JPWO2008153134A1 - Recording apparatus and control method thereof - Google Patents

Abstract

There is provided a recording apparatus 1a having a first line head unit (10) and a second line head unit (20). The first line head unit (10) includes first recording heads (11a to 11e), and a part of the recordable area of the first recording heads (11a to 11e) adjacent to each other overlaps. 1 region and a second region where the first recording heads (11a to 11e) do not overlap. The second line head unit 20 includes second recording heads (21a to 21d), and a third recording head is overlapped with a part of the recordable area of the second recording heads (21a to 21d) adjacent to each other. And a fourth region where the second recording heads (21a to 21d) do not overlap. The first and second line head units 10 and 20 are arranged such that the first area faces a part of the fourth area and the third area faces a part of the second area. Yes.

Description

  The present invention relates to a recording apparatus suitable for an inkjet printer or the like and a control method thereof.

  An inkjet line printer using a line head provided with a large number of recording elements so as to correspond to the entire width of the recording medium has been studied. As the line head, a line head composed of a long recording head having a length corresponding to the entire width of the recording medium and a short recording head shorter than the long recording head are arranged in the width direction (scanning direction) of the recording medium. A line head arranged along the line is known. Japanese Laid-Open Patent Publication No. 2000-62148 (hereinafter referred to as Document 1) discloses a recording apparatus using a long head. Japanese Laid-Open Patent Publication No. 2002-144542 (hereinafter referred to as Document 2) and Japanese Laid-Open Patent Publication No. 2006-305763 (hereinafter referred to as Document 3) use a line head in which a plurality of short heads are arranged in one direction. An apparatus is disclosed. In many cases, a line head formed by arranging a plurality of short heads in one direction has a plurality of short heads arranged in a staggered pattern in the scanning direction.

  Since the long head has a structure having a large number of recording elements, the yield during manufacture is poor and the manufacturing cost tends to be high. In addition, a recording apparatus using a long head has a high maintenance cost because the long head must be replaced by a unit even if some recording elements are defective. Further, as described in Document 1, in a recording apparatus using a long head, the recording position is likely to be displaced due to variations in manufacturing. In Document 1, in order to correct the positional deviation of the recording position, the ink ejection timing for each nozzle is delayed so as to cancel out the positional deviation of the nozzle, but a mechanism for delaying the ink ejection timing for each nozzle. Is expected to be a complex mechanism.

  A line head in which a plurality of short heads are arranged in one direction has a better yield at the time of manufacturing and can suppress manufacturing costs compared to a line head made of long heads. In addition, when a problem occurs in some of the recording elements, only the corresponding short head needs to be replaced, so that there is an advantage that maintenance costs can be suppressed. However, in a recording apparatus using a line head in which a plurality of short heads are arranged in one direction, stripe-shaped density unevenness, white stripes, dark stripes, and the like are likely to occur at a portion corresponding to the joint of each short head. . Therefore, in a line head in which a plurality of short heads are arranged in one direction and a recording apparatus using the same, it is required to improve the recording quality of a portion corresponding to the joint of each short head.

  Document 2 discloses a line head and an image recording method used therefor for improving color / density unevenness. Document 3 discloses a method for adjusting a recording apparatus in order to suppress quality degradation such as discontinuity and color misregistration.

  For a recording apparatus using a line head (line head unit) in which a plurality of short heads are arranged in one direction, the quality of the portion corresponding to the joint of each short head is improved as in Reference 2 and Reference 3, etc. Various means aimed at have been proposed. Nevertheless, density unevenness may occur in the portion corresponding to the joint of each short head, and further improvement is required.

  For example, in a line head including a plurality of recording heads (short heads) arranged in one direction, the recording heads are arranged in one direction so that a part of the recordable area of adjacent recording heads overlaps. In a printer including such a line head, a short head that is responsible for recording is switched at a random position in an overlapping region, and the recording is performed as a seam. By performing such recording, streaky density unevenness (density unevenness), white streaks, dark streaks, and the like are made inconspicuous. However, even if a part of the recordable area of the recording heads adjacent to each other is overlapped, a recording (printing) trouble such as density unevenness or color misregistration may occur in a part corresponding to the overlapping area serving as a joint. is there. These lead to deterioration of recording quality. This density unevenness, color misregistration, and the like can be dispersed to some extent by making the joints (switching points) of the short heads random within the overlapping region. However, the width of the overlapping area is limited. For this reason, it is difficult to effectively suppress density unevenness and color misregistration that affect the quality of output, for example, output (printed) on paper.

  On the other hand, a recording apparatus using a line head (one-pass recording apparatus) performs recording while moving a short head in a scanning direction (a direction orthogonal to the recording medium conveyance direction) (multi-pass recording). Compared to a device, there is an advantage that recording can be performed at a high speed on a recording medium. For this reason, a recording apparatus using a line head (one-pass recording apparatus) is expected to be capable of recording at higher speed.

  One embodiment of the present invention is a recording apparatus that includes a feeder that is a means for conveying a recording medium in a first direction, a first line head unit, and a second line head unit. The first line head unit includes a plurality of first recording heads each including a recordable area provided with a plurality of nozzles for discharging droplets, and the plurality of first recording heads are adjacent to each other. They are arranged side by side along a second direction that intersects the first direction so that a part of the recordable area of one recording head overlaps. The second line head unit includes a plurality of second recording heads each including a recordable area provided with a plurality of nozzles for discharging droplets, and the plurality of second recording heads are adjacent to each other. The two print heads are arranged side by side along the second direction so that a part of the printable area overlaps. In this recording apparatus, the first line head unit includes a first area in which a part of the recordable area of the first recording heads adjacent to each other overlaps and a first area in which the first recording head does not overlap. The second line head unit includes a third area in which a part of the recordable area of the second recording heads adjacent to each other overlaps with a second recording head. And no fourth region. In the first line head unit and the second line head unit, the first area faces a part of the fourth area, and the third area faces a part of the second area. Is arranged.

