JP4419494B2 - Droplet ejection device, driving method of droplet ejection device, and manufacturing method of display device - Google Patents

Description

  The present invention relates to a droplet discharge device, a driving method thereof, a display device manufacturing method using the same, and a display device.

As a method for arranging a predetermined amount of liquid material at a desired position, a droplet discharge method such as an ink jet method is known.
A droplet discharge head used in this droplet discharge method includes, for example, a cavity containing a liquid material, a nozzle plate having a nozzle communicating with the cavity, and changing the internal volume by vibrating the cavity. And a pressure generating element that discharges the liquid material in the cavity from the discharge port of the nozzle.

  By the way, in such a droplet discharge process by the droplet discharge head, a cap is attached to the discharge surface side of the droplet discharge head when preparing for discharge or when clogging occurs during discharge. The air bubbles in the droplet discharge head are removed or the liquid clogging is eliminated by suctioning with a vacuum pump or the like. Then, after performing suction in this manner, the liquid surface remaining on the discharge surface is wiped off by wiping the discharge surface of the droplet discharge head with a wiping material.

However, even if the liquid is sucked or wiped in this way, until the main discharge for actually discharging the droplet onto the member to be dropped is performed until the droplet discharge head is idle or discharged. There will be a time during which no discharge will occur. During this time, the surface of the meniscus of the liquid in the cavity dries and the viscosity increases, which may cause inconvenience that the liquid is not discharged in the first shot.
Therefore, in a conventional ink jet device (see, for example, Patent Document 1 and Patent Document 2), in order to prevent the meniscus in the nozzle from touching the outside air and forming a film on the surface, for example, a liquid material in the cavity is formed by a pressure generating element. On the other hand, a slight vibration that does not discharge droplets is applied.
Japanese Patent Laid-Open No. 9-11457 Japanese Patent Laid-Open No. 9-29996

  However, by giving such a slight vibration, it is possible to discharge the first shot in the main discharge, but the meniscus in the nozzle is greatly shaken by the slight vibration. A new problem such as deterioration in accuracy occurs. Such a deterioration in landing accuracy is particularly noticeable when discharging a highly viscous liquid having a viscosity of 10 mPa · s or more.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to enable discharge in the first shot in the main discharge after idle running of the droplet discharge head or standby until discharge. An object of the present invention is to provide a droplet discharge device and a driving method thereof, and a display device manufacturing method and a display device using the same, which can improve landing accuracy.

  In order to achieve the above object, a droplet discharge device according to the present invention includes a cavity containing a liquid material, a nozzle communicating with the cavity, and vibrating the cavity to change its internal volume, thereby changing the inside volume of the cavity. A droplet discharge head including a pressure generating element for discharging the liquid material from the nozzle as droplets, a contraction signal for continuously contracting the pressure generating element from a predetermined state, and a contracted pressure A maintenance signal for maintaining the generating element in the contracted state and a recovery signal for recovering the pressure generating element to a steady state by continuously releasing the contracted state of the pressure generating element to the pressure generating element. Drive means for sending out as a drive signal, and the drive means has a discharge waveform consisting of the drive signal for discharging droplets from the nozzle as the pressure generating element. Before the liquid is delivered to the nozzle, it is composed of the contraction signal, the maintenance signal, and the recovery signal as a fine vibration waveform that gives a fine vibration to the liquid in the cavity without discharging a droplet from the nozzle. A control unit is provided that sends a drive signal to the pressure generating element that sets the delivery time to 1 μs or more and 100 μs or less and is approximately an integral multiple of the natural vibration period of the cavity.

  Further, the method for driving the droplet discharge device according to the present invention includes a cavity for accommodating a liquid material, a nozzle communicating with the cavity, and vibrating the cavity to change its internal volume, thereby changing the liquid in the cavity. A method for driving a droplet discharge device comprising a droplet discharge head including a pressure generating element that discharges a body as a droplet from the nozzle, wherein the pressure generating element is continuously contracted from a predetermined state. A contraction signal for maintaining the contracted pressure generating element in the contracted state, and a recovery signal for recovering the pressure generating element to a steady state by continuously releasing the contracted state of the pressure generating element Is sent as a drive signal to the pressure generating element, and a discharge waveform composed of the drive signal for discharging a droplet from the nozzle is expressed as the pressure generating element. Prior to delivery, the contraction signal, the maintenance signal, and the recovery signal are used as a micro-vibration waveform that imparts micro-vibration to the liquid material in the cavity without discharging droplets from the nozzle. A drive signal is sent to the pressure generating element so that the time is set to 1 μs or more and 100 μs or less and is approximately an integral multiple of the natural vibration period of the cavity.

