JP3218664B2 - Inkjet print head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an on-demand type ink jet print head which forms an image on a recording medium by causing ink in a pressure generating chamber to fly from nozzle openings as ink droplets.

[0002]

2. Description of the Related Art Conventionally, as an example in which a silicon wafer is used as a substrate material for forming an ink flow path in an ink jet print head, there is a thermal ink jet head disclosed in, for example, JP-A-2-265754.
This head bonded an anisotropically etched ink supply port of a through recess and a first substrate having an ink channel formed of a plurality of parallel narrow grooves, and a second substrate having a heating element and an addressing electrode. Thereafter, a nozzle is formed on the end face of the substrate by cutting at a predetermined position, and a pressure is generated by the heating element to discharge an ink droplet from the nozzle. A method of forming a nozzle opening by anisotropic etching of a silicon wafer is one of widely used nozzle forming techniques as disclosed in, for example, Japanese Patent Application Laid-Open No. 58-112755. .

[0003]

However, in the above-mentioned prior art, a plurality of members are adhered to each other by bonding, and a nozzle is formed by cutting, or a nozzle opening is formed. In general, an ink jet print head is formed by bonding a substrate on which is formed, a substrate on which an ink flow path is formed, and a top plate to each other. Therefore, in the conventional technology, the manufacturing process is complicated to secure the accuracy of a plurality of parts and the accuracy of assembly. In particular, when the nozzle is formed by cutting, chips such as chipping are likely to be generated. There is a limit. Further, the use of the adhesive has a problem that it is difficult to ensure reliability such as an outflow of the adhesive into the ink flow path, insufficient adhesive strength, and anticorrosiveness of the ink.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to simplify the manufacturing process and to easily ensure the shape accuracy, and to provide a highly reliable and highly durable product. The present invention provides an ink jet print head.

[0005]

According to the present invention, there is provided an ink jet print head comprising a nozzle opening, a pressure generating chamber communicating with the nozzle opening, an ink supply path communicating with the pressure generating chamber, and one of the pressure generating chambers. In an ink jet print head including a vibration plate forming a wall surface and a pressure generation element formed at a position of the vibration plate facing the pressure generation chamber, the pressure generation chamber and the ink supply forming an ink flow path are provided. A flow path substrate formed of a silicon single crystal substrate in which a passage and the nozzle opening are integrally formed, and a diaphragm in which a silicon compound is formed on a surface of a metal material having substantially the same thermal expansion coefficient as the silicon single crystal substrate. Wherein the flow path substrate and the surface on which the silicon compound is formed of the vibration plate are joined without interposing an adhesive layer.

[0006]

According to the above construction of the present invention, the shape required for the ink flow path constituting portion of the ink jet print head is formed in a single member by the same manufacturing process, thereby shortening the manufacturing process and reducing the ink flow path structure. It is possible to improve the shape accuracy of the portion.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the illustrated embodiments.

FIG. 1 is an exploded perspective view showing the structure of an ink jet print head according to an embodiment of the present invention, and FIG. 2 is a perspective view of a flow path substrate. A flow path substrate 1 having an ink flow path formed therein,
A diaphragm 2 having the same coefficient of thermal expansion as the flow path substrate 1, a strip-shaped or comb-shaped piezoelectric element 3 constituting a pressure generating element, a lead electrode 4 for transmitting a print signal to the piezoelectric element 3, and a print head for printing ink And an ink supply pipe 5 for supplying the ink to the ink supply pipe. The ink (not shown) supplied from the ink supply pipe 5 is filled into a plurality of pressure generating chambers 7 arranged in parallel from a reservoir 9 through an ink supply port 8. When a print signal is applied to the lead electrode 4, distortion occurs in the piezoelectric element 3 and the diaphragm 2
When the pressure is applied to the pressure generating chamber 7, the ink droplets can be ejected from the nozzle openings 6.

