JP5863177B2 - Inkjet recording device - Google Patents

Description

  The present invention relates to an ink jet recording apparatus such as a printer, a copying machine, a multifunction machine, a facsimile machine or the like. In particular, the present invention relates to an ink jet recording apparatus having a line head.

  The ink jet recording apparatus has a recording head. The recording head includes a plurality of nozzles that eject ink. In the past, the nozzles of the recording head were provided in a straight line. However, as the resolution (dot density per unit area) increases, it becomes difficult to arrange the nozzles in a straight line. Therefore, a head in which nozzle installation positions are distributed (nozzles are provided in a staggered manner) may be used. However, since the position of the nozzle is shifted from a straight line, it is necessary to adjust the timing for ejecting the ink in accordance with the installation position of the nozzle (in accordance with the shift amount).

  A printer that corrects dot timing (print data) sent to a recording head and corrects print timing in accordance with displacement of the nozzle installation position is described in Patent Document 1. Specifically, Patent Document 1 discloses a printer that forms an image composed of a matrix-like dot pattern, and nozzles individually corresponding to each line along the printing direction of the dot pattern are arranged along the printing direction. For each of the heads arranged in a dispersed manner and each of the lines, a dot data constituting a dot pattern is raster data divided into a certain number of dots, and a data storage unit that stores a column address number for each raster data, and A correction value storage unit that stores a correction value corresponding to the nozzle position in the printing direction for each line, and a data storage unit for each line, depending on the arrangement position of the nozzle corresponding to the line in the printing direction. A column address selector for reading raster data from two consecutive column address numbers selected, A register that stores the raster data read by the system address selection unit in the order of two column address numbers, and among the raster data stored in the register, a certain number of dots in a continuous portion corresponding to the correction value of the corresponding line A dot data selection section that selectively reads out dot data, and dot data for a fixed number of dots read out by the dot data selection section is accumulated for each line, and the number of common dots from the beginning of the accumulated dot data for each line There is described a printer including a raster column converter that sequentially sends a data sequence composed of dot data of each line to a head at a common print timing for each data sequence. Accordingly, the print data is efficiently read by matching the nozzle position and the print timing (see Patent Document 1: Claim 1, paragraph [0005], etc.).

Japanese Patent No. 4032279

  In the ink jet recording apparatus, based on image data to be printed on paper, first, dot data that determines whether or not ink is ejected (whether ink is ejected) is generated for each pixel (each dot). As described above, in an ink jet recording apparatus having a head in which nozzle installation positions are distributed in the paper conveyance direction, it is necessary to adjust the generated dot data in accordance with the amount of deviation. In other words, it is necessary to adjust the dot data so that ink is ejected faster or later by the amount that is deviated from the reference.

  For example, when ink is ejected simultaneously from all nozzles, a straight line is not printed due to a shift in the nozzle installation position. For example, when printing a straight line parallel to the line direction on the paper, the ink ejection timing is adjusted according to the nozzle installation position (shift amount in the paper transport direction) so that the straight line is printed. Adjust the dot data to shift. A straight line parallel to the line direction can be printed on the paper by transferring the adjusted dot data to the head and adjusting the timing of ink ejection from each nozzle.

  Here, for dot data adjustment (shift of each pixel), redundant data including unnecessary data (data not used) is read, and data with the same content (dot data before adjustment) is read multiple times. If wasteful read processing such as this is performed, dot data adjustment (shifting of each pixel) and transfer of adjusted dot data to the head unit cannot be performed efficiently, and processing cannot be performed at high speed. is there.

  Here, looking at the invention of Patent Document 1, the printer described in Patent Document 1 reads out 16-bit dots for adjustment according to the installation position of the nozzles, and selects and uses 8 bits among them. Therefore, in the printer described in Patent Document 1, extra data is read (redundant data is read) for dot data adjustment, and image data adjustment is not efficient (Patent Document 1: Paragraphs [0024], [0025] etc.). In addition, column address selection and calculation (division and addition) and calculation using correction values are necessary (see Patent Document 1: Paragraphs [0026], [0035], etc.), and processing that cannot be said to be simple at all is performed. There is also a problem.

  In view of the above problems, the present invention first adjusts dot data in accordance with the nozzle installation position (shift in the paper conveyance direction) to eliminate unnecessary data reading, and does not include unnecessary data. It is an object to increase the processing speed by transferring the bind data to the head unit.

  In order to solve the above-described problem, an ink jet recording apparatus according to claim 1 ejects ink at a predetermined timing, and at least one dot is provided for each dot in the line direction, and the position in the paper transport direction is shifted. A head unit including a plurality of nozzles, a halftone processing unit that converts image data into dot data indicating the presence or absence of dot formation for each pixel in one page, and dot data generated by the halftone processing unit An extraction processing unit that generates binding data including information indicating the operation of each nozzle in units of one ink ejection drive, and the extraction processing unit. A bind memory for storing the bind data output by the unit, and the bind data stored in the bind memory. The anda transfer unit for transferring toward the head portion, each said nozzle of said head portion was be performed based on said binding data, the ejection driving of the ink.

  According to this configuration, the dot data generated by the halftone processing unit is shifted according to the displacement of the nozzle position in the paper transport direction, and includes information indicating the operation of each nozzle in units of ink ejection drive. An extraction processing unit that generates bind data; a bind memory that stores bind data output by the extraction processing unit; and a transfer unit that transfers the bind data accumulated in the bind memory toward the head unit. Each nozzle of the unit performs ink ejection drive based on the bind data. In this way, first, the position adjustment (line shift) of each pixel in the image data in accordance with the nozzle installation position (shift in the paper conveyance direction) is performed in the extraction processing unit, and the ink ejection drive is performed in units of one time. Thus, bind data including information indicating the operation of each nozzle is generated.

  Therefore, the transfer unit only needs to transfer bind data that does not include extra data to the head. When transferring data to the head, the transfer unit reads redundant data including unnecessary data (data that is not used) and the same contents. This eliminates unnecessary reading processing such as reading data (dot data before adjustment) multiple times. Therefore, it is possible to increase the processing speed until the dot data is adjusted and the adjusted dot data (bind data) is passed to the head unit (line head). In addition, since the adjustment of dot data and the processing until the adjusted dot data is passed to the head are accelerated, it is not necessary to increase the clock speed or use an expensive device corresponding to the increased clock speed. In addition, the manufacturing cost of the ink jet recording apparatus can be reduced.

