JPH10202860A - Ink jet recording head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and inexpensively produce an ink emitting actuator in an ink jet recording head. SOLUTION: An ink jet recording head is equipped with an ink cavity 16 housing ink, the film 14 composed of a halogen-containing org. compd. opposed to the ink cavity 16 and having a common electrode 30 provided to the surface opposed to the ink cavity thereof and also having drive voltage applying individual electrodes 32 provided to the opposite surface thereof and the base electrode 40 provided to the individual electrodes 32 of the film 14 in a non-adhesive state and receiving the application of bias electrode having the same polarity as the drive voltage to form an electric field between the common electrode 30 and the base electrode 40.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording head for recording an image by attaching ink droplets discharged according to an image signal to a recording medium such as recording paper.

[0002]

2. Description of the Related Art Conventionally, in an ink jet type image recording apparatus, an ink jet recording head using a piezoelectric member as an actuator for discharging ink droplets according to an image signal has been known. In general, this type of head is arranged so as to face a plurality of ink cavities for accommodating ink and each of the ink cavities, and pressurizes the ink in the ink cavities based on deformation when a voltage is applied to eject ink droplets from nozzles. And a plurality of piezoelectric members. In many cases, these piezoelectric members are divided and formed by applying a plurality of grooves to a single piezoelectric plate fixed on a substrate using a dicing saw.

[0003]

However, the above-mentioned method for forming a piezoelectric member separates and forms piezoelectric members one by one from a piezoelectric plate while maintaining high processing accuracy, and therefore, the processing efficiency is extremely low. Was bad. Further, since the piezoelectric member is formed in a long shape with a minute width of, for example, about 100 μm, there is also a problem that the piezoelectric member is easily broken during processing, it is difficult to increase the yield, and the cost is increased.

[0004]

Accordingly, an ink jet recording head according to the present invention has been developed in order to solve the above-mentioned problems.
An ink cavity containing the ink and a halogen-containing organic compound having a first electrode layer on the surface facing the ink cavity and facing the ink cavity and having a second electrode layer for applying a driving voltage on the opposite surface. A third layer, which is provided in a non-adhered state with respect to the film layer and the second electrode layer of the film layer, and is applied with a bias voltage having the same polarity as the driving voltage to form an electric field between the first electrode layer and the third electrode layer; And an electrode layer.

In the ink jet recording head, the halogen-containing organic compound is preferably a fluorine-containing organic compound.

Further, the film layer may be configured to be in direct contact with the ink contained in the ink cavity.

Further, the thickness of the peripheral portion of the film layer in the region facing the ink cavity may be formed thinner than the actuator portion in the inner region.

[0008]

In the ink jet recording head according to the present invention, an electric field is formed between the third electrode layer and the first electrode layer by the bias voltage applied to the third electrode layer. Generates a charge having the same polarity as the bias voltage. In this state, when a drive voltage having the same polarity as the above-mentioned bias voltage is applied to the second electrode layer of the film layer, the halogen-containing organic compound constituting the film layer has a higher dielectric constant than the ordinary resin material, and thus the second electrode layer has a higher dielectric constant. A large amount of electric charge having the same polarity as the driving voltage is stored in the electrode layer, and an electrostatic repulsion is generated between the electrode layer and the surface of the third electrode layer where the electric charge of the same polarity is generated. Since the film layer is not adhered to the third electrode layer, the film layer is displaced away from the third electrode layer by the repulsive force. This displacement of the film layer reduces the volume in the ink cavity, whereby the pressurized ink is ejected as ink droplets.

As described above, in the ink jet recording head of the present invention, the film layer made of a halogen-containing organic compound is used as an actuator for ejecting ink. Since this film layer can be easily formed into a desired shape by molding or the like and is inexpensive, it is extremely advantageous for mass production of heads. Further, since the film layer has excellent displacement response, the image forming speed can be increased by applying a high-period driving voltage to increase the number of ink droplets ejected per time.

Further, when a fluorine-containing organic compound is used as the halogen-containing organic compound constituting the film layer, since the dielectric constant is large, a larger electrostatic repulsion can be obtained, and the ink ejection efficiency can be improved. .

In an ink jet recording head in which the film layer comes into direct contact with the ink contained in the ink cavity, the material of the film layer can be made water-resistant. As described above, there is no need for a water-resistant coat or a protective member for preventing adverse effects due to ink permeation, and component costs can be reduced.

Further, in the ink jet recording head in which the peripheral portion of the film layer in the region facing the ink cavity is formed thinner than the actuator portion in the inner region, the actuator portion of the film layer is displaced by making the peripheral portion thinner. Since the resistance at the time of the driving is small, the displacement of the actuator can be increased even with the same driving voltage, and the ink ejection efficiency is improved.

