JP2003127361A - Pattern forming method and ink jet apparatus by ink jet system - Google Patents

Abstract

(57) [Summary] To reduce the number of droplets ejected from a head and increase the ejection speed of the droplets. An ink jet apparatus includes a piezo drive type head, a drive pulse generation circuit for generating a drive pulse A, and a control circuit. There is a bending point Y in the middle of the fall of the drive pulse A. The falling waveform includes a first slope AF1 from a falling start point X to a bending point Y,
The second slope A from the bending point Y to the falling end point Z
F2, the slope of the first slope AF1 is steeper than the slope of the second slope AF2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pattern forming method and an inkjet apparatus by an inkjet method capable of forming a highly precise pattern.

[0002]

2. Description of the Related Art A color liquid crystal display device has a color filter corresponding to a color to be displayed for each pixel. As a method for manufacturing a color filter, a pigment dispersion method in which a photolithography process is repeated a plurality of times has been conventionally used, but in recent years, mainly for cost reduction,
A method using an inkjet device has been attracting attention.

The pattern pitch of the color filter tends to become finer as the color liquid crystal display device becomes finer. When a high-definition pattern is to be formed by an inkjet method, it is necessary to control the amount of ink ejected from the head of an inkjet device with high accuracy so that the amount of ink is small and uniform. This is because it is preferable that the amount of ink in each droplet is small in order to form a line having an extremely narrow line width such as a colored layer that constitutes a color filter.

[0004]

By the way, there is a case where an inkjet head using a piezo element is used as the head. In the piezo drive type head, the smaller the pushing force for pushing the ink out of the ejection surface of the nozzle, the smaller the droplet can be made, but the ejection speed of the droplet is lowered. Generally, when the discharge speed of the liquid droplets decreases, the discharge operation becomes unstable, and there is a problem that a slight nonuniformity of ink leakage at the nozzles bends the liquid droplet discharging direction. That is, there is a trade-off relationship between miniaturization of droplets and stable ejection operation of droplets.

The present invention has been made in view of the above circumstances, and an object thereof is to reduce the amount of liquid droplets ejected from a head and at the same time stabilize the ejection operation, and further control the liquid droplet amount. An object of the present invention is to provide a pattern forming method and an inkjet device using the inkjet method.

[0006]

In order to achieve the above object, the present invention provides an ink jet system for applying a driving pulse to a piezo drive type head to eject a liquid droplet, as described in claim 1. In the pattern forming method by
The drive pulse is generated as a positive pulse with the drive voltage intensity in the normal state of the piezo drive type head as the reference voltage intensity, a bending point is provided in the middle of the fall of the drive pulse, and the falling waveform is A first slope from a falling start point to the bending point and a second slope from the bending point to the falling end point, wherein the slope of the first slope is steeper than the slope of the second slope And a method for forming a pattern by an inkjet method.

When the drive pulse is generated as a positive polarity pulse with reference to the drive voltage intensity in the normal state of the piezo drive type head, ink is sucked into the nozzle in synchronization with the rise of the drive pulse and Ink is ejected from the nozzles in synchronization with the fall. According to the present invention, the falling waveform includes the first slope and the second slope, and the slope of the first slope is steeper than the slope of the second slope. The force that pushes the ink out of the ejection surface becomes larger as the slope of the falling waveform becomes steeper. Therefore, in the period from the start of ejection to the end of the first slope, a large pushing force is applied to the ink while the second force is applied. In the period from the start of the slope to the end of the ejection, a small pressing force is applied to the ink. This makes it possible to reduce the pushing force so as not to inadvertently grow the nuclei after giving a large amount of pushing force to the nucleus that is the source of the droplets in a short time so that the nuclei can be separated.
As a result, it becomes possible to miniaturize the liquid droplets and, at the same time, to speed up the liquid droplet ejection speed and stabilize the ejection.