The ink flow path includes a nozzle opening 6, a pressure generating chamber 7, an ink supply port 8, and a reservoir 9. Here, the material of the flow path substrate 1 has a thickness of 200 to 5
Using a silicon single crystal substrate of 00 μm,
The {100} crystal plane is provided on the substrate surface, and all the ink flow paths are formed by anisotropic etching along the {111} crystal plane. Therefore, the nozzle opening 6 has an inner wall of 4
The pressure generating chamber 7 and the reservoir 9 are formed as a through hole having a pyramid shape, the depth thereof is the same as that of the pressure generating chamber 7, and the cross section forms a trapezoidal concave portion. The ink supply port 8 communicates with each pressure generating chamber 7 from the reservoir 9. The cross section is formed as a V-shaped groove at the position where it is. Here, the shape of the ink supply port 8 is not limited to the V-shaped groove, and may be a trapezoidal groove similar to the pressure generating chamber 7. However, due to the design of the ink flow path, the fluid resistance of the ink supply port 8 is substantially equal to that of the nozzle opening 6, and it is required that the fluid resistance of the pressure generating chamber 7 be sufficiently large. The cross-sectional area of the channel 8 is the pressure generating chamber 8
It must be set to be sufficiently smaller than that of.
In addition, since the ink flow path is anisotropically etched along the {111} crystal plane, the taper angle in each ink flow path cross section is 54.5 which is peculiar to silicon single crystal with respect to the {100} crystal plane on the substrate surface. It makes an angle of 7 °.

FIG. 3 shows a process of forming the ink flow path described with reference to FIG. First, a silicon single crystal substrate of $ 10
0.5 mm on the upper and lower surfaces of the crystal plane by thermal oxidation treatment in an oxygen atmosphere at 1000-1200 ° C.
After the i-oxide film 13 is formed, a photoresist is coated, and the nozzle opening pattern is exposed and developed. Next, when the Si oxide film is removed with a hydrofluoric acid aqueous solution, FIG.
(A), the {100} crystal plane of the silicon single crystal substrate is exposed as a nozzle opening pattern. So, KOH
First anisotropic etching is performed using an anisotropic etching solution such as an aqueous solution until the remaining thickness of the silicon single crystal substrate becomes a thickness corresponding to the depth of the pressure generating chamber 7 with respect to the total thickness of the silicon single crystal substrate. The recess 1a as shown in FIG. 3 (b) is formed. Subsequently, after the pressure generating chamber 7 and the ink supply port 8 pattern are formed in the photoresist by the same method as described above, the Si oxide film is removed (FIG. 3C). Further, by performing the second anisotropic etching, the nozzle opening 6 penetrates at the same time,
Ink flow paths other than the nozzle openings 6 are formed as recesses,
An ink flow path shape as shown in FIG. 3D can be obtained. Here, if the pattern width of the ink supply port 8 is set sufficiently small with respect to the etching depth, the {111} crystal planes intersect because the anisotropic etching is etched along the {111} crystal plane. At this point, the etching stops, and the ink supply port is formed as a V-shaped groove. Therefore, the pressure generating chamber 7 and the ink supply port 8 can be formed simultaneously by one etching process, even though the etching depth is different.

Therefore, as shown in FIG. 2, the width of the pressure generating chamber 7 is made equal to the opening length of the nozzle inlet 11, and the ink supply ports 8 are arranged at two locations on the same wall extension of the pressure generating chamber wall 10. Then, by forming so as to form a V-shaped groove,
The plurality of ink flow paths excluding the reservoir 9 are regularly arranged in parallel and can form an ink flow path having no discontinuity such as a step on each ink flow path wall. Therefore, the ink supplied from the reservoir 9 to each of the ink supply ports 8 reaches the nozzles by a smooth flow without generation of stagnation or stagnation.

Since the nozzle opening 6 and the pressure generating chamber 7 are formed to communicate with each other by two anisotropic etchings, the first
In a portion where the wall surface of the nozzle opening formed by the anisotropic etching described above overlaps with the wall surface of the pressure generating chamber formed by the second anisotropic etching, a new crystal plane is exposed and a notched wall surface 12 is formed. There is no problem on the function of the ink jet print head.

