JPH0349467Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a thickness-shear oscillator. It is already well known that a thickness-shear oscillator serves as a highly accurate time reference, and the oscillator (hereinafter, for simplicity, the term oscillator will also be used to refer to the crystal piece itself). Circular or rectangular shapes are often used, and in the field of clocks where the size of the resonator holder does not require much miniaturization, thickness-shear resonators are
Along with the development of IC, they are being used in large quantities.
On the other hand, in the field of watches, it is generally difficult to reduce the size of the cage with the thickness-shear vibrator of the above shape, so by making the shape of the vibrator rectangular, the size of the cage can be increased. Attempts are being made to miniaturize it. However, when the shape of the vibrator is rectangular, even though it is a thickness-shear vibrator, the vibration mode includes not only the thickness-shear mode but also the bending mode, which is essential. The vibration modes of a rectangular thickness-shear oscillator are shown in Figures 1A and B. Figure 1A is
This shows a first-order thickness shear mode, indicating that most of the vibration energy is concentrated below the electrode 1. Therefore, the end surface 2 of the rectangular plate forms a vibration node over a wide range in the thickness shear mode. FIG. 1B shows a higher-order bending mode that is included simultaneously with the thickness shear mode, and vibration nodes occur at positions indicated by 3, 4, 5, etc. In this case, a widespread vibration node cannot be obtained. When supporting a vibrator, it is necessary to suppress vibration nodes over a relatively large area from the viewpoint of energy loss and impact cracking resistance in the support portion. It is clear from the above description that it is difficult to support the conventional rectangular thickness-shear vibrator. An object of the present invention is to provide a compact thickness-shear oscillator that is easy to support. The gist of the present invention to achieve the above object is that in order to form vibration nodes over a wide range in the bending mode as well as in the thickness shear mode, it is possible to A slit is provided so that the vibrations in the bending mode of the parts divided by the slit have opposite phases. Examples of the present invention will be described below. FIG. 2 shows a thin rectangular crystal plate 6 of uniform thickness with two slits 7 and 8 parallel to the longitudinal direction of the rectangle, and branches 9 and 10 that are divided by the slits. 11
The lengths of the branches are the same, and the widths of branches 9 and 1 are the same.
0 are equal. The excitation electrodes of the vibrator can be placed on all three branches, but in the case of Fig. 2, the metal thin film electrode 1 is placed near the center of the branch 11.
2 are fixed to the upper and lower surfaces of the board. If a voltage with a frequency equal to the fundamental frequency of the thickness shear mode is applied between the two electrodes 12, the vibration of the thickness shear mode and the vibration of the bending mode are simultaneously excited, and the vibration of the thickness shear mode is caused by the vibration of the electrode of the branch 11. The bending mode vibration occurs near branches 9 and 1.
0 and 11, the vibration phases of the bending modes of branches 9 and 10 are in phase, and the vibration phases of the bending modes of branch 11 are opposite to those of branches 9 and 10. This situation is shown in FIG. In FIG. 3, the solid line indicates the bending mode of branches 9 and 10, and the dotted line indicates the bending mode of branch 1.
1 is shown. It can be seen from FIG. 3 that the bottom part 13 of the slit has a large extent and forms a vibration node. Examples of supporting the vibrator of the present invention are shown in FIGS. 4A, B, and C. A is an example in which the bottom of the slit is fixed to two stems with solder, adhesive, etc.
B is an example in which the lower surface of the slit bottom is fixed to a support such as a package cage, and C is an example in which the side surface of the slit bottom is fixed. FIG. 5 shows another embodiment of the present invention, in which there is only one slit, and the operation is almost the same as that of the previous embodiment. As explained above, the effects of the present invention are that the vibrator can be easily supported, the area of the support part can be increased to provide strong support, and the energy loss from the support part can be extremely small.
The vibrator has a large Q value and has excellent impact resistance. In addition, in this invention, the vibrator material is not limited to crystal, but also other piezoelectric materials,
It goes without saying that materials such as lithium tantalate can also be used.

[Brief explanation of drawings]

1A and 1B are schematic explanatory diagrams of vibration modes of a conventional rectangular thickness-shear oscillator, FIG. 2 is a perspective view of the oscillator of the present invention, and FIG. 3 is a bending mode characteristic diagram of the oscillator shown in FIG. 4A, B, and C are cross-sectional views and perspective views illustrating the supported state of a vibrator showing an embodiment of the present invention, and FIG. 5 is a perspective view showing another embodiment of the present invention. 6... Crystal plate, 7, 8... Slit, 12...
electrode.

Claims (1)

[Scope of utility model registration request] A rectangular piezoelectric crystal thin plate having a uniform thickness has two slits of equal size parallel to the long sides of the thin plate, and three slits opening toward the short sides of the thin plate. In a vibrator having branches, the width dimensions of the two outer branches among the three branches are the same, metal thin film electrodes are provided on the upper and lower surfaces of the central branch of the three branches; A thickness-shear oscillator characterized in that the branches vibrate with thickness-shear vibration and bending vibration, and the two outer branches vibrate with bending vibration in opposite phase to the bending vibration of the central branch.