JP5832369B2 - Inkjet recording device - Google Patents

Description

  The present invention relates to an ink jet recording apparatus, and more particularly to a technology for reducing variation in dot movement due to landing interference and suppressing image deterioration when pixels are recorded mutually using two nozzle arrays.

  The number of nozzles of the full line head reaches several thousand, and the probability of occurrence of abnormal nozzles increases in proportion to this, and there is a problem that it is difficult to obtain a defect-free image.

  As a technique for solving such a problem, two nozzle rows are provided, half of the image data for one row is recorded in one nozzle row, and the remaining 1 / second pixel is recorded in the other nozzle row. A technique for recording two pixels is known (Patent Document 1).

  According to Patent Document 1, even when there are defective nozzles such as nozzles with different ink discharge directions and nozzles with a small ink droplet discharge amount in one nozzle row, the degree of influence is as follows. Since the ratio of the image data is halved to about 1/2, the influence of defective nozzles is averaged, and image defects can be made inconspicuous. In addition, when there is a non-ejection nozzle in one nozzle row, it is possible to prevent white streaks due to the non-ejection nozzle by complementing and recording with a normal nozzle in the other nozzle row.

  However, in Patent Document 1, each nozzle row is one-dimensionally arranged on a straight line, and there is a limit to the recording resolution. In recent years, an ink jet head in which nozzles are two-dimensionally arranged has become mainstream in order to increase the density of nozzles accompanying higher resolution of recorded images.

  Even in such a full line head in which nozzles are two-dimensionally arranged, there is a problem that it is difficult to obtain a defect-free image due to the occurrence of abnormal nozzles. And an image defect can be reduced by the method of providing a some nozzle row.

  Japanese Patent Application Laid-Open No. 2004-228561 describes a technique for making an image defect inconspicuous by alternately ejecting ink from each nozzle of two nozzle rows in which nozzles are two-dimensionally arranged.

Japanese Patent Laid-Open No. 10-6488 JP 2002-225265 A

  FIG. 22 is a diagram showing an outline of the ink-jet head described in Patent Document 2. As shown in FIG. As shown in the figure, this inkjet head has two nozzle rows, nozzle row A and nozzle row B, and the pressure chambers of each nozzle row are located on the same straight line extending in the paper transport direction. .

  For example, the pressure chamber 221 and the pressure chamber 223 are located on the same straight line in the paper transport direction. The pressure chamber 222 and the pressure chamber 224 are also located on the same straight line in the paper transport direction.

  In Patent Document 2, ink is alternately ejected from nozzles located on the same straight line in the paper transport direction. For example, ink is alternately ejected from nozzles corresponding to the pressure chamber 221 and the pressure chamber 223. Ink is also alternately ejected from the nozzles corresponding to the pressure chamber 222 and the pressure chamber 224.

  Further, each line in the direction orthogonal to the paper transport direction is formed by alternately ejecting ink from the nozzles in the nozzle row A and the nozzles in the nozzle row B.

  Therefore, assuming that the dots 211 shown in FIG. 22 are formed by being ejected from the nozzles corresponding to the pressure chambers 221 belonging to the nozzle row A, the dots 212 adjacent to the dots 211 in the direction orthogonal to the paper transport direction are It is formed by being discharged from the pressure chamber 223 belonging to the nozzle row B.

  The difference in landing time between the dot 211 and the dot 212 is determined by the interval between the two nozzles in the paper transport direction and the paper transport speed.

  In addition, the pressure chambers 231 belonging to the nozzle row A and the pressure chambers 232 belonging to the nozzle row B shown in FIG. 22 are located on adjacent straight lines in the paper transport direction, and the dots 213 are formed from the nozzles corresponding to the pressure chambers 232. The dots 214 are formed from nozzles corresponding to the pressure chambers 231.

  The difference in landing time between the dot 213 and the dot 214 is determined by the interval between the two nozzles in the paper transport direction and the paper transport speed.

  As shown in FIG. 22, the distance between the nozzle corresponding to the pressure chamber 221 and the nozzle corresponding to the pressure chamber 223 is greatly different from the distance between the nozzle corresponding to the pressure chamber 231 and the nozzle corresponding to the pressure chamber 232. ing. That is, the landing time difference of each dot pair is different.

  Due to this difference in landing time difference, the degree of landing interference of each pair of dots differs, and as a result, a streak-like image defect extending in the paper transport direction occurs. The landing interference refers to a phenomenon in which ink droplets move on the recording medium immediately after landing due to the attracting of adjacent ink droplets on the recording medium.

  However, the cited documents 1 and 2 do not disclose a solution for an image defect due to a landing time difference.

  The present invention has been made in view of such circumstances, and when recording each pixel using two nozzle arrays, the variation in dot movement due to landing interference is effectively reduced, and image degradation is reduced. An object of the present invention is to provide an ink jet recording apparatus that can be suppressed.

In order to achieve the above object, one aspect of an ink jet recording apparatus is a recording head having a first nozzle row and a second nozzle row for recording the same color, the first nozzle row and the second nozzle. The rows have the same nozzle recording pitch in the first direction, and each nozzle in the first nozzle row and each nozzle in the second nozzle row are parallel to the second direction orthogonal to the first direction. Recording is performed by the recording head, the recording head arranged overlapping on a straight line, transport means for transporting at least one of the recording head and the recording medium and relatively moving the recording head and the recording medium in the second direction, and the recording head. Data acquisition means for acquiring image data, distribution means for mutually distributing the image data to the respective nozzles of the first nozzle array and the second nozzle array, and the distributed image data recorded by the recording head And a first nozzle row and a second nozzle row each having a first area to which nozzles for recording odd-numbered pixels counted from one side in the first direction belong, The recording head has a second area to which the nozzles for recording the pixels belong, and the recording head has a first area of the first nozzle array and a second area of the first nozzle array from the upstream side in the second direction. Region, second region of the second nozzle row, first region of the second nozzle row, or second region of the first nozzle row, first region of the first nozzle row, The first area of the second nozzle row and the second area of the second nozzle row are arranged in this order, and the distribution means assigns each pixel in the first direction to the nozzle of the first nozzle row and the second nozzle row. Are alternately distributed to the nozzles of the first nozzle row and each pixel in the second direction is assigned to the nozzles of the first nozzle row and the second nozzle row. It distributes alternately and Le.
In order to achieve the above object, one aspect of an ink jet recording apparatus is a recording head having a first nozzle row and a second nozzle row for recording the same color, the first nozzle row and the second nozzle. The rows have the same nozzle recording pitch in the first direction, and each nozzle in the first nozzle row and each nozzle in the second nozzle row are parallel to the second direction orthogonal to the first direction. Recording is performed by the recording head, the recording head arranged overlapping on a straight line, transport means for transporting at least one of the recording head and the recording medium and relatively moving the recording head and the recording medium in the second direction, and the recording head. Data acquisition means for acquiring image data, distribution means for mutually distributing the image data to the respective nozzles of the first nozzle array and the second nozzle array, and the distributed image data recorded by the recording head And the first nozzle row and the second nozzle row each have a first area to which nozzles for recording odd-numbered pixels counted from one side in the first direction belong, and even-numbered nozzles. And a recording head includes a first area of the first nozzle row, a second area of the first nozzle row, a second area, and a second area along a second direction. The second region of the two nozzle rows, the first region of the second nozzle row, or the second region of the first nozzle row, the first region of the first nozzle row, the second nozzle The first region of the row and the second region of the second nozzle row are arranged in this order.

  According to this aspect, the first nozzle row and the second nozzle row that record the same color are provided, and the first nozzle row and the second nozzle row have the same nozzle recording pitch in the first direction. The nozzles of the first nozzle row and the nozzles of the second nozzle row are arranged overlapping on a straight line parallel to the second direction orthogonal to the first direction, and are each in the first direction. A first region to which nozzles that record odd-numbered pixels counting from one side of the first region belong, and a second region to which nozzles that record even-numbered pixels belong, and upstream in the second direction. To the first region of the first nozzle row, the second region of the first nozzle row, the second region of the second nozzle row, the first region of the second nozzle row, or the first The second region of the nozzle row, the first region of the first nozzle row, the first region of the second nozzle row, the second nozzle Since each of the nozzles of the recording head arranged in the order of the second area is mutually distributed and recorded, when each pixel is recorded mutually using two nozzle rows, between adjacent dots By equalizing the landing time difference, it is possible to effectively reduce variations in dot movement due to landing interference and to suppress image deterioration.

  In each of the first nozzle row and the second nozzle row, nozzles are arranged over a length corresponding to the full recordable width in the first direction of the recording medium, and the conveying means moves the recording head and the recording medium once. The relative movement in the second direction is preferable. This aspect can be applied to an ink jet recording apparatus that relatively moves the recording head and the recording medium only once.

  The distribution unit alternately distributes the pixels in the first direction to the nozzles of the first nozzle row and the nozzles of the second nozzle row and distributes the pixels in the second direction to the nozzles of the first nozzle row. It is preferable to distribute alternately to the nozzles of the second nozzle row.

  This aspect can be applied to an ink jet recording apparatus that records by alternately distributing each pixel. In addition, about the 2nd direction, you may distribute alternately every 2 pixels or more instead of distributing alternately every other pixel. By distributing and recording each pixel in the first direction, it is possible to make the landing time difference between adjacent dots uniform.

  A defective nozzle information acquisition unit configured to acquire information on positions of defective nozzles in the first nozzle row and the second nozzle row, and the distribution unit is configured to detect defects in the first nozzle row based on information on the positions of defective nozzles. It is preferable to distribute data corresponding to the nozzles to the nozzles of the second nozzle row and distribute data corresponding to the defective nozzles of the second nozzle row to the nozzles of the first nozzle row.

  As described above, the data corresponding to the defective nozzles in the first nozzle row is distributed to the nozzles in the second nozzle row that are arranged on the straight line parallel to the second direction. By distributing the data corresponding to the defective nozzles to the nozzles of the first nozzle row which are arranged on a straight line parallel to the second direction, the defective nozzles can be appropriately complemented.

  Based on the information on the position of the defective nozzle in the first nozzle row and the second nozzle row, the relative shift amount in the first direction of the first nozzle row and the second nozzle row, A shift amount determining means for determining a shift amount for associating a nozzle that is not a defective nozzle with at least one of the nozzles arranged on a straight line parallel to the direction of the first nozzle row and the second nozzle The moving means for moving the relative positions of the rows, the control means for relatively shifting the first nozzle row and the second nozzle row by the determined shift amount by the moving means, and the distributing means for distributing the determined shift amount. Data moving means for shifting the image data may be provided.

  As described above, when both the nozzles of the first nozzle row and the nozzles of the second nozzle row that are arranged overlapping on a straight line parallel to the second direction are defective nozzles, at least one of them is a defective nozzle. Image defects due to defective nozzles can be avoided by relatively shifting the first nozzle row and the second nozzle row so as to correspond to nozzles that are not.