According to the first aspect of the present invention , the transfer unit includes a transfer memory for storing the bind data, and the bind memory and the transfer memory store information indicating the operation of the nozzle in advance according to the position of the nozzle. It was decided to store it in the specified storage location.

  According to this configuration, the transfer unit includes a transfer memory for storing bind data, and the bind memory and the transfer memory store information indicating the operation of the nozzle in a predetermined storage location according to the position of the nozzle. As a result, there is a one-to-one correspondence between each nozzle included in the head unit and the storage location address. Therefore, it is not necessary to include in the bind data the information indicating which nozzle corresponds to which nozzle, and the size of the bind data can be reduced. As described above, since the bind data is compact, the data transfer amount can be reduced, and the processing until the adjusted image data (bind data) is transferred to the head can be easily accelerated.

In the invention of 請 Motomeko 1, the transfer unit receives the bound data from the main memory and the main memory for receiving said binding data from the bound memory, wherein for transferring the output memory for outputting the bound data to the head portion And a controller for controlling transfer of the bind data between the bind memory and the main memory and between the main memory and the output memory.

  According to this configuration, the transfer unit includes the main memory that receives the bind data from the bind memory and the output memory that receives the bind data from the main memory and outputs the bind data to the head unit as the transfer memory, and between the bind memory and the main memory. And a controller for controlling the transfer of bind data between the main memory and the output memory. Thereby, it is possible to reliably and accurately transfer the bind data between the memories.

According to a second aspect of the present invention , the bind memory and the output memory have a storage capacity corresponding to the size of the bind data for one ink ejection drive, and the main memory is used for printing at least one page. The storage capacity is determined according to the size of the bind data corresponding to the total number of ejection driving operations.

  According to this configuration, the bind memory and the output memory have a storage capacity corresponding to the size of the bind data for one ink ejection drive, and the main memory corresponds to the total number of ejection drives performed for printing at least one page. It has a storage capacity corresponding to the size of the bind data. Thereby, the capacity of the bind memory and the output memory can be reduced, and the manufacturing cost of the ink jet recording apparatus can be reduced. The main memory stores bind data for one page, so when an error such as a jam (paper jam) occurs and printing needs to be performed again, image data is sent again to the inkjet recording device (input). Even without this, printing can be resumed by resending bind data (image data) from the main memory to the head.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the bind memory is an SDRAM.

  Ink jet recording apparatuses may require a capacity of several hundred MBytes or more in order to handle image data. In some cases, the reading speed and the writing speed are required to be several hundred MByte / Sec or more. On the other hand, it is necessary to reduce the manufacturing cost. For example, an HDD (Hard disk drive) is insufficient in terms of reading speed and writing speed even if the capacity is sufficient. In addition, a static random access memory (SRAM) or a solid state drive (SSD) significantly increases the manufacturing cost of the ink jet recording apparatus. Therefore, the bind memory is SDRAM. Thereby, it is possible to avoid a significant increase in manufacturing cost while satisfying the requirements of the reading speed and the writing speed.

  As described above, according to the present invention, dot data is adjusted in accordance with the nozzle installation position (shift in the paper conveyance direction). Then, bind data that is dot data after adjustment is first generated, and then bind data to which no extra data is added is transferred toward the head unit. Therefore, it is not necessary to read out extra data multiple times or transfer data with extra data (redundant data) until the adjusted dot data is input to the head, thus speeding up the processing. Can be achieved.

FIG. 2 is a front sectional view schematically illustrating the configuration of the printer. 2 is a block diagram illustrating an example of a hardware configuration of a printer. FIG. It is a block diagram which shows an example of the mechanism regarding the discharge of ink. It is explanatory drawing which shows an example of arrangement | positioning of a nozzle. It is explanatory drawing which shows an example of adjustment of dot data. It is a block diagram which shows an example of an image process part. It is a block diagram which shows an example of an extraction process part. It is explanatory drawing which shows an example of the bind data stored in the main memory. It is explanatory drawing which shows an example of the state of the bind data accumulate | stored in a bind memory, an output memory, etc. 6 is a flowchart illustrating an example of a flow of dot data adjustment and ink ejection driving.

  Hereinafter, embodiments will be described with reference to FIGS. In the present embodiment, a printer 100 (corresponding to an ink jet recording apparatus) having a fixed line head 4 (corresponding to a head unit) will be described as an example of the ink jet recording apparatus.

(Outline of printer 100)
First, the outline of the printer 100 according to the embodiment will be described with reference to FIG. FIG. 1 is a schematic front sectional view showing a schematic configuration of the printer 100.

  As shown in FIG. 1, a paper feed tray 1 is provided on the left side of the printer 100. The paper feed tray 1 stacks and stores paper. A pair of paper feed rollers 11 is provided at the downstream end of the paper feed tray 1 in the paper transport direction. The pair of paper feed rollers 11 sequentially feeds the stored paper from the top paper to the transport unit 2 one by one.

  A transport unit 2 is provided on the downstream side (right side in FIG. 1) of the paper feed roller pair 11 in the paper transport direction. The transport unit 2 includes a drive roller 21, a driven roller 22 whose axis is parallel to the drive roller 21, and a transport belt 2323 stretched between the drive roller 21 and the driven roller 22. The driving roller 21 rotates upon receiving the driving force of the belt driving motor 25 (see FIG. 2). The conveyor belt 23 circulates as the driving roller 21 rotates. As a result, the paper on the transport belt 23 is transported in the direction of the arrow X in FIG. In addition, a discharge roller pair 31 for discharging a sheet on which an image is recorded (printed) is provided on the downstream side of the conveyance belt 23 in the sheet conveyance direction. Further, the discharge roller pair 31 discharges the printed paper to the discharge tray 3.

  A line head 4 for recording (printing) an image is arranged on each sheet to be conveyed. Specifically, a line head 4C that discharges cyan ink from the upstream side in the paper transport direction between the paper feed roller pair 11 and the discharge roller pair 31 and above the transport belt 23, and a line head 4M that discharges magenta ink. A line head 4Y that discharges yellow ink and a line head 4Bk that discharges black ink are sequentially arranged. These line heads 4C to 4Bk are filled with inks of four different colors (cyan, magenta, yellow and black). Then, each color ink is ejected from each of the line heads 4C to 4Bk, and a color image is recorded (printed) on the paper. In the present embodiment, an example in which line heads 4 for four colors are provided will be described, but line heads 4 of other colors may be provided. The line heads 4C to 4Bk are the same, and in the following description, the reference numerals (C, M, Y, Bk) indicating colors are omitted, and the line heads 4 may be simply referred to as line heads 4.

