JP2013224008A - Image recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image recording apparatus that has improved image quality by reading out print data to be shifted into a print head, a following discharge data and a next following discharge data so that the landing position of the discharged ink may become a straight line, when the nozzle row of the print head is diagonally arranged by A, B, and C row, selecting bit from corresponding each data so that the landing positions may become a straight line according to the displacement of the nozzle, and controls to make the landing positions of the ink may become a straight line by shifting in the head.SOLUTION: Image quality can be improved by including a plurality of print heads in which nozzle rows disposed in three rows of A, B, and C are diagonally arranged, reading out from the discharge data accumulated in the memory, Nth discharge data, (N+1)th discharge data, and (N+2)th discharge data from memory according to the signals indicating discharge timing and moving direction of the carriage generated from a linear scale encoder, and making the ink landing on the straight line by performing data shift in to the print head and discharge operation of A, B, and C-phases.

Description

  The present invention relates to an image recording apparatus provided with an ink jet print head.

  The print data is stored in a FIFO memory before being shifted into the ink jet print head, from which it is read and printed according to the print resolution. The data shifted into the print head is landed on a recording medium such as plastic film or paper in a straight line by one ejection and forms an image.

  If the print head nozzle array is in a straight line, the landing position will also be in a straight line, but if the print head nozzle array is slanted with respect to the main scanning direction, The position is not aligned and the image quality is degraded. Therefore, the landing position is made straight by adjusting the discharge timing.

JP 2003-19792 A

  There is known a print head in which the nozzle rows are divided into three rows A, B, and C, and the rows are arranged in parallel. In such a print head, adjacent dots formed on a recording medium are formed by ink ejected from nozzles arranged in different rows. More specifically, if a nozzle near one end in the longitudinal direction of the head is in row A, the next nearest nozzle is in row B, the next nearest nozzle is in row C, and the next nearest nozzle is As shown in the A column, the A, B, and C columns are arranged in this order. At this time, the nozzles that form adjacent dots are disposed obliquely with respect to the longitudinal direction. The reason is that if the adjacent nozzles are too close, it is difficult to form the nozzles, and if the adjacent nozzles are too close, other nozzles may be adversely affected during ink discharge and cause discharge failure. . There are cases where such nozzle arrangement is used when it is desired to arrange nozzles at a higher density in the sub-scanning direction.

  When the nozzles that form adjacent dots are arranged obliquely in this way, in order to land the ejected ink in a straight line, the timing is adjusted in the order of the A, B, and C rows, and the ejection operation is performed. Is going. Further, when the carriage on which the print head is mounted moves in the opposite direction, the ejection operation is performed in the order of C, B, and A rows. However, when high-resolution printing is performed, the distance that the carriage moves during the discharge timing time of the A, B, and C rows becomes smaller than the distance between the nozzles between the A, B, and C rows, and the landing position is in a straight line. Don't be. For this reason, the landing accuracy deteriorates and the image quality deteriorates.

  Therefore, in order to solve such a problem, the present invention changes the FIFO memory to 2PORT-RAM so that the print data to be shifted into the print head can be read out the next discharge data and the next discharge data. Select the corresponding bit from each data so that the landing will be in a straight line according to the displacement of the nozzle and shift in to the head to improve the image quality by controlling the ink landing position to be a straight line. An image recording apparatus is provided.

  The image recording apparatus of the present invention includes a plurality of print heads in which nozzle rows are formed along the sub-scanning direction by a plurality of nozzles that eject ink, and the nozzle rows are provided in at least two or more rows in the main scanning direction, In an image recording apparatus that has a band memory for storing line order data and an image memory for storing ejection data to be shifted into the print head, and records an image on a recording medium, the main scanning direction between the nozzle rows When the distance is longer than the inter-dot distance based on the printing resolution, the nozzle included in the head nozzle row in the traveling direction of the print head is instructed to eject the ink for each inter-dot distance. Between the generation of the first timing signal and the ejection timing of the ink indicated by the first timing signal, the other timing signals are output. A timing generation means for generating a second timing signal for instructing the timing for ejecting the ink from the ink row; and when the ejection data is stored in the image memory, the head for the nozzles of the nozzle row N-th data (N is a positive integer) of the line order data stored in the band memory is stored as discharge data, and the line order is used as the discharge data for the nozzles in the other nozzle row. Storage means for storing the (N + 1) th data, and discharging the discharge data stored in the image memory based on the first timing signal from the nozzles of the head nozzle row, Based on the second timing signal, the discharge data stored in the image memory is discharged from the nozzles of the other nozzle row. Characterized in that it.

