JPS5945242B2 - Tuning fork type piezoelectric vibrator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the shape and support structure of a tuning fork type piezoelectric vibrator, and more specifically, to a tuning fork that vibrates in a secondary vibration mode, increases the number of support points, and improves impact resistance. The present invention relates to type piezoelectric vibrators.

Conventionally, the shape, support structure, and vibration mode of a tuning fork type piezoelectric vibrator are as shown in FIG.

As can be seen from Figure 1, since the tuning fork is supported only at its base, it is extremely vulnerable to shocks, and devices using it should not stop due to breakage, chips, etc. I couldn't.

Particularly when used as a time standard for electronic wristwatches, its vulnerability to shocks was a major drawback.

There are also devices that are supported using springs or the like to make them strong against impact, but in this case, the number of parts increases, the cost increases, and the manufacturing process is extremely complicated.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to obtain a tuning fork type piezoelectric vibrator that has a simple support structure and is highly resistant to shock without impairing its characteristics.

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

Figure 2 shows the external shape of the piezoelectric vibrator of the present invention, in which a part 3a connecting both prongs and parts 3b and 3c connecting the base and tip node points are added to the conventional tuning fork, and the whole is integrated. It is formed by etching or the like.

As shown in FIG. 5, when using the secondary vibration mode of the tuning fork, the node point is theoretically located at a point approximately 0.2261 points from the tip (l is the length of the tuning fork). If the tuning fork is supported near this node point, energy leakage will be extremely small and there will be no negative effect on the characteristics.

Furthermore, if the thickness of the connecting part 3a and the supporting part 3c in Fig. 2 is made sufficiently smaller than the width of the tuning fork (ideally, the thickness is zero), the problem of energy leakage can be solved. It should disappear completely.

In reality, the width was set to 1/3 or less of the width of the fork.

In this case, as described above, the vibration is made in the secondary vibration mode, so if the electrode structure is as shown in FIG. 3, which is different from that shown in FIG. 1A, the vibration efficiency will be very high.

This is because the vibration state of the secondary allocation mode is as shown in FIG. 5, and the stress distribution thereof changes polarity at approximately 0.2267 points from the base, as shown in FIG.

Therefore, the electrode structure in this case is most efficient if the direction of the electric field is different between the base side and the tip side, with a point between 0.201 and 0.25 A from the base as shown in Figure 3. Therefore, if the portions 3a, 3b, and 3c are used for this electrode connection, the electrodes can be easily arranged.

Also, to fix the entire vibrator, see Figure 4A.
If the base part of the tuning fork and the above-mentioned part 3b are fixed at the same time with the U-shaped support base 4 as shown in FIG. A strong support structure can be constructed.

In addition, FIG. 4B shows another example of fixing, in which the support stand 4 fixes only the base of the tuning fork as in the conventional case, and the tip of the part 3b is also fixed by the support stand 4a, obtaining the same effect as described above. be able to.

As described above, according to the present invention, it is possible to obtain a piezoelectric vibrator that is extremely resistant to shocks by simply fixing it by simply applying burrs, as in the conventional case.

Further, due to the etching process, the dimensional accuracy is good, so the node point at the tip can be accurately supported, and there is almost no reduction in the resonance sharpness Q due to energy leakage.

Furthermore, since an electrode structure for the secondary vibration mode is adopted, the device can be put to practical use without sacrificing its characteristics even if it is miniaturized.

Therefore, it is effective when used in electronic wristwatches, etc., which require impact resistance and must be made smaller, and reliability can be greatly improved without increasing costs.

[Brief explanation of drawings]

1 is a diagram showing a conventional tuning fork type piezoelectric vibrator, A is a diagram showing an electrode structure, B is a diagram showing a support structure, C is a diagram showing a vibration state, and FIG. 2 is a diagram showing a vibration according to the present invention. 3 is a diagram showing the electrode structure, FIGS. 4A and 4B are diagrams showing different embodiments for fixing the entire vibrator to a support base, and FIG. FIG. 6 is a diagram showing the vibration state of the vibrator, and FIG. 6 is a diagram showing the stress distribution thereof. 3a...Connection part, 3b, 3c...Support part, 4...Support stand.

Claims (1)

[Scope of Claims] 1. A tuning fork type piezoelectric vibrator, characterized in that both prongs are supported near the secondary vibration mode node point of the tuning fork in addition to the base of the tuning fork. 2. The tuning fork type piezoelectric vibrator according to claim 1, further comprising a connecting portion 3a that mechanically connects the vicinity of the secondary vibration mode node point on the inside of both the prongs. 3 Parts 3b and 3c that mechanically connect the vicinity of the secondary vibration mode node point on the outside of both prongs and the base of the tuning fork, respectively.
A tuning fork type piezoelectric vibrator according to claim 1, characterized in that the tuning fork type piezoelectric vibrator is provided with: 4. Claim 1, characterized in that the tuning fork, the connection part of both prongs, and the support part are integrally molded by etching.
A tuning fork type piezoelectric vibrator as described in . 5. The tuning fork type piezoelectric vibrator according to claim 1, wherein the width of the connecting portion of the two prongs and the width of the supporting portion are 1/3 or less of the width of the prongs of the tuning fork.