According to a second aspect of the present invention, in a pattern forming method by an ink jet system in which a drive pulse is applied to a piezo drive type head to eject droplets, the drive pulse is applied to the piezo drive type head. The drive voltage intensity in the normal state of the head is generated as a negative voltage pulse with reference voltage intensity, a bending point is provided in the middle of the rising of the driving pulse, and the rising waveform has a first waveform from the rising start point to the bending point. Provided is a pattern forming method by an inkjet method, which includes a slope and a second slope from the bending point to the rising end point, wherein the slope of the first slope is steeper than the slope of the second slope. .

When a positive polarity pulse is generated with the drive voltage intensity in the normal state of the piezo drive type head as a reference, ink is sucked into the nozzle in synchronization with the fall of the drive pulse, and at the rise of the drive pulse. Ink is ejected from the nozzles in synchronization. According to the invention,
The rising waveform includes the first slope and the second slope, and the slope of the first slope is steeper than the slope of the second slope. The force that pushes the ink out of the ejection surface increases as the slope of the rising waveform becomes steeper. Therefore, during the period from the start of ejection to the end of the first slope, a large pushing force is applied to the ink while the second slope is applied. In the period from the start to the end of ejection, a small pressing force is applied to the ink. This makes it possible to reduce the pushing force so as not to inadvertently grow the nuclei after giving a large amount of pushing force to the nucleus that is the source of the droplets in a short time so that the nuclei can be separated. As a result, it becomes possible to miniaturize the liquid droplets and, at the same time, to speed up the liquid droplet ejection speed and stabilize the ejection.

Further, in the invention described in claim 1 or 2, as described in claim 3, the inflection point is 4/5 or less of the maximum voltage intensity of the drive pulse and the maximum voltage intensity of the drive pulse. It is preferably 1/60 or more. By defining the bending point within this range, it is possible to further balance the miniaturization of the droplet and the stability of the droplet ejection operation.

Further, in the invention described in claim 1 or 2, when the natural vibration frequency of the piezoelectric drive type head is set to λ as described in claim 4, the drive pulse rises and falls. Up to λ
The time is preferably / 2 or less. If the drive pulse applied to the piezo drive type head contains a frequency component in the vicinity of the natural vibration frequency, normal operation cannot be performed and abnormal ejection may be caused. However, according to the present invention, from the rising of the drive pulse. The period until the fall is λ /
Since the time is 2 or less, it becomes possible to stably operate the piezo drive type head.

Next, in the invention described in claim 5,
A piezo drive type head that sucks ink at the rising edge of the driving pulse and discharges ink at the falling edge of the driving pulse, and a bending point is provided in the middle of the falling edge. First to the point
An inkjet including a slope and a second slope from the bending point to the trailing end point, the drive pulse generating unit generating a drive pulse in which the slope of the first slope is steeper than the slope of the second slope. Provide a device. Further, in the invention according to claim 6, a piezo drive type head that sucks ink at the trailing edge of the driving pulse and ejects ink at the leading edge of the driving pulse, and a bending point is provided in the middle of the leading edge. The rising waveform has a first slope from the rising start point to the bending point and a second slope from the bending point to the rising end point.
And a slope, wherein the slope of the first slope is the second slope.
Provided is an inkjet device including a drive pulse generating unit that generates a drive pulse that is steeper than the slope of a slope.

According to the fifth or sixth aspect of the invention, the slope of the waveform can be made different before and after the bending point, and the slope of the trailing slope can be made gentle as compared with the preceding slope. Therefore, after giving a large amount of momentum to the nucleus that is the source of the droplets to give a separable momentum in a short time, the momentum can be reduced so that the nucleus does not grow carelessly. As a result, it becomes possible to miniaturize the liquid droplets and, at the same time, to speed up the liquid droplet ejection speed and stabilize the ejection.

Further, in the invention of claim 5 or 6, the bending point is 4/5 or less of the maximum voltage intensity of the drive pulse and the maximum voltage intensity of the maximum voltage intensity of the drive pulse as described in claim 7. It is preferably 1/60 or more. By defining the bending point within this range, it is possible to further balance the miniaturization of the droplet and the stability of the droplet ejection operation. Further, in the invention described in claim 5 or 6, when the natural vibration frequency of the piezo drive type head is λ as described in claim 8,
The period from the rise to the fall of the drive pulse is preferably λ / 2 or less. If the drive pulse applied to the piezo drive type head contains a frequency component in the vicinity of the natural vibration frequency, normal operation cannot be performed and abnormal ejection may be caused. However, according to the present invention, from the rising of the drive pulse. Since the period until the fall is λ / 2 or less, it becomes possible to stably operate the piezo drive type head.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of an inkjet device according to the present invention will be described below with reference to the drawings.

