Patent Grant
10654264
The present invention relates to a printing system, a printing control apparatus, and a printing control method.
There is a printing apparatus configured to perform a printing operation during a relative scan of a print head, in which printing elements such as nozzles including ink ejection openings are arrayed, and a print medium in a direction intersecting with the direction of the ejection opening array. In this printing apparatus, the print head is driven concurrently with the relative scan. In the case of supplying power necessary for that from a common power supply, if the power supply is selected on the assumption that it can supply sufficient power even when ink is concurrently ejected from all the ejection openings of the print head and a print medium is conveyed at the maximum speed, the power supply should be a large-capacity one. However, in general, not many images require concurrent ink ejection from all the ejection openings. The use of a reduced-capacity power supply is thus considered, but in the case of a high-duty image including dots widely formed at high density, a shortage of power supply capacity may occur, which causes a void in a printed image.
To counter the above problem, in Japanese Patent Laid-Open No. 2006-289859, the number of nozzles that are concurrently driven to perform ejection operation (hereinafter referred to as “concurrent ejection number”) is calculated in advance based on image data. If the number is greater than or equal to a predetermined value, a conveying speed is reduced or a print scan is divided into several scans. This countermeasure is thus premised on the calculation of the concurrent ejection number. However, in some cases, the concurrent ejection number cannot be calculated only from image data. For example, in a printing apparatus configured to perform printing by means of print heads arranged in parallel in a relative scan direction (conveying direction) of a print medium, adjustment called registration is performed for highly accurate alignment of the positions of dots formed by the print heads. The adjustment value should be taken into consideration when performing the calculation.
Registration includes adjustment between the positions of dots formed by the print heads in the print medium conveying direction (vertical adjustment) and adjustment between the positions of dots formed by the print heads in the ejection opening array direction (horizontal adjustment). In vertical adjustment, depending on a distance between a print head located upstream in the conveying direction and a print head located downstream, a timing of ink ejection by the downstream print head is adjusted. In horizontal adjustment, a print head in which ejection openings are arrayed in a range wider than the width of a print medium is used to adjust a range of ejection openings to be used for printing between print heads in accordance with position displacement between the print heads in the ejection opening array direction. In Japanese Patent Laid-Open No. 2006-7635, adjustment based on an inclination of a print head with respect to the conveying direction (inclination adjustment) is performed as registration. Since the concurrent ejection number changes depending on the adjustments, the adjustment values should be reflected in the calculation of the concurrent ejection number.
However, the installation state of the print heads including a distance between print heads in the conveying direction, position displacement between print heads in the ejection opening array direction, and an inclination of print heads with respect to the conveying direction are different for each printing apparatus. Accordingly, to reflect the adjustment values in concurrent ejection number calculation, the adjustment values set for the printing apparatus must be acquired in advance. However, in a printing system composed of a host apparatus and a printing apparatus, in the case of creating image data before the establishment of communication between the host apparatus and the printing apparatus, the concurrent ejection number cannot be calculated in advance. In this case, the host apparatus first creates only image data, then acquires the adjustment values after the establishment of communication with the printing apparatus, and calculates the concurrent ejection number. The host apparatus then transmits the calculated value to the printing apparatus together with the image data and the printing apparatus determines a conveying speed based on them and starts printing. That is, the conventional printing system has a problem that printing operation cannot be started immediately after the establishment of communication between the host apparatus and the printing apparatus.
In a first aspect of the present invention, there is provided a printing system including a printing apparatus configured to perform printing on a print medium and a printing control apparatus configured to create image data used for printing by the printing apparatus, wherein
the printing apparatus has:
the printing control apparatus has:
the control unit of the printing apparatus sets the conveying speed of the conveying unit based on the maximum concurrent drive number acquired by the acquisition unit of the printing control apparatus and performs printing based on the image data transmitted from the printing control apparatus.
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 be described below in detail with reference to the accompanying drawings. It should be noted that the description below is not intended to limit the claims of the present invention and that not all of the combinations of the features described herein are necessarily required for the means to solve the problem to be solved by the present invention. It should also be noted that the same reference numeral is assigned to the same constituent element and the description thereof may be omitted.
