Patent Grant
7287825
1. Field of the Invention
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 unrelated to printing, 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.
2. Detailed Description of the Related Art
The preliminary ejection 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 a 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. A usual manner of such preliminary ejection is that, in the case of 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 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 relatvely 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, with 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. However, the paper preliminary ejection can partly replace normal preliminary ejection, which is performed at a predetermined position in a printing apparatus, or can be performed in place of the normal preliminary ejection. Thereby, time period for the normal preliminary ejection can be decreased as much and thus lowering of the throughput can be prevented. In addition, on focusing attention on an ejection orifice in the printing head, a non-ejection state of the ejection orifice, for which print data represents “non-ejection”, may continue, and then ink ejection from the ejection orifice may be executed by that the print data represents “ejection” during scanning of the printing head in the non-ejection state. In such case, when printing on a large sized printing medium, the ejection orifice in the printing head remains exposed for a long period of time. For this condition, the paper preliminary ejection is performed and then first ejection for printing after the exposed state can be well executed.
However, when the paper preliminary ejection is performed for different colors of inks without variation, unnecessary preliminary ejection may be performed and ink may be used wastefully. More specifically, a property of ink affecting ink ejection by the printing head, such as a degree of viscosity increasing of ink, generally depends on colors of ink. In such case, when the paper preliminary ejection of a constant period is performed for a plurality of colors of inks without variations, the paper preliminary ejection for the ink which does not increase viscosity during such constant period is also performed, and then the ink as much is used wastefully.
Particularly in the case of using both the normal preliminary ejection which is performed at a predetermined location in a printing apparatus and the paper preliminary ejection, there may be a case that depending on a color of ink, an ejection performance of a printing head for ejecting the color of ink can be maintained well only by the normal preliminary ejection. In this case, it is desirable that the paper preliminary ejection for the color of ink is not performed in terms of decreasing ink use for the preliminary ejection. A reason that properties of inks, such as viscosity increasing, affecting ink ejection by the printing head differ depending on colors of ink is that the properties differ depending on color materials in ink such as dye and pigment, and contents of the color materials of the same color inks, and further differ depending on other solvent in ink.
Further, the above discussion is the case with ejection amounts different for each printing head. Generally, the greater an amount (a volume of an ink droplet) of one time ejection is, the longer the time period during which a factor causing a ejection failure, such as increasing of ink viscosity, does not occur. Therefore, when the paper preliminary ejection of the constant period is performed for the plurality of colors of ink without variations, ink may be used wastefully for the printing head ejecting such greater amount of ink.
The present invention can provide a preliminary ejection method and an ink jet printing apparatus which can perform paper preliminary ejection in which unnecessary ink use is suppressed.
In a first aspect of the present invention, there is provided a paper preliminary ejection method, which is used in an ink jet printing apparatus in which ink is ejected from a printing head for ejecting a plurality of kinds of ink to a printing medium to print an image, for performing ink ejection of no concern to the image to be printed to the printing medium, the method comprising:
step for ejecting ink to the printing medium based on image data corresponding to the image to be printed to print the an image; and
step for causing the printing head to execute preliminary ejection to the printing medium, based on conditions related to the preliminary ejection,
wherein the conditions are individually determined for respective kinds of ink, and
the conditions are different between a kind of ink and other kind of ink within the plurality of kinds of ink.
In a second aspect of the present invention, there is provided a paper preliminary ejection method, which is used in an ink jet printing apparatus in which ink is ejected from a printing head for ejecting a plurality of kinds of ink to a printing medium to print an image, for performing ink ejection of no concern to the image to be printed to the printing medium, the method comprising:
step for, for each of the plurality of kinds of ink, determining information on predetermined time periods for each of plurality of frequencies for paper preliminary ejection including a lowest frequency at which no paper preliminary ejection is performed, the predetermined time period being defined as a time period elapsing after an operation of discharging ink from the printing head with the paper preliminary ejection being performed at the corresponding frequency, after the time period having been elapsed and upon starting of printing a predetermined image, no predetermined degradation of printed image occurring: and
step for, for each of the plurality of kinds of ink, comparing the predetermined time period for each of the plurality of frequencies with a time period from the operation of discharging ink to the next operation of discharging ink, and when the predetermined time period is shorter than the time period from the operation of discharging ink to the next operation of discharging ink, the performing the paper preliminary ejection at the frequency higher than the frequency corresponding to the predetermined time period for the corresponding ink.
