JP2006082250A - Inkjet head and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a long-life inkjet head by suppressing an aged deterioration in ink ejection characteristics, which is caused by an increase in channel resistance inside a head. <P>SOLUTION: This inkjet head comprises an ink chamber which communicates with an ink channel, a plurality of nozzles which communicate with the ink chamber, a diaphragm which constitutes a part of the ink chamber, and an ink-chamber pressurizing means which is provided in the position, facing the ink chamber, of the diaphragm. The inkjet head makes the ink-chamber pressurizing means change internal pressure of the ink chamber, and makes ink ejected from the nozzle. The inkjet head is provided with a filter which is arranged in a channel, and the filter is composed of a plurality of protrusions and microporous filters which are formed among the plurality of protrusions. In this invention, a manufacturing method for the inkjet head is also disclosed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ink jet head used in an ink jet printer, and more particularly to an on-demand ink jet head and a manufacturing method thereof.

  In general, an ink jet head is configured to eject ink from a nozzle by introducing ink into the head and driving a piezoelectric element or the like to apply a pressure fluctuation to a pressure chamber into which the ink has been introduced. In such an ink jet head, if foreign matter is present in the supplied ink, the nozzles are clogged, resulting in ejection failure. In addition, air bubbles present in the ink also cause ejection failure because the flow of ink is hindered or pressure applied by a piezoelectric element or the like is absorbed. For this reason, a filter that normally has a plurality of fine holes in the ink supply path and removes foreign matters and bubbles in the ink is attached.

  As this filter, conventionally, a filter having a structure in which fibers or metal wires are woven to make a filter hole is used, and foreign matters and bubbles are removed when ink passes through the filter hole. However, since the filter of this structure cannot make the fiber so thin, when the filter hole is made small, the aperture ratio becomes small. As a result, the pressure loss when the ink flows is increased, and the discharge performance is lowered. There is a problem.

  As a method for increasing the aperture ratio, Patent Document 1 discloses a method in which a nickel plate having round holes formed by electroforming is used as a filter. According to this proposal, the filter has an aperture ratio of about 30%, and a filter that does not significantly affect the pressure loss of the ink flow can be manufactured.

JP 11-291514 A

  In the conventional filter, since relatively coarse dust sticks to the filter surface, there is a problem that the substantial aperture ratio of the filter decreases as the head is used, and the head characteristics also deteriorate.

  An object of the present invention is to provide an inkjet head including a long-life filter in which a hole through which ink flows is formed to be small and an increase in flow resistance due to adhesion of dust is suppressed.

  In order to achieve the above object, the present invention provides an ink chamber that communicates with an ink flow path, a plurality of nozzles that communicate with the ink chamber, a diaphragm that forms part of the ink chamber, and an ink chamber of the diaphragm. The present invention is intended for an ink jet head that includes ink chamber pressurizing means provided at opposed positions, in which the ink chamber pressure is changed by the ink chamber pressurizing means, and ink is ejected from the nozzles.

  In the flow path, for example, a filter is formed of silicon, and the filter is formed by integrally forming a relatively coarse first filter and a fine second filter. is there. Furthermore, in the above-described ink jet head, the first filter is formed with a communication path for ensuring the ink flow to the second filter. As the nozzle diameter of the head has been reduced with the recent high definition of printing, the diameter of the filter hole needs to be made smaller and smaller, such as 5 μm to 10 μm. There are cases where it is impossible to cope with the limitation of the patterning resolution. There is also a problem that nickel is attacked when the liquid to be discharged is a solvent or a corrosive liquid. However, the filter using silicon in the embodiment of the present invention does not have such a problem.

  In the present invention, the hole or the recess formed in the relatively coarse first filter has a bottom, and a micropore constituting the second filter is formed in the bottom. The holes or recesses may be independent, or the holes or recesses may be connected by a communication groove. Moreover, not a so-called hole but a parallel or non-parallel protrusion may be used. A bottom is formed between the protrusions, and a micropore is formed in the bottom. In addition, the hole formed as a 2nd filter is called a micropore in this specification. Micropores are formed at the bottom of the first filter, such as between the projections, between the holes or between the parallel projections.

  According to the present invention, since the first filter reliably captures large foreign matter in the ink and does not form a state where the foreign matter is blocked by the foreign matter, the increase in flow resistance is minimized. It can be suppressed to the limit.

  Next, the best mode for carrying out the ink jet head according to the present invention will be described with reference to the drawings. The main embodiments of the present invention are as follows.

  (1) The above-mentioned filter is an inkjet head in which a first filter having a relatively coarse mesh and a fine second filter formed inside the first filter are integrated.

  (2) The ink jet head in which the first filter has a large number of cells, and the second filter has a large number of micropores formed in the cells.