  Even after the first nozzle row and the second nozzle row are relatively displaced, the first nozzle row and the second nozzle row are aligned with each other in the second direction along the second direction. 1 region, the second region of the first nozzle row, the second region of the second nozzle row, the first region of the second nozzle row, or the second region of the first nozzle row The first region of the first nozzle row, the first region of the second nozzle row, and the second region of the second nozzle row need to be arranged in this order. That is, it is necessary to set the shift amount that can maintain this positional relationship.

  Conversion means for converting the position of each defective nozzle into the position of one coordinate system from the information of the position of the defective nozzle in the first nozzle array and the second nozzle array, and the first nozzle array and the second nozzle array A calculating unit that calculates a difference between a defective nozzle position in one nozzle row and a defective nozzle position in another nozzle row, and an extracting unit that extracts a shift amount candidate from the calculated difference; Preferably, the determining means determines a value closest to 0 from among the extracted candidates for the shift amount as the shift amount. Thereby, an appropriate shift amount can be determined.

  It is preferable that the calculation means calculates a position difference within a movable range of the movement means. Thereby, calculation time can be shortened.

  The shift amount determination means may periodically determine a different value as the shift amount from the extracted shift amount candidates.

  In this way, by periodically changing the shift amount, it is possible to disperse the load of the nozzle that complements the defective nozzle, and it is possible to improve the durability of the recording head.

  At least one nozzle row of the first nozzle row and the second nozzle row is composed of a plurality of sub nozzle rows arranged in the first direction, and the shift amount determination means sets the shift amount for each sub nozzle row. Preferably, the moving means is provided for each sub nozzle array, and the control means preferably shifts the sub nozzle array based on the determined shift amount.

  Thereby, since the number of nozzles can be reduced, manufacturing cost is reduced. If the number of nozzles is not reduced, the number of effective nozzles is increased, and the recording width can be expanded.

  The defective nozzle information acquisition means preferably acquires information on the position of a non-ejection nozzle that cannot eject ink, or a nozzle where a defective nozzle including a bent nozzle, a nozzle having a different droplet amount, and a splash nozzle is non-ejection. This makes it possible to complement not only the non-ejection nozzle but also the nozzle in which the defective nozzle is non-ejection. Here, a nozzle whose discharge direction deviates from a predetermined direction by a predetermined amount or more is called a bent nozzle.

  You may provide the memory | storage means to memorize | store the information of the position of the defective nozzle of a 1st nozzle row and a 2nd nozzle row. Thereby, the position information of the defective recording element can be appropriately acquired.

  Of the first nozzle row and the second nozzle row, the nozzle row moved by the moving means preferably has an extra nozzle in the first direction. As the number of extra recording elements increases, the moving range of the moving means can be expanded.

  According to the present invention, when each pixel is recorded using two nozzle arrays, the difference in dot movement due to landing interference is effectively reduced by equalizing the landing time difference between adjacent dots. Deterioration of the image can be suppressed.

Schematic diagram showing an inkjet recording apparatus Plane perspective view showing a structural example of a line head Top view for explaining image recording on paper by head The figure which shows the modification of a head The figure which shows the modification of a head Top view for explaining image recording on paper by head The figure which shows the state which shifted one side of the dual head A table showing the probability that non-ejection nozzles of both heads will become corresponding nozzles on the same raster line Flow chart showing shift amount calculation processing Schematic diagram showing an example of the position of the dual head and its non-ejection nozzle The figure which shows a mode that one head of the dual head is shifted to the left The figure which shows the frequency of the difference about all the combinations of the non-ejection nozzle position of a dual head Diagram showing the position of the dual head and its non-ejection nozzle The figure which shows a mode that one head of the sub head is shifted to the right Graph showing the probability that the positions of non-ejection nozzles on both heads match when divided into sub-heads Other configuration diagram of inkjet recording apparatus Plane perspective view showing structural example of head Plane perspective view showing another structural example of the head Sectional drawing which shows the three-dimensional structure of the droplet discharge element for 1 channel Main block diagram showing the system configuration of the inkjet recording apparatus Block diagram showing the internal configuration of the print controller The figure which shows the outline of the inkjet head described in patent document 2

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

<First Embodiment>
FIG. 1 is a schematic diagram illustrating an ink jet recording apparatus according to the present embodiment, in which FIG. 1A is a side view and FIG. 1B is a plan view. The ink jet recording apparatus 10 is a printer that forms an image on the recording surface of the paper P by ejecting ink from the line head 20 onto the recording surface of the paper P that is transported in the paper transport direction (y direction) by a transport means (not shown). It is.

  FIG. 2 is a perspective plan view showing a structural example of the line head 20. As shown in the figure, in the line head 20 of this example, the head 30 and the head 40 (corresponding to the first nozzle row and the second nozzle row) that record the same color are in the y direction (the conveyance direction of the paper P). , Corresponding to the second direction). The head 30 and the head 40 have the same structure in which nozzles, which are ink discharge ports for discharging the same color ink, are two-dimensionally arranged in a matrix.

  The nozzles of the head 30 and the head 40 are arranged so that a substantial nozzle interval (projection nozzle pitch) projected (orthogonally projected) to be aligned along the x direction (corresponding to the first direction) is L. Has been. Moreover, each nozzle of the head 30 and the head 40 is arrange | positioned so that it may overlap on the same straight line parallel to ay direction.

  For example, the nozzle 302 of the head 30 and the nozzle 402 of the head 40 are on the same straight line parallel to the y direction, and the second pixel is counted from the left in the x direction of the paper P (counted from one side). It is arranged at the position where it drops.

  Similarly, the nozzles 303 of the head 30 and the nozzles 403 of the head 40 are arranged on the same straight line parallel to the y direction, and are disposed at positions where the third pixel is deposited from the left in the x direction of the paper P. The nozzle 304 and the nozzle 404 are arranged on the same straight line parallel to the y direction, and are disposed at positions where the fourth pixel is deposited from the left in the x direction of the paper P.

  Similarly, the nozzles of the head 30 and the head 40 are arranged corresponding to each pixel of the paper P, and the nozzle 348 and the nozzle 448 are on the same straight line parallel to the y direction, and The 48th pixel is counted from the left in the x direction.

  In addition, each nozzle of the head 30 is a nozzle that records even pixels in a region 30o (corresponding to the first region) in which a nozzle group that ejects odd pixels on the paper P is located upstream in the transport direction of the paper P. The groups are respectively arranged in the region 30e (corresponding to the second region) located on the downstream side in the transport direction of the paper P.

  Similarly, each nozzle of the head 40 records odd pixels in a region 40e (corresponding to the first region) in which a nozzle group for ejecting even pixels on the paper P is located upstream in the transport direction of the paper P. Nozzle groups are respectively arranged in regions 40o (corresponding to the first region) located on the downstream side in the transport direction of the paper P.

  Here, the distance D1 between the position in the y direction of the region 30o and the position in the y direction of the region 40e is equal to the distance D2 in the y direction between the region 30e and the region 40o. Here, the average position in the y direction of each nozzle arranged in each region is defined as the position in the y direction of that region.

  FIG. 3 is a top view for explaining image recording on the paper P by the line head 20, and is a view seen through each nozzle. Here, the dots recorded by the nozzles arranged in the area 30 o of the head 30 are upward black triangle marks “▲”, the dots recorded by the nozzles arranged in the area 30 e are upward white triangle marks “Δ”, and the head 40 The dots recorded by the nozzles arranged in the area 40e are indicated by the downward white triangle mark “▽”, and the dots recorded by the nozzles arranged in the area 40o are indicated by the downward black triangle mark “▼”.

  As shown in FIG. 3, each recording line parallel to the x direction is recorded alternately by the nozzles of the head 30 and the nozzles of the head 40. Further, recording lines parallel to the y direction are also recorded alternately by the nozzles of the head 30 and the nozzles of the head 40.

  For example, the dot 501 shown in FIG. 3 is a dot ejected by the nozzle 303 arranged in the region 30 o of the head 30. A dot 502 adjacent to the dot 501 in the x direction is a dot ejected by the nozzle 404 disposed in the region 40 e of the head 40. A dot 503 adjacent to the dot 502 in the x direction is a dot ejected by the nozzle 305 disposed in the region 30 o of the head 30.

  In this way, the recording lines parallel to the x direction formed from the dots 501, 502, 503,... Are alternately formed from the nozzles arranged in the region 30o of the head 30 and the nozzles arranged in the region 40e of the head 40. Each pixel is recorded with each other when the dots are ejected. Therefore, the landing time differences between the dots adjacent to each other in the x direction are almost equal, and the degree of landing interference is also equal.

  On the other hand, the dot 511 adjacent to the y direction of the dot 501 is a dot ejected by the nozzle 403 arranged in the area 40 o of the head 40. A dot 512 adjacent to the dot 511 in the x direction is a dot ejected by the nozzle 304 arranged in the region 30 e of the head 30. A dot 513 adjacent to the dot 512 in the x direction is a dot ejected by the nozzle 405 arranged in the region 40 o of the head 40.

  As described above, the recording lines parallel to the x direction formed from the dots 511, 512, 513,... Are alternately formed from the nozzles arranged in the area 30e of the head 30 and the nozzles arranged in the area 40o of the head 40. Dots are recorded. Therefore, the landing time differences between the dots adjacent to each other in the x direction are almost equal, and the degree of landing interference is also equal.

  Thus, by using the line head 20 having the nozzle arrangement shown in FIG. 2, it is possible to effectively reduce the variation in dot movement due to landing interference.

  In the example shown in FIG. 3, the recording lines parallel to the y direction are alternately recorded every other pixel by the nozzles of the head 30 and the nozzle of the head 40, but are alternately recorded every two or more pixels. Also good.

  In the line head 20 shown in FIG. 2, in order from the upstream in the transport direction of the paper P, a region 30 o where nozzle groups for ejecting odd pixels of the head 30 are arranged, and a nozzle group for ejecting even pixels of the head 30. Are arranged in the order of the region 30e where the nozzle group for ejecting the even pixels of the head 40 is disposed, and the region 40o where the nozzle group for ejecting the odd pixels of the head 40 is disposed. The arrangement is not limited to this.

  For example, as in the line head 22 shown in FIG. 4, a region 30 e where nozzle groups for ejecting even pixels of the head 30 are arranged in order from the upstream in the transport direction of the paper P, and nozzles for ejecting odd pixels of the head 30. An area 30o in which groups are arranged, an area 40o in which nozzle groups for ejecting odd pixels of the head 40 are disposed, and an area 40e in which nozzle groups for ejecting even pixels of the head 40 are disposed are arranged in this order. Good.

  Also, the nozzle arrangement in each region is not particularly limited. For example, it may be arranged like a line head 24 shown in FIG.

