JP2019034545A - Liquid droplet discharge device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a droplet ejection device capable of accurately controlling a ejection position of a droplet ejected from a nozzle with respect to a medium. A droplet ejection device is predetermined as a first piezo element 13 for moving a head in a first direction and a second piezo element 14 for moving a head in a second direction opposite to the first direction. A moving unit that moves the medium 8 in the first direction according to the target moving amount, a transport amount detecting unit 9 as a moving amount detecting unit that detects the moving amount of the medium 8 in the first direction, and a first piezo. A drive control unit for controlling the drive of the element 13 and the second piezo element 14 is provided, and the drive control unit has a target transfer amount A as a target movement amount and a movement amount detected by the transfer amount detection unit 9. Either the first piezo element 13 or the second piezo element 14 is driven according to the difference BA from the transport amount B. [Selection diagram] Fig. 2

Description

  The present invention relates to a droplet discharge device.

  2. Description of the Related Art Conventionally, an ink jet printer (hereinafter also simply referred to as “printer”) that discharges ink from a head toward a medium such as printing paper is known as a droplet discharge device. The printer normally prints an image or text on the medium by conveying the medium in a predetermined conveyance direction and ejecting ink from the head toward the medium. In order to perform high-quality printing, it is necessary to accurately match the relative positions of the medium and the head. For example, in the ink jet recording apparatus disclosed in Patent Document 1, after the recording medium is transported, the recording head is moved in the transport direction of the recording medium in accordance with an error in the transport amount of the recording medium, and the recording head for the transported recording medium is recorded. The position of is adjusted. Further, in the ink jet apparatus of Patent Document 2, a voltage is applied to a piezo element provided in the ink jet head, whereby the line head is finely moved in the main scanning direction to perform alignment between the plurality of heads.

JP 2010-699 A JP-A-9-226131

  In the techniques of Patent Document 1 and Patent Document 2, the position of the recording head is adjusted by expanding and contracting a piezoelectric element (piezo element). However, the piezo element has hysteresis characteristics and creep characteristics, and the degree of expansion / contraction with respect to the same applied voltage, that is, the amount of displacement may change. Such a change in the displacement amount of the piezo element causes an error in the position control of the recording head, and there is a problem of causing a shift in the ejection position of the droplets ejected from the recording head onto the medium.

  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] A liquid droplet ejection apparatus according to this application example is a liquid droplet ejection apparatus that ejects liquid droplets from the plurality of nozzles to the medium while relatively moving a head including the plurality of nozzles and the medium. A first piezo element that moves the head in a first direction, a second piezo element that moves the head in a second direction opposite to the first direction, and a predetermined target movement amount A moving unit that moves the head or the medium in the first direction, a moving amount detection unit that detects a moving amount of the head or the medium in the first direction, the first piezo element, and the first A drive control unit that controls driving of the two piezo elements, wherein the first piezo element is disposed on the second direction side of the head, and the second piezo element is on the first direction side of the head. Placed in The drive control unit is configured to select one of the first piezo element and the second piezo element according to a difference B-A between the target movement amount A and the movement amount B detected by the movement amount detection unit. It is characterized by driving.

  According to this application example, by driving either the first piezo element or the second piezo element, only the expansion direction of the piezo element is used, and the difference B−A between the target movement amount A and the actual movement amount B is used. Accordingly, it is possible to correct the ejection positions of the liquid droplets ejected from the plurality of nozzles onto the medium. Therefore, compared to the case of using one piezo element, it is less affected by hysteresis characteristics and creep characteristics, and the relative position of the head with respect to the medium can be adjusted with high accuracy.

[Application Example] In the droplet discharge device according to the application example, the moving unit moves the medium in the first direction, and the drive control unit is configured to perform the first operation when the difference is a positive value. When one piezo element is driven and the difference is a negative value, the second piezo element is preferably driven.
According to this application example, the ejection position can be corrected only by adjusting the head position without switching the ejection nozzle by switching the piezo element to be used depending on whether the medium movement amount error is positive or negative. Accordingly, the ejection position can be corrected with higher accuracy.

[Application Example] In the liquid droplet ejection apparatus according to the application example, the moving unit moves the head in the first direction, and the drive control unit is configured to perform the first operation when the difference is a positive value. When the two piezo elements are driven and the difference is a negative value, the first piezo element is preferably driven.
According to this application example, the ejection position can be corrected only by adjusting the head position without switching the ejection nozzle by switching the piezo element to be used depending on whether the head movement amount error is positive or negative. Accordingly, the ejection position can be corrected with higher accuracy.

[Application Example] In the liquid droplet ejection apparatus according to the application example, the plurality of nozzles are arranged at a pitch P in the first direction, the moving unit moves the medium in the first direction, and The drive control unit drives the first piezo element when the difference is a positive value and less than or equal to P / 2, and drives the first piezo element when the difference is greater than the positive value and P / 2. And when the difference is a negative value and P / 2 or less, the second piezo element is driven, and when the difference is a negative value and greater than P / 2, the first piezo element is It is preferable to drive.
According to this application example, the first piezo element or the second piezo element is selected according to the magnitude of the difference B−A between the target movement amount A and the movement amount B of the medium and the half of the nozzle pitch P. Since the piezo element is selected and driven, the head position adjustment amount for adjusting the ejection position can be further reduced. The variation of the displacement amount of the piezo element due to the hysteresis characteristics and the creep characteristics increases as the drive potential increases, that is, the displacement amount increases. Therefore, by reducing the head position adjustment amount, the drive potential, that is, the displacement amount of the piezo element can be made smaller, fluctuations in the displacement amount can be further reduced, and the ejection position can be corrected with higher accuracy. It can be performed.

