JPH05246024A - Ink-jet head - Google Patents

Abstract

PURPOSE:To obtain an ink-jet head which is superior in ink discharge efficiency, has a low manufacturing cost and can cope with a constitution of high density nozzles, and obtain an actuator which is superior in displacing efficiency. CONSTITUTION:A pressure chamber is formed between a base 4 and electrostrictive thin plate 1 continuing to the pressure chamber, an elastic thin plate 2 is provided on the electrostrictive thin plate surface 1 in relation to the pressure chamber and a pressure generating element is constituted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is directed to ejecting ink droplets,
The present invention relates to an inkjet recording apparatus such as a printer that forms an ink image on a recording medium such as recording paper, and more specifically to an inkjet head.

[0002]

2. Description of the Related Art As a conventional technique, JP-A-55-6555 is known.
After a plurality of pressure chambers are formed between a glass substrate and a glass thin plate and a plate of a pressure generating element having electrodes formed on both sides is cut into a size of the pressure chamber as disclosed in Japanese Patent Publication There is an inkjet head bonded to the glass thin plate side of each pressure chamber. In addition, a nozzle forming substrate having a plurality of nozzles and a pressure generating element made of a piezoelectric material and a conductive material, which is arranged so as to face the nozzle, are provided, and the pressure generating element is displaced by an applied voltage to eject ink from the nozzle. On-demand type ink jet head,
It is disclosed in Japanese Patent Publication No. 8953.

FIG. 12 is a partial perspective view illustrating the structure of a conventional ink jet head. Reference numeral 4 is a base substrate including the nozzle 3 and the ink supply path 6. The elastic thin plate 2 composed of a single plate is bonded to the base substrate 4,
A plurality of electrostrictive material thin plates, which have electrodes formed on both surfaces and are cut and processed, are adhered to the elastic thin plate surfaces to form a plurality of pressure generating elements 1a. FIG. 13 is a partial top view illustrating a conventional inkjet head. The ink supplied from the ink supply path 6 into the pressure chamber formed below the pressure generating element 1a ejects an ink droplet 9 from the nozzle 3 by applying a selective voltage to the pressure generating element 1a. be able to. FIG. 14 shows the pressure generating element 1
It is BB sectional drawing of FIG. 13 explaining the displacement mechanism of a. When the electric field is applied to the gap between the positive electrode 7 and the negative electrode 8, the pressure generating element 1a expands in the electric field direction and contracts in the direction perpendicular to the electric field direction. Due to such an action, a bending moment as shown by M is generated, and a flexural displacement as shown by a broken line E is generated.

In such a type of print head, the ink drop forming efficiency (ink discharge amount / actuator drive voltage) is large, the nozzle pitch is narrow, and high precision machining is easy. It is desirable to have low manufacturing costs and low component costs.

[0005]

However, in order to realize a compact and high resolution ink jet head, if the pitch between nozzles is narrowed, the area of the pressure chamber must be narrowed. In general, the formation efficiency of ink droplets has a positive correlation with the area facing the pressure chamber surface of the actuator and the electric field strength applied to the actuator. Therefore, it becomes difficult to obtain sufficient droplet formation efficiency and sufficient ink flying capability. Further, due to the demand for high-precision processing, the degree of difficulty in manufacturing technology increases and it becomes difficult to reduce the manufacturing cost. Further, due to the interference between the adjacent pressure chambers, the ink ejection phenomenon from the unselected nozzles and the ink ejection capability (ink ejection amount, ink ejection speed) due to the printing condition (text pattern printing and solid printing) are remarkable. Changes (crosstalk) are likely to occur.

[0006] The problems to be solved by the present invention are, firstly, to facilitate high-precision machining and to reduce manufacturing and component costs, and secondly, while ensuring excellent printing quality. That is, it is possible to cope with high density nozzles.

[0007]

An ink jet head of the present invention comprises a base substrate having a plurality of nozzles for ejecting ink and an ink supply path, a pressure plate composed of an electrostrictive material thin plate and elastic thin plates having electrodes formed on both sides. In an ink jet head having a generating element, a plurality of pressure chambers formed by laminating the base substrate and the pressure generating element, and a voltage applying unit for applying a voltage to the pressure generating element, the pressure chamber Is formed between the base substrate and the electrostrictive material thin plate continuous to the plurality of pressure chambers, and the elastic thin plate is provided on the electrostrictive material thin plate surface for each of the pressure chambers. It is characterized in that it constitutes a pressure generating element.

Further, a base substrate on which nozzles for ejecting ink and ink supply paths are formed, a pressure generating element formed of an electrostrictive material thin plate and an elastic thin plate on which electrodes are formed on both sides, the base substrate and the pressure generating element. In an ink jet head having a pressure chamber formed by bonding together a pressure chamber and a voltage applying unit for applying a voltage to the pressure generating element, the elastic thin plate is opposite to the pressure chamber side of the electrostrictive material thin plate and the counter pressure chamber. Characterized by staggered construction on both sides. Further, the present invention is characterized in that a plurality of the inkjet heads are arranged.

