JP2004082624A - Ink jet recording apparatus and control method of the apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable good image recording by preventing color irregularities because of a difference of recording times when recording of a predetermined image region is carried out bidirectionally in a sequence of reciprocation in an ink jet printer which carries out recording of the predetermined image region on the basis of recording data while an ink jet recording head is scanned in two ways over a record medium. <P>SOLUTION: The recording time difference varies by a recording position when an image recording region is recorded by a two pass printing mode at a first half way and a second half way in a scanning direction. Color irregularities brought about by the recording time difference are prevented by using a printing mask which changes a recording amount to be recorded at the first half way and the second half way in accordance with the recording position. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an ink jet recording apparatus that performs recording by ejecting ink while performing recording in a recording head having a nozzle array in a paper transport direction in a direction crossing the paper transport direction in both directions. More particularly, the present invention relates to an ink jet recording apparatus that completes an image and a method of controlling the same, and more specifically, to prevention of color unevenness caused by a difference in recording time.
[0002]
[Prior art]
2. Description of the Related Art In recent years, with the spread of personal computers, digital cameras, and the like, recording devices, such as printers for recording digital images, have been improved in definition. Among the recording apparatuses, an ink jet recording apparatus using an ink jet type recording head is rapidly spreading, and a device which realizes a high-definition image and is inexpensive is demanded.
In the ink jet recording apparatus, a recording head in which a plurality of recording elements are integrated and used is used to improve a recording speed. Further, a color printer generally includes a plurality of recording heads for discharging inks of different colors.
[0003]
FIG. 1 shows a configuration of a main part of an apparatus for performing recording on a paper surface using the recording head.
[0004]
In FIG. 1, reference numeral 101 denotes an ink jet cartridge. These are composed of ink tanks storing four color inks, that is, black, cyan, magenta, and yellow inks, and recording heads 102 corresponding to the respective inks.
[0005]
In this recording head, n ejection ports are arranged on each recording head 102 at an N pixel density per inch (Ndpi). Reference numeral 103 denotes a paper feed roller which rotates in the direction of the arrow in the figure while holding the print paper P together with the auxiliary roller 104, and conveys the print paper P in the y direction (paper feed direction) as needed.
[0006]
A pair of paper feed rollers 105 feeds print paper. Reference numeral 106 denotes a carriage that supports the four ink jet cartridges 101 and performs scanning of the cartridges together with printing. The carriage 106 waits at the home position h at the position shown by the broken line in the drawing when printing is not being performed or when the recording head 102 performs recovery processing or the like.
[0007]
When a print start command is issued, the carriage 106 at the home position h before the start of printing moves in the x direction (print head scanning direction), and is arranged at a density of N pieces per inch of the print head 102. Printing with a width of n / N inches is performed on the paper by the nozzles. When printing to the end of the sheet is completed, the carriage returns to the original home position, and moves again for printing in the x direction.
[0008]
Before the second printing starts after the first printing is completed, the paper feeding roller 103 rotates in the direction of the arrow to feed the paper in the y-direction by the width of n / N inches. In this manner, by repeatedly performing printing of the n / N inch width and paper feeding by the recording head 102 for each main scan of the carriage 106, printing of, for example, one page can be completed. Note that such a print mode is hereinafter referred to as a one-pass print mode.
[0009]
In the one-pass print mode, although the image recording speed is high, there is a disadvantage that the image quality greatly depends on the landing accuracy of each nozzle. Therefore, there is a multi-pass printing mode as a printing mode in which the image recording speed can be maintained more stably without depending on the landing accuracy of the nozzles than the one-pass printing mode, although the image printing speed is lowered. The multi-pass print mode is a print mode in which printing is completed by overprinting a print area in a plurality of times. The multi-pass print mode will be described in detail. When a print start command is issued, the carriage 106 at the home position h before printing starts performs printing on the paper with a width of n / N inches while moving in the x direction. If the overprinting is performed in M times, the dots to be printed by scanning at this time are obtained by thinning specified image data to 1 / M in a predetermined pattern. When printing to the end of the paper surface is completed, the carriage returns to the original home position and moves again for printing in the x direction.
[0010]
Before the end of the first printing and before the second printing starts, the paper feed roller 103 rotates in the direction of the arrow to feed the paper in the y direction by a width of n / (M × N) inches. Then, in the M-th scan, printing is performed according to each mask pattern, thereby completing the image. Hereinafter, the multi-pass print mode using M overprints is also referred to as an M-pass print mode.
[0011]
FIG. 2 shows a two-pass mask pattern used in the two-pass print mode (M = 2). In FIG. 2, reference numeral 201 denotes a first pass mask pattern, and reference numeral 202 denotes a second pass mask pattern.
[0012]
Reference numerals 201 and 202 denote 4 × 4 print masks, each of which corresponds to one pixel. This mask data is stored in the main memory as binary data of 1 for black pixels and 0 for white pixels. By performing AND (logical product) with the image data in each pass, a pixel (data 1) to be printed is determined, and printing in each pass is performed.
[0013]
The first-pass mask pattern 201 and the second-pass mask pattern 202 are staggered mask patterns, and the first-pass mask pattern 201 and the second-pass mask pattern 202 are both interpolated (the first-pass mask pattern 202 and the second-pass mask pattern 202). If printing is performed twice using the mask pattern of the second pass, the entire print area can be printed, so that print data is not lost.) In addition to the mask pattern shown in FIG. 2, a mask pattern in which the print density in each pass is １ ／ is usually used for both the one-pass and two-pass mask patterns.
