1. Field of the Invention
The present invention relates to a control device for a printing apparatus, a control method, and a storage medium, and more particularly to time-division driving of a plurality of print heads and distribution of print data to the plurality of print heads.
2. Description of the Related Art
Printing apparatuses such as printers or copiers are configured to print images (including letters, symbols, and the like) on print media such as paper by using color material based on print information. The printing apparatuses are classified into an ink jet type, a wire dot type, a thermal type, an electrophotography type (a laser exposure type and an LED exposure type), and the like according to their printing systems. Of these types, a printing apparatus of an ink jet type (an ink jet printing apparatus) performs printing by using an ink jet print head to eject ink droplets from ejection ports of the print head toward a print medium.
Printing methods for the ink jet printing apparatus fall roughly into two types: a multipass system and a full line system. The multipass system repeats the operation of conveying a print medium by a predetermined amount in a direction crossing a direction in which a print head scans the print medium to perform printing over the entire area of the print medium. In the multipass system, the print head performs print scanning multiple times with respect to the same area on the print medium to print an image on the print medium. This can achieve a high image quality at relatively low cost. Therefore, ink jet printing apparatuses for consumers often use this system.
In the full line system, a print head has a printing width corresponding to the width of a print medium, and a print medium is moved so that an image is printed on the print medium. In this case, the print head performs print scanning once on the print medium. Such a print head having a long length and used in the full line system generally often has a configuration in which a plurality of print chips having a short length are arranged in a printing width direction. As compared to the ink jet printing apparatus of the multipass system, the cost of the apparatus body is higher, but it is possible to obtain an output product of a high image quality at high speed. Therefore, the full line system is often used in the ink jet printing apparatuses for POD (Print on Demand) or the like. Today, there is a need for high speed printing of print materials of a high image quality equivalent to that in offset printing, for example, at a high resolution of 1200 dpi×1200 dpi or greater, at a rate of several hundreds of pages to several thousands of pages per minute on a print medium having a Kiku size (152 mm×218 mm). Such a printing apparatus of the full line system is disclosed in, for example, Japanese Patent Laid-Open No. 2002-292859.
For a print head mounted on the printing apparatus of the full line system, a so-called multi-array head is often used, in which a plurality of arrays of printing elements that can print the same color material are arranged in parallel. Providing a plurality of printing element arrays associated with the same color material can print image data associated with a specific color material by a plurality of printing elements. This can suppress degradation in image quality caused by variations in landing positions of dots formed by ink droplets from respective printing elements or by variations in ejection amounts. Furthermore, since a time difference can be made between landings of adjacent dots on the print medium, it is possible to suppress degradation in image quality caused when dots which have landed on the print medium coalesce into one to form an inappropriate shape.
Each of the printing elements provided for the plurality of printing element arrays generally has a system using an electrothermal transducer element (heater) or a system using a piezoelectric element. Both systems control ejection of ink droplets by electric signals.
Printing elements in printing element arrays are arranged at a high density of, for example, 600 dpi. To downsize power sources for driving heads and members for power sources such as connectors and cables, the printing elements are often driven by a time-division driving system. In the time-division driving system, a plurality of printing elements are divided into sections, each including a predetermined number of printing elements. Then, each section is segmented into a plurality of driving blocks and the printing elements for each driving block are divided by time to be driven.
With reference to the attached drawings, the case of driving a print head by the time-division driving system will be described in detail.
In an example shown in
Time-division driving by pulse driving signals 2 with a time difference in ejection timings of ink droplets between driving blocks causes ink droplets to be ejected at different timings as shown in
As described, the technique of solving the problem of ragged lines is disclosed, for example, in Japanese Patent Laid-Open Nos. 2007-276353 and 2007-090714.
Japanese Patent Laid-Open No. 2007-276353 discloses a printing method in which the number of blocks driven in a single printing element array is reduced to 1/N and portions to be printed by the printing elements in a non-driven block are assigned to another print pass or another ejection port array for the same ink color. In this method, a time difference of block driving occurring in a single printing element array is reduced to 1/N, so as to reduce a shift of a landing position from an ideal position.
