JP2008260237A - Liquid droplet ejection head and liquid droplet ejector and their ejection control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a liquid droplet ejection head having a structure for performing ejection control in various mode. <P>SOLUTION: The liquid droplet ejection head comprises a nozzle 31 for ejecting a liquid in the form of a droplet, an ejection chamber 21 equipped, in series, with oscillating boards (upstream side oscillating board 22A, downstream side oscillating board 22B) for pressurizing the liquid by displacement and provided on a liquid channel communicating with the nozzle 31, and fixed electrodes 12A and 12B opposing respective oscillating boards of the ejection chamber 21 and displacing respective oscillating boards at independent timing by generating electrostatic force between them. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a droplet discharge head, a droplet discharge apparatus having the droplet discharge head, and the like.

  For example, micro electro mechanical systems (MEMS) that process silicon or the like to form minute elements or the like have made rapid progress. Examples of microfabricated elements formed by microfabrication technology include, for example, a droplet discharge head (inkjet head), a micropump, and an optical variable filter used in a recording (printing) apparatus such as a droplet discharge type printer. There are electrostatic actuators such as motors, pressure sensors and the like.

  The droplet discharge method (typically, there is an inkjet used for printing by discharging ink) is used for printing (printing) in all fields regardless of household use or industrial use. Yes. In the droplet discharge method, for example, a droplet discharge head having a plurality of nozzles, which are microfabricated elements, is moved relative to an object and the liquid is discharged to a predetermined position of the object. In recent years, it has also been used to manufacture color filters for manufacturing display devices using liquid crystals, display substrates (OLEDs) using organic electroluminescence (Organic ElectroLuminescence) elements, DNA, bioarray microarrays, etc. It's being used.

  As a discharge head for realizing the droplet discharge method, at least one wall of a discharge chamber for storing discharge liquid on the flow path (for example, a bottom wall. This wall is integrally formed with other walls. This wall is referred to as a diaphragm), and the shape is changed by bending, and the diaphragm is bent to increase the pressure in the discharge chamber, and the liquid droplets are discharged from the nozzle communicating with the discharge chamber. There is.

  In the case of an electrostatic droplet discharge head, an electrostatic force is generated between a diaphragm that is a movable electrode and an individual electrode that is a fixed electrode facing the diaphragm, and the diaphragm is attracted to the individual electrode. After that, when the electrostatic force is weakened or the generation is stopped, the restoring force (elastic force) that returns the diaphragm to the original state to be in an equilibrium state works, so that the diaphragm is displaced to the original position. By repeating these steps, the diaphragm is driven and droplets are ejected (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 2005-007735

  As described above, in the liquid droplet ejection head, the vibration plates vibrate, but basically, only two-way selective driving control can be performed by supplying or not supplying electric charges to each individual electrode. Many. However, it is more convenient for the droplet discharge head to be able to perform various controls in order to improve the printing quality and speed. There is a high demand for controlling the electrostatic actuator corresponding to each nozzle so that the droplet discharge amount per landing place (hereinafter referred to as discharge amount) can be changed or stable discharge can be performed.

  Thus, for example, there is a method in which the liquid in the discharge chamber is vibrated small, and the liquid is pressurized by resonating with the vibration to discharge the liquid droplets. However, there is a possibility that the period of small vibrations varies depending on the manufacturing variations of the droplet discharge heads, and it is difficult to set the drive waveform (applied voltage) so that resonance occurs in each head. There is also a method in which individual electrodes are formed in a step shape, and the diaphragm is controlled to be displaced in accordance with each step, and the discharge amount is changed based on the displacement. However, when each step is small, the change in the discharge amount is also small. However, if the distance between the individual electrode and the diaphragm is increased, the electrostatic force is weakened or the power consumption is increased, so that it is difficult to widen the range of change in the discharge amount.

  In view of the above, an object of the present invention is to obtain a droplet discharge head having a structure capable of performing discharge control in various modes.

The droplet discharge head according to the present invention is
A nozzle and a plurality of diaphragms that displace and pressurize the liquid are provided in series, and a discharge chamber provided on a liquid flow path communicating with the nozzle is opposed to the diaphragm of the discharge chamber, and between each diaphragm. A stationary electrode that generates electrostatic force to displace each diaphragm.
According to the present invention, a discharge chamber having a plurality of vibration plates is arranged on the flow path with respect to the nozzle, the vibration plates are displaced by the fixed electrodes that generate electrostatic force between the vibration fields, and the liquid is pressurized. Since ejection is performed, for example, by devising control of a plurality of diaphragms, a plurality of types of ejection amounts can be properly used in a single ejection.

In the liquid droplet ejection head according to the present invention, the fixed electrode includes a plurality of electrodes, which are wired independently and face each diaphragm.
According to the present invention, it is possible to greatly change the discharge amount by changing the timing of displacing each diaphragm.

In the droplet discharge head according to the present invention, two substrates provided with a plurality of fixed electrodes are bonded to both surfaces of a substrate having a plurality of discharge chambers.
According to the present invention, since the plurality of fixed electrodes are provided separately on the two substrates, the number of fixed electrodes and the number of wirings can be reduced compared to the case where the fixed electrodes are arranged on one substrate. A plurality of diaphragms can change the discharge amount, and the droplet discharge head can be downsized.

In the droplet discharge head according to the present invention, the nozzle is provided on the end surface of the head.
According to the present invention, since the nozzle is provided on the end surface of the head, as described above, even if the substrate having the fixed electrodes is provided on both surfaces of the droplet discharge head, the droplet can be discharged from the end surface. . Also in manufacturing, manufacturing is easier than providing a nozzle on a substrate having a fixed electrode.

A droplet discharge device according to the present invention is equipped with the above-described droplet discharge head.
According to the present invention, since the above-described droplet discharge head is mounted, the discharge amount can be controlled. For example, in the case of applications such as image printing, high image quality can be achieved.

