JPH04259563A - Ink jet head and its manufacture - Google Patents

Abstract

PURPOSE:To provide a high releable ink jet head which is high in density and high in a number of nozzles. CONSTITUTION:Piezoelectric substrates 20, 21 made from piezoelectric material polarized in the thickness direction are joined to each other symmetrically by placing the joined part 30 between them so that polarization directions 50, 51 become an opposed direction to each other to form a laminate substrate. Thereafter, a passage 5 and an electrode layer 40 are formed on the laminate substrate.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet head for selectively depositing ink droplets onto an image recording medium.

0002

[Prior Art] The structure of a conventional inkjet head is as follows:
JP-A-63-252750 or JP-A-63
It is disclosed in the publication No.-247051.

As shown in FIG. 16, these inkjet heads have a large number of parallel channels 235 spaced apart from each other in the direction in which the nozzles are arranged, and these channels are arranged in the longitudinal direction of the channels and in the longitudinal direction. It is divided by side walls 236 extending perpendicularly to both nozzle arrangement directions. One end of these channels is connected to a nozzle plate 2 having a plurality of nozzles 3, and the other end is connected to an ink supply means 209 for replenishing each channel with ink. The side wall 236 is partially or entirely composed of a piezoelectric material, and causes deformation parallel to the array direction such as a shear mode using an electric actuator, and changes the pressure of the ink by using the flow path as the pressure generating chamber 5 and the nozzle 3. It was designed to eject ink droplets from. Moreover, as shown in FIG. 17, the manufacturing method includes a piezoelectric ceramic substrate 220 polarized in the thickness direction.
A process of forming a plurality of parallel channels 235 on the top, and forming side walls 236 that partition adjacent channels 235, as shown in FIG.
16, a step of forming an electrode layer 240 for each channel, and FIG.
As shown in , an upper substrate 221 and a lower substrate 222 made of piezoelectric ceramic substrates subjected to the above process are stacked so that the flow channels of both substrates face each other and overlap, and the electrode layer 241 of the upper substrate and the electrode layer 242 of the lower substrate are stacked. This consisted of a step of joining and fixing both substrates so that they are electrically connected at the surface portions 243 to form the pressure generating chamber 5.

0004

[Problems to be Solved by the Invention] However, after forming flow channels that will become pressure generation chambers on the upper substrate and the lower substrate, and forming electrode layers for causing deformation on the side walls that partition each pressure generation chamber. The conventional technique of joining and fixing an upper substrate and a lower substrate so that their flow paths overlap had the following problems.

(i) The relative positional accuracy between both members must be sufficiently high.

(ii) During joining and fixing, the side wall portion, which is weak in strength, is likely to be destroyed.

(iii) The adhesive material blocks the flow path during bonding and fixing.

(iv) The upper and lower electrodes must be connected.

The object of the present invention is to solve these problems, and the purpose is to eliminate the need to bond the upper and lower substrates on which flow channels and electrodes are formed. Our objective is to provide an inkjet head with high density, high number of nozzles, and high reliability.

0010

[Means for Solving the Problems] A first inkjet head according to the present invention has a large number of parallel channels spaced apart from each other in the direction in which the nozzles are arranged, and the top, bottom, and side walls of these channels are Electrodes are formed on a part or all of the surface, and the side wall is made of a piezoelectric material, and the pressure in the channel is changed by deformation of the side wall by electrical actuating means. This is an inkjet head that ejects ink droplets from a nozzle formed at one end, and the piezoelectric substrates are made of piezoelectric material polarized in the thickness direction, and the polarization directions are opposite to each other with a joint between them. The present invention is characterized in that after symmetrically bonding to form a laminated substrate, flow channels and electrodes are formed on this laminated substrate.

Further, in the second inkjet head according to the present invention, the piezoelectric substrates of the laminated substrate are piezoelectric substrates having different thicknesses, and the flow path is formed from the thin piezoelectric substrate side, and the flow path is formed from the thin piezoelectric substrate side. The depth of the path is equal to the thickness of the thin piezoelectric substrate.

