JPH09183238A - Ink-jet recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reproduce normal color by increasing density sufficiently, for example, even in a picture element which is formed by low density ink by forming a picture element of a specified color by multiple printing in which ink of a specified color is sprayed repeatedly. SOLUTION: First, it is judged whether a set printing mode is a color printing mode or not (S1), and when judged to be the color printing mode, color printing data to be printed are input (S2). When the color printing data are expressed by an RGB image signal, the color signal is converted from the RGB image signal into a CMY signal, and an ink quantity is determined on the basis of the CMY signal (S3). After that, the CMY signal is corrected on the basis of the ink quantity (S4), and the dot image data of each color are prepared by binary conversion processing using a dither method, an error diffusion method, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus for printing by ejecting ink onto a recording medium.

[0002]

2. Description of the Related Art An information processing device such as a personal computer is usually connected to a recording device capable of recording data such as characters and figures as visual information on paper. This printing apparatus employs various printing methods such as impact method, heat-sensitive method, and inkjet method. In recent years, an inkjet method that is excellent in quietness and can be suitably printed on paper of various materials has been adopted. The ink jet recording device adopted is drawing attention.

In the above-mentioned ink jet recording apparatus, a recording head having nozzle groups arranged in the sub-scanning direction and a sheet are arranged so as to face each other, and ink is ejected from the nozzles while the main scanning of the recording head is performed to spray the sheet. After printing for one band, the printing process of sub-scanning this paper for one band width is repeated to print the entire surface of the paper. When performing color printing with such an ink jet recording apparatus, conventionally, recording heads for each color are arranged in the main scanning direction so as to eject each ink of cyan, magenta, yellow, and black. However, when the recording heads are main-scanned, the ejection timings of the inks are shifted and the inks of a single color or a plurality of colors are sprayed in one pixel, so that the pixels of a plurality of colors are mixed in one band.

[0004]

However, in the above-described conventional configuration, since the density of each color ink is different,
There is a difference in density between pixels formed by superimposing one ink or a plurality of inks at the same dot position, and in a pixel formed by ink of low density,
Since the ink density is low, there is a problem that a regular color may not be reproduced. Further, since the ink is sprayed once to the single-color pixels, there is also a problem that it is not possible to perform color printing that emphasizes the specific-color pixels.

Therefore, according to the present invention, for example, even in a pixel formed of ink having a low density, it is possible to sufficiently increase the density to reproduce a normal color, and emphasize a pixel of a specific color to perform color printing. It is an object of the present invention to provide an inkjet recording device that can be used.

[0006]

In order to solve the above-mentioned problems, the invention of claim 1 has a recording head capable of ejecting inks of different colors, and the recording head is directed along a recording medium in a predetermined direction. In an ink jet recording apparatus capable of performing color printing in which pixels of a plurality of colors are mixed by spraying the ink onto a recording medium while reciprocating the ink, a multiplex printing process of spraying a specific color ink of the plurality of colors a plurality of times. Is provided with a specific color pixel forming means for forming a specific color pixel. Accordingly, in color printing, by forming the specific color pixel by spraying the ink of the specific color a plurality of times, for example, even when the density of the ink of the specific color is low, the density of the specific pixel is sufficiently supplemented. Therefore, a well-balanced high-quality color image can be obtained. Further, if the density of the ink of the specific color is sufficient, it is possible to perform color printing by emphasizing the pixels of the specific color.

According to a second aspect of the present invention, there is provided the ink jet recording apparatus according to the first aspect, wherein the ink of the specific color has a lower density than the inks of other colors. Accordingly, by forming the specific color pixel by spraying the ink of the specific color twice or more, it is possible to make the specific color pixel of sufficient density which is comparable to the pixels of other colors.

According to a third aspect of the present invention, there is provided a recording head capable of ejecting ink of plural colors including black, and the ink is sprayed onto the recording medium while reciprocating the recording head in a predetermined direction along the recording medium. Accordingly, in an inkjet recording apparatus capable of performing color printing in which black pixels and pixels of other colors are mixed, a black pixel forming unit for forming the black pixels by a multiple printing process of spraying the black ink a plurality of times is provided. It is characterized by doing. Accordingly, in color printing, by forming black pixels by spraying black ink a plurality of times, it is possible to sufficiently increase the optical density of the black pixels.
Therefore, it is possible to obtain a high-quality color image in which the black is tight and the contrast is sufficient.