  In this embodiment, the head 30 and the head 40 having the same structure are shifted by one pixel in the x direction and arranged along the transport direction of the paper P. However, two nozzle rows may be arranged in one head. Good. In this case, nozzles that record odd pixels of the first nozzle row, nozzles that record even pixels of the first nozzle row, and even pixels of second nozzle row are recorded along the transport direction of the paper P. Nozzles, nozzles for recording odd pixels in the second nozzle array, nozzles for recording even pixels in the first nozzle array, nozzles for recording odd pixels in the first nozzle array, second nozzle arrays The nozzles for recording the odd pixels and the nozzles for recording the even pixels in the second nozzle row may be arranged in this order. Further, either the first nozzle row or the second nozzle row may be located on the upstream side.

<Second Embodiment>
6 is a top view for explaining image recording on the paper P by the line head 20 shown in FIG. 2, and shows a state in which each nozzle is seen through as in FIG. Here, non-ejection nozzles are indicated by “x”.

  Similarly to the first embodiment, the line head 20 records each recording line parallel to the x direction and each recording line (raster line) parallel to the y direction by the nozzles of the head 30 and the nozzles of the head 40. To do.

  For example, in FIG. 6, raster lines 521 are alternately recorded by the nozzles 302 of the head 30 and the nozzles 402 of the head 40 arranged on the same straight line parallel to the y direction. The nozzles of the head 30 and the nozzles of the head 40 arranged on the same straight line parallel to the y direction are referred to as corresponding nozzles.

  Further, the line head 20 of the present embodiment is replaced by the nozzle of the other head corresponding to this non-ejection nozzle when there is a non-ejection nozzle (nozzle that cannot eject ink) in the head 30 or the head 40. To record (alternative droplet ejection).

  For example, it is assumed that the nozzle 406 of the head 40 is a non-ejection nozzle. The raster line 522 should be recorded alternately by the nozzle 306 of the head 30 and the nozzle 406 of the head 40, but since the nozzle 406 is a non-ejection nozzle, all dots are recorded by the nozzle 306.

  Further, it is assumed that the nozzle 317 of the head 30 is a non-ejection nozzle. In this case, the raster line 523 records all the dots by the nozzle 417 of the head 40 arranged on the same straight line parallel to the y direction as the nozzle 317.

  Thus, according to the line head 20 constituting the dual head, even if one of the corresponding nozzles is a non-ejection nozzle, it is possible to prevent image defects by complementing with the other nozzle.

  However, when both of the corresponding nozzles are non-ejection nozzles, complementation cannot be performed. In the example of FIG. 6, since both the nozzle 323 of the head 30 and the nozzle 423 of the head 40, which are corresponding nozzles, are non-ejection nozzles, white stripes occur in the raster line 524.

  In order to prevent this, the line head 20 of the present embodiment is configured such that the head 40 can be moved in the x direction in units of twice the nozzle interval (2 × L units) by moving means (not shown). . That is, the head 40 can change the corresponding nozzle while maintaining the state where the nozzle group for ejecting odd pixels on the paper P is disposed in the area 40o and the nozzle group for recording even pixels is disposed in the area 40e. It is.

  FIG. 7 is a diagram illustrating a state in which the head 40 is shifted by two nozzles (2 × L) in the left direction in the x direction in the line head 20 illustrated in FIG. 6.

  In the example of FIG. 7, since the head 40 is moved in the left direction, the raster lines 521 are alternately recorded by the nozzles 302 and 404 which are corresponding nozzles. That is, data corresponding to the nozzle 402 before the head 40 is moved is recorded by the nozzle 404. As described above, it is necessary to shift the data recorded in each nozzle of the head 40 according to the movement amount of the head 40.

  Further, as shown in FIG. 7, the corresponding nozzle of the nozzle 406 that is a non-ejection nozzle of the head 40 is a nozzle 304. Accordingly, all dots are recorded by the nozzle 304 in the raster line 532 corresponding to the nozzle 406.

  Similarly, the corresponding nozzle of the nozzle 317 that is a non-ejection nozzle of the head 30 is the nozzle 419. Accordingly, all dots are recorded by the nozzle 419 in the raster line 533 corresponding to the nozzle 317.

  Further, since the head 40 is shifted, the two non-ejection nozzles 323 and 423, which are corresponding nozzles, are arranged on different straight lines parallel to the y direction. Therefore, these non-ejection nozzles can also be supplemented with new corresponding nozzles.

  Here, the nozzle corresponding to the nozzle 423 is the nozzle 321. Therefore, all dots are recorded by the nozzle 321 in the raster line 534 corresponding to the nozzle 423. Further, the nozzle corresponding to the nozzle 323 is the nozzle 425. Therefore, all dots are recorded by the nozzle 425 on the raster line 535 corresponding to the nozzle 323.

  As described above, when there is a combination in which both of the corresponding nozzles of the same raster line are non-ejection nozzles, the inkjet recording apparatus 10 shifts the two heads relative to each other in the x direction to change the combination of the corresponding nozzles. By changing and changing to a combination in which at least one of the corresponding nozzle combinations is a normal nozzle, all raster lines can be recorded, and image defects can be avoided.

  In the example of FIG. 6, when the head 40 is shifted by two nozzles to the left in the x direction, at least one of the corresponding nozzle combinations is a normal nozzle combination.

  Here, in the case where the number of nozzles of each of the two heads is 25,000, when there are the same number of non-ejection nozzles in each head, the probability that the non-ejection nozzles of both heads coincide, that is, the non-ejection of both heads. The probability that a nozzle will be a corresponding nozzle on the same raster line is shown in FIG.

For example, when there are 240 non-ejection nozzles (about 1% of the total number of nozzles), the probability that the non-ejection nozzles match is about 90% as shown in FIG. In this way, when the number of non-ejection nozzles (absolute number) is large, if one tries to find a combination in which at least one is a normal nozzle while shifting by one nozzle or several nozzles, it will take until the combination is reached. It will take a lot of time.

  Therefore, in this embodiment, the shift amount is not determined by trial and error, but is definitely determined, and a state in which the defective nozzles do not match is surely created by shifting with the determined shift amount.

<Calculation method of shift amount>
FIG. 9 is a flowchart showing a shift amount calculation process in the present embodiment. FIG. 10 shows a dual head composed of an A head and a B head arranged in order along the transport direction (y direction) of the paper P by the transport means (not shown) and the non-ejection thereof. It is a schematic diagram which shows an example of the position of a nozzle. The head A and the head B are two-dimensionally arranged in a matrix like the head 30 and the head 40 shown in FIG. 2, respectively, but here each nozzle is arranged in a line in the x direction. It is shown as simplified.

  The nozzles of the A head and the nozzle of the B head are arranged so as to overlap on the same straight line parallel to the y direction. Further, the B head is configured to be movable in units of two nozzles (two raster lines) in the x direction.

  In the example shown in FIG. 10, each of the A head and the B head has 40 nozzles arranged at equal intervals in the x direction. The number of non-ejection nozzles is Nng_a = 4 for the A head and Nng_b = 5 for the B head.

  Note that the flowchart shown in FIG. 9 may be performed when the positions of the non-ejection nozzles overlap on the same raster line, or when the non-ejection nozzles do not overlap for load distribution described later. Also good.

[Step S1 (Defect Recording Element Information Acquisition Step)]
First, information No._A (ng) and No._B (ng) of the non-ejection nozzle positions of both the A and B heads are acquired. The non-ejection nozzle position information is acquired by printing a non-ejection nozzle detection test chart for each head and reading the test chart image printed by a scanner or the like. Here, information on the non-ejection nozzle position obtained based on the read data of the test chart image is stored in advance in the memory, and this information is read out from the memory and obtained.

In the example shown in FIG. 10, the position of the non-ejection nozzle is No._A (ng) = {4, 19, 27, 31} for the A head, and No._B ( ng) = {5, 17, 27, 30, 34}.
[Step S2 (coordinate conversion process)]
Next, the information No._A (ng) and No._B (ng) of the non-ejection nozzle positions of both heads A and B are combined with the position information No. (A, ng), No. Convert to. (B, ng).

  As described above, the B head is configured to be movable in units of two nozzles in the x direction, and the nozzle of the B head corresponding to each raster line of the paper P varies depending on the current movement amount (set position). Come. Therefore, the non-ejection nozzle position of the B head is converted into the coordinate system of the A head based on the current movement amount.

  In the example shown in FIG. 10, for the A head, the position of the non-ejection nozzle in one coordinate system is No. (A, ng) = {4, 19, 27, 31}. The movement amount of the B head is 0, and the position of the non-ejection nozzle of the B head in one coordinate system is No. B (ng) = {5, 17, 27, 30, 34}. If the B head is moved by one raster in the right direction in the drawing, the position of the non-ejection nozzle of the B head in one coordinate system is added by one nozzle from the non-ejection nozzle position in the B head. The position, that is, No. B (ng) = {6, 18, 28, 31, 35}.

[Step S3 (difference calculation step)]
Based on the information No. (A, ng) and No. (B, ng) of the non-ejection nozzle position in one coordinate system obtained in step S2, the non-ejection nozzle position of the A head and the non-ejection nozzle of the B head The difference ΔNo. (B−A) = No. (B, ng) −No. (A, ng) is obtained for all combinations of positions.

  For example, the position number (A, ng) = {4, 19, 27, 31 of each non-ejection nozzle of the A head with respect to the position number (B, ng) = 5 of one non-ejection nozzle of the B head. } Is ΔNo. (B−A) = {1, −14, −22, −26}. Further, the position number (A, ng) = {4, 19, 27, 31 of each non-ejection nozzle of the A head with respect to the position number (B, ng) = 17 of other non-ejection nozzles of the B head. } Is ΔNo. (B−A) = {13, −2, −10, −14}. Similarly, for each of the non-ejection nozzles of B head, No. (B, ng) = 27, No. (B, ng) = 30, No. (B, ng) = 34, each non-ejection of A head The difference from the nozzle position is calculated.

  As a result, the difference between all combinations is ΔNo. (B−A) = {30,26,23,15,13,11,8,7,3,3,1,0, -1, -2,- 4, -10, -14, -14, -22, -26}.

[Step S4 (shift amount determination step)]
For a plurality of differences ΔNo. (B−A) calculated in step S3, multiples of 2 that are not included in these values are candidates for the shift amount. That is, when the B head is shifted by the shift amount calculated in step S3, a raster line is generated in which both nozzles of the corresponding nozzle are non-ejection nozzles. Conversely, if the B head is shifted by a shift amount other than the value calculated in step S3, at least one of the corresponding nozzles on the same raster line becomes a normal nozzle in all regions.

  As described above, the nozzles of the A head and the B head are arranged in the same manner as the head 30 and the head 40 shown in FIG. That is, in order from the upstream in the transport direction of the paper P, an area where nozzle groups for ejecting odd pixels of the A head are disposed, an area where nozzle groups for ejecting even pixels of the A head are disposed, and even pixels of the B head Are arranged in the order of the area where the nozzle group for ejecting droplets is disposed and the area where the nozzle group for ejecting odd pixels of the B head is disposed.

