JPH0757545B2 - INKJET HEAD AND METHOD OF MANUFACTURING THE SAME - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an on-demand type ink jet head using a piezoelectric element, and more particularly to a structure of a multi-nozzle head in which a large number of nozzles are integrated at a high density and a manufacturing method thereof.

[0002]

2. Description of the Related Art On-demand type ink jets have been developed as low-priced printing devices because of their simple structure. The ejection of ink is performed by the deformation of the piezoelectric element, and conventionally, the deformation in the direction perpendicular to the polarization, that is, the piezoelectric strain constant d.
Utilized the deformation caused by ₃₁ . For example, when a conventional head using a unimorph is shown in FIG. 4, the piezoelectric vibrator 102 laminated on the vibration plate 101 is polarized in the direction of (three axes) in the figure, and the electrodes 103 and 104 provided above and below are arranged. By applying a voltage between them, the piezoelectric vibrator is contracted in the (uniaxial) direction, and the diaphragm 101 and the piezoelectric element 102 are bent and deformed like a bimetal to deform the volume of the pressurizing chamber 105. Since the deformation of the piezoelectric element is proportional to the electric field and proportional to the length in the deformation direction, the structure of the conventional example shown in FIG. 4 is thin (3
The electric field is increased by applying a voltage in the (axial) direction, and the deformation is increased by utilizing the displacement in the long (uniaxial) direction of the element.

On the other hand, FIG. 5 shows another conventional example utilizing the deformation of the piezoelectric strain constant d ₃₁ perpendicular to the polarization direction. In this example, the piezoelectric element is arranged perpendicular to the (uniaxial) vibration plate 101,
The diaphragm 101 is bent by the deformation in the (uniaxial) direction.
Also in this example, as in the example of FIG. 4, a voltage is applied in the thin direction and deformation is generated in the long direction so that the drive voltage does not rise.

[0004]

The conventional example described above has the advantage that the drive voltage does not rise relatively, but it is difficult to increase the number of nozzles and to integrate them at high density. For example, if the pressure chambers are integrated to about 10 / mm, in the example of FIG. 4, the length of the piezoelectric element in the (uniaxial) direction becomes short, deformation cannot be taken, and the driving voltage becomes too high. Figure 5
In this example, it is necessary to arrange a large number of piezoelectric elements adjacent to each other, and the adjacent electrodes are not short-circuited, and moreover, 10 pieces / mm
It was technically difficult to arrange them in, and there was almost no mass productivity.

Therefore, it is an object of the present invention to provide a highly integrated multi-nozzle head and an ink jet head having no crosstalk.

Another object of the present invention is to provide a method of manufacturing an ink jet head capable of reliably connecting a piezoelectric element and a vibration plate.

[0007]

An ink jet head of the present invention is constructed by alternately arranging one electrode exposed from one side surface and the electrode of the other pole exposed from the other side surface in a piezoelectric material. The piezoelectric element is fixed to a rigid member, and a groove for separating at least the tip side of the piezoelectric element is formed on the free end side of the piezoelectric element to divide the piezoelectric element into a plurality of elements. Pressurizing means polarized in the same direction so as to have a piezoelectric strain constant d ₃₃ , a vibrating plate abutting the free ends of the plurality of elements and having a peripheral edge supported by the rigid member, and a vibrating plate by the respective elements. And a substrate having nozzle openings for ejecting ink from the pressure chamber.

Further, according to the method of manufacturing an ink jet head of the present invention, one electrode exposed from one side surface and the electrode of the other pole exposed from the other side surface are alternately arranged in the piezoelectric material. Fixing a piezoelectric element having a piezoelectric strain constant d ₃₃ polarized in the same direction as the electric field direction to a rigid member,
A step of forming a groove having a depth on the rigid member side at a predetermined pitch on the free end side of the piezoelectric element to divide a plurality of elements, and a tip of each element and a pressurizing chamber are brought into contact with each other via a vibration plate. And fixing the peripheral portion to the rigid member.

