JPH05347536A - Piezoelectric vibrator - Google Patents

Abstract

PURPOSE:To decrease spurious wave without exerting substantial influence on an electrode even after the electrode is formed by providing vibration electrodes on both principal surface in the thickness direction of a piezoelectric substrate, and providing a specific inclined surface on the piezoelectric substrate. CONSTITUTION:Vibration electrodes 1, 2 are provided on both principal surfaces 31, 32 in the thickness direction of a piezoelectric substrate 3. Also, the piezoelectric substrate 3 is provided with inclined surfaces 331, 332, 341 and 342 for reducing end part width W2 on side faces 33, 34 for intersecting with both the principal surfaces 31, 32 of both sides in the lengthwise direction, when the main displacement direction of a thickness slide and the intersecting direction are set as the lengthwise direction and the width direction, respectively. Accordingly, by these inclined surfaces, reflection and length vibration in both sides of the piezoelectric substrate 3 are prevented, and spuriouswaves can be reduced. Moreover, since the vibration electrodes 1, 2 are provided on both principal surfaces 31, 32 in the thickness direction of the piezoelectric substrate 3, even after the vibration electrodes 1, 2 are formed, no substantial influence is exerted on the vibration electrodes 1, 2, and by adjusting the inclined surfaces 331, 332, 341 and 342, and the end part width W2, the spurious wave can be decreased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric vibrator, and more particularly to improvement of a piezoelectric vibrator utilizing thickness shear vibration.

[0002]

2. Description of the Related Art This type of piezoelectric vibrator is used for a filter or the like, and has a basic structure in which a pair of vibrating electrodes are provided on opposite main surfaces of a piezoelectric substrate made of ceramic. The piezoelectric substrate is usually an elongated hexahedron.
Although the piezoelectric vibrator having this basic structure is easy to manufacture, reflection and length vibration are likely to occur at both ends in the length direction of the piezoelectric substrate. Therefore, in the frequency-impedance characteristic or the frequency-phase characteristic, spurious is generated between the resonance frequency and the anti-resonance frequency. Various techniques have been proposed and put to practical use as spurious reducing means. One of them is provided with vibration electrodes on opposite main surfaces of the piezoelectric substrate, and inclined surfaces for reducing the end thickness are provided on both main surfaces having the vibration electrodes on both sides in the length direction so that reflection and long reflection can be achieved. A technique for preventing vibration and reducing spurious is known.

[0003]

However, in the conventional structure in which both the principal surfaces having the vibrating electrodes are provided with the inclined surfaces for reducing the end thickness, the inclined surface and the end thickness adjustment for reducing the spurious before the electrodes are formed. Need to be machined for. However, it is difficult to measure impedance characteristics and the like unless electrodes are formed. Therefore, even if it is necessary to adjust the inclined surface and the end portion thickness after forming the vibration electrode, it is difficult to cope with this. If the thickness of the inclined surface and the end portion is to be adjusted, the completed vibration electrode must be removed and machining for adjusting the thickness of the inclined surface and the end portion must be performed, which makes the adjustment work extremely troublesome. become.

Therefore, the present invention solves the above-mentioned conventional problems, and adjusts the inclined surface and the end portion thickness to substantially prevent spurious noise even after the electrode is formed without substantially affecting the electrode. A piezoelectric vibrator that can be reduced.

[0005]

In order to solve the above-mentioned problems, the present invention is a piezoelectric vibrator including a vibrating electrode and a piezoelectric substrate and utilizing thickness shear vibration, wherein the vibrating electrode comprises: The piezoelectric substrate is provided on both main surfaces in the thickness direction, and the piezoelectric substrate has end portions on both side surfaces in the length direction when the main displacement direction is the length direction and the intersecting direction is the width direction. It has an inclined surface that reduces the width.

[0006]

When the main displacement direction is the length direction and the intersecting direction is the width direction, the piezoelectric substrate has inclined surfaces for reducing the end width on both sides in the length direction. It is possible to prevent reflection and length vibration on both sides of the and reduce spurious.

The vibrating electrodes are provided on both principal surfaces in the thickness direction of the piezoelectric substrate, and the piezoelectric substrate has inclined surfaces on its side surfaces, so that the electrodes are substantially affected even after the electrodes are formed. Instead, the inclined surface and the end portion thickness can be adjusted to reduce spurious.

[0008]

1 is a plan view of a piezoelectric vibrator according to the present invention, and FIG. 2 is a front view of the same. 1 and 2 are electrodes for vibration,
Reference numeral 3 is a piezoelectric substrate. The piezoelectric substrate 3 is made of a known piezoelectric ceramic material and is polarized so as to generate thickness shear vibration.

