WO2007145112A1

WO2007145112A1 - Liquid ejecting apparatus and liquid ejecting method

Info

Publication number: WO2007145112A1
Application number: PCT/JP2007/061441
Authority: WO
Inventors: Takehiro Murakami
Original assignee: Konica Minolta Holdings, Inc.
Priority date: 2006-06-14
Filing date: 2007-06-06
Publication date: 2007-12-21

Abstract

Provided is an electrostatically attracting type liquid ejecting apparatus which keeps a head gap constant. The liquid ejecting apparatus is provided with a liquid ejecting head (10) for ejecting a liquid toward a base material (K); an ejection driving power supply (30) for applying a driving voltage and forming a meniscus; a counter electrode (5) for supporting the base material (K); an electrostatic voltage power supply (8) which applies an electrostatic voltage between the liquid ejecting head (10) and the counter electrode (5) and generates an electrostatically attracting force; a plurality of sensors (15) for measuring a gap between the ejecting surface (23) and the base material (K); a piezoelectric element (13) for adjusting the gap between the ejecting surface (23) and the base material (K); and a control means (14) for controlling the piezoelectric element (13), corresponding to the measurement results obtained from the sensors (15).

Description

Specification

Liquid ejection apparatus and liquid ejection method

Technical field

The present invention relates to a liquid ejection apparatus and a liquid ejection method, and more particularly to an electrostatic suction type liquid ejection apparatus and a liquid ejection method.

Background art

Conventionally, as a technology for ejecting not only a low-viscosity liquid but also a high-viscosity liquid, the liquid in the nozzle is charged and the nozzle and the liquid droplets are landed. There is known an electrostatic suction type liquid discharge technique in which discharge is performed by an electrostatic suction force received from an electric field formed between various base materials that are objects to be received.

[0003] In addition, there has been a development of a liquid discharge apparatus using an electric field assist method that combines this liquid discharge technique and a technique for discharging liquid using pressure due to deformation of a piezoelectric element or generation of bubbles inside the liquid. Progressing. This electric field assist method uses the meniscus forming means and electrostatic attraction force to raise the liquid meniscus in the nozzle discharge hole, thereby increasing the electrostatic attraction force against the meniscus and overcoming the surface tension of the meniscus. It is a method of dropletizing and discharging.

In such a liquid ejecting apparatus, a technique for miniaturizing droplets in order to eject liquid stably and accurately is known. By setting the diameter of the fluid discharge hole at the tip of the nozzle to be equal to or less than the droplet diameter of the fluid immediately after discharge, the charge concentration region and the meniscus region can be matched to improve discharge accuracy. In addition, by setting the internal flow path length of the nozzle to at least 10 times the internal diameter, it is possible to increase the electric field strength and improve the stability of liquid discharge.

[0005] On the other hand, in a liquid ejection device that ejects liquid using only pressure due to deformation of a piezoelectric element or generation of bubbles inside the liquid, a gap between the liquid ejection head and the surface of an object ( Hereinafter, the “head gap”) is kept constant (for example, see Patent Document 1).

Patent Document 1: JP 2004-122112 A Disclosure of the invention

Problems to be solved by the invention

[0006] In contrast to the conventional liquid ejecting apparatus disclosed in Patent Document 1, the gap between the liquid ejecting head and the surface of the object (hereinafter referred to as “head gap”) is kept constant. There was a problem that it was difficult to keep. As a head gap correction method, a pre-discharge is performed in advance and correction is performed based on the result of landing on the surface of the object and the object, or based on the result of observing the flying droplet with a camera or the like. Is. In this case, when the head gap is corrected, there is a problem that even the posture of the liquid discharge head cannot be corrected. When the head gap becomes unstable during droplet discharge, the landing position and the like are different, and there is a problem that accurate liquid discharge cannot be performed. In particular, the electrostatic attraction method has a problem that the influence of the change in the head gap is large because the electric field strength at the nozzle tip varies depending on the head gap. In addition, when using a liquid discharge head having a plurality of nozzles, the distance between the open end of each nozzle and the surface of the object differs depending on the inclination angle of the liquid discharge head with respect to the object surface. There was also a problem.

[0007] Furthermore, due to the property of flying in a direction perpendicular to the surface of the head or the substrate that is electrostatically attracted by the inclination of the head and the substrate, the landing position is equal to the inclination of the head and the substrate than the expected landing position. Cause the problem of misalignment. When a liquid discharge head having a plurality of nozzles is used, the expected landing position of each nozzle varies depending on the inclination angle of the liquid discharge head with respect to the surface of the object.

The present invention has been made in view of these points, and an object of the present invention is to provide an electrostatic suction-type liquid ejection device that keeps the head gap constant.