  The first line head unit and the second line head unit of this printing apparatus are a first area (one of recordable areas of the first print heads adjacent to each other) that is an overlapping area of the first line head unit. The first area where the portions overlap each other and the fourth area which is the non-overlapping area of the second line head unit (the fourth area where the second recording head does not overlap) face each other. Placed in. Further, the first line head unit and the second line head unit include a third area (a part of the recordable area of the second recording head adjacent to each other) that is an overlapping area of the second line head unit. The third area overlapping) and the second area which is the non-overlapping area of the first line head unit (second area where the first recording head does not overlap) are arranged to face each other. Is done.

  According to this recording apparatus, one line (scanning line) can be recorded by using two line head units and switching the line head unit responsible for recording at random positions. In addition, the number of switching points and / or switching point selection conditions can be set, and the line head unit responsible for recording can be switched at random positions so as to satisfy this. In addition, since the line head units can be switched at random positions, the switching points in each line can be distributed within the range of the line width. Therefore, according to this recording apparatus, factors that may cause recording quality deterioration such as density unevenness and color misregistration that may occur at individual switching points can be dispersed within the range of the line width. For this reason, even if density unevenness or color misregistration occurs at individual switching points, streak-like density unevenness, white streaks, dark streaks, etc. that degrade the recording quality are difficult to see and good. High quality records.

  In this recording apparatus, the seam can be randomly selected within the range of the width of the line head by changing the charge of recording between the plurality of line head units (first to fourth areas). In order to record information (data) of a certain scanning line, in each line head unit, the responsibility for recording is changed between the recording heads. A seam may be generated in an area where the recording heads overlap (first and / or third area), or a seam may be generated while avoiding the first area and the third area. For example, when recording a portion corresponding to the first area that is the overlapping area of the first line head unit, recording is performed using the fourth area that is the non-overlapping area of the second line head unit, When recording a portion corresponding to the third area that is the overlapping area of the second line head unit, recording can be performed using the second area that is the non-overlapping area of the first line head unit. It is possible to prevent the seams from concentrating on a narrow and limited area of the overlapping area, and to suppress the fact that the recording quality deterioration factor substantially affects the recording quality.

  According to this recording apparatus, the entire recordable area of the first line head unit and the entire recordable area of the second line head unit can be selected, the number of switching points is set, and random One line can be recorded while switching the head unit responsible for recording at the position. In this case, the duty (efficiency, operating rate) of each of the first and second line head units can be halved compared to the conventional one. Therefore, it is possible to reduce the load applied to each recording head, and it is possible to suppress the possibility of occurrence of other factors that lead to deterioration in recording quality, such as heat generation due to driving of each recording head and imbalance in ink supply. Therefore, higher quality recording is possible.

  According to this recording apparatus, in recording where the recording quality is not a problem as in the case of trial printing in a printer (recording apparatus), two line head units are used simultaneously (in parallel), and the two line head units are used. Two lines can be recorded simultaneously. When used in this way, higher-speed recording can be realized. Therefore, the range of functions that can be selected by the user, such as speed-oriented and quality-oriented, is expanded.

  Another embodiment of the present invention is a recording head. The recording head includes a first line head including a plurality of first recording heads each including a recordable area provided with a plurality of nozzles for discharging droplets, and a plurality of nozzles for discharging droplets. And a second line head including a plurality of second recording heads each including the recorded recordable area. In the first line head, a plurality of first recording heads are arranged side by side in one direction so that a part of the recordable area of the first recording heads adjacent to each other overlaps. In the second line head, the plurality of second recording heads are arranged side by side in one direction so that a part of the recordable area of the second recording head adjacent to each other overlaps. In this recording head, the first line head unit does not overlap the first recording head with the first area where a part of the recordable area of the first recording heads adjacent to each other overlaps. The second line head unit includes a second area, and the second recording head overlaps the third area where a part of the recordable area of the second recording head adjacent to each other overlaps. And a fourth region that is not. In the first line head unit and the second line head unit, the first area faces a part of the fourth area, and the third area faces a part of the second area. Is arranged.

  In the recording apparatus and the recording head, the plurality of first recording heads of the first line head unit and the plurality of second recording heads of the second line head unit are, for example, all in the same shape. Can do. In this case, the plurality of first recording heads and the plurality of second recording heads are preferably arranged at an equal pitch. The first line head unit and the second line head unit are preferably arranged so as to be shifted by approximately ½ pitch. The recording apparatus and the recording head can be realized relatively simply without preparing a plurality of types of recording heads (short heads). However, in this case, there is a possibility that a recordable area that can be recorded but is not used for recording on the recording medium remains at the end of the first line head unit and / or the end of the second line head unit. is there. Such a recordable area can be used for recording on a recording medium having a slightly different width such as a legal size with respect to the A4 size.

  In the recording apparatus and the recording head, the plurality of first recording heads of the first line head unit have the same shape and a plurality of first type recording heads arranged at an equal pitch, and the first type recording head. And a second type recording head having a size approximately half that of the head. In this case, the plurality of second recording heads of the second line head unit are each a first type recording head, and are preferably arranged at an equal pitch. The first line head unit and the second line head unit are preferably arranged so as to be shifted by approximately ½ pitch. This is a preferred example for realizing the recording apparatus and the recording head in which there is no recordable area that is not used for recording on the recording medium.

