JPS58141021A - Thickness sliding crystal oscillator - Google Patents

Abstract

PURPOSE:To obtain an oscillator whose equivalent resistance is free of the influence of both-end holding and sticking of a conductive electrode adhesive, by forming a step at least one end part of a reactangular plate crystal piece by plane work after working one main surface of the crystal piece into a curved surface. CONSTITUTION:One main surface of the crystal plate 10 has the curved surface 1 with X-axial curvature R in the center and one end part of the main surface is worked into a plane 3 with an Y'-axial step 2. A thickness sliding oscillator of said structure has leakage of oscillation energy prevented by the step 2. Therefore, an adhesive are affixed at the end part having the plane part 2 to further reinforce the energy confinement effect of the thickness sliding crystal oscillator, thus obtaining a high-Q crystal oscillator, i.e. crystal oscillator with small equivalent resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an AT-cut thickness-shear crystal resonator.

The direction of vibrational displacement of the thickness-shear crystal resonator of the rotating Y plate, such as AT cut or BT cut of the crystal plate, is parallel to the X-axis direction of the crystal plate. Conventionally, in such thickness-shear crystal oscillators, square plates or circular plates have often been used, especially when there are no restrictions on external dimensions.

However, with the miniaturization of electronic devices or for use in electronic watches, there is a demand for smaller and thinner crystal units, and at the same time, to reduce power consumption, the Q of the crystal unit
A high value, that is, a low equivalent resistance is required.

Conventionally, there is a crystal oscillator that satisfies these requirements, which is made of a rectangular plate in which the dimension of the crystal piece is long in the direction of vibrational displacement and short in the direction perpendicular to the vibrational displacement.

FIG. 1 is a perspective view of a thickness-shear crystal resonator processed into a rectangular plate elongated in the vibration direction, that is, in the X-axis direction. When the length in the X-axis direction is shortened in the four-crystal resonator shown in FIG. 1, many unnecessary vibrations occur, thereby increasing the equivalent resistance. The reason is that the vibration energy of thickness shear vibration is in the direction of vibration displacement.
That is, this is because leakage occurs in the X-axis direction.

In order to prevent such leakage of resonator energy, a method is generally known in which the thickness of both ends of the crystal resonator is made thinner than the thickness of the central part. Figure 2(a).

(b) and (c) show perspective views of the most typical thickness-shear crystal resonator that embodies this method, and (a)
is called a plano bevel type, (b) is a double bevel type, and (c) is a double convex type, and both ends of the vibrator are processed to be thin as shown.

However, in all of these crystal resonators, further improvement in terms of equivalent resistance has been desired. For example, when such a crystal resonator is sealed in a container, if both ends or one end of the resonator are held and fixed with a conductive electrode adhesive or the like, the equivalent resistance increases as a result. The reason for this is that even if it is processed into the shape shown in FIG. 2, it is not possible to completely prevent vibration energy from leaking from both ends, that is, from the holding portion.

The present invention eliminates these conventional drawbacks and provides a thickness shear crystal resonator whose equivalent resistance is not affected by the above-mentioned both-end holding or adhesion of the conductive electrode adhesive.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.The central part has a curved surface 1 having a curvature of R in the X-axis direction, and one end of this main surface has a step 2 in the Y'-axis direction. It is provided and processed into a flat surface 3. Further, the other main surface of the crystal plate 1o is processed to be flat up to both ends. In the thickness shear resonator having such a structure, leakage of vibration energy is prevented by the steps 2. Therefore, if holding or fixing with an adhesive is performed at the end portion having the flat portion 3, the equivalent resistance will hardly change. Further, by performing such processing, the energy trapping effect of the thickness-shear crystal resonator is further increased, and a crystal resonator with a high Q value, that is, a crystal resonator with a small equivalent resistance can be obtained. Note that during planar processing, it is desirable that the thickness at both ends be equal to or less than the thickness W of the central portion.

Further, the effect of the crystal resonator shown in FIG. 3 will be increased if it is hermetically sealed in a metal container or the like by holding one end, that is, holding it vertically.

The crystal resonator shown in FIG. 4 shows an embodiment suitable for holding both ends, and the central part of one main surface of the crystal plate 2o has a curved surface 11 having a curvature of R in the X-axis direction. A step 12°14 is provided at both ends of the main surface in the Y' axis direction, and a flat surface 13.1
It has 4. Therefore, when holding both ends, the plane 13.1
By applying a conductive adhesive to 5 and fixing it, it is possible to obtain a thickness shear crystal resonator that is not affected by the equivalent resistance.

A specific example of the present invention will be described below as a crystal resonator for AT power.
Using No. 19 material, the curvature R at the center of one main surface is 5o.
JIs, the plane dimensions of the end are Q and 5 in both Figures 3 and 4.
A thickness-shear crystal resonator was prepared with the following dimensions: jlB, end thickness o, and os as. As a result, the resonance frequencies were both 4.2 MHz, and the equivalent resistance of the crystal resonator shown in FIG. 3 before holding and bonding was 72 Ω.

After holding one end of the crystal resonator to the resonator sealing paste, we fixed it with conductive adhesive and measured the equivalent resistance, which was 7.
At 6Ω, it exhibited superior characteristics compared to the quartz crystal resonator manufactured by Touka. Furthermore, according to the crystal resonator shown in Fig. 4, the equivalent resistance before holding is 68Ω, and the equivalent resistance after holding and fixing is 7oΩ.
All effects were superior to conventional products.

As is clear from the above description, the thickness-shear crystal resonator of the present invention has a rectangular crystal plate having one main surface curved.
At least one end of the crystal piece is flat-processed to provide a step, and according to the present invention, leakage of vibration energy can be prevented, and as a result, changes in equivalent resistance due to assembly are small, and the Q value is Since it is possible to realize a high pressure-slip crystal resonator, its industrial value is considerable.

[Brief explanation of the drawing]

Figure 1 is a perspective view of a thickness shear crystal resonator processed into a rectangular plate, Figures 2 (a), (b), and (c) are perspective views showing conventional examples of thickness shear crystal resonators. and FIG. 4 is a perspective view of a thickness-shear crystal resonator showing each embodiment of the present invention. 1.1111...Curved surface with radius of curvature R, 2,12.
14...Step part, 3,13.15...
Holding part by plane, 4916...・0 plane, 10, 20
"""Crystal board. Name of agent: Patent attorney Toshio Nakao and 1 other person11
Figure Z' Figure 2 Figure 3 Figure 1' Figure 4 2θ 99-

Claims (1)

[Claims] One main surface of an AT-cut rectangular plate crystal piece whose thickness is in the Y'-axis direction, length in the X-axis direction, and width in the 2'-axis direction is processed into a curved surface with a curvature of R in the X-axis direction, and The other main surface is processed into a flat surface, and at least one end of the one main surface in the X-axis direction of the rectangular plate crystal piece is processed into a Y-shaped surface.
- A thickness-shear crystal resonator characterized by being processed into a plane perpendicular to the axis and having a step between it and the curved surface having the curvature of R.