  In order to shift the B head while maintaining this relationship, it is necessary to shift in the x direction in units of 2 nozzles (2 raster lines). Therefore, a multiple of 2 that is not included in the values of a plurality of differences ΔNo. (B−A) is set as a candidate for the shift amount.

  Here, {..., 6,5,4,2, -3, -5, ...} can be extracted as candidates for the shift amount. A multiple of 2 closest to 0 is selected from the candidates for the shift amount, and is set as the shift amount. Here, the shift amount = 2.

[Step S5 (movement process)]
Next, the shift amount determined in step S4 is given between the A and B heads. Here, since the shift amount = 2, it is only necessary to shift the B head by two nozzles with respect to the A head. That is, the B head is shifted by two nozzles in the left direction in FIG.

  FIG. 11A is a diagram illustrating a state in which the B head is shifted leftward by two nozzles. As shown in the figure, in the nozzles corresponding to the raster lines of A head and B head, there is no position where the non-ejection nozzles overlap. That is, all the raster lines can be recorded with the nozzles of A head or B head.

[Step S6 (Data Movement Step)]
Finally, the calculated shift amount is given to the image data recorded in the B head with respect to the image data acquired in advance (corresponding to the data acquisition step). That is, the image data is shifted to the right in the drawing by two nozzles and input to the B head.

  As described above, the shift amount is definitely determined based on the position information of the non-discharge nozzles of the two heads, and the determined shift amount is given to the head, so that the position of the non-discharge nozzles is not surely matched. Can be produced.

  FIG. 12 is a table showing simulation results when it is assumed that 240 non-ejection nozzles are randomly present in both the A and B heads when the number of nozzles of the A head and B head is 25,000, respectively. The difference ΔNo. (BA) for all combinations of the non-ejection nozzle position of the A head and the non-ejection nozzle position of the B head indicates the frequency at which ΔNo. (BA) = − 20 to 20.

  In the example shown in FIG. 12, there is no combination in which ΔNo. (B-A) is 16, -13, or -16. Among these, 16 and -16, which are multiples of 2, are candidates for the shift amount. Thus, when the number of non-ejection nozzles is large, it is difficult to find a candidate for the shift amount by trial and error. On the other hand, according to the processing of the present embodiment, the amount of shift can be determined by simple calculation and the head can be quickly shifted.

  In this embodiment, the B head is shifted in the x direction with respect to the calculated shift amount, but the shift is not limited to the B head, and the shift amount is relatively between the A head and the B head. Should be given.

  For example, in this embodiment, the B head is shifted leftward by two nozzles with respect to the calculated shift amount = 2, but the same effect can be obtained by shifting the A head by two nozzles rightward. The same applies when the A head is shifted rightward by one nozzle and the B head is shifted leftward by one nozzle. In this case, for the shifted head, it is necessary to shift and input the image data in accordance with the shift amount.

  Further, in this embodiment, the difference ΔNo. (B−A) is calculated for all combinations of the non-ejection nozzle position information of the A head and the non-ejection nozzle position information of the B head, but within the movable range of the B head. The difference may be calculated at.

  For example, when the possible shift amount of the B head in the x direction is ± 6 nozzles (± 6 raster lines), B exists at a position within ± 6 raster lines with respect to the non-ejection nozzles of the A head. The position difference is calculated with respect to the ejection failure nozzle of the head. With respect to the calculated difference ΔNo. (B−A), a value that is a multiple of 2 that is not included in these values and is close to 0 and within the movable range of the B head is obtained. What is necessary is just to set it as the amount of shift.

  In this way, the calculation time of the shift amount can be shortened by performing only necessary calculations.

  In addition, as described with reference to FIG. 6, when the corresponding nozzle on the same recording line is a non-ejection nozzle, it is necessary to supplement the nozzle and eject ink, so that the complementary nozzle is another nozzle. The number of discharges increases and the load is large.

  On the other hand, according to the present embodiment, a plurality of candidates for the required shift amount can be listed. Therefore, by periodically changing the displacement amount of these candidates, it is possible to disperse the complementary nozzles with a large load, and thus it is possible to improve the durability of the head.

  Here, “periodic” may be every time the power is turned on, every job, every other predetermined number of prints, or every time the user manually switches.

  In the above example, {..., 6, 5, 4, 2, -3, -5,. From these candidates, for example, shift amount = 2 and shift amount = 4 are selected. The complementary nozzle can be switched by periodically switching the shift amount = 2 and the shift amount = 4.

  FIG. 11B is a diagram illustrating a state in which the B head is shifted leftward by 4 nozzles. As shown in FIGS. 11A and 11B, the complementary nozzles are different depending on the shift amount, and the load of each nozzle can be distributed. Thereby, the load of the head can be reduced and the durability can be improved.

  In the present embodiment, the case where the positions of the non-ejection nozzles overlap has been described. However, the nozzles that do not perform printing are not limited to non-ejection nozzles. For example, defective nozzles such as bent nozzles (nozzles whose ejection direction deviates by a predetermined amount or more from a predetermined direction), nozzles with a small ejection amount, and nozzles with a large splash may be masked to cause non-ejection. The processing of this embodiment can also be applied to the non-ejection nozzle in this case.

<Third Embodiment>
FIG. 13 is a diagram showing the positions of the A head and B head and the non-ejection nozzles in this embodiment. The A head of the present embodiment is a two-dimensional arrangement of nozzles in a matrix, and in FIG. 13, as in FIG. 10, each nozzle is arranged in a row in the x direction for simplicity. ing.

  In the B head of this embodiment, sub heads (C1 head to C5 head, corresponding to the sub recording element array) each having 12 nozzles arranged in a matrix are arranged in a staggered manner in the x direction. In FIG. 13, similarly to the head A, each sub head is shown in a simplified manner assuming that the nozzles are arranged in a line in the x direction.

  These C1 to C5 heads are configured to be movable in units of two raster lines in the x direction by moving means (not shown). Further, the nozzles of the A head and the nozzle of the B head are arranged so as to overlap on the same straight line parallel to the y direction so that the raster lines are complementarily recorded.

  Here, the same raster as the first to eighth nozzles from the left of the A head is recorded in the nozzle of the C1 head, and the same as the ninth to sixteenth nozzles from the left of the A head in the nozzle of the C2 head. The raster is recorded, and the same raster as the 17th to 24th nozzles from the left of the A head is recorded at the nozzle of the C3 head, and the same as the 25th to 32nd nozzles from the left of the A head at the nozzle of the C4 head. The raster is recorded, and the same raster as the 33rd to 40th nozzles from the left of the A head is recorded in the nozzle of the C5 head.

  Hereinafter, the shift amount calculation method according to the present embodiment will be described with reference to the flowchart of FIG.

[Step S1]
First, information on the ejection failure nozzle positions of both the A and B heads is acquired. Note that, as in the second embodiment, information on the non-ejection nozzle position for each head is stored in the memory in advance.

  In the example shown in FIG. 13, the non-ejection nozzle position is No. A (ng) = {4, 19, 27, 31} for the A head. For head B, No.C1 (ng) = 7, No.C3 (ng) = 3, No.C4 (ng) = {5,8}, No.C5 (ng) = 4 for each sub head. Can be represented.

[Step S2]
Next, the information No. A (ng) and No. CN (ng) of the non-ejection nozzle positions of both A and B heads are combined with the position information No. (A, ng), No. Convert to. (B, ng). Here, similarly to the second embodiment, the non-ejection nozzle position of the movable B head is converted into the coordinate system of the A head.

  In the example shown in FIG. 13, for A head, the position of the non-ejection nozzle in one coordinate system is No. (A, ng) = {4, 19, 27, 31}. The B head can be expressed as No. B (ng) = {5, 17, 27, 30, 34} from the positions of the heads C1 to C5.

[Step S3]
From the non-ejection nozzle position information No. (A, ng) and No. (B, ng) in one coordinate system obtained in step S2, the non-ejection nozzle positions overlap, that is, on the same raster line. It can be seen that both of the corresponding nozzles are non-ejection nozzles at the 27th position from the left of the A head. In the B head, the raster at this position is recorded by the C4 head, and therefore only the C4 head needs to be shifted in this example.

  Therefore, here, all combinations of the non-ejection nozzle position information in the range recorded by the C4 head among the non-ejection nozzle position information of the A head and the non-ejection nozzle position information of the C4 head among the non-ejection nozzle position information of the B head. The difference ΔNo. (B−A) = No. (B, ng) −No. (A, ng) is obtained. That is, the difference between the non-ejection nozzle position information No. (A, ng) = {27, 31} of the A head and the non-ejection nozzle position information No. B (ng) = {27, 30} of the B head is calculated. do it.

  As a result, the difference between all combinations is ΔNo. (B−A) = {3, 0, −1, −4}.

[Step S4]
For a plurality of differences ΔNo. (B−A) calculated in step S3, multiples of 2 that are not included in these values are candidates for the shift amount. Here, a value closest to 0 is selected from the candidates for the shift amount, and is set as the shift amount. In this example, the shift amount = −2.

[Step S5]
Next, the shift amount determined in step S4 is given between the A and B heads. Here, since the shift amount = −2, it is only necessary to shift the C4 head of the B heads by −2 rasters with respect to the A head. That is, the C4 head is shifted by two rasters to the right in FIG.

  FIG. 14 is a diagram showing a state in which the C4 head of the B heads is shifted rightward by two rasters. As shown in the figure, in each raster line, there is no position where the non-ejection nozzles of A head and B head overlap.

[Step S6]
Finally, the calculated shift amount is given to the image data recorded in the C4 head among the B heads. That is, the image data is shifted to the left of the drawing by −2 rasters.

  FIG. 15 shows the probability that the positions of the non-ejecting nozzles of both heads A and B have the same number of non-ejecting nozzles when both A and B heads have 25,000 nozzles. It is the shown graph, and has shown the probability at the time of dividing | segmenting into 1, 2, 4, 12 subheads, respectively.

  As shown in FIG. 15, it can be seen that even if the total number of non-ejection nozzles is the same, the probability that the positions of non-ejection nozzles match decreases as the number of divisions increases. Therefore, at least one normal nozzle can correspond to each raster line with a small shift amount.

  As described above, by dividing the head into sub head units and configured to be movable for each sub head, the shift amount when the positions of the non-ejection nozzles coincide can be reduced. Thereby, the number of nozzles can be reduced and the manufacturing cost is reduced. If the number of nozzles is not reduced, the number of effective nozzles is increased, and the recording width can be expanded.

  In the present embodiment, the B head is divided into sub heads and the sub heads can be moved in the x direction. However, it is also possible to divide both the A and B heads into sub heads.

<Other structural examples of inkjet recording apparatus>
FIG. 16 is another configuration diagram of an ink jet recording apparatus to which the present embodiment is applicable. This ink jet recording apparatus 100 is an impression cylinder direct drawing type ink jet that forms a desired color image by directly ejecting ink of a plurality of colors onto a recording medium 114 held on the impression cylinder 126c of the ink droplet ejection unit 108. The recording apparatus is an on-demand type image forming apparatus to which a two-liquid reaction (aggregation) method for forming an image on a recording medium 114 using ink and a processing liquid (here, an aggregation processing liquid) is applied.

