JP2011031592A - Image processing device and image processing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve an improvement in printing speed while preventing poor discharge of ink. <P>SOLUTION: The side of a main controller is configured as follows. Gray scale data are extracted from in RGB data of resolution (600 dpi) matched with K so as to take out the gray scale data as K data and to transmit the K data to a sub controller 50. The remaining RGB data are converted into resolution (300 dpi) matched with CMY while the converted RGB data are converted into CMY data by a 3D-LUT. The converted CMY data are binarized by halftone processing so as to generate image data for CMY. The side of the sub controller is configured as follows. The received K data are binarized by halftone processing. If an ink discharge amount Q when discharging K ink by one pass is below a threshold Qref, image data for one pass are generated from the binarized data for one pass. If the ink discharge amount is larger than the threshold Qref, image data of each pass are generated by dividing the binarized data such that printing for one pass is executed by a plurality of passes. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image processing apparatus and an image processing method.

  2. Description of the Related Art Conventionally, serial printers that record by scanning the recording head in the main scanning direction while feeding paper in the sub-scanning direction have been proposed that perform recording for one scan by a plurality of scans (for example, patents). Reference 1).

Japanese Patent Application Laid-Open No. 08-290562

  By the way, in a serial printer, if recording for one scan is performed by one scan in a scene that requires a large amount of ink at one time, the ink supply may not catch up and an ejection failure may occur. As described above, by performing recording for one scan divided into a plurality of scans, ink ejection defects can be prevented, and print quality can be ensured. However, whether or not to divide the recording for one scan into a plurality of scans needs to be determined each time based on the print data for one scan, which increases the processing load. Since a printing apparatus usually uses a processor with a relatively low processing capability, such an increase in processing load adversely affects printing speed.

  The image processing apparatus and the image processing method of the present invention are mainly intended to suppress ink ejection failure and improve printing speed.

  The image processing apparatus and the image processing method of the present invention employ the following means in order to achieve the main object described above.

The image processing apparatus of the present invention
The first nozzle group capable of ejecting the first color ink among the colors forming the color image and the second nozzle group capable of ejecting the second color ink with a larger number of nozzles than the first color ink. An image processing apparatus for generating print data for driving the print head in a printing apparatus that prints by ejecting ink from each nozzle group while scanning the print head formed with
Image data is acquired, first color ink image data and second color ink image data for one scan of the print head are extracted from the acquired image data, and the extracted first color for one scan Print data for the first color ink for one scan is generated from the image data for ink, and the ejection amount of the second color ink for one scan based on the extracted second color ink image data for one scan If the discharge amount of the second color ink for one scan is determined not to exceed the predetermined amount, the extracted second color ink for one scan is determined. When the print data for the second color ink for one scan is generated from the image data and it is determined that the ejection amount of the second color ink for the one scan exceeds the predetermined amount, the second for the one scan. Divide so that printing with ink of different colors is performed by multiple scans Generating a second color ink print data for each scanning operation Te is summarized as.

  In the image processing apparatus according to the present invention, image data is acquired, first color ink image data and second color ink image data for one scan of the print head are extracted from the acquired image data, and extracted 1 Print data for the first color ink for one scan is generated from the image data for the first color ink for the scan, and the second color for one scan is generated based on the extracted second color ink image data for the one scan. When it is determined whether or not the amount of ink discharged exceeds a predetermined amount and it is determined that the amount of ink discharged for the second color for one scan does not exceed the predetermined amount, the extracted second color for one scan When print data for the second color ink for one scan is generated from the image data for ink and it is determined that the ejection amount of the second color ink for one scan exceeds a predetermined amount, the second color for one scan is output. The color ink is divided so that printing is performed by multiple scans. Generating a second color ink print data in each scanning operation. Thereby, even when ink of the second color is ejected by the second nozzle group, it is possible to more reliably prevent the occurrence of ejection failure due to insufficient supply of ink. In addition, when the first color ink is ejected from the first nozzle group, which requires a relatively small amount of ink for one scan, this determination process is omitted, so the processing burden can be reduced. As a result, ink ejection failure can be prevented and the printing speed can be improved. Here, the first nozzle group is a nozzle group capable of discharging CMY color inks as the first color ink, and the second nozzle group is K ink as the second color ink. It is also possible to be a nozzle group capable of discharging the above.