[Problems to be solved by the invention]
However, in the two-pass print mode using the above mask, the difference between the time recorded in the first pass and the time recorded in the second pass differs depending on the print area, so that the absorption of ink into the recording medium is reduced. As a result, there is a problem that unevenness in recording density (hereinafter, referred to as “time difference unevenness”) occurs, thereby deteriorating image quality.
[0014]
Hereinafter, the reason why the time difference unevenness occurs depending on the printing area will be described in detail.
[0015]
FIG. 3 shows a schematic diagram of the nozzle arrangement of the recording head. Reference numeral 301 denotes a nozzle. The recording head has n nozzles arranged in the y direction (paper feed direction) at Ndpi intervals.
[0016]
FIG. 4A is a schematic diagram of a two-pass bidirectional print mode when the print head of FIG. 3 and the print mask of FIG. 2 are used. The paper feed is in the Y direction in the figure. First, in order to print the first pass of the image area 401, paper feeding is performed so that the recording head is at the position 403 with respect to the image.
[0017]
The recording head 403 ejects ink while scanning in the direction of the arrow to perform printing of the first pass in the 401 area. At this time, the mask pattern 201 is ANDed with the image of the area 401. Next, paper feeding is performed, and the recording head moves to the position of 404, and simultaneously performs printing of the second pass of 401 and printing of the first pass of 402 while moving in the direction of the arrow.
[0018]
At this time, the mask pattern 202 and the mask pattern 201 are AND-ed with the image of the area 401 and the image of the area 402, respectively. Thus, the image of the image area 401 is completed. By repeating such an operation, the area 402 is also completed. At this time, the time difference between the first pass and the second pass is as shown in FIG. 4B depending on the image area.
[0019]
The horizontal axis indicates the position of the image in the X direction (perpendicular to the Y direction in FIG. 4A). The vertical axis is the time difference between the first pass and the second pass. It can be seen that there is a difference in the time difference between the first pass and the second pass in the printing areas 401 and 402 depending on the position in the X direction. Particularly, the difference is large between the left end and the right end of the image area.
[0020]
This time difference causes a difference in recording density, resulting in a time difference unevenness (a difference in recording density caused by a difference in recording time). Thus, Japanese Patent Application Laid-Open No. 6-240007 proposes a recording method effective for time difference unevenness. However, in the case of an image having a different image width for each scan, it cannot be said that it is sufficient as a measure against time difference unevenness. Further, since the paper feed is indefinite and not in a fixed direction, the control of the paper feed is more complicated than in the present invention.
[0021]
The present invention has been made to solve the above-described problems of the related art as a starting point, and an object of the present invention is to bidirectionally scan an ink jet recording head which performs recording by discharging ink on a recording medium. In an ink-jet printing apparatus that prints a predetermined image area based on print data, when printing this predetermined image area in a series of two-way reciprocation, color unevenness (time difference) caused by a difference in printing density caused by a difference in printing time. An object of the present invention is to provide an ink jet recording apparatus capable of preventing occurrence of unevenness and performing good image recording and a control method thereof.
[0022]
[Means for Solving the Problems]
In order to achieve the above object, a multi-pass printing method according to an embodiment of the present invention has the following configuration. That is, an ink jet recording apparatus that records a predetermined image area based on recording data input while scanning an ink jet recording head that ejects ink and performs recording on a recording medium in a bidirectional manner. When recording the predetermined image area in the direction, the recording ratio is set so as to increase the recording rate for recording from the scanning start position to the scanning end position with respect to the direction in which the predetermined image area is recorded first. A recording ratio setting unit that sets a complementary recording ratio of the recording ratio in a direction opposite to the first recording direction; and a recording ratio setting unit that sets the predetermined image area based on the recording ratio set by the recording ratio setting unit. Recording means for performing recording.
[0023]
Here, for example, it is preferable that the recording ratio is determined according to a recording time difference between the first recording time and the reverse recording time.
[0024]
Here, for example, it is preferable that the recording ratio setting means has a print mask pattern corresponding to the recording ratio.
[0025]
Here, for example, the print mask pattern preferably has a maximum width of an image that can be printed in the scanning direction.
[0026]
Here, for example, it is preferable that the recording ratio increases as the recording time difference increases.
[0027]
Here, for example, the first recording direction is preferably the bidirectional outward or return path.
[0028]
Here, for example, it is preferable that the predetermined image area is divided into a plurality of blocks having a predetermined number of pixels in the scanning direction of the recording medium, and the recording ratio is set for each of the blocks.
[0029]
Here, for example, it is preferable that the recording ratio changes according to the input recording data.
[0030]
Here, for example, it is preferable that the recording head is a recording head that discharges ink using thermal energy, and includes a thermal energy converter for generating thermal energy to be applied to the ink.
[0031]
A control method according to an embodiment of the present invention for achieving the above object has the following configuration. That is, a method of controlling an ink jet recording apparatus for recording a predetermined image area based on input recording data while scanning an ink jet recording head that performs recording by ejecting ink bidirectionally on a recording medium. When recording the predetermined image area in the reciprocating two-way direction, the recording ratio is increased so that the recording ratio for recording from the scanning start position to the scanning end position with respect to the direction in which the predetermined image area is first recorded is increased. A recording ratio setting step of setting a complementary recording ratio of the recording ratio in a direction opposite to the first recording direction, and the recording ratio set in the recording ratio setting step. Recording a predetermined image area.
