JP2006116730A - Inkjet printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet printer which can precisely carry out control of a discharge timing in a main scanning direction when it has a plurality of head units along a sub scanning direction. <P>SOLUTION: The inkjet printer has the head units 41, 42 and 43 with a plurality of ink nozzles set along the sub scanning direction, a unit support 32 for setting and supporting a plurality of the head units 41, 42 and 43 along the sub scanning direction, and an adjusting means 56 for adjusting an ink discharge timing in the main scanning direction among the plurality of head units 41, 42 and 43. The adjusting means 56 adjusts the discharge timing based on ink nozzles 411a and 421a corresponding to the head units 41 and 42 located at the upstream side and the downstream side in the sub scanning direction. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention provides a head unit provided with a plurality of ink nozzles along the sub-scanning direction, a unit support for mounting and supporting a plurality of head units along the sub-scanning direction, and between the plurality of head units. The present invention relates to an ink jet printer including an adjusting unit for adjusting an ink discharge timing in a main scanning direction.

  An ink jet printer includes a head unit having ink nozzles for ejecting ink, and transports paper (image forming medium) on which an image is formed in the sub-scanning direction and scans the head unit in the main scanning direction. By repeating, an image is formed (for example, Patent Documents 1 and 2 below). The head unit is provided with a plurality of ink nozzles (nozzle rows) along the sub-scanning direction. When a color image is formed, a plurality of rows (for example, seven rows for seven colors) are formed along the main scanning direction. ) Nozzle rows are provided.

  On the other hand, in order to form an image at high speed, an ink jet printer in which a plurality of head units are provided along the sub-scanning direction is known (for example, Patent Document 3 below). FIG. 8 shows a configuration example when a plurality of head units are provided in the sub-scanning direction. As shown in FIG. 8, the downstream head unit 100 and the upstream head unit 200 are attached to and supported by a unit support 150 along the sub-scanning direction. These head units 100 and 200 have the same configuration, and are provided with seven nozzle rows 101, 102... 107, 201, 202. A number of ink nozzles 101a, 101b... 101n, 201a, 201b... 201n are formed in each nozzle row along the sub-scanning direction. One row of ink nozzles ejects the same color ink, and the corresponding upstream and downstream nozzle rows (101 and 201, 102 and 202,... 107 and 207) eject the same color ink. It is configured. Thus, by providing a plurality of head units along the sub-scanning direction, it becomes possible to perform image formation at high speed.

  When performing image formation by providing a plurality of head units 100 and 200, it is necessary to attach the head units 100 and 200 to the support 150 with high accuracy. When the head units 100 and 200 are attached to the support 150, an XY table or the like is used so that the nozzle row is parallel to a reference line L (conceptually shown in FIG. 8) formed on the support 150. And attach while visually adjusting mechanically. The head units 100 and 200 are provided with adjustment long holes 110 and 210, and when the adjustment position is determined, the head units 100 and 200 are fastened to the support 150 with screws 111 and 211.

  In this way, the head units 100, 200 are attached to the support 150, and the nozzle rows 101, 201,... Are assembled in parallel with the reference line L.

  However, even if each nozzle row is assembled so as to be parallel, the attachment error in the main scanning direction between the corresponding nozzle rows remains. That is, in the main scanning direction of the nozzle row 101 and the nozzle row 201, an attachment error Δx remains as shown in FIG. Accordingly, since the image quality is adversely affected as it is, the downstream head unit 100 and the upstream head unit 200 are electronically controlled to shift the ink ejection timing by the number of dots corresponding to Δx. Is going.

  In addition, when measuring the specific magnitude | size of (DELTA) x, there exists the method by a test print, for example. A predetermined test print can be created by actually ejecting ink from the ink nozzles, and the magnitude of Δx can be determined based on this.

  In this case, the discharge timing is controlled after obtaining Δx with reference to the nozzles closest to each other, that is, the nozzle 101n at the rear end of the upstream head unit 100 and the nozzle 201a at the front end of the downstream head unit 200. I was doing. That is, the ink discharge timing is shifted by the number of dots corresponding to Δx (the difference in distance between the ink nozzles 101n and 201a) between the ink nozzle group belonging to the upstream side and the ink nozzle group belonging to the downstream side. The reason why close nozzles are used as a reference is that if Δx is determined between distant ink nozzles, it is believed that the accuracy of the measured Δx is reduced due to the oblique conveyance of paper and the like. .