A. Configuration of Inkjet Device First, the configuration of the inkjet device will be described. This ink jet device adopts an ink jet method to which a single pulse method is applied in which a pulse is applied once to eject one droplet.

FIG. 1 is a block diagram showing the structure of the ink jet device, and FIG. 2 is a timing chart showing the operation of the ink jet device. As shown in FIG. 1, the inkjet apparatus includes a control circuit 100, a drive pulse generation circuit 200, and a piezo drive type head 300.

The control circuit 100 uses the first control signal CTL.
The first, second control signal CTL2, and third control signal CTL3 are generated and supplied to the drive pulse generation circuit 200. The drive pulse generation circuit 200 generates the drive pulse A shown in FIG. The drive pulse A has a substantially trapezoidal waveform, and has a rising edge AR and a falling edge AF. Further, the falling edge AF has a bending point Y. In the following description, a portion from the falling start point X to the bending point X will be referred to as a first slope AF1 and a portion from the bending point Y to the falling end point Z will be referred to as a second slope AF2.

Details of the first to third control signals CTL1 to CTL3 generated in the control circuit 100 will be described as needed, but the outline thereof is as follows. First,
The first control signal CTL1 specifies the rising period of the drive pulse A. Next, the second control signal CTL2 specifies the falling period of the drive pulse A. Next, the third control signal C
TL3 designates the time of occurrence of the inflection point Y at the time when the level changes from the high level to the low level.

The drive pulse generating circuit 200 includes a first constant current source 210, a second constant current source 220, a capacitor 230, and an operational amplifier 240, as shown in FIG. First
The constant current source 210 flows the current i1 into the capacitor 230, while the second constant current source 220 draws the current i2 from the capacitor 230. One end of the capacitor 230 is grounded, and the other end is at the connection point W at the operational amplifier 2
It is connected to 40 positive input terminals. Operational amplifier 240
Constitutes a voltage follower, and the input impedance is high impedance, while the output impedance is low impedance. Therefore, the electric charge accumulated in the capacitor 230 does not flow into the operational amplifier 240, and the potential of the connection point W is the same as that of the first constant current source 21.
It is determined only by the current i1 flowing from 0 and the current i2 flowing into the second constant current source 220. The potential of the connection point W is
The potential of the drive pulse A is taken out by the operational amplifier 240.

The first constant current source 210 has PNP transistors 211 to 213 and resistors 214 to 216. P
NP transistors 211, 212 and resistors 214-2
Reference numeral 16 constitutes a current mirror circuit. Where resistor 2
The value of 15 and the value of the resistor 214 are set to be equal.
In this case, the value of the current flowing through the PNP transistor 212 and the value of the current flowing through the PNP transistor 211 become equal. If the resistance value of the resistor 215 is R1 and the resistance value of the resistor 216 is R2, the current i1 flowing out from the first constant current source 210 is i1 = (Vcc-Vss-0.7) / (R1 +
Given in R2).

The PNP transistor 213 has a first
On / off is controlled based on the control signal CTL1.
When the first control signal CTL1 is at low level, the PNP transistor 213 is turned on, while the first control signal C
When TL1 is high level, PNP transistor 213
Turns off. When the PNP transistor 213 is turned on, the base voltage of the PNP transistors 211 and 212 is 0.3 V lower than the power supply voltage Vcc, so the PNP transistors 211 and 212 are turned off and the current mirror circuit operates in constant current. Stop. On the other hand, when the PNP transistor 213 is off, the PNP transistors 211 and 212 are on, and the current mirror circuit outputs a constant current.
Therefore, the first constant current source 210 operates the first control signal CT.
While the constant current i1 is output when L1 is at the high level,
The operation is stopped when the first control signal CTL1 is at the low level.

