JPH06338752A - Piezoelectric oscillator - Google Patents

Abstract

PURPOSE:To realize the holding structure for piezoelectric oscillator which is stable and reduces the characteristic very little. CONSTITUTION:Projecting materials 3 made of conductive materials like a metal or ceramics are linearly attached along the nodal line of lengthwise oscillation which is excited in a piezoelectric oscillator 1 by an electrode. The piezoelectric oscillator 1 has projecting materials 3 caught between holding tools 4 having the spring property from above and below and is held and is stored in a case. At the time of the use, an AC electric field is applied to the electrode of the piezoelectric oscillator 1 from holding tools 4 or feed parts formed in these tools 4 through projecting materials 3 to excite the lengthwise oscillation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric vibrator using a piezoelectric material such as piezoelectric ceramic, crystal, niobium lithium oxide, etc., and more particularly to a piezoelectric element holding structure.

[0002]

2. Description of the Related Art A conventional structure of a piezoelectric vibrator holding structure using a piezoelectric material such as piezoelectric ceramics, crystal, niobium lithium oxide or the like will be described below.

Piezoelectric vibrators used for mechanical filters, oscillators, etc. are made of materials such as piezoelectric ceramics, crystal, and niobium lithium oxide. Depending on the frequency range used,
Appropriate vibration modes such as spreading vibration, longitudinal thickness vibration, and bending vibration are excited by the piezoelectric effect with small vibration loss. Further, these piezoelectric vibrators have a large mechanical quality factor Qm, and can realize a filter or an oscillator with higher frequency accuracy than a filter or an oscillator using a capacitor or a coil.

Therefore, it is one of the important techniques to hold the piezoelectric vibrator so as not to suppress the vibration. Generally, it is held near a node where the vibration amplitude becomes 0 and configured as a filter or an oscillator. Since the vibration node is a point or line that does not have an area, ideally the area of the piezoelectric vibrator is 0.
It is desirable to hold the piezoelectric vibrator by the points or lines, but in order to realize stable holding of the piezoelectric vibrator, in reality, the characteristics are sacrificed to some extent and held with a finite area.

FIG. 5 is a perspective view of a rectangular plate type piezoelectric vibrator 11 made of a piezoelectric material such as a piezoelectric ceramic, in which electrodes 12 are formed on two opposing main surfaces and an electric field is applied between the electrodes. Then, the spreading vibration of the square plate is excited. This vibration mode has a node where the vibration is 0 at the center of the square plate, has a node near the center of the piezoelectric vibrator as shown in the figure, and has a flat portion at the tip for stable holding. In order to prevent the vibration from being disturbed, the holder 13 having a spring property is pressed from both sides of the piezoelectric vibrator and held by sandwiching it.

FIG. 6 is a perspective view of a rectangular plate piezoelectric vibrator 14 made of a piezoelectric material, in which electrodes 12 are formed on two opposing main surfaces, and an electric field is applied between the electrodes to cause length vibration. Are excited. In the length vibration of the rectangular plate piezoelectric vibrator 14, the node of vibration is linear in the center of the rectangle, and conventionally, as shown in the same figure, the vicinity of the node of the piezoelectric vibrator has a width at the tip and a spring property. It was held by being sandwiched by the holding tool 15 held.

[0007]

The conventional piezoelectric vibrator holding structure does not deteriorate the characteristics because the piezoelectric vibrator has a certain area and is directly held by a holding tool in a dot shape or a linear shape. If the holding area is reduced like this,
The holding becomes unstable, and when a shock such as a drop is applied, the posture of the vibrator changes and the holding position changes, so that the characteristics greatly change.

Further, when the holding area is increased in order to stabilize the holding, the vibrating portion is pressed, and the vibration of the vibrator is suppressed, so that the characteristics are deteriorated.

Further, since the piezoelectric element is directly held by the holding tool, the contact area between the piezoelectric element and the holding tool varies, and as a result, the characteristics vary greatly. That is, the conventional piezoelectric vibrator holding method has a problem in that it is difficult to realize reliable and stable holding with little influence on the vibrator characteristics.

[0010]

[Means for Solving the Problems] Conductive projections such as metal or ceramics are formed on the electrode surface of a piezoelectric vibrator by a method such as thermal spraying, sputtering, vapor deposition, CVD, plating, sol-gel method or printing, and the projections are formed. Hold the piezoelectric vibrator through.

[0011]

The piezoelectric vibrator and the holder are formed by forming an electrically conductive protrusion such as metal or ceramic in the vicinity of the vibration node of the piezoelectric oscillator by, for example, thermal spraying and holding the piezoelectric oscillator through the protrusion. The area of the contact portion is determined by the tip area of the protrusion and can be made substantially constant, and the area for holding can be maximized. Further, even if the relative positions of the piezoelectric vibrator and the holder deviate to some extent, the holding position viewed from the piezoelectric vibrator is constant.

[0012]

Embodiments of the present invention will be described in detail below with reference to the drawings.

(Embodiment 1) FIG. 1 is a perspective view of a piezoelectric vibrator used in a holding structure according to a first embodiment of the present invention. In the figure, reference numeral 1 is a rectangular plate-shaped piezoelectric vibrator made of a piezoelectric material such as piezoelectric ceramic, crystal, or niobium lithium oxide, and driving electrodes 2 are attached to two opposing main surfaces. By applying an AC electric field to the electrode 2, a length vibration having a main displacement in the length direction of the piezoelectric vibrator 1 is excited. The node of this length vibration is linear in the central portion of the rectangular plate as shown in the figure, and the protrusion 3 made of a conductive material such as metal or ceramic is linearly attached along this node line 9. The width and the thickness of the projection 3 are determined in consideration of stable holding that satisfies the required vibration resistance and the allowable influence on the characteristics of the piezoelectric vibrator 1. The material of the protrusions 3 is required to be mechanically stable even if a holding force is applied and to have stable electrical properties because it also serves as a lead wire. It is determined by the electric conductivity, elastic modulus (hardness), etc.

