JPH04353454A - Liquid-drop jet apparatus - Google Patents

Abstract

PURPOSE:To provide the apparatus capable of being driven by low voltage. CONSTITUTION:In a liquid-drop jet apparatus equipped with a plurality of jet devices injecting the ink in ink passages by changing the volumes of the ink passages 31 using a piezoelectric transducer 1, the ink passages 31 are constituted of the piezoelectric transducer 1 having a plurality of grooves and two plates 21, 22 different in the modulus of elasticity and, since the plate 22 lower in the modulus of elasticity is engaged with the piezoelectric transducer 1, the quantity of deformation of the ink passages 31 sufficient to inject an ink droplet even by low drive voltage can be obtained and the liquid-drip apparatus capable of being driven by low voltage can be provided.

Description

[Detailed description of the invention]

0001

[Industrial Field of Application] The present invention relates to a droplet jetting device.
More specifically, the present invention relates to a droplet ejecting device that utilizes the deformation of a piezoelectric transducer.

0002

2. Description of the Related Art Conventionally, printer heads using piezoelectric inkjet have been proposed. By changing the volume of the ink flow path by changing the dimensions of the piezoelectric transducer, when the volume decreases, the ink in the ink flow path is ejected from the orifice, and when the volume increases, the ink is ejected from the other valve into the ink flow path. This method is called the drop-on-demand method. A plurality of such injection devices are arranged close to each other,
Desired characters and images are formed by ejecting ink from an ejecting device at a predetermined position.

This type of droplet injection device is disclosed in, for example, Japanese Patent Laid-Open No. 63-247051 and Japanese Patent Laid-Open No. 63-25.
Some of them are described in Japanese Patent No. 2750. FIGS. 3 and 4 show schematic diagrams of these conventional examples. Hereinafter, a conventional example will be specifically explained with reference to FIG. 3 showing a cross-sectional view of a part of the array. A piezoelectric ceramic having a plurality of side walls 2a, 2b, 2c, and 2d and subjected to polarization treatment in the direction of an arrow 51. By joining the plate 1 and the cover plate 21 made of a metal material, a glass material, a ceramic material, etc. via the bonding layer 12, a plurality of ink channels 31a, 31b, 31c which are spaced apart from each other in the lateral direction are formed. configured. The ink channels 31a, 31b, and 31c have an elongated shape with a rectangular cross section, and the side walls 2a, 2b, 2c, and 2d extend over the entire length of the channels, and are deformable in a direction perpendicular to the channel axis and the polarization direction. Change ink pressure. The side walls 2a, 2b, 2
On the surfaces of c and 2d are metal electrodes 11c for applying a driving electric field,
11d, 11e, and 11f are formed.

In the array, when, for example, the injection device 31b is selected according to predetermined print data, the metal electrode 1
A driving electric field is applied between each of 1c and 11d and metal electrodes 11e and 11f. At this time, since the driving electric field direction and the polarization direction are perpendicular to each other, the side walls 2b and 2c are deformed inward of the ink flow path 31b due to the piezoelectric thickness shear effect. This deformation reduces the volume within the ink flow path 31b, increases the ink pressure, and ink droplets are ejected from an orifice (not shown). Further, when the application of the driving electric field is stopped, the side wall returns to the position before deformation, so the ink pressure in the flow path decreases, and ink is supplied into the flow path from an ink supply section (not shown).

[0005] The array is manufactured by the following manufacturing method. As shown in FIG. 4, parallel grooves 3 that form flow channels in the shape described above are created in a piezoelectric ceramic plate 1 that has been polarized in the direction of an arrow 51 by grinding by rotating a diamond cutting disk or the like. . The aforementioned metal electrode is formed on the surface of this groove 3 by sputtering or the like. A cover plate 21 is bonded to the upper surface 4a of the piezoelectric ceramic plate 1 on the groove side. Further, an orifice plate 41 having an orifice 42 provided at a position corresponding to the position of the flow path is bonded to the end face 4b of the groove of the piezoelectric ceramic plate on the ink injection side.

[0006]

[Problems to be Solved by the Invention] However, in the above-mentioned conventional droplet injection device, the deformation of the piezoelectric transducer is partially restricted due to the bonding between the piezoelectric transducer and the cover plate. However, there is a problem in that a high driving voltage is required to eject the ink droplets.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a droplet ejecting device that can be driven at low voltage.

[0008]

Means for Solving the Problems To achieve this object, the droplet ejecting device of the present invention ejects ink in an ink flow path by changing the volume of the ink flow path using a piezoelectric transducer. A droplet ejecting device including a plurality of devices, a piezoelectric transducer having a plurality of grooves forming an ink flow path, a first flat plate covering the grooves provided on the piezoelectric transducer, and a first flat plate provided on the first flat plate. a second flat plate arranged in a laminated manner and made of a material having a higher elastic modulus than the first flat plate, the volume of the ink flow path is changed by applying a predetermined electric field to the piezoelectric transducer; It is characterized by ejecting ink from an ink flow path.

