JPH0129088B2 - - 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 has been made with the aim of eliminating the drawbacks of these conventional products and obtaining a vibrator that has the advantages. Excellent temperature characteristics can be expected, and a resonator 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, including support, inside a container of a vibrator according to an embodiment of the present invention.
Reference numeral 1 denotes a rod-shaped crystal vibrator with a substantially square or rectangular cross section, and the length of the rod in the central axis direction is sufficiently larger than the length of each side of the end surface of the rod to produce an edge mode effect. Only the upper end of the rod, as shown by the two-dot chain line, is designed so that the same cross-sectional vibration mode as that of the so-called DT cut diaphragm occurs, which is known as the vibration mode. As is well known, the vibration mode of the DT cut diaphragm is one of the vibration modes in which each point within the plate surface moves two-dimensionally symmetrically with respect to the central axis of the plate surface. In order to generate such vibrations at the upper end of the rod, surface electrode films 2 and 3 are provided to generate an effective electric field only at the upper end. Both electrodes generate an electric field in the direction across the rod end, and the component of this electric field excluding the z-axis direction among the x, y, and z crystal axes of the crystal, especially the y-axis component, is within the electric field of the rod. Excite the sliding vibration of the part.

The electrodes 2 and 3 are routed toward the lower end so as not to create an excitation electric field as much as possible, and near the lower end of the rod 1, the terminal pins 4 and 5 that penetrate the insulating glass part of the hermetic terminal 6 are connected to the protruding parts inside the container. For example, the crystal rod 1 is fixed in a cantilevered manner by conductively adhering it by soldering or by directly adhering it to the terminal 6, and connecting it to the pins 4 and 5 with conductive paste.

The entire device is hermetically housed in a cylindrical container, but this is not shown.

FIG. 2 shows an example of the cutting direction of the crystal rod 1 with respect to the crystal axis, and the direction of the end face almost coincides with the direction of the DT plate. Alternatively, it can be said that it is almost perpendicular to the AT plate. There is a very high possibility that the temperature coefficient of frequency becomes zero at a cutting angle in this vicinity. The excitation electrode is desirably arranged so that the y-direction component of the electric field it creates is the largest and is concentrated as much as possible in a local area where vibration distortion is large (the center of each side of the tip). This embodiment does not take such detailed consideration into consideration.

FIG. 3 shows a state in which a crystal rod 1 is being cut out from a block 7 of crystal material using a wire saw or a blade saw, and 8 is a wire. As shown in the figure, the crystal block 7 is cut into a lattice shape in two steps and then cut into a large number of crystal rods.

Each figure in FIG. 4 shows a side profile of another embodiment of the crystal rod 1. All of them are designed to increase the effect of confining vibration energy to the upper end, by changing the cross-sectional shape along the longitudinal direction of the rod to make the natural frequency of the annular sliding vibration different at any cross-section. The purpose is to minimize the propagation of vibration to the lower end.

FIG. 4a shows a structure in which a plurality of cuts are made in the middle of the height, and these can be easily formed by swinging the wire saw from side to side during the cutting process.

Figures 4b to 4e show the results of processing to reduce the cross section of a part of a rectangular parallelepiped bar.During processing, the wire saw was tilted (in the cutting direction), and one side of the grid was cut off. Grind the plates to change the thickness, then stack the plates again and wire cut them, or align and glue the bars cut into a rectangular parallelepiped on the jig plate again and grind one side at a time (the ankle claw of the watch) It is made by processing similar to stone.

FIG. 4f shows an example in which a hole is formed on the side surface to change the cross section. In addition, these profile processing,
For example, if the side length of the crystal rod is 200 μm or less, it is possible to cut out a large number of crystal rods at the same time by etching from a crystal wafer, and the current thin crystal tuning fork vibrating piece can be separated from the wafer after completion of electrode attachment. The same possibility exists. The cross-sectional change may be provided not only on a pair of opposing side surfaces but also on all four side surfaces. The natural frequency of the oscillator in this mode can be approximately several 100K to several megahertz. Also, since the vibrations are balanced in each cross section like the DT board, there is no need to make it into a complicated shape like a tuning fork.

As is clear from the above, in the present invention, a vibrator with a simple shape and easy support can be constructed, making it suitable for mass production at low manufacturing costs, and with a moderately high frequency and excellent temperature characteristics. It has the effect of It goes without saying that the cutting angle, the detailed shape of the rod-shaped vibrator, the arrangement structure of the electrode membrane, the method of support, and the shape of the container are not limited to those shown in the drawings.

[Brief explanation of drawings]

Fig. 1 is a perspective view of an embodiment of the present invention, Fig. 2 is an explanatory view showing an example of the cutting direction of a crystal plate, Fig. 3 is a perspective view showing an outline of a method of processing a crystal rod, and Fig. 4 Each figure is a plan view showing the profile of a crystal rod in each other embodiment of the present invention. 1...Crystal rod, 2, 3...Excitation electrode.

Claims (1)

[Claims] 1 Cut out a rod from a crystal material whose central axis is inclined to the Y axis and whose length along the central axis is longer than the length of each side of the end surface, and one end surface of the rod is cut out. An electric field is applied to the inside of the rod to produce contour vibration, that is, to promote two-dimensional movement of each point in the end surface in a plane perpendicular to the central axis on the one end surface symmetrically with respect to the central axis. An electrode film is provided on the surface of the rod so as to be formed near the one end surface of the rod, and the electrode film is extended along the surface of the rod to near the other end surface of the rod. A crystal resonator characterized in that each extended portion is conductively fixed to an external lead terminal.