Image processing device, control method thereof, and program

Abstract

To restrict a cost increase by restricting an increase in an amount of print data held by holding means and reducing the scale of a circuit forming the holding means.SOLUTION: An image processing device includes: holding means configured to hold print data of a number of lines corresponding to an amount of positional deviation of a nozzle with respect to a direction orthogonal to a conveyance direction of a recording medium; and correction means configured to correct the print data for each line held by the holding means, based on the amount of positional deviation of the nozzle with respect to the direction orthogonal to the conveyance direction; wherein the correction means performs a process of correcting the print data for each N lines, held by the holding means, N times while shifting the print data by one line.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to an image processing apparatus, a control method thereof, and a program. [Background technology]

[0002] In inkjet recording devices, one recording method that is advantageous for improving recording speed is a method of recording using a full-line type recording head. A full-line type recording head is configured with an array of many nozzles and is fixed to the recording device body so that the direction of the array coincides with the paper width direction. Since recording can be performed by transporting the recording medium while the recording head remains fixed, recording at higher speeds is possible compared to recording devices with moving recording heads. Various countermeasures have been proposed for such full-line type recording heads to achieve high-quality recording without color shift or tilt due to the shape or assembly accuracy of the recording head.

[0003] Patent Document 1 discloses a mechanism for arranging multiple recording heads to form a full-line type recording head and rotating each individual recording head. Furthermore, Patent Document 2 discloses a configuration in an electrophotographic image forming apparatus in which correction is performed electrically by processing print data, eliminating the need for mechanical adjustment or adjustment processes during assembly. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-125806 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-170755 Summary of the Invention [Problem to be solved by the invention]

[0005] The method described in Patent Document 1 requires a rotatable mechanism for the recording head holder, which requires mechanical adjustment and increases the number of parts, leading to increased costs. Furthermore, the method described in Patent Document 2 requires a line buffer for the amount required for correction. The amount of line buffer space depends on the width to be corrected and the resolution of the print data to be processed.

[0006] For example, if the width to be corrected is 1 mm and the print data resolution is 1200 dpi, then (1 mm ÷ 25.4 mm / inch) × 1200 dpi ≈ 95, so a line buffer of about 95 lines is required, and if the print data resolution is 2400 dpi, a line buffer of twice this size is required. The higher the print data resolution, the greater the amount of memory used by the line buffer, which increases the circuit scale that forms the memory and causes costs to rise.

[0007] The present disclosure aims to suppress an increase in the amount of print data stored in a storage unit, reduce the circuit scale that forms the storage unit, and suppress an increase in costs. [Means for solving the problem]

[0008] One aspect of the present invention is a method for printing an image, comprising: a storage unit capable of storing print data for a number of lines corresponding to the amount of misalignment of nozzles in a direction perpendicular to the conveyance direction of a recording medium; a correction unit that corrects the print data for each line held by the holding unit based on the amount of nozzle positional deviation in a direction perpendicular to the transport direction; Equipped with The correction means executes a process of correcting the print data for every N lines held by the holding means N times, shifting the process by one line at a time. death, The printer has a first print mode in which printing is performed at a first resolution based on print data, and a second print mode in which printing is performed at a second resolution that is N times (N is a natural number equal to or greater than 2) the first resolution based on print data. An image processing device comprising: [Effects of the Invention]

[0009] In the present disclosure, the process of correcting print data for every N lines held in the holding means is executed N times, shifting the data by one line at a time. As a result, if the present disclosure has holding means for N lines, it is possible to correct print data for more than N lines, thereby suppressing an increase in the amount of print data held by the holding means, reducing the circuit scale forming the holding means, and suppressing increases in costs. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 2 is a diagram showing the configuration of a print control unit of the recording apparatus according to the first embodiment. [Figure 2] FIG. 2 is a diagram illustrating the configuration of a recording head according to the first embodiment. [Figure 3] FIG. 4 is a diagram showing the inclination of the recording head according to the first embodiment. [Figure 4] 5A to 5C are diagrams for explaining the principle of a correction method according to the first embodiment. [Figure 5] FIG. 4 is a diagram illustrating a discharge interval according to the first embodiment. [Figure 6] FIG. 2 is a detailed configuration diagram of a print data correction unit according to the first embodiment. [Figure 7] 6 is a flowchart of a print data correction process according to the first embodiment. [Figure 8] FIG. 3 is an explanatory diagram of print data stored in an image memory according to the first embodiment. [Figure 9] 10 is a flowchart of a print data correction process according to the second embodiment. [Figure 10] FIG. 10 is an explanatory diagram of print data stored in an image memory according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the invention claimed. Although multiple features are described in the embodiments, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.