[0032]
A control program according to an embodiment of the present invention for achieving the above object has the following configuration. That is, a control program for controlling an inkjet printing apparatus that prints a predetermined image area based on print data input while bidirectionally scanning an inkjet print head that performs printing by discharging ink on a print medium. When printing the predetermined image area in a series of reciprocating bidirectional directions, the printing ratio for printing from the scan start position to the scan end position with respect to the direction in which the predetermined image area is first printed is increased. A recording ratio setting step of setting a recording ratio, and setting a complementary recording ratio of the recording ratio in a direction opposite to the first recording direction; and a recording ratio set in the recording ratio setting step. And a recording step of recording the predetermined image area.
[0033]
A computer-readable storage medium according to an embodiment of the present invention for achieving the above object has the following configuration. That is, a control program for controlling an inkjet printing apparatus that prints a predetermined image area based on print data input while bidirectionally scanning an inkjet printhead that performs printing by discharging ink is stored. A computer-readable storage medium, wherein the control program is configured such that when recording the predetermined image area in a reciprocating two-way sequence, a scan start position to a scan end position with respect to a direction in which the predetermined image area is first recorded. A recording ratio setting step of setting a recording ratio so as to increase the recording ratio for performing recording toward the first recording direction, and setting a complementary recording ratio of the recording ratio in a direction opposite to the first recording direction; A recording step of recording the predetermined image area based on a recording ratio set in the recording ratio setting step.
[0034]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an image recording apparatus according to an embodiment of the present invention will be described with reference to the drawings.
[0035]
However, in the present embodiment, an ink-jet printer using an ink-jet recording method is taken as an example of an image recording device, and a personal computer (hereinafter referred to as a personal computer) is taken as an example of a higher-level device that transmits image recording data to the image recording device. Although described, it is not intended to limit the scope of the present invention to the described examples.
[0036]
In this specification, “recording” (sometimes referred to as “drawing” or “printing”) refers not only to the formation of significant information such as characters and figures, but also to human perception, whether significant or insignificant. Regardless of whether or not the image has been exposed, the case where an image, a pattern, a pattern, or the like is widely formed on a recording medium or the medium is processed is also shown.
[0037]
In addition, the term “recording medium” refers not only to paper used in general recording devices but also to a wide range of materials that can accept ink, such as cloth, plastic films, metal plates, glass, ceramics, wood, and leather. Shall be.
[0038]
Further, “ink” (sometimes referred to as “liquid”) is to be widely interpreted similarly to the definition of “recording (drawing)”, and is applied to a recording medium to form an image, A liquid that can be used for forming a pattern, processing a recording medium, or processing ink (for example, coagulation or insolubilization of a colorant in ink applied to a recording medium).
[0039]
<First embodiment>
Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings.
[0040]
The mechanical configuration of the ink jet recording apparatus 100 according to the present embodiment is the same as that shown in FIG.
[0041]
[Control configuration of inkjet recording apparatus: FIG. 5]
FIG. 5 is a block diagram showing a control configuration of the inkjet recording apparatus 100 according to one embodiment of the present invention.
[0042]
In FIG. 5, a CPU 500 controls each unit of the apparatus and executes data processing via a main bus line 505. That is, the CPU 500 controls data processing, head driving, and carriage driving described in FIG. 5 and thereafter through the following units according to a program stored in the ROM 501. The RAM 502 is used as a work area for data processing and the like by the CPU 500. These memories include a hard disk and the like. The image input unit 503 has an interface with the host device, and temporarily holds an image input from the host device. The image signal processing unit 504 executes data processing shown in FIG. 5 and subsequent figures in addition to color conversion and binarization.
[0043]
The operation unit 506 includes keys and the like, thereby enabling control input and the like by the operator. The recovery system control circuit 507 controls a recovery operation such as preliminary ejection in accordance with a recovery processing program stored in the RAM 502. That is, the recovery system motor 508 drives the recording head 513, the cleaning blade 509, the cap 510, and the suction pump 511 that are opposed to and separate from the recording head 513. The head drive control circuit 515 controls the driving of the electrothermal transducer for ink ejection of the recording head 513, and usually causes the recording head 513 to perform preliminary ejection and ink ejection for recording. Further, the carriage drive control circuit 516 and the paper feed control circuit 517 similarly control the movement of the carriage and the paper feed, respectively, according to the program.
[0044]
[Recording head: Fig. 6]
FIG. 6 shows an outline of a print head 600 having 256 nozzles (print elements) as an example of a print head used in the present embodiment. The nozzle rows 602, 603, and 604 in which 256 nozzles 601 are arranged in the Y direction (paper feed direction) at a pitch of 600 dpi are arranged in parallel in the direction (X direction) orthogonal to the three-row paper feed. From each nozzle, a 10 pl ink droplet is ejected by driving an ink ejection electrothermal transducer provided for each nozzle. Cyan ink is ejected from the nozzle row 602, magenta ink is ejected from the nozzle row 603, and cyan ink is ejected from the nozzle row 604.
[0045]
[Image pattern: Fig. 7]
FIG. 7 shows an image pattern used in the present embodiment. This is a solid pattern (all data is 1) of blue (printing using all nozzles, 100% duty for both cyan ink and magenta ink) of 4800 pixels in the horizontal direction (printing head scanning direction) × 256 pixels in the vertical direction (paper feeding direction).
