JP3114437B2 - Ink jet device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet apparatus.

[0002]

2. Description of the Related Art Conventionally, a drop-on-demand type ink jet printer head using piezoelectric ceramics has been proposed as a printer head. This is because, by changing the volume of the ink liquid chamber by deformation of the piezoelectric ceramics, the ink in the ink liquid chamber is ejected as droplets from the nozzle when the volume decreases, and when the volume increases, the ink enters the ink liquid chamber from the other ink introduction path. Ink is introduced. A large number of such ink liquid chambers are arranged close to each other, and ink droplets are ejected from a nozzle at a desired position in accordance with desired print data. An image is formed.

[0003] For example, Japanese Patent Application Laid-Open Nos. 63-27051 and 63-252 disclose such an ink ejecting apparatus.
750 and JP-A-2-150355. FIG. 14, FIG. 15, FIG. 16, FIG.
7 and 18 are schematic diagrams of these conventional examples. Hereinafter, the configuration of the conventional example will be specifically described with reference to FIG. 14 showing a cross-sectional view of the ink ejecting apparatus. A piezoelectric ceramic plate 1 having a plurality of grooves 15 (FIG. 16) and side walls 11 separating the grooves 15 and having been subjected to polarization processing in the direction of arrow 4 and a cover plate 2 made of a ceramic material or a resin material The groove 15 (FIG. 16) becomes a plurality of ink liquid chambers 12 spaced from each other in the lateral direction by bonding via the bonding layer 3 made of epoxy adhesive or the like. Ink liquid chamber 1
Reference numeral 2 denotes an elongated shape having a rectangular cross section, and the side wall 11 extends over the entire length of the ink liquid chamber 12. Electrodes 13 for applying a driving electric field are formed on both surfaces from the upper portion of the side wall 11 near the adhesive layer 3 to the center of the side wall 11.
All the ink liquid chambers 12 are filled with ink.

FIG. 1 is a cross-sectional view of an ink ejecting apparatus.
5, the operation of the conventional example will be described. In the ink ejecting apparatus, for example, when the ink liquid chamber 12b is selected according to desired print data, a positive drive voltage is rapidly applied to the electrodes 13e and 13f, and the electrodes 13d and 13g are grounded. As a result, a driving electric field in the direction of arrow 14b acts on the side wall 11b, and a driving electric field in the direction of arrow 14c acts on the side wall 11c. At this time, since the driving electric field directions 14b and 14c are orthogonal to the polarization direction 4, the side walls 11b and 11c
c rapidly deforms toward the inside of the ink liquid chamber 12b due to the piezoelectric thickness-shear effect. Due to this deformation, the volume of the ink liquid chamber 12b decreases, the ink pressure in the ink liquid chamber 12b rapidly increases, and a pressure wave is generated.
Ink droplets are ejected from the nozzle 32 (FIG. 16) communicating with b. When the application of the driving voltage is gradually stopped,
Since the side walls 11b and 11c return to the positions before deformation (see FIG. 14), the ink pressure in the ink liquid chamber 12b gradually decreases, and the manifold 22 is moved from the ink supply port 21 (FIG. 16).
Ink is supplied into the ink liquid chamber 12b through (FIG. 16).

In the conventional example, since ink droplets cannot be simultaneously ejected from two nozzles communicating with two adjacent ink liquid chambers, for example, nozzles communicating with odd-numbered ink liquid chambers 12a and 12c from the left end After the ink droplets are ejected from the ink liquid chambers 12b and 12d, the ink droplets are ejected from the nozzles communicating with the even-numbered ink liquid chambers 12b and 12d, and then the ink droplets are ejected again from the odd-numbered ink chambers. And the nozzles 32 are divided into a plurality of groups to eject ink droplets.

However, the above operation is merely a basic operation of the conventional example, and when embodied as a product, first, a drive voltage is applied in a direction of increasing the volume, and the ink liquid chamber 12b is first applied.
After the supply of the ink, the application of the driving voltage may be stopped to return to the original state (see FIG. 14), and the ink may be ejected.

Next, FIG. 1 is a perspective view of an ink ejecting apparatus.
6, the configuration and manufacturing method of the conventional example will be described. Parallel grooves 15 for forming the ink liquid chambers 12 are formed on the polarized piezoelectric ceramic plate 1 by grinding using a thin disk-shaped diamond blade or the like. The groove 15 is a parallel groove having the same depth over almost the entire area of the piezoelectric ceramic plate 1, but gradually becomes shallower as approaching the end face 17, and becomes shallow and parallel near the end face 17.
8 is produced. The electrodes 13 are formed on the inner surfaces of the groove 15 and the shallow parallel groove 18 by sputtering or the like. On the inner surface of the groove 15, the electrode 13 is formed only on the upper half of the side surface. On the inner surface of the shallow and parallel groove 18, the electrode 13 is formed on the entire side surface and bottom surface.
Further, the ink inlet 21 and the manifold 22 are formed on the cover plate 2 made of a ceramic material or a resin material by grinding or cutting.