Further, in the third inkjet head according to the present invention, the laminated substrate is formed by laminating two piezoelectric substrates of equal thickness on a base substrate so that polarization directions are opposite to each other, and A path is formed at a depth reaching the base substrate from the surface of the piezoelectric substrate. Further, the fourth inkjet head is characterized in that the base substrate is made of an insulating material having a lower dielectric constant than the piezoelectric material.

Furthermore, the method for manufacturing an inkjet head according to the present invention has a large number of parallel channels spaced apart from each other in the direction in which the nozzles are arranged, and the top, bottom, and
and an electrode is formed on a part or the entire surface of the side wall, the side wall is partially or entirely composed of a piezoelectric material, and the pressure in the flow path is changed by deformation of the side wall by electrical actuating means. , a method for manufacturing an inkjet head in which ink droplets are ejected from a nozzle formed at one end of a flow path, in which piezoelectric substrates made of piezoelectric material polarized in the thickness direction are sandwiched between piezoelectric substrates whose polarization directions are mutually opposite to each other with a joint between them. a step of bonding in opposite directions to form a laminated substrate; a step of forming a large number of parallel channels having intervals from each other on the surface of the laminated substrate; and an inner surface of the flow path formed in the laminated substrate. The method is characterized by comprising a step of forming an electrode layer, and a step of bonding a substrate to the surface of the laminated substrate on which the flow path and the electrode layer are formed.

[0014]

[Operation] According to the above structure of the inkjet head of the present invention, the piezoelectric material forming the side wall that partitions the flow path serving as the pressure generating chamber is symmetrical with respect to the joint, so that when the side wall is deformed, the piezoelectric material A highly efficient actuator can be constructed. Further, by using an insulating material having a lower dielectric constant than a piezoelectric material for the base substrate, it is possible to suppress the bonding between the electrodes formed in each pressure generating chamber.

Furthermore, according to the method of manufacturing an inkjet head of the present invention, the side walls that define the flow paths that become the pressure generating chambers are formed after the piezoelectric substrates are bonded, so that the relative positional accuracy is automatically adjusted during processing. guaranteed. In addition, the adhesive layer of the piezoelectric substrate does not block the flow path, and the substrate strength during bonding and fixation is high and sufficient adhesive strength can be ensured. Furthermore, since the electrode layer is formed after the sidewall is formed, there is no need to bond the electrode layer within the pressure generating chamber.

[0016]

EXAMPLES Examples of the present invention will be described in detail below.

In the drawings used in the following description, arrows within the piezoelectric material indicate polarization directions.

(First Embodiment) In FIG. 1, a piezoelectric material made of lead zirconate titanate is polarized in the thickness direction.
A 400 μm thick piezoelectric substrate 20 and a 1 mm thick piezoelectric substrate 21 were bonded together using a polyimide substrate bonding layer 30 such that their polarization directions 50 and 51 were opposite to each other to form a laminated substrate 11. As shown in FIG. 2, the laminated substrate 11 is cut to a depth of 800μ using a diamond cutting disk.
A large number of parallel grooves each having a width of 100 μm and a width of 100 μm were formed in parallel with each other at a pitch of 169 μm to form a large number of parallel channels 35. Thin piezoelectric substrate 2 constituting the laminated substrate 11 for cutting
Start from the 0 side and adjust the depth of the groove to the thickness 4 of the thin piezoelectric substrate 20.
By setting the thickness to twice 00 μm, the deformed portions 36, which are side walls that partition adjacent flow channels, can be formed symmetrically with respect to the substrate bonding layer 30. In this embodiment, since the substrate bonding layer 30 made of polyimide is sufficiently thin compared to the thickness of the piezoelectric substrate 20, the groove depth is set to twice that of the piezoelectric substrate 20. However, if the substrate bonding layer 30 is thick, By adding the thickness of the layer 30 to the groove depth, the deformed portion 36 can be formed symmetrically with respect to the substrate bonding layer 30. As shown in FIG. 3, on the grooved multilayer substrate 111, an electrode layer 40 is formed by vapor deposition on the inner surface of the channel 35, and after removing unnecessary electrode parts, a polyimide strip seal with ink liquid tightness is applied. The pressure generating chamber 5 was formed by bonding the alumina substrate 25 with a thickness of 400 μm using the bonding seal layer 45 consisting of the following. The pressure generating chamber 5 formed by the process of FIGS. 1 to 3 is connected to the nozzle 3 formed on the nozzle plate 2 and the ink supply means 9 as shown in FIG. 4, and the electrode layer 40 is electrically connected as shown in FIG. By connecting to the actuating means 70,
An inkjet head is configured.