Means for solving the problem

[0009] In order to solve the above-mentioned problem, the invention according to claim 1 provides a liquid ejecting apparatus comprising:

A liquid ejection head having a nozzle plate on which nozzles for ejecting liquid toward the substrate are formed, and a cavity for storing liquid ejected from the nozzles;

Pressure generating means for applying a driving voltage to generate pressure in the liquid stored in the cavity to form a meniscus in the nozzle; A counter electrode that supports the substrate while facing the discharge surface of the liquid discharge head, and an electrostatic voltage that generates an electrostatic attraction force by applying an electrostatic voltage between the liquid discharge head and the counter electrode. Generating means;

A plurality of measuring means for measuring gaps at a plurality of different positions between the discharge surface and the substrate;

A gap adjusting means for adjusting a gap between the liquid discharge head and the substrate;

Control means for controlling the gap adjusting means in accordance with the measurement result of the measuring means.

[0010] According to the invention described in claim 1, the plurality of measuring means measure the gaps at a plurality of different positions between the liquid discharge head and the substrate, and the control means determines the gap according to the measurement result. Adjust the head gap by adjusting means. After adjusting the head gap, the control means applies an electrostatic voltage and a driving voltage, and discharges a droplet.

[0011] The invention according to claim 2 is the liquid ejection device according to claim 1,

The gap adjusting means adjusts the distance and inclination between the substrate and the discharge surface of the liquid discharge head.

[0012] According to the invention of claim 2, the gap adjusting means adjusts the distance and inclination between the base material and the discharge surface of the liquid discharge head, and the discharge surface of the liquid discharge head and the base Adjust the head gap so that the surface of the material is parallel and constant.

[0013] The invention described in claim 3 is the liquid discharge device according to claim 1 or 2,

The gap adjusting means is a piezoelectric element.

According to the invention described in claim 3, the gap can be adjusted accurately by using a piezoelectric element having good linearity of output with respect to the input as the gap adjusting means.

[0015] The invention described in claim 4 is directed to the liquid ejection device according to any one of claims 1 to 3.

The measuring means measures the gap without contacting the substrate.

[0016] According to the invention described in claim 4 of the invention, the measurement means that is not in contact with the substrate is used. Thus, the liquid discharge head and the base material are discharged without conducting electricity.

[0017] The invention according to claim 5 is a liquid ejection method,

A liquid discharge head having a nozzle plate on which nozzles for discharging liquid toward the substrate are formed and a cavity for storing liquid discharged from the nozzles is applied to the liquid stored in the cavity by applying a driving voltage. A pressure generating step of generating pressure to form a meniscus in the nozzle;

An electrostatic voltage generating step of generating an electrostatic attraction force by applying an electrostatic voltage between the liquid discharge head and a counter electrode facing the discharge surface of the liquid discharge head while supporting the substrate;

A measurement step of measuring a plurality of gaps at different positions between the discharge surface and the base material, and a gap between the liquid discharge head and the base material according to a plurality of measurement results obtained in the measurement step. A gap adjusting step for adjusting

It is characterized by providing.

[0018] According to the invention described in claim 5, the head gap is adjusted according to a plurality of measurement results obtained by measuring gaps at a plurality of different positions between the liquid discharge head and the substrate. After adjusting the head gap, the control means applies an electrostatic voltage and a driving voltage to eject droplets.

[0019] The invention according to claim 6 is the liquid ejection method according to claim 5,

The gap adjusting step adjusts a distance and an inclination between the base material and an ejection surface of the liquid ejection head.

[0020] According to the invention described in claim 6, in the gap adjustment step, the distance and the inclination between the substrate and the discharge surface of the liquid discharge head are adjusted, and the discharge of the liquid discharge head is performed. Adjust the head gap so that the surface and the substrate surface are parallel and at a constant distance.

The invention's effect

[0021] According to the invention described in claim 1, since the liquid droplets are discharged while adjusting the head gap, the head gap can be kept constant and the liquid can be discharged stably. it can. Therefore, it is possible to maintain a constant discharge speed, landing position, etc. Body discharge can be performed. Further, when the liquid is discharged, by adjusting the head gap while relatively moving the liquid discharge head and the substrate, the accuracy of droplet discharge can be improved, and further, the landing accuracy can be improved.

According to the invention described in claim 2, since the distance and inclination between the base material and the ejection surface of the liquid ejection head are adjusted, the head gap can be easily adjusted. In addition, even with a liquid discharge head having a plurality of nozzles, the discharge surface of the liquid discharge head and the base material can be made parallel to make the gap between the open end of each nozzle and the base material constant. Stable liquid discharge is possible. In addition, it is possible to perform more accurate liquid ejection by keeping the ejection speed, landing position, and the like of droplets ejected from each nozzle constant.