According to the droplet discharge device and the driving method thereof, the recovery time of the recovery signal is set to 1 μs or more and 100 μs or less as a fine vibration waveform for giving a fine vibration to the liquid in the cavity, and substantially the natural vibration period of the cavity. Since the drive signal for an integral multiple of time is sent from the control unit to the pressure generating element, the meniscus fluctuation in the liquid nozzle caused by this drive signal is synchronized with the natural vibration period of the cavity. Will decay and stop more quickly.
Therefore, the first shot of the main discharge can be discharged due to the fine vibration effect, and the meniscus shake due to the fine vibration stops more quickly, so that the discharge of the first shot due to the meniscus shake can be prevented. The landing accuracy is prevented from deteriorating.
Further, by setting the recovery signal transmission time to 1 μs or more, the effect of attenuating the meniscus swing is secured, and by setting it to 100 μs or less, thickening due to drying of the meniscus surface in the nozzle can be suppressed.

In the droplet discharge device and the driving method thereof, the drive signal that is the fine vibration waveform sent out from the control unit has the same contraction signal sending time as the natural vibration period of the pressure generating element. It is preferably longer than this and shorter than the natural vibration period of the cavity.
In this way, the sending time of the contraction signal is set to be equal to or longer than the natural vibration period of the pressure generating element, so that an excessive load is prevented from being applied to the pressure generating element. Further, if it is longer than the natural vibration period of the cavity, it becomes difficult to discharge in the first shot in the main discharge, but since it is shorter than this, it is possible to discharge in the first shot in the main discharge.

Further, in the droplet discharge device and the driving method thereof, the drive signal that is the fine vibration waveform sent from the control unit has a sum of the sending time of the contraction signal and the sending time of the maintenance signal, Preferably, it is approximately equal to the sum of the time that is an integral multiple of the natural vibration period and the time that is half the natural vibration period of the cavity.
In this way, the sum of the sending time of the contraction signal and the maintenance signal in the micro vibration waveform is an integral multiple plus half of the natural vibration period of the cavity, so that the natural vibration of the cavity cancels the micro vibration waveform. Works. Therefore, the attenuation of the meniscus swing due to the fine vibration waveform is accelerated, and thereby the meniscus swing stops more quickly.

Further, in the droplet discharge device and the driving method thereof, the drive signal having the fine vibration waveform sent from the control unit has a voltage value of the sustain signal of the sustain signal in the drive signal having the discharge waveform. It is preferably 30% or more and 60% or less of the voltage value.
By setting the voltage value of the sustain signal in the drive signal having a fine vibration waveform to 30% or more of that in the case of the discharge waveform, the meniscus can be satisfactorily caused by drawing the meniscus toward the cavity. . Further, by setting the ratio to 60% or less, the meniscus swings greatly, and a part of the liquid material comes out of the nozzle, and the outer surface of the nozzle plate on which the nozzle is formed is soiled, resulting in a decrease in ejection performance. Is prevented.

In the droplet discharge device and the driving method thereof, the liquid may have a viscosity of 10 mPa · s or more.
When the liquid material has such a high viscosity, the deterioration of the landing accuracy is particularly noticeable in the past, but the landing accuracy is deteriorated by stopping the meniscus shake due to the slight vibration as described above. Can be prevented.

In the display device manufacturing method of the present invention, the step of discharging the liquid material using the droplet discharge device or the method of driving the droplet discharge device is one of the display device manufacturing steps. It is characterized by having prepared.
According to this display device manufacturing method, the manufacturing process of the display device including the step of discharging the liquid material enables discharge in the first shot in the main discharge, and also prevents deterioration in landing accuracy. Thus, the reliability of the obtained display device is improved.