  In such an image processing apparatus of the present invention, the image data is acquired, image data for the first color ink and image data for the second color ink for one scan of the print head are extracted from the acquired image data, The first image data for the second ink that is extracted is transmitted, and the first color ink print data for one scan is generated from the extracted first color ink image data for the one scan. When the second color ink image data for one scan is received from the first processing device, the processing device is connected to the first processing device via a predetermined communication interface so that communication is possible. Based on the received second color ink image data for one scan, it is determined whether or not the ejection amount of the second color ink for one scan exceeds the predetermined amount. The discharge amount of the color ink is If it is determined that the predetermined amount is not exceeded, the second color ink print data for one scan is generated from the extracted second color ink image data for one scan, and the second color for the first scan is generated. If it is determined that the amount of ink discharged exceeds the predetermined amount, printing for the second color ink for each scan is performed by dividing the print with the second color ink for one scan by a plurality of scans. It is also possible to include a second processing device that generates print data. In this way, it is possible to improve the printing speed by efficiently using the two processing devices. In this aspect of the image processing apparatus of the present invention, the first processing apparatus compresses the extracted second color ink image data by using a predetermined compression process and the compressed image after the compression. The data may be transmitted to the second processing device, and the second processing device may decompress the received compressed image and generate print data using the image data obtained by the decompression. In this way, the amount of data required for transfer to the second processing device can be reduced, so that it is possible to prevent the overall processing speed from being reduced by the data transfer processing. In this case, the predetermined compression process may be a reversible compression process.

The image processing method of the present invention includes:
The first nozzle group capable of ejecting the first color ink among the colors forming the color image and the second nozzle group capable of ejecting the second color ink with a larger number of nozzles than the first color ink. An image processing method for generating print data for driving the print head in a printing apparatus that prints by ejecting ink from each nozzle group while scanning the print head formed with
Image data is acquired, first color ink image data and second color ink image data for one scan of the print head are extracted from the acquired image data, and the extracted first color for one scan Print data for the first color ink for one scan is generated from the image data for ink, and the ejection amount of the second color ink for one scan based on the extracted second color ink image data for one scan If the discharge amount of the second color ink for one scan is determined not to exceed the predetermined amount, the extracted second color ink for one scan is determined. When the print data for the second color ink for one scan is generated from the image data and it is determined that the ejection amount of the second color ink for the one scan exceeds the predetermined amount, the second for the one scan. Divide so that printing with ink of different colors is performed by multiple scans Generating a second color ink print data for each scanning operation Te is summarized as.

  According to the image processing method of the present invention, image data is acquired, and image data for first color ink and image data for second color ink for one scan of the print head are extracted from the acquired image data, and extracted. The first color ink print data for one scan is generated from the first color ink image data for one scan, and the second color for one scan is generated based on the extracted second color ink image data for one scan. If it is determined whether or not the discharge amount of the second color ink exceeds a predetermined amount and it is determined that the discharge amount of the second color ink for one scan does not exceed the predetermined amount, the extracted first scan for the first color is determined. If print data for the second color ink for one scan is generated from the image data for two color inks and it is determined that the ejection amount of the second color ink for one scan exceeds a predetermined amount, the first data for one scan So that printing with two colors of ink is performed by multiple scans. And generating a second color ink print data for each scanning operation by. Thereby, even when ink of the second color is ejected by the second nozzle group, it is possible to more reliably prevent the occurrence of ejection failure due to insufficient supply of ink. In addition, when the first color ink is ejected from the first nozzle group, which requires a relatively small amount of ink for one scan, this determination process is omitted, so the processing burden can be reduced. As a result, ink ejection failure can be prevented and the printing speed can be improved. As a result, ink ejection failure can be prevented and the printing speed can be improved.

1 is a configuration diagram illustrating an outline of the configuration of an inkjet printer. FIG. 2 is a configuration diagram showing an outline of the configuration of a print head 25. 4 is an explanatory diagram showing an electrical connection relationship between the ASICs 43 and 53 and the print head 25. FIG. The functional block diagram of ASIC43,53. Explanatory drawing which shows the sequence of a printing process.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing the schematic configuration of an inkjet printer 10 equipped with the image processing apparatus of the present invention, FIG. 2 is a schematic diagram showing the schematic configuration of a print head 25, and FIG. 3 shows ASICs 43 and 53. 4 is an explanatory diagram showing an electrical connection relationship with the print head 25. FIG. As shown in FIG. 1, the inkjet printer 10 of the present embodiment communicates with a printer mechanism 20 that prints an image on a recording sheet S, a main controller 40 that executes various processes, and the main controller 40 via a USB cable 14. And a sub-controller 50 that is connected so as to execute various processes. Here, the main controller 40 and the sub-controller 50 correspond to the image processing apparatus.