For example, a metal such as nickel-chromium alloy, stainless alloy, tungsten, brass, silver, copper alloy or aluminum alloy, or conductive ceramic can be used as the material of the protrusion 3. And the protrusion 3
The method of forming the film is thermal spraying, sputtering, vapor deposition, CV
Construction methods such as D, plating or printing can be used.

FIG. 2 shows a holding structure for the piezoelectric vibrator 1 shown in FIG. 1, in which the vibrator 1 is vertically sandwiched between the protrusions 3 by a holder 4 having a spring property, and is housed in a case. ing. The spring property of the holder 4 is determined by the piezoelectric vibrator 1
This is for maintaining a constant pressure, and not for disturbing the vibration of the vibrator 1. The holding structure of FIG. 2 suppresses variations in characteristics, improves stability and reliability of characteristics, and realizes holding of the piezoelectric vibrator with less deterioration of characteristics.

Note that it is necessary that the projection 3 does not undergo a large plastic deformation even if it is pressed in from above and below. At the time of use, an AC electric field is applied to the electrode 2 of the piezoelectric vibrator 1 from the holder 4 or a power feeding portion (not shown in the figure) formed on the holder 4 through the protrusion 3 to extend the length. Excite the vibration.

(Embodiment 2) FIG. 3 is a perspective view of a piezoelectric vibrator used in a holding structure according to another embodiment of the present invention. In the figure, reference numeral 5 denotes a disk-shaped piezoelectric vibrator having electrodes 6 attached to two opposing main surfaces, which has a main displacement in the radial direction of the vibrator 5 when an AC electric field is applied to the electrodes 6. The spreading vibration mode can be excited. The node of this vibration is a point in the center of the disk, and a disk-shaped conductive protrusion 7 such as a metal or ceramic having an area with a tip near the node.
Is attached. Here, the area of the tip can be stably maintained to satisfy the required vibration resistance, and the allowable piezoelectric vibrator 1
It is determined in consideration of the influence on the characteristics of, and is generally about 1/50 to 1/5 of the diameter of the disc.

FIG. 4 shows a holding structure for the piezoelectric vibrator 5 of FIG. 3, in which the piezoelectric vibrator 5 is sandwiched and held by a holder 8 having a spring property via a protrusion 7. Similar to the first embodiment, the holder 8 has a spring property in order to hold the piezoelectric vibrator 1 with a constant pressing force and to prevent vibration inhibition. Further, although the projection 7 is formed in a disc shape, it goes without saying that the projection 7 may be a prism shape without being particular about this shape. At the time of use, an AC electric field is applied to the electrode 6 of the piezoelectric vibrator 5 from the holder 8 or a power feeding portion (not shown in the drawing) formed on the holder 8 via the protrusion 7 to generate a diameter. Excitation of directional vibration.

[0019]

EFFECTS OF THE INVENTION By forming an electrically conductive protrusion such as a metal or ceramic near the vibration node of a piezoelectric vibrator and holding the piezoelectric vibrator through this sprayed film, the piezoelectric vibrator and the holder are held. The area of the contact portion is determined by the tip area of the protrusion and can be made substantially constant. Therefore, considering the influence on the characteristics of the piezoelectric vibrator, the area for holding can be made as large as possible, and even if the relative position of the piezoelectric vibrator and the holder is slightly shifted, The holding position seen is constant. Therefore, it is possible to improve the stability and reliability of the characteristics and to hold the piezoelectric vibrator with less deterioration of the characteristics. Moreover, since the protrusion also serves as a lead wire for feeding power, the structure can be simplified.

[Brief description of drawings]

FIG. 1 is a perspective view of a piezoelectric vibrator used in a holding structure according to an embodiment of the present invention.

FIG. 2 is a holding structure diagram of the piezoelectric vibrator of the invention.

FIG. 3 is a perspective view of a piezoelectric vibrator used in a holding structure according to another embodiment of the present invention.

FIG. 4 is a holding structure diagram of the piezoelectric vibrator of the invention.

FIG. 5 is a perspective view of a conventional holding structure for a rectangular plate type piezoelectric vibrator.

FIG. 6 is a perspective view of a conventional holding structure for a rectangular plate type piezoelectric vibrator.

[Explanation of symbols]

 1 Piezoelectric vibrator 2 Electrode 3 Protrusion 4 Holder 5 Piezoelectric vibrator 6 Electrode 7 Protrusion 8 Holder

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masahiro Nagasawa 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (3)

[Claims] 1. A piezoelectric vibrator using a piezoelectric material, wherein conductive protrusions such as metal or ceramics are formed on the piezoelectric vibrator, and the piezoelectric vibrator is held via the protrusions. Piezoelectric vibrator. 2. A conductive projection is formed by thermal spraying, sputtering, vapor deposition,
The piezoelectric vibrator according to claim 1, which is formed by a method such as CVD, plating, a sol-gel method, or printing. 3. The piezoelectric vibrator according to claim 1, wherein a conductive protrusion such as metal or ceramic is formed on the electrode of the piezoelectric vibrator.