(Hardware configuration)
Next, an example of the hardware configuration of the printer 100 according to the embodiment will be described with reference to FIG. FIG. 2 is a block diagram illustrating an exemplary hardware configuration of the printer 100.

  First, the printer 100 is provided with a control unit 5 that controls a recording operation (printing operation). The control unit 5 includes a main control unit that performs overall control and image processing, an engine control unit that controls ON / OFF of a motor that rotates image recording and various rotating bodies, an image processing control unit that performs image processing, and the like. A plurality of types of control units may be provided by being divided according to functions and processing contents.

  For example, the control unit 5 is provided with a CPU 51 as a central processing unit. And the control part 5 is connected with the memory | storage part 52 so that communication is possible. For example, the storage unit 52 includes ROM (Read Only Memory), RAM (Random Access Memory), HDD (Hard Disk Drive), and flash ROM nonvolatile and volatile storage devices. The storage unit 52 stores control programs, control data, image data, and the like. The CPU 51 performs calculations and the like based on the control program and control data stored in the storage unit 52, and issues a control signal to each unit of the printer 100.

  The control unit 5 is connected to the communication unit 53. The communication unit 53 is communicably connected to an external computer 200 (for example, a personal computer or a server) or a scanner 300 that reads an image recorded on paper and generates image data via a network or a cable. The communication unit 53 includes various connectors, sockets, a communication control controller, a chip, a memory, and the like. The communication unit 53 receives print data (for example, data including image data and print setting data) for causing the printer 100 to perform printing from the external computer 200 or the scanner 300. When the communication unit 53 receives the printing data, the control unit 5 operates each line head 4 or the transport unit 2 based on the printing data to perform printing.

  The image processing unit 6 performs various image processes on various image data such as image data received from the computer 200 and image data stored in the storage unit 52. Note that image processing that can be performed by the image processing unit 6 is diverse, and the image processing unit 6 can perform known image processing, and the description of the content of each image processing is omitted for convenience. Then, the image processing unit 6 finally indicates the presence / absence of dot formation (ink ejection) and the ejection amount for each pixel (each dot) in one page based on the image data indicating the content to be printed on the paper. Convert to dot data. The image processing unit 6 adjusts dot data according to the position of the nozzle 8 in the paper conveyance direction for each color, and transmits the adjusted dot data (details will be described later) to the driver 7 of each line head 4. The image processing unit 6 may be functionally realized by the CPU 51, the storage unit 52, and the program of the control unit 5.

  The control unit 5 (image processing unit 6) is connected to each line head 4 and instructs each line head 4 to operate. Each line head 4 is provided with a driver 7 that actually controls the ejection of ink from each nozzle 8. Each driver 7 simultaneously ejects ink from each nozzle 8 at a constant cycle. Each driver 7 adjusts the presence / absence of ink ejected from each nozzle 8 and the amount of ink ejected based on the adjusted dot data, thereby adjusting the gradation (dot area) of dots formed on the recording medium. Control. For example, each driver 7 adjusts the presence / absence of ink ejection and the ejection amount by changing the drive voltage value and drive pulse width applied to each nozzle 8 based on an instruction from the control unit 5.

  As shown in FIG. 2, the control unit 5 is connected to each part of the printer 100 such as the paper feed roller pair 11, the transport unit 2, the discharge roller pair 31, and the operation panel 54. The control unit 5 controls and instructs the operation of each unit. For example, the operation panel 54 includes hard keys (not shown) and a display unit (not shown) that includes a touch panel and displays soft keys. The operation panel 54 receives an input made by pressing a hard key or a soft key. The operation panel 54 recognizes the input content and transmits data indicating the input content to the control unit 5. The control unit 5 causes each part to perform an operation in accordance with the input content.

  The encoder 24 of the transport unit 2 is connected to a driving roller 21 or a driven roller 22 that stretches the transport belt 23. The encoder 24 outputs a pulse in accordance with the rotational displacement (rotation angle) of the rotation shaft of the driving roller 21 or the driven roller 22 (for example, one pulse in a few rounds or half a circle, which can be arbitrarily set). The controller 5 counts the number of pulses transmitted from the encoder 24 and grasps the sheet feed amount from the rotation amount. Further, the control unit 5 grasps the rotational speed of the belt drive motor 25 based on the cycle of the signal from the encoder 24, and controls the rotational speed of the belt drive motor 25 so that the paper transport speed is constant. Then, the control unit 5 causes the transport unit 2 to transport the paper so that the paper advances by one dot (one line width) with respect to the ejection of ink from the nozzle 8 once.

  The paper sensor 26 is a sensor for measuring the image recording start timing. For example, the paper sensor 26 is an optical sensor, and the output changes depending on whether the paper is present in the detection area or not. The paper sensor 26 is connected to the control unit 5. Based on the distance between the sheet sensor 26 and the position of the nozzle 8 of each line head 4 and the sheet conveyance speed, the control unit 5 measures the time for each line head 4. When the time set for each line head 4 (for each line head 4) is counted, the control unit 5 causes each line head 4 to start ejecting ink. In other words, the control unit 5 causes each line head 4 to start ejecting ink when a time required to convey the distance from the paper sensor 26 to each nozzle 8 has elapsed from the time when the leading edge of the paper is detected (printing of one page). start).

  The suction unit 27 applies a voltage to the paper-feed-side driven roller 22 based on a signal from the control unit 5 to cause the paper to be electrostatically attracted to the transport belt 23 (or suction by suction). The electrostatic adsorption is released based on an instruction from the control unit 5 when the adsorption unit 27 performs grounding.

(Ink ejection control mechanism)
Next, an example of a mechanism related to ink ejection in the printer 100 according to the embodiment will be described with reference to FIG. FIG. 3 is a block diagram illustrating an example of a mechanism related to ink ejection.

