JP3030969B2 - Droplet ejector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid droplet ejecting apparatus, and more particularly to a liquid droplet ejecting apparatus utilizing deformation of a piezoelectric transducer.

[0002]

2. Description of the Related Art Heretofore, there has been proposed a printer head using a piezoelectric ink jet head. By changing the volume of the ink flow path by deformation of the piezoelectric transducer, ink in the ink flow path is ejected from the orifice when the volume is reduced, and ink is introduced into the ink flow path from the other valve when the volume is increased. This is an ink-jet printer head called a so-called drop-on-demand system. Then, by arranging a plurality of such ejecting devices in close proximity to each other and ejecting ink from the ejecting device at a predetermined position, desired characters, figures and images are formed.

For example, Japanese Patent Application Laid-Open Nos. 63-247051 and 63-25
There is one described in Japanese Patent No. 2750. FIGS. 4, 5 and 6 are schematic diagrams of these conventional examples.

Hereinafter, the conventional example will be specifically described with reference to FIG. 4 showing a partial cross-sectional view of the array.
a, 13b, 13c, 13d, and a piezoelectric ceramic plate 1 that has been polarized in the direction of arrow d and a cover plate 2 made of a metal material, a glass material, a ceramic material, a resin material, or the like. By joining through 5,
A large number of ink flow paths 31a spaced from each other in the lateral direction,
31b and 31c are configured. Ink flow paths 31a, 31
b and 31c have an elongated shape with a rectangular cross section,
a, 13b, 13c, and 13d extend over the entire length of the flow path, are deformable in a direction perpendicular to the flow path axis and the polarization direction, and change the ink pressure in the flow path. The side walls 13a, 13
Metal electrodes 11a, 11b, 11c and 11d for applying a driving electric field are formed on the surfaces of b, 13c and 13d, and on the surfaces of the metal electrodes 11a, 11b, 11c and 11d,
Surface treatment to prevent corrosion by ink.

In the array, when, for example, the ejection device 31b is selected according to predetermined print data, the metal electrode 1
A driving electric field is applied between each of 1a and 11b and each of metal electrodes 11c and 11d. At this time, since the driving electric field direction and the polarization direction are orthogonal to each other, the side wall 13b and the side wall 13c are deformed toward the inside of the ink flow path 31b due to the piezoelectric thickness-shear effect as shown in FIG. Due to this deformation, the volume in the ink flow path 31b decreases, the ink pressure increases, 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 the deformation, so that the ink pressure in the flow path decreases, and ink is supplied into the flow path from an ink supply unit (not shown).

The array is manufactured by the following manufacturing method. As shown in FIG. 6, a parallel groove 3 for forming a flow path having the above-described shape is formed in a piezoelectric ceramic plate 1 that has been subjected to a polarization process in the direction of arrow d by grinding or the like by rotating a diamond cutting disk. . The metal electrode is formed on the surface of the groove 3 by sputtering or the like. Then, the upper surface 12 on the groove side of the piezoelectric ceramic plate 1
To the cover plate 2. Further, the orifice plate 4 provided with the orifice 41 at a position corresponding to the position of the flow path is bonded to the end surface 14 of the groove of the piezoelectric ceramic plate on the ink ejection side.

[0007]

However, in the above-described conventional droplet device, a side wall of a certain ejecting device is driven to eject droplets from an orifice corresponding to a flow path position of the ejecting device. In an ejection device adjacent to the ejection device, the side wall forming the flow path acts to increase the volume in the ink flow path. Therefore, it is impossible to simultaneously drive the adjacent ejection devices to eject the droplet from the orifice corresponding to the flow path position. This complicates the control and reduces the printing speed in forming characters, figures and images using the droplet apparatus.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has as its object to provide a liquid droplet ejecting apparatus having high working efficiency in forming characters, figures, and images.