According to the invention described in claim 3, the gap can be adjusted accurately by using a piezoelectric element having excellent linearity of output with respect to the input as the gap adjusting means.

[0024] According to the invention as set forth in claim 4, the measuring means is non-contact, and it is possible to prevent electrical conduction between the liquid ejection device and the substrate. In addition, if the liquid discharge head is provided with a measuring means, it is possible to accurately measure the gap without being affected by the vibration caused by the movement of the substrate.

[0025] According to the invention described in claim 5, since the liquid droplets are discharged while adjusting the head gap, the head gap can be kept constant and the liquid can be discharged stably. it can. Accordingly, it is possible to keep the discharge speed, the landing position, and the like of the discharged droplets constant, so that accurate liquid discharge can be performed. Further, when the liquid is discharged, by adjusting the head gap while relatively moving the liquid discharge head and the substrate, the accuracy of droplet discharge can be improved, and further, the landing accuracy can be improved.

[0026] According to the invention described in claim 6, since the distance and the inclination between the base material and the ejection surface of the liquid ejection head are adjusted, the head gap can be easily adjusted. In addition, even with a liquid discharge head having a plurality of nozzles, the discharge surface of the liquid discharge head and the base material can be made parallel to make the gap between the open end of each nozzle and the base material constant. Stable liquid discharge is possible. In addition, it is possible to perform more accurate liquid ejection by keeping the ejection speed, landing position, and the like of droplets ejected from each nozzle constant.

Brief Description of Drawings FIG. 1 is a side view showing a schematic configuration of a liquid ejection apparatus in the present embodiment.

FIG. 2 is a plan view showing a schematic configuration of a liquid ejection apparatus in the present embodiment.

FIG. 3 is a front view showing a schematic configuration of a liquid ejection apparatus in the present embodiment.

FIG. 4 is a cross-sectional view showing a schematic configuration of a liquid discharge head in the present embodiment.

FIG. 5 is a block diagram showing a control configuration of the liquid ejection apparatus in the present embodiment.

FIG. 6 is an explanatory diagram showing a liquid discharge method using the liquid discharge head in the present embodiment.

FIG. 7 is a flowchart showing a flow of gap adjustment in the liquid ejection method of the present embodiment.

Explanation of symbols

[0028] 1 Liquid discharge device

4 Means of transportation

8 Carriage

9 Head Honoreg

10 Housing discharge head

11 Movement detection method

13 Piezoelectric element

14 Control means

15 sensors

16 Angle meter

21 nozzles

23 Discharge surface

25 Electrostatic voltage power supply

29 Piezo elements

30 Discharge drive power supply

31 Displacement detection means

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of a liquid ejection apparatus 1 according to the present invention will be described with reference to the drawings. Light up. However, the scope of the invention is not limited to the illustrated examples.

The liquid ejection apparatus 1 according to the present embodiment ejects liquid droplets from the liquid ejection head 10 toward the substrate K. The liquid discharge apparatus 1 will be described below as a serial type. As shown in FIG. 1, the liquid ejection device 1 is provided with a vibration isolator 7 that removes vibrations of the installation position force. A flat plate-like counter electrode 5 that supports the base material K is provided on the upper surface of the vibration isolation table 7. The counter electrode 5 is grounded and is always kept at the ground potential. A flat insulator 6 is provided below the counter electrode 5 to insulate so that current due to application of electrostatic voltage does not flow to the liquid ejection device 1.

A moving means 4 (see FIG. 5) for moving the counter electrode 5 supporting the base material K together with the insulator 6 is provided on the upper part of the vibration isolation table 7. As shown in FIG. 2, an X linear motor 2 and a Y linear motor 3 are provided which intermittently move the counter electrode 5 in the X direction and the Y direction, respectively. These correspond to the moving means 4. Examples of the X linear motor 2 and the Y linear motor 3 include a general-purpose linear motor with a linear encoder.

As shown in FIG. 3, a carriage 8 that is supported above the base material K and reciprocates in the Y direction is provided as a moving means 4 at a position facing the counter electrode 5 in FIG. The The carriage 8 is provided with a head holder 9 that supports the liquid discharge head 10. The liquid discharge head 10 is a substantially rectangular parallelepiped, and the head holder 9 is attached to the upper surface of the liquid discharge head 10 and two adjacent side surfaces. A carriage 8 is connected to the head holder 9 as a moving means 4 for roughly adjusting the position in the height direction (Z direction) so that the height of the liquid discharge head 10 can be roughly adjusted. It has become. Examples of the carriage 8 include the linear motor with the linear encoder. A linear encoder attached to the linear motor is used as the movement amount detection means 11 of the movement means 4. The head holder 9 is provided with a sensor 15 (see FIG. 2) as a displacement meter for measuring the height of the head holder 9. A known displacement meter can be used. In the present embodiment, the sensor 15 detects the position of the liquid discharge head 10 relative to the counter electrode 5 that may function as the movement amount detection means 11 (see FIG. 5).