Here, the capacitance value of the capacitor 230 is C,
Letting t be an elapsed time after the first control signal CTL1 becomes high level, the capacitor 2 with the ground potential as a reference is used.
The voltage V at the connection point W of 30 is V = i1 · t / C.
That is, the voltage V increases with the passage of time, and its slope is given by dV / dt = i1 / C. Current value i
Since 1 is fixed, the inclination is constant.

Therefore, as shown in FIG. 2, when the first control signal CTL1 transitions from the low level to the high level at time t1, the charging of the capacitor 230 is started and the voltage of the drive pulse A increases at a constant slope. To do. Then, at time t2, when the first control signal CTL1 transitions from the high level to the low level, the charging of the capacitor 230 ends. As a result, the rising edge AR is generated.

Next, as shown in FIG. 1, the second constant current source 220 includes NPN transistors 221-223 and a resistor 22.
4 to 227, and a switch 228.

NPN transistors 221 and 222 and resistors 224 to 226 form a current mirror circuit.
Here, the value of the resistor 225 is set to be equal to the value of the resistor 224. In this case, the NPN transistor 222
And the value of the current flowing through the NPN transistor 221 become equal. The switch 228 selects one of the resistors 226 and 227 as the collector resistor of the NPN transistor 222. Therefore, the current i2 absorbed by the second constant current source 220 from the capacitor 230 is changed according to the selection of the resistor 226 and the resistor 227. Here, the resistance value of the resistor 225 is set to R
3, the resistance value of the resistor 226 is Ra, the resistance value of the resistor 227 is Rb, the value of the current i2 when the resistor 226 is selected is i2a, and the value of the current i2 when the resistor 227 is selected is i.
2b, i2a and i2b are given by the following equations.

I2a = (Vcc-Vss-0.7) /
(Ra + R3) i2b = (Vcc-Vss-0.7) / (Rb + R3) Further, the resistors 226 and 227 are set so that Ra <Rb. Therefore, i2a> i2b. In addition, the switch 228 is configured to select the resistor 226 when the third control signal CTL1 is at the high level, and to select the resistor 227 when the third control signal CTL1 is at the low level. Has been done. The NPN transistor 223 is on / off controlled based on the second control signal CTL2. When the second control signal CTL2 is low level, the NPN transistor 223 is turned off, while when the second control signal CTL2 is high level, NP
The N transistor 223 is turned on. When the NPN transistor 223 is turned on, the base voltage of the NPN transistors 221 and 222 becomes 0.3 V higher than the power supply voltage Vss, so the NPN transistors 221 and 222 are turned off and the current mirror circuit operates in constant current. Stop. On the other hand, if the NPN transistor 223 is off, the NPN transistor 22
1 and 222 are turned on, and the current mirror circuit outputs a constant current.

Therefore, the second constant current source 220 is
When the control signal CTL2 is low level, the constant current i2 is absorbed, while when the second control signal CTL2 is high level, the operation is stopped.

As shown in FIG. 2, at time t3, the second
When the control signal CTL2 transitions from the high level to the low level, the second constant current source 220 starts operating. Time t3
Then, since the third control signal CTL3 is at the high level, the switch 228 selects the resistor 226 as described above. Therefore, the value of the current i2 absorbed by the second constant current source 220 from the capacitor 230 is i2a.

At time t4, the third control signal CTL3
Switch from high level to low level, and switch 228
Selects resistor 227. Then, the value of the current i2 is i2
Change from a to i2b. As described above, i2a> i2
b, and the potential change dV / dt of the connection point W per unit time is given by i2 / C. Therefore, i2
The second slope AF2 determined according to b has a gentler slope than the first slope AF2 determined according to i2a.

When the second control signal CTL2 transitions from the low level to the high level at time t5, the second constant current source 220 stops its operation. In this way, the drive pulse generation circuit 200 generates one drive pulse A.