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 to 3 show an ink jet recording head 10 according to one embodiment of the present invention. The head 10 includes a top plate 12 at a portion facing a recording medium (not shown). The top plate 12 is made of ceramic, synthetic resin, metal, or the like, and has a plurality of groove-shaped concave portions formed by finely processing the back surface. A film layer 14 is bonded and fixed to the top plate 12 so as to cover each recess. The inside of each concave portion covered with the film layer 14 is an ink cavity 16 for storing ink, an ink supply chamber 18 for storing replenishment ink, and an ink inlet 20 for communicating each ink cavity 16 with the ink supply chamber 18. Is formed. The ink cavities 14 are formed in parallel and at equal pitches, respectively.
Reference numeral 6 is connected to an ink tank (not shown). On the top plate 12, nozzles 22 communicating with the ink cavities 16 are formed on the opposite side of the ink inlets 20 by excimer laser processing or the like.

The film layer 14 is made of a halogen-containing organic compound which is a dielectric, and is particularly preferably formed of a fluorine-containing organic compound. A preferable specific material having excellent displacement response is polytetrafluoroethylene (PT).
FE), polychlorotrifluoroethylene (PCTF
E), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), polyvinylidene fluoride (PV
DF), polyvinyl fluoride (PVF), and a dispersion of piezoelectric material particles in polyvinylidene fluoride. Further, a material in which piezoelectric material particles are dispersed in a rubber material such as polyurethane, polysilicone, polybutadiene, and polyfluorosilicone can also be used as the material of the film layer 14.

The film layer 14 is provided so as to face one wall of the ink cavity 16 and the like, and is in direct contact with the ink contained in the ink cavity 16 and the like. In addition, the thickness of the peripheral portion of the film layer 14 in the ink cavity facing region is formed to be smaller than that of the actuator portion 28 in the inner region. In other words, the actuator portion 28 is formed of a rectangular convex portion protruding from the lower surface of the film layer 14 corresponding to each ink cavity 16, and its length and width are formed slightly smaller than the ink cavity 16. In the layer 14, the actuator section 28 is formed to be thick, and other portions including the peripheral portion are formed to be thinner than the actuator section 28. Such a shape of the film layer 14 can be formed by a known resin integral molding technique such as extrusion molding, compression molding, calendar molding, and casting molding.

The film layer 14 has a common electrode (first electrode layer) 30 made of, for example, an Au sputter film on the surface on the ink cavity 16 side, and the common electrode (first electrode layer) 30 is formed on the lower surface of the actuator section 28 on the opposite side. It has an individual electrode (second electrode layer) 32 made of an Au sputtering film for applying a driving voltage. The common electrode 30 is formed over the entire surface of the film layer 14 and projects from the side of the head.
4 is connected to the ground from the end 24. On the other hand, the individual electrodes 32 are formed in a pattern corresponding to the respective actuator sections 28, are respectively drawn out to the ends 24 of the film layer 14, and are individually connected to an image signal control circuit 36 via a flexible wiring or the like. I have. For forming the common electrode 30 and the individual electrode 32, various known methods such as coating, vapor deposition, ion plating, and conductive paste printing can be used other than sputtering.

A base electrode (third electrode layer) 40 made of a metal plate is provided on the surface of the film layer 14 on which the individual electrode 32 of each actuator section 28 is formed in a non-adhered state. Each base electrode 40 is fixed to a substrate 42 made of ceramic, synthetic resin, or the like. Also, the substrate 4
A plurality of spacer members 44, 46, 48, 50 are fixed around the base electrode 40, and support the top plate 12 via the film layer 14.

Next, the ink discharging operation of the ink jet recording head 10 having the above-described configuration will be described with reference to FIGS. FIGS. 4 and 5 are schematic diagrams for explaining the operation when the actuator section 28 of the film layer 14 is displaced. In the following description, the polarity of the drive voltage of the actuator unit 28 and the other voltages will be described as plus. However, even when the polarity is minus, the same displacement operation and effect can be obtained for the actuator unit 28.

When the head 10 is in a state where ink can be ejected, a constant bias voltage (for example, 350 volts) is applied to the base electrode 40 by the power supply 54. This bias voltage is applied to an actuator 28 described later.
Is a voltage having the same polarity as the drive voltage. An electric field in the direction toward the common electrode 30 is formed between the base electrode 40 and the common electrode 30 by the bias voltage, and a positive charge is generated on the individual electrode 32 side inside the base electrode 40.
Further, the individual electrode 32 is in contact with the base electrode 40 so as to conduct, and the individual electrode 32 similarly generates a positive charge.