In addition, the droplet discharge head discharge control method according to the present invention includes two diaphragms that are arranged in series in a discharge chamber on a flow path communicating with a nozzle, pressurize the liquid by being displaced, and each diaphragm In a discharge control method of a droplet discharge head, which includes two fixed electrodes that generate an electrostatic force based on a potential difference generated between the two and a displacement plate, and pressurizes the liquid by displacing the vibration plate. The process of generating an electrostatic force between the downstream diaphragm closer to the nozzle and the downstream fixed electrode to apply a pressure for discharging the liquid to the liquid, and after the liquid to be discharged from the nozzle as a liquid droplet A process of generating electrostatic force between the upstream diaphragm, which is the other diaphragm, and the upstream fixed electrode to draw the end portion into the flow path, and pulling the upstream diaphragm toward the upstream fixed electrode And have.
According to the present invention, since the rear end portion of the liquid to be discharged from the nozzle is drawn into the flow path by the upstream vibration plate, the control is performed to discharge the liquid droplet by reducing the discharge amount than usual. It can be carried out.

In addition, the droplet discharge head discharge control method according to the present invention includes two diaphragms that are arranged in series in a discharge chamber on a flow path communicating with a nozzle, pressurize the liquid by being displaced, and each diaphragm In a discharge control method of a droplet discharge head, which includes two fixed electrodes that generate an electrostatic force based on a potential difference generated between the two and a displacement plate, and pressurizes the liquid by displacing the vibration plate. Pull the upstream diaphragm farther away from the nozzle toward the upstream fixed electrode and wait, and generate an electrostatic force between the downstream diaphragm, which is the other diaphragm, and the downstream fixed electrode. A step of attracting the liquid to the side fixed electrode side and applying a pressure for droplet discharge to the liquid by the downstream diaphragm and the upstream diaphragm.
According to the present invention, after the upstream diaphragm is drawn to the upstream fixed electrode side and stands by, the pressure for droplet discharge is applied to the liquid by the downstream diaphragm and the upstream diaphragm. By pressurizing the upstream diaphragm, the pressure applied by the downstream diaphragm can suppress the force in the direction opposite to the nozzle direction and increase the force in the nozzle direction. Can be controlled.

In addition, the droplet discharge head discharge control method according to the present invention includes two diaphragms that are arranged in series in a discharge chamber on a flow path communicating with a nozzle, pressurize the liquid by being displaced, and each diaphragm In a discharge control method of a droplet discharge head, which includes two fixed electrodes that generate an electrostatic force based on a potential difference generated between the two and a displacement plate, and pressurizes the liquid by displacing the vibration plate. The process of generating an electrostatic force between the downstream diaphragm closer to the nozzle and the downstream fixed electrode to apply a pressure for droplet discharge to the liquid, and after discharging the droplet from the nozzle, the other Generating an electrostatic force between the upstream diaphragm and the upstream fixed electrode, and causing the upstream diaphragm to generate a vibration that cancels out the natural vibration of the liquid in the flow path.
According to the present invention, a vibration that cancels the natural vibration is generated in the upstream diaphragm so as to suppress the residual vibration after the liquid droplet is discharged, so that the liquid and the diaphragm in the flow path are immediately stabilized. Since the time per discharge can be shortened, the speed can be increased. In particular, since the upstream diaphragm is not displaced and does not overshoot like the downstream diaphragm, the upstream diaphragm can generate an electrostatic force necessary for suppressing residual vibration immediately after ejection.

In addition, the discharge control method of the droplet discharge device according to the present invention controls the discharge of the droplet discharge device by applying the discharge control method of the droplet discharge head described above.
According to the present invention, since the discharge control method of the droplet discharge head is applied, the image quality can be improved by controlling the discharge amount, for example, for applications such as image printing. In particular, since the time spent per place can be reduced, the processing such as printing can be speeded up. In particular, since the discharge interval can be shortened, the speed of processing such as printing can be increased.

Embodiment 1 FIG.
FIG. 1 is an exploded view of a droplet discharge head according to Embodiment 1 of the present invention. FIG. 1 shows a part of the droplet discharge head. In the present embodiment, a face eject type droplet discharge head will be described. The droplet discharge head is a device in which a plurality of electrostatic actuators are integrated for the purpose of forming an image by discharging droplets, for example. In addition, in order to illustrate the constituent members and make it easy to see, the relationship between the sizes of the constituent members in the following drawings including FIG. 1 may be different from the actual one. Further, description will be made with the upper side of the figure as the upper side and the lower side as the lower side.

  As shown in FIG. 1, the droplet discharge head according to the present embodiment is configured by stacking three substrates, an electrode substrate 10, a cavity substrate 20, and a nozzle substrate 30, in order from the bottom. Here, in the present embodiment, the electrode substrate 10 and the cavity substrate 20 are bonded by anodic bonding. The cavity substrate 20 and the nozzle substrate 30 are bonded using an adhesive such as an epoxy resin.

  The electrode substrate 10 is mainly made of a substrate such as a borosilicate heat-resistant hard glass having a thickness of about 1 mm. In the present embodiment, the glass substrate is used, but single crystal silicon may be used as the substrate, for example. A plurality of recesses 11 having a depth of, for example, about 0.3 μm are formed on the surface of the electrode substrate 10. Two individual electrodes (fixed electrodes) are provided inside the recess 11 (particularly at the bottom) so as to face the upstream diaphragm 22A and the downstream diaphragm 22B of the cavity substrate 20. Here, the individual electrode on the upstream side (closer to the reservoir 24) with respect to the liquid flow is referred to as an upstream individual electrode 12A. The upstream individual electrode 12A is integrally provided with an upstream lead portion 13A and an upstream terminal portion 14A (hereinafter referred to as the upstream individual electrode 12A unless otherwise distinguished. To do). Further, the individual electrode closer to the nozzle 31 on the downstream side with respect to the flow of the liquid is defined as the downstream individual electrode 12B. The downstream individual electrode 12B is integrally provided with a downstream lead portion 13B and a downstream terminal portion 14B (hereinafter referred to as the downstream individual electrode 12B together unless otherwise distinguished). Moreover, if it is not necessary to distinguish the upstream individual electrode 12A and the downstream individual electrode 12B, these will be described together as the individual electrode 12). The upstream diaphragm 22A and the downstream diaphragm 22B bend (displace) between the upstream diaphragm 22A (downstream diaphragm 22B) and the upstream individual electrode 12A (downstream individual electrode 12B). A certain gap (air gap) is formed by the recess 11. The upstream individual electrode 12A and the downstream individual electrode 12B are formed by depositing ITO with a thickness of 0.1 μm inside the recess 11 by, for example, sputtering. In addition, the electrode substrate 10 is provided with a through hole serving as a liquid supply port 15 serving as a flow path for taking in liquid supplied from an external tank (not shown).