  The printer mechanism 20 is driven by a belt 21 looped in the left-right direction and reciprocates in the left-right direction (main scanning direction) along the guide 22, and is mounted on the carriage 23 and mounted on cyan (C), Magenta (M), yellow (Y), and black (K) (hereinafter referred to as C, M, Y, and K as appropriate) ink cartridges 24 that individually store ink of each color, and supplied from each ink cartridge 24 A printing head 25 that applies pressure to each ink and discharges the ink toward the recording paper S, and a transport roller 26 that feeds the recording paper S supplied from the back side to the near side are provided. As shown in FIG. 2, the print head 25 includes a nozzle group in which nozzles 32C, 32M, and 32Y that can individually eject inks of CMY colors are arranged along the conveyance direction (sub-scanning direction) of the recording paper S. 30C, 30M, and 30Y, and nozzle groups 30K1 and 30K2 in which nozzles 32K that can eject black (K) ink are arranged along the sub-scanning direction are formed. Here, the configuration of each nozzle group will be described using the cyan (C) nozzle group 30C as an example. The nozzle group 30C includes two nozzle rows C1 and C2, and the nozzles 32C are arranged such that each nozzle row C1 and C2 has a predetermined length L in pitch. The nozzles 32C of the nozzle row C1 and the nozzles 32C of the nozzle row C2 are arranged in a zigzag pattern along the sub-scanning direction, and the pitch is a length L / 2 that is half the predetermined length L. ing. In this embodiment, the predetermined length L is set so that the dot has a resolution of 150 dpi, and the dots formed by the nozzle row C1 and the dots formed by the nozzle row C2 are alternately arranged in a line in the sub-scanning direction. By performing printing in this way, the resolution of cyan (C) dots is 300 dpi. Since the magenta (M) nozzle group 30M and the yellow (Y) nozzle group 30Y are similarly configured, the resolution obtained is 300 dpi. Similarly, the black (K) nozzle groups 30K1 and 30K2 include two nozzle rows K11 and K12 and two nozzle rows K21 and K22, respectively. Further, the nozzles 32K of the nozzle group 30K1 and the nozzles 32K of the nozzle group 30K2 are arranged so that the pitch in the sub-scanning direction is a length L / 4 that is half the length L / 2. Therefore, by performing printing so that the dots formed by the nozzle group 30K1 and the dots formed by the nozzle group 30K2 are alternately arranged in a line in the sub-scanning direction, the resolution of the black (K) dots is 600 dpi. Become. Thus, the print head 25 includes a total of 10 nozzle rows, and is configured such that the resolution of CMY dots is 300 dpi and the resolution of K dots is 600 dpi. That is, the nozzle density of K is higher than that of CMY. Further, the print head 25 forms a dot on the recording paper S by applying a voltage to the piezoelectric element individually provided in each nozzle and deforming it, and ejecting the pressurized ink thereby. In FIG. 3, the piezoelectric elements respectively provided in the nozzles 32C of the nozzle row C1 are collectively shown as a piezoelectric element 38C1, and the print head 25 includes a drive circuit 36C1 as a circuit for applying a voltage to the piezoelectric element 38C1. Similarly, the piezoelectric elements of the nozzle arrays C2 to K22 are collectively referred to as piezoelectric elements 38C2 to 38K22, and drive circuits 36C2 to 36K22 are provided as circuits for applying voltages to the piezoelectric elements 38C2 to 38K22. Since the print head 25 includes a total of 10 nozzle rows, the print head 25 includes a total of 10 drive circuits 36C1 to 36K22.

  As shown in FIG. 1, the main controller 40 includes an SOC (System On a Chip) 40a on which a CPU 41 and the like are mounted, a ROM 46 storing various data and various tables, an SDRAM 45 capable of reading and writing data, a photograph And a card interface (I / F) 47 used for connection to a memory card MC storing image data such as. In addition to the CPU 41, the SOC 40 a includes a USB interface (I / F) 42 that exchanges information with the sub-controller 50, an ASIC 43 that executes various processes related to print processing and controls the printer mechanism 20, and SDRAM 45 An SRAM (not shown) that can be accessed at high speed is mounted, and these are connected via the bus 48 so that various control signals and data can be exchanged with each other. The bus 48 also functions as an external bus that connects the SOC 40a, the ROM 46, the SDRAM 45, and the card I / F 47. Further, as shown in FIG. 3, the ASIC 43 includes six transmission cables 44 (44a) for each of the six drive circuits 36C1 to 36Y2 for driving the CMY nozzle groups 30C, 30M, and 30Y of the print head 25. To 44f) and transmits a drive signal to each of the drive circuits 36C1 to 36Y2. Therefore, the main controller 40 can drive the CMY nozzle groups 30C, 30M, and 30Y among the nozzle groups 30C, 30M, 30Y, 30K1, and 30K2 of the print head 25. Further, the main controller 40 inputs various operation signals from the printer mechanism 20, inputs various control signals transmitted from the sub-controller 50 via the USB I / F 42, and a memory card via the card I / F 47. Input image data saved in the MC. Also, image data and various control signals are output to the sub-controller 50 via the USB I / F 42. Image data input from the memory card MC via the card I / F 47 is stored in the SDRAM 45 as RGB data of 600 dpi in accordance with the K dot resolution of the print head 25. When the input image data is other than RGB data, the CPU 41 converts the color data into RGB data and stores it. When the resolution is other than 600 dpi, pixels are generated by interpolation between adjacent pixels or at a predetermined ratio. Thin out pixels. Note that each value of RGB data is represented by 256 gradations (8 bits) of values 0 to 255 according to the shading.

