Method for manufacturing a filter

A method for manufacturing a filter is provided which can easily manufacture the filter that has both excellent anti-corrosion properties and anti-abrasion properties. In the method, a first substrate is produced that has a plurality of holes, a ceramic layer will be formed by depositing extremely small particles of ceramic material on one side of the first substrate, and a filter having a plurality of holes will be obtained. The manufactured filter is composed of ceramic material, and has excellent anti-abrasion and anti-corrosion properties.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to Japanese Patent Application No. 2004-315223 filed on Oct. 29, 2004, the contents of which are hereby incorporated by reference into this application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for manufacturing a filter that removes dust contained in a fluid. In particular, the present invention relates to a method for manufacturing a filter for removing dust contained in a corrosive fluid such as ink or the like, that has excellent anti-abrasion properties and anti-corrosion properties.

2. Description of the Related Art

For the purpose of removing dust contained in a fluid, filters having a plurality of holes which allow the fluid to pass therethrough but do not allow dust to pass therethrough are widely used in various fields. For example, an ink jet head that ejects ink from nozzles generally has a filter having holes whose diameters are smaller than the nozzle diameters, in order to prevent dust from clogging the nozzles and ink no longer being able to be discharged therefrom (for example, FIG. 1 of Japanese Laid-Open Patent Application Publication No. 2004-268454). The filter of Japanese Laid-Open Patent Application Publication No. 2004-268454 is formed by electrotyping. In other words, after forming a resist pattern that corresponds to a plurality of holes at a surface of a conductive substrate, a metal such as nickel, copper, or the like is deposited by electro deposition method to form a thin metal layer on the portions of the substrate in which the resist pattern is not formed, and then the substrate is removed from the metal layer to obtain a filter.

BRIEF SUMMARY OF THE INVENTION

However, when the filter is formed by electrotyping, the material of the filter is limited to metals such as nickel, copper, or the like that have poor anti-corrosion properties. Because of that, when the filter is arranged in a corrosive fluid such as ink or the like, problems will occur in which the diameters of the holes in the filter will gradually enlarge due to corrosion, and the dust removal function of the filter will decline, and thus the life of the filter will be shortened. In addition, problems will occur in which the diameters of the holes in the filter will gradually enlarge due to abrasion that occurs when a fluid such as ink or the like passes therethrough, the dust removal function of the filter will decline, and thus the life of the filter will be shortened.

The shortening of the life of the filter that accompanies the corrosion and abrasion will be identical with filters composed of a synthetic resin material. By forming holes with a laser process in a substrate composed of a synthetic resin, it will be possible to manufacture a filter having microscopic holes. However, because synthetic resin has poor anti-corrosion properties and anti-abrasion properties, the holes in the filter will gradually enlarge due to the abrasion that occurs when ink passes therethrough or due to the corrosion caused by ink, and thus the life of the filter will be shortened.

It is generally possible to form a filter composed of a metal having good anti-corrosion properties and anti-abrasion properties by methods other than electrotyping. However, it is generally difficult to process this type of metal with high-precision, and difficult to manufacture a filter having holes with small diameters that is essential in an ink jet head. For example, when forming holes in a stainless steel plate having good anti-corrosion properties with a mechanical process such as a micropunching process, drill process, or the like, it is difficult to form a plurality of holes with good precision that have diameters smaller than the diameters of the nozzles (for example, 10 μm or less).

An object of the present invention is to provide a method for manufacturing a filter having microscopic holes, that is capable of easily manufacturing the filter that has both excellent anti-corrosion properties and anti-abrasion properties.

The present invention may be embodied as a method for manufacturing a filter. The method for manufacturing a filter of the present invention includes processes of forming a first substrate having a plurality of holes, and depositing particles of ceramic material on one side of the first substrate to form a ceramic layer.

In the aforementioned method, the ceramic layer is formed on one side of the first substrate. Because a plurality of holes is arranged on the first substrate, the ceramic layer formed in the aforementioned method has a plurality of holes that are identical with the first substrate. This ceramic layer can be used as a filter.

When ceramic is employed as a filter for a corrosive fluid such as ink or the like, it will be difficult for corrosion to occur because the anti-corrosion properties of the ceramic are high, and it will be difficult for the diameters of the holes to become enlarged. In addition, even if a fluid such as ink or the like passes through the filter, it will be difficult for the diameters of the holes to become enlarged because the anti-abrasion properties of the ceramic are good. In other words, it will be difficult for the dust removal function of the filter to decline, and thus a filter having a long life can be manufactured.

