JP2007175940A - Droplet jet head, droplet jet device, method for manufacturing droplet jet head, and method for manufacturing droplet jet device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a droplet jet head that is equipped with discrete electrodes each having a plurality of step faces and can control an amount of an ink droplet to be ejected by controlling flowing of an ink in an ejection chamber formed on a cavity substrate, and to provide a droplet jet device, a method for manufacturing the droplet jet head and a method for manufacturing the droplet jet device. <P>SOLUTION: This droplet jet head 100 is equipped with a glass substrate 30 comprising a glass groove 32 having step face sections 40-60 on which the discrete electrodes 31 each having the plurality step faces in a stairway shape, respectively. The step face sections are formed in the stairway shape from the step face section 60 at the lowermost portion formed on the bottom face of the glass groove 32 toward both ends in the longitudinal direction of the glass groove 32. The lengths of the two pairs of step face sections in the stairway shape (the step face section 40a and the step face section 40b, and the step face section 50a and the step face 50b) arranged toward both ends in the longitudinal direction are not symmetric in the longitudinal direction of the glass groove 32. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a droplet discharge head, a droplet discharge device, a method for manufacturing a droplet discharge head, and a method for manufacturing a droplet discharge device, and in particular, a droplet that can adjust the flow of ink and the amount of ink discharged in a discharge chamber. The present invention relates to a discharge head, a droplet discharge device, a method for manufacturing a droplet discharge head, and a method for manufacturing a droplet discharge device.

  As a droplet discharge head for discharging droplets, for example, an inkjet head mounted on an inkjet recording apparatus is known. In general, this inkjet head has a nozzle substrate formed with a plurality of nozzle holes for discharging ink droplets, an ejection chamber joined to the nozzle substrate and communicating with the nozzle holes, and an ink flow path such as a reservoir. And a cavity substrate, and is configured to eject ink droplets from selected nozzle holes by applying pressure to the ejection chamber. As means for ejecting ink droplets as described above, there are an electrostatic drive system using electrostatic force, a piezoelectric system using a piezoelectric element, a bubble jet (registered trademark) system using a heating element, and the like.

  Among these, in an electrostatic drive type inkjet head, a cavity substrate having a bottom plate of a discharge chamber as a vibration plate and a glass substrate on which individual electrodes facing the vibration plate through a predetermined gap (gap) are formed. The structure is joined. This individual electrode is formed by sputtering ITO (Indium Tin Oxide) or the like on the bottom surface of a recess formed on the surface of a glass substrate, for example, in order to ensure a predetermined gap length so as to allow the vibration plate to be displaced. ing.

  Then, when ejecting ink droplets, a drive voltage is applied to the individual electrodes to be positively charged, and a drive voltage is applied to the corresponding diaphragm to be negatively charged. Then, the diaphragm is elastically deformed toward the individual electrode by the electrostatic attractive force generated at this time. When this drive voltage is turned off, the diaphragm is restored. At this time, the pressure inside the discharge chamber rises rapidly, and a part of the ink in the discharge chamber is discharged from the nozzle hole as an ink droplet.

  In recent years, in such an electrostatic drive type ink jet head, it is required to increase the density of nozzle holes. In addition, it is required to secure an ink discharge amount without causing an increase in driving voltage. As one of the measures, “having a diaphragm and an individual electrode provided opposite to the diaphragm on an electrode substrate bonded to the diaphragm via a gap, and between the diaphragm and the individual electrode, An electrostatic actuator that applies a driving voltage and deforms the diaphragm by an electrostatic force, and forms a gap between the diaphragm, which is formed of a rectangle having a short side and a long side, and an individual electrode. There has been proposed an electrostatic actuator that has a gap, the short side of which is a concave shape, and is formed in a step shape having at least two gap lengths (for example, Patent Document 1). reference).

  Further, “an ink nozzle that ejects ink, an ink chamber that communicates with the nozzle and holds the ink, an ink supply path that supplies ink to the ink chamber, and the ink chamber are partitioned. A diaphragm that is formed on the peripheral wall and is elastically displaceable in an out-of-plane direction; and an opposing wall that is disposed opposite to the diaphragm on the outside of the ink chamber, In an inkjet head that ejects ink droplets from the ink nozzles using pressure fluctuations generated in the ink chamber in response to vibration of the diaphragm, a relatively large gap is provided as the gap between the diaphragm and the opposing wall. An “inkjet head having a portion and a small gap portion” has been proposed (see, for example, Patent Document 2).

JP 2000-318155 A (first page, FIG. 2) JP 09-39235 (Page 5, FIG. 1)

  In the electrostatic actuator described in Patent Document 1, the individual electrodes are formed in multiple steps in a stepped manner, and when the diaphragm is elastically deformed by electrostatic attraction, it abuts along the stepped portions of the stepped individual electrodes. Elastic deformation can be obtained. Therefore, it is possible to ensure a predetermined ink discharge amount without increasing the drive voltage (or lowering the drive voltage). In addition, by forming an insulating film on the electrode portion in the glass groove, a short circuit at the time of contact is prevented.

  However, in such an electrostatic actuator, the number of patterning and etching increases proportionally as the number of steps increases. As a result, the number of man-hours in the manufacturing process increased accordingly, which was troublesome. In addition, when the number of work steps increases, the yield decreases, and thus there is a problem that the manufacturing cost of the electrostatic actuator increases significantly.

  In the ink jet head described in Patent Document 2, even if the driving voltage applied between the diaphragm and the counter electrode is small, the diaphragm portion located in the small gap is easily elastically displaced toward the counter wall. It is supposed to be. Therefore, it is possible to reduce the applied drive voltage. In addition, by controlling the discharge rate to control the contact of each opposing wall with the diaphragm, the compliance by the ink vibration system can be changed, and the amount of ink droplets to be ejected can be adjusted. ing.

