JPH03108553A - Ink jet head - Google Patents

Abstract

PURPOSE:To increase the displacement of a pressure generation member and improve the frequency response and the jetting stability by a method wherein the pressure generation member is a beam-form member composed of an elastic material and a piezoelectric material having a part less than half in width than the elastic material, and the pressure generation member is supported at both longitudinal ends thereof. CONSTITUTION:A pressure generation member 12 consists of a piezoelectric material 14 and an elastic material 13 and has a center beam structure in the longitudinal direction thereof. A nozzle 10 is formed on the bottom of an elliptically recessed part 17 provided in a recessed groove part 16. The pressure generation member 12 is a beam-form member composed of the elastic material 13 and the piezoelectric material 14 having a part less than half in width than the elastic material 13. In this manner, the displacement of the pressure generation member 12 can be efficiently obtained. An ink jet head having superior frequency response and jetting stability as well as ensuring adequate ink drop jetting speed and amount can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an inkjet recording apparatus such as a printer that ejects ink droplets to form an ink image on a medium such as recording paper, and more particularly relates to relates to inkjet printer heads.

[Prior Art] A pressure generating member supported at both ends in the longitudinal direction of a beam-like member made of a pressure member such as PZT, a metal plate, and a laminated material of ceramic, ink as a flying medium, and this ink. An on-demand inkjet head, which has a nozzle as an ejection port, generates pressure from a pressure generator using an applied voltage, and projects ink from the nozzle, was developed in the Japanese Patent Publication No. 6
No. 0-8953. An inkjet head with this structure has low running costs because the pressure generator operates to eject ink only when it is necessary to eject ink, it is easy to have multiple nozzles, and because both ends are fixed. This has advantages such as a stable gap.

In the prior art, in the pressure generating member, the width of each part of the elastic plate and the piezoelectric material was always the same. Therefore, the displacement cannot be obtained effectively, and the characteristics such as the ejection speed, ejection amount, and ejection response of the ink droplet are also affected accordingly. The problem is that it has to be done.

Therefore, in order to solve these conventional problems, the present invention increases the displacement of the pressure generating member, ensures sufficient ejection speed and amount of ink droplets, and has excellent frequency response and ejection stability. Our goal is to provide inkjet heads.

Further, since the conventional pressure generating member was made of bulk material, the piezoelectric material was thick, so displacement could not be obtained effectively. In addition, in order to effectively obtain displacement, the beam must be made longer, resulting in an increase in the size of the head itself.

SUMMARY OF THE INVENTION In order to solve these conventional problems, the present invention aims to provide a head that can effectively obtain displacement by thinning the piezoelectric member and that is also miniaturized.

[Means for Solving Problem i] The inkjet head of the present invention is an inkjet head that ejects ink to form an ink image on a recording medium, and the inkjet head includes a nozzle as the ink ejection opening; Pressure is applied to the ink as a flying medium.

The pressure generating member includes a pressure generating member and a voltage applying means for applying a voltage for generating pressure to the pressure generating member, and the pressure generating member is made of an elastic material and has a width of 1/2 or less of the width of the elastic material. The pressure generating member is a beam-like member having a piezoelectric material as a component, and is characterized in that both ends of the pressure generating member in the longitudinal direction are supported. Furthermore, the thickness of the piezoelectric material is 50 μm or less. Furthermore, the pressure generating member is arranged to face the nozzle. Furthermore, a plurality of the nozzles and the pressure generating member are arranged in one-to-one correspondence.

[Function] According to the above structure of the present invention, since the piezoelectric member of the pressure generating member has a portion whose width is 1/2 or less of the width of the elastic material, the displacement of the pressure generating member can be effectively obtained. west,
It is possible to provide an inkjet head with excellent frequency response and ejection stability while ensuring sufficient ejection speed and amount of ink droplets.

Furthermore, by forming the pressure generating member from a thin film, the beam can be shortened and the applied voltage can be reduced. Thereby, it is possible to reduce the size and cost.

[Example] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic perspective view of a printer using an inkjet head according to an embodiment of the present invention. 100 is an inkjet head of the present invention, and 101 is its power line. 200 is a recording paper, and 300 is a platen. By rotating the platen 300 in the direction of arrow P in the figure, the recording paper 200 is fed in the direction of arrow M in the figure. At this time, the inkjet head 100 forms an ink image on the recording paper 200 while moving in the direction of arrow H in the figure.

FIGS. 2(a) and 2(b) are a sectional view and a top view of the main parts of an inkjet head according to an embodiment of the present invention.

As shown in FIG. 2(a), the pressure generating member 12 has three
It is made of a piezoelectric material 14 having a thickness of about 0 μm and an elastic material 13 having a thickness of about 15 μm, and has a structure of a double-supported beam with a length of 2 mm in the longitudinal direction. The nozzle 10 is formed on the bottom surface of an elliptical recess 17 provided in the recessed groove 16.

As shown in FIG. 2(b), nozzles 1o are arranged on the nozzle forming substrate 11 at intervals of 0.33 mm. The width of the piezoelectric material 14 is 250μ at the central wide part 14a.
The thin portions 14b at both ends have a width of 30 μm. Note that the corner between 14a and 14b is rounded or tapered to prevent stress concentration.

Further, the elastic material 13 has a width of 250 μm. A portion 14a of the piezoelectric material 14 has a length of about 1.5 mm at the center of the beam.

In this way, by widening the width of the piezoelectric material near the nozzle and narrowing the width of the mounting portion, the displacement of the pressure generating member can be effectively obtained.

