Patent Application
20240198676
The present disclosure relates to a printing apparatus, a control method, and a storage medium.
A technique of this kind is used in, for example, the industrial printing field. In this field, there are demands for printing on a colored printing medium and a transparent printing medium. In this event, from the perspective of controlling the color reproduction of a color image printed and the transparency of a printing medium, a foundation layer is printed on the printing medium, and the color image is printed thereon.
In a case where such a stack of images are printed by scanning a printhead a plurality of times, in order to perform printing consecutively while reducing mixing between the foundation layer and the color image, the foundation layer and the color image are printed so as not to overlap with each other in a single scan. In a technique described in Japanese Patent Laid-Open No. 2020-49783, from ejection port arrays each having ejection ports arranged in the printing medium conveyance direction, an ejection port group of ejection ports that eject ink for printing a foundation layer and an ejection port group of ejection ports that eject ink for printing a color image are selectively used so as not to overlap with each other in the scanning direction.
However, such selective use of ejection port groups may lead to inequality in the times of usage (ejection) among ejection ports in an ejection port array. Thus, ejection ports that are used more than others reach their limit of serviceability faster than the others, which consequently shortens the life of the printhead.
A printing apparatus according to an aspect of the present disclosure includes: a conveyance unit configured to convey a printing medium; a printing unit having a first ejection port array in which a plurality of ejection ports for ejecting a first ink are arranged in a conveyance direction in which the printing medium is conveyed and a second ejection port array in which a plurality of ejection ports for ejecting a second ink different from the first ink are arranged in the conveyance direction, the first ejection port array and the second ejection port array being arranged in a predetermined direction intersecting with the conveyance direction, the printing unit being configured to print an image by scanning relative to the printing medium in a direction along the predetermined direction; and a control unit configured to perform control to print an image of a foundation layer, an image in a stack region, and an image in a non-stack region on the printing medium by causing the conveyance unit to convey the printing medium while causing the printing unit to perform the scanning. In the printing unit, an ejection port group in the first ejection port array used to print the image of the foundation layer, an ejection port group in the second ejection port array used to print the image in the stack region stacked on the foundation layer, and an ejection port group in the second ejection port array used to print the image in the non-stack region not stacked on the foundation layer are set. The control unit performs control so that in printing of the image in the non-stack region, the image of the foundation layer is printed using an ejection port group in the first ejection port array which is located at a same position as an ejection port group in the second ejection port array for printing the image in the non-stack region, in a direction in which the ejection ports of the first ejection port array are arranged.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Embodiments of the present disclosure are described in detail below with reference to the drawings.
The printing medium P is in a roll shape wound around a spool (not shown) and is fed by being unwound from the roll. The printing medium P thus fed travels along a conveyance route (not shown) from the farther side of the printing apparatus in
In the scanning by the printhead, the printhead ejects ink at a timing based on a position signal from an encoder 7 and performs printing within a band width corresponding to the arrangement range of ejection ports at the printhead. The printhead of the present embodiment includes electrothermal conversion elements as printing elements for the respective ejection ports for ejecting ink. These elements generate heat energy by being driven, and this heat produces an air bubble in ink. Then, the pressure of the air bubble causes the ink to be ejected. Note that elements usable as the printing elements besides the electrothermal conversion elements include piezoelectric elements, electrostatic elements, and MEMS elements. Scanning speed is variable, and scanning can be done 10 inches to 70 inches per second. Printing resolution is also variable, and the ejection operation can be done at 300 dpi to 2400 dpi. In the present embodiment, (pixel) printing is performed at a resolution of 1200 dpi. After the scanning described above, the printing medium P is conveyed by a predetermined amount to be printed on a region of the next band width.
