiment)
In the above-described embodiment, the color conversion profiles for forward scanning and backward scanning are used. However, the present invention is not limited to this. For example, a corresponding color conversion profile may be used for each region having different printing ratios in forward scanning and backward scanning, such as regions 0, 1, and 2. The present invention can also be applied to the case where one color conversion profile is used.

  When all the areas 0 are recorded by forward scanning and all the areas 2 are recorded by backward scanning as in the above-described embodiment, the color difference between them tends to increase. In this embodiment, in order to reduce such a color difference, as described later, the pass where the fixed mask is effective is limited, and in the pass where the fixed mask is invalid, the recording is performed with the recording ratio of the random mask. Paths with invalid fixed masks are set to paths that tend to control the color of the image among the eight paths. For example, in the case of a so-called penetrating ink system that uses a dye ink that easily penetrates a recording medium, the pass that easily controls the color tone is the first pass, and in the case of a so-called superposition ink system that uses pigment ink. Is the last pass. With respect to such a pass that tends to dominate the color, the color difference between the region 0 and the region 2 can be kept small by making the recording ratio of the entire region in the main scanning direction recorded by the pass uniform (uniform recording). . Hereinafter, the means for keeping the color difference small is also referred to as second means.

  In the case of the present embodiment, in the 8-pass printing method using an additional ink system, the last two of the 8 passes are set as equal printing passes. That is, the recording pass with the nozzles 2/8 from the top in FIG. 4 is a uniform recording pass, and the recording pass with the nozzles 6/8 from the bottom in FIG.

  FIG. 7 is a diagram for explaining an example of processing of recording data in the present embodiment.

  In the present embodiment, the same recording data D1 as in FIG. 1 is converted to binary data D3 by one color conversion profile. This data D3 is thinned out into four data for main scanning (first, third, fifth and seventh scanning) using a random mask and at the same time for main scanning (2, 4, 6, and 7) using the same random mask. The data is thinned out to the four data of the eighth scan). At this time, for the data from the first scan to the sixth scan, the thinning rate is set to 25%, and for the data at the seventh and eighth scans, the thinning rate is set to 12.5%. Specifically, the data corresponding to 2/8 nozzles from the top in FIG. 4 is thinned out by 25%, and the data corresponding to 6/8 nozzles from the bottom in FIG. 4 is thinned out by 12.5%.

  Then, as shown by a rectangular frame B in FIG. 7, the first to sixth scans are based on data thinned out selectively using the fixed masks 0, 1, and 2, as in the above-described embodiment. Record. On the other hand, in the seventh and eighth scans, an image is recorded based on data that is thinned to 12.5% by a random mask without using fixed masks 0, 1, and 2.

  As a result, as shown in FIG. 8, the print ratio for the seventh and eighth scans is equal to 12.5%. Further, as is clear from the comparison with FIG. 6, the recording ratio at the time of forward scanning in the area 0 and the recording ratio at the time of backward scanning in the area 2 are reduced from 100% to 87.5%, respectively.

  As described above, in the case of the present embodiment, in the multi-pass printing method using the addition type ink system, the last two passes are set to the equal printing pass without using the fixed mask, so The color difference can be reduced.

(Third embodiment)
In the case of the above-described embodiment, in each of the forward and backward print scans, the print ratio is decreased as the print scan starts and ends. However, the relationship between the recording scan position and the recording ratio is not limited to this. For example, the image recording range may be divided into two areas, with one area having a forward scanning ratio of 100% and the other area having a backward scanning ratio of 100%. Further, as in the present embodiment, the print ratio at the start of print scan may be increased or decreased.

FIG. 9 is an explanatory diagram of the relationship between the printing scan position and the printing ratio in the present embodiment.

  In this example, the image recording range on the recording medium P is divided into nine areas. The vertical ruled line on the lower side in FIG. 9 shows a state where the image recording range is divided. In this example, in order to perform marginless recording with no margin at the periphery of the recording medium P, a range larger than the recording medium P is set as an image recording range. The nine areas are areas 0, 1,... 8 from the left.