[0012] (First embodiment) The first embodiment will be described in detail below with reference to the drawings. A print control unit 100 that performs data flow processing for an inkjet recording device in this embodiment will be described with reference to FIG. 1. The inkjet recording device and print control unit 100 are an example of an image processing device. An operator issues instructions to the recording device from an operation unit 120 connected to an operation unit I / F unit 105, and the instructions are input to a CPU 101 via the operation unit I / F unit 105. The operation unit 120 is a user interface such as a touch panel screen and buttons, and can be operated by an operator to input various instructions and information to the print control unit 100. The operation unit I / F unit 105 functions as an interface between the operation unit 120 and the CPU 101.

[0013] CPU 101 controls each unit in print control unit 100 in response to instructions from operation unit 120 or network 121. Network 121 is a network such as the Internet or a LAN, and may be a wired network or a wireless network. CPU 101 controls each unit based on a control program stored in ROM 102, for example. The control program stored in ROM 102 includes an OS for time-sharing control in units of load modules called tasks using a system clock. CPU 101 uses RAM 103 as a working area for processing. Each unit in print control unit 100, including CPU 101, is connected to system bus 111. Image memory 104 may include a DRAM with the capacity necessary for print control.

[0014] The print control unit 100 has a host I / F unit 106. The image data generation unit 107 renders print data input from the network 121 via the host I / F unit 106 and converts it into multi-value bitmap data. The input print data is data written in, for example, PDL (page description language). The print data generation unit 108 performs processes such as ink color conversion and quantization on the multi-value bitmap data to convert it into ink color halftone data. Furthermore, the print data generation unit 108 assigns the halftone data to each nozzle for each ink color, and generates print data (binary data) for each line based on the number of nozzles. Note that the print data also includes data for images other than characters. The print data generation unit 108 stores the print data generated in this way in the image memory 104.

[0015] CPU 101 transfers the print data stored in image memory 104 to print data correction unit 109, which performs print data correction processing described below. Print data correction unit 109 transfers the print data that has undergone print data correction processing to print unit 122 via engine I / F unit 110. Print unit 122 includes a recording head having nozzles arranged in a row along the main scanning direction, which is the width direction of the recording medium, and controls the ejection of ink from the nozzles based on the transferred print data, causing ink to be ejected sequentially onto a recording medium such as paper being transported by the recording device.

[0016] FIG. 2 is a configuration diagram of the nozzle arrangement in the print head 200. FIG. 2(a) shows the print head 200 having 16,384 nozzles 201 arranged in a row along the main scanning direction, which is the width direction of the print medium. The main scanning direction is perpendicular to the direction in which the print medium is transported. The direction in which the nozzles 201 are arranged (nozzle row direction) is an example of the arrangement direction. Ideally, the arrangement direction is parallel to the main scanning direction. In this embodiment, the nozzles 201 are arranged at 1200 dpi (the spacing between nozzles is 1 / 1200 inch), and the print head 200 has a printing width of approximately 346 mm. The print head 200 can eject ink from the nozzles 201 based on print data.

[0017] 2(b) shows the configuration of a recording head 210 in which an additional nozzle row, identical to the nozzle row shown in FIG. 2(a), is added to the recording head 200 in the sub-scanning direction. The sub-scanning direction is parallel to the direction in which the recording medium is transported. The printing unit 122 controls the printing timing of multiple nozzle rows, enabling faster printing and enabling the nozzles in other rows to compensate for ink ejection when some nozzles fail and are no longer able to eject ink.

[0018] On the other hand, Figure 2(c) shows the configuration of a print head 220 (a print head 220 having 1024 nozzles arranged in a single row along the nozzle row direction) that is shorter in width than the print head described above. Making precision components like print heads large can result in poor yields and increased costs. By combining small print heads like print head 220, component costs can be reduced.

[0019] FIG. 3 illustrates the installation of a print head in a printing apparatus and the positional relationship between the print head and the print medium. In FIG. 3(a), the print head 200 is installed so that the nozzle row direction in the print head 200 is parallel to the main scanning direction and perpendicular to the sub-scanning direction, which is the transport direction. That is, FIG. 3(a) shows the ideal installation of the print head 200. In FIG. 3(b), the print head 200 is installed tilted by Pmax lines from the main scanning direction. That is, the line corresponding to the nozzle on the right side of the print head 200 is Pmax lines above the line corresponding to the nozzle on the left side of the print head 200. When ink is ejected based on print data with the print head 200 installed tilted with respect to the main scanning direction, the image formed on the print medium will be tilted.

