JP2001150700A - Imaging method, imaging apparatus, and image treatment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form an image in which image density is not changed largely, and the nonuniformity of density and color is reduced even when registration by an error in physical precision is changed finely in a recording apparatus for recording by a multi-pass method. SOLUTION: Multi-value image data of each color (A, L) are divided into image data sections for scanning a prescribed area (B, C, M, N), and the gradation of respective divided multi-value data are lowered by different error distribution matrices (H, I, S, T). An image with a compensation relationship between colors decreased is formed by each scanning, and by forming an image without the relationship between colors, the dependency of the change of color density and color tone on the change of registration is decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-pass image forming method and apparatus for forming an image by completing a predetermined area by scanning a plurality of times, and further to an image processing method. In particular, the present invention relates to an image forming method and apparatus for reducing density unevenness and color tone unevenness of a recorded image in an image forming apparatus such as a copying machine, a facsimile, a printer, a textile printing machine, and an image processing method.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine or a textile printing machine, density unevenness of an image is reduced by completing the same area by scanning a plurality of times. An image forming apparatus using the multi-pass method will be described using a printing machine as an example.

FIG. 1 is a schematic diagram showing an outline of an image printing section of an ink jet recording type textile printing machine which performs recording on a fabric applicable to the present invention. This printing apparatus is roughly divided into a feeding section B for feeding a print medium such as a roll-shaped cloth which has been subjected to a pre-treatment for textile printing, and a feed line for feeding the sent print medium precisely, and an ink jet head. And a winding unit C for drying and winding the printed print medium. The main body section A further includes a precision feeding section A-1 for a print medium including a platen and an ink jet printing section A-2.

[0004] The operation of this apparatus will be described below by taking as an example a case where printing is performed using a pre-processed print medium as a print medium.

[0005] Pre-processed roll-shaped print medium 23
6 is sent out from the payment section B and sent to the main body. The body is a thin endless belt 23 that is precisely step driven.
7 is wound around a driving roller 247 and a winding roller 249. The driving roller 247 is directly step-driven by a high-resolution stepping motor (not shown), and steps the belt by the step amount. The sent cloth 236 is pressed against the surface of the belt 237 backed up by the winding roller 249 by the pressing roller 240 and is attached.

The print medium 236 that has been step-fed by the belt is localized in the first print unit 602 by the platen 232 on the back surface of the belt, and is printed by the inkjet head 209 from the front side. Each time one line of printing is completed, the printing paper is stepped by a predetermined amount and then heated by the heating plate 234 from the back of the belt and supplied / discharged by the hot air duct 235.
It is dried by warm air from the surface. Subsequently, in the second print unit 603, overprinting is performed in the same manner as in the first print unit.

[0007] The print medium 236 after printing is peeled off, and the heating plate 234 and the hot air duct 2 described above are peeled off.
The sheet is dried again in the post-drying section 246 similar to 35, guided by the guide roll 241, and wound on the take-up roll 248. Then, the wound print medium 236 is removed from the present apparatus, and is subjected to a post-processing step such as color development, washing, and drying in a batch process to become a product.

Next, details of the vicinity of the ink jet printing section A-2 will be described with reference to FIG.

Here, the head of the first printing unit
The information is printed by thinning out the number of dots, and after a drying process, ink droplets are ejected by the head of the second printing unit so as to complement the information thinned out in the first printing unit.

In FIG. 2, a print medium 236 is attached to a belt 237, and is fed stepwise in the upward direction in the figure. A first carriage 244 on which four inkjet heads for Y, M, C, and K are mounted is provided in a first print unit 602 at a lower portion in the drawing. The ink jet head (print head) in this example uses an element having an element that generates thermal energy that causes film boiling of the ink as energy used for discharging the ink.

Downstream of the first printing section, there is provided a drying section 245 comprising a heating plate 234 for heating from the back side of the belt and a hot air duct 235 for drying from the front side. The heat transfer surface of the heating plate 234 is pressed against a strongly tensioned endless belt 237, and the belt 237 is strongly heated from the back surface by the high-temperature and high-pressure steam passing through the hollow inside. The belt 237 directly and effectively heats the attached print medium 236 by heat conduction. Fins 234 'for heat collection are provided inside the heating plate surface so that heat can be efficiently concentrated on the back surface of the belt. The side not in contact with the belt is covered with a heat insulating material 243 to prevent loss due to heat radiation.

On the front side, by blowing dry warm air from the downstream supply duct 230, the print medium 236 being dried is exposed to lower humidity air to enhance the effect. Then, the air flowing in the opposite direction to the transport direction of the print medium 236 and sufficiently containing water is sucked from the suction duct 233 on the upstream side by a much larger amount than the amount of the sprayed air. Prevents condensation on surrounding machinery. The supply source of the hot air is located at the back side in FIG. 2, and suction is performed from the near side. The pressure difference between the outlet 238 facing the print medium 236 and the suction port 239 extends over the entire area in the longitudinal direction. It is made uniform. Blowing air /
The suction section is offset downstream with respect to the center of the heating plate 234 on the rear surface so that air can hit a sufficiently heated place. Thus, the first printing unit 602 strongly dries a large amount of water in the ink including the thinning liquid received by the print medium 236.

A second print unit 603 is provided downstream (upper side in the figure), and a second print unit is formed by a second carriage 244 'having the same configuration as the first carriage. Downstream, a post-drying unit 46 having the same configuration as the hot air duct 235 is provided.