Next, the grooves 1 of the piezoelectric ceramic plate 1
(5) The surface on the processing side and the surface on the processing side of the manifold 22 of the cover plate 2 are bonded to each other with an epoxy-based adhesive or the like so that each of the grooves 15 forms the ink liquid chamber 12 having the above-described shape. Next, the nozzle plate 3 provided with the nozzle 32 at a position corresponding to the position of each ink liquid chamber 12 on the end face 16 of the piezoelectric ceramic plate 1 and the cover plate 2.
1 is adhered. A substrate 41 provided with a conductive layer pattern 42 at a position corresponding to the position of each ink liquid chamber 12 on the surface of the piezoelectric ceramic plate 1 opposite to the groove 15 processing side.
Are bonded with an epoxy adhesive or the like. Then, the electrode 13 and the conductive layer pattern 4 on the bottom of the shallow parallel groove 18 are formed.
2 are connected by a conductive wire 43 by well-known wire bonding.

Next, the configuration of a conventional control unit will be described with reference to FIG. 17 showing a block diagram of the control unit. The conductive layer patterns 42 provided on the substrate 41 are individually connected to the LSI chip 51, and the clock line 52, the data line 53, the voltage line 54, and the ground line 55 are also connected to the LSI chip 51.
It is connected to a chip 51. The LSI chip 51 determines from the data appearing on the data line 53 which nozzle 32 should eject the ink droplet based on the continuous clock pulse supplied from the clock line 52, The voltage V of the voltage line 54 is applied to the pattern 42 of the conductive layer that is electrically connected to the electrode 13 in the chamber 12.
Is applied. Further, the electrodes 13 other than the ink liquid chamber 12
The voltage 0 of the ground line 55 is applied to the pattern 42 of the conductive layer which is conducted to the conductive layer.

Next, the configuration and operation of the conventional example will be described with reference to FIG. 18 showing a perspective view of a printer. The ink ejection device 61 and the nozzle plate 31 have the configuration and operation described with reference to FIG. 14, FIG. 15, and FIG. The ink ejection device 61 is fixed on a carriage 62, the ink supply tube 63 communicates with the ink supply port 21 (FIG. 16), the LSI chip 51 (FIG. 17) is built in the carriage 62, and the flexible cable 64 is Clock line 52, data line 53, and voltage line 54 shown
And the ground line 55. Carriage 62
Reciprocates along the slider 66 in the direction of arrow 65 over the entire width of the recording paper 71, and the ink ejecting device 61 moves the nozzle plate 31 against the recording paper 71 held by the platen roller 72 while the carriage 62 is moving. Ink droplets are ejected from nozzles 32 (FIG. 16) provided in
Ink droplets are made to adhere to the recording paper 71.

The recording paper 71 is stationary when the ink ejecting device 61 ejects ink droplets, but each time the carriage 62 reciprocates, it is moved in the direction of arrow 75 by the paper feed rollers 73 and 74. It is transferred by a fixed amount. Thus, the ink ejecting apparatus 61 can form desired characters and images on the entire surface of the recording paper 71.

[0012]

However, in the above-described conventional ink ejecting apparatus 61, the direction of polarization (arrow 4) and the direction of the electric field generated by application to the electrode 13 (arrows 14b and 14c) are orthogonal to each other. Therefore, when the piezoelectric characteristics of the piezoelectric ceramic plate 1 are deteriorated, it is impossible to perform the repolarization process. Therefore, in the step of forming the electrodes 13 and the step of bonding each component such as the step of bonding the piezoelectric ceramic plate 1 and the cover plate 2, the temperature is higher than the Curie temperature of the piezoelectric material (the temperature at which the piezoelectric characteristics are lost). Heat treatment could not be performed. As a result, the piezoelectric ceramic plate 1 of the electrode 13
And low bonding strength of each part,
At the time of driving, the joint is broken or the electrode 13 is peeled off. For this reason, the amount of deformation of the side wall 11 is reduced, or the electrode 13 is disconnected, so that the voltage is not transmitted to a part of the side wall 11 and a part of the side wall 11 is not deformed, so that the injection becomes unstable. There were also problems. Therefore, there is a problem that the reliability of the ink ejecting apparatus is low.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an ink jet apparatus which has a high bonding strength between components, a long electrode life, and a high reliability. And

[0014]

In order to achieve the above object, according to the first aspect of the present invention, there is provided an ink liquid chamber filled with ink, and a piezoelectric part having at least a part polarized by separating the ink liquid chamber. And a driving electrode formed on the piezoelectric portion so as to generate an electric field substantially orthogonal to the polarization direction, and the thickness of the side wall is increased by applying a voltage to the driving electrode. An ink ejecting apparatus that ejects ink by applying a pressure to ink in the ink liquid chamber by deforming a slipping effect, wherein a pair of piezoelectric elements formed in the piezoelectric portion to generate an electric field parallel to the polarization direction. The electrode for polarization is formed of a material whose electric resistance decreases at a temperature equal to or higher than a predetermined temperature T1 to become a conductor, and whose electric resistance increases at a temperature lower than the predetermined temperature T1 to become an insulator. ,
The driving electrode is made of a material whose electric resistance increases at a temperature equal to or higher than a predetermined temperature T2 to become an insulator, and whose electric resistance decreases at a temperature lower than the predetermined temperature T2 to become a conductor.

