JPH10157109A - Ink jet head and method for forming it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet head of such type as an ink pressure chamber is provided on the piezoelectric element side in which no significant warp or waving takes place even when a laminate of piezoelectric elements is fired. SOLUTION: A cavity plate 6 comprises a laminate of six sheet-like piezoelectric elements 6a-6f where a common electrode 14 is provided on the upper surface of the sheet-like piezoelectric element 6a in the uppermost layer and an independent electrode 16 is provided at the common part on the lower surface of each sheet-like piezoelectric element 6a-6f. The part of independent electrode 16 of each sheet-like piezoelectric element 6a-6f is then trenched up to the second sheet-like piezoelectric element 6b from below thus forming an ink pressure chamber 4. A sheet-like cover member 10 is bonded to the cavity plate 6 on the opening side of the ink pressure chamber 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet head, and more particularly, to a cavity plate composed of a piezoelectric element in which an ink pressure chamber and electrodes corresponding to the ink pressure chamber are formed, and an opening of the ink pressure chamber. And a nozzle communicating with the ink pressure chamber, and applying a drive voltage to the electrode to deform the cavity plate, thereby generating pressure vibration in the ink pressure chamber, and The present invention relates to an inkjet head that ejects ink.

[0002]

2. Description of the Related Art In a conventional ink jet head 150, as shown in FIG. 9, a cavity plate 154 provided with an ink pressure chamber 152, a piezoelectric element 160 provided with an external electrode 156 and an internal electrode 158 and laminated and fired are provided. Was pasted. The piezoelectric element 160 serves as a lid of the ink pressure chamber 152 of the cavity plate 154.
2, a pressure wave is generated, and the ink droplets are
Was discharged from a nozzle communicating with the nozzle.

In such an ink jet head 150, a plurality of ink pressure chambers 152 are usually provided, and ink is ejected from nozzles connected to each of the ink pressure chambers 152. In terms of print quality, the ejection performance is uniform. It is important that However, the ink pressure chamber 152
The piezoelectric element 160 is provided in the cavity plate 154,
The ink pressure chamber 152 is closed by being joined to each end surface of the side wall 153 that partitions the ink pressure chamber 152. Thus, the cavity plate 1 forming the ink pressure chamber 152
The piezoelectric element 160 and the piezoelectric element 160 are originally separated from each other. Therefore, the bonding state greatly affects the deformation characteristics of the piezoelectric element 160, and the uniformity of the accuracy of the bonded portion affects the uniformity of the ejection performance of each nozzle.

[0004] In order to make the accuracy of each joint portion uniform, high flatness is required between each end face of the side wall 153 and the piezoelectric element 160 side. Furthermore, in the joining process using an adhesive or the like, it is required that uniform joining be performed at each joining portion. However, it is difficult to achieve high flatness and uniform bonding at all bonding portions, and slight flatness or uneven bonding may cause deformation of the piezoelectric element 160 supported on the tip end surface of the side wall 153. Change the characteristics slightly,
It has been difficult to provide uniform ejection performance to all nozzles.

To solve this problem, an ink jet head 200 having the following configuration has been proposed. This is, as shown in FIG.
08 is printed on each of the sheet-like piezoelectric elements 210.
a and 210b are laminated and fired, and then the lower piezoelectric element 2
By subjecting the groove 10b to groove processing, the ink pressure chamber 202 is formed.
Then, the ink pressure chamber 202 is covered with the flat plate 204.

In this configuration, the sheet-like piezoelectric element 210
a is laminated on the outer surface on the opposite side of the lower piezoelectric element 210b, not on the side where the ink pressure chamber 202 is open. This lamination is performed, for example, by bonding an adhesive to the lower piezoelectric element 210b in which the ink pressure chamber 202 is formed, or by applying a vacuum to the unsintered sheet-shaped piezoelectric element 210a and the unsintered lower piezoelectric element 210b. This is achieved by a method such as forming the ink pressure chamber by bringing it into close contact with a press or the like, followed by baking.

