KR20190029447A - Inkjet head, inkjet apparatus using the same, and method for manufacturing device - Google Patents

Abstract

An objective of the present invention is to provide an inkjet head capable of mitigating abnormal injection caused by fluid crosstalk generated among a plurality of injection elements and also maintaining the desired volume of an injected droplet. According to the present invention, the inkjet head comprises: a nozzle to inject a droplet; a first pressure chamber connected to the nozzle; supply and injection side second pressure chambers connected to the first pressure chamber; a supply side third pressure chamber connected to the supply side second pressure chamber; an injection side third pressure chamber connected to the injection side second pressure chamber; an energy generation element to provide injection force to liquid stored in the first pressure chamber; a supply side first fastening unit disposed between the first pressure chamber and the supply side second pressure chamber; an injection side first fastening unit disposed between the first pressure chamber and the injection side second pressure chamber; a supply side second fastening unit disposed between the supply side second and third pressure chambers; and an injection side second fastening unit disposed between the injection side second and third pressure chambers.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an ink-jet head, an ink-jet apparatus using the same,

The present invention relates to an ink jet head, an ink jet apparatus using the same, and a manufacturing method of the device.

A drop-on-demand type ink-jet head is known as an ink-jet head capable of applying necessary amounts of ink according to an input signal when necessary. In particular, a drop-on-demand type ink jet head of a piezoelectric (piezoelectric element) type generally includes an ink supply passage, a plurality of pressure chambers connected to the ink supply passage and having nozzles, Device.

1 (a) and 1 (b) show a cross-sectional structure of a general ink-jet head.

The ink jet head includes a plurality of nozzles 100 for ejecting droplets, a pressure chamber 110 communicating with the nozzles, a partition wall 111 dividing the pressure chambers corresponding to the different nozzles, a diaphragm A piezoelectric element 130 for vibrating the diaphragm 112, a piezoelectric member 140 for supporting the partition 111 and a common electrode (not shown) for applying a voltage to the piezoelectric element 130 I have. Although not shown in the figure, it has a liquid inlet.

The piezoelectric element 130 and the piezoelectric member 140 for supporting the partition 111 are separated from one piezoelectric member by dicing. The nozzle 100 of the inkjet head has a diameter of 10 mu m to 50 mu m and 100 holes to 300 holes at intervals of 100 mu m to 500 mu m.

The inkjet head thus configured operates as follows. When a voltage is applied between the common electrode (not shown) on the other side of the piezoelectric element 130 and the piezoelectric element 130, the piezoelectric element 130 moves in the state of FIG. 1 (a) State. When the rightmost piezoelectric element 130 in Fig. 1 (b) is deformed (the lower portion of the piezoelectric element 130 is deformed), the volume of the pressure chamber 110 becomes small, and pressure can be applied to the liquid. The ink present in the pressure chamber 110 is discharged to the outside as the droplet 150 by the pressure.

In the inkjet head of the kind that circulates the ink, the inkjet head has a liquid injection port and a discharge port (not shown), and discharges the ink while circulating the ink. The effect of circulating the ink will be described below.

The ink in the vicinity of the nozzle is always in contact with the atmosphere. Since the contact area is very small, the evaporation of the solvent of the ink is also in a state in which it can not be ignored. As the solvent of the ink evaporates, the solid content of the ink rises, and as a result, the viscosity of the ink rises, making it difficult to discharge the normal ink. Here, by circulating the ink to the vicinity of the nozzle, the ink with the increased viscosity can always be changed, so that the ink discharged in the vicinity of the nozzle is always maintained at the normal ink viscosity. Thus, clogging of the nozzles can be suppressed and normal discharge can be normally performed.

As the structure of the ink jet head, a structure using a thin film piezoelectric element may be used. 2 (a) and 2 (b) are diagrams showing the structure of a thin film inkjet head. 2 (a), a nozzle 200 for discharging liquid, a pressure chamber 210 communicating with the nozzle, and a common pressure chamber 230 for supplying liquid to the pressure chamber are connected. A thin film piezoelectric element 220 is formed on an upper portion of a diaphragm 212 constituting a part of a pressure chamber. The inkjet head thus configured operates as follows. When a voltage is applied to the thin film piezoelectric element 220, the thin film piezoelectric element 220 is transformed from the state of FIG. 2 (a) to the state of FIG. 2 (b). When the thin film piezoelectric element 220 is deformed, the volume of the pressure chamber 210 becomes small and pressure can be transmitted to the liquid. And the droplets 150 are discharged by the pressure.

When an ink jet head having such a flow path structure drives one piezoelectric element to eject ink from the nozzles, the flow of ink at the time of ejection affects other nozzles communicating with the same flow path through the common flow path, A phenomenon such as an unstable crosstalk occurs.

Fig. 3 shows a cross-sectional view of the ink jet head described in Patent Document 1. Fig. As to the problem of crosstalk, Patent Document 1 discloses a liquid ejecting apparatus including a plurality of nozzles 500 for ejecting droplets, a plurality of pressure chambers 501 provided corresponding to the plurality of nozzles 500, (503) for supplying a liquid to a plurality of pressure chambers (501), and a common flow path (503) for supplying liquid to the respective pressure chambers (501) And a throttle portion 504 provided in a separate flow path portion connecting between the throttle portions 503 and 503.