[0020] 3(c) shows that the print head 220 shown in FIG. 2(c) is intentionally tilted with respect to the main scanning direction. When print heads 220 with nozzles arranged at 1200 dpi are arranged in a straight line along the main scanning direction, the outer periphery of the housing of the print head 220 causes the spacing between the nozzles at one end of the print head 220 to differ from the spacing at the center of the print head 220. Therefore, the print head 220 is tilted and installed so that some of the print head components overlap in the main scanning direction, thereby ensuring a constant nozzle spacing in the main scanning direction.

[0021] In Fig. 3(d), multiple recording heads 200 are installed for each ink color at an angle to the main scanning direction. In this state, if ink is ejected using print data that has not been corrected by the correction process described below, the image formed on the recording medium will be formed in a different position for each ink color, resulting in color misalignment of the image formed on the recording medium compared to the case of Fig. 3(b).

[0022] Next, the principle of the correction process performed by print data correction unit 109 of this embodiment will be described with reference to Fig. 4. Fig. 4 is a diagram for explaining the principle of the correction process of print data according to this embodiment.

[0023] FIG. 4(a) is a diagram showing the deviation of the ink ejection position of each nozzle (i.e., the nozzle position) from the ideal position (the ink ejection position of each nozzle (i.e., the nozzle position) when the print head 200 is installed at an angle as shown in FIG. 3(b)). In FIG. 4(a), the horizontal axis represents the main scanning direction, and the vertical axis represents the sub-scanning direction. FIG. 4(a) illustrates an example in which the function connecting the ink ejection positions of each nozzle when the print head 200 is tilted, i.e., arranged in an arrangement direction intersecting the main scanning direction, can be expressed by a linear equation. However, the deviation may be as shown in FIG. 3(c) or a curved deviation. Furthermore, in the case of a printing apparatus having multiple print heads as shown in FIG. 3(d), the deviation may be defined not as the deviation from the ideal position, but as the amount of deviation based on the ink ejection position of a print head corresponding to a reference ink color, for example, K (black).

[0024] FIG. 4B shows an example of a table REG_SEG_POS[i] in which the offset in the sub-scanning direction for each nozzle position shown in FIG. 4A is registered, expressed in terms of the sub-scanning resolution of the print data. For example, as shown in FIG. 3B, assume that the print head 200 (with a main scanning width of approximately 364 mm) is tilted 2 mm relative to the main scanning direction. Assume that the nozzle array is spaced 1200 dpi apart and the print data is 1200 dpi in the sub-scanning direction. In this case, the print data is shifted by one line in the sub-scanning direction for approximately every 174 nozzles. The nozzle array in the print head 200 is numbered from the leftmost nozzle to the rightmost nozzle, as 0th, 1st, ..., 16383rd. The offset in the sub-scanning direction for the i-th nozzle in the print head 200 is registered in REG_SEG_POS[i] (i = 0, 1, 2, ..., 16383). In this case, Pmax, which is the amount of positional deviation converted into the number of lines, is approximately 94. CPU 101 sets the number of lines of Pmax in print data correction unit 109, which then performs correction processing, which will be described later.

[0025] Figure 4(c) shows how print data correction unit 109 outputs print data (bottom of Figure 4(c)) while switching the print data for each line (top of Figure 4(c)) to offset the misalignment in the sub-scanning direction. Here, line n indicates the line that should have been printed. The black portion in Figure 4(c) indicates the print data that is transferred to printing unit 122 when printing line n. In this way, when the lines of print data are switched and output so as to offset the misalignment in the sub-scanning direction, the image formed on the recording medium can be prevented from tilting.

[0026] FIG. 5 illustrates the ejection interval of a nozzle in the sub-scanning direction in the main scanning direction. The positions of the print head 200 and nozzle 201 are fixed, and the print medium transported by the printing device passes below the print head 200 in the sub-scanning direction. FIG. 5(a) shows how the nozzle 201 of the print head 200 ejects ink in a normal resolution print mode. The print head 200 ejects ink droplets 510, 511, and 512 using the nozzle 201 based on the transferred print data, and the ejected ink lands on the print medium. The printing device controls the ink ejection time interval Td and the ejection interval length Ld to be constant depending on the print medium transport speed in the sub-scanning direction. For example, if the print device's sub-scanning resolution is 1200 dpi and the transport speed is 200 mm / sec, Ld is approximately 21 μm and Td is approximately 9.5 msec.

[0027] Figure 5(b) shows how the nozzles 201 of the print head 200 eject ink in a print mode in which the print medium transport speed is halved, for example, to 100 mm / sec, while the ejection time interval remains the same as in Figure 5(a). By ejecting inks 530, 531, and 532 that could not be ejected in Figure 5(a), the print head can increase the amount of ink ejected onto the print medium. In other words, Figure 5(b) shows a print mode in which high-resolution printing is performed.

