JP2932754B2 - 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 structure for preventing clogging of a flow channel due to drying of ink droplets.

[0002]

2. Description of the Related Art Conventionally, ink jet printers such as a bubble jet type using an electrothermal conversion element as a pressure generator and a piezoelectric type using an electromechanical conversion element have lower noise than an impact type printer. For some reason, it has attracted attention in recent years. For example, the piezoelectric type changes the volume of the ink flow path by the dimensional displacement of the piezoelectric actuator, so that the ink in the ink flow path is ejected from the orifice when the volume is reduced, and the ink is injected into the ink flow path when the volume is increased. This is called the drop-on-demand method. Then, by arranging a large number of such ejecting devices close to each other and ejecting ink from the ejecting device at a predetermined position, desired characters and images are formed.

[0003]

However, as shown in the perspective view of FIG. 7, the array 1 constituting the conventional droplet ejecting apparatus has an ink flow path (not shown) formed of a large number of grooves. After joining the piezoelectric ceramic plate 2 and the lid 6 of the ink flow path, a nozzle plate 8 having ejection ports 10 corresponding to the ink flow paths in a one-to-one correspondence.
Must be accurately joined to the end surface of the joined body of the piezoelectric ceramic plate 2 and the lid 6, and at the time of non-printing, the cap 30 is provided with a nozzle plate to prevent clogging of the ink flow path due to drying of the ink. 8, the ink flow path 4 is often clogged in the number of parts, the manufacturing process, and the joining process.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a nozzle plate, a component which does not require a cap, a small number of manufacturing steps, a good yield, a low manufacturing cost, and a clogging of an ink channel. It is an object of the present invention to provide a liquid droplet ejecting apparatus without any problem.

[0005]

In order to achieve this object, a droplet ejecting apparatus according to the present invention ejects ink in the ink flow path by changing the volume of the ink flow path using a pressure generator. In a droplet ejecting apparatus provided with a large number of ejecting apparatuses, a plate made of piezoelectric ceramics, an ink flow path formed on the plate, and having a first groove one end of which is separated from the edge by a predetermined distance, A lid having an ejection port formed of a second groove communicating with the ink flow path in a one-to-one manner, and a lid joined to the plate so as to be relatively movable in a longitudinal direction of the first groove; At the time of non-printing, the lid is relatively moved to a position where the second groove does not communicate with the first groove, thereby preventing contact between ink and outside air.

[0006]

According to the liquid droplet ejecting apparatus of the present invention having the above-described structure, when the volume of the ink flow path corresponding to the predetermined ejecting apparatus is reduced, the ink in the flow path is discharged from the ejection port formed by the groove provided on the substrate. When ejected, the substrate slides on the plate during non-printing to prevent contact between the ink and the outside air.

[0007]

FIG. 1 shows an embodiment of the present invention.
This will be described in detail with reference to FIGS. For convenience, the same parts as those in the conventional example and the equivalent parts will be described with the same reference numerals.

As shown in FIG. 1, a droplet ejecting apparatus according to this embodiment includes a piezoelectric ceramic plate 2 having an ink flow path 4 composed of a large number of parallel grooves as shown in a perspective view of a part of the array 1. A lid 6 having an ejection port 10 formed of a groove corresponding to the ink flow path 4 on a one-to-one basis;
2 and an elastic spring 14 made of rubber or the like, the other end of which is fixed to the back surface of the piezoelectric ceramic plate 2. A cam 12 is mounted behind the piezoelectric ceramic plate 2 so that the cam 12 can be rotated by a motor (not shown), and the cam 12 is in contact with the lid 6 in a state where the short-diameter direction of the cam 12 coincides with the direction of the ink flow path 4. Have been.

As shown in the side sectional view of FIG. 3, the ink flow path 4 has an uncut portion 3 at the end of the piezoelectric ceramic plate 2, and the ejection port 10 is provided in the ink flow path 4. The groove 3 has a smaller cross-sectional area than the uncut portion 3 and is longer in the flow path direction than the uncut portion 3.
Are connected to one of the ejection ports 10 at the end of the flow path having the uncut portion 3, and further connected to an ink supply unit (not shown) at the other end.

