JP2822647B2 - Energy confined thickness shear oscillator - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an energy trapping thickness shear resonator, and more particularly to an energy trapping thickness shear resonator used for a resonator or the like.

(Prior art)

With reference to FIGS. 5A and 5B, in the conventional energy trapped thickness-sliding vibrator 1, wax is dripped on the vibrating portion 4 of the resonator main body 3 having the electrodes 2 formed on both main surfaces thereof and in the vicinity thereof. Then, the exterior resin 5 is dipped and baked from above to form a cavity 6 around the vibrating part 4.

[Problems to be solved by the invention]

In such a conventional energy-contained thickness-sliding vibrator 1, the vibrator main body 3 is formed by forming the exterior resin 5.
The thermal stress is applied to portions other than the vibrating portion 4. When thickness shear vibration is used, the polarization axis is in a direction parallel to the main surface of the vibrator main body 3, and therefore, the stress F in the long side direction, that is, the direction of the polarization axis greatly affects the characteristics of the vibrator main body 3. .

Therefore, it is conceivable to change the material of the exterior resin 5 to one having a small thermal stress. However, considering the mounting surface and the like, the material is limited to a material having a certain hardness or more, so that the stress F is still applied. As a result, the characteristics fluctuate, for example, the effective vibration frequency band of the vibrator main body 3 is narrowed, and there is a problem that a design value cannot be obtained.

On the other hand, a prior art in which a void is formed on the entire outer periphery of a vibrator body including a vibrating part and both ends of a short side is disclosed in, for example,
No. 218213 and Japanese Utility Model Unexamined Publication No. 61-151427. In such a conventional technique, since the vibrator and the resin sheath are not in contact with each other, there is an effect that deterioration of characteristics due to thermal stress at the time of forming the resin sheath can be mitigated. is there. In other words,
In the related art disclosed in JP-A-61-218213 and JP-A-61-151427, since a gap is formed between the entire outer periphery of the vibrator and the resin sheath, the vibrator is directly held by the resin sheath. Therefore, there is a new problem that unnecessary vibration of the vibrator cannot be suppressed or absorbed by the resin exterior.

SUMMARY OF THE INVENTION Therefore, a main object of the present invention is to provide an energy confined thickness shear resonator that has a small variation in characteristics even when an exterior resin is formed and that can suppress unnecessary vibration.

[Means for solving the problem]

The present invention relates to a rectangular shape having two long sides and two short sides, the polarization axis of which is parallel to the long side, and
A vibrator body supported by two short sides, a vibrating part of the vibrator main body is located between the two short sides, and the vibrating part has a first vibrating part.
Energy confining thickness-sliding resonator, which is resin-encased so that a gap is formed, characterized in that a second gap separate from the first gap is formed in two short side portions. It is a thickness shear oscillator.

[Action]

Since the second gap is provided in the two short sides in addition to the first gap of the vibrating portion existing between the two short sides,
Stress in the direction of the polarization axis due to the exterior resin is reduced. Further, since the second gap is formed separately and independently from the first gap, a part of the vibrator body is directly held by the resin sheath, and therefore, unnecessary vibration generated in the vibrator is reduced by the resin sheath. Is absorbed by

〔The invention's effect〕

According to this invention, by forming the first gap and the second gap, the stress in the direction of the polarization axis due to the exterior resin can be alleviated. The fluctuation is small. Moreover,
Since the second gap is formed independently of the first gap, unnecessary vibration generated in the vibrator is absorbed by the resin sheath, and unnecessary vibration is suppressed.

The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

〔Example〕

The energy confinement thickness shear oscillator 10 shown in FIGS. 1A and 1B is the same as that disclosed in the above-mentioned JP-A-61-218213 and JP-A-61-151427, The prior art will be described to the extent necessary to describe the energy confinement thickness shear resonator 10 'of the embodiment according to the present invention shown in FIGS. 4A and 4B.

1A and 1B includes a rectangular vibrator main body 16 having two long sides 12 and two short sides 14. The vibrator main body 16 is polarized in a direction along its long side, that is, parallel or substantially parallel to the long side. Electrodes 18 are respectively formed on both main surfaces of the vibrator main body 16 so as to partially face each other at the center. The opposing part of these two electrodes 18 becomes the vibrating part 20. Terminals 22 are connected to the electrodes 18 on the two short sides of the vibrator body 16 by, for example, soldering.
Then, as shown by a dotted line 24, wax is dripped on the entire vibrator main body 16 and a part of the terminal 22, and the exterior resin 26 such as epoxy is dipped and baked. Then, the wax impregnates the exterior resin 26, so that a void 28 is formed in a portion surrounded by the dotted line 24.

In the energy confinement thickness-sliding vibrator 10 thus formed, the voids 28 are also formed at both ends of the vibrator main body 16, so that the stress in the polarization axis direction of the vibrator main body 16 is as shown in FIG. 5A and FIG. It is relaxed compared to the conventional one shown in FIG. 5B. Therefore, the characteristics of the energy confinement thickness shear resonator 10 are influenced mainly by the soldering of the terminals 22 and only fluctuate.

