JP2010188596A - Method of cleaning liquid droplet delivery head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of cleaning a liquid droplet delivery head, capable of regulating finely a supply amount of a functional liquid such as ink supplied to a nozzle face. <P>SOLUTION: This method of cleaning the liquid droplet delivery head includes a functional liquid supply process for controlling a drive waveform applied to a driving element, to supply the functional liquid L from a nozzle 21b to the nozzle face 21a, and a wiping process for wiping the nozzle face 21a, after finishing the functional liquid supply process. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for cleaning a droplet discharge head.

  Conventionally, as a method for cleaning a droplet discharge head, a method is known in which a cap is pressed against the nozzle surface of the droplet discharge head to suck ink or the like and then the nozzle surface is rubbed with a wiper (for example, Patent Document 1). reference). In Patent Document 1, a step of pressing a cap against a nozzle surface, a step of supplying a negative pressure to the cap, a step of sucking ink with the cap, a step of removing the cap from the nozzle surface, and rubbing ink adhering to the nozzle surface with a wiper Steps such as taking are sequentially executed.

  In addition, a cleaning method including a step of forcibly discharging ink or the like from all nozzles of a droplet discharge head is known (see, for example, Patent Document 2). In Patent Document 2, the pressure in the sub-tank is controlled so that the pressure in the head flow path of the droplet discharge head becomes a forced discharge pressure for forcibly discharging ink or the like from all nozzles of the droplet discharge head. ing.

Japanese Patent No. 3978956 Japanese Patent No. 4007165

However, the cleaning method of Patent Document 1 has a problem that the number of processes in the process of sucking ink or the like by pressing a cap against the nozzle surface is large, and cleaning requires a long time.
On the other hand, according to the cleaning method of Patent Document 2, it is not necessary to provide a cleaning device such as a suction pump, and there is an advantage that the time required for cleaning can be shortened. However, when ink or the like is forcibly discharged from all nozzles, it is necessary to pressurize and control the pressure in the sub-tank, which makes it difficult to control the discharge amount of ink or the like.

  Therefore, the present invention provides a method of cleaning a droplet discharge head that can omit the suction step and can finely adjust the supply amount of functional liquid such as ink supplied to the nozzle surface.

  In order to solve the above problems, a droplet discharge head cleaning method of the present invention has a nozzle surface provided with a plurality of nozzles, and a drive element provided corresponding to each of the nozzles, A method of cleaning a droplet discharge head that discharges a droplet of a functional liquid from each of the nozzles, wherein the function liquid is supplied from the nozzle to the nozzle surface by controlling a drive waveform applied to the drive element. A liquid supply step; and a wiping step of wiping the nozzle surface after completion of the functional liquid supply step.

According to the present invention, the functional liquid can be supplied to the nozzle surface using the drive element used for normal droplet discharge. Therefore, it is not necessary to increase the pressure in the sub tank in order to supply the functional liquid to the nozzle surface.
Further, by controlling the drive waveform applied to the drive element, the functional liquid can be scattered by the nozzle and adhered to the nozzle surface. In addition, the functional liquid can be gradually oozed from the nozzle and spread on the nozzle surface. This makes it possible to finely adjust the supply amount of the functional liquid supplied to the nozzle surface as compared with the conventional method.
Accordingly, it is possible to reduce the cleaning time by omitting the suction by the conventional cap and improve the productivity. In addition, by finely adjusting the supply amount of the functional liquid supplied to the nozzle surface, it is possible to reduce the consumption amount of the functional liquid as compared with the conventional case and reduce the manufacturing cost.

  In the method for cleaning a droplet discharge head of the present invention, in the functional liquid supply step, a droplet scattering step in which the functional liquid is scattered and adhered to the nozzle surface, and in the droplet scattering step, the nozzle surface is applied to the nozzle surface. And a droplet growth step for growing the adhered functional liquid.

  According to the present invention, by controlling the drive waveform of the drive element, the droplets of the functional liquid are scattered on the nozzle surface, and more droplets are attached to the nozzle surface in a shorter time than during normal droplet discharge. be able to. Furthermore, in the droplet growth step, the functional liquid gradually oozed out from the nozzle can be supplied to the droplet adhered to the nozzle surface to grow it. That is, in the droplet growth process, the functional liquid can be spread over the nozzle surface in a shorter time by using the droplet attached to the nozzle surface. Therefore, the functional liquid can be supplied to the nozzle surface more efficiently in the functional liquid supply process, the processing time of the functional liquid supply process can be shortened, and the entire cleaning process can be shortened.