[0046]
[Recording operation of 2-pass bidirectional printing: FIG. 8]
(1) When using a 50% duty print mask
First, a printing operation when two-pass bidirectional printing is performed using the print masks (50% Duty: mask 50% of the print area) 201 and 202 in FIG. 2 will be described with reference to FIG. The effect of using a print mask is exactly the same, but differs from that described in "Prior Art" for simplicity of explanation.
[0047]
In the present embodiment, in order to prevent density unevenness due to factors other than the time difference unevenness (unevenness due to a difference in the order of printing colors on the printing medium), when printing while scanning in the positive X-axis direction, the nozzle arrays 603 and 604 are used. When printing is performed while scanning in the negative direction of the X-axis, the nozzle arrays 602 and 603 are used. That is, even if printing is performed while scanning in either direction, the recording is performed in the order of cyan → magenta, so that unevenness due to the difference in the order of recording colors on the recording medium does not occur.
[0048]
In FIG. 8, the print image is divided into eight equal regions in the X direction (print head scanning direction), and these regions are respectively 804 to 811. Also, the upper and lower pixels are divided into 128 pixels each in the Y direction (recording medium transport direction) to form an A region and a B region. The print head is divided into upper 128 nozzles and lower 128 nozzles, and each nozzle group is defined as a and b. That is, the image positions in the X direction of the A region 804 to 811 are A-804 to A-811, and the image positions in the X direction of the B region 804 to 811 are B-804 to B-811.
[0049]
[First scan: recording of first pass of area A]
In the first scan, after the image of the area A is ANDed with the print mask 201 (partially masking the image of the area A with the print mask 201) to generate a print image, the image is scanned from the position 801 in the positive X direction. , B group nozzles are driven to perform the first pass printing in the area A. Next, the paper is fed in the positive Y direction for 128 pixels, and the position of the recording head is moved to 802 with respect to the image area.
[0050]
[Second scan: second pass printing in area A + first pass printing in area B]
In the second scan, after the image of the area A and the print mask 202 and the image of the area B and the print mask 202 are ANDed to generate an image of each area, the head is scanned from the position 802 in the negative X direction. , A group perform the second pass printing of the A area, and at the same time, perform the first pass printing of the B area in the b group. Further, the paper is fed by 128 pixels, and the position of the recording head is moved to 803 with respect to the image area.
[0051]
[Third scan: recording of the second pass in area B]
In the third scan, after the image of the area B and the print mask 201 are ANDed to generate a recording image, the second pass of the area B is printed with a while scanning in the positive direction from the position 803, and the image is printed. Complete.
[0052]
[Time difference T1, T2]
Here, the luminance L at the image position A-804 to A-811 in the X direction of the area A (total of 8 points) and the image position B-804 to B-811 in the X direction of the area B (total of 8 points) is shown. ^* Is shown in FIG. 9 (a).
[0053]
The time difference between the first pass and the second pass at the center of each measurement position in the image position in the X direction of the area A is T1, the time difference between the first pass and the second pass at the center of each measurement position in the image position of the area B in the X direction is X. Assuming that the time difference of the pass is T2, the time difference T1 and the time difference T2 are as follows.
[0054]
Time difference T1
A-804: 1.10 sec, A-805: 0.98 sec, A-806: 0.86 sec, A-807: 0.74 sec, A-808: 0.62 sec, A-809: 0 .50 seconds, A-810: 0.38 seconds, A-811: 0.26 seconds,
Time difference T2
B-804: 0.26 sec, B-805: 0.38 sec, B-806: 0.50 sec, B-807: 0.62 sec, B-808: 0.74 sec, B-809: 0 .86 sec, B-810: 0.98 sec, B-811: 1.10 sec.
[0055]
Further, FIG. 9B shows the result of a subjective evaluation on the time difference unevenness (difference in recording density caused by the difference in recording time) in each of the areas 804 to 811. Areas below the OK level line are areas where color unevenness is not felt (807 to 808 in FIG. 9B), and areas above the OK level line are areas where density unevenness is felt.
[0056]
Here, the regions 807 to 808 in FIG. 9B correspond to the luminance L in FIG. ^* Are areas that are almost the same. That is, from FIG. 9A and FIG. 9B, the luminance L of the A region and the B region is shown. ^* It is determined that a time difference non-uniformity occurs when a difference appears.
[0057]
Therefore, according to the printing method using the mask patterns 201 and 202 (50% duty each) shown in FIG. 2, the densities of the A region and the B region other than the regions (807, 808) where the time difference between the first pass and the second pass are almost the same. Unevenness occurs.
[0058]
(2) When using print masks of 62.5% and 37.5% duty
Next, the same two-pass reciprocal printing was performed by changing the print mask to the mask shown in FIG. A mask of 1001 was used instead of the mask of 201, and a mask of 1002 was used instead of the mask of 202. The mask of 1001 is 62.5%, and the mask of 1002 is 37.5%.
[0059]
FIG. 11A shows the luminance L at that time. ^* FIG. 11B shows the result of the subjective evaluation of the time difference unevenness. According to FIG. 11B, it can be seen that the region where the unevenness is not recognized shifts from the region 807 to 808 in FIG. 9B to the region 808 to 809.
[0060]
In other words, it is considered that by changing the recording duty of the first pass and the second pass (50 → 62.5%), the time difference unevenness of the first pass and the second pass of the A region and the B region can be eliminated.