Accordingly, since the sheet-like piezoelectric element 210a is not joined to the lower piezoelectric element 210b on the side where the ink pressure chamber 202 is open, it is joined to the front end surface of the side wall 203 that partitions the ink pressure chamber 202. It will be laminated on the opposite outer surface consisting of one surface. As described above, the sheet-like piezoelectric element 210a and the lower piezoelectric element 210b need only achieve uniformity in flatness and bonding on one surface, and uniform lamination can be easily performed on all pressure chambers. As a result, uniform ejection performance was obtained for all nozzles.

[0008]

However, in this method, the thickness of one lower piezoelectric element 210b must be increased by the depth of the ink pressure chamber 202 provided by groove processing. However, in firing such piezoelectric elements having different thicknesses integrally, deformation such as warpage or undulation is inevitable. In the conventional ink jet head 150 shown in FIG. 9, since the thickness is the same, deformation such as warpage and undulation is unlikely to occur, and even if slight, grinding is performed on both the upper and lower surfaces of the piezoelectric element 160 after firing. Flatness can be obtained.

However, as shown in FIG.
The piezoelectric element constituting the upper sheet-like piezoelectric element 2
Since the thickness of the lower piezoelectric element 210a is different from that of the lower piezoelectric element 210b, large warpage and undulation are likely to occur, and it may not be possible to use the inkjet head as an ink-jet head.

An object of the present invention is to provide an ink jet head in which an ink pressure chamber is provided on the side of a piezoelectric element and in which a large warpage or undulation hardly occurs even when a laminate of piezoelectric elements is fired, and a method of forming the same. Things.

[0011]

Means for Solving the Problems and Effects of the Invention Here, one or more inventions are described, each having the structure and effect described below. An ink jet head according to the present invention includes a cavity plate formed of a piezoelectric element in which an ink pressure chamber and an electrode corresponding to the ink pressure chamber are formed, and a plate-like body attached so as to cover an opening of the ink pressure chamber. And a nozzle communicating with the ink pressure chamber, and applying a drive voltage to the electrode to deform the cavity plate, thereby causing pressure oscillation in the ink pressure chamber to eject ink from the nozzle. In the ink jet head, the cavity plate arranges a plurality of sheet-shaped piezoelectric elements such that an arrangement of the thickness of the sheet-shaped piezoelectric elements is symmetric in a thickness direction, and an electrode is provided between the sheet-shaped piezoelectric elements. The ink pressure chamber is provided in a stacked arrangement.

As described above, by using the cavity plate configured so that the thickness relationship of the laminated sheet-shaped piezoelectric elements is symmetric in the thickness direction, the laminated body of the sheet-shaped piezoelectric elements is fired. Even a big sled,
There is no swell. That is, since the amount of shrinkage of the ceramic sheet generated during firing varies depending on the thickness, in a set of two ceramic sheets having different thicknesses, warpage and undulation are unavoidable, but two sheets symmetrical in the thickness direction are inevitable. In the ceramic sheets of the set, the amount of shrinkage generated in the two ceramic sheets of each set during firing is substantially the same, so that the warpage, undulation, etc. are offset in each set, and the warped cavity plate is not warped. Swells and the like hardly appear.

Therefore, there is no occurrence of a warp or swell that cannot be used in the ink jet head.
If the flatness is obtained, the ink jet head can be sufficiently used. In addition, since the electrode is usually thinner than the piezoelectric element, even if the symmetry of the thickness of the electrode is not considered, a large undulation does not occur, but in order to further reduce the undulation, A cavity plate in which a plurality of sheet-shaped piezoelectric elements and electrodes are arranged and stacked so that the thickness arrangement of the sheet-shaped piezoelectric elements and the electrodes is symmetric in the thickness direction, and ink pressure chambers are provided. It is good.

As a method of forming such an ink-jet head, for example, at least one of a plurality of unsintered sheet-shaped piezoelectric elements provided with electrodes on one surface is formed by symmetrically setting the thickness of the sheet-shaped piezoelectric elements in the thickness direction. After arranging and laminating so that the electrodes are inside, firing is performed to form a plate, and the plate is subjected to groove processing to provide the ink pressure chamber to form the cavity plate. The forming method may include a step of covering the opening of the ink pressure chamber of the cavity plate with the plate.

