JP5444838B2 - Recording position correction apparatus, recording apparatus, and recording position correction method - Google Patents

Description

  The present invention relates to a recording position correction apparatus, a control method for a recording position correction apparatus, and a recording apparatus.

  Conventionally, in a recording apparatus such as an ink jet printer, various techniques have been proposed for ejecting a liquid from a head unit to an accurate position with respect to a transported recording medium. For example, in the ink jet printer described in Patent Document 1 below, in order to land droplets at an accurate position even in a print medium region where the transport speed is not constant, the transport speed of the print medium is detected and the discharge timing is set. I am trying to correct it. In addition, in the inkjet printer described in Patent Document 2 below, the alignment adjustment of the line head is automatically performed with high accuracy in order to prevent printing defects such as oblique lines due to the alignment failure of the line head. Yes.

JP-A-8-230194 JP 2008-12712 A

  However, the ink jet printer described in Patent Document 1 cannot cope with a change in the behavior in the width direction of the print medium during printing. Further, it cannot cope with a case where the print medium is transported in an oblique transport direction, or when the print medium is transported out of the original transport position. As described above, when the relative position between the print medium and the head unit is not constant, an image cannot be formed on an intended portion of the print medium. In addition, in the case of the above-mentioned Patent Document 2, it is a proposal related to the alignment method of the line head of the ink jet printer, and as in the case of the above-described Patent Document 1, the relative position between the print medium and the head unit during printing is changed. I cannot respond to it.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

[Application Example 1]
The recording position correction apparatus according to this application example includes a plurality of ejection heads arranged in a direction crossing the conveyance direction of the recording medium, and the liquid from the ejection head to the recording medium conveyed on the conveyance surface. And a detection unit for detecting the position of the recording medium to be conveyed, and calculating conveyance information indicating the conveyance state of the recording medium based on the position of the recording medium detected by the detection unit And a control unit that controls movement of the head unit in a direction intersecting the transport direction and rotation about an axis in a direction perpendicular to the transport surface based on the transport information. It is characterized by having.

According to this recording position correction apparatus, the conveyance information calculation unit calculates conveyance information indicating the conveyance state of the recording medium based on the position of the recording medium detected by the detection unit. And based on this conveyance information, a control part controls the rotation to the periphery of the direction perpendicular | vertical to a conveyance surface and a direction perpendicular | vertical to a conveyance surface with respect to a head unit.
Since the movement and rotation of the head unit are controlled based on the conveyance information indicating the conveyance state of the recording medium, when the relative position between the recording medium being conveyed and the head unit is not constant, according to the conveyance information These relative positions can be made constant by moving and rotating the head unit. As a result, it is possible to form an image on the intended portion of the recording medium from the head unit.

[Application Example 2]
In the recording position correction apparatus according to the application example described above, the transport information includes a positional deviation amount from a predetermined reference position in the width direction of the recording medium, and the control unit is configured to control the head based on the positional deviation amount. It is desirable to control the movement of the unit in the direction intersecting the transport direction.

  According to this recording position correcting apparatus, the control unit can move the head unit based on the positional deviation amount in the width direction of the recording medium included in the conveyance information. Thus, when the recording medium is displaced from a predetermined reference position, the head unit can be moved to cope with the displacement.

[Application Example 3]
In the recording position correction apparatus according to the application example described above, the conveyance information includes a skew amount of the recording medium, and the control unit determines the conveyance surface and the head surface based on the skew amount. It is desirable to control rotation about the axis in the vertical direction.

  According to this recording position correction apparatus, the control unit can rotate the head unit based on the skew amount included in the conveyance information. Thus, when the skew occurs in the recording medium, the skew can be dealt with by rotating the head unit.

[Application Example 4]
In the recording position correction apparatus according to the application example described above, it is preferable that the control unit rotates the head unit based on the skew amount so that the head unit is orthogonal to a width direction end of the recording medium. .

  According to this recording position correction apparatus, the control unit can rotate the head unit so as to be orthogonal to the widthwise end of the recording medium. As a result, even when skew occurs in the recording medium, the head unit can eject the liquid while facing the recording medium correctly.

[Application Example 5]
In the recording position correction apparatus according to the application example, when the liquid is ejected from the ejection head onto the recording medium, the control unit moves in a direction intersecting the transport direction with respect to the head unit. It is desirable to control the rotation about the axis in the direction perpendicular to the transport surface.

  According to this recording position correction apparatus, the movement and rotation of the head unit can be controlled while ejecting liquid from the ejection head onto the recording medium. Thereby, even during printing on the recording medium, the relative position between the recording medium and the head unit can be made constant by moving and rotating the head unit. As a result, an image can be formed more accurately on the intended portion of the recording medium from the head unit.

[Application Example 6]
In the recording position correction apparatus according to the application example described above, it is preferable that the detection units are arranged on the upstream side and the downstream side of the head unit in the transport direction of the recording medium.