  The cavity substrate 20 is mainly made of, for example, a silicon single crystal substrate (hereinafter referred to as a silicon substrate) whose surface is (110) plane orientation. The cavity substrate 20 includes a recess that serves as a discharge chamber 21 for temporarily storing a liquid to be discharged (the bottom wall is an upstream diaphragm 22A and a downstream diaphragm 22B that serve as movable electrodes) and a recess that serves as a reservoir 24. (If there is no need to distinguish between the upstream diaphragm 22A and the downstream diaphragm 22B, these will be described together as the diaphragm 22). Here, as for the dimensions of the diaphragm 22 in the present embodiment, for example, the width (length in the short direction) is about 100 μm, the length is about 1.5 mm, and the thickness is 2 μm. However, the present invention is not limited to this.

Further, a TEOS film (here, Tetraethyl orthosilicate Tetraethoxysilane: tetraethylorthosilicate (ethyl silicate) is used on the lower surface of the cavity substrate 20 (surface facing the electrode substrate 10) to electrically insulate the individual electrodes 12 from each other. ) and refers to the SiO ₂ film that can be used as a raw material gas) is an insulating film 23 was 0.1 [mu] m (100 nm) deposited by. Here, the insulating film 23 is formed of a TEOS film, but Al ₂ O ₃ (aluminum oxide (alumina)) or the like may be used, for example. In addition, a recess is formed which becomes a reservoir (common liquid chamber) 24 for supplying a liquid to each discharge chamber 21. Furthermore, a common electrode terminal 27 is provided as a terminal for supplying electric charges from an external power supply means (not shown) to the cavity substrate 20 (the diaphragm 22).

  The nozzle substrate 30 is also mainly made of a silicon substrate, for example. A plurality of nozzles 31 are formed on the nozzle substrate 30. Each nozzle 31 discharges the liquid pressurized by the displacement of the diaphragm 22 to the outside as a droplet. In the present embodiment, the holes of the nozzle 31 are formed in a plurality of stages in order to improve the straightness of the discharged droplets. Further, a diaphragm 32 is further provided for buffering the pressure applied in the direction of the reservoir 24 as the diaphragm 22 is bent. Further, an orifice 33 serving as a groove for communicating the discharge chamber 21 and the reservoir 24 is provided.

  FIG. 2 is a cross-sectional view of the droplet discharge head. In FIG. 2, the discharge chamber 21 stores liquid to be discharged from the nozzle 31. By bending the diaphragm 22 which is the bottom wall of the discharge chamber 21, the pressure in the discharge chamber 21 is increased, and droplets are discharged from the nozzle 31. In the present embodiment, two diaphragms 22 (upstream diaphragm 22A and downstream diaphragm 22B) are formed in the discharge chamber 21 provided on the flow path communicating with each nozzle 31, and the displacement of the two diaphragms ( By controlling the timing of contact and separation, the amount of droplets discharged from the nozzle 31 is changed. Here, a sealing material 25 is provided at the electrode outlet 26 in order to block and seal the gap from the outside air so that foreign matter, moisture (water vapor) and the like do not enter the gap.

  FIG. 3 is a diagram illustrating a configuration centering on the drive control circuit 40. Based on FIG. 3, a description will be given of a means for performing control for ejecting droplets from the droplet ejection head by controlling contact and separation of the diaphragm 22. The drive control circuit 40 includes a head control unit 41 configured around a CPU 42a. For example, a signal including print data is transmitted from the external device 50 such as a computer to the CPU 42a of the head controller 41 via the bus 51.

  The head controller 41 includes a ROM 43a, a RAM 43b, and a character generator 43c, and is connected to the CPU 42a via an internal bus 42b. The CPU 42a executes processing based on a control program stored in the ROM 43a, and generates an ejection control signal corresponding to the printing data. At that time, the storage area in the RAM 43b is used as a work area, and when printing characters or the like, processing based on character data stored in the character generator 43c is performed. The ejection control signal generated by the CPU 42a is transmitted to the logic gate array 45 via the internal bus 42b. Based on the ejection control signal, the logic gate array 45 generates a signal related to charge supply to the individual electrode 12 as described later. Further, a signal relating to charge supply to the cavity substrate 20 (the diaphragm 22) is generated from the COM generation circuit 46a as described later. The drive pulse generation circuit 46b generates a signal for synchronization. These signals are transmitted to the driver IC 48 via the connector 47.

  The driver IC 48 is electrically connected to the upstream terminal portion 14 </ b> A, the downstream terminal portion 14 </ b> B, and the common electrode terminal 27 directly or via a wiring 49 such as an FPC (Flexible Print Circuit) or a wire. If the number of terminals of the driver IC 48 is not enough for the number of nozzles 31 of the droplet discharge head, the driver IC 48 may be composed of a plurality of driver ICs 48. The driver IC 48 receives supply of power from the power supply circuit 52 (voltage is applied), and starts (charges) the charge supply to the cavity substrate 20 (the diaphragm 22) and the individual electrodes 12 based on the various signals described above. , Means for actually holding and discharging. By repeating charge supply, holding, and discharge, for example, a potential difference is generated by creating a state in which charge is supplied to the cavity substrate 20 side but not supplied to the individual electrode 12 side.