  In the method for cleaning a droplet discharge head according to the present invention, in the functional liquid supply step, the amplitude of the drive waveform is 40% or more and 70% or less of the amplitude of the discharge waveform applied when droplets of the functional liquid are discharged. It is characterized by doing.

  According to the present invention, the force for pushing out the functional liquid from the nozzle by the driving element is weaker than in the case of ejecting droplets in a normal droplet ejection process. For this reason, the liquid droplets are scattered in various directions different from the direction of the liquid droplets during normal ejection. Part of the scattered functional liquid adheres to the nozzle surface. By repeating this, the functional liquid can be rapidly supplied to the nozzle surface.

  Further, in the cleaning method for a droplet discharge head according to the present invention, the driving waveform is a trapezoidal wave including a voltage rising portion, a constant voltage portion, and a voltage falling portion, and the width of the voltage rising portion is 4.5 μsec, The constant voltage portion has a width of 3.0 μsec, and the voltage drop portion has a width of 3.2 μsec.

  According to the present invention, the functional liquid can be more efficiently pushed out from the nozzle by the drive element and scattered in the vicinity of the nozzle, and the functional liquid can be efficiently supplied to the nozzle surface.

  In the method for cleaning a droplet discharge head according to the present invention, in the functional liquid supply step, the amplitude of the drive waveform is set to 70% or more and 100% or less of the amplitude of the fine vibration waveform applied to the discharge head. Features.

  According to the present invention, the drive waveform of the drive element is controlled to have an amplitude equal to or smaller than a normal fine vibration waveform that prevents the functional liquid from solidifying. Accordingly, the functional liquid can ooze out from the nozzle onto the nozzle surface without discharging the functional liquid droplets from the nozzle, and the functional liquid can be wetted and spread on the nozzle surface.

  In the method for cleaning a droplet discharge head according to the present invention, the driving waveform is a trapezoidal wave including a voltage rising portion, a constant voltage portion, and a voltage falling portion, and the width of the voltage rising portion is 7.0 μsec. The width of the constant voltage part is 2.0 μs, and the width of the voltage drop part is 7.0 μs.

  According to the present invention, the functional liquid can be more efficiently oozed from the nozzle by the driving element and wetted and spread on the nozzle surface, so that the functional liquid can be efficiently supplied to the nozzle surface.

It is a perspective view of a droplet discharge device in an embodiment of the present invention. It is a top view of the droplet discharge head of the droplet discharge apparatus shown in FIG. It is a fragmentary sectional view of the droplet discharge head of the droplet discharge device shown in FIG. It is a side view of the stage of the droplet discharge apparatus shown in FIG. 4 is an example of a drive waveform of a drive element of the droplet discharge head shown in FIG. 3. It is process drawing of a functional liquid supply process (droplet scattering process). 4 is an example of a drive waveform of a drive element of the droplet discharge head shown in FIG. 3. It is process drawing of a functional liquid supply process (droplet growth process). 4 is another example of a drive waveform of a drive element of the droplet discharge head shown in FIG. 3.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the scale is appropriately changed for each member so that each member has a size that can be recognized on the drawing. The following description will be made using an orthogonal coordinate system in which the substrate transport direction is the X-axis direction, the direction perpendicular to the top surface of the substrate is the Z-axis direction, and the X-axis direction and the direction perpendicular to the Z-axis direction are the Y-axis directions.

FIG. 1 is a perspective view showing an example of a droplet discharge device 1 according to the present embodiment.
As shown in FIG. 1, a droplet discharge apparatus 1 includes a discharge head (droplet discharge head) 2 that discharges droplets of a functional liquid such as ink, a stage 3 on which a substrate P is placed, and a discharge head 2. A first drive unit 4 to be moved, a second drive unit 5 to move the stage 3, and a control device 7 that controls the operation of the entire droplet discharge device 1 are provided.