However, when the closest nozzles are used as a reference, the following problems occur. That is, the head units 100 and 200 are attached to the support 150, and are attached after mechanical adjustment when the support 150 is attached to a main body frame (not shown). As a result, an attachment error of the support 150 itself occurs, and the entire support 150 may be assembled in an inclined state as shown in FIG. 9B. As a result, the deviation A in the main scanning direction between the upstream nozzle 101a on the upstream side and the downstream nozzle 201n on the downstream side is larger than Δx, which adversely affects image quality.
Japanese Patent Laid-Open No. 2001-10065 JP 2001-187448 A JP-A-6-191057

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an ink jet printer that can accurately control ejection timing in the main scanning direction when a plurality of head units are provided along the sub scanning direction. Is to provide.

In order to solve the above problems, an ink jet printer according to the present invention provides:
A head unit provided with a plurality of ink nozzles along the sub-scanning direction;
A unit support for mounting and supporting a plurality of head units along the sub-scanning direction;
Adjusting means for adjusting the ink discharge timing in the main scanning direction between the plurality of head units,
The adjusting means adjusts the ejection timing with reference to corresponding ink nozzles between the head units located on the upstream side and the downstream side in the sub-scanning direction.

  The operation and effect of the ink jet printer having this configuration will be described. A plurality of head units are attached and supported to the unit support along the sub-scanning direction. Further, the adjustment unit electronically adjusts the ink ejection timing in the main scanning direction between the plurality of head units. In this case, the adjustment is performed based on the ink nozzles corresponding to the head units located on the upstream side and the downstream side. Here, “corresponding ink nozzle” refers to, for example, the leading end nozzle of the upstream head unit and the leading end nozzle of the downstream head unit, the trailing end nozzle of the upstream head unit, the trailing end nozzle of the downstream head unit, the upstream This refers to the second (nth) nozzle from the tip of the side head unit and the second (nth) nozzle from the tip of the downstream head unit.

  For example, when the front end nozzles are used as a reference, as shown in FIG. 10, the difference between the timing adjustment amount Δx and the amount of deviation A between the front end nozzle 101a and the rear end nozzle 201n is compared with the case of FIG. 9B. Can be suppressed. Therefore, it is possible to provide an ink jet printer that can suppress deterioration in image quality and can accurately control ejection timing in the main scanning direction.

  A preferred embodiment of an ink jet printer according to the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing an internal configuration of the ink jet printer.

<Printer configuration>
As shown in FIG. 1, a supply unit U1, a print unit U2, a loop forming unit U3, a cutter unit U4, a reversing unit U5, and a discharge unit U6 are provided in this order from the upstream side along the conveyance path. A paper magazine 1 containing paper P (corresponding to an image forming medium) in a roll shape is detachably attached to the apparatus main body. For example, two paper magazines 1 containing papers having different width dimensions can be attached, and when image formation is performed, the paper P is pulled out from one of the paper magazines 1 and conveyed. While the paper P is transported along the transport path in the sub-scanning direction, the print head 10 is scanned in the main scanning direction (a direction perpendicular to the sub-scanning direction and a direction perpendicular to the paper surface of FIG. 1). An image is formed on the paper surface based on the data. Thereafter, the paper P on which the image has been formed is conveyed from the loop forming unit U3 to the cutter unit U4 and cut into a predetermined print size. Thereafter, the sheet is fed to the transport belt 2 or the rack plate 3 by the reversing unit U5 and the discharge unit U6.

  The supply unit U1 includes a support roller 1a and a supply roller 1b, and sends out the paper P to the downstream side. The print unit U2 includes a guide mechanism 13 for reciprocally driving the print head 10 as shown in FIG. 1 along the main scanning direction. The guide mechanism 13 includes a guide groove 11 on the print head 10 side and a guide rail 12 on the main body frame side. Note that the relationship between the guide groove and the guide rail may be reversed. As a drive mechanism for driving the print head 10 in the main scanning direction, the print head 10 includes a pulley 14 and a drive belt 15 wound around the pulley 14, and the drive belt 15 is driven by a drive motor (not shown) so that the print head 10 can be reciprocated along the main scanning direction.

  A paper holding table 16 is provided at a position facing the print head 10, and a suction surface 16 a for sucking the paper P by a negative pressure action by the suction fan 17 is provided. A large number of holes (not shown) are formed in the suction surface 16a. Print transport rollers 18 are respectively provided on the upstream side and the downstream side in the transport direction of the paper holder 16, and the paper P is transported in the sub-scanning direction by the transport rollers 18.

  The loop forming unit U3 includes a guide plate 19 disposed on the downstream print transport roller 18 and a pressure-bonding intermediate roller 20 for transporting the paper P guided by the guide plate 19. The guide plate 19 is configured to be switchable between a horizontal posture (broken line in FIG. 1) extending substantially in the horizontal direction and an open posture (solid line in FIG. 1) extending in the vertical direction.

  When forming an image on the long paper P, after the leading end of the paper P is transferred to the intermediate roller 20 through the horizontal guide plate 19, the conveyance of the paper P by the intermediate roller 20 is stopped, and then The guide plate 19 is switched from the horizontal posture to the open posture, and the paper P is suspended to form a loop.

