JPH0241948Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a piezoelectric vibrator that is applied to oscillators, resonators, filters, etc.

A piezoelectric vibrator consists of a piezoelectric vibrating element with electrodes on both sides, elastically held between terminal plates that conduct with the electrodes.
The basic structure is that this is housed in a synthetic resin case, and a space is provided around the piezoelectric vibrating element so as not to inhibit its vibration.

By the way, if air can freely flow in and out from outside the case into the space provided around the piezoelectric vibrator, flux, cleaning fluid, etc. may enter the space due to temperature changes when the piezoelectric vibrator is soldered to the set board. It adheres to the device and causes defects such as changing the characteristics of the device and corroding the device and terminal board.

There are two methods of assembling piezoelectric vibrators: manual assembly method and automatic assembly method, and structures are adopted according to each method. However, manual assembly method has low work efficiency and cannot be mass-produced, so the product price is high. Since there is a problem of high cost, it is desirable to introduce an automatic assembly method.

In other words, the former manual assembly method is similar to Figures 1 and 2.
As shown in the figure, terminal plates 3, 3 are stacked on both sides of a piezoelectric vibrating element 2, which has electrodes 1, 1 on both sides, and are electrically connected to the electrodes. The springs 4 that absorb dimensional variations are stacked, and these are inserted into a synthetic resin case 5 that is open at the bottom, and cuts 7, 7 are made for penetrating the external terminals 6, 6 of the terminal plates 3, 3. The provided paper base 8 for preventing resin inflow is fitted into the lower part of the case 5, and then a thermosetting resin 9 is inserted into the lower part of the case 5.
The opening of the case 5 is then sealed.

As shown in FIGS. 3 and 4, the structure of the latter automatic assembly method is such that a piezoelectric vibrating element 2, which has electrodes 1 and 1 on both sides, is sandwiched between a spring terminal plate 3a and a terminal plate 3. are sequentially inserted into a case 5a whose one side is open, and a synthetic resin cap 11 is stacked on the open side of the case 5a and welded by means such as ultrasonic waves, and a thermosetting resin 9 is placed in the lower part of the case 5a. It is cast and sealed, and finally the external terminals 6, 6 of the terminal boards 3a, 3 are cut from the connecting parts 12, 12.

As mentioned above, in any structure of the piezoelectric vibrator, the gap created inside the cases 5 and 5a communicates with the vibration space 13 formed on the outer periphery of the element 2.
In rare cases, gaps may be formed between the cases 5, 5a, the terminal plates 3, 3a, and the sealing resin 9 due to differences in expansion coefficients. This has the disadvantage that it is impossible to prevent flux, cleaning liquid, etc. from adhering to the elements and terminal boards.

Further, vacuum sealing of the case may be considered as one means of sealing, but if a gap occurs in the sealing portion as described above, outside air will flow in and the case will not be effective.

This idea was made in order to solve the above-mentioned problem of sealing the space around the element in the conventional piezoelectric vibrator. The purpose of the present invention is to provide a piezoelectric vibrator that is possible and inexpensive to manufacture.

The structure of this device is that a frame-shaped elastic body that comes into close contact with the terminal plate is placed on the outer periphery surrounding the element between the corresponding surfaces of the terminal plate that holds the piezoelectric vibrating element, or the elastic body that sandwiches the frame body is compressed by both terminal plates. It is designed to improve the airtightness of the space around the element.

Hereinafter, embodiments of this invention will be described based on FIGS. 5 to 7 of the accompanying drawings.

5 and 6 show a first example in which the hand assembly method is applied, in which the outside of the piezoelectric vibrating element 22, which has electrodes 21, 21 provided on both sides, is surrounded by a frame 23 made of synthetic resin, etc. Terminal plates 24 are provided on both sides of this frame body 23.
and 24, one terminal plate 24 is brought into direct contact with the center of the electrode 21, and the other terminal plate 24 and electrode 2
1 with a spring 25 interposed between both terminal plates 2
The element 22 is held between 4 and 24, and these are inserted into a case 26 made of synthetic resin that is open at the bottom. At this time, the frame body 23 has a vibration space 27 for the element 22 inside.
At the same time, annular grooves 28, 28 are formed on both surfaces where the terminal plates 24 and 24 overlap, and a frame-shaped elastic body 29,
29 are fitted in each. During assembly, the holes 24a, 24a provided at each of the four corners of the terminal boards 24, 24
Then, the projections 23a provided at the four corners of both sides of the frame body 23 are passed through, and the projections 23a are crushed and fixed by caulking.

