JP2001179972A - Laminated piezoelectric element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid a hindrance in an electric characteristic even when a tolerance in accuracy of printing position of an electrode pattern in a laminated piezoelectric element which is formed in such a manner that an electrostriction material green sheet having a conductive paste and an electrode pattern printed thereon is laminated to be baked. SOLUTION: The laminated piezoelectric element 1 is constituted such that driving pillars 2 each having an external individual electrode 7 and being contracted or expanded corresponding to an applied voltage and non-driving pillars 3 each not having an external individual electrode are alternately disposed at a small pitch. The electrode pattern of the conductive paste is formed in a shape that an internal electrode 4 is not placed at each of the non-driving pillars 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a laminated piezoelectric element and a method of manufacturing the same, and more particularly, to a laminated piezoelectric element suitable for use in an ink jet head of an ink jet printer and a method of manufacturing the same. More specifically, in the present invention, a plurality of minute driving pillars (pillar sections extending in response to voltage application) and non-driving pillars (pillar sections which do not extend even when voltage is applied) are alternately arranged in the longitudinal direction. And a method of manufacturing the same.

[0002]

2. Description of the Related Art A laminated piezoelectric element is used as an actuator of an ink jet head of an ink jet printer. For example, 300 dots per inch (300dpi)
In order to realize such a high-resolution inkjet printer, this kind of piezoelectric element must be manufactured very minutely and precisely.

Referring to the accompanying drawings, the structure and manufacturing method of this type of conventional laminated piezoelectric element will be described. As shown in FIG. 1, laminated piezoelectric elements 1 are alternately arranged at a fine pitch in the longitudinal direction. A plurality of driving columns 2 and non-driving columns 3. Internal electrodes 4 and 5 and external electrodes 6 and 7 are formed on the driving column 2. When a voltage is applied between the external electrodes 6 and 7, the driving column 2 moves in a direction indicated by an arrow in FIG. It is designed to expand. The non-driving column 3 is for supporting the driving column 2 and does not have the external electrode 7 and cannot be extended. As shown in the front view of FIG. 1 (F), each drive column 2 is composed of an upper inert layer (Q layer) made of only an electrostrictive material and having no internal electrodes, and an intermediate layer having internal electrodes 4 and 5. , And a lower inactive layer (N layer) made of only an electrostrictive material and having no internal electrode.

The laminated piezoelectric element 1 is a green sheet of an electrostrictive material on which a conductive paste for forming the internal electrodes 4 and 5 is printed in a predetermined pattern (a thin sheet of a mud-like electrostrictive ceramic material dried). ) And a green sheet made of only an electrostrictive material on which the conductive paste for internal electrodes is not printed, and a conductive paste for forming the external electrodes 6 and 7 is printed, baked, and machined. It can be manufactured by applying.

The upper inactive layer (Q layer) and the lower inactive layer (N layer) of the laminated piezoelectric element 1 are made of a green sheet made of only an electrostrictive material on which no conductive paste pattern for forming internal electrodes is printed. Is formed. On the other hand, the active layer (P layer) has internal electrodes 4 and 5 alternately arranged so as to be exposed on the side surfaces of the piezoelectric element 1 as shown in the cross-sectional view of FIG. For example, the internal electrode 4 is used as a positive electrode, and the internal electrode 5 is used as a negative electrode. The active layer (P layer) alternates between green sheets 10 and 11 on which conductive pastes 8 and 9 for forming internal electrodes are printed in different printing patterns as shown in FIGS. 2A and 2B, respectively. It is formed by laminating.

FIG. 2 shows a printed pattern of a conductive paste for forming internal electrodes when eight piezoelectric elements are taken. When a plurality of green sheets are obtained as described above, the green sheets are stacked and then cut into individual blocks along a cutting line S indicated by a broken line in FIG. Next, a conductive paste for forming an external electrode is printed on both side surfaces of each block in a pattern suitable for the external electrodes 6 and 7. As shown in FIG. 1B, one external electrode 6 is a common electrode connected to the internal electrodes 5 of all the driving columns 2. In contrast, FIG.
As shown in FIG. 2D, the external electrodes 7 are individual electrodes which are individually connected to the internal electrodes 4 of the individual driving columns 2 and are independent from each other. It is used to connect to wiring such as. By firing the block thus obtained, the green sheet and the conductive paste are sintered. By forming grooves 12 between the adjacent driving pillars 2 and non-driving pillars 3 by cutting in the obtained sintered body, each driving pillar 2 is individualized.

