JP3149448B2 - 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,
More specifically, the present invention relates to a liquid droplet ejecting apparatus utilizing deformation of a piezoelectric material.

[0002]

2. Description of the Related Art Conventionally, a printer head using a piezoelectric ink jet has been proposed in recent years. this is,
By changing the volume of the ink flow path by the dimensional displacement of the piezoelectric actuator, the ink in the ink flow path is ejected from the orifice when the volume is reduced, and the ink is introduced into the ink flow path from the other valve 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.

FIG. 7 shows an example of this type of droplet ejecting apparatus. Hereinafter, a conventional example will be specifically described with reference to FIG. 7 showing a partial cross-sectional view of an array. An upper piezoelectric element having a plurality of side walls 60a, 60c, 60e, and 60g and having been subjected to polarization processing in the direction of arrow 26 Ceramic plate 2 and a plurality of side walls 60b, 60d, 60f, 60h
And the lower piezoelectric ceramics plate 3 which has been polarized in the direction of arrow 28 is bonded to the lower piezoelectric ceramics plate 3 via the adhesive layer 12, so that a large number of parallel ink flow paths 4a, 4b spaced from each other in the lateral direction are provided. , 4c and 4d. The ink flow path 4 has a long and narrow rectangular cross section, and the side wall 60 extends over the entire length of the flow path and can be deformed perpendicularly to the flow path axis to change the ink pressure in the flow path. A metal electrode 6 for applying a driving electric field is formed on the surface of the side wall 60.
Has been treated to prevent corrosion by ink.

In this array, for example, when the ejection device 34b is selected according to predetermined print data, the metal electrode 6
A driving electric field is applied between the electrodes b, 6c and the metal electrodes 6d, 6e. At this time, since the driving electric field direction and the polarization direction are orthogonal to each other, the side walls 60c, 60d and the side walls 60e, 60
f is deformed into a V-shape toward the inside of the ink flow path 4b by the piezoelectric thickness-shear effect. Due to this deformation, the ink pressure in the ink flow path 4b increases, and ink droplets are ejected from an orifice (not shown).

[0005]

However, in the above-described conventional droplet ejecting apparatus, a driving metal electrode is formed on the inner wall of a groove of a piezoelectric ceramic plate having a groove for forming an ink flow path in a manufacturing process. And a passivation treatment for preventing corrosion of the electrode was required. For this reason, there was a problem that the cost at the time of manufacture was high.

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 a small number of manufacturing steps and a low manufacturing cost.

[0007]

In order to achieve this object, a liquid drop ejecting apparatus according to the present invention uses a piezo-electric material to change the volume of an ink passage to eject ink in the ink passage. In a droplet ejection device equipped with many devices,
Ink in the ink flow path is a conductive ink filled in the ink flow path in contact with the piezoelectric material, said Lee
Provided at a position come in contact with the conductive ink of the ink flow path in a portion of the ink flow path, a drive line for applying a voltage on the conductive ink, by the driving line, the conductive An electric field is applied to the piezoelectric material in contact with the conductive ink using the ink as an electrode to deform the piezoelectric material by a piezoelectric effect.

[0008]

According to the droplet ejecting apparatus of the present invention having the above structure, when a voltage is applied to the conductive ink in the ink flow path, an electric field is applied to the piezoelectric material using the conductive ink in contact with the piezoelectric material as an electrode. Applied, the piezoelectric material deforms the piezoelectric effect,
The ink is ejected from the ejection device by changing the volume of the flow path.

[0009]

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

FIG. 6 is a view showing a main part of an ink jet printer equipped with a droplet ejecting apparatus according to one embodiment of the present invention. A platen 36 supporting a paper 58 can be rotated on a frame 40 by a shaft 38. And is driven by a motor 42. A droplet ejecting device 44 is provided to face the platen 36. Droplet ejector 44
Is mounted on a carriage 48 together with the ink supply device 46. The carriage 48 is slidably supported by two guide rods 50 arranged in parallel with the axis of the platen 36, and is coupled with a timing belt 56 wound around a pair of pulleys 52. Then, the one pulley 52 is rotated by the motor 54 and the timing belt 56 is fed, so that the carriage 48
Is moved along the platen 36.

FIG. 1 is a sectional view of an array 1 used in the droplet ejecting apparatus 44. The array 1 is polarized in the direction of the arrow 26 and has side walls 60a, 60c, 60
e, 60g, the upper piezoelectric ceramic plate 2 having a plurality of downwardly-opening parallel grooves and a polarization treatment in the direction of arrow 28, and side walls 60b, 60d, 60
f, 60h and a lower piezoelectric ceramics plate 3 having a plurality of parallel grooves which are open in the upward direction.
The ink passages 4a, 4b, 4c, 4d, and 4e having a rectangular cross section are formed by bonding at the 0 portion via the adhesive layer 12. Conductive ink as ink in the ink flow path 4;
For example, it is filled with a water-soluble ink.

Each array 1 is provided with an electric circuit shown in FIG. Ink flow paths 4a, 4
b, 4c, 4d, and 4e are separately connected to the driving LSI chip 16 via the driving line 17, and the clock line 18, the data line 20, the voltage line 22, and the ground line 24 are also connected to the driving LSI chip 1.
6 is connected. Ink channels 4 are not adjacent to each other.
The clock line 18 is divided into a second group.
Successive clock pulses supplied from the first and second groups continuously drive the first and second groups. The data in the multi-bit word format appearing on the data line 20 determines which of the ink flow paths 4 of each group should be activated, and the ink flow path 4 of the group selected by the circuit of the driving LSI chip 16. The voltage V of the voltage line 22 is applied to the ink inside. This voltage causes the side walls 60 on both sides of the ink flow path 4 selected to be deformed by the piezoelectric effect, and thus all the ink flow paths 4 can be operated in each group. At this time, the ink in the same group of ink flow paths 4 that is not activated and the ink in all the ink flow paths 4 belonging to other groups are grounded.

