JPS5814085B2 - Holding device for tuning fork piezoelectric vibrator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tuning fork-shaped piezoelectric vibrator using a bending vibration mode that is used in a low frequency band, and is particularly applicable to various devices that require good electrical characteristics and mechanical strength. The present invention relates to a holding device for a tuning fork-shaped piezoelectric vibrator that is suitable for implementation.

Conventionally, devices of this type, such as wristwatches, have piezoelectric vibrators (piezoelectric vibrators made of crystal, lithium tantalate, lithium niobate, etc.).

) came into general use, there has been a strong demand for smaller shapes, higher performance, vibration and impact resistance, as well as good electrical properties, but these demands are not mutually exclusive. This is not easily satisfied as there are contradictory points.

In other words, tuning fork-shaped piezoelectric vibrators using a bending vibration mode used in low frequency bands are excellent in terms of miniaturization, but for example, tuning fork-shaped piezoelectric vibrators using a thickness-shear vibration mode used in high frequency bands Unlike AT-cut, FC-cut, etc. crystal resonators, in order to improve vibration resistance and impact resistance, when the holder is firmly fixed and the oscillator is held, the holder is excited and exhibits the characteristic of bending vibration. Wire resonance phenomena often occurred.

When this wire resonance phenomenon occurs, vibration leakage peculiar to bending vibration occurs in the container after the vibrator is housed in the container, and the stability of the resonant frequency enjoyed by the vibrator itself is deteriorated.

The tuning fork piezoelectric vibrator shown in FIG. 5 shows a holding device for a tuning fork piezoelectric vibrator according to the prior art, which holds the vibrator vertically.

Here, 1 and 2 are the legs and the base of a tuning fork-shaped piezoelectric vibrator, respectively, and the two are connected so that the main surface of the piezoelectric plate forms a U-shape.

4 and 5 are inner parts of the leader line I fixed in the insertion hole 6 planted in the base 8, with the base 8 as the border, and 5 is the tip of the part. This is a holding part that is positioned and holds the base 2 on the main surface, and 4 is an intermediate holding part from the holding part 5 to the fixed end of the insertion hole 6.

The field of the tuning fork-shaped piezoelectric vibrator configured in this way is an odd number (
λ is the wavelength of the intermediate holding part of the resonant frequency of the vibrator), and forming a standing wave eliminates the degree of freedom in setting the length of the intermediate holding part 4 from the viewpoint of miniaturization, and , even if the length of intermediate holding part 4 is held by part 5,
For example, it is not possible to form a standing wave as is commonly used in the case of a vibrator in a contour vibration mode.

For this reason, it is extremely inconvenient when using a tuning fork-shaped piezoelectric vibrator as a reference vibrator for a wristwatch, for example, and there has been a desire for a solution to prevent the vibration leakage peculiar to this bending vibration. An accurate and easy method has not yet been developed.

In view of the above points, the present invention has been made to solve the problem, and its purpose is to improve the piezoelectric vibrator itself by improving the holding device for a piezoelectric bending vibrator having a tuning fork shape. It is an object of the present invention to provide a holding device for a tuning fork-shaped piezoelectric vibrator that does not deteriorate the characteristics enjoyed by the present invention.

Hereinafter, the present invention will be explained in detail using drawings of embodiments.

First, in order to facilitate understanding of the present invention, the configuration and operating principle of a tuning fork-shaped piezoelectric vibrator, which is the basis of the present invention, will be explained with reference to FIGS. 1 and 2.

FIG. 1 is a perspective view showing the basic configuration of a conventionally known tuning-fork piezoelectric vibrator. Electrode arrangement for vibration, each leg 11
The divided electrodes 31 are placed on the opposing main surfaces (BICI planes) of
, and leg 1.

Four-sided electrodes 32 are arranged on opposing surfaces of the main surface (82C2 plane) and side surfaces (A2C2 plane), respectively.

Note that 21 and 22 are the bases of the tuning fork-shaped piezoelectric vibrator, and connect the two legs 1] and 12.

The shape of the tuning fork-shaped piezoelectric vibrator is as follows in 1 and 11.
Each has a U-shape with the BICl plane and the 82C2,000 plane as its main plane, and the crystal axes AI+B]tc1 and A2B2+C
2 are orthogonal cubic coordinate axes, and if expressed using commonly used crystal coordinate axes x, y, z, for example, if the piezoelectric material is quartz, AI is X, Bl is 2', and Cl is Y-1. So, A2 is 2', B2 is X, and C2 is Y.

In addition, when the piezoelectric material is lithium tantalate, AI is Z, B
．． is X! ．． C1 is Yt, A2 is X', B2 is Z'
, C2 is Y'.

Here, the coordinate axes x, y, z' are the first coordinate axes x, y,
X, Y', z' means that the coordinate axes are rotated around the x axis of z, and the coordinate axes x', y'', z' are centered around the Z axis of the initial coordinate axes x, y, z. The coordinate axes x', y', and z are further rotated around the X axis after the coordinate axes have been rotated by X', Y', and Z'.