The pressure wave generated in the pressure chamber 501 is attenuated when passing through the throttle portion 504 and is difficult to be transmitted to the pressure chambers 501 of other nozzles, so that crosstalk can be mitigated.

Japanese Patent Application Laid-Open No. H11-11653

However, in the inkjet head shown in Patent Document 1, the flow path resistance in the throttle portion 504 is larger than the flow path resistance of the nozzle 500, and the pressure generated by the vibration of the energy generating element 502 is increased by the nozzle 500 .

As a result, the volume of the droplet discharged from the nozzle 500 becomes too large, and the desired droplet volume can not be maintained.

In the case of an ink jet head capable of ejecting a very small liquid droplet having a liquid droplet volume of about 1 picoliter, the diameter of the nozzle 500 is about 10 μm, and it is difficult to maintain the processing accuracy and to machine the small holes.

Accordingly, an object of the present invention is to provide an inkjet head and an inkjet apparatus using the same and a method of manufacturing a device, capable of achieving both relaxation of ejection more than that caused by fluid crosstalk generated between a plurality of nozzles and maintenance of a desired discharge liquid volume will be.

In order to solve the above problems, the present invention provides a liquid ejecting apparatus comprising: a nozzle for ejecting droplets; a first pressure chamber connected to the nozzle; a supply side second pressure chamber and an outlet side second pressure chamber connected to the first pressure chamber; A third pressure chamber connected to the supply side third pressure chamber, the discharge side third pressure chamber connected to the discharge side second pressure chamber, an energy generation element for imparting a ground output to the liquid in the first pressure chamber, A first throttle on the supply side between the supply side first pressure chamber and the supply side second pressure chamber and a first throttle on the discharge side between the first pressure chamber and the discharge side second pressure chamber and a second throttle on the supply side between the supply side second pressure chamber and the supply side third pressure chamber, A plurality of discharge units including a throttle portion, a discharge side second throttle between the discharge side second pressure chamber and the discharge side third pressure chamber, and a plurality of discharge side third pressure chambers of the plurality of discharge units, year Supply side uses a common flow path and a discharge-side ink jet head provided with a common flow path connecting each of the exhaust side third pressure chamber between the plurality of discharging units.

A second pressure chamber communicating with the first pressure chamber; a second pressure chamber communicating with the first pressure chamber; a second pressure chamber communicating with the first pressure chamber; and a second pressure chamber communicating with the supply side third pressure chamber, An energy generating element for imparting a ground output to the liquid in the first pressure chamber, a first throttle between the first pressure chamber and the supply side second pressure chamber, and a second throttle between the first pressure chamber and the discharge side second pressure A plurality of discharge units including a first throttle between the supply side second pressure chambers and the supply side third pressure chambers and a second throttle between the supply side third pressure chambers and the supply side third pressure chambers of the plurality of discharge units, Side common flow path connecting the supply-side common flow path and the discharge-side common flow path connecting the discharge-side second pressure chambers of the plurality of discharge units.

The inkjet head further includes drive control means for generating a drive voltage signal to be applied to the energy generating element to control the ejecting operation of the inkjet head and conveying means for relatively moving the inkjet head and the drawing medium An inkjet apparatus is used.

According to the inkjet head and the inkjet apparatus of the present invention, it is possible to alleviate the fluid cross-talk in a portion that occurs mutually between a plurality of nozzles. In addition, it is possible to maintain a desired minute droplet volume, and it is possible to realize droplet ejection with high accuracy. As a result, the quality of the print quality can be improved.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a diagram showing the structure of a conventional bulk inkjet head, (b) a state of a head when a voltage is applied to the piezoelectric element in the bulk inkjet head of FIG.
2 is a diagram showing the state of a head when a voltage is applied to a piezoelectric element in (a) the structure of a conventional thin film inkjet head, and (b) the thin film type inkjet head of (a).
3 is a cross-sectional view of the inkjet head of Patent Document 1.
4A is a cross-sectional view schematically showing the configuration of the inkjet head according to the embodiment, Fig. 4B is a cross-sectional view of the inkjet head according to the first embodiment, and Fig.
Fig. 5 is a view showing the speed variation of the ink jet head of the first embodiment. Fig.
6 is a cross-sectional view of the ink-jet head of Comparative Example 1. Fig.
7 is a graph showing the speed variation of the ink jet head of Comparative Example 1. Fig.
8 is a sectional view of the ink jet head of the second embodiment.
Fig. 9 is a view showing a speed deviation of the ink jet head of the second embodiment. Fig.
10 is a sectional view of the ink jet head of Comparative Example 2. Fig.
11 is a view showing the speed deviation of the ink jet head of Comparative Example 2. Fig.
12 is a cross-sectional view of an ink jet head of Comparative Example 3;
13 is a graph showing the speed variation of the ink jet head of Comparative Example 3
14 is a sectional view of the ink-jet head of Embodiment 2
15 is a graph showing the relationship between the particle size and the sedimentation velocity in the second embodiment
16 is a side view of the inkjet apparatus of the embodiment

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment Mode 1)

≪ Configuration of inkjet head >

Fig. 4 (a) is a cross-sectional view schematically showing the configuration of an ink-jet head according to Embodiment 1. Fig. 4 (b) is a cross-sectional view taken along the XY plane in Fig. 4 (a). 4 (c) is a plan view of the entire inkjet head.