  The ink jet recording apparatus 100 mainly includes a paper supply unit 102 that supplies a recording medium 114, a permeation suppression agent applying unit 104 that applies a permeation suppression agent to the recording medium 114, and a process that applies a treatment liquid to the recording medium 114. The liquid application unit 106, the ink droplet ejection unit 108 that ejects ink onto the recording medium 114, the fixing unit 110 that fixes the image formed on the recording medium 114, and the recording medium 114 on which the image is formed are conveyed. The paper discharge unit 112 is configured to be discharged.

  The paper supply unit 102 is provided with a paper supply table 120 on which a sheet recording medium 114 is stacked. The recording media 114 loaded on the paper feed table 120 are sent one by one to the feeder board 122 in order from the top, and received by the pressure drum (permeation inhibitor drum) 126a of the permeation suppression agent applying unit 104 via the transfer drum 124a. Passed.

  Holding claws 115a and 115b (grippers) for holding the leading end of the recording medium 114 are formed on the surface (circumferential surface) of the pressure drum 126a. The recording medium 114 transferred from the transfer drum 124a to the pressure drum 126a is in close contact with the surface of the pressure drum 126a while being held at the front end by the holding claws 115a and 115b (that is, the state wound around the pressure drum 126a). ) In the rotational direction of the impression cylinder 126a (counterclockwise direction in FIG. 16). The same configuration is applied to other impression cylinders 126b to 126d described later. A member 116 is formed on the surface (circumferential surface) of the transfer drum 124a to transfer the tip of the recording medium 114 to the holding claws 115a and 115b of the pressure drum 126a. The same configuration is applied to other transfer cylinders 124b to 124d described later.

(Penetration inhibitor application part)
In the permeation suppression agent applying unit 104, the sheet preheating unit 128 and the permeation suppression agent discharge are disposed at positions facing the surface of the pressure drum 126 a in order from the upstream side in the rotation direction of the pressure drum 126 a (counterclockwise direction in FIG. 16). A head 130 and a permeation suppression agent drying unit 132 are provided.

  Each of the paper preheating unit 128 and the permeation suppression agent drying unit 132 is provided with a hot air dryer capable of controlling temperature and air volume within a predetermined range. When the recording medium 114 held on the impression cylinder 126a passes through a position facing the paper preheating unit 128 and the permeation suppression agent drying unit 132, the air heated by the hot air dryer (hot air) is applied to the surface of the recording medium 114. It is configured to be sprayed toward.

  The permeation suppression agent discharge head 130 discharges a solution containing a permeation suppression agent (hereinafter also simply referred to as “permeation suppression agent”) to the recording medium 114 held on the pressure drum 126a. In this example, a droplet ejection method is applied as a means for applying a permeation inhibitor to the surface of the recording medium 114, but the present invention is not limited to this, and various methods such as a roller coating method and a spray method are applied. It is also possible to do.

  The permeation suppressor suppresses permeation into the recording medium 114 of a solvent (and a solvophilic organic solvent) contained in a processing liquid and an ink liquid described later. As the permeation inhibitor, a resin particle dispersed (or dissolved) in a solution is used. For example, an organic solvent or water is used as the solution of the penetration inhibitor. As the organic solvent for the penetration inhibitor, methyl ethyl ketone, petroleum, and the like are preferably used.

  The paper preheating unit 128 makes the temperature Tm1 of the recording medium 114 higher than the minimum film-forming temperature Tf1 of the resin particles of the permeation suppression agent. As a method for adjusting the temperature Tm1, there are a method of heating the recording medium 114 from the lower surface using a heating element such as a heater installed inside the pressure drum 126a, and a method of heating the upper surface of the recording medium 114 by applying hot air. In this example, a method of heating from the upper surface of the recording medium 114 using an infrared heater or the like is used. These methods may be combined.

  For the method of applying the penetration inhibitor, droplet ejection, spray coating, roller coating or the like is preferably used. In the case of droplet ejection, a permeation inhibitor can be selectively applied only to the ink droplet ejection location and its surroundings, which will be described later, which is preferable. Further, in the case of the recording medium 114 where curling is unlikely to occur, the application of the permeation inhibitor may be omitted.

  A treatment liquid application unit 106 is provided following the permeation suppression agent application unit 104. A transfer drum 124b is provided between the pressure drum (penetration inhibitor drum) 126a of the permeation suppression agent applying unit 104 and the pressure drum (processing liquid drum) 126b of the treatment liquid applying unit 106 so as to be in contact therewith. ing. As a result, the recording medium 114 held on the pressure drum 126a of the permeation suppression agent applying unit 104 is delivered to the pressure drum 126b of the treatment liquid application unit 106 via the transfer drum 124b after the permeation suppression agent is applied. .

(Processing liquid application part)
In the treatment liquid application unit 106, a sheet preheating unit 134 and a treatment liquid discharge head 136 are disposed at positions facing the surface of the pressure drum 126 b in order from the upstream side in the rotation direction of the pressure drum 126 b (counterclockwise direction in FIG. 16). , And a processing liquid drying unit 138 are provided.

  Since the paper preheating unit 134 has the same configuration as that of the paper preheating unit 128 of the permeation suppression agent applying unit 104, the description thereof is omitted here. Of course, different configurations may be applied.

  The treatment liquid ejection head 136 is for ejecting treatment liquid onto the recording medium 114 held by the pressure drum 126b, and is the same as each ink ejection head 140C, 140M, 140Y, 140K of the ink ejection unit 108. Configuration is applied.

  The processing liquid used in this example agglomerates color materials contained in the ink ejected from the ink ejection heads 140M, 140K, 140C, and 140Y disposed in the ink ejection unit 108 toward the recording medium 114. It is an acidic liquid having an action.

  The processing liquid drying unit 138 is provided with a hot air dryer capable of controlling the temperature and the air volume within a predetermined range, and the recording medium 114 held on the impression cylinder 126 b faces the hot air dryer of the processing liquid drying unit 138. When passing through the position, air heated by a hot air dryer (hot air) is sprayed onto the processing liquid on the recording medium 114.

  The temperature and air volume of the hot air dryer are adjusted so that the processing liquid applied on the recording medium 114 is dried by the processing liquid discharge head 136 disposed on the upstream side in the rotation direction of the impression cylinder 126 b, and the solid is formed on the surface of the recording medium 114. Or a semi-solid solution aggregation treatment agent layer (thin film layer in which the treatment liquid is dried) is set to such a value.

[Ink ejection part]
An ink droplet ejection unit 108 is provided following the treatment liquid application unit 106. A transfer cylinder 124c is provided between the pressure drum (processing liquid drum) 126b of the treatment liquid application unit 106 and the pressure drum 126c of the ink droplet ejection unit 108 so as to be in contact therewith. As a result, the recording medium 114 held on the pressure drum 126b of the treatment liquid application unit 106 is applied with the treatment liquid to form a solid or semi-solid aggregating treatment agent layer, and then via the transfer cylinder 124c. The ink is transferred to a pressure drum (drawing drum) 126c of the ink droplet ejection unit 108.

  The ink droplet ejecting section 108 has four colors of CMYK at positions facing the surface of the pressure drum 126c in order from the upstream side in the rotation direction (counterclockwise direction in FIG. 16) of the pressure drum 126c (corresponding to the conveying means). Ink droplet ejection heads 140C, 140M, 140Y, and 140K (corresponding to recording heads) corresponding to the respective inks are provided side by side, and further, solvent drying units 142a and 142b are provided downstream thereof.

  As each of the ink droplet ejection heads 140C, 140M, 140Y, and 140K, a dual head in which a plurality of recording heads (liquid droplet ejection heads) that eject liquid is sequentially arranged along the transport direction is applied. That is, each of the ink droplet ejection heads 140C, 140M, 140Y, and 140K has a plurality of heads arranged in order along the transport direction, and a recording medium in which the corresponding color ink droplets are held on the impression cylinder 126c. It discharges toward 114.

  The ink storage / loading unit (not shown) includes an ink tank that stores ink supplied to each of the ink droplet ejection heads 140C, 140M, 140Y, and 140K. Each ink tank communicates with a corresponding head via a required flow path, and supplies a corresponding ink to each ink droplet ejection head. The ink storage / loading unit includes notifying means (display means, warning sound generating means) for notifying when the remaining amount of liquid in the tank is low, and has a mechanism for preventing erroneous loading between colors. ing.

  Ink is supplied from each ink tank of the ink storage / loading unit to each ink droplet ejection head 140C, 140M, 140Y, 140K, and from each ink droplet ejection head 140C, 140M, 140Y, 140K to the recording medium 114 according to an image signal. On the other hand, corresponding color inks are ejected.

  Each of the ink droplet ejection heads 140C, 140M, 140Y, and 140K has a length corresponding to the maximum width of the image forming area in the recording medium 114 held by the impression cylinder 126c, and the image forming area is disposed on the ink ejection surface. This is a dual head having a plurality of full line type heads in which a plurality of nozzles for ink ejection (not shown in FIG. 16) are arranged over the entire width (see FIG. 17). The ink droplet ejection heads 140C, 140M, 140Y, and 140K are installed so as to extend in a direction orthogonal to the rotation direction of the impression cylinder 126c (conveying direction of the recording medium 114).

  According to the configuration in which a full line head having a nozzle row covering the entire width of the image forming area of the recording medium 114 is provided for each ink color, the recording medium 114 is conveyed at a constant speed by the impression cylinder 126c, and this conveying direction ( With respect to the sub-scanning direction), the image of the recording medium 114 can be obtained by performing the operation of relatively moving the recording medium 114 and the ink ejection heads 140C, 140M, 140Y, and 140K once (that is, in one sub-scanning). An image can be recorded in the formation area. Single-pass image formation with such a full-line (page wide) head is a multi-pass with a serial (shuttle) type head that reciprocates in the direction (main scanning direction) orthogonal to the recording medium conveyance direction (sub-scanning direction). High-speed printing is possible as compared with the case where the method is applied, and print productivity can be improved.

  The ink jet recording apparatus 100 of this example is capable of recording up to, for example, a recording medium (recording paper) having a maximum chrysanthemum half size. As the impression cylinder (drawing drum) 126c, for example, a drum having a diameter of 810 mm corresponding to a recording medium width of 720 mm. Is used. The ink ejection volumes of the ink ejection heads 140C, 140M, 140Y, and 140K are, for example, 2 pl, and the recording density is the main scanning direction (width direction of the recording medium 114) and the sub-scanning direction (conveyance direction of the recording medium 114). Both are 1200 dpi, for example.

  Further, in this example, the configuration of four colors of CMYK is illustrated, but the combination of ink colors and the number of colors is not limited to the present embodiment, and R (red), G (green), and B as necessary. (Blue) ink, light ink, dark ink, and special color ink may be added. For example, it is possible to add a head for ejecting light ink such as light cyan and light magenta, and the arrangement order of the color heads is not particularly limited.