  According to this recording position correction apparatus, the recording medium is inclined on the transport surface even during printing on the leading edge or the trailing edge of the recording medium based on the positions of the recording medium detected by the upstream and downstream detection units. It is possible to determine whether the recording medium is transported in an inclined state, the recording medium is transported in an oblique transport direction, or the recording medium is transported out of the original transport position.

[Application Example 7]
In the recording position correction apparatus according to the application example, it is preferable that the control unit individually controls each of the plurality of ejection heads based on the conveyance information.

  According to this recording position correction apparatus, by individually controlling each of the plurality of ejection heads based on the conveyance information, each ejection head can be finely moved and rotated according to the conveyance information. As a result, an image can be formed on an intended portion of the recording medium in accordance with various conveyance states of the recording medium.

[Application Example 8]
The control method of the recording position correction apparatus according to this application example includes a detection step of detecting a position of a recording medium conveyed on a conveyance surface, and the recording medium based on the position of the recording medium detected in the detection step. A conveyance information calculation step for calculating conveyance information indicating a conveyance state of the recording medium, and a movement in a direction crossing the conveyance direction and the conveyance surface with respect to the head unit that ejects liquid onto the recording medium based on the conveyance information. And a control step for controlling rotation around an axis in a direction perpendicular to the axis.

According to the control method of the recording position correction apparatus, in the conveyance information calculation step, conveyance information indicating the conveyance state of the recording medium is calculated based on the position of the recording medium detected by the detection step. Based on this transport information, in the control step, the head unit is controlled to move in the direction intersecting the transport direction and to rotate about the axis in the direction perpendicular to the transport surface.
Since the movement and rotation of the head unit are controlled based on the conveyance information indicating the conveyance state of the recording medium, when the relative position between the recording medium being conveyed and the head unit is not constant, according to the conveyance information These relative positions can be made constant by moving and rotating the head unit. As a result, it is possible to form an image on the intended portion of the recording medium from the head unit.

[Application Example 9]
A recording apparatus according to this application example includes the recording position correction apparatus described above, and performs recording on a recording medium.

  According to this recording apparatus, when the relative position between the recording medium being conveyed and the head unit is not constant, the relative position between the recording medium and the head unit is made constant by the recording position correction apparatus, and the recording medium is intended. It becomes possible to form and record an image on the part.

1 is a side sectional view schematically showing an outline of an ink jet printer according to a first embodiment. FIG. 2 is a plan view schematically showing the outline of the ink jet printer according to the first embodiment. Explanatory drawing of the arrangement | sequence of each discharge head. Explanatory drawing of the mechanism and operation | movement which concern on the movement and rotation of a head unit. Explanatory drawing of the cam mechanism and operation | movement which concern on the movement and rotation of a head unit. 6 is a flowchart showing the operation of the recording position correction apparatus during printing. The figure which shows the example of the correction | amendment presence or absence with respect to a head unit. The top view which shows typically the outline of the inkjet printer which concerns on 2nd Embodiment. Explanatory drawing of the mechanism and operation | movement which concern on the movement and rotation of the head unit which concern on 2nd Embodiment. 1 is a side sectional view schematically showing an outline of a tandem type ink jet printer.

(First embodiment)
Hereinafter, as an example of a recording apparatus that includes a recording position correction apparatus and performs recording on a recording medium, an inkjet according to the first embodiment that prints an image or the like on a recording medium such as paper by ejecting (discharging) a liquid such as ink. The printer will be described. The ink jet printer here includes two head units in which a plurality of ink jet heads (ejection heads) are arranged in a direction intersecting the paper transport direction, and is a line head type ink jet printer capable of printing in a so-called one pass. It is.

  FIG. 1 is a side sectional view schematically showing an outline of the ink jet printer 100 according to the first embodiment. FIG. 2 is a plan view schematically showing the outline of the inkjet printer 100. Inside the inkjet printer 100 shown in FIG. 1 and FIG. 2, a transport unit 1 that holds and transports the paper P to be printed, and printing that performs printing on the paper P held and transported by the transport unit 1. Part 2 is provided. The operations of the transport unit 1 and the printing unit 2 are controlled by a control unit 90 shown in FIG. In the following description, the normal transport direction of the paper P in the ink jet printer 100 is referred to as a transport direction X, and the direction orthogonal to the transport direction X is referred to as a transport width direction Y.

  The conveyance unit 1 includes a gate roller 31 constituted by a pair of upper and lower nip rollers shown in FIG. 1, a driven roller 32 disposed on the upstream side in the conveyance direction X, and a drive roller disposed on the downstream side in the conveyance direction X. 34, a tension roller 33 disposed below the driven roller 32 and the drive roller 34, and an endless belt 35 that winds between the three rollers 32, 33, 34 in a loop.

  The drive roller 34 is a roller for applying a transport force in the transport direction X to the endless belt 35. As shown in FIG. 2, a conveyance drive motor 36 for transmitting power to the drive roller 34 is directly connected to one end in the conveyance width direction Y. On the other hand, the driven roller 32 is a roller having the same height as that of the driving roller 34 and arranged to face each other in parallel at a certain distance.