A gap adjusting means is provided between the head holder 9 and the liquid discharge head 10 to adjust the distance and inclination between the head holder 9 and the liquid discharge head 10. Gap adjustment means It is an actuator that expands and contracts in proportion to the amount of reasoning, and has a function as a displacement generation means for adjusting the head gap by displacing the position of the liquid discharge head 10. As the above-mentioned actuator, a piezoelectric element is used as an actuator in this embodiment in which a piezoelectric element is preferred because it is easy to manage an output with respect to an input of a physical quantity that can be used without any limitation. That is, in the present embodiment, at least one piezoelectric element 13 as a gap adjusting means for adjusting the distance and inclination between the head holder 9 and the liquid discharge head 10 between the head holder 9 and the liquid discharge head 10. Is provided. At least one of the piezoelectric elements 13 is provided in at least one of the three gaps between the liquid discharge head 10 and the head holder 9 and having different directions. The piezoelectric element 13 is preferably one that can be deformed in units of several zm to make the fine adjustment of the head gap as short as possible.

[0034] Here, two piezoelectric elements 13 are arranged on each of the three surfaces of the liquid ejection head 10, but the distance and inclination between the head holder 9 and the liquid ejection head 10 are adjusted, and as a result, the liquid If the height and angle of the body discharge head 10 can be adjusted, it can be changed as appropriate. Further, a plate panel or the like for amplifying expansion / contraction of the piezoelectric element 13 may be interposed between the piezoelectric element 13 and the liquid discharge head 10. In that case, it is preferable to monitor the amount of deformation of the plate panel or the like with respect to the expansion and contraction of the piezoelectric element 13 and convert it into a head gap adjustment amount for use in control.

On the side surface of the liquid discharge head 10 or around the discharge port, a sensor 15 is disposed as a measurement unit that measures the distance to the substrate K. The sensor 15 is provided with a light emitting means (not shown) that emits light toward the base material K positioned below, and a light receiving means (not shown) that receives the light reflected by the base material K. Is provided. The sensor 15 is not in contact with the base material K, and measures the distance from the base material K based on the output of the light receiving means. There is no particular limitation on the measurement means, but by using a non-contact measurement means (e.g., sensor 15), measurement failure due to conduction between the liquid discharge head 10 and the substrate K or vibration associated with the movement of the substrate K. Etc. can be avoided. The measurement result by the sensor 15 is output to the control means 14 described later. Here, since the head gap is usually about 0.1 to 1 mm, it is preferable that the sensor 15 is capable of measuring with high accuracy in units of several tens / zm. Examples of the sensor 15 include a C MOS type two-dimensional laser length measuring machine and a confocal type. A laser length measuring machine is mentioned.

Further, the liquid discharge head 10 is provided with an angle meter 16 that measures an absolute angle of the liquid discharge head 10 with respect to the vertical direction. The goniometer 16 may measure the absolute angle of the liquid ejection head 10 every time the inclination angle of the liquid ejection head 10 is adjusted by the sensor 15 which may be used to measure the absolute angle of the liquid ejection head 10 continuously. The measurement result by the angle meter 16 is output to the control means 14 described later. Also, instead of the goniometer 16, a plurality of sensors 15 may be arranged and used as a means of measuring the tilt.

Next, a schematic structure inside the liquid ejection head 10 will be described with reference to FIG.

The liquid discharge head 10 is provided with a resin nozzle plate 20 facing the substrate K. In the present embodiment, the thickness of the nozzle plate 20 is preferably 75 m or more for stable droplet discharge. The nozzle plate 20 is also formed with an insulating force, and its volume resistivity is 10 ¹⁵ Ωm or more.

[0039] The nozzle plate 20 is provided with a plurality of nozzles 21 perforating the droplets D of the chargeable liquid L such as ink. The nozzle 21 is formed so as to be tapered toward the base material K toward the base. The diameter of the opening end of the nozzle 21 is preferably 15 m or less so that liquid can be stably discharged even at low electric field strength. In this embodiment, the diameter of the opening end of the nozzle 21 is 10 μm or less, and the nozzle 21 has a large diameter (opposite the opening end) of 100 m. Further, the nozzle 21 is flat so that it does not protrude from the nozzle plate 20 or the protruding amount of the nozzle 21 is about 30 m or less. By using the flat nozzle plate 20, it is possible to easily perform cleaning by wiping. Here, the cross-sectional shape of the nozzle 21 is not limited to the tapered shape and can be changed as appropriate.