FIG. 2 is a plan view of the ejection head 2 as viewed from below.
As shown in FIG. 2, a substantially rectangular nozzle plate 21 is provided at the lower end of the discharge head 2. The nozzle surface 21 a of the nozzle plate 21 is provided with a plurality of nozzles 21 b that discharge droplets of ink or the like. The nozzle surface 21 a is substantially parallel to the upper surface (XY plane) of the substrate P placed on the stage 3. The nozzles 21b are arranged along the longitudinal direction of the nozzle surface 21a, and eject liquid droplets of functional liquid such as ink from each nozzle 21b.

FIG. 3 is a cross-sectional view of the ejection head 2.
As shown in FIG. 3, the ejection head 2 is mainly composed of a nozzle plate 21, a common ink chamber (reservoir) 23, a diaphragm 24, a head body 25, and a piezo element (drive element) 26. ing.

  The nozzle plate 21 is provided at the lower end of the ejection head 2 so as to close the lower portion of the common ink chamber 23. A plurality of nozzles 21b are provided in the nozzle plate 21 so as to penetrate the nozzle plate 21, and are opened in the nozzle surface 21a on the lower surface (see FIG. 2).

  The common ink chamber 23 is formed of silicon or the like, for example, and a plurality of cavities 23a are formed therein. The cavity 23a is provided corresponding to each of the nozzles 21b, and is partitioned for each nozzle 21b. The common ink chamber 23 is connected to a functional liquid supply unit (not shown) that supplies functional liquid such as ink. The functional liquid such as ink supplied from the functional liquid supply unit into the common ink chamber 23 is stored in each of the cavities 23 a in the common ink chamber 23.

  A vibration plate 24 is provided on the common ink chamber 23 using a flexible material, and the volume of the cavity 23a of the common ink chamber 23 changes as the vibration plate 24 vibrates up and down. On the vibration plate 24, a head body 25 having an accommodation chamber 25a therein is provided. The accommodation chamber 25a is provided at a position corresponding to the cavity 23a, and the piezo element 26 is accommodated therein. One end side of the piezoelectric element 26 is fixed to the inner wall of the storage chamber 25 a, and the other end side is disposed on the vibration plate 24. The piezo element 26 is provided so as to be able to expand and contract in the vertical direction (longitudinal direction) by a drive signal from the control device 7, and vibrates the vibration plate 24 in the vertical direction (the common ink chamber 23 side and the storage chamber 25 a side). .

  As shown in FIG. 1, the first drive unit 4 includes a support mechanism 4A that supports the discharge head 2, and an actuator 4B that rotates and moves the discharge head via the support mechanism 4A. The first drive unit 4 can move the ejection head 2 in the X-axis, Y-axis, and Z-axis directions. Further, the discharge head 2 can be rotated around the Z axis.

FIG. 4 is a side view of the stage 3.
The stage 3 includes a slide member 3A and a holder member 3B as shown in FIGS. The slide member 3A is provided so as to be slidable along a rail-shaped guide member 8 extending in the Y-axis direction on the base member 10. On the slide member 3A, a holder member 3B that holds the substrate P in a positioned state is provided. The holder member 3B holds the substrate P so that the surface thereof is substantially parallel to the XY plane.

The second drive unit 5 includes a first drive unit 5A that slides the slide member 3A along the guide member 8, and a second drive unit 5B that finely moves the holder member 3B on the slide member 3A. The first drive unit 5A is configured by, for example, a linear motor. The second drive unit 5B is configured by a plurality of actuators such as piezo elements, for example, and causes the holder member 3B to finely move in the X axis, Y axis, and Z axis directions and around each axis with respect to the slide member 3A. Can be done.
The control device 7 controls the first drive unit 4 and the second drive unit 5 to place the ejection head 2 at a desired position on the stage 3.

  In the droplet ejection process in which droplets are ejected by the droplet ejection device 1 and placed on the substrate P, the control device 7 first supplies a functional liquid such as ink from a functional liquid supply unit (not shown), and FIG. As shown, the cavity 23 a of the common ink chamber 23 of the ejection head 2 is filled with the functional liquid L. The ejection head 2 is moved to a predetermined position by the control device 7 in advance.