[Application Example] In the liquid droplet ejection apparatus according to the application example, when the difference is a negative value and larger than P / 2, the drive control unit moves the ejection end nozzle on the first direction side in the second direction. If the difference is a positive value and greater than P / 2, the discharge end nozzle on the first direction side is changed to the adjacent nozzle on the first direction side, and the difference is a positive value. When the difference is P / 2 or less, or when the difference is a negative value and P / 2 or less, it is preferable not to change the discharge end nozzle on the first direction side.
According to this application example, the discharge area before moving the medium overlaps with the discharge area after moving the medium, or the discharge area before moving the medium and the discharge area after moving the medium It is possible to reduce the occurrence of a region where no droplet is ejected between the two.

[Application Example] In the liquid droplet ejection apparatus according to the application example, the drive control unit includes the first piezo element and the second piezo element according to the number of times the first piezo element or the second piezo element is continuously driven. Of the two piezo elements, the piezo element to be driven is preferably switched.
According to this application example, it is possible to reduce the bias of the piezo element driven for head position adjustment to either the first piezo element or the second piezo element. When the head position is adjusted based on the head position adjusted in the previous ejection, when the piezoelectric element driven for head position adjustment is biased to either side, the biased piezoelectric element There is a risk that the amount of displacement of the piezo element increases. By switching the piezo elements according to the number of times of continuous driving, the bias of the driven piezo elements is reduced. Therefore, an increase in the displacement amount due to accumulation of expansion of the piezo elements is reduced, fluctuations in the displacement amount due to hysteresis characteristics and creep characteristics can be reduced, and the ejection position can be corrected with higher accuracy.

[Application Example] In the droplet discharge device according to the application example described above, it is preferable that the drive control unit drives the first piezo element and the second piezo element alternately.
According to this application example, either the first piezo element or the second piezo element is not continuously driven for head position adjustment. When the head position is adjusted based on the head position adjusted in the previous ejection, when either piezo element is driven continuously for head position adjustment, the head position is continuously driven. There is a possibility that the extension of the piezo element is accumulated and the displacement amount of the piezo element is increased. By alternately driving the two piezo elements, it is possible to further reduce an increase in the displacement amount due to the accumulation of expansion of the piezo elements. Therefore, variation in displacement due to hysteresis characteristics and creep characteristics can be reduced, and the ejection position can be corrected with higher accuracy.

FIG. 2 is a schematic plan view showing a configuration of a droplet discharge device. FIG. 2 is a schematic cross-sectional view showing the structure of a droplet discharge device. The enlarged view of the carriage part in a droplet discharge apparatus. The graph which shows the relationship between the drive voltage of a 1st piezoelectric element, and a head position. The graph which shows the relationship between the drive voltage of a 2nd piezoelectric element, and a head position. 6 is a flowchart of a head position adjustment method according to the first embodiment. Each process figure of the head position adjustment method in 1st Embodiment. Each process figure of the head position adjustment method in 1st Embodiment. Each process figure of the head position adjustment method in 1st Embodiment. Each process figure of the head position adjustment method in 1st Embodiment. Each process figure of the head position adjustment method in 1st Embodiment. Each process figure of the head position adjustment method in 1st Embodiment. 9 is a flowchart of a head position adjustment method according to the second embodiment. Each process figure of the head position adjustment method in 2nd Embodiment. Each process figure of the head position adjustment method in 2nd Embodiment. Each process figure of the head position adjustment method in 2nd Embodiment. Each process figure of the head position adjustment method in 2nd Embodiment. Each process figure of the head position adjustment method in 2nd Embodiment. Each process figure of the head position adjustment method in 2nd Embodiment. Each process figure of the head position adjustment method in 2nd Embodiment. Each process figure of the head position adjustment method in 2nd Embodiment.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of the invention will be described with reference to the drawings. Note that the drawings to be used are appropriately enlarged or reduced so that the part to be described can be recognized. However, the following embodiments do not limit the invention according to the claims. In addition, not all the combinations of features described in the embodiments are essential for the solving means of the invention.

(First embodiment)
<Droplet ejection device>
The droplet discharge device of this embodiment will be described with reference to FIGS. 1 and 2.
FIG. 1 is a schematic plan view showing the configuration of the droplet discharge device in the first embodiment. 2 is a schematic cross-sectional view showing the structure of the droplet discharge device along the line HH ′ of FIG.

  As shown in FIGS. 1 and 2, the droplet discharge device 100 </ b> A of the present embodiment is an inkjet printer that discharges ink from the nozzles of the head 1 as droplets toward the medium 8. The droplet discharge device 100A includes a head 1, a carriage 2, a control unit 3, a guide shaft 4, a guide rail 5, a scanning belt 11, a scanning driving shaft 6, a head scanning driving unit 7, and a carry amount. The detector 9, the transport roller driving unit 29, the transport roller 10, and the medium support unit 20 (see FIG. 2) are provided.