Next, a specific example of ink-jet textile printing will be described. As described above, FIG. 1 is a diagram illustrating a configuration of an inkjet printing apparatus suitable for printing. Using an inkjet printing apparatus as shown in FIG.
After the inkjet printing process, the print medium is dried (including natural drying). Subsequently, a step of diffusing the dye on the print medium fiber and reacting and fixing the dye on the fiber is performed. By this step, it is possible to obtain sufficient color-forming properties and fastness due to fixation of the dye.

The diffusion and reaction fixing step may be performed by a conventionally known method, for example, a steaming method. In addition,
In this case, the printing medium may be subjected to an alkali treatment before the printing step.

Thereafter, in a post-treatment step, unreacted dye is removed and substances used in the pre-treatment are removed. Finally, the print is completed through an orderly finishing process such as defect correction and ironing.

FIG. 3 is a view showing the arrangement of the ink jet recording heads shown in FIGS. As described above, this printer forms an image with four basic CMYK inks. The recording head unit 601 includes two ink jet heads of each ink color, and a head 603 (hereinafter, referred to as a rear head) arranged at an upper part of the drawing and a head 602 (hereinafter, referred to as a rear head) arranged at a lower part. The head is located at a distance of 2.5 bands in the sub-scanning direction (a band is a unit of width in the nozzle row direction in which the inkjet head performs printing in one scan).

FIG. 4 is a view showing a state in which printing is performed by the front head 602 and the rear head 603 in the printer. One sub-scan is performed for each main scan. The feed amount in the sub-scanning direction is one band, and the front head 6
02 and the rear head 603 are shifted from each other by a half band, that is, an image is formed by half band overlap. Here, half band 7
03 is formed by the upper half of the front head 602 and the lower half of the rear head 603, respectively, and the half band 704 is formed by the lower half of the front head 602 and the rear head 6 respectively.
03 is formed in the upper half.

FIG. 5 shows the processing contents from binarization of the multi-valued image data transferred to the printer, conversion into head drive data, ejection of ink from nozzles, and printing. Will be described.

(1) The multi-valued image data transferred from the host computer is stored in the image data storage device 801. From here, data is read for each band.

(2) In the pallet conversion circuit 802, the image data is decomposed into multi-value data of each ink color. Less than,
The black ink Bk will be described as a representative.

(3) The γ-conversion circuit 803-K performs γ-conversion on the multi-valued data separated into ink colors.

(4) The non-uniformity correction circuit 804-K corrects non-uniformity caused by nozzle characteristic variations using a non-uniformity correction table (multi-valued to multi-valued lookup table).

(5) The binarization circuit 805-K converts multi-valued data into binary data by the error diffusion method (ED).

(6) An SMS (sequential multi-scan) circuit 806-K determines whether the binary data of each color is printed by the front head 602-K or the rear head 603-K. The SMS circuit-K alternately allocates front, rear, front, rear,... In order from the dot which appears first from the left end of the image when attention is paid to a certain raster.
Controller) circuits 807-K1 and 807-K2. As a result, adjacent dots are not printed by the same head, and printing can be performed at twice the driving frequency of the head. Further, the first dot to be printed in each raster is printed by the rear head 603-K in the case of an odd raster and by the front head 602-K in the case of an even raster.

(7) TMC circuits 807-K1 and 807-K
In No. 2, one band of data is output to each of the heads 602-K and 603-K one row at a time in the nozzle row direction. The horizontal registration adjustment value adjusts the positional deviation between the heads 807-K1 and 807-K2 in the head main scanning direction, but the output timing of one column of data differs depending on the horizontal registration adjustment value.

(8) PHC (Connector between Printer Heads)
On the substrates 808-K1 and 808-K2, binary data in the nozzle row direction is output corresponding to the nozzles that actually perform printing. The vertical registration adjustment value adjusts the positional deviation between the heads 807-K1 and 807-K2 in the nozzle row direction. In the head in this example, the upper and lower eight nozzles are print effective nozzles in addition to the 1344 nozzles.
8 range. When the vertical register tone value is ± 0, the center 13
Although 44 nozzles are used, when the vertical registration tone value is ± 1 to 8, the 1344 nozzles to be actually printed are shifted from the center by 1 to 8 nozzles. With this vertical register tone value, 1344
The data for the nozzles is output in correspondence with the nozzles that actually perform printing.

(9) Finally, the binary data of each nozzle is
The data is converted into head drive data by a print control device (Head CPU) 809, and printing is performed by discharging ink.

FIG. 7 specifically shows the processing of (5) and (6). Each ink color is separated, and γ conversion and unevenness correction processing (802, 803, 8 in FIG. 5)
04) is subjected to error diffusion processing (FIG. 7B) using an error diffusion matrix A (an example of the error diffusion matrix shown in FIG. 6A) to perform binarization (FIG. 7B). C). Note that * in FIG. 6 represents a target pixel. And S
The MS (806 in FIG. 5) determines whether to print with the front head or the rear head (FIG. 7D). Then, the data shown in FIG. 7E is sent to the front head, and the data shown in FIG. 7F is sent to the rear head.

According to the above-described method, the image of the predetermined area is 2
Since the heads are formed by different nozzles of one head, it is possible to reduce unevenness in density and the like due to variation in characteristics of a plurality of nozzles. In addition, since the seams of the image are in half band units, the banding cycle is halved, and the banding is less noticeable.

[0031]

However, the printed image may have an error in the registration adjustment value between the front head and the rear head,
There is a problem in that the head is easily affected by oblique mounting of the head, an error in the amount of feed of the recording medium in the sub-scanning direction, or an error in landing of ink droplets due to the vibration of the carriage. This is because, in the above method, the "complementary relationship" in the print image of the front head and the print image of the rear head is complete,
It has been found by the study of the present inventors.