Because ceramics have a high degree of hardness, it is difficult to form microscopic holes with good precision in a ceramic plate by a mechanical process. However, in the aforementioned method for manufacturing a filter, by forming a ceramic layer on the first substrate having a plurality of holes, a ceramic layer that has a plurality of holes can be obtained formed with good precision.

DETAILED DESCRIPTION OF THE INVENTION

One embodiment of the invention will be described with reference to the figures. The present embodiment is an example in which the present invention is practiced to manufacture a filter of an ink jet head that discharges ink onto recording sheets.

First, an ink jet printer100will be described with reference toFIG. 1. The ink jet printer100has a carriage101capable of moving in a scanning direction (the left to right direction ofFIG. 1), a serial type of ink jet head1that is arranged on the carriage101and ejects ink onto a recording sheet P, a transport roller102that transports the recording sheet P in a sheet feed direction (the forward direction ofFIG. 1), and other items. The ink jet head1moves in the scanning direction together with the carriage101, and ejects ink onto the recording sheet P from the lower surface thereof. The recording sheet P onto which ink is ejected is discharged in the sheet feed direction by means of the transport roller102.

Next, the ink jet head1will be described with reference toFIGS. 2 to 4. As shown inFIG. 2, the ink jet head1has cylindrical connection member42which is connected to an ink supply tube (not shown in the figures) connected to an ink tank (not shown in the figures), a flow path unit2(seeFIG. 3) in which ink flow paths are formed in the interior thereof, and a piezoelectric actuator3that is laminated on the upper portion of the flow path unit2. The ink supplied from the connection member42is ejected from a plurality of nozzles20arranged on the lower portion of the flow path unit2.

As shown inFIGS. 3 and 4, the flow path unit2has a cavity plate10, a base plate11, a manifold plate12, and a nozzle plate13, and these four plates are sequentially laminated and adhered to each other from above. In addition, the piezoelectric actuator3has an oscillation plate30, and the oscillation plate30is laminated and bonded to the upper portion of the cavity plate10of the flow path unit2.

As shown inFIG. 4, the nozzle plate13has nozzles20. As shown inFIG. 2, the plurality of nozzles20are linearly aligned in the sheet feed direction. In the present embodiment, the plurality of nozzles20is aligned in two rows.

As shown inFIG. 4, in the laminated state, the manifold plate12has communication holes19that respectively communicate with the corresponding nozzles20arranged on the nozzle plate13. The base plate11has communication holes16that respectively communicate with the corresponding communication holes19in the laminated state. The cavity plate10has pressure chambers14that respectively communicate with the corresponding communication holes16in the laminated state.

As shown inFIG. 2, the pressure chambers14are substantially oval shaped and extend along the scanning direction. The pressure chambers14communicate with the communication holes16on one end thereof, and communicate with the communication holes15described below on the other end thereof.

As shown inFIG. 4, the base plate11has communication holes15that respectively communicate with the corresponding pressure chambers14in the laminated state. The manifold plate12has a manifold17that communicate with each of the plurality of communication holes15. For each of the plurality of nozzles20, individual ink flow paths21are formed inside the flow path unit2from the manifold17to the nozzles20via the pressure chambers14.

As shown inFIG. 3, the oscillation plate30has an ink supply port18. Ink is supplied from the connection member42to the ink supply port18. The cavity plate10has a communication hole40that communicates with the ink supply port18in the laminated state. The base plate11has a communication hole41that communicates with the communication hole40in the laminated state. The manifold17of the manifold plate12communicate with the communication hole40in the laminated state. Ink supplied from the ink supply port18passes through the communication holes40,41and flows into the manifold17. Ink that has flowed into the manifold17will pass through each of the communication holes15and flow into the respective pressure chambers14. Ink that has flowed into the respective pressure chambers14will pass through the communication holes16,19, and be supplied to the respective nozzles20.

As shown inFIG. 3, a filter43composed of ceramic material such as alumina, zirconia, silicon nitride, silicon carbonate, and the like, and whose thickness is extremely thin (e.g., about 5-10 μm), is interposed between the oscillation plate30and the connection member42. The filter43has a plurality of holes43athrough which the ink passes. The diameters of the plurality of holes43aare smaller (e.g., about 10 μm) than the diameters of the nozzles20that discharge ink (e.g., about 20 μm). Because of that, dust contained in the ink supplied to the manifold17from the ink tank will be reliably removed by the filter43, and will prevent dust from clogging the nozzles20and ink from no longer being able to be discharged from the nozzles20.