The vibrating electrodes 1 and 2 are provided on both principal surfaces 31 and 32 in the thickness direction of the piezoelectric substrate 3. The vibrating electrodes 1 and 2 are formed according to a well-known electrode forming technique.

The piezoelectric substrate 3 has side surfaces 33 and 34 which intersect with both main surfaces 31 and 32 on both sides in the longitudinal direction when the main displacement direction of thickness slip is the length direction and the intersecting direction is the width direction. Inclined surfaces 331, 332, 341, 3 that reduce the end width W2
42.

As described above, in the piezoelectric substrate 3, when the main displacement direction is the length direction and the intersecting direction is the width direction,
Inclined surfaces 331 for reducing the end width W2 on both sides in the length direction,
Since it has 332, 341, and 342, the inclined surface 331,
By 332, 341, and 342, it is possible to prevent reflection and length vibration on both sides of the piezoelectric substrate 3 and reduce spurious.

Moreover, the vibrating electrodes 1 and 2 are provided on both principal surfaces 31 and 32 in the thickness direction of the piezoelectric substrate 3, and the piezoelectric substrate 3 has inclined surfaces 331, 332 and 34 on its side surfaces 33 and 34.
1 and 342, the inclined surfaces 331, 332, 341 and 342 and the end widths do not substantially affect the vibrating electrodes 1 and 2 even after the vibrating electrodes 1 and 2 are formed. W2 can be adjusted to reduce spurious.

In the embodiment of FIGS. 1 and 2, the piezoelectric substrate 3 is provided with inclined surfaces 331, 332, 341, 342 at two diagonal portions. In addition, as shown in FIGS. 3 and 4, the piezoelectric substrate 3 may have a structure in which inclined surfaces 332 and 341 are provided at a pair of diagonal portions.

Next, a specific example for making the spurious reduction effect more effective will be described. First, the piezoelectric substrate 3
Is the width W1 of the region that is not subjected to the width reduction by the inclined surfaces 331, 332, 341, 342, and the inclined surfaces 331, 332,
The remaining end width W2 reduced by 341, 342,
That is, the ratio of the end widths W21 and W22 (W21, W22 /
It is desirable to set W1) so as to satisfy 0 ≦ W21 and W22 / W1 ≦ 0.35. FIG. 5 shows the piezoelectric substrate 3
Shows an example in which 0 = W21 / W1 is satisfied on one side in the longitudinal direction of FIG.
An example of satisfying W21 and W22 / W1 is shown.

The piezoelectric substrate 3 has inclined surfaces 331, 33.
It is desirable that the projected length L2 and the total length L1 of 2, 341 and 342 are set so as to satisfy 0.6 ≦ L2 / L1 ≦ 0.9.

Further, in the piezoelectric substrate 3, when the ratio (W21 / W1) on one end side in the length direction is α1 and the ratio (W22 / W1) on the other end side is α2, the differences (α1 to α) are obtained.
It is desirable that 2) be set so as to satisfy 0 ≦ (α1 to α2) ≦ 0.2. 1 to 5 is 0 =
An example of (α1 to α2) is shown.

FIG. 7 is a plan view of another embodiment of the piezoelectric vibrator according to the present invention. In this embodiment, the piezoelectric substrate 3
The inclined surfaces 341 and 342 are provided on the same side.
In the case of this embodiment, the ratio (W21, W22 / W1) of the width W1 of the region that is not subjected to the width reduction by the inclined surfaces 341, 342 and the remaining end widths W21, W22 reduced by the inclined surfaces 341, 342. ) Satisfies 0.3 ≦ W21 and W22 / W1 ≦ 0.7, a more excellent spurious reduction effect can be obtained.

Next, description will be made with reference to the actual measurement data examples shown in FIGS. In FIGS. 8 to 23, the horizontal axis represents frequency (kHz), the left vertical axis represents impedance (Ω), and the right vertical axis represents phase (degree). The solid line shows the impedance characteristic, and the broken line shows the phase characteristic.

First, FIG. 8 shows the characteristics when a rectangular flat plate-shaped piezoelectric substrate is used, and FIG. 9 shows the characteristics of the piezoelectric substrate shown in FIG. W1 = 0.13 W22 / W1 = 0.27 L2 / L1 = 0.65 The characteristics when the inclined surfaces of α1 to α2 = 0.14 are provided are shown. Therefore, the conditions of 0 ≦ W21, W22 / W1 ≦ 0.35 0.6 ≦ L2 / L1 ≦ 0.9 0 ≦ (α1 to α2) ≦ 0.2 are satisfied. As shown in FIG. 8, spurious waves are generated between the resonance frequency and the anti-resonance frequency.
In, spurious is extremely small.