That is, in the above-described method, half-band images completed by two scans have a completely complementary relationship to each other (hereinafter, a relationship in which dots printed in each pass spatially complement each other). Is called a "complementary relationship.") For this reason, if an error occurs in the registration for each band, for example, if the horizontal registration for half a dot is shifted, complementation is performed with the horizontal registration shifted.

Originally, if printing is performed by the above-described method using an ideal apparatus, the solid (uniform) image shown in FIG. 8 has overlapping dots even if the images printed by each scan are overlapped. They should be evenly spaced. In FIG. 8, 201 (black circle dot) indicates the image printed by the front head 602, 202 (white circle dot) indicates the image printed by the rear head 603, and each of the heads ejects the same color ink, for example, the head 602. -K and 603-K
It is printed with.

However, in an actual apparatus, the registration changes slightly in each scan due to an error in physical accuracy. Therefore, when the images recorded in each scan are overlapped, the dots are not close to each other. They may be too far, far apart, or overlap. For example, when a shift of the horizontal registration by half a dot occurs in the front head 602, as shown in FIG. 9, uneven density occurs between the dots, and overlapping of the dots occurs. 201 (black dot)
Indicates a printout made by the front head 602;
(Dots of white circles) are printed by the rear head 603. As a result, the recorded image is different from the original image density, and density unevenness occurs, which is a serious problem.
That is, a band having a high density (a band is a unit of the width in the nozzle row direction in which the ink jet head performs printing in one scan) or a thin band is generated, and half band unevenness occurs.

When multi-valued data has the same value in a plurality of recording colors, if the registration of the recording heads is matched, dots of recording colors of the same value land at the same position. become. This is because, as shown in FIG. 10, the binarization processing and the like are performed in exactly the same manner for each color of Bk,.

However, if an error occurs in the registration for each recording color for each band, the degree of dot overlap will change, the tint of the secondary color will change, and half-band unevenness will occur.

FIG. 11 shows a state in which cyan and magenta dots are completely overlapped, and 401 indicates a dot in which cyan and magenta overlap (a blue dot). At this time, the multi-valued data of cyan and magenta are assumed to be the same, and the registration of the head of each recording color matches.

On the other hand, FIG. 12 shows how dots are printed when the registrations of cyan and magenta do not match. In the figure, 501 (black dot) indicates a cyan dot, and 502 (white circle dot)
Indicates a magenta dot.

When FIG. 11 is compared with FIG. 12, it is understood that the degree of dot overlap is different. As described above, when an error occurs in the registration for each band, a difference occurs in the degree of dot overlap, the color tone changes, and half-band unevenness occurs. Further, even if no registration error occurs, if all the dots overlap as shown in FIG. 4, there arises a problem that the color reproduction range of the secondary color is narrowed.

As described above, in the conventional multi-pass printing, when an image is formed by a plurality of scans, the image completed by the plurality of scans has a completely complementary relationship, and each color has a correlation. Therefore, the present inventors have found that the change in the registration directly appears as density unevenness or color unevenness of the image.

The present invention has been made in order to solve the above-mentioned problems, and even if the registration is slightly changed due to a physical precision error, the image density and color are not largely changed and the density unevenness and color unevenness are not changed. It is an object of the present invention to provide an image forming apparatus, an image forming method, and an image processing method capable of forming an image with reduced image quality.

[0042]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a method for complementing an image on a predetermined area of a recording medium for each color by performing a plurality of scans of a plurality of recording heads corresponding to a plurality of colors. A distribution unit that distributes multi-valued image data corresponding to the predetermined area for each color in accordance with the plurality of scans, and for each color distributed by the distribution unit. Means for lowering the gradation of the multi-valued image data, and the plurality of scans in the plurality of scans based on the image data for each color which has been reduced in gradation by the lowering means. Forming means for driving a recording head to form an image having the complementary relationship for each color, wherein each color formed by the forming means is provided by at least one of the distributing means and the gradation lowering means. Every Characterized by reducing the correlation between complementary relationship and each color image.

According to the present invention, there is provided an image forming apparatus for forming an image on a predetermined area of a recording medium by a plurality of scans of a plurality of recording heads corresponding to a plurality of colors. Distributing means for distributing the image data of different values in the plurality of scans, and lowering the gradation of the multi-valued image data of each color distributed by the distributing means by different processing for each color Means, and forming means for forming an image by driving the plurality of recording heads in the plurality of scans based on image data of each color reduced in tone by the tone reducing means. Features.

Further, according to the present invention, in an image forming apparatus for forming an image on a predetermined area of a recording medium by a plurality of scans of a plurality of recording heads corresponding to a plurality of colors, a multi-color image corresponding to the predetermined area is provided. Distributing means for distributing the image data of the value corresponding to the plurality of scans, and a lower level for lowering the gradation of the multi-valued image data for each color and each scan distributed by the distributing means by different processing. Conditioning means;
Forming means for forming an image by driving the plurality of recording heads in the plurality of scans based on the image data of each color reduced in tone by the tone reducing means. .

Further, according to the present invention, there is provided an image forming method for forming an image on a predetermined area of a recording medium by an image having a complementary relationship by a plurality of scans of a plurality of recording heads corresponding to a plurality of colors, In this manner, an image for each color corresponding to the predetermined area is formed in an incomplete complement relationship by scanning, and an image between the colors is formed in an incomplete correlation.