[0028] The ink ejection interval of the print head is limited by constraints such as ink refill time. Therefore, a printing device may perform this type of control to increase the ejection volume or to improve the resolution of the image in the sub-scanning direction. In this case, the print head 200 must transfer twice the amount of print data per unit print area in the sub-scanning direction compared to normal. Furthermore, the lines corrected by the correction process described with reference to Figure 4 must be corrected twice as much in the sub-scanning direction compared to normal. For example, a 2 mm ejection position deviation corresponds to approximately 94 lines at 1200 dpi, but approximately 189 lines at 2400 dpi. Therefore, even with the same physical deviation of 2 mm, the deviation increases as the resolution in the sub-scanning direction increases.

[0029] Next, the configuration of the print data correction unit 109 will be described with reference to Fig. 6. Fig. 6 is a block diagram showing the detailed configuration of the print data correction unit 109 of the print control unit 100 according to the first embodiment.

[0030] The register unit 605 has multiple registers. Instructions from the CPU 101 to the print data correction unit 109 are given by the CPU 101 writing appropriate values ​​into the register unit 605. The values ​​written by the CPU 101 include the table REG_SEG_POS shown in FIG. 4(b) described above.

[0031] Based on the values ​​stored in the register unit 605, the control unit 604 controls the operations of the image reading unit 601, the correction processing unit 602, and the image writing unit 603, which will be described later.

[0032] Based on the control of each register of the register unit 605 and the control unit 604 , the image reading unit 601 reads out print data stored in a predetermined area of ​​the image memory 104 line by line, and outputs it to the correction processing unit 602 .

[0033] The correction processing unit 602 performs correction processing on one line of print data received from the image reading unit 601 based on the table REG_SEG_POS written in the register unit 605, and outputs the corrected print data to the image writing unit 603. The correction processing unit 602 has a line buffer that can store multiple lines of print data in the main scanning direction. The line buffer is configured to hold print data for a number of lines corresponding to the amount of nozzle positional deviation. In this embodiment, the line buffer is assumed to be SRAM that allows high-speed access, but other types of memory may also be used. The recording apparatus of this embodiment has a line buffer that can store 96 lines of print data, which can correct a 2 mm ejection position deviation at a sub-scanning resolution of 1200 dpi, for example. When 96 lines of print data are stored in the line buffer, the correction processing unit 602 deletes the oldest print data stored in the line buffer each time one line of print data is input, and then stores the input print data in the line buffer.

[0034] By performing these operations, the correction processing unit 602 can secure print data for the number of lines required for correction processing in the line buffer. The correction processing unit 602 selects print data for one line from the print data for multiple lines stored in the line buffer based on the values ​​stored in each register of the register unit 605 and each position (position in the main scanning direction) on the line being processed, and outputs the data corresponding to that position in the selected print data.

[0035] For example, when the value of REG_SEG_POS[i] is smaller, the correction processing unit 602 selects print data stored in the line buffer earlier, and when the value of REG_SEG_POS[i] is larger, the correction processing unit 602 selects print data stored in the line buffer closer to the present. The correction processing unit 602 outputs a set of data output for each position on the line being processed as corrected print data for that line. In this way, the correction processing unit 602 performs correction processing by switching and outputting lines of print data according to the amount of deviation in the sub-scanning direction for each position in the main scanning direction.

[0036] The image writing unit 603 writes the corrected print data output from the correction processing unit 602 into the image memory 104 based on the values ​​stored in the registers of the register unit 605 and the control of the control unit 604 .

[0037] Next, the correction process performed by the print data correction unit 109 of this embodiment and the print data before and after the correction process will be described with reference to Figures 7 and 8. Figure 7 is a flowchart showing the operation of the control unit 604 of the print data correction unit 109. Figure 8 shows the table REG_SEG_POS and the print data stored in the image memory 106.

[0038] Here, the values ​​that CPU 101 writes to register unit 605 include, in addition to the table REG_SEG_POS mentioned above, the address (read start address) REG_SA_RD at which reading starts in the memory area in image memory 104 where pre-corrected print data is stored, the address (write start address) REG_SA_WR at which writing starts in the memory area in image memory 104 where post-corrected print data is stored, the width in the main scanning direction REG_LINE_WIDTH and the width in the sub-scanning direction REG_LINES of the print data to be processed, and the amount of address change REG_LOFST from the start address of the print data of the line of interest to the start address of the print data of the next line, as shown in FIG.