FIG. 10 shows characteristics when a rectangular flat plate-shaped piezoelectric substrate having no inclined surface is used, and FIG. 11 is shown in FIG.
3 and 4 with respect to the piezoelectric substrate of, W21 / W1 = 0.56 W22 / W1 = 0.63 L2 / L1 = 0.74 α1 to α2 = 0.07 The characteristics in the case where is provided are shown. Therefore, the condition of 0.6 ≦ L2 / L1 ≦ 0.9 0 ≦ (α1 to α2) ≦ 0.2 is satisfied, but 0 ≦ W21, W22 / W1 ≦
It does not satisfy 0.35. Looking at FIG. 11, spurious is generated between the resonance frequency and the anti-resonance frequency,
A sufficient spurious reduction effect cannot be obtained.

FIG. 12 shows the characteristics when a rectangular flat plate-shaped piezoelectric substrate having no inclined surface is used, and FIG.
3 and FIG. 4 with respect to the piezoelectric substrate of, W21 / W1 = 0.19 W22 / W1 = 0.20 L2 / L1 = 0.27 α1-α2 = 0.01 The characteristics in the case where is provided are shown. Therefore, the condition of 0 ≦ W21, W22 / W1 ≦ 0.350 0 ≦ (α1 to α2) ≦ 0.2 is satisfied, but 0.6 ≦ L2 / L1 ≦ 0.9.
Does not meet. As shown in FIG. 13, spurious waves are generated in a wide frequency range, and a sufficient spurious noise reduction effect cannot be obtained.

FIG. 14 shows the characteristics when a rectangular flat plate-shaped piezoelectric substrate having no inclined surface is used, and FIG.
In the case where the inclined surface of W21 / W1 = 0 W22 / W1 = 0.28 L2 / L1 = 0.75 α1 to α2 = 0.28 is provided on the piezoelectric substrate of FIG. Shows the characteristics. Therefore, FIG. 15 shows data when the condition of 0 ≦ W21, W22 / W1 ≦ 0.35 0.6 ≦ L2 / L1 ≦ 0.9 0 ≦ (α1 to α2) ≦ 0.2 is satisfied. .. As shown in FIG. 14, spurious is generated between the resonance frequency and the anti-resonance frequency, but in FIG. 15, the spurious is extremely small.

FIG. 16 shows the characteristics when a rectangular flat plate-shaped piezoelectric substrate having no inclined surface is used, and FIG. 17 shows the characteristics.
1 and 2 with respect to the piezoelectric substrate of, W21 / W1 = 0.59 W22 / W1 = 0.34 L2 / L1 = 0.85 α1-α2 = 0.25 inclined surfaces The characteristics in the case where is provided are shown. Therefore, in FIG. 15, the condition of 0 ≦ W22 / W1 ≦ 0.35 0.6 ≦ L2 / L1 ≦ 0.9 0 ≦ (α1 to α2) ≦ 0.2 is satisfied, but W21 / W1 ≦ 0.35 It shows the data when the condition is not satisfied. As shown in FIG. 17, spurious is generated near the anti-resonance frequency.

FIG. 18 shows the characteristics when a rectangular flat plate-shaped piezoelectric substrate having no inclined surface is used, and FIG.
6 shows characteristics when the inclined surface of W21 / W1 = 0 W22 / W1 = 0 L2 / L1 = 0.71 α1 to α2 = 0 is provided for the piezoelectric substrate of FIG. There is. Therefore, FIG. 19 shows data when the condition of 0 ≦ W21, W22 / W1 ≦ 0.35 0.6 ≦ L2 / L1 ≦ 0.9 0 ≦ (α1 to α2) ≦ 0.2 is satisfied. .. As shown in FIG. 18, spurious signals are generated near the anti-resonance frequency, but in FIG. 19, the spurious signals are remarkably small.

FIG. 20 shows the characteristics when a rectangular flat plate-shaped piezoelectric substrate having no inclined surface is used, and FIG.
7, the inclined surface of W21 / W1 = 0.15 W22 / W1 = 0.17 L2 / L1 = 0.66 α1 to α2 = 0.02 was provided on the piezoelectric substrate of FIG. The characteristics of the case are shown. Therefore, FIG. 21 satisfies the condition of 0.3 ≦ W21, W22 / W1 ≦ 0.7 0 ≦ (α1 to α2) ≦ 0.2, but does not satisfy 0.6 ≦ L2 / L1 ≦ 0.9. The data of the case is shown. As shown in FIG. 21, spurious signals are generated near the resonance frequency and the anti-resonance frequency.