Note that a carriage belt can be used to transmit driving power from the carriage motor to the carriage unit 2. However, a different driving method can be used instead of a carriage belt. Examples of the different driving method include using a mechanism having a lead screw which extends in the X-direction and is driven and rotated by a carriage motor and an engagement part which is provided at the carriage unit 2 and engages with a groove in the lead screw. Also, a heating unit is provided to heat and dry ink on the printing medium P which has undergone the printing operation. Further, a drying mechanism is provided to dry a printed image during printing and scanning. The temperature and wind speed for this drying mechanism can be set freely and are not limited to particular values. After being printed on by the printhead to be described in more detail later, the printing medium P is wound around the winding spool 6 and is formed into a roll-shaped wound medium.
The reaction liquid reacts with a color material or the like in each of the above-described inks to promote their coagulation. Especially in cases of a low-permeable printing medium and an impermeable printing medium to be described later, a contact between a reaction liquid and an ink on a printing medium promotes increase in viscosity due to coagulation of a color material. As a result, an image with less beading can be favorably printed. Also, a reaction liquid can react also with a solid content in the foundation ink and increase the viscosity. Although the same reaction liquid is used in the present embodiment to react with the color ink and the foundation ink, different reaction liquids may be used for the color ink and the foundation ink. In that case, another reaction-liquid ejection port array is added.
Liquid storage tanks (not shown) for storing the inks and the reaction liquid described above are provided corresponding to the respective ejection port arrays, and the inks and the like are supplied from these liquid storage tanks. Note that the printhead and the ink tanks used in the present embodiment may be configured integrally or separably.
First, in S401, the CPU 301 obtains image data (brightness data) sent from the PC 312 (a host computer) to the printing apparatus 100, the image data being expressed by 8-bit 256-value information (0 to 255) on each of red (R), green (G), and blue (B). Similarly, as to the foundation ink, the CPU 301 obtains foundation layer data expressed by 8-bit 256-value information. Note that a region to form the foundation layer on a printing medium can be defined in correspondence to a color image to be stacked, determined by a user of the apparatus, or determined by printing conditions.
Next, in S402, the CPU 301 executes color conversion processing to convert RGB image data into CMYK data corresponding to the color inks. This color conversion processing generates CMYK data such that each of C, M, Y, and K is expressed by 12-bit 4096-value information. The CPU 301 similarly executes color conversion processing for the foundation layer data. Also, in S402, the CPU 301 generates reaction liquid data corresponding to the CMYK data and the foundation layer data obtained by the color conversion processing. For example, tone values of the reaction liquid data are set to be 20% of the tone values of each set of the data.
Next, in S403, the CPU 301 quantizes the CMYK data to generate quantized data such that C, M, Y, and K are each expressed by 3-bit 5-value data. The quantization processing can be executed using the dithering method, the error diffusion method, or the like. The CPU 301 performs quantization processing similarly on the foundation layer data and the reaction liquid data to generate 3-bit 5-value data. Note that in the present embodiment, quantization data having a data resolution of 600 dpi is generated by the quantization processing. Next, in S404, the CPU 301 performs index development processing using development pattern data that uses the above quantized data as indices and thereby converts each of C, M, Y, and K into 1-bit binary print data. The CPU 301 performs the index development processing on the foundation layer data and the reaction liquid data as well to convert them into 1-bit binary data. For example, the 3-bit 5-value data to serve as an index is associated with one of five index patterns each with 4×4 cells and can express five tones depending on arrangement of “1” or “0” in the 4×4 cells. Also, because 3-bit 5-value data is at a resolution of 600 dpi, the index-developed pattern of 4×4 cells becomes binary data at a resolution of 1200 dpi to be the print data to be described below.
Lastly, in S405, the CPU 301 performs masking processing corresponding to multi-pass printing to be described later on the color ink print data, the foundation layer print data, and the reaction liquid print data obtained in S404 and thereby generates 1-bit print data for each ejection port array for each scan.
The printhead ejects ink according to the print data generated as above. Although the CPU 301 of the printing apparatus 100 executes all the processes in S401 to S405 in the mode described in the present embodiment, it is to be noted that the present disclosure is not limited to this mode. For example, the PC 312 may execute all the processes in S401 to S405. Also, for example, the PC 312 may execute part of the processes, and the printing apparatus 100 may execute the rest of the processes.