Next, the principle of operation of the ink jet head using the pressure generating chamber of this embodiment will be outlined with reference to FIGS. 5 and 6. In FIG. 5, electrodes 40a and 40b formed in the pressure generating chamber 5 are electrically connected, and a driving driver element 70, which is an electrical actuating means, is connected for each flow path.
It is connected to the. The driver element 70 selectively supplies high voltage output or low voltage output from the DC power supply 73 to the electrodes 40 in each pressure generating chamber 5 in response to a control signal 72 from the control unit 71 . Each pressure generating chamber 5 is grouped into two groups (even numbered and odd numbered), and each group is divided by time and driven alternately. As shown in FIG. 6, the deformed portion 3 is a side wall that partitions a selected pressure generating chamber 5a and its adjacent pressure generating chambers 5b, 5b.
6, 36, when the driver elements connected to the selected pressure generating chamber 5a and its adjacent pressure generating chambers 5b, 5b are controlled so as to be perpendicular to the polarization directions 50, 51 of the piezoelectric material, the piezoelectric material The deformed portion 36 deforms as shown in the shear mode. Due to this deformation, the volume of the selected pressure generating chamber 5a is reduced, and pressure is generated in the ink 6 filling the pressure generating chamber 5a. The generated pressure is transferred to the pressure generation chamber 5.
The ink droplets propagate through the inside of a and eject ink droplets from the nozzle (see FIG. 4).

The basic operating principle is the same in the embodiments described below.

(Second Embodiment) In FIG. 7, a piezoelectric material of lead zirconate titanate polarized in the thickness direction is shown.
Piezoelectric substrates 20 and 22 with a thickness of 400 μm and a thickness of 1.5 mm
The piezoelectric substrates 21 were bonded together with a polyimide substrate bonding layer 30 such that their polarization directions 50 and 51 were opposite to each other at the bonding surface, thereby forming a laminated substrate 13. Laminated board 1
3, as shown in FIG.
A large number of parallel grooves each having a width of 100 μm were formed parallel to each other at a pitch of 169 μm on both sides of the laminated substrate 13 while being shifted by 1/2 pitch, thereby forming a large number of parallel channels 35. The depth of the cutting groove is 400 mm, which is the thickness of the thin piezoelectric substrates 20 and 22.
By setting the thickness to twice μm, the deformed portions 36, which are side walls that partition adjacent flow channels, can be formed symmetrically with respect to the substrate bonding layer 30. As shown in FIG. 9, on the grooved multilayer substrate 113, an electrode layer 40 is formed by vapor deposition on the inner surface of the channel 35, and after removing unnecessary electrode parts, a polyimide strip seal with ink liquid tightness is applied. The pressure generating chamber 5 was formed by bonding the alumina substrate 25 with a thickness of 400 μm using the bonding seal layer 45 consisting of the following.