According to a fourth aspect of the present invention, there is provided the ink jet recording apparatus according to the third aspect, wherein the multiplex printing process by the black pixel forming means includes spraying ink during forward movement of the recording head and returning during the backward movement. It is characterized by consisting of spraying ink. This makes it possible to form a black pixel by spraying black ink twice by only reciprocating the recording head. Therefore, for example, when performing color printing in the unidirectional printing mode,
Printing speed does not decrease.

A fifth aspect of the present invention is the ink jet recording apparatus according to the third or fourth aspect, wherein in the multiplex printing process by the black pixel forming means, the ink is sprayed at the same pixel position on the recording medium. I am trying. As a result, the optical density of the black pixels formed by spraying the black ink a plurality of times can be increased most efficiently.

According to a sixth aspect of the invention, there is provided the ink jet recording apparatus according to the third or fourth aspect, wherein the multiplex printing process by the black pixel forming means sprays the ink to different positions on the recording medium. There is. This makes it possible to increase the area of the black pixel formed by spraying the black ink a plurality of times to efficiently compensate for the insufficient density, or to emphasize it.

According to a seventh aspect of the present invention, there is provided the ink jet recording apparatus according to any of the third to sixth aspects, wherein the multiplex printing process by the black pixel forming means provides an appropriate distribution density among all black pixels. It is characterized in that the ink is sprayed a plurality of times only on the pixels specified as follows. As a result, it is possible to select black pixels according to the density of the ink to be used or to select the black pixels at the distribution density desired by the operator and perform the multiple printing process. The optimum image quality can be obtained.

According to an eighth aspect of the present invention, in the ink jet recording apparatus according to the seventh aspect, in the multiplex printing process by the black pixel forming means, the distribution density of specific pixels with respect to all black pixels is changed according to the type of print data. It is characterized by making changes. As a result, the black pixels can be selected with the distribution density suitable for the type of print data and the multiple printing process can be performed, so that a good image quality corresponding to the form of color printing can be obtained.

According to a ninth aspect of the present invention, there is provided the ink jet recording apparatus according to the seventh or eighth aspect, wherein in the multiplex printing process by the black pixel forming means, the distribution density of the specific pixels with respect to all the black pixels is made uniform. It is characterized by having done. As a result, it is possible to obtain the specific pixels that have been subjected to the multiple printing process in an evenly dispersed state regardless of the form of color printing.

According to a tenth aspect of the invention, there is provided the ink jet recording apparatus according to the seventh or eighth aspect, wherein in the multiplex printing process by the black pixel forming means, the distribution density of specific pixels with respect to all black pixels is calculated as the density of the printing area. It is characterized by changing according to. This makes it possible to obtain specific pixels that have been subjected to multiplex printing processing with a distribution density that corresponds to the density of the printing area, and thus it is possible to further improve the image quality of color printing.

According to an eleventh aspect of the present invention, in the ink jet recording apparatus according to the tenth aspect, in the multiplex printing process by the black pixel forming means, when the print data is text, the higher the density region, the higher the distribution density becomes. It is characterized by reducing. As a result, the multiple printing process is performed on the black pixels specified so as to have a distribution density suitable for color printing of text, so that a better image quality can be obtained.

According to a twelfth aspect of the invention, there is provided the ink jet recording apparatus according to the tenth aspect, wherein the multiplex printing process by the black pixel forming means, when the print data is a photograph,
It is characterized in that the distribution density is increased as the concentration increases. As a result, the multiple printing process is performed on the black pixels specified so as to have a distribution density suitable for color printing of photographs, so that a better image quality can be obtained.

[0018]

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention will be described below with reference to FIGS. The inkjet recording apparatus according to the present embodiment is connected to an information processing apparatus 1 such as a personal computer as shown in FIG. The information processing device 1 is used for inputting and instructing data, a processing device main body 2 having a built-in auxiliary storage device such as a magnetic disk device and a central processing unit, a CRT (cathode-ray tube) 3 for displaying data and the like on a screen. It has a keyboard 4 and a mouse 5 and is connected to a printer 7 which is an ink jet recording apparatus via a printer cable 6 of Centronics specification, for example.

As shown in FIG. 5, the processing apparatus main body 2 is equipped with, for example, a window system 8 as an operating system (OS). The window system 8 includes an application 9 such as a document creation program, a font driver 10 for managing fonts, a CRT driver 11 for managing the CRT 3, a keyboard driver 12 for managing the keyboard 4, and a mouse driver 13 for managing the mouse 5. One or a plurality of applications 9 can be simultaneously executed in cooperation with various functional groups such as a printer driver 14 that manages the printer 7 which is an inkjet recording device.