Further, the elastic modulus of the elastic thin plate is equal to or more than the elastic modulus of the electrostrictive material thin plate.
Furthermore, the thickness of the elastic thin plate is equal to or less than the thickness of the electrostrictive material thin plate. Further, the width of the elastic thin plate is narrower than the width of the pressure chamber. The elastic thin plate is made of a conductive material.

[0010]

The details of the first embodiment of the present invention will be described below.
A description will be given with reference to the drawings.

FIG. 1 is a perspective view of a main portion of an ink jet head according to the first aspect of the present invention. FIG. 2 is a partial cross-sectional view (X-X cross-sectional view of FIG. 1) of the main part of the inkjet head showing the structural relationship of each member according to the first aspect of the present invention.
FIG. 3 is an enlarged view of a portion indicated by a broken line A in FIG. Figure 2
As shown in, the plurality of pressure chambers 5 are formed between the base substrate 4 and the electrostrictive material thin plate 1 continuous with the plurality of pressure chambers 5. By generating an electric field in the gap between the positive electrode 7 formed on the upper surface of the electrostrictive material thin plate and the negative electrode 8 formed on the lower surface of the electrostrictive material thin plate shown in FIG.
Expands in the electric field direction and contracts in the direction perpendicular to the electric field direction. By such an action, a bending moment as shown by an arrow I in FIG. 3 is generated, and a flexural displacement as shown by a broken line C is generated. At this time, the volume inside the pressure chamber 5 increases, so that the pressure decreases, and ink is filled from the ink supply path communicating with the pressure chamber 5. Immediately after this, by removing the electric field, the flexural displacement is restored to a steady state, so the pressure in the pressure chamber is increased and ink is ejected from the nozzle 3. By configuring the inkjet head as described above, cutting of the electrostrictive material thin plate that is difficult to perform easily,
Not only the steps such as adhesion can be eliminated, but also highly accurate processing that easily obtains the optimum shape by vapor deposition or plating of the electrostrictive elastic thin plate or plating and etching, and the manufacturing cost can be dramatically reduced. it can.

FIG. 4 is a characteristic curve showing the relationship between the thickness of the elastic thin plate 2 (t shown in FIG. 2) and the ink ejection amount for a typical elastic thin plate material. Shows the case where stainless is used, glass is used, and resin material is used for the elastic thin plate 2, respectively. The respective elastic moduli have a relation of >>. In order to obtain the ink ejection amount most efficiently,
It is desirable that the elastic thin plate 2 be hard (high elastic modulus) and have a small thickness t. Therefore, the elastic thin plate 2 is formed of nickel or stainless steel, which has a higher elastic modulus than the electrostrictive material thin plate 1 as shown in the fourth item of the present invention, and the fifth item of the present invention. As shown in (1), it is formed thinner than the electrostrictive material thin plate 1. With such a configuration, it is possible to configure an inkjet head having a high deflection efficiency and suitable for increasing the density of nozzles.

FIG. 5 shows the width of the elastic thin plate 2 (W shown in FIG. 3).
p) and the width of the pressure chamber 5 (Wa shown in FIG. 3) and the crosstalk rate. Width W of elastic thin plate 2
When the ratio of p and the width Wa of the pressure chamber 5 is equal, the crosstalk rate (change rate of ink ejection amount per nozzle when ink is ejected from adjacent nozzles and when ink is not ejected)
Occurs about -30%. However, as shown in FIG. 5, it has been confirmed that the width Wp of the elastic thin plate is made narrower than the width Wa of the pressure chamber 5 to drastically reduce the crosstalk rate. Therefore, as shown in the sixth aspect of the present invention, the width Wp of the elastic thin plate 2 is formed to be about 90% of the width Wa of the pressure chamber 5. With such a configuration, it is possible to suppress the interference between the adjacent nozzle rows, and it is possible to configure an inkjet head having excellent printing quality.

Further, the elastic thin plate 2 is formed of a conductive material as shown in the seventh aspect of the present invention, and has an advantage that the elastic thin plate 2 itself can be used as an electrode.

The details of the second embodiment according to the present invention will be described below with reference to the drawings.