  As shown in FIG. 1, the sub controller 50 includes an SOC 50a on which a CPU 51 and the like are mounted, a ROM 56 that stores various data and various tables, and an SDRAM 55 that can read and write data. Like the main controller 50, the SOC 50 a is faster than the CPU 51, the USB interface (I / F) 52, the ASIC 53 that executes various processes related to the printing process and controls the printer mechanism 20, and the SDRAM 55. An accessible SRAM (not shown) or the like is mounted, and these are connected via a bus 58 so that various control signals and data can be exchanged with each other. The sub controller 50 inputs image data and various control signals transmitted from the main controller 40 via the USB I / F 52, and outputs various control signals to the main controller 40 via the USB I / F 52. The input image data is stored in the SDRAM 55. Further, as shown in FIG. 3, the ASIC 53 includes four transmission cables 54 (54a to 54d) in each of the four drive circuits 36K11 to 36K22 for driving the K nozzle groups 30K1 and 30K2 of the print head 25. ), And a drive signal is transmitted to each of the drive circuits 36K11 to 36K22. Therefore, the sub-controller 50 can drive the K nozzle groups 30K1, 30K2 among the nozzle groups 30C, 30M, 30Y, 30K1, 30K2 of the print head 25.

  Here, each function regarding the printing process which the ASIC 43 of the main controller 40 and the ASIC 53 of the sub controller 50 have will be described. FIG. 4 is a functional block diagram of the ASICs 43 and 53. As shown in FIG. 4A, the ASIC 43 includes an image input unit 43a, a grayscale data extraction unit 43b, a compression processing unit 43c, a resolution conversion processing unit 43d, a color conversion processing unit 43e, and a halftone process. 43f, a microweave processing unit 43g, and a drive signal transmission unit 43h. The image input unit 43a inputs the RGB data stored in the SDRAM 45 by an amount necessary for processing, for example, an amount necessary for generating print data for one pass of the print head 25. The grayscale data extraction processing unit 43b is a processing unit for extracting grayscale data from input RGB data. Specifically, the RGB gradation values are the same value (R = G = B). Pixels are extracted and extracted as K data. The compression processing unit 43c performs a compression process on the K data extracted by the grayscale data extraction processing unit 43b. The compression process is performed by a reversible compression method, and in this embodiment, run-length compression is used to encode and compress the continuous length of the same data. Here, since the K ink is used only for printing of a relatively dark color, the occurrence probability of K data in color printing is often lower than the occurrence probability of other CMY data. For this reason, when K-length data is extracted from CMYK data and run-length compression is performed, blank portions without K-data often continue, so that the compression process can be performed smoothly and the compression efficiency can be increased. The resolution conversion processing unit 43d thins out the pixels at a predetermined rate, calculates the average value of the gradation values of adjacent pixels, and replaces them with one pixel, or generates a new pixel by interpolation between adjacent pixels. To convert the resolution. The color conversion processing unit 43e performs color conversion processing for converting the input RGB data into CMY data with reference to a three-dimensional color conversion lookup table (3D-LUT) stored in the SDRAM 45. It should be noted that each value of the CMY data subjected to the color conversion processing is represented by 256 gradations (8 bits) of values 0 to 255 according to the shading. The halftone processing unit 43f performs halftone processing for converting each 8-bit CMYK data into 2-bit binary data. Halftone processing is performed using a dither method or an error diffusion method. The dither method binarizes dots on / off by comparing the threshold value given by a preset dither matrix and the gradation value of each pixel. Further, the error diffusion method compares the gradation value of the pixel of interest with a predetermined threshold value, binarizes the dot on / off, and makes a difference between the binarized gradation value and the original gradation value. Is diffused at a certain rate to unprocessed pixels around the pixel of interest. As described above, in the halftone process, a process is required for each pixel of the CMYK data regardless of which process is used. The microweave processing unit 43g rearranges the halftoned binarized data in the order in which the print head 25 forms dots to generate image data for one pass. At this time, if the nozzle pitch is wider than the interval corresponding to the printing resolution, so-called microweave processing is performed in which the dot lines formed in the previous pass are filled with the dot lines formed in the next pass. The dot formation order is determined. The drive signal transmission unit 43h generates a pulse of a voltage applied to the piezoelectric elements 38C1 to 38K22 of the print head 25 from the image data for one pass as a drive signal, and transmits it to the drive circuits 36C1 to 36K22. Each of these processing units stores the processed data in a data buffer (not shown) of the SDRAM 45 or reads the data to be processed from the data buffer of the SDRAM 45 for processing. Although not shown, the ASIC 43 controls the motor that reciprocates the carriage 23 of the printer mechanism 20 and the motor that drives the transport roller 26.