FIG. 5 is a sectional view of a communication portion between the ink flow path 4 and the ejection port 10 of the array 1 used in the droplet ejection apparatus. The array 1 has a groove formed by a plurality of parallel ink flow paths 4 having a width of 0.1 mm and a height of 0.25 mm, which has been subjected to polarization processing in the direction of arrow 28, and has a width across the ink flow path 4. And a lid 6 having a plurality of parallel ejection ports 10 having a width of 0.04 mm, a height of 0.06 mm, and a semi-oval cross section. Consists of

The piezoelectric ceramic plate 2 is prepared by preparing a plate having a thickness of 0.4 mm obtained by subjecting a lead zirconate titanate (PZT) -based ceramic material having ferroelectricity to a polarization treatment in the direction of arrow 28. A parallel groove having the above-mentioned shape is obtained by cutting the necessary number of the remaining uncut portions 3 by rotating a diamond cutting disk or laser or the like, forming an electrode 7 on the surface of the groove, and performing insulation treatment. The lid 6 is prepared by preparing a plate having a thickness of 0.2 mm made of the same kind of material as the piezoelectric ceramics plate 2 which is not subjected to polarization processing or another material, and forming parallel grooves having the above-mentioned shapes by rotating a diamond cutting disk. It can be obtained by cutting the required number by laser or etching. The ink flow path 4 and the ejection port 10
The piezoelectric ceramic plate 2 and the lid 6 are relatively movably engaged in the direction of the flow path so that the one-to-one correspondence is obtained, whereby the array 1 is obtained.

The array 1 is provided with an electric circuit shown in FIG. In this electric circuit, the electrode 7a
~ 7g are separately connected to the LSI chip 16, respectively.
Clock line 18, data line 20, voltage line 2
2 and the ground line 24 are also connected to the LSI chip 24. The ink flow paths 4a to 4e are divided into first and second groups that are not adjacent to each other, and a continuous clock pulse supplied from the clock line 18 is used for the first and second groups.
Drive the group continuously.

The data in the form of multi-bit words appearing on the data line 20 determines which of the ink flow paths 4a to 4e of each group is to be activated, and the flow of the group selected by the circuit of the LSI chip 16 is determined. Road electrodes 7a-
The voltage V of the voltage line 22 is applied to 7 g. Side walls 5a to 5e on both sides of the ink flow paths 4a to 4e selected by this voltage.
5f is deformed by the piezoelectric effect, so that all the ink flow paths 4a to 4e can be operated in each group. At this time, the ink flow paths 4a to 4a of the same group which are not operated
The electrodes 7a to 7g of 4e and the electrodes 7a to 7g of all the ink flow paths 4a to 4e belonging to other groups are grounded.
The injection devices 34a to 34e are formed with the above configuration.

FIG. 6 shows a case where the ejection device 34c at the center of the ejection device 34 is selected in accordance with predetermined print data. The voltage V of the voltage line 22 is applied to the electrode 7c in the ink flow path 4c. , Other electrodes 7a, 7b, 7d,
7e, 7f, 7g are grounded. Since an electric field (in the direction of the arrow in the drawing) perpendicular to the polarization direction is applied to the side walls 5c and 5d, the side walls 5c and 5d are deformed by the piezoelectric thickness-shear effect.
d is deformed into a C-shape toward the inside of the ink flow path 4c.
Therefore, the volume of the ink flow path 4c is reduced, and the ink in the flow path is ejected through the ejection port 10c. When the application of the voltage is cut off and the side walls 5c and 5d are returned to their original positions, ink is replenished from the ink supply unit (not shown) with the increase in the volume of the ink flow path 4c at that time. Incidentally, for example, when another injection device 34b is selected, the side wall 5
The b and 5c are deformed, and the ink in the ink flow path 4b is ejected.