Here, the inkjet head 10 for ejecting ink droplets is described as an example, but in this embodiment, the liquid used for ejection is not limited to ink.

The inkjet head 10 has a nozzle 12 serving as an ink ejection opening and a first pressure chamber 14 communicating with the nozzle 12. [ The first pressure chamber 14 has an actuator 30, that is, an energy generating element.

As the ink supply side flow path to the first pressure chamber 14, there are the following components. There is a supply side second pressure chamber 15a communicating with the first pressure chamber 14 through a supply side first throttle 20a for allowing liquid to flow in and out. The supply side second pressure chamber 15a also has a supply side third pressure chamber 16a communicating with the supply side second throttle 22a.

As the discharge-side flow path of the ink from the first pressure chamber 14, there are the following components. There is a discharge-side second pressure chamber 15b communicating with the first pressure chamber 14 through a discharge-side first throttle 20b for allowing the liquid to flow in and out. Further, the discharge side second pressure chamber 15b has a discharge side third pressure chamber 16b communicating with the discharge side second throttle 22b.

It is preferable that the supply side flow path and the discharge side flow path are provided so as to be opposed to each other with the first pressure chamber (14) as the center. It is preferable that the first pressure chambers 14, the supply-side flow path, and the discharge-side flow path are arranged in a straight line and arranged parallel to the lower surface of the inkjet head 10.

The first pressure chamber 14 and the discharge-side flow path of ink and the supply-side flow path are one discharge unit 11. In the inkjet head 10, a plurality of discharge units 11 are arranged in parallel. There is a supply side common flow passage 51a for communicating the supply side third pressure chambers 16a of the plurality of discharge units 11. Further, there is a discharge side common flow passage 51b for communicating the discharge side third pressure chamber 16b of the plurality of discharge units 11.

The nozzle 12 is a through hole for discharging the ink and has a diameter of about 5 to 30 mu m. The processing method is laser processing, etching, or punching.

The first pressure chamber (14) has a function of appropriately collecting the pressure generated by the vibration of the actuator (30). The pressure to be collected changes depending on the volume of the first pressure chamber 14 or the flow path resistance of the first throttle 20a on the supply side and the throttle 20b on the discharge side. Therefore, it is necessary to optimize the volume and the like of the first pressure chamber 14 in accordance with the volume and velocity of the droplet to be discharged.

Side third pressure chamber 16b and the supply-side common flow passage 51a, the discharge-side second pressure chamber 15b, the supply-side third pressure chamber 16a, the discharge-side third pressure chamber 16b, 51b are lengths through which the ink passes.

These pressure chambers and flow paths are manufactured by thermal bonding of a metal plate processed by etching or the like, etching of a silicon material, or the like.

<Supply side damper 25a and discharge side damper 25b>

The following description may be made on at least one of the supply-side flow path and the discharge-side flow path. It is preferable to be on both sides.

At least one of the supply side second throttle 22a, the discharge side second throttle 22b, or the wall forming the supply side second pressure chamber 15a and the discharge side second pressure chamber 15b is elastic Is formed by a large plate.

It is a supply-side damper 25a and a discharge-side damper 25b which absorb vibration waves present in the supply-side second pressure chamber 15a and the discharge-side second pressure chamber 15b.

The supply side damper 25a and the discharge side damper 25b may be a thin metal plate or a resin film and are not limited to materials. Direction and perpendicular to the Z direction. The supply side damper 25a and the discharge side damper 25b disposed in the first pressure chamber 14 are held by the plate 26 (vibration preventing plate) having high rigidity. Therefore, there is no damping effect of the vibration wave, and the vibration wave necessary for ejecting the ink is not attenuated.

The supply side damper 25a and the discharge side damper 25b are not required to be provided in the first pressure chamber 14 but may be provided in the first pressure chamber 14 in order to form the supply side common flow path 51a, Respectively.

On the other hand, the supply side damper 25a disposed in the supply side second pressure chamber 15a, the discharge side second pressure chamber 15b and the supply side third pressure chamber 16a, the discharge side third pressure chamber 16b, The damper 25b is not held by the high rigidity plate 26 (anti-vibration plate), but only the end portion is maintained in the hollow state. The supply side damper 25a and the discharge side damper 25b are in the hollow state and the supply side second pressure chamber 15a, the discharge side second pressure chamber 15b, the supply side third pressure chamber 16a, The vibration wave existing in the third pressure chamber 16b is attenuated by the dumping effect and the fluid crosstalk caused by the interaction with the adjacent nozzle 12 is relaxed.

Position in the Z direction of the supply side first throttle 20a, the discharge side first throttle 20b, the supply side second throttle 22a, and the discharge side second throttle 22b>

The position of the actuator 30 in the Z direction is different due to the different positions of the supply side first throttle 20a, the discharge side first throttle 20b, the supply side second throttle 22a, and the discharge side second throttle 22b, The vibration wave generated by the vibration of the first throttle valve 20a reaches the supply side second pressure chamber 15a and the discharge side second pressure chamber 15b through the supply side first throttle 20a and the discharge side first throttle 20b, And then passes through the supply side second throttle 22a and the discharge side second throttle 22b.