  Although not shown in the drawing, head maintenance such as preliminary discharge and suction operation is performed by moving the head from an image recording position (drawing position) immediately above the impression cylinder 126c (drawing drum) to a predetermined maintenance position (for example, pressure). The cylinder 126c is configured to be executed in a state of being retracted to a position outside the drum in the axial direction.

  The solvent drying units 142a and 142b include hot air dryers that can control the temperature and the air volume within a predetermined range, like the paper preheating units 128 and 134, the permeation suppression agent drying unit 132, and the treatment liquid drying unit 138 described above. Composed. When ink droplets are ejected onto a solid or semi-solid aggregation processing agent layer formed on the surface of the recording medium 114, ink aggregates (coloring material aggregates) are formed on the recording medium 114. At the same time, the ink solvent separated from the color material spreads to form a liquid layer in which the aggregation treatment agent is dissolved. In this way, the solvent component (liquid component) remaining on the recording medium 114 causes not only curling of the recording medium 114 but also image degradation. Therefore, in this example, after the corresponding color inks are ejected onto the recording medium 114 from the respective ink ejection heads 140C, 140M, 140Y, and 140K, the solvent components are dried by the hot air dryers of the solvent drying units 142a and 142b. Is evaporated and dried.

  A fixing unit 110 is provided following the ink ejection unit 108. A transfer drum 124d is provided between the pressure drum (drawing drum) 126c of the ink droplet ejection unit 108 and the pressure drum (fixing drum) 126d of the fixing unit 110 so as to be in contact therewith. As a result, the recording medium 114 held on the pressure drum 126c of the ink droplet ejection unit 108 is delivered to the pressure drum 126d of the fixing unit 110 via the transfer drum 124d after each color ink is applied.

[Fixing part]
In the fixing unit 110, print detection is performed by reading the print result of the ink droplet ejection unit 108 at a position facing the surface of the pressure drum 126d in order from the upstream side in the rotation direction of the pressure drum 126d (counterclockwise direction in FIG. 16). A portion 144 and heating rollers 148a and 148b are provided.

  The print detection unit 144 is a reading unit that reads an output image, and includes an image sensor for imaging a print result of the ink droplet ejection unit 108 (a droplet ejection result of each ink droplet ejection head 140C, 140M, 140Y, 140K). It functions as a means for checking nozzle clogging and other ejection defects from a droplet ejection image read by the image sensor, or as a colorimetric means for acquiring color information.

  In this example, a test pattern based on a line pattern, a density pattern, or a combination thereof is formed in an image recording area or a non-image area (so-called blank area) of the recording medium 114, and the test pattern is read by the print detection unit 144. Based on the reading result, inline detection is performed such as acquisition of color information (colorimetry), detection of density unevenness, and determination of the presence or absence of ejection abnormality for each nozzle.

  The heating rollers 148a and 148b are rollers capable of controlling the temperature within a predetermined range (for example, 100 ° C. to 180 ° C.), and heat the recording medium 114 sandwiched between the heating rollers 148a and 148b and the impression cylinder 126d. While pressing, the image formed on the recording medium 114 is fixed. The heating temperature of the heating rollers 148a and 148b is preferably set according to the glass transition temperature of the polymer fine particles contained in the treatment liquid or ink.

  In addition, it may replace with the ink containing the high boiling point solvent and the thermoplastic resin particle, and may contain the monomer component which can be polymerized and hardened by UV exposure. In this case, the inkjet recording apparatus 100 includes a UV exposure unit that exposes the ink on the recording medium 114 to UV light instead of the heat-pressure fixing unit using a heat roller. In this way, when ink containing an actinic ray curable resin such as a UV curable resin is used, an actinic ray is irradiated, such as a UV lamp or an ultraviolet LD (laser diode) array, instead of a fixing roller for heat fixing. Means are provided.

[Paper output section]
Subsequent to the fixing unit 110, a paper discharge unit 112 is provided. The paper discharge unit 112 includes a paper discharge drum 150 that receives the recording medium 114 on which an image is fixed, a paper discharge tray 152 on which the recording medium 114 is loaded, and a sprocket and a paper discharge tray 152 provided on the paper discharge drum 150. And a paper discharge chain 154 provided with a plurality of paper discharge grippers. Although the details of the paper transport mechanism by the paper discharge chain 154 are not shown, the recording medium 114 after printing is held at the leading edge of the paper by a gripper of a bar (not shown) passed between the endless paper discharge chains 154. Then, the sheet is transported above the sheet discharge table 152 by the rotation of the sheet discharge chain 154.

<Head structure>
Next, the structure of the head will be described. Since the structures of the respective heads 140C, 140M, 140Y, and 140K are common, the heads will be represented by the reference numeral 250 in the following.

  FIG. 17A is a plan perspective view showing an example of the structure of the head 250, and FIG. 17B is an enlarged view of a part thereof. 18 is a perspective plan view showing another structural example of the head 250, and FIG. 19 is a three-dimensional configuration of one-channel droplet discharge elements (ink chamber units corresponding to one nozzle 251) serving as recording element units. FIG. 18 is a cross-sectional view (a cross-sectional view taken along line AA in FIG. 17).

  As shown in FIG. 17, in the head 250 of this example, the head 250A and the head 250B (corresponding to the first nozzle row and the second nozzle row) are along the y direction (the conveyance direction of the recording medium 114). Dual heads arranged in order. The head 250A and the head 250B each have a matrix of a plurality of ink chamber units (droplet discharge elements) 253 including nozzles 251 which are ink discharge ports for discharging the same color ink, and pressure chambers 252 corresponding to the nozzles 251. In this way, the density of the substantial nozzle interval (projection nozzle pitch) projected (orthogonal projection) so as to be aligned along the x direction is achieved.

  In each nozzle of the head 250A, a nozzle group for ejecting odd pixels on the recording medium 114 is disposed in the area A-odd, and a nozzle group for recording even pixels is disposed in the area A-even. In addition, each nozzle of the head 250 </ b> B has a nozzle group for ejecting odd pixels on the recording medium 114 disposed in the area B-odd and a nozzle group for recording even pixels in the area B-even.

  These four areas are arranged in the order of B-odd, B-even, A-even, and A-odd from the upstream side in the conveyance direction of the recording medium 114. Note that B-even, B-odd, A-odd, and A-even may be arranged in this order, or the head 250A and the head 250B are interchanged, and A-odd, A-even, B-even, B- You may arrange | position in order of odd, A-even, A-odd, B-odd, and B-even.

  The nozzles 251 of the head 250A and the nozzles 251 of the head 250B are arranged so as to overlap on the same straight line parallel to the y direction.

  Furthermore, the heads 250A and 250B are configured to be relatively movable in the x direction. Here, the head 250A is fixed, and the head 250B can be moved in the x direction by a piezo actuator (not shown, corresponding to moving means). The moving means for moving the head 250B is not particularly limited.

  The printable range in the x direction of the recording medium 114 in the head 250 is a range where the printable range in the x direction of the head 250A (the range in which the nozzles 251 are disposed) and the printable range in the x direction of the head 250B overlap. . Therefore, it is preferable that the head 250B configured to be movable in the x direction has an extra nozzle in the x direction. As the number of surplus nozzles increases, the moving range of the head 250B in the x direction can be expanded while keeping the recordable range of the head 250A as the recordable range of the recording medium 114.

  In the example illustrated in FIG. 17, the head 250 </ b> B includes 12 extra nozzles (nozzle group 260 surrounded by a broken line) at both ends in the x direction. Therefore, if the moving range of the head 250B is a range of 12 nozzles on the left and right in the x direction (12 raster lines), the printable range in the x direction in the head 250 can be made constant.

  Here, the head 250B is configured to be movable in the x direction. However, when the head 250A is configured to be movable in the x direction, it is preferable that the head 250A also includes an extra nozzle 251 in the x direction. . Thus, by providing an extra nozzle for the movable head, it is possible to widen the moving range of the head while keeping the recordable range constant.

  In addition, the form which comprises the nozzle row more than the length corresponding to the full width Wm of the drawing area | region of the recording medium 114 in the direction (x direction) substantially orthogonal to ay direction is not limited to this example. For example, instead of the configuration of FIG. 17A, as shown in FIG. 18A, short sub-heads 250 ′ in which a plurality of nozzles 251 are two-dimensionally arranged are arranged in a staggered manner and connected together. A mode of configuring the heads 250A and 250B having nozzle rows having a length corresponding to the entire width of the recording medium 114, or a head 250A ″ formed by connecting the sub-heads 250 ″ in a line as shown in FIG. 18B. There is also an aspect to do.

  These sub-heads are preferably configured to be movable in the x direction as described with reference to FIG. In this case, it is necessary to provide extra nozzles (nozzle groups 260 ′ and 260 ″ surrounded by broken lines) in the x direction of each sub head.

  The pressure chamber 252 provided corresponding to each nozzle 251 has a substantially square planar shape (see FIGS. 17A and 17B), and the nozzle 251 is provided at one of the diagonal corners. An outlet for supplying ink (supply port) 254 is provided on the other side. Note that the shape of the pressure chamber 252 is not limited to this example, and the planar shape may have various forms such as a quadrangle (rhombus, rectangle, etc.), a pentagon, a hexagon, other polygons, a circle, and an ellipse. As shown in FIG. 19, the head 250 has a structure in which a nozzle plate 251A in which nozzles 251 are formed and a flow path plate 252P in which flow paths such as a pressure chamber 252 and a common flow path 255 are formed are laminated and joined. . The nozzle plate 251A constitutes a nozzle surface (ink ejection surface) 250A of the head 250, and a plurality of nozzles 251 communicating with the pressure chambers 252 are two-dimensionally formed.

  The flow path plate 252P forms a side wall of the pressure chamber 252 and a flow path that forms a supply port 254 as a narrowed portion (most narrowed portion) of an individual supply path that guides ink from the common flow path 255 to the pressure chamber 252. It is a forming member. For convenience of explanation, the flow path plate 252P has a structure in which one or a plurality of substrates are stacked, although it is simply illustrated in FIG.

  The nozzle plate 251A and the flow path plate 252P can be processed into a required shape by a semiconductor manufacturing process using silicon as a material.

  The common flow channel 255 communicates with an ink tank (not shown) as an ink supply source, and ink supplied from the ink tank is supplied to each pressure chamber 252 via the common flow channel 255.

  A piezoelectric actuator 258 having an individual electrode 257 is joined to a diaphragm 256 that constitutes a part of the pressure chamber 252 (the top surface in FIG. 19). The diaphragm 256 of this example is made of silicon (Si) with a nickel (Ni) conductive layer functioning as a common electrode 259 corresponding to the lower electrode of the piezoelectric actuator 258, and is arranged corresponding to each pressure chamber 252. It also serves as a common electrode for the actuator 258. It is also possible to form the diaphragm with a non-conductive material such as resin. In this case, a common electrode layer made of a conductive material such as metal is formed on the surface of the diaphragm member. Moreover, you may comprise the diaphragm which serves as a common electrode with metals (conductive material), such as stainless steel (SUS).