Further, Japanese Patent Laid-Open No. 2007-090714 discloses a driving method in which a plurality of printing element arrays are driven in different block driving orders. This method can reduce raggedness of lines.
Today, however, in ink jet printing apparatuses for POD printing or the like, there is an increasing need for high-definition output of image data, like offset printing. The above-described related art can reduce raggedness of thin lines, but a further improvement is required for such a need.
With respect to such a need, the method disclosed in Japanese Patent Laid-Open No. 2007-276353 can reduce raggedness of vertical lines, but variations in positions caused by a time difference in block driving after restriction still remain, and thus it cannot be said that the raggedness can be sufficiently reduced. As N increases, load on processing to another pass (another ejection port array in the full line system) and the number of passes increase. Therefore, it is difficult to indiscriminately increase a value of N in actuality.
With respect to such a need, the method disclosed in Japanese Patent Laid-Open No. 2007-090714 can reduce raggedness of vertical lines like Japanese Patent Laid-Open No. 2007-276353, but raggedness of thin lines still remains since block driving orders are different between printing element arrays.
An object of the present invention is to provide a control device for a printing apparatus in which deterioration in image quality caused by differences in timings of time-division driving can be suppressed, in particular, raggedness of thin lines and edges can be suppressed, a control method, and a storage medium.
In one aspect of a device according to the present invention, there is provided a control device for a printing apparatus provided with a print head in which a plurality of printing element arrays each having a plurality of printing elements arranged therein are placed in parallel in a direction crossing an arrangement direction of the printing elements, wherein the print head and a print medium opposite to the print head are relatively moved in the direction crossing the arrangement direction of the printing elements to print an image on the print medium by the print head, the control device comprising: an acquisition unit configured to acquire image data; a distribution unit configured to assign each pixel in the image data to a printing element for outputting a pixel value of the pixel according to distribution information indicating that each of the pixels forming the image data is associated with one of the plurality of printing elements; and a control unit configured to control printing of the image data by driving the plurality of printing elements by time-division driving in which a different driving timing is set for each printing element according to assignment by the distribution unit, wherein the control unit drives the printing elements such that the printing elements included in the printing element array are associated with a plurality of different driving timings and further the plurality of printing element arrays have different orders of driving timings for the respective printing elements in the arrangement direction of the printing elements, and the distribution information is set such that, with respect to a pixel group corresponding to the arrangement direction of the printing elements, of the printing elements that can print a pixel included in the pixel group, a printing element driven at a reference driving timing or a driving timing close to the reference driving timing is assigned to the pixel.
In another aspect of a device according to the present invention, there is provided a control device for a printing apparatus provided with a print head in which a plurality of printing element arrays each having a plurality of printing elements arranged therein are placed in parallel in a direction crossing an arrangement direction of the printing elements, wherein the print head and a print medium opposite to the print head are relatively moved in the direction crossing the arrangement direction of the printing elements to print an image on the print medium by the print head, the control device comprising: an acquisition unit configured to acquire image data representing a dot arrangement for each pixel; a distribution unit configured to assign each pixel in the image data to a printing element for outputting a pixel value of the pixel according to distribution information indicating that each of the pixels forming the image data is associated with one of the plurality of printing elements; and a control unit configured to control printing of the image data by driving each printing element at a predetermined driving timing according to assignment by the distribution unit, wherein the control unit drives the printing elements such that the printing elements included in the printing element array are associated with a plurality of different driving timings and further the plurality of printing element arrays have different orders of driving timings for the respective printing elements in the arrangement direction of the printing elements, and the distribution information assigns printing elements driven at the same driving timing to all pixels in the arrangement direction of the printing elements.
The present invention further provides a printing apparatus having a device according to the above aspects, a computer program for causing a computer to function as the device according to the above aspects, and a control method carried out in the device according to the above aspects.
According to the present invention, it is possible to suppress deterioration in image quality caused by differences in timings of time-division driving, in particular, raggedness of thin lines and edges.
Further features of the present invention will become apparent from the following description of exemplary embodiments (with reference to the attached drawings).
Preferred embodiments of the present invention will now be described with reference to the attached drawings. It should be noted that the configurations shown in the following embodiments are given by way of illustration, and the present invention should not be limited to the configurations shown in the drawings.