  Each line head 4 (4C to 4Bk) applies a voltage to each of the plurality of nozzles 8, one piezoelectric element 81 (piezo element, PZN, etc.) for each nozzle 8, and discharges ink. A plurality of drivers 7 that actually control For example, about 2500 nozzles (2500 dots) are provided in each line head 4 depending on the printable paper size in the specification. The number of nozzles 8 provided in each line head 4 may be less than 2500, or 2500 or more. In FIG. 3, for the sake of convenience, only one line head 4Bk among the line heads 4 is shown with a part of the internal configuration, but the configuration of each line head 4 is basically the same and is not shown. doing.

  Each nozzle 8 is formed by making a hole in a metal plate by etching or the like. A piezoelectric element 81 is provided for each nozzle 8. The driver 7 applies a voltage to the piezoelectric element 81 that causes ink to be ejected in accordance with the dot data among the piezoelectric elements 81 under its control. For example, the control unit 5 (image processing unit 6) gives information indicating the operation of each nozzle 8 in units of one ejection drive to each driver 7 (the presence / absence of ejection, information indicating density, and adjusted dot data). Send. Each driver 7 applies a voltage to the piezoelectric element 81 corresponding to the nozzle 8 to which ink is to be ejected based on information indicating the operation of each nozzle 8. As a result, the piezoelectric element 81 is deformed by voltage application, and pressure is applied to a flow path (not shown) for supplying ink to the nozzle 8. And the pressure with respect to a flow path propagates and ink is ejected from the nozzle 8.

  Each driver 7 can change the voltage applied to the piezoelectric element 81. For example, the voltage applied to the piezoelectric element 81 can be made smaller than the reference voltage applied to the piezoelectric element 81. Accordingly, the driver 7 can adjust the ink discharge speed and the discharge amount with respect to the reference ink discharge speed and the discharge amount, and can make a difference in the density of one dot.

(Disposition of nozzles 8 in the line head 4)
Next, an example of the arrangement of the nozzles 8 in the printer 100 according to the embodiment will be described with reference to FIG. FIG. 4 is an explanatory diagram showing an example of the arrangement of the nozzles 8.

  First, FIG. 4 shows an arrangement of 16 extracted nozzles 8 among a plurality of nozzles 8 provided in each line head 4. And the left-right direction of FIG. 4 is a paper conveyance direction (printing direction). 4 is the line direction (the longitudinal direction of the line head 4 and the direction perpendicular to the paper transport direction). Further, a square (rectangle) in FIG. 4 represents one dot (one pixel). Each nozzle 8 is formed with a diameter corresponding to the pitch of one pixel (one dot).

  In order to indicate the position of each nozzle 8 as coordinates, in FIG. 4, numbers 0 to 23 are added as scales indicating the number of rows for each row (each dot) in the paper conveyance direction, and the vertical direction For each line (each dot) in the (line direction), the alphabet of A to P is attached as a scale indicating the number of lines.

  If the nozzles 8 are formed in a straight line in the line head 4 in the line direction, it is not necessary to shift the dot data, and the head portion can be miniaturized, which is ideal. However, the higher the resolution of the printer 100 (the shorter the diameter of the nozzles 8), the more difficult it is to form (process) the nozzles 8 in a straight line in the line direction.

  Therefore, in each line head 4 of the present embodiment, one nozzle 8 is provided for each dot so as not to overlap in the line direction. In the paper transport direction (printing direction), the positions of the nozzles 8 adjacent to each other in the line direction are shifted while providing an interval in dot pitch units (line width units). Specifically, in the example of FIG. 4, in terms of coordinates, A0 (A row 0 column), B3 (B row 3 column), C6 (C row 6 column), D9 (D row 9 column), E12 (E Row 12), F15 (F15), G18 (G Row 18), H21 (H Row 21), I0 (I Row 0), J3 (J Row 3), K6 (K Row 6) , L9 (row L9 column), M12 (M row 12 column), N15 (N row 15 column), O18 (O row 18 column), P21 (P row 21) are arranged.

  First, in the line head 4 of the present embodiment, the nozzle 8 is provided on the most upstream side in the sheet conveyance direction for each a dot in the line direction (every 8 dots in the example of FIG. 4, other than 8 dots may be used) (in FIG. 4). A line and I line). In other words, the nozzles 8 are provided at the most upstream position in the sheet conveyance direction in the line direction with a period of 8 dots.

  In the line head 4 of the present embodiment, the nozzles 8 on the most upstream side in the paper transport direction are shown by dotted arrows in FIG. 4 for each b dot as they go downstream in the paper transport direction. In the example, 7 nozzles 8 are provided (every 3 dots, other than 3 dots) (3, 6, 9, 12, 15, 18, 21 rows in FIG. 4). Further, in the line head 4 of this embodiment, the position of the nozzle 8 is shifted upward by one dot in the line direction toward the downstream side in the paper transport direction with respect to the nozzle 8 on the most upstream side in the paper transport direction (B Line-H line, J line to P line).

  If the position of the nozzle 8 on the most upstream side in the sheet conveying direction is (X (row) = 0, Y (column) = 0), the position of the downstream nozzle 8 is (X = b × n, Y = n). Position. Further, b is an interval in the paper conveyance direction, n is an arbitrary integer, and the unit is a pitch per dot. Thus, in each line head 4 of the present embodiment, each nozzle 8 is formed based on a certain rule while shifting the position in the paper transport direction. In other words, each nozzle 8 is formed so that the position in the paper transport direction is the same for every fixed number (eight) of nozzles 8.

(Necessity of dot data adjustment)
Next, the necessity for adjustment of dot data will be described with reference to FIGS. FIG. 5 is an explanatory diagram showing an example of dot data adjustment.

  As described with reference to FIG. 4, the position of the nozzle 8 of each line head 4 of this embodiment is shifted in the paper transport direction (printing direction). For this reason, if the dot data indicating the printed state is not adjusted and is supplied to each driver 7 line by line and ink is ejected from the nozzles 8, the displacement of the positions of the nozzles 8 is reflected in printing.

This will be specifically described with reference to FIG. FIG. 5 shows an example of dot data. One square in FIG. 5 represents one dot. And “0” written in each dot (each square) is “no discharge”
“1” indicates “discharge at a high density” (shown with a strong shading in FIG. 5), and “2” indicates “discharge at a low density” (shown with a weak shading in FIG. 5). . As described above, each driver 7 of the present embodiment can change the density by changing the ink discharge amount in dot units.

  In FIG. 5, dot data on the left side indicates image data before adjustment (dot data indicating a printed state). This data indicates that solid coating is performed at a high density for two lines and then solid coating is performed at a low density.