In the second aspect, the predetermined temperatures T1, T2
Is characterized in that the temperature is lower than the temperature at which the piezoelectric portion loses piezoelectric characteristics.

According to a third aspect of the present invention, the polarization electrode is composed of a vanadium oxide-based negative temperature characteristic thermistor material, and the driving electrode is composed of a barium titanate-based positive temperature characteristic thermistor material. I do.

[0017]

In the ink jetting apparatus according to the present invention having the above-described structure, the polarization electrode formed on the piezoelectric portion has a predetermined temperature T.
The driving electrode formed of a material whose electric resistance decreases to become a conductor when the electric resistance decreases by 1 or more and whose electric resistance increases below the predetermined temperature T1 becomes an insulator, and which is formed on the piezoelectric portion,
At a temperature equal to or higher than the predetermined temperature T2, the electric resistance increases and the insulator becomes
Since it is made of a material whose electric resistance decreases below the predetermined temperature T2 and becomes an electric conductor, a driving voltage is applied to the driving electrode at the time of driving. However, when polarization is desired, a predetermined temperature T1, T2 or more is required. In this environment, polarization can be freely performed by applying a polarization voltage to the polarization electrode.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. The same members as those in the related art are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 1 is a sectional view of an array used in an ink jetting apparatus according to one embodiment of the present invention. The first CTR internal electrode layer 7 is provided on the actuator ceramic plate 5.
And a plurality of side walls 111 formed by laminating a piezoelectric ceramic layer 6 and a second CTR internal electrode layer 8. Further, a plurality of grooves 15 which are separated by the side wall 111 and open upward in the drawing are provided. The PTC external electrode 9 is formed on the surface of the side wall 111.

The piezoelectric ceramic layer 6 is made of a ferroelectric lead zirconate titanate-based ceramic and is polarized in the direction of arrow 4. Next, FIG.
The first CTR internal electrode layer 7, the second CTR internal electrode layer 8, and the PTC external electrode 9 will be described with reference to FIG. 1st CT
The R internal electrode layer 7 and the second CTR internal electrode layer 8 are insulators at room temperature, but have a temperature lower than the temperature at which the ferroelectricity of the lead zirconate titanate-based ceramics is lost, that is, the Curie temperature (for example, 250 ° C.). At a low predetermined temperature T1 (for example, 70 ° C.) or higher, a vanadium oxide based negative temperature characteristic thermistor material (C
TR thermistor material). Also PTC
The external electrode 9 is a conductor at normal temperature, but has a predetermined temperature T lower than the Curie temperature (for example, 250 ° C.).
It is made of a barium titanate-based positive temperature characteristic thermistor material (PTC thermistor material) which becomes an insulator due to a sudden increase in electric resistance at 2 (for example, 130 ° C.) or more.

As the material of the first CTR internal electrode layer 7 and the second CTR internal electrode layer 8, in addition to vanadium oxide-based thermistor material, nickel oxide-based, cobalt oxide-based, manganese oxide-based, and lanthanum oxide-based negative temperature characteristics are used. A characteristic thermistor material may be used.

The actuator ceramic plate 5
Is manufactured by the following manufacturing method.

First, a lead zirconate titanate-based ceramic material constituting the piezoelectric ceramic layer 6 and a first C
Prepare a vanadium oxide-based negative temperature characteristic thermistor material constituting the TR internal electrode layer 7 and the second CTR internal electrode layer 8 and form them into sheets each having a predetermined thickness by a doctor blade method or the like. As shown in FIG. 3, after lamination, pressure bonding is performed, cut into a predetermined shape, and integrally fired. At this stage, the spontaneous polarization direction of the piezoelectric ceramic layer 6 is random, and does not have piezoelectric characteristics.

Next, as shown in FIG. 4, the required number of grooves 15 are formed by rotation of a diamond cutting disk or laser or the like. Further, as shown in FIG. 5, a PTC external electrode 9 is formed on the inner surface of the groove 15 by using a barium titanate-based positive temperature characteristic thermistor material, and the actuator ceramic plate 5 is obtained. The method of forming the PTC external electrode 9 includes sputtering, vapor deposition, CVD, P
There is a method of firing after a dry process such as VD or thermal spraying or a wet process such as a sol-gel method. However, since the PTC external electrode 9 is formed prior to the polarization step of the piezoelectric ceramic layer 6, the piezoelectric ceramic layer 6 is formed. Even if the bonding is performed by a heat treatment process at a temperature equal to or higher than the Curie temperature (for example, 250 ° C.), there is no problem.
And the PTC external electrode 9 can be firmly adhered.