  FIG. 1 shows arrows X, Y, and Z that are orthogonal to each other. Each arrow X, Y, Z indicates a direction based on the arrangement posture of the droplet discharge device 100A when in a normal use state in which it is arranged on a horizontal plane and used. Hereinafter, directions indicated by arrows X, Y, and Z are referred to as “X direction”, “Y direction”, and “Z direction”, respectively. The X and Y directions are directions parallel to the horizontal plane. The X direction is parallel to the scanning direction of the droplet discharge device 100A, and the Y direction is parallel to the transport direction of the medium 8. The H-H ′ line is a line segment parallel to the Y direction. The Z direction is the direction opposite to the direction of gravity. In the following description, when referred to as “up” or “down”, it means the vertical direction based on the direction of gravity unless otherwise specified. The X, Y, and Z directions are appropriately illustrated so as to correspond to FIG.

  The head 1 ejects droplets onto the medium 8. A plurality of nozzles 19 (see FIG. 2) are provided in a row on the surface of the head 1 facing the medium 8, and by ejecting liquid droplets from the nozzles 19 based on the print data, the medium 8. By forming ink dots, the print image represented by the print data is recorded. Further, the head 1 is provided with a head drive circuit 28. The head drive circuit 28 generates an ejection pulse according to an electric signal sent from the control unit 3, and the generated ejection pulse is input to the head 1 so that the head 1 1 droplet discharge is performed.

  The carriage 2 mounts the head 1 and can move in the X direction along the guide shaft 4 and the guide rail 5. A scanning belt 11 (endless belt) that rotates in a direction parallel to the guide shaft 4 and the guide rail 5 is connected to the carriage 2, and power is supplied from the head scanning drive unit 7 to the scanning belt 11 via the scanning drive shaft 6. Is transmitted, the carriage 2 moves in the X direction, and scanning in the X direction (main scanning) is performed. The head scanning drive unit 7 includes, for example, a motor (not shown), and the motor is operated by a command from the control unit 3 based on print data input from the outside to scan the head 1.

  The medium 8 is held horizontally by the medium support unit 20 (platen) in the area scanned by the head 1. The medium 8 is, for example, paper, and is transported in the transport direction (first direction) when the transport roller driving unit 29 (moving unit) drives the transport roller 10.

  As shown in FIG. 2, the transport amount detection unit 9 is provided at the lower portion of the medium 8 on the upstream side of the head 1, and a light emitting unit that emits detection light toward the medium 8 and a light emitting unit reflected by the medium 8. A light receiving portion for receiving light from the light receiving portion. The light emitting unit is, for example, an LED, a semiconductor laser, a lamp, or the like. The light receiving unit is, for example, an imaging device such as a CCD or a CMOS image sensor, and can detect the transport amount of the medium 8 by imaging the medium 8. Further, the carry amount detection unit 9 may image the printing surface of the medium 8 or the reverse surface on the opposite side. The carry amount detection unit 9 may detect the carry amount of the medium 8 based on a change in the shade pattern or pattern on the surface of the imaged medium. The transport amount detection unit 9 of the present embodiment is an example of a movement amount detection unit in the present invention.

  Inside the head 1, ink chambers communicating with each of the nozzles 19 are provided (not shown). The head 1 ejects ink in the ink chamber from the nozzle 19 toward the medium 8 by a known method such as application of pressure to the ink by a piezo element. In the droplet discharge device 100 </ b> A, the head 1 discharges ink from each nozzle 19 toward the medium 8 while moving relative to the medium 8 in the scanning direction. Note that the method of discharging droplets from the head 1 is not limited to the method using the piezo element. The head 1 may be applied with a so-called thermal-type droplet discharge method in which an ink chamber is heated to generate bubbles and a droplet is discharged from a nozzle 19.

  Ink may be supplied to the ink chamber of the head 1 from a cartridge that is detachably attached to the carriage 2. Alternatively, the ink may be supplied from an ink tank provided at a location separated from the carriage 2 via a piping member such as a tube provided in the droplet discharge device 100A.

  The control unit 3 includes a memory 26 and a control circuit 27. The memory 26 is electrically connected to the control circuit 27, and the control circuit 27 is electrically connected to the head scanning drive unit 7, the head drive circuit 28, the conveyance roller drive unit 29, and the conveyance amount detection unit 9, and each of them. Electric signals can be input and output. The control circuit 27 reads the print data stored in the memory 26 and controls the operations of the head scanning drive unit 7, the head drive circuit 28, the transport roller drive unit, and the transport amount detection unit 9 based on the print data. The scanning amount of the head 1, the scanning timing, the ejection amount, the ejection timing, and the conveyance amount of the medium 8 are controlled.

  Droplet ejection is performed while scanning the head 1 in the scanning direction (X direction) or in the direction opposite to the scanning direction. For example, after performing a first drawing by discharging droplets while performing a first scan in the X direction, the transport roller 10 is driven to transport the medium 8 in the transport direction. Drawing is performed on the medium 8 by discharging droplets while performing the second scanning in the opposite direction.

  FIG. 3 is a plan view of the head 1 as viewed from the Z direction. The head 1 is detachably attached to the carriage 2 via a head holding member 12. That is, the worn head 1 can be replaced by removing the head 1 from the head holding member 12. The head holding member 12 has an opening 21 in which a region where the nozzle 19 is provided is opened in a plan view as viewed from the Z direction, so that the liquid droplets discharged from the nozzle 19 can land on the medium 8. It has become.