  The cutter unit U4 includes a fixed blade 21, a movable blade 22, and a cut position sensor 23. A pressure-feeding type feeding roller 24 for feeding the cut paper P is provided.

  The reversing unit U5 includes a pressure-reversing reversing roller 25 that crimps the paper P, a driving mechanism (not shown) that rotates the reversing roller 25 forward and backward, and a reversing mechanism that rotates the reversing roller 25 by 90 ° around its axis. And. In the reversing unit U5, after the paper P fed from the front end side by the cutter unit U4 is conveyed by the reversing roller 25 so that the rear end portion reaches the position of the reversing roller 25, the reversing unit U5 as shown by the arrow in FIG. The paper P is sent from the rear end portion to the discharge unit U6 by rotating U5 about 90 ° around the axis and then reversely rotating the reverse roller 25.

  The discharge unit U6 switches a plurality of pressure-bonding type discharge rollers 26 for transporting the paper P, and a path switching for feeding the paper P transported by the discharge rollers 26 to one of the lateral feed belt 2 and the rack plate 3. A mechanism (not shown) is provided.

<Configuration of print head>
Next, the configuration of the print head 10 will be described with reference to an external perspective view of FIG. 2 and a front view of FIG. The print head 10 includes a main body 30 and a unit support 32 that is fastened to the main body 30 by four screws 31.

  Three head units 41, 42, and 43 are attached to the unit support 32 along the sub-scanning direction. That is, the downstream head unit 41, the intermediate head unit 42, and the upstream head unit 43. These head units all have the same configuration, and will be described by using the downstream head unit 41 as a representative.

  The head unit 41 includes nozzle rows 411, 412... 417 in which a large number of ink nozzles are formed along the sub-scanning direction. In order to form a color image, nozzle rows 411, 412... 417 for seven colors are provided, and yellow (Y), magenta (M), cyan (C), black (K), red (R), ... 417 for ejecting violet (V) and transparent (CL) inks are arranged along the main scanning direction. A cartridge (not shown) containing ink for these seven colors is detachably attached to the ink supply unit 33 (see FIG. 2).

  Each of the nozzle rows 411, 412,... 417 is formed with a large number of ink nozzles along the sub-scanning direction. For example, the nozzle row 411 includes ink nozzles 411a, 411b,. The same applies to the other nozzle rows. The head unit 41 is fastened to the unit support 32 by screws 41a. Further, the head unit 41 is formed with a long hole 41b, and a pin 321 implanted in the unit support 32 is fitted therein. By such a coupling mechanism, the head unit 41 is adjusted and assembled so that each nozzle row 411, 412... 417 is parallel to the reference line L. Adjustment is performed on the XY table, and the operator visually adjusts the reference line L and the nozzle rows 411, 412. When the adjustment position is determined, the screw 41a is used for fastening. Various modifications of the mechanical adjustment mechanism are possible.

  Although the configuration of the downstream head unit 41 has been described, the configuration of the other head units 42 and 43 is the same, and only the figure numbers are given and description thereof is omitted.

  In FIG. 3, the nozzle rows arranged in the sub-scanning direction are configured to eject the same ink. For example, the ink nozzles in the nozzle rows 411, 421, and 431 are configured to eject the same color ink. The same applies to the nozzle rows 412, 422, 432. When the adjustment and attachment of the three head units 41, 42, 43 to the unit support 32 are completed, the nozzle rows of all the head units 41, 42, 43 are in a state parallel to the reference line L and are mutually connected. These nozzle rows are also in a parallel state.

<Control block configuration>
Next, the control block configuration of the ink jet printer will be described with reference to FIG. FIG. 4 shows only main functions related to the present invention.

  The controller 50 has a function for controlling the operation of the entire printer. The conveyance control unit 51 controls conveyance of the paper P, and performs drive control on the print conveyance roller 18 and the suction fan 17. The head unit control unit 52 controls the head units 41, 42, and 43, and controls the discharge amount of each color ink based on the image data.

  The image data input unit 53 inputs image data to be formed. For example, image data stored in a storage medium of a digital camera can be captured. The image processing unit 54 performs image processing on input image data, and performs color / density correction, trimming, data enlargement processing, and the like. The image transfer unit 55 transfers the print image data subjected to the image processing to the head unit control unit 52. An image can be formed on the paper P using the print image data.

  The adjusting means 56 is provided to absorb assembly errors in the main scanning direction between the head units 41, 42, and 43, and adjusts according to the ink discharge timing between the head units 41, 42, and 43. . Adjustment data for this purpose is stored. In order to determine the adjustment amount, it is necessary to create a test print, and test print image data for that purpose is stored in the test print data storage unit 57. The test print reading unit 58 has a function of reading a test print, and is configured by, for example, a flat bed scanner. The adjustment amount determination unit 59 determines the adjustment amount based on the read image data of the test print. The determined adjustment amount is stored as adjustment data. The adjustment amount may be determined based on measurement by the operator.