  (3) The first filter is constituted by a plurality of parallel or non-parallel protrusions, and the second filter is an ink-jet head constituted by a large number of micropores formed between the parallel or non-parallel protrusions.

  (4) The ink jet head, wherein the first filter includes a large number of holes and grooves communicating between the holes, and the second filter includes a large number of micro holes formed in the holes.

  (5) SOI (Silicon On Insulator) substrate in which a silicon substrate, a stopper layer, and an active layer (used as a functional layer of a device and generally have a thickness of several μm to several tens of μm) are stacked and integrated. Forming a first silicon oxide film on the substrate surface; patterning the first silicon oxide film to form a pattern to be a first filter of an internal filter; forming a mask material on the pattern; Etching the pattern to be the first filter using a material; after removing the mask material, etching the pattern up to the stopper layer; forming a second silicon oxide film on the active layer surface; Patterning the oxide film to form a pattern to be a micropore of the second filter; removing the stopper layer; Method of manufacturing the ink jet head.

  (6) forming a second silicon oxide film on the active layer surface of the SOI substrate in which a silicon substrate, a stopper layer and an active layer are laminated and integrated; patterning the second silicon oxide film to form micropores in the second filter Forming a pattern; forming a first silicon oxide film on the substrate surface; patterning the first silicon oxide film to form a pattern to be a first filter of an internal filter; and applying a mask material on the pattern Forming and etching the pattern to be the first filter using the mask material; after removing the mask material, etching the pattern up to the stopper layer; removing the stopper layer; Production method.

  (7) The SOI substrate includes a region of a diaphragm portion and an internal filter portion. In the diaphragm portion, after the second silicon oxide film is formed on the active layer, the stopper layer is removed without patterning. The method of manufacturing an ink jet head, wherein the diaphragm is formed by removing the silicon oxide film.

  1 is a perspective view of an inkjet head 1 according to the present embodiment, FIG. 2 is an exploded perspective view of the inkjet head 1, and FIG. 3 is a cross-sectional view showing a flow path configuration corresponding to one nozzle of the inkjet head 1. Is. As shown in FIG. 2, the inkjet head 1 is roughly composed of a drive unit 100 and a flow path unit 101.

  The flow path unit 101 includes an orifice plate 3 having a nozzle 2, a chamber plate 5 having a pressure chamber 4, a diaphragm plate 8 having an internal filter 6 and a diaphragm 7 for preventing dust from entering the flow path, and a flow path. It is composed of a reinforcing plate 9 for reinforcing. In this embodiment, all of the diaphragm plate 8, the nozzle plate 3 and the chamber plate 5 having the internal filter 6 are formed by etching of silicon.

  The drive unit 100 includes a flexible cable (FPC) 13 that is electrically connected to the outside such as a power source and a control device, a relay member 10 corresponding to the ink chamber 4, a piezoelectric vibrator 11, a support substrate 12, and the like. The piezoelectric vibrator 11 is bonded to the end of the support substrate 12.

  As shown in FIG. 3, the ink is introduced from the ink supply port 14, passes through the internal filter 6, and reaches the pressure chamber 4 through the restrictor 15 that controls the flow rate of the ink. One wall of the pressure chamber 4 is bonded to the piezoelectric vibrator 11 to be a diaphragm 7 that vibrates in response to the displacement of the piezoelectric vibrator 11, and pressure fluctuations are generated in the pressure chamber 4 due to the vibration of the diaphragm 7, Ink is ejected from the nozzle 2.

  Here, a perspective view of the internal filter 6 according to the present invention is shown in FIG. In order to catch relatively coarse dust, this filter is integrally formed with a first filter 16 having a mesh or mesh shape with a side of about 50 μm and a second filter 17 having many micropores with a diameter of about 5 μm. . An enlarged perspective view of the internal filter 6 is shown in FIG. The first filter 16 has a communication groove 18 formed between the ribs. As is apparent from FIGS. 4 and 5, the first filter has a large number of continuous or discontinuous protrusions, and its height is high. The height is higher than the surface of the second filter having micropores. As a result, as shown in FIG. 6, when coarse dust 19 adheres to the filter, the fine holes of the second filter are not blocked by the dust, and the ink can pass through the fine holes. Ink can be flowed through the communication groove 18 to suppress an increase in channel resistance.

  The filter according to the present invention has no non-uniformity due to the position as a filter function, can capture coarse dust at any position, and can catch fine dust without escaping from the filter. If the first filter with coarse eyes and the second filter with fine eyes exist separately on the filter surface, the ink flows to the first filter with coarse flow having low flow resistance and is originally captured by the second filter. There is a risk that fine dust should pass through the first filter, but this is not the case with the present invention. In addition, since the protrusion of the first filter is higher than the surface of the second filter, there is an effect that coarse dust does not adhere to the second filter surface, and therefore the second filter is less likely to be clogged. .

