JPS6410128B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a crystal resonator having a novel vibration mode based on the concept of so-called edge mode.

Conventionally, tuning fork-type or lens-type AT plates have been used as crystal resonators that are ultra-small, have relatively flat frequency-temperature characteristics, and are easy to manufacture, and have been mainly used in quartz watches and the like. However, in the tuning fork type, the oscillation frequency is a little too low, so fine adjustment of the output frequency using a frequency divider with a variable frequency division ratio becomes too coarse, which is inconvenient, and the extent to which the natural frequencies of the left and right branches of the tuning fork match Even a slight deviation due to machining error tends to cause characteristic deterioration, which is one of the causes of lower yields in mass production. On the other hand, the frequency-temperature characteristic of an AT plate resonator is a cubic curve that is difficult to compensate for, and it is extremely sensitive to the cutting angle.There are also so-called secondary vibrations, so it is difficult to match the characteristics, and the lens processing is also difficult. Since they are made individually, it is not possible to simultaneously process a large number of vibrating pieces within a crystal block or wafer, which inevitably increases the cost.

The present invention was made with the aim of eliminating the drawbacks of these conventional products and obtaining a vibrator that has the advantages. , relatively excellent temperature characteristics can be expected, and a vibrator with a moderately high frequency can be obtained. This will be explained below based on the drawings.

FIG. 1 is a perspective view showing the structure of a vibrator including support inside a container according to an embodiment of the present invention.

1 is a plate-shaped crystal oscillator, 2 and 3 are excitation electrodes, and the upper edge of plate 1 is in the bending mode shown by the imaginary line at the top of the figure (the end surface is perpendicular to the plate surface, Deformation similar to vibration, that is, deformation in which both ends and the center of the upper edge are displaced in a direction perpendicular to the board surface and in opposite directions, and each part is curved so that it is connected in a gentle curve. It is arranged so that the electric field necessary for vibration is mainly applied to the vicinity of the end.

A portion of the electrode films 2 and 3 is extended as a lead pattern to the lower end of the plate 1, and is directly connected to the lead wires 4 and 5 of the hermetic terminal 6 by means such as soldering. That is, the lower end of the plate 1 is fixed to the container. Therefore, the bending vibration has a maximum amplitude at the upper end of the plate, gradually decreases downward, and reaches zero amplitude at the lower end of the plate. The vibration behavior of the plate 1 at any given height is almost similar, and the bending vibration of the rod, which is free at both ends, is balanced by itself (there is no reaction to the support system), so the plate 1 can have a simple shape. Regardless of the situation, the overall vibration is well-balanced and there is no vibration leakage to the outside. Although there is a tendency to vibrate the lower end of the plate, the effect of fixing the lower end and the effective excitation part of the electrode film being at the upper end results in vibration with a sufficiently high Q.

Furthermore, since both this example and the conventional tuning fork have a common point of bending vibration, the end surface of the plate should be aligned with the plate surface from which the tuning fork is cut (so-called +5° Z cut, 1' shown in Fig. 2). The orientation taken with respect to the crystal axis is the second
If it is as shown in Figure 1, that is, the normal to the plate surface is approximately in the X-axis direction, and one relatively short side is in the Y-axis and +
If it is cut out at an angle of around 5 degrees, it can be expected to have at least the same temperature characteristics as a tuning fork. Also, due to the difference in vibration mode, it is easier to obtain considerably higher frequencies than with a cantilevered tuning fork. As shown in FIG. 1, the electrode films 2 and 3 for excitation are provided on the side surface of the relatively short upper end of the plate 1, and on the main part (large area) of the other electrode film 3. are provided on both sides of the board near the top edge. Then, when a voltage is applied between the electrode films 2 and 3, if we consider a cross section along a plane that includes the normal to the plate surface near the top edge and is perpendicular to the top edge, there will be areas around this cross section in the positive X plane. Since the electrode is connected to the electrode on the negative X plane, and there is one electrode on the Z' plane, a symmetrical electric field is generated on both sides of the plane that is the center of the plate thickness. That is, when an electric field component in the X direction is generated directly under one of the plate surfaces, an electric field component in the -X direction is generated directly under the other plate surface. As a result, near the top edge, the crystal material directly below one plate surface slightly stretches, and the crystal material directly below the other plate surface contracts slightly, causing the top edge to tend to bend as a whole. The way the electric field is generated near the cross section of the upper end is similar to the electric field generated in the cross section of the bar when one of the four surrounding electrodes on the Z' plane of the conventional +5°XY-cut free-free bar is removed. resemble.

FIG. 3 shows another example of changing the shape of the diaphragm in order to further increase the effect of confining vibration energy to the end of the plate.

Figure 3a shows the middle part of the board being squeezed, and Figure 3b shows the fixed end by making a hole and changing the cross section so that only the portion corresponding to the node of the free rod at both ends with a length equal to the board width remains. An example of improving the insulation effect in Figure 3c
This is an example of making it thinner toward the fixed end and thickening it as shown in Fig. 3(d) to change the natural frequency of bending of the tip and other parts to make it difficult to vibrate the base. These shapes can be cut out in large numbers directly from a crystal wafer by etching, like a tuning fork, or by cutting into a crystal block in a grid pattern with a wire saw or blade saw, a rectangular parallelepiped crystal piece as shown in Figure 1 can be created. It is also possible to obtain a large number of these and form them by side grinding. Although not shown in the drawings, the thickness of the plate may be varied by half-etching or grinding in the middle of the plate surface from the free end to the fixed end. Furthermore, instead of making the board edges flat, it is also possible to make them somewhat convex or concave.

As is clear from the above description, in the present invention, the resonator is constructed by cantilever-supporting a plate-like resonator that is simple and has a well-balanced shape. This has the effect of providing a vibrator that is easy to use, inexpensive, has a moderately high frequency, and has excellent characteristics. Of course, the cutting angle and the shape of the plate material are not limited to those shown in the drawings.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of one embodiment of the present invention, Fig. 2 is an explanatory diagram showing an example of the cutting direction of a crystal plate, and each figure in Fig. 3 is a plane of the outline of a crystal plate in other embodiments. It is a diagram. 1... Quartz plate, 2, 3... Excitation electrode.

Claims (1)

[Scope of Claims] 1. A plate made of quartz material and having two opposing sides, so that one side of the two sides makes a bending vibration within a plane including the one side and the normal line of the plate, that is, The surface of the plate in the vicinity of the one side is such that both ends and the center of the one side generate an electric field in the plate that promotes displacement in a direction perpendicular to the plane of the plate and in mutually opposite directions. and disposing an electrode film on a side surface of the one side, extending the electrode film to the vicinity of the other side opposite to the one side of the plate, and connecting the extended electrode film to a lead terminal in a conductive manner. A crystal oscillator characterized by being fixed. 2. Claim 1, characterized in that the normal to the plate surface of the plate made of quartz material is approximately in the X-axis direction, and one side that makes bending vibration is in a direction inclined at approximately +5° with respect to the Y-axis. crystal oscillator.