FIG. 4 shows a cross section of the ink jet print head of this embodiment. The vibration plate 2 having the same thermal expansion coefficient as the flow path substrate 1 is joined to the flow path substrate 1 in which the ink flow path is formed, and the ink flow path is completed. Here, Pyrex glass having a thickness of 20 to 100 μm is used as a material of the diaphragm 2. The flow path substrate 1 and the vibration plate 2 are overlapped and fixed, and both substrates are heated at an ambient temperature of 200 to 500 ° C. Then, when a DC voltage of 200 to 1000 V is applied between the two substrates, a current flows at the same time as the bonding interface comes into close contact due to electrostatic attraction, and the two substrates are strongly bonded. As described above, since the bonding surface between the flow path substrate 1 and the vibration plate 2 can be bonded without the interposition of an organic compound such as an adhesive, extremely high dimensional accuracy can be obtained even in a complicated fine shape. .

The bonding surface of the vibration plate 2 to the piezoelectric element 3 has S
An n-oxide or ITO (In ₂ O ₅ —SnO ₂ ) is formed as a thin film as a lead electrode, and is electrically connected to a print signal source set outside.

As the material of the diaphragm 2, a silicon single crystal, a Si compound, or a metal material having a Si compound formed on the surface can be used. It is also possible to use a 42 alloy (Fe-Ni alloy) having a thermal expansion coefficient equal to that of a silicon single crystal as a metal material. In this case, a thin film of Si oxide is formed in advance on the surface by sputtering or the like. There is a need. The 42 alloy Si oxide forming surface was placed on the flow path substrate 1
Then, both substrates can be joined by the same method as described above, and a strong joining force can be obtained. The 42 alloy is a conductive material and can be used as a common electrode.
Will be connected to the upper surface.

[0016]

According to the ink jet print head of the present invention, the nozzle opening, the pressure generating chamber communicating with the nozzle opening, the ink supply path communicating with the pressure generating chamber, and one wall surface of the pressure generating chamber are formed. In the ink jet print head comprising a vibrating plate to be configured and a pressure generating element formed at a position of the vibrating plate facing the pressure generating chamber, the pressure generating chamber and the ink supply path forming an ink flow path A flow path substrate formed of a silicon single crystal substrate integrally formed with the nozzle opening, and a diaphragm in which a silicon compound is formed on a surface of a metal material having substantially the same thermal expansion coefficient as the silicon single crystal substrate. Since the flow path substrate and the silicon compound forming surface of the vibration plate are joined without using an adhesive layer, a vibration plate simply formed from a silicon single crystal substrate is used. Compared to the case, the use of a metal material prevents problems such as breaking of the diaphragm, and the metal material of the diaphragm is substantially equivalent to the silicon single crystal substrate forming the flow path substrate. Since it has a thermal expansion coefficient, it is possible to prevent poor joining that occurs when a heating step is used when joining the flow path substrate and the diaphragm.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a configuration of an ink jet print head of the present invention.

FIG. 2 is a perspective view illustrating an appearance of a flow path substrate.

FIGS. 3A to 3D are diagrams illustrating a process of forming an ink flow path of a flow path substrate.

FIG. 4 is a partial cross-sectional view of the inkjet print head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Flow path board 2 Vibration plate 3 Piezoelectric element 4 Lead electrode 5 Ink supply pipe 6 Nozzle opening 7 Pressure generating chamber 8 Ink supply port 9 Reservoir

Claims (1)

(57) [Claims] 1. A nozzle opening, a pressure generating chamber communicating with the nozzle opening, an ink supply path communicating with the pressure generating chamber, a diaphragm constituting one wall surface of the pressure generating chamber, An ink jet print head comprising a pressure generating element formed at a position facing the pressure generating chamber, wherein the pressure generating chamber forming an ink flow path, the ink supply path, and the nozzle opening are integrally formed with silicon. A flow path substrate composed of a single crystal substrate; and a diaphragm in which a silicon compound is formed on a surface of a metal material having substantially the same thermal expansion coefficient as the silicon single crystal substrate. An ink jet print head, wherein the surface of the substrate is bonded to the surface on which the silicon compound is formed without interposing an adhesive layer.