In this specification, “printing” (or “image forming”) does not only express formation of significant information such as characters and figures. “Print medium” widely means any medium capable of receiving ink such as a cloth, plastic film, metal plate, glass, ceramic, wood, or leather, as well as paper used in general printing apparatuses. “Ink” (or “liquid”) should be broadly interpreted in the same way as the above definition of “printing.” That is, the term expresses a liquid that is applied to a print medium to form an image, design, pattern or the like. “Nozzle” collectively means an ejection opening, a liquid path communicating with the ejection opening, and an element that generates energy used for ink ejection, unless otherwise specified.
A system bus of the CPU 220 has a hierarchical bus configuration. For example, the system bus is connected to a local bus such as a PCI bus via a host/PCI bridge 221, further connected to an ISA bus via a PO/ISA bridge 228, and connected to a device on each bus. Blocks in the host apparatus 101 transmit data to and receive data from one another via the system bus. Although not shown, a high-speed memory using a static RAM (SRAM) called L2 cache can be connected to the system bus so as to store codes and data to be continuously accessed by the CPU 220.
A main memory 222 is used as a storage area for temporarily storing execution programs such as the operating system (OS), an application program, and the printer driver. The main memory 222 is also used as a working memory area for execution of each program. The main memory 222 also stores, for example, RGB image data obtained through rendering processing by an application program and ink color data obtained through color space conversion of the RGB image data and corresponding to each of ink colors of print heads of the printing apparatus 102. In the present embodiment, the ink color data is binary data corresponding to each of the ink colors: black, cyan, magenta, and yellow.
The host apparatus 101 expands, on the main memory 222, image data binarized by an error diffusion method or the like, maximum concurrent ejection number data obtained through processing to be described later, and the like. Then, the host apparatus 101 creates print data by adding the maximum ejection number data to the image data and transmits the print data to the printing apparatus 102 via a communication interface 223. The communication interface 223 is, for example, a USB interface or a network interface, and is connected to the PCI bus.
A CRTC 224 is a video controller. The CRTC 224 reads display bitmap data written to a VRAM 225 by the CPU 220 and transfers it to a display 226 such as a CRT, LCD, or PDP. The display 226 allows a user to confirm, for example, a processing progress and processing result of a print job instructed to be printed.
A ROM 229 stores a Basic Input Output System (BIOS) program for controlling input/output devices such as an input device 232 and an FDD 231, an initialization program at power-up, a self-diagnostic program, and the like. The input device 232 is, for example, a keyboard or a pointing device. For instance, a user can use the input device 232 to instruct the printing apparatus 102 to perform printing. An EEPROM 230 is a rewritable nonvolatile memory for storing various permanently-used parameters.
Programs such as the operating system (OS), various application programs, a program that executes each process, and the printer driver corresponding to the printing apparatus 102 are loaded from an HDD 227 into the main memory 222 and executed by the CPU 220. Print data created offline is stored in the HDD 227. Concurrent ejection number acquisition processing is performed at the time of print data creation to be described later.
The printing apparatus 102 includes a RAM 202 for storing print data and maximum concurrent ejection number data, a ROM 203 for storing control programs, concurrent ejection number, and the like, a communication apparatus 204 to be an interface that communicates with the host apparatus 101, and a print head control unit 205 for drive control of each print head. The printing apparatus 102 also includes an EEPROM for example, as a non-volatile memory for storing the various adjustment values also when the printing apparatus 102 is powered off. The printing apparatus 102 also includes an apparatus driving unit 206 for drive control of an actuator for print medium conveyance and the like, and a memory control circuit 207 for control of reading from and writing to (R/W) memories (EEPROMs) 208 to 211 in the respective print heads. A CPU 201 executes various programs stored in the ROM 203 to implement the operation of the present embodiment. The printing apparatus 102 is equipped with line-type print heads corresponding to nozzle arrays of four colors, namely black, cyan, magenta, and yellow, respectively. Although the printing apparatus comprising the print heads corresponding to the above four colors is described as an example in the present embodiment, the printing apparatus may include print heads corresponding to colors other than the above four colors such as light cyan and light magenta and print heads corresponding to a particular color for a specific purpose. Each print head is detachably attached to a carriage or the like.