When a metallic material or a synthetic resin material is used as the filter43, the holes43awill widen and the dust removal function of the filter43will gradually decline with the use of the ink jet head1because of abrasion of the filter43due to ink passing through the holes43a, or the corrosion of the filter43due to ink. However, in the present embodiment, the filter43is formed with a ceramic material having good anti-abrasion properties and anti-corrosion properties. Because of that, it will be difficult for the holes43ato become enlarged due to abrasion and corrosion, and thus the rate of decline in the dust removal function will be small, and the filter43will have a long life. The method in which the filter43is manufactured will be described in detail below.

Next, the piezoelectric actuator3will be described. As shown inFIGS. 3 and 4, the piezoelectric actuator3has the oscillation plate30, a piezoelectric layer31that is formed on the upper surface of the oscillating plate30, and a plurality of individual electrodes32that are formed on the upper surface of the piezoelectric layer31. As shown inFIG. 2, the individual electrodes32are formed in positions which correspond to the respective plurality of pressure chambers14of the flow path unit2.

The oscillation plate30is a metallic plate, and serves as a common electrode that faces the plurality of individual electrodes32and creates an electric field in the piezoelectric layer31between the individual electrodes32and the oscillation plate30. The oscillation plate30is grounded and maintained in the ground state.

The piezoelectric layer31is formed on the upper surface of the oscillation30, and the primary component thereof is lead zirconate titanate (PZT) which is a solid solution of lead titanate and lead zirconate and is also a ferroelectric substance.

The individual electrodes32are plate shaped members composed of a conductive material, and as shown inFIG. 2, have a flat oval shape that is slightly smaller than the pressure chambers14. In the plan view ofFIG. 2, the plurality of individual electrodes32is respectively arranged in regions which face the central portions of the corresponding pressure chambers14. Furthermore, terminals35are formed on the ends of the individual electrodes32. As shown inFIG. 4, the terminals35are electrically connected to a driver IC37via flexible wiring members (not shown in the figures) such as a flexible print wiring board and the like, and a drive voltage is selectively applied from the driver IC37to the plurality of individual electrodes32via the terminals35.

Next, the operation of the piezoelectric actuator3will be described. When a drive voltage is selectively applied from the driver IC37to the plurality of individual electrodes32, the electric potential of the individual electrodes32to which the drive voltage is applied will be different than the electric potential of the oscillation plate30maintained in the ground state, and an electric field will be produced in the vertical direction ofFIG. 4in the piezoelectric layer31interposed between the individual electrodes32and the oscillation plate30. By creating an electric field, the piezoelectric layer31will polarized in the vertical direction ofFIG. 4, and will contract in a direction perpendicular to the polarization direction. With the contraction of the piezoelectric layer31, bending will be effected in the oscillation plate30, and the oscillation plate30will deform so as to be convex on the pressure chamber14side. The capacity inside the pressure chambers14will be reduced, the ink inside the pressure chambers14will be pressurized, and the ink will be ejected from the nozzles20that communicate with the pressure chambers14.

Next, a method of manufacturing the filter43made of ceramic will be described with reference toFIG. 5.

First, as shown inFIG. 5(a), a photo-resist pattern51is formed on one side of a second substrate50. A conductive material such as stainless steel, a silicon wafer, and the like is employed as the second substrate50. The photo-resist pattern51is formed on the portions in which one wants holes to be formed in a first substrate52.

Next, as shown inFIG. 5(b), electro deposition is performed on the second substrate50. A metal such as nickel, copper, or the like is deposited on the portions in which the photo-resist pattern51is not formed. In this way, a metal layer60having a plurality of holes52awill be formed on the second substrate50.

Next, as shown inFIG. 5(c), the second substrate50and the photo-resist pattern51will be removed from the metal layer60, and the first substrate52will be obtained. As noted above, by employing an electro deposition method in which the photo-resist pattern51was used, a first substrate52having extremely small holes52aof about 10 μm in diameter can be easily produced.

Next, as shown inFIG. 5(d), particles of a ceramic material such as alumina, zirconia, silicon nitride, silicon carbide, and the like will be deposited on the surface of the first substrate52(the metal layer60) from which the second substrate50was removed, and a ceramic layer61will be formed. For example, the ceramic layer61can be formed by an aerosol deposition method (AD method) that sprays extremely small particles of ceramic material mixed with a carrier gas onto the substrate52to cause them to collide therewith at a high speed, and thereby be deposited on the first substrate52. Or, a sputtering method or a chemical vapor deposition method (CVD method) can be employed to form the ceramic layer61. In this way, an extremely thin ceramic layer61having a thickness of about 5-10 μm can be formed.

The plurality of holes52aare formed in the first substrate52(metal layer60), and particles of ceramic material will not be deposited in the positions of these holes. Thus, the ceramic layer61that is formed has holes43athat are formed in the positions that correspond to the holes52aof the first substrate52.