In four-pass printing, the 16 ejection ports are divided into first to fourth ejection port groups 502 to 505 each having four ejection ports. Then, the first to fourth ejection port groups are associated with first to fourth mask patterns (mask regions) 506 to 509, respectively. Each mask pattern has a region of four areas×four areas. An area in black denotes an area where printing of a dot is permitted, while an area in white denotes an area where printing of a dot is not permitted. The first to fourth mask patterns are in a complementary relation with one another and complete an image on a unit region corresponding to a single ejection port group. To simplify the illustration, patterns 510, 511, 512, and 513 show images printed on the printing medium P by the first to fourth scans of the printhead in a case where the print-permitted areas of the mask patterns are all printed. It goes without saying that in actuality, an image is printed based on logical ANDs between the areas of the mask patterns and the print data.
After every scan of the printhead, the printing medium P is conveyed in the Y-direction relative to the ejection port array on the printhead by an amount corresponding to the above-described unit region. First, in the first scan, the pattern 510 is printed on the printing medium P by ejection from the ejection port group 502 corresponding to the mask 506. Next, in the second scan, the pattern 511 is printed on the printing medium P by ejection from the ejection port group 502 corresponding to the mask 506 and ejection from the ejection port group 503 corresponding to the mask 507. Printing is performed similarly afterwards, so that the pattern 513 is printed on the printing medium P with four scans, and printing on a unit region corresponding to the ejection port group 505 is thus completed.
The color inks and the foundation ink used in the printing apparatus of the present embodiment are as follows. These inks each contain a solid component that forms a foundation layer or a color image and a liquid component that volatilizes. Examples of the liquid component include water or a water-soluble organic solvent. As the solid component, the color inks contain a color material which is at least one of a pigment and a dye, and the foundation ink contains at least one of a white pigment and a metallic pigment. Using a white pigment improves the color reproduction of the color inks, and using a metallic pigment provides special glossiness to a printing medium. All of these inks contain water-soluble resin particles for bringing a printing medium and a color material into close contact with each other to improve a print medium's property against chafing (fixation property).
Using a reaction liquid in the printing apparatus of the present embodiment improves fixation of an image printed especially on a low-permeable printing medium or on an impermeable printing medium. Specifically, the reaction liquid used in the present embodiment contains a reactive component that reacts with a pigment or resin particles contained in an ink and coagulates them or turns them into gel. By being mixed, on a printing medium or the like, with an ink containing a pigment which is stably dispersed or dissolved in an aqueous medium due to action of an ionic group, this reactive component can break dispersion stability of the ink. Note that the reaction liquid is not necessarily have to be used in all the printing modes, and only an amount thereof necessary to print an image is applied considering the amount of ink applied.
Examples of the printing medium used in the printing apparatus of the present embodiment include not only paper and the like typically used in printing, but also other media capable of receiving ink, such as a cloth, a plastic film, a metal plate, glass, ceramics, resin, wood, and leather. Specifically, an “impermeable printing medium” can be used, and this refers to a printing medium with no ink permeability for an aqueous ink. Also, a “low-permeable printing medium” refers to a printing medium with lower ink permeability for an aqueous ink than paper and the like typically used. More quantitively, a “low-permeable printing medium” refers to a printing medium having a print surface that absorbs water of 10 mL/m2 or less within 30 msec½ from the start of contact in the Bristow method. The Bristow method is widely used as a method for measuring the amount of liquid absorbed in a short period of time, and is employed in JAPAN TAPPI.
Examples of an impermeable printing medium include ones that are not fabricated as a printing medium for aqueous inks, such as glass, plastic, a film, or yupo paper. The examples further include ones with surfaces that are not processed for printing (have no ink absorption layer formed thereon), e.g., a plastic film or a medium having a base material such as paper coated with plastic. Examples of the plastic include polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, polyurethane, polyethylene, and polypropylene. Also, examples of the low-permeable printing medium include, e.g., printing media such as actual printing stock used for offset printing or the like, such as art paper and coated paper.
