Patent Grant
7290858
The present invention relates to an ink jet printing method and an ink jet printing apparatus and, more particularly, to an ink jet printing method and an ink jet printing apparatus for performing so-called preliminary ejection, in which ink is ejected from a printing head for taking no part of printing, is performed while printing an image.
Also, the present invention can be applied to apparatuses such as a printer, a copying machine, a facsimile machine having a communication system, a word processor having a printer section and so on for printing on a medium to be printed such as paper, yarn, fiber, fabric, metal, plastic, rubber, glass, wood, ceramics and so on and, moreover, industrial printing apparatuses combined complexly with various processing units.
It should be appreciated that “printing” in the present specification means not only to afford images having a meaning such as characters and graphics to the medium to be printed, but also to afford images having no meaning such as patterns.
The preliminary ejection in an ink jet printer is performed to discharge highly viscous ink and dust in an ink ejection orifice of a printing head through ink ejection thereof so as to keep the ejection performance of the printing head satisfactory. It is also executed for avoiding density unevenness on a printed image by ejecting ink whose concentration of color material such as dye and pigment has increased. Usual manners of such preliminary ejection include, in the case of a serial method of printing by causing the printing head to scan, the ink ejection is performed, for the preliminary ejection, to an ink receptacle disposed at one end of the scanning area. Further, in the case of a full line method for printing by moving a printing medium with respect to a printing head whose ink ejection orifices are arranged in correspondence to the width of the printing medium, the ink receptacle is moved relatively to the printing head to oppose thereto and ink is ejected to the same.
On the other hand, those of which ink is ejected for the preliminary ejection while an image is printed on the printing medium are also known. For instance, it is described to perform the preliminary ejection at a constant frequency for the ink ejection for printing, in Japanese Patent Application Laid-Open No. 1980-139269. According to such preliminary ejection, it is not necessary for the printing head to move for preliminary ejection as in the case of performing the preliminary ejection to a predetermined ink receptacle disposed in the printer. Therefore, it becomes possible to prevent the throughput of printing from lowering as much. Even when the ejection is not performed for certain ejection orifices during the printing in relation with the printing data, the preliminary ejection can be performed for these ejection orifices, because this method for performing the preliminary ejection to the printing medium (also referred as “paper preliminary ejection” in the present specification) is performed, basically, accompanying the ink ejection for printing an image. More specifically, during the printing, the printing is performed in a state where the printing head is not covered with a cap or the like and the ejection orifice part is exposed, and in this case, even when the ejection is not performed for certain ejection orifices according to the printing data, the ink ejection through preliminary ejection can be performed for these ejection orifices, allowing to effectively prevent ejection failure due to the exposed state.
Particularly, the paper preliminary ejection is effective in the case of printing on a relatively large sized printing medium. More specifically, in the case of printing on a large sized printing medium, the throughput tends to lower because as much time is necessary for the printing head to scan. The paper preliminary ejection is a method desirable for preventing the throughput from lowering. In addition, when printing on a large sized printing medium, the ejection orifice in the printing head remains exposed for a long period of time. However, the paper preliminary ejection is preferable as a method allowing ejecting of ink during this exposed state.
Furthermore, without limiting to the case of using the large sized printing medium, the paper preliminary ejection is preferable as a method allowing to eject ink for the printing head in the exposed state, when the ink uses pigment or the like, for instance, as a color agent and tends to become highly viscous by coagulation.
However, the paper preliminary ejection sometimes degrades the image quality for usual ink jet printers in which the printing is performed using a plurality of ink colors. For example, ink dots of a plurality of low-lightness colors are sometimes formed on the printing medium in a concentrated manner, in the case of performing the paper preliminary ejection for each one of a plurality of ink colors at a constant frequency, as described in Japanese Patent Application Laid-Open No. 1980-139269. These concentrated dots of the plurality of low-lightness colors are so conspicuous as they are perceived by a viewer of the printed image, and then the printed image is degraded.
The present invention can provide an ink jet printing method and an ink jet printing apparatus which can perform paper preliminary ejection that would not bring the deterioration of image quality due to dots of low-lightness colors.
In the first aspect of the present invention, there is provided an ink jet printing method that uses a printing head for ejecting a plurality of colors of ink on a printing medium to perform printing, in which the plurality of colors of ink are ejected on the printing medium for preliminary ejection in conjunction with ink ejection for the performance of printing, the method comprising:
step for generating print data by adding preliminary ejection data for the preliminary ejection to print data based on an image to be printed; and
step for ejecting the plurality of colors of ink on the printing medium from the printing head, based on the generated print data,
wherein a dot pattern of the plurality of colors of ink formed based on the preliminary ejection data is a pattern having a relation that a distance between any two dots other than a dot of highest-lightness is longer than a distance between a dot nearest to the dot of highest-lightness and a dot of highest-lightness, among the plurality of colors of dots.
