JPH0286455A - inkjet head - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an inkjet recording device such as a printer that forms an ink image on a medium such as a recording paper by flying ink droplets, and more specifically relates to an inkjet recording device such as a printer that forms an ink image on a medium such as recording paper. Regarding printer heads.

[Conventional technology]

An inkjet head in which a nozzle forming substrate having a plurality of nozzles and a piezoelectric transducer for directly contacting ink and pressurizing the ink is arranged behind the nozzle forming substrate is disclosed in Japanese Patent Publication No. 8953/1988. An inkjet head with this structure has improved ink droplet ejection efficiency and ejection stability because the vibrator formed in the piezoelectric transducer is displaced almost perpendicularly to the nozzle forming substrate and the ink flow path of the nozzle is short. is high, and even if foreign matter such as air bubbles or dust gets into the ink, normal operation is possible without being affected by it.
Furthermore, since the vibrator is cantilevered or double-sided, the electromechanical conversion efficiency is high and the required vibrator displacement can be obtained at low voltage.

[Problem to be solved by the invention]

However, in the above-mentioned conventional technology, when the piezoelectric transducer is machined to form each vibrator, cracks and chips occur in the piezoelectric element, which is a brittle component of the piezoelectric transducer. Because of this, it was necessary to reduce the machining speed to reduce damage to the vibrator, and when assembling the head, it was necessary to pay close attention to handling in order to avoid damaging the piezoelectric transducer. Therefore, there have been problems in that the yield of parts is lowered, the processing time is increased, the yield of the head is lowered, the number of assembly steps is increased, etc., and the cost of the head is increased.

The purpose of the present invention is to solve these problems, improve the yield and processing efficiency during manufacturing of piezoelectric transducers, reduce parts costs, and further improve the operation of piezoelectric transducers during head assembly. The object of the present invention is to realize a low-cost inkjet head by improving the yield of the head by improving the performance.

[Means to solve the problem]

The inkjet head of the present invention includes a nozzle forming substrate having a plurality of nozzles, a piezoelectric transducer arranged to face each of the nozzles, immersed in ink and forming a vibrator that can be driven independently, and In an inkjet head that displaces the piezoelectric transducer by application of an electric current and ejects ink in a gap between the nozzle forming substrate and the piezoelectric transducer from the nozzle, the exposed surface of the brittle member constituting the piezoelectric transducer is coated with zinc. It is characterized by being provided with a thin film showing the following.

C Effect] In the above configuration of the present invention, the thin film exhibiting slenderness (sticky strength) formed on the surface of the brittle member serves as a surface protective layer.

〔Example〕

Next, the present invention will be explained based on examples.

FIG. 1 is a perspective view for explaining an embodiment of a recording apparatus equipped with an inkjet head according to the present invention. The recording medium 1 is wound around a platen 4 by pressure from feed rollers 2 and 3, and is conveyed in the direction of an arrow 5 as recording progresses. An inkjet head 9 having a plurality of nozzles that can independently control the ejection of ink droplets is mounted on a carriage 8 that is guided by a guide shaft 6°7 and movable in a direction parallel to the axis of the platen 4. The recording medium 1 is scanned in 10 directions, and ink droplets are selectively ejected from each nozzle to form an ink image on the recording medium 1.

FIGS. 2(a) and 2(b) are cross-sectional views for explaining the structure of the inkjet head and the principle of ejecting ink droplets according to the present invention. Frame 40 and subframe 41
The nozzle forming substrate 30, spacer 43, piezoelectric transducer 20, and elastic sheet 42 are laminated and fixed between the holes. A plurality of nozzles 31 are arranged in a row on the nozzle forming substrate 30, and the free ends of the plurality of vibrators 21 of the piezoelectric transducer 20 are arranged at a position corresponding to each nozzle with a minute gap 45 interposed therebetween. (
Figure 2(a)). The piezoelectric transducer 20 has electrodes A23 on both sides.
A surface protective layer 25 made of Ni and serving as a signal electrode is formed on one side of the piezoelectric element 22 on which the electrode B24 is formed, and a metal plate 25 made of Ni and serving as a common electrode is formed on the other side.
6 is formed. Since the metal plate 26 can be used as a common electrode, the electrode A23 can be omitted (FIG. 2(b)).