[0009]

In order to achieve this object, a liquid drop ejecting apparatus according to the present invention uses a piezoelectric transducer to change the volume of an ink flow path to eject ink in the ink flow path. A droplet ejecting apparatus including a plurality of devices, wherein a plurality of first walls of a piezoelectric transducer that can be deformed only in a single direction forming a groove of the ink flow path and the adjacent ink flow path are separated. , A plurality of second walls positioned opposite to each other in a direction in which the first wall is deformed, wherein the first wall of the piezoelectric transducer and the second wall are provided.
And one wall of the ink is formed between the first and second walls.

[0010]

According to the droplet ejecting apparatus of the present invention having the above-described structure, the first wall of the piezoelectric transducer forming a part of the ink flow path is deformed by the application of the driving electric field, and the one wall of the ink flow path is also deformed. A volume change occurs in the ink flow path between the second wall forming the portion and the second wall. At this time, since the second wall separates the respective ink flow paths, the ejection of the ink droplets and the supply of the ink to the ink flow paths can be freely performed in the individual ejecting devices that eject the ink in the ink flow paths. Will be

[0011]

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

First, one embodiment of the present invention will be specifically described with reference to FIG. 1 showing a partial cross-sectional view of the array. The array of this embodiment has a plurality of side walls 13a, 13b, 13c, and A piezoelectric ceramic plate 1 that has been polarized in the direction of arrow d, a cover plate 2 made of a metal material, a glass material, a ceramic material, a resin material, or the like having a plurality of side walls 21a, 21b, 21c; And a bonding layer 5 made of, for example, an epoxy-based adhesive bonding the upper portions of the plurality of side walls 13a, 13b, 13c to the side wall forming surface of the cover plate 2. for that reason,
A plurality of side walls 13a, 13 of the piezoelectric ceramic plate 1
b, 13c and the plurality of side walls 21a, 21b of the cover plate 2,
21c, a number of ink flow paths 31a, 31b, 31c having different intervals in the horizontal direction are formed.

The ink flow paths 31a, 31b, 31c have an elongated shape with a rectangular cross section, and have side walls 13a, 13b, 13c.
c and the side walls 21a, 21b, 21c extend over the entire length of the flow path, are deformable in the direction perpendicular to the flow path axis and the polarization direction, and change the ink pressure in the flow path. On the surfaces of the side walls 13a, 13b, 13c of the piezoelectric ceramic plate 1, metal electrodes 11a, 11b, 11c, 11 for applying a driving electric field are provided.
d, 11e and 11f are formed, and the metal electrode 11
The surfaces of a, 11b, 11c, 11d, 11e, and 11f are subjected to a surface treatment for preventing corrosion by ink. In addition, as shown in FIG.
The orifice plate 4 provided with the orifice 41 at a position corresponding to the position of the flow path is bonded to the ink ejection side end surfaces 14 and 22 of the cover plate 2.

Next, the operation will be described. In the array, for example, according to predetermined print data, for example, the ejection device 3
1a and the injection device 31b are selected, the metal electrode 11
A driving electric field is applied between each of the metal electrodes 11a and 11b and the metal electrodes 11c and 11d. At this time, since the driving electric field direction and the polarization direction are perpendicular to each other, the side walls 13a and 13b
As shown in (1), they are deformed inward of the flow channel 31a and the flow channel 31b, respectively. Here, the flow path 31a is
The flow path 31b is composed of the piezoelectric ceramic plate 1 and its side wall 13b, the cover plate 2 and its side wall 21b. Due to the deformation, the volumes of the ink flow paths 31a and 31b decrease, the ink pressure in the flow paths increases, and ink droplets are ejected from the orifices 41 corresponding to each flow path. Also,
When the application of the driving electric field is stopped, the side walls 13a and 13b
Since the ink returns to the position before the deformation, the ink pressure in the flow path decreases, and ink is supplied into each flow path from an ink supply unit (not shown).