The printer driver 14 has a frequency table for photographs and a frequency table for text graphs. As shown in FIG. 6, these frequency tables are data tables showing the relationship between the print density and the double print frequency of black pixels when the print data is a photograph and text or graph. . Specifically, the frequency table for photographs has data contents in which the double printing frequency of black pixels increases as the density increases (the area where the ratio of the number of black pixels to the total number of all pixels per fixed area is large). The frequency table for a text graph has
It has data contents such that the frequency of double printing decreases as the density increases. The double-printing frequency indicates the ratio of the number of black pixels formed by actually spraying the ink twice to the total number of pixels of double-printing target pixels, here black pixels. Is.

Then, when the "print execution" menu is specified for the data displayed on the screen of the CRT 3 for example, the printer driver 14 uses the preselected color print mode or monochrome print mode. Dot image data can be formed. In the color print mode, for example, based on the font data of the text to be printed and the pixel data of graphs, photographs, etc., yellow (Y), magenta (M) ), Cyan (C), and black (K) four-color dot image data (pixel data arranged in a dot matrix in the horizontal and vertical directions) is formed, and double printing of the frequency table is performed. Dot image data for double printing is formed for the black pixels specified based on the frequency. Is adapted to sequentially output from the interface (I / F) section 15 dot image data for each raster as the horizontal print data (raster direction) 8-bit units.

The print data output in the raster scan format as described above, as shown in FIG.
Is input to the I / F (interface) unit 16 of. This printer 7 includes a printer controller 17, print buffers 18a to 18d for storing print data for yellow (Y), magenta (M), cyan (C), and black (K), and head drive. It has a unit (print head driving unit) 19 and a motor driving unit 20. The motor drive unit 20 is connected to the CR motor 22 and is configured to rotate the CR motor 22 forward and backward. On the other hand, the head driving unit 19 includes print heads (recording heads) 21a to 21a for yellow (Y), magenta (M), cyan (C), and black (K).
21d. Each of these print heads 21a
Nozzles (not shown) for ejecting ink due to displacement of the piezoelectric elements are arranged in the sub-scanning direction in the sub-scanning direction, for example, for 64 channels.
A drive voltage from the head drive unit 19 is applied so as to displace the piezoelectric element.

The head drive unit 19 will be described in detail. As shown in FIG. 7, the head drive unit 19 is a buffer unit 33a including a buffer circuit provided corresponding to each nozzle of the print heads 21a to 21d. To 33d, gate sections 32a to 32d formed of 2-input AND circuits connected to the respective buffer circuits of the buffer sections 33a to 33d, and serial connected to one input side of each of the AND circuits of the gate sections 32a to 32d. -Parallel conversion circuit 31. The serial-parallel conversion circuit 31 takes in the dot-unit print data serially output from the print buffers 18a to 18d of FIG. 5 via the printer controller 17 at the input timing of the transfer clock and outputs the data in parallel. . In addition, the gate portion 32a
.About.32d are buffer units 33a to 33d when the print clock (Y, M, C, K) of the print data output in parallel is output, that is, when the print data becomes high level.
Are output to the buffer unit 33.
a to 33d output driving voltages (Y, M, C, and K) to the nozzles of the print heads 21a to 21d, respectively, when the input print data is at a high level. There is.

In this way, the print heads 21a to 21d to which the drive voltage is supplied from the head drive section 19 are arranged in the main scanning direction X as shown in FIG. It is fixed to the carriage 23 so as to form a predetermined angle. A guide shaft 24 horizontally provided in the main scanning direction X is movably inserted into the carriage 23, and a scanning belt 26 driven by the CR motor 22 is connected to the carriage 23 to drive the scanning belt 26. The CR motor 22 moves the carriage 2 along the guide shaft 24.
By reciprocating 3 in the main scanning direction X, the print heads 21a to 21d are main-scanned while keeping a constant distance from the paper 25.

On the lower surface of the carriage 23, an encoder element 2 including a non-contact type sensor such as an optical type or a magnetic type is provided.
7 are provided. In the detection direction of the encoder element 27, a timing slit 28 having a large number of slit portions 28a at equal intervals is provided in parallel with the guide shaft 24.
At the same time, when it moves in the main scanning direction X, the slit portion 28a of the timing slit 28 is detected and output as an encoder signal.