In this state, a drive voltage is applied from the image signal control circuit 36 to the individual electrodes 32. As the driving voltage, for example, a rectangular pulse voltage having a rise time of 6 μsec, a maximum voltage value of 400 volts, and a maximum voltage application time of 100 μsec is applied. Then, the actuator unit 2
Since the halogen-containing organic compound composing 8 has a higher dielectric constant than a normal resin material, a large amount of positive charges are rapidly stored in the individual electrode 32, and a large amount of positive charges are generated between the individual electrode 32 and the base electrode 40 which also generates positive charges. Generates an electrostatic repulsion. Since the actuator unit 28 is not in contact with the base electrode 40, the repulsive force causes the actuator unit 28
Is displaced away from the base electrode 40 (in the direction of the arrow 56). Due to this displacement, the volume of the ink cavity 16 is reduced and the ink inside is pressurized, and is ejected from the nozzle 22 as an ink droplet. The ink droplets adhere to a recording medium (not shown) to record an image.

As described above, in the ink jet recording head 10 of the present embodiment, the film layer 1 made of a halogen-containing organic compound is used as an ink ejection actuator.
4 is used. Since the film layer 14 can be easily formed into a desired shape by molding or the like and is inexpensive, it is extremely advantageous for mass production of a head as compared with the case where a piezoelectric member is used for an actuator. Further, since the film layer 14 has good displacement response, the image forming speed can be increased by applying a high-period driving voltage to increase the number of ink droplets ejected per time.

Further, when a fluorine-containing organic compound is used as the halogen-containing organic compound constituting the film layer, a larger electrostatic repulsion can be obtained with respect to the base electrode 40, and the ink ejection efficiency can be improved. be able to.

Further, since the material of the film layer 14 can be made water-resistant, there is no need for a water-resistant coating or a protective member for preventing an adverse effect due to ink penetration as in the case of using a piezoelectric member for the actuator.
Parts cost can be reduced.

Further, since the film layer 14 is formed to have a smaller thickness at the peripheral portion than the actuator portion 28, the resistance when the actuator portion 28 is displaced is small, and the actuator portion 28 has the same driving voltage. Can be increased, and the ink ejection efficiency can be increased.

If the water resistance of the film layer 14 is too high and the water repellency is strong, the surface of the film layer 14 is subjected to a hydrophilic treatment to improve the wettability with respect to the ink. Can be prevented, and the responsiveness of ink supply from the ink supply chamber 18 to the ink cabbage 16 when the film layer 14 is restored can be improved.

The ink jet recording head 10
In the above, the base electrodes 40 are individually provided corresponding to the respective actuator portions 28 of the film layer 14. However, as shown in FIG. 6, if the base electrode plate 60 is provided so as to be common to all the actuator portions 28, manufacturing is possible. Becomes easier.

[Brief description of the drawings]

FIG. 1 is a partial plan view of a recording medium facing portion of an ink jet recording head according to the present invention.

FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 is a sectional view taken along line III-III in FIG. 2;

FIG. 4 is a schematic diagram for explaining an operation when an actuator section of a film layer is displaced.

FIG. 5 is a schematic diagram for explaining an operation when an actuator section of a film layer is displaced, similarly to FIG. 4;

FIG. 6 is a view showing a modification in which a base electrode is formed in a plate shape common to each actuator unit.

[Explanation of symbols]

10 ... inkjet recording head, 12 ... top plate, 14 ...
Film layer, 16: ink cavity, 28: actuator section, 30: common electrode (first electrode layer), 32: individual electrode (second electrode layer), 40: base electrode (third electrode layer).

Claims (4)

[Claims] An ink cavity containing ink;
A film layer made of a halogen-containing organic compound having a first electrode layer on the ink cavity side surface opposite to the ink cavity and having a second electrode layer for applying a driving voltage on the opposite surface; An ink jet recording method comprising: a third electrode layer provided in a non-adhesive state with respect to the second electrode layer, and to which a bias voltage having the same polarity as the driving voltage is applied to form an electric field with the first electrode layer. head. 2. The ink jet recording head according to claim 1, wherein said halogen-containing organic compound is a fluorine-containing organic compound. 3. The ink jet recording head according to claim 1, wherein the film layer is in direct contact with the ink contained in the ink cavity. 4. The ink jet recording head according to claim 1, wherein a thickness of a peripheral portion of the film layer in a region facing the ink cavity is made thinner than an actuator portion in an inner region thereof.