JPS59148421A - Piezoelectric resonator - Google Patents

Abstract

PURPOSE:To eliminate the spurious oscillation at the operating frequency band by adjusting the lengthwise size of a piezoelectric substrate so as to take out the harmonics of oscillation where the resonance frequency is decided by the length of the lengthwise side of the piezoelectric substrate generated in the piezoelectric substrate from the operating frequency band. CONSTITUTION:The length l of the piezoelectric substrate 1 is adjusted so that the harmonics of the oscillation where the resonance frequency is decided by the length of the lengthwise side of the piezoelectric substrate 1 generated in the piezoelectric substrate 1 together with the cross section contour shear oscillation are taken out of the frequency band between the resonance frequency and the anti-resonance frequency of the cross section contour shear oscillation of the piezoelectric substrate 1. That is, in taking the thickness (t) of the piezoelectric substrate 1 as t=614mum, the width (w) as w=736mum as constant values, and in cutting the length l in the range from 5,200mum to 3,800mum by 100mum each by a dicing cut machine, the resonance characteristic is measured by fitting a lead to electrodes 2, 3 of the piezoelectric substrate 1. In taking the l as l=4,000mum, the spurious radiation (s) by the oscillation of lengthwise side is taken out of the frequency band between the resonance frequency fr of the cross section contour oscillation of the piezoelectric substrate 1 and the anti-resonance frequency fa.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a piezoelectric resonator in which a piezoelectric substrate having a rectangular parallelepiped Z shape vibrates in a cross-sectional profile sliding vibration mode.

Conventional technology.

Conventionally, as shown in FIGS. 1 and 2, this type of piezoelectric resonator has a piezoelectric substrate 1 having a rectangular parallelepiped shape with a length of 4 and a width of W1 in thickness.
, 3, and the piezoelectric substrate 1 is polarized in the [1]W direction as shown below.

By the way, in the piezoelectric resonator as described above, the thickness t and [1]W of the piezoelectric substrate 1 are uniquely determined once the operating frequency is determined, whereas the length e only needs to be e≧2W. Therefore, l = 50 at the operating frequency of around 2 MHz.
The size was set to be constant at 00 μm.

As mentioned above, if the length 4 in the longitudinal direction of the piezoelectric substrate 1 is constant, depending on the frequency of use, not only the cross-sectional contour sliding vibration of the piezoelectric substrate 1 but also the side vibration based on the above-mentioned length β of the piezoelectric substrate 1 may occur. The spurious due to harmonics is the resonant frequency fr and the anti-resonant frequency of the cross-sectional contour sliding vibration of the piezoelectric substrate 1.
Appears between a. For example, t=614μm, w==
614Q'l.

When g=5oooμm and the working frequency is 2.225 MHz, as shown in FIG. 3, the resonant frequency "r=2.
Spurious S appears at 1hj between 160 MHz and anti-resonance frequency fa:=2.280 MHz, and when such a piezoelectric resonator is used as an oscillator or filter, the oscillation frequency may jump or the group delay time characteristics may be disturbed. There was a problem.

OBJECTS OF THE INVENTION The present invention has been made to solve the above-mentioned problems in conventional piezoelectric resonators. By adjusting the longitudinal dimension of the piezoelectric resonator, harmonics of vibrations generated in the piezoelectric substrate, whose resonant frequency is determined by the length of the longitudinal side of the piezoelectric substrate, can be removed from the operating frequency band. The purpose is to eliminate unnecessary vibrations.

SUMMARY OF THE INVENTION To summarize the present invention, there is provided a piezoelectric resonator that vibrates with a cross-sectional contour sliding vibration of a piezoelectric substrate having a rectangular parallelepiped shape, the piezoelectric resonator vibrating along a longitudinal side of the piezoelectric substrate that occurs along with cross-sectional contour sliding vibration in the piezoelectric substrate. The longitudinal dimensions of the piezoelectric substrate are adjusted so that the harmonics of the vibration, whose resonance frequency is determined by the length of the piezoelectric substrate, are out of the frequency band between the resonant frequency and anti-resonance frequency of the cross-sectional contour of the piezoelectric substrate and the anti-resonance frequency of the sliding vibration. This piezoelectric resonator is characterized by the following characteristics.