The encoder signal is input to the printer controller 17, as shown in FIG. The printer controller 17 has a print timing generator 34, a buffer controller 35, a CPU 38, an I / F controller 42, and a print controller 43. Then, the print timing generator 34 and the buffer controller 35
The I / F control unit 42 and the print control unit 43 are connected to the ASIC.
The ASIC unit 39 is integrally formed by a hard logic circuit such as (Application Specific Integrated Circuit).

The print timing generating section 34 constituting the ASIC section 39 forms a print timing signal as a print clock on the basis of the encoder signal, and the print timing signal is supplied to the buffer control section 35 and the print control section. It is designed to output to 43. The buffer control unit 35 includes a DMA controller, an address generator, and the like, and stores the print data input via the I / F unit 16 in the print buffers 18a to 18d and the print buffers 18a to 18d. A read process is executed to read the selected print data at a predetermined timing and output it to the print control unit 43.

That is, the write processing and the read processing will be specifically described. Each of the print buffers 18a to 18a.
In d, as shown in FIGS. 10A and 10B, for example, 64 rasters are arranged in a matrix of a horizontal direction (raster direction) corresponding to the main scanning direction X and a vertical direction corresponding to the sub scanning direction. A data table is formed. This data table is divided into 8-bit data areas, which are the transmission units of print data, and when write processing is performed, print data is sequentially output in the same raster scan format as that output from the information processing apparatus 1. It is designed to be stored in each data area. On the other hand, when the reading process is performed, the print data in the vertical direction, which is the sub-scanning direction, is sequentially read in the horizontal direction from the left end in the drawing.

The print data read from each of the print buffers 18a to 18d by the above-described read processing is output to the print control unit 43 as shown in FIG. Then, the print control unit 43 uses the print head 21a read from each of the print buffers 18a to 18d.
The print data corresponding to the nozzles 21d to 21d is temporarily stored, and then the print data is sequentially sent to the head drive unit 19 in dot units.

The operation of the ink jet recording apparatus having the above structure will be described. First, as shown in FIG. 4, when the instruction data is input by the keyboard 4 or the mouse 5 to start printing (the menu of "print execution" is designated), the window system 8 of FIG. -By operating the driver 14, the print processing routine will be executed. In the following operation, the printer driver 14 of the information processing device 1
And the CPU section 38 of the printer 7 functions as a specific pixel forming unit.

That is, as shown in FIG. 1, first, it is determined whether or not the setting content of the print mode is the color print mode (S1), and if it is determined that the color print mode is set (S1, If YES, the color print data to be printed (for example, halftone RGB image signal) is input (S2). The color print data is an RGB image signal, that is, data relating to red, green, and blue (RGB
Signal), the signals are converted into signals (CMY signals) relating to cyan, magenta, and yellow colors.
The color signal is converted from the RGB image signal into the CMY signal, and the black amount (K value) is determined based on the CMY signal (S3). After that, the CMY signal is corrected based on the black amount (K value) (referred to as undercolor removal (UCR)) (S4), and further, a binary value using a dither method, an error diffusion method, or the like. By the conversion processing, dot image data of each color is created (S5).

Next, it is determined whether or not the type of print data composed of dot image data is a photograph (S6). When it is determined that the print data is a photograph (S6, YES), the ratio of double printing is specified for the black (K) dot image data created in S5. The double printing frequency is calculated from the frequency table for photographs, and predetermined black pixels (dots) are specified so as to have the distribution density of the double printing frequency. At this time, the black pixels are specified by referring to a frequency table as shown in FIG. 6, and an appropriate distribution density is selected from all the black pixels according to the density of the ink used or the operator's preference. May be performed so as to obtain a uniform distribution density, and further, depending on the density of the print area, that is, in all pixels (dots) per fixed area. It may be performed so as to change according to a ratio indicating how many black pixels are present. Then, dot image data for double printing is created for the black pixel specified in this way (S7).

On the other hand, if it is determined that the print data is not a photograph (S6, NO), the double printing frequency is text.
A predetermined black pixel (dot) is specified by the same specifying method as in S7 so that the distribution density of the double printing frequency is obtained from the frequency table for the graph.
Then, for the black pixel specified in this way,
Dot image data for double printing is created (S8).