FIG. 22 shows the characteristics when a rectangular flat plate-shaped piezoelectric substrate having no inclined surface is used, and FIG.
7, the inclined surface of W21 / W1 = 0.47 W22 / W1 = 0.55 L2 / L1 = 0.8 α1 to α2 = 0.08 was provided so as to have the shape shown in FIG. The characteristics of the case are shown. Therefore, FIG. 23 shows data when the conditions of 0.3 ≦ W21, W22 / W1 ≦ 0.7 0.6 ≦ L2 / L1 ≦ 0.90 ≦ (α1 to α2) ≦ 0.2 are satisfied. ing. As shown in FIG. 22, spurious components are generated near the anti-resonance frequency, but in FIG. 23, the spurious components are significantly reduced.

[0027]

As described above, according to the present invention, the following effects can be obtained. (A) When the main displacement direction is the length direction and the intersecting direction is the width direction, the piezoelectric substrate has inclined surfaces for reducing the end width on both sides in the length direction. A piezoelectric vibrator that can prevent reflection and length vibration on both sides of the piezoelectric substrate and reduce spurious can be provided. (B) The vibrating electrodes are provided on both main surfaces in the thickness direction of the piezoelectric substrate, and the piezoelectric substrate has inclined surfaces on its side surfaces, so that the electrodes are substantially affected even after the electrodes are formed. It is possible to provide a piezoelectric vibrator that can reduce spurious by adjusting the inclined surface and the end thickness.

[Brief description of drawings]

FIG. 1 is a plan view of a piezoelectric vibrator according to the present invention.

2 is a front view of the piezoelectric vibrator shown in FIG. 1. FIG.

FIG. 3 is a plan view showing another example of the piezoelectric vibrator according to the present invention.

FIG. 4 is a front view of the piezoelectric vibrator shown in FIG.

FIG. 5 is a plan view showing another example of the piezoelectric vibrator according to the present invention.

FIG. 6 is a plan view showing another example of the piezoelectric vibrator according to the present invention.

FIG. 7 is a plan view showing another example of the piezoelectric vibrator according to the present invention.

[Figure 8]

FIG. 23 is a diagram showing measured data of frequency-impedance characteristics and phase characteristics.

[Explanation of symbols]

 1, 2 Vibration electrode 3 Piezoelectric substrate 31, 32 Main surface 331, 332, 341, 342 Inclined surface

Claims (8)

[Claims] 1. A piezoelectric vibrator including a vibrating electrode and a piezoelectric substrate and utilizing thickness shear vibration, wherein the vibrating electrode is provided on both main surfaces in the thickness direction of the piezoelectric substrate. The piezoelectric substrate has a sloping surface for reducing the end width on both side surfaces in the length direction when the main displacement direction is the length direction and the intersecting direction is the width direction. 2. The piezoelectric vibrator according to claim 1, wherein the piezoelectric substrate is provided with the inclined surfaces at two pairs of diagonal portions. 3. The piezoelectric vibrator according to claim 1, wherein the piezoelectric substrate is provided with the inclined surfaces at a pair of diagonal portions. 4. The piezoelectric substrate has a ratio (W2 / W1) of a width W1 of a region that is not subjected to width reduction by the inclined surface and a remaining end width W2 reduced by the inclined surface such that 0 ≦ The piezoelectric vibrator according to claim 1, wherein W2 / W1 ≦ 0.35 is satisfied. 5. The piezoelectric vibrator according to claim 1, wherein the inclined surface of the piezoelectric substrate is provided on the same side. 6. The piezoelectric substrate has a ratio (W2 / W1) of a width W1 of a region that is not subjected to width reduction by the inclined surface and a remaining end width W2 reduced by the inclined surface as follows: The piezoelectric vibrator according to claim 5, wherein 3 ≦ W2 / W1 ≦ 0.7 is satisfied. 7. The piezoelectric vibrator according to claim 4, 5 or 6, wherein a projected length L2 and a total length L2 of the inclined surface of the piezoelectric substrate satisfy 0.6 ≦ L2 / L1 ≦ 0.9. 8. The piezoelectric substrate has a difference (α1 to α) when the ratio (W2 / W1) on one end side in the length direction is α1 and the ratio (W2 / W1) on the other end side is α2.
The piezoelectric vibrator according to claim 4, 5, 6 or 7, wherein 2) satisfies 0 ≦ (α1 to α2) ≦ 0.2.