  On the other hand, as shown in FIG. 4B, the ASIC 53 includes an image input unit 53a for inputting image data stored in the SDRAM 55, and a decompression processing unit 53c for decompressing image data compressed by run-length compression. A color conversion processing unit 53e that converts the decompressed K data into K data suitable for printing with reference to a one-dimensional color conversion lookup table (1D-LUT), a halftone processing unit 53f, and a microweave A processing unit 53g and a drive signal transmission unit 53h are provided. It is assumed that each value of the K data subjected to the color conversion processing by the color conversion processing unit 53e is represented by 256 gradations (8 bits) of values 0 to 255 according to the shading. Each of these processing units performs processing using a data buffer (not shown) of the SDRAM 55, similarly to each processing unit of the ASIC 43. As described above, since the ASICs 43 and 53 execute the respective processes using the respective data buffers of the SDRAMs 45 and 55, the main controller 40 and the sub controller 50 can execute the processes independently of each other.

  Here, the microweave processing unit 53g of the ASIC 53 rearranges the halftone-processed binarized data in the order in which the print head 25 forms dots in the same manner as the microweave processing unit 43g of the ASIC 43, and thus for one pass. Although image data is generated, K has a larger number of nozzles than other CMY, and it may be necessary to eject a large amount of ink at a time. Therefore, in some cases, K ink is supplied during one-pass printing. There is a risk of running out of ink. In this embodiment, based on K data for one pass after halftone processing by the halftone processing unit 53f, the K ink ejection amount Q is estimated when printing is attempted in one pass, and the estimated ink ejection is determined. The amount Q is compared with the threshold value Qref, and when the ink ejection amount Q is less than or equal to the threshold value Qref, it is determined that there is no possibility of causing the above-mentioned ink outage, and image data for one pass is generated from K data for one pass. When the ink discharge amount Q is larger than the threshold value Qref, it is determined that there is a possibility that ink will run out, and the K data for one pass is divided into a plurality of passes so that printing of the K data for one pass is performed by a plurality of passes. The image data of each pass is generated by dividing. Note that the microweave processing unit 43g of the ASIC 43 does not need to eject a large amount of ink in one pass and does not cause the above-described problem of running out of ink. Therefore, such image data division is not performed.

  Next, the operation of the ink jet printer 10 according to the present embodiment configured as described above, particularly the operation when printing processing is performed based on each 8-bit RGB data having a resolution of 600 dpi stored in the SDRAM 45 will be described. FIG. 5 is an explanatory diagram showing a sequence when the printing process is executed by the main controller 40 and the sub-controller 50. In this sequence, the main controller 40 performs processing using the above-described processing functions of the CPU 41 and ASIC 43 as appropriate, and the same applies to the sub-controller 50. In the figure, the numerical value in parentheses indicates the number of bits of image data. First, the main controller 40 inputs RGB data necessary for printing processing for one pass among the RGB data stored in the SDRAM 45 (step S100). Next, by extracting gray scale data having the same gradation value (R = G = B) from the input 8-bit RGB data, for example, the value of R is set and K data is extracted (step S110). The extracted K data is compressed (step S120) and transmitted to the sub-controller 50 (step S130). As described above, since the K data can be efficiently compressed by the run length compression, the data transmission time can be shortened by performing the compression process smoothly. Moreover, since run length compression is reversible compression, it can prevent that image quality is impaired. Subsequently, a resolution conversion process for converting the remaining RGB data after extracting the K data from the RGB data from 600 dpi to 300 dpi is executed (step S140), and the RGB data after the resolution conversion is converted into each data using a 3D-LUT. A color conversion process for converting the color into 8-bit CMY data is executed (step S150). Here, the color conversion process is a relatively heavy process because the 3D-LUT is used. In this embodiment, the K data is extracted at a necessary 600 dpi resolution, and the remaining RGB data is resolved from 600 dpi to 300 dpi. By applying to the RGB data after the resolution conversion after the conversion, the processing load can be greatly reduced. When color conversion processing is performed in this way, halftone processing is performed to convert each 8-bit CMY data into 2-bit binary data (step S160), and image data for one pass of CMY is generated ( Step S170) Waits for reception of a processing completion signal transmitted from the sub-controller 50 (step S180).