Examples of the groove processing include shot blast processing. The groove processing, for the position of the plate, the electrode is laminated inside,
By performing so as to leave at least one of the electrodes, a piezoelectric element can be sandwiched between an externally provided electrode and a driving voltage applied between the external electrode and the internal electrode. By deforming the piezoelectric element, the ink in the ink pressure chamber can be discharged from the nozzle. In addition, a polarization process can be performed on the piezoelectric element using the electrode.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION

[Embodiment 1] FIGS. 1A and 2 show a configuration of an ink jet head 2 to which some of the above-described inventions are applied. FIG. 2 is a longitudinal section cut along the axial direction of an ink pressure chamber 4. FIG. FIG. 1A is a longitudinal sectional explanatory view showing a part of a plane cut at a right angle (XX) to the axial direction of the ink pressure chamber 4 in an enlarged manner.

The ink pressure chamber 4 has a cavity plate 6
Is formed in a groove shape on one side by a side wall 7. The side of the cavity plate 6 where the ink pressure chamber 4 is open is covered with a sheet-like cover member 10 joined to the front end face 8 of the side wall 7.

The cavity plate 6 is formed by laminating six sheet-like piezoelectric elements 6a, 6b, 6c, 6d, 6e, 6f. Uppermost sheet-shaped piezoelectric element 6a
The common electrode 14 is provided on almost the entire surface of the substrate. The common electrode 14 is commonly used as a negative electrode corresponding to all the ink pressure chambers 4 formed in the cavity plate 6.

At the interface between the uppermost sheet-shaped piezoelectric element 6a and the sheet-shaped piezoelectric element 6b therebelow, independent positive electrodes 16 are formed corresponding to the individual ink pressure chambers 4, respectively. ing. The uppermost sheet-shaped piezoelectric element 6a is polarized in the thickness direction of the sheet-shaped piezoelectric element 6a toward the side opposite to the ink pressure chamber 4, as indicated by the arrow in the figure. Therefore, the common electrode 14 and the independent electrode 1
6, a portion 18 sandwiched between the common electrode 14 and the independent electrode 16 to which the drive voltage has been applied, of the uppermost sheet-like piezoelectric element 6a, is formed as shown in FIG.
The direction of the arrow F shown in FIG.
It contracts in the in-plane direction of a.

When a part of the uppermost sheet-like piezoelectric element 6a located at the center of the ink pressure chamber 4 contracts as described above,
Since the sheet-like piezoelectric element 6b laminated below the uppermost sheet-like piezoelectric element 6a does not shrink, the lower sheet-like piezoelectric element 6b side is a convex side, and the uppermost sheet-like piezoelectric element 6a side is a concave side. As shown in FIG. 1B, the ink pressure chamber 4
Is projected toward the inside of the ink pressure chamber 4.
As a result, the volume of the ink pressure chamber 4 decreases, the pressure of the ink increases, and the ink is ejected from the nozzle 22 to the outside.

Subsequently, when the application of the drive voltage between the common electrode 14 and the independent electrode 16 is stopped, the state returns to the state of FIG. 1A from the state of FIG. Returning, the pressure of the ink in the ink pressure chamber 4 decreases, and the ink is sucked from the ink chamber 20 into the ink pressure chamber 4.

The assembly of the ink jet head 2 is as follows.
The following steps are performed. First, as shown in FIG. 3A, six unfired PZT (lead zirconate titanate) ceramic sheets 24a having the same thickness and having a conductive paste printed on the pattern 25 of the independent electrode 16 on one surface side, 2
4b, 24c, 24d, 24e, and 24f are prepared, and vacuum pressing is performed in a state where the ceramic sheets 24a to 24f are stacked, so that the six unfired PZT-based ceramic sheets 24a to 24f are adhered to each other.

This is fired to form a cavity plate 6 as shown in FIG. Then, a groove processing for cutting a portion indicated by a two-dot chain line is performed. This groove processing,
This is performed by shot blasting. The shot blast processing is performed, for example, as follows.