The present invention will be described in detail below.
(Overall configuration of droplet discharge device)
FIG. 1 is a perspective view showing an embodiment in which the liquid droplet ejection apparatus of the present invention is applied to an ink jet apparatus. Reference numeral 10 in FIG. 1 denotes an ink jet apparatus (liquid droplet ejection apparatus).
In the ink jet apparatus 10, the carriage 11 is connected to a pulse motor 13 through a timing belt 12, and is guided by a guide member 14 so as to reciprocate in the width direction of the dropped member 15. The carriage 11 has an ink jet head (droplet discharge head) 16 attached to the surface facing the dropping member 15, that is, the lower surface thereof.

  The head 16 receives ink (liquid material) from an ink cartridge 17 placed on the carriage 11 and discharges ink droplets (droplets) as dots in accordance with the movement of the carriage 11. The droplet is disposed at a desired position on the dropping member 15. Further, a capping device 18 is disposed in the non-dropping region of the ink jet device 10 and seals the nozzle outlet of the head 16 during the pause, while the ink is discharged from the head 16 by the flushing operation performed during the dropping operation. It is designed to receive drops. Further, a cleaning device 19 is disposed in the vicinity of the capping device 18. In this cleaning device 19, the surface of the head 16 is wiped with a wiping material such as a blade so as to wipe off ink scum adhering thereto. It has become.

(Head configuration)
FIG. 2 is a cross-sectional view showing a schematic configuration of the head 16.
As shown in FIG. 2, the head 16 is provided with a nozzle plate 110, and a nozzle 111 is formed on the nozzle plate 110. A liquid repellent film 110a is formed on the outer surface side of the nozzle plate 110, and an opening of the nozzle 111 on the side where the liquid repellent film 110a is formed serves as a discharge port 111a.

  The liquid repellent film 110a is a plasma polymerization film made of a fluorine resin. As a method for forming the liquid repellent film 110a, for example, a plasma processing method using tetrafluoromethane or another fluorocarbon-based gas as a processing gas in an air atmosphere is employed. By appropriately setting the conditions for such plasma treatment, the static contact angle and receding contact angle of the obtained plasma polymerized film (liquid repellent film 110a) with respect to the liquid can be set to desired angles.

  In the head 16, the flow path forming plate 112 has a through hole that divides the cavity 113, a through hole or groove that divides the two ink supply ports 114 communicating with the cavity 113 on both sides, and the ink supply ports 114. A through hole is formed that divides two common ink chambers 115 communicating with each other. The diaphragm 116 is made of an elastically deformable thin plate, is in contact with the tip of a piezoelectric vibrator (pressure generating element) PZT such as a piezoelectric element, and has a nozzle plate with the flow path forming plate 112 interposed therebetween. The flow path unit 118 is constituted by being fixed integrally with the liquid 110 in a liquid-tight manner.

  The base 119 includes an accommodation chamber 120 that accommodates the piezoelectric vibrator PZT so as to vibrate and an opening 121 that supports the flow path unit 118, and the tip of the piezoelectric vibrator PZT is exposed from the opening 121. The piezoelectric vibrator PZT is fixed by a fixed substrate 122. The base 119 holds the head 16 together by fixing the flow path unit 118 to the opening 121 in a state where the island 116 a of the diaphragm 116 is in contact with the piezoelectric vibrator PZT.

  With such a configuration, when the piezoelectric vibrator PZT contracts and the diaphragm 116 bends and the cavity 113 vibrates to increase its internal volume, the ink (liquid material) in the common ink chamber 115 is supplied with ink. It flows into the cavity 113 via the mouth 114. Further, when the piezoelectric vibrator PZT expands after a predetermined time elapses and the diaphragm 116 returns to its original state and the cavity 113 contracts to reduce its internal volume, the ink in the cavity 113 is compressed and the nozzle 111 discharges. Ink droplets (droplets) are ejected from the outlet 111a.

(Configuration of control system and drive system)
Next, the configuration of the control system and drive system of the inkjet apparatus 10 will be described with reference to FIG.
As shown in FIG. 3, the control circuit 60 in the inkjet apparatus 10 receives, for example, a discharge command signal and discharge data from the host, and controls the drive signal generator 61, the memory 62, the shift register 63, and the latch circuit 64, respectively. It is comprised as mentioned above and becomes a control part in the present invention.