As a result, in the traveling direction of the vibration wave, the components that are directly in contact with the surfaces of the supply side damper 25a and the discharge side damper 25b increase.

The fact that the positions in the Z direction are different means that the straight line connecting the supply side first throttle 20a and the supply side second throttle 22a, the first throttle 20b on the discharge side and the second throttle 22b on the discharge side (The surface of the damper 25 in Fig. 4 (a)) perpendicular to the discharge direction of the liquid droplets from the nozzles 12 It means not. Or each of them is not parallel to the flow direction of the ink.

Further, the discharge direction is parallel to the Z direction. This direction is also perpendicular to the lower surface on which the nozzles 12 are present in Fig. 4 (a). In this case, the supply-side first throttle 20a is separated from the supply-side second throttle 22a by a distance from the supply-side damper 25a.

And the relationship between the traveling direction of the vibration wave and the direction parallel to the plane of the supply side damper 25a and the discharge side damper 25b was analyzed as a fluid. As a result, it was found that the damping effect of the vibration wave was large when the traveling direction of the vibration wave was a direction directly opposite to the surfaces of the supply side damper 25a and the discharge side damper 25b.

Therefore, the dumping effect is increased in the structure of the embodiment. The supply side damper 25a and the discharge side damper 25b are disposed so as to maximize the damper effect with respect to the flow of the ink in the discharge direction.

<Flow resistance of the supply side second throttle 22a and the supply side first throttle 20a>

The flow path resistance of the supply side second throttle 22a is larger than the flow path resistance of the supply side first throttle 20a. And the supply side second throttle 22a prevents the other discharge unit 11 from being influenced.

Similarly, the flow path resistance of the discharge side second throttle 22b is larger than the flow path resistance of the discharge side first throttle 20b.

<Overall configuration>

4A shows only one ejection unit 11, that is, only the periphery of one nozzle 12. In the inkjet head 10, however, a plurality of ejection units 11 are provided. For example, in Fig. 4 (a), a plurality of discharge units 11 are arranged in the Y direction.

Although not shown in Fig. 4 (c), a plurality of discharge units 11 are connected in parallel to the supply-side common flow passage 51a and the discharge-side common flow passage 51b.

The supply side common flow path 51a and the discharge side common flow path 51b are connected to an ink resolver (not shown), and the ink resolver is also connected to an ink tank (not shown) as an ink supply source. Ink is supplied from the ink resolver to the supply side common flow path 51a through the ink supply port 53 and the ink flowing into the plurality of discharge side common flow paths 51b arranged in the Y direction is discharged from the ink discharge port 54 do.

The ink resolver is a second ink tank existing between the supply side common flow path 51a and the discharge side common flow path 51b and the ink tank. The second ink tank is pressurized or depressurized to control the pressure applied to the nozzle 12 so as to discharge the ink in an appropriate state.

The first throttle 20a on the supply side, the first throttle 20b on the discharge side, the second throttle 22a on the supply side and the second throttle 22b on the discharge side are connected to the first pressure chamber 14, Compared with the pressure chamber 15a, the discharge side second pressure chamber 15b, the supply side third pressure chamber 16a and the discharge side third pressure chamber 16b, the flow path cross sectional area is sufficiently small and functions as a throttle portion.

A pressure difference is set between the ink supply tank connected to the supply side third pressure chamber 16a and the ink recovery tank connected to the discharge side third pressure chamber 16b and the ink flows. By adopting such an ink circulation system, it is possible to always supply fresh ink to each of the first pressure chambers 14, thereby preventing the ink in the portions in contact with the atmosphere in the vicinity of the nozzles 12 from being thickened. Thus, stable discharge for a long time is possible.

&Lt; Actuator 30 &gt;

As the actuator 30 of this example, a piezoelectric element is used. A piezoelectric element has a structure in which a piezoelectric body is interposed between a lower electrode and an upper electrode, and a plurality of layers are laminated. The lower electrode serves as a common electrode (common electrode) for the plurality of actuators 30, and the upper electrode serves as a separate electrode for each of the actuators 30. [

By applying a drive voltage between the electrodes of the actuator 30, the actuator 30 is displaced and the volume of the first pressure chamber 14 changes. The ink is ejected from the nozzle 12 by this volume change.

Here, the piezoelectric actuator 30 of the d33 mode is exemplified. However, the energy generating element is not limited to this, and various types of modes such as a piezoelectric actuator, an electrostatic actuator, and a heating element using the d31 mode or the front- Is possible. Corresponding energy generating elements corresponding to the ejection method employed are used.

The channel structure shown in Fig. 4 (a) can be fabricated by forming grooves or holes or the like to etch silicon (Si) to form flow paths, or by thermal diffusion bonding of each etched metal plate.

&Lt; Evaluation of Examples and Comparative Examples &

In the following Examples and Comparative Examples, the influence on the discharge characteristics of fluid crosstalk mutually generated among a plurality of discharge elements was evaluated. The evaluation method is as follows. The application timing of the drive waveform to be applied to the actuator 30 is delayed by 1 microsecond only for one nozzle and the application timing of the drive waveform is delayed for each nozzle 12 provided in the inkjet head 10. [ And the discharge speed of the droplet discharged from the nozzle 12 was evaluated.