In a third aspect of the present invention, there is provided an ink jet printing apparatus in which ink is ejected from a printing head for ejecting a plurality of kinds of ink to a printing medium to print an image, the apparatus comprising:
means for performing a preliminary ejection based on conditions related to the preliminary ejection that ejects ink of no concern to the image to be printed to the printing medium,
wherein the conditions are individually determined for respective kinds of ink, and
the conditions are different between a first ink and a second ink within the plurality of kinds of ink.
According to the present invention, conditions for paper preliminary ejection are individually set for plurality kinds of ink. Thereby, minimum amount of paper preliminary ejection can be performed for each of the plurality of kinds of ink.
As a result, the paper preliminary ejection in which unnecessary ink use is suppressed can be performed.
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 serves as a working area and a temporary data storage area of the MPU 221. 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 designed to read from and write to 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 of data held in the print buffer 229 attains such a quantity that allows printing of the actual band data, the MPU 221 transports the paper 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 performing the printing process for each band.
A printer driver 250, software for controlling the printer, is preliminary 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 500 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 preliminary in ROM data in a printer main body, and 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
The pattern of this
Further, the resolution of the paper preliminary ejection pattern is equal to that of the binary data and, in the present embodiment, the resolution in Y direction is supposed to be 1200 dpi, equal to the resolution of the printing head, and also 1200 dpi in X direction. 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+X1, 1) gained by shifting by 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. Similarly, the pixel of coordinate (X0+2×X1, 2) gained by shifting by 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×X1, 3) gained by shifting by 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 4×X1 pixels in the X direction and 4×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 case where the paper preliminary ejection is performed for plurality kinds of ink, the pattern of paper preliminary ejection for them can be described with four parameters of original point X0, Y0, distances X1 and Y1 between dots, for each color. Obviously, the aforementioned pattern of paper preliminary ejection is an example, parameters of other forms may also be used for realizing other patterns of paper preliminary ejection, and, a pattern may be expressed without using parameters.
The first embodiment of the present invention is set to perform the paper preliminary ejection for only cyan ink out of cyan, magenta, yellow, black, light cyan and light magenta. More specifically, the present embodiment is set to perform so-called normal preliminary ejection, in which preliminary ejection is executed into an ink receptacle in the vicinity of the home position for each reciprocal scanning of a printing head. In this case, as mentioned below, if it is set to perform the normal preliminary ejection for each reciprocal scanning, there may be a color of ink which may possibly cause ejection failure due to increased viscosity if no ejection is executed during reciprocal scanning. In the present embodiment the cyan ink corresponds to that ink. Therefore, the paper preliminary ejection is executed only for this cyan ink. In other words, the number of colors of ink that require execution of the paper preliminary ejection may possibly increase, in an apparatus where the interval for executing the aforementioned normal preliminary ejection is set longer, and in such a case, it goes without saying that the paper preliminary ejection is to be also executed according to the present invention for those colors of ink. Thus, the application of the present embodiment is relative with respect to the interval for executing normal preliminary ejection, and ink requiring the paper preliminary ejection is determined according to that interval.
Here, it is intended to define the longest period of time (also called “rest time” hereinafter) that enables maintaining the state where image data showing “non-ejection” continues from scanning after the normal preliminary ejection, and thereafter no ejection failure occurs in the ink ejection of the first image data showing “ejection” and to then use this time to evaluate the presence or absence of the paper preliminary ejection or the frequency of the paper preliminary ejection. Here, the state where any ejection failure does not occur designates a state where non-ejection phenomenon where ink is not ejected from the nozzle, distortion phenomenon where ink is ejected though not quite satisfactorily but the landing position of this ejected ink is deviated from the regular position, splashing ejection phenomenon due to insufficient ink refill, and so on do not occur.
It should be appreciated that the rest time as defined above varies according to the presence or absence of the paper preliminary ejection or the frequency thereof as shown in Table 1 below, and the rest time becomes longer in the case where the paper preliminary ejection is performed in comparison to the case where paper preliminary ejection is not performed.
The definition of rest time can apply to the case of not performing the paper preliminary ejection or the case of performing the paper preliminary ejection. First, the rest time in the case of not performing the paper preliminary ejection shall be described referring to the example of cyan in Table 1. Here, a rest time of 1.1 sec means that no ejection failure occurs in the first ejection, if the non-ejection period after the normal preliminary ejection is shorter than 1.1 sec. In other words, ejection failure occurs if the non-ejection period from the normal preliminary ejection is equal to or longer than 1.1 sec.