FIG. 3 is a sectional view showing the mechanical structure of the piezo drive type head 300. As shown in this figure, the piezo drive type head 300 has a piezo element (piezoelectric element) 310 bonded to the upper part of an ink chamber 320.
Ink K is supplied to the ink chamber 320 from an ink supply unit (not shown).
Are being supplied. In addition, the piezo element 31
The wall of the ink chamber 320 corresponding to 0 has a smaller thickness than other portions, and acts like a leaf spring. The piezo element 310 is not deformed in the normal state as shown in the figure, but is deformed in the direction of the arrow in the figure when the voltage intensity of the drive pulse A is increased. Then, the piezo element 310 is bent by the drive pulse A, and the ink chamber 32
The ink K of 0 is ejected from the ejection surface 340 of the nozzle 330.

In the above-mentioned ink jet device, a single piezo drive type head 300 is used for simplification of the description, but in an actual ink jet device, a plurality of piezo drive type heads 300 are used. Is often used. In such a case, the drive pulse generation circuit 200 may be provided for each piezo drive type head 300. Further, the amount of one droplet of each piezo drive type head 300 often varies. In such a case, it is preferable to adjust the droplet amount by changing the waveform of the drive pulse A using various control signals from the control circuit 100 to make the droplet amount uniform. .

B. Droplet Discharging Operation Next, a droplet discharging operation using the inkjet device will be described in detail with reference to FIGS. 2 and 4. Figure 4
FIG. 6 is a schematic diagram showing a state of the piezo drive type head 300.

First, before the time t1 when the voltage intensity of the drive pulse A is 0 V, the upper surface and the lower surface of the piezo element 310 are parallel to each other as shown in FIG. 4 (A). At this time, the ink K in the ink chamber 320 is filled up to the ejection surface 340.

Next, when the drive pulse A rises in the period from time t1 to time t2, the piezo element 310 swells upward in synchronization with this. As a result, when the internal pressure of the ink chamber 320 drops, the piezo drive type head 30
In the state of 0, the ink K is sucked into the nozzle 330 as shown in FIG.

Next, when the drive pulse A falls during the period from time t3 to time t5, the piezo element 310 returns to its original state in synchronization with this. At this time, the internal pressure of the ink chamber 320 rises, the state of the piezo drive type head 300 becomes as shown in FIG. 4C, and the ink K is ejected from the ejection surface 340.

Here, the process until the ink K extruded from the ejection surface 340 forms the droplet G will be described with reference to FIG. First, as shown in FIG. 5A, the ink K swells in a convex shape from the ejection surface 340 (first step). Next, as shown in FIG. 5B, a portion is formed in which this bulge extends in the ejection direction and becomes the nucleus g of the final droplet G (second step). Next, as shown in FIG. 5C, a constriction is formed between the ink K extruded from the ejection surface 340 and the nucleus g (third step). Finally, Fig. 5 (D)
The droplet G is separated from the ink K as shown in (4th step).

In the process of generating the droplet G, the discharge speed of the droplet G is determined only up to the intermediate process between the second step and the third step. That is, the droplet G
It is not necessary to apply a large pushing force in the ejection direction after the separable momentum has been given to the nucleus g which is the source of.
On the contrary, if a large pushing force is applied forever, the nucleus g is grown, and the ink amount of the droplet G increases.

In the present embodiment, as shown in FIG. 2, a bending point Y is provided at the trailing edge AF of the drive pulse A, and the trailing edge AF is divided into the first slope AF1 and the second slope AF1.
The slope AF2 and the slope AF2 are provided to increase the ejection speed of the droplet G and reduce the ink amount of the droplet G.

The slope of the first slope AF1 is steeper than the slope of the second slope AF2. The slope of each slope determines the speed at which the piezo element 310 deforms. Ink chamber 32
Since the internal pressure of 0 changes according to the movement speed of the piezo element 310, the pushing force that pushes the ink K from the ejection surface 340 is determined according to the slopes of the slopes AF1 and AF2.
The steeper the slope, the greater the magnitude of the force. Therefore,
During the period of the first slope AF1, the push output is relatively large. This period corresponds to the intermediate process between the second step and the third step described with reference to FIG. On the other hand, during the period of the second slope AF2, the pushing force is relatively small. This period corresponds to the intermediate process and after.