  In the present embodiment, the control unit 5 causes each driver 7 to eject ink from each nozzle 8 once every time the transport unit 2 transports one dot (one line). In other words, ink is ejected from the nozzles 8 at the same time (the ejection cycle is the same), and the control unit 5 feeds the paper for one dot (for one line) between the ink ejection and the ejection to the transport unit 2. Transport.

  When the pre-adjustment dot data shown in FIG. 5 is given to the driver 7 as it is, ink is ejected while the positional deviation of each nozzle 8 is reflected. With the arrangement of the nozzles 8 shown in FIG. 4, when ink is ejected based on the dot data before adjustment, a diagonal line is printed along the line, not on a straight line.

  Therefore, in accordance with the arrangement of the nozzles 8, it is necessary to adjust the ink ejection timing of each dot with respect to one line of dot data. Specifically, the discharge timing is delayed according to the distance in the paper transport direction with respect to the nozzle 8 that is most upstream in the paper transport direction.

  For example, the B8 nozzle 8 shown in FIG. 4 is shifted from the A0 nozzle 8 by 3 dots (3 lines) in the paper transport direction. Therefore, when drawing a straight line in the line direction, the nozzle 8 of B3 is used when the discharge drive of the nozzle A8 of A0 (first time) is performed three times after the discharge drive (fourth time of discharge drive, after moving by three lines). Ink may be discharged. Similarly, for the C6 nozzle 8, it is only necessary to discharge ink to the C6 nozzle 8 during the discharge drive (seventh discharge drive) six times after the discharge drive (first time) of the A0 nozzle 8. For the nozzle 8 of D9, it is only necessary to discharge ink to the nozzle 8 of D9 at the time of the discharge drive (first discharge drive) nine times after the discharge drive (first time) of the A0 nozzle 8; For the nozzle 8, it is only necessary to eject ink to the nozzle E 8 at the time of the ejection drive (13th ejection drive) 12 times after the ejection drive (first time) of the A 0 nozzle 8. 8, it is only necessary to discharge ink to the nozzle 15 of the F15 at the time of the discharge drive (the 16th discharge drive) 15 times after the discharge drive of the A0 nozzle 8 (first time). A0 nozzle It is sufficient that ink is ejected to the nozzle 18 of G18 at the time of the ejection driving 18 times after the ejection driving (first time) (19th ejection driving). For the nozzle 8 of H21, the ejection of the nozzle 8 of A0 is performed. The ink may be ejected to the nozzles 21 of H21 at the time of ejection driving 21 times after the driving (first time) (22nd ejection driving). Since I0 to P21 are the same, they are omitted.

  In this way, in order to obtain an intended printed matter, adjustment for shifting (shifting) the ejection timing of ink according to the distance in the paper conveyance direction from the most upstream nozzle 8 in the paper conveyance direction is performed on the dot data. There is a need to do.

(Flow of image processing by image processing unit 6)
Next, an example of the flow of image processing by the image processing unit 6 including adjustment of dot data will be described with reference to FIGS. FIG. 6 is a block diagram illustrating an example of the image processing unit 6. FIG. 7 is a block diagram illustrating an example of the extraction processing unit 91. FIG. 8 is an explanatory diagram showing an example of bind data stored in the main memory 95.

  As described above, the communication unit 53 receives printing data including the contents to be printed by the printer 100 and setting information from the computer 200 or the like. For example, the image processing unit 6 is provided with a raster data generation unit 61. For example, the raster data generation unit 61 generates bitmap format image data based on the description content in the page description language included in the print data. In other words, the raster data generating unit 61 generates image data including pixel values in which each pixel indicates density.

  The image data generated by the raster data generation unit 61 is delivered to the image processing circuit 62. The image processing circuit 62 performs various image processing on the image data. When image data in the raster data format is received from the computer 200 or the like, the image data may be delivered to the image processing circuit 62 without using the raster data generation unit 61.

  The image processing circuit 62 includes a circuit that performs a plurality of image processing. For example, the image processing circuit 62 includes a circuit that performs format conversion (color conversion or the like) of image data and a circuit that performs image data processing (for example, density conversion or zoom). In accordance with the setting data included in the printing data, the image processing circuit 62 performs image processing on the image data.

  The image data subjected to the image processing by the image processing circuit 62 is given to the halftone processing unit 63. The halftone processing unit 63 performs halftone processing to convert image data into dot data. The halftone processing unit 63 generates dot data for each color, which is data indicating ON / OFF of dots (data indicating the presence / absence of ink ejection and density of each pixel). For example, the halftone processing unit 63 generates dot data for each color using a technique such as a dither method.

  The dot data generated by the halftone processing unit 63 is stored in the image memory 64. Then, the image memory 64 inputs the dot data to the output processing unit 9 line by line. The image memory 64 may not be provided, and dot data may be input from the halftone processing unit 63 to the output processing unit 9 line by line.

  The output processing unit 9 is a part that adjusts dot data according to the arrangement of the nozzles 8 of the line head 4 and outputs the adjusted dot data to the line head 4 (driver 7). Note that one output processing unit 9 may be provided for each color. However, since there is no difference in the contents and methods of processing performed by each output processing unit 9, the following description will be given without mentioning color distinction, and only one output processing unit 9 is shown in FIG. The following explanation applies to the output processing unit 9 of any color.

  For example, the output processing unit 9 includes an extraction processing unit 91, a bind memory 92, a write DMA controller 93 (equivalent to a transfer unit and a controller), a memory controller 94 (equivalent to a transfer unit and a controller), and a main memory 95 (a transfer unit and transfer). A read DMA controller 96 (equivalent to a transfer unit and a controller), and an output memory 97 (equivalent to a transfer unit and a transfer memory). For example, the extraction processing unit 91, the bind memory 92, the write DMA controller 93, the memory controller 94, the read DMA controller 96, and the output memory 97 are made into one chip as a single chip (which is made into an ASIC, with broken lines in FIG. 6). Enclosing range).

  The extraction processing unit 91 determines whether or not ink is ejected in units of ink ejection driving from the dot data before adjustment according to the displacement of each nozzle 8 of the line head 4 in the paper conveyance direction (according to the arrangement of the nozzles 8). And a circuit for obtaining bind data (adjusted dot data collected in units of one discharge drive) in which information indicating the discharge density of ink is determined for each nozzle 8.