If an ejection state is changed by adhesion of foreign matter such as dust particles and ink droplets to ejection opening forming surfaces of the print heads 22K, 22C, 22M, and 22Y along with printing by the print heads, the quality of a printed image may be affected. In addition, ink inside ejection openings may be thickened. Accordingly, the printing apparatus 102 has a recovery unit 40 so as to eject ink stably from each of the print heads 22K, 22C, 22M, and 22Y The CPU 220 keeps or recovers a good ink ejection state of the print heads 22K, 22C, 22M, and 22Y by regular recovery processing of the recovery unit 40. The recovery unit 40 is equipped with a cap unit 50 corresponding to each print head and including a cap configured to cap the ejection opening forming surface while printing operation is not performed. For cleaning the ejection opening forming surface, the cap unit 50 comprises a blade for performing wiping operation of the ejection opening forming surface and a blade holding member. The cap unit 50 further comprises a unit configured to remove ink received by the cap during so-called suction recovery and preliminary ejection. In addition, the printing apparatus 102 is equipped with ink tanks 28K, 28C, 28M, and 28Y storing inks to be supplied to the respective print heads, pumps configured to fill the respective print heads with the inks, pumps used for recovery operation, and the like.
The print medium P, which is shown as a roll sheet in
The CPU 220 determines a standard value of an ejection timing of each print head based on a relationship between the conveying speed and distances between the print heads. However, an error in mounting positions of the print heads leads to print position deviation (deviation of the positions of dots formed by nozzles). To correct the print position deviation, the CPU 220 determines an ejection timing adjustment value using a test pattern composed of pattern elements printed at regular intervals at the time of installation of the printing apparatus 102 or at a time when a user requests correction of the position deviation. This value is used for adjustment of the ejection timing in the conveying direction of the print medium P, which corresponds to the vertical adjustment described above. Further, depending on the position deviation between the print heads in the ejection opening array direction, the horizontal adjustment for adjusting the range of ejection openings to be used for printing between the print heads and the inclination adjustment based on an inclination of the print heads with respect to the conveying direction are also performed.
Power necessary for conveyance of the print medium P, ink ejection operation from each print head (22K, 22C, 22M, and 22Y), and the like is supplied from a single power supply unit (not shown). The necessary power is not constant and increases with the conveying speed of the print medium P and the total number of nozzles of the print heads driven concurrently (concurrent ejection number). Not many images require formation of dots at high density in a large area by, for example, concurrent ejection from substantially all the nozzles of the print heads (22K, 22C, 22M, and 22Y). In view of this, it is not so advantageous to use a power supply unit having such a large capacity as to enable concurrent ejection from all the nozzles of the print heads (22K, 22C, 22M, and 22Y) during conveyance operation in a mode of conveying the print medium P at high speed. Therefore, the power supply capacity of the power supply unit is minimized and the mode is automatically changed to a low-speed mode in a case where a concurrent ejection number (the number of nozzles) of each print head exceeds a predetermined number (the number of dots as a threshold of power supply capacity), thereby dealing with high-duty image data, namely high-density image data.
The vertical adjustment, the horizontal adjustment, and the inclination adjustment will be described below.