The actuator ceramic plate 5 thus obtained and the cover plate 2 made of a ceramic material or a resin material are connected to each other at the upper portion of the side wall 111 as shown in FIG. The groove 15 becomes the ink liquid chamber 12 which is spaced apart from each other in the lateral direction by joining through the intermediary 3. The ink liquid chamber 12 has an elongated shape with a rectangular cross section, and the side wall 111 has the ink liquid chamber 1.
2 extending the full length of the two. Piezoelectric ceramic layer 6
In order to join the cover plate 2 before the polarization step, the Curie temperature of the piezoelectric ceramic layer 6 (for example, 25
By performing a heat treatment process at a temperature of 0 ° C. or higher, there is no problem even if the above-described bonding is performed, and a strong bonding between the actuator ceramic plate 5 and the cover plate 2 is possible.

Subsequently, as shown in FIG. 7, the polarization ground terminal 19 is brought into contact with the first CTR internal electrode layer 7, and the polarization plus terminal 20 is brought into contact with the second CTR internal electrode layer 8, respectively. A voltage is applied in the laminating direction of the actuator ceramic plate 5 through the polarization earth terminal 19 and the polarization plus terminal 20 in an insulating oil such as silicon oil. At this time, the temperature of the insulating oil (not shown) is higher than the temperature T1 (70 ° C. in this embodiment) at which the first CTR internal electrode layer 7 and the second CTR internal electrode layer 8 become conductors, and the PTC external electrode 9 is Temperature T2
The temperature is higher than (130 ° C. in this embodiment) and lower than the Curie temperature of the piezoelectric ceramic layer 6 (250 ° C. in this embodiment), for example, about 150 ° C. Then the first
The CTR internal electrode layer 7 and the second CTR internal electrode layer 8 become conductors, the PTC external electrodes 9 become insulators, and the piezoelectric ceramic layer 6 has ferroelectricity. For this reason, a voltage is applied between the first CTR internal electrode layer 7 and the second CTR internal electrode layer 8, and the piezoelectric ceramic layer 6 has an arrow 4
Polarization in the direction of. At this time, the electric field applied to the piezoelectric ceramic layer 6 is, for example, about 2 kV / mm.

The normal operating temperature of the actuator ceramic plate 5 is determined by the first CTR internal electrode layer 7 and the second CTR.
The temperature is sufficiently lower than the temperature T1 (70 ° C. in this embodiment) at which the TR internal electrode layer 8 becomes a conductor and the temperature T2 (130 ° C. in this embodiment) at which the PTC external electrode 9 becomes an insulator.
The C external electrode 9 becomes a conductor and functions as a driving electrode, and the first CTR internal electrode layer 7 and the second CTR internal electrode layer 8
Becomes an insulator and functions only as a constituent material of the side wall 111. In the conventional example (FIG. 14), this polarization step had to be always performed before the formation of the electrode 13. However, in this embodiment, it may be performed at any time. For example, the polarization step may be performed after use as an ink ejecting apparatus. When the piezoelectric characteristics of the ceramic layer 6 are degraded by heat, driving electric field, or the like, repolarization processing is performed, and the ceramic layer 6 can be used again.

An array used in the ink ejecting apparatus according to one embodiment of the present invention is provided with an electric circuit shown in FIG. 2 and all the ink liquid chambers 12 are filled with ink. In this electric circuit, the PTC external electrodes 9a to 9c formed in each groove 15 are individually
The clock line 52, the data line 53, the voltage line 54, and the ground line 55 are also connected to the chip 51.
It is connected to the I chip 51.

The ink liquid chambers 12 are divided into a plurality of groups that are not adjacent to each other, and the LSI chip 51 continuously drives the plurality of groups by a continuous clock pulse supplied from the clock line 52. Data line 53
The data in multi-bit word format appearing above gives LS
The I chip 51 is connected to any of the ink chambers 12 of each group.
Is to be activated, and the selected ink liquid chamber 12 is determined.
The voltage V of the voltage line 54 is applied to the PTC external electrode 9. The side walls 111 on both sides of the selected ink liquid chamber 12 are deformed by the piezoelectric effect of the piezoelectric ceramic layer 6, so that all the ink liquid chambers 12 can be operated in each group. At this time, the PTC external electrodes 9 of the ink liquid chambers 12 of the same group that are not operated and the PTC external electrodes 9 of all the ink liquid chambers 12 belonging to other groups are grounded.