Further, the present invention provides an image processing method for forming an image on a predetermined area of a recording medium by an image having a complementary relationship by a plurality of scans of a plurality of recording heads corresponding to a plurality of colors. In order to form an image of each color corresponding to the predetermined area in an incomplete complementation by scanning twice, and to form an image between the colors in an incomplete correlation,
Processing image data to be supplied to the plurality of print heads in the plurality of scans.

According to the above configuration, the image recorded by each scan has a reduced complementarity, or an image is formed with an incomplete complementarity, and an image having no correlation between the colors is formed. Even if the registration changes slightly due to physical accuracy errors, the dependence on the change in the registration decreases, so that an image with reduced density unevenness and color unevenness is formed without significant change in image density and color. can do.

[0048]

Embodiments of the present invention will be described below in detail with reference to the drawings. Embodiments 1, 2, and 5 are embodiments in which a plurality of heads of the same color are provided, and Embodiment 3 is an embodiment in which quaternary processing is performed instead of binarization as low gradation. The fourth embodiment is an embodiment in which one head of the same color is provided. The ink jet recording type textile printing machine that performs recording on the fabric shown in FIGS. 1 to 4 can be applied to the present embodiment as described above, and the details are omitted here.

(Embodiment 1) In this embodiment, the multi-value data of each ink color is binarized, and the binary data is not distributed to the front head and the rear head. The multi-valued data is distributed to the front head and the rear head, the distributed multi-valued data is subjected to data conversion using different coefficients, and different binarization processes are performed on the converted data. This makes it possible to reduce the "complementary relationship" of the printed image in each scan and each ink color, or to eliminate the "correlation" to prevent half-band unevenness.

In this embodiment, the multi-valued image data is
FIG. 13 shows a process of converting the values into head drive data, discharging the ink from the nozzles, and printing.
The processing flow will be described with reference to the drawings.

(1) The multi-valued image data transferred from the host computer is stored in the image data storage device 101. From here, data is read for each band.

(2) In the pallet conversion circuit 102, the image data is decomposed into multi-value data of each ink color. Less than,
The black ink Bk will be described as a representative.

(3) The γ-conversion circuit 103-K performs γ-conversion on the multi-valued data separated into ink colors.

(4) The non-uniformity correction circuit 104-K corrects non-uniformity caused by nozzle characteristic variations using a non-uniformity correction table (multi-valued → multi-valued look-up table).
The processing up to this point is the same as the conventional processing shown in FIG.

(5) Distribution circuits 105-K1 and 105-K
In step 2, data is distributed to the front head and the rear head.

(6) Data conversion circuit 106-K1, 10
At 6-K2, data distribution is performed on the distributed data using predetermined coefficients.

(7) Low gradation circuit 107-K1, 107
At -K2, a gradation reduction process is performed for each head by the error diffusion method.

(8) TMC (Timing Memory Controller)
In the circuits 108-K1 and 108-K2, for each head,
One band of data is output one row at a time in the nozzle row direction. The horizontal registration adjustment value adjusts the positional deviation of the head in the main scanning direction of the head. The output timing of data for one column differs according to the horizontal registration adjustment value.

(9) PHC (Connector between Printer Heads)
On the substrates 109-K1 and 109-K2, binary data in the nozzle row direction is output corresponding to the nozzles that actually perform printing. The vertical registration adjustment value adjusts the positional deviation of the head in the nozzle row direction. In the head in this example, the upper and lower eight nozzles are print effective nozzles in addition to the 1344 nozzles, so the vertical registration adjustment value is in the range of -8 to +8. When the vertical registration key value is ± 0, the center 1344 nozzles are used. When the vertical registration key value is ± 1 to 8, the 1344 nozzles to be actually printed are shifted from the center by 1 to 8 nozzles. With this vertical registration tone value, data for 1344 nozzles is output in association with the nozzles that actually perform printing.

(10) Finally, the binary data of each nozzle is converted into head drive data by the print control device (Head CPU) 110, and printing is performed by discharging ink.

In this embodiment, an example has been described in which the above-described processing is realized by the hardware configuration of the image processing apparatus. However, the processing can be realized by using software or the like as appropriate.

FIG. 14 shows 105, 106 and 107 in FIG.
3 shows a specific example of the processing. In FIG.
The multi-value data of each color (A in the figure) is transferred to the front head 602
Data (B in the figure) to be sent to the
3 and the image data to be sent to C.3 (C in the same figure). The distributed data is multiplied by the same coefficient (0.5) (FIGS. D and E). Each of the converted data (F and G in the figure) is binarized by an error diffusion method (H and I in the figure) using a different error distribution matrix, and the binarized data (J and K in the figure) are converted to respective data. Print with the head. The error distribution matrices used in FIGS. H and I are those shown in FIGS. 6A and 6B.

The multivalued data distributed and converted for the front head and the rear head are the same, but the error distribution matrices for error diffusion are different from each other, so that the images printed by the respective heads have a "complementary relationship". It is possible to form an image having reduced half band unevenness.

In the above description, only the black ink is described. However, in this embodiment, as shown in FIG. 15, not only the front and rear heads but also each ink color has a different error distribution matrix by the error diffusion method. Value, 2
The digitized data is printed by each head.

That is, FIG. 15 shows the processing for the yellow (Y) head in addition to the black (Bk). FIG.
At T, each of the converted data (Q, R in FIG. 6) is binarized by an error diffusion method (C, D in FIG. 6) of a different error distribution matrix, and binarized data (U, V in FIG. 6). ) Is printed by each head. Similarly, for cyan (C) and magenta (M) not shown,
Different error distribution matrix error diffusion methods are used.