  The head holding member 12 can be moved in the first direction (conveyance direction) by two head guide rails 18 provided along the first direction. The head holding member 12 and the second head guide member 18 can be moved in the Y direction. It is clamped by the head moving unit 24.

  The first head moving unit 23 includes a first piezo element 13, a piezo element holding member 15, and a contact member 16 that connects the first piezo element 13 to the head holding member 12. One end of the first piezo element 13 is fixed to the carriage 2 by a piezo element holding member 15, and the other end is fixed to the head holding member 12 via a contact member 16. Therefore, the head 1 held by the head holding member 12 can be displaced along the head guide rail 18 in the first direction (conveying direction) by extending the first piezoelectric element 13.

  The second head moving unit 24 includes a second piezo element 14, a piezo element holding member 15, and a contact member 16 that connects the second piezo element 14 to the head holding member 12. One end of the second piezo element 14 is fixed to the carriage 2 by a piezo element holding member 15, and the other end is fixed to the head holding member 12 via a contact member 16. Accordingly, when the second piezo element 14 extends, the head 1 held by the head holding member 12 can be displaced in the second direction opposite to the first direction (conveyance direction).

  The first piezo element 13 and the second piezo element 14 are electrically connected to the control unit 3. By controlling the expansion / contraction of the first piezo element 13 or the second piezo element 14 by the control unit 3, the ejection position is adjusted according to the medium conveyance amount acquired by the conveyance amount detection unit 9. The control unit 3 of this embodiment is an example of a drive control unit of the present invention.

FIG. 4 is a graph showing the relationship between the driving voltage of the first piezo element and the head position, and FIG. 5 is a graph showing the relationship between the driving voltage of the second piezo element and the head position. 4 shows the relationship between the drive voltage applied to the first piezo element 13 and the position of the head 1 from the reference position in the transport direction. FIG. 5 shows the relationship applied to the second piezo element 14. The relationship between the drive voltage and the position of the head 1 from the reference position in the transport direction is shown. As shown in FIG. 3, the reference position is set, for example, by a position in the carriage 2 that contacts a stopper 30 provided on the upstream side in the transport direction of the head holding member 12. A stopper 30 may also be provided on the flow side of the head holding member 12.
As shown in FIG. 4, the expansion amount of the first piezo element 13 varies depending on the drive voltage applied. By changing the extension amount, the position of the head 1 in the transport direction can be adjusted in the + direction (forward direction) with respect to the reference position. As shown in FIG. 5, the expansion amount of the second piezo element 14 changes depending on the drive voltage applied. By changing the extension amount, it is possible to adjust the position of the head 1 in the negative direction (reverse direction) with respect to the reference position in the transport direction.

  If the transport amount of the medium 8 deviates from the target transport amount after performing the first drawing discharge, the droplet discharge position in the second drawing discharge is determined from the drawing pattern determined by the print data. It will shift. For example, when the actual transport amount is larger than the target transport amount, the discharge position is shifted in the direction opposite to the transport direction from the drawing pattern, that is, in the second direction. Further, when the actual transport amount is smaller than the target transport amount, the discharge position is shifted in the transport direction, that is, the first direction, from the drawing pattern. As described above, the landing position of the liquid droplet shifts due to the shift of the ejection position, so that an unintended streak-like print pattern is generated in the printed matter, which leads to a significant loss in print quality.

  In the liquid droplet ejection apparatus 100A in the present embodiment, after the head 1 ejects liquid droplets, the medium 8 is transported according to the target transport amount A stored in the memory 26 in advance. Next, the conveyance amount B is acquired by the conveyance amount detection unit 9, and the acquired conveyance amount B is transferred to the control unit 3. In the control unit 3, the control circuit 27 calculates a difference C (B−A) between the target carry amount A read from the memory 26 and the carry amount B transferred from the carry amount detection unit 9. Depending on the value, a drive signal is sent to the first piezo element 13 or the second piezo element 14 to adjust the position of the head 1. That is, the ejection position is corrected by adjusting the position of the head 1 using the first piezo element 13 and the second piezo element 14 according to the actual transport amount. Note that the target carry amount A in the present embodiment corresponds to the target movement amount A in the present invention, and the carry amount B corresponds to the movement amount B in the present invention.

<Head position adjustment method>
Next, a head position adjusting method using the first piezo element 13 or the second piezo element 14 will be described with reference to FIGS. FIG. 6 is a flowchart of the head position adjusting method in this embodiment. 7-12 is a figure which shows each process of the head position adjustment method in this embodiment. In this embodiment, the influence of hysteresis is reduced by selecting either the first piezo element 13 or the second piezo element 14 depending on whether the difference C is positive or negative (or 0). The head position is adjusted. Hereinafter, step S1 to step S10 in the flowchart of FIG. 6 will be described.

  In step S1, a first drawing discharge is performed, and droplets are discharged onto the medium 8 as shown in FIG. Hereinafter, a droplet 25 is attached to the droplet landed on the medium 8 to indicate a droplet discharge position. Then, the process proceeds to step S2.

  In step S2, the medium 8 is transported in the first direction according to the target transport amount A. The target carry amount A is stored in the memory 26, the control circuit 27 reads the target carry amount A from the memory 26, and a control signal is transmitted from the control unit 3 to the carry roller drive unit 29 in accordance with the target carry amount A. In response to the control signal, the medium 8 is transported. Then, the process proceeds to step S3.