  An electrostatic force is generated between the diaphragm 22 and the individual electrode 12 by applying a voltage, and the diaphragm 22 is drawn toward the individual electrode 12 to bend and contact. For this reason, the volume of the discharge chamber 21 increases. When the generation of the electrostatic force is stopped, the diaphragm 22 is released from the individual electrode 12 in order to return to the original state. However, pressure due to the restoring force at this time (hereinafter referred to as restoring pressure) is applied to the liquid, and the liquid is discharged from the nozzle 31. The liquid droplets are ejected by extrusion. The ejected liquid droplets are initially formed in a columnar shape and connected to the liquid droplet ejection head (nozzle 31), and then become spherical due to the surface tension of the liquid and are separated from the liquid droplet ejection head. Recording such as printing is performed when the droplets land on a recording sheet to be recorded, for example. At this time, the discharge amount can be changed by changing the timing of contact and separation by the upstream diaphragm 22A and the downstream diaphragm 22B by controlling the timing of voltage application, respectively. Here, the generation of the electrostatic force is stopped and the diaphragm 22 is detached. However, for example, the electrostatic force may be adjusted without completely stopping the generation of the electrostatic force. By adjusting the electrostatic force and adjusting the speed at which the diaphragm 22 is detached, pressurization of the diaphragm 22 to the liquid can be controlled.

  Next, a control example of the discharge amount discharged from the nozzle 31 performed by the drive control circuit 40 will be described. In the present embodiment, it is assumed that the following modes 1 to 5 are controlled according to the discharge amount from the nozzle 31 to perform the droplet discharge control. Here, although the control regarding five modes is demonstrated, it does not limit to this number. Further, the timing of contact and separation between the upstream diaphragm 22A and the downstream diaphragm 22B is not limited to that in each mode, and another timing setting can be performed.

Mode 1
An electrostatic force is generated between the downstream-side individual electrode 12B and the downstream-side diaphragm 22B, and the downstream-side diaphragm 22B is brought into contact with the downstream-side individual electrode 12B. Then, the downstream diaphragm 22B is detached from the downstream individual electrode 12B to pressurize the liquid, and droplets are ejected from the nozzle 31. As described above, the discharged droplets initially form a columnar shape and are connected to the droplet discharge head. Therefore, before the liquid is separated from the droplet discharge head, an electrostatic force is generated between the upstream individual electrode 12A and the upstream diaphragm 22A, and the upstream diaphragm 22A is brought into contact with the upstream individual electrode 12A. . The front end side of the columnar liquid pressurized by the restoring pressure is kept away from the head while maintaining the momentum of the pressurization, but the rear end side is drawn into the discharge chamber 21B (nozzle 31). In this way, by forcibly separating the trailing edge of the droplet, it is possible to control the discharge amount (the size of the droplet) to be reduced as compared with the case of normal discharge.

Mode 2
An electrostatic force is generated between the downstream-side individual electrode 12B and the downstream-side diaphragm 22B, and the downstream-side diaphragm 22B is brought into contact with the downstream-side individual electrode 12B. Then, the downstream diaphragm 22B is detached from the downstream individual electrode 12B to pressurize the liquid. Unlike mode 1, the upstream diaphragm 22A is brought into contact with the upstream individual electrode 12A and discharged without drawing the trailing edge of the droplet. For this reason, the upstream diaphragm 22A is not brought into contact or detached.

Mode 3
An electrostatic force is generated in advance between the upstream individual electrode 12A and the upstream diaphragm 22A, and the upstream diaphragm 22A is brought into contact with the upstream individual electrode 12A to be on standby. Then, an electrostatic force is generated between the downstream individual electrode 12B and the downstream diaphragm 22B, and the downstream diaphragm 22B is brought into contact with the downstream individual electrode 12B. Thereafter, the downstream diaphragm 22B is detached from the downstream individual electrode 12B to pressurize the liquid, but at the same time, the upstream diaphragm 22A is detached from the upstream individual electrode 12A. Usually, the force due to the restoring pressure is applied not only in the direction of the nozzle 31 but also in the direction of the reservoir 24. In mode 3, the upstream diaphragm 22A is brought into contact in advance. Then, the upstream diaphragm 22A and the downstream diaphragm 22B are simultaneously separated, and the restoring pressure applied in the direction of the reservoir 24 by the downstream diaphragm 22B is canceled by the restoring pressure applied in the direction of the nozzle 31 by the upstream diaphragm 22A. Like that. As a result, the flow (reverse flow) of the liquid trying to flow into the reservoir 24 from the discharge chamber 21 is reduced, and the discharge amount is increased as compared with the mode 2 so that the force is directed to the nozzle 31.

Mode 4
An electrostatic force is generated between the upstream side individual electrode 12A and the upstream side diaphragm 22A, and the downstream side individual electrode 12B and the downstream side diaphragm 22B, and the upstream side diaphragm 22A is brought into contact with the upstream side individual electrode 12A. The side diaphragm 22B is brought into contact with the downstream individual electrode 12B. Thereafter, the upstream diaphragm 22A and the downstream diaphragm 22B are simultaneously separated from the upstream individual electrode 12A and the downstream individual electrode 12B, respectively, to pressurize the liquid. As in mode 3, the restoration pressure by the upstream diaphragm 22A is not used to prevent the backflow of the liquid, but is used positively for discharging from the nozzle 31, so that the discharge amount is higher than in the case of mode 3. Do more. Here, the upstream diaphragm 22A and the downstream diaphragm 22B may be separated at the same time. For example, depending on the type of liquid, the applied voltage, etc., the separation of the downstream diaphragm 22B is slightly accelerated. Alternatively, control according to a desired discharge amount may be performed.

  Next, control of vibration generated in the liquid by the upstream diaphragm 22A will be described. For example, after the diaphragm 22 is detached from the individual electrode 12 and pressurizes the liquid, the diaphragm 22 does not immediately return to the original position but attenuates while repeating overshoot with respect to the original position. Then, free vibration is finally converged to the original position. The vibration other than the displacement to return to the original position first (hereinafter referred to as residual vibration) is not only necessary for the discharge of the droplet, but also adversely affects the operation of the next period and the discharge of other adjacent nozzles. Will be affected. Therefore, the residual vibration should be suppressed.

  Here, if the vibration plate 22 pressurized with liquid and the individual electrode 12 are separated from the distance at the base position due to overshoot, the electrostatic force is suddenly weakened and the control becomes difficult. Therefore, when there is only one diaphragm 22, it is difficult to perform residual vibration control on the diaphragm 22 that overshoots.