In the second aspect of the present invention, there is provided an ink jet printing apparatus that uses a printing head for ejecting a plurality of colors of ink on a printing medium to perform printing, in which the plurality of colors of ink are ejected on the printing medium for preliminary ejection in conjunction with ink ejection for the performance of printing, the apparatus comprising:
generating means for generating print data by adding preliminary ejection data for the preliminary ejection to print data based on an image to be printed; and
ejection means for ejecting the plurality of colors of ink on the printing medium from the printing head, based on the generated print data,
wherein a dot pattern of the plurality of colors of ink formed based on the preliminary ejection data is a pattern having a relation that a distance between any two dots other than a dot of highest-lightness is longer than a distance between a dot nearest to the dot of highest-lightness and a dot of highest-lightness, among the plurality of colors of dots.
According to the above structure, the dot pattern formed based on preliminary ejection data is a pattern having a relation that the distance between any two dots other than the dot of highest-lightness is longer than the distance between a dot nearest to the dot of highest-lightness and the dot of highest-lightness, among a plurality of color dots. Therefore, the interval between low-lightness color dots can be set longer, and then the dot pattern preventing these dots from being perceived as a group of collected dots can be designed easily. More specifically, when the patterns are designed under a condition to arrange a plurality of color dots in an area of a predetermined length, the interval between low-lightness color dots can be set longer than that in a pattern in which respective dots are arranged equally spaced. The predetermined length in the above condition can be determined as a length obtained by deriving the quantity of preliminary ejection (the number of times of ejection) necessary for a single scanning for one color ink during the printing for instance on printing paper of A3 format, based on viscosity increasing property of ink, scanning speed of the printing head, and the like, and dividing the width of the scanning direction of the A3 format printing paper by this number of times of ejection.
The printing can be realized without deteriorating the printing quality by the paper preliminary ejection, because forming dots which are perceived as a group of collected dots is prevented by using a preliminary ejection pattern as mentioned above.
The above and other objects, effects, features and advantages of the present invention will become more apparent from the following description of embodiments thereof taken in conjunction with the accompanying drawings.
Embodiments of the present invention will be described in detail referring to accompanying drawings. A printer shall be illustrated as an ink jet printing apparatus, in the embodiments described below.
The printing operation of the ink jet printer of the present embodiment described above referring to
When printing starts, printing papers 1 stacked in the cassette 15 are fed one by one to a printing area by a paper feed roller (not shown). Then, the printing head 22 scans in the printing area, and the printing paper is fed by a predetermined amount by a pair of transport rollers 3, on a platen (not shown) installed in an area to which the printing head 22 faces. On the other hand, ink is fed from the ink tank 21 to the printing head 22 and the printing head 22 ejects the ink on the printing paper 1 based on printing data, while scanning in the arrow B direction (forth scanning direction) of
The printing head 22 returns to the home position at a predetermined timing such as that before starting the printing, and performs a recovery operation by a recovery mechanism. More specifically, the ejection orifice face of the printing head 22 is capped with the cap 141 and ink in the ejection orifice 23 is sucked. Also, the above capping is performed during the non-printing, to prevent the ink from drying. Moreover, a wiper blade 143 wipes the ejection orifice 23 face of the printing head 22 by moving in the arrow C direction, to remove the ink attached to the ejection orifice face.
Further, as described later for
In the print engine control section 220, an MPU (Micro Processor Unit) 221 executes various operations, according to programs stored in a ROM 227. A RAM 228 is served as a working area and a temporary data storage area of the MPU 228. The MPU 221 controls a carriage driving system 223, a feed drive system 224, a recovery drive system 225 and a head drive system 226 via an ASIC (Application Specific Integrated Circuit) 222. Also, the MPU 221 is composed to read and write a print buffer 229 and a mask buffer 230 that can be read and written from the ASIC 222.
The print buffer 229 temporarily stores those image data converted into a format to be transferred to the printing head. The mask buffer 230 temporarily holds a predetermined mask pattern for exerting the AND processing to the data as necessary for multi-path printing when transferring from the print buffer 229 during the transfer to the printing head. It should be appreciated that several sets of mask patterns are available in the ROM 227 for multi-path printing different in the number of paths, a concerned mask pattern is read out from the ROM 227 during the actual printing, to be stored in the mask buffer 230. The AND processing with the mask buffer 229 is composed not to be executed when unnecessary as in the case of a single path printing.