  The endless belt 35 is an endless belt-shaped member formed of a material having elasticity such as a synthetic rubber or a resin film. As shown in FIG. 2, the endless belt 35 has a large number of air holes 37 formed therein. The suction and holding action of the paper P by a suction device (not shown) is executed through the vent hole 37 so that the paper P is sucked and held on the transport surface 50 of the endless belt 35 that transports the paper P. Here, as a suction method of the suction device, for example, suction by negative pressure or electrostatic suction can be employed.

On the other hand, the printing unit 2 includes a head unit 10 disposed on the upstream side in the transport direction X, a head unit 20 disposed on the downstream side, and the like. Each head unit 10, 20 includes a plurality of ejection heads 11 that eject ink droplets, as shown in FIG. These ejection heads 11 are divided (separated) in the transport direction X by each of the head units 10 and 20, and four are arranged in the head unit 10 row and three in the head unit 20 row. The ejection heads 11 in each row are also divided (separated) in the transport width direction Y so that the entire ejection heads 11 are staggered in plan view, that is, transported along the transport width direction Y. They are alternately arranged upstream and downstream in the direction X.
The head units 10 and 20 can be reciprocated in the transport width direction Y and rotated around the θ rotation shaft 13 by the Y-axis motor 14 and the θ-axis motor 15 provided therein. Details of the movement and rotation of the head units 10 and 20 will be described later.

  FIG. 3 is an explanatory diagram of the arrangement of the ejection heads 11 and is a view of the head units 10 and 20 as viewed from below. As shown in the figure, on the surface (nozzle surface) of each ejection head 11 facing the transport surface 50, a number of nozzles that eject ink droplets are formed. Specifically, on each nozzle surface, four rows of nozzle rows composed of a plurality of nozzles arranged along the transport width direction Y are formed apart from each other in the transport direction X. These four nozzle arrays can eject inks of different colors. In this embodiment, black (K), cyan (C), magenta (M), yellow are sequentially arranged from the upstream side in the transport direction X. (Y) ink is ejected. In addition, each ejection head 11 is superposed in the transport direction X with the nozzle at the transport width direction Y end of the adjacent ejection head 11 that is separated in the transport direction X or the opposite direction. It is arranged. Then, for each color, that is, for each nozzle row, a necessary amount of ink droplets are simultaneously ejected from the nozzles at the necessary locations, thereby forming minute ink dots on the paper P. The ink jet printer 100 repeats this operation while transporting the paper P in the transport direction X. Then, only by sending the paper P in the transport direction X in one pass, an image having a width corresponding to the distance between the nozzles at both ends in the transport width direction Y of the head units 10 and 20 can be printed.

  The method for ejecting ink from the nozzles is not limited to a specific method, and various methods such as an electrostatic method, a piezo method, and a film boiling ink jet method can be employed. The electrostatic method is a method in which a drive pulse is applied to the electrostatic gap to displace the diaphragm in the cavity, and ink droplets are ejected by a pressure change in the cavity caused by the displacement. The piezo method is a method in which a drive pulse is applied to a piezo element to displace a diaphragm in a cavity, and ink droplets are ejected by a pressure change in the cavity caused by the displacement. The film boiling ink jet method is a method in which ink is heated by a micro heater provided in a cavity, and ink droplets are ejected by a pressure change accompanying generation of bubbles.

  The head units 10 and 20 can be reciprocated in the transport width direction Y that is parallel to the transport surface 50. Further, each of the head units 10 and 20 can be rotated clockwise and counterclockwise around an axis in a direction perpendicular to the conveying surface 50 around the θ rotation shaft 13 shown in FIG. That is, the head units 10 and 20 can be rotated in a direction parallel to the transport surface 50.

  FIG. 4 is an explanatory diagram of a mechanism and an operation related to the movement and rotation of the head unit 10. The head unit 10 shown in the figure includes a Y-axis motor 14 for transmitting power for reciprocating the head panel 12 in the transport width direction Y, a slide rail (not shown) extending along the transport width direction Y, a head A θ-axis motor 15 that transmits power for rotating the panel 12 around the θ-rotating shaft 13 is attached. As with the head unit 10, the head unit 20 is also provided with a Y-axis motor 14, a slide rail, and a θ-axis motor 15. Then, the head unit 20 can be reciprocated in the transport width direction Y and rotated clockwise and counterclockwise about the θ rotation shaft 13. In this embodiment, as the Y-axis motor 14 and the θ-axis motor 15 attached to the head units 10 and 20, for example, a linear ultrasonic motor capable of controlling a minute displacement is used.

  FIG. 4A shows an example in which the head unit 10 has moved by Ya in the transport width direction Y from the reference position. This is a result of driving the Y-axis motor 14 based on the control of the control unit 90 and moving the head panel 12 by Ya in the transport width direction Y according to the slide rail.