That is, a resist mask is formed on the front end face 8 of a portion to be left as the side wall 7, and the ink pressure chamber 4 is formed in a groove shape by shot blasting with ceramic powder, and the resist mask on the front end face 8 of the side wall 7 is formed. Is carried out. In addition, the groove removes all the independent electrodes 16 from the lowermost sheet-shaped piezoelectric element 6f to the second sheet-shaped piezoelectric element 6b, and removes the second sheet-shaped piezoelectric element 6b.
Is made to leave partially. This allows
The independent electrodes 16 are only those sandwiched between the uppermost sheet-shaped piezoelectric element 6a and the second sheet-shaped piezoelectric element 6b.

Then, the upper surface of the uppermost sheet-like piezoelectric element 6a and the front end face 8 of the side wall 7 are polished to obtain a flatness and finished. As shown in FIG. The common electrode 14 is printed on the upper surface of 6a. Next, the sheet-shaped cover member 10 is bonded to the tip end surface 8 of the side wall 7 with an adhesive to form the ink jet head 2 as shown in FIG.

In the first embodiment, six unfired PZT ceramic sheets 24a to 24f formed in exactly the same shape are laminated and fired. That is, the cavity plate 6 includes six sheet-shaped piezoelectric elements 6a to 6a.
6f are arranged such that the arrangement of the thicknesses of the sheet-shaped piezoelectric elements 6a to 6f is symmetric in the thickness direction (vertically symmetric with respect to the interface between the sheet-shaped piezoelectric element 6c and the sheet-shaped piezoelectric element 6d). Independent electrodes 16 between the piezoelectric elements 6a to 6f
Are arranged and laminated, and an ink pressure chamber 4 is further provided.

Since the thicknesses of the sheet-like piezoelectric elements 6a to 6f are all the same, all the ceramic sheets 24a to 24f shrink to the same degree during firing. Therefore, warpage, undulation, and the like hardly appear in the fired cavity plate 6.

As described above, according to the inkjet head 2 of the first embodiment, warpage and undulation can be sufficiently suppressed, and the production yield of the inkjet head 2 can be sufficiently increased. In the ink jet head 2 of the first embodiment, the uppermost sheet-like piezoelectric element 6a that is deformed by the driving voltage as the piezoelectric element is integrally fired with the cavity plate 6, so that the bonding surface using an adhesive or the like is used. Does not exist, and non-uniformity of the flatness of the bonding surface and the bonding state does not occur, and uniform discharge performance can be obtained in all the nozzles 22.

Furthermore, the uppermost sheet-like piezoelectric element 6a is
Since it is a single sheet corresponding to all of the ink pressure chambers 4, the uniformity of performance can be further improved, and more uniform ejection performance can be obtained in all the nozzles 22. Although the lower surface of the cavity plate 6 in which the ink pressure chamber 4 is opened is covered by the sheet-shaped cover member 10, even if the flatness and the joint of the joining surface by the sheet-shaped cover member 10 are slightly uneven, On the cover member 10 side, no deformation that changes the volume of the ink pressure chamber 4 is performed, so that there is no adverse effect on the ejection performance.

Further, since all the sheet-shaped piezoelectric elements 6a to 6f constituting the cavity plate 6 are made of the same material, the affinity of all the sheet-shaped piezoelectric elements 6a to 6f is high, and the uppermost sheet-shaped piezoelectric element 6a to 6f is used. Even with a configuration in which only the element 6a is deformed, the inkjet head 2 with extremely high durability can be formed.

Also, since the polarization process can be performed using the common electrode 14 and the independent electrode 16 as they are, there is no need to use a special polarization device, the efficiency is high, and the manufacturing cost is low. Note that the first embodiment is a so-called unimorph type in which the direction of the electric field generated by the drive voltage matches the polarization direction of the piezoelectric element, and the direction of the electric field of the drive voltage and the polarization direction of the piezoelectric element are different from each other. Are not in the orthogonal share mode, so, in particular,
There is no need to print on the sheet-shaped piezoelectric elements 6a to 6f, which is preferable in terms of accuracy and manufacturing efficiency.

Since the ink pressure chamber 4 is formed in the cavity plate 6 by shot blasting,
The ink pressure chamber 4 can be formed easily and without causing distortion in the cavity plate 6, and more uniform ejection performance can be obtained. [Embodiment 2] FIG.
Of the inkjet head 32 of FIG. FIG. 4 is a diagram corresponding to FIG. 1B of the first embodiment.