[0039] When print data correction processing is started in response to an instruction from CPU 101, control unit 604 first performs processing (initialization steps) from step S101 to step S107. In step S101, control unit 604 determines whether the instruction from CPU 101 is an instruction to execute high-resolution processing. In this embodiment, if CPU 101 instructs that 1200 dpi be used as the resolution in the sub-scanning direction during ejection, control unit 604 determines "No" and performs normal resolution processing steps S102, S103, and S104. On the other hand, if CPU 101 instructs that 2400 dpi be used as the resolution in the sub-scanning direction, control unit 604 determines "Yes" and performs high-resolution processing steps S105, S106, and S107.

[0040] Figures 8(a) and 8(c) show print data (input image) before correction stored in image memory 106. Figure 8(a) shows print data (input image) to be processed when control unit 604 determines in step S101 that high-resolution processing is not required. Figure 8(c) shows print data to be processed when control unit 604 determines in step S101 that high-resolution processing is required.

[0041] In step S102, the control unit 604 sets the number of times of processing. Here, the control unit 604 sets the print data of all lines to be processed to be processed in one processing flow (sets the number of times of processing to 1). Next, in step S103, the control unit 604 sets the value of REG_LOFST as an additional value for updating the address in the image memory 104 where the next processing starts after processing one line. This processing is processing in which the control unit 604 sets the value of REG_LINES as the number of lines to be processed in one processing.

[0042] Meanwhile, in step S105, the control unit 604 sets the print data for all lines to be processed so that it is processed in two processing flows (sets the number of processing times to two). When processing an image with a high resolution N times the normal resolution, the control unit 604 sets the number of processing times to N, where N is a natural number equal to or greater than 2. Next, in step S106, the control unit 604 sets a value twice the value of REG_LOFST as an additional value used to update the address in the image memory 104 where the next processing starts after processing one line. This processing is processing in which the control unit 604 sets a setting so that after processing one line, it processes a line that is skipped by one line. In other words, the control unit 604 processes every two lines. When processing an image with a high resolution N times the normal resolution, the control unit 604 processes every N lines.

[0043] In step S107, the control unit 604 sets the number of lines to be processed in one processing cycle to half the value of REG_LINES. Note that this embodiment targets print data with a resolution twice the normal resolution. However, when processing print data with a resolution N times the normal resolution, where N is an integer, the control unit 604 sets the number of processing times to N in step S105, sets the address addition value to N times the value of REG_LOFST in step S106, and sets the number of processing lines to 1 / N of the value of REG_LINES in step S107.

[0044] Next, in step S108, the control unit 604 sets a read start address and a write start address depending on the number of times the process of step S108 has been executed. In the first step S108, the control unit 604 sets the value of REG_SA_RD as the read start address and the value of REG_SA_WR as the write start address. In the second step S108, the control unit 604 sets the value obtained by adding the value of REG_LOFST to the value of REG_SA_RD as the read start address, and sets the value obtained by adding the value of REG_LOFST to the value of the write start address REG_SA_WR.

[0045] As explained in steps S101 to S108, if the control unit 604 determines in step S101 that high-resolution processing is not required, it sets the processing to be performed line by line, and if it determines that high-resolution processing is required, it sets the processing to be performed over the entire length of the print data in the transport direction, processing odd-numbered lines the first time and even-numbered lines the second time.

[0046] In step S109, the control unit 604 uses the image reading unit 601 to read one line of print data from the read start address in the image memory 104. In step S110, the control unit 604 updates the read start address by adding the addition value set in step S103 or step S106 to the read start address. In step S111, the control unit 604 uses the image reading unit 601 to store one line of print data read in step S109 in the line buffer of the correction processing unit 602.

[0047] Next, in step S112, the control unit 604 determines whether the image reading unit 601 has read the print data necessary for the correction process from the image memory 104 and stored it in the line buffer. In this embodiment, the control unit 604 determines that the print data necessary for the correction process has been stored when it reads one line of print data and stores it in the line buffer. Note that the control unit 604 may also determine that the print data necessary for the correction process has been stored when the image reading unit 601 reads the print data for the number of lines corresponding to the maximum value registered in the table REG_SEG_POS from the image memory 104 and stores it in the line buffer. If the control unit 604 determines that the print data necessary for the correction process has been stored in the line buffer, the process proceeds to step S113. On the other hand, if the control unit 604 determines that the print data necessary for the correction process has not been stored in the line buffer, the process returns to step S109.

[0048] In step S113, the control unit 604 controls the correction processing unit 602 to select and acquire one piece of print data that has not yet been selected from the multiple lines of print data stored in the line buffer as selected print data. In step S114, the control unit 604 controls the correction processing unit 602 to perform correction processing to acquire corrected print data by correcting the selected print data. Here, the control unit 604 controls the correction processing unit 602 to perform correction processing, which is processing to acquire corrected print data based on the print data of the line selected based on the table REG_SEG_POS, which indicates the amount of deviation in the sub-scanning direction. More specifically, the correction processing unit 602 acquires the value of REG_SEG_POS[i] for the i-th nozzle on the selected line.