The printing apparatus 100 of the present embodiment is capable of printing an image such that a foundation layer and a color image are stacked together. A description is now given of a specific method for printing the stack portions.
As shown in
In a case where a color image and a foundation layer are stacked in this order on a printing medium, as shown in
Note that it is also possible to stack three or more layers of a foundation layer and a color image. In this case, as described above, the ejection ports are used selectively so that an ejection port group that prints the foundation layer and ejection port groups that print a color image do not overlap in the scanning direction.
In one embodiment of the present disclosure, in the basic printing method described above, a stack region where a color image is stacked and a non-stack region where a color image is not stacked are set in a foundation layer, and ejection ports used to print the stack region and ejection ports used to print the non-stack region are different from each other.
As shown in
In the present embodiment, depending on the “stack region” and the “non-stack region” of the image, processing to be described later with
In
Setting the ejection ports to use as above can reduce the inequality in the frequency of usage among the ejection ports in the ejection port array for the foundation layer ink and therefore can reduce shortening of the life of the printhead, compared to a case where the foundation layer is printed by the third ejection port group 803 uniformly. Note that the setting of the ejection port group to use for printing is not limited to the above mode, as long as ejection ports other than the third ejection port group 803 are used to print a non-stack region of the foundation layer where the color image is not stacked. This still allows, to some degree or another, reduction in inequality in the frequency of usage among the ejection ports in the foundation-ink ejection port array 201Back. In this case, the ejection ports in the third ejection port group may be used in addition to the ejection ports other than the third ejection port group, or only the ejection ports other than the third ejection port group may be used.
First, in S901, as described above with e.g.
If it is determined in S903 that it is a stack region, in S904, the CPU 301 sets a second mask pattern. Also, if it is determined in S903 that it is a non-stack region, in S905, the CPU 301 sets a first mask pattern. Then, using the corresponding masks, the CPU 301 generates print data for each scan. The processing in S904 and S905 will be described later using
Then, in S906, the CPU 301 sends the print data including the mask patterns described above to a printhead control processing unit. Then, masked print data for each scan is generated. Lastly, in S907, the CPU 301 executes scanning and printing.
The mask patterns in
In a case of performing multi-pass printing with four scans, 32 ejection ports of the color-ink ejection port array 1201Color are divided into ejection port groups A to D each having eight ejection ports. The first ejection port group described above corresponds to the ejection port groups A and B. Similarly, the foundation-ink ejection port array 1201Back is divided into ejection port groups E to H. The second ejection port group described above corresponds to the ejection port groups E and F, and the third ejection port group described above corresponds to the ejection port groups G and H.
Then, the ejection port groups A to D of the color-ink ejection port array 1201Color are associated with mask regions MC-1 to MC-4, respectively, to perform the printing with the first ejection port group. As a result, the ejection port groups A and B print images that complement each other, and the ejection port groups C and D do not print any image. Meanwhile, for the foundation-ink ejection port array 1201Back, the first mask pattern or the second mask pattern is associated depending on whether the color image is stacked (Steps S904 and S905 in
With the mask pattern and the ejection ports of the ejection port array thus associated with each other, a color ink image is printed as follows: color image data 1004 is masked with the mask regions MC-1 to MC-4, and ink is ejected only for pixels overlapping with the print-permitted pixels of the mask pattern. Similarly, a foundation layer is printed with the stack region 1003 of the foundation layer data being masked by the mask regions M1-1 to M1-4 of the first mask pattern. Also, the foundation layer is printed with the non-stack region 1002 being masked by the mask regions M2-1 to M2-4 of the second mask pattern.
Ejection ports to use in each of the four scans are defined to complete printing using the mask patterns described above, and thus, printing is performed with four scans based on print data. As shown at the right end of
Note that the above-described correspondences between the first to fourth ejection port groups and the actual ranges of the ejection ports in the ejection port arrays are not limited to the example described above. The correspondences can be defined at will according to the inks used, the size of the unit region, or the like as long as their relative positional relations are maintained.