In the aforementioned composition, the printing operation starts when image data are sent from the host device 200 to the image controller 210. The image controller 210 analyzes the image data received from the host device 200, generates printing quality, margin information or other information necessary for printing and moreover analyzes and develops the image data for starting the conversion into the binary image data of respective colors. Along with the development processing of these image data, information necessary for printing by the print engine control section 220 such as printing quality and margin information is transmitted to the print engine control section 220. Then, in the print engine control section 220, this transmitted information is processed by the MPU 221 via the ASIC 222 and held by the RAM 228. Thereafter, this information is referred to as necessary and used for segmenting the process. Furthermore, the mask pattern is written in the mask buffer 230 as necessary.
When the notification of necessary information is terminated, the image controller 210 starts to transfer the binary printing data of respective colors converted from the image data to the print engine control section 220. The print engine control section 220 writes the transferred printing data in the print buffer 229. And, as will be described later in
When the printing data held in the print buffer 229 attains such a quantity that allows printing the actual band data, the MPU 221 makes the paper transported by the carrying drive system 224 via the ASIC 222 and at the same time, moves the carriage 11 by the carriage driving system 223. Also, the recovery system is driven by the recovery drive system 225 for performing the recovery operation necessary before the printing operation. Furthermore, image output position and others are set for the ASIC 222 and the carriage 11 is driven to start the printing operation. When the carriage 11 moves and attains the printing start position set in the ASIC 222, printing data to which the aforementioned paper preliminary ejection pattern is added are read consecutively from the print buffer 229, in accordance with the ejection timing. Corresponding mask patterns are read from the mask buffer 230 as necessary. Then the AND (logical product) of the printing data read out and the mask data is determined and transferred to the printing head. In the printing head, the ejection is performed by driving the printing head according to the transferred data, under the control of the head driving system 226. Thus, for instance, a printing of one page is performed by repeating the processing of receiving the printing data from the image controller 210 and thereafter.
A printer driver 250, software for controlling the printer is preliminarily installed in the host device 200, and activated when a user intends to print a desired image. First, the printer driver 250 generates multi-value image data (here, respectively 8 bits) in RGB (red, green, blue) or KCMY (black, cyan, magenta, yellow) format of 600 dpi×600 dpi and transfers them to the printer. If the received image data are of RGB format, the image controller 210 performs a color conversion processing 500 from RGB to R′G′B′ in order to render a color space appropriate for the printer. Next, a color separating processing 510 is performed respectively from 8-bit data of R′G′B′ to multi-value data (here, respectively 8 bits) of K, LC, LM, C, M, Y of 600 dpi×600 dpi for adapting to the ink color used by the printer. On the other hand, if data received by the image controller 210 are of KCMY format, a color separating processing 510 is performed without performing the color conversion processing 500. Thus, respective color data corresponding to the ink color to be used by the printer is generated in the color conversion processing 510 independently of the data format generated by the printer driver 250. Colors are converted by means of a look-up table for a predetermined color conversion, in the color conversion processing 500 and the color separating processing 510. The look-up table may be held preliminarily in ROM data in a printer main body, the processing may also be executed based on the table transferred from the host device 200 with the printing data.
Following this, a quantization processing 520 from 8-bit (255 gradation values) data of K, LC, LM, C, M, Y to 4-bit (5 gradation values) for respective colors is performed. The quantization processing 520 is performed by using publicly known error dispersion method or dither method. The 4-bit (5 gradation values) data of quantized K, LC, LM, C, M, Y is submitted to an index development processing 530 mentioned below in
(“0000”, “0001”, “0010”, “0011”, “0100”) for 5 gradation values is set beforehand for the same. This setting pattern may be held in the ROM of the printer, or, downloaded from the host device together with the image data. 4-bit data of 600 dpi are developed by pixel unit based on the pattern of respective graduation level sets as mentioned above, to generate 1-bit (2 gradation values) data of 1200 dpi. In the print engine control section 220 preliminary ejection data are added as paper preliminary ejection generated beforehand as described later by OR (logical sum) to the data of 1-bit (2 gradation values) for respective colors of thus developed K, LC, LM, C, M, Y.