  In the present embodiment, the internal filter 6 is formed by dry etching. A method for manufacturing the internal filter 6 will be described below.

A cross-sectional view of the SOI substrate 201 used in this embodiment is shown in FIG. This SOI substrate is a substrate for manufacturing the internal filter 6. The thickness of the support layer 202 was 550 μm, and the thickness of the active layer 203 was 3 μm. The plane orientation is (100). The stopper layer 204 is a 1 μm thick SiO ₂ layer. An etching process of the SOI substrate 201 will be described with reference to cross-sectional views (a) to (f) of FIG.

First, after oxidizing at 1150 ° C. in a water vapor atmosphere to form a SiO ₂ film 205 having a thickness of 1.5 μm on the surface, the front and back SiO ₂ films 205 are patterned with hydrofluoric acid by photolithography. Thereafter, an Al film 206 was sputter-deposited on the SiO ₂ film 205 on the support layer side by 0.8 μm, and the Al film 206 was patterned with a 1% hydrofluoric acid aqueous solution by photolithography (FIG. 8A). .

Next, using a high frequency inductively coupled plasma reactive ion etching apparatus (not shown), dry etching was performed using the Al film 206 as a mask, and the support layer 202 side was etched by about 200 μm (FIG. 8B). Thereby, the first filter 16 and the communication groove 18 are formed. The Al film 206 is dissolved and removed with a 1% hydrofluoric acid aqueous solution to expose the SiO ₂ film 205 on the surface (FIG. 8C). Next, etching is performed up to the stopper layer 204 using the SiO ₂ film 205 as a mask (FIG. 8D).

Next, the processing steps on the active layer 203 side will be described. Similarly to the processing on the support layer 202 side, a SiO ₂ film 207 of 1 μm is formed by thermal oxidation, and then patterned with hydrofluoric acid by a photolithography method (FIG. 8E). Thereafter, etching is performed up to the stopper layer 204 using the SiO ₂ film 207 as a mask, and the exposed stopper layer 204 is removed with hydrofluoric acid (FIG. 8F). By this step, the second filter 17 is formed on the active layer 203 side corresponding to the first filter 16 formed on the support layer 204 side. In addition, the diaphragm 7 is simultaneously formed by the active layer 203. In the present embodiment, the first filter 16 has a grid shape with a side of 52 μm, the hole diameter of the second filter 17 is 5 μm, and a fine array with a pitch of 7.5 μm. Accordingly, about 56 holes of the second filter holes 20 are formed per 1 meter of the first filter 16, and the aperture ratio is about 40%. Either the active layer or the support layer may be processed first.

  9 and 10 are cross-sectional views showing other configuration examples of the internal filter 6. In this way, various types of filters can be considered by changing the shape of the first filter 16 or the second filter 17, but any shape can be formed by the manufacturing process described above. In the example shown in FIG. 9, the first filter 16 is not a mesh shape or a mesh shape, but is constituted by parallel or non-parallel protrusions and micropores formed between the protrusions. From the viewpoint of design and manufacturing, the filter of FIG. 9 is a more preferable configuration example. Although the protrusion has a continuous or non-continuous parallel or non-parallel structure, a substantially parallel protrusion is desirable in terms of design and manufacturing.

  Finally, the orifice plate 3 and the diaphragm plate 8 were joined to the chamber plate 5 by anodic bonding to obtain the ink jet head 1 shown in FIG. In the internal filter 6 obtained by this embodiment, the first filter 16 and the second filter 17 are integrally formed by etching silicon, so that relatively large dust and relatively small dust in the ink can be separated. it can. Furthermore, since the communication path 18 for securing the ink flow is formed in the first filter 16, the ink flows through the communication path 18 even when relatively coarse dust adheres to the filter. The increase in resistance can be minimized. Furthermore, it is possible to minimize the change over time in the ink ejection characteristics caused by such an increase in flow path resistance, and to provide a high-quality and long-life inkjet head.

  According to the above embodiment, since the filter is formed by etching silicon, a filter hole diameter of 5 μm can be easily formed with high accuracy, and is configured by the first filter and the second filter. The first filter is formed with a communication path for ensuring ink flow, so that even if relatively coarse dust adheres to the filter, the communication path is prevented. Since ink flows through, an increase in channel resistance can be prevented.