An interval (mm) between two arbitrary points in the arrow A direction (corresponding nozzles of adjacent print heads in the arrow A direction) on the print medium P can be converted into the number of dots by using a print resolution (dpi) in the arrow A direction. In a case where an interval between adjacent print heads is a specified interval, that is, in a case where each of an interval between the print heads 22K and 22C and an interval between the print heads 22C and 22M is a specified interval, it is assumed that the specified interval corresponds to n dots. In this state, the images 401K, 401C, and 401M are formed at regular intervals of n dots in the arrow A direction. In contrast, in a case where the print head 22Y is displaced to the print head 22M side by z dots as shown by the chain double-dashed line, an interval between the images 601Y and 401M corresponds to (n−z) dots. Accordingly, in the case of adjusting ejection timings of adjacent print heads to n dots based on the interval between the images 401M and 601Y formed by concurrent ejection, the ejection timing of the print head 22Y is set at a timing earlier by a time period Z obtained by dividing z dots by the set conveying speed. In the present embodiment, the Z value at this time is defined as an ejection timing adjustment value or a vertical adjustment value. In a case where the ejection timing is required to be late, that is, for example, in a case where the print head 22Y is displaced by z dots in a direction away from the print head 22M, a negative value of Z (−Z) can be set as the ejection timing adjustment value.
On the contrary, on the basis of the state where the ejection timing has already been adjusted, for example, if it is found that the ejection timing adjustment value is Z, the ejection timings of the print heads 22K to 22Y can be set so that an interval between images formed by concurrent ejection corresponds to a certain number of dots (n−z).
As described above, the nozzles of each print head correspond to a print medium having the largest dimension in the width direction and are arrayed in a region wider than the largest print width of the print medium. That is, both sides of each print head has a predetermined number of extra nozzles that are arranged uniformly, for example. Printing is generally performed by using the most of a group of nozzles in the central area exclusive of the extra nozzles, but the extra nozzles are used if there is a need for horizontal adjustment. To avoid the deviation of the image 901Y as shown in
The horizontal adjustment is used not only for avoiding color deviation in the horizontal direction but also for horizontally shifting the nozzle use ranges of the print heads of all the colors to prevent a load from being applied to a specific nozzle by continuously forming vertical ruled lines (images in the form of vertical ruled lines extending in the medium conveying direction) at the same position. Since the present embodiment has no need to distinguish between horizontal color deviation adjustment and adjustment for shifting vertical ruled lines, they can be collectively treated as horizontal adjustment.
The various adjustment values described above are input to the host apparatus 101 by a user after the user visually determines a test pattern output by the printing apparatus 102, whereby the values are stored in the EEPROM 213 of the printing apparatus 102. In a case where the printing apparatus 102 comprises an input unit that accepts input by a user, the values may be set via the input unit.
The CPU 201 performs printing operation while performing registration based on the adjustment values described above. At this time, the conveying speed of the print medium P is changed based on data about a maximum concurrent ejection number calculated by the host apparatus 101. In a conventional method, as described above, in the case of creating print data, the host apparatus 101 acquires adjustment values to be reflected in calculation from the printing apparatus 102 and performs calculation. Accordingly, printing operation cannot be started immediately after the establishment of communication between them. Further, there is a case where the printing system is configured so that a plurality of printing apparatuses are connected to the host apparatus 101 and the same image can be printed. In this case, the host apparatus 101 is required to receive adjustment values from each printing apparatus and perform concurrent ejection number calculation based on the adjustment values specific to each printing apparatus. As a result, the host apparatus 101 cannot efficiently perform processing. Further, if the printing apparatus 102 receives only image data from the host apparatus 101 and the CPU 201 performs concurrent ejection number calculation based on the image data and the adjustment values set for the printing apparatus 102, it takes time to start printing.
In view of the above, in the present embodiment, the host apparatus 101 calculates a maximum value of the number of nozzles that may be driven (hereinafter “maximum concurrent ejection number”) based on the image data and the amount of deviation of dot formation positions that may occur in the printing apparatus 102. Then, the host apparatus 101 transmits maximum concurrent ejection number data together with the image data to the printing apparatus 102. In the printing apparatus 102, the CPU 201 sets the conveying speed based on the received maximum concurrent ejection number data.