  On the other hand, the sub-controller 50 waits for the completion of reception of the K data transmitted from the main controller 40 (step S200), and executes the decompression process of the received K data (step S210). When the decompression process is executed, a color conversion process for converting the decompressed K data into K data suitable for printing with reference to the 1D-LUT is executed (step S220), and the 8-bit K data is converted into 2-bit 2 A halftone process for converting to the digitized data is executed (step S230). Since the transmitted K data is 600 dpi in accordance with the K resolution, the sub-controller 50 does not perform resolution conversion processing. The color conversion process performs color conversion of 600 dpi K data, which is a higher resolution than the above-described CMY data, but the lookup table used is a 1D-LUT, and therefore the processing load is excessive. There is no. Based on the binarized data after the halftone process, the ink discharge amount Q when K ink is discharged in one pass is estimated (step S240), and the estimated ink discharge amount Q is compared with the threshold value Qref (step S240). Step S250). When the ink discharge amount Q is less than or equal to the threshold value Qref, image data for one pass is generated from the binarized data for one pass after the halftone process (step S260). When the ink discharge amount Q is larger than the threshold value Qref, the threshold value is generated. The binarized data for one pass after halftone processing is divided into a plurality of passes so as to be equal to or lower than Qref, and image data of each pass is generated (step S270). For example, when printing K data for one pass is performed in two passes, this process is 1 in the first half of the K ink nozzle rows K11 to K22 (the upper half of the nozzle rows K11 to K22 in FIG. 2). The printing of the second pass is performed, and image data is generated by dividing the second half of the nozzle rows K11 to K22 (the lower half of the nozzle rows K11 to K22 in FIG. 2) so that the second pass is printed. It is. As a result, the supply of K ink cannot catch up due to a large amount of K ink being used in one pass, and it is possible to prevent the ink from running out temporarily. When the image data is generated in this way, a process completion signal is transmitted to the main controller 40 (step S280), and a reception of a drive signal transmission instruction transmitted from the main controller 40 is awaited (step S285). In this embodiment, the processing can be distributed by processing the K data by the sub-controller 50. As described above, since the main controller 40 and the sub-controller 50 can perform processing independently, parallel processing of distributed processing is possible. In particular, since the color conversion processing using the 3D-LUT by the color conversion processing unit 43b of the ASIC 43 and the image data division generation processing by the microweave processing unit 53g of the ASIC 53 have a relatively large processing load, the respective processings are different from each other. The processing efficiency can be improved by performing the parallel processing by distributing the processes. In order to distribute the processing, compression processing and transmission processing of K data are required. As described above, the data transmission time can be shortened by smooth compression processing, and processing for each pixel can be performed. Therefore, the time required for each process does not become a significant problem.

  The main controller 40 that has received the processing completion signal in step S180 transmits a drive signal transmission instruction to the sub-controller 50 (step S185), and sends the drive signals for the nozzles 32C, 32M, and 32Y for one pass to the print head 25. Transmit (step S190). Specifically, the drive signals generated from the CMY data for one pass are transmitted to the drive circuits 36C1 to 36Y2 of the print head 25 via the transmission cables 44a to 44f, respectively. On the other hand, the sub-controller 50 that has received the drive signal transmission instruction in step S285 transmits a drive signal for the nozzles 32K for one pass to the print head 25 (step S290). Specifically, the drive signals generated from the K data for one pass are transmitted to the drive circuits 36K11 to 36K22 of the print head 25 via the cables 54a to 54d, respectively. When image data is generated by dividing the K data for one pass into a plurality of passes in step S270, that is, when there is a next pass (step S295), the process returns to step S290 to drive the nozzle 32K for the next pass. A signal is transmitted to the print head 25. When the CMYK data for one pass is thus transmitted to the print head 25, the main controller 40 controls each motor and executes the printing process for one pass (step S195). At this time, when the K data for one pass is divided and K data is transmitted a plurality of times, the main controller 40 performs the first pass printing based on the first pass K data and the CMY data, When the second pass K data is transmitted without the CMY data, the print head 25 is driven in the main scanning direction without feeding the paper to perform the second pass printing based only on the K data. These processes are repeated until there is no more data in the next pass.

  Here, the correspondence between the components of the present embodiment and the components of the present invention will be clarified. The main controller 40 of the present embodiment corresponds to a “first processing apparatus”, the sub-controller 50 corresponds to a “second processing apparatus”, and the print head 25 corresponds to a “print head”.