  Next, the control device 7 applies a predetermined voltage waveform to each piezo element 26 as a discharge waveform (drive waveform), and expands and contracts each piezo element 26 according to the discharge waveform. Thereby, the diaphragm 24 vibrates and the volume of the cavity 23a changes. A change in volume of the cavity 23a causes a pressure change in the cavity 23a. As the pressure of the functional liquid L in each cavity 23a increases due to this pressure change, the droplet D of the functional liquid L is discharged from each nozzle 21b.

  The droplets D of the functional liquid L discharged from each nozzle 21b land on a predetermined position on the substrate P, and the functional liquid L is disposed on the substrate P. The control device 7 further ejects the droplet D of the functional liquid L by the ejection head 2 while relatively moving the substrate P and the ejection head 2, and the droplet D of the functional liquid L at a predetermined position on the substrate P. Will continue to arrange. When the droplet D is discharged, mist of the functional liquid L is generated around the nozzle 21b as the droplet D is discharged. A part of the mist of the functional liquid L adheres to the nozzle surface 21a, and the viscosity increases due to evaporation of the solvent or the dispersion medium.

The control device 7 executes a cleaning process of the ejection head 2 after a predetermined time has elapsed. In the cleaning process, the functional liquid that has adhered to the nozzle surface 21a of the ejection head 2 and increased in viscosity in the ejection process of the droplet D is removed.
The cleaning process of the present embodiment includes a functional liquid supply process for supplying a new functional liquid L to the nozzle surface 21a, and a wiping process for wiping the functional liquid L on the nozzle surface 21a with a wiper after the functional liquid supply process is completed. ing. In addition, the functional liquid supply process includes a liquid droplet scattering process for spraying the liquid droplets of the functional liquid L and a liquid droplet growth process for growing the liquid droplets of the functional liquid L attached to the nozzle surface 21a.
Hereinafter, the cleaning process of the ejection head 2 of the present embodiment will be described in detail with reference to FIGS.

FIG. 5 shows voltage waveforms applied to the piezo element 26 in the droplet scattering process of the functional liquid supply process.
In the cleaning process, the control device 7 first executes a droplet scattering process included in the functional liquid supply process. As shown in FIG. 5, the control device 7 applies a trapezoidal wave similar to the ejection waveform W at the time of droplet ejection as a scattering waveform (driving waveform) W1 to each piezo element 26. The scattering waveform W1 is formed by a voltage rising portion W1a, a constant voltage portion W1b, and a voltage falling portion W1c.

  Here, the width T1a of the voltage rising portion W1a in the scattered waveform W1 is about 4.5 μsec, the width T1b of the constant voltage portion W1b is about 3.0 μsec, and the width T1c of the voltage falling portion W1c is about 3.2 μsec. is there. Therefore, the width T1 of the scattered waveform W1 is about 10.7 μsec. In the present embodiment, the width T1a to T1c of each part of the scattering waveform W1 is equal to the width of each part of the trapezoidal wave of the ejection waveform W.

  Further, when the voltage of the constant voltage portion Wb of the discharge waveform W is V, the control device 7 makes the voltage V1 of the constant voltage portion W1b of the scattered waveform W1 satisfy 0.4V ≦ V1 ≦ 0.7V. The voltage V1 of the constant voltage unit W1b is determined. In this embodiment, the voltage V of the constant voltage portion Wb of the ejection waveform W is about 27V, for example, and the voltage V1 of the constant voltage portion of the scattered waveform W1 is about 60 of the voltage V of the constant voltage portion Wb of the ejection waveform W. %. Note that the value of V differs for each ejection head, and is about 24V to about 34V.

In the droplet scattering step, the control device 7 applies the scattering waveform W1 shown in FIG. 5 to the piezo element 26 at a frequency of about 10 KHz for about 10 seconds. When such a scattered waveform W1 is applied to the piezo element 26 shown in FIG. 3, the diaphragm 24 vibrates and the volume of the cavity 23a changes, as in the discharge of the droplet D, and the inside of the cavity 23a changes. Pressure change occurs.
However, since the scattering waveform W1 is about 40% to about 70% of the amplitude of the ejection waveform W, the amplitude of the diaphragm 24 is smaller than that during ejection of the droplet D in the droplet ejection process. Therefore, the pressure change in the cavity 23a is also reduced, and the force for pushing out the functional liquid L from the nozzle 21b is also weakened.