  FIG. 4B shows an example in which the head unit 10 is rotated clockwise from the reference position by the angle θa around the θ rotation shaft 13. This is a result of driving the θ-axis motor 15 and rotating the head panel 12 about the θ rotation shaft 13 clockwise by an angle θa based on the control of the control unit 90.

  Here, as a combination of FIGS. 4A and 4B, the Y-axis motor 14 is driven to move the head panel 12 in the transport width direction Y, and then the θ-axis motor 15 is driven to The panel 12 can be rotated about the θ rotation axis 13. Conversely, the θ-axis motor 15 is driven to rotate the head panel 12 around the θ-rotation shaft 13, and then the Y-axis motor 14 is driven to move the head panel 12 in the transport width direction Y. You may make it let it. Of course, the movement and rotation of the head panel 12 may be performed simultaneously.

On the other hand, as shown in FIG. 5, by attaching a Y-axis cam 16 and a θ-axis cam 17 to the head unit 10, the head unit 10 is reciprocated in the transport width direction Y, and at the same time, the θ rotation shaft 13 is moved. You may make it rotate clockwise and counterclockwise around a center.
FIG. 5A shows an example in which the head unit 10 has moved by Ya in the transport width direction Y from the reference position in accordance with the rotation of the Y-axis cam 16. FIG. 5B shows an example in which the head unit 10 is rotated clockwise from the reference position by the angle θa around the θ rotation shaft 13 in accordance with the rotation of the θ axis cam 17.
The positions of the θ rotation shaft 13, the Y axis motor 14, the θ axis motor 15, the Y axis cam 16, and the θ axis cam 17 are not limited to the positions shown in FIGS.

Referring back to FIGS. 1 and 2, two edge sensors S1 and S2 are disposed on the upstream side in the transport direction X across the head unit 10, and two edge sensors S3 and S4 are disposed on the downstream side. In addition, two edge sensors S5 and S6 are disposed on the upstream side in the transport direction X with the head unit 20 interposed therebetween, and two edge sensors S7 and S8 are disposed on the downstream side. These edge sensors S1 to S8 are sensors as detection units for detecting the position of the end portion in the width direction of the paper P. For example, a reflection type having a structure in which a light emitting element and a light receiving element face the direction of the conveyance surface 50. It is an image sensor. Each edge sensor S1-S8 detects the position of the width direction edge part of the paper P on the conveyance surface 50 by irradiating the light from a light emitting element to the conveyance surface 50 direction, and receiving reflected light with several light receiving elements. can do. In the present embodiment, for example, a CCD image sensor or a CMOS image sensor is used as the edge sensors S1 to S8.
Note that these edge sensors S1 to S8 may be automatically moved to a position where the position of the edge in the width direction can be detected according to the size of the paper P in the width direction.

A control unit 90 shown in FIG. 2 includes a CPU, a ROM, a RAM, and the like (not shown), and controls each unit and each mechanism in the inkjet printer 100. The control unit 90 includes a conveyance information calculation unit 91 that calculates conveyance information indicating the conveyance state of the paper P on the conveyance surface 50. This conveyance information includes the positional deviation amount and skew amount of the paper P.
The conveyance information calculation unit 91 detects the positional deviation amount and skew of the sheet P based on the position of the end in the width direction detected when the sheet P conveyed on the conveyance surface 50 passes through each of the edge sensors S1 to S8. Calculate the amount. The misregistration amount here is a misregistration amount from a predetermined reference position in the transport width direction Y of the paper P, and represents an interval from the reference position to the position of the end portion in the width direction of the paper P. Further, the skew amount represents the amount of inclination of the end portion in the width direction of the paper P with respect to the transport direction X.

Further, the control unit 90 includes the amount of movement in the transport width direction Y of each head unit 10 and 20 and the θ rotation shaft 13 based on the positional deviation amount and skew amount calculated by the transport information calculation unit 91. A movement amount calculation unit 92 for calculating the rotation amount at the center is included.
For example, when a displacement occurs when the transported paper P passes under the head units 10 and 20, the movement amount calculated by the movement amount calculation unit 92 causes the head units 10 and 20 to be displaced. By moving in the direction, the amount of movement corresponds to the positional deviation. Further, when the paper P is skewed when the paper P passes under the head units 10 and 20, the rotation amount calculated by the movement amount calculation unit 92 causes the head units 10 and 20 to skew. The amount of rotation corresponding to the skew is obtained by rotating to match the inclination of. That is, when the paper P passes under the head units 10 and 20, the rotation amount for making the head units 10 and 20 orthogonal to the width direction ends of the paper P is calculated.

The control unit 90 including the head units 10 and 20, the edge sensors S1 to S8, the conveyance information calculation unit 91, and the movement amount calculation unit 92 constitutes a recording position correction device, and the sheet P depends on the conveyance state of the sheet P. It has a function of correcting printing on P.
Note that the number and arrangement positions of the edge sensors to be arranged are not limited to the above. For example, the position of the paper P is detected by arranging only one edge sensor or three or more edge sensors on the upstream and downstream sides of each head unit 10 and 20. You may make it do. Alternatively, the edge sensor may be disposed only on either the upstream side or the downstream side of the head units 10 and 20.

