JP3741804B2 - Inkjet recording head - Google Patents

Description

[0001]
[Field of the Invention]
The present invention relates to an ink jet recording head in which a part of a pressure generation chamber communicating with a nozzle opening is expanded and contracted by an actuator that flexures and vibrates to discharge ink droplets from the nozzle opening.
[0002]
[Prior art]
The ink jet recording head has a piezoelectric vibration type that pressurizes ink by mechanically deforming a pressure generation chamber, and a heating element provided in the pressure generation chamber, and ink is applied by pressure of bubbles generated by heat of the heating element. There are two types, a bubble jet type that pressurizes. Piezoelectric vibration type recording heads are further classified into two types: a first recording head using a piezoelectric vibrator that is displaced in the axial direction and a second recording head using a piezoelectric vibrator that is flexibly displaced. .
[0003]
The first recording head can be driven at a high speed and can be recorded at a high density. On the other hand, the processing of the piezoelectric vibrator is accompanied by a cutting operation, or is fixed when the piezoelectric vibrator is fixed to the pressure generating chamber. There is a problem that the number of manufacturing steps increases because of the need for a dimensional assembly work. On the other hand, the second recording head has a piezoelectric vibrator in the form of a film, so that it can be fired integrally with the elastic film constituting the pressure generating chamber, thereby simplifying the manufacturing process. Although it has a feature that it can be achieved, it requires an area that can bend and vibrate, and therefore has a problem that the width of the pressure generating chamber is increased and the arrangement density is lowered.
[0004]
In order to overcome the problems of a recording head using such flexural vibration, for example, in Japanese Patent Application Publication No. 5-504740, a silicon single crystal substrate having a lattice plane (110) is anisotropically etched to perform pressure. A flow path forming unit in which a generation chamber, an ink supply port, and a reservoir are formed, and a nozzle plate in which a plurality of nozzle openings communicating with the pressure generation chamber are formed. The other surface of the flow path forming unit is elastically deformed by silicon oxide. An ink jet recording head configured as a possible membrane has been proposed.
[0005]
According to this, since a main member can be formed by etching, a recording head having a high printing density can be manufactured with a high yield.
[0006]
[Problems to be solved by the invention]
However, because the silicon single crystal substrate is etched from one side and the other side is left to form the partition wall, the wall constituting the reservoir has high rigidity, and ink supply to the pressure generating chamber is insufficient. Or crosstalk.
In order to solve such problems, it may be possible to selectively thin the elastic plate in the region facing the reservoir. However, since the reservoir has a relatively large area, the strength of the elastic plate is reduced and durability is reduced. New problems occur.
The present invention has been made in view of such problems, and the object of the present invention is to use a silicon single crystal substrate that can ensure sufficient compliance in the reservoir without lowering the strength of the exposed surface. An ink jet recording head is provided.
[0007]
[Means for Solving the Problems]
In order to solve such a problem, in the present invention, a pressure generation chamber for ejecting ink droplets from the nozzle opening, a reservoir for receiving ink supply from the outside, and a pressure generation means for pressurizing the pressure generation chamber, the ink jet recording head at least the reservoir is formed by anisotropic etching of the silicon single crystal substrate, the reservoir, in a direction crossing the arrangement direction of the pressure generating chamber, and the reservoir-side from the pressure generating chamber side continuously extending partition walls are placed at predetermined intervals in the arrangement direction of the pressure generating chamber, said partition wall, a wall is elastically deformed by the pressure of the ink flowing back to the reservoir from the pressure generating chamber, wherein It is comprised by the hollow part pinched | interposed by the wall.
[0008]
[Action]
When the pressure in the reservoir rises due to ink droplet ejection, the wall of the partition is bent and absorbs the pressure.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Therefore, details of the present invention will be described below based on the illustrated embodiments.
FIG. 1 is an assembled perspective view showing an embodiment of the present invention, and FIG. 2 is a view showing a cross-sectional structure in the longitudinal direction of one pressure generating chamber. An actuator unit 1 that pressurizes ink in the pressure generating chamber 11 by a generating unit, and a flow path that includes a nozzle opening that supplies ink to the actuator unit 1 and discharges the ink pressurized in the pressure generating chamber 11 as ink droplets. A forming unit 2 and an ink supply port forming substrate 3 for joining these two members are configured.
[0010]
The actuator unit 1 has a pressure generating chamber 11 formed as a recess whose opening side is expanded and the other surface is sealed by an elastic plate 12 at a constant pitch, and is opposed to the pressure generating chamber 11 of the elastic plate 12. In this embodiment, a pressure generating means, in this embodiment, a piezoelectric vibrator 13 made of a piezoelectric vibrating body film formed by a thin film method is formed.
[0011]
The flow path forming unit 2 forms a guide path 21 and a reservoir 22 communicating with the end of the pressure generation chamber 11 so that the end faces thereof substantially coincide with one end of the pressure generation chamber 11, in this embodiment, the side portion. A nozzle communication hole 23 communicating with each pressure generating chamber 11 independently and a nozzle opening 24 are formed so as to be located on the other end side of the nozzle.
[0012]
Both ends 21a of the guide path 21 are extended to the side where the pressure generating chamber 11 is not located, and the reservoir 22 is positioned in a region where the pressure generating chamber 11 is located so that ink does not flow as shown in FIG. A partition wall 25 composed of two walls 25b each having a hollow portion 25a is formed at a predetermined interval.
[0013]
The ink supply port forming substrate 3 has an ink supply port 31 at a position facing one slope 11 a of the opening of the pressure generation chamber 11 and a nozzle communication hole 32 at a position facing the other slope 11 b of the pressure generation chamber 11. Further, an ink introduction port 33 for supplying ink from the outside is provided at a position where the pressure generation chamber 11 is not located and is opposed to the end portion 21a of the guide path 21.
[0014]
The ink supply port forming substrate 3 is made of a metal made of a metal having a higher elasticity than the silicon single crystal substrate, such as a non-rust steel, and having a corrosion resistance against the ink. Has been.
[0015]
In this embodiment, when a signal is applied from an external drive circuit to the piezoelectric vibrator 13, the piezoelectric vibrator 13 is deflected to reduce the volume of the pressure generating chamber 11.