Finally, as shown inFIG. 5(e), the first substrate52(metal layer60) is removed from the ceramic layer61by etching with hydrochloric acid or the like to obtain the filter43. The ceramic layer61is heated to a high temperature at which the particles of the ceramic material will be sintered. The first substrate52may be removed before heating or after heating the ceramic layer61.

According to the method for manufacturing the filter43, a filter43will be obtained that is composed of ceramic materials that have both excellent anti-abrasion properties and anti-corrosion properties with respect to ink. It will be difficult for enlargement of the holes43aof the filter43to occur due to abrasion or corrosion. It will be difficult for the dust removal function of the filter43to decline, and thus the filter43will have a long life. In addition, the filter43can be easily manufactured, and the manufacturing costs will be low.

Because the hardness of ceramic material is high, it will be extremely difficult to perform a mechanical process such as a drill process or the like on a ceramic plate. According to the method for manufacturing the filter of the present embodiment, a ceramic layer61having a plurality of holes43acan be easily formed on the smooth surface of the metal layer60having a plurality of holes52a, by forming a ceramic layer61by the AD method, the sputtering method or the CVD method.

By employing the AD method, the sputtering method, or the CVD method, an extremely thin ceramic layer61can be formed. In the aforementioned method for manufacturing, after the ceramic layer61was formed, the overall thickness of the filter43can be further reduced by removing the metal layer60from the ceramic layer61. The filter43produced in this way will have an extremely small flow resistance (pressure drop) when ink passes therethrough.

In particular, when air bubbles that have a harmful impact on ink discharge operations are mixed into the individual ink flow paths21which include the pressure chambers14(seeFIG. 4), the ink will be forcibly pressurized and discharged together with the air bubbles from the nozzles20. In other words, although it will be necessary to perform a purge operation, the air bubbles will become easier to discharge when the pressure drop of the ink is small in the filter43because the speed of the ink that is discharged from the nozzle20will increase.

Next, modified examples will be described in which various modifications were added to the aforementioned embodiment. However, portions having the same composition as the aforementioned embodiment will be referred to with the same reference numerals, and descriptions thereof will be appropriately omitted.

MODIFICATION EXAMPLE 1

In the aforementioned embodiment, after the first substrate52(metal layer60) was used to form the ceramic layer61, the whole of the first substrate52is removed from the ceramic layer61. However, it is possible that only the central part of the first substrate52is removed and the peripheral part of the first substrate52is left. As shown inFIG. 5(d), the ceramic layer61may be formed on a smooth surface (bottom surface) of the first substrate52, and then as shown inFIG. 7(a), a mask72is formed on the other surface (upper surface) of the first substrate52. The mask72is formed so that only the peripheral part of the first substrate52is covered by the mask72. Next, as shown inFIG. 7(b), the first substrate52is etched. The central part of the first substrate52, on which the mask72is not formed, is removed from the ceramic layer61. In this case, a filter73of which the peripheral part is reinforced with a stiff metallic frame can be obtained. The filter73is difficult to break, and is easy to handle for fitting within the ink jet head1. In addition, as shown inFIG. 7(c), it is also possible to remove the mask72after removing the central part of the first substrate52.

MODIFICATION EXAMPLE 2

In the aforementioned embodiments, after the first substrate52(metal layer60) was used to form the ceramic layer61, the first substrate52is removed from the ceramic layer61. However, removing the first substrate52may be omitted. In this case, the thickness of the entire filter increases because of the thickness of the first substrate52. However, a layer of ceramic material whose durability is generally low can be reinforced by means of the first substrate52composed of a metallic material such as nickel, copper, or the like, and thus the strength of the filter will improve.

MODIFICATION EXAMPLE 3

As shown inFIG. 6(a), a ceramic layer70may be formed on a smooth surface (bottom surface) of the first substrate52, and then as shown inFIG. 6(b), the entire first substrate52may be coated with the ceramic layer70by depositing a ceramic material on another surface (upper surface) of the first substrate which has assumed a slightly rounded shape and on the inner surface of the holes52a. In this case, because the entire first substrate52that is made of metal having a high degree of strength is coated with the ceramic layer70having good anti-abrasion properties and anti-corrosion properties, a filter43A can be obtained that has both excellent anti-abrasion and anti-corrosion properties, and a high degree of strength.

MODIFICATION EXAMPLE 4

The aforementioned embodiment is an example in which the present invention was applied to a filter of an ink jet head, however because the anti-corrosion properties of the filter of the present invention are high, the filter can be used in various devices that use various fluids other than ink which contain corrosive fluid (not only fluids such as water and the like, but also gases such as air and the like).