  In the present embodiment, two diaphragms 22 are provided in the flow path with respect to the nozzle 31, but when the upstream diaphragm 22A does not perform pressurization for discharge as in mode 1 and mode 2, for example, The upstream diaphragm 22A does not overshoot. Therefore, after the downstream diaphragm 22B pressurizes the liquid, the displacement of the upstream diaphragm 22A is controlled to perform the pressurization so as to suppress the vibration (natural vibration) of the liquid in the discharge chamber 21. Try to suppress vibration.

  As described above, according to the droplet discharge head of the first embodiment, the upstream diaphragm 22A and the downstream diaphragm 22B are arranged in series on the flow path for each nozzle 31. Then, the upstream diaphragm 22A is controlled by generating and stopping the electrostatic force independently between the upstream diaphragm 22A and the individual electrode 12A, and between the downstream diaphragm 22B and the individual electrode 12B. Since the downstream diaphragm 22B is brought into contact with and detached from the nozzle 31 at a predetermined timing, the discharge amount of the liquid droplets discharged from the nozzle 31 can be changed. Therefore, a plurality of types of discharge amounts can be properly used in one discharge. Then, the timing of contact and separation of the two diaphragms 22 is devised, and the change in the discharge amount is increased by applying pressure to the liquid by the two diaphragms 22 and drawing in the liquid to be discharged. , Can widen the range of change.

  In addition, by having a plurality of diaphragms 22, for example, an electrostatic force for suppressing residual vibration can be effectively generated for the upstream diaphragm 22 </ b> A that has not overshooted, and residual vibration can be suppressed. Control can be performed efficiently. Therefore, since residual vibration can be suppressed and the state can be quickly shifted to an equilibrium state, the drive frequency can be increased (the drive cycle can be shortened), and the speed can be increased. Further, the residual vibration does not pressurize the liquid accumulated in the discharge chamber 21 and discharge it from the nozzle 31, nor does it adversely affect the liquid, vibration, etc. in the discharge chamber 21 on the flow path of the other nozzle 31. .

Embodiment 2. FIG.
FIG. 4 is a diagram illustrating an example of a manufacturing process of the electrode substrate 10. In the present embodiment, a manufacturing method of a droplet discharge head will be described. First, a manufacturing procedure of the electrode substrate 10 will be described based on FIG. 4 described above. Here, in the manufacture of the droplet discharge head, a plurality of substrates such as the electrode substrate 10 are actually manufactured at the same time in units of wafers. Although the ejection head is manufactured, in the drawings showing the following steps, a cross section when a part of one droplet ejection head is cut in the long side direction is shown.

First, for example, a glass substrate 60 having a thickness of 2 to 3 mm is ground (grinded) by mechanical grinding, etching or the like until the thickness of the substrate 3a becomes about 1 mm, for example. Then, for example, the glass substrate 60 is etched by 10 to 20 μm to remove the work-affected layer (FIG. 4A). For removing the work-affected layer, for example, dry etching with SF ₆ or the like, spin etching with hydrofluoric acid aqueous solution, or the like may be performed. When dry etching is performed, the work-affected layer formed on one surface of the glass substrate 60 can be efficiently removed, and protection of the opposite surface is not required. Further, when performing spin etching (wet etching), a small amount of etching solution is required, and a new etching solution is always supplied, so that stable etching can be performed.

  A film to be an etching mask 61 made of chromium (Cr) is formed on the entire surface of the glass substrate 60 by, for example, sputtering. Then, a resist (not shown) is patterned on the surface of the etching mask 61 by photolithography so as to correspond to the shape of the concave portion 11, and wet etching or the like is further performed to expose the glass substrate 60 (FIG. 4B). ). Thereafter, for example, the glass substrate 60 is wet-etched with a hydrofluoric acid aqueous solution such as a BHF (buffered hydrofluoric acid. Hydrofluoric acid: ammonium fluoride = 1: 6) aqueous solution to form the recesses 11 (FIG. 4C).

  Thereafter, a conductive ITO film 62 is formed on the entire surface of the glass substrate 60 on which the concave portion 11 is formed by, for example, sputtering (FIG. 4D). Then, a resist (not shown) is patterned by photolithography to protect a portion to be left as the individual electrode 12, and then the ITO film 62 is etched. Further, a through hole that becomes the liquid supply port 15 is formed by a sandblasting method or a cutting process (FIG. 4E). The electrode substrate 10 is manufactured through the above steps.

FIG. 5 is a diagram showing a manufacturing process of the droplet discharge head. One side of the silicon substrate 70 (becomes the bonding surface with the electrode substrate 10) is mirror-polished to produce a substrate having a thickness of 220 μm (to be the cavity substrate 20), for example. Next, the surface of the silicon substrate 70 on which the boron-doped layer is formed is opposed to a solid diffusion source mainly composed of B ₂ O ₃ , and is placed in a vertical furnace to diffuse boron into the silicon substrate 70 to obtain a high concentration. A boron-doped layer (about 5 × 10 ¹⁹ atoms / cm ³ ) is formed. Then, on the surface on which the boron doped layer is formed, for example, by plasma CVD, the processing temperature during film formation is 360 ° C., the high-frequency output is 250 W, the pressure is 66.7 Pa (0.5 Torr), and the gas flow rate is TEOS flow rate 100 cm ^3. The insulating film 23 is formed to a thickness of 0.1 μm under the conditions of / min (100 sccm) and an oxygen flow rate of 1000 cm ³ / min (1000 sccm) (FIG. 5A).

  After the silicon substrate 70 and the electrode substrate 10 are heated to 360 ° C., a negative electrode is connected to the electrode substrate 10 and a positive electrode is connected to the silicon substrate 70, and a voltage of 800 V is applied to perform anodic bonding. In the substrate after anodic bonding (hereinafter referred to as a bonded substrate), the surface of the silicon substrate 70 is ground until the thickness of the silicon substrate 70 becomes about 60 μm. Thereafter, in order to remove the work-affected layer, the silicon substrate 70 is wet-etched by about 10 μm with a potassium hydroxide solution having a concentration of 32 w%. Thus, the thickness of the silicon substrate 70 is set to about 50 μm (FIG. 5B).