1 is a perspective view of an inkjet head according to an embodiment of the present invention. The disassembled perspective view of an inkjet head. Sectional drawing which shows the flow-path structure corresponding to the nozzle of an inkjet head. The perspective view of the internal filter 6. FIG. FIG. 3 is an enlarged perspective view of an internal filter 6. Sectional drawing of the internal filter 6. FIG. 1 is a cross-sectional view illustrating a configuration of an SOI substrate 201 used in an embodiment of the present invention. 3 is a flowchart showing a first step of etching the SOI substrate 201. FIG. The flowchart which shows the 2nd process of the etching of SOI substrate 201. FIG. FIG. 9 is a flowchart showing a third step of etching the SOI substrate 201. FIG. 9 is a flowchart showing a fourth step of etching the SOI substrate 201. FIG. 9 is a flowchart showing a fifth step of etching the SOI substrate 201. The flowchart which shows the 6th process of the etching of SOI substrate 201. FIG. Sectional drawing which shows the other structure of the internal filter 6. FIG. Sectional drawing which shows another structure for the internal filter 6. FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Inkjet head, 2 ... Nozzle, 3 ... Orifice plate, 4 ... Pressure chamber, 5 ... Chamber plate, 6 ... Internal filter, 7 ... Vibration plate, 8 ... Diaphragm plate, 9 ... Reinforcement plate, 10 ... Relay member, 11 DESCRIPTION OF SYMBOLS ... Piezoelectric vibrator, 12 ... Support substrate, 13 ... FPC, 14 ... Ink supply port, 15 ... Restrictor, 16 ... First filter, 17 ... Second filter, 18 ... Communication groove, 100 ... Drive part, 101 ... Flow Road part, 201 ... SOI substrate, 202 ... support layer, 203 ... active layer.

Claims (12)

An ink chamber that communicates with the ink flow path, a plurality of nozzles that communicate with the ink chamber, a diaphragm that forms part of the ink chamber, and an ink chamber that is provided at a position facing the ink chamber of the diaphragm. In an inkjet head that includes a pressure unit, changes an ink chamber pressure by the ink chamber pressurizing unit, and discharges ink from the nozzle.
An inkjet head comprising a filter disposed in a flow path, wherein the filter is composed of a plurality of protrusions and a microporous filter formed between the protrusions.   2. The ink jet head according to claim 1, wherein the plurality of protrusions constitute a relatively coarse first filter, and the microporous filter constitutes a second filter.   3. The ink jet head according to claim 2, wherein the plurality of protrusions are formed with communication passages for ensuring ink flow to the adjacent second filter.   2. The ink jet head according to claim 1, wherein the height of the plurality of protrusions protrudes from the surface of the microporous filter.   2. The ink jet head according to claim 1, wherein the filter is made of silicon. An ink chamber communicating with the ink flow path, a plurality of nozzles communicating with the ink chamber, a vibration plate forming a part of the ink chamber, and a piezoelectric vibrator provided at a position facing the ink chamber of the vibration plate An ink jet head that changes ink chamber pressure by expansion and contraction parallel to the polarization direction of the piezoelectric vibrator, and ejects ink from the nozzles.
A filter formed in the flow path, the filter comprising a first filter constituted by a protrusion and a second filter having a micropore formed in a region surrounded by the protrusion. Inkjet head characterized. The inkjet head according to claim 6.
The ink jet head according to claim 1, wherein the first filter has a number of meshes, and the second filter has a number of micropores formed in the cells. The inkjet head according to claim 6.
2. The ink jet head according to claim 1, wherein the first filter includes a plurality of parallel protrusions, and the second filter includes a plurality of micropores formed between the parallel protrusions. The inkjet head according to claim 6.
The ink jet head according to claim 1, wherein the first filter includes a plurality of holes and grooves communicating between the holes, and the second filter includes a plurality of micro holes formed in the holes. Forming a first silicon oxide film on the substrate surface of the SOI substrate in which a silicon substrate, a stopper layer and an active layer are laminated and integrated;
Patterning the first silicon oxide film to form a pattern to be the first filter of the internal filter;
A mask material is formed on the pattern and the mask material is used to etch the pattern to be the first filter,
After removing the mask material, the pattern is etched to the stopper layer,
Forming a second silicon oxide film on the active layer surface;
Patterning the second silicon oxide film to form a pattern to be a micropore of the second filter;
Removing the stopper layer,
A method of manufacturing an ink-jet head. Forming a second silicon oxide film on the active layer surface of the SOI substrate in which the silicon substrate, the stopper layer, and the active layer are laminated and integrated;
Patterning the second silicon oxide film to form a pattern to be a micropore of the second filter;
Forming a first silicon oxide film on the substrate surface;
Patterning the first silicon oxide film to form a pattern to be the first filter of the internal filter;
A mask material is formed on the pattern and the mask material is used to etch the pattern to be the first filter,
After removing the mask material, the pattern is etched to the stopper layer,
Removing the stopper layer,
A method of manufacturing an ink-jet head. The SOI substrate includes a region of a diaphragm portion and an internal filter portion. In the diaphragm portion, after the second silicon oxide film is formed on the active layer, the stopper layer is removed without patterning, and then the silicon oxide film is formed. Remove to form a diaphragm,
The method of manufacturing an ink jet head according to claim 10 or 11, wherein:

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