[0061]
(3) When using print masks of 75% and 25% duty
Similarly, a 75% mask was used instead of the 201 mask, and a 25% mask was used instead of the 202 mask. FIG. 12 shows the result of the subjective evaluation of the time difference unevenness. It can be seen that the point at which the time difference unevenness shown in FIG. 11B is eliminated (the area 808 to 809) has shifted to the area 810 to 811 in FIG.
[0062]
[Relationship between time difference and mask duty for eliminating time difference unevenness: FIG. 13]
FIG. 13 is a diagram summarizing the relationship between the time differences T1 and T2 at the center of the measurement position and the mask Duty for eliminating the time difference unevenness. The time difference between the first pass and the second pass in each of the divided areas of the region A and the region B is shown in the upper part, and the mask duty of the first pass → the mask Duty of the second pass is shown in the lower part.
[0063]
[High-quality image without time difference unevenness: FIG. 14]
The following describes the result of recording in the same manner as described above using the mask shown in FIG. 14 of 4800 pixels in width based on the data in FIG.
[0064]
The mask (M1) in the first pass includes a mask duty 25% in the area a, a mask duty 37.5% in the area b, a mask duty 50% in the area c, a mask duty 50% in the area d, a mask duty 62.5% in the area e, f A mask having a mask duty of 75% is used in the area, and the mask (M2) in the second pass is a complementary mask of the mask in the first pass. The mask duty is 75% in the a ′ area, the mask duty is 62.5% in the b ′ area, A mask duty of 50% is used in the c 'area, a mask duty of 50% is used in the d' area, a mask duty is 37.5% in the e 'area, and a mask duty is 25% in the f' area.
[0065]
These two M1 and M2 masks are used alternately for each scan. That is, in FIG. 8, in the first scan, an image obtained by ANDing M1 with the area A of the image is recorded in the area 801b. In the second scan, an image obtained by ANDing M2 on the A and B areas of the image is recorded in the 802 a and b areas. In the third scan, an image obtained by ANDing M1 with the area B of the image is recorded in the area a 803.
[0066]
As described above, as a result of performing two-pass bidirectional printing using an ink jet printing apparatus using the above-described masks M1 and M2, unevenness in time difference (a difference in printing density caused by a difference in printing time) conventionally occurred. Was eliminated, and a high-quality image without time difference unevenness could be recorded.
[0067]
The mask Duty of the two M1 and M2 masks described with reference to FIG. 14 is an example, and changes when the time differences T1 and T2 change depending on the configuration of the inkjet recording apparatus. May be prepared, and a device suitable for each device may be used. Also, a plurality of masks Duty are prepared according to the type of ink to be used, and a mask Duty suitable for each type of ink may be used. As described above, in the inkjet printing apparatus of the present embodiment, which performs printing in a predetermined image area based on print data while scanning the inkjet print head that performs printing by ejecting ink bidirectionally on a print medium, When printing this predetermined image area in both reciprocating directions, the printing ratio for printing from the scanning start position to the scanning end position in the direction in which this predetermined image area is printed first (forward or backward) is increased. The recording ratio is set in such a manner that the recording ratio is set to a predetermined value, and a complementary recording ratio of the recording ratio is set in a direction (return or forward) opposite to the first recording direction, and recording of a predetermined image area is performed based on the recording ratio. Is performed, color unevenness caused by a difference in recording time is eliminated, and a high-quality image can be recorded.
[0068]
<Second embodiment>
In the present embodiment, a print mask control that predicts a print time difference between the first pass and the second pass from the image and the recording operation by applying the first embodiment is performed. As a result, a high-quality image without time difference unevenness is achieved regardless of the image.
[0069]
[Print mask control: Fig. 15]
FIG. 15 shows a flowchart of this embodiment. This control is executed by the CPU 500 according to a control program stored in the ROM 501, and the RAM 502 is used as a work area for data processing and the like by the CPU 500.
[0070]
First, in step S1501, the width to be scanned (the width in the x direction) is detected.
[0071]
Next, the process advances to step S1502 to determine the recording scanning direction (first scanning direction (positive direction in x direction) or second scanning direction (negative direction in x direction) opposite to the first scanning direction). .
[0072]
Next, in step S1503, the use start point of the print mask is set based on the scan width (width in the x direction) obtained in steps S1501 and S1502 and the recording scan direction (first scan direction or second scan direction). Then, image recording using this print mask is executed.
[0073]
[Details of Recording Operation and Print Mask Control: FIGS. 16 to 18]
Hereinafter, the print mask control and the printing operation shown in FIG. 15 will be described in detail with reference to the drawings.
[0074]
FIG. 16 shows a print mask used in the present embodiment. It is formed of 4800 horizontal pixels × vertical (128 × 2) pixels. The mask duty% described in the figure is the duty of the print mask. a (25%) indicates that the mask Duty% of the region a is 25%. Hereinafter, the lower row, which is a complement of the upper row (a to e), is described as a ′ to e ′. For simplicity, the X axis is set with MP in the figure as the origin (0) of the coordinate axis. The unit is a pixel.
[0075]
[Image example: FIG. 17]
FIG. 17 shows an image used in the present embodiment. The band of the area A is 4800 pixels × 128 pixels vertically, and the areas B and C are 2400 pixels × 128 pixels vertically. For simplicity of description, the X axis and the Y axis are set with P in the figure as the origin (0, 0) of the coordinate axis. The unit is a pixel. It is assumed that all pixels are blue solid images composed of cyan and magenta. Note that the recording head (FIG. 6) and the ink colors (FIG. 7) ejected from each nozzle row are the same as those in the first embodiment, and the description thereof will not be repeated here.