FIG. 6 is a partial cross-sectional view (X-X cross-sectional view of FIG. 11) for explaining the ink jet head shown in the second and third aspects of the present invention. As shown in FIG.
The elastic thin plates 2 are alternately arranged on both surfaces of the electrostrictive material thin plate 1. By generating an electric field in the gap between the positive electrode 7 and the negative electrode 8, the electrostrictive material thin plate 1 expands in the electric field direction and contracts in the direction perpendicular to the electric field direction. By the above action, a bending moment as indicated by an arrow J is generated at the center of the beam, and bending moments as indicated by an arrow K and an arrow L are generated at the fixed end of the beam. In this way, it is possible to obtain the flexible displacement as shown by the broken line D. With such a structure, compared with the conventional structure shown in FIG.
Since the flexible displacement can be generated efficiently,
Ink ejection efficiency can be increased, and high density of nozzles can be sufficiently dealt with. Further, as in the first embodiment of the present invention, the elastic thin plate 2 is made of nickel or stainless steel having a higher elastic modulus than the electrostrictive material thin plate 1 as shown in the fourth item of the present invention. Is formed. Further, as shown in the fifth aspect of the present invention, the elastic thin plate 2 is formed thinner than the electrostrictive material thin plate 1, and has a shape narrower than the pressure chamber 5 as shown in the sixth aspect of the present invention. Is formed in. The elastic thin plate 2 is made of a conductive material as described in the seventh item of the present invention. With such a configuration, it is possible to generate an ideal displacement shape in an inkjet head that causes a flexible displacement, and it is possible to achieve excellent ink ejection efficiency, so that it is possible to increase the density of nozzles. It can be fully realized. Moreover, when a plurality of such inkjet heads are arranged,
By forming an elastic thin plate in advance on a continuous thin plate of electrostrictive material and then joining the thin plate with a base substrate having a plurality of nozzles and ink supply paths, electrostriction that is difficult to perform easily, as in the first embodiment. Not only can processes such as cutting and bonding of thin material plates be eliminated, but it is also easy to perform high-precision processing to obtain an optimum shape by etching or electroplating elastic thin plates on electrostrictive elastic thin plates in advance, which dramatically reduces manufacturing costs. Can be reduced to Further, by combining the hard and thin elastic thin plate with the electrostrictive material thin plate, it is possible to configure an inkjet head suitable for increasing the density of nozzles having high deflection efficiency. Furthermore, it is possible to suppress the interference with the adjacent nozzle rows, and it is possible to configure an inkjet head having excellent printing quality.

The details of the third embodiment according to the present invention will be described below with reference to the drawings.

FIG. 7 is a partial cross-sectional view (X-X cross-sectional view of FIG. 11) for explaining the ink jet head shown in the second and third aspects of the present invention. As shown in FIG.
The elastic thin plates 2 are alternately arranged on both sides of the electrostrictive material thin plate 1, and further, in the width direction of the pressure chamber 5, there is a structural relationship in which the elastic thin plates 2 sandwiching the electrostrictive material thin plate 1 overlap with each other. is doing. With such a configuration, it is possible to obtain a reinforcing effect against the shear stress generated in the thickness direction of the electrostrictive elastic thin plate 1 when the displacement shown by the broken line D in FIG. 6 is generated. Therefore, it is possible to configure a more reliable inkjet head as compared with the second embodiment. Further, it is structurally clear that it also has the effects shown in the first and second embodiments of the present invention.

Hereinafter, a schematic manufacturing process of the ink jet head in the third embodiment of the present invention will be described.

FIG. 8 is a partial perspective view of the base substrate 4. Nozzle 3, ink supply path 6, rectangular groove P that serves as a pressure chamber
A conductive material film to be the negative electrode 8 is formed on the upper surface (thick line hatching portion) of the base substrate 4 integrally molded with. FIG. 9 is a partial perspective view of the electrostrictive elastic thin plate 1 attached to the base substrate 4. On the upper surface of the electrostrictive elastic thin plate 1, a positive electrode 7 made of a conductive material film is formed in a shape substantially equal to the upward projected shape of the rectangular groove P serving as the pressure chamber shown in FIG. An independent electrode pattern corresponding to each pressure chamber 5 formed by laminating the strained material thin plate 1 is formed. On the other hand, a conductive material film serving as a negative electrode is also formed on the lower surface. FIG. 10 is a perspective view of the electrostrictive material thin plate 1 on which the electrode patterning has been completed.
Elastic thin plates 2 having a thickness of 10 to 15 μm are formed on the upper and lower surfaces of the electrostrictive material thin plate 1 by electric field plating so as to form the cross-sectional shape shown in FIG. The composite unit of the electrostrictive material thin plate 1 and the elastic plate 2 thus formed is shown in FIG.
By bonding to the base substrate 4 described above, the main part of the inkjet head as shown in FIG. 11 can be formed. By applying a selective electric signal to the positive electrode 7 and the negative electrode 8 of the main part of the inkjet head, the inkjet head as a component of the printer can be constructed. According to the manufacturing process as described above, not only the steps of cutting and bonding the electrostrictive material thin plate, which are difficult to perform easily, can be eliminated, but also the resist pattern is applied to the electrostrictive material thin plate in advance, and the electrode and the elastic thin plate are vapor-deposited. By plating, high precision machining can be performed relatively easily. Therefore, the manufacturing cost can be dramatically reduced.