[0009]

[Operation] According to the droplet ejecting device of the present invention having the above configuration, the side wall of the piezoelectric transducer forming a part of the ink flow path is deformed by the piezoelectric thickness shear effect due to the application of a driving electric field, and the ink droplet is Ejection and supply of ink to the ink flow path are performed.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment embodying the present invention will be described below with reference to the drawings.

First, an embodiment of the present invention will be specifically described with reference to FIG. 1 showing a cross-sectional view of a part of the array. A piezoelectric ceramic plate 1 subjected to polarization treatment, a lower cover plate 22 made of, for example, a resin material, bonded to the piezoelectric ceramic plate 1 via a bonding layer 12, and the other side of the lower cover plate 22. An upper cover plate 21 having a higher elastic modulus than the lower cover plate 22 and made of, for example, aluminum or a metal material is provided. This upper cover plate 21 and lower cover plate 2
The attachment surface 2 may be joined or only mechanically pressed. This forms a plurality of ink flow paths 31a, 31b, and 31c that are spaced apart from each other in the lateral direction. The ink channels 31a, 31b, and 31c have an elongated shape with a rectangular cross section, and the side walls 2a, 2b, 2c, and 2d extend over the entire length of the channels, and are deformable in a direction perpendicular to the channel axis and the polarization direction. Change ink pressure. Further, metal electrodes 11c, 11d, 11e, 11f for applying a driving electric field are formed on the surfaces of the side walls 2a, 2b, 2c, and 2d by sputtering or the like.

Next, regarding the operation, in the array, for example, the injection device 31b is activated according to predetermined print data.
is selected, metal electrodes 11c, 11d and metal electrode 1
A driving electric field is applied between each of 1e and 11f. FIG. 2 shows the deformed state of the side wall at this time. Since the driving electric field direction and the polarization direction are perpendicular to each other, the side walls 2b and 2c are deformed inward of the ink flow path 31b due to the piezoelectric thickness shear effect. This deformation reduces the volume within the ink flow path 31b, increases the ink pressure, and ink droplets are ejected from an orifice (not shown). Further, when the application of the driving electric field is stopped, the side wall returns to the position before deformation, so the ink pressure in the flow path decreases, and ink is supplied into the flow path from an ink supply section (not shown). The lower cover plate 22 has a lower elastic modulus than the upper cover plate 21, and when the side wall is deformed, the lower cover plate 22 deforms greatly, so that the restraining force against deformation of the side wall is small. In addition, the lower cover plate 22
is deformed by expanding inward of the ink flow path, so the volume of the ink flow path decreases by the amount of deformation of the lower cover plate 22. From the above, it is possible to obtain a sufficient amount of deformation of the side wall to eject ink droplets even at a low driving voltage.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and numerous modifications can be made without departing from the spirit thereof. For example, the polarization direction 51 of the piezoelectric transducer may be in the opposite direction. Furthermore, the timing of voltage application when ejecting ink droplets and when supplying ink may be reversed to the above method. That is, upon application of the driving voltage, the side walls 2b and 2c are deformed toward the outside of the ink flow path 31b due to the piezoelectric thickness shear effect. This deformation increases the volume within the ink flow path 31b, reduces the ink pressure, and ink is supplied into the flow path from an ink supply section (not shown). Further, when the application of the driving electric field is stopped, the side wall returns to the position before deformation, so the ink pressure increases, and ink droplets are ejected from an orifice (not shown).

[0014]

As is clear from the above explanation, the droplet ejecting device of the present invention has an ink flow path composed of a piezoelectric transducer having a plurality of grooves and two plates having different moduli of elasticity. Because the plate with the lower rate engages the piezoelectric transducer, the ink flow path can be deformed enough to eject ink droplets even at low drive voltages, allowing drive at low voltages. It is possible to provide a droplet ejecting device that is

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of an array forming part of a droplet ejection device.

FIG. 2 is a cross-sectional view of an array forming part of a droplet ejecting device when a driving voltage is applied.

FIG. 3 is a cross-sectional view of an array forming part of a conventional droplet ejecting device.

FIG. 4 is a perspective view showing a method of manufacturing an array forming a part of a droplet ejecting device in a conventional example.

[Explanation of symbols]

1 Piezoelectric ceramic plate 2 Side wall of piezoelectric ceramic plate 11 Electrode 12 Adhesive layer 21 Upper cover plate (high elastic modulus) 22 Lower cover plate (low elastic modulus) 31 Ink flow path 51 Polarization direction

Claims (1)

[Claims] 1. A droplet ejecting device comprising a plurality of ejecting devices that eject ink in an ink flow path by changing the volume of the ink flow path using a piezoelectric transducer, comprising a plurality of grooves forming an ink flow path. a first flat plate that covers a groove provided on the piezoelectric transducer; and a first flat plate that is laminated on the first flat plate and is made of a material having a higher elastic modulus than the first flat plate. A droplet ejecting device characterized in that the volume of the ink flow path is changed by applying a predetermined electric field to the piezoelectric transducer, and the ink in the ink flow path is ejected.