  In step S3, the carry amount B is detected. The transport amount B is detected by photographing the front surface (or back surface) of the medium 8 by the transport amount detection unit 9 in accordance with a signal from the control unit 3. The detected carry amount B is transferred from the carry amount detection unit 9 to the control circuit 27 of the control unit 3. Then, the process proceeds to step S4.

  In step S4, the control circuit 27 calculates a difference C (B−A) between the carry amount B and the target carry amount A. Then, the process proceeds to step S5.

  In step S5, in the control circuit 27, the difference C between the carry amount B and the target carry amount A is C <0 (negative value), C> 0 (positive value), or C = 0. It is determined whether or not.

  When the difference C is C> 0 (positive value), the process proceeds to step S6, and the drive signal (drive voltage) of the first piezo element 13 is calculated. In this case, a displacement driving signal (driving voltage) corresponding to the absolute value | C | of the difference C from the relationship between the driving voltage of the first piezo element 13 and the head position shown in FIG. 4 is calculated. After calculating the drive signal (drive voltage), the process proceeds to step S8.

  When the difference C is C <0 (negative value), the process proceeds to step S7, and the drive signal (drive voltage) of the second piezo element 14 is calculated. In this case, a displacement driving signal (driving voltage) corresponding to the absolute value | C | of the difference C from the relationship between the driving voltage of the second piezo element 14 shown in FIG. 5 and the head position is calculated. After calculating the drive signal (drive voltage), the process proceeds to step S9.

  When the difference C is C = 0, the drive signal (drive voltage) is not calculated and the head position is not adjusted, and the process proceeds to step S10.

  In step S8, the drive signal (drive voltage) calculated in step S6 is applied to the first piezo element 13, and the head position is adjusted according to the difference C. As shown in FIG. 8, by applying the calculated drive signal (drive voltage) to the first piezo element 13 for driving, the head 1 is displaced by a displacement corresponding to the absolute value | C | of the difference C in the first direction. Can be moved. Before applying a driving voltage to the first piezo element 13, a driving signal (driving voltage) for reducing the expansion of the first piezo element 13 is applied to the second piezo element 14. As shown in FIG. 9, by moving the head 1, the nozzle position of the head 1 can be matched with the target discharge position 22 with higher accuracy. After the head 1 is moved, the process proceeds to step S10.

  In step S9, the drive signal (drive voltage) calculated in step S7 is applied to the second piezo element 14, and the head position is adjusted according to the difference C. As shown in FIG. 10, by applying the calculated drive signal (drive voltage) to the second piezo element 14 and driving it, the absolute value | C | of the difference C is changed in the second direction opposite to the first direction. The head 1 can be moved by a corresponding amount of displacement. Before applying a driving voltage to the second piezo element 14, a driving signal (driving voltage) for reducing the expansion of the second piezo element 14 is applied to the first piezo element 13. As shown in FIG. 11, by moving the head 1, the nozzle position of the head 1 can be matched with the target discharge position 22 with higher accuracy. After the head 1 is moved, the process proceeds to step S10.

  In step S10, the second drawing discharge is performed. As shown in FIG. 12, the discharge position accuracy can be improved by performing the second drawing discharge after the head position adjustment. After the second drawing discharge is performed, the process returns to step S2 again, transports the medium 8 according to the target transport amount A, and repeats steps S3 to S10 again. Thereafter, printing is performed by repeating step S2 to step S10 a plurality of times.

  In the present embodiment, either the first piezo element 13 or the second piezo element 14 is driven in accordance with the positive or negative of the difference C between the target carry amount A and the actual carry amount B, and the medium 8 is driven from the plurality of nozzles 19. The ejection position of the droplets ejected on the substrate is corrected. The hysteresis characteristic of the piezo element is generated by repeatedly expanding and contracting the piezo element. In this embodiment, since the head position is adjusted only by extending the first piezo element 13 or the second piezo element 14, the hysteresis of the piezo element is obtained. Characteristics can be reduced. The creep characteristic is generated when a voltage is concentrated and applied to one piezo element. In the present embodiment, the time during which a voltage is applied to the piezo element is distributed to the first piezo element 13 and the second piezo element 14 as compared to the case of using one piezo element. Thereby, creep characteristics can be reduced.

(Second Embodiment)
Next, a head position adjusting method according to the second embodiment using the droplet discharge device 100A according to the first embodiment will be described with reference to FIGS.
FIG. 13 is a flowchart of a head position adjusting method according to the second embodiment. 14 to 21 are schematic views showing each step of the head position adjusting method of the second embodiment. In the head position adjustment method using the droplet discharge device 100A of the second embodiment, in addition to the positive / negative (or 0) of the difference C between the transport amount B of the medium 8 and the target transport amount A, the nozzle pitch P of the nozzle 19 is set. The case (case) is divided according to the magnitude relationship with 1/2. Select which of the first piezo element 13 or the second piezo element 14 is driven according to each case (case), and further change the discharge end nozzle in each case (case) to reduce the influence of hysteresis. The head position is adjusted. Hereinafter, each of step S21 to step S38 in the flowchart of FIG. 13 will be described. In the present embodiment, the discharge end nozzle represents the outermost nozzle that performs discharge among the plurality of nozzles 19 constituting the nozzle row. Hereinafter, unless otherwise specified, the term “discharge end nozzle” refers to the discharge end nozzle on the first direction side.