[0076]
Details of the recording operation will be described with reference to FIG.
[0077]
[First scan: recording of the first pass of the area A]
In the first scan, an image is formed while scanning 4,800 pixels in the X positive direction from the head position D. At the end of the scan, the recording head moves to the position of E. Therefore, the scan width is 4800 pixels, and the scan direction is the X positive direction. Therefore, the use start point of the print mask becomes the X coordinate 0 (= 4800 (print mask width) -4800 (scan width)), and the mask is ANDed with respect to the recorded image. At this time, the mask is applied so that the scanning direction and the positive direction of the print mask X axis coincide. When the print image thus formed is printed, the printing of the first pass in the area A is completed. Next, paper feeding of 128 pixels is performed, and the recording head moves to the position of F.
[0078]
[Second scan: recording of the second pass of the area A + the first pass of the area B]
In the second scan, an image is formed while scanning 4,800 pixels from the head position F in the negative X direction. At the end of the scan, the recording head moves to the position G. Therefore, the scan width is 4800 pixels, and the scan direction is the X negative direction. For the area B, the use start point of the print mask is the X coordinate 0 (= 4800 (print mask width) −4800 (scan width)), and the mask is ANDed with respect to the recorded image. At this time, the mask is applied so that the scanning direction and the positive direction of the print mask X axis coincide. (In other words, instead of masking the print mask of FIG. 16 in the usual order of a → b → c → d → e, the print mask of FIG. 16 is turned over and e → d → c → b → a. Thus, when the generated recording image is recorded, printing of the first pass of the area B is performed. In the area A, an image that is complementary to the image recorded in the first scan is recorded, and the image is completed. Next, paper feeding of 128 pixels is performed, and the recording head moves to the H position.
[0079]
[Third scan: second pass of B area + first pass of C area]
In the third scan, an image is formed while scanning 2,400 pixels from the head position H in the positive X direction. At the end of the scan, the recording head moves to the position of I. Therefore, the scan width is 2400 pixels, and the scan direction is the X positive direction. For the area C, the use start point of the print mask is the X coordinate 2400 (= 4800 (print mask width) −2400 (scan width)), and the mask is ANDed with the print image. At this time, the mask is applied so that the scanning direction and the positive direction of the print mask X axis coincide. As a result, the generated recording image is recorded, and the first pass of the C area is printed. In the area B, an image complementary to the image recorded in the second scan is recorded to complete the image. Next, paper feeding of 128 pixels is performed, and the recording head moves to the position of J.
[0080]
[Fourth scan: recording of the second pass in the C area]
In the fourth scan, an image is formed while scanning 2,400 pixels in the negative X direction from the head position J. At the end of the scan, the recording head moves to the position K. Therefore, the scan width is 2400 pixels, and the scan direction is the X negative direction. The area C records an image that is complementary to the image recorded in the third scan, and completes the image.
[0081]
[Relationship between time difference and mask duty for eliminating time difference unevenness: FIG. 19]
FIG. 19 shows the time difference T1 or T2 (upper row) of the first pass and the second pass at the center of each area in the A area, the B area, and the C area, and the mask Duty of the first pass → the mask Duty of the second pass (lower row). Show the relationship.
[0082]
By performing print mask control for estimating the print time difference between the first pass and the second pass shown in FIG. 19 on the image (A + B + C area) shown in FIG. 17, high-quality images with no time difference unevenness can be obtained regardless of the image. Images could be achieved.
[0083]
The inks used in the first and second embodiments are shown below.
[0084]
Cyan ink
・ Projet Fast Cyan 2 (Zeneca) 2.5 copies
・ Diethylene glycol 10 parts
・ Sodium hydroxide 0.2 parts
・ Acetylene glycol ethylene oxide adduct 1.0 part
(Product name: Acetyleneol EH, manufactured by Kawaken Fine Chemical)
・ 84.5 parts of water
Magenta ink
・ Projet Fast Magenta 2 (Zeneca) 3 copies
・ Diethylene glycol 10 parts
・ Lithium hydroxide 0.2 parts
・ Acetylene glycol ethylene oxide adduct 1.0 part
(Product name: Acetyleneol EH, manufactured by Kawaken Fine Chemical)
・ 85.8 parts of water
Note that a typical configuration and principle of the ink jet printer of the present embodiment is preferably performed using the basic principle disclosed in, for example, US Pat. Nos. 4,723,129 and 4,740,796. This method can be applied to both the so-called on-demand type and the continuous type. In particular, in the case of the on-demand type, it corresponds to a sheet or a liquid path holding a liquid (ink). By applying at least one drive signal corresponding to the information to be recorded and providing a rapid temperature rise exceeding nucleate boiling to the arranged electrothermal transducer, heat energy is generated in the electrothermal transducer and the recording is performed. This is effective because film boiling occurs on the heat-acting surface of the head, and as a result, bubbles in the liquid (ink) corresponding to this drive signal on a one-to-one basis are formed.
[0085]
By discharging the liquid (ink) through the discharge opening by the growth and contraction of the bubble, at least one droplet is formed. When the drive signal is in a pulse shape, the growth and shrinkage of the bubble are performed immediately and appropriately, so that the ejection of liquid (ink) having particularly excellent responsiveness can be achieved, which is more preferable.
[0086]
As the pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable. Further, if the conditions described in US Pat. No. 4,313,124 of the invention relating to the temperature rise rate of the heat acting surface are adopted, more excellent recording can be performed.