  The recording apparatus further includes a first line buffer corresponding to the first line head unit, a second line buffer corresponding to the second line head unit, and data for recording one line in the first line buffer. It is preferable to have a control unit including a function of randomly distributing the line buffer and the second line buffer. The control unit randomly assigns data for recording one line (scan line) to the first line buffer and the second line buffer. In order to record the line on the recording medium, the first line head unit records the data of the first line buffer on the recording medium, and the second line head unit records the data of the second line buffer on the recording medium. Record. Thereby, it is possible to obtain an output (recording result) in which the joints between the first line head unit and the second line head unit are randomly distributed with the line width.

  According to this recording apparatus, when data such as an image is recorded (printed) on one recording medium, the data of each scanning line is recorded at random positions (various switching points). The first line head unit is switched to the second line head unit, and the second line head unit is switched to the first line head unit (changed). For this reason, the seams (switching points, recording transition positions) are randomly distributed within the scanning line width in units of scanning lines, and good recording quality can be obtained.

Yet another embodiment of the present invention is a method for controlling a recording apparatus by a control unit. The method includes the following steps.
(A) Data for recording one line is randomly distributed to the first line buffer and the second line buffer, and the first line head unit and / or the second line head is based on the distributed data. Record one line by unit.

  According to this method, data for recording one line is randomly distributed to the first line buffer and the second line buffer, and based on the distributed data, the first line head unit and / or the first line buffer is recorded. One line is recorded by two line head units. For this reason, the switching points (recording transition positions) that become seams can be dispersed.

It is desirable that recording (step (a)) further includes the following steps.
(A1) The (n + i) th line is recorded by the first line head unit based on data randomly selected from the data for recording the (n + i) th line.
(A2) Recording the nth line by the second line head unit based on unrecorded data among the data for recording the nth line.

  In this method, a part of one line, for example, the nth line, is recorded by the first line head unit, and then the other part is recorded by the second line head unit. That is, in this control method, one line is recorded at different timings by a plurality of line head units. Different lines may be partially printed in parallel (simultaneously) by a plurality of line head units. That is, although the step (a2) may be performed after the step (a1), the step (a2) may be performed simultaneously with the step (a1).

  Yet another embodiment of the present invention is a program for causing a computer to function as a control unit that controls the recording apparatus. The program randomly distributes data for recording one line to the first line buffer and the second line buffer by the control unit, and based on the distributed data, the first line head unit and / or the second line buffer. This includes recording one line (scanning line) at different timings by two line head units.

1 shows a schematic configuration of a recording apparatus according to a first embodiment. 1 shows a schematic configuration of a first line head unit and a second line head unit. A part of 1st line head unit is expanded and shown. 2 shows a schematic configuration of a control system of the recording apparatus of FIG. It is a figure which shows the 1st mode of high-speed recording, Comprising: An example of the operation area | region (droplet application | coating area | region) of a 1st line head unit and a 2nd line head unit is shown. 6A and 6B schematically show the second mode of high speed and high quality. FIGS. 7A to 7C schematically show a third mode for recording with high quality. FIG. 8A is a flowchart showing a control method when the (n + i) th line is printed by the first line head unit. FIG. 8B is a flowchart showing a control method when the n-th line is printed by the second line head unit. 2 shows a schematic configuration of a recording apparatus according to a second embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

  FIG. 1 shows a schematic configuration of a recording apparatus according to the first embodiment of the present invention. The recording apparatus 1a is an ink jet type line printer, and performs recording (printing) on a recording paper (sheet) P as a recording medium. The printer 1a of this example is capable of printing up to A3 size (length 420 mm × width 297 mm) recording paper P, and scans to correspond to the entire area (full width) of the width (297 mm) of A3 size recording paper P. A recording head (line head) 30 extending in the direction (paper width direction, second direction) Y and the recording paper P are conveyed in a direction (conveyance direction, sub-scanning direction, first direction) X that intersects the scanning direction. A transport device (feeder) 40 and a control board (motherboard, computer) 50 mounted with a CPU or microcomputer functioning as a control unit are provided.

  The transport device 40 includes a pair of belt drive drums (rollers) 41a and 41b, a transport belt 42 that is stretched between the belt drive drums 41a and 41b and transports the recording paper P in the transport direction X, and one belt drive drum. A transport motor 43 that drives the transport belt 42 is provided via 41b. A rotation shaft 43a of the transport motor 43 is connected to the belt drive drum 41b. The recording head 30 is disposed above the conveyance belt 42, and the recording paper P passes between the recording head 30 and the conveyance belt 42. In this example, the recording head 30 and the conveyance device 40 are arranged so that the conveyance direction (first direction) X and the scanning direction (second direction) Y are orthogonal to each other.

  The printer 1a of this example is a color printer, and the recording head 30 includes a yellow line head unit 30Y corresponding to a yellow recording color, a magenta line head unit 30M corresponding to a magenta recording color, and a cyan recording head. A cyan line head unit 30C corresponding to the recording color and a black line head unit 30K corresponding to the black recording color are provided. Each color line head unit 30Y, 30M, 30C, 30K includes a first line head unit 10 including a plurality of first recording heads 11a, 11b, 11c, 11d, and 11e, and a plurality of second recording heads. And a second line head unit 20 including 21a, 21b, 21c, and 21d. In this example, the five first recording heads 11a to 11e and the four second recording heads 21a to 21d are all recording heads (short heads) having the same shape.

  FIG. 2 shows a more detailed configuration of each line head unit, taking the black line head unit 30K as an example. The line head unit 30 </ b> K includes a first line head unit (line head) 10 and a second line head unit (line head) 20. FIG. 3 is an enlarged conceptual view of a part of the first line head unit 10 included in the black line head unit 30K. 2 and 3 show the black line head unit 30K as an example, but the schematic configurations of the yellow line head unit 30Y, the magenta line head unit 30M, and the cyan line head unit 30C are the same. . In FIG. 3, a part of the first line head unit 10 is shown enlarged, but the second line head unit 20 has the same schematic configuration. This will be described in more detail with reference to FIGS.

