JPH04348949A - Ink droplet jet device - Google Patents

Abstract

PURPOSE:To avoid an increase in temperatures of piezo-electric transducers and the deterioration of piezo-electric characteristics of elements by consisting a part of ink flow passageways from the piezo-electric transducers and providing grooves continuous with the ink flow passageways and having smaller sectional areas than those of the ink flow passageways on the ink jet side of the piezo-electric transducers. CONSTITUTION:Grooves 3 forming ink flow passageways are made on a piezo-electric ceramic plate 1 to which polarization processing is applied, by a grinding machining to be performed by rotating a diamond cutting disc, or by a laser beam machining. In this case, the depth of grooves 5 continuous with the grooves 3 and positioned in the vicinity of the end face of the piezo-electric ceramic plate on its ink jet side is made shallower than that of the grooves 3. Metal electrodes for applying a drive electric field to piezo-electric transducers are formed on the surfaces of the grooves 3 by a method of sputtering and the like, and thereafter, a cover plate 21 is bonded to the upper face of the piezo-electric ceramic plate 1 on its groove side. When the side walls 2a, 2b of the piezo-electric transducers are deformed by applying the drive electric field to the metal electrodes, the capacities of the grooves forming the ink flow passageways are varied.

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. By joining the piezoelectric ceramic plate 1 and the cover plate 21 made of metal material, glass material, ceramic material, etc. via the bonding layer 12, a large number of ink flow channels 31a, 31b, which are spaced apart from each other in the lateral direction are created. 31c and 31d are configured. The ink flow path 31 has an elongated shape with a rectangular cross section,
The side wall 2 extends over the entire length of the channel and is deformable in a direction perpendicular to the channel axis and the polarization direction to change the ink pressure within the channel. A metal electrode 1 for applying a driving electric field is provided on the surface of the side wall 2.
1 is formed, and the surface of the metal electrode 11 is subjected to surface treatment to prevent corrosion by ink.

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 1a, 11b and metal electrodes 11c, 11d. 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 piezoelectric ceramic plate on the ink injection side.

[0006]

[Problems to be Solved by the Invention] However, in the conventional droplet injection device described above, it is necessary to bond the orifice plate to the piezoelectric transducer during the manufacturing process, which increases the number of parts and manufacturing steps, increasing manufacturing costs. There was a problem. Further, in the step of joining the orifice plates, the temperature of the piezoelectric transducer increases, causing a problem in that the piezoelectric characteristics of the element deteriorate.

The present invention has been made to solve the above-mentioned problems, and aims to provide a droplet ejecting device that reduces manufacturing costs and prevents deterioration of the piezoelectric characteristics of a piezoelectric transducer. .

[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. In the droplet ejecting device, the piezoelectric transducer forms a part of the ink flow path, and the piezoelectric transducer forms a groove that is continuous with the ink flow path and has a cross-sectional area smaller than the cross-sectional area of the ink flow path. It is characterized by being provided on the ink ejection side of the transducer.

[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 flow path is Ink droplets are ejected from a groove that is continuous and has a cross-sectional area smaller than the cross-sectional area of the ink flow path.

0010

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

First, a manufacturing method according to an embodiment of the present invention will be specifically explained with reference to FIG. The first groove 3 that forms the ink flow path is created by machining or the like. At this time, the depth of the second groove 5 near the end face on the ink ejection side, which is continuous with the first groove 3, is formed to be smaller than the depth of the first groove 3. Such a shape can be created by moving the diamond cutting disc upward near the end face of the piezoelectric ceramic plate in the case of grinding using a diamond cutting disc, or by moving the diamond cutting disc upward near the end face of the piezoelectric ceramic plate in the case of laser processing. This is easily achieved by reducing the laser power at . A metal electrode (not shown) for applying a driving electric field to the piezoelectric transducer is formed on the surface of the first groove 3 by sputtering or the like. Then, the piezoelectric ceramic plate 1
A cover plate 21 is adhered to the upper surface 4a of the groove side.

Next, the operation of one embodiment of the present invention will be explained in detail with reference to FIG. first groove 3 forming a channel;
The volume of the groove 5 changes, and ink is ejected from the second groove 5.

As described above, in the droplet ejecting device of this embodiment, there is no need to adhere an orifice plate to the end face of the piezoelectric ceramic plate on the ink ejection side, which reduces the number of parts and manufacturing steps, and reduces manufacturing costs. Furthermore, it is possible to avoid a rise in temperature of the piezoelectric transducer and deterioration of the piezoelectric characteristics of the element in the process of joining the orifice plates.

It should be noted that the present invention is not limited to the embodiments described above, and numerous modifications can be made without departing from the spirit thereof. For example, the following manufacturing method, which will be specifically explained with reference to FIG. 2, may be used. arrow 51
First grooves 3, which form ink flow paths, are created in a piezoelectric ceramic plate 1 that has been subjected to a polarization process in a direction by grinding by rotating a diamond cutting disk, laser machining, or the like. At this time, the first groove 3 is formed so as not to reach the end surface 4b on the ink ejection side. Then, a second groove 5 that is continuous with the first groove 3 and has a cross-sectional area smaller than the cross-sectional area of the first groove 3 is manufactured. A metal electrode for applying a driving electric field to the piezoelectric transducer is formed on the surface of the first groove 3 by sputtering or the like. Then, a cover plate 21 is bonded to the upper surface 4a of the piezoelectric ceramic plate 1 on the groove side. Furthermore, the formation of the ink flow path is not limited to the bonding of the piezoelectric ceramic plate 1 and the cover plate 21, but may be formed by bonding two piezoelectric ceramic plates of the same shape.

[0015]

[Effects of the Invention] As is clear from the above explanation, the droplet ejecting device of the present invention eliminates the need to bond an orifice plate to the ink ejection side end face of the piezoelectric ceramic plate, reducing the number of parts and manufacturing process. In addition, it is possible to avoid a rise in the temperature of the piezoelectric transducer and a deterioration of the piezoelectric characteristics of the element in the process of joining the orifice plates.

[Brief explanation of drawings]

FIG. 1 is a perspective view illustrating a method of manufacturing an array forming part of a droplet ejection device.

FIG. 2 is a perspective view illustrating a method of manufacturing an array forming part of a droplet ejecting device.

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 2a Side wall of piezoelectric ceramic plate 2b Side wall of piezoelectric ceramic plate 3 First groove 5 Second groove (ink injection port) 21 Cover plate 51 Polarization direction

Claims (1)

[Claims] 1. A droplet ejecting device comprising an ejecting device that ejects ink in an ink flow path by changing the volume of the ink flow path using a piezoelectric transducer, comprising:
The piezoelectric transducer constitutes a part of the ink flow path, and the piezoelectric transducer has a groove on the ink ejection side that is continuous with the ink flow path and has a cross-sectional area smaller than the cross-sectional area of the ink flow path. Droplet injection device.