The printer moves the print head IJH and the print medium P relative to each other for printing. In the present embodiment, a conveying motor is driven according to control of a control circuit as will be described so that the print medium P is conveyed in VS direction (referred to as a main scanning direction in the full line type) shown in
The print head IJH is connected to an ink supply tube (not shown) and can perform printing by ejecting ink from ink jet printing elements. Further, each ink jet printing element used in the present embodiment is provided with a heat generating element (electrothermal transducer) that generates thermal energy for ink ejection at an internal portion (liquid channel) that is in communication with the printing element.
While
As shown in
Note that the ink jet printing system is not limited to the system using a heat generating element (heater).
Various modification examples can be employed also for the configuration of the print head. For example, the ink jet printing system may be a system that ejects ink by using pressures by a piezoelectric element. Examples of a continuous type that continuously injects ink droplets for granulation include a charge control type and a divergence control type. Further, in a case where the ink jet printing system is an on-demand type that ejects ink droplets as necessary, the ink jet printing system may be a pressure control system or the like that ejects ink droplets from an orifice by vibration of a piezoelectric element.
A CPU 43 has control over the present printer according to various control programs. A storage medium 44 stores control programs for the CPU 43 to control the present printer and the like. In the present embodiment, under the control by the CPU 43, an image printing unit 47 that is included in the printer outputs an image as will be described. Further, the storage medium 44 stores print medium information 44a relating to a type of print medium, ink information 44b used for printing, and environment information 44c relating to environment such as temperature and humidity of a printer at the time of printing. As the storage medium 44, a ROM, an FD, a CD-ROM, a HD, a memory card, a magneto-optical disk, and the like can be used. A RAM 45 is used as a work area for the various programs in the storage medium 44, a temporary save area for data at the time of error processing, and a work area at the time of image processing. Furthermore, under the control by the CPU 43, various tables in the storage medium 44 may be copied to the RAM 45 to change the content of the tables, and image processing may be performed with reference to the changed tables.
An image data input unit 41 inputs multivalued image data from an image input device such as a scanner or a digital camera, a hard disk such as a personal computer, or the like. An operation unit 42 is provided with various keys for instructing settings of various parameters and starting of printing. Address signals, data, control signals, or the like in the present printer are transmitted or received through a bus unit 48.
An image data processing unit 46 applies various kinds of image processing such as color matching, color separation, γ correction, and resolution conversion, onto image data input through the image data input unit 41. Then, the multivalued image data obtained as a result of the processing is quantized and converted into binary image data for each pixel. For example, in the present embodiment, the image data processing unit 46 performs binarization by dither processing which will be described later, but the binarization may be performed by other arbitrary methods such as an error diffusion method or an average density preservation method.
An image printing unit 47 forms a dot image on a print medium by ejecting ink from corresponding printing elements 35 based on binary image data created by the image data processing unit 46. Details of the image printing unit 47 will be described later.
A calculation method of dither processing will now be explained. For example, a pixel value of black in the post color separation data 501 is set as K, a threshold in the threshold matrix 503 for dither processing on black is set as Th_K. Halftone data K_b can be represented by the following equation (1) and equation (2):
if K<Th—K, K—b=0 (1)
if Th—K≦K, K—b=1 (2).
All of the printing element arrays in each of the print chips 51 to 56 have the same configuration. By way of example, the configuration of the print chip 51 will be described. As described above, the print chip 51 has four printing element arrays 51A, 51B, 51C, and 51D arranged in parallel with each other, each having 1024 printing elements at a resolution of 1200 dpi. Further, all of the printing element arrays A, B, C, and D provided for each of the print chips 51 to 56 eject ink of the same color. In the present embodiment, an example of the case where the printing element arrays in each of the print chips 51 to 56 eject ink of black color will be described. Any other ink color may be used such as cyan, magenta, and yellow, or special colors of similar colors having different densities such as red, blue, and green.
Incidentally, the printing element arrays A, B, C, and D are separated from each other by a predetermined distance d in a direction in which a print medium is conveyed. Timings at which ink is ejected from the printing element arrays A, B, C, and D vary so that pixels in one of the lines in the arrangement direction of printing elements of image data to be printed align on the print medium in the arrangement direction of printing elements.