Next, the operation of the recording position correction apparatus during printing will be described.
FIG. 6 is a flowchart showing the operation of the recording position correction apparatus during printing. The operation shown in the figure is started when the paper P to be printed is transported onto the transport surface 50. Although the operation in the head unit 10 will be described here, the same applies to the head unit 20.

  First, in step S05, the control unit 90 controls the edge sensors S1 to S4 disposed on the upstream side and the downstream side of the head unit 10, and starts detection operations in the edge sensors S1 to S4.

In step S <b> 10, the control unit 90 determines whether or not the edge direction of the paper P is detected by the edge sensors S <b> 1 and S <b> 2 disposed on the upstream side of the head unit 10.
If both the edge sensors S1, S2 detect the width direction edge of the paper P, the process proceeds to the next step S20.

  On the other hand, if none of the edge sensors S1, S2 detects the width direction end of the paper P, the process proceeds to step S11, and the control unit 90 performs a specified time after the paper P is transported onto the transport surface 50. It is determined whether or not elapses. The specified time here is a time exceeding the allowable time until the paper P conveyed on the conveyance surface 50 passes through both the edge sensors S1 and S2. Therefore, when the specified time has elapsed, the control unit 90 determines that the paper P is in a jammed state or is transported with a large deviation that cannot be detected by the edge sensors S1 and S2.

Here, if the specified time has elapsed, the process proceeds to step S12, and the control unit 90 takes measures such as paper jam. When the handling of the paper jam or the like in step S12 is completed, the process returns to step S10, and the determination of the detection of the edge in the width direction of the paper P is repeated. For example, the control unit 90 displays a message indicating that a jam or the like has occurred on the paper P on an operation screen (not shown) and accepts a user operation.
On the other hand, if the specified time has not elapsed, the process returns to step S10, and the determination of detection of the edge in the width direction of the paper P is repeated.

  In step S20, the control unit 90 causes the conveyance information calculation unit 91 to calculate the positional deviation amount and the skew amount of the paper P based on the detection results of the upstream edge sensors S1 and S2 in step S10. Specifically, the positional deviation amount and the skew amount of the paper P are calculated based on the positions of the end portions in the width direction of the paper P detected by the edge sensors S1 and S2.

  In step S30, the control unit 90 causes the movement amount calculation unit 92 to move the head unit 10 in the transport width direction Y based on the positional deviation amount and the skew amount calculated in step S20, and the θ rotation axis. The amount of rotation around 13 is calculated.

  In step S40, the control unit 90 performs movement correction and rotation correction on the head unit 10 based on the movement amount and rotation amount of the head unit 10 calculated in step S30.

Here, when the calculated movement amount is 0 and the rotation amount is 0, that is, when neither the positional deviation nor the skew is generated for the paper P, the movement correction and the head unit 10 are corrected. None of the rotation correction is performed and the state is left as it is.
On the other hand, when the movement amount is other than 0 and the rotation amount is 0, that is, when only the positional deviation occurs and the skew does not occur with respect to the paper P, for example, as shown in FIG. 10, only movement correction in the conveyance width direction Y is performed.
On the other hand, when the amount of movement is 0 and the amount of rotation is other than 0, that is, when only the skew is generated with no positional deviation for the paper P, for example, as shown in FIG. 10, only rotation correction is performed around the θ rotation axis 13.
On the other hand, when the movement amount is other than 0 and the rotation amount is other than 0, that is, when both the positional deviation and the skew are generated with respect to the paper P, for example, as shown in FIGS. Like the combination, the head unit 10 is subjected to rotation correction about the θ rotation axis 13 together with movement correction in the transport width direction Y.

  In step S50, the control unit 90 starts ejecting ink droplets onto the paper P from the head unit 10 that has been subjected to movement correction and rotation correction in step S40. As a result, printing on the paper P is started.

  In step S <b> 60, the control unit 90 calculates the positional deviation amount and the skew amount of the paper P based on the detection results of the edge sensors S <b> 3 and S <b> 4 arranged on the downstream side of the head unit 10 by the conveyance information calculation unit 91. calculate. Specifically, the positional deviation amount and the skew amount of the paper P are calculated based on the positions of the end portions in the width direction of the paper P detected by the edge sensors S3 and S4. Note that the detection results of the edge sensors S1 and S2 may be used in addition to the detection results of the edge sensors S3 and S4 when calculating the positional deviation amount and the skew amount.

  In step S70, the control unit 90 uses the movement amount calculation unit 92 to move the head unit 10 in the transport width direction Y based on the positional deviation amount and the skew amount calculated in step S60, and the θ rotation axis. The amount of rotation around 13 is calculated.

  In step S80, the control unit 90 performs movement correction and rotation correction on the head unit 10 based on the movement amount and rotation amount of the head unit 10 calculated in step S70.