  By applying a driving voltage to the individual electrode 257, the piezo actuator 258 is deformed and the volume of the pressure chamber 252 is changed, and ink is ejected from the nozzle 251 due to the pressure change accompanying this. When the piezo actuator 258 returns to its original state after ink ejection, new ink is refilled into the pressure chamber 252 from the common channel 255 through the supply port 254.

  As shown in FIG. 17B, the ink chamber unit 253 having such a structure is fixed for each of the areas A-odd, A-even, B-odd, and B-even. The high-density nozzle head of this example is realized by arranging a large number in a grid pattern with a constant arrangement pattern along an oblique row direction having an angle θ. In such a matrix arrangement, when the interval between adjacent nozzles in the y direction is Ls, in the x direction, each nozzle 251 is handled in an equivalent manner as a substantially linear arrangement with a constant pitch 2L = Ls / tan θ. Can do.

  Further, in the region A-odd and the region A-even, the positions of the nozzles are shifted by a half pitch (L) in the x direction. As a result, the head 250A can be handled equivalently to the nozzles 251 arranged in a straight line with a pitch L in the x direction.

  Similarly, the region B-odd and the region B-even are arranged such that the positions of the nozzles are shifted by a half pitch (L) in the x direction. Therefore, the head 250B can also be handled equivalently as the nozzles 251 arranged in a straight line with the pitch L in the x direction.

  As described above, the head 250B is configured to be movable in the x direction. However, the movement stop position is on the same straight line in which each nozzle 251 of the head 250A and each nozzle 251 of the head 250B are parallel to the y direction. It will be a position that overlaps. That is, the movement unit of the head 250B is a substantial nozzle pitch L (= raster line interval).

  Further, in this embodiment, the arrangement form of the nozzles 251 in the head 250 is not limited to the illustrated example, and various nozzle arrangement structures can be applied as long as they are within the nozzle group region that ejects odd pixels and even pixels. For example, instead of the matrix array described in FIG. 17, a linear array of lines, a V-shaped nozzle array, and a zigzag (W-shaped) nozzle array having a V-shaped array as a repeating unit. Etc. are also possible.

  The means for generating the discharge pressure (discharge energy) for discharging the droplets from each nozzle in the inkjet head is not limited to the piezo actuator (piezoelectric element), but the thermal method (the pressure of film boiling due to the heating of the heater) Various pressure generating elements (energy generating elements) such as heaters (heating elements) and other actuators based on other systems can be applied. Corresponding energy generating elements are provided in the flow path structure according to the ejection method of the head.

<Description of control system>
FIG. 20 is a principal block diagram showing the system configuration of the inkjet recording apparatus 100. The inkjet recording apparatus 100 includes a communication interface 170, a system controller 172, a memory 174, a motor driver 176, a heater driver 178, a print control unit 180, an image buffer memory 182, a head driver 184, and the like.

  The communication interface 170 is an interface unit (corresponding to a data acquisition unit) that receives image data sent from the host computer 186. As the communication interface 170, a serial interface such as USB (Universal Serial Bus), IEEE 1394, Ethernet (registered trademark), a wireless network, or a parallel interface such as Centronics can be applied. In this part, a buffer memory (not shown) for speeding up communication may be mounted. Image data sent from the host computer 186 is taken into the inkjet recording apparatus 100 via the communication interface 170 and temporarily stored in the memory 174.

  The memory 174 is a storage unit that temporarily stores an image input via the communication interface 170, and data is read and written through the system controller 172. The memory 174 is not limited to a memory made of a semiconductor element, and a magnetic medium such as a hard disk may be used.

  The system controller 172 includes a central processing unit (CPU) and its peripheral circuits, and functions as a control device that controls the entire inkjet recording apparatus 100 according to a predetermined program, and also functions as an arithmetic device that performs various calculations. . That is, the system controller 172 controls the communication interface 170, the memory 174, the motor driver 176, the heater driver 178, and the like, performs communication control with the host computer 186, read / write control of the memory 174, etc. A control signal for controlling the motor 188 and the heater 189 is generated.

  The memory 174 stores programs executed by the CPU of the system controller 172 and various data necessary for control. Note that the memory 174 may be a non-rewritable storage unit or a rewritable storage unit such as an EEPROM. The memory 174 is used as a temporary storage area for image data, and is also used as a program development area and a calculation work area for the CPU.

  Various control programs are stored in the program storage unit 190, and the control programs are read and executed in accordance with instructions from the system controller 172. The program storage unit may use a semiconductor memory such as a ROM or an EEPROM, or may use a magnetic disk or the like. An external interface may be provided and a memory card or PC card may be used. Of course, you may provide several recording media among these recording media. Note that the program storage unit may also be used as a storage means such as operation parameters.

  The motor driver 176 is a driver that drives the motor 188 in accordance with instructions from the system controller 172. In FIG. 20, a motor (actuator) arranged in each part in the apparatus is represented by reference numeral 188. For example, the motor 188 shown in FIG. 20 includes a motor for driving the pressure drums 126a to 126d, the transfer drums 124a to 124d and the paper discharge drum 150 in FIG. 16, the head 40 in FIG. 7, and the head 250B in FIG. And a motor for shifting in the x direction.

  The heater driver 178 is a driver that drives the heater 189 in accordance with an instruction from the system controller 172. In FIG. 20, a plurality of heaters provided in the ink jet recording apparatus 100 are represented by reference numeral 189. For example, the heater 189 shown in FIG. 20 includes the paper preheating units 128 and 134, the permeation suppression agent drying unit 132, the treatment liquid drying unit 138, the solvent drying units 142a and 142b, and the heating rollers 148a and 148b shown in FIG. A built-in heater is included.

  The print control unit 180 (corresponding to a recording unit) has a signal processing function for performing various processes such as processing and correction for generating a print control signal from image data in the memory 174 in accordance with the control of the system controller 172. The control unit distributes the generated print data (dot data) to each head of the dual head and supplies it to the head driver 184.

  Necessary signal processing is performed in the print control unit 180, and the ejection amount and ejection timing of the ink droplets of the head 250 are controlled via the head driver 184 based on the image data. Thereby, a desired dot size and dot arrangement are realized. In this way, the print controller 180 records each pixel of the image data with the head 250A and the head 250B.

  The print control unit 180 is provided with an image buffer memory 182, and image data, parameters, and other data are temporarily stored in the image buffer memory 182 when image data is processed in the print control unit 180. Also possible is an aspect in which the print controller 180 and the system controller 172 are integrated and configured with one processor.

  Furthermore, each processing block for realizing the processing of the flowchart shown in FIG.

  FIG. 21 is a block diagram illustrating an internal configuration of the print control unit 180. As shown in the figure, the print control unit 180 includes a non-ejection nozzle data storage unit 201, a non-ejection nozzle coordinate conversion unit 202, a difference calculation unit 203, a shift amount candidate extraction unit 204, a shift amount determination unit 205, and a head control unit. 206, a data shifting unit 207, and the like.

  The non-ejection nozzle data storage unit 201 (corresponding to a storage unit) stores information such as the position in the head of a nozzle (non-ejection nozzle) that cannot eject ink. In addition, even when defective nozzles such as bent nozzles, nozzles with different droplet amounts, and splash nozzles are made non-ejecting (ink ejection is stopped), information such as the position of these non-ejecting nozzles in the head is stored. To do.

  Information on the non-ejection nozzle positions of both the A and B heads in step S1 of the flowchart shown in FIG. 9 is stored in the non-ejection nozzle data storage unit 201.

  The non-ejecting nozzle coordinate conversion unit 202 acquires information on non-ejecting nozzles of each head of the dual head from the non-ejecting nozzle data storage unit 201 (corresponding to a defective recording element information acquisition unit), and the positions of the non-ejecting nozzles are unified. To a position in a single coordinate system. The process of step S2 in the flowchart shown in FIG.

  A difference calculation unit 203 (corresponding to a calculation unit) calculates a difference between the non-ejection nozzle positions of the heads based on the positions of the non-ejection nozzles of the dual heads converted by the non-ejection nozzle coordinate conversion unit 202. . The difference calculation unit 203 performs the process of step S3 in the flowchart illustrated in FIG.

  The shift amount candidate extraction unit 204 (corresponding to the extraction unit) calculates an integer value not included in these values as a shift amount candidate for the difference calculated by the difference calculation unit 203. Further, a shift amount determination unit 205 (corresponding to a shift amount determination unit) determines a shift amount from the shift amount candidates extracted by the shift amount candidate extraction unit 204. The process of step S4 in the flowchart shown in FIG. 9 is performed by the shift amount candidate extraction unit 204 and the shift amount determination unit 205.

  The head control unit 206 (corresponding to the control means) gives the shift amount determined by the shift amount determination unit 205 between the dual heads via the system controller 172 and the motor driver 176. The head control unit 206 performs the process of step S5 of the flowchart shown in FIG.

  The data shifting unit 207 (corresponding to the data moving unit) gives the shift amount determined by the shift amount determining unit 205 to the data of the shifted head. That is, the image data in the memory 174 is subjected to signal processing, and the generated dot data is distributed to the head 250A and the head 250B. Then, the data of the head 250B is shifted by the shift amount determined by the shift amount determination unit 205. Further, as a result of shifting the data, the position of the non-ejection nozzle corresponding to each raster line changes, so the data corresponding to the non-ejection nozzle is redistributed to the head 250A and the head 250B and supplied to the head driver 184. The process of step S6 in the flowchart shown in FIG.

  An overview of the processing flow from image input to print output is as follows. Image data to be printed is input from the outside via the communication interface 170 and stored in the memory 174. At this stage, for example, RGB multivalued image data is stored in the memory 174.

  The original image (RGB) data stored in the memory 174 is sent to the print control unit 180 via the system controller 172, and the print control unit 180 uses the halftoning process using a threshold matrix, an error diffusion method, etc. It is converted into dot data (binary data or multi-value data including dot size information) for each color (K, C, M, Y). When a relative shift amount is given between the dual heads, data is generated according to the shift amount.

  Thus, the dot data generated by the print control unit 180 is stored in the image buffer memory 182. The dot data for each color is converted into CMYK droplet ejection data for ejecting ink from the nozzles of the head 250, and the ink ejection data to be printed is determined.

  The head driver 184 sets the piezoelectric elements (actuators 258 in FIG. 16) corresponding to the nozzles 251 of the head 250 based on print data (that is, dot data stored in the image buffer memory 182) given from the print control unit 180. A drive signal for driving is output. The head driver 184 may include a feedback control system for keeping the head driving condition constant.