  The first line head unit 10 includes five first recording heads 11a to 11e each including a recordable area A provided with a plurality of nozzles N for discharging droplets. These first recording heads 11a to 11e are all recording heads (short heads) having the same shape. Each of the first recording heads 11a to 11e includes a piezoelectric element as a recording element, and ejects ink droplets from a plurality of nozzles N by a plurality of piezoelectric elements.

  Each of the first recording heads 11a to 11e is one structure in which a plurality of nozzles N are assembled. Each of the first recording heads 11 a to 11 e includes attachment areas C provided at both ends of the recordable area A. In the attachment area C, there are provided attachment holes 12 for fixing the recording heads directly or indirectly to the chassis of the printer 1a. Due to the mounting area C, these first recording heads 11a to 11e cannot physically be arranged so that the recordable areas A of the respective heads are continuous in a straight line without a gap. In order to suppress discontinuity in recording (printing) of the connection portion (connection portion), these first recording heads 11a to 11e are recordable areas of the first recording heads 11a to 11e adjacent to each other. It arrange | positions so that a part (edge part) of A may overlap. That is, the first recording heads 11a to 11e are arranged in a staggered manner along the scanning direction so that a part of the plurality of recording elements (a part of the plurality of nozzles N) overlap.

  These first recording heads 11a to 11e are arranged at equal intervals (pitch PP). The first line head unit 10 includes a first area (overlapping area) B1 in which a part of the recordable area A of the first recording heads 11a to 11e adjacent to each other overlaps, and the first recording head 11a. To 11e include a second region (non-overlapping region) B2 that does not overlap.

  The second line head unit 20 includes four second recording heads 21a to 21d each including a recordable area A provided with a plurality of nozzles N for discharging droplets. These second recording heads 21a to 21d are all recording heads (short heads) having the same shape as the first recording heads 11a to 11e. That is, the second recording heads 21a to 21d include piezoelectric elements as recording elements, and eject a droplet of ink from a plurality of nozzles N by a plurality of piezoelectric elements.

  Each of the second recording heads 21a to 21d also includes attachment areas C provided with attachment holes 22 and the like at both ends of the recordable area A. For this reason, these second recording heads 21a to 21d are also physically unable to be arranged so that the recordable area A is continuous in a straight line. Therefore, in order to prevent discontinuity in recording (printing) of the connection portion (connection portion), these second recording heads 21a to 21d are recorded by the second recording heads 21a to 21d adjacent to each other. It arrange | positions so that a part (edge part) of the possible area | region A may overlap. That is, the second recording heads 21a to 21d are also arranged in a staggered manner along the scanning direction so that a part of the recording elements (a part of the nozzles N) overlap.

  These second recording heads 21a to 21d are also arranged at an equal pitch. Therefore, the second line head unit 20 includes a second area (overlapping area) B3 in which a part of the recordable area A of the second recording heads 21a to 21d adjacent to each other overlaps the second recording head. 4 includes a fourth region (non-overlapping region) B4 where the heads 21a to 21d do not overlap.

  The first line head unit 10 and the second line head unit 20 are arranged to face each other so as to be displaced by approximately ½ pitch (½ PP). That is, in the first line head unit 10 and the second line head unit 20, the first area B1 that is an overlapping area of one line head is a fourth area that is a non-overlapping area of the other line head. The third region B3 that is opposed to a part of the substantially central portion of B4 and that is the overlapping region of the other line head is a part of the substantially central portion of the second region B2 that is a non-overlapping region of the one line head Are arranged to face each other.

  FIG. 4 is a control block diagram of the printer 1a of this example. In FIG. 4, a control system of the black line head unit 30K is shown as an example. The yellow line head unit 30Y, the magenta line head unit 30M, and the cyan line head unit 30C also have the same control system.

  The printer 1 a of this example includes a control device (control board) 50. The control device 50 corresponds to a memory 51 including a program 52 for controlling the printer 1a, a CPU 60 functioning as a control unit, a memory (input buffer) 80 for storing image data, and each line head unit for each color. And a buffer 90 including a line buffer.

  The input buffer 80 is supplied with pixel data 85 that has been bitmapped from a host device such as a personal computer or a printer image control device connected to the host device, and is stored therein. The pixel data 85 includes information for outputting each dot (each pixel) of each color. An image is output by outputting image data 85 serially (sequentially) in the order of scanning lines (lines). In FIG. 4, the bitmap information (pixel data) in the nth row and the (n + i) th row is indicated by data (block data) 81 and 82 that are blocked in units of scanning lines. Note that n and i are integers of 1, 2, 3,. In FIG. 4, the block data 81 in the nth row and the block data 82 in the (n + 1) th row of the image data 80 of one color (eg, black) included in the color (eg, CMYK) are shown for reference.

  The buffer 90 includes a first line buffer (line buffer 1) 91 corresponding to the first line head unit 10 and a second line buffer (line buffer 2) 92 corresponding to the second line head unit 20. Contains. FIG. 4 illustrates the first and second line buffers 91 and 92 corresponding to the black line head unit 30K.

  The control unit 60 includes a random number generation unit 61, a paper feed control unit 62, and a distribution function unit 70. The random number generator 61 is a unit for generating and outputting random numbers by a known method. The distribution function unit 70 is a unit for randomly selecting a switching position between the first line head unit 10 and the second line head unit 20 based on a random number. The paper feed control unit 62 is a unit for controlling the drive of the carry motor 43 of the carry device 40 and feeding the sheet P at a pitch suitable for printing each scanning line by the line head units 10 and 20. .