In the ink ejecting apparatus, for example, when the ink liquid chamber 12b is selected in accordance with desired print data, P
A positive drive voltage is rapidly applied to the TC external electrode 9b,
The TC external electrodes 9a and 9c are grounded. As a result, a driving electric field in the direction of arrow 14a acts on the piezoelectric ceramic layer 6a, and a driving electric field in the direction of arrow 14b acts on the piezoelectric ceramic layer 6b. At this time, the driving electric field directions 14a and 1
4b and the polarization direction 4 are orthogonal to each other, so that the side wall 111a
And 111b are rapidly deformed toward the inside of the ink liquid chamber 12b due to the piezoelectric thickness-shear effect. Due to this deformation, the volume of the ink liquid chamber 12b decreases and the ink liquid chamber 12b
Is rapidly increased, a pressure wave is generated, and ink droplets are ejected from a nozzle (not shown) communicating with the ink liquid chamber 12b. When the application of the driving voltage is stopped,
Positions of the side walls 111a and 111b before deformation (see FIG. 1)
, The ink pressure in the ink liquid chamber 12b decreases,
Ink is supplied into the ink liquid chamber 12b from an ink supply port (not shown).

However, the above operation is only a basic operation of the present embodiment, and when embodied as a product, a driving voltage is first applied in a direction of increasing the volume, and the ink
After the ink is supplied to b, the application of the drive voltage may be stopped to return to the original state (see FIG. 1) and the ink may be ejected.

As described above, in the ink jetting apparatus of the present embodiment, the first and second CTR internal electrode layers 7 and 8 serving as polarization electrodes and the driving electrodes are provided on the piezoelectric ceramic layer 6 on the side wall 111. A PTC external electrode 9 is formed. The first CTR internal electrode layer 7 and the second CTR internal electrode layer 8 are conductors at a temperature equal to or higher than T1 (70 ° C.) and are insulators at a temperature lower than T1. The PTC external electrode 9 is an insulator at a temperature of T2 (130 ° C.) or higher,
Less than 2 is a conductor. That is, at room temperature, the first CTR internal electrode layer 7 and the second CTR internal electrode layer 8 are insulators, and the PTC external electrode 9 is a conductor. The ink is ejected by being deformed by the piezoelectric thickness-shear effect of the layer 6.

When the temperature is equal to or higher than T2 (130 ° C.), the first CTR internal electrode layer 7 and the second CTR internal electrode layer 8 are conductors, the PTC external electrode 9 is an insulator, and the first CTR internal electrode layer 7 In addition, the piezoelectric ceramic layer 6 can be polarized by applying a voltage to the second CTR internal electrode layer 8. Thus, the piezoelectric ceramic layer 6
Since the polarization of the PTC can be performed at any time, the formation of the PTC external electrode 9 and the
In various manufacturing steps such as bonding of the piezoelectric ceramic layer 6 to the cover plate 2, the heat treatment can be performed at a temperature higher than the Curie temperature of the piezoelectric ceramic layer 6 (temperature at which piezoelectric characteristics are lost). As a result, the adhesion strength of the PTC external electrode 9 to the side wall 111 and the bonding strength between each component and the actuator ceramic plate 5 and the like are increased, so that the joint portion is not damaged during driving and the PTC external electrode 9 is prevented from peeling. Is done.

Conventionally, metal electrode 13 (FIG. 16)
Since the electrode 13 comes into contact with the ink inside the ink liquid chamber 12, the electrode 13 is corroded by moisture or the like contained in the ink, so that the durability of the electrode 13 is reduced. In this embodiment, since the electrode material is a ceramic thermistor material which is hardly corroded, corrosion by ink does not occur at all without special protection.

Further, by using the ink jetting device for a long time,
When the piezoelectric characteristics of the piezoelectric ceramic layer 6 are deteriorated by heat, a driving electric field, or the like, repolarization processing can be performed and the piezoelectric ceramic layer 6 can be used again, which leads to resource saving.

Therefore, a highly reliable ink ejecting apparatus can be realized in which the life of the joints of the components and the electrodes is long.

Next, a second embodiment of the present invention will be described with reference to FIGS. The same members as those in the conventional example and the first embodiment of the present invention are denoted by the same reference numerals, and the description thereof will be omitted.

FIG. 8 is a sectional view of an array used in the ink jetting apparatus according to the second embodiment of the present invention. The actuator ceramic plate 25 has a first CTR internal electrode layer 7, a piezoelectric ceramic layer 6, and a third CTR internal layer. Electrode layer 23
And a plurality of side walls 111 formed by laminating the piezoelectric ceramic layer 10 and the second CTR internal electrode layer 8. Further, a plurality of grooves 15 which are separated by the side wall 111 and open upward in the figure are provided. The PTC external electrode 9 is formed on the surface of the side wall 111.