As thus described, in the present embodiment, ejection ports used to print a non-stack region of the foundation layer where the color image is not stacked and ejection ports used to print a stack region of the foundation layer are different. This reduces the inequality in the frequency of usage among the ejection ports of the foundation-ink ejection port array and consequently can reduce shortening of the life of the printhead.
In the example described above with
As shown in
In the first embodiment described above, a non-stack region of a foundation layer where a color image is not stacked is printed only by an ejection port group other than the third ejection port group. In the present embodiment, part of the third ejection port group is used to print a non-stack region. In addition, each ejection port group's usage frequency is set based on the ratio of the area of a non-stack region and the area of a stack region. This enables further reduction of shortening of the life of the printhead. The following description omits detailed descriptions of configurations that are similar to those in the first embodiment.
In the above example, the ratio of the area of non-stack region to the foundation layer is ⅔. Also, the ratio of the length of the second ejection port group to the total length of the foundation-ink ejection port array (a second ejection port group ratio) is ½. Thus, in this case, in a case where the ratio of the area of non-stack region to the foundation layer is larger than the second ejection port group ratio, if the non-stack region of the foundation layer is printed only by the second ejection port group, the second ejection port group is used more frequently than the third ejection port group that prints the stack region of the foundation layer. Thus, the amounts of ink applied by the second ejection port group and by the third ejection port group are adjusted as will be described below.
Specifically, in the close-up view shown in
x+x(1−x)=2x−x{circumflex over ( )}2, where x is the second ejection port group ratio.
By thus adjusting the usage frequencies, the difference in usage frequency between the second and third ejection port groups is reduced, so that shortening of the life of the printhead can further be reduced compared to a case where a non-stack region of the foundation layer where a color image is not stacked is printed only by the second ejection port group.
Note that the lengths and positions of the ejection port groups described above are mere examples and can be defined at will as long as the relative positional relations are maintained.
The first and second embodiments described above relate to reducing shortening of the life of the ejection port array for printing a foundation ink. However, the fact that using some ejection ports more than others in multi-layer printing shortens the life of the printhead also applies to ejection port arrays for printing color inks. For example, in a case where a transparent printing medium is used, printing a color ink on top of a foundation layer enables the color image to be visible only from one side of the printing medium. In order for the color image to be visible from both sides of a printing medium, the color image is printed without the foundation layer printed. In this case, an ejection port group used in the ejection port array for printing a color ink can be set without being bound by its relation to the ejection port group used in the ejection port array for printing the foundation ink. Thus, shortening of the life can be reduced by appropriately setting the ejection port group to use for a region where a color image is printed without a foundation layer being stacked.
In
With reference to
Embodiment(s) of the present disclosure can also be realized by a computer of a system or apparatus that reads out and executes computer executable instructions (e.g., one or more programs) recorded on a storage medium (which may also be referred to more fully as a ‘non-transitory computer-readable storage medium’) to perform the functions of one or more of the above-described embodiment(s) and/or that includes one or more circuits (e.g., application specific integrated circuit (ASIC)) for performing the functions of one or more of the above-described embodiment(s), and by a method performed by the computer of the system or apparatus by, for example, reading out and executing the computer executable instructions from the storage medium to perform the functions of one or more of the above-described embodiment(s) and/or controlling the one or more circuits to perform the functions of one or more of the above-described embodiment(s). The computer may comprise one or more processors (e.g., central processing unit (CPU), micro processing unit (MPU)) and may include a network of separate computers or separate processors to read out and execute the computer executable instructions. The computer executable instructions may be provided to the computer, for example, from a network or the storage medium. The storage medium may include, for example, one or more of a hard disk, a random-access memory (RAM), a read only memory (ROM), a storage of distributed computing systems, an optical disk (such as a compact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™), a flash memory device, a memory card, and the like.
While the present disclosure has been described with reference to exemplary embodiments, it is to be understood that the disclosure is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2022-203744, filed Dec. 20, 2022, which is hereby incorporated by reference wherein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-203744 | Dec 2022 | JP | national |