  The distribution function unit 70 stores data for recording one line, for example, data 81 in the n-th row, into the first line buffer 91 and the second line buffer 92 so as to correspond to the line head units for each color. It has a function to distribute randomly. Explaining the portion related to the black line head unit 30K, the distribution function unit 70 obtains the switching position between the first line head unit 10 and the second line head unit 20 from the random number generator 61. The distribution function unit 70 distributes the data for recording the respective lines of the n-th row and the (n + i) -th row to the first line buffer 91 and the second line buffer 92 based on the switching position. Since the switching position changes randomly in each row, the data is distributed randomly as a result. Further, whether to distribute at each switching position may be determined at random, and the distribution function unit 70 can distribute data more randomly.

  Specifically, a part of the (n + i) -th line is distributed (allocated) to the first line buffer 91 by the distribution operation, and is printed by the first line head 10. At that time, the remaining part of the n-th line (unrecorded part that was not previously printed by the first line head 10) is distributed (allocated) to the second line buffer 92. ), And is printed by the second line head 20. The distribution function unit 70 includes a first selector (selector 1) 71 that selects data to be stored in the first line buffer 91, and a second selector (selector 2) that selects data to be stored in the second line buffer 92. ) 72, a first selector control unit 70 a that controls the first selector 71, and a second selector control unit 70 b that controls the second selector 72. Although not shown, the distribution function unit 70 also includes a first selector and a second selector that correspond to the line head units 30Y, 30M, and 30C for each color for the line head units 30Y, 30M, and 30C for other colors. , A first selector control unit, and a second selector control unit.

  The program 52 stored in the memory 51 is loaded into the CPU 60 and causes the CPU 60 to function as a control unit. The control unit 60 implemented by the program 52 has a function of randomly distributing data for recording one line for each color to the first line buffer 91 and the second line buffer 92 at different timings. including. The control unit 60 further includes a function of recording one line at different timings by the first line head unit 10 and / or the second line head unit 20 based on the distributed data. More specifically, the control unit 60 has a function of recording the (n + i) th line by the first line head unit 10 based on data randomly selected from the data for recording the (n + i) th line. And a function of recording the nth line by the second line head unit 20 based on unrecorded data among the data for recording the nth line.

  Typically, the control unit 60 includes a plurality of short recording heads arranged in a zigzag manner in the scanning direction Y and shifted in the sub-scanning direction X in each of the line head units 10 and 20. Functions 11a to 11e and 21a to 21d include a function for recording one line. In each of the line head units 10 and 20 in which these short heads are combined, a control function for recording one line is known from the above cited references and the like. Accordingly, in this specification, the individual line head units 10 and 20 are described as being combined with a short head, but can be controlled as one long head.

  In the printer 1a, the first and second line head units 10 and 20 are used, and one line is recorded while switching the line head unit responsible for recording at random positions. Typically, one line is recorded (printed) as follows. Here, taking the case where black is recorded as an example, the explanation will be made assuming that the integers n and i are 1.

  First, according to the random number generated in the random number generation unit 61, the distribution function unit 70 randomly selects a switching position between the first line head unit 10 and the second line head unit 20 for the first row (n = 1). select. The distribution function unit 70 divides a line segment in which the first line head unit 10 is in charge of recording and a line segment in which the second line head unit 20 is in charge of recording based on the switching position information selected by a random number.

  The first selector control unit 70 a uses the first selector 71 to select line segment data for which the first line head unit 10 is responsible for recording from the pixel data 81 in the first row, and stores the line data in the first line buffer 91. Store. At this time, the line segment data stored in the first line buffer 91 is a selected (randomly selected) part of the image data of the first row. Then, based on the line segment data stored in the first line buffer 91, the selected part of the first line is printed by the first line head unit 10.

  It is assumed that the second line head unit 20 is arranged so that the next line (scanning line) of the first line head unit 10 can be printed. When the sheet P is advanced by one line in the sub-scanning direction X by the conveying device 40, the second selector control unit 70b causes the second selector 72 to move the second line head unit 20 from the pixel data 81 in the first row. Is stored in the second line buffer 92. At this time, the line segment data stored in the second line buffer 92 is the remaining (unrecorded) data of the pixel data 81 in the first row and is not stored in the first line buffer 91. .

  At the same time, the distribution function unit 70 switches between the first line head unit 10 and the second line head unit 20 for the second row (i = 1, n + i = 2) based on the random number generated in the random number generation unit 61. Select a position at random. Based on the switching position information, the distribution function unit 70 divides the pixel data 82 in the second row into a line segment in which the first line head unit 10 is in charge of recording, and a line segment in which the second line head unit 20 is in charge of recording. Sort out. By the first selector control unit 70 a, the first selector 71 selects line segment data for which the first line head unit 10 is responsible for recording from the pixel data 82 in the second row, and stores it in the first line buffer 91. Store. At this time, the line segment data stored in the first line buffer 91 is a randomly selected part of the pixel data 82 in the second row. Then, based on the line segment data stored in the first line buffer 91, the selected part of the second row is printed by the first line head unit 10.

  Therefore, in this cycle, the remaining part (unrecorded part) of the first line is printed by the second line head unit 20 and simultaneously (in parallel), the first line head unit 10 performs two lines. A randomly selected part of the eye is printed. By repeating this process, an image is recorded (printed) on the recording paper P.

  The printer 1a of this example can arbitrarily select the following three modes.