Strobe light emission was performed in synchronization with the application timing of the drive waveform, the droplet was irradiated, and the droplet was observed by observing it with a camera. In addition, the droplet between two points was observed by delaying the timing of the strobe light emission, and the ejection speed of the droplet was evaluated.

The ink used for the evaluation is an ink having a viscosity of 8 mPa · s and a surface tension of 33 mN / m. The viscosity was measured using clay-based AR-G2 (TA Insruments). The surface tension was measured using a surface tension meter DSA100 (manufactured by KRUSS).

Table 1 shows the conditions of the examples and comparative examples and the evaluation results. The acceptance criterion for the velocity fluctuation is 6.1 m / s or less in the case of the inkjet head 10 having 4 pL, and 6.1 m / s or less in the case of the inkjet head 10 having 1 pL. This is because it is necessary in the case of applying to the display panel described in the following discussion.

The speed fluctuation in Table 1 is the maximum value among the difference between the maximum value and the minimum value.

(Example 1)

The structure of the ink-jet head of the first embodiment is the same as the structure of the head shown in Fig. 4 (a). Fig. 5 shows the results of the above evaluation of the ink jet head of Example 1. Fig. 5, the abscissa indicates the delay time (microsecond) of the ejection timing of the liquid droplet, and the ordinate indicates the ejection speed of the liquid droplet, which is the evaluation result of three nozzles in one inkjet head 10. The delay time of the ejection timing means the delay time of the application start time of the drive waveform to be applied to each actuator 30.

CH75, CH150 and CH1 indicate the number of the nozzle 12. [ In the present embodiment, data was acquired using three representative nozzles (No. 75, No. 150, No. 1) among the nozzles 12 having 150 nozzles in one nozzle row. CH150 and CH1 are the nozzles 12 at both ends, and CH75 is the nozzle 12 located at the center.

The point at which the delay time is 0 microseconds indicates the discharge speed when all the nozzles 12 are simultaneously discharged. The degree of influence of the fluid crosstalk differs depending on the location of the nozzle 12 (depending on the difference between CH75, CH150, and CH1), and the behavior of the speed fluctuation differs. In general, It can be seen that the ejection speed of the liquid droplet largely fluctuates when it is 10 microseconds.

It can be considered that the timing at which the vibration waves between the plurality of nozzles 12 resonate corresponds to these times. In the region where the delay time is 15 microseconds or more, the speed fluctuation hardly occurs, and it can be considered that the vibration wave is sufficiently attenuated until this time.

(CH75) of the nozzle 12 is 2.1 m / s, and the fluctuation range of the discharge speed with respect to the delay time of the discharge timing is expressed by the value of (maximum value of velocity) - (minimum value of velocity) (CH150) of the nozzle 12 is 1.4 m / s, and the number 1 (CH1) of the nozzle 12 is 1.2 m / s.

(Comparative Example 1)

Fig. 6 shows a cross-sectional view of the ink jet head in Comparative Example 1. Fig.

Differences from the structure of the ink jet head 10 in the first embodiment will be described below. There is no supply side second throttle 22a and discharge side second throttle 22b and therefore there is no supply side third pressure chamber 16a and discharge side third pressure chamber 16b. Further, neither the supply side damper 25a nor the discharge side damper 25b are disposed. The other structure is the same as that of the ink jet head in the first embodiment.

Fig. 7 shows the result of evaluating the variation in the discharge speed when the discharge timing is delayed, as in the first embodiment.

Since there is no supply side second throttle 22a and discharge side second throttle 22b and no supply side damper 25a and discharge side damper 25b, the fluid crosstalk in the ink jet head of Comparative Example 1 Is larger than the value in the first embodiment.

(Example 2)

8 is a cross-sectional view of the ink-jet head according to the second embodiment. Compared with the structure of the first embodiment, it can be seen that the volume of the first pressure chamber 14 is small. The volume of the first pressure chamber 14 varies depending on the volume of the droplet to be discharged, but it is about 0.007 mm ³ when droplets of a volume of 1 picoliter are discharged. In addition, the volume when discharging a droplet of a volume of about 4 picoliters is about 0.025 mm ³ .

The relationship between the droplet volume and the resonance frequency attributed to the internal structure of the ink jet head 10 can be expressed as shown in Equation 1 by assuming that the ink flowing in the microchannel of the inkjet head 10 is a laminar flow, can do.

V: droplet volume, S: nozzle cross section, v: droplet discharge speed, f: resonance frequency

From this, it can be seen that it is necessary to reduce the volume of the first pressure chamber 14 and increase the resonance frequency of the vibration wave in the first pressure chamber 14 in order to discharge the liquid droplets in a small volume.

Since the inverse number of the resonance frequency is the resonance period, it is necessary to shorten the resonance period. Since the resonance period is shortened when the volume of the pressure chamber is small, it is theoretically valid to make the volume of the pressure chamber small to reduce the volume of the liquid droplet.

That is, the ink-jet head 10 of the second embodiment shown in Fig. 8 can discharge droplets of a small volume.

The lengths in the X direction of the supply side second throttle 22a and the discharge side second throttle 22b are respectively longer than the lengths of the supply side first throttle 20a and the discharge side first throttle 20b And the flow resistance is large. The length in the Y direction is the same.