The difference from the first embodiment is that the same sheet-like piezoelectric elements 36a, 36b, 36c, 36d, 36e, 3
The auxiliary electrode 47 is also provided at a position between the independent electrodes 46 in 6f.
Is provided. Ink pressure chamber 34, sheet-shaped cover member 40, common electrode 44, and independent electrode 46
Are formed in the same manner as in the first embodiment.

The uppermost sheet-shaped piezoelectric element 36a of the cavity plate 36 is polarized in the thickness direction of the sheet-shaped piezoelectric element 36a toward the side opposite to the ink pressure chamber 34, as indicated by the arrow in the drawing. Therefore, by applying a drive voltage between the common electrode 44 and the independent electrode 46, the topmost sheet-like piezoelectric element 36a is sandwiched between the common electrode 44 and the independent electrode 46 to which the drive voltage is applied. The contracted portion 48 contracts in the in-plane direction of the sheet-like piezoelectric element 36a as in the first embodiment. When the portion 48 contracts in this manner, the uppermost sheet-like piezoelectric element 3
Since the sheet-like piezoelectric element 36b stacked below 6a does not shrink, the lower sheet-like piezoelectric element 36b side is a convex side and the uppermost sheet-like piezoelectric element 36a side is a concave side, as shown in FIG. The vicinity of the center of the ink pressure chamber 34 protrudes toward the inside of the ink pressure chamber 34.

Further, the second driving electrode is provided between the two auxiliary electrodes 47 on both sides of the independent electrode 46 such that an electric field is generated from the independent electrode 46 toward the auxiliary electrode 47 between the two auxiliary electrodes 47. Apply voltage. As a result, the shear mode is deformed on both sides of the portion 48, and acts to move the portion 48 further to the ink pressure chamber 34 side.

As a result, the volume of the ink pressure chamber 34 is greatly reduced as compared with the first embodiment, the pressure of the ink is increased, and a larger amount of ink is ejected from the nozzles to the outside. Subsequently, the common electrode 44 and the independent electrode 4
When the application of the driving voltage between the independent electrodes 46 and the two auxiliary electrodes 47 on both sides is stopped, the sheet-like piezoelectric elements 36a and 36b are moved from the state shown in FIG. Returning to the state, the volume of the ink pressure chamber 34 returns to the original state, the pressure of the ink in the ink pressure chamber 34 decreases,
The ink is sucked into the ink pressure chamber 34 from the ink chamber.

The assembly of the ink jet head 32 is performed in the following steps. First, as shown in FIG. 5 (a), six unfired pieces of the same shape in which a conductive paste is printed on the pattern 56 of the independent electrode 46 and a conductive paste is further printed on the pattern 57 of the auxiliary electrode 47 on one surface side. PZ
T (lead zirconate titanate) ceramic sheet 54
a, 54b, 54c, 54d, 54e, and 54f are prepared, and vacuum pressing is performed in a state where the ceramic sheets 54a to 54f are stacked, so that the six unfired PZT-based ceramic sheets 54a to 54f are adhered to each other.

This is fired to form a cavity plate 36 as shown in FIG. Then, a groove processing for cutting a portion indicated by a two-dot chain line is performed. This groove processing is performed by the same shot blast processing as in the first embodiment. The groove is formed in the lowermost sheet-like piezoelectric element 36f.
Independent electrodes 4 from the second to the second sheet-like piezoelectric element 36b
6, and the second sheet-like piezoelectric element 36b is partially left. Thus, the independent electrode 46 is only the one sandwiched between the uppermost sheet-shaped piezoelectric element 36a and the second sheet-shaped piezoelectric element 36b.
However, the auxiliary electrode 47 remains on the side wall 37.

Then, the uppermost sheet-like piezoelectric element 36a
Is polished to obtain a flatness, and the auxiliary electrode 47 on the tip end surface 38 of the side wall 37 is polished and removed, and the flatness is obtained and finished. As shown in FIG. A common electrode 44 is printed on the upper surface of the piezoelectric element 36a.