In the area 0, the forward scanning recording ratio per pass is set to 20%. Similarly, in the area 8, the backward scanning recording ratio per pass is set to 20%. In areas 1 and 2, the forward scanning recording ratio per pass is 23% and 25 %, and in areas 7 and 6, the backward scanning recording ratio per pass is 23% and 25 %. These areas 0, 1, and 2 are recorded only by the forward scanning, and the areas 8, 7, and 6 are recorded only by the backward scanning. For the areas 0 and 8 that may be located outside the recording medium P, the recording ratio of the eight passes is set to 80% of 100% or less (recording data is thinned out to 80%). Ink mist scattered outside can be suppressed. For the areas 1 and 7, in order to make the boundary with the areas 0 and 8 having a recording ratio of 80% inconspicuous in this way, the recording ratio is set to 92%, which is almost in the middle of 100% and 80% (recording data). Is reduced to 92%). For areas 2 to 6, the total recording ratio of 8 passes is 100%. Areas 3, 4, and 5 are recorded by forward scanning and backward scanning. For the central area 4, the printing ratio for forward scanning and backward scanning is set to 50%. For area 3, the recording ratio in the sub-scanning direction per pass is set to 5%, and for area 5, the recording ratio in the main scanning direction per pass is set to 5%. The boundary with the region 4 can be made inconspicuous.

  As described above, in order to determine the recording ratio in the main scanning direction, a relatively small fixed mask as in the above-described embodiment can be used as a mask for thinning out recording data. Thereby, even when recording on a large recording medium, the memory capacity can be kept small, and the calculation processing time can be shortened.

(Fourth embodiment)
The present invention is particularly effective when a multicolor pigment ink is used, and is also effective when a plurality of inks having different contents of the colorant and the colorant dispersion with respect to the ink solvent are used. In such a case, the ink having a small content of the colorant or the colorant dispersion has a relatively high absorption rate with respect to the ink receiving layer on the recording medium.

  Hereinafter, a case where dark and light inks are used as such inks will be described. In a recording apparatus for photo use, the basic main colors of C (cyan), M (magenta), Y (yellow), and K (black), which are widely used in the past, are light C (diluted cyan), In many cases, a total of six colors of ink are used, in which two colors of light M (diluted magenta) are added. The light C and light M inks obtained by diluting the main color ink are used to relax the graininess of the main color. When these structures are made of water-based pigment ink, light C and light M inks (hereinafter referred to as “light ink”) have a main color with respect to the ink receiving layer of the recording medium. Absorption speed tends to be faster than ink. In order to express the secondary color and the tertiary color, when the main color ink is applied to the recording medium prior to the light ink, and when the main color ink is applied to the recording medium after the light ink, The ink absorptivity, that is, the ink overflow state when an image is recorded on a recording medium is different. When the overflow state is different in this way and the image is recorded with different ink application sequences in the forward scan and the backward scan, the color difference between the forward scan and the backward scan makes it difficult to cause the above-mentioned problem of closing. It was easy to appear greatly. In particular, when a pigment ink is used, a color difference is likely to occur due to a difference in color constancy due to a local overflow of ink from a dot formation position and a presence or absence of a bronze phenomenon (image quality deterioration phenomenon).

  As described above, the ink absorbability (penetration) with respect to the recording medium is generally evaluated by the Bristow method. In this method, the recording medium is affixed to a rotating body so that the recording surface of the target recording medium is the upper surface, and a certain amount of ink droplets are applied while the rotating body is rotating. Dripping onto the recording surface of the recording medium. The traces of the ink droplets dropped on the recording surface are in a state of having a tail, and the ink absorbency is evaluated by measuring the length thereof. When the ink absorption speed is slow, the tail length becomes long, and when it is fast, the tail length becomes short.

  When the ink absorption speed was measured and checked for each ink type by such an evaluation method, light ink, particularly light C ink was fast, and dark ink was slow. For this reason, when recording was actually performed, when the dark ink was applied after the light ink was applied, the absorbability of the dark ink was deteriorated compared to the case where they were applied in the reverse order.

  FIG. 10 is an explanatory diagram in the case of recording an image by the multi-scan method as shown in FIG. 3 using the recording head 10 capable of ejecting six types of ink as an example of this embodiment. 10Y is a nozzle for discharging yellow (Y) ink, 10M is a nozzle for discharging magenta (M) ink, 10C is a nozzle for discharging cyan (C) ink, and 10K is a nozzle for discharging black (K) ink. 10C1 and 10C2 are first and second nozzles for discharging light cyan (light C) ink. The light C ink discharged from the former nozzle 10C1 is the light C1 ink, and the light C ink discharged from the latter nozzle 10C2. Is called light C2 ink. 10M1 and 10M2 are first and second nozzles for discharging light magenta (light M) ink. The light M ink discharged from the former nozzle 10M1 is the light M2 ink, and the light M ink discharged from the latter nozzle 10M2. Is called light M2 ink.