[0016]
A portion of the ink pressurized by the reduction of the pressure generating chamber 11 passes from the nozzle opening 24 via the nozzle communication hole 32 of the ink supply port forming substrate 3 and the nozzle communication hole 23 of the flow path forming unit 2. It is ejected as ink droplets.
[0017]
When the ejection of the ink droplets is completed and the piezoelectric vibrator 13 returns to the original state, the pressure generation chamber 11 expands, and the ink in the reservoir 22 passes through the ink supply port 31 of the ink supply port forming substrate 3. 11 to prepare for the discharge of the next ink droplet.
[0018]
By the way, when the pressure generating chamber 11 contracts and the ink in the pressure generating chamber 11 is pressurized, ink other than the ink droplets discharged from the ink supply port 31 flows into the reservoir 22 to increase the pressure here.
[0019]
Due to this pressure increase, the walls 25b, 25b constituting the partition wall 25 formed relatively thin bends toward the hollow portion 25a, absorbs the increased pressure, and does not discharge ink droplets. Prevents pressure fluctuations from propagating to the surface.
[0020]
This prevents the phenomenon that ink droplets are ejected from the nozzle opening 24 of the pressure generating chamber 11 to which no drive signal is applied, that is, the occurrence of so-called crosstalk, and provides compliance for supplying ink to the pressure generating chamber 11.
[0021]
Next, a manufacturing method of the actuator unit described above will be described with reference to FIG. A base material 43 in which SiO 2 layers 41 and 42 of about 1 μm are formed on at least the front and back surfaces of the silicon single crystal substrate 40 whose surface is cut out at (110) is prepared by a thermal oxidation method or the like. The SiO2 layer 41 formed on the etching surface side (lower surface in the drawing) functions as an etching protective film, and the SiO2 layer 42 on the driving surface (upper surface in the drawing) is the piezoelectric vibrator 13 formed thereon. The insulating film and the elastic film 12 function (FIG. 4I).
[0022]
A platinum (Pt) film having a thickness of about 0.2 to 0.8 .mu.m is formed by sputtering on the surface of the SiO2 layer 42 to be a non-etched surface, and a lower electrode 44 is sputtered on the surface and a piezoelectric material such as PZT is sputtered. A piezoelectric film 45 having a thickness of 1.0 μm is formed by a film forming method such as the above, and annealing treatment is performed at a predetermined temperature for a predetermined time with infrared light (FIG. 4 (II)).
[0023]
After the annealing treatment, the piezoelectric film 45 is trimmed corresponding to the region to be the pressure generation chamber 11 and formed as a piezoelectric vibrator 13 that can be displaced independently for each pressure generation chamber 11 (FIG. 4 (III)).
[0024]
A photoresist layer is formed in accordance with the arrangement direction of the pressure generating chambers 11, and the SiO2 layer 41 on the etching surface is removed using a buffered hydrofluoric acid solution in which hydrofluoric acid and ammonium fluoride are mixed at a ratio of 1: 6. Then, the window 46 corresponding to the opening side of the pressure generating chamber 11 is patterned (FIG. 4 (IV)).
[0025]
When the base material 43 is immersed in a 10% potassium hydroxide solution heated to about 80 ° C. and anisotropic etching is performed until the base material 43 reaches the other SiO 2 layer 42, a recess 47 serving as the pressure generating chamber 11 is formed. When the SiO2 layer 41 on the joining surface side is removed as necessary, the actuator unit is completed.
[0026]
Next, the manufacturing method of a flow path formation unit is demonstrated based on FIG.
A base material 53 in which SiO 2 layers 51 and 52 of about 1 μm are formed on at least the front and back surfaces of the silicon single crystal substrate 50 whose surface is cut out at (110) is prepared by a thermal oxidation method or the like (FIG. 5 (I)).
[0027]
A photoresist layer is formed at a position where the guide path 21, the reservoir 22, the nozzle communication hole 23, and the partition wall 25 are to be formed, and a buffer fluoride in which hydrofluoric acid and ammonium fluoride are mixed at a ratio of 1: 6. The SiO2 layer 51 on the etched surface is removed using an acid solution to pattern the windows 54, 55, and 56 to form the guide path 21, the reservoir 22, the nozzle communication hole 23, and the hollow portion 25a of the partition wall 25 (see FIG. 5 (II)).
[0028]
The base material 53 is immersed in a 10% potassium hydroxide solution heated to about 80 ° C., and anisotropic etching is performed to an optimum depth as a reservoir. As a result, recesses 57 and 58 to be the guide path 21 and the nozzle communication hole 23 are formed (FIG. 5 (III)), and a recess 59 to be the reservoir 22 is formed together with the partition wall 25 (FIG. 5 (III ′)).
[0029]
When a hole 60 having a diameter suitable for the nozzle opening 24 is formed by dry etching or the like in alignment with the tip of the concave portion 58 to be the nozzle communication hole 23, the SiO2 layer 52 on the joint surface side is removed as necessary. Then, the flow path forming unit is completed (FIG. 5 (IV)).
[0030]
The actuator unit 1, the ink supply port forming substrate 3, and the flow path forming unit 2 thus configured are stacked via an adhesive layer and heated to a temperature suitable for bonding, for example, 60 to 200 ° C. Then, pressurize with a predetermined pressure to bond.
[0031]
When the bonding is completed and the temperature is returned to room temperature, the difference in thermal expansion between the silicon constituting the actuator unit 1 and the flow path forming unit 2 and the metal constituting the ink supply port forming substrate 3 is different. The resulting stress acts on each joint surface, but the ink supply port forming substrate 3 absorbs it by its own elasticity.
[0032]
In the above-described embodiment, the piezoelectric vibrator is formed by the film forming method. However, the same thing can be said even if a piezoelectric material is formed by attaching a green sheet of piezoelectric material and firing it. It is clear that there is an effect.
[0033]
【The invention's effect】
As described above, according to the present invention, regardless of the rigidity of the outer wall, the pressure increase in the reservoir due to the ink flowing backward by ink droplet ejection can be reliably absorbed by the deformation of the partition wall. .
[Brief description of the drawings]
FIG. 1 is an assembled perspective view showing an embodiment of a recording head of the present invention.
FIG. 2 is a diagram showing a cross-sectional structure of one pressure generating chamber according to an embodiment of the recording head of the present invention.
FIG. 3 is an enlarged view showing a partition formed in a reservoir.
FIGS. 4 (I) to (V) are diagrams showing a method of manufacturing an actuator unit, respectively.
FIGS. 5 (I) to (IV) are diagrams showing a method for manufacturing a flow path forming unit, respectively.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Actuator unit 2 Flow path formation unit 3 Ink supply port formation board | substrate 11 Pressure generation chamber 12 Elastic plate 13 Piezoelectric vibrator 21 Guide path 22 Reservoir 23 Nozzle communication hole 24 Nozzle opening 25 Partition 25a Hollow chamber 25b Wall 31 Ink supply port 32 Nozzle Communication hole 33 Ink introduction port