The piezoelectric ceramic layers 6 and 10 are made of ferroelectric lead zirconate titanate-based ceramics, and are polarized in the directions of arrows 4 and 24, respectively. On the other hand, the first CTR internal electrode layer 7, the second CTR internal electrode layer 8, and the third CTR internal electrode layer 23 are insulators at room temperature, but have a Curie temperature (for example, 250
At a predetermined temperature T1 (for example, 70 ° C.) lower than (° C.) or lower, the electrical resistance sharply decreases, and a vanadium oxide-based negative temperature characteristic thermistor material (CTR thermistor material) becomes a conductor. The PTC external electrode 9 is a conductor at room temperature, but has a predetermined temperature T lower than the temperature at which the ferroelectricity of the lead zirconate titanate-based ceramics is lost, that is, the Curie temperature (for example, 250 ° C.).
It is made of a barium titanate-based positive temperature characteristic thermistor material (PTC thermistor material) which becomes an insulator due to a sudden increase in electric resistance at 2 (for example, 130 ° C.) or more.

Actuator ceramic plate 25
Is manufactured by the following manufacturing method.

First, a lead zirconate titanate-based ceramic material forming the piezoelectric ceramic layers 6 and 10, and vanadium oxide forming the first CTR internal electrode layer 7, the second CTR internal electrode layer 8 and the third CTR internal electrode layer 23. A negative temperature characteristic thermistor material of the system is prepared, and they are formed into sheets each having a predetermined thickness by a doctor blade method or the like, and as shown in FIG. Cut into a shape and fired integrally. At this stage, the spontaneous polarization directions of the piezoelectric ceramic layers 6 and 10 are random and do not have piezoelectric characteristics.

Next, as shown in FIG.
Then, a PTC external electrode 9 is formed on the inner surface of the groove 15 as shown in FIG. Since the PTC external electrode 9 is formed prior to the polarization step of the piezoelectric ceramic layers 6 and 10, even if a heat treatment process at a temperature higher than the Curie temperature (for example, 250 ° C.) of the piezoelectric ceramic layer 6 is performed, there is no problem at all. Strong adhesion between the piezoelectric ceramic layer 6 and the PTC external electrode 9 is possible.

The actuator ceramic plate 25 thus obtained and the cover plate 2 made of a ceramic material or a resin material are connected to a bonding layer made of an epoxy-based adhesive or the like on the side wall 111 as shown in FIG. The groove 15 becomes the ink liquid chamber 12 which is spaced apart from each other in the lateral direction by joining through the intermediary 3. Since the joining of the cover plate 2 is performed before the polarization step of the piezoelectric ceramic layer 6, even if a heat treatment process at a temperature higher than the Curie temperature (for example, 250 ° C.) of the piezoelectric ceramic layers 6, 10, there is no problem at all. Strong bonding between the actuator ceramic plate 25 and the cover plate 2 is possible.

Subsequently, as shown in FIG. 13, the first CTR internal electrode layer 7 and the second CTR internal electrode layer 8 are grounded, a polarization voltage is applied to the third CTR internal electrode layer 23, and a silicon oil (not shown) And so on in insulating oil.
The temperature of the insulating oil (not shown) depends on the first CTR internal electrode layer 7, the second CTR internal electrode layer 8, and the third CTR internal electrode layer 2.
3 is higher than the temperature T1 (70 ° C. in the present embodiment) at which the PTC external electrode 9 becomes an insulator.
(130 ° C. in this embodiment) and the Curie temperature of the piezoelectric ceramic layers 6 and 10 (2 in this embodiment).
50 ° C.), for example, about 150 ° C.

At this time, the first CTR internal electrode layer 7 and the third CTR
The TR internal electrode layer 23 and the third CTR internal electrode layer 23 become conductors, the PTC external electrodes 9 become insulators, and the piezoelectric ceramic layers 6, 10 have ferroelectricity. Therefore, the first
A voltage is applied between the CTR internal electrode layer 7 and the second CTR internal electrode layer 8, and between the second CTR internal electrode layer 8 and the third CTR internal electrode layer 23, and arrows are applied to the piezoelectric ceramic layers 6 and 10, respectively. It is well polarized in the directions of 4, 24. At this time, the electric field applied to the piezoelectric ceramic layers 6 and 10 is, for example, about 2 kV / mm.

The normal operating temperature of the actuator ceramic plate 25 is determined by the first CTR internal electrode layer 7 and the second
The temperature T1 (70 ° C. in this embodiment) at which the CTR internal electrode layer 8 and the third CTR internal electrode layer 23 become conductors, and PT
The temperature T2 at which the C external electrode 9 becomes an insulator (1 in this embodiment).
30 ° C.), the PTC external electrode 9 becomes a conductor and functions as a driving electrode, and the first CTR internal electrode layer 7, the second CTR internal electrode layer 8, and the third CTR internal electrode layer 2
3 is an insulator and functions only as a constituent material of the side wall 111.