Example Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

In the present invention, as shown in FIGS. 1 and 2,
Piezoelectric substrate 1 having a rectangular parallelepiped shape with length 4, width W, and thickness t
In the piezoelectric resonator that utilizes the sliding vibration of the cross-sectional contour of the piezoelectric substrate 1, the piezoelectric substrate 1 is polarized at P in the direction of the width W by forming electrodes 2.3 on both opposing principal surfaces of the piezoelectric substrate 1, respectively. Adjust the length e as follows.

That is, the harmonics of the vibration, whose resonant frequency is determined by the length of the longitudinal side of the piezoelectric substrate 1, which occurs in the piezoelectric substrate 1 along with the cross-sectional contour sliding vibration, are opposite to the resonant frequency of the cross-sectional contour sliding vibration of the piezoelectric substrate 1. The length l of the piezoelectric substrate 1 is adjusted so that it is out of the frequency band between the resonance frequency and the resonance frequency.

Specifically, the thickness of the piezoelectric substrate 1 [L=614 μm
, the width W is a constant value of W=736 μm, and the length e is N=5.
200. 100μ■1 in the range from c+m to 3800μm
Each time, the Guising Kazoto machine (not shown) cant the sea urchin,
Resonance characteristics are measured with lead wires (not shown) attached to the electrodes 2 and 3 of the piezoelectric substrate 1, respectively. For example, 1
=5200μm.

At 4500 μm, 4200 μm, and 4000 μm, the results shown in FIGS. 4, 5, 6, and 7, respectively, are obtained.

As is clear from the above figures 4, 5, 6, and 7, when 6 = 5200 μm, the frequency is around 2.2 MHz, when 1 = 4500 μm, the frequency is around 225 MHz, and when l = 4200 μm, the frequency is around 2.2 MHz. When e is 4000 .mu.m, spurious S is produced near 2.27 MHz, and when e is 4000 .mu.m, near 2.33 MHz due to side vibration in the longitudinal direction of the piezoelectric substrate 1.

On the other hand, the resonance frequency [r
is [r-4-2.17 MHz, and the anti-resonant frequency fa is fa*2.30 MHz.

Therefore, when L=614μm and w=736μm,
If l = 4000 μm, the spurious S caused by the side vibration in the longitudinal direction of the piezoelectric substrate 1 deviates from the frequency band between the resonant frequency fr of the cross-sectional contour vibration of the piezoelectric substrate 1 and the anti-resonant frequency fa, and When an electric resonator is used as an oscillator or filter, stable oscillation characteristics and good group delay characteristics are obtained.

Even in cases other than t=614 μm and w=736 μm, the length of l can be determined experimentally in exactly the same manner as above.

Effects of the Invention As is clear from the detailed explanation, the present invention has the following effects:
In a piezoelectric resonator that uses the cross-sectional contour vibration mode of a rectangular parallelepiped piezoelectric substrate, the longitudinal dimension of the piezoelectric substrate is adjusted to generate vibration harmonics whose resonant frequency is determined by the length of the longitudinal side of the piezoelectric substrate from the operating frequency band. Because I made it come off,
Unwanted vibrations in the frequency band in which the piezoelectric resonator is used are eliminated, and a piezoelectric resonator having good resonance characteristics can be obtained.

[Brief explanation of drawings]

Figure 1 is a perspective view of a piezoelectric resonator that performs cross-sectional contour vibration;
The figure is an explanatory diagram of the polarization of the piezoelectric resonator in Figure 1, Figure 3 is an insertion loss characteristic diagram of a conventional piezoelectric resonator, and Figures 4, 5, 6, and 7 are the lengths of the piezoelectric substrates, respectively. It is an insertion loss characteristic diagram when the length between squares is changed variously. 1... Piezoelectric substrate, 2, 3... Electrode, [... Thickness,
W...width, l...length, S...spurious. Patent Applicant: Murata Manufacturing Co., Ltd. Agent, Physician Aoyama Hajime, and 2 others 7s1 Figure 2

Claims (1)

[Claims] (1) A piezoelectric resonator in which a piezoelectric substrate having a rectangular parallelepiped shape vibrates with cross-sectional contour sliding vibration, and the resonant frequency is determined by the length of the longitudinal side of the piezoelectric substrate that occurs in the piezoelectric substrate along with cross-sectional contour sliding vibration. A piezoelectric device characterized in that the dimension in the longitudinal direction of the piezoelectric substrate is adjusted so that the harmonics of the determined vibration are out of a frequency band between the resonance frequency and the anti-resonance frequency of the cross-sectional contour sliding vibration of the piezoelectric substrate. resonator.