6A and 6B are enlarged side views of the vicinity of the nozzle surface 21a.
When the force for pushing the functional liquid L from the nozzle 21b becomes weak, as shown in FIG. 6A, the ejection direction of the droplet d of the functional liquid L becomes unstable, and the droplet D (FIG. 3) in the droplet ejection process. The liquid droplets are scattered in an oblique direction or a lateral direction with respect to the discharge direction (see FIG. 4) (droplet scattering step). As shown in FIG. 6B, the functional liquid droplet d scattered in an oblique direction or a horizontal direction adheres to the nozzle surface 21a, and the functional liquid L is supplied to a part of the nozzle surface 21a.

  A part of the droplet d of the functional liquid L does not adhere to the nozzle surface 21a but scatters toward the substrate P side. Therefore, in the droplet scattering step, for example, a cap or the like (not shown) is disposed in the vicinity of the nozzle surface 21a so as to receive the droplet d scattered on the substrate P side.

FIG. 7 shows voltage waveforms applied to the piezo element 26 in the droplet growth process of the functional liquid supply process.
After completion of the droplet scattering process, the control device 7 supplies a supply waveform (driving waveform) that is a trapezoidal wave similar to the fine vibration waveform w for preventing the solidification of the functional liquid to each piezoelectric element 26, as shown in FIG. ) Apply W2. The supply waveform W2 is formed by a voltage increase portion W2a, a constant voltage portion W2b, and a voltage decrease portion W2c, similarly to the discharge waveform W and the scattering waveform W1.

  Here, the width T2a of the voltage rising portion W2a in the supply waveform W2 is about 7.0 μsec, the width T2b of the constant voltage portion W2b is about 2.0 μsec, and the width T2c of the voltage falling portion W2c is about 7.0 μsec. is there. Therefore, the width T2 of the supply waveform W2 is about 16 μsec. In the present embodiment, the widths T2a to T2c of the respective parts of the supply waveform W2 are equal to the widths of the respective parts of the trapezoidal wave of the fine vibration waveform w.

  Further, when the voltage of the constant voltage portion Wb of the discharge waveform W and the constant voltage portion wb of the fine vibration waveform w is V, the control device 7 sets the voltage V2 of the constant voltage portion W2b of the supply waveform W2 to 0.7V. The voltage V2 of the constant voltage unit W2b is determined so as to satisfy ≦ V2 ≦ V. In the present embodiment, the voltage V of the constant voltage portion Wb of the discharge waveform W and the constant voltage portion wb of the fine vibration waveform w is about 27 V, for example, and the voltage V2 of the constant voltage portion W2b of the supply waveform W2 is the discharge waveform W. It is about 85% of the voltage V of the constant voltage portion Wb of the current and the constant voltage portion wb of the fine vibration waveform w. Note that the value of the voltage V differs for each ejection head, and is, for example, about 24V to about 34V.

  In the droplet growth process, the control device 7 applies the two supply waveforms W2 and W2 shown in FIG. 7 to the piezo element 26 at a frequency of about 13.7 KHz for about 10 seconds. The interval Ts between the two supply waveforms W2, W2 is about 9 μsec. When such a supply waveform W2 is applied to the piezo element 26 shown in FIG. 3, the diaphragm 24 vibrates and the volume of the cavity 23a changes as in the discharge of the droplet D, and the inside of the cavity 23a changes. Changes in the pressure.

  Since the supply waveform W2 is about 70% to about 100% of the amplitude of the fine vibration waveform w that does not eject a droplet from the nozzle 21b, the amplitude of the diaphragm 24 by the supply waveform W2 is equal to the amplitude by the fine vibration waveform w. Or smaller. However, the pressure in the cavity 23a is continuously changed by the diaphragm 24 by applying the two supply waveforms W2, W2 to the piezo element 26 at a predetermined interval (width Ts). Thereby, the functional liquid L is discharged so as to ooze from the nozzle 21b to the nozzle surface 21a.

FIGS. 8A to 8C are enlarged plan views of the nozzle surface 21a for explaining the state of the functional liquid L in the droplet growth process.
After the liquid droplet scattering step, the functional liquid L is partially disposed on the nozzle surface 21a as shown in FIGS. 6B and 8A. In this state, by applying the supply waveform W2 to the piezo element 26 as described above, the functional liquid L is supplied so as to ooze out from the nozzle 21b. As a result, as shown in FIG. 8B, droplets of the functional liquid L adhering to the nozzle surface 21a grow and gradually expand. Then, at the end of the droplet growth step, as shown in FIG. 8C, the functional liquid L is disposed on the entire surface of the nozzle surface 21a.
Thus, the functional liquid supply process is completed.