  In other words, the responsiveness at the time of ink ejection is increased to eject ink droplets at high speed, and the fluid movement after ink ejection is relaxed to suppress unnecessary ink droplet ejection. . However, although the amount of ink droplets can be adjusted at the ejection speed, it has not been possible to control the flow of ink in the ejection chamber by adjusting the vibration plate and adjust the amount of ink droplets to be ejected.

  The present invention has been made to solve the above-described problems, and controls the flow of ink in a discharge chamber formed on a cavity substrate in a droplet discharge head provided with individual electrodes having a plurality of step surfaces. It is an object of the present invention to provide a droplet discharge head, a droplet discharge device, a method for manufacturing a droplet discharge head, and a method for manufacturing a droplet discharge device capable of adjusting the amount of ink droplets to be discharged.

  The droplet discharge head according to the present invention includes a cavity substrate on which a bottom wall forms a vibration plate and a discharge chamber for storing and discharging droplets, and an individual electrode that faces the vibration plate and drives the vibration plate. A droplet discharge head comprising a glass substrate and a nozzle substrate in which nozzle holes for discharging droplets transferred from a discharge chamber are formed. The step is formed with a plurality of step surfaces stepwise from the intermediate portion toward both ends in the longitudinal direction with the portion as the lowermost step surface, and the step surfaces having the same height in the two stepped step surfaces toward both ends The length in the longitudinal direction is asymmetric.

  Therefore, it is possible to control the flow of ink in the discharge chamber by using the inclined surface generated when the diaphragm abutted on the electrode (individual electrode) is detached. In addition, the flow of ink can be controlled, and the amount of ink discharged from the nozzle holes can be adjusted. In other words, it can be used properly according to the use of the droplet discharge head, and can be set according to the purpose and use requested by the user.

  The droplet discharge head according to the present invention is provided with a glass groove for installing an individual electrode on a glass substrate, and the glass groove has an intermediate portion of the plane as a lowermost surface and extends from the intermediate portion to both ends in the longitudinal direction. A plurality of step surfaces are formed in a step shape, and the lengths in the longitudinal direction of the step surfaces having the same height in the two step surface steps toward both ends of the individual electrode are made asymmetric. Therefore, the glass substrate can be processed without requiring a complicated manufacturing process.

  The droplet discharge head according to the present invention is characterized in that, for each individual electrode, an asymmetry of the length in the longitudinal direction of the step surface having the same height in the two stepped step surfaces facing both ends can be set. Therefore, the amount of ink ejected for each individual electrode can be adjusted, and the setting of the droplet ejection head can be executed in more detail. That is, it is possible to provide the user after setting the ink discharge amount set according to the use of the droplet discharge head in more detail.

  A droplet discharge apparatus according to the present invention includes the above-described droplet discharge head. Therefore, the droplet discharge device has the same effect as the above-described droplet discharge head.

  The manufacturing method of a droplet discharge head according to the present invention includes a cavity substrate on which a bottom wall forms a vibration plate and a discharge chamber in which droplets are collected and discharged, and an individual electrode that faces the vibration plate and drives the vibration plate The glass substrate on which the nozzle is formed is bonded with a gap between the diaphragm and the individual electrode, and the nozzle substrate on which the nozzle hole for discharging the droplets transferred from the discharge chamber is formed is bonded to the cavity substrate. A method for manufacturing a droplet discharge head is provided, wherein a glass groove for installing an individual electrode is provided on a glass substrate, the plane of the individual electrode has an elongated shape, and an intermediate portion of the plane is used as a lowermost surface. A plurality of step surfaces are provided stepwise from the portion toward both ends in the longitudinal direction, and the lengths in the longitudinal direction of the step surfaces having the same height in the two stepped step surfaces facing both ends are formed as asymmetric. .

  Therefore, it is possible to control the flow of ink in the discharge chamber by using the inclined surface generated when the diaphragm abutted on the electrode (individual electrode) is detached. In addition, the flow of ink can be controlled, and the amount of ink discharged from the nozzle holes can be adjusted. In other words, it can be used properly according to the use of the droplet discharge head, and can be set according to the purpose and use requested by the user.

  In the method for manufacturing a droplet discharge head according to the present invention, a plurality of step surfaces are formed stepwise from the intermediate portion toward both ends in the longitudinal direction in the glass groove, with the intermediate portion of the plane being the lowest step surface. The longitudinal lengths of the step surfaces having the same height in the two stepped step surfaces facing both ends of the individual electrode are asymmetric.

  Therefore, it is possible to control the flow of ink in the discharge chamber by using the inclined surface generated when the diaphragm abutted on the electrode (individual electrode) is detached. In addition, the flow of ink can be controlled, and the amount of ink discharged from the nozzle holes can be adjusted. In other words, it can be used properly according to the use of the droplet discharge head, and can be set according to the purpose and use requested by the user.

  The manufacturing method of the droplet discharge head according to the present invention is characterized in that the individual electrodes are formed by sputtering. Therefore, the droplet discharge head can be manufactured without requiring a special process. In addition, a method for manufacturing a droplet discharge device according to the present invention includes the above-described method for manufacturing a droplet discharge head. Therefore, it has the same effect as the above-described manufacturing method of the droplet discharge head.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Embodiment 1 FIG.
FIG. 1 is an exploded perspective view of a droplet discharge head 100 according to Embodiment 1 of the present invention. FIG. 2 is a cross-sectional view showing a schematic configuration of the droplet discharge head 100. The configuration and operation of the droplet discharge head 100 will be described with reference to FIGS. In the embodiment, as a representative of a device equipped with an electrostatic actuator that is driven by an electrostatic drive method, a face ejection type droplet discharge head that discharges droplets from nozzle holes provided on the surface side of the nozzle substrate. Is described as an example. Moreover, in the following drawings including FIG. 1, the relationship of the size of each component may be different from the actual one.