More specifically, after ink is ejected from the printing elements in the printing element array A, ink is ejected from the printing elements in the printing element array B at a timing at which the print medium is conveyed by a distance d in the right direction in
In
In an example shown in the driving block allocation table 70, a first driving block (0) is assigned to 256 printing elements, that is, every four printing elements, from the printing element of printing element No. 0 in the printing element array 51A. Likewise, a second driving block (1) is assigned to 256 printing elements, that is, every four printing elements, from the printing element of printing element No. 1 in the printing element array 51A. Further, a third driving block (2) is assigned to 256 printing elements, that is, every four printing elements, from the printing element of printing element No. 2 in the printing element array 51A. Still further, a fourth driving block (3) is assigned to 256 printing elements, that is, every four printing elements, from the printing element of printing element No. 3 in the printing element array 51A.
Also with respect to the printing element arrays 51B, 51C, and 51D, as shown in the driving block allocation table 70, four driving blocks (0 to 3) are allocated like the printing element array 51A. An algorithm for driving order allocation in block-division driving shown in the driving block allocation table 70 will be described later in detail.
A configuration method of a distribution mask used in the present embodiment and an algorithm for assigning a driving order (driving block) in block-division driving as shown in the driving block allocation table 70 will be described.
In S910, a number of driving blocks N is obtained and in S920, a number of printing element arrays L is obtained. In the present embodiment, N=L=4.
Here, a memory for storing a value of a driving block to be assigned to each printing element in each printing element array, a memory for configuring a distribution mask, and a memory for representing driving blocks allocated to print data are prepared. These memories are shown in
In the following S930, a distribution mask is set. When a driving block of each printing element as shown in
In S940, a driving block (a driving order in block-division driving) is assigned to each printing element in the first printing element array 51A. Since N=4, values from 0 to 3 may be randomly assigned one by one, but here, values from 0 to 3 are assigned from the top as in a driving block allocation 101 as shown in
In S950, with reference to the driving block allocation to each printing element in the printing element array 51A in which allocation has already been finished in the driving block allocation 101 and the distribution mask 111, driving blocks allocated to print data are obtained. More specifically, in the distribution mask 111, “A” associated with data to be printed by each printing element in the printing element array 51A is searched, and assigned driving blocks 0 to 3 in the driving block allocation 101 are written into corresponding positions in a matrix 120. As a result, a driving block allocation 131 to print data as shown in
In the following S960, based on the assigned driving blocks in the driving block allocation 131, driving block allocation to print data to which a driving block is not assigned yet is sequentially determined. The order of determination is shown by an arrow 132 in
The processing of S960 will be described in more detail. According to the arrow 132, a driving block at a position 133 in the driving block allocation 131 is referenced. Since the driving block “0” is assigned to the position 133, an assigned value is retained. If no driving block is assigned, another row in the same column is referenced until a position to which a driving block is assigned is found.
Still according to the arrow 132, a driving block at a position 134 shown in
Next, to obtain information about which printing element performs printing at the position 134 of print data, a position 114 corresponding to the position 134 of the distribution mask 111 as shown in
The above-described processing in S960 is repeated according to determination processing in S970, so that the driving blocks that are unassigned in the driving block allocation 131 are sequentially determined. As a result, a driving block allocation 155 to print data is finally obtained as shown in
As an example of print data 160, halftone data is used herein to represent by 1 a pixel to which a dot is printed and to represent by 0 a pixel to which a dot is not printed. The print data 160 corresponds to an image pattern formed on the print medium, including two thin lines in the arrangement direction of printing elements (a vertical direction) having a one-pixel width with an interval corresponding to the one-pixel width. By applying a distribution mask 161 to the print data 160, each dot of the print data 160 is distributed to one of the printing elements in the printing element arrays A, B, C, and D of the print chip 51, and a driving block is assigned to each dot. A driving block allocation 162 is generated for the print data 160. The distribution mask 161 is repeatedly applied so that pixels of the print data 160 are allocated to all of the printing elements of the print head.
A description will be given of how driving blocks (0 to 3) are allocated to the pixel group of the print data 160.