[0087]
As the configuration of the recording head, in addition to the combination of the discharge port, the liquid path, and the electrothermal converter (the linear liquid flow path or the right-angled liquid flow path) as disclosed in each of the above-mentioned specifications, a heat acting surface The configurations described in U.S. Pat. No. 4,558,333 and U.S. Pat. No. 4,459,600, which disclose the configuration in which the is bent, are also included in the present invention. In addition, Japanese Unexamined Patent Publication No. 59-123670 discloses a configuration in which a common slot is used as a discharge portion of an electrothermal converter for a plurality of electrothermal converters, or an opening for absorbing a pressure wave of thermal energy is discharged. A configuration based on JP-A-59-138461, which discloses a configuration corresponding to each unit, may be adopted.
[0088]
In addition, not only the cartridge-type recording head in which the ink tank is provided integrally with the recording head itself described in the above embodiment, but also the electric connection with the apparatus main body by being attached to the apparatus main body. A replaceable chip-type recording head that can supply ink from the apparatus main body may be used.
[0089]
Further, it is preferable to add recovery means for the printhead, preliminary auxiliary means, and the like to the configuration of the printing apparatus described above, since the printing operation can be further stabilized. Specific examples thereof include capping means for the recording head, cleaning means, pressurizing or sucking means, preheating means using an electrothermal transducer or another heating element or a combination thereof. It is also effective to provide a preliminary ejection mode for performing ejection that is different from printing, in order to perform stable printing.
[0090]
Further, the printing mode of the printing apparatus is not limited to a printing mode of only a mainstream color such as black, and may be a printing head integrally formed or a combination of a plurality of printing heads. The device may be provided with at least one of the full colors.
[0091]
In the above-described embodiment, the description has been made on the assumption that the ink is a liquid.However, even if the ink solidifies at room temperature or below, an ink that softens or liquefies at room temperature may be used. Alternatively, in the ink jet system, the temperature of the ink itself is controlled within a range of 30 ° C. or more and 70 ° C. or less to control the temperature so that the viscosity of the ink is in a stable ejection range. It is sufficient if the ink is sometimes in a liquid state.
[0092]
In addition, to prevent the temperature rise due to thermal energy from being used as the energy of the state change of the ink from the solid state to the liquid state, or to prevent the ink from evaporating, the ink solidifies in a standing state. Alternatively, ink that liquefies by heating may be used. In any case, the application of heat energy causes the ink to be liquefied by the application of the heat energy according to the recording signal and the liquid ink to be ejected, or to start solidifying when it reaches the recording medium. The present invention is also applicable to a case where an ink having a property of liquefying for the first time is used.
[0093]
In such a case, as described in JP-A-54-56847 or JP-A-60-71260, the ink is held in a liquid state or a solid state in the concave portion or through hole of the porous sheet. It is good also as a form which opposes an electrothermal transducer. In the present invention, the most effective one for each of the above-mentioned inks is to execute the above-mentioned film boiling method.
[0094]
[Other embodiments]
Further, an object of the present invention is to provide a storage medium storing a program code of software for realizing the functions of the above-described embodiments to a system or an apparatus, and a computer (or CPU or MPU) of the system or apparatus to store the storage medium. It is needless to say that the present invention can also be achieved by reading and executing the program code stored in the program. In this case, the program code itself read from the storage medium realizes the function of the above-described embodiment, and the storage medium storing the program code constitutes the present invention.
[0095]
As a storage medium for supplying the program code, for example, a floppy disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a CD-R, a magnetic tape, a nonvolatile memory card, a ROM, and the like can be used.
[0096]
When the computer executes the readout program code, not only the functions of the above-described embodiments are realized, but also an OS (Operating System) running on the computer based on the instruction of the program code. It goes without saying that a part or all of the actual processing is performed and the functions of the above-described embodiments are realized by the processing.
[0097]
Further, after the program code read from the storage medium is written into a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, the function expansion is performed based on the instruction of the program code. It goes without saying that a CPU or the like provided in the board or the function expansion unit performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.
[0098]
When the present invention is applied to the storage medium, the storage medium stores program codes corresponding to the above-described flowchart (shown in FIG. 15).
[0099]
【The invention's effect】
As described above, according to the present invention, there is provided an ink jet recording apparatus that records a predetermined image area based on print data while bidirectionally scanning an ink jet recording head that performs recording by discharging ink on a recording medium. When printing a predetermined image area in a series of reciprocating directions, color unevenness (time difference unevenness) due to a difference in printing density caused by a difference in printing time can be prevented, and good image printing can be performed. A simple inkjet recording apparatus and a control method thereof can be provided.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a main part of an ink jet recording apparatus using a recording head.
FIG. 2 shows mask patterns of a first pass and a second pass for a second pass.
FIG. 3 is a schematic diagram of a nozzle arrangement.
FIG. 4A is an explanatory diagram of two-pass bidirectional printing, and FIG. 4B is an explanatory diagram of time differences T1 and T2 in two-pass bidirectional printing.
FIG. 5 is a block diagram illustrating a control configuration of the inkjet recording apparatus.
FIG. 6 is a schematic diagram of a recording head used in the present embodiment.
FIG. 7 is a diagram illustrating a print pattern used in the first embodiment.
FIG. 8 is a diagram illustrating two-pass bidirectional printing according to the first embodiment.