[0009]

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows a cross-sectional view taken in a direction perpendicular to the axis of the flow path as an embodiment of the present invention. Reference numeral 1 denotes a polysulfone substrate having ink channels formed as grooves on its surface. FIG. 1 shows a cross section of the pressurizing chamber 2 in the ink flow path.
The width Wc of the pressurizing chamber is 80 μm, the width Wd is 20 μm, and the pressurizing chambers are arranged at a pitch of 100 μm. The depth Dc of the pressurizing chamber is 30 μm. Reference numeral 3 denotes a polysulfone diaphragm having a thickness of 10 μm, which is laminated on the substrate 1. Reference numeral 4 denotes a piezoelectric element which covers all the pressurizing chambers, which has electrodes 5 and 6 at the top and bottom, and is divided by a groove 7 so as to correspond to each pressurizing chamber, leaving an upper part. The vibrating plate 3 and the piezoelectric element 4 are bonded to an electrode 8 provided on the surface of the vibrating plate 3.

The width W of the portion of the piezoelectric element corresponding to each pressurizing chamber
p is 50 μm, length Lp is 300 μm, distance between electrodes Le
Is 350 μm. 9 is the piezoelectric element 4 via the electrode 10.
Is a rigid member laminated on the electrode 5 and has both ends bent in a U-shape and adhered to the diaphragm 3 and has a thickness Lg sufficiently larger than the thickness of the diaphragm 3. In this example, Lg is 1 mm
Is.

A method of manufacturing the above-mentioned structure will be described with reference to FIG.

The substrate 1 is made by injection molding, and ink flow paths such as the nozzle 11, the supply passage 12, the supply pipe 13 and the like are formed together with the pressurizing chamber 2. Then, the vibrating plate 3 is solvent-bonded to the surface to form a head body. A metal thin film is sputtered on the surface of the diaphragm 3 and an electrode 8 as shown in the figure is formed by etching. On the other hand, the rigid member 9 is formed by injection molding of polysulfone, and the electrode 10 is formed on the lower surface by sputtering. Further, the piezoelectric material 40 having the electrodes 5 and 6 on the upper and lower surfaces is adhered to the rigid member 9, and the groove 7 is formed with a diamond saw to form the piezoelectric element 4. Further, the rigid member 9 and the piezoelectric element 4 are adhered to the vibrating plate 3, and wiring from a control circuit (not shown) is performed on the rear portion 8-1 of the electrode 8.

Although the heads having four nozzles are shown in the embodiments of FIGS. 1 and 2, in reality, there are 24 nozzles to 200 nozzles.
A zero nozzle head can be created.

Next, the operation of the above embodiment will be described.

The flow path is filled with ink and the electrodes 8 and 1 are filled.
When a drive signal from a control circuit (not shown) is applied during 0, a voltage is applied to the piezoelectric element 4 via the electrodes 5 and 6. At this time, if the voltage is V, the piezoelectric element 4 has ε
A strain of = d ₃₃ V / Le is generated, which causes the diaphragm 3 to bend and pressurizes the ink in the pressurizing chamber 2 to eject the ink from the nozzle 11 for recording. Since the thickness Lg of the rigid member 9 is 100 times that of the diaphragm 3, the bending rigidity is 100 ³ = 10 ⁶ times, and almost all deformation of the piezoelectric element 4 is transmitted to the diaphragm 3. Generally, the bending rigidity of the rigid member should be 100 times or more that of the diaphragm.

As can be seen from the above embodiment, by utilizing the deformation of the piezoelectric element in the polarization direction, it is possible to easily arrange the piezoelectric elements for a large number of pressurizing chambers, and it is possible to highly integrate the multi-nozzle head.

The value of the piezoelectric strain constant d33, which is the same as the polarization direction, is usually two to three times the value of the piezoelectric strain constant d31 perpendicular to the polarization direction, so that the distance between the electrodes 5 and 6 is relatively long. Nevertheless, there is an advantage that distortion can be taken large.

