JPS6118885B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thin and small piezoelectric vibrator in which a thin and small tuning fork vibrating piece is sandwiched between two transparent cases.

An object of the present invention is to provide an ultra-small and high-performance piezoelectric vibrator.

In recent years, with the spread of crystal oscillation type electronic wristwatches, crystal oscillators are being used as time standards, and they are rapidly becoming smaller, more high-performance, and less expensive.

Among these, for vibrating pieces, a processing method that applies photoetching technology is becoming popular because it is superior in terms of low cost and miniaturization.

An example of a conventional thin and small piezoelectric vibrator is shown in FIG. 1, FIG. 2, and FIG. In FIG. 1, A is a plan view of a thin and small tuning fork vibrator, and B is a cross-sectional view of A along line A-A'. FIG. 2 is a top plan view of the tuning fork type vibrating piece used in the thin and small tuning fork vibrator of FIG. 1. FIG. In FIG. 1, transparent cases 1 and 8 and a vibrating piece 3 are connected to a holding frame 1 integrally formed with the vibrating piece.
0 is hermetically sealed via a eutectic material 12. The front electrode 5 of the vibrating piece passes through the root part 6 of the vibrating piece 3,
When the holding frame 10 is pulled out and the transparent case 1 is hermetically sealed, it is pulled out to the external electrode 2 provided on the case 1 via the eutectic material 12. Similarly, the back electrode 7 passes through the root portion 11 of the vibrating element 3 and is drawn out to the external electrode 9 provided on the case 8 via the eutectic material 12 when the transparent case 8 is hermetically sealed. In this configuration, since the vibrating piece 3 is made of a very thin plate, it is susceptible to shock, and if it falls, the free end 4 of the vibrating piece will directly hit the transparent case 8, so the free end 4 is likely to be cracked, chipped, etc. In addition, since the root portion 26 of the vibrating piece 3 is directly held in the transparent cases 1 and 8 over a large area, stress is generated when it is hermetically sealed with the solder material 12, etc., which greatly reduces the frequency change after dropping. are doing. Furthermore, by holding the root portion 26 of the vibrating piece 3, there is a drawback that a large amount of vibration energy leaks to the outside during vibration, and the Q value decreases.

The present invention eliminates the above-mentioned drawbacks and eliminates chips, cracks, etc. by providing a support part integrally with the thin and small vibrating piece and holding it so that the displacement of the vibrating piece during impact is made almost parallel to the case. In addition, since the vibrating piece is not directly held, the effect of stress during hermetic sealing is small, and the frequency change after dropping is greatly reduced. Furthermore, since the vibrating piece is held via the support portion, there is little leakage of vibration energy to the outside, and the characteristics of the vibrator are greatly improved.

FIG. 3 shows an embodiment of a piezoelectric vibrator according to the present invention. FIG. 3A is a plan view.

FIG. 3B is a sectional view taken along line B-B' of A.

FIG. 3C shows the electrode arrangement on the surface of the tuning fork type vibrating piece.

FIG. 3D shows the electrode arrangement on the back side of the tuning fork type vibrating piece.

In the figure, the piezoelectric vibrator of the present invention includes a tuning fork type vibrating piece 13, support parts 14 and 15 extending in parallel from both sides of the base 13a of the tuning fork type vibrating piece 13 toward the tip 13b, and symmetrical support parts 14 and 15. Support part 14,1
5 are connected to each other, and a holding frame 17 is formed to surround the tuning fork type vibrating piece 13, and the support part 14,
15 consists of a first part extending parallel to the longitudinal direction of the tuning fork type vibrator piece, and a second part extending almost perpendicularly thereto, and the second part is located approximately at the center of the tuning fork type vibrator piece in the longitudinal direction. The tuning fork type vibrating piece is connected to the holding frame 17 at a portion thereof, and furthermore, the base bottom end portion 13c of the tuning fork type vibrating piece and the holding frame 17 are formed with a gap therebetween. At this time, the distance between the transparent cases 18, 19 and the tuning fork type vibrating piece 13 can be determined by the thickness of the solder material, or any desired distance can be obtained by photo-etching the vibrating piece 20 of the transparent case to provide a recess. can. Tuning fork type vibrating piece 13 according to this method
The method for taking out the electrode to the outside is as follows. The front electrode 21 passes through the integrated support part 14 from the tuning fork type vibrating piece 13, passes through the holding frame 16 surrounding the tuning fork type vibrating piece 13, and then connects a solder material 25 to the external electrode 23 provided in advance on the transparent case 18.
etc., to achieve hermetic sealing and electrical connection at the same time.
Similarly to the front electrode 21, the back electrode 22 is also attached to the transparent case 19 through the supporting part 15 that is integrated with the tuning fork type vibrating piece 13, and through the holding frame 16 surrounding the tuning fork type vibrating piece 13. External electrode 2
4 by solder material 25 or the like.