  As shown in FIG. 1, this droplet discharge head 100 is characterized by a three-layer structure in which three substrates, a nozzle substrate 10, a cavity substrate 20, and a glass substrate 30, are joined in order. The nozzle substrate 10 is bonded to one surface (upper surface) of the cavity substrate 20, and the glass substrate 30 is bonded to the other surface (lower surface). That is, the cavity substrate 20 is sandwiched between the glass substrate 30 and the nozzle substrate 10 from above and below.

  In this embodiment, it is assumed that the glass substrate 30 and the cavity substrate 20 are bonded by anodic bonding, and the cavity substrate 20 and the nozzle substrate 10 are bonded using an adhesive such as an epoxy resin. The individual electrodes 31 formed on the glass substrate 30 of the droplet discharge head 100 are supplied with a drive signal (pulse voltage) by a power supply means such as a driver IC (not shown).

[Glass substrate 30]
The glass substrate 30 is preferably formed using, for example, glass such as borosilicate glass having a thickness of 1 mm as a main material. Here, a case where the glass substrate 30 is formed of borosilicate glass is shown as an example, but the glass substrate 30 may be formed of single crystal silicon. On the surface of the glass substrate 30, a plurality of glass grooves 32 are formed in accordance with the shape of the recess 21 a that becomes the discharge chamber 21 of the cavity substrate 20 described later.

  In addition, inside the glass groove 32 (particularly at the bottom), the individual electrodes 31 serving as fixed electrodes are formed so as to face the respective discharge chambers 21 (vibrating plates 22) of the cavity substrate 20 with a certain interval. Has been. And this glass groove | channel 32 is pattern-formed by the slightly large shape similar to these shapes so that the one part can mount | wear with the individual electrode 31. FIG. The individual electrode 31 may be produced by sputtering ITO (Indium Tin Oxide) with a thickness of 0.1 μm, for example.

  Further, the individual electrode 31 is manufactured by integrating the lead portion 33 and the terminal portion 34. One end (terminal portion 34) of the individual electrode 31 is connected to a power supply unit (not shown), and a drive signal is supplied from the power supply unit to the individual electrode 31. Note that the lead portion 33 and the terminal portion 34 are combined to be described as the individual electrode 31 unless it is particularly necessary to distinguish between them.

Here, the detail of the glass groove | channel 32 which is the characteristic part of Embodiment 1 is demonstrated.
On the bottom surface of the glass groove 32, three stepped step surface portions 40, 50, and 60 are provided in the longitudinal direction (long side direction) of the glass groove 32 (or the individual electrode 31). The step surface means a surface having a step having a predetermined height. The individual electrodes 31 having the same number of step surfaces are formed on these step surface portions 40, 50 and 60. Therefore, as shown in FIG. 2, the individual electrode 31 has stepped gap lengths G1, G2, and G3 between the diaphragm 22 and the glass substrate 30 and the cavity substrate 20 when bonded. Yes. The gap lengths G1, G2, and G3 are distances between the surface (lower surface) of the insulating film 24 formed on the lower surface of the diaphragm 22 and the surface of the individual electrode 31 formed in a step shape.

  Moreover, the step surface parts 40 and 50 are comprised by the part of the same height divided into 2 with respect to the longitudinal direction. That is, the step surface portion 40 includes a step surface portion 40a and a step surface portion 40b, and the step surface portion 50 includes a step surface portion 50a and a step surface portion 50b. And the difference is provided in the length of these step surface parts. That is, the length of the stepped portion having the same height is made asymmetric. In FIG. 1 and FIG. 2, the step surface portions closer to the nozzle hole 11 (step surface portion 40 a and step surface portion 50 a) are formed shorter than the step surface portions farther from the nozzle hole 11 (step surface portion 40 b and step surface portion 50 b). ing.

  In this way, the flow of ink in the discharge chamber 21 is controlled by making the length of the stepped surface portions of the same height asymmetric. In other words, if the lengths of the stepped surface portions having the same height are made asymmetrical, a difference occurs in the time during which the diaphragm 22 is kept in contact with the individual electrode 31. The flow is controlled. As shown in FIG. 1, when the stepped surface portion 40a and the stepped surface portion 50a are shorter than the stepped surface portion 40b and the stepped surface portion 50b, the contacting diaphragm 22 is detached from the stepped surface portion 40a and the stepped surface portion 50a.

  Therefore, it is effective when it is desired to reduce the amount of ink droplets ejected from the nozzle hole 11 (details will be described with reference to FIGS. 3 and 4). On the other hand, when it is desired to increase the amount of ink droplets ejected from the nozzle hole 11, the step surface portion closer to the nozzle hole 11 (the step surface portion 40 a and the step surface portion 50 a) is changed to the step surface portion farther from the nozzle hole 11 ( What is necessary is just to form longer than the step surface part 40b and the step surface part 50b). Further, the step surface may be made asymmetric for each individual electrode 31 so as to change the discharge amount of each nozzle hole 11 (see FIGS. 8 and 9).

  When the glass substrate 30 and the cavity substrate 20 are joined, a certain gap (air gap) that allows the vibration plate 22 to bend (displace) between the vibration plate 22 and the individual electrode 31. It is formed by the glass groove 32. Since the glass groove 32 is provided with the stepped step surface portion as described above, the gap has a gap length corresponding to the step surface portion (that is, the gap lengths G1, G2, and G3). ing. The glass substrate 30 is provided with an ink supply hole 25 serving as a flow path for taking in liquid supplied from an external ink tank (not shown).