[0021]

EFFECTS OF THE INVENTION Low component cost and low manufacturing cost, high ink drop formation efficiency (ink discharge amount / actuator drive voltage), compact size and high drive efficiency capable of realizing high resolution printing. Inkjet head can be configured. Therefore, it is possible to realize a low-cost inkjet printer with excellent printing quality.

[Brief description of drawings]

FIG. 1 is a structural explanatory perspective view of a main part of an inkjet head showing a first embodiment of the present invention.

FIG. 2 is a structural explanatory cross-sectional view of a main part of an inkjet head showing a first embodiment of the present invention.

FIG. 3 is an enlarged cross-sectional view illustrating the structure of the main part of the inkjet head according to the first embodiment of the present invention.

FIG. 4 is a characteristic curve showing the relationship between the thickness of the elastic thin plate (t shown in FIG. 2) and the ink discharge amount for a typical elastic thin plate material, which illustrates the first embodiment of the present invention.

FIG. 5 is a characteristic curve showing the relationship between the ratio of the width of the elastic thin plate (Wp shown in FIG. 2) to the width of the pressure chamber (Wa shown in FIG. 2) and the crosstalk rate, which explains the first embodiment of the present invention. Is.

FIG. 6 is an enlarged cross-sectional view illustrating the structure of a main part of an inkjet head according to a second embodiment of the present invention.

FIG. 7 is an enlarged cross-sectional view illustrating the structure of a main part of an inkjet head according to a third embodiment of the present invention.

FIG. 8 is a partial perspective view of a base substrate 4 illustrating a schematic manufacturing process of an inkjet head according to a third embodiment of the present invention.

FIG. 9 is a partial perspective view of an electrostrictive material thin plate 1 illustrating a schematic manufacturing process of an inkjet head according to a third embodiment of the present invention.

FIG. 10 is a partial perspective view of an electrostrictive material thin plate 1 on which a positive electrode 7 is formed for explaining a schematic manufacturing process of an inkjet head according to a third embodiment of the present invention.

FIG. 11 is a partial perspective view of a main part of an inkjet head according to a third embodiment of the present invention.

FIG. 12 is a structural explanatory cross-sectional view of a main part of an inkjet head showing a conventional example related to the present invention.

FIG. 13 is a structural explanatory top view of a main part of an inkjet head showing a conventional example related to the present invention.

FIG. 14 is a structural explanatory cross-sectional view of a main part of an inkjet head showing a conventional example related to the present invention.

[Explanation of symbols]

 1 Electrostrictive Material Thin Plate 1a Pressure Generating Element 2 Elastic Thin Plate 3 Nozzle 4 Base Substrate 5 Pressure Chamber 6 Ink Supply Path 7 Positive Electrode 8 Negative Electrode 9 Ink Drop

Claims (7)

[Claims] 1. A base substrate having a plurality of nozzles for ejecting ink and an ink supply path, a pressure generating element made of an electrostrictive material thin plate and elastic thin plates having electrodes formed on both sides thereof, the base substrate and the pressure generating device. In an inkjet head having a plurality of pressure chambers formed by bonding elements to each other, and a voltage applying unit that applies a voltage to the pressure generating element, the pressure chambers include the base substrate and a plurality of pressure chambers. Characterized in that the elastic thin plates are formed between the electrostrictive material thin plates that are continuous with each other, and the elastic thin plates are provided on the electrostrictive material thin plate surface for each of the pressure chambers, and form a plurality of the pressure generating elements. Inkjet head to do. 2. A base substrate having nozzles for ejecting ink and an ink supply path, a pressure generating element made of an electrostrictive material thin plate and elastic thin plates having electrodes formed on both surfaces, the base substrate and the pressure generating element. In an ink jet head having a pressure chamber formed by pasting together and a voltage applying means for applying a voltage to the pressure generating element, the elastic thin plate is opposite to the pressure chamber side of the electrostrictive material thin plate and a counter pressure. Inkjet head characterized in that both sides of the chamber are staggered. 3. An ink jet head comprising a plurality of the ink jet heads according to claim 2 arrayed. 4. The elastic modulus of the elastic thin plate is equal to or more than the elastic modulus of the electrostrictive material thin plate.
Alternatively, the inkjet head according to claim 2. 5. The ink jet head according to claim 1, wherein the thickness of the elastic thin plate is equal to or less than the thickness of the electrostrictive material thin plate. 6. The ink jet head according to claim 1, wherein a width of the elastic thin plate is narrower than a width of the pressure chamber. 7. The ink jet head according to claim 1, wherein the elastic thin plate is made of a conductive material.