For example, a pixel of a pixel value of 1 in the top row in the leftmost column of the print data 160 corresponds to a value of A in the distribution mask 161. This value represents that the pixel is printed by the printing element array 51A. Furthermore, of the printing elements in the printing element array 51A, this pixel is printed by the printing element of printing element No. 0 at a corresponding position in the arrangement direction of printing elements, and with reference to
With respect to the following row, the block driving order assigned to the printing elements of printing element No. 1 in the printing element arrays 51B, 51C, and 51D is different from that of the top row. Further, the distribution order of the distribution mask 161 is D, A, B, and C in the order of the main scanning direction, which is different from that of the top row in the distribution mask 161. As a result of applying the distribution mask 161 in the same manner to the pixels in the following row of the print data 160, the first driving block (0), the second driving block (1), the third driving block (2), and the fourth driving block (3) are assigned to the printing elements in the order of the main scanning direction. In the same manner, the same driving block is assigned in the arrangement direction of printing elements as the driving block allocation 162 to the printing elements of printing element No. 2 onward. More specifically, one line in a direction crossing the main scanning direction on the print medium is printed at a single driving timing which is less than the number of segments 4.
When the heaters for the printing elements are driven according to the driving block allocation 162, dots corresponding to the pixels in the first column having the pixel value of 1 in the first driving block (0) are printed in a line in the array direction on the print medium, whereas pixels in the second column having the pixel value of 0 in the second driving block (1) are not printed. Then, dots corresponding to the pixels in the third column having the pixel value of 1 in the third driving block (2) are printed in a line in the array direction on the print medium, whereas pixels in the fourth column having the pixel value of 0 in the fourth driving block (3) are not printed. According to the present embodiment, like the output image 163 as schematically shown in
Each dot corresponding to each pixel in the first column is printed in the following manner described in detail. First, the printing element of printing element No. 0 in the printing element array 51A is driven at a driving timing 81 in the first driving block (0), and a dot is printed on the top. Then, the printing element of printing element No. 3 in the printing element array 51B is driven at a driving timing 82 in the first driving block (0), and a dot is printed on the fourth position from the top. Then, the printing element of printing element No. 2 in the printing element array 51C is driven at a driving timing 83 in the first driving block (0), and a dot is printed on the third position from the top. Then, the printing element of the printing element No. 1 in the printing element array 51D is driven at a driving timing (not shown) in the first driving block (0), and a dot is printed on the second position from the top. In this manner, the left thin line in the output image 163 is printed. The right thin line is printed in the same manner at driving timings 84 and 85 in the third driving block (2) or the like.
Note that due to block-division driving which drives blocks at different timings, positions at which dots corresponding to the pixel group of print data are formed vary in a pixel area on the print medium corresponding to the pixels. More specifically, as shown in landing displacements by driving timings shown in
In a case where the same driving block is assigned in the arrangement direction of printing elements, positions at which dots, corresponding to the pixels of print data, formed according to the driving block within the pixel area on the print medium vary in the main scanning direction. This is as shown in the example of
More preferably, to avoid such a phenomenon, in printing a dot associated with the second driving block (1), for example, an ejection timing of a dot may be advanced by T/4 so that the dot lands not onto an area 172 but onto the area 171 in the first driving block (0). In the same manner, in printing a dot associated with the third driving block (2), an ejection timing of a dot may be advanced by 2T/4, and in printing a dot associated with the fourth driving block (3), an ejection timing of a dot may be advanced by 3T/4.
In a modification example, the print chip may be manufactured such that physical positions of the printing element arrays are shifted so that all of the dots land onto the area 171 in the first driving block (0). According to the above improved embodiment, it is possible to avoid the above phenomenon in which density variation in dot intervals occurs in the main scanning direction, and dots can be regularly arranged as shown in
Note that in the above description, the example of part of the printing elements in the print chip 51 is shown. The present embodiment can be applied similarly to other printing elements and print chips. Furthermore, the numbers of printing element arrays, printing elements provided for each printing element array, driving blocks, and sections for time-division driving may be set or designated to any numbers according to the configurations of the printing apparatus and the print head. For example, the number of printing element arrays may be set to 8, the number of printing elements provided for each printing element array to 1024, the number of driving blocks to 8, the number of sections for time-division driving to 128, and the like.