Further, as shown in FIG. 2(a), the nozzle forming substrate 11 stores ink 30 in a concave groove 16 and an elliptical depression 17 having a depth of about 10 μm.

As shown in equation (1), the displacement δ of the pressure generating part with a double-supported beam structure is determined by the square of the length L in the longitudinal direction and the electric field strength E.
and inversely proportional to the thickness T.

δcc12E/l... (1) Also, (2)
As shown in the equation, the vibration period ω has a characteristic that it is proportional to the thickness T and inversely proportional to the square of the length L in the longitudinal direction.

ωccT/L2 (2) Therefore, by configuring the pressure generating member 12 according to this embodiment to be thinner than the conventional pressure generating unit, the required displacement can be obtained at a lower voltage. Is possible.

Furthermore, if the ratio between the thickness T and the square of the length L in the longitudinal direction is constant, it is possible to obtain the same vibration period ω and displacement δ. Even if the length in the longitudinal direction is shortened by reducing the thickness of the pressure generating member 12 according to the embodiment, it is possible to obtain equivalent ink ejection characteristics.

This embodiment is characterized in that the piezoelectric material 14 has a thickness of 50 μm or less, so that the required displacement can be effectively obtained.

FIGS. 3A to 3C are perspective views showing the manufacturing process of an inkjet head according to an embodiment of the present invention.

The heat-resistant resist 20 shown in FIG. 3(a) fills the concave groove 16 of the nozzle forming substrate 11, the elliptical depression 17 formed on the lower surface thereof, and the nozzle 10.

In FIG. 3(b), an elastic material 13Ji is deposited or plated to a thickness of about 15 μm, and 14 layers of piezoelectric material are 30 μm thick.
The figure shows a state in which the film is deposited to a thickness of about 100 m.

In FIG. 3(c), the attachment of the 14 layers of piezoelectric material is shown in section 14.
In order to make b thinner, the extra part of the 14 layers of piezoelectric material is
Remove by etching.

After that, in order to make each pressure generating member 12 independent, the portion 18a in FIG. 3(b) is cut and removed, and each pressure generating member 1 is made independent as shown in FIG.
A groove 18b is created between the two.

Finally, the heat-resistant resist 20 filling the concave groove 16 of the nozzle forming substrate 11, the elliptical depression 17, and the nozzle 10 is removed by cleaning with a solvent.

In this way, the inkjet head according to the present invention allows a plurality of units to be manufactured simultaneously in a continuous process.

FIG. 4 is a perspective view of an inkjet head showing a second embodiment of the present invention. The pressure generating member 12 has a thickness of 30μ
It consists of a piezoelectric material 14 having a thickness of about m and an elastic material 13 having a thickness of about 15 μm, and has a length of 2 mm in the longitudinal direction.
It has a double-sided beam structure. The width of the piezoelectric material 14 is 250 μm at the wide portions 14d at both ends, and 30 μm at the narrow portion 14c at the center. Further, the elastic material 13 has a width of 250 μm. The narrow portion 14c of the piezoelectric material 14 has a length of approximately 7 mm at the center of the beam. Wide part 14d and narrow part 14
In order to prevent stress concentration between C and C, a corner is rounded and tapered.

By doing so as well, the displacement of the pressure generating member 12 can be effectively obtained.

Further, the manufacturing method is the same as in the first embodiment described above.

[Effects of the Invention] As described above, in the inkjet head of the present invention, since the piezoelectric material has a portion whose width is 1/2 or less of the width of the elastic material, it is possible to efficiently obtain displacement of the pressure generating member. This makes it possible to provide an inkjet head with excellent frequency response and ejection stability while ensuring sufficient ejection speed and amount of ink droplets. In addition, by creating the pressure generating part using a thin film, the beam can be shortened, thereby reducing the applied voltage, enabling miniaturization and high integration, and improving performance. Moreover, costs can be reduced.

[Brief explanation of drawings]

FIG. 1 is a schematic perspective view of a printer using an inkjet head according to an embodiment of the present invention. FIG. 2(a) is a sectional view of the main parts of an inkjet head according to an embodiment of the present invention. and FIG. 2(b) is a top view of the main parts of an inkjet head according to an embodiment of the present invention. FIGS. 3A to 3C are perspective views showing the manufacturing process of an inkjet head according to an embodiment of the present invention. FIG. 4 is a perspective view of an inkjet head showing a second embodiment of the present invention. 100... Inkjet head 101... Power line 200... Recording paper 300... Platen 10... Nozzle 11... Nozzle forming substrate 12... Pressure generating member 13 ...Elastic material 14...Piezoelectric material 20...Resist or higher

Claims (4)

[Claims] (1) In an inkjet head that flies ink to form an ink image on a recording medium, the inkjet head includes a nozzle as the ink ejection opening and a pressure generating member that applies pressure to the ink as the flying medium. , a voltage applying means for applying a voltage for generating pressure to the pressure generating member, and the pressure generating member is made of an elastic material;
A beam-like member having as a component a piezoelectric material having a portion whose width is 1/2 or less of the width of the elastic material, and characterized in that both longitudinal ends of the pressure generating member are supported. inkjet head. (2) The inkjet head according to claim 1, wherein the thickness of the piezoelectric material is 50 μm or less. (3) The inkjet head according to claim 1, wherein the pressure generating member is arranged to face the nozzle. (4) The inkjet according to claim 1, wherein a plurality of the nozzles and the pressure generating member are arranged, and the nozzles and the pressure generating member are arranged in a one-to-one correspondence. head.