According to the present invention, a thin piezoelectric vibrator is formed in which a tuning fork-shaped vibrating piece, a holding frame surrounding it, and a supporting part connecting the two are integrally formed, and an upper case and a lower case are joined to the upper and lower surfaces of the holding frame. In the child, the shape of the supporting portion extends from both sides near the bottom end of the base of the tuning fork type vibrating piece, and the first support part extends parallel to the tip direction of the tuning fork type vibrating piece between the tuning fork type vibrating piece and the holding frame. and a second portion extending perpendicularly from the first portion, and the second portion is joined to the holding frame at approximately the longitudinal center of the tuning fork vibrator on the tip side of the fork portion of the tuning fork vibrator piece. Since the tuning fork type vibrating piece is formed as shown in FIG.

(a) In other words, when a shock is applied to the piezoelectric vibrator and the supporting part is bent and the tuning fork vibrator piece is displaced, the direction in which damage is likely to occur is in the direction perpendicular to the plane of the tuning fork vibrator piece. . At this time, if the tuning fork vibrator piece is tilted significantly and the tip collides with the case, it will most likely cause damage. On the other hand, in the present invention, the shape of the support part has a first part that extends parallel to the distal direction from both sides near the bottom end of the base, and a second part that bends at a right angle from there and joins to the holding frame. Since the second part is joined to the holding frame at approximately the center in the longitudinal direction of the tuning fork type vibrator piece, even if there is an impact as described above, the tuning fork type vibrator piece will not break apart due to the elasticity of the two supporting parts. Since it is displaced almost in parallel without swinging, it is possible to prevent only the tip from colliding, so damage can be significantly reduced.

(b) Since the bottom end of the base of the tuning fork type vibrator piece and the holding frame are formed with a gap, the stress generated when the holding frame and the case are hermetically sealed is buffered by the supporting part. Since it does not directly affect the vibrating piece, frequency changes due to drop impact can be extremely reduced.

[Brief explanation of the drawing]

Figure 1 shows a conventional thin and small tuning fork type vibrator.
The figure is a plan view, and FIG. 1B is a sectional view taken along line A-A' of A. FIG. 2 is a plan view of a conventional tuning fork type vibrating piece. Fig. 3 shows an embodiment of the present invention, Fig. 3A is a plan view, Fig. 3B is a sectional view taken along line B-B' of A,
FIG. 3C is a diagram showing the arrangement of electrodes on the front surface of the vibrating element, and FIG. 3D is a diagram showing the arrangement of electrodes on the back surface of the vibrating element. 1 and 8 are transparent cases, 2 and 9 are external electrodes, 3 is a vibrating piece, 4 is a free end of the vibrating piece, 5 is a front electrode, 6 is a base, 7 is a back electrode, 10 is a holding frame, 11 is a back The base of the electrode, 12 is a eutectic material, 13 is a tuning fork type vibrating piece, 14 and 15 are supporting parts, 16 is a holding frame, 18,
19 is a transparent case, 20 is a vibrating piece part of the transparent case, 21 is a front electrode, 22 is a back electrode, 23 and 24 are external electrodes, 25 is a solder material, etc., and 26 is a root part of the vibrating piece.

Claims (1)

[Claims] 1. A tuning fork type vibrating piece, a holding frame arranged to surround the tuning fork type vibrating piece, and a support part connecting the holding frame to the tuning fork type vibrating piece are integrally formed, and the supporting part connects the holding frame to the tuning fork type vibrating piece. In a piezoelectric vibrator in which an upper case and a lower case are respectively joined to the lower surface, the support portion extends from both sides of the bottom end of the base, and extends between the tuning fork type vibrating piece and the holding frame. a first portion extending parallel to the tip; and a second portion extending substantially perpendicularly to the first portion and connected to the holding frame; and a base bottom of the tuning fork vibrating piece. The end portion and the holding frame are formed with a gap, and the second portion of the support portion is shaped like a tuning fork so that the tuning fork vibrating piece is displaced substantially parallel to the piezoelectric vibrator when an impact is applied to the piezoelectric vibrator. 1. A piezoelectric vibrator, characterized in that the vibrating piece is connected to the holding frame at approximately the center in the longitudinal direction of the tuning fork type vibrator on the tip side of the fork part.