  In step S21, the first drawing discharge is performed, and the droplets 25 are discharged onto the medium 8 as shown in FIG. 7 in the first embodiment. Then, the process proceeds to step S22.

  In step S22, according to the target transport amount A, the medium 8 is transported in the first direction as shown in FIG. The transport of the medium 8 is performed by the control circuit 27 reading the target transport amount A from the memory 26 and sending a control signal from the control unit 3 to the transport roller driving unit 29 according to the target transport amount A. The target transport amount A is stored in the memory 26, and is determined so that the first drawing discharge landing droplets and the second drawing discharge landing droplets performed after the transport are arranged at the same pitch. It is done. Further, the discharge end nozzle in the second drawing discharge is a nozzle in the second direction with respect to the end nozzle of the nozzle row, the nozzle in the first direction with respect to the discharge end nozzle is a non-discharge nozzle, and according to the discharge end nozzle It is desirable to set the target transport amount A. At this time, it is desirable to select the discharge end nozzle in consideration of a conveyance amount error estimated in advance. Thereby, when the difference C (that is, the conveyance amount error) exceeding the nozzle pitch P occurs, the adjustment amount of the head position can be reduced by changing the discharge end nozzle. In the present embodiment, the discharge end nozzle is set to a nozzle shifted by one in the second direction side from the end nozzle of the nozzle row. That is, one end nozzle becomes a non-ejection nozzle. Then, the process proceeds to step S23.

  In step S23, the carry amount B is detected. In accordance with a signal from the control circuit 27, the carry amount detection unit 9 captures the front surface (or back surface) of the medium to detect the carry amount B. The detected carry amount B is transferred from the carry amount detector 9 to the control circuit 27. Then, the process proceeds to step S24.

  In step S24, the control circuit 27 calculates a difference C (B−A) between the carry amount B and the target carry amount A. Then, the process proceeds to step S25.

  In step S25, in the control circuit 27, the difference C between the carry amount B and the target carry amount A is C> 0 (positive value), C <0 (negative value), or C = 0. It is determined whether or not.

  When the difference C is C = 0, the ejection position is not adjusted, and the process proceeds to step S38 to perform the second drawing ejection.

  If the difference C is C <0 (negative value), the process proceeds to step S26, and the control circuit 27 determines whether the absolute value | C | of the difference C is | C | ≦ P / 2 or | C |> It is determined whether it is P / 2.

[Case 1]
In step S26, if | C | ≦ P / 2, that is, as shown in FIG. 14, the position of the discharge end nozzle is positioned downstream of the target discharge position 22 in the transport direction (Y direction). If the deviation is less than half of the nozzle pitch P, the process proceeds to step S28, and the drive signal (drive voltage) of the second piezo element 14 is calculated. A displacement driving signal (driving voltage) corresponding to the absolute value | C | of the difference C is calculated from the relationship between the driving voltage of the second piezo element 14 and the head position shown in FIG. In this embodiment, Case 1 is a case where | C | <0 and | C | ≦ P / 2. After the calculation is completed, the process proceeds to step S32.

  In step S32, the drive signal (drive voltage) calculated in step S28 is applied to the second piezo element 14, and the head position is adjusted according to the absolute value | C | of the difference C. As shown in FIG. 14, the head 1 can be moved in the second direction by the difference C by driving the second piezo element 14. Before applying a driving voltage to the second piezo element 14, a driving signal (driving voltage) for reducing the expansion of the second piezo element 14 is applied to the first piezo element 13. Thereby, as shown in FIG. 15, the position of the discharge end nozzle can be brought close to the target discharge position 22. After the head 1 is moved, the process proceeds to step S38.

[Case 2]
When | C |> P / 2, that is, as shown in FIG. 16, when the nozzle adjacent to the discharge end nozzle is closer to the target discharge position 22, the process proceeds to step S29 to drive the first piezo element 13. A signal (drive voltage) is calculated. In this embodiment, this case is referred to as case 2. A displacement driving signal (driving voltage) corresponding to the absolute value | C | of the difference C is calculated from the relationship between the driving voltage of the first piezo element 13 and the head position shown in FIG. After the calculation is completed, the process proceeds to step S33.

  In step S33, the drive signal (drive voltage) calculated in step S29 is applied to the first piezo element 13, and the head position is adjusted according to the difference C. Before applying a driving voltage to the first piezo element 13, a driving signal (driving voltage) for reducing the expansion of the first piezo element 13 is applied to the second piezo element 14. As shown in FIG. 16, the head 1 can be moved in the first direction by driving the first piezo element 13. Thereby, as shown in FIG. 17, the position of the nozzle adjacent to the discharge end nozzle in the second direction can be brought close to the target discharge position 22. After the head 1 is moved, the process proceeds to step S36.

  In step S36, the discharge end nozzle is changed from the preset discharge end nozzle to the adjacent nozzle on the second direction side by one nozzle. That is, the discharge end nozzles are set as nozzles on the second direction side by two nozzles from the end nozzle. After the setting of the discharge end nozzle is completed, the process proceeds to step S38. In the second drawing discharge performed in step S38, the two nozzles at the end of the nozzle row on the first direction side are non-discharge nozzles.