  In the droplet discharge head 100, a plurality of individual electrodes 31 are formed in a rectangular shape having long sides and short sides, and the individual electrodes 31 are arranged so that their long sides are parallel to each other. FIG. 1 shows two electrode rows extending in the short side direction of the individual electrode 31. In addition, when the short side of the individual electrode 31 is formed obliquely with respect to the long side and the individual electrode 31 has an elongated parallelogram shape, an electrode array extending in a direction perpendicular to the long side direction is formed. What should I do?

[Cavity substrate 20]
The cavity substrate 20 is configured with, for example, a silicon single crystal substrate (hereinafter simply referred to as a silicon substrate) having a thickness of about 50 μm (micrometer) as a main material. The cavity substrate 20 is formed with a plurality of recesses 21 a that serve as discharge chambers (or pressure chambers) 21 whose bottom wall serves as the diaphragm 22. The discharge chamber 21 is formed corresponding to the electrode row of the individual electrode 31.

Furthermore, on the lower surface of the cavity substrate 20 (the surface facing the glass substrate 30), a TEOS film (herein, tetraethylsilane: tetraethoxysilane) for electrically insulating between the diaphragm 22 and the individual electrode 31 is provided. An insulating film 24 made of (which is an SiO ₂ film made of ethyl silicate) is formed to a thickness of 0.1 μm by plasma CVD (also referred to as Chemical Vapor Deposition: TEOS-pCVD). This is for preventing dielectric breakdown and short-circuit when the diaphragm 22 is driven, and for preventing etching of the cavity substrate 20 by droplets of ink or the like.

Although the case where the insulating film 24 is a TEOS film is shown here, the present invention is not limited to this, and any material that improves the insulating performance may be used. For example, Al ₂ O ₃ (aluminum oxide (alumina)) may be used. The cavity substrate 20 is also provided with ink supply holes 25 (in communication with the ink supply holes 25 provided in the glass substrate 30). Furthermore, a common electrode terminal 27 is provided which serves as a terminal for supplying a charge having a polarity opposite to that of the individual electrode 31 from the power supply means (not shown) to the diaphragm 22.

The diaphragm 22 may be formed of a high concentration boron doped layer. The etching rate in etching single crystal silicon with an alkaline solution such as an aqueous potassium hydroxide solution is very small in a high concentration region of about 5 × 10 ¹⁹ atoms / cm ³ or more when the dopant is boron. For this reason, when the diaphragm 22 is formed as a high-concentration boron-doped layer and the discharge chamber 21 is formed by anisotropic etching with an alkaline solution, the boron-doped layer is exposed and the etching rate becomes extremely small, so-called etching stop. By using the technique, the diaphragm 22 can be formed to a desired thickness.

[Nozzle substrate 10]
The nozzle substrate 10 is composed of, for example, a silicon substrate having a thickness of about 100 μm as a main material. And it is joined to the upper surface of the cavity substrate 20 (the surface opposite to the surface to which the glass substrate 30 is joined). A plurality of nozzle holes 11 communicating with the discharge chamber 21 are formed on the upper surface of the nozzle substrate 10. Each nozzle hole 11 discharges the liquid droplets transferred from the discharge chamber 21 to the outside. In addition, when the nozzle hole 11 is formed in a plurality of stages (for example, two stages), it is possible to expect improvement in straightness when ejecting droplets.

  A narrow groove serving as the orifice 12 is provided on the lower surface, and the discharge chamber 21 and the recess serving as the reservoir 23 are communicated with each other. Here, the nozzle substrate 10 having the nozzle holes 11 is described as the upper surface, and the glass substrate 30 is described as the lower surface. However, when actually used, the nozzle substrate 10 is often lower than the glass substrate 30. . In the first embodiment, the case where the orifice 12 is formed on the nozzle substrate 10 is shown as an example, but the orifice 12 may be formed on the cavity substrate 20. The nozzle substrate 10 is provided with a diaphragm 13 for buffering the pressure applied to the liquid on the reservoir 23 side by the vibration plate 22.

  Here, the operation of the droplet discharge head 100 will be described. A droplet such as ink is supplied to the reservoir 23 from the outside through the ink supply hole 15. In addition, droplets are supplied from the reservoir 23 to the discharge chamber 21 via the supply port 32. A pulse voltage of about 0 V to 40 V is applied to the individual electrode 31 selected by the power supply means such as a driver IC, and the individual electrode 31 is positively charged.

  At this time, charge having a negative polarity is supplied to the cavity substrate 20 through the common electrode terminal 27, and the diaphragm 22 corresponding to the positively charged individual electrode 31 is relatively negatively charged. Therefore, an electrostatic force is generated between the selected individual electrode 31 and the diaphragm 22. If it does so, the diaphragm 22 will be drawn near to the individual electrode 31 side by electrostatic force, and will bend.

  That is, as described above, the individual electrode 31 is provided with a plurality of stepped surface portions 40, 50 and 60 in a step shape so that the central portion in the longitudinal direction is the lowest, and the gap length is accordingly increased stepwise. Therefore, the diaphragm 22 is displaced from the step surface portion 40 to the step surface portion 60 by forward feeding, and is attracted to the individual electrode 31 and comes into contact therewith. As a result, the volume of the discharge chamber 21 increases.

  Thereafter, when the supply of electric charges to the individual electrode 31 is stopped, the electrostatic force between the diaphragm 22 and the individual electrode 31 disappears, and the diaphragm 22 is restored to the original state by the elastic force. At this time, since the volume of the discharge chamber 21 is rapidly decreased, the pressure inside the discharge chamber 21 is rapidly increased. Thereby, a part of the ink in the discharge chamber 21 is discharged from the nozzle hole 11 as an ink droplet. Printing or the like is performed by the droplets landing on a recording sheet, for example. Thereafter, the droplets are replenished from the reservoir 23 into the discharge chamber 21 through the supply port 32, and the initial state is restored.