In addition, the present embodiment can be applied similarly to the connection portions provided for each print chip. More specifically, in the connection portion, after the print data is distributed to two print chips which form a connection portion, the present embodiment can be applied in the same manner.
A description will be given of a comparative example for comparison with the first embodiment while comparing with the first embodiment.
Also in the present comparative example, the same print chip 51 as the one in the first embodiment is used. In the present comparative example, as shown in a driving block allocation table 200, the order of driving blocks in an arrangement direction of printing elements is the same in all of four printing element arrays 51A, 51B, 51C, and 51D. Then, to the printing elements of printing element Nos. 0 to 1023, driving blocks 0, 1, 2, and 3 are repeatedly set in the order mentioned.
The same print data 160 and the distribution mask 161 (
To each of the printing elements in the printing element arrays 51A, 51B, 51C, and 51D to which block driving orders are set as shown in
According to the present comparative example, each of two vertical thin lines is printed not in a line but in a ragged manner as shown in an output image 223 as schematically shown in
In the first embodiment, the same driving block is assigned to each of a plurality of pixel areas arranged in a direction corresponding to an arrangement direction of printing elements on a print medium, and a vertical thin line is printed in a line while setting to zero the amount of displacement in a main scanning direction of dot positions of dots formed in each pixel area. However, the first embodiment is an example in which straightness is obtained in every line in the arrangement direction of printing elements in a case where both of the number of printing element arrays and the number of driving blocks are four. If the number of driving blocks is greater than the number of printing element arrays, such straightness may not be obtained. In the present embodiment, there is provided a configuration of obtaining more favorable straightness in every line even in a case where the number of driving blocks is greater than the number of printing element arrays by restricting the amount of displacement in the main scanning direction as possible.
A description will be given of a second embodiment in which the number of printing element arrays is set to 4, the number of printing elements provided for each printing element array to 1024, the number of driving blocks to 8, and the number of sections in time-division driving to 128.
In an exemplary driving block allocation table 230 as shown in
With respect to the printing element arrays 51B, 51C, and 51D, eight driving blocks (0 to 7) are allocated as shown in
Also in the processing of S940 in the present embodiment, a driving block (driving order in block-division driving) is assigned to each printing element in the first printing element array 51A. In the present embodiment, since N=8, values from 0 to 7 are randomly assigned one by one (
To each of the printing elements in the printing element arrays 51A, 51B, 51C, and 51D to which block driving orders are set as shown in
In a case where a print head is driven according to the driving block allocation 242 and the print data 160 is printed on the print medium, with respect to pixels in the leftmost column of the print data 160, for example, in the order from the top, the printing elements are driven alternately in the first driving block (0) and the second driving block (1). More specifically, one line in a direction crossing the main scanning direction on the print medium is printed on the print medium in two adjacent driving timings, which is less than the number of segments 8. As a result, according to the present embodiment, as shown in an output image 243 schematically shown in
Incidentally, in accordance with the algorithms of the embodiments shown in the flowcharts and the schematic diagrams of
In the first embodiment, a distribution mask is configured for setting printing element arrays so that a plurality of pixels arranged in a direction corresponding to the arrangement direction of printing elements are printed on the print medium at the same driving timing as possible so as to set to zero the displacement in the main scanning direction of positions of dots formed. In the second embodiment, to reduce the displacement to ⅛ a width of a pixel area, a distribution mask for setting a printing element array to each pixel. As described above, in a control system of a printer (printing apparatus) of the present embodiment, the displacement is suppressed in the main scanning direction to a limited portion of the pixel area so as to improve straightness of lines printed in the direction corresponding to the arrangement direction of printing elements. Accordingly, in the control system of the printer (printing apparatus) of the present embodiment, a printing element array is assigned to each pixel in turn based on the driving timings at which pixels in the same line in the arrangement direction of the printing elements are printed. In particular, it is preferable that a printing element array to be assigned to a certain pixel be either a printing element array driven at the same driving timing as a driving timing at which a pixel in the same line is printed or a printing element array driven at the following driving timing.