When the dot image data for double printing is created by the above S7 and S8, the double printing processing routine is executed so that the color printing including the black double printing is performed subsequently. (S9). That is,
As shown in FIG. 2, when a color print mode setting command is sent to the printer 7, a data area for the print buffers 18a to 18d is formed so that the printer controller 17 can perform color printing. (S11). After that, "1" is set to the print row designation pointer n (S12), and the dot image data of cyan color (C), magenta color (M), yellow color (Y), and black color (K) is printed. The data is transmitted and stored in the print buffers 18a to 18d (S13).

When the print data for one band is stored in the print buffers 18a to 18d, the CR motor 22 is rotationally driven in the positive direction, and the print heads 21a to 21d are scanned in the main scanning direction X, as shown in FIG. The forward movement (movement to the right) of will be started. After this, the print head 21
When a to 21d reach the print start position when moving to the right, as shown in FIG. 9, cyan (C), magenta (M), yellow (Y), and black (from the print buffers 18a to 18d) By transferring the print data of K) to the print control unit 43 by the buffer control unit 35, the inks of the respective colors are ejected from the print heads 21a to 21d at a predetermined timing, and pixels of a plurality of colors are mixed in the right direction. Color printing will be performed.

While such one-band color printing is being performed, the printer driver 14 of the information processing apparatus 1 of FIG. 5 determines whether or not the right color printing has been completed ( If it is determined that the color printing is not completed until the printing is completed (S14) (S1).
4, NO), and the determination in S14 is repeated. Then, when it is determined that the color printing in the right direction is completed (S14, YES), S7 and S in FIG.
The black (K) dot image data determined in 8 is transmitted as print data and stored in the black (K) print buffer 18d (S15).

When one band of black (K) print data is stored in the print buffer 18d, the CR motor 22 is rotationally driven in the reverse direction as shown in FIG.
The return movement (movement to the left) of the print heads 21a to 21d in the main scanning direction X is started. After that, when the print heads 21a to 21d reach the print start position when moving to the left, as shown in FIG. 9, black (K) print data is transferred from the print buffer 18d to the print control unit 43 by the buffer control unit 35. As a result, black ink is ejected from the print head 21d at a predetermined timing. As a result, by the color printing in the right direction, the ink is sprayed a second time on a specific black pixel (dot) in one band in which pixels of a plurality of colors are mixed. Incidentally, the second ink spraying on the black pixels may be performed at the same position as the first ink spraying position, or at a different position, for example, an intermediate position of each pixel (dot) formed during the forward movement. May be used, or the position may be slightly deviated. Further, it may be a position different in the sub-scanning direction or a position deviated in both the main scanning direction and the sub-scanning direction. In this case, the paper 25 is moved by a predetermined amount in the sub-scanning direction before the print head is moved back. It can be carried out by sending.

While such second printing for one band is being performed, the printer driver 14 of the information processing apparatus 1 shown in FIG. 5 determines whether leftward printing has been completed. (S16) If it is determined that the printing is not completed (S16, NO), the determination in S16 is repeated until the printing is completed. When it is determined that the printing in the left direction is completed (S
16, YES), and then it is determined whether or not the printing for one page has been completed (S17). If it is determined that the printing has not been completed (S17, NO), the print line designation pointer n
Is incremented by 1 (S18), and the paper 25 is fed by one band (when the paper is fed by a predetermined amount before leftward printing, the remaining amount) by the paper feeding, driving of a motor, etc., not shown. After that, the process is re-executed from S13 described above, and printing for one band of the next line is performed. On the other hand, if it is determined that the printing of one page has been completed (S17, YE
S), the routine returns from this routine to the print processing routine of FIG. 1, and the print processing routine ends.

Next, as shown in FIG. 1, when it is determined in S1 that the setting contents of the print mode is not the color print mode (S1, NO), the black and white print processing routine is executed ( S10). That is, as shown in FIG. 3, monochrome print data to be printed is input (S2
1) Based on this data, black (K) dot image data is created (S22). When the black (K) dot image data is created, a monochrome print mode setting command is sent to the printer 7 via the I / F units 15 and 16 shown in FIG. On the other hand, a data area of the black-and-white print buffer is formed so that black-and-white printing can be performed (S23).

After that, "1" is set to the print line designation pointer n (S24), and the black (K) dot image data is transferred to the black and white print buffer as print data, and the print head 21d is used. Printing for one band is performed using only black ink (S2
5). When the printing for one band is repeatedly performed (S25, S26, S27, S28) and the printing for one page is completed (S27, YES), the print process of FIG. The routine returns to the routine, and the print processing routine ends.