[0007]

The above-described problems of the conventional laminated piezoelectric element and the method of manufacturing the same are caused by the fact that the driving column 2 is used as an actuator for an ink jet head.
And the non-driving pillars 3 are arranged at very small intervals (for example, 300 dots per inch), so that the positional accuracy of the printed pattern of the conductive paste for forming the external individual electrodes 7 may vary. If the processing accuracy of the groove 12 varies, the electrical characteristics of the driving column 2 often become defective. That is, for example,
A shift occurs in the printing position of the external individual electrode, and as shown by reference numeral 7 ′ in FIG.
When formed over both the driving columns 2 and the non-driving columns 3 adjacent thereto, the adjacent non-driving columns 3 are simultaneously driven by the driving signal to the driving columns 2, and the inkjet head Malfunctions. In order to prevent such inconveniences, a high degree of positional accuracy is required for forming the individual electrodes 7 and processing the grooves 12, which has been an obstacle to improving productivity.

An object of the present invention is to provide a laminated piezoelectric element having high productivity and excellent electric characteristics of a driving column, and a method of manufacturing the same. Another object of the present invention is to provide a low-cost laminated piezoelectric element.

[0009]

According to the laminated piezoelectric element and the method of manufacturing the same of the present invention, there is a possibility that a printed pattern of a conductive paste for forming an internal electrode is connected to an external individual electrode on a non-driving pillar. It is characterized in that the shape is such that there is no internal electrode. That is, according to the present invention, the first and second internal electrodes spaced apart from each other are stacked inside a rectangular parallelepiped block made of an electrostrictive material, and the block is formed of a plurality of driving columns alternately arranged in the longitudinal direction. The driving pillars are divided, and the first internal electrodes of all the driving pillars are connected to the external common electrodes arranged on the first side surface of the block,
In a laminated piezoelectric element in which a second internal electrode of each driving column is individually connected to an external individual electrode disposed on a second side surface opposite to the first side surface, the non-driving column has a second internal electrode. The internal electrode is not laminated.

According to another aspect of the present invention, a plurality of driving columns and non-driving columns are alternately arranged in a longitudinal direction using a green sheet of an electrostrictive material on which an electrode pattern made of a conductive paste is printed. The present invention provides a method of manufacturing a laminated piezoelectric element, in which an electrode pattern for forming a driving pillar internal electrode, which is made of a conductive paste and is separated from each other in a longitudinal direction, is printed on the surface of a green sheet made of an electrostrictive material. Forming a rectangular parallelepiped block in which the first and second internal electrode patterns are laminated only in the driving pillar region by laminating a plurality of the green sheets and cutting as necessary; An external common electrode pattern connected to the first internal electrode patterns of all the driving columns is arranged on the side surface, and the individual driving columns are arranged on a second side surface opposite to the first side surface. (2) a plurality of independent individual external electrode patterns which are individually connected to the internal electrode patterns and are longitudinally separated from each other are arranged, and the block thus obtained is fired, and grooves are formed between adjacent driving columns and non-driving columns. Is formed so that adjacent driving columns and non-driving columns are mutually independent.

As described above, according to the present invention, since the non-driving pillar does not have the internal electrode which may be connected to the external individual electrode, the position accuracy of the external individual electrode formed on the side face of the driving pillar is improved. Poorly, even if a part of the external individual electrode is formed on the adjacent non-driving column, the non-driving column adjacent to the driving column is not unintentionally driven, and the driving column has a problem in electrical characteristics. Not receive.

In a preferred embodiment, the non-driven columns are not printed with external common electrodes. In this case, the consumption of the electrode material can be reduced, and the cost can be reduced.

[0013]

Next, an embodiment of the present invention will be described with reference to FIGS. In these figures, components common to those shown in FIGS. 1 and 2 are denoted by the same reference numerals. Referring to FIG. 3, the laminated piezoelectric element 1 of the present invention comprises a plurality of driving columns 2 and non-driving columns alternately arranged at a fine pitch in the longitudinal direction, similarly to the conventional laminated piezoelectric element shown in FIG. 3, an upper inert layer (Q layer) made of only an electrostrictive material, and internal electrodes 4 and 5.
, And a lower inactive layer (N layer) made of only an electrostrictive material.

As can be seen from the sectional view of FIG. 3H, in this embodiment, the active layers (P layers) are alternately stacked.
It has one first internal electrode 5 and three second internal electrodes 4.
The internal electrode 4 is used, for example, as a positive electrode, and the internal electrode 5 is used as a negative electrode. The number of these internal electrodes can be appropriately increased or decreased. The active layer (P layer) is formed of green sheets 10 and 11 of electrostrictive material on which conductive pastes 8 and 9 for forming internal electrodes are printed in the printing patterns shown in FIGS. 4A and 4B, respectively. It is formed by alternately stacking.

In order to manufacture a large number of piezoelectric elements at a time from a set of stacked green sheets, a printing pattern of a conductive paste for forming an internal electrode is designed so that a plurality of printing patterns can be obtained. In the embodiment shown in FIG.
The printed pattern of the conductive paste for forming an internal electrode in the case of individual production is shown, and the laminated green sheet is cut along a cutting line S indicated by a broken line (only two lines are shown in FIG. 4). As a result, eight piezoelectric elements are manufactured. Thus, each conductive paste print pattern 8 and 9 has eight columns 13. Of course, the number of columns 13 can be arbitrarily increased or decreased.