That is, as shown in FIG. 2, the impedance change amount ΔZ at the time of resonance becomes as shown by a line A in this embodiment, and the change amount is greatly reduced as compared with the prior art shown by a dotted line B. can do.

FIG. 3 shows an energy confined thickness shear resonator.
10 is a graph showing the relationship between the vibration frequency and the impedance of 10, a dotted line C shows a characteristic curve of the vibrator main body 16, a chain line D shows a characteristic curve after the terminal 22 is attached, and a solid line E shows a characteristic curve after the outer resin 26 is formed. . Note that F _r1 , F _r2 , and F _r3 indicate resonance frequencies, and F _a1 , F _a2 , and F _a3 indicate anti-resonance frequencies. Here, in the prior art shown in FIGS. 5A and 5B, the characteristic curve fluctuates from C → D → E every time the manufacturing process is performed.
In the examples shown in FIGS. 1A and 1B, only C → D changes.

According to experiments, the effective vibration frequency range ΔF (= anti-resonance frequency F _a −resonance frequency F _r ) is determined by the vibrator body indicated by the dotted line C.
In the state of 16, ΔF _C = F _a1 −F _r1 = 1180 kHz. Then, in the prior art shown in FIGS. 5A and Figure 5B, whereas a _{ΔF E = F a3 -F r3 =} 750Hz as shown by the solid line E, the first
In the example of FIG. A and FIG. 1B, as indicated by the chain line D, ΔF _D = F
the _a2 -F _r2 = 1060Hz. Thus, FIG. 1A and FIG.
In the example of FIG. B, the effective vibration frequency range ΔF after the formation of the exterior resin 26 can be made wider than in the conventional case.

In addition, since a material having high hardness can be used as the material of the exterior resin 26, variations in characteristics after completion can be reduced,
In addition, the characteristics can be improved.

However, in the structure shown in FIGS. 1A and 1B, since a void is formed between the outer peripheral resin and the outer peripheral surface of the vibrator main body, the vibrator main body is directly held by the resin outer housing. There is no part, and unnecessary vibration of the vibrator main body cannot be suppressed or absorbed by the resin exterior.

4A and 4B, the energy confining thickness shear resonator 10 'of one embodiment of the present invention includes a gap (a first gap) 28a of the vibrating portion 20 of the vibrator main body 16 and a gap 28a of the vibrator main body 16. The gaps (second gaps) 28b and 28c at the two short sides are formed separately. Other structures are the same as those in the examples shown in FIGS. 1A and 1B.

Also in this embodiment, since no stress is applied in the direction of the polarization axis at both ends of the vibrator main body 16, the same effect as in the example of FIGS. 1A and 1B can be obtained. Moreover,
According to this embodiment, since the first gap 28a and the second gaps 28b and 28c of the two short sides are formed independently of each other, unnecessary vibrators can be suppressed. That is, in this embodiment, a part of the vibrator main body 16 is directly held by the resin
Unnecessary vibrations caused by the vibration are absorbed by the resin sheath 26, and thus unnecessary vibrations are suppressed.

The present invention is also applicable to an energy confined thickness shear resonator with a capacitor described in Japanese Utility Model Application Laid-Open No. 63-149628.

[Brief description of the drawings]

FIG. 1A and FIG. 1B are illustrative views showing an example of the prior art which is the background of the present invention. FIG. 1A is a perspective view, and FIG. 1B is a plan sectional view. FIG. 2 is a graph showing the amount of impedance change during resonance in the example shown in FIGS. 1A and 1B in comparison with the prior art shown in FIGS. 5A and 5B. FIG. 3 is a graph showing the relationship between the vibration frequency and the impedance of the example shown in FIGS. 1A and 1B in comparison with the prior art shown in FIGS. 5A and 5B. 4A and 4B are illustrative views showing one embodiment of the present invention, wherein FIG. 4A is a perspective view and FIG. 4B is a plan sectional view. 5A and 5B are illustrative views showing a conventional technique, and FIG.
5A is a perspective view, and FIG. 5B is a plan sectional view. In the figure, 10 'is an energy trapping thickness shear oscillator, 12 is a long side, 14 is a short side, 16 is a vibrator main body, 20 is a vibrating portion, 26 is an exterior resin, and 28a, 28b, 28c are voids.

Claims (1)

(57) [Claims] 1. A vibrator body having a rectangular shape having two long sides and two short sides and having a polarization axis parallel to the long sides and supported by the two short sides, In the energy-trapping thickness-slip resonator, in which the vibrating part of the vibrator main body is located between two short sides and resin-encased so that a first void is formed in the vibrating part, the first void is An energy confined thickness shear resonator, wherein separate second gaps are formed in the two short sides.