[0049] When the value of REG_SEG_POS[i] is smaller, the correction processing unit 602 selects print data stored in the line buffer earlier, and when the value of REG_SEG_POS[i] is larger, the correction processing unit 602 selects print data stored in the line buffer closer to the present. For example, when REG_SEG_POS[i] = 0, the correction processing unit 602 selects print data 40 lines before the selected line, and when REG_SEG_POS[i] = 10, the correction processing unit 602 selects print data 20 lines before the selected line. Note that if the print data selected according to the value of REG_SEG_POS[i] has not yet been stored in the line buffer, the control unit 604, for example, pads a predetermined value indicating non-ejection of ink instead of the print data and outputs it.

[0050] The correction processing unit 602 then outputs the data corresponding to the i-th nozzle in the selected print data as print data corresponding to the i-th nozzle. By performing this process for all i, the correction processing unit 602 can obtain print data (or padded values) corresponding to all i. The correction processing unit 602 then generates and outputs concatenated data that concatenates the print data corresponding to i=0, the print data corresponding to i=1, ..., and all other print data corresponding to i, as corrected print data for the selected line.

[0051] In step S115, the control unit 604 controls the image writing unit 603 to write, in order from the write start address, the corrected print data for the selected line output from the correction processing unit 602. In step S116, the control unit 604 updates the write start address by adding the additional value set in step S103 or step S106 to the write start address.

[0052] In step S117, the control unit 604 determines whether the number of processed lines has reached the number of lines set in step S104 or step S107. If the result of this determination is that the number of processed lines has reached the number of lines set in step S104 or step S107, the process proceeds to step S119. On the other hand, if the number of processed lines has not yet reached the number of lines set in step S104 or step S107, the process proceeds to step S118.

[0053] In step S118, control unit 604 determines whether or not there is print data remaining to be read from image memory 104. If the result of this determination is that there is print data remaining to be read from image memory 104, the process proceeds to step S109. On the other hand, if there is no print data remaining to be read from image memory 104, the process proceeds to step S113.

[0054] Figure 8(b) shows the corrected print data stored in image memory 106 at this point in time if control unit 604 determines in step S101 that high-resolution processing is not being performed. In Figure 8(b), the print data has been corrected to offset the amount of deviation in the sub-scanning direction. As explained in step S113, the padded values ​​are stored in the shaded area.

[0055] 8(d) shows the corrected print data stored in the image memory 106 when the control unit 604 determines in step S101 that high-resolution processing is being performed. Because the print data is processed every other line, there are areas where print data has not yet been stored, and these areas are shown in black.

[0056] In step S119, it is determined whether the number of processes (the processes of steps S108 to S118) set in step S102 or step S105 has been completed. If the number of processes is 1, and the processes of steps S108 to S118 have been executed once, the process according to the flowchart in Fig. 7 ends. If the number of processes is 2, and the processes of steps S108 to S118 have been executed once, the process proceeds to step S108, and if the processes of steps S108 to S118 have been executed twice, the process according to the flowchart in Fig. 7 ends. If the number of processes is N, the process proceeds to step S108 until the processes of steps S108 to S118 have been executed N times, and if the processes of steps S108 to S118 have been executed N times, the process according to the flowchart in Fig. 7 ends. 8(e) shows the corrected print data stored in the image memory 106 after all processing cycles are completed when the control unit 604 determines in step S101 that high-resolution processing is being performed. Even for high-resolution print data, the print data has been corrected to offset the amount of positional deviation in the sub-scanning direction.

[0057] As described above, according to this embodiment, when the ejection position of each nozzle of the print head is misaligned in the sub-scanning direction, correction can be made using a line buffer with the number of lines at normal resolution corresponding to the amount of misalignment in the sub-scanning direction, so correction processing can be performed on print data that is an integer multiple of a predetermined sub-scanning resolution without increasing the memory capacity or circuit scale. As a result, the printing apparatus of this embodiment can print by offsetting the amount of misalignment in the ejection position without increasing the parts cost of the memory.

[0058] (Second embodiment) In the first embodiment, the print data correction unit 109 performs correction processing on high-resolution print data, but the correction accuracy is equivalent to the normal resolution. Therefore, although it takes longer to process, the print data correction unit 109 can also further correct the print data of the corrected lines to achieve correction accuracy equivalent to the processing resolution. Below, we will explain the differences from the first embodiment, and unless otherwise noted below, it is assumed that the second embodiment is the same as the first embodiment.