In step S90, the control unit 90 determines whether or not the ejection time for one sheet of paper P has elapsed.
When the ejection time has elapsed, the process proceeds to the next step S100, and the control unit 90 determines whether or not printing of all sheets P to be printed has been completed. When the printing of all the sheets P is finished, the printing process is finished. If the sheet P to be printed remains, the process returns to step S10 to determine whether to detect the end of the next sheet P in the width direction.
In step S90, instead of determining whether or not the ejection time has elapsed, a sensor for detecting the end of the sheet P1 is provided to determine whether or not printing for the sheet P1 has been completed. You may do it.

On the other hand, if it is determined in step S90 that the ejection time has not elapsed, printing for one sheet P1 is continuing and the sheet P is being conveyed, so the process returns to step S60, and detection of the edge sensors S3 and S4 is performed. Based on the result, the amount of misalignment and the amount of skew of the edge in the width direction of the paper P are calculated.
That is, the position of the edge in the width direction of the paper P conveyed along with printing is detected in real time, and movement correction and rotation correction are performed on the head unit 10 in real time according to the detected position. As a result, the positional relationship between the paper P and the head unit 10 can always be kept correctly during printing.

  Next, specific examples of movement correction and rotation correction for the head units 10 and 20 will be described. FIG. 7 is a diagram illustrating an example of whether or not the head unit 10 is corrected. FIGS. 7A1, B1, C1, D1, and E1 show printing examples when no correction is performed, and A2, B2, C2, and D2. , (E2) shows a printing example when correction is performed. In each figure, the paper P before printing is shown on the upstream side in the transport direction X across the head unit 10, and the paper P after printing is shown on the downstream side. A white arrow indicates a direction in which the paper P is conveyed. Although an example of correction by the head unit 10 is described here, the same applies to the head unit 20.

  In FIG. 7A1, the paper P is transported in the transport direction X while maintaining the correct posture, but the entire paper P is displaced in the transport width direction Y. For this reason, in the case where no correction is performed (a1), the entire rectangular print image G is printed biased toward the edge of the paper P. On the other hand, in (a2), printing is performed with the head unit 10 moved and corrected in the transport width direction Y. As a result of this correction printing, in (a2), a rectangular print image G is printed at the correct position in the central portion of the paper P.

  In FIG. 7B1, the paper P is transported in the transport direction X in a skewed posture. For this reason, when correction is not performed (b1), the entire rectangular print image G is printed on the paper P with an inclination. On the other hand, in (b2), printing is performed while moving the head unit 10 in the direction opposite to the conveyance width direction Y in a state where the head unit 10 is rotationally corrected and placed at a position orthogonal to the widthwise end of the paper P. ing. As a result of this correction printing, in (b2), the rectangular print image G is printed in the correct posture on the central portion of the paper P.

  In FIG. 7C1, the sheet P is maintained in the correct posture, but is conveyed in an oblique direction with respect to the conveyance direction X. For this reason, when correction is not performed (c1), the print image G that should be a rectangular shape is printed on the paper P in a parallelogram shape and an inclined shape on the paper P due to the deviation of the image G at the time of printing. Yes. On the other hand, in (c2), printing is performed while moving the head unit 10 in the transport width direction Y. As a result of this correction printing, in (c2), the correct rectangular print image G is printed in the correct posture on the central portion of the paper P.

  In FIG. 7D 1, the paper P is transported in an oblique direction with respect to the transport direction X in a skewed posture. For this reason, when correction is not performed (d1), the print image G that should be a rectangular shape is printed in a parallelogram shape on the paper P instead of a rectangular shape due to the deviation of the image G at the time of printing. On the other hand, in (d2), printing is performed in a state where the head unit 10 is rotationally corrected and placed at a position orthogonal to the width direction end of the paper P. As a result of this correction printing, a correct rectangular print image G is printed on the central portion of the paper P in (d2).

  In FIG. 7 (e1), the paper P is meandering in the transport direction X and being transported. For this reason, when correction is not performed (e1), the print image G that should be a rectangular shape is printed in a distorted shape including a curve instead of a rectangular shape on the paper P due to the deviation of the image G at the time of printing. Yes. On the other hand, in (e2), printing is performed in a state where the head unit 10 is placed at a position orthogonal to the width direction end portion of the paper P while being rotationally corrected. As a result of this correction printing, a correct rectangular print image G is printed on the central portion of the paper P in (e2).

  As described above, according to the ink jet printer 100 of the present embodiment, the following effects can be obtained.

  In the ink jet printer 100 of the present embodiment, movement correction and rotation correction are performed on the head units 10 and 20 according to the positional deviation amount and skew amount of the paper P calculated based on the detection results of the edge sensors S1 to S8. I do. For this reason, for example, when the paper P is displaced in the transport width direction Y, in a skewed posture, transported in an oblique direction, or transported in a meandering state, etc. Even in this case, the movement correction, the rotation correction, and the combination of the movement correction and the rotation correction are performed according to the conveyance state, and the relative position between the paper P and the head units 10 and 20 can be made constant during printing. it can. As a result, an image can be formed on an intended portion of the paper P, and an image with high resist accuracy and less visible unevenness can be formed.