Therefore, the droplet G
After imparting a separable momentum to the nucleus g, which is the source of, in a short time, the pushing force can be reduced so that the nucleus g does not grow carelessly, and the ejection speed of the droplet G At the same time, it is possible to reduce the size of the droplet G at the same time.

In the falling edge AF of the drive pulse A described above, the bending point Y becomes a change point of the pushing output,
Optimization of the bending point Y is an important factor in the ejection operation. Therefore, the present inventors conducted various experiments on the voltage intensity at the bending point Y. In the following description, the voltage intensity at the bending point Y is Vy, and the maximum voltage intensity of the drive pulse A is Vm.

First, regarding the upper limit value of the voltage intensity Vy,
It is desirable that Vy ≦ (4/5) · Vm. This is because when the voltage intensity Vy exceeds 4/5 times the maximum voltage intensity Vm, the effect of micronizing the droplet G is small regardless of the position of the end point Z. Furthermore, Vy ≦ (3/4) · V
More preferably m. This is because when the voltage intensity Vy is set to 3/4 or less of the maximum voltage intensity Vm, the size of the droplet G becomes uniform and the variation is reduced.

Next, regarding the lower limit value of the voltage intensity Vy,
It is desirable that Vy ≧ (1/60) · Vm. When the voltage intensity Vy is less than 1/60 of the maximum voltage intensity Vm,
This is because the size of the droplet G cannot be controlled. Furthermore, it is more preferable that Vy ≧ (1/12) · Vm.
This is because if the voltage intensity Vy is 1/12 or more of the maximum voltage intensity Vm, the effect of miniaturizing the size of the droplet G is great.

The piezo drive type head 300 has a so-called natural frequency. When the piezo drive type head 300 is driven in the vicinity of the natural frequency, the head itself resonates, so that the ink K cannot be ejected normally. Here, when the natural vibration period is λ, the time T from time t1 to time t5 is preferably set to T <λ / 2. The reason for setting the end point Z of the second slope AF2 so that the entire period of the drive pulse A is shorter than λ / 2 is to avoid ejection abnormality due to resonance of the head.

As described above, according to the ink jet device of this embodiment, the bending point Y is provided at the trailing edge AF of the drive pulse A, and the first slope AF1 having a relatively steep slope and the relatively gentle slope are provided. Na second slope AF2
Since it is configured by, it is possible to change the pushing force of the ink K and to make the droplet G minute without reducing the ejection speed of the droplet G. As a result, it becomes possible to stably eject the minute liquid droplets G, and a color filter that requires the formation of a high-definition pattern can be easily manufactured by using an inkjet device, and the cost can be reduced. It is possible to dramatically improve the quality of the color filter while aiming.

In addition, according to the ink jet device of this embodiment, the small droplet G can be stably ejected, so that the ink amount of the droplet G can be accurately controlled. As a result, a plurality of piezoelectric drive type heads 3
00, it is possible to make the ink amount of the droplet G between the heads uniform when forming a pattern, and it is possible to eliminate the unevenness of the pattern.

C. Modifications The present invention is not limited to the above-mentioned embodiment,
The above-described embodiment is an exemplification, and for example, the modifications described below are possible. In addition, anything having substantially the same configuration as the technical idea described in the claims of the present invention and exhibiting the same operational effect is included in the technical scope of the present invention. To be done.

(1) The ink jet apparatus of the above-described embodiment has been described as a part of a color filter manufacturing apparatus, but the present invention is not limited to this, and ink is ejected onto a recording medium such as paper. It is needless to say that the present invention can be applied to a printer device that performs printing by printing.

(2) In the above-described embodiment, the drive pulse A is a positive pulse with reference to the drive voltage intensity of the piezo drive type head 300 in the normal state. This is because the piezo drive type head 300 drives the drive pulse A.
This is because the ink is sucked at the rising edge of and the ink is ejected at the falling edge of the drive pulse A. On the other hand, the present invention is not limited to such a piezo drive type head 300, and is a type that sucks ink at the falling edge of the drive pulse A and ejects ink at the rising edge of the drive pulse A. May be applied to FIG. 6 is a cross-sectional view of a piezo drive type head 300 ′ according to a modification, and FIG. 6 (A) shows the behavior of the piezo drive type head 300 ′ in a normal state, while FIG. 6 (B). Shows the behavior of the piezo drive type head 300 ′ when the ink K is sucked.