Next, the sheet-like cover member 40 is joined to the tip end surface 38 of the side wall 37 with an adhesive to form the ink jet head 32 as shown in FIG. In the second embodiment, since six unsintered PZT-based ceramic sheets 54a to 54f formed in exactly the same shape are stacked and fired, the same effect as in the first embodiment is obtained. The cavity plate 36 has a sled,
Swells and the like hardly appear. Therefore, according to the inkjet head 32 of the second embodiment, warpage, undulation, and the like can be sufficiently suppressed, and the production yield of the inkjet head 32 can be sufficiently increased.

Since the polarization process can be performed using the common electrode 44 and the independent electrode 46 as they are, there is no need to use a special polarization device, and the process is efficient and the production cost can be reduced. In the second embodiment, the unimorph type in which the direction of the electric field generated by the drive voltage matches the polarization direction of the piezoelectric element, and the direction of the electric field generated by the drive voltage and the polarization direction of the piezoelectric element are orthogonal to each other. Because of the combination with the shared mode type, a larger deformation amount can be obtained, and the ink ejection amount can be increased.

Incidentally, the number of sheet-like piezoelectric elements (ceramic sheets) may be an odd number. [Embodiment 3] FIG.
A part of the inkjet head 62 of FIG. FIG. 6 is a diagram corresponding to FIG. 4 of the second embodiment.

The difference from the second embodiment is that an independent electrode 76 and an auxiliary electrode 77 which are the same as the independent electrode 76 and the auxiliary electrode 77 provided on the lower surface of each of the sheet-shaped piezoelectric elements 66a to 66f are provided instead of the common electrode. It is a point that is.
Other independent electrode 76, other auxiliary electrode 77, ink pressure chamber 6
4 and the sheet-shaped cover member 70 are formed in the same manner as in the second embodiment.

The uppermost sheet-shaped piezoelectric element 66a of the cavity plate 66 is polarized in the thickness direction of the sheet-shaped piezoelectric element 66a toward the side opposite to the ink pressure chamber 64, as indicated by the arrow in the figure. For this reason, two independent electrodes 76 provided on the upper and lower surfaces of the uppermost sheet-shaped piezoelectric element 66a, and four independent electrodes 76 on both sides of the independent electrode 76 are provided.
By applying a drive voltage between the two auxiliary electrodes 77, portions 78 a, both sides of which are sandwiched between the independent electrode 76 to which the drive voltage is applied and the auxiliary electrode 77, of the uppermost sheet-shaped piezoelectric element 66 a 78b causes a deformation of the share mode.

For this reason, as shown in FIG. 6, the center of the ink pressure chamber 64 is located near the center of the ink pressure chamber 64, with the lower sheet-shaped piezoelectric element 66b side being the convex side and the uppermost sheet-shaped piezoelectric element 66a side being the concave side. Protruding toward the inside. As a result, the volume of the ink pressure chamber 64 is greatly reduced, the pressure of the ink is further increased, and a larger amount of ink is ejected from the nozzles to the outside.

Subsequently, when the application of the driving voltage between the independent electrode 76 and the auxiliary electrode 77 is stopped, the sheet-like piezoelectric element 66
a and 66b return from the state of FIG. 6 to the flat state, the volume of the ink pressure chamber 64 returns to its original state, the pressure of the ink in the ink pressure chamber 64 decreases, and the ink is moved from the ink chamber into the ink pressure chamber 64. Suction.

The assembly of the ink jet head 62 is performed in the following steps. First, as shown in FIG. 7 (a), the same five unbaked PZTs in which the conductive paste is printed on the pattern 86 of the independent electrode 76 and the conductive paste is printed on the pattern 87 of the auxiliary electrode 77 are formed on one surface side.
(Lead zirconate titanate) ceramic sheet 84
b, 84c, 84d, 84e, 84f and one unfired PZT (lead zirconate titanate) -based ceramic sheet 84a which is different from the other ceramic sheets 84b to 84f in that the patterns 86, 87 are printed on both sides. Is prepared, and vacuum pressing is performed in a state where the ceramic sheets 84a to 84f are overlapped, so that the six unfired PZT-based ceramic sheets 84a to 84f are adhered to each other.