  If the difference C is C> 0 (positive value), the process proceeds to step S27, and the control circuit 27 determines whether the absolute value | C | of the difference C is | C | ≦ P / 2 or | C |> It is determined whether it is P / 2.

[Case 3]
When | C | ≦ P / 2 in step S27, that is, as shown in FIG. 18, the position of the discharge end nozzle is located upstream of the target discharge position 22 in the transport direction (Y direction) If the amount of deviation is less than half of the nozzle pitch P, the process proceeds to step S30, and the drive signal (drive voltage) of the first piezo element 13 is calculated. A displacement driving signal (driving voltage) corresponding to the absolute value | C | of the difference C is calculated from the relationship between the driving voltage of the first piezo element 13 and the head position shown in FIG. In this embodiment, such a case where | C |> 0 and | C | ≦ P / 2 is referred to as Case 3. After the calculation is completed, the process proceeds to step S34.

  In step S34, the drive signal (drive voltage) calculated in step S30 is applied to the first piezo element 13, and the head position is adjusted according to the difference C. As shown in FIG. 18, by driving the first piezo element 13, the head 1 can be moved in the first direction by the absolute value | C | of the difference C. Before applying a driving voltage to the first piezo element 13, a driving signal (driving voltage) for reducing the expansion of the first piezo element 13 is applied to the second piezo element 14. Thereby, as shown in FIG. 19, the position of the discharge end nozzle can be brought close to the target discharge position 22. After the head 1 is moved, the process proceeds to step S38.

[Case 4]
When | C |> P / 2, that is, as shown in FIG. 20, when the end nozzle of the nozzle row is closer to the target discharge position 22 than the discharge end nozzle, the process proceeds to step S31, and the second piezo element 14 drive signals (drive voltages) are calculated. In the present embodiment, this case is referred to as case 4. A displacement driving signal (driving voltage) corresponding to the absolute value | C | of the difference C is calculated from the relationship between the driving voltage of the second piezo element 14 and the head position shown in FIG. After the calculation is completed, the process proceeds to step S35.

  In step S35, the drive signal (drive voltage) calculated in step S31 is applied to the second piezo element 14, and the head position is adjusted according to the absolute value | C | of the difference C. As shown in FIG. 20, the head 1 can be moved in the second direction by driving the second piezo element 14. Before applying a driving voltage to the second piezo element 14, a driving signal (driving voltage) for reducing the expansion of the second piezo element 14 is applied to the first piezo element 13. Thereby, as shown in FIG. 21, the position of the nozzle adjacent to the discharge end nozzle in the first direction can be brought close to the target discharge position 22. After the head 1 is moved, the process proceeds to step S37.

  In step S37, the discharge end nozzle is changed from the preset discharge end nozzle to the adjacent nozzle on the first direction side by one nozzle. That is, the end nozzle set as the non-discharge nozzle becomes the discharge nozzle and is set as the discharge end nozzle. After the setting of the discharge end nozzle is completed, the process proceeds to step S38.

  In step S38, the second drawing discharge is performed.

  According to the second embodiment, the head position adjustment amount for adjusting the ejection position can be reduced by aligning the nozzle 19 closer to the target ejection position 22. Therefore, by reducing the head position adjustment amount, the driving voltage of the piezo element, that is, the displacement amount of the piezo element can be further reduced. Therefore, since the fluctuation of the displacement amount can be further reduced, the discharge position can be corrected with higher accuracy.

(Third embodiment)
The head position adjustment method of the third embodiment uses the droplet discharge device 100A of the first embodiment, and in this embodiment, the difference C between the transport amount B and the target transport amount A is set. Regardless, in a plurality of drawing discharges, the number of times the first piezo element 13 or the second piezo element 14 is continuously driven is counted for each drawing discharge. When the number of times of continuous driving of one reaches a specified value, the piezo element to be used is switched to the other piezo element.

  According to the present embodiment, it is possible to reduce the bias of the piezo element to be used in one direction, and it is possible to reduce the variation of the displacement amount due to the extension amount of the first piezo element 13 and the second piezo element 14 reaching the limit.

(Fourth embodiment)
The head position adjustment method according to the fourth embodiment uses the droplet discharge device 100A according to the first embodiment, and draws and discharges regardless of the value of the difference C between the carry amount B and the target carry amount A. The piezo elements to be used every time are alternately switched between the first piezo element 13 and the second piezo element 14.

  According to the present embodiment, it is possible to reduce the continuous operation of the piezo elements to be used, and it is possible to reduce the variation in the displacement amount due to the extension amounts of the first piezo element 13 and the second piezo element 14 reaching the limit.

  Each configuration described in each of the above embodiments can be modified as follows, for example. Any of the modifications described below is positioned as an example of an embodiment for carrying out the invention.

  (Modification 1) In the droplet discharge device 100A of the above embodiment, the head 1 is mounted on the carriage 2 and configured to reciprocate in the scanning direction. The present invention is not limited to this, and the head 1 may not be mounted on the carriage 2 and may not move in the scanning direction. For example, in the droplet discharge device of the present invention, the head 1 may be a line printer configured by a line head in which a plurality of nozzles 19 are arranged in the X direction. In this case, drawing may be performed by ejecting liquid droplets from the line head while moving the medium 8 in the first direction by the transport roller driving unit 29 and the transport roller 10 as the moving unit, or as the moving unit. A moving mechanism that moves the line head in the Y direction may be provided, and drawing may be performed by performing ejection while moving the line head in the Y direction with respect to the medium 8. In the latter case, a movement amount detection unit that detects the movement amount of the line head in the Y direction with respect to the medium 8 is provided, and a difference B−A between the target movement amount A and the movement amount B detected by the movement amount detection unit. Accordingly, either the first piezo element 13 or the second piezo element 14 may be driven.