  By improving the ink landing position accuracy, high-quality image formation can be performed.

FIG. 1 is a diagram illustrating the nozzle surface and nozzle arrangement of the print head. FIG. 2 is a diagram illustrating the discharge timing of the nozzle row. FIG. 3 is a detailed block diagram of a portion for shifting data into the print head. FIG. 4 is a block diagram showing the configuration of the image recording apparatus.

An embodiment of the present invention will be described.
FIG. 1 is a diagram illustrating the nozzle surface and nozzle arrangement of the print head. In the print head, the L row and the R row are bonded together. The No. 1 nozzle 1 in the L row belongs to the A row 5 in the L row, and the nozzles are arranged obliquely in order from there on the paper. The second nozzle belongs to the B row 6 and the third nozzle belongs to the C row 7. Thereafter, this arrangement is repeated, and the No. 512 nozzle 2 belongs to the B row 6. The first nozzle is arranged in the R row from the direction opposite to the L row by 180 degrees. The first nozzle 4 in the R row belongs to the A row 5, the second nozzle belongs to the B row 6, and the third nozzle belongs to the C row 7. No. 512 nozzle 3 in the R row belongs to the B row. The distance 8 between the nozzle rows between the rows A and B and between the rows B and C is a common interval for both the rows L and R. When the print head moves in the direction of the L row during printing, the L row ejects ink in the order of the A row 5, the B row 6, and the C row 7. In the R row, ink is ejected in the order of the C row 7, the B row 6, and the A row 5. Conversely, when the print head moves in the direction of the R row, the L row performs ink ejection in the order of the C row 7, the B row 6, and the A row 5. In the R row, ink is ejected in the order of A row 5, B row 6, and C row 7. In order for each of the ejected inks to land on a straight line, the movement distance of the carriage is between the A row 5 and the B row 6 in the time from the ejection of the A row 5 to the ejection of the B row 6. It is necessary to be equal to the distance 8 between nozzle rows. However, when high-resolution printing is performed, since the time interval from the ejection of the A row 5 to the ejection of the B row 6 is smaller than the distance 8 between the nozzle rows between the A row 5 and the B row 6, the straight line It is impossible in principle to land on top. The L row and the R row can also be considered as independent print heads.

  FIG. 2 is a diagram illustrating the discharge timing of the nozzle row. Various timing signals are generated based on the output of the linear scale encoder. For example, a dot timing signal in the main scanning direction is output in accordance with the printing resolution. The interval T is a discharge timing period calculated from the carriage moving speed and the printing resolution. For example, when the carriage moving speed is 476.25 mm / sec and the printing resolution is 1440 dpi, T = 37.04 μssec. If ink is ejected at this interval, 1440 dpi can be realized. Since the nozzles are divided into three rows, this cycle is divided according to the set times of Tb and Tc for the nozzles in each row, and A row nozzle discharge timing, B row nozzle discharge timing, and C row nozzle discharge timing are generated. . If it is simply divided into three, the time between the A nozzle ejection timing and the B row nozzle ejection timing, and the time between the B nozzle ejection timing and the C row nozzle ejection timing is 12.35 μssec, and the distance that the carriage moves at this time is 5. 88 μm. The distance 8 between the nozzle rows between rows A, B and B, C in FIG. 1 is about 23.5 μm, and a landing position deviation of 17.62 μm occurs. This 17.62 μm exceeds the adjustment range of the set values of Tb and Tc. On the other hand, the distance between dots of 1440 dpi is 17.64 μm, which substantially matches the landing deviation. That is, after the ejection of the A row, the B row is ejected to the ejection position of the next A row. In order to form adjacent dots on a straight line, it is necessary to set the discharge timing to such an extent that it can be regarded as a straight line after printing. In particular, if the landing position is shifted to 5% or less, more preferably 1% or less, printing is performed. This is preferable because it can be regarded as a back straight line. In other words, when the dot formation interval based on the printing resolution and the carriage moving speed is shorter than the distance between each nozzle row, it is difficult to set the ejection timing of printing properly and it is difficult to print a straight line. On the other hand, it is possible to print a straight line by appropriately setting the discharge timing and the discharge order of the print data. The carriage can be moved at high speed, and higher resolution printing can be performed.