  FIG. 3 is an explanatory view showing a state in which the diaphragm 22 is in contact with the individual electrode 31. FIG. 4 is an explanatory diagram showing a state when the diaphragm 22 that has been in contact with the individual electrode 31 is detached. Based on FIGS. 3 and 3, control of the flow of ink in the ejection chamber 21 will be described. In the liquid droplet ejection head 100, when a voltage sufficient and sufficient for the diaphragm 22 corresponding to the gap length G1 to contact the individual electrode 31 is applied between the diaphragm 22 and the individual electrode 31, the diaphragm 22 is held in contact with the individual electrode 31 of the first stage having the smallest gap length.

  At this time, the gap length temporarily becomes (gap length G2−gap length G1) at the boundary portion corresponding to the gap length G1 and the gap length G2. Thereby, since a large electrostatic attraction force acts on the diaphragm 22, the diaphragm 22 corresponding to the next gap length G <b> 2 is also in contact with the counter electrode 31 with the same voltage. In this way, the forward feeding action is continuously induced up to the portion corresponding to G3 having the largest gap length.

  Accordingly, the entire diaphragm 22 can be brought into contact with the counter electrode 31 with a voltage necessary and sufficient for the portion of the diaphragm 22 corresponding to the gap length G1 to come into contact with the counter electrode 31. In this way, the manner or contact state in which the diaphragm 22 contacts in order along each step of the counter electrode 31 is referred to as “coupled contact”. The diaphragm 22 does not necessarily have to be in contact with all the stepped surface portions of the counter electrode 31. For example, the diaphragm 22 may not come into contact with the lowermost counter electrode 31, but such a state is also included in the concept of “coupled contact”.

  The step surface portion to which the diaphragm 22 is brought into contact is controlled by power supply means for supplying a drive signal to the individual electrode 31. That is, the contact position may be controlled by adjusting the supply time of the drive signal supplied by the power supply means. Therefore, the droplet discharge head 100 according to Embodiment 1 can increase the displacement of the diaphragm 22 without increasing the drive voltage or even with a low drive voltage. Therefore, it is possible to stably secure the ink discharge amount.

  Furthermore, the step surface portion 40a and the step surface portion 40b of the step surface portion 40 are formed such that the length of the glass groove 32 in the longitudinal direction is asymmetric. The same applies to the stepped surface portion 50. In this way, the flow of ink in the discharge chamber 21 is controlled by using the inclination when the diaphragm 22 that is in contact with the combined contact is detached. As shown in FIG. 4, the diaphragm 22 is detached from the short step surface portion (here, the step surface portion 50 a). At this time, the diaphragm 22 has a predetermined inclined surface.

  That is, the flow of ink in the discharge chamber 21 is controlled by using the inclined surface generated at that time. For example, as shown in FIG. 4, when the droplet discharge head 100 is used under conditions where it is preferable that the amount of ink droplets discharged from the nozzle holes 11 is small, a stepped surface portion closer to the nozzle holes 11 is formed. If shortened, most of the ink in the discharge chamber 21 flows in the direction opposite to the nozzle holes 11 (in the direction of the arrows in the figure). Conversely, when the droplet discharge head 100 is used under conditions where it is preferable that the amount of ink droplets discharged from the nozzle holes 11 is large, the stepped surface portion closer to the nozzle holes 11 may be made longer.

  As described above, the droplet discharge head 100 has the stepped surface portions 40, 50 and 60 in which the bottom surface of the glass groove 32 of the glass substrate 30 has a stepped shape in the longitudinal direction, and the same number of individual electrodes 31 formed on the bottom surface. Therefore, the elastic deformation of the diaphragm 22 abuts along the step surface portion of the individual electrode 31 during driving, as shown in FIG. Therefore, the volume increase of the discharge chamber 21 is increased, and as a result, a necessary ink discharge amount can be ensured without increasing the drive voltage.

  Furthermore, since the lengths of the stepped surface portion 40a and the stepped surface portion 40b constituting the stepped surface portion 40 and the stepped surface portion 50 and the stepped surface portion 50a and the stepped surface portion 50b are asymmetrical, they are selectively used according to the application of the droplet discharge head 100. It is possible to do. Therefore, the amount of ink droplets can be adjusted according to the position where the combined contact is made, and the flow of ink in the discharge chamber 21 can be controlled by using the inclined surface when the combined contact is released. It can be done.

  Note that the depths of the gap lengths G1 to G3 are not particularly limited. For example, the largest (deep) gap length G3 may be 140 μm, and the smallest (shallow) gap length G1 may be 80 μm. In addition, the step surface of each step of the individual electrode 31 is preferably formed so as to become smaller toward the center of the glass groove 32. This is because the entire vibration plate 22 can be easily brought into contact with the counter electrode 31 with a driving voltage at which the vibration plate 22 and the counter electrode 31 are in contact with each other in the portion having the smallest gap length.

  Furthermore, in Embodiment 1, although the case where the three step surface parts were formed was demonstrated to the example, it is not limited to this. For example, the number of stepped surface portions may be two or less, or may be four or more, and the number of stepped surface portions may be set according to the application of the droplet discharge head 100. Further, the lengths of the stepped surface portions 40a and 40b and the stepped surface portion 50a and the stepped surface portion 50b are not particularly limited. For example, the length of each stepped surface portion may be determined in consideration of the ink flow in the ejection chamber 21.

Next, the manufacturing process of the glass substrate 30 is demonstrated based on drawing.
5-7 is a longitudinal cross-sectional view which shows the manufacturing process of the glass substrate 30. FIG. Here, although the manufacturing method of the glass substrate 30 which has a three-step step surface part (step surface part 40-step surface part 60) is shown as an example, it is not limited to this. In the following description, the thickness, etching, depth, etc. of the substrate are merely examples, and do not limit the present invention.