9A is a luminance measurement result of the time difference unevenness when the mask of FIG. 2 is used in the first embodiment, and FIG. 9B is a subjective evaluation of the time difference unevenness when the mask of FIG. 2 is used in the first embodiment. It is a figure explaining a result.
FIG. 10 is a mask pattern for two passes used in the first embodiment.
11A is a luminance measurement result of the time difference unevenness when the mask of FIG. 11 is used in the first embodiment, and FIG. 11B is a subjective evaluation result of the time difference unevenness when the mask of FIG. 11 is used in the first embodiment. FIG.
FIG. 12 is a diagram illustrating a subjective evaluation result of time difference unevenness when another mask is used in the first embodiment.
FIG. 13 is a diagram illustrating a relationship between a recording time difference and a mask duty according to the first embodiment.
FIG. 14 is a diagram illustrating a mask pattern used in the first embodiment.
FIG. 15 is a flowchart illustrating print mask control processing according to the second embodiment.
FIG. 16 is a diagram illustrating a mask pattern used in the second embodiment.
FIG. 17 is an example of an image used in the second embodiment.
FIG. 18 is a diagram illustrating a printing operation according to the second embodiment.
FIG. 19 is a diagram illustrating a relationship between a recording time difference and a mask duty when recording the image of FIG. 17 in the second embodiment.
[Explanation of symbols]
101 ... CPU
102 ... ROM
103 ... RAM
104 Interface (I / F)
105: ASIC (inkjet printer control unit)
106 ... Interface control circuit
107: Data control circuit
108: Print data generation circuit
109 ... Head control circuit
110 ... Drive circuit control
111: Recording head
112 ... Carriage motor
113 ... Transport motor
201: Data processing unit
202: Print buffer control unit
203: Sequence control unit
204: boundary detection unit
205: overlapping data holding unit

Claims (12)

An inkjet printing apparatus that performs printing of a predetermined image area based on print data input while bidirectionally scanning an inkjet print head that performs printing by discharging ink on a printing medium,
When printing the predetermined image area in a series of reciprocating bidirectional printing, the printing is performed so as to increase the printing ratio of printing from the scan start position to the scan end position with respect to the direction in which the predetermined image area is printed first. Setting a ratio, a recording ratio setting means for setting a complementary recording ratio of the recording ratio in a direction opposite to the first recording direction,
Recording means for recording the predetermined image area based on a recording ratio set by the recording ratio setting means,
An ink jet recording apparatus comprising: The inkjet recording apparatus according to claim 1, wherein the recording ratio is determined according to a recording time difference between the first recording time and the reverse recording time. 2. The ink jet recording apparatus according to claim 1, wherein the recording ratio setting unit has a print mask pattern corresponding to the recording ratio. The ink jet recording apparatus according to claim 1, wherein the print mask pattern has a maximum width of an image that can be printed in the scanning direction. 3. The ink jet recording apparatus according to claim 2, wherein the recording ratio increases as the recording time difference increases. 2. The ink jet recording apparatus according to claim 1, wherein the first recording direction is the bidirectional outward or return path. 2. The ink-jet apparatus according to claim 1, wherein the predetermined image area is divided into a plurality of blocks having a predetermined number of pixels in a scanning direction of the recording medium, and the recording ratio is set for each of the blocks. Recording device. The inkjet recording apparatus according to claim 7, wherein the recording ratio changes according to the input recording data. 4. The recording head according to claim 1, wherein the recording head ejects ink by using thermal energy, and includes a thermal energy converter for generating thermal energy to be applied to the ink. 9. The ink jet recording apparatus according to any one of 8. A method for controlling an ink jet printing apparatus that performs printing of a predetermined image area based on print data input while scanning an ink jet print head that performs printing by ejecting ink bidirectionally on a print medium,
When printing the predetermined image area in a series of reciprocating bidirectional printing, the printing is performed so as to increase the printing ratio of printing from the scan start position to the scan end position with respect to the direction in which the predetermined image area is printed first. Setting a ratio, a recording ratio setting step of setting a complementary recording ratio of the recording ratio for a direction opposite to the first recording direction,
A recording step of recording the predetermined image area based on a recording ratio set in the recording ratio setting step,
A method for controlling an inkjet recording apparatus, comprising: A control program for controlling an inkjet printing apparatus that performs printing of a predetermined image area based on print data input while bidirectionally scanning an inkjet print head that performs printing by discharging ink on a printing medium,
When printing the predetermined image area in a series of reciprocating bidirectional printing, the printing is performed so as to increase the printing ratio of printing from the scan start position to the scan end position with respect to the direction in which the predetermined image area is printed first. Setting a ratio, a recording ratio setting step of setting a complementary recording ratio of the recording ratio for a direction opposite to the first recording direction,
A recording step of recording the predetermined image area based on a recording ratio set in the recording ratio setting step,
A control program characterized by comprising: A computer-readable program that stores a control program for controlling an inkjet printing apparatus that prints a predetermined image area based on print data input while scanning an inkjet print head that ejects ink to perform printing on a printing medium in both directions. A storage medium,
The control program includes:
When printing the predetermined image area in a series of reciprocating bidirectional printing, the printing is performed so as to increase the printing ratio of printing from the scan start position to the scan end position with respect to the direction in which the predetermined image area is printed first. Setting a ratio, a recording ratio setting step of setting a complementary recording ratio of the recording ratio for a direction opposite to the first recording direction,
A recording step of recording the predetermined image area based on a recording ratio set in the recording ratio setting step,
A computer-readable storage medium comprising:

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