The array is manufactured by the following manufacturing method. As shown in FIG. 3, a plurality of grooves having a part of the inner surface forming a flow path having the above-mentioned shape are formed on the piezoelectric ceramic plate 1 which has been subjected to polarization processing in the direction of arrow d by grinding or the like by rotation of a diamond cutting disk. 3 is manufactured. This groove 3
The above-mentioned electrodes are formed on the surface by sputtering or the like. In addition, the cover plate 2 made of a metal material, a glass material, a ceramic material, a resin material, or the like, has a plurality of processing methods that differ depending on the material, but a part of the inner surface of which forms a flow path having the above-described shape by grinding or shaping. A groove 6 is formed and bonded to the piezoelectric ceramic plate 1 to form an ink flow path.
Further, the orifice plate 4 having the orifice 41 provided at a position corresponding to the position of the flow path is bonded to the end surfaces 14 and 22 of the grooves of the piezoelectric ceramic plate 1 and the cover plate 2 on the ink ejection side.

As described above, in the liquid droplet ejecting apparatus according to the present embodiment, the wall of the piezoelectric ceramics plate 1 which is deformed only in a single direction and the cover which is located opposite to the direction in which the wall of the piezoelectric transducer is deformed. The piezoelectric ceramic plate 1 and the cover plate 2 are formed so that the wall of the plate 2, the bottom surface of the groove of the piezoelectric ceramic plate 1, and the bottom surface of the groove of the cover plate 2 constitute one ink flow path. As described above, ink droplets can be simultaneously ejected from adjacent flow paths without interference with each other as described above. As a result, compared to the conventional method, it is possible to improve the printing speed and simplify the control of the ejection of the ink droplets when forming characters, figures, and images.

The present embodiment is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present embodiment.

For example, in this embodiment, the upper portions of the plurality of walls of the piezoelectric ceramic plate 1 and the bottom of the groove of the cover plate 2 are bonded. The upper part of the plurality of walls of the plate 2 may be bonded,
The upper portions of the plurality of walls of the piezoelectric ceramic plate 1 may be bonded to the bottoms of the grooves of the cover plate 2, and the bottoms of the grooves of the piezoelectric ceramic plate 1 may be bonded to the upper portions of the plurality of walls of the cover plate 2.

The piezoelectric ceramic plate 1 and the cover plate 2 may be fastened with bolts or the like instead of being bonded.
The polarization direction of the piezoelectric ceramic plate 1 may be opposite to the direction of the arrow d.

[0020]

As is apparent from the above description, the droplet ejecting apparatus according to the present invention is different from the conventional method in that the adjacent ejecting apparatuses are simultaneously driven so that the orifice corresponding to the flow path position is moved from the orifice corresponding to the flow path position. Since droplets can be ejected, the printing speed can be improved and the control of ejecting ink droplets can be simplified when forming characters, figures, and images.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an array constituting a part of a liquid droplet ejecting apparatus according to an embodiment.

FIG. 2 is a cross-sectional view of the inside of a flow channel when a driving electric field is applied to the droplet ejecting apparatus of the present embodiment.

FIG. 3 is a perspective view illustrating a method of manufacturing an array constituting a part of the liquid droplet ejecting apparatus according to the embodiment.

FIG. 4 is a cross-sectional view of an array constituting a part of a conventional droplet ejecting apparatus.

FIG. 5 is a cross-sectional view of the inside of a flow channel when a driving electric field is applied to a conventional droplet ejecting apparatus.

FIG. 6 is a perspective view showing a method of manufacturing an array forming a part of a conventional droplet ejecting apparatus.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 piezoelectric ceramic plate 2 cover plate 3 groove of piezoelectric ceramic plate 5 joint 6 groove of cover plate

Continuation of the front page (56) References JP-A-3-108549 (JP, A) JP-A-2-208050 (JP, A) JP-A-3-175046 (JP, A) JP-A-2-263650 (JP) , A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B41J 2/045 B41J 2/055 B41J 2/16

Claims (1)

(57) [Claims] 1. A droplet ejecting device including a plurality of ejecting devices for ejecting ink in an ink flow path by changing the volume of the ink flow path by using a piezoelectric transducer, wherein a groove of the ink flow path is formed. A plurality of first walls of a piezoelectric transducer that can be deformed only in a single direction, and a plurality of second walls that separate adjacent ink flow paths and that are located opposite to the direction in which the first walls deform. A liquid ejecting apparatus comprising: a first ink flow path between the first wall and the second wall of the piezoelectric transducer.