  When the recording head 10 performs recording scanning in the forward direction of the arrow X1, ink is applied in the order of K, C, M, Y, light M2, and light C2 using the nozzles 10K, 10C, 10M, 10Y, 10M2, and 10C2. On the other hand, when the recording head 10 performs recording scanning in the backward direction of the arrow X2, the nozzles 10Y, 10M, 10C, 10M1, 10C1, and 10K are used, and ink is applied in the order of Y, M, C, light M1, light C1, and K. To do. In this way, by not applying the light ink first in any of the reciprocating scans, it is possible to suppress the occurrence of a color difference due to a change in ink absorbability. Further, the order of application of light M (M1, M2) ink and light C (C1, C2) ink is delayed, and light M (M1, M2) ink is applied after M ink, and light C (C1, C2) is applied. ) Ink is applied after C ink.

  The light M ink discharge nozzles 10M1 and 10M2 and the light C ink discharge nozzles 19C1 and 10C2 do not necessarily have to be symmetrically provided as in this example. At least by providing Y, M, and C inks symmetrically as in this example, chromatic secondary colors and tertiary colors can be reproduced well, and the black portion of the image is made up of K ink. There is no problem in the image by almost replacing it with a single color. This is also due to the fact that the black color is so dark that fine ink overflows are not visually noticeable.

  By arranging the nozzles as in this example, it is possible to make it difficult for color differences to occur even when the recorded image is divided into areas 0, 1, and 2 as in the above-described embodiment.

(Fifth embodiment)
If there is no difference in absorbability with respect to the recording medium depending on the ink, or if there is no significant problem even if there is a difference, the ink that is used the most frequently among the multiple inks used is ejected. A plurality of nozzle rows may be provided. Thereby, the usage frequency of the several ink to be used can be equalize | homogenized. For example, it is assumed that inks of six colors of K, light C, light M, C, M, and Y are used, and light ink (light Y) is not used for Y ink. In this case, when a normal natural image is recorded, that is, when a uniform image or various images are recorded and the amount of C, M, and Y ink used is averaged, the amount of Y ink is increased. Consumption will increase and it will be the earliest. In such a case, the use amount of a plurality of inks to be used can be equalized by providing two sets of Y ink ejection nozzle rows. In this case, among the two sets of nozzle arrays for Y ink ejection, Y ink ejected from one is Y1 ink, Y ink ejected from the other is Y2 ink, Y1, light C, C, K, M, The nozzle rows for discharging light M and Y2 inks may be arranged in the main scanning direction in that order. In this case, the nozzle row for Y1 ink ejection and the nozzle row for Y2 ink ejection have symmetry in the main scanning direction, and Y ink is applied first in the reciprocating scanning. The color difference of the backward-scanned recorded image can be further reduced.

  Further, by arranging the nozzles as in this example, it is possible to make it difficult for color differences to occur even when the recorded image is divided into 0, 1, and 2 regions, as in the above-described embodiment.

(Other embodiments)
The recording apparatus of the present invention can constitute a recording system together with a host device such as a personal computer. In this case, at least a part of the control function of the recording apparatus can be provided in the host device. 3 may be provided on the recording apparatus 50 side, and conversely, at least a part of the functions on the recording apparatus 50 side may be provided on the host apparatus 200 side. May be. Further, the function for setting the recording ratio can be exhibited by a program that can be executed by the recording device or the host device, and such a program can be stored in a computer-readable storage medium. it can.

  The present invention is not limited to the bidirectional 8-pass printing method described above, and can be widely applied to a so-called bidirectional multi-pass printing method such as a bidirectional 2-pass printing method. According to the present invention, a recording ratio is set according to the scanning position of the recording head and recording is performed according to the recording ratio in at least one scanning among a plurality of scannings of the recording head with respect to a predetermined recording area. The area may be limited. The effects of the present invention described above can be obtained to some extent even in such a configuration.