Claims (2)

A pressure generation chamber for discharging ink droplets from the nozzle opening; a reservoir for receiving ink supply from the outside; and a pressure generation means for pressurizing the pressure generation chamber. At least the reservoir is formed by anisotropic etching of a silicon single crystal substrate. In the formed inkjet recording head,
Said reservoir, said in a direction crossing the arrangement direction of the pressure generating chambers, and distribution at predetermined intervals in the arrangement direction of the partition wall extending continuously in the reservoir side from the pressure generating chamber side is the pressure generating chamber Placed,
The partition walls, the pressure on the wall of the elastic deformation of the ink flowing back to the reservoir from the pressure generating chamber, an ink jet recording head is constituted by a hollow portion sandwiched by the wall. A silicon single crystal substrate having pressure generating chambers formed on one surface as concave portions sealed by an elastic plate at a constant pitch, and having pressure generating means at positions facing the pressure generating chambers of the elastic plate; An actuator unit formed by anisotropic etching of
An ink supply port that is communicated at one end of the pressure generation chamber, a nozzle communication hole that is communicated at the other end of the pressure generation chamber, and an ink supply port forming substrate made of a metal material;
A flow path forming unit formed by anisotropic etching of a silicon single crystal substrate, having a reservoir communicating with one end of the pressure generating chamber and a nozzle opening communicating with the other end of the pressure generating chamber;
In an ink jet recording head configured by laminating and bonding ,
Said reservoir, said in a direction crossing the arrangement direction of the pressure generating chambers, and distribution at predetermined intervals in the arrangement direction of the partition wall extending continuously in the reservoir side from the pressure generating chamber side is the pressure generating chamber Placed,
The partition walls, the pressure on the wall of the elastic deformation of the ink flowing back to the reservoir from the pressure generating chamber, an ink jet recording head is constituted by a hollow portion sandwiched by the wall.

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