The functional liquid L newly supplied to the nozzle surface 21a in the functional liquid supply process lowers the viscosity of the functional liquid that has adhered to the nozzle surface 21a and increased in viscosity in the normal droplet discharge process.
After the completion of the functional liquid supply process, the control device 7 wipes and removes the functional liquid L on the nozzle surface 21a having a reduced viscosity with a wiper or the like (wiping process).
Thus, the cleaning process of the present embodiment is completed.

According to the cleaning method of the discharge head 2 of the present embodiment, the functional liquid L can be supplied to the nozzle surface 21a using the piezo element 26 used for discharging the normal droplet D. Therefore, there is no need to increase the pressure in the sub tank in order to supply the functional liquid L to the nozzle surface 21a.
Further, by controlling the drive waveform applied to the piezo element 26, the functional liquid L can be scattered by the nozzle 21b and adhered to the nozzle surface 21a. Further, the functional liquid L can be gradually oozed out of the nozzle 21b, and can be spread on the nozzle surface 21a.

  Thereby, compared with the conventional method, the supply amount of the functional liquid L supplied to the nozzle surface 21a can be finely adjusted. Therefore, not only can the suction by the conventional cap be omitted to shorten the cleaning time and improve the productivity, but also by finely adjusting the supply amount of the functional liquid L supplied to the nozzle surface 21a, compared with the conventional case. In addition, the consumption of the functional liquid L can be reduced and the manufacturing cost can be reduced.

  Further, in the droplet scattering process, the drive waveform of the piezo element 26 is controlled so that the droplet d of the functional liquid L is scattered on the nozzle surface 21a, and more on the nozzle surface 21a than when the normal droplet D is discharged. The droplet d can be attached in a short time. Furthermore, in the droplet growth step, the functional liquid L gradually oozed from the nozzle 21b can be supplied to the droplets of the functional liquid L adhered to the nozzle surface 21a to be grown.

  That is, in the droplet growth process, the functional liquid L can be spread over the entire surface of the nozzle surface 21a in a shorter time by using the droplet of the functional liquid L attached to the nozzle surface 21a. Therefore, the functional liquid L can be supplied to the nozzle surface 21a more efficiently than when the functional liquid L is supplied only by the method of causing the functional liquid L to ooze from the nozzle 21b. Therefore, the processing time of the functional liquid supply process can be shortened, and the entire cleaning process can be shortened.

  Further, in the droplet scattering process, the force for pushing the functional liquid L from the nozzle 21b by the piezo element 26 is weaker than when the droplet D is discharged in the normal droplet discharging process. Therefore, the droplet d is scattered in various directions different from the scattering direction of the droplet D during normal ejection. A part of the scattered functional liquid L adheres to the nozzle surface 21a. By repeating this, the functional liquid L can be rapidly supplied to the nozzle surface 21a.

In the droplet scattering step, the functional liquid L can be pushed out from the nozzle 21b more efficiently by the piezo element 26 by setting the widths T1a to T1c of each part of the scattering waveform W1 as described above. Thereby, the functional liquid L can be scattered in the vicinity of the nozzle 21b, and the functional liquid L can be efficiently supplied from the nozzle surface 21a.
Further, by applying the scattering waveform W1 to the piezoelectric element 26 at a frequency of 10 KHz for about 10 seconds, the diaphragm 24 is vibrated about 100,000 times by the piezoelectric element 26 and sufficient functional liquid L is supplied to the nozzle surface 21a. be able to.

  Further, in the droplet growth process, the drive waveform of the piezo element 26 is controlled as an amplitude equal to or smaller than the amplitude of the normal fine vibration waveform w that prevents the functional liquid L from solidifying. Thereby, without discharging the droplet of the functional liquid L from the nozzle 21b, the functional L liquid can ooze out from the nozzle 21b to the nozzle surface 21a, and the functional liquid L can be wetted and spread on the nozzle surface 21a.