  Further, since printing is performed in a state where the head unit 10 is rotationally corrected and placed at a position orthogonal to the widthwise end of the paper P, ink droplets are always ejected from the head units 10 and 20 onto the paper P. It is possible to maintain the ideal positional relationship orthogonal. As a result, for example, when image data matched with ejection characteristics generated in advance by image processing or image data in which unevenness is difficult to see due to error dispersion or the like is printed, the effect of these images is not impaired.

  Further, by performing the above-described movement correction and rotation correction on each head unit 10 and 20 at high speed and with high accuracy, the eccentricity and vibration of each roller of the transport unit 1 that changes every time during transport of the paper P. It is possible to cope with a minute (several tens of μm) posture change of the paper P caused by the above.

  Further, since it is not necessary to correct the position, posture, etc. of the paper P in front of the head units 10 and 20, no skew correction or leading edge alignment mechanism for the paper P is required. Thereby, the effect of the cost reduction of the inkjet printer 100 can be acquired.

(Second Embodiment)
Next, an inkjet printer 200 according to the second embodiment will be described. Here, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. The ink jet printer 100 according to the first embodiment and the ink jet printer 200 according to the second embodiment include a mechanism and an operation related to the movement and rotation of the head units 10 and 20, and an arrangement of sensors for detecting the position of the paper P. Is different. FIG. 8 is a plan view schematically showing the outline of the ink jet printer 200 according to the second embodiment. FIG. 9 is an explanatory diagram of a mechanism and an operation related to movement and rotation of the head unit 10 according to the second embodiment. Here, the head unit 10 will be described, but the same applies to the head unit 20.

  In the head unit 10 according to the first embodiment, the entire head unit 10 can be moved and rotated. However, in the head unit 10 according to the second embodiment shown in FIG. 9, each ejection head 11 provided in the head unit 10. Movement and rotation can be performed every time. Therefore, for each ejection head 11, a Y-axis motor 14 that transmits power for reciprocating movement in the transport width direction Y, a slide rail (not shown) that extends along the transport width direction Y, and each ejection head 11 is θ A θ-axis motor (not shown) that transmits power for rotating around the rotation shaft 13 is attached.

  FIG. 9A shows an example in which each ejection head 11 has moved by Ya in the transport width direction Y from the reference position. This is because the Y-axis motor 14 for the discharge head 11 to be moved is driven based on the control of the control unit 90 and the corresponding discharge head 11 is moved by Ya in the transport width direction Y according to the slide rail. Become. In the figure, all the ejection heads 11 are the movement targets, but the ejection heads 11 that are the movement targets can be appropriately selected.

  FIG. 9B shows an example in which each ejection head 11 is rotated clockwise from the reference position by an angle θa around the θ rotation axis 13 of each ejection head 11. This is based on the control of the control unit 90 to drive the θ-axis motor for the discharge head 11 to be rotated and rotate the corresponding discharge head 11 clockwise around the θ rotation axis 13 by the angle θa. Result. In the figure, all the ejection heads 11 are the rotation targets, but the ejection heads 11 that are the rotation targets can be appropriately selected.

  Here, as a combination of FIGS. 9A and 9B, after the Y-axis motor 14 for the ejection head 11 to be moved is driven and the corresponding ejection head 11 is moved in the transport width direction Y, By driving a θ-axis motor for the discharge head 11 to be rotated, the corresponding discharge head 11 can be rotated about the θ rotation shaft 13. Conversely, after driving the θ-axis motor for the ejection head 11 to be rotated and rotating the corresponding ejection head 11 around the θ rotation axis 13, the Y-axis for the ejection head 11 to be moved is used. By driving the motor 14, the corresponding ejection head 11 can be moved in the transport width direction Y. Here, the ejection head 11 that performs only movement, the ejection head 11 that performs only rotation, and the ejection head 11 that performs both movement and rotation can coexist in the head unit 10.

  8, the inkjet printer 200 according to the second embodiment differs from the inkjet printer 100 according to the first embodiment in the edge sensors S1 to S8 that detect the position of the end in the width direction of the paper P. Instead, identification sensors S <b> 11 to S <b> 18 are provided as detection units that detect identification of marks or the like on the paper P. These identification sensors S11 to S18 are arranged for each ejection head 11 provided in each head unit 10 and 20. Two identification sensors S11 and S12 are disposed for each ejection head 11 on the upstream side in the transport direction X with the head unit 10 interposed therebetween, and two identification sensors S13 and S14 are disposed on the downstream side. Further, two identification sensors S15 and S16 are disposed for each ejection head 11 on the upstream side in the transport direction X with the head unit 20 interposed therebetween, and two identification sensors S17 and S18 are disposed on the downstream side.