  The first mode is a mode (speed priority mode) in which recording at a higher speed than the image quality is selected. FIG. 5 shows an example of recording in this speed priority mode. FIG. 5 schematically shows an example of the operation area (droplet application area) of the first line head unit 10 and the second line head unit 20 with a thick solid line. In recording where the recording quality does not matter much like trial printing, two lines can be recorded in parallel by using two line head units at the same time. In the first mode, every line head unit 10 and 20 records lines (scanning lines) every i rows independently. In this case, all the pixel data of the nth row are stored in the second line buffer 92, and all the pixel data of the (n + i) th row are stored in the first line buffer 91.

  In the first mode, the first area (overlapping area) B1 and the third area (overlapping area) B3 are always used for recording. For this reason, the line printed by the first line head unit 10 has four portions printed in the overlapping region B1, and the line printed by the second line head unit 20 has a portion printed in the overlapping region B3. Three, unless those areas are white.

  The second mode is an image quality and speed priority mode that provides the advantages of both image quality and speed. In the second mode, the duty of each line head unit can be reduced to ½ on average. FIGS. 6A and 6B show examples in which the duty of each line head unit is reduced to ½ on average. FIGS. 6A and 6B schematically show the operation areas (droplet application areas) of the first line head unit 10 and the second line head unit 20 with thick solid lines, respectively. In the second mode, the entire recordable area A of each recording head 11a to 11e of the first line head unit 10 and the recordable area A of each recording head 21a to 21d of the second line head unit 20 are displayed. The entire area can be selected. As for the number of switching points, an appropriate upper limit is set for the number, and the position is selected at random. In the second mode, one line is recorded while switching the head unit responsible for recording at the switching point selected under such conditions.

  FIG. 6A shows an example when the number of switching points is four (when the transition between the line head units is four). FIG. 6B shows an example when the number of switching points is three (when the transition between the line head units is three times). In the second mode, since the line head unit responsible for recording is switched at random positions, density unevenness due to the switching of the line head unit is not noticeable. In the second mode, not only the second region (non-overlapping region) B2 and the fourth region (non-overlapping region) B4, but also the first region (overlapping region) B1 and the third region (overlapping region). ) B3 may also be used for recording. However, the first area (overlapping area) B1 and the third area (overlapping area) B3 are used twice in the example of FIG. 6A and three times in the example of FIG. 6B.

  In the first mode, the number of uses of the overlapping areas B1 and B3 is the number of recording heads (short heads) minus one. On the other hand, in the second mode, the use probabilities of the first region B1 and the third region B3 can be reduced to about ½ on average. Therefore, it is difficult to show print quality deterioration such as density unevenness due to the use of the overlapping area B1 of the first line head unit 10 and the overlapping area B3 of the second line head unit 20, and the recording quality can be improved.

  In the second mode, there are 3-4 transitions between the line head units 10 and 20, and in these transitions, there is a possibility that print quality degradation will occur. However, the transition between the line head units 10 and 20 is not limited in area. For this reason, even if a factor that leads to print quality degradation occurs due to the transition between the line heads, the location of the transition is distributed over all the images or all the pages, so that the degradation of the recording quality can be suppressed.

  In the second mode, one line is further printed by the line head units 10 and 20 at different timings. Therefore, the average duty of the line head units 10 and 20 is halved (50%). For this reason, the heat generation of the line head units 10 and 20 can be suppressed, and the ink state can also be suppressed from becoming unstable. In the second mode, it is possible to suppress a decrease in print quality due to the above. In the second mode, the duty is also reduced in the driver circuits (drive circuits) (not shown) of the line head units 10 and 20. As a result, the energization time is reduced and the occurrence of problems due to heat generation can be prevented.

  In the second mode, the duty of the line head units 10 and 20 can be increased to 100% by matching the number and position of switching points for each i row. Thereby, the printing speed of an image can be doubled. Since the positions of the transition between the line head units 10 and 20 can be distributed in a random manner in the width direction, a recording apparatus with high output speed and good recording quality can be provided.

  Further, in the printer 1a, a plurality of nozzles are arranged at the same printing position for each color. In an inkjet line printer, there is a possibility that a failure due to nozzle clogging may occur. When only one nozzle is arranged at the same printing position, when a failure due to clogging occurs, dots corresponding to the nozzle are not printed unless clogging is eliminated, leading to significant quality degradation. In this printer 1a, even if clogging occurs in one nozzle of one line head unit, it is possible to perform printing instead of the nozzles of another line head unit by performing appropriate control. . Therefore, in the printer 1a, clogging of the nozzles can be prevented from becoming a fatal failure. In this printer 1a, even if nozzle clogging occurs, it is possible to prevent the operating rate of the printer from being remarkably lowered and the printing quality from being significantly deteriorated until it is repaired later.

  FIGS. 7A to 7C show a third mode for recording with higher quality. FIGS. 7A to 7C schematically show the operation areas (droplet application areas) of the first line head unit 10 and the second line head unit 20 by thick solid lines, respectively. The third mode is an image quality priority mode, and printing is performed without using the first areas B1 and B3, which are overlapping areas of the line head units 10 and 20, respectively. Therefore, when recording a portion corresponding to the first area B1 that is the overlapping area of the first line head unit 10, the fourth area B4 that is the non-overlapping area of the second line head unit 20 is selected. Is done. When recording a portion corresponding to the third area B3 that is the overlapping area of the second line head unit 20, the second area B2 that is the non-overlapping area of the first line head unit 10 is selected. Is done. Such selection is interpreted by limiting the random number generated by the random number generator 61. Alternatively, the random number is requested one after another until a random number matching the restriction (selection) is obtained.