In the above embodiment, the electrodes 5, 6, 8, 1
0 is provided, but electrode 5 and electrode 10, electrode 6 and electrode 8
It is possible to reduce the number of electrodes by using the same member. If the rigid member 9 is made of metal, it can also serve as the electrode 10. In addition, the groove 7 is partly inserted in the piezoelectric element 4,
This is to increase the bonding strength of the piezoelectric element 4 and the rigid member 9. If the bonding strength is sufficient, the mutual influence of adjacent piezoelectric elements may be reduced, and in order to reduce the voltage loss, the piezoelectric elements may be cut until all are separated.

FIG. 3 shows a cross section taken along a flow path as another embodiment of the present invention. Unlike the embodiment shown in FIGS. 1 and 2, the piezoelectric element 20 is formed by laminating nine layers of 50 μm elements, and electrodes 21 and 22 are provided between the elements. The piezoelectric element 20 is arranged in a rectangular shape in the longitudinal direction of the pressure chamber 2, and
1, 2 and 22 are formed in a comb shape from the supply path side and the nozzle side, and are alternately laminated. The electric field applied to the piezoelectric element is about 1/9 of that of FIG. 1, which is 10 V or less, compared with the example of FIG.
When a large number of nozzles such as 00 nozzles are driven, it is advantageous in terms of a driver IC.

[0021]

As described above, according to the present invention, since the peripheral portion of the diaphragm on the pressure chamber is fixed by the rigid member, the deflection of the substrate having the pressure chamber due to the pressure applied to the pressure chamber. Deformation can be prevented and crosstalk can be prevented. Further, by alternately stacking the electrodes of the piezoelectric element in a comb shape in the longitudinal direction of the pressure chamber, the pressure chamber can be arranged at high density.
Nevertheless, the displacement can be made large and the influence of the variation in the electrode position can be reduced.

Further, according to the manufacturing method of the present invention, by fixing the peripheral portion of the diaphragm with the rigid member, the deflection of the diaphragm can be corrected, and the tip of the piezoelectric element is evenly contacted with the diaphragm. Can be contacted.

[Brief description of drawings]

FIG. 1 is a sectional view of FIG. 2 showing an embodiment of an inkjet head of the present invention.

FIG. 2 is a perspective view showing an embodiment of the inkjet head of the present invention.

FIG. 3 is a perspective view showing another embodiment of the inkjet head of the present invention.

FIG. 4 is a schematic sectional view of a conventional inkjet head.

FIG. 5 is a schematic sectional view of a conventional inkjet head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... Pressurizing chamber 3 ... Vibration plate 4, 20 ... Piezoelectric element 5, 6, 8, 10, 21, 22 ... Electrode 7 ... Groove 9 ... Rigid member 11 ... Nozzle 12 ... Supply path

Claims (3)

[Claims] 1. A piezoelectric element, which is configured by alternately arranging one electrode exposed from one side surface of the piezoelectric material and the other pole electrode exposed from the other side surface in a piezoelectric material, is fixed to a rigid member,
A groove is formed on the free end side of the piezoelectric element for separating at least the tip side thereof to divide the element into a plurality of elements, and the piezoelectric material is polarized in the same direction as the electric field direction between the electrodes to generate a piezoelectric strain constant d. A pressurizing means having ₃₃ , a vibrating plate which is in contact with the free ends of the plurality of elements and whose peripheral edge is supported by the rigid member, and a pressurizing chamber which is pressurized by the respective elements through the vibrating plate. And a substrate having a nozzle opening for ejecting ink from the pressure chamber, 2. The piezoelectric element is arranged in a rectangular shape in the longitudinal direction of the pressurizing chamber, and the electrodes are alternately laminated in a comb shape from both side surfaces in the longitudinal direction of the piezoelectric element. Item 2. The inkjet head according to item 1. 3. A piezoelectric strain in which one electrode exposed from one side surface thereof and an electrode of the other pole exposed from the other side surface thereof are alternately arranged in the piezoelectric material and polarized in the same direction as the electric field direction between the electrodes. Fixing a piezoelectric element having a constant d ₃₃ to a rigid member; forming a groove on the free end side of the piezoelectric element having a depth on the rigid member side at a predetermined pitch to divide the plurality of elements; A method of manufacturing an inkjet head, comprising the step of bringing the tip of each element into contact with the pressure chamber via a vibration plate and fixing the peripheral edge portion to the rigid member.