As described above, even if the values of the multi-value data of the different ink colors are the same, the "correlation" between the respective colors disappears because the error distribution matrices are different. Therefore, as described below, even if the registration is slightly changed due to a physical error, an image without color unevenness can be formed, and the color reproduction range can be widened.

FIG. 16 is a diagram showing a case in which overprinting is performed by the front head and the rear head using the image processing method according to the present invention, assuming that the physical accuracy is ideally ideal. Reference numeral 601 (black dot) indicates a result printed by the front head, and 602 (white circle dot) indicates a result printed by the rear head.

FIG. 17 shows a case where the registration of the front head and the rear head is slightly shifted in FIG. Here, a case where the registration of the front head is shifted by half a dot (to the right in the drawing). Even if FIG. 16 and FIG. 17 are compared, no significant change is observed in the density of the image. That is, even if the registration in each scan slightly changes, the density hardly changes and half band unevenness does not occur.

16 and 17, 601 (black dots) are cyan dots and 602 (white circle dots) are magenta dots. Considering that both were printed by the front heads or the rear heads, 16,1
7 does not show any significant change in the degree of dot overlap. That is, even if the registration of the head of each recording color is slightly changed, the degree of overlap of each color hardly changes, so that the color is hardly changed and an image without half band unevenness can be generated.

Further, since the dots for each recording color are appropriately dispersed without completely overlapping, the color reproduction range is wider than before.

Further, by performing data conversion by the data conversion process, printing with a duty of 100% or more becomes possible.

Although the concept of the "complementary relationship" in which the image formed by a plurality of passes is macroscopically described in this embodiment has been described here, it is also possible to microscopically capture the image. In this case, paying attention to dots recorded in a plurality of passes, an image is formed in which a "correlation" in which dots recorded in another pass are present next to dots recorded in a certain pass, You can also catch it.

On the other hand, the “correlation” between colors is 2
This means that the dots forming the next color all overlap.

(Embodiment 2) FIG. 18 is a cross-sectional view of FIG.
This shows a specific example of the processing of steps 06 and 107. In FIG. 18, the multi-valued data (A in FIG. 18) is divided into image data (B in the same drawing) for sending to the front head and image data (C in the same drawing) for sending to the rear head.
The same coefficient for each distributed multi-value data) (0.
5) (FIGS. D and E). The two data (F and G in the figure) subjected to the data conversion are respectively binarized by the error diffusion method (H and I in the figure) having different threshold values, and the binarized data (J and K in the figure). ) Is printed by each head.

The multi-valued data distributed and converted for the front head and the rear head are the same, but since the threshold values for error diffusion are different, the "complementary relationship" of the image printed by each head is reduced. Thus, it is possible to form an image with reduced half band unevenness.

In the above description, only the black ink is described. However, in this embodiment, as shown in FIG. 19, not only the front and rear heads but also the respective ink colors are binarized by different threshold values, and the binarization is performed. The converted data is printed by each head.

That is, FIG. 19 shows the processing for the yellow (Y) head in addition to the black (Bk). FIG.
At T, each of the converted data (Q and R in the figure) is binarized by an error diffusion method with different threshold values, and the binarized data (U and V in the figure) is printed by each head. Similarly, error diffusion methods with different threshold values are used for cyan (C) and magenta (M) not shown.

As described above, even if the values of the multi-value data of the different ink colors are the same, the threshold values are different from each other, so that there is no "correlation" between the colors. Therefore, even if the registration is slightly changed due to a physical error, an image without color unevenness can be formed, and the color reproduction range can be widened.

The same effect can be obtained by combining the respective elements (error diffusion matrix for error diffusion, threshold value for binarization) of the first and second embodiments.

(Embodiment 3) Next, FIG. 13 shows a specific example of the processing in FIG. 13 in which quaternary processing is performed using dot diameter modulation as gradation reduction. The same as in the first embodiment except that the quaternary processing is performed as the gradation lowering processing, and the multi-valued data (A in the figure) is distributed to the number of times of scanning the same area (B and C in the figure). The obtained multivalued data is multiplied by the same coefficient (0.5) (FIGS. D and E).
Each of the converted data (F and G in FIG. 4) is divided into four by the error diffusion method (H and I in FIG. 4) of a different error distribution matrix.
The data is digitized and quaternized data (J and K in the figure) is printed by each head.

Even if the quaternizing process is performed, when printing is performed by the conventional processing method, the images printed by the respective heads have a complete “complementary relationship”. The head "complementary relationship" can be reduced, and an image in which half band unevenness is reduced can be formed.

In the above description, only the black ink is described. However, in this embodiment, as shown in FIG. 21, not only the front and rear heads but also each ink color has a different error distribution matrix by the error diffusion method. Value 4
The digitized data is printed by each head.

That is, FIG. 21 shows the processing for the yellow (Y) head in addition to the black (Bk). FIG.
At T, each of the converted data (Q, R in FIG. 6) is quaternized by an error diffusion method (C, D in FIG. 6) of a different error distribution matrix, and the quaternized data (U, V in FIG. 6). ) Is printed by each head. Similarly, for cyan (C) and magenta (M) not shown,
Different error distribution matrix error diffusion methods are used.

As described above, even if the values of the multi-value data of the different ink colors are the same, since the error distribution matrices are different from each other, there is no "correlation" between the colors. Therefore, even if the registration is slightly changed due to a physical error, an image without color unevenness can be formed, and the color reproduction range can be widened.