[0059] The correction process performed by the control unit 604 of the second embodiment and the print data before and after the correction process will be described using Figures 9 and 10. Figure 9 is a flowchart showing the operation of the control unit 604 according to the second embodiment. Figure 10 shows the register REG_SEG_POS and the print data stored in the image memory 106.

[0060] In response to an instruction from CPU 101, print data correction unit 109 starts print data correction processing and performs the processing steps shown in Fig. 9. First, steps S101, S102, and S105 are the same as the processing flow described in Fig. 7, so their description will be omitted.

[0061] In step S201, the control unit 604 of the print data correction unit 109 determines whether to perform high-resolution processing on print data with high resolution in the sub-scanning direction. In the recording device according to this embodiment, when a high-resolution mode, which prints high-resolution print data with improved correction accuracy even at the expense of print speed, is instructed from the operation unit 120 or the like, the CPU 101 instructs the correction processing unit 602 to use high-resolution processing. If, as a result of this determination, the CPU 101 has instructed to perform high-resolution processing on print data with high resolution in the sub-scanning direction, the process proceeds to step S103. If the CPU 101 has not instructed to perform high-resolution processing on print data with high resolution in the sub-scanning direction, the process proceeds to step S106. Note that in this embodiment, when the high-resolution mode has been instructed, the CPU 101 updates the value registered in table REG_SEG_POS to a value converted to high resolution.

[0062] In step S108, the control unit 604 is instructed by the CPU 101 to perform high-resolution processing on high-resolution print data in the sub-scanning direction, and in the case of the second or subsequent iterations of step S108, the read start address is set to the address of the area in which the corrected print data from the previous processing was stored.

[0063] In step S114, the control unit 604 is instructed by the CPU 101 to perform high-resolution processing on print data with high resolution in the sub-scanning direction. Accordingly, in the first iteration of step S114, the control unit 604 halves the value of table REG_SEG_POS, which associates the number of lines corresponding to the amount of misalignment with each nozzle, and then truncates the value to the nearest integer (i.e., shifts the value one bit to the right). This value is then generated as a new "table REG_SEG_POS value" and associated with each nozzle. The control unit 604 then performs a correction process on the print data using the new "table REG_SEG_POS value" in the same manner as in the first embodiment, generating provisional correction data. The table data including the original table REG_SEG_POS value is an example of first data. The new "table REG_SEG_POS value" is an example of the number of lines corresponding to the new amount of misalignment, and the table data including the new "table REG_SEG_POS value" is an example of second data.

[0064] When the control unit 604 is instructed by the CPU 101 to perform high-resolution processing on print data with high resolution in the sub-scanning direction, and when step S114 is performed for the second time, the control unit 604 generates a difference value between the new table REG_SEG_POS value used in the first correction process and the table REG_SEG_POS value as a "table REG_SEG_POS value" and associates it with each nozzle. Based on the "table REG_SEG_POS value" resulting from the difference value, the control unit 604 performs a correction process similar to that of the first embodiment on the provisional correction data corrected in the first correction process. The table data including the "table REG_SEG_POS value" resulting from the difference value is an example of third data.

[0065] FIG. 10(a) shows the print data stored in image memory 104 after the first correction process when it is determined in step S201 that the print data shown in FIG. 8(c) is high-resolution processing. "REG_SEG_POS" in the upper row of FIG. 10(a) is an example of first data. "REG_SEG_POS" in the lower row of FIG. 10(a) is an example of second data. Because the amount of deviation to be corrected is half the resolution of the print data to be processed, the degree of offset of the positional deviation of the ejection position is insufficient. For example, if the amount of deviation is 2 mm, only the number of lines of the corrected print data shown in FIG. 10(a) is corrected corresponding to a deviation of approximately 1 mm.

[0066] Figure 10(b) shows corrected print data that has undergone a second correction process and is stored in image memory 104 using print data for every two lines that are shifted by one line from the provisional correction data, which is the print data for the lines used in the first correction process, and the print data after the first correction process shown in Figure 10(a).

[0067] Generally speaking, in a high-resolution correction process at a resolution N times the normal resolution, the control unit 604 performs the first correction process with 1 / N of the number of lines corresponding to the amount of misalignment stored in the line buffer. Therefore, in the first correction process, the control unit 604 can only perform correction according to approximately 1 / N of the number of lines corresponding to the amount of nozzle misalignment. However, the control unit 604 updates a table that associates the number of lines corresponding to the amount of misalignment with the nozzles, and repeats the correction process N times to generate print data corrected by the number of lines corresponding to the amount of nozzle misalignment. This allows the control unit 604 to correct high-resolution print data to high resolution according to the resolution without increasing the capacity of the line buffer.