  According to the inkjet printer 10 of the present embodiment described in detail above, the main controller 40 and the sub controller 50 are connected via the USB interfaces 42 and 52, and the main controller 50 side has a resolution (600 dpi) according to K. ) By extracting grayscale data from the RGB data and sending it to the sub-controller 50 as the K data, converting the remaining RGB data to a resolution (300 dpi) that matches CMY, and RGB data after the resolution conversion. Is converted into CMY data by referring to the 3D-LUT, and the converted CMY data is binarized by halftone processing to generate CMY image data. The sub-controller 50 side, in parallel with the main controller 50, Receive The K data is binarized by halftone processing, the ink ejection amount Q when K ink is to be ejected in one pass is estimated based on the binarized data, and when the ink ejection amount Q is less than or equal to the threshold value Qref Image data for one pass is generated from binarized data for one pass, and when the ink ejection amount Q is larger than the threshold value Qref, the binary data for one pass is divided into a plurality of passes so that it is less than or equal to the threshold value Qref. Since the image data for each pass is generated and the K data for one pass is printed by a plurality of passes, unnecessary processing is omitted for CMY data with a small amount of ink ejected at a time to reduce the processing load. For K data that can be discharged at a time, the supply of K ink catches up because a large amount of K ink is discharged in one pass. It is possible to prevent the cause out of ink disappears. As a result, ink ejection failure can be prevented and the printing speed can be further improved. Moreover, since such processing is performed by combining the main controller 40 and the sub-controller 50, the printing speed can be further improved by distributed processing. In particular, the color conversion processing using the 3D-LUT by the color conversion processing unit 43b of the ASIC 43 and the image data division generation processing by the microweave processing unit 53g of the ASIC 53 have a relatively large processing load. The processing efficiency can be improved by performing the parallel processing by distributing the processes. Also, because K data is efficiently compressed and transmitted by run-length compression, which is a lossless compression method, the data transmission time can be shortened without losing image quality, and the overall processing speed is reduced by the communication time. Can be suppressed.

  In addition, this invention is not limited to the embodiment mentioned above at all, and it cannot be overemphasized that it can implement with a various aspect, as long as it belongs to the technical scope of this invention.

  In the embodiment described above, when printing for one pass is performed by two passes, the first pass and the second pass are performed separately for the first half and the second half of the K nozzle rows K11 to K22, respectively. However, the present invention is not limited to this. For example, the nozzle rows K11 to K22 may be divided into nozzle rows (nozzle rows K11 and K12 and nozzle rows K21 and K22).

  In the embodiment described above, the nozzle groups 30C, 30M, 30Y, 30K1, and 30K2 are configured to include two nozzle rows each. However, the present invention is not limited to this, and each nozzle group may be one row or three or more rows. It may be provided.

  In the above-described embodiment, the K data is compressed by the run length compression. However, the present invention is not limited to this, and the compression may be performed by another lossless compression method such as Huffman coding. Further, the present invention is not limited to the lossless compression method, and an irreversible compression method may be used. Further, such compression processing may not be performed, and the extracted K data may be transmitted as it is. However, in order to shorten the data transmission time, it is preferable to perform compression processing as in this embodiment.

  In the embodiment described above, the image data stored in the memory card MC is input. However, the present invention is not limited to this, and image data transmitted from a personal computer or the like may be input. Further, CMYK data may be transmitted as image data transmitted from a personal computer or the like. In this case, the color conversion process in step S140 or step S220 may be omitted.

  In the embodiment described above, the ink colors are four colors of cyan (C), magenta (M), yellow (Y), and black (K). However, the present invention is not limited to this, and light cyan (LC) or light magenta (LM). 5 colors, 6 colors, or a plurality of more colors.

  In the embodiment described above, each controller is provided with a USB interface. However, the present invention is not limited to this, and may be provided with an interface of another standard such as an IEEE1394 interface.

  In the embodiment described above, the main controller 40 and the sub-controller 50 are combined to generate a drive signal necessary for driving the print head 25. However, the present invention is not limited to this, and a single controller is used. It does n’t matter.

  In the above-described embodiment, the image processing apparatus is connected to the print head 25 of the ink jet printer 20, but is not limited thereto, and may be connected to a print head capable of ejecting ink such as a facsimile apparatus. .