As described above, in the ink jet recording apparatus according to the present embodiment, when performing color printing in which cyan, magenta, yellow, and black inks are ejected and pixels of a plurality of colors are mixed, black printing is performed. 2 black ink for pixels
The double-printing process of spraying twice is performed. Accordingly, by forming the black pixel (dot) by spraying the black ink twice, it is possible to obtain the black pixel (dot) having a high optical density (large OD value). Therefore, it is possible to print a color image having a tight black color and a sufficient contrast and a high image quality.

In the present embodiment, the case where the double printing process is performed on the black pixel has been described, but the present invention is not limited to this, and the pixel of the specific color is subjected to the specific color. It is also possible to perform a multiplex printing process in which ink is sprayed twice or more. For example, yellow (Y)
When the density of the ink is low, the double-printing process of the yellow ink is executed, so that the full-color printing balanced with other colors can be performed.

Further, in the present embodiment, the double printing process is carried out using the black ink under the condition that the four color inks of cyan, magenta, yellow and black are used. Although the case has been described, the present invention is not limited to this, and inks of different colors may be used. Further, the ink to be subjected to the multiple printing process such as the double printing process does not necessarily have to be the ink having the low density. That is, when the multiple printing process is performed on the pixel formed by the ink having a low density, the image density excellent in color balance can be obtained by supplementing the density of the ink. When the multiple printing process is performed on the ink that can obtain a sufficient density even by spraying, color printing can be performed by emphasizing the pixels (dots) formed by this ink.

Further, in the present embodiment, as shown in FIG. 1, the distribution density is changed according to the density depending on the type of print data (photograph, text, etc.) in S6 to S8. Without being limited to this, for example, by deleting S6 to S8, all black pixels (dots) are irrespective of the type or density of print data.
Multiple print processing may be performed for
A certain proportion of all black pixels (dots), eg 4
The multiple printing process may be performed such that only 0% of the black pixels are uniform in all areas. In this case, 100% of all black pixels may be printed at the time of color printing in the right direction and then 40% of black pixels may be overprinted at the time of printing in the left direction, or all the black pixels may be printed at the time of color printing in the right direction. After printing only 70% of the black pixels, the remaining 30% and 40% of the black pixels (dots) for multiple printing may be printed when printing in the left direction.

By the way, in this embodiment, the printer driver 14 of the information processing apparatus 1 is used to control C, M, Y, and K.
The dot image data for double printing is created based on the black (K) dot image data when the dot image data for each color is created, but the invention is not limited to this. For example, when performing multiplex printing processing on all black pixels (dots), or when performing multiplex printing processing only on a certain proportion of black pixels with uniform density, the information processing apparatus 1 may be used to print When the dot image data of each color of C, M, Y, K is transferred to the 7 side, the CPU unit 38 which is the main control means of the printer controller 17 causes the dot image data of (K) for double printing. May be created. In this case, the CPU unit 3 on the printer 7 side
A specific color pixel forming means is constituted by 8.

Further, the print buffers 18a to 18d have a capacity capable of storing print data for at least one page, and print data (dot image data) in all lines for one page is transferred from the information processing device 1 to the printer 7 in advance. If it is possible to transfer the data to all the users at once, the frequency table for photographs and the frequency table for text graphs as shown in FIG. 6 should be stored in a read-only memory (ROM). Thus, the dot image data for double printing may be created from the black (K) dot image data of the print buffer 18d based on the program control of the CPU section 38 which is the main control means on the printer 7 side. According to this, similarly to the above-described embodiment, it becomes possible to appropriately change the distribution density of black pixels for performing multiple printing according to the type of print data, according to the density, and to obtain high-quality color. Images can be obtained.

[0047]

According to the invention of claim 1, there is provided a recording head capable of ejecting inks of different colors, and the ink is sprayed onto the recording medium while reciprocating the recording head in a predetermined direction along the recording medium. As a result, in an inkjet recording apparatus capable of performing color printing in which pixels of a plurality of colors are mixed, a specific color pixel forming unit that forms a specific color pixel by multiple printing processing in which ink of a specific color of the plurality of colors is sprayed multiple times It is a structure having. Thus, in color printing, by forming the specific color pixel by spraying the ink of the specific color a plurality of times, for example, even if the density of the ink of the specific color is low, the density of the specific color pixel can be sufficiently increased. It is possible to make up for it and obtain a well-balanced high-quality image. Further, if the density of the ink of the specific color is sufficient, there is an effect that it is possible to perform color printing in which the pixels of the specific color are emphasized.