  An example of the extraction processing unit 91 will be described. As shown in FIG. 7, the extraction processing unit 91 can include a shift register group 910 including a plurality of shift registers 91R. Each shift register 91R outputs dot data obtained by delaying the input data by the nozzle interval (dot number) in the line direction. As in the example shown in FIG. 4, if the nozzles 8 are provided by 8 dots in the same row (line direction), each shift register 91R has dot data obtained by delaying data inputted by 8 dots in the line direction. Is output.

  Note that a clock signal (for example, generated by the clock generation unit 55 provided in the control unit 5; see FIG. 2) is supplied to each shift register 91R in order to match the timing for performing the shift. The period of the clock signal generated by the clock generation unit 55 is the same as the time per line. Alternatively, a clock signal obtained by multiplying the clock signal generated by the clock generation unit 55 may be given to each shift register 91R. Each driver 7 ejects ink in synchronization with the clock signal, and the control unit 5 controls the transport unit 2 so that one line of paper is transported in the cycle of the clock signal. In other words, the clock signal is a signal for synchronizing ink ejection driving, paper conveyance, and shift.

  For example, in the head 4 of each color of this embodiment, if about 2400 nozzles (2400 dots) are provided along the line direction, about 300 (2400 ÷ 8) shift registers 91R are provided (in FIG. 7). Only part of it is shown).

  The extraction processing unit 91 includes a reading control unit 911 as a controller that controls reading of dot data from the image memory 64. The read control unit 911 reads dot data corresponding to the installation position of the nozzle 8 from the dot data stored in the image memory 64 in units of lines (line direction) in the main scanning direction, and inputs the dot data to the shift register group 910 one by one. .

  This will be described using an example of the arrangement of the nozzles 8 shown in FIG. For example, the reading control unit 911 uses the nozzle 8 in the dot data stored in the image memory to perform the ejection drive (the dot to be extracted from the dot data in the ejection drive varies depending on the transport position of the paper). The dot data of the lines corresponding to the installation positions (lines corresponding to 0, 3, 6, 9, 12, 12, 15, 18, 21 in the example of FIG. 4) are sequentially read out in line units. Input to the shift register group 910. Each shift register 91R outputs dot data obtained by delaying the input data by the interval of the nozzles 8 in the line direction (8 dots in the example of FIG. 4). Then, the bind memory 92 takes in the data (output) of each shift register 91R as the bind data when the first (upper) bit (for example, the bit in the A row 0 column) is output from the shift register 91R at the rearmost stage ( Store). In other words, the bind memory 92 stores the output of each shift register 91R when dot data corresponding to the installation position of the nozzle 8 is being output.

  Specifically, the nozzles in the 0th column line such as the dot data corresponding to the position of the nozzle 8 in the A row 0 column and the dot data corresponding to the position of the nozzle 8 in the I row 0 column when the ejection driving is performed. The dot data corresponding to the position 8 is stored in the bind memory 92 as bind data. As a result, the bind memory 92 stores the dot data of the installation positions of the nozzles 8 from the nozzle 8 at the head position in the line direction to the tail direction as bind data.

  Next, in accordance with the interval in the sheet conveyance direction of the nozzles 8 (3 dots in the example of FIG. 4), the read control unit 911 performs dots corresponding to the positions of the nozzles 8 in the third row line when performing the ejection driving. Data is input to the shift register group 910. As a result, the bind memory 92 stores the dot data corresponding to the position of the nozzle 8 in the B row and the third column, followed by the dot data corresponding to the position of the nozzle 8 in the J row and the third column. 8 is stored in the bind memory 92 as bind data. Thereafter, the read control unit 911 inputs dot data to the shift register group 910 in units of lines at intervals of 3 dots in the 6th, 9th, 12th, 15th, 18th, and 21th rows in the paper conveyance direction. The dot data corresponding to the installation positions of the nozzles 8 in each row is stored in the bind memory 92 as bind data. A plurality of shift register groups 910 may be provided in order to increase the generation speed of bind data.

  In this way, the nozzle data extracted according to the position of the nozzle 8 in one ejection drive is performed by repeating the dot data extraction process corresponding to the nozzle interval in units of lines for each line in the paper transport direction. 8 is stored in the bind memory 92 as bind data. In other words, the extraction processing unit 91 extracts and generates dot data that excludes dot data that does not correspond to the installation position of the nozzle 8 from the dot data of the line, and stores it in the bind memory 92.

  As a result, the bind data includes the nozzle 8 that ejects ink in one ejection drive in a predetermined order of the nozzles 8 and information indicating the ink ejection density.

  As described above, the read control unit 911 instructs data transfer from the image memory 64 to the shift register group 910 in the extraction processing unit 91, and the image memory 64 automatically generates bind data when data is transferred in line units. Since it is stored in the bind memory 92, it is favorable in terms of processing speed and efficiency.

  Each dot of the dot data corresponds to each pixel in each printed matter, and the order in which the dots are rearranged when generating the bind data is fixedly determined according to the arrangement of the nozzles 8. Accordingly, the shift register group 910 is not provided, and the read control unit 911 reads in advance information indicating the ink discharge density in the order of the nozzles 8 in accordance with the arrangement of the nozzles 8 from the image memory 64. The bind data may be stored in the bind memory 92 by reading the dot data in a predetermined address order and storing the dot data in the bind memory 92 in the read order.

  The bind data stored in the bind memory 92 is transferred to the main memory 95. The main memory 95 stores the transferred bind data. As shown in FIG. 8, the main memory 95 stores bind data for a plurality of times of ejection driving. For example, the main memory 95 has a capacity that can store bind data of 1 to several tens of pages (for example, 10 pages) at the maximum paper size that can be printed.

  FIG. 8 shows the storage state of each bind data in the main memory 95 when performing L-time ejection driving for printing one page. The main memory 95 of the present embodiment can store bind data for a plurality of pages, and FIG. 8 shows an example of a state in which bind data for the second page (from the L + 1th time) is stored.

  When bind data for one page or a plurality of pages is accumulated in the main memory 95, the bind data is sequentially transferred to the output memory 97 for each ejection drive. Then, bind data for one ejection drive is sequentially transferred from the output memory 97 to each driver 7 of the line head 4. Based on this bind data, each driver 7 causes ink to be ejected from each nozzle 8.

