JPH04292947A - Liquid drop jetting device - Google Patents

Abstract

PURPOSE:To simplify the structure and lower the cost by a method wherein in a device in which a volume of an ink flow path is changed by a piezoelectric transducer for jetting ink, the ink flow paths are radially disposed on the flat surface of the piezoelectric transducer. CONSTITUTION:A piezoelectric transducer 1 formed by laminating two disk-form piezoelectric ceramics plates 2, 3 is provided rotatably about a rotation center. Ink flow paths 6 to be filled with ink and side walls 60 are disposed radially about a rotating shaft 30 of the piezoelectric transducer 1. On the periphery of the transducer 1, an orifice plate ring 12 having orifices 10 connecting to the ink flow paths 6 is provided. Under the upper piezoelectric ceramics plate 2, an LSI chip 16 covered with an insulating layer 32 is loaded. The ink flow path 6 has a rectangular cross section which is reduced in width toward the rotation center 7. On the surface of each of the side walls 60 inside the flow path, an electrode 4 treated to be insulated from ink is provided.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a droplet ejecting device.

0002

2. Description of the Related Art Conventionally, printer heads using piezoelectric inkjet have been proposed in recent years. this is,
By changing the volume of the ink flow path by dimensional displacement of the piezoelectric actuator, ink in the ink flow path is ejected from the orifice when the volume decreases, and ink is introduced into the ink flow path from the other valve when the volume increases. This is called the drop-on-demand method. By arranging a large number of such ejecting devices close to each other and ejecting ink from the ejecting devices at predetermined positions, desired characters and images are formed.

0003

[Problems to be Solved by the Invention] However, since the above-mentioned conventional droplet jetting device uses one piezoelectric transducer for one jetting device, it is necessary to use a large number of jetting devices in order to perform high-speed printing with high resolution. If you try to arrange them closely, the problem is that the structure is complicated, requires many manufacturing steps, and becomes expensive.

The present invention has been made in order to solve the above-mentioned problems, and it is an object of the present invention to provide a droplet ejecting device that has a simple structure, low manufacturing cost, and can realize high resolution and high printing speed. purpose.

[0005]

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 equipped with the device, the ink flow path is arranged radially on a plane of the piezoelectric transducer, and the piezoelectric transducer is arranged so that the piezoelectric transducer passes through its radial center and is substantially perpendicular to the longitudinal direction of the ink flow path. It is characterized by being rotatable about a rotation axis.

[0006]

[Operation] According to the droplet ejecting device of the present invention having the above-mentioned configuration, the ink flow path corresponding to a predetermined ejection device is deformed, and the ink in the flow path is ejected while rotating. Move relative to something.

[0007]

[Example] Hereinafter, an example embodying the present invention will be shown in Figure 1.
This will be described in detail with reference to FIGS. FIG. 1 is a partially cutaway plan view of a piezoelectric transducer 1. FIG. Center of rotation 7
Two disc-shaped piezoelectric ceramic plates 2 and 3 having a diameter are pasted together, and an ink flow path 6 filled with ink and a side wall 60 are arranged radially around the rotation axis. Further, an orifice plate ring 1 having an orifice 10 connected to the ink flow path 6 on the outer periphery.
2 is placed.

FIG. 2 is a sectional view taken along line AA' in FIG. A rotation shaft 30 passing through the rotation center 7 is attached to the lower part of the piezoelectric transducer 1. The inside of the rotating shaft 30 is an ink supply path 14 connected to an ink reservoir (not shown). Further, the ink supply path 14 is also connected to the ink flow path 6. An LSI chip 16 is attached to the lower part of the upper piezoelectric ceramic plate 2, and an insulating layer 32 is formed on the surface of the LSI chip 16 for insulation from ink. The LSI chip 16 is connected to a drive circuit (not shown) via a line 34 passing through the ink supply path 14.

FIG. 3 is a sectional view taken along the line CC' in FIG. The upper piezoelectric ceramic plate 2 is polarized in the direction of arrow 26 and has a plurality of downwardly opening parallel grooves formed by side walls 60a, 60c, 60e, and 60g, and the upper piezoelectric ceramic plate 2 is polarized in the direction of arrow 28. , and a lower piezoelectric ceramic plate 3 having a plurality of upwardly opening parallel grooves formed by side walls 60b, 60d, 60f, and 60h, are bonded to each other via an adhesive layer 5 at the side wall 60 portion. . Here, the ink flow path 6 has a rectangular cross section, and its width becomes smaller as it approaches the rotation center 7. Electrodes 4 are formed on the inner surfaces of all the side walls 60 in the flow paths, and the surfaces of the electrodes 4 are treated for insulation from ink.

The piezoelectric transducer 1 is manufactured by the following manufacturing method.

As shown in FIG. 5, first, a disc-shaped ceramic material of lead zirconate titanate (PZT) having ferroelectric properties is polarized in opposite directions as shown by arrows 26 and 28. The upper piezoelectric ceramic plate 2 and the lower ceramic plate 3 are prepared by preparing a plate and cutting the required number of parallel grooves in the above-described shape using a laser or the like. A bearing hole into which the rotating shaft 30 is inserted is formed in the center of the lower piezoelectric ceramic plate 3. After forming electrodes 4 on the groove surfaces of both piezoelectric ceramic plates 2 and 3,
The electrode 4 is insulated, and the LSI electrically connected to the electrode 4 is placed in the center of the lower part of the upper piezoelectric ceramic plate.
Attach the chip 16. Both piezoelectric ceramic plates 2 and 3
An orifice plate ring 12 having an orifice 10 for ink jetting is joined to the outer periphery of both piezoelectric ceramic plates 2 and 3,
is configured.