With such a configuration, as shown in FIG. 6, both elastic bodies 29 and 29 are assembled into the case 26 in a state in which they are compressed and deformed in close contact with the terminal plates 24, 24, and then are inserted into the case 26. A thermosetting resin 30 is cast on the lower part of the housing and sealed.

The elastic bodies 29, 29 completely seal the space 27 formed around the outer periphery of the element 22. Therefore, even if a gap occurs between the case 26 and the resin 30 due to differences in expansion coefficients between the case 26, the terminal plates 24, 24, and the sealing resin 30, the space 27 around the outer periphery of the element can be sealed. You can maintain your sexuality.

Next, the second example shown in FIG. 7 is a case where the automatic assembly method is applied, in which the frame itself that surrounds the outside of the piezoelectric vibrating element 22 and forms the vibration space is formed of an elastic body 29a such as rubber, Terminal plates 24 and 24 having annular ribs 24b for enhancing the sealing effect on both sides of this elastic body 29a are stacked, and these are sequentially housed in a case 26a with open sides, and a spring 25 is inserted between the open sides of the case 26a. Then, the cap 31 is fitted and welded, and then the lower part of the inside of the case 26a is sealed with a resin 30.

The elastic body 29a is compressed by the terminal plates 24 and 24 by the pressure of the spring 25, and comes into close contact with the terminal plates, thereby sealing the vibration space 27 formed around the outer periphery of the element 22.

As in this second example, the frame itself is made of an elastic body 29
Forming with a is advantageous in that even if the element 22 is misaligned and comes into contact with the elastic body 29a, the vibration characteristics of the element 22 will not change.

Note that in any of the examples, the vibration mode of the piezoelectric vibrating element 22 can be freely selected such as the radial direction, spread, length, bending, thickness, etc., and the piezoelectric substrate used for the element 22 may be made of a single crystal of quartz or the like in addition to ceramics. be able to.

Also, although we have shown an example using one element and two terminal boards, it is also possible to incorporate multiple elements by sandwiching the terminal board in one case, or to use a three-terminal piezoelectric vibrating element. You can do the same.

Furthermore, the transmission of electrical signals and the holding of the element 22 are not limited to metal terminal plates;
For example, the conductor may be printed on an insulating plate made of synthetic resin or the like, provided by baking, adhesion, vapor deposition, plating, or sputtering, or may be formed by laminating foil or a conductive rubber sheet.

Further, although not shown, the outside of the cases 26, 26a may be covered with a metal exterior case or coated with dip coating.

As described above, according to this invention, the frame-shaped elastic body surrounding the element is compressed and clamped in close contact with the terminal plate between the corresponding surfaces of the terminal plate that holds the piezoelectric vibrating element. The vibration space formed around the outer periphery of the element can be sealed with an elastic body, and the sealing performance of the vibration space is greatly improved.

In addition, since the vibration space of the element can be sealed with an elastic body, even if a gap is created between the sealing resin at the case opening and the case due to a difference in expansion coefficient, air will not enter or exit the vibration space, and the attachment will not occur. It is possible to prevent defects such as changes in characteristics and corrosion due to the kimono.

Furthermore, since the structure is such that an elastic body is interposed between the terminal plates, it is possible to adopt an automatic assembly method in which the case is assembled sequentially from the open side, and a low-cost piezoelectric vibrator can be obtained.

[Brief explanation of the drawing]

Fig. 1 is an exploded perspective view of a conventional piezoelectric vibrator using the hand assembly method, Fig. 2 is a vertical cross-sectional view showing the assembled state of the same as above, Fig. 3 is an exploded perspective view of the same automatic assembly method, and Fig. 4 is an exploded perspective view of the conventional piezoelectric vibrator. 5 is an exploded perspective view showing the first example of the piezoelectric vibrator according to the invention; FIG. 6 is a longitudinal sectional view showing the assembled state of the same; FIG. FIG. 8 is a longitudinal sectional view showing the second example, and a perspective view of the terminal board. 21... Electrode, 22... Piezoelectric vibration element, 23...
... Frame body, 24 ... Terminal board, 25 ... Spring,
26, 26a...Case, 27...Vibration space, 2
8... Concave groove, 29, 29a... Elastic body, 30...
Sealing resin.

Claims (1)

[Scope of utility model registration request] In a piezoelectric vibrator in which a piezoelectric vibrating element is sandwiched between terminal plates and sealed in a case, a frame-shaped structure that surrounds the piezoelectric vibrating element between the corresponding surfaces of opposing terminal plates with the piezoelectric vibrating element in between and is in close contact with the terminal plate. A piezoelectric vibrator characterized in that the elastic body or the elastic body sandwiching a frame body is compressed and held between both terminal plates.