[0040] On the substrate K side of the nozzle plate 20, a liquid repellent layer 22 is provided for suppressing the seepage of the liquid L from the nozzle 21. Therefore, the discharge surface 23 of the liquid discharge head 10 in the present embodiment is one surface of the liquid repellent layer 22 on the substrate K side. For the liquid repellent layer 22, for example, a material having water repellency is used if the liquid is aqueous, and a material having oil repellency is used if the liquid L is oily. There are no particular restrictions on the material and formation method of the liquid repellent layer, and any known one can be used as appropriate. In order to improve the adhesion of the liquid repellent layer, a film is formed via an intermediate layer. May be.

[0041] On the upper surface of the nozzle plate 20, a charging electrode 24 for applying an electrostatic voltage to charge the liquid L is provided in a layered manner. The charging electrode 24 is mainly formed of a conductive material such as NiP. The charging electrode 24 extends to the inner peripheral surface of the nozzle 21 and comes into contact with the liquid L in the nozzle 21.

[0042] The charging electrode 24 is connected to an electrostatic voltage source 25 as an electrostatic voltage applying means for applying an electrostatic voltage. The electrostatic voltage power supply 25 is connected with a control means 14 to be described later, and the application operation of the electrostatic voltage is controlled. Since the counter electrode 5 is grounded, an electrostatic attraction force is generated between the liquid discharge head 10 and the counter electrode 5, particularly between the liquid L and the substrate K, when the liquid L is charged. It is supposed to be. In addition, when the droplet D made of the charged liquid L lands on the substrate K, the counter electrode 5 releases the electric charge by grounding.

[0043] On the other surface side of the charging electrode 24, a body layer 26 is provided in a layered form. A substantially cylindrical cavity 27 having the same cross section as the nozzle 21 is formed at a position facing the nozzles 21 of the body layer 26. In the cavity 27, the liquid L discharged through the nozzle 21 is stored for a long time. The cavity 27 communicates with a flow path (not shown) for supplying the liquid L from an external liquid tank (not shown).

[0044] On the other surface side of the body layer 26, a flexible layer 28 made of a flexible metal thin plate, silicon, or the like is provided. Piezo elements 29 that are piezoelectric element actuators are provided at positions corresponding to the cavities 27 on the other surface side of the flexible layer 28. The piezo element 29 is connected to an ejection drive power source 30 as a droplet ejection drive means for applying a drive voltage for deforming the piezo element 29. In the present embodiment, the pressure generating means includes the piezo element 29 and the ejection drive power supply 30. The piezo element 29 is deformed by the application of the drive voltage, and pressure is generated in the liquid L in the nozzle 21. A meniscus is formed at the end. The discharge drive power supply 30 is connected to a control means 14 to be described later, and the drive voltage application operation is controlled.

Next, the control configuration of the liquid ejection apparatus 1 will be described with reference to FIG. 4 or FIG.

The liquid ejection apparatus 1 includes an ejection drive power source 30, an electrostatic voltage power source 25, a moving unit 4, a piezoelectric element Control means 14 is provided which is electrically connected to the child 13, the sensor 15 and the goniometer 16 and controls them. The control means 14 also has a computer power configured by connecting the CPU 14a, the ROM 14b, the RAM 14c, and the like through a BUS (not shown). The control means 14 develops the power supply control program stored in the ROM 14b in the RAM 14c and executes it by the CPU 14a.

When the liquid discharge head 10 starts the liquid discharge, the control unit 14 controls the moving unit 4 so that the liquid discharge head 10 faces the droplet landing start position on the substrate K. Specifically, the counter electrode 5 is moved by the X linear motor 2 and the Y linear motor 3 so that the droplet landing start position of the substrate K is opposed to the liquid discharge head 10 and the height of the head holder 9 is roughly adjusted. At this time, the control means 14 causes the displacement and angle meter 16 to measure the height and tilt of the liquid discharge head 10.

[0048] When discharging the droplet D onto the substrate K, the control unit 14 controls the moving unit 4 to reciprocate the liquid discharge head 10 in the Y direction while facing the substrate K. Further, the control means 14 applies an electrostatic voltage from the electrostatic voltage power supply 25 to generate an electric field between the liquid L and the substrate K, and discharge driving as a pressure generating means based on the droplet discharge signal. The power source 30 is controlled to generate a pressure on the liquid L and discharge the droplet D.