(Third Embodiment) In FIG. 10, piezoelectric substrates 20 and 23 with a thickness of 400 μm and a piezoelectric substrate 23 with a thickness of 600 μm are made of a piezoelectric material of lead zirconate titanate polarized in the thickness direction.
m piezoelectric substrates 21 and 22 are bonded with a polyimide substrate bonding layer 30 so that their polarization directions 50 and 51 are opposite to each other at the bonding surface and are symmetrical across the alumina substrate 26 that is the base substrate, and the laminated substrate 14 was constructed. For the laminated substrate 14, as shown in FIG.
μm, parallel grooves with a width of 100 μm and a width of 169 μm parallel to each other.
A large number of parallel channels 35 were formed at a pitch of 1/2 pitch on both sides of the laminated substrate 14. As shown in FIG. 12, on the grooved multilayer substrate 114, an electrode layer 40 is formed by vapor deposition on the inner surface of the channel 35, and after removing unnecessary electrode parts, a polyimide strip seal with ink liquid tightness is applied. A 400 μm thick alumina substrate 25 was bonded using a bonding seal layer 45 consisting of the following, to form a pressure generating chamber 5. In the configuration in which the pressure generating chambers 5 are formed on both sides of the laminated substrate 114 as in this embodiment, the laminated substrate 1
By laminating a material having a sufficiently lower dielectric constant than the piezoelectric material as the base substrate 26 between the pressure generating chambers 5 on both sides of the base substrate 26, the electrical coupling between the pressure generating chambers 5 on both sides of the base substrate 26 is reduced. It has become possible to sufficiently reduce crosstalk.

(Fourth Embodiment) In FIG. 13, piezoelectric substrates 20, 21, 22, and 23 of equal thickness made of a piezoelectric material of lead zirconate titanate polarized in the thickness direction and an alumina substrate serving as a base substrate are shown. 26, its polarization direction 50,
The laminated substrate 15 was constructed by bonding the piezoelectric materials using a polyimide substrate bonding layer 30 such that the bonding surfaces of the piezoelectric materials 51 were in opposite directions. As shown in FIG. 14, the laminated substrate 15 is made by using a diamond cutting disk to cut parallel grooves on both sides of the laminated substrate 15 parallel to each other to a depth that reaches the alumina substrate 26. A large number of parallel flow paths 35 were formed by shifting the positions by /2 pitches and performing a large number of processing operations. The piezoelectric substrates 20, 21, 22, and 23 made of piezoelectric materials bonded to each other have the same thickness, and the piezoelectric substrate 2
By cutting over the thicknesses of 0, 21, 22, and 23, the deformed portions 36, which are part of the side walls that partition adjacent flow channels, can be formed symmetrically with respect to the substrate bonding layer 30. The laminated substrate 115 in which grooves are formed is shown in FIG.
As shown in , an electrode layer 40 is deposited on the inner surface of the channel,
After removing unnecessary electrode parts, the alumina substrate 25 was bonded using a bonding seal layer 45 made of a polyimide strip seal having ink liquid tightness to form the pressure generating chamber 5. In the configuration in which the pressure generating chambers 5 are formed on both sides of the laminated substrate 115 as in this embodiment, by using alumina as the material of the base substrate 26, which has a sufficiently lower dielectric constant than the piezoelectric material, the pressure generation chambers 5 on both sides of the base substrate 26 are Electrical coupling between the pressure generating chambers 5 is reduced, making it possible to sufficiently reduce crosstalk. Furthermore, since the piezoelectric material is used only in the deformable portion 36, it is economical and provides strength and processing stability. Furthermore, since the flow path depth can be designed independently of the amount of volume change of the pressure generating chamber 5, the degree of freedom in flow path resistance design increases and optimization design becomes easy.

[0024]

According to the present invention, by forming a flow channel and an electrode layer after bonding piezoelectric substrates polarized in the thickness direction, it is possible to improve the relative positioning of the flow channel at the top and bottom and the electrode layer. The effect is that bonding of layers becomes unnecessary. Furthermore, the adhesive layer does not block the flow path when piezoelectric substrates are bonded, and the substrates are not destroyed during bonding.

It is also possible to bond piezoelectric substrates with different thicknesses and form a flow path from the thinner piezoelectric substrate side so that the depth of the flow path in the thicker piezoelectric substrate is equal to the thickness of the thinner piezoelectric substrate, or Two piezoelectric substrates of equal thickness are stacked on the
By forming the flow path at a depth that reaches the base substrate from the surface of the piezoelectric substrate, it is possible to easily form a structure in which the piezoelectric material of the side wall that defines the flow path that becomes the pressure generation chamber is symmetrical with respect to the joint portion.