Each column 13 of conductive paste print patterns 8 and 9 for forming internal electrodes 4 and 5
Has a plurality of independent internal electrode patterns 14 spaced apart from each other in the length direction. For convenience, FIG. 4 shows each column 13 as having nine internal electrode patterns 14.
Can be increased or decreased as appropriate, and can be, for example, 32. As shown in FIG. 4, two adjacent internal electrode patterns 14 in each column 13 are separated at equal intervals in the length direction of the column 13, and a conductive property is provided between two adjacent internal electrode patterns 14. There is no paste print pattern.

Green sheet 1 used for active layer (P layer)
The conductive paste print patterns 8 and 9 printed on the internal electrodes 0 and 11 are formed such that the internal electrodes 4 and 5 formed by the conductive pastes are alternately arranged as shown in the sectional view of FIG. It is arranged so as to be exposed on both side surfaces of the element 1. The region L at both ends in the longitudinal direction of each column 13 also
The electrode pattern 15 (its function will be described later) is printed.

The piezoelectric element 1 of the present invention can be manufactured by the following method. First, green sheets made of only an electrostrictive material on which no conductive paste for forming an internal electrode is printed are laminated in a number necessary for forming a lower inert layer (N layer), and the conductive sheet for forming an internal electrode is formed thereon. A required number of green sheets 10 and 11 for the active layer (P layer) on which the paste print patterns 8 and 9 are printed are laminated, and only the electrostrictive material for forming the upper inactive layer (Q layer) thereon is formed. Green sheets. By cutting the obtained laminate along the cutting line S (FIG. 4), a plurality of elongated rectangular parallelepiped blocks are obtained. As shown in the cross-sectional view of FIG. 3H, in each of the obtained blocks, the edge of the internal electrode 5 is exposed on the right side of the block, and the edge of the internal electrode 4 is exposed on the left side of the block. ing.

Next, as shown in FIG. 3B, the first internal electrodes 5 of all the driving columns 2 are provided on the right side surface of this block.
The conductive paste pattern of the external common electrode 6 connected to the print pattern 14 is printed. The external common electrode 6 extends to the regions L at both ends. Further, as shown in FIG. 3D, on the left side surface of this block, external independent individual electrodes 7 which are individually connected to the print pattern 14 of the second internal electrode 4 of each drive pillar 2 are provided. The electrode pattern to be formed is printed. Further, external common electrode lead-out terminals 16 are printed on both end regions L of the block.

Next, the green sheet and the conductive paste are sintered by firing the block thus obtained. Further, similarly to the conventional laminated piezoelectric element shown in FIG. 1, a groove 12 deeper than the active layer (P layer) is formed between the adjacent driving columns 2 and the non-driving columns 3 by cutting. Each drive column 2 is individualized.

The laminated piezoelectric element 1 thus formed is mounted on a printed circuit board or the like, and the individual external electrodes 7 arranged on the left side of the piezoelectric element block are connected to individual wirings of the printed circuit board by soldering or the like. Is done. The external common electrode lead-out terminal 16 is also connected to the wiring of the printed circuit board on the same left side as the external individual electrode 7. Since these external common electrode lead-out terminals 16 are connected to the external common electrodes 6 via the electrode patterns 15 in the end region L, the electrode patterns 15 in the end region L and the external common electrode lead-out terminals 16 are used. Thereby, the external common electrode 6 can be connected to the wiring of the printed circuit board on the same side as the external individual electrode 7.

A required number of laminated piezoelectric elements 1 can be mounted on a printed circuit board according to the number of pixels of the ink jet head. When driving the laminated piezoelectric element 1, when a voltage having an arbitrary driving waveform is applied between the external common electrode lead-out terminal 16 and the external individual electrode 7 of any one of the driving columns 2, the driving column 2 is 3 (D), the ink is ejected from the inkjet head by extending in the direction indicated by the arrow. The non-drive pillar 3 plays a role of supporting the drive pillar 2. When the application of the voltage is stopped, the driving column 2 returns to the initial state.

According to the present invention, the conductive paste print patterns 8 and 9 for forming the internal electrodes to be printed on the green sheets 10 and 11 are separated in the length direction by sections where no conductive paste exists as shown in FIG. 3 is composed of isolated individual electrode patterns 14 shown in FIG.
As can be seen from (C) and (F), in the laminated piezoelectric element 1 of the present invention, the internal electrodes 4
And 5 are not present. Since there is no internal electrode inside the non-driving pillar 3, the printing position of any one of the external individual electrodes is shifted as shown by reference numeral 7 'in FIG. Even when a part of the second external individual electrode 7 ′ is formed across the non-driving column 3 adjacent to the driving column 2, the non-driving column 3 is not unintentionally driven. Note that, in the illustrated embodiment, the conductive paste print patterns 8 and 9 have the internal electrodes 4 inside the non-driving pillar 3.
Although there is a pattern in which neither of the above and 5 does not exist, in order to achieve the object of the present invention, it is sufficient if there is no internal electrode 4 inside the non-driving pillar 3.