According to a second aspect of the invention, there is provided the ink jet recording apparatus according to the first aspect, wherein the ink of the specific color has a smaller density than the inks of other colors. Thus, by forming the specific color pixel by spraying the ink of the specific color twice or more, it is possible to obtain the specific color pixel of sufficient density which is comparable to the pixels of other colors.

According to a third aspect of the present invention, there is provided a recording head capable of ejecting ink of a plurality of colors including black, and the ink is sprayed onto the recording medium while reciprocating the recording head in a predetermined direction along the recording medium. Accordingly, in an inkjet recording apparatus capable of performing color printing in which black pixels and pixels of other colors are mixed, a black pixel forming unit for forming the black pixels by a multiple printing process of spraying the black ink a plurality of times is provided. This is the configuration. Accordingly, in color printing, by forming black pixels by spraying black ink a plurality of times, it is possible to sufficiently increase the optical density of the black pixels. Therefore, there is an effect that it is possible to obtain a high-quality color image in which the black is tight and the contrast is sufficient.

According to a fourth aspect of the present invention, there is provided the ink jet recording apparatus according to the third aspect, wherein the multiplex printing process by the black pixel forming means includes spraying ink during forward movement of the recording head and returning during the backward movement. This is a structure including spraying of ink. This makes it possible to form black pixels by spraying black ink twice by only moving the recording head back and forth once. For example, when color printing is performed in the unidirectional printing mode, the printing speed is increased. Has the effect of not decreasing.

A fifth aspect of the present invention is the ink jet recording apparatus according to the third or fourth aspect, wherein the multiplex printing process by the black pixel forming means is configured to spray the ink onto the same pixel position on the recording medium. . As a result, the optical density of the black pixels formed by spraying the black ink a plurality of times can be effectively increased.

According to a sixth aspect of the invention, there is provided the ink jet recording apparatus according to the third or fourth aspect, wherein the multiplex printing process by the black pixel forming means is configured to spray the ink onto different positions on the recording medium. As a result, there is an effect that the area of the black pixel formed by spraying the black ink a plurality of times can be increased to efficiently compensate for the insufficient density or to emphasize it.

According to a seventh aspect of the present invention, there is provided the ink jet recording apparatus according to any of the third to sixth aspects, wherein the multiple printing process by the black pixel forming means has an appropriate distribution density among all black pixels. The ink is sprayed a plurality of times only on the pixels specified as described above. As a result, it is possible to select black pixels according to the density of the ink to be used or to select the black pixels at the distribution density desired by the operator and perform the multiple printing process. Therefore, the optimum image quality can be obtained.

According to an eighth aspect of the present invention, in the ink jet recording apparatus according to the seventh aspect, in the multiplex printing process by the black pixel forming means, the distribution density of specific pixels for all black pixels is changed according to the type of print data. It is a structure that changes. As a result, the black pixels can be selected with the distribution density suitable for the type of print data and the multiple printing process can be performed, so that there is an effect that a good image quality can be obtained for the form of color printing.

According to a ninth aspect of the present invention, there is provided the ink jet recording apparatus according to the seventh or eighth aspect, wherein in the multiplex printing process by the black pixel forming means, the distribution density of the specific pixels with respect to all the black pixels is made uniform. This is the configuration. As a result, it is possible to obtain the specific pixels that have been subjected to the multiple printing process in an evenly dispersed state regardless of the form of the color printing.

According to a tenth aspect of the present invention, there is provided the ink jet recording apparatus according to the seventh or eighth aspect, wherein in the multiplex printing process by the black pixel forming means, the distribution density of specific pixels with respect to all black pixels is calculated as the density of the printing area. The configuration is changed according to. This makes it possible to obtain specific pixels that have been subjected to multiplex printing processing at a distribution density according to the density of the printing area, and thus it is possible to further improve the image quality of color printing.

According to an eleventh aspect of the present invention, in the ink jet recording apparatus according to the tenth aspect, in the multiplex printing process by the black pixel forming means, when the print data is text, the higher the density region, the higher the distribution density becomes. It is a structure to lower. As a result, the multiple-printing process is performed on the black pixels specified so that the distribution density is suitable for the color printing of the text, so that it is possible to obtain a better image quality.

