JPH01196350A - Ink jet head - Google Patents

Abstract

PURPOSE:To enable realization of an ink jet head with stable characteristics as a laminated pressed body of a nozzle plate and a separate reinforcing plate by applying the reinforcing plate as a nozzle forming member on the ink discharge side of the member and fastening the reinforcing plate to the external frame of an ink jet head or holding said plate using a spring member. CONSTITUTION:Ink is supplied to an area near a nozzle 28 from an ink reserver 24 and becomes full there. If a voltage is applied between a common electrode 51 and a pattern electrode 54, a piezoelectric element contracts due to a piezoelectric effect. If the meantime, the layer of the pattern electrode 54 has a limited size change due to its high modulus of elasticity, and a bending moment occurs on the side of the common electrode 53. As a result, the free end of a vibrator 52 is deformed and displaced to the direction of a nozzle plate 27, and the ink in the nearby area is discharged from a nozzle. Simultaneously the nozzle plate receives the pressure of ink, causing a bending vibration. However, the nozzle plate is characteristically stable and free from vibration under the pressure of a reinforcing plate 34. The reinforcing plate should be installed at a height of at most, 2m/m.

Description

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

[Conventional technology]

A known structure of a conventional inkjet head includes a nozzle plate having a plurality of nozzle openings and a piezoelectric transducer behind the nozzle plate that is in direct contact with ink. (Showa 60-8953, etc.) With this structure, the vibrator constituting the piezoelectric transducer vibrates as if displaced in a direction approximately perpendicular to the nozzle plate, and the ink droplet ejection efficiency and stability between each nozzle are high. Even if foreign matter such as gas or dust gets into the product, normal operation is possible without being affected by this, and the vibrator is screwed from the ink supply side of the nozzle plate without welding or reinforcing plates. .

[Problem to be solved by the invention]

The conventional structure of the inkjet I head that does not use a reinforcing plate has problems in that it is difficult to secure dimensions during operation and the vibration of the piezoelectric transducer is unstable. That is, since the gap between the nozzle plate and the movable part of the vibrator facing the nozzle plate affects the ink ejection characteristics, it is necessary to manage the minute gap with high precision and to make the vibration of the piezoelectric transducer uniform.

However, since the thickness of the nozzle plate is very thin, about 100 μm, the nozzle plate also bends and vibrates due to the operation of the piezoelectric transducer, and the gap between the vibrator and the nozzle plate changes over time, and the bending vibration of the nozzle plate changes over time. This has had the problem of acting as a disturbance to the vibrations of the piezoelectric transducer, resulting in non-uniform vibrations and unstable characteristics.

An object of the present invention is to solve these problems and realize an inkjet with stable characteristics.

[Means to solve the problem]

An inkjet head of the present invention includes a nozzle forming member having a plurality of nozzle openings and a piezoelectric transducer, and ink is filled between the nozzle forming member and the piezoelectric transducer in the vicinity of the nozzle. The forming member is characterized in that a reinforcing plate is placed on the ink ejection side of the member, and the forming member is fastened to the head outer frame or fixed with a spring member.

[For production]

In the above structure of the present invention, the reinforcing plate suppresses the bending vibration of the nozzle plate, and the minute gap between the nozzle plate and the vibrator is kept constant, and the vibrator always vibrates uniformly in the direction perpendicular to the nozzle plate, thereby removing ink from the vicinity. Extruded ink droplets are ejected.

〔Example〕

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

In the following embodiments, a case will be described in which a piezoelectric transducer is used as the electromechanical transducer, but the present invention is not limited to this.

FIG. 1 is a perspective view of a printer showing an embodiment of the present invention. In the figure, recording paper 10 is wound around a platen 11 and is pressed by feed rollers 12 and 13. The inkjet head 16 is mounted on a carriage 15 that is guided by guide shafts 14 and 17 and movable in a direction parallel to the platen axis. The inkjet head 16 has a plurality of nozzles that can independently control the ejection of ink droplets, and is scanned in the platen axis direction to selectively eject ink droplets from the nozzles to form an ink image on the recording paper 10.

The recording paper 10 is conveyed in the sub-scanning direction perpendicular to the scanning direction by rotation of the platen 11 and feed rollers 12 and 13, and printing is performed on the recording paper surface.

FIG. 2 shows a cross section of the inkjet head.