  10 inkjet printer, 14 USB cable, 20 printer mechanism, 21 belt, 22 guide, 23 carriage, 24 ink cartridge, 25 print head, 26 transport roller, 30C, 30M, 30Y, 30K1, 30K2 nozzle group, 32C, 32M, 32Y , 32K nozzle, 36C1, 36C2, 36M1, 36M2, 36Y1, 36Y2, 36K11, 36K12, 36K21, 36K22 drive circuit, 38C1, 38C2, 38M1, 38M2, 38Y1, 38Y2, 38K11, 38K12, 38K21, 38K22 piezoelectric element, 40 mains Controller, 40a, 50a SOC, 41, 51 CPU, 42, 52 USB interface (I / F), 43, 53 ASIC, 43a, 53a Image input , 43b gray scale data extraction processing unit, 43c compression processing unit, 53c decompression processing unit, 43d resolution conversion processing unit, 43e, 53e color conversion processing unit, 43f, 53f halftone processing unit, 43g, 53g microweave processing unit, 43h, 53h Drive signal transmitter, 44 (44a to 44f), 54 (54a to 54d) Transmission cable, 45, 55 SDRAM, 46, 56 ROM, 47 Card interface (I / F), 48, 58 bus, 50 sub Controller, 53C thawing processing unit, C1, C2, M1, M2, Y1, Y2, K11, K12, K21, K22 nozzle row, MC memory card, S recording paper.

Claims (6)

The first nozzle group capable of ejecting the first color ink among the colors forming the color image and the second nozzle group capable of ejecting the second color ink with a larger number of nozzles than the first color ink. An image processing apparatus for generating print data for driving the print head in a printing apparatus that prints by ejecting ink from each nozzle group while scanning the print head formed with
Image data is acquired, first color ink image data and second color ink image data for one scan of the print head are extracted from the acquired image data, and the extracted first color for one scan Print data for the first color ink for one scan is generated from the image data for ink, and the ejection amount of the second color ink for one scan based on the extracted second color ink image data for one scan If the discharge amount of the second color ink for one scan is determined not to exceed the predetermined amount, the extracted second color ink for one scan is determined. When the print data for the second color ink for one scan is generated from the image data and it is determined that the ejection amount of the second color ink for the one scan exceeds the predetermined amount, the second for the one scan. Divide so that printing with ink of different colors is performed by multiple scans Generating a second color ink print data for each scanning operation Te image processing apparatus according to claim. The image processing apparatus according to claim 1,
The image data is acquired, image data for the first color ink and image data for the second color ink for one scan of the print head are extracted from the acquired image data, and the extracted second data for one scan is extracted. A first processing device for transmitting image data for ink and generating print data for first color ink for one scan from the extracted first color ink image data for one scan;
When the image data for the second color ink for one scan is received from the first processing device, the first processing device is connected so as to be able to communicate with the first processing device via a predetermined communication interface. On the basis of the image data for the second color ink for one minute, it is determined whether or not the ejection amount of the second color ink for one scan exceeds the predetermined amount. When it is determined that the ejection amount does not exceed the predetermined amount, the second color ink print data for one scan is generated from the extracted second color ink image data for one scan, and the one scan worth When it is determined that the ejection amount of the second color ink exceeds the predetermined amount, printing is performed so that printing with the second color ink for one scan is performed by a plurality of scans. Second processing device for generating print data for second color ink Image processing apparatus comprising a. The image processing apparatus according to claim 2,
The first processing device compresses the extracted second color ink image data using a predetermined compression process and transmits the compressed image after the compression to the second processing device,
The second processing apparatus decompresses the received compressed image and generates print data using image data obtained by the decompression.   The image processing apparatus according to claim 3, wherein the predetermined compression process is a lossless compression process. The image processing apparatus according to any one of claims 1 to 4,
The first nozzle group is a nozzle group capable of discharging CMY color inks as the first color ink,
The image processing apparatus, wherein the second nozzle group is a nozzle group capable of ejecting K ink as the second color ink. The first nozzle group capable of ejecting the first color ink among the colors forming the color image and the second nozzle group capable of ejecting the second color ink with a larger number of nozzles than the first color ink. An image processing method for generating print data for driving the print head in a printing apparatus that prints by ejecting ink from each nozzle group while scanning the print head formed with
Image data is acquired, first color ink image data and second color ink image data for one scan of the print head are extracted from the acquired image data, and the extracted first color for one scan Print data for the first color ink for one scan is generated from the image data for ink, and the ejection amount of the second color ink for one scan based on the extracted second color ink image data for one scan If the discharge amount of the second color ink for one scan is determined not to exceed the predetermined amount, the extracted second color ink for one scan is determined. When the print data for the second color ink for one scan is generated from the image data and it is determined that the ejection amount of the second color ink for the one scan exceeds the predetermined amount, the second for the one scan. Divide so that printing with ink of different colors is performed by multiple scans Image processing method characterized by generating a second color ink print data for each scanning operation Te.

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