The drive signal generating device 61 ejects ink as a drive waveform as a voltage to be applied to the piezoelectric vibrator PZT (pressure generating element), giving a fine vibration to the ink (liquid material) in the cavity 113, and ink. A head drive circuit that generates a discharge waveform for generating the waveform, and is configured to send out each waveform generated by the head drive circuit, which is a drive means in the present invention.
The memory 62 stores discharge data input via the control circuit 60.
The shift register 63 stores the ejection data serially transferred from the memory 62.
The latch circuit 64 latches the ejection data stored in the shift register 63 at the same time. By controlling on / off of the transistor T, the latch circuit 64 controls the drive signal (from the drive signal generator 61 to the piezoelectric vibrator PZT). Drive voltage) is selectively applied.

(Description of drive circuit and drive pulse)
Next, an example of a head drive circuit in the drive signal generator 61 and a drive signal (drive pulse) formed therein will be described with reference to FIGS. FIG. 4 is a circuit diagram of the head drive circuit 30. FIGS. 5A and 5B are waveform diagrams of drive signals (drive pulses) formed by the head drive circuit. FIG. 5A is a view showing the discharge waveform A, and FIG. It is a figure which shows the fine vibration waveform B. Here, the fine vibration waveform B is sent to the piezoelectric vibrator (pressure generating element) PZT as shown in FIG. 5B before the discharge waveform A for discharging is sent.

  As shown in FIG. 4, the drive voltage generation circuit 31 of the head drive circuit 30 includes a one-shot multivibrator 50 that converts a timing signal 49 from the control circuit 60 into a pulse signal having a constant width, and this one-shot multivibrator. 50 is configured to output a positive signal and a negative signal from the output terminal in synchronization with the timing signal 49. The base of the NPN transistor 51 is connected to this one terminal via a resistor, and the PNP transistor 52 is connected to this one via a resistor. Therefore, when the timing signal is input, the first terminal is connected to the first terminal. From the power source (not shown), the capacitor 53 is charged with a constant current until the terminal voltage thereof reaches the voltage of the first power source. Here, the first power source is a power source generated from the main power source. Since the charging current at this time is defined by the base-emitter voltage of the transistor 54 and the resistance value of the resistor 56, the rising slope of the capacitor 53 is thereby defined.

  An NPN transistor 58 is connected to the other terminal of the one-shot multivibrator 50. When the timing signal is switched, the NPN transistor 58 is turned on instead of the PNP transistor 52 being turned off. Become. As a result, the charge charged in the capacitor 53 is discharged at a constant current until the terminal voltage reaches a predetermined value. Since the discharge current at this time is defined by the base-emitter voltage of the transistor 55 and the resistance value of the resistor 57, the falling gradient of the capacitor 53 is thereby defined. Accordingly, the terminal voltage (drive pulse Vin) of the capacitor 53 maintains a constant value and a region VA (also referred to as a rising signal VA) that rises at a constant gradient, as shown by, for example, the ejection waveform A in FIG. Saturation region VB (also referred to as sustain signal VB), a region VC falling at a constant gradient (also referred to as falling signal VC), and a region where a pull-in voltage of 10 V is applied as an intermediate voltage (lead-in signal VD). Waveform.

  As a result, the terminal voltage of the capacitor 53 is output as a drive pulse Vin to the bases of the NPN transistor Q1 and the PNP transistor Q2 included in the current amplifier circuit of the drive voltage generation circuit 31, and the current amplifier circuit Current amplified and output to the piezoelectric vibrator PZT via the connection point P0 of the transistors Q1 and Q2. During this time, the piezoelectric vibrator PZT is charged through one transistor Q1, and the piezoelectric vibrator PZT is discharged through the other transistor Q2.

  The drive pulse Vin having the waveform generated in this way maintains the maximum potential for a predetermined time in the sustain signal VB after the voltage value of the rising signal VA rises with a constant gradient from the intermediate potential to the maximum potential. Next, in the falling signal VC, the drive pulse falls at a constant gradient to the lowest potential. Next, after maintaining in this state for a predetermined time, the pull-in signal VD returns to the intermediate potential, and then the intermediate potential is maintained.