Next, a TEOS etching mask (hereinafter referred to as a TEOS etching mask) 71 is formed on the wet etched surface by a plasma CVD method. As film formation conditions, for example, the processing temperature during film formation is 360 ° C., the high-frequency output is 700 W, the pressure is 33.3 Pa (0.25 Torr), the gas flow rate is TEOS flow rate 100 cm ³ / min (100 sccm), and the oxygen flow rate is 1000 cm. ^A film of about 1.0 μm is formed under the condition of ³ / min (1000 sccm) (FIG. 5C). Film formation using TEOS can be performed at a relatively low temperature, which is advantageous in that the heating of the substrate can be suppressed as much as possible.

  Then, resist patterning is performed in order to etch the TEOS etching mask 71 in the portion that becomes the discharge chamber 21 and the electrode outlet 26. Then, the TEOS etching mask 71 is patterned by using a hydrofluoric acid aqueous solution until the TEOS etching mask 71 disappears, and the silicon substrate 70 is exposed. Then, after etching, the resist is peeled off. Here, with respect to the portion that becomes the electrode extraction port 26, for example, the portion that becomes the boundary between the electrode extraction port 26 and the cavity substrate 20 is exposed without leaving silicon exposed, and the remaining portion is left in an island shape. In this case, silicon may be prevented from cracking.

  Further, resist patterning is performed in order to half-etch the TEOS etching mask 71 in a portion that becomes the reservoir 24. Then, the TEOS etching mask 71 of those portions is etched by, for example, about 0.7 μm with a hydrofluoric acid aqueous solution and patterned. As a result, the thickness of the TEOS etching mask 71 remaining in the portion that becomes the reservoir 24 becomes about 0.3 μm, and the silicon substrate 70 is not exposed. Here, the thickness of the TEOS etching mask 71 to be left is about 0.3 μm. However, it is necessary to adjust the thickness depending on the desired size of the flow path and the depth of the reservoir 24. Then, after etching, the resist is peeled off (FIG. 5D).

  Next, the bonded substrate is immersed in a 35 wt% potassium hydroxide aqueous solution, and wet etching is performed until the thickness of the portion where the silicon is exposed in the portion serving as the discharge chamber 21 and the portion serving as the electrode outlet 26 is approximately 10 μm. I do. Thereafter, in order to remove the TEOS etching mask 71 in the portion that becomes the reservoir 24, the bonded substrate is immersed in a hydrofluoric acid aqueous solution and etched and removed. Further, the bonded substrate is immersed in a 3 wt% potassium hydroxide aqueous solution, and etching is continued until it is determined that the etching stop is sufficiently effective in the boron doped layer. Thus, by performing etching using the two types of potassium hydroxide aqueous solutions having different concentrations, it is possible to suppress surface roughness of the diaphragm 22 to be formed and to improve the thickness accuracy. As a result, the discharge performance of the droplet discharge head can be stabilized (FIG. 5E).

When the wet etching is finished, the bonded substrate is immersed in a hydrofluoric acid aqueous solution, and the TEOS etching mask 71 on the surface of the silicon substrate 70 is peeled off. Then, in order to remove the silicon in the portion that becomes the electrode extraction opening 26 of the silicon substrate 70, a silicon mask having an opening in the portion that becomes the electrode extraction opening 25 is attached to the surface of the bonded substrate on the silicon substrate 70 side. Then, for example, RIE dry etching (anisotropic dry etching) is performed for 2 hours under the conditions of an RF power of 200 W, a pressure of 40 Pa (0.3 Torr), and a CF ₄ flow rate of 30 cm ³ / min (30 sccm). A plasma is applied only to the part to be opened. Opening also opens the gap to the atmosphere. Here, the portion of silicon that protrudes with a pin or the like and becomes the electrode outlet 26 may be removed.

  Then, a sealing material 25 made of, for example, epoxy resin is poured along the end of the electrode outlet 26 (the opening portion of the gap formed between the cavity substrate 20 and the recess of the electrode substrate 10) to seal the gap. Stop. In addition, a mask having an opening at a portion to be the common electrode terminal 27 is attached to the surface of the bonding substrate on the silicon substrate 70 side. Then, for example, sputtering is performed using platinum (Pt) as a target to form the common electrode terminal 27. Further, a through hole for communicating the liquid supply port 15 and the reservoir 24 is formed in the silicon substrate 70. Here, in order to protect the cavity substrate 20 from the liquid flowing through the flow path, a liquid protective film (not shown) such as silicon oxide may be further formed. Thereby, the processing performed on the bonded substrate is completed (FIG. 5F).

  By forming the nozzle hole 31, the diaphragm 32, and the orifice 33 in advance, the manufactured nozzle substrate 30 is bonded from the cavity substrate 20 side of the bonded substrate with, for example, an epoxy adhesive. Then, dicing is performed and the liquid droplet ejection head is cut into individual liquid droplet ejection heads, thereby completing the liquid droplet ejection head capable of performing the operation as in the first embodiment (FIG. 5G).

Embodiment 3 FIG.
FIG. 6 is a cross-sectional view of a droplet discharge head according to Embodiment 3 of the present invention. In FIG. 6, the same reference numerals as those in the above-described embodiment perform the same operation, and thus the description thereof is omitted. The upstream electrode substrate 10A is a substrate having the upstream individual electrode 12A described in the first embodiment. On the other hand, the downstream electrode substrate 10B is a substrate having the downstream individual electrodes 12B. Here, since the liquid supply port 15 may be provided on either the upstream electrode substrate 10A or the downstream electrode substrate 10B, it is provided on the upstream electrode substrate 10A in FIG.

  The upstream cavity plate 20A has a concave portion that becomes the discharge chamber 21 described in the first embodiment and an upstream diaphragm 22A that is a part of the concave portion. An insulating film 23A is formed on the surface facing the electrode substrate 10A. And sealing is performed by the sealing material 25A.