Also, the rest time can be explained as follows when the paper preliminary ejection is executed. In general, the frequency of the paper preliminary ejection is set to be a value lower than the frequency of ink ejection during printing or normal preliminary ejection, so that ink dots on the printing medium through the paper preliminary erection are unremarkable in contrast to the printed image. Therefore, ejection failure may sometimes occur according to the kind of ink even if the paper preliminary ejection is simply executed at a given constant cycle. A rest time of 2.7 sec for cyan in Table 1 means that ejection failure occurs if the non-ejection period is equal to or longer than 2.7 sec even if the paper preliminary ejection is executed by one time of ejection/8 inch. In other words, it comes off without producing ejection failure if the non-ejection period from the normal preliminary ejection is shorter than 2.7 sec. According to this, the time of keeping a better printing state becomes longer comparing to the case without paper preliminary ejection. Thus, it is advantageous in increasing quality of a printed image.
Table 1 shows the rest time according to the presence or absence of the paper preliminary ejection and the frequency of paper preliminary ejection in the case of ejecting respective ink of black, light cyan, cyan, light magenta, magenta and yellow from the ejection orifice 23 of respective printing heads 22K, 22LC, 22C, 22LM, 22M and 22Y (refer to
As it is evident from Table 1, the rest time of cyan ink in the case of not performing the paper preliminary ejection is 1.1 sec, which is shorter than the time of 1.6 sec from the normal preliminary ejection to the next normal preliminary ejection, shown in
In other words, as it is evident from Table 1, with regard to the rest time in the case of not performing the paper preliminary ejection, only cyan ink has the time shorter than 1.6 sec (the black ink of the present embodiment also has the time longer than 1.6 sec similarly to the other ink), so the paper preliminary ejection shall be performed only for the printing head of this ink. Thereby, the paper preliminary ejection is not executed for the other ink, avoiding unnecessary ink consumption provoked by uniform paper preliminary ejection for all colors of ink.
Here, the frequency of paper preliminary ejection for determining the rest time shown in Table 1 above is one time of ejection/8 inch (hence, 1.5 times ejections/sec=3 times ejections/2 sec) and one time ejection/4 inch (similarly, 3 times ejections/sec=6 times ejections/2 sec). It should be appreciated that only one time of paper preliminary ejection based on the pattern shown in
A second embodiment of the present embodiment is a case where there are a plurality of colors of ink requiring the paper preliminary ejection and the frequency of paper preliminary ejection is different depending on these colors of ink.
Table 2 shows the rest time according to the presence or absence of paper preliminary ejection and the frequency of paper preliminary ejection, for the present embodiment. As shown in Table 2, the rest time in the case of not performing the paper preliminary ejection is 1.1 sec for cyan ink, 1.5 sec for magenta ink and 1.3 sec for yellow ink, which are shorter than the time interval of 1.6 sec, corresponding to the time interval between consecutive two times of normal preliminary ejection, shown in
A third embodiment of the present invention relates to the application of the paper preliminary ejection to a case of using a printing head that can eject two kinds of ejection amount (volume of ink drop) for a single color of ink.
The above first embodiment corresponds to a case where the volume (ejection amount) of one ink drop ejected from respective ejection orifices is 4 pl. On the contrary, the present embodiment uses a printing head provided with two kinds of ejection orifices for ejecting 4 pl and 8 pl.
Table 3 shows the rest time according to the presence or absence of paper preliminary ejection and the frequency of paper preliminary ejection, for each ejection quantity, concerning the present embodiment.
As shown in Table 3, a case where ejection failure may occur if printing starts within time period of 1.6 sec shown in
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.
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 analyzes the image data received from the host device 200 and generates information necessary for the printing such as printing data, printing quality, and 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 preliminary 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 as fall within the true spirit of the invention.
This application claims priority from Japanese Patent Application No. 2004-177374 filed Jun. 15, 2004, which is hereby incorporated by reference herein.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2004-177374 | Jun 2004 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 5659342 | Lund et al. | Aug 1997 | A |
| 6565186 | Hattori et al. | May 2003 | B1 |
| 20050275687 | Furuichi et al. | Dec 2005 | A1 |
| Number | Date | Country |
|---|---|---|
| 55-139269 | Oct 1980 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20050275683 A1 | Dec 2005 | US |