  First, a borosilicate glass substrate 30a processed to a predetermined thickness (for example, 1 mm thick) is prepared (FIG. 5A). Next, an etching mask 80 made of chromium (Cr) is formed on the surface of the glass substrate 30a, for example, by sputtering, and etching is performed by patterning a resist (not shown) having a predetermined shape on the surface of the etching mask 80 by photolithography. Then, an opening having a shape corresponding to the third step surface portion 60 of the glass groove 32 is formed in the etching mask 80 (FIG. 5B).

  Then, for example, the stepped surface portion 60 is formed by etching the glass substrate 30a with a hydrofluoric acid aqueous solution (FIG. 5C). Then, after removing the resist with an organic stripping solution or the like, the glass substrate 30a is immersed in a chromium etching solution to remove the etching mask 80 (FIG. 5D). Next, the second etching mask 81 is patterned and etched by photolithography so as to cover the portion from the end of the glass substrate 30a to the stepped surface portion 50 (FIG. 5E).

  That is, an etching mask 81 made of chromium, for example, is formed by sputtering on the surface of the glass substrate 30a in FIG. 5D, and etching is performed by patterning a resist (not shown) having a predetermined shape on the surface of the etching mask 81 by photolithography. Then, the third step surface portion 60 and the second step surface portion 50 are formed on the etching mask 81. Then, for example, by etching the glass substrate 30a with a hydrofluoric acid aqueous solution, the stepped surface portion 50 and the stepped surface portion 60 are dug down (FIG. 6F).

  Next, after stripping the resist with an organic stripping solution or the like, if the glass substrate 30a is immersed in a chrome etching solution and the etching mask 81 is removed, the step surface portion 50 and the step surface portion 60 up to the second and third steps are stepped. It is formed (FIG. 6 (g)). The step surface portion 50 includes a step surface portion 50a and a step surface portion 50b. The length of the step surface portion 50a in the longitudinal direction of the glass substrate 30a is shorter than the length of the step surface portion 50b in the longitudinal direction of the glass substrate 30a. ing.

  Then, the third etching mask 82 is patterned and etched by photolithography so as to cover the surface portion from the edge of the glass substrate 30a to the first stepped surface portion 40 (FIG. 6 (h)). That is, an etching mask 82 made of chromium, for example, is formed by sputtering on the surface of the glass substrate 30a in FIG. 6G, and a resist (not shown) having a predetermined shape is patterned on the surface of the etching mask 82 by photolithography. Steps 1 to 3 are formed on the etching mask 82.

  Then, for example, by etching the glass substrate 30a with a hydrofluoric acid aqueous solution, the first stepped surface portion 40 is dug down (FIG. 6 (i)). Then, after the resist is stripped with an organic stripping solution or the like, the glass substrate 30a is immersed in a chrome etching solution and the etching mask 82 is removed, whereby the stepped surface portions 40 to 60 from the first step to the third step are formed stepwise. (FIG. 6 (j)). The step surface portion 40 includes a step surface portion 40a and a step surface portion 40b, and the length of the step surface portion 40a in the longitudinal direction of the glass substrate 30a is shorter than the length of the step surface portion 40b in the longitudinal direction of the glass substrate 30a. ing.

  As described above, the patterning and etching of the etching mask 80 to the etching mask 82 are repeated three times in total, whereby the three stepped portions 40 to 60 can be formed on the bottom surface of the glass substrate 30a. In addition, the depth (gap length G1-G3) of each step surface part can be formed in a required dimension by adjusting etching time. Moreover, the depth and length of each step surface part are not specifically limited.

  Thereafter, for example, an ITO (Indium Tin Oxide) film 85 is formed on the entire surface of the glass substrate 30a including the glass grooves by sputtering (FIG. 7 (k)). The ITO film 85 is formed to be thicker than any step surface of the glass groove 32 formed in a step shape. For example, the film may be formed to have a thickness of 0.1 μm. Then, a resist (not shown) is patterned and etched by photolithography to form an ITO pattern corresponding to the individual electrode 31 (FIG. 7L).

  That is, the individual electrode 31 is formed on the stepped step surface portions 40 to 60, and a plurality of gap lengths G1 to G3 are formed in the gap. Here, the case where the material of the counter electrode 31 is ITO has been described as an example, but the present invention is not limited to this. For example, a metal such as chrome may be used. However, since ITO is transparent, it is generally often used because it is easy to check whether or not it has been discharged.

  As described above, the glass substrate 30 is manufactured. After that, the cavity substrate 20 is anodically bonded to the glass substrate 30 through the insulating film 24 with the diaphragm 22 facing the individual electrode 31, and the nozzle substrate 10 is bonded to the cavity substrate 20 with an adhesive such as epoxy resin. The droplet discharge head 100 is manufactured by using and bonding. Here, the case where the glass substrate 30a is used as the substrate to be processed has been described as an example, but the substrate material is not particularly limited, and for example, a silicon substrate may be used.

  In addition, although the manufacturing process of the step surface portion has three steps (step surface portions 40 to 60) has been described as an example, the number of step surface portions is not limited to three steps. For example, the step surface portion may be two steps or less, or may be four steps or more. Further, the depth and length of each stepped surface portion may be set according to the application in which the droplet discharge head 100 is used. For example, if it is desired to eject a large amount of ink droplets, the stepped surface portion closer to the nozzle hole 11 may be formed shorter. Conversely, if it is desired to eject less ink droplets, the step closer to the nozzle hole 11 is required. What is necessary is just to form a surface part long.

Embodiment 2. FIG.
FIG. 8 is a perspective view of the glass substrate 35 used in the droplet discharge head according to the second embodiment. In the second embodiment, differences from the first embodiment will be mainly described, and the same parts as those in the first embodiment will be denoted by the same reference numerals and description thereof will be omitted. That is, a difference is provided in the stepped surface portion formed in the glass groove 32a of the glass substrate 35, and the difference is provided from the glass substrate 30 according to the first embodiment.