<Adjustment method>
Next, an adjustment method will be described. When adjusting the discharge timings of the upstream and downstream head units as already described with reference to FIGS. 9 and 10, if the closest ink nozzles are used as a reference, the unit support 31 is formed as shown in FIG. When attached to the main body 30 in a state inclined by the angle θ, the amount of deviation in the main scanning direction between the farthest ink nozzles becomes larger than the adjustment amount, which causes a reduction in image quality. For example, when looking between the head units 41 and 42, the shift amount D1 in the main scanning direction between the furthest ink nozzles 411a and 421n and the shift amount E1 in the main scanning direction between the closest ink nozzles 411n and 421a are considerably open. Therefore, if the adjustment data is determined based on E1, the error becomes large. The same applies to the shift amounts D2 and E2 generated between the head units 42 and 43.

  In the present invention, when adjusting the ejection timing between the upstream and downstream head units, the ink nozzles corresponding in the sub-scanning direction are determined with reference to each other. Here, the corresponding ink nozzles, when considered between the head units 41 and 42, are ink nozzles 411a and 421a (tips), or ink nozzles 411b and 421b (seconds from the tip) ... Ink nozzles 411n and 421n (rear ends). Any of these combinations may be adopted as long as they are compatible. The same applies between the head units 42 and 43, and the ink nozzles 421a and 431a (front ends), or 421b and 431b (second positions from the front end),..., Or 421n and 431n (rear ends). In FIG. 6, the deviation amounts of the ink nozzles between the tips are displayed as F <b> 1 and F <b> 2. As can be seen from FIG. 6, by adjusting the discharge timing with reference to the corresponding ink nozzles, even if the unit support 32 is inclined, it is possible to suppress image quality deterioration as much as possible.

  An example of the test print will be described with reference to FIG. As shown in FIG. 7, the head units 41, 42, and 43 are driven to form images of straight lines L1, L2, and L3 along the sub-scanning direction. L1 is formed by the head unit 41, L2 is formed by the heel 42, and L3 is formed by the head unit 43. A plurality (four in the example) of straight lines L1, L2, and L3 are formed along the main scanning direction. This test print is read by the test print reading means 58, the shift amount in the main scanning direction of the straight lines L1, L2, and L3 (the shift amount between the corresponding nozzles) is obtained, and ink ejection is performed based on the number of dots corresponding to this shift amount. Adjust timing. The test print is not limited to that illustrated in FIG. 7, and various modifications are possible.

<Another embodiment>
In the present embodiment, a print head in which three head units are arranged in the sub-scanning direction has been described, but there may be two as shown in the figure. Further, four or more head units may be arranged in the sub-scanning direction. In this embodiment, only one head unit is arranged in the main scanning direction, but two or more head units may be arranged. The number of nozzle rows in this embodiment is seven for seven colors, but the number of rows can be changed as appropriate. The formed image may be a black and white image instead of a color image.

Cross-sectional schematic diagram showing the internal configuration of an inkjet printer External perspective view showing configuration of print head Front view showing the configuration of the print head The figure which shows the control block constitution of the ink jet printer The figure which shows the attachment error of the main scanning direction between each head unit Diagram showing the amount of deviation when the head unit is tilted Figure showing an example of creating a test print Front view showing the configuration of the print head The figure which shows the attachment error of the main scanning direction between two head units. Diagram showing the amount of deviation when the head unit is tilted

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Print head 41 1st head unit 42 2nd head unit 43 3rd head unit 50 Controller 52 Head unit control part 56 Adjustment means 411,412 ... 417 Nozzle row | line 421,422 ... 427 Nozzle row | line | column 431,432. .. 437 Nozzle rows 411a, 411b ... 411n Ink nozzles 421a, 421b ... 421n Ink nozzles 431a, 431b ... 431n Ink nozzle L Reference line

Claims (2)

A head unit provided with a plurality of ink nozzles along the sub-scanning direction;
A unit support for mounting and supporting a plurality of head units along the sub-scanning direction;
Adjusting means for adjusting the ink discharge timing in the main scanning direction between the plurality of head units,
The adjustment unit adjusts the ejection timing with reference to corresponding ink nozzles between head units located on the upstream side and the downstream side in the sub-scanning direction.   The corresponding ink nozzles are a front end nozzle of the upstream head unit and a front end nozzle of the downstream head unit, or a rear end nozzle of the upstream head unit and a rear end nozzle of the downstream head unit. The inkjet printer according to claim 1.

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