The first throttle 20a on the supply side and the first throttle 20b on the discharge side are related to the liquid volume to be discharged and the length of the fastening of the supply side first throttle 20a and the discharge side first throttle 20b is If the resistance is increased by lengthening, the volume of the droplet coming out of the nozzle 12 becomes large. Therefore, resistance can not be easily raised. Therefore, in order to suppress the crosstalk, the lengths of the supply side first throttle 20a and the discharge side first throttle 20b are determined in terms of the liquid volume, and the length of the supply side second throttle 22a, Crosstalk is suppressed by the length of the female portion 22b. In other words, it is preferable that the supply side second throttle 22a and the discharge side second throttle 22b are longer.

The results of measuring the variation in the discharge speed when the discharge timing is delayed are shown in Fig. 9, similarly to the first embodiment. Expressing the fluctuation width of the discharge speed with respect to the delay time of the discharge timing as the value of the difference between the maximum value of the speed and the minimum value of the speed, the No. 75 CH75 of the nozzle 12 is 4.6 m / The CH150 of the nozzle 12 is 3.9 m / s and the CH1 of the nozzle 12 is 2.6 m / s.

The droplet volume is 0.9 picoliters when the discharge speed is 5 m / s.

(Comparative Example 2)

Fig. 10 shows a cross-sectional view of the ink-jet head in Comparative Example 2. Fig. Differences from the structure of the ink jet head in the second embodiment will be described below. There are no supply side second throttle 22a and discharge side second throttle 22b, and therefore there is no supply side third pressure chamber 16a and discharge side third pressure chamber 16b. No damper is arranged. The other structure is the same as that of the ink jet head in the second embodiment.

11 shows the result of evaluating the variation in the discharge speed when the discharge timing is delayed, as in the second embodiment. The fluctuation range of the discharge speed with respect to the delay time of the discharge timing is 7.4 m / s at 75 (CH75) of the nozzle 12, 5.0 m / s at 150 (CH150) of the nozzle 12, 1 (CH1) is 4.6 m / s.

The droplet volume is 1.0 picoliter when the discharge speed is 5 m / s.

In the inkjet head of Comparative Example 2, the droplet volume is as small as 1.0 picoliter, but the fluid crosstalk between a plurality of ejection elements is large and the speed fluctuation is large.

(Comparative Example 3)

Fig. 12 shows a cross-sectional view of the ink-jet head in Comparative Example 3. Fig. Differences from the structure of the ink jet head in the second embodiment will be described below. There are no supply side second throttle 22a and discharge side second throttle 22b, and therefore there is no supply side third pressure chamber 16a and discharge side third pressure chamber 16b. Also, the damper 25 is not disposed. The first throttle 20a on the supply side and the first throttle 20b on the discharge side are very long and have a very large flow path resistance. The other structure is the same as that of the ink jet head in the second embodiment.

Fig. 13 shows the result of evaluating the variation in the discharge speed when the discharge timing is delayed, as in the second embodiment. The fluctuation range of the ejection speed with respect to the delay time of the ejection timing is set such that the number 75 (CH75) of the nozzle 12 is 2.4 m / s, the number 150 of the nozzle 12 (CH150) 1 (CH1) is 2.0 m / s.

The droplet volume is 1.6 picoliters when the discharge speed is 5 m / s.

In the inkjet head of Comparative Example 3, although the fluid crosstalk between the plurality of ejection elements is small, the volume of the droplet is found to be 1.6 picoliters. Since the lengths of the supply side first throttle 20a and the discharge side first throttle 20b are long and the flow path resistance is large, attenuation in the individual flow path of the vibration wave is effectively generated. However, since the flow path resistance is very large, most of the vibration wave generated by the vibration of the actuator 30 is discharged from the nozzle 12. [ As a result, the velocity fluctuation due to the crosstalk is small, but the volume of the droplet is large.

The diameter of the nozzle of the ink jet head in Comparative Example 3 is 10 占 퐉 and it is difficult to process the small hole more than this while maintaining the processing accuracy. The droplet volume is determined according to the resolution of an image to be applied by the inkjet. If the droplet volume is too large, it is difficult to apply the ink while maintaining a predetermined accuracy.

<Review>

The object to be coated with the ink jet head of Example 2 is, for example, an ink forming a light emitting layer of Red, Green, and Blue of the organic EL display panel. Data such as a drive waveform for ejection, a drive voltage, and an image pattern to be applied are sent from the drive control mechanism to the inkjet head.

In response to the signal, the ink-jet head ejects ink into the pixels of the organic EL display panel, which is a coating object provided on the movable stage.

When the pixel resolution of the organic EL display is high, the volume of the droplet ejected from the ink-jet head is required to be 1 picoliter or less. When the droplet volume is large, the droplet diameter becomes large, and the margin of the landing position when the ink droplet is landed on the pixel becomes small. If the landing position is deviated, color mixing occurs between pixels of Red, Green, and Blue, and the display quality of the organic EL display panel is deteriorated. The specific specification of the speed deviation can not be uniformly determined, but when the application is performed with high accuracy, the speed deviation is required to be as small as possible.