When the liquid is discharged, the control unit 14 controls the sensor 15 to measure the distance between the liquid discharge head 10 and the surface of the substrate K. The control means 14 determines whether or not the measurement results obtained by the sensors 15 match each other, and determines whether or not the discharge surface 23 is parallel to the substrate K. When the measurement results of the sensors 15 do not match, the control means 14 applies a voltage to each piezoelectric element 13 to deform it, and adjusts the distance between the head holder 9 and the liquid ejection head 10. Further, the control means 14 stores a specified value as a head gap in advance, and determines whether or not the measurement result of each sensor 15 matches the specified value. Is adjusted.

[0050] After applying a voltage to each piezoelectric element 13, the control means 14 causes the sensor 15 to measure the deformation amount of each piezoelectric element 13, and stores the deformation amount. The control means 14 includes a liquid discharge head for an applied voltage based on the stored deformation amount. Displacement amount detection means 31 for detecting the displacement amount of the ten ejection surfaces is provided. The control means 14 calculates the amount of deformation of the applied voltage value of each piezoelectric element 13 by the displacement amount detecting means 31 and calculates the voltage value necessary to deform the piezoelectric element 13 by a desired amount. ing.

[0051] Next, a liquid ejection method using the liquid ejection apparatus 1 of the present embodiment will be described.

FIG. 6 is a diagram for explaining drive control of the liquid ejection head 10 by the control means 14. In the present embodiment, for example, the constant electrostatic voltage V applied to the charging electrode 24 from the electrostatic voltage power supply 25 is set to several kV, and the discharge drive power supply 30 applies to the piezo element 29.

C

The following explanation assumes that the applied pulsed drive voltage V is set to 20V.

P First, adjust the yap according to the flowchart shown in Fig. 7.

[0053] The moving means 4 moves the counter electrode 5 to a position orthogonal to the X linear motor 2 and the Y linear motor 3, and makes the liquid discharge head 10 face the droplet landing start position of the substrate K (step Sl ). In addition, the carriage 8 which is the moving means 4 of the liquid discharge head 10 moves the head holder 9 in the Z direction, the displacement meter measures the height of the head holder 9, and the head gap is about 1.0 to 3. Omm. Make coarse adjustments within the range. At the time of rough adjustment, the goniometer 16 measures the absolute angle of the liquid discharge head 10, measures the inclination of the liquid discharge head 10 with respect to the base material K, and determines whether the control means 14 is within the control range.

[0054] Subsequently, in the measurement process, each sensor 15 measures the distance between the position where each sensor 15 is attached and the surface of the base material K. Further, the inclination of the head discharge surface 23 and the base material K is measured by the angle meter 16 (step S2). The measurement result is output to the control means 14. The control means 14 calculates the head gap by subtracting the measurement result force from the distance between the mounting position of each sensor 15 and the discharge surface 23 (step S3). When the calculated head gap differs depending on each sensor 15, or when the inclination angle is detected by the goniometer 16, the control means 14 determines that the discharge surface 23 is inclined with respect to the substrate K. Then, in the gap adjustment step, a piezoelectric element for finely adjusting the tilt angle of the liquid discharge head 10 by expanding and contracting the piezoelectric element 13 is selected, and a voltage applied to each piezoelectric element 13 is calculated (step S4). If the measured value of the sensor 15 is different from the pre-stored V and the specified value as the head gap, the specified value A piezoelectric element for canceling the deviation is selected, and a voltage applied to each piezoelectric element 13 is calculated (step S4).

Next, in the gap adjustment step, the calculated voltage is amplified and applied to each selected piezoelectric element 13, and each piezoelectric element 13 is expanded and contracted to finely adjust the height and inclination angle of the liquid ejection head 10. (Step S5)

During the fine adjustment, the control means 14 applies a voltage to each piezoelectric element 13 based on the amount of deviation of the measurement result calculated by each sensor 15. Here, the piezoelectric element 13 is provided between the head holder 9 and the liquid discharge head 10, and the head holder 9 is fixed to the carriage 8. The head gap between the discharge surface 23 and the substrate K can be adjusted by adjusting the distance between the liquid discharge heads 10. In addition, since the piezoelectric elements 13 are disposed at both ends of each surface of the liquid discharge head 10, the distance and inclination of the liquid discharge head 10 with respect to the head holder 9 are changed by deformation of at least one of the paired piezoelectric elements 13. The gap between the discharge surface 23 and the surface of the base material K can be adjusted.