  On the other hand, similarly to the upstream cavity plate 20A, the downstream cavity plate 20B has a concave portion that becomes the discharge chamber 21 described in the first embodiment and a downstream diaphragm 22B that is a part of the concave portion. An insulating film 23B is also formed, and sealing with the sealing material 25B is also performed.

  In the present embodiment, the upstream cavity plate 20A and the downstream cavity plate 20B form a hole communicating with the nozzle 31A in a portion that becomes an end surface (side surface) of the droplet discharge head. Although this hole may be used as a nozzle, the shape that can be formed may be defined by, for example, the crystal plane orientation. In order to stabilize the discharge, it is better that the nozzle shape is a cylinder, a conical shape, etc., so that a nozzle plate 30A having a nozzle 31A formed in a predetermined shape in advance is provided on the end surface (side surface) of the droplet discharge head. And

  In the first embodiment described above, the upstream individual electrode 12A and the downstream individual electrode 12B are provided on the electrode substrate 10. However, wiring is performed for wiring the two individual electrodes 12 to one nozzle 31. Wiring may be difficult due to the high density.

  Therefore, in the present embodiment, the upstream individual electrode 12A is formed on the upstream electrode substrate 10A, and the downstream individual electrode 12B is formed on the downstream electrode substrate 10B. Then, a recess serving as a discharge chamber 21 and an upstream diaphragm 22A are formed in the upstream cavity plate 20A according to the upstream individual electrode 12A, and a discharge chamber is formed in the downstream cavity plate 20B according to the downstream individual electrode 12B. 21 and the downstream diaphragm 22B are formed.

  Then, for example, the upstream electrode substrate 10A is disposed on the lower side and the downstream electrode substrate 10B is disposed on the upper side, and the upstream cavity plate 20A and the downstream cavity plate 20B are opposed to each other. Since the upstream electrode substrate 10A and the downstream electrode substrate 10B are arranged vertically, the droplet discharge head according to the present embodiment is not the face eject type as in the first embodiment, but an edge eject type liquid. As a droplet discharge head, a nozzle plate 30A having nozzles 31A is provided on the side of the head.

  In manufacturing the droplet discharge head in the present embodiment, the upstream electrode substrate 10A and the upstream cavity plate 20A are subjected to photolithography, etching, cutting, and the like in the same procedure as described in the second embodiment. And a laminated substrate of the downstream electrode substrate 10B and the downstream cavity plate 20B. Here, when the recesses such as the discharge chamber 21 are formed, a channel for communicating with the nozzle 31A is also formed. Then, the two laminated substrates are bonded with an epoxy adhesive or the like so that the upstream cavity plate 20A and the downstream cavity plate 20B face each other. Then, dicing is performed to cut each droplet discharge head.

  On the other hand, for the production of the nozzle plate 30A, for example, dry etching is performed on a silicon substrate to form nozzle holes with a predetermined depth and division grooves for dividing the nozzle plates into individual nozzle plates are formed. Then, the silicon substrate is polished to penetrate the nozzle hole to form the nozzle 31A. Since the divided grooves formed together with the nozzle holes have the same depth, they are divided into the respective nozzle plates 30A together with the nozzle holes penetrating. Then, each nozzle plate 30A is bonded to a bonded substrate cut by dicing using an epoxy adhesive or the like, thereby completing a droplet discharge head. Since the control such as the discharge amount control is the same as that described in the first embodiment, the description thereof is omitted.

  As described above, in the droplet discharge head according to the third embodiment, each nozzle is divided into two so that the upstream electrode substrate 10A is on the lower side and the downstream electrode substrate 10B is on the upper side. Since the upstream vibration plate 22A and the downstream vibration plate 22B are arranged in series on the flow path with respect to 31, the droplet discharge head having the same effect as in the first embodiment can be reduced in size.

Embodiment 4 FIG.
In the above-described embodiment, the two diaphragms 22 and the two individual electrodes 12 are provided on the flow path for the nozzle 31. However, the number is not limited to this, and three or more vibrations are provided. The plate 22 and the individual electrode 12 may be provided.

  In addition, the timing control of contact and separation of the diaphragm 22 for suppressing residual vibration and changing the discharge amount has been described. The present invention is not limited to these controls, and other controls may be performed.

Embodiment 5. FIG.
For example, in the above-described embodiment, the liquid droplet ejection head configured by laminating the three substrates of the electrode substrate 10, the cavity substrate 20, and the nozzle substrate 30 has been described. However, the present invention is not limited to this. For example, the present invention can also be applied to a droplet discharge head that includes a discharge chamber 21 and a reservoir 24 that are formed on separate substrates and are formed of four stacked layers.

Embodiment 6 FIG.
FIG. 7 is an external view of a droplet discharge apparatus (printer 100) using the droplet discharge head manufactured in the above-described embodiment. FIG. 8 is a diagram illustrating an example of main components of the droplet discharge device. 7 and 8 is intended for printing by a droplet discharge method (inkjet method). Further, it is a so-called serial type device. In FIG. 8, a drum 101 that supports a printing paper 110 that is a printing object and a droplet discharge head 102 that discharges ink onto the printing paper 110 and performs recording are mainly configured. Although not shown, there is an ink supply means for supplying ink to the droplet discharge head 102. The print paper 110 is held by being pressed against the drum 101 by a paper press roller 103 provided parallel to the axial direction of the drum 101. A feed screw 104 is provided parallel to the axial direction of the drum 101, and the droplet discharge head 102 is held. As the feed screw 104 rotates, the droplet discharge head 102 moves in the axial direction of the drum 101.

  On the other hand, the drum 101 is rotationally driven by a motor 106 via a belt 105 or the like. The drive control circuit 40 drives the feed screw 104 and the motor 106 based on the printing data and the control signal. Although not shown here, as described in the first embodiment, the driver IC 48 controls the charge supply to the individual electrodes 12A and 12B and applies an arbitrary voltage to vibrate each diaphragm 22. And printing is performed on the print paper 110 while controlling.