  The write DMA controller 93 controls writing of the bind data stored in the bind memory 92 to the main memory 95. The read DMA controller 96 reads the bind data stored in the main memory 95 and controls the transfer to the output memory 97. The memory controller 94 gives an instruction to the write DMA controller 93 and the read DMA controller 96 to control the writing and reading control of the main memory 95 in the image processing unit 6. In other words, each transfer memory such as the bind memory 92 → the main memory 95 → the output memory 97 is controlled by a controller (a write DMA controller 93, a memory controller 94, and a read DMA controller 96).

(Store bind data in each memory)
Next, storage of bind data will be described with reference to FIG. FIG. 9 is an explanatory diagram showing an example of the state of bind data stored in the bind memory 92, the output memory 97, and the like.

  The extraction processing unit 91 outputs information indicating the operation of each nozzle 8 to the bind memory 92 for each nozzle 8 in units of ink ejection drive. For example, if the number of nozzles 8 is 2500 per line head 4, the extraction processing unit 91 outputs information indicating the operation of 2500 nozzles 8 as bind data.

  The bind data is transferred in the order of the bind memory 92, the main memory 95, and the output memory 97. Note that SDRAM is used for the bind memory 92, the main memory 95, and the output memory 97 from the viewpoint of satisfying the cost, the transfer rate, and the capacity.

  In the bind memory 92, the main memory 95, and the output memory 97, it is determined in advance at which location (memory address) information about which nozzle 8 is stored. In other words, in each memory, information indicating the operation of the nozzle 8 is stored in a predetermined storage location according to the position of each nozzle 8, and the storage location (address of the stored memory) indicates the corresponding nozzle 8. . For example, information indicating the operation of the A0 nozzle 8 is always stored in a storage location (address) determined in each memory.

  The bind memory 92 stores information indicating the operation of each nozzle 8 in the bind data output from the extraction processing unit 91 at a predetermined address corresponding to the position of the nozzle 8. The write DMA controller 93 reads the bind data from the bind memory 92 and stores information indicating the operation of each nozzle 8 at a predetermined address in the main memory 95 corresponding to the position of the nozzle 8. The read DMA controller 96 reads the bind data from the main memory 95 and stores information indicating the operation of each nozzle 8 at a predetermined address in the output memory 97 corresponding to the position of the nozzle 8. Accordingly, it is not necessary to attach data indicating the position of the nozzle 8 to the information indicating the operation of the nozzle 8 in the bind data.

  The capacities of the bind memory 92 and the output memory 97 of this embodiment have a capacity capable of storing bind data for one ejection drive of all the nozzles 8 (may be one or more times). For example, if information indicating the presence / absence of discharge, darkness, or lightness is included in the information indicating the operation, at least 2 bits are required for each nozzle. For example, if there are 2500 nozzles 8 per line head 4, the bind memory 92 and the output memory 97 have a capacity of 2500 (number of nozzles 8) × 2 (bits). If the ejection driving is performed 5000 times per page, the bind data for one page is 2500 (number of nozzles) × 2 (bits) × 5000 (number of ejection driving times). For example, the main memory 95 has a capacity capable of storing as many bind data as can be stored.

(Dot data adjustment and ink ejection drive flow)
Next, an example of dot data adjustment and ink ejection driving flow (processing flow of the output processing unit 9) in the printer 100 according to the present embodiment will be described with reference to FIG. FIG. 10 is a flowchart illustrating an example of the flow of dot data adjustment and ink ejection driving.

  In the flowchart of FIG. 10, an example of printing one page will be described. When printing over a plurality of pages, ink discharge may be started after storing bind data for a plurality of pages in the main memory 95, or the flowchart of FIG. 10 may be repeated for each page.

  The start of FIG. 10 is the time when the halftone processing unit 63 generates dot data corresponding to the image data in order to start printing based on the printing data transmitted from the computer 200.

  Then, the image processing unit 6 (control unit 5) inputs dot data to the extraction processing unit 91 in units of one line (step # 1). Then, the extraction processing unit 91 shifts (delays) information indicating the operation of the nozzle 8 of each dot in the dot data in accordance with the position of the nozzle 8, and information indicating the operation of each nozzle 8 in one ejection drive. The combined bind data is generated (step # 2). The bind memory 92 stores the generated bind data (step # 3). Next, the memory controller 94 and the write DMA controller 93 transfer the bind data in the bind memory 92 to the main memory 95 (step # 4).

  Then, the memory controller 94 confirms whether or not a predetermined amount of bind data has been accumulated in the main memory 95 as an ink discharge start condition (step # 5). In other words, the memory controller 94 checks whether or not a predetermined amount of bind data has been accumulated in the main memory 95 (step # 5).

  For example, when printing is stopped due to an error such as a jam (paper jam), the main memory 95 does not need to re-send printing data from the computer 200 or perform image processing again when printing is performed again. Binding data for one page or a plurality of pages is accumulated. The control unit 5 can detect the occurrence of a jam based on the output of the paper sensor 26. For example, based on the paper feed start time, the paper transport speed, and the installation position of the paper sensor 26, the paper sensor 26 should detect the arrival of the paper but not detect it, or the paper sensor 26 should detect the passage of the paper. When not, the control unit 5 recognizes that a jam has occurred.

  Therefore, in this flowchart, the ink discharge start condition is the time when bind data for one page is accumulated in the main memory 95. When printing continuously over a plurality of pages in one print job, ink ejection may be started when bind data for a plurality of pages is accumulated in the main memory 95, or for one page. Each time the bind data is accumulated in the main memory 95, ink ejection may be started.

  If accumulation of bind data has not been completed (No in step # 5), the flow returns to step # 1. On the other hand, if the accumulation of the bind data has been completed (Yes in step # 5), the read DMA controller 96 passes the bind data in the main memory 95 through the output memory 97 one by one for each ejection drive unit. (Bind data for one page in total. Step # 6). As a result, the driver 7 ejects ink from each nozzle 8 at a constant cycle based on the bind data, and printing (recording) on the paper for one page is performed. Note that the control unit 5 feeds and conveys paper in accordance with ink ejection.

  When the printing of one page is completed, the main memory 95 deletes the printed bind data for one page (step # 7). Then, this flow ends (END).