First, in step S1201, the CPU 220 creates print data. This will be described later in detail with reference to the flowchart of
The CPU 201 of the printing apparatus 102 receives the print data in step S1203 and analyzes maximum concurrent ejection number data included in the print data (step S1204). Then, the CPU 201 sets the conveying speed at high speed (step S1205) if the maximum concurrent ejection number is less than a predetermined value and sets the conveying speed at low speed (step S1206) if the maximum concurrent ejection number is equal to or greater than the predetermined value. After that, the processing advances to step S1207. The CPU 201 performs printing operation on the print medium 104 and finishes the printing operation. The printing operation in step S1207 is performed based on various adjustment values set for the printing apparatus 102.
Instead of the CPU 201 of the printing apparatus 102 analyzing the maximum concurrent ejection number data, the CPU 220 of the host apparatus 101 can directly determine a printing speed based on the maximum concurrent ejection number data. In this case, data designating the printing speed is added to the print data and transmitted to the printing apparatus 102. The CPU 201 of the printing apparatus 102 sets the printing speed based on this designation of the printing speed.
A print head inclination adjustment value used for calculation described below is set based on an assumed inclination. In the present embodiment, it is assumed that the value can be set in a range from −hs to +hs (hs is a positive integer). In step S1403, a minimum value −hs is set as an inclination adjustment value of the print head of the target color (K at first). Next, the processing advances to step S1404 and ejection number calculation is performed. An ejection number calculation method will be described below with reference to
A case where the host apparatus 101 calculates ejection numbers without obtaining the horizontal adjustment value from the printing apparatus 102 is assumed. In this case, in order to correctly calculate ejection numbers corresponding to all the moments (drive positions of nozzles corresponding to all the rasters), the CPU 220 of the host apparatus 101 is required to make calculation by the number of times obtained by shifting the horizontal adjustment value from −r to +r one by one, that is, (2r+1) times. Moreover, this calculation is for one head. The CPU 220 is required to make the calculation by the number of times obtained by multiplying the number of rasters L in one image by the total number of print heads.
The sum of the ejection numbers in the region 1601 printed by the nozzles in the left half of the print head and the additional region thereof is (w/2)+r dots. That is, the region 1601 printed by the nozzles in the left half of the print head and the additional region thereof overlap the dot-ON shaded portion 1604 by (w/2)+r dots. In contrast, the sum of the ejection numbers in the region 1602 printed by the nozzles in the right half of the print head and the additional region thereof is 0 dots. That is, neither the region 1602 printed by the nozzles in the right half of the print head nor the additional region thereof overlaps the dot-ON shaded portion 1604.
As a result, the sum of the ejection numbers in the predetermined raster is (w/2)+r dots. This is a maximum value among possible values of the concurrent ejection number. In other words, the maximum possible concurrent ejection number can be obtained only by one calculation of adding the ejection number in the case of the maximum horizontal adjustment value of +r to the ejection number in the case of the minimum horizontal adjustment value of −r.
As shown in
However, the horizontal adjustment value is not switched at least during printing of one image. Thus, the above situation never actually occurs.
However, in the present embodiment, a higher priority is given to a calculation speed than the accuracy of a calculation result. Further, an error in a calculation result occurs in a direction of increasing the ejection number. Therefore, the error expands a margin of control and does not affect an image.
Next, in step S1405, the CPU 220 determines whether the ejection number calculated in step S1404 is greater than a value stored in a position indicated by a raster number in a current target color in the ejection number list. If it is greater, the processing advances to step S1406. Otherwise the processing advances to step S1407. In step S1406, the CPU 220 updates the ejection number list by storing the ejection number calculated in step S1404 in the current position in the ejection number list and then advances to step S1407.
In step S1407, the CPU 220 determines whether the inclination adjustment value of the print head of the calculation target color has reached the maximum value hs. The processing advances to step S1408 if YES and advances to step S1409 if NO. In step S1408, the CPU 220 determines whether the raster number in the calculation target color has reached L (the number of rasters in one page). The processing advances to step S1410 if YES and advances to step S1411 if NO. On the other hand, in step S1409, the CPU 220 adds one to the inclination adjustment value for the print head of the calculation target color, returns to step S1404, and repeats the subsequent procedure.