A piezoelectric transducer 31, a nozzle plate 27, and a reinforcing plate 34 are stacked on the frame 26 and fixed using fixing screws 32 and 33. The nozzle plate 27 is composed of a thin metal plate having a plurality of nozzles 28. The mounting height of the reinforcing plate including the fixing screws 32 and 33 is less than or equal to 2IwI11. Therefore, since the inkjet head 16 does not hit the recording paper 10 while the printer is in operation, printing stains do not occur.

FIG. 3 shows another embodiment of the invention.

A piezoelectric transducer 31, a nozzle plate 27, and a reinforcing plate 34 are stacked on a frame 26 and sandwiched between solid springs 36 and 37.

The piezoelectric transducer 31, whose perspective view is shown in FIG. 4, has a common electrode layer 5 made of four Au layers on one side of a piezoelectric element 30 made of PZT.
3 and a spacer layer 51 made of a thin layer of Ni, and the other side has a spacer layer 51 made of a thin layer of Ni.
It has a patterned electrode layer 54 made of a thin plate. The piezoelectric transducer 31 is separated by a notch 56 into a plurality of vibrators 5.
2 is configured. Again in FIG. 2, the nozzles 2 are connected to the vicinity of the vibrator tip and the corresponding nozzles 2 through a minute gap.
8 are arranged facing each other. Wires 29 are individually connected to the pattern electrodes, and a voltage is applied at the tip.

Next, the operation will be explained. Ink (not shown) is supplied from the ink reservoir 24 to the vicinity of the nozzle to fill it.

By applying a voltage between the common electrode 51 and the pattern electrode 54, the piezoelectric element contracts due to the piezoelectric effect. On the other hand, since the layer of the pattern electrode 54 has a high elastic modulus, dimensional changes are restricted, and a bending moment is generated as the pattern electrode 54 bends toward the common t[i53 side. The free end of the vibrator 52 is thereby deformed and displaced in the direction of the nozzle plate, causing nearby ink to be ejected from the nozzle.

At the same time, the nozzle plate also bends under the pressure of the ink and tries to vibrate, but it is suppressed by the reinforcing plate 34 and the nozzle plate can obtain stable characteristics without vibration.
In the figure, the height a for installing the reinforcing plate is 2171 or less, but the optimal dimension is 0.5 to 11/1 in order to obtain the minimum pressing force and to prevent print stains on the recording paper.
It is.

〔Effect of the invention〕

In the above structure of the present invention, since it is an i-structure in which the nozzle plate and a separate reinforcing plate are laminated and pressed, it has the following advantages.

■The vibration of the nozzle plate is attenuated by the friction between the laminated interfaces between the two, so it has a great vibration-proofing effect and can realize an inkjet head with stable characteristics.

Since the nozzle plate has a flat and simple shape due to the 02-body structure, nozzle hole formation, which is important in terms of characteristics, can be easily performed.

(2) By using a two-piece construction and changing the materials of both, only the nozzle plate that comes into contact with ink can be made of an ink-resistant material, and the auxiliary plate can be made of an inexpensive and high-quality material.

■The recording paper is wound around a platen and faces the nozzle in a convex manner, but the nozzle plate is concave near the nozzle, which improves space usage efficiency and prevents printing stains.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a printer equipped with an inkjet head showing one embodiment of the present invention. FIG. 2 is a sectional view of an inkjet head showing an embodiment of the present invention. FIG. 3 is a sectional view of an inkjet head showing another embodiment according to the present invention. FIG. 4 is a perspective view of a piezoelectric transducer of an inkjet head showing an embodiment according to the present invention. 16... Inkjet head 27...
・Nozzle plate 28...Nozzle 30...Piezoelectric element 31...Piezoelectric transducer 34.35...Reinforcement plate 36.37...Fixing spring 51... ... Spacer 52 ... Vibrator 53 ... Common electrode 54 ... Pattern electrode and above Applicant Seiko Epson Co., Ltd. Agent Patent attorney Tsutomu Mogami (1 other person) 7g, Inkshi 1 Esotohefd Figure 1 Figure 3

Claims (2)

[Claims] (1) In an inkjet head having a nozzle forming member having a plurality of nozzle openings and an electromechanical transducer, the space between the nozzle forming member and the electromechanical converter is filled with ink. An inkjet head characterized in that a reinforcing plate is placed on the ink ejection side of the member and fastened to a frame or fixed with a spring member. (2) The inkjet head according to item 1, wherein the reinforcing plate mounting height a is 2 m/m or less.