Furthermore, by using an insulating material having a lower dielectric constant than the piezoelectric material as the material of the base substrate, it is possible to suppress electrical coupling between the electrodes formed in each pressure generating chamber.

[Brief explanation of the drawing]

FIG. 1 is a process diagram showing a first embodiment of an inkjet head and a method for manufacturing the same according to the present invention.

FIG. 2 is a process diagram as well.

FIG. 3 is a process diagram as well.

FIG. 4 is a process diagram as well.

FIG. 5 is an explanatory diagram of the operating principle of the inkjet head according to the present invention.

FIG. 6 is a diagram explaining the principle of operation.

FIG. 7 is a process diagram showing a second embodiment of an inkjet head and a method for manufacturing the same according to the present invention.

FIG. 8 is a process diagram as well.

FIG. 9 is a process diagram as well.

FIG. 10 is a process diagram showing a third embodiment of an inkjet head and a method for manufacturing the same according to the present invention.

FIG. 11 is a process diagram as well.

FIG. 12 is a process diagram as well.

FIG. 13 is a process diagram showing a fourth embodiment of an inkjet head and a method for manufacturing the same according to the present invention.

FIG. 14 is a process diagram as well.

FIG. 15 is a process diagram as well.

FIG. 16 is a process diagram showing a conventional inkjet head and its manufacturing method.

FIG. 17 is a process diagram as well.

FIG. 18 is a process diagram as well.

[Explanation of symbols]

2 Nozzle plate 3 Nozzle 5 Pressure generation chamber 9 Ink supply means 20, 21, 22, 23 Piezoelectric substrate 26 Base board 30　Substrate bonding layer 35 Flow path 36 Side wall (deformed part) 40 Electrode layer 50, 51 Polarization direction

Claims (5)

[Claims] Claim 1: A large number of parallel flow channels spaced apart from each other in the direction in which the nozzles are arranged, electrodes are formed on a part or the entire surface of the side walls of these flow channels, and the side wall is partially or entirely An inkjet head made of a piezoelectric material and configured to eject ink droplets from a nozzle formed at one end of the flow path by changing the pressure within the flow path by deforming the side wall by electrical actuating means, the head having a thickness of Piezoelectric substrates made of piezoelectric materials polarized in the transversal direction are symmetrically bonded to each other so that the polarization directions are opposite to each other across the bonded portion to form a laminated substrate. An inkjet head characterized by forming electrodes. 2. The piezoelectric substrates of the laminated substrate are piezoelectric substrates having different thicknesses, the flow path is formed from the thin piezoelectric substrate side, and the depth of the flow path in the thick piezoelectric substrate is equal to that of the thin piezoelectric substrate. Claim 1 characterized in that the thickness is equal to
The inkjet head described. 3. The laminated substrate is formed by laminating two piezoelectric substrates having the same thickness on a base substrate such that polarization directions are opposite to each other, and the flow path extends from the surface of the piezoelectric substrate to the base substrate. The inkjet head according to claim 1, wherein the inkjet head is formed to a depth that reaches the substrate. 4. The ink jet head according to claim 3, wherein the base substrate is made of an insulating material having a lower dielectric constant than the piezoelectric material. 5. A large number of parallel flow channels spaced apart from each other in the direction in which the nozzles are arranged, electrodes are formed on a part or the entire surface of the side walls of these flow channels, and the side wall is partially or entirely A method for manufacturing an inkjet head comprising a piezoelectric material, in which the pressure within the channel is changed by deformation of the side wall by electrical actuating means, and ink droplets are ejected from a nozzle formed at one end of the channel. a step of bonding piezoelectric substrates made of piezoelectric materials polarized in the thickness direction so that the polarization directions are opposite to each other across the bonding portion to form a laminated substrate; a step of forming a large number of parallel channels having intervals from each other; a step of forming an electrode layer on the inner surface of the channel formed in the laminated substrate; and a step of forming the multilayer substrate on which the channel and the electrode layer are formed. 5. The method for manufacturing an inkjet head according to claim 1, further comprising the step of bonding a substrate to the surface of the inkjet head.