As in the second embodiment, the same effect can be obtained by using an error diffusion method having a different threshold value, or using an error distribution matrix and a threshold value different from each other.

(Embodiment 4) Next, an embodiment of a printer having one head for one color will be described with reference to the drawings. In FIG. 13, when the F (front) head is replaced with the first scan and the R (rear) head is replaced with the second scan, the flow of the image processing of the present embodiment is shown.

FIG. 22 shows the superimposed state of the print images of the first scan and the second scan. The feed amount of the medium is a half band, and an image is formed by half band overlap of the first scan and the second scan.

In this embodiment, as in the first and second embodiments, data is distributed by the number of times of scanning the same area (here, 2), each data is converted by a predetermined coefficient, and the converted data is converted. Is binarized by a predetermined error diffusion method.

FIG. 23 shows a specific example of the processing corresponding to FIG. In FIG. 23, as in the first to third embodiments, multi-valued data (A in FIG. 23) is distributed into (two) data (B and C in FIG. 23) for the number of times of scanning the same area. Of the same coefficient (first scan: 0.5,
Data conversion is performed in the second scan: 0.5) (D and E in the same figure).
The converted data (F and G in the figure) is binarized by an error diffusion method (H and I in the figure) of a different error distribution matrix, and the binarized data (J and K in the figure) is scanned in the first scan. And the second
Print by scanning.

Although the above description is for black (Bk), the same applies to yellow (Y).
, Each of the converted data (Q, R in FIG. 6) is binarized by an error diffusion method (C, D in FIG. 6) of a different error distribution matrix, and binarized data (U, V in FIG. 6). Is printed in the first scan and the second scan. Similarly, error diffusion methods of different error distribution matrices are used for cyan (C) and magenta (M) not shown.

Even if an error occurs in the feed amount of the medium in the sub-scanning direction or the registration changes slightly, the error distribution matrices are different, and the "complementary relationship" of the image printed in each scan is reduced. Thus, an image in which half band unevenness is reduced can be formed.

Further, even if the values of the multi-valued data of different ink colors are the same, the error distribution matrices are different from each other, so that there is no "correlation" between the colors. for that reason,
Even if the registration is slightly changed due to physical errors, it is possible to form an image without color unevenness,
In addition, the color reproduction range can be widened.

Further, similar to the second embodiment, the same effect can be obtained by using different threshold values in the error diffusion method, or by using an error diffusion method having different error distribution matrices and different threshold values.

(Embodiment 5) FIG.
This shows a specific example of the processing of steps 06 and 107. In FIG. 24, the multi-valued data (A in FIG. 24) is divided into two parts: image data (B in the same figure) for sending to the front head and image data (C in the same figure) for sending to the rear head.
Data conversion is performed on the distributed data using different coefficients for the front head and the rear head (FIGS. D and E). Each of the converted data (F and G in the figure) is binarized by an error diffusion method (H and I in the figure) using a different error distribution matrix, and the binarized data (J and K in the figure) are converted to respective data. Print with the head.

Here, the difference from the first to fourth embodiments is that the sum of the coefficients in the data conversion processing is not 1 but 1 or more, and that the data conversion coefficients for the front head and the rear head are different from each other. is there. In the fifth embodiment, the sum of the coefficients is 1.2 (front: 0.65, rear:
0.55). This means that printing with a duty of 100% or more is possible.

Although the above description is for black (Bk), the same applies to yellow (Y).
In FIG. 6, each of the converted data (Q and R in FIG. 6) is binarized by an error diffusion method (B in FIG. 6) of an error distribution matrix different from Bk and binarized data (U and V in FIG. 6). Is printed by the first scan and the second scan. Similarly, error diffusion methods of different error distribution matrices are used for cyan (C) and magenta (M) not shown.

Since different data conversion coefficients are used for the multivalued data for the front head and the multivalued data for the rear head, the "complementary relationship" is reduced in the images printed by the respective heads, and the half band unevenness is reduced. Can be formed. Also in the first to fourth embodiments, by using different data conversion coefficients for the front and rear, and for the first and second scans, it is possible to reduce the "complementary relationship" between the print images.

Further, even if the values of the multi-valued data of the different ink colors are the same, since the error distribution matrices are different, there is no "correlation" between the colors. for that reason,
Even if the registration is slightly changed due to physical errors, it is possible to form an image without color unevenness,
In addition, the color reproduction range can be widened.

In the fifth embodiment, different error distribution matrices are shown. However, similar effects can be obtained by using different threshold values.

Further, since the sum of the data conversion coefficients at the time of the data conversion processing is 1 or more, printing at a duty of 100% or more becomes possible. Also in the first to fourth embodiments, by using the one in which the sum of the data conversion coefficients is 1 or more, printing with a duty of 100% or more becomes possible.

The present invention particularly provides an excellent effect in a recording apparatus using an ink jet type recording head which performs recording by forming flying droplets by utilizing thermal energy among ink jet recording methods.

The typical configuration and principle are described, for example, in US Pat. Nos. 4,723,129 and 4,740.
It is preferable to use the basic principle disclosed in the specification of Japanese Patent No. 796. This method is a so-called on-demand type,
Although it can be applied to any type of continuous type, in particular, in the case of the on-demand type, it can be applied to a sheet holding liquid (ink) or an electrothermal converter arranged corresponding to the liquid path. By applying at least one drive signal corresponding to recording information and giving a rapid temperature rise exceeding nucleate boiling, heat energy is generated in the electrothermal transducer, and film boiling occurs on the heat acting surface of the recording head. Liquid (ink) corresponding to the drive signal
This is effective because air bubbles in the interior can be formed. 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 formed into a pulse shape, the growth and shrinkage of the bubble are performed immediately and appropriately, so that the ejection of a liquid (ink) having particularly excellent responsiveness can be achieved, which is more preferable. 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 relating to the temperature rise rate of the heat acting surface are adopted, more excellent recording can be performed.