[Glass substrate 35]
The glass substrate 35 is preferably formed using, for example, glass such as borosilicate glass having a thickness of 1 mm as a main material. Here, a case where the glass substrate 35 is formed of borosilicate glass is shown as an example, but the glass substrate 35 may be formed of single crystal silicon. A plurality of glass grooves 32 a are formed on the surface of the glass substrate 35.

Here, the details of the glass groove 32a which is a characteristic part of the second embodiment will be described.
On the bottom surface of the glass groove 32a, three stepped step surfaces are provided in the longitudinal direction of the glass groove 32a. The individual electrodes 31 having the same number of stepped surface portions are formed on the stepped surface portion. In the second embodiment, each step surface portion closer to the nozzle hole 11 in one row of the glass grooves 32 a corresponding to the electrode row of the individual electrode 31 (on the left side in the drawing) is located farther from the nozzle hole 11. Each step surface portion is formed shorter than each step surface portion, and in the other row (on the right side in the drawing), each step surface portion closer to the nozzle hole 11 is formed longer than each step surface portion farther from the nozzle hole 11.

  That is, the amount of ink droplets to be ejected can be set according to the column. Therefore, by making the length of the stepped portion asymmetric, the amount of ink droplets to be ejected can be adjusted while controlling the flow of ink in the ejection chamber 21. In this way, it is possible to set the usage properly according to the application of the droplet discharge head 100.

Embodiment 3 FIG.
FIG. 9 is a perspective view of the glass substrate 36 used in the droplet discharge head according to the third embodiment. In the third embodiment, differences from the first embodiment will be mainly described, and the same parts as those in the first embodiment will be denoted by the same reference numerals and description thereof will be omitted. That is, a difference is provided in the stepped surface portion formed in the glass groove 32b of the glass substrate 36, and the difference is provided from the glass substrate 30 according to the first embodiment.

[Glass substrate 36]
The glass substrate 36 is preferably formed using, for example, glass such as borosilicate glass having a thickness of 1 mm as a main material. Here, a case where the glass substrate 36 is formed of borosilicate glass is shown as an example, but the glass substrate 36 may be formed of single crystal silicon. A plurality of glass grooves 32 b are formed on the surface of the glass substrate 36.

Here, the details of the glass groove 32b, which is a characteristic part of the third embodiment, will be described.
On the bottom surface of the glass groove 32b, three stepped step surfaces are provided in the longitudinal direction of the glass groove 32b. The individual electrodes 31 having the same number of stepped surface portions are formed on the stepped surface portion. In the third embodiment, the glass grooves 32b corresponding to the electrode rows of the individual electrodes 31 are alternately provided to change the asymmetric direction one by one.

  That is, when each step surface portion closer to the nozzle hole 11 is formed shorter than each step surface portion farther from the nozzle hole 11 in one glass groove, each step surface portion closer to the nozzle hole 11 in the adjacent glass groove 11 Is formed longer than each step surface portion far from the nozzle hole 11. Therefore, it is possible to set the ejection amount of ink droplets in each of the nozzle holes 11 having a high density.

  In other words, the amount of ink droplets to be ejected can be set according to the nozzle hole 11. Therefore, by making the length of the stepped surface portion asymmetric, the amount of ink droplets to be ejected can be adjusted for each nozzle hole 11 while controlling the flow of ink in the ejection chamber 21. In this way, it is possible to set the usage properly according to the application of the droplet discharge head 100. In addition, in FIG.8 and FIG.9, an example of the shape of a glass groove was demonstrated, and it does not limit to the content demonstrated here. That is, it is possible to adjust the amount of ink droplets ejected from each nozzle hole 11 by changing the asymmetric ratio for each glass groove.

Embodiment 4 FIG.
FIG. 10 is a cross-sectional view showing a schematic configuration of a droplet discharge head 200 according to the fourth embodiment. In the fourth embodiment, differences from the first to third embodiments will be mainly described, and the same parts as those in the first to third embodiments will be denoted by the same reference numerals and the description thereof will be omitted. It shall be. That is, the individual electrodes 31 a formed on the glass substrate 37 are provided with stepped surface portions (stepped surface portions 41, 51 and 61) to control the ink flow in the discharge chamber 21.

  Therefore, the glass groove 32c formed in the glass substrate 37 can be formed with a certain depth. The individual electrode 31a is generally produced by ITO sputtering. At that time, the individual electrode 31a is produced by sputtering so as to form step surfaces (step surfaces 41, 51 and 61). That is, it is not necessary to form a stepped surface portion in the glass groove 32c, and in order to form the individual electrode 31a with a step, the step of etching the glass substrate 37 and the like can be omitted. It becomes possible to reduce.

Embodiment 5 FIG.
FIG. 11 is a perspective view showing an example of a droplet discharge device 150 on which the droplet discharge heads of Embodiments 1 to 4 are mounted. A droplet discharge device 150 shown in FIG. 11 is a general inkjet printer. The droplet discharge device 150 can be manufactured by a known manufacturing method. The droplet discharge heads obtained in the first to fourth embodiments are characterized by the glass substrate 30, the glass substrate 35, the glass substrate 36, and the glass substrate 37.

  That is, the droplet discharge heads obtained in the first to fourth embodiments are provided with stepped surfaces on the individual electrode 31 and the individual electrode 31a with which the diaphragm 22 abuts, and the diaphragm 22 has the individual electrode 31 and the individual electrode 31a. The flow of ink in the discharge chamber 21 is controlled by using an inclined surface generated when the ink is separated from the ink. The droplet discharge device 150 on which this droplet discharge head is mounted can also have the same effect, and the droplet discharge head to be mounted may be determined according to the application.