Considering the results of Example 2, Comparative Example 2 and Comparative Example 3 at the above point, the ink volume of the ink jet head of Comparative Example 3 is larger than 1.6 picoliters and 1 picoliter, It is difficult to apply the ink of the light emitting layer to the pixel of the pixel.

In the inkjet head of Comparative Example 2, the droplet volume is 1 picoliter, which is within the specification range. However, since the speed deviation is larger than that of the inkjet head of Embodiment 2, the structure of the optimum inkjet head is not.

(Embodiment 2)

Fig. 14 is a cross-sectional view schematically showing the configuration of an ink-jet head according to Embodiment 2. Fig. The difference from the first embodiment will be mainly described. Items which are not described are the same as in the first embodiment.

(1) The positional relationship between the supply side first throttle 20a and the supply side second throttle 22a in the Z direction is such that the supply side first throttle 20a is away from the nozzle 12. [

By taking such a positional relationship, in the course of ink flow, the ink rises in a direction away from the nozzle 12 in the Z direction within the supply side second pressure chamber 15a. As a result, in the course of the ink flowing, the coarse particles in the ink settles and stays in the supply side second pressure chamber 15a. In other words, it is possible to suppress intrusion of coarse particles into the first pressure chamber 14 in order to realize normal discharge.

(2) In the tightening structure on the ink discharge side, only the discharge-side first throttle 20b is disposed. This is because the particles in the ink settled in the first pressure chamber 14 are discharged as much as possible.

(3) The discharge side first throttle 20b on the side from which the ink is discharged is disposed at a position nearer to the Z direction. As a result, the coarse particles precipitated in the first pressure chamber 14 can be easily discharged.

(4) The supply side damper 27a has higher rigidity than the discharge side damper 27b. Specifically, the width of the discharge side damper 27b in the X direction is larger than that of the supply side damper 27a. Here, the width of the damper is the width of the portion that is not held, and the width of the portion that can vibrate, that is, the width of the portion that alleviates the vibration. In this case, it is the width of the portion which is not held by the plate 26 having high rigidity. The stiffness may be changed by changing the material of the supply side damper 27a and the discharge side damper 27b.

(5) The supply side damper 27a or the discharge side damper 27b preferably has a higher resonance frequency than the diaphragm non-return portion 28. [ The supply side damper 27a or the discharge side damper 27b alleviates vibration of the ink from the diaphragm non-return portion 28. [ Details will be described with reference to Table 2.

The diaphragm non-return portion 28 is a fluctuating portion of the diaphragm.

The material of the diaphragm non-return portion 28 is a nickel alloy and has a density of 8900 kg / m ³ and a Young's modulus of 209 GPa. The dimensions in the inkjet head 10 are 4 占 퐉 in thickness in the Z direction and 50 占 퐉 in the X direction. From these values, the moment of inertia of the diaphragm non-return portion 28 is 2.67 x 10 &lt; ^-22 &gt; and the resonance frequency is 2.5 x 10 ^-4 Hz.

The supply side damper 27a or the discharge side damper 27b is made of stainless steel and has a density of 7930 kg / m ³ , a Young's modulus of 193 GPa, a thickness of 20 μm, and a width of 1000 μm. The secondary moment of inertia of the supply side damper 27a or the discharge side damper 27b becomes 6.67 10 ^-19 and the resonance frequency becomes 3.2 10 ^-4 Hz.

It can be seen from these that the resonance frequency of the supply-side damper 27a or the discharge-side damper 27b is larger than that of the diaphragm non-return valve 28.

&Lt; Including particles in ink &gt;

Here, a case where an ink in which particles are dispersed as ink is used will be described. The particles adjust the properties of the ink so that particles can be stably present in the dispersing agent or the pH adjustment of the solution. However, particles in the ink may aggregate and produce coarse particles compared to the design. When the particles other than the design flow into the nozzle 12, the nozzle is clogged and the droplet can not be discharged.

However, the particles in the ink settled over time. The sedimentation rate of the particles is determined according to the sedimentation rate equation of the stroke expressed by the following equation (2).

v _s : settling velocity D _p : particle diameter ρ _p : particle density ρ _f : liquid density

eta: ink viscosity g: gravitational acceleration

Figure 15 shows an sedimentation rate of the particle size of the dispersed particles in the ink when the ink viscosity 3mPa · s, particle density of 4g / cm ^3, a liquid density of 1g / cm ³ days. When particles having a particle diameter of 1.3 μm are dispersed, it can be seen that the particles precipitate in the liquid at a sedimentation rate of 0.055 mm / min.

Since the height of the supply side second pressure chamber 15a in the Z direction is approximately 0.2 mm, it can be seen that the particles settle down in approximately 4 minutes. In this way, the coarse particles other than the design can be settled in the supply side second pressure chamber 15a, and flow of the coarse particles to the nozzle 12 can be suppressed. In the discharge side second pressure chamber 15b, the discharge side first throttle 20b is arranged below the Z direction so that sedimented particles do not accumulate.

By using such a head structure, it is possible to stably eject the ink even when the particles are dispersed, without causing nozzle clogging.

(overall)

Embodiments 1 and 2 can combine some of them. Particularly, (1) to (5) of the second embodiment can be combined with the first embodiment. That is, at least one of (1) to (5) can be used for the inkjet head 10 of the first embodiment.