  Therefore, in the head 16 shown in FIG. 2, when the voltage value of the drive pulse Vin rises from the intermediate potential to the maximum potential, the piezoelectric vibrator PZT contracts, the internal volume of the cavity 113 increases, and a negative pressure is generated in the cavity 113. The ink flows into the cavity 113 while this state is maintained. Subsequently, when the voltage value decreases to the lowest potential, the contraction of the piezoelectric vibrator PZT is released, the shape returns to the direction in which the internal volume of the cavity 113 decreases, and positive pressure is generated in the cavity 113, and ink is ejected from the ejection port 111a. Drops are ejected. Furthermore, when the voltage value rises from the lowest potential to the intermediate potential, the piezoelectric vibrator PZT slightly contracts, and the internal volume of the cavity 113 slightly increases, so that the ink near the ejection port 111a in the nozzle 111 is obtained. A meniscus (not shown) of the (liquid material) is pulled back to the cavity 113 side to be in an initial state (predetermined state) for the next discharge.

  Here, the configuration of the drive pulse (drive signal) Vin will be described in comparison with the ink droplet ejection mode. As shown in FIG. 5A, the drive pulse Vin starts the piezoelectric vibrator PZT from a predetermined state. By continuously releasing the contraction signal VA for continuously contracting to the contraction state before ink droplet ejection, the maintenance signal VB for maintaining the contraction state, and the contraction state of the piezoelectric vibrator PZT, the piezoelectric vibration is obtained. And a recovery signal VC for reducing the internal volume of the cavity 113 by restoring the child PZT to a steady state. Note that the contraction signal VA, the maintenance signal VB, and the contraction signal VC constituting the ejection waveform A as described above are elements constituting the micro-vibration waveform B even in the micro-vibration waveform B shown in FIG. ing.

  That is, also in the fine vibration waveform B in the present invention, the drive pulse (drive signal) Vin includes a contraction signal VA that continuously contracts the piezoelectric vibrator PZT from a predetermined state, and a maintenance signal VB that maintains this contraction state. And a recovery signal VC for reducing the internal volume of the cavity 113 by continuously releasing the contraction state of the piezoelectric vibrator PZT to restore the piezoelectric vibrator PZT to a steady state. Here, this fine vibration waveform B is sent when the head 16 is idle or before waiting for the discharge before the main discharge by the discharge waveform A, and is sent to the liquid in the cavity 113. This is to allow the first shot to be discharged in the main discharge by applying a slight vibration to shake the meniscus in the nozzle 111 and prevent the meniscus portion from thickening due to solvent evaporation. Therefore, in the minute vibration waveform B, the voltage value of the sustain signal VB is smaller than the voltage value of the sustain signal VB in the drive signal that becomes the ejection waveform A, and thus the droplets are not ejected from the nozzle 111. It is like that.

In particular, each signal in the fine vibration waveform B is set as follows.
That is, in this fine vibration waveform B, the recovery signal VC is a time during which the delivery time is substantially an integral multiple of the natural vibration period of the cavity 113, and is 1 μs or more and 100 μs or less.
With this setting, the meniscus swing in the liquid nozzle 111 caused by the recovery of the piezoelectric vibrator PZT by this recovery signal VC (drive signal) is synchronized with the natural vibration period of the cavity 113. To come. By synchronizing in this way, the meniscus swing is attenuated by the natural vibration of the cavity 113, and thus is attenuated faster than when not synchronizing with the natural vibration period of the cavity 113, resulting in a meniscus. The tremor stops more quickly.

Therefore, when the discharge waveform A is sent after this fine vibration waveform B as shown in FIG. It is hardly affected by the fine vibration waveform B, and therefore the landing accuracy is improved without deteriorating.
It should be noted that the liquid in the cavity 113 due to the minute vibrations causes the meniscus in the nozzle 111 to sway and prevent local thickening due to solvent evaporation at the meniscus, thereby preventing the liquid in the main discharge. The discharge in the first shot is favorably performed.