Rotating the coordinate axes in this way means rotating the extraction angle of the piezoelectric material within a range of several degrees in order to obtain frequency characteristics suitable for the temperature used, and is a design technique for piezoelectric bending vibrators. This is the usual means of

The electrode connection diagrams shown at 1 and 11 in FIG. 2 correspond to the same symbols 1 and 11 in FIG. 1, respectively, and are detailed diagrams of the parts related to each electrode. The view is shown from the top of part 11.12.

If an alternating voltage that matches the resonance frequency of the tuning fork piezoelectric vibrator is applied between the terminals DJ and E and between the terminals D2 and E2, the tuning fork piezoelectric vibrator shown at 1 and 11 in FIG.
81C each. Bending vibration is performed using the plane and the B2C2 plane as the bending vibration plane.

Reference numerals 1, 11, 111 and 1v in FIG. 3 respectively indicate an embodiment of a holding device for a tuning fork type piezoelectric vibrator of the present invention which holds the vibrator vertically, and symbols 1, 2, 4, 5, 6 , 7 and 8 are the same as the symbols used in FIG.

Although the electrode 3 is not shown, the same electrode as shown in FIG. 1 is arranged.

A part of the holding device as shown at 1 in FIG.
The intermediate holding part 4, which is located between the holding part 5 and the fixed end of the leader wire 7 implanted in the insertion hole 6, is made of materials with different acoustic impedances (for example, nickel silver and or 1 in the same figure.
As shown by 1, 111, and 1v, the material is the same as that of the intermediate holding part 4, but the cross-sectional shape of the intermediate supporting part 4 perpendicular to the direction in which the intermediate holding part 4 extends is at least one piece. By forming non-uniform areas, the acoustic impedance is mismatched.

In addition, the structure of the intermediate holding part 4 is such that as it advances from the holding part 5 in the direction of the external leader line 7 in ii, the cross-sectional shape perpendicular to that direction becomes smaller, and at 111 there is a hole (round shape in the illustration, but square shape). , an oval shape, etc.) is opened, and a recess is provided at 1v.

As a result, vibration leakage is almost eliminated as a bending vibrator.

In order to eliminate the vibration leakage, this example was tested by a person skilled in the art through a so-called clamp test in which a case is placed on the base 8, a load of about 100 g is applied to the case, and the resonance frequency fluctuation due to the effect is measured. It has been confirmed that a holding device based on this method is excellent in terms of vibration leakage.

1, 11, [11 and i■ in FIG. 4 respectively indicate another embodiment of the present invention in which the vibrator is held horizontally, and symbols 1, 2, 4, 5, 6, 7 and 8 are Figures 5 and 3
Since the symbols are the same as those used in the figures, the explanation of the structure of this example will be replaced with symbols.

In this example as well, it was confirmed by the aforementioned clamp test that vibration leakage was eliminated.

FIG. 6 shows another embodiment of the present invention;
Two holding devices shown in FIG. 1 are used on the base 2 on the main surface of the vibrator.

In this example, similar to the holding device for a tuning fork-shaped piezoelectric vibrator shown in FIG. 3, an electrode (not shown in FIG. 6, but shown in FIG. There is an advantage that the electrodes 3, t32) as shown in FIG. 1 can be electrically connected to the two holding parts 5.

As described above, regarding the characteristics of the tuning fork type piezoelectric vibrator of the present invention,
Although the explanation has focused on vibration leakage, which is a problem specific to bending vibrators, the tuning fork type piezoelectric vibrator of the present invention also has the same characteristics as the piezoelectric vibrator itself in terms of output voltage characteristics and frequency temperature characteristics. Needless to say, it does not deteriorate the electrical characteristics.

Furthermore, in terms of mechanical strength, even if a wristwatch incorporating the tuning fork type piezoelectric vibrator of the present invention is dropped from a height of 1.5 m onto a wooden board, the fluctuation rate of the resonant frequency is 2 ppm or less. It has also been confirmed that it has excellent mechanical strength.

In this way, the tuning fork type piezoelectric vibrator holding device of the present invention has the following features:
It has excellent both electrical and mechanical properties, and is also suitable for miniaturization and mass production.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the basic configuration of a tuning fork-shaped piezoelectric vibrator that is the object of the present invention, FIG. 2 is a detailed view of the electrode connection in FIG. 1, and FIGS. 3, 4, and 6. 5 is a diagram showing the structure of an embodiment of a holding device for a tuning fork-shaped piezoelectric vibrator according to the present invention, and FIG. 5 is a diagram showing the structure of a conventional holding device for a tuning fork-shaped piezoelectric vibrator. 1... Leg part, 2... Base part, 3... Electrode, 4... Intermediate holding part, 5... Holding part.

Claims (1)

[Claims] 1. A tuning fork-shaped piezoelectric body in which the main surface of the piezoelectric plate has a U-shape consisting of two legs and a base that connects the legs, and electrodes for causing bending vibration are arranged on the legs. In the holding structure that holds the base of the vibrator, whichever of the holding part and the intermediate holding part is perpendicular to the direction in which the intermediate holding part extends from the holding part holding the base to the fixed end at the other end. A holding device for a tuning fork-shaped piezoelectric vibrator, characterized in that at least one non-uniform portion is formed in the cross-sectional shape. 2. The device for holding a tuning fork-shaped piezoelectric vibrator according to claim 1, wherein the cross-sectional shape of the holding portion is larger than the cross-sectional shape of the intermediate holding portion.