In this modification, since the piezo element 310 is deformed in the normal state, the drive pulse A is deformed at the time of deformation.
The voltage intensity of is large. Therefore, the drive pulse A is
As shown in FIG. 7, a bending point Y is provided at the rising edge AR of the drive pulse A, and the rising edge A
R may be configured by the first slope AR1 and the second slope AR2.

[0053]

As described above, according to the present invention, the amount of droplets ejected from the head can be reduced and the ejection speed of the droplets can be increased to stably eject ink. . Therefore, a high-definition pattern can be formed with high quality and stability, and the amount of droplets can be controlled with high precision.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an inkjet device according to an embodiment of the present invention.

FIG. 2 is a timing chart showing the operation of the device.

FIG. 3 is a cross-sectional view showing a mechanical configuration of a piezo drive type head.

FIG. 4 is a schematic view showing a state of a piezo drive type head used in the apparatus.

FIG. 5 is a schematic diagram showing a process of separating droplets and ink.

FIG. 6 is a sectional view of a piezo drive type head according to a modification.

FIG. 7 is a waveform diagram of drive pulses according to a modification.

[Explanation of symbols]

K ... Ink G ... Droplet A ... Drive pulse AF1 ... 1st slope AF2 ... 2nd slope 100 ... Control circuit 200 ... Drive pulse generation circuit 300 ... Piezo drive type head

Claims (8)

[Claims] 1. A pattern forming method using an ink jet method, wherein a drive pulse is applied to a piezo drive type head to eject droplets, wherein the drive pulse is based on a drive voltage intensity in a normal state of the piezo drive type head. Generated as a positive polarity pulse as the voltage intensity, a bending point is provided in the middle of the fall of the drive pulse, and the falling waveform has a first slope from the falling start point to the bending point and from the bending point. A second slope up to the end point of fall, wherein the slope of the first slope is steeper than the slope of the second slope. 2. A pattern forming method using an ink jet method, wherein a drive pulse is applied to a piezo drive type head to eject droplets, wherein the drive pulse is based on a drive voltage intensity in a normal state of the piezo drive type head. Generated as a negative polarity pulse as the voltage intensity, a bending point is provided in the middle of the rising of the drive pulse, and the rising waveform has a first slope from the rising start point to the bending point and a rising end point from the bending point. And a second slope, wherein the slope of the first slope is steeper than the slope of the second slope. 3. The inkjet according to claim 1, wherein the bending point is 4/5 or less of the maximum voltage intensity of the drive pulse and 1/60 or more of the maximum voltage intensity of the drive pulse. Pattern formation method by method. 4. The period from the rise to the fall of the drive pulse is a time of λ / 2 or less, where λ is the natural vibration frequency of the piezoelectric drive type head. The pattern forming method by the inkjet method according to claim 2. 5. A piezo drive type head that sucks ink at the rise of a drive pulse and discharges ink at the fall of the drive pulse, and a bending point is provided in the middle of the fall, and the fall waveform is
A first slope from the falling start point to the bending point and a second slope from the bending point to the falling end point are included, and the slope of the first slope is steeper than the slope of the second slope. An inkjet device, comprising: a drive pulse generating unit that generates a drive pulse. 6. A piezo drive type head that sucks ink at the trailing edge of a drive pulse and ejects ink at the leading edge of the drive pulse, and a bending point is provided on the way of the leading edge, and the leading edge waveform is
A drive pulse including a first slope from the rising start point to the bending point and a second slope from the bending point to the rising end point, and the slope of the first slope is steeper than the slope of the second slope. And a drive pulse generating means for generating 7. The inkjet according to claim 5, wherein the bending point is 4/5 or less of the maximum voltage intensity of the drive pulse and 1/60 or more of the maximum voltage intensity of the drive pulse. apparatus. 8. The period from the rise to the fall of the drive pulse is λ / 2 or less, where λ is the natural vibration frequency of the piezoelectric drive type head. The inkjet device according to claim 6.