The array 1 constituting the droplet ejecting apparatus of the present embodiment described above has a cam 1 as shown in FIG.
When the cam 12 is rotated to a position where the major axis direction of the ink passage 4 coincides with the direction of the major axis of the ink passage 4, the lid 6 is moved in the forward direction of the passage with respect to the piezoelectric ceramic plate 2 to the length of the groove forming the ejection port 10. Slides by a distance equal to or greater than the difference between the length of the uncut portion of the piezoelectric ceramic plate 2 and the elastic spring 14 undergoes a shear deformation to store elastic energy. At this time, as shown in the side sectional view of FIG. 4, the ink flow path 4 and the ejection port 10 are not communicated with each other, so that the ink in the flow path is not in contact with the outside air and the drying of the ink is prevented. When the cam 12 is rotated to the original position when it is driven again, the elastic spring 14 releases the stored elastic energy and returns to the original shape.
Returns to the original position shown in FIG. 1, and the ink flow path 4 and the ejection port 10 communicate with each other.

The liquid droplet ejecting apparatus according to the present embodiment does not require the nozzle plate 8 having the ejection port 10 and the cap 30 as compared with the conventional liquid droplet ejecting apparatus shown in FIG. 7, thereby reducing the number of parts and the number of joining steps. As a result, the manufacturing cost can be reduced, and the clogging of the ink flow path 4 which is likely to occur during joining and non-printing can be reduced, and the yield and reliability can be improved.

It should be noted that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, a non-piezoelectric material may be used for the plate having the ink flow path, and the lid may be made of piezoelectric ceramics that undergoes a longitudinal effect deformation. Of course, an electrothermal transducer may be used as the pressure generator. Also, the relative sliding direction between the grooved plate and the lid is not limited to the flow path direction but may be, for example, in the array direction as long as the contact between the ink and the outside air is cut off.

[0018]

As is apparent from the above description, the droplet ejecting apparatus according to the present invention is constructed so that the ejecting port can be formed without the nozzle plate, and the ink is prevented from drying without the cap. In addition, it is possible to provide a liquid droplet ejecting apparatus which requires less joining steps, has a low manufacturing cost, and has good ink yield without clogging.

[Brief description of the drawings]

FIG. 1 is a perspective view of an array constituting a droplet ejecting apparatus.

FIG. 2 is a transparent perspective view showing a state in which a flow path of the array is cut off from outside air.

FIG. 3 is a side sectional view of a part of an array constituting the droplet ejecting apparatus.

FIG. 4 is a side cross-sectional view showing a state in which a flow path of the array is cut off from outside air.

FIG. 5 is a front sectional view of a part of an array constituting the droplet ejecting apparatus.

FIG. 6 is an explanatory diagram showing a driving state.

FIG. 7 is a perspective view showing an array constituting a droplet ejection device in a conventional example.

[Explanation of symbols]

 2 Piezoelectric ceramic plate (pressure generator) 4 Ink channel 6 Lid (substrate) 10 Injection port 34 Injection device

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-214451 (JP, A) JP-A-63-22661 (JP, A) Real opening Sho-61-93250 (JP, U) (58) Field (Int.Cl. ⁶ , DB name) B41J 2/045 B41J 2/055 B41J 2/165

Claims (1)

(57) [Claims] 1. A droplet ejecting apparatus having a large number of ejecting apparatuses for ejecting ink in an ink flow path by changing the volume of the ink flow path by using a pressure generator, comprising: a plate made of piezoelectric ceramic; An ink flow path composed of a first groove formed on a plate and having one end separated from the edge by a predetermined distance, and an ejection port composed of a second groove communicating one-to-one with the ink flow path. And a lid joined to the plate so as to be relatively movable in the longitudinal direction of the first groove, wherein the second groove is the first groove when printing is not performed.
Relative movement of the lid to a position that does not communicate with the groove of
A droplet ejecting apparatus for preventing contact between ink and outside air.