In the conventional example (FIG. 14), this polarization step had to be performed before the formation of the electrode 13. However, in this embodiment, it may be performed at any time, for example, even after use as an ink ejecting apparatus. Therefore, when the piezoelectric characteristics of the piezoelectric ceramic layers 6 and 10 are deteriorated due to heat, a driving electric field, or the like, repolarization can be performed and the piezoelectric ceramic layers 6 and 10 can be used again.

The array used in the ink ejecting apparatus according to the second embodiment of the present invention is provided with an electric circuit shown in FIG. 9, and all the ink liquid chambers 12 are filled with ink. . In this electric circuit, the PTC external electrodes 9a to 9c formed in the respective grooves 15 are individually L
The clock line 52, the data line 53, the voltage line 54, and the ground line 55 are also connected to the LSI chip 51. The ink liquid chambers 12 are divided into a plurality of groups that are not adjacent to each other, and the LSI chip 51 continuously drives the plurality of groups by a continuous clock pulse supplied from the clock line 52. The LSI chip 51 determines which of the ink chambers 12 of each group should be activated by the multi-bit word format data appearing on the data line 53, and the PTC external electrode of the ink chamber 12 of the selected group is determined. The voltage V of the voltage line 54 is applied to 9.

The side walls 111 on both sides of the selected ink liquid chamber 12 are deformed by the piezoelectric effect of the piezoelectric ceramic layers 6 and 10, so that all the ink liquid chambers 1 in each group are formed.
2 becomes operational. At this time, the PTC external electrodes 9 of the ink liquid chambers 12 of the same group that are not operated and the PTC external electrodes 9 of all the ink liquid chambers 12 belonging to other groups are grounded.

In the ink ejecting apparatus, for example, when the ink liquid chamber 12b is selected in accordance with desired print data, P
A positive drive voltage is rapidly applied to the TC external electrode 9b,
The TC external electrodes 9a and 9c are grounded. Thus, a driving electric field in the direction of arrow 14a is applied to the piezoelectric ceramic layer 6a, a driving electric field in the direction of arrow 14b is applied to the piezoelectric ceramic layer 6b, and a driving electric field in the direction of arrow 14c is applied to the piezoelectric ceramic layer 10a. A driving electric field in the direction of arrow 14d acts on 10b. At this time, since the driving electric field directions 14a and 14b are perpendicular to the polarization direction 4 and the driving electric field directions 14c and 14d are perpendicular to the polarization direction 24, the side walls 111a and 111b are in the inner direction of the ink liquid chamber 12b due to the piezoelectric thickness-shear effect. Deforms rapidly. Due to this deformation, the volume of the ink liquid chamber 12b decreases, the ink pressure in the ink liquid chamber 12b rapidly increases, a pressure wave is generated, and ink droplets are ejected from a nozzle (not shown) communicating with the ink liquid chamber 12b. You.

When the application of the driving voltage is stopped, the side walls 111a and 111b return to the positions before the deformation (see FIG. 1), so that the ink pressure in the ink liquid chamber 12b decreases, and the ink liquid is supplied from an ink supply port (not shown). The ink is supplied into the chamber 12b.

However, the above operation is only a basic operation of the present embodiment, and when embodied as a product, first, a drive voltage is applied in a direction of increasing the volume, and the ink liquid chamber 12 is first applied.
After the ink is supplied to b, the application of the driving voltage may be stopped to return to the original state (see FIG. 8), and the ink may be ejected.

As described above, the same effects as those of the first embodiment can be obtained in the ink jetting apparatus of the present embodiment. Further, in the first embodiment (FIG. 1), one piezoelectric active portion (piezoelectric ceramic layer 6) is provided for one side wall 111, whereas in this embodiment, the piezoelectric active portion (piezoelectric ceramic layer 6) is provided for one side wall 111. Since the active portions (piezoelectric ceramic layers 6 and 10) are located at two locations above and below, the drive voltage required for ink ejection can be reduced to about half, leading to a reduction in the cost of a drive power supply and the like.

Accordingly, it is possible to realize an ink ejecting apparatus which has a long life of the joints of the parts and the electrodes, high reliability, and low production cost.

Further, a plurality of piezoelectric ceramic layers may be provided.

In this embodiment, the temperature T1 (70 ° C.) at which the polarization electrode changes from an insulator to a conductor and the temperature T2 (130 ° C.) at which the drive electrode changes from a conductor to an insulator are different. However, the temperature may be the same.

In this embodiment, the temperature T1 (70 ° C.)
Was lower than the temperature T2 (130 ° C.), but the temperature T2 may be lower than the temperature T1.

Further, in this embodiment, the polarization electrode C
The TR internal electrode layer forms the side wall 111, and the side wall 111
Although the PTC external electrode 9 serving as a driving electrode is formed on the side surface of the CTR, the arrangement of the CTR internal electrode layer and the PTC external electrode may be replaced. However, in this case, the polarization direction of the piezoelectric ceramic layer is changed by 90 degrees.