  Therefore, when the carriage moves in the direction of the L row, in the L row, the N + 2nd ejection data is in the A row 5, the N + 1th data is in the B row 6, and the Nth ejection is in the C row 7. If the data is shifted in the R row, the Nth ejection data in the A row 5, the N + 1th data in the B row 6 and the N + 2th ejection data in the C row 7 are shifted in. Will land. Here, N is a positive integer.

  FIG. 3 is a detailed block diagram of a portion for shifting data into the print head. The image data sent in the line order is stored in the band memory 14. When there is a free space in the image data written in the RAM 12, the image data is read from the band memory 14 in the shift-in direction of the print head and read to the RAM 12. Write. The write address is generated by the write address control unit 13. The print data is read from the RAM 12 by the discharge timing generation counter 11 that generates the discharge timing according to the resolution from the main scanning direction dot timing signal generated from the linear scale encoder. The generation of the read address is performed by the read address control unit 15, and the Nth ejection data, the N + 1th ejection data, the N + 2th ejection data, and the reading are sequentially repeated in byte units. When the carriage moves the read three data in the direction of the L row, in the L row, the N + 2nd ejection data is in the A row 5, the N + 1th data is in the B row 6, and the C + 1 is in the C row 7. The head shift is performed so that the Nth ejection data is the Nth ejection data in the A row 5 in the R row, the N + 1th data in the B row 6, and the N + 2th ejection data in the C row 7 in the R row. The in-data selection unit 16 performs selection. The selected ejection data is shifted into the print head 17 to form an image.

  Here, in order to align the dot positions more accurately, a circuit for finely adjusting the nozzle ejection timing signals of the nozzles of the A-line ejection line 5, the nozzles of the B-line ejection line 6, and the nozzles of the C-line ejection line 7 is provided. This is because the print head has individual differences and the actual dot position is slightly different, so that the ejection timing is finely adjusted so that the dot position matches the ideal position. The positional deviation also occurs depending on the ejection method according to the dot size. Accordingly, the discharge timing generation counter 11 includes a storage circuit that stores in advance data indicating how much the nozzle discharge timing signal is advanced or delayed, and an adjustment circuit that inputs the data to advance or delay the discharge timing signal. Add to. For example, although a positional deviation of 0.02 μm theoretically occurs, the actual positional deviation is confirmed by actually discharging. A value for minimizing the positional deviation amount is stored in the storage circuit as data by advancing or delaying the ejection timing in accordance with the positional deviation amount. Then, an ejection timing signal corresponding to the data is generated.

FIG. 4 is a block diagram showing the configuration of the image recording apparatus.
The control unit 22 is a control unit that controls the entire image recording apparatus. For example, the control means 22 is a CPU. The ROM 21 is a storage unit that stores an operation program and data of the control unit 22. The control unit 22 controls each unit according to the operation program stored in the ROM 21. That is, the control unit 22 controls the main scanning direction writing unit 24, the sub scanning direction reading unit 26, the mask processing unit 28, the write address control unit 13, and the read address control unit 15.

  The print data is sent to the USB interface 23 as line order data. The data is written in the band memory 14 by the main scanning direction writing unit 24 in the line order. The sub-scanning direction reading unit 26 checks the free capacity of the RAM 12 included in the carriage unit 29, and reads data from the band memory 14 in the direction shifted to the print head 17 (sub-scanning direction) if writing is possible. In accordance with the read data and the mask information written in the mask memory 27, mask processing is performed by the mask processing unit 28, and image data is written to the RAM 12. The control of the address written to the RAM 12 is automatically generated by the write address control unit 13 by looking at the flow of data written to the RAM 12. As for the ejection data, the Nth ejection data, the N + 1th ejection data, and the N + 2th ejection data are read in byte units by the read address control unit 15, and the N, N + 1, N + 2 data is read by the head shift-in data selection unit 16. Then, data is selected according to the nozzle position and a shift-in operation is performed on the print head 17.