1 is a schematic perspective view of an ink jet recording apparatus to which the present invention can be applied. FIG. 3 is a schematic block configuration diagram of a control system in the ink jet recording apparatus of FIG. 2. FIG. 3 is a basic block configuration diagram of an image data processing system in the ink jet recording apparatus of FIG. 2. FIG. 6 is an explanatory diagram of an example of a multi-scan recording operation according to the first embodiment of the present invention. FIG. 5 is an explanatory diagram of a processing procedure of image data during the recording operation of FIG. 4. It is explanatory drawing of the recording ratio set by the image data process of FIG. It is explanatory drawing of the process sequence of the image data in the 2nd Embodiment of this invention. It is explanatory drawing of the recording ratio set by the image data process of FIG. It is explanatory drawing of the recording ratio in the 3rd Embodiment of this invention. It is explanatory drawing of the recording head used in the 4th Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Recording head 10K Nozzle row for discharging black ink 10C Nozzle row for discharging cyan ink 10M Nozzle row for discharging magenta ink 10Y Nozzle row for discharging yellow ink 10C1 First nozzle row for discharging light cyan ink 10C2 Light cyan ink Second nozzle row for ejection 10M1 First nozzle row for ejection of light magenta ink 10M2 Second nozzle row for ejection of light magenta ink X Main scanning direction X1 Forward direction X2 Reverse direction Y Sub-scanning direction P Recording medium

Claims (8)

Inkjet recording that records an image corresponding to image data in the recording area by reciprocally scanning a recording head capable of ejecting ink from a plurality of nozzles in a main scanning direction on a predetermined recording area of the recording medium In the device
Recording of the first area from the forward scanning start position side of the recording head to a predetermined first position in the middle of the recording area is allowed, and the downstream area from the first position in the forward scanning direction. The first recording by the forward scanning based on the recording data obtained by the first mask that divides the image data so as not to allow the recording, and the middle of the recording area from the backward scanning start position side of the recording head Dividing the image data so as to allow recording in a second area up to a predetermined second position and not allow recording in a downstream area from the second position in the backward scanning direction; and An inkjet recording apparatus that performs second recording by backward scanning based on recording data obtained by a second mask having a complementary relationship with the first mask. In the vicinity of the start position of at least one of the reciprocating scans, a recovery processing unit for performing recovery processing of the recording head is provided,
2. The ink jet recording apparatus according to claim 1, wherein the recording ratio is set to be smaller as the recording head advances from the scanning start position in the scanning direction. The plurality of nozzles form a nozzle row along a sub-scanning direction intersecting the main scanning direction,
The inkjet recording apparatus according to claim 1, wherein the first and second masks thin out the image data corresponding to each of the plurality of nozzles.   The inkjet recording apparatus according to claim 3, wherein the first and second masks correspond to a size obtained by dividing the nozzle row into a plurality of blocks. The plurality of nozzles form a plurality of nozzle rows along the sub-scanning direction intersecting the main scanning direction so as to correspond to different inks,
At least one of the nozzle row corresponding to a particular ink jet recording apparatus according to any one of 4 claims 1, wherein a plurality equipped. The specific ink is any one of cyan ink, magenta ink, or yellow ink,
6. The inkjet recording apparatus according to claim 5 , wherein at least one nozzle row corresponding to another ink excluding the specific ink is located between the plurality of nozzle rows corresponding to the specific ink. Inkjet recording that records an image corresponding to image data in the recording area by reciprocally scanning a recording head capable of ejecting ink from a plurality of nozzles in a main scanning direction on a predetermined recording area of the recording medium In the method
Recording of the first area from the forward scanning start position side of the recording head to a predetermined first position in the middle of the recording area is allowed, and the downstream area from the first position in the forward scanning direction. The first recording by the forward scanning based on the recording data obtained by the first mask that divides the image data so as not to allow the recording, and the middle of the recording area from the backward scanning start position side of the recording head Dividing the image data so as to allow recording in a second area up to a predetermined second position and not allow recording in a downstream area from the second position in the backward scanning direction; and 2. An ink jet recording method comprising: performing second recording by backward scanning based on recording data obtained by a second mask having a complementary relationship with the first mask. A recording head capable of ejecting ink from a plurality of nozzles is reciprocated in the main scanning direction on a predetermined recording area of the recording medium to record an image corresponding to image data in the recording area. A program,
Recording of the first area from the forward scanning start position side of the recording head to a predetermined first position in the middle of the recording area is allowed, and the downstream area from the first position in the forward scanning direction. The first recording by the forward scanning based on the recording data obtained by the first mask that divides the image data so as not to allow the recording, and the middle of the recording area from the backward scanning start position side of the recording head Dividing the image data so as to allow recording in a second area up to a predetermined second position and not allow recording in a downstream area from the second position in the backward scanning direction; and A program for causing a computer to execute a step of performing second printing by backward scanning based on print data obtained by a second mask having a complementary relationship with the first mask.

Images