The polarization direction of the piezoelectric element 22 is different from that of the metal plate 26 and the protective layer 250.
They are placed so that when a voltage is applied between them, they contract in a direction perpendicular to the electric field. On the other hand, since the metal plate 26 has a high elastic modulus, dimensional changes are restricted, and a bending moment is generated as the metal plate 26 bends toward the protective layer 25 side. As a result, the vibrator 21
The free end of the nozzle forming substrate 30 is deformed and displaced in the opposite direction. When the voltage constantly applied to the piezoelectric transducer 20 is selectively released, the vibrator 21 moves to the nozzle forming substrate 3.
The vibrator 21 and the nozzle forming substrate 3 are deformed and displaced in the direction of 0.
The ink 44 interposed between 0 and 0 is ejected from the nozzle 31.

The protective layer 25 is made of a material exhibiting adhesive properties (sticky strength), and in addition to metal thin films such as Ni, Au, and Cr, resin thin films such as polyimide and polyethylene terephthalate can also be used, and the thickness is 0.01 μm to 0.01 μm. The effect as a protective layer appears within the range of 30 μm. When a metal thin film is adopted as the protective layer 25, the protective layer 25 can be used as an electrode.
Electrode B24 can be omitted. At this time, vibrator 2
The protective layer 25 provided on the surface of the vibrator 21
There is a concern that the deformation curvature and bending rigidity of the resonator will be affected, but we confirmed this through simulation and determined that the thickness of the protective layer can suppress the effect on the above characteristics to within 10%, thereby improving the characteristics of the resonator. It is also possible to improve resistance to cracking and chipping during processing of the vibrator while minimizing the impact. In this embodiment, the piezoelectric element 2
When the thickness of 2 is 100 μm and the thickness of metal plate 26 is 50 μm,
The thickness of the protective layer 25 was set to 1 μm.

Therefore, due to the effect of protection N25, the yield during the manufacture of the vibrator was improved, and the processing speed of the vibrator was also increased, which greatly contributed to reducing the cost of the vibrator parts. Furthermore, it was possible to prevent a decrease in head yield due to breakage of the vibrator during head assembly, and it was also possible to reduce the cost of the head.

In this embodiment, a cantilever-shaped vibrator is used as the vibrator, but a similar configuration is possible with a double-sided beam-shaped vibrator.

〔Effect of the invention〕

As described above, according to the above structure of the present invention, the protective layer formed on the surface of the piezoelectric element strengthens the piezoelectric element's resistance to cracking and chipping, so that the yield of the vibrator during machining is reduced. In addition, it is possible to increase the machining speed, thereby shortening the machining time and reducing the cost of parts for the vibrator.

In addition, since the operability of the vibrator is increased during head assembly, the risk of damage to the vibrator is reduced, resulting in improved head yield and head assembly efficiency.
This has the effect of realizing a low-cost inkjet head together with a reduction in component costs.

[Brief explanation of drawings]

FIG. 1 is a perspective view for explaining an embodiment of a recording apparatus equipped with an inkjet head according to the present invention. FIGS. 2(a) and 2(b) are cross-sectional views for explaining the structure of the inkjet head and the principle of ink discharge in the present invention. Recording Media Infujiera Piezoelectric Transducer Piezoelectric Element Metal Plate Nozzle Inkt Head Vibrator Protective Layer Nozzle Formation Substrate Spacer Gap or More Applicant Seiko Epson Corporation Agent Patent Attorney Kizobe Suzuki and 1 other person Figure 1

Claims (1)

[Scope of Claims] A nozzle forming substrate having a plurality of nozzles, a piezoelectric transducer disposed facing each of the nozzles, immersed in ink and forming a vibrator that can be driven independently, and applying a voltage. In an inkjet head that displaces the piezoelectric transducer by displacing the piezoelectric transducer and ejecting ink in a gap between the nozzle forming substrate and the piezoelectric transducer from the nozzle, An inkjet head characterized by being provided with a thin film shown in FIG.