A side view of the inkjet apparatus 64 using the inkjet head 10 is shown in Fig. A drive control means 61 for generating a drive voltage signal to be applied to the actuator 30 to control the ejection operation of the inkjet head 10 and an inkjet head 10 And conveying means (62) for relatively moving the drawing medium (63).

Various devices can be manufactured by applying ink to the writing medium 63, which is a variety of devices.

The ink-jet head and the ink-jet apparatus of the present invention can be used for manufacturing an organic EL display panel having high-precision pixels. That is, it can be applied to the application of an emissive layer of an organic EL display panel, the application of an edible ink or resin encapsulation ink using UV curable ink or the like, the application of a conductive ink, and the application of an aqueous ink for cosmetic use.

10: ink jet head 11: ejection unit
12: nozzle 14: first pressure chamber
15a: supply side second pressure chamber 15b: discharge side second pressure chamber
16a: supply side third pressure chamber 16b: discharge side third pressure chamber
20a: supply side first throttle 20b: discharge side first throttle
22a: supply side second throttle 22b: discharge side second throttle
25a: supply side damper 25b: discharge side damper
26: High rigidity plate (anti-vibration plate)
27a: supply side damper 27b: discharge side damper
28: Diaphragm Remark 30: Actuator
51a: Supply side common flow path 51b:
53: ink supply port 54: ink outlet
61: drive control means 62:
63: Pigmenting medium 64: Ink-jet apparatus
100: nozzle 110: pressure chamber
111: partition wall 112: diaphragm
130: Piezoelectric element 140: Piezoelectric element
150: droplet 200: nozzle
210: pressure chamber 212: diaphragm
220: Thin film piezoelectric element 230: Common pressure chamber
500: nozzle 501: pressure chamber
502: Energy generating element 503:
504:

Claims (14)

A nozzle for discharging droplets,
A first pressure chamber connected to the nozzle,
A supply side second pressure chamber and an exhaust side second pressure chamber connected to the first pressure chamber,
A third supply side pressure chamber connected to the supply side second pressure chamber,
A discharge side third pressure chamber connected to the discharge side second pressure chamber,
An energy generating element for imparting a ground output to the liquid in the first pressure chamber,
A supply-side first throttle between the first pressure chamber and the supply-side second pressure chamber,
A discharge side first throttle between the first pressure chamber and the discharge side second pressure chamber,
A supply side second throttle between the supply side second pressure chamber and the supply side third pressure chamber,
A plurality of discharge units including a discharge side second throttle between the discharge side second pressure chamber and the discharge side third pressure chamber,
A supply side common flow passage connecting the supply side third pressure chambers of each of the plurality of discharge units,
And a discharge-side common flow passage connecting the discharge-side third pressure chambers of each of the plurality of discharge units. The method according to claim 1,
Wherein the first pressure chamber, the supply-side second pressure chamber, the discharge-side second pressure chamber, the supply-side third pressure chamber, and the discharge-side third pressure chamber are arranged in a straight line. The method according to claim 1,
Wherein the straight line connecting the supply side first throttle and the supply side second throttle is not parallel to the flow direction of the ink. The method according to claim 1,
And a supply side damper is disposed in the supply side second pressure chamber. The method of claim 4,
Wherein the supply side damper is disposed over the supply side third pressure chamber and the supply side second pressure chamber. The method of claim 4,
Wherein a part of the supply side damper is disposed in a hollow state. The method of claim 4,
Wherein the supply side first tightening portion has a distance from the supply side damper to the supply side second throttle. The method according to claim 1,
Wherein the flow path resistance of the supply side second throttle is larger than the flow path resistance of the supply side first throttle. A nozzle for discharging droplets,
A first pressure chamber connected to the nozzle,
A supply side second pressure chamber and an exhaust side second pressure chamber connected to the first pressure chamber,
A third supply side pressure chamber connected to the supply side second pressure chamber,
An energy generating element for imparting a ground output to the liquid in the first pressure chamber,
A supply-side first throttle between the first pressure chamber and the supply-side second pressure chamber,
A discharge side first throttle between the first pressure chamber and the discharge side second pressure chamber,
A plurality of discharge units including a second throttle between the supply side second pressure chamber and the supply side third pressure chamber,
A supply side common flow passage connecting the supply side third pressure chambers of each of the plurality of discharge units,
And a discharge-side common flow passage connecting the discharge-side second pressure chambers of each of the plurality of discharge units. The method of claim 9,
Wherein the first pressure chamber, the supply-side second pressure chamber, the discharge-side second pressure chamber and the supply-side third pressure chamber are arranged in a straight line. The method of claim 9,
Wherein the straight line connecting the supply side first throttle and the supply side second throttle is not parallel to the flow direction of the ink. The method of claim 9,
A supply side damper is disposed in the supply side second pressure chamber,
A discharge-side damper is disposed in the discharge-side second pressure chamber,
Wherein the supply side damper is higher in rigidity than the discharge side damper. An ink jet head comprising: the ink jet head according to any one of claims 1 to 12;
Driving control means for generating a driving voltage signal to be applied to the energy generating element and controlling the discharging operation of the ink jet head,
And transport means for relatively moving the inkjet head and the image-drawing medium. A manufacturing method for manufacturing a device by applying an ink using the inkjet head device according to claim 13.

Images