[0068] As explained above, according to this embodiment, when the ejection position of each nozzle of the print head is shifted in the sub-scanning direction, a line buffer corresponding to the amount of deviation in the resolution in the specified sub-scanning direction can be used to perform correction processing on print data that is an integer multiple of the specified resolution in the sub-scanning direction relative to the normal resolution, making it possible to offset the amount of deviation in the ejection position with greater precision when printing.

[0069] (Other Examples) The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program.The present invention can also be realized by a circuit (e.g., ASIC) that realizes one or more functions.

[0070] The disclosure of this specification includes the following image processing device, its control method, and program. (Item 1) a storage unit capable of storing print data for the number of lines corresponding to the amount of nozzle positional deviation in a direction perpendicular to the conveyance direction of the recording medium; a correction unit that corrects the print data for each line held by the holding unit based on the amount of nozzle positional deviation in a direction perpendicular to the transport direction; Equipped with The image processing device is characterized in that the correction means executes a process of correcting the print data for every N lines held by the holding means N times, shifting the process by one line at a time. (Item 2) moreover, 2. The image processing device according to item 1, comprising a recording head having a plurality of nozzles arranged in an arrangement direction intersecting the conveyance direction of the recording medium. (Item 3) 3. An image processing device according to item 1 or 2, characterized in that it has a first print mode that prints at a first resolution based on print data, and a second print mode that prints at a second resolution that is N times (N is a natural number greater than or equal to 2) the first resolution based on print data. (Item 4) The correction means In the second resolution printing, generating provisional correction data by correcting the print data based on second data associated with each of the nozzles, the value being half the number of lines corresponding to the amount of misalignment of first data that associates the number of lines corresponding to the amount of misalignment with each of the nozzles, rounded down to the nearest whole number; Item 3. The image processing device according to item 3, wherein the provisional correction data is corrected based on third data that associates the difference between the number of lines corresponding to the amount of positional deviation of the first data and the number of lines corresponding to the amount of positional deviation of the second data with each of the nozzles. (Item 5) storing print data for the number of lines corresponding to the amount of nozzle positional deviation in a direction perpendicular to the conveyance direction of the recording medium in a storage means; the holding means corrects the print data for each line held therein based on the amount of nozzle positional deviation in a direction perpendicular to the transport direction; The method for controlling an image processing apparatus is characterized in that the correction comprises executing a process of correcting print data for every N lines held by the holding means N times, shifting the process by one line at a time. (Item 6) A program that, when read and executed by a computer, causes the computer to execute the method described in item 5.

[0071] The invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

[0072] 100...print control unit, 101...CPU, 104...image memory, 109...print data correction unit, 200...recording head, 201...nozzle

Claims

1. a storage unit capable of storing print data for the number of lines corresponding to the amount of nozzle positional deviation in a direction perpendicular to the conveyance direction of the recording medium; a correction unit that corrects the print data for each line held by the holding unit based on the amount of nozzle positional deviation in a direction perpendicular to the transport direction; Equipped with the correction means executes a process of correcting the print data for every N lines held by the holding means N times, shifting the process by one line at a time; An image processing device characterized by having a first print mode that prints at a first resolution based on print data, and a second print mode that prints at a second resolution that is N times (N is a natural number greater than or equal to 2) the first resolution based on the print data.

2. moreover, 2. The image processing apparatus according to claim 1, further comprising a recording head having a plurality of nozzles arranged in an arrangement direction intersecting the conveyance direction of the recording medium.

3. The correction means In the second resolution printing, generating provisional correction data by correcting the print data based on second data associated with each of the nozzles, the value being half the number of lines corresponding to the amount of misalignment of the first data associating the number of lines corresponding to the amount of misalignment with each of the nozzles, rounded down to the nearest whole number; 2. The image processing device according to claim 1, wherein the provisional correction data is corrected based on third data that associates the difference between the number of lines corresponding to the amount of positional deviation of the first data and the number of lines corresponding to the amount of positional deviation of the second data with each of the nozzles.

4. storing print data for the number of lines corresponding to the amount of nozzle positional deviation in a direction perpendicular to the conveyance direction of the recording medium in a storage means; the holding means corrects the print data for each line held therein based on the amount of nozzle positional deviation in a direction perpendicular to the transport direction; In the correction, a process of correcting the print data for every N lines held by the holding means is executed N times, shifting the data by one line at a time; A control method for an image processing device characterized by having a first print mode that prints at a first resolution based on print data, and a second print mode that prints at a second resolution that is N times (N is a natural number greater than or equal to 2) the first resolution based on the print data.

5. A program that, when read and executed by a computer, causes the computer to execute the method according to claim 4.

Images