  The ink jet recording apparatus 100 shown in this example applies a common drive waveform signal to each piezoelectric element corresponding to a plurality of nozzles belonging to the same nozzle group block divided into M, and at the ejection timing of each piezoelectric element (actuator 258). Accordingly, a piezoelectric drive method is applied in which ink is ejected from the nozzle corresponding to each piezoelectric element by switching on and off the switch element connected to the individual electrode of each piezoelectric element.

  The print detection unit 144 is a block including a CCD line sensor, reads an image printed on the recording medium 114, performs necessary signal processing, etc., and performs printing status (color, density, presence / absence of ejection, variation in droplet ejection, etc.) ) And the detection result is provided to the print controller 180 via the system controller 172.

  The print control unit 180 functions as a defective recording element information acquisition unit that determines ejection abnormal nozzles based on information obtained from the print detection unit 144. Examples of abnormal ejection nozzles include non-ejection nozzles, nozzles with large bends, nozzles with small ejection amounts, and nozzles with large splashes.

  The print control unit 180 stores non-ejection nozzle position information and the like in the non-ejection nozzle data storage unit 201. Further, when ejection failure nozzles other than the ejection failure nozzles are ejected, position information of the ejection failure nozzles and the like are also stored.

  In addition, a control signal may be sent to each unit via the system controller 172 so that a nozzle recovery operation such as preliminary discharge or suction is performed on the abnormal discharge nozzle.

[Printing operation by inkjet recording device]
Next, the operation of the inkjet recording apparatus 100 configured as described above will be described.

  The recording medium 114 is sent out from the paper supply stand 120 of the paper supply unit 102 to the feeder board 122. The recording medium 114 is held by the pressure drum 126a of the permeation suppression agent applying unit 104 via the transfer drum 124a, preheated by the paper preheating unit 128, and the permeation suppression agent is ejected by the permeation suppression agent discharge head 130. . Thereafter, the recording medium 114 held on the impression cylinder 126a is heated by the permeation suppression agent drying unit 132, and the solvent component (liquid component) of the permeation suppression agent is evaporated and dried.

  The recording medium 114 thus subjected to the permeation suppression process is transferred from the pressure drum 126a of the permeation suppression agent applying unit 104 to the pressure drum 126b of the processing liquid application unit 106 via the transfer cylinder 124b. The recording medium 114 held on the pressure drum 126 b is preheated by the paper preheating unit 134, and the processing liquid is ejected by the processing liquid discharge head 136. Thereafter, the recording medium 114 held on the pressure drum 126b is heated by the treatment liquid drying unit 138, and the solvent component (liquid component) of the treatment liquid is evaporated and dried. Thereby, a solid or semi-solid aggregation treatment agent layer is formed on the recording medium 114.

  The recording medium 114 to which the treatment liquid is applied to form a solid or semi-solid aggregation treatment agent layer is formed on the recording medium 114 from the pressure drum 126b of the treatment liquid application section 106 through the transfer cylinder 124c. It is delivered to the trunk 126c. Corresponding color inks are ejected from the heads 140C, 140M, 140Y, and 140K to the recording medium 114 held on the impression cylinder 126c in accordance with the input image data.

  When the ink droplet lands on the aggregation treatment agent layer, the contact surface between the ink droplet and the aggregation treatment agent layer lands in a predetermined area due to the balance between the flight energy and the surface energy. The aggregation reaction starts immediately after the ink droplets land on the aggregation treatment agent, but the aggregation reaction starts from the contact surface between the ink droplets and the aggregation treatment agent layer. The agglomeration reaction occurs only in the vicinity of the contact surface, and the color material in the ink is agglomerated in a state where the adhesive force is obtained with a predetermined contact area at the time of ink landing, so that the color material movement is suppressed.

  Even if other ink droplets land adjacent to this ink droplet, the color material of the ink that has landed first is already agglomerated, so the color materials do not mix with the ink that landed later, Bleed is suppressed. Note that after the color material is aggregated, the separated ink solvent spreads, and a liquid layer in which the aggregation treatment agent is dissolved is formed on the recording medium 114.

  The recording medium 114 held on the impression cylinder 126c is heated by the solvent drying units 142a and 142b, and the solvent component (liquid component) separated from the ink aggregates on the recording medium 114 is evaporated and dried. As a result, curling of the recording medium 114 can be prevented and image quality deterioration due to the solvent component can be suppressed.

  The recording medium 114 to which the color ink is applied by the ink droplet ejection unit 108 is transferred from the pressure drum 126c of the ink droplet ejection unit 108 to the pressure drum 126d of the fixing unit 110 through the transfer drum 124d. The recording medium 114 held on the impression cylinder 126d is heated and pressed by the heating rollers 148a and 148b after the printing result of the ink ejection unit 108 is read by the printing detection unit 144.

  Further, after that, the recording medium 114 is transferred from the pressure drum 126 d to the paper discharge drum 150 and conveyed to the paper discharge tray 152 by the paper discharge chain 154. The recording medium 114 on which the image has been formed in this manner is transported above the paper discharge table 152 by the paper discharge chain 154 and stacked on the paper discharge table 152.

  As described above, according to the present embodiment, even when the positions of the non-ejection nozzles of the dual head are overlapped, the shift amount is definitely determined, and the state where the positions of the defective recording elements do not coincide with each other is ensured. Can be produced.

  In addition, a mode in which the functions of the print control unit 180 and the system controller 172 are installed in the host computer 186 and other computers and non-ejection correction processing is performed is also possible. Further, a program for realizing these processes by a computer is recorded on a CD-ROM, a magnetic disk or other recording medium, and the program is provided to a third party through the recording medium, or the program is transmitted through a communication line such as the Internet. It is also possible to provide a download service.

  In the above embodiment, the case where the present invention is applied to an ink jet recording apparatus has been described. However, the scope of the present invention is not limited to this. That is, the present invention relates to an image recording apparatus of a type other than an ink jet recording apparatus, for example, a thermal transfer recording apparatus having a recording head having a thermal element as a recording element, and an LED electrophotography having a recording head having an LED element as a recording element. The present invention is also applicable to a printer and a silver halide photographic printer having an LED line exposure head.

  The technical scope of the present invention is not limited to the scope described in the above embodiment. The configurations and the like in the respective embodiments can be appropriately combined among the respective embodiments without departing from the spirit of the present invention.

  DESCRIPTION OF SYMBOLS 10,100 ... Inkjet recording device 20, 22, 24 ... Line head, 30, 40, 250 ... Head, 30e, 30o, 40e, 40o, A-even, A-odd, B-even, B-odd ... area , 250 ', 250 "... sub head, 251 ... nozzle, 260', 260" ... nozzle group

Claims (11)

A recording head having a first nozzle row and a second nozzle row for printing the same color, wherein the first nozzle row and the second nozzle row have the same nozzle recording pitch in the first direction. A recording head in which each nozzle of the first nozzle row and each nozzle of the second nozzle row are arranged on a straight line parallel to a second direction orthogonal to the first direction; ,
Conveying means for conveying at least one of the recording head and the recording medium to relatively move the recording head and the recording medium in the second direction;
Data acquisition means for acquiring image data to be recorded by the recording head;
Distribution means for mutually distributing the image data to the respective nozzles of the first nozzle row and the second nozzle row;
Recording means for recording the distributed image data by the recording head;
With
The first nozzle row and the second nozzle row are respectively a first region to which nozzles that record odd-numbered pixels counted from one side in the first direction belong, and nozzles that record even-numbered pixels. A second region to which
The recording head includes a first region of the first nozzle row, a second region of the first nozzle row, a second region of the second nozzle row from the upstream side along the second direction. Region, first region of the second nozzle row, or second region of the first nozzle row, first region of the first nozzle row, first of the second nozzle row. Are arranged in the order of the second region of the second nozzle row ,
The distribution unit alternately distributes the pixels in the first direction to the nozzles of the first nozzle row and the nozzles of the second nozzle row and distributes the pixels in the second direction to the first. An inkjet recording apparatus that alternately distributes the nozzles of the nozzle row and the nozzles of the second nozzle row . In each of the first nozzle row and the second nozzle row, nozzles are arranged over a length corresponding to the full recordable width in the first direction of the recording medium,
The inkjet recording apparatus according to claim 1, wherein the transport unit relatively moves the recording head and the recording medium in the second direction only once. Comprising defective nozzle information acquisition means for acquiring information on positions of defective nozzles in the first nozzle row and the second nozzle row;
The distribution unit distributes data corresponding to the defective nozzles of the first nozzle row to the nozzles of the second nozzle row based on the position information of the defective nozzles, and the second nozzle row is defective. an ink jet recording apparatus according to claim 1 or 2 distributes the data corresponding to the nozzle to the nozzle of the first nozzle row. A relative shift amount of the first nozzle row and the second nozzle row in the first direction based on information on a position of a defective nozzle in the first nozzle row and the second nozzle row; A shift amount determining means for determining a shift amount for causing at least one of the nozzles arranged on a straight line parallel to the second direction to correspond to a nozzle that is not a defective nozzle;
Moving means for moving relative positions of the first nozzle row and the second nozzle row;
Control means for relatively shifting the first nozzle row and the second nozzle row by the determined shift amount by the moving means;
Data moving means for shifting the image data distributed by the distributing means by the determined shift amount;
An ink jet recording apparatus according to claim 3 . Conversion means for converting the position of each defective nozzle into the position of one coordinate system from the information on the position of the defective nozzle in the first nozzle array and the second nozzle array;
Calculating means for calculating a difference between a position of a defective nozzle in one nozzle row and a position of a defective nozzle in another nozzle row of the first nozzle row and the second nozzle row;
Extraction means for extracting a shift amount candidate from the calculated difference;
With
The inkjet recording apparatus according to claim 4 , wherein the shift amount determination unit determines a value closest to 0 from among the extracted shift amount candidates as a shift amount. The inkjet recording apparatus according to claim 5 , wherein the calculation unit calculates a difference in the position within a movable range of the moving unit. The shift amount determining means, an ink jet recording apparatus according to claim 5 or 6 for determining the amount of shifting the periodic different values from among the candidates of the extracted shift amount. At least one of the first nozzle row and the second nozzle row is composed of a plurality of sub nozzle rows arranged in the first direction,
The shift amount determining means determines the shift amount for each sub nozzle row,
The moving means is provided for each sub nozzle row,
It said control means is an ink jet recording apparatus according to any one of claims 4 to 7 to shift the sub-nozzle arrays on the basis of the shift amount of the determined. The defective nozzle information obtaining means, faulty nozzle can not discharge ink, or bending the nozzle, droplet amount different nozzles, a malfunctioning nozzle that includes a splash nozzle claims 4 to acquire information on the position of the nozzles misfiring of 8 The inkjet recording apparatus according to any one of the above. The ink jet recording apparatus according to any one of the first nozzle row and the second claims 3 to 9 which includes a storage means for storing information on the position of the defective nozzle of the nozzle array. The inkjet recording according to any one of claims 4 to 9 , wherein the nozzle row that is moved by the moving unit among the first nozzle row and the second nozzle row has an extra nozzle in the first direction. apparatus.

Images