  FIG. 7A is an example when the number of switching points is six (when the transition between line head units is six times). FIG. 7B is an example when the number of switching points is 7 (when the transition between the line head units is 7 times). FIG. 7C is an example when the number of switching points is eight (when the number of transitions between line head units is eight). In the third mode, printing is not performed in the first area B1 and the third area B3. Therefore, printing is not performed in the overlapping areas B1 and B3, and in the overlapping areas B1 and B3, there is no transition between the recording heads 11a to 11e and the recording heads 21a to 21d. For this reason, there is no transition in a limited area of the overlapping areas B1 and B3, and there is no possibility that the quality deterioration in printing (according to the switching point) will appear.

  Transitions (switching points) between the line head units 10 and 20 can be distributed over the entire area in the width direction of the recording paper P, excluding the first area B1 and the third area B3. The entire image to be printed on the recording paper P can be recorded in the second area (non-overlapping area) B2 and the fourth area (non-overlapping area) B4 where good recording quality can be obtained. For this reason, even if a printing failure (density unevenness or the like) due to switching between the line head units 10 and 20 occurs, it can be dispersed over a wide range. Therefore, high quality recording without density unevenness can be performed.

  Also in the third mode, one line is printed by the line head units 10 and 20 at different timings. That is, the average duty of the line head units 10 and 20 is almost half (50%). Similarly to the second mode, the heat generation of the line head units 10 and 20 can be suppressed, and the ink state can also be suppressed from becoming unstable. Therefore, it is possible to suppress a decrease in the quality of the printed image.

  If the duty of the line head units 10 and 20 can be increased to nearly 100%, the image printing speed can be doubled. However, the portion of the second area B2 of the first line head unit 10 corresponding to the third area B3 of the second line head unit 20 is always used for printing. Further, a portion of the fourth area B4 of the second line head unit 20 corresponding to the first area B1 of the first line head 10 is always used for printing. However, since the portions that are always used for printing are limited to only a small part of the line head units 10 and 20, the occurrence of factors such as heat generation that lead to deterioration in printing quality is greatly suppressed.

  FIG. 8A is a flowchart illustrating an example of a control method when the first line head unit 10 prints the (n + i) th row ((n + i) line, (n + i) th line). FIG. 8B is a flowchart illustrating an example of a control method for printing the nth row (nth line, nth line) by the second line head unit 20.

  In the process of FIG. 8A, first, in step 110, pixel data in the (n + i) th row is selected. In step 111, line segment data to be recorded by the first line head unit 10 is selected from the pixel data in the (n + i) th row. In step 112, the selected line segment is recorded (printed) using the first line head unit 10. In step 113, if there is no next line to be processed, the job is terminated.

  In the process of FIG. 8B, the remaining line segments that are not printed by the first line head unit 10 are printed by the second line head unit 20. First, in step 120, data in the nth row is selected. In step 121, the remaining (unrecorded) line segment data that is recorded by the second line head unit 20 is selected from the pixel data of the nth row. In step 122, the second line head unit 20 records (prints) the remaining line segments. In step 123, if there is no next line to be processed, the job is terminated. 8B (steps 120 to 123) may be performed in parallel with the processing of FIG. 8A (steps 110 to 113), and before and after steps 110 to 113. You may go.

  As described above, according to the recording head 30 of the present embodiment and the printer 1a including the recording head, it is possible to record (print) an image with good quality or record (print) an image at high speed. Further, according to the printer control method and the program 52 of this example, an image can be recorded (printed) with good quality.

  FIG. 9 shows a schematic configuration of a recording apparatus according to the second embodiment of the present invention. The recording apparatus 1b can record (print) an image with good quality or record (print) an image at high speed. Further, in the line head of the recording apparatus (line printer) 1b, there is no recordable area A that is not used for recording on the recording paper P. In the above-described line printer 1a, the recording head 30 is composed of one type of short head. The line printer 1a does not require a plurality of types of recording heads (short heads). However, in the line printer 1a, a part of the first line head unit 10, that is, a part of the first recording heads 11a and 11e can be recorded, but is not used for recording the recording paper P.

  In the recording apparatus (ink-jet line printer) 1b of FIG. 9, the first three recording heads 11b to 11d in the middle are the first type recording heads having the same shape and arranged at an equal pitch. The two first recording heads 11a and 11e at both ends are second type recording heads having a size approximately half that of the first type recording head. The four second recording heads 21a to 21d of the second line head unit 20 are each a first type recording head and are arranged at an equal pitch. The first line head unit 10 and the second line head unit 20 are arranged so as to be shifted by approximately ½ pitch. Even in this case, similarly to the first embodiment, it is possible to record (print) an image with good quality or to record (print) an image at high speed. In addition, since there is no recordable area A that is not used for recording on the recording paper P, a compact recording head and printer can be obtained.

  In the above embodiment, the first and second recording heads are short heads each having a piezo element as a recording element. However, the first and second recording heads are not limited to this. Absent. The first and second recording heads include, for example, a recording element that oscillates a diaphragm other than a piezo element and ejects ink with that force, and a recording element that ejects droplets such as ink from a nozzle by applying heat. A plurality of short heads may be used. Further, the number of first recording heads provided in the first line head unit and the length and number of second recording heads provided in the second line head unit can be arbitrarily set. An example of the short head is about 2 to 3 inches in length, but is not limited thereto. The number of the first recording heads provided in the first line head unit and the number of the second recording heads provided in the second line head unit are determined depending on the size of the recording medium on which recording is performed and the recording head used (short length). It may be set in consideration of the size of the head.

  The first and second line head units are not limited to those described above. Each of the first and second line head units includes a plurality of recording heads (short heads) each including a recordable area provided with a plurality of nozzles for discharging droplets, and the plurality of recording heads are mutually connected. What is necessary is just to arrange in one direction so that a part of recordable area | region of an adjacent recording head may overlap. Each of the first and second line head units can be a known line head that is arranged in one direction so that a part of the recordable area of the adjacent recording heads overlaps. Reference can be made to the line heads described in Document 2 and Document 3.