  Further, since the recovery signal transmission time is set to 1 μs or longer, the effect of attenuating the meniscus fluctuation is ensured. On the other hand, since it is set to 100 μs or less, thickening due to drying of the meniscus surface in the nozzle 111 is suppressed, and as described above, the first discharge in the main discharge is favorably performed.

In the fine vibration waveform B, the delivery time of the contraction signal VA is equal to or longer than the natural vibration period of the piezoelectric vibrator PZT and shorter than the natural vibration period of the cavity 113.
Thus, by making the sending time of the contraction signal VA equal to or longer than the natural vibration period of the piezoelectric vibrator PZT, it is possible to prevent an excessive load from being applied to the piezoelectric vibrator PZT. Deterioration and destruction of the piezoelectric vibrator PZT can be prevented. Further, it has been experimentally known that if the delivery time of the contraction signal VA is made longer than the natural vibration period of the cavity 113, the discharge in the first shot in the main discharge tends to become difficult. In the main discharge, the first shot can be discharged satisfactorily.

  This is considered to be because if the delivery time of the contraction signal VA is made longer than the natural vibration period of the cavity 113, the meniscus portion in the nozzle 11 is maintained in a film state. That is, if the delivery time of the contraction signal VA is made shorter than the natural vibration period of the cavity 113, the meniscus portion formed into a film in the nozzle 11 is broken by the rapid contraction of the piezoelectric vibrator PZT, and the liquid material in the meniscus portion is This is because the liquid material in the inside or the nozzle 111 is in the same state.

In the fine vibration waveform B, the sum of the sending time of the contraction signal VA and the sending time of the maintenance signal VB is an integral multiple of the natural vibration period of the cavity 113 and the natural vibration period of the cavity 113. It is almost equal to the sum of half the time.
By doing so, the sum of the sending time of the contraction signal VA and the maintenance signal VB in the fine vibration waveform B becomes an integral multiple plus half of the natural vibration period of the cavity 11. Then, since the remaining recovery signal VC in the fine vibration waveform B has a sending time that is almost an integral multiple of the natural vibration period of the cavity 113 as described above, the entire sending time of the fine vibration waveform B is also large. , Approximately equal to an integral multiple plus half of the natural vibration period of the cavity 11.

Then, the vibration (fine vibration) of the piezoelectric vibrator PZT generated by the fine vibration waveform B and the natural vibration of the cavity 113 are, for example, that the natural vibration of the cavity 113 is shifted by a half cycle of the vibration phase represented by a sine curve. It acts so as to cancel the fine vibration of the piezoelectric vibrator PZT. Accordingly, since the time until the fine vibration of the piezoelectric vibrator PZT is attenuated is accelerated, the attenuation of the meniscus fluctuation due to the fine vibration of the piezoelectric vibrator PZT is also accelerated, thereby stopping the meniscus fluctuation more quickly. To come.
Therefore, when the ejection waveform A is sent after the micro-vibration waveform B as shown in FIG. 5B due to the rapid stop of the meniscus swing, The influence by the minute vibration waveform B is hardly received, and the landing accuracy is improved as described above.

In the fine vibration waveform B, the voltage value Vh (B) of the sustain signal VB is 30% or more and 60% or less of the voltage value Vh (A) of the sustain signal VB in the drive signal that becomes the ejection waveform A. It has become.
Thus, by setting the voltage value Vh (B) of the sustain signal in the fine vibration waveform B to 30% or more of the discharge waveform A, the meniscus in the nozzle 111 can be satisfactorily drawn into the cavity 113 side. Become. Since the meniscus can be drawn in this way, the meniscus can be satisfactorily shaken, so that the liquid in the cavity 113 and the nozzle 111 can be agitated, and the solvent concentration and the like can be made uniform. .
Further, by setting the ratio to 60% or less, the meniscus swings greatly, and a part of the liquid material comes out of the nozzle 111, and the outer surface of the nozzle plate 110 is soiled, so that the discharge performance is lowered. Can be prevented.

In such an ink jet device 10, a liquid having a high viscosity of, for example, 10 mPa · s or more can be used as the liquid discharged from the head 16.
When the liquid material has such a high viscosity, the deterioration of the landing accuracy is particularly noticeable in the past. However, as described above, the landing accuracy is deteriorated by stopping the meniscus shake due to the slight vibration more quickly. Can be prevented and good discharge can be performed.