  Here, the liquid is ejected onto the print paper 110 as ink, but the liquid ejected from the droplet ejection head is not limited to ink. For example, in an application to be discharged onto a substrate to be a color filter, a light emitting element is used in an application to be discharged onto a substrate of a display panel (OLED or the like) using an electroluminescent element such as a liquid containing a color filter pigment or an organic compound. For example, a liquid containing a conductive metal and a liquid containing a conductive metal may be discharged from a droplet discharge head provided in each device. In addition, when the droplet discharge head is used as a dispenser and used for discharging onto a substrate that is a microarray of biomolecules, DNA (Deoxyribo Nucleic Acids: deoxyribonucleic acid), other nucleic acids (for example, Ribo Nucleic Acid: ribonucleic acid, Peptide (Nucleic Acids: peptide nucleic acids, etc.) A liquid containing a probe such as a protein may be discharged. In addition, it can also be used for discharging dyes such as cloth.

2 is an exploded view of a droplet discharge head according to Embodiment 1. FIG. 2 is a cross-sectional view of a droplet discharge head according to Embodiment 1. FIG. 2 is a diagram illustrating a configuration centering on a drive control circuit 40. FIG. 5 is a diagram illustrating an example of a manufacturing process of the electrode substrate 10. It is a figure which shows the manufacturing process of a droplet discharge head. 6 is a cross-sectional view of a droplet discharge head according to Embodiment 3. FIG. It is an external view of a droplet discharge device using a droplet discharge head. It is a figure showing an example of the main structural means of a droplet discharge apparatus.

Explanation of symbols

  10 electrode substrate, 10A upstream electrode substrate, 10B downstream electrode substrate, 11 concave portion, 12A upstream individual electrode, 13A upstream lead portion, 14A upstream terminal portion, 12B downstream individual electrode, 13B downstream lead portion, 14B Downstream terminal portion, 15 Liquid supply port, 20 Cavity substrate, 20A Upstream cavity substrate, 20B Downstream cavity substrate, 21 Discharge chamber, 22A Upstream diaphragm, 22B Downstream diaphragm, 23, 23A, 23B Insulating film, 24 Reservoir, 25, 25A, 25B Sealing material, 26 Electrode outlet, 27 Common electrode terminal, 30 Nozzle substrate, 31 Nozzle, 32 Diaphragm, 33 Orifice, 40 Drive control circuit, 41 Head controller, 42a CPU, 42b Bus 43a ROM, 43b RAM, 43c Character Gene 45, logic gate array, 46a COM generation circuit, 46b drive pulse generation circuit, 47 connector, 48 driver IC, 49 wiring, 50 external device, 51 bus, 52 power supply circuit, 60 glass substrate, 61 etching mask, 62 ITO Film, 70 silicon substrate, 71 TEOS etching mask, 100 printer, 101 drum, 102 droplet discharge head, 103 paper pressure roller, 104 feed screw, 105 belt, 106 motor, 107 print control means, 110 print paper.

Claims (9)

A nozzle,
A plurality of diaphragms that are displaced to pressurize the liquid are provided in series, and a discharge chamber provided on a liquid flow path communicating with the nozzle;
A droplet discharge head, comprising: a fixed electrode facing the diaphragm of the discharge chamber and generating an electrostatic force between the diaphragm and displacing each diaphragm.   The liquid droplet ejection head according to claim 1, wherein the fixed electrode includes a plurality of fixed electrodes, and each of the fixed electrodes is independently wired and faces each diaphragm.   3. The droplet discharge head according to claim 2, wherein two substrates provided with the plurality of fixed electrodes separately are bonded to both surfaces of the substrate having the plurality of discharge chambers.   The droplet discharge head according to claim 3, wherein the nozzle is provided on an end surface of the head.   A droplet discharge apparatus comprising the droplet discharge head according to claim 1. Two diaphragms that are arranged in series in discharge chambers on a flow path communicating with the nozzle and pressurize the liquid by displacement, and an electrostatic force based on a potential difference generated between each diaphragm 2 is generated. In a discharge control method of a droplet discharge head comprising two fixed electrodes and pressurizing a liquid by displacing the diaphragm,
A step of generating an electrostatic force between the downstream diaphragm closer to the nozzle and the downstream fixed electrode of the two diaphragms, and applying a pressure for droplet discharge to the liquid;
In order to draw the rear end portion of the liquid to be discharged from the nozzle as droplets into the flow path, an electrostatic force is generated between the upstream diaphragm, which is the other diaphragm, and the upstream fixed electrode. And a step of drawing the upstream diaphragm toward the upstream fixed electrode side. Two diaphragms that are arranged in series in discharge chambers on a flow path communicating with the nozzle and pressurize the liquid by displacement, and an electrostatic force based on a potential difference generated between each diaphragm 2 is generated. In a discharge control method of a droplet discharge head comprising two fixed electrodes and pressurizing a liquid by displacing the diaphragm,
Of the two diaphragms, a step of waiting by drawing the upstream diaphragm farther from the nozzle toward the upstream fixed electrode;
An electrostatic force is generated between the downstream diaphragm, which is the other diaphragm, and the downstream fixed electrode, attracted to the downstream fixed electrode, and droplets are discharged by the downstream diaphragm and the upstream diaphragm. And a step of applying a pressure for the liquid to the liquid. Two diaphragms that are arranged in series in discharge chambers on a flow path communicating with the nozzle and pressurize the liquid by displacement, and an electrostatic force based on a potential difference generated between each diaphragm 2 is generated. In a discharge control method of a droplet discharge head comprising two fixed electrodes and pressurizing a liquid by displacing the diaphragm,
A step of generating an electrostatic force between the downstream diaphragm closer to the nozzle and the downstream fixed electrode of the two diaphragms, and applying a pressure for droplet discharge to the liquid;
After ejecting droplets from the nozzle, an electrostatic force is generated between the upstream diaphragm, which is the other diaphragm, and the upstream fixed electrode, and vibration that cancels out the natural vibration of the liquid in the flow path is generated. And a step of causing the upstream diaphragm to generate the discharge control method of the droplet discharge head.   9. A discharge control method for a droplet discharge device, wherein the discharge control method for a droplet discharge device according to claim 6 is applied to control discharge of the droplet discharge device.

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