Further, in the droplet growth step, the functional liquid L can be oozed out of the nozzle 21b more efficiently by setting the widths T2a to T2c of each part of the supply waveform W2 as described above. Therefore, the functional liquid L can be efficiently wetted and spread by the nozzle surface 21a, and the functional liquid L can be efficiently supplied by the nozzle surface 21a.
Further, by applying two supply waveforms W2 and W2 to the piezo element 26 at a frequency of 13.7 KHz for about 10 seconds, the piezo element 26 causes the diaphragm 24 to vibrate approximately 100,000 times, and the nozzle surface 21a has sufficient function. Liquid L can be supplied.

  As described above, according to the cleaning method of the ejection head 2 of the present embodiment, the suction step by the cap can be omitted without providing a special mechanism, and the cleaning can be quickly performed with a small amount of the functional liquid L. . Therefore, improvement in productivity and reduction in manufacturing cost can be realized.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, in the functional liquid supply process, only the droplet scattering process in which the drive waveform of the piezoelectric element is 40% or more and 70% or less of the amplitude of the ejection waveform may be performed. Alternatively, only the droplet growth process in which the drive waveform of the piezo element is set to 70% to 100% of the amplitude of the fine vibration waveform may be performed.

Further, the amplitude of the drive waveform of the piezo element and the width of each part are not particularly limited. As the drive waveform, for example, a rectangular wave as shown in FIG. 9 can be used. In this case, the wavelength λ of the rectangular wave is set to 100 μsec, for example, and can be applied to the piezo element at a frequency of about 10 Hz. Further, the amplitude V3 can be set to about 70% to 100% of the amplitude of the fine vibration waveform.
Further, the amplitude of the drive waveform in the cleaning process can be appropriately adjusted according to the discharge waveform or the amplitude of the limit (discharge limit) at which droplets are discharged.

2 ejection head, 21a nozzle surface, 21b nozzle, 26 piezo element (drive element), D droplet, L functional liquid, W ejection waveform, w micro vibration waveform, W1 scattering waveform (drive waveform), W1a voltage riser, W1b Constant voltage part, W1c voltage drop part, W2 supply waveform (drive waveform), W2a voltage rise part, W2b constant voltage part, W2c voltage drop part, T1a, T1b, T1c, T2a, T2b, T2c width, V, v, V1 , V2 voltage (amplitude)

Claims (6)

A method for cleaning a droplet discharge head, comprising a nozzle surface provided with a plurality of nozzles, and a drive element provided corresponding to each of the nozzles, and discharging droplets of a functional liquid from each of the nozzles. There,
A functional liquid supply step of controlling the drive waveform applied to the drive element to supply the functional liquid from the nozzle to the nozzle surface;
A wiping step of wiping the nozzle surface after the functional liquid supply step;
A method for cleaning a droplet discharge head, comprising:   In the functional liquid supply step, a liquid droplet scattering step for scattering and adhering the functional liquid to the nozzle surface, and a liquid droplet growth step for growing the functional liquid attached to the nozzle surface in the liquid droplet scattering step The method for cleaning a droplet discharge head according to claim 1, comprising:   3. The function liquid supply step according to claim 1, wherein the amplitude of the drive waveform is 40% or more and 70% or less of the amplitude of the ejection waveform applied when ejecting the droplet of the functional liquid. A method for cleaning a liquid droplet ejection head as described. The driving waveform is a trapezoidal wave composed of a voltage rising part, a constant voltage part, and a voltage falling part,
4. The droplet according to claim 3, wherein the voltage rising part has a width of 4.5 μs, the constant voltage part has a width of 3.0 μs, and the voltage dropping part has a width of 3.2 μs. A method for cleaning the discharge head.   5. The liquid according to claim 1, wherein, in the functional liquid supply step, the amplitude of the drive waveform is set to 70% or more and 100% or less of the amplitude of the fine vibration waveform applied to the ejection head. A method for cleaning a droplet discharge head. The driving waveform is a trapezoidal wave composed of a voltage rising part, a constant voltage part, and a voltage falling part,
6. The liquid according to claim 5, wherein the time width of the voltage rising portion is 7.0 μsec, the width of the constant voltage portion is 2.0 μsec, and the width of the voltage falling portion is 7.0 μsec. A method for cleaning a droplet discharge head.

Images