(Display device)
Next, an example of a display device manufactured using the inkjet device (droplet discharge device) 10 will be described.
FIG. 6 is a side sectional view of an organic EL display device in which some components are manufactured by the inkjet device 10. First, a schematic configuration of the organic EL display device will be described.
As shown in FIG. 6, the organic EL display device 301 includes a substrate 311, a circuit element portion 321, a pixel electrode 331, a bank portion 341, a light emitting element 351, a cathode 361 (counter electrode), and a sealing substrate 371. A wiring of a flexible substrate (not shown) and a driving IC (not shown) are connected to the organic EL element 302. In the circuit element portion 321, an active element made of a TFT or the like is formed on the substrate 311, and a plurality of pixel electrodes 331 are arranged on the circuit element portion 321. Bank portions 341 are formed in a lattice shape between the pixel electrodes 331, and light emitting elements 351 are formed in the recess openings 344 generated by the bank portions 341. The cathode 361 is formed on the entire upper surface of the bank portion 341 and the light emitting element 351, and a sealing substrate 371 is laminated on the cathode 361.

  The manufacturing process of the organic EL device 301 including the organic EL element includes a bank part forming step for forming the bank part 341, a plasma processing step for appropriately forming the light emitting element 351, and each functional layer constituting the light emitting element 351. A step of forming a light emitting element, a counter electrode forming step of forming a cathode 361, and a sealing step of stacking and sealing a sealing substrate 371 on the cathode 361.

  In the light emitting element formation step, the light emitting element 351 is formed by forming each functional layer including the hole injection layer 352 and the light emitting layer 353 on the concave opening 344, that is, the pixel electrode 331. A step and a light emitting layer forming step. In the hole injection layer forming step, a liquid material for forming the hole injection layer 352 is discharged onto each pixel electrode 331, and the discharged liquid material is dried to form the hole injection layer 352. The light emitting layer forming step includes a discharge step of discharging a liquid material for forming the light emitting layer 353 onto the hole injection layer 352, and a light emission by drying the discharged liquid material. A drying step of forming the layer 353.

  In particular, as a liquid material for forming the hole injection layer 352, a polymer material (polythiophene derivative (PEDOT)), which is a constituent material thereof, includes a predetermined medium (water and an organic solvent soluble in water). In this case, the liquid material is a liquid material having a relatively high viscosity.

In such a light emitting element forming step, the ink jet device 10 is used in the discharging step in the hole injection layer forming step and the discharging step in the light emitting layer forming step.
Therefore, also in the manufacture of the organic EL display device 301, in particular, for a material made of a highly viscous liquid material such as a liquid material for forming the hole injection layer 352, good landing accuracy from the first shot of the main discharge. The liquid droplets can be discharged and the liquid droplets can be arranged and applied to the concave opening 344 with high accuracy, and thus the reliability of the organic EL display device 301 obtained can be improved.

The display device of the present invention is not limited to the organic EL device, and can be applied to various display devices such as a liquid crystal display device.
In addition, such a display device can be used as a display unit in various electronic devices such as a portable information processing device such as a word processor or a personal computer, a mobile phone, and a wristwatch type electronic device.

It is a schematic block diagram of an inkjet apparatus. It is a schematic block diagram of a head. It is a block diagram for demonstrating a control system and a drive system. It is a circuit diagram of a head drive circuit. (A), (b) is a wave form diagram of a drive pulse. It is a sectional side view of an organic electroluminescence display.