The piezoelectric transducer 1 is provided with an electric circuit shown in FIG. The electrodes 4a to 4h are connected to the LSI chip 16 separately via the drive line 17.
connected to a clock line 18, a data line 20,
A voltage line 22 and a ground line 24 are also connected to the LSI chip 16. The ink channels 6 are located in the first
, divided into a second group, clock line 1
The successive clock pulses supplied from 8
Continue to drive the second group. The data in the form of a multi-bit word appearing on the data line 20 determines which ink flow path 6 of each group is to be activated;
The voltage V of the voltage line 22 is applied to the electrodes 4 of the flow paths of the group selected by the circuit of the SI chip 16. This voltage deforms the side walls 60 on both sides of the selected ink flow path 6 due to the piezoelectric effect, so that all the ink flow paths 6 in each group become operational. At this time, the electrodes 4 of the ink channels 6 of the same group that are not activated and the electrodes 4 of all the ink channels 6 belonging to other groups are grounded.

FIG. 4 shows a case where the ejecting device 8c is selected according to predetermined print data, and the ink flow path 6c
The voltage V of the voltage line 22 is applied to the inner electrodes 4d and 4e, and the other electrodes 4a, 4b, 4c, 4f, 4g, and 4h are grounded. Since an electric field perpendicular to the polarization direction is applied to the side walls 60c, 60d, 60e, and 60f, the side walls 60c, 60d and the side wall 6 are deformed due to the piezoelectric thickness shear effect.
0e and 60f are deformed into a dogleg shape toward the ink flow path 6c between them. Therefore, the volume of the ink flow path 6c decreases, and the ink within the flow path is ejected from the orifice 10. Further, the application of voltage is cut off and the side walls 60c, 60d, 60
When e and 60f are returned to their original positions, ink is replenished from the ink supply device via a valve (not shown) as the volume of the ink flow path 6c increases at that time. Note that, for example, if another injection device 8b is selected, the side walls 60a, 60
b, 60c, and 60d are deformed, and the ink in the ink flow path 6b is ejected.

FIGS. 6(a) to 6(c) are diagrams showing the moving direction of the piezoelectric transducer 1. The piezoelectric transducer 1 rotates at a constant speed in the rotation direction 40 about the rotation center 7. There is. The recording paper 70 partially forms a cylindrical body at the outer circumference of the piezoelectric transducer 1, and the piezoelectric transducer 1
ejects ink droplets 36 toward its outer periphery while moving relatively in the movement direction 38 .

In the droplet jetting device according to this embodiment,
Since the displacement of the piezoelectric thickness shear effect is utilized, a single piezoelectric transducer 9 that functions as a transducer for a large number of injection devices 8 can be easily made by simply forming grooves and electrodes, and as a result, the structure is simplified. This reduces the number of manufacturing steps and reduces manufacturing costs. In addition, since the piezoelectric transducer 1 is disk-shaped and performs spraying operation while rotating at a constant speed, the printing range per time increases.
Furthermore, it is possible to perform printing with a distance between adjacent dots smaller than the pitch of the ink flow paths 6, thereby realizing high speed and high resolution.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and can be modified in many ways without departing from the spirit thereof. For example, piezoelectric ceramic plate 2,
3 by injection molding, it is possible to eliminate the step of forming the grooves for the ink flow path 6. Further, if the ink flow path 6 is formed into a groove with a constant width, processing using a normal blade becomes possible. Further, the orifice 10 does not need to be located on the outer periphery of the piezoelectric transducer 1, and may be provided on the upper part of the piezoelectric transducer 1 as shown in FIGS. 7 and 8. In this case, the recording paper is placed on top of the piezoelectric transducer 1 perpendicular to the axis passing through the center of rotation 7, and the piezoelectric transducer 1 moves relative to the recording paper in the direction of movement 38. FIG. 8 shows an example in which the distance of the orifice 10 from the rotation center 7 is changed in order to further improve printing resolution.

[0017]

Effects of the Invention As is clear from the above explanation, the droplet injection device of the present invention has a simple structure because a single piezoelectric transducer that performs displacement due to the piezoelectric thickness shear effect functions as a transducer for a large number of injection devices. This simplifies the process, reduces the number of manufacturing steps, and reduces manufacturing costs. Also,
Since the droplet ejecting device performs the ejecting operation while rotating, the printing range per time increases and the printing pitch becomes finer. This results in lower manufacturing costs, higher printing speeds, and
A droplet ejecting device with high resolution can be provided.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway plan view of a piezoelectric transducer.

FIG. 2 is a sectional view taken along line AA' of the piezoelectric transducer.

FIG. 3 is a cross-sectional view taken along line CC' of the piezoelectric transducer.

FIG. 4 is an explanatory diagram of the operation of a piezoelectric transducer.

FIG. 5 is a perspective view showing the manufacturing process of a piezoelectric transducer.

FIG. 6 is an explanatory diagram showing the moving direction of the piezoelectric transducer.

FIG. 7 is a perspective view showing the moving direction of the piezoelectric transducer in another embodiment.

FIG. 8 is a perspective view showing the moving direction of the piezoelectric transducer in another embodiment.

[Explanation of symbols]

1 Piezoelectric transducer 2 Upper piezoelectric ceramic plate 3 Lower piezoelectric ceramic plate 6 Ink flow path 7 Center of rotation 8 Injection device 60 Side wall

Claims (1)

[Claims] 1. In a droplet ejecting device including an ejecting device that ejects ink in an ink flow path by changing the volume of the ink flow path using a piezoelectric transducer, the ink flow path is controlled by a piezoelectric transducer. A droplet ejecting device characterized in that the piezoelectric transducer is arranged radially on a plane and is rotatable about a rotation axis passing through the radial center and substantially perpendicular to the longitudinal direction of the ink flow path. .