After the voltage is applied to the piezoelectric element 13, the sensor 15 and the goniometer 16 measure the head gap again (step S6). The measurement result is output to the control means 14, and the measurement result is compared with the target value to determine whether it is within the target range (step S7). If it is within the target range (step S7: YES), the gap adjustment is completed and the process moves to drawing. If it is not within the target range (step S7: NO), return to step S3 and adjust the gear again.

Steps S3 to S7 are repeated until the measurement result falls within the target range.

In the above flow, the measurement result is output to the control unit 14, and the displacement amount of the head gap due to voltage application is detected and output to the displacement amount detection unit 31. In the displacement amount detection step, the displacement amount detection means 31 detects the displacement amount of the ejection surface of the liquid ejection head 10 with respect to the voltage amount applied to the piezoelectric element 13. The detection result is output to the control means 14 and used to calculate the voltage value to be applied in the subsequent gap adjustment step. Each time the piezoelectric element 13 is deformed by applying a voltage, the displacement amount of the head gap is fed back to the displacement amount detecting means 31 to influence the thermal expansion of the piezoelectric element 13 and the difference between the upstream voltage and the downstream voltage. The gap adjustment process can be performed in consideration.

[0056] When the head gap is adjusted in this way, the carriage 8 reciprocates the liquid ejection head 10 in the Y direction. Then, the liquid discharge head 10 applies an electrostatic voltage from the electrostatic voltage power supply 25 to generate an electric field between the liquid L and the substrate K, and stores the discharge drive power supply 30 in the cavity 27 by applying the discharge drive power supply 30. A pressure is generated on the liquid L and the droplet D is ejected. Specifically, as shown in FIG. 6, in the electrostatic voltage generation process, the electrostatic voltage power supply 25 is connected to the charging electrode 2.

A constant electrostatic voltage V is applied to 4 and each nozzle 21 of the liquid discharge head 10 and the counter electrode 5 and c

An electric field is generated between them (see A in Fig. 6). In the pressure generation step, the ejection drive power supply 30 applies a pulsed drive voltage Vp to deform the piezo element 29. The pressure of the liquid L inside the nozzle 21 increases due to deformation of the piezo element 29, and a meniscus is formed at the open end of the nozzle 21 (see B in Fig. 6).

If a meniscus is formed in a state where an electric field is generated between the nozzle 21 and the counter electrode 5, a high electric field concentration occurs at the tip of the meniscus, and a very strong electrostatic force is applied. If the application of the drive voltage V is stopped in this state, the meniscus will be generated without generating mist or satellite.

P

The force S is torn off and droplet D is ejected (see C in Fig. 6). The ejected droplet D flies to the substrate by force, is accelerated by the electric field, and is sucked toward the counter electrode 5 (see D in FIG. 6). When the droplet D reaches the target point of the substrate K supported by the counter electrode 5, the potential of the droplet D becomes equal to the potential of the counter electrode 5, and the same potential is obtained (see E in FIG. 6).

When the liquid ejection head 10 and the base material K are relatively moved, the control unit 14 performs the above-described measurement process and gap adjustment process. Here, the measurement step and the gap adjustment step may be performed during intermittent conveyance of the base material, or at every elapse of a fixed time which may be performed every intermittent conveyance.

Furthermore, even when the liquid discharge head 10 including the plurality of nozzles 21 is provided in the liquid discharge apparatus 1 of the present embodiment, in order to adjust the distance and the inclination between the discharge surface 23 and the substrate K, By flattening the discharge surface 23, the distance between the open end of each nozzle 21 and the substrate K can be kept constant, and stable liquid discharge is possible. By adjusting the discharge speed and direction of each nozzle 21, the discharged droplet can be landed at a more accurate position.

[0059] A head gap can be easily adjusted by applying a voltage to the piezoelectric element 13 based on the measurement result of the sensor 15. Sarako, equipped with multiple piezoelectric elements 13 in the liquid discharge head 10 Therefore, the distance and inclination of the discharge surface 23 relative to the base material K can be adjusted.

[0060] Power! In addition, by detecting the amount of displacement of the ejection surface of the liquid ejection head 10 with respect to the voltage applied to the piezoelectric element 13, it is possible to calculate the voltage value necessary to cancel the difference between the measurement result by the sensor 15 and the target value. Yes, adjustment of the head gap is easy. Also

The displacement amount detection means 31 measures and detects the distance and inclination between the discharge surface 23 and the substrate Κ, thereby moving the displacement means 4 according to the thermal expansion of each member including the piezoelectric element 13. By applying a correction voltage to the piezoelectric element 13 to correct the difference between the discharge surface 23 caused by the fluctuation and the substrate に対する and the target value of the inclination, the distance and inclination between the discharge surface 23 and the substrate Κ Can be kept constant.