  In the above embodiment, a color printer is described as an example. However, the present invention can also be applied to a monochrome printer or the like. In the above embodiment, the recording head includes the yellow line head unit, the magenta line head unit, the cyan line head unit, and the black line head unit. A line head unit corresponding to a color (for example, black) may be provided, or a line head unit corresponding to an arbitrary plurality of colors may be provided.

  Furthermore, in the above-described embodiment, the printer is described as an example of the recording apparatus. However, the recording apparatus of the present invention is not limited to the printer. The recording apparatus of the present invention can also be applied to a copying machine, a facsimile, and the like. The recording apparatus of the present invention can also be applied as a printing apparatus that replaces an offset printing apparatus or a gravure printing apparatus.

  In the above embodiment, paper (recording paper) is used as the recording medium, but the recording medium is not limited to paper. The recording medium may be a cloth or the like. The recording apparatus of the present invention can be suitably used when recording on a sheet-like medium regardless of the material.

Claims (10)

A feeder for conveying a recording medium in a first direction;
A first line head including a plurality of first recording heads each including a recordable region provided with a plurality of nozzles for discharging droplets, wherein the plurality of first recording heads are adjacent to each other. A first line head unit arranged side by side along a second direction intersecting the first direction so that a part of the recordable area of one recording head overlaps;
A second line head including a plurality of second recording heads each including a recordable area provided with a plurality of nozzles for discharging droplets, wherein the plurality of second recording heads are adjacent to each other. A second line head unit arranged side by side along the second direction so that a part of the recordable area of the two recording heads overlaps,
The first line head unit includes a first area in which a part of the recordable areas of the first recording heads adjacent to each other overlaps, and a second area in which the first recording heads do not overlap. Including
The second line head unit includes a third area where a part of the recordable area of the second recording heads adjacent to each other overlaps, and a fourth area where the second recording head does not overlap. Including
In the first line head unit and the second line head unit, the first area is opposed to a part of the fourth area, and the third area is a part of the second area. The recording device is arranged so as to oppose. In claim 1,
The plurality of first recording heads of the first line head unit and the plurality of second recording heads of the second line head unit have the same shape,
The plurality of first recording heads and the plurality of second recording heads are arranged at an equal pitch,
The recording apparatus, wherein the first line head unit and the second line head unit are arranged so as to be shifted by approximately ½ pitch. In claim 1,
The plurality of first recording heads of the first line head unit have the same shape and a plurality of first type recording heads arranged at an equal pitch, and approximately half of the first type recording heads. A second type recording head of size,
The plurality of second recording heads of the second line head unit are the first type recording heads, and are arranged at an equal pitch,
The recording apparatus, wherein the first line head unit and the second line head unit are arranged so as to be shifted by approximately ½ pitch. The claim 1, further comprising:
A first line buffer corresponding to the first line head unit;
A second line buffer corresponding to the second line head unit;
And a control unit including a function of randomly distributing data for recording one line to the first line buffer and the second line buffer. A method for controlling a recording apparatus according to claim 1, comprising:
The recording device further includes:
A first line buffer corresponding to the first line head unit;
A second line buffer corresponding to the second line head unit,
The method is
Data for recording one line is randomly distributed to the first line buffer and the second line buffer, and the first line head unit and / or the second line is based on the distributed data. Recording a line with the head unit. In claim 5, the recording includes:
Recording the (n + i) th line by the first line head unit based on data randomly selected from the data for recording the (n + i) th line;
recording the nth line by the second line head unit based on unrecorded data of data for recording the nth line. A program for causing a computer to function as a control unit for controlling the recording apparatus according to claim 1,
The recording device further includes:
A first line buffer corresponding to the first line head unit;
A second line buffer corresponding to the second line head unit,
The program is
Data for recording one line is randomly distributed to the first line buffer and the second line buffer, and the first line head unit and / or the second line is based on the distributed data. A program including recording one line by a head unit. A first line head unit including a plurality of first recording heads each including a recordable area provided with a plurality of nozzles for discharging droplets, wherein the plurality of first recording heads are adjacent to each other. A first line head unit arranged in one direction so that a part of the recordable area of the first recording head overlaps;
A second line head unit including a plurality of second recording heads each including a recordable area provided with a plurality of nozzles for discharging droplets, wherein the plurality of second recording heads are adjacent to each other. A second line head unit arranged in one direction so that a part of the recordable area of the second recording head overlaps,
The first line head unit includes a first area in which a part of the recordable areas of the first recording heads adjacent to each other overlaps, and a second area in which the first recording heads do not overlap. Including
The second line head unit includes a third area where a part of the recordable area of the second recording heads adjacent to each other overlaps, and a fourth area where the second recording head does not overlap. Including
In the first line head unit and the second line head unit, the first area is opposed to a part of the fourth area, and the third area is a part of the second area. The recording head is arranged so as to face the head. In claim 8,
The plurality of first recording heads of the first line head unit and the plurality of second recording heads of the second line head unit have the same shape,
The plurality of first recording heads and the plurality of second recording heads are arranged at an equal pitch,
The recording head, wherein the first line head unit and the second line head unit are arranged so as to be shifted by 1/2 pitch. In claim 8,
The plurality of first recording heads of the first line head unit have the same shape and a plurality of first type recording heads arranged at an equal pitch, and half the size of the first type recording heads And a second type recording head.
The plurality of second recording heads of the second line head unit are the first type recording heads, and are arranged at an equal pitch,
The recording head, wherein the first line head unit and the second line head unit are arranged so as to be shifted by 1/2 pitch.

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