Also in the present embodiment, density variation in dot intervals occurs as described in the first embodiment, and the same method for avoidance can be employed. More specifically, also in printing dots associated with the second driving block (1) to the eighth driving block (7), ejection timings of dots may be advanced by respective time intervals so that the dots land onto an area 171 in the first driving block (0). In a modification example, a print chip may be manufactured in a manner that the physical positions of the printing element arrays are staggered so that all dots land onto the area 171 in the first driving block (0).
Incidentally, in the second embodiment, a description is given of part of printing elements in the print chip 51 as in the first embodiment. However, the present embodiment can be applied similarly to other printing elements and print chips. Furthermore, the numbers of printing element arrays, printing elements provided for each printing element array, driving blocks, and sections for time-division driving may be set or designated to any numbers according to the configurations of the printing apparatus and the print head. For example, the number of printing element arrays may be set to 8, the number of printing elements provided for each printing element array to 1024, the number of driving blocks to 16, the number of sections for time-division driving to 64, and the like.
In addition, the present embodiment can be applied to a connection portion like the first embodiment.
The above-described first and second embodiments are examples using the distribution mask 161 that is relatively small in size for a simple distribution method. However, the size of a distribution mask and a distribution method are not limited to these examples. Distribution masks having various characteristics of any size may be set, for example, distribution masks of a Bayer type, a dot concentration type, a blue noise mask type, and the like.
The above-described first to third embodiments employ the configuration (
An image data processing unit 251 outputs post color separation print data and transmits it to an image printing unit 252. A print data distribution unit 253 distributes the received post color separation print data to each printing element array according to a mask stored in a distribution mask 254. A halftone unit 255 applies halftone processing individually to the distributed print data according to a threshold value matrix stored in a threshold value storage unit 256. A time-division driving unit 257 generates driving signals for the halftone data.
As in the present embodiment, even in the case of performing halftone processing after a distribution mask is applied to the print data, like the first to third embodiments, the print data can be printed on a print medium in a line in an arrangement direction of printing elements.
While an ink jet type is described in the above-described embodiments, any printer can carry out the above-described embodiments as long as it has printing element arrays and each printing element is driven by time-division driving. For example, a printer of, for example, a thermal type or an electrophotography type by LED exposure may be used. Further, in the above-described embodiments, examples are given, but not by way of limitation, of using a distribution mask as distribution information indicating that each of the pixels forming image data is associated with one of the plurality of printing elements. The distribution information may be implemented as a table in which pixel positions are associated with printing elements for printing pixels at the pixel positions.
While a configuration of only an ink jet printer is shown in the above-described embodiments, the above-described embodiments may be applied to a system provided with a plurality of devices (for example, a host computer, an interface device, a reader, and a printer). Further, as described above, image data processing is performed in a printing apparatus, but may also be performed in an external device (a computer) for controlling a printing apparatus. In this case, the external device performs determination processing on binary data for each ejection port array (printing element array) and transfer the binary data to the printing apparatus, and the printing apparatus performs printing based on the transferred data.
In the specification, the term “print” represents not only to form significant information such as letters or graphics but also, whether significant or nonsignificant, to form images, figures, patterns, or the like on a print medium in general or to process a medium. In addition, whether or not the information is displayed so that a human can visually recognize it would not be questioned.
Further, the term “print medium” represents not only paper used for general printing apparatuses but also a medium in general that can accept ink, such as cloth, plastic films, metal plates, glass, ceramics, wood, and leather.
Still further, the term “ink” should be widely interpreted as the definition of the above-mentioned “print”. It represents a liquid that may be associated with formation of images, figures, patterns, or the like, processing of print media, or processing of ink, by being applied onto print media. Furthermore, examples of the processing of ink include solidification or insolubilization of a coloring agent contained in ink applied onto print media.
Embodiment(s) of the present invention 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 invention has been described with reference to exemplary embodiments, it is to be understood that the invention 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. 2014-046528, filed Mar. 10, 2014, which is hereby incorporated by reference wherein in its entirety.
Number | Date | Country | Kind |
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2014-046528 | Mar 2014 | JP | national |