In
Reference numeral 360 represents the original point (X0, Y0) of the target pixel. In the case of forming an additional dot of preliminary ejection to this target pixel, ink ejection from an ejection orifice 310 will be applied. The pixel of coordinates (X0+4×X1, 1) gained by shifting by 4×X1 pixels in the X direction and 1 pixel in the Y direction from the original point 360 is a target pixel 361 to which ink from the ejection orifice 311 is applied. As mentioned above, X1 pixel corresponds to 75 pixels. Consequently, the target pixel 360 and the target pixel 361 are separated by 300 pixels (=4×X1 pixels) in the X direction. Similarly, the pixel of coordinate (X0+2×4×X1, 2) gained by shifting by 4×X1 pixels in the X direction and 1 pixel in the Y direction from the target pixel 361 to which ink is added by the ejection orifice 311 is a target pixel 362 to which ink from the ejection orifice 312 is applied. Further, the pixel of coordinate (X0+3×4×X1, 3) gained by shifting by 4×X1 pixels in the X direction and 1 pixel in the Y direction from the target pixel 362 is a target pixel 363 to which ink from the ejection orifice 313 is applied. In the pattern, when becoming Y0+3=Y1−1, the target pixel 364 to which ink from the ejection orifice 314 is added is repeated as (X0+X1, Y1). Thus, pixels in which ink is ejected for preliminary ejection can be determined all over the printing area, by repeating a paper preliminary ejection pattern of a size of 16×X1 pixels in the X direction and 16×Y1 pixels, which is a pattern unit for performing paper preliminary ejection to all of 16 ejection orifices, for the ink of one color. In the present embodiment, the unit of paper preliminary ejection pattern is a size of 1200 pixels in the X direction and 16 pixels in Y direction.
This pattern decision takes into account of the interval of pixels to be applied mutually by the ink color as described below in
Here,
The width d1 shown in
Here,
In
The conventional pattern 1206 is a pattern for arranging dots equidistant (distance 1211=distance 1212=distance 1213=distance 1214) independently of the color. That is, distance 1211 between cyan dot 1201 and magenta dot 1202, distance 1212 between magenta dot 1202 and light cyan dot 1203 and distance 1213 between light cyan dot 1203 and magenta dot 1204, that is, distance between relatively low-lightness colors of dot is set equal to the distance 1214 between these low-lightness colors of dot (light magenta in the pattern 1206) and the yellow dot 1205, which is relatively high-lightness color. Consequently, the distance between low-lightness colors becomes so short that dots of relatively low-lightness colors may be perceived as a group of collected dots in the printed image, thereby causing a granular feeling or the like and deteriorating the quality.
On the other hand, the pattern of the present embodiment, as shown in the pattern 1207 as one example of the embodiment, is determined so that the distance between relatively low-lightness colors, namely cyan dot 1201 and magenta dot 1202, is longer than the distance 1216 between the yellow dot 1205, relatively high-lightness color, and the cyan dot 1201 nearest to the yellow dot among low-lightness dots. Furthermore, the distance between the light magenta dot 1204 positioned at the rightmost end of one pattern unit existing in the range of the distance d1 and the cyan dot 1201 positioned at the leftmost end of the following pattern unit is set approximately equal to the distances between colors of dots from which the yellow dot is excluded. More specifically, the pattern shown in
Then, for the whole printing, the pattern of the paper preliminary ejection is so created under the relation of dots of other colors and this pattern 1207 that dots of respective colors repeat the basic pattern within the range of the distance d1 as mentioned before in
A pattern 1208, another example of patterns of the present embodiment, sets the low-lightness dot nearest the yellow dot 1205 as magenta 1202. Similarly, the pattern 1209, still another example, sets the low-lightness dot nearest the yellow dot 1205 as light cyan dot 1203, and the pattern 1210 sets the low-lightness dot nearest the yellow dot 1205 as light magenta dot 1204.
Though the arrangement of black ink dots is not described in the above examples, it is evident from the foregoing that a black dot, taken as a low-lightness color dot, can also be set as a pattern of six colors of ink, making the distance relation with the yellow dot same as dots of other low-lightness colors.
Though only the position of the original pixel 360 in the basic pattern of
Low-lightness dots for the paper preliminary ejection can be separated as far as possible, by establishing such relation among preliminary ejection positions of respective colors.