The configuration of the recording head includes a combination of a discharge port, a liquid path, and an electrothermal converter (a linear liquid flow path or a right-angled liquid flow path) as disclosed in the above-mentioned respective specifications. U.S. Pat. No. 4,558,333 and U.S. Pat.
A configuration using the specification of Japanese Patent No. 59600 is also included in the present invention. In addition, Japanese Unexamined Patent Application Publication No. 59-123670 discloses a configuration in which a common slit is used as a discharge portion of an electrothermal converter for a plurality of electrothermal converters, and an aperture for absorbing a pressure wave of thermal energy is provided. The effect of the present invention is effective even if the configuration is based on JP-A-59-138461, which discloses a configuration corresponding to a discharge unit. That is, according to the present invention, recording can be reliably and efficiently performed regardless of the form of the recording head.

In addition, even in the case of the serial type as described above, the recording head fixed to the apparatus main body or the electric connection with the apparatus main body or the ink from the apparatus main body is mounted on the apparatus main body. The present invention is also effective when a replaceable chip-type recording head that can be supplied or a cartridge-type recording head in which an ink tank is provided integrally with the recording head itself is used.

Further, it is preferable to add ejection recovery means for the recording head, preliminary auxiliary means, and the like as the configuration of the recording apparatus of the present invention since the effects of the present invention can be further stabilized. If these are specifically mentioned, the recording head is heated using capping means, cleaning means, pressurizing or suction means, an electrothermal transducer, another heating element or a combination thereof. Pre-heating means for performing the pre-heating and pre-discharging means for performing the discharging other than the recording can be used.

Also, as for the type or number of print heads to be mounted, two or more print heads may be provided corresponding to a plurality of inks having different print colors and densities. That is, for example, the printing mode of the printing apparatus is not limited to a printing mode of only a mainstream color such as black, but may be any of integrally forming a printing head or a combination of a plurality of printing heads. The present invention is also very effective for an apparatus provided with at least one of the recording modes of full color by color mixture.

In addition, in the embodiments of the present invention described above, the ink is described as a liquid. However, an ink which solidifies at room temperature or lower and which softens or liquefies at room temperature may be used. In general, the ink jet method generally controls the temperature of the ink itself 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. Sometimes, the ink may be in a liquid state. In addition, in order to positively prevent temperature rise due to thermal energy by using it as energy for changing the state of the ink from a solid state to a liquid state, or to prevent evaporation of the ink, the ink is solidified in a standing state and heated. 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 to solidify when reaching 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. In such a case, the ink
JP-A-54-56847 or JP-A-60-7
As described in Japanese Patent Publication No. 1260, a form may be adopted in which the liquid sheet or the solid substance is held as a liquid or solid substance in the concave portion or through hole of the porous sheet and faces the electrothermal converter. In the present invention, the most effective one for each of the above-mentioned inks is to execute the above-mentioned film boiling method.

In addition, the form of the ink jet recording apparatus of the present invention is not limited to those used as image output terminals of information processing equipment such as computers, copying apparatuses combined with readers and the like, and facsimile apparatuses having a transmission / reception function. It may take a form.

[0109]

According to the present invention, an image for each color recorded in each scan has a reduced complementarity or an image is formed with an incomplete complementarity, and the image between the colors has no correlation. Even if the registration is slightly changed due to a physical accuracy error, the dependence on the registration change is reduced, so that the image density is not largely changed and an image with reduced density unevenness and color unevenness is formed. Can be.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an outline of an image printing section of an ink jet recording type textile printing machine which performs recording on a fabric applicable to the present invention.

FIG. 2 is a perspective view showing details in the vicinity of an inkjet printing unit A-2 shown in FIG.

FIG. 3 is a diagram showing an arrangement state of heads applicable to the present invention.

FIG. 4 is a diagram showing a superimposed state of print images of a front head and a rear head.

FIG. 5 is a block diagram showing a flow of processing performed until data sent to a conventional printer is printed.

FIG. 6 is a diagram illustrating an example of an error distribution matrix.

FIG. 7 is a diagram showing a flow of a conventional image processing method.

FIG. 8 is a diagram showing an arrangement of dots in a case where overprinting is performed by a conventional ideal front head and rear head.

FIG. 9 is a diagram showing an arrangement of dots in a case where overlapping printing is performed by a conventional actual front head and rear head.

FIG. 10 is a diagram showing image processing in the related art.

FIG. 11 is a diagram showing a dot arrangement in a case where cyan and magenta are overprinted in a conventional ideal state.

FIG. 12 is a diagram illustrating a dot arrangement in a case where cyan and magenta are overprinted in a conventional actual state.

FIG. 13 is a block diagram showing a flow of processing until data sent to a printer is printed in the present invention.

FIG. 14 is a diagram illustrating a specific example of image processing according to the first embodiment of the present invention.

FIG. 15 is a diagram illustrating a specific example of image processing according to the first embodiment of the present invention.

FIG. 16 is a diagram showing an arrangement of dots in a case where overprinting is performed by an ideal front head and rear head according to the present invention.