This is fired to form a cavity plate 66 as shown in FIG. Then, a groove processing for cutting a portion indicated by a two-dot chain line is performed. This groove processing is performed by the same shot blast processing as in the first embodiment. The groove is formed in the lowermost sheet-like piezoelectric element 66f.
Independent electrodes 7 from the first sheet-shaped piezoelectric element 66b to the second sheet-shaped piezoelectric element 66b
6, and the second sheet-shaped piezoelectric element 66b is partially left. Thus, only two independent electrodes 76 sandwich the uppermost sheet-shaped piezoelectric element 66a. However, the auxiliary electrode 77 is
Is left in the part.

Then, the auxiliary electrode 77 on the distal end surface 68 of the side wall 67 is polished and removed, and is finished with flatness. Next, the sheet-shaped cover member 70 is bonded to the tip end surface 68 of the side wall 67 with an adhesive, thereby forming the ink jet head 62 as shown in FIG.

In the third embodiment, five ceramic sheets 84b to 84f formed in exactly the same shape are used.
In addition, since the uppermost layer is laminated and fired with one ceramic sheet 84a having different patterns 86 and 87 printed on both sides, the same effect as in the first embodiment is obtained.
Warpage, undulation, etc. hardly appear in the fired cavity plate 66. Therefore, according to the inkjet head 62 of the third embodiment, warpage, undulation, and the like can be sufficiently suppressed, and the production yield of the inkjet head 62 can be sufficiently increased.

Furthermore, since the independent electrode 76 (pattern 86) and the auxiliary electrode 77 (pattern 87) are also arranged symmetrically in the thickness direction, warpage, undulation, etc. do not appear further. Note that an odd number of sheet-shaped piezoelectric elements (ceramic sheets) may be used.

[Others] In the third embodiment, the uppermost sheet-shaped piezoelectric element 6 is driven in the share mode.
For example, as shown in FIG. 8, the same unfired PZT (FIG. 8) in which the conductive paste is printed on the pattern of the independent electrode 106 and the conductive paste is printed on the pattern of the auxiliary electrode 107 only on one surface side. By increasing the number of lead zirconate titanate) -based ceramic sheets, seven sheet-shaped piezoelectric elements 96b to 96h are formed here,
A total of eight cavity plates 96 are formed with the uppermost sheet-shaped piezoelectric element 96a.

Then, the three-layered sheet-like piezoelectric element 9 from the top
6a, 96b, 96c independent electrodes 106 on both sides
By leaving the auxiliary electrode 107, the number of sheets driven in the share mode is set to three. By increasing in this manner, four layers of sheet-like piezoelectric elements 96a, 96
The deformation amounts of b, 96c, and 96d can be increased. Other effects are the same as those of the third embodiment.

In the above embodiments, each of the sheet-like piezoelectric elements 6a to 6f, 36a to 36f, 66a to 66f, 96
a to 96h have the same thickness, but the thicknesses may be arranged so as to be symmetric in the thickness direction. It is sufficient that the sheet-shaped piezoelectric elements described above have the same thickness.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a configuration and an operation of an ink jet head according to a first embodiment. FIG. 1A is an enlarged view of a part of a surface cut at a right angle (XX in FIG. 2) in an axial direction of a pressure chamber. FIG. 4B is a vertical sectional view, and FIG. 4B is an operation explanatory diagram when a driving voltage is applied.

FIG. 2 is a longitudinal sectional view of the ink jet head according to the first embodiment, taken along an axial direction of a pressure chamber.

FIG. 3 is an explanatory diagram of a manufacturing process of the inkjet head according to the first embodiment.

FIG. 4 is an explanatory diagram of a configuration of an inkjet head according to a second embodiment.

FIG. 5 is an explanatory diagram of a manufacturing process of the ink jet head according to the second embodiment.

FIG. 6 is an explanatory diagram of a configuration of an inkjet head according to a third embodiment.

FIG. 7 is an explanatory diagram of a manufacturing process of the inkjet head according to the third embodiment.

FIG. 8 is a diagram illustrating the configuration of another example of an inkjet head.

FIG. 9 is an explanatory diagram of a configuration of an ink jet head as a conventional technique.

FIG. 10 is a diagram illustrating the configuration of an inkjet head as a comparative technique.