According to a twelfth aspect of the invention, there is provided the ink jet recording apparatus according to the tenth aspect, wherein the multiplex printing process by the black pixel forming means, when the print data is a photograph,
The distribution density is increased as the concentration increases. As a result, the multiple-printing process is performed on the black pixels specified so that the distribution density is suitable for color printing of photographs, so that it is possible to obtain a better image quality.

[Brief description of the drawings]

FIG. 1 is a flowchart of a print processing routine.

FIG. 2 is a flowchart of a double printing processing routine.

FIG. 3 is a flowchart of a monochrome printing processing routine.

FIG. 4 is a perspective view of an inkjet recording apparatus to which an information processing apparatus is connected.

FIG. 5 is a block diagram of an information processing device and an inkjet recording device.

FIG. 6 is a graph showing the relationship between double printing frequency and density.

FIG. 7 is a circuit diagram of a head drive unit.

FIG. 8 is a perspective view of a main part of the inkjet recording apparatus.

FIG. 9 is a block diagram including an ASIC unit.

10A and 10B are explanatory diagrams showing a data area of a print buffer, FIG. 10A is a diagram showing a bit state, and FIG. 10B is a diagram showing a dot state.

[Explanation of symbols]

 1 Information Processing Device 14 Printer Driver (Specific Color Pixel Forming Means) 16 I / F Unit 17 Printer Controller 18a to 18d Print Buffer 19 Head Drive Unit (Print Head Drive Unit) 20 Motor Drive Unit 21a to 21d Print Head (Record Head) ) 22 CR motor 23 carriage 24 guide shaft 25 paper 26 scanning belt 27 encoder element 28 timing slit 35 buffer control section 38 CPU section (specific color pixel forming means) 39 ASIC section

Claims (12)

[Claims] 1. A pixel having a plurality of colors is provided, comprising a recording head capable of ejecting inks of different colors, and spraying the ink on the recording medium while reciprocating the recording head in a predetermined direction along the recording medium. In an ink jet recording apparatus capable of performing mixed color printing, a specific color pixel forming unit for forming a specific color pixel by a multiplex printing process of spraying a specific color ink of the plurality of colors a plurality of times is provided. Characteristic inkjet recording device. 2. The ink jet recording apparatus according to claim 1, wherein the ink of the specific color has a lower density than the inks of other colors. 3. A black pixel having a recording head capable of ejecting a plurality of colors of ink including black, and spraying the ink onto the recording medium while reciprocating the recording head in a predetermined direction along the recording medium. In an inkjet recording apparatus capable of performing color printing in which pixels of other colors are mixed, a black pixel forming unit for forming the black pixels by multiple printing processing in which the black ink is sprayed a plurality of times is provided. Characteristic inkjet recording device. 4. The multiplex printing process by the black pixel forming means includes spraying ink during forward movement of the recording head,
4. The ink jet recording apparatus according to claim 3, wherein the ink jetting is performed during the backward movement. 5. The ink jet recording apparatus according to claim 3, wherein in the multiplex printing process by the black pixel forming means, the ink is sprayed at the same pixel position on the recording medium. 6. The ink jet recording apparatus according to claim 3, wherein the multiple printing process by the black pixel forming means sprays the ink onto different positions on a recording medium. 7. The multiple printing process by the black pixel forming means is characterized in that ink is sprayed a plurality of times only on the pixels specified to have an appropriate distribution density out of all black pixels. The inkjet recording device according to any one of 1. 8. The ink jet recording apparatus according to claim 7, wherein the multiplex printing process by the black pixel forming means changes the distribution density of specific pixels with respect to all black pixels according to the type of print data. 9. The ink jet recording apparatus according to claim 7, wherein in the multiplex printing process by the black pixel forming means, the distribution density of specific pixels with respect to all black pixels is made uniform. 10. The ink jet recording according to claim 7, wherein in the multiplex printing process by the black pixel forming means, the distribution density of specific pixels with respect to all black pixels is changed according to the density of the printing area. apparatus. 11. The ink jet recording apparatus according to claim 10, wherein, in the multiplex printing process by the black pixel forming means, when the print data is text, the distribution density is lowered as the density of the print data increases. 12. The ink jet recording apparatus according to claim 10, wherein, in the multiplex printing process by the black pixel forming means, when the print data is a photograph, the distribution density is increased in a region of higher density.