The width d2 shown in
Here,
In
The conventional pattern 1108 is a pattern for arranging dots equidistant (distance 1104=distance 1105) independently of the color. That is, distance 1104 between cyan dot 1101 and magenta dot 1102, is set equal to the distance 1105 between these dots of low-lightness colors (light magenta in this pattern) and the yellow dot 1103, relatively high-lightness color. Consequently, the distance between low-lightness colors becomes so short that dots of relatively low-lightness colors are perceived as a group of collected dots in the printing image, thereby causing sometimes a granular feeling or the like. Incidentally, in the pattern in which distances among each dot are equidistance, even if the magenta dot 1102 of low-lightness color is arranged at the rightmost end of the pattern unit and the yellow dot 1103 is arranged in the middle, the cyan dot 1101 comes at the leftmost end of the next pattern unit, thus the mutual distance (1106) between their dots is equal to the above distance 1104 (1105). Therefore, as shown in the above, distances among low-lightness colors can become such a short distance that dots of relatively low-lightness colors in the printed image can be perceived as a group of collected dots.
On the other hand, in the pattern of the present embodiment, with the pattern 1109 as an example thereof, the distance 1107 between cyan dot 1101 of relatively low-lightness color and magenta dot 1102 is longer than the distance 1111 between the yellow dot 1103 of relatively high-lightness color and the cyan dot 1101 nearest to the yellow dot among low-lightness colors. More specifically, when a pattern is designed under the condition to arrange dots of three colors in a range (similar to a direction orthogonal to this direction) of the same length d2, as shown in
In a pattern 1110, another example of patterns of the present embodiment, a low-lightness dot nearest the yellow dot 1103 is set as magenta dot 1102.
In the aforementioned first and second embodiments, preliminary ejection patterns are described in the case where the quantity (the number of times of ejection) of ink of respective colors is the same in paper preliminary ejection, while the present embodiment relates to a preliminary ejection pattern in the case where the quantity (the number of times of ejection) is differentiated according to the ink color.
As shown in the same drawing, the pattern 1113 is a pattern wherein the shortest distance 1115 among distances between cyan dot 1101 of relatively low-lightness and magenta dot 1102 is longer than the distance 1114 between the relatively high-lightness yellow dot 1103 and the cyan dot 1101 nearest the yellow dot among low-lightness colors. Also, the distance 1116 to cyan dot 1101 at the leftmost end of the adjacent pattern unit is also set equal to the long distance 1115. The printing can be performed without deteriorating the printing quality because of dots of the paper preliminary ejection, by using such patterns of preliminary ejection.
Though, in the aforementioned respective embodiments, a binary paper preliminary ejection pattern is added to the binarized printing data after the index development, data of the paper preliminary ejection pattern may be added to the printing data of index form. For instance, index data of 4 bits correspond to 2×2 in pixel of 1200 dpi×1200 dpi corresponding to the binary printing data. From this fact, these index data are the ones where the position thereof is homologized taking 2 pixels×2 pixels as one unit, in a dot pattern per a pixel shown in
A processing 540 for adding a paper preliminary ejection pattern is executed to 4-bit (5 gradation values) data of quantized K, LC, LM, C, M, Y. More specifically, the 4-bit (5 gradation values) data of quantized K, LC, LM, C, M, Y have any one value among “0000”, “0001”, “0010”, “0011”, “0100” as described in
Then, the printing data to which the preliminary ejection data are added are converted into printing data of 1-bit (2 gradation values) for respective colors of K, LC, LM, C, M, Y and transferred to the printer engine 220 as printing data containing the paper preliminary ejection data.
In addition, the present invention can also be applied to a composition for performing image processing in a printer driver of the host device.
In this composition, the printing operation starts by sending image data from the host device 200 to a reception buffer 250 of a print engine control section 220. The print engine control section 220 analyses the image data received from the host device 200 and generates information necessary for the printing such as printing data, printing quality, margin information. There, printing data, printing quality, margin information or the like are processed by an MPU 221 through an ASIC 222 and held in a RAM 228. Thereafter, this information is referred to as necessary and used for segmenting the process. Furthermore, the mask pattern is written in a mask buffer 230 as necessary. And, printing data to which the data of paper preliminary ejection are added can be created by taking the OR (logical sum) of preliminary ejection data which are preliminarily generated and the above, as printing data.
The present invention has been described in detail with respect to preferred embodiments, and it will now be apparent from the foregoing to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects, and it is the intention, therefore, that the appended claims cover all such changes and modifications.
This application claims priority from Japanese Patent Application No. 2004-177373 filed Jun. 15, 2004, which is hereby incorporated by reference herein.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2004-177373 | Jun 2004 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 6984009 | Nakagawa et al. | Jan 2006 | B2 |
| 7014292 | Yazawa et al. | Mar 2006 | B2 |
| 7029092 | Edamura et al. | Apr 2006 | B2 |
| Number | Date | Country |
|---|---|---|
| 55-139269 | Oct 1980 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20050275687 A1 | Dec 2005 | US |