Explanation of symbols

10 ... Inkjet device (droplet ejection device), 16 ... Head (droplet ejection head),
60 ... control circuit (control unit), 61 ... drive signal generator (drive means),
111 ... Nozzle, 113 ... Cavity, PZT ... Piezoelectric vibrator (pressure generating element)

Claims (11)

A cavity for accommodating a liquid material, a nozzle communicating with the cavity, and a pressure generating element for ejecting the liquid material in the cavity as droplets from the nozzle by vibrating the cavity to change its internal volume; In a droplet discharge device comprising a droplet discharge head comprising:
A contraction signal for continuously contracting the pressure generating element from a predetermined state, a maintenance signal for maintaining the contracted pressure generating element in the contracted state, and continuously releasing the contracted state of the pressure generating element, Drive means for sending a recovery signal for recovering the pressure generating element to a steady state as a drive signal for the pressure generating element;
The driving means does not cause the liquid droplets in the cavity to be discharged without discharging the liquid droplets from the nozzles before sending the discharge waveform consisting of the driving signal for discharging the liquid droplets from the nozzles to the pressure generating element. As a micro-vibration waveform for imparting micro-vibration, the contraction signal, the maintenance signal, and the recovery signal are included. The recovery signal is transmitted for 1 μs or more and 100 μs or less, and is approximately an integral multiple of the natural vibration period of the cavity. A droplet discharge apparatus, comprising: a control unit that sends a drive signal for time to the pressure generating element.   The drive signal that is the fine vibration waveform sent out from the control unit has a sending time of the contraction signal equal to or longer than the natural vibration period of the pressure generating element and shorter than the natural vibration period of the cavity. The droplet discharge device according to claim 1.   The drive signal having the micro-vibration waveform sent from the control unit has a time when the sum of the sending time of the contraction signal and the sending time of the maintenance signal is an integral multiple of the natural vibration period of the cavity, and 3. The liquid droplet ejection apparatus according to claim 1, wherein the liquid droplet ejection apparatus is substantially equal to a sum of a half of the natural vibration period.   The drive signal that is the fine vibration waveform sent from the control unit has a voltage value of the sustain signal that is 30% or more and 60% or less of the voltage value of the sustain signal in the drive signal that becomes the ejection waveform. The droplet discharge device according to any one of claims 1 to 3.   The droplet discharge device according to claim 1, wherein the liquid has a viscosity of 10 mPa · s or more. A cavity for accommodating a liquid material, a nozzle communicating with the cavity, and a pressure generating element for ejecting the liquid material in the cavity as droplets from the nozzle by vibrating the cavity to change its internal volume; A droplet discharge apparatus comprising a droplet discharge head comprising:
A contraction signal for continuously contracting the pressure generating element from a predetermined state, a maintenance signal for maintaining the contracted pressure generating element in the contracted state, and continuously releasing the contracted state of the pressure generating element, When sending a recovery signal for recovering the pressure generating element to a steady state as a drive signal for the pressure generating element,
Before sending a discharge waveform consisting of the drive signal for discharging a droplet from the nozzle to the pressure generating element, a fine vibration is applied to the liquid in the cavity without discharging the droplet from the nozzle. A drive signal that includes the contraction signal, the maintenance signal, and the recovery signal as a fine vibration waveform, and sets the transmission time of the recovery signal to 1 μs or more and 100 μs or less and is approximately an integral multiple of the natural vibration period of the cavity. A method for driving a droplet discharge device, wherein the droplet generating device is sent to the pressure generating element.   The drive signal that is the fine vibration waveform sent out from the control unit has a sending time of the contraction signal equal to or longer than the natural vibration period of the pressure generating element and shorter than the natural vibration period of the cavity. The method for driving a droplet discharge device according to claim 6.   The drive signal having the micro-vibration waveform sent from the control unit has a time when the sum of the sending time of the contraction signal and the sending time of the maintenance signal is an integral multiple of the natural vibration period of the cavity, and 8. The method of driving a droplet discharge device according to claim 6, wherein the driving method is substantially equal to a sum of a time that is half the natural vibration period.   The drive signal that is the fine vibration waveform sent from the control unit has a voltage value of the sustain signal that is 30% or more and 60% or less of the voltage value of the sustain signal in the drive signal that becomes the ejection waveform. The method for driving a droplet discharge device according to any one of claims 6 to 8.   The method for driving a droplet discharge device according to claim 6, wherein the liquid has a viscosity of 10 mPa · s or more.   The liquid material is discharged using the droplet discharge device according to any one of claims 1 to 5 or the driving method of the droplet discharge device according to any one of claims 6 to 10. A method for manufacturing a display device, comprising the step as one of manufacturing steps of the display device.

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