[0061] As the pressure generating means for forming a meniscus in the nozzle 21 of the liquid discharge head 10, in addition to the piezoelectric element actuator as in the present embodiment, for example, an electrostatic actuating system is used. It is also possible to adopt.

In the present embodiment, the liquid ejecting apparatus 1 has been described as a serial type, but can also be applied to a line type or the like. In the present embodiment, the counter electrode 5 is grounded and an electrostatic voltage is applied to the charging electrode 24 of the liquid discharge head 10. The electrostatic discharge voltage is applied to the counter electrode and the liquid discharge head 10 side is grounded. It is also good to do.

In the present embodiment, at least one of the meniscus formed at the opening end of the nozzle 21 and the still image or moving image of the flying droplet D is formed in the gap between the liquid discharge head 10 and the base plate. It is also acceptable to provide an imaging means for imaging and detecting abnormal ejection of droplets. As a means for imaging, a known power source such as a camera can be used without particular limitation. CCD cameras are preferred because they can continuously capture an imaging target. When abnormal ejection of droplets is detected by the imaging means, it is preferable to perform maintenance such as adjusting the head gap and cleaning the ejection surface 23.

In the present embodiment, the liquid discharge head 10 is provided with the sensor 15 as the measuring means, but the measuring means may be provided on the counter electrode 5 side. In that case, by disposing the measuring means outside the region of the counter electrode 5 that supports the substrate K, it is possible to measure the distance and the inclination with respect to the ejection surface of the liquid ejection head 10 without interposing the substrate K. The By providing the measuring means so as to face the standby position of the liquid discharge head 10, the liquid It is preferable that the head gap can be adjusted each time the droplet discharge operation of the body discharge head 10 is completed.

In the present embodiment, the control unit 14 stores a predetermined value as a head gap in advance, but the discharge surface 23 and the base material K are used using a high-precision displacement meter at the stage of coarse adjustment. It is also possible to adjust the distance and inclination between the discharge surface 23 and the substrate K by the gap adjusting means.

In the present embodiment, the piezoelectric element 13 as the gap adjusting means adjusts the height and inclination of the liquid discharge head 10, but is provided below the counter electrode 5 to increase the height of the base material K. It is also possible to adjust the head gap by adjusting the tilt and tilt. As a measurement means for measuring the gap between the discharge surface of the liquid discharge head 10 and the substrate K, the liquid discharge head 10 is provided with the sensor 15, but the measurement means may be provided on the counter electrode 5 side. good.

As described above, according to the liquid discharge apparatus 1 of the present embodiment, since the liquid droplet is discharged while adjusting the head gap, the head gap can be kept constant and the liquid discharge can be stably performed. Can go out. Accordingly, it is possible to keep the droplet discharge speed, the landing position, etc. constant, and to perform accurate liquid discharge. In addition, when discharging liquid droplets, the liquid discharge accuracy can be improved by adjusting the head gap while moving the liquid discharge head 10 relative to the substrate K.

Claims

The scope of the claims

[1] A liquid discharge head having a nozzle plate on which nozzles for discharging liquid toward a substrate are formed, and a cavity for storing liquid discharged from the nozzles;

Pressure generating means for applying a driving voltage to generate pressure in the liquid stored in the cavity to form a meniscus in the nozzle;

A counter electrode that supports the substrate while facing the discharge surface of the liquid discharge head, and an electrostatic voltage that generates an electrostatic attraction force by applying an electrostatic voltage between the liquid discharge head and the counter electrode. Generating means;

And a control unit that controls the gap adjusting unit according to a measurement result of the measuring unit.

[2] The liquid ejection apparatus according to [1], wherein the gap adjusting unit adjusts a distance and an inclination between the base material and an ejection surface of the liquid ejection head.

[3] The liquid ejection device according to [1] or [2], wherein the gap adjusting means is a piezoelectric element.

[4] The liquid ejecting apparatus according to any one of [1] to [3], wherein the measurement unit measures the gap without contacting the base material.

[5] A drive voltage is applied to a liquid discharge head having a nozzle plate on which nozzles for discharging liquid toward the substrate are formed and a cavity for storing liquid discharged from the nozzles, and stored in the cavity. Pressure generating step of generating pressure on the liquid to form a meniscus in the nozzle;

A measuring step for measuring gaps at a plurality of different positions between the discharge surface and the substrate, and the liquid discharge head and the base according to a plurality of measurement results obtained in the measuring step. A gap adjusting step for adjusting the gap between the material and

A liquid ejection method comprising:

6. The liquid ejection method according to claim 5, wherein the gap adjustment step adjusts a distance and an inclination between the base material and an ejection surface of the liquid ejection head.