[0059]

As is apparent from the above description, according to the present invention, the polarization electrode becomes an electric conductor whose electric resistance decreases at a temperature equal to or higher than a predetermined temperature T1, and increases at a temperature lower than the predetermined temperature T1. The driving electrode is made of a material that becomes an insulator by increasing the electric resistance at a predetermined temperature T2 or higher and becomes an insulator, and that becomes a conductor at a lower temperature than the predetermined temperature T2. It is configured. Therefore, at room temperature, the polarization electrode becomes an insulator and the drive electrode becomes a conductor, whereas at a temperature equal to or higher than the predetermined temperature T1, T2, the polarization electrode becomes a conductor and the drive electrode becomes insulated. Be a body. As a result, if the temperature is equal to or higher than the predetermined temperatures T1 and T2 even after the driving electrodes are formed, the polarization of the piezoelectric ceramics can be performed. In the manufacturing process, heat treatment can be performed at a temperature higher than the Curie temperature of the piezoelectric material (temperature at which the piezoelectric characteristics are lost). As a result, the adhesion strength of the electrodes and the bonding strength between each part and the piezoelectric ceramic plate etc. increase,
The joint is prevented from being damaged or the electrode is peeled during driving. Therefore, it is possible to provide a highly reliable ink ejecting apparatus in which the lives of the joints of the components and the electrodes are long.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an ink ejecting apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram illustrating an operation of the ink ejecting apparatus according to the embodiment of the present invention.

FIG. 3 is a perspective view showing a manufacturing process of the actuator ceramic plate according to one embodiment of the present invention.

FIG. 4 is a sectional view showing a manufacturing process of the actuator ceramic plate according to one embodiment of the present invention.

FIG. 5 is a sectional view showing a manufacturing process of the actuator ceramic plate according to one embodiment of the present invention.

FIG. 6 is an explanatory diagram showing temperature characteristics of electric resistance of a thermistor material according to one example of the present invention.

FIG. 7 is a sectional view showing a polarization step of the actuator ceramic plate according to one embodiment of the present invention.

FIG. 8 is a cross-sectional view illustrating an ink ejecting apparatus according to a modified example of the invention.

FIG. 9 is an explanatory diagram illustrating an operation of an ink ejection device according to a modified example of the invention.

FIG. 10 is a perspective view illustrating a manufacturing process of an actuator ceramic plate according to a modification of the present invention.

FIG. 11 is a sectional view showing a manufacturing process of an actuator ceramic plate according to a modified example of the present invention.

FIG. 12 is a sectional view showing a manufacturing process of an actuator ceramic plate according to a modification of the present invention.

FIG. 13 is a perspective view showing a polarization step of an actuator ceramic plate according to a modification of the present invention.

FIG. 14 is a cross-sectional view illustrating a conventional ink ejecting apparatus.

FIG. 15 is an explanatory diagram showing an operation of a conventional ink ejecting apparatus.

FIG. 16 is a perspective view showing a conventional ink ejecting apparatus.

FIG. 17 is a block diagram showing a control unit of a conventional example.

FIG. 18 is a perspective view showing a conventional printer.

[Explanation of symbols]

 4 Polarization direction 6 Piezoelectric ceramic layer 7 First CTR internal electrode layer 8 Second CTR internal electrode layer 9 PTC external electrode 12 Ink liquid chamber 14a Electric field direction 14b Electric field direction 14c Electric field direction 14d Electric field direction 23 Third CTR internal electrode layer 24 Polarization direction 111 Side wall

Claims (3)

(57) [Claims] 1. An ink liquid chamber filled with ink, a side wall composed of at least a part of a piezoelectric portion that separates the ink liquid chamber, and an electric field substantially perpendicular to the polarization direction. A pair of drive electrodes formed on the piezoelectric portion, and the side wall is deformed by a piezoelectric thickness-shear effect of the piezoelectric portion by applying a voltage to the drive electrode, so that the ink in the ink liquid chamber is An ink ejecting apparatus that ejects ink by applying pressure to the piezoelectric device, further comprising a pair of polarizing electrodes formed on the piezoelectric portion so as to generate an electric field parallel to the polarizing direction, An electric resistance is reduced at a predetermined temperature T1 or higher to become a conductor, and an electric resistance is increased at a temperature lower than the predetermined temperature T1 to be an insulator. The driving electrode is configured to have an electric resistance at a predetermined temperature T2 or higher. Increased insulation An ink ejecting apparatus comprising: a material that becomes a body and has a lower electrical resistance at a temperature lower than the predetermined temperature T2 and becomes a conductor. 2. The ink ejecting apparatus according to claim 1, wherein the predetermined temperatures T1 and T2 are lower than a temperature at which the piezoelectric portion loses piezoelectric characteristics. 3. The device according to claim 1, wherein the polarization electrode is made of a vanadium oxide-based negative temperature characteristic thermistor material, and the driving electrode is made of a barium titanate-based positive temperature characteristic thermistor material. 2. The ink ejection device according to 1.