  (Modification 2) The droplet discharge device 100A of the above embodiment is configured to perform discharge while reciprocating the head 1 in the X direction. However, the present invention is not limited to this, and the medium 8 is not limited to this. The head scanning drive unit 7 may perform sub-scanning for performing drawing while moving and performing drawing to change the drawing position.

  (Modification 3) In the droplet discharge device 100A of the above embodiment, the first piezo element 13 and the second piezo element 14 are mounted on the carriage 2 and are configured to adjust the head position within the carriage 2. However, the present invention is not limited to this, and the first piezo element 13 and the second piezo element 14 are provided outside the carriage 2, and the head 1 is displaced together with the carriage 2 in the first direction or the second direction. You may let them.

  (Modification 4) Although the droplet discharge device 100A of the above embodiment is an ink jet printer, the present invention is not limited to this. For example, OLED (Organic Light Emitting) using an ink jet method used for industrial applications. Diode) manufacturing apparatus, wiring forming apparatus, and the like, and a droplet discharge apparatus used for manufacturing an electronic device may be used.

  The present invention is not limited to the above-described embodiments, examples, and modifications, and can be realized with various configurations without departing from the spirit thereof. For example, the technical features in the embodiments, examples, and modifications corresponding to the technical features in each embodiment described in the summary section of the invention are to solve some or all of the above-described problems, or In order to achieve part or all of the above effects, replacement or combination can be performed as appropriate. Further, if the technical feature is not described as essential in the present specification, it can be deleted as appropriate.

  DESCRIPTION OF SYMBOLS 100A ... Droplet discharge apparatus, 1 ... Head, 2 ... Carriage, 3 ... Control part as drive control part, 4 ... Guide shaft, 5 ... Guide rail, 6 ... Scanning drive axis, 7 ... Head scanning drive part, 8 ... Medium: 9... Transport amount detection unit as a movement amount detection unit, 10... Transport roller, 11... Scanning belt, 12 ... Head holding member, 13 ... 1st piezo element, 14 ... 2nd piezo element, 15. Members 16, contact members 18, head guide rails 19, nozzles 20, medium support portions (platens), 21 openings, 22 target discharge positions, 23 first head moving portions, 24 second Head moving unit, 25 ... droplet, 26 ... memory, 27 ... control circuit, 28 ... head driving circuit, 29 ... conveying roller driving unit, 30 ... stopper.

Claims (7)

A liquid droplet ejection apparatus that ejects liquid droplets from the plurality of nozzles to the medium while relatively moving a head including the plurality of nozzles and the medium,
A first piezo element that moves the head in a first direction;
A second piezo element that moves the head in a second direction opposite to the first direction;
A moving unit that moves the head or the medium in the first direction according to a predetermined target movement amount;
A movement amount detection unit for detecting a movement amount of the head or the medium in the first direction;
A drive control unit for controlling the driving of the first piezo element and the second piezo element;
With
The first piezo element is disposed on the second direction side of the head,
The second piezo element is disposed on the first direction side of the head;
The drive control unit is configured to select one of the first piezo element and the second piezo element according to a difference B-A between the target movement amount A and the movement amount B detected by the movement amount detection unit. A droplet discharge device for driving the above. The moving unit moves the medium in the first direction,
The drive control unit drives the first piezo element when the difference is a positive value, and drives the second piezo element when the difference is a negative value. 1
The droplet discharge device according to 1. The moving unit moves the head in the first direction,
The drive control unit drives the second piezo element when the difference is a positive value, and drives the first piezo element when the difference is a negative value. 2. The droplet discharge device according to 1. The plurality of nozzles are arranged at a pitch P in the first direction,
The moving unit moves the medium in the first direction,
The drive control unit
When the difference is a positive value and not more than P / 2, the first piezo element is driven,
If the difference is a positive value and greater than P / 2, drive the second piezo element;
When the difference is a negative value and not more than P / 2, the second piezo element is driven,
2. The droplet discharge device according to claim 1, wherein when the difference is a negative value and greater than P / 2, the first piezoelectric element is driven. If the difference is a negative value and greater than P / 2, the drive control unit changes the discharge end nozzle on the first direction side to an adjacent nozzle on the second direction side,
When the difference is a positive value and greater than P / 2, the discharge end nozzle on the first direction side is changed to an adjacent nozzle on the first direction side,
The discharge end nozzle on the first direction side is not changed when the difference is a positive value and P / 2 or less, or when the difference is a negative value and P / 2 or less. Item 5. The droplet discharge device according to Item 4.   The drive control unit switches a piezo element to be driven among the first piezo element and the second piezo element according to the number of times the first piezo element or the second piezo element is continuously driven. The droplet discharge device according to claim 1.   The liquid droplet ejection apparatus according to claim 1, wherein the drive control unit drives the first piezo element and the second piezo element alternately.

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