  In this way, the ink jet recording apparatus shown in the present embodiment ejects ink at a predetermined timing, is provided with at least one for each dot in the line direction, and is provided with a shifted position in the paper transport direction. A head unit (line head 4) including a plurality of nozzles 8, a halftone processing unit 63 that converts image data into dot data indicating the presence or absence of dot formation for each pixel in one page, and a halftone processing unit 63 An extraction processing unit 91 that shifts the generated dot data in accordance with the displacement of the position of the nozzle 8 in the paper transport direction and generates bind data including information indicating the operation of each nozzle 8 in units of ink ejection drive. A bind memory 92 that stores the bind data output by the extraction processing unit 91, and the bind memory 92 stores the bind data. A transfer unit (main memory 95, output memory 97, write DMA controller 93, memory controller 94, read DMA controller 96, etc.) for transferring Indian data to the head unit, and each nozzle 8 of the head unit is bound Based on the data, ink ejection drive is performed.

  As a result, the position adjustment (line shift) of each pixel in the image data according to the installation position of the nozzle 8 (shift in the paper transport direction) is first performed by the extraction processing unit 91, and the ink is ejected once. Bind data including information indicating the operation of each nozzle 8 is generated in units. Therefore, the transfer unit (main memory 95, output memory 97, write DMA controller 93, memory controller 94, read DMA controller 96, etc.) only has to transfer bind data that does not contain extra data to the head. When transferring data to the, there is no need to perform unnecessary read processing such as reading redundant data including unnecessary data (data not used) or reading the same data (dot data before adjustment) multiple times. . Therefore, it is possible to increase the processing speed until the dot data is adjusted and the adjusted dot data (bind data) is passed to the head unit. In addition, since the adjustment of dot data and the processing until the adjusted dot data is passed to the head are accelerated, it is not necessary to increase the clock speed or use an expensive device corresponding to the increased clock speed. The manufacturing cost of the ink jet recording apparatus (printer 100) can be reduced.

  The transfer unit includes a transfer memory (main memory 95, output memory 97) for storing bind data, and the bind memory 92 and the transfer memory have predetermined information indicating the operation of the nozzle 8 according to the position of the nozzle 8. Store in the storage location. As a result, there is a one-to-one correspondence between each nozzle 8 included in the head portion (line head 4) and the storage location address. Accordingly, it is not necessary to include in the bind data information indicating which nozzle 8 corresponds to which information indicating the operation of which nozzle 8, and the size of the bind data can be reduced. As described above, since the bind data is compact, the data transfer amount can be reduced, and the processing until the adjusted image data (bind data) is transferred to the head can be easily accelerated.

  The transfer unit includes a main memory 95 that receives bind data from the bind memory 92 and an output memory 97 that receives bind data from the main memory 95 and outputs the bind data to the head unit (line head 4) as a transfer memory. And controllers (a write DMA controller 93, a memory controller 94, and a read DMA controller 96) that control the transfer of bind data between the main memory 95 and the main memory 95 and the output memory 97. Thereby, it is possible to reliably and accurately transfer the bind data between the memories.

  The bind memory 92 and the output memory 97 have a storage capacity corresponding to the size of the bind data for one ink ejection drive, and the main memory 95 binds for the total number of ejection drives performed when printing at least one page. It has a storage capacity corresponding to the data size. Thereby, the capacity of the bind memory 92 and the output memory 97 can be reduced, and the manufacturing cost of the ink jet recording apparatus (printer 100) can be reduced. Since the main memory 95 stores bind data for one page, when an error such as a jam (paper jam) occurs and printing needs to be performed again, image data is sent again to the inkjet recording apparatus (input). ), The printing can be resumed by resending the bind data from the main memory 95 to the head.

  In addition, the ink jet recording apparatus (printer 100) may require a capacity of several hundred MBytes or more in order to handle image data. In some cases, the reading speed and the writing speed are required to be several hundred MByte / Sec or more. On the other hand, it is necessary to reduce the manufacturing cost. For example, an HDD (Hard disk drive) is insufficient in terms of reading speed and writing speed even if the capacity is sufficient. In addition, the manufacturing cost of the inkjet recording apparatus (printer 100) is greatly increased in static random access memory (SRAM) and solid state drive (SSD). Therefore, the bind memory 92 is an SDRAM. Thereby, it is possible to avoid a significant increase in manufacturing cost while satisfying the requirements of the reading speed and the writing speed.

  The embodiment of the present invention has been described above, but the scope of the present invention is not limited to this, and various modifications can be made without departing from the spirit of the invention.

  The present invention is applicable to an ink jet recording apparatus in which the position of a nozzle is shifted in the paper transport direction.

100 Printer (inkjet recording device) 4 Line head (head)
63 Halftone processing unit 8 Nozzle 91 Extraction processing unit 92 Bind memory 93 Write DMA controller (transfer unit, controller)
94 Memory controller (transfer unit, controller)
95 Main memory (transfer section, transfer memory)
96 Read DMA controller (transfer unit, controller)
97 Output memory (transfer section, transfer memory) jet recording device)

Claims (3)

A head unit that ejects ink at a predetermined timing and includes a plurality of nozzles that are provided at least one for each dot in the line direction and that are shifted in the paper conveyance direction;
A halftone processing unit that converts image data into dot data indicating the presence or absence of dot formation for each pixel in one page;
The dot data generated by the halftone processing unit is shifted in accordance with the displacement of the nozzle position in the paper conveyance direction, and bind data including information indicating the operation of each nozzle in units of ink ejection driving. An extraction processing unit to generate,
A bind memory for storing the bind data output by the extraction processing unit;
A transfer unit that transfers the bind data stored in the bind memory toward the head unit,
The transfer unit has a main memory for receiving the bind data from the bind memory and an output memory for receiving the bind data from the main memory and outputting the bind data to the head unit as a transfer memory for storing the bind data. Further including a controller that controls transfer of the bind data between the bind memory and the main memory, and between the main memory and the output memory,
The bind memory and the transfer memory store information indicating the operation of the nozzle in a predetermined storage location according to the position of the nozzle,
Each of the nozzles of the head unit performs ink ejection driving based on the bind data. The bind memory and the output memory have a storage capacity corresponding to the size of the bind data for one ink ejection drive,
2. The ink jet recording apparatus according to claim 1 , wherein the main memory has a storage capacity corresponding to the size of the bind data corresponding to the total number of times of ejection driving performed when printing at least one page. 3. The ink jet recording apparatus according to claim 1, wherein the bind memory is an SDRAM.

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