FIG. 17 is a diagram showing an arrangement of dots when overprinting is performed by an actual front head and a rear head according to the present invention.

FIG. 18 is a diagram illustrating a specific example of image processing according to the second embodiment of the present invention.

FIG. 19 is a diagram illustrating a specific example of image processing according to the second embodiment of the present invention.

FIG. 20 is a diagram illustrating a specific example of image processing according to the third embodiment of the present invention.

FIG. 21 is a diagram illustrating a specific example of image processing according to a third embodiment of the present invention.

FIG. 22 is a diagram illustrating a superimposed state of print images of respective scans of a printer having one head per color applicable to the present invention.

FIG. 23 is a diagram illustrating a specific example of image processing according to a fourth embodiment of the present invention.

FIG. 24 is a diagram illustrating a specific example of image processing in Embodiment 5 of the present invention.

[Explanation of symbols]

Reference Signs List 101 Image data storage device 102 Pallet conversion circuit 103 γ conversion circuit 104 Unevenness correction circuit 105 Distribution circuit 106 Data conversion circuit 107 Gradation reduction circuit 108 TMC (Timing Memory Con)
(controller) circuit 109 Conn between PHC (Printer Head)
ector) substrate 110 print control device 601 recording head unit 602 front head 603 rear head

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroshi Endo 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Tsuyoshi Ozasa 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inside (72) Inventor Makoto Katsuma 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term (reference) 2C057 AF30 AF31 AF39 AF91 AG12 AH15 AJ03 AM03 AM28 AM40 AN01 CA05 4H057 AA02 AA03 DA01 DA34 FA23 FA24 GA06 GA11 5C074 AA02 BB16 DD03 DD24 DD28 FF13 FF15 GG09 HH02 5C077 LL04 MM22 MP06 MP08 NN02 NN11 PP15 PP33 PP38 RR02 RR08 RR16 RR19 SS02 TT05 TT06

Claims (14)

[Claims] 1. An image forming apparatus for forming an image on a predetermined area of a recording medium by an image having a complementary relationship for each color by scanning a plurality of recording heads corresponding to a plurality of colors a plurality of times, Distributing means for distributing the multi-valued image data corresponding to each of the plurality of scans for each color; Driving the plurality of recording heads in the plurality of scans based on the image data for each color whose gradation has been reduced by the gradation lowering unit, and performing the complementing relationship for each color. Forming means for forming an image having at least one of the distributing means and the gradation lowering means for reducing a complementary relation of an image for each color formed by the forming means and a correlation between the colors. Do An image forming apparatus comprising. 2. An image forming apparatus according to claim 1, wherein said gradation lowering means is a binarizing means. 3. An image forming apparatus according to claim 1, wherein said distribution means distributes multi-valued image data of each color corresponding to said predetermined area differently in said plurality of scans. 4. An image forming apparatus according to claim 1, wherein said gradation lowering means lowers the gradation of multi-valued image data by an error diffusion method. 5. An image forming apparatus according to claim 4, wherein said gradation lowering means makes error diffusion different for multi-valued image data for each color and each scan distributed by the distribution means. . 6. The image processing apparatus according to claim 4, wherein the gradation lowering unit changes the threshold value of the gradation lowering for the multi-valued image data for each color and each scan distributed by the distribution unit. Image forming device. 7. The image forming apparatus according to claim 1, wherein the recording head discharges ink. 8. The image forming apparatus according to claim 1, wherein the recording medium is a fabric. 9. The recording medium according to claim 1, wherein the plurality of recording heads include first and second heads arranged in a sub-scanning direction of a recording medium for each color, and the predetermined area is defined by the first and second heads. An image forming apparatus formed by a second head. 10. The image forming apparatus according to claim 1, wherein the recording head has a plurality of recording elements, and the predetermined area is formed by the plurality of different recording elements. 11. An image forming apparatus for forming an image on a predetermined area of a recording medium by a plurality of scans of a plurality of recording heads corresponding to a plurality of colors, wherein a multi-valued image of each color corresponding to the predetermined area is provided. Distributing means for distributing data differently in the plurality of scans; and low-gradation means for lowering the multi-valued image data of each color distributed by the distributing means by different processing for each color; Forming means for forming an image by driving the plurality of recording heads in the plurality of scans based on the image data of each color reduced in tone by the tone reducing means. Image forming device. 12. An image forming apparatus which forms an image on a predetermined area of a recording medium by a plurality of scans of a plurality of recording heads corresponding to a plurality of colors, wherein a multi-valued image of each color corresponding to the predetermined area is provided. Distributing means for distributing data corresponding to the plurality of scans; and low-gradation means for lowering the multi-valued image data for each color and each scan distributed by the distributing means by different processing. And forming means for forming an image by driving the plurality of recording heads in the plurality of scans based on the image data of each color reduced in tone by the tone reducing means. Image forming apparatus. 13. An image forming method for forming an image on a predetermined area of a recording medium by an image having a complementary relationship by a plurality of scans of a plurality of print heads corresponding to a plurality of colors, wherein An image forming method, wherein an image for each color corresponding to a predetermined area is formed in an incomplete complement relation, and an image between the colors is formed in an incomplete correlation. 14. An image processing method for forming an image on a predetermined area of a recording medium by an image having a complementary relationship by a plurality of scans of a plurality of print heads corresponding to a plurality of colors, wherein the plurality of scans In order to form an image for each color corresponding to the predetermined area in an incomplete complement relation and to form an image between the colors in an incomplete correlation, the image is supplied to the plurality of recording heads in the plurality of scans. An image processing method characterized by processing power image data.