  In addition to the droplet discharge device 150 shown in FIG. 11, the droplet discharge heads obtained in Embodiments 1 to 4 can be used to manufacture various color filters for liquid crystal displays and organic EL. The present invention can also be applied to formation of a light emitting portion of a display device, discharge of a biological liquid, and the like. The droplet discharge heads obtained in Embodiments 1 to 4 can also be used in piezoelectric-driven droplet discharge devices and bubble jet (registered trademark) droplet discharge devices.

  The electrostatic actuator, the droplet discharge head, the droplet discharge device, the method for manufacturing the electrostatic actuator, the method for manufacturing the droplet discharge head, and the method for manufacturing the droplet discharge device according to the embodiment of the present invention are described above. The present invention is not limited to the contents described in the embodiment, and can be changed within the scope of the idea of the present invention. Moreover, although the case where the droplet discharge head according to the first to fourth embodiments has a three-layer structure including the glass substrate 30, the cavity substrate 20, and the nozzle substrate 10 has been described as an example, the droplet discharge head is made of glass. A four-layer structure including a substrate, a cavity substrate, a reservoir substrate, and a nozzle plate may be used.

2 is an exploded perspective view of a droplet discharge head according to Embodiment 1. FIG. It is sectional drawing which shows schematic structure of a droplet discharge head. It is explanatory drawing which shows the state which the diaphragm contact | abuts to the separate electrode. It is explanatory drawing which shows the state at the time of the diaphragm which contact | abutted to the individual electrode detach | leave. It is a longitudinal cross-sectional view which shows the manufacturing process of a glass substrate. It is a longitudinal cross-sectional view which shows the manufacturing process of a glass substrate. It is a longitudinal cross-sectional view which shows the manufacturing process of a glass substrate. It is a perspective view of the glass substrate of Embodiment 2. It is a perspective view of the glass substrate of Embodiment 3. 6 is a cross-sectional view illustrating a schematic configuration of a droplet discharge head according to Embodiment 4. FIG. It is the perspective view which showed an example of the droplet discharge apparatus carrying a droplet discharge head.

Explanation of symbols

10 Nozzle Substrate, 11 Nozzle Hole, 12 Orifice, 13 Diaphragm, 20 Cavity Substrate, 21 Discharge Chamber (Pressure Chamber), 21a Recess, 22 Vibration Plate, 23 Reservoir, 24 Insulating Film, 25 Ink Supply Hole, 27 Common Electrode Terminal, 30 glass substrate, 30a glass substrate, 31 individual electrode, 31a individual electrode, 32 glass groove, 32a glass groove, 32b glass groove, 32c glass groove, 33 lead portion, 34 terminal portion, 35 glass substrate, 36 glass substrate, 37 glass Substrate, 40 step surface portion, 40a step surface portion, 40b step surface portion, 41 step surface portion, 50 step surface portion, 50a step surface portion, 50b step surface portion, 51 step surface portion, 60 step surface portion, 61 step surface portion, 80 etching mask, 81 etching mask, 82 Etching mask, 85 ITO film, 100 droplet ejection head, 150 droplet ejection device , 200 droplet discharge head.

Claims (8)

A cavity substrate in which a bottom wall forms a vibration plate and a discharge chamber for storing and discharging droplets is formed;
A glass substrate on which an individual electrode for driving the diaphragm facing the diaphragm is formed;
A droplet discharge head comprising a nozzle substrate on which nozzle holes for discharging droplets transferred from the discharge chamber are formed,
The individual electrodes are:
The flat surface has an elongated shape, and is formed with a plurality of step surfaces stepwise from the intermediate portion toward both ends in the longitudinal direction, with the middle portion of the plane being the lowest step surface. A droplet discharge head characterized in that the length in the longitudinal direction of the step surface having the same height in the stepped step surface is asymmetric. A glass groove for installing the individual electrode on the glass substrate is provided,
In the glass groove, a plurality of step surfaces are formed stepwise from the intermediate portion toward both ends in the longitudinal direction, with the intermediate portion of the plane being the lowest step surface, and two steps toward the both ends of the individual electrode The droplet discharge head according to claim 1, wherein the lengths in the longitudinal direction of the step surfaces having the same height in the shape step surface are asymmetric. 3. The liquid according to claim 1, wherein an asymmetry of the length in the longitudinal direction of the step surfaces having the same height in the two stepped step surfaces facing the both ends can be set for each of the individual electrodes. Drop ejection head. A droplet discharge apparatus comprising the droplet discharge head according to claim 1. A cavity substrate having a bottom wall forming a vibration plate to form a discharge chamber for collecting and discharging droplets, and a glass substrate on which an individual electrode for driving the vibration plate is formed facing the vibration plate. Bonding with a gap between the plate and the individual electrodes;
A method of manufacturing a droplet discharge head for bonding a nozzle substrate formed with a nozzle hole for discharging a droplet transferred from the discharge chamber to the cavity substrate,
A glass groove for installing the individual electrode on the glass substrate is provided,
The individual electrode is provided with a plurality of step surfaces in a staircase shape from the intermediate portion toward both ends in the longitudinal direction, with the middle portion of the plane being the lowermost step surface, and two steps toward the both ends. A method for manufacturing a droplet discharge head, wherein the lengths in the longitudinal direction of stepped surfaces having the same height on the stepped surface are asymmetric. In the glass groove, a plurality of step surfaces are formed stepwise from the intermediate portion toward both ends in the longitudinal direction, with the intermediate portion of the plane being the lowest step surface, and two steps toward the both ends of the individual electrode The length in the longitudinal direction of the step surface of the same height in the shape step surface is asymmetric
The method of manufacturing a droplet discharge head according to claim 5. The method for manufacturing a droplet discharge head according to claim 5, wherein the individual electrodes are formed by sputtering. A method for manufacturing a droplet discharge device, comprising the method for manufacturing a droplet discharge head according to any one of claims 5 to 7.

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