In step S1410, the CPU 220 determines whether the calculation target color is Y that is ejected by the print head 22Y located on the most downstream side in the medium conveying direction. If the calculation target print head color is other than Y, the processing advances to step S1412. On the other hand, in step S1411, the CPU 220 adds one to the raster number in the calculation target color, returns to step S1403, and repeats the subsequent procedure.
In step S1412, the host apparatus 101 changes the calculation target color to the next color, returns to step S1402, and repeats the subsequent procedure. In the present embodiment, the print heads 22K, 22C, 22M, and 22Y are arranged in this order from the upstream side in the medium conveying direction. Accordingly, the calculation target color is switched in the order of K, C, M, and Y. If the calculation target color is Y in step S1410, the CPU 220 finishes the ejection number list creation.
In
Next, in step S2104, the CPU 220 adds, to SyncX, a maximum concurrent ejection number of C within an adjustable range of the ejection timing adjustment value of C. In the example of
In step S2105, the CPU 220 adds, to SyncX, a maximum concurrent ejection number in M within an adjustable range of the ejection timing adjustment value of M. In the example of
In step S2106, the CPU 220 adds, to SyncX, a maximum concurrent ejection number in Y within the entire adjustable range of the ejection timing adjustment value of Y. In the example of
In step S2107, the CPU 220 determines whether SyncX is greater than SyncMax. If YES, the CPU 220 advances to step S2108, updates SyncMax by substituting the value of SyncX for SyncMax, and then advances to step S2109. If NO, the CPU 220 immediately advances to step S2109.
In step S2109, the CPU 220 determines whether y has reached the maximum serial number L+3n in one image. If NO, the CPU 220 advances to step S2110, add one to y, returns to step S2103, and repeats the subsequent procedure. If YES, the maximum concurrent ejection number calculation is finished.
As described above, in the present embodiment, without acquiring the vertical adjustment value, the inclination adjustment value, or the horizontal adjustment value from the printing apparatus, the maximum possible concurrent ejection number is calculated in consideration of all the ranges of the adjustment values in the host apparatus (printing control apparatus). Accordingly, a time required for starting printing operation after the establishment of communication between the host apparatus and the printing apparatus can be reduced and printing operation can be performed at optimum conveying speed without a shortage of power supply capacity. Further, in a case where the printing system is configured so that a plurality of printing apparatuses are connected to the host apparatus and the same image can be printed, the host apparatus does not need to receive the adjustment values from each printing apparatus, which is advantageous to efficient processing.
The present invention is not limited to the embodiment and modifications described above. For example, the present invention can be applied to a printing apparatus and system having printing unit other than inkjet print heads as long as the printing apparatus has a shortage of power supply capacity depending on the maximum concurrent drive number in printing elements. In addition, the number of print heads, colors used for printing, and the order of arrangement can be determined as appropriate. Furthermore, the present invention does not exclude application to a system using a printing apparatus in the form of a serial printer. The application of the present invention is effective as long as a print head is driven concurrently with a scan of a print medium and a shortage of power supply capacity occurs depending on the maximum concurrent drive number of printing elements. As a matter of course, values used in course of calculation such as z, n, and T can be set as appropriate within the range of possibility of registration processing.
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 Applications No. 2017-209645 filed Oct. 30, 2017, and No. 2018-197837 filed Oct. 19, 2018, which are hereby incorporated by reference herein in their entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2017-209645 | Oct 2017 | JP | national |
| 2018-197837 | Oct 2018 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 6969155 | Umezawa | Nov 2005 | B2 |
| 10300694 | Kaburagi | May 2019 | B2 |
| Number | Date | Country |
|---|---|---|
| 2006-007635 | Jan 2006 | JP |
| 2006-289859 | Oct 2006 | JP |
| Entry |
|---|
| U.S. Appl. No. 16/172,904, Yusuke Tanaka Daichi Nitta, filed Oct. 29, 2018. |
| Number | Date | Country | |
|---|---|---|---|
| 20190126615 A1 | May 2019 | US |