  The head shift-in data selection unit 16 also supports 2 bit / dot variable dots. When forming dots on a recording medium, one nozzle is driven twice in succession to eject ink, thereby increasing the amount of ink to be ejected and forming large dots. At this time, as data indicating whether the nozzle is driven once or twice, 2 bits are used for one dot on the RAM 12. In addition, 4-stage driving conditions can be theoretically indicated by 2-bit data. In this way, it is possible to deal with a plurality of dot sizes.

  The present invention can be used for an image recording apparatus.

1 L row 1 nozzle 2 L row 512 nozzle 3 R row 512 nozzle 4 R row 1 nozzle 5 A row discharge line 6 B row discharge line 7 C row discharge line 8 Nozzle row distance

Claims (6)

A band memory for storing line sequence data by mounting a plurality of print heads in which at least two nozzle rows are formed in the main scanning direction, in which nozzle rows are formed by a plurality of nozzles that eject ink along the sub-scanning direction. And an image recording device that stores image data on a recording medium, and having an image memory that stores ejection data to be shifted into the print head.
When the distance in the main scanning direction between the nozzle rows is longer than the inter-dot distance based on the printing resolution,
Generation of a first timing signal for instructing the timing of ejecting the ink for each of the inter-dot distances to the nozzles included in the head nozzle row in the traveling direction of the print head, and the first timing Timing generating means for generating a second timing signal for instructing the timing of ejecting the ink from the other nozzle row during the timing of ejecting the ink indicated by the signal;
When storing the discharge data in the image memory, the N (N is a positive integer) th of the line sequence data stored in the band memory as the discharge data for the nozzles of the head nozzle row Storage means for storing (N + 1) th data of the line order data as the ejection data for the nozzles of the other nozzle row,
Have
Discharging the discharge data stored in the image memory based on the first timing signal from the nozzles of the top nozzle row;
An image recording apparatus, wherein the ejection data stored in the image memory is ejected from the nozzles of the other nozzle row based on the second timing signal. The print head includes three nozzle rows, and the nozzle rows are arranged at equal intervals in the main scanning direction.
The timing generation unit outputs a third timing signal indicating the timing of ejecting the ink from the other nozzle row after the timing of ejecting the ink by the second timing signal. A signal, the second timing signal, and the third timing signal are generated so that the ink discharge timings indicated by the third timing signal are equally spaced;
When storing the discharge data in the image memory, the storage means stores the N + 2th data of the line sequence data as the discharge data for the nozzles of the further nozzle row,
The image recording apparatus according to claim 1, wherein the ejection data stored in the image memory is ejected from the nozzles of the other nozzle row based on the third timing signal.   A dot formed by the ink ejected by the first timing signal and a dot formed by the ink ejected by the second timing signal are formed adjacent to each other on a straight line in the sub-scanning direction. The image recording apparatus according to claim 1, wherein: The print head can vary the ink discharge amount by being driven continuously multiple times,
2. The image memory according to claim 1, wherein 2 bits are assigned as data for forming one dot, and a value corresponding to the ejection amount of the ink ejected from the nozzle is stored as the ejection data. 4. The image recording apparatus according to any one of items 3.   The timing generation means includes: a first adjustment circuit that shifts the first timing signal for a first predetermined time; a second adjustment circuit that shifts the second timing signal for a second predetermined time; A storage circuit for storing the first predetermined time and the second predetermined time; the first timing signal shifted in the first predetermined time stored in the storage circuit; and the storage circuit 5. The image recording apparatus according to claim 1, wherein the second timing signal shifted in the second predetermined time is stored in the image recording apparatus.   The timing generation means includes: a first adjustment circuit that shifts the first timing signal for a first predetermined time; a second adjustment circuit that shifts the second timing signal for a second predetermined time; A third adjustment circuit for shifting the third timing signal for a third predetermined time; and a memory circuit for storing the first predetermined time, the second predetermined time, and the third predetermined time. The first timing signal shifted in the first predetermined time stored in the storage circuit and the second timing signal shifted in the second predetermined time stored in the storage circuit 3. The image recording apparatus according to claim 2, wherein the third timing signal shifted by the third predetermined time stored in the storage circuit is generated.

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