[Explanation of symbols]

2 Inkjet head 4 Ink pressure chamber 6 Cavity plate 6a, 6b, 6c, 6d, 6e, 6f Sheet-like piezoelectric element 7 Side wall 8 Tip surface 10 Sheet-like cover member 14 Common electrode 16 Plus Independent electrodes 16 ...
Independent electrode 20 Ink chamber 22 Nozzle 24a, 24b, 24c, 24d, 24e, 24f Unfired PZT-based ceramic sheet 25 Pattern 32 Ink jet head 3
4 ink pressure chamber 36 cavity plate 36a, 36b, 36c, 36d, 36e, 36f sheet-like piezoelectric element 37 side wall 38 tip surface 40 sheet-like cover member 44 common electrode 46 independent electrode 47 auxiliary electrode 54a, 54b, 54c, 54d, 54e, 54f Unfired PZT-based ceramic sheet 56 ... Pattern 57 ... Pattern 62 ... Inkjet head 64 ... Ink pressure chamber 66 ... Cavity plate 66a, 66b, 66c, 66d, 66e, 66f ... Sheet-shaped piezoelectric element 67 ... Side wall 68 ... Tip surface 70 ... Sheet-shaped cover member 76 ... Independent electrode 77 ... Auxiliary electrode 84a, 84b, 84c, 84d, 84e, 84f ... Unfired PZT-based ceramic sheet 86 ... Pattern 87 ... Pattern 96 ... cavity plate 96a, 96b, 96c, 96d, 96e, 96f, 9
6g, 96h: sheet-like piezoelectric element 106: independent electrode 107: auxiliary electrode

Claims (5)

[Claims] A cavity plate comprising a piezoelectric element in which an ink pressure chamber and electrodes corresponding to the ink pressure chamber are formed; a plate-like body attached so as to cover an opening of the ink pressure chamber; A nozzle communicating with the ink pressure chamber, and applying a drive voltage to the electrode to deform the cavity plate, thereby generating pressure vibration in the ink pressure chamber and discharging ink from the nozzle. In the cavity plate, a plurality of sheet-shaped piezoelectric elements are arranged so that the thickness arrangement of the sheet-shaped piezoelectric elements is symmetric in a thickness direction, and electrodes are arranged between the sheet-shaped piezoelectric elements. An ink jet head characterized in that the ink pressure chambers are provided in a stacked structure. 2. A cavity plate comprising a piezoelectric element in which an ink pressure chamber and electrodes corresponding to the ink pressure chamber are formed, a plate-like body attached so as to cover an opening of the ink pressure chamber, A nozzle communicating with the ink pressure chamber, and applying a drive voltage to the electrode to deform the cavity plate, thereby generating pressure vibration in the ink pressure chamber and discharging ink from the nozzle. In the ink, the cavity plate is formed by laminating a plurality of sheet-shaped piezoelectric elements and electrodes such that an arrangement of the thicknesses of the sheet-shaped piezoelectric elements and the electrodes is symmetric in a thickness direction. An ink jet head comprising a pressure chamber. 3. A cavity plate comprising a piezoelectric element in which an ink pressure chamber and an electrode corresponding to the ink pressure chamber are formed, a plate-like body attached so as to cover an opening of the ink pressure chamber, A nozzle communicating with the ink pressure chamber, and applying a drive voltage to the electrode to deform the cavity plate, thereby generating pressure vibration in the ink pressure chamber and discharging ink from the nozzle. Wherein at least one of the plurality of unsintered sheet-shaped piezoelectric elements provided with electrodes on one surface is formed such that the thickness of the sheet-shaped piezoelectric elements is symmetric in the thickness direction, and the electrodes are formed inside and outside. After arranging and laminating, a plate is formed by baking, and the plate is subjected to groove processing to provide the ink pressure chamber, thereby forming the cavity. Forming an ink plate, and covering an opening of the ink pressure chamber of the cavity plate with the plate-like body. 4. The method according to claim 3, wherein said groove processing is performed by shot blast processing. 5. The method according to claim 1, wherein the groove processing is performed such that at least one of the electrodes is left at a position in the plate where the electrodes are laminated. 5. The method for forming an inkjet head according to item 4.