FIG. 3I shows a variation of the external common electrode 6. In this variation, the external common electrode 6 is not formed on the non-driving pillar 3 in the region of the active layer (P layer) and the upper inactive layer (Q layer). With such an electrode pattern, the consumption of the conductive paste can be reduced, and the cost can be reduced.

[0025]

A first effect of the present invention is that the productivity of the laminated piezoelectric element can be improved while securing desired electric characteristics. The reason for this is that the non-driven columns do not have internal electrodes, and the non-driven columns are not unintentionally driven even if the positional accuracy of the formation of external individual electrodes and groove cutting varies, resulting in a non-defective product ratio. This is because it is possible to increase the tolerance of forming the external individual electrode and the groove cutting process while securing the tolerance. The second effect of the present invention is as follows.
This means that costs can be reduced. The reason is,
This is because, in the preferred embodiment, the internal electrodes are not stacked on the non-driven pillars which do not need to expand and contract in function, so that the consumption of the electrode material is reduced.

[Brief description of the drawings]

1 (A) is a plan view, FIG. 1 (B) is a right side view, FIG. 1 (C) is a right side view before forming a common electrode, FIG. 1 (D) is a left side view, (E) is a left side view before forming an individual electrode, (F) is a front view, (G) is a rear view, and (H) is a cross-sectional view taken along line AA of FIG. 1 (A).

FIG. 2 is a plan view showing an internal electrode printing pattern of the conventional laminated piezoelectric element shown in FIG.

3 (A) is a plan view, FIG. 3 (B) is a right side view, FIG. 3 (C) is a right side view before forming a common electrode, and FIG. 3 (D) is a left side view. , (E) is a left side view before forming an individual electrode, (F) is a front view, (G) is a rear view, (H)
3A is a cross-sectional view along the line AA in FIG. 3A, and FIG. 3I is a right side view showing a variation of the common electrode.

4 is a plan view showing an internal electrode printing pattern of the laminated piezoelectric element of the present invention shown in FIG.

[Explanation of symbols]

 1: Multilayer piezoelectric element 2: Driving column 3: Non-driving column 4: Second internal electrode 5: First internal electrode 6: External common electrode 7: External individual electrode 13: Column of conductive paste printing pattern 14: Internal electrode pattern

Claims (5)

[Claims] 1. A cuboid block made of an electrostrictive material, in which first and second internal electrodes separated from each other are laminated, and the block is not driven by a plurality of driving columns alternately arranged in the longitudinal direction. The first internal electrodes of all the driving columns are connected to an external common electrode disposed on the first side surface of the block, and the second internal electrodes of each driving column are connected to the first internal electrodes.
In a laminated piezoelectric element of a type individually connected to external individual electrodes arranged on a second side surface opposite to the side surface, no second internal electrode is laminated on the non-driving pillar. Multilayer piezoelectric element. 2. The multilayer piezoelectric element according to claim 1, wherein the first internal electrode is not laminated on the non-driving pillar. 3. The method according to claim 1, wherein the non-driving pillar has a first side.
2. An external electrode is not formed.
Or a laminated piezoelectric element based on 2. 4. A method for manufacturing a laminated piezoelectric element in which a plurality of driving columns and non-driving columns are alternately arranged in a longitudinal direction using a green sheet of an electrostrictive material on which an electrode pattern made of a conductive paste is printed. : Printing electrode patterns for forming drive column internal electrodes, which are made of a conductive paste and are separated from each other in the longitudinal direction, on the surface of a green sheet made of an electrostrictive material, laminating a plurality of the green sheets, and cutting as necessary. To form a rectangular parallelepiped block in which the first and second internal electrode patterns are stacked only inside the driving pillar, and the first side of all the driving pillars is provided on the first side surface of the obtained block.
An external common electrode pattern connected to the internal electrode pattern is arranged, and is separately connected to the second internal electrode pattern of each driving pillar on a second side surface opposite to the first side surface and is separated from each other in the longitudinal direction. A plurality of independent external individual electrode patterns are arranged, and the obtained block is fired, and a groove is formed between the adjacent driving column and the non-driving column to form the adjacent driving column and the non-driving column. A method for manufacturing a laminated piezoelectric element, which is independent of each other. 5. The method according to claim 4, wherein in the step of arranging the common external electrode, no external common electrode is printed on the non-driving pillar.