The conveyance information calculation unit 91 is a sheet at the lower position of each ejection head 11 based on the identification position of the mark or the like detected when the sheet P conveyed on the conveyance surface 50 passes through each identification sensor S11 to S18. The position shift amount and skew amount of P are calculated.
Further, the movement amount calculation unit 92 is based on the positional deviation amount and the skew amount calculated by the conveyance information calculation unit 91, and the movement amount in the conveyance width direction Y for each ejection head 11 and each ejection head 11. The amount of rotation about the θ rotation axis 13 is calculated.
The control unit 90 performs movement correction and rotation correction for each of the ejection heads 11 based on the movement amount and the rotation amount of each ejection head 11 calculated by the movement amount calculation unit 92.

  In the ink jet printer 200 of the present embodiment, the positional deviation amount and the skew amount of the paper P at the lower position of each ejection head 11 based on the detection results of the identification sensors S11 to S18 provided for each ejection head 11. And movement correction and rotation correction are performed for each ejection head 11. Thereby, for example, it is possible to finely cope with local expansion and contraction of the paper P due to heat or ink droplet ejection.

  Further, when each of the identification sensors S11 to S18 detects a test pattern printed on the paper P, each of the ejection heads 11 can be automatically aligned, and a load related to the assembly of the ink jet printer 200 can be reduced. It becomes possible.

(Modification)
In the above-described embodiment, as shown in FIG. 1 and the like, one common transport unit 1 is provided for the two head units of the head units 10 and 20. However, the present invention is not limited to this. For example, as shown in a side sectional view schematically showing the outline of the ink jet printer 300 in FIG. 10, a tandem type in which a transport unit 1 is provided as an independent mechanism for each head unit 10, 20. It may be configured as follows.

  In addition, the plurality of ejection heads 11 are divided and arranged by the two head units 10 and 20, but the invention is not limited to this. The inkjet printer includes only one head unit, and all the ejection units are disposed in the head unit. A configuration in which the heads are arranged may be employed.

  DESCRIPTION OF SYMBOLS 1 ... Conveyance part, 2 ... Printing part, 10, 20 ... Head unit, 11 ... Discharge head, 12 ... Head panel, 13 ... θ rotation axis, 14 ... Y axis motor, 15 ... θ axis motor, 16 ... Y axis cam , 17 ... θ-axis cam, 31 ... gate roller, 32 ... driven roller, 33 ... tension roller, 34 ... drive roller, 35 ... endless belt, 36 ... transport drive motor, 37 ... vent hole, 50 ... transport surface, 90 ... Control unit 91 ... Conveyance information calculation unit 92 ... Movement amount calculation unit 100 ... Inkjet printer according to the first embodiment 200 ... Inkjet printer according to the second embodiment, 300 ... Inkjet printer according to the modification, S1 to S1 S8: Edge sensor, S11-S18: Identification sensor.

Claims (8)

A head unit in which a plurality of ejection heads that eject liquid onto a recording medium to be conveyed are arranged in a width direction that is a direction that intersects the conveyance direction of the recording medium;
A detection unit disposed for each of the ejection heads to detect a pattern on the recording medium;
Based on the pattern detected by the detection unit, a conveyance information calculation unit that calculates conveyance information indicating a conveyance state of the recording medium at a detection location for each corresponding ejection head;
A controller that individually controls movement of the ejection head in the width direction and rotation about an axis in a direction perpendicular to the conveyance surface of the recording medium, based on the conveyance information. Recording position correction device. The transport information includes a skew amount of the recording medium and a positional deviation amount from a predetermined reference position in the width direction,
The control unit controls the movement of the ejection head in the width direction based on the displacement amount, and rotates around an axis in a direction perpendicular to the transport surface of the ejection head based on the skew amount. The recording position correction apparatus according to claim 1, wherein the rotation is controlled.   The recording position correction apparatus according to claim 1, wherein the detection unit is disposed on an upstream side of the ejection head in the transport direction and on a downstream side of the ejection head in the transport direction. . The head unit includes a first head unit and a second head unit disposed downstream of the first head unit in the transport direction,
The said detection part in the said width direction differs between the said detection part arrange | positioned in the said 1st head unit, and the said detection part arrange | positioned in the said 2nd head unit, The Claim 1 to 3 characterized by the above-mentioned. The recording position correction apparatus according to any one of the above. Claim 4 in which the first head unit and the detecting unit disposed in the second head unit and disposed to said detection unit, characterized in that it is arranged in different positions in the width direction The recording position correction apparatus described in 1.   The recording position correction apparatus according to claim 1, wherein the pattern is a mark.   A recording apparatus comprising the recording position correction apparatus according to claim 1 and performing recording on a recording medium. A recording position correction method using a recording apparatus comprising: a plurality of head units in which a plurality of ejection heads that eject liquid to a recording medium to be conveyed are arranged in a width direction that is a direction intersecting the conveying direction of the recording medium. Detecting a pattern on the recording medium;
Based on the detected pattern, calculating conveyance information indicating a conveyance state of the recording medium at a detection location for each of the ejection heads corresponding to the detection location;
Recording based on the transport information, and controlling individually the movement in the width direction and the rotation about the axis in the direction perpendicular to the transport surface of the recording medium based on the ejection head. Position correction method.

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