FIG. 2 shows a case where the ejection device 34c is selected according to predetermined print data.
The voltage V of the voltage line 22 is applied to the ink in c, and the ink in the other ink flow paths 4a, 4b, 4d, and 4e is grounded. Since an electric field perpendicular to the direction of polarization is applied to the side walls 60c, 60d, 60e and 60f, the side walls 60c and 60d and the side walls 60c and 60d are deformed by the piezoelectric thickness-shear effect.
e and 60f are deformed into a V 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 from an orifice (not shown).
For example, when another injection device 34b is selected,
The side walls 60a, 60b, 60c, and 60d are deformed, and the ink in the ink flow path 4b is ejected.

The array 1 is easily manufactured by the following manufacturing method.

As shown in FIG. 3 (a), first, a two-step step-like shape obtained by performing a polarization treatment in the direction of arrow 28 with a ceramic material of lead zirconate titanate (PZT) having ferroelectricity is used. A plate is prepared, and the piezoelectric ceramics 3b having a small thickness is prepared.
A plurality of parallel grooves are cut from the portion toward the thick piezoelectric ceramic portion 3a by rotating a diamond cutting disk or laser or the like to form an ink flow path 4, thereby producing a lower ceramic plate 3. At this time, as shown in FIG. 3B, the ink flow path 4 is stopped when it is slightly cut into the thick piezoelectric ceramics 3a. As shown in FIG. 3C, a drive line 17 and a drive LSI chip 16 are arranged on the thick piezoelectric ceramic portion 3a of the lower piezoelectric ceramic plate 3, and the lower piezoelectric ceramic plate 3 has a thin piezoelectric plate. The upper piezoelectric ceramics plate 2 which has been subjected to the polarization process in the direction of arrow 26 is joined to the ceramics 3b at the side wall 60 in a manner that the piezoelectric ceramics 3b is turned upside down.

The portion where the ink flow path 4 is slightly cut into the thick piezoelectric ceramic 3a is the ink supply port 1.
4 is formed. An array 1 is obtained by joining an orifice plate 8 having an orifice 10 for ejecting liquid droplets corresponding to the ink flow path 4 in front of the ink flow path 4. Each of the ink flow paths 4 has a longitudinal sectional shape as shown in FIG. 4 and is connected to an ink supply port 14 opening upward. The ink supply port 14 is not connected to the ink supply device 46, and ink droplets are dropped from the ink supply device 46 as needed. This prevents the ink in each ink flow path 4 from being electrically short-circuited. Also,
The ink in the ink flow path 4 at both left and right ends of the ink flow path 4 to be ejected works only as a drive electrode, and is not ejected.

As described above, in the droplet ejecting apparatus of the present embodiment,
The process of forming a metal electrode and the passivation process for preventing corrosion of the electrode, which have been conventionally required, are not required, and the manufacturing cost is reduced.

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, the ink need not be limited to water-soluble but may be anything as long as it has conductivity. The displacement mode of the piezoelectric ceramic is not limited to the piezoelectric thickness-shear effect, but may be any mode. For example, FIG. 5 shows a configuration example in the case of the displacement mode of the piezoelectric longitudinal effect. Although a metal electrode 6 is provided for a common ground electrode, it is not necessary to form a split electrode corresponding to the ink flow path 4.

[0019]

As is apparent from the above description, the droplet ejecting apparatus of the present invention uses the ink in the ink flow path as conductive and used as the driving electrode.
In addition, the passivation step is not required, and the manufacturing cost can be reduced.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing a state in which an electric circuit is provided in an array.

FIG. 3 is a perspective view showing an array manufacturing process.

FIG. 4 is a longitudinal sectional view of the array.

FIG. 5 is a cross-sectional view of an array constituting a part of a droplet ejecting apparatus according to another embodiment.

FIG. 6 is a perspective view illustrating a main part of an ink jet printer equipped with a droplet ejecting apparatus.

FIG. 7 is a cross-sectional view of an array constituting a part of a liquid droplet ejecting apparatus in a conventional example.

[Explanation of symbols]

 2 Piezoelectric ceramics (upper piezoelectric ceramics plate) 3 Piezoelectric ceramics (lower piezoelectric ceramics plate) 4 Ink flow path 34 Injection device 44 Droplet ejection device

Continued on the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B41J 2/045 B41J 2/055 B41J 2/175 H01L 41/09

Claims (1)

(57) [Claims] In a droplet ejecting apparatus provided with a large number of ejecting devices for ejecting ink in an ink flow path by changing the volume of the ink flow path using a piezoelectric material, the ink in the ink flow path is provided. but wherein a conductive ink filled in the ink flow path in contact with the piezoelectric material, provided at a position come in contact with the conductive ink of the ink flow path in a portion of the ink flow path, said A drive line for applying a voltage to the conductive ink is provided, and the drive line applies an electric field to the piezoelectric material in contact with the conductive ink using the conductive ink as an electrode,
A droplet ejecting apparatus, wherein the piezoelectric material is deformed by a piezoelectric effect.