JPS632166B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for efficiently and highly accurately adjusting the oscillation frequency and unbalanced vibration components of a tuning fork type single crystal resonator used in a wristwatch or the like. Currently, tuning fork type single crystal vibrators used in wristwatches, etc., are often cut out from single crystal blanks using cutting machines, but due to various processing errors, the left and right vibrating pieces of the tuning fork may have dimensional variations. As a result, large variations in oscillation frequency and unbalanced vibration components occur. For tuning fork type single crystal resonators, the above two problems are major factors that determine the characteristics of the resonator. The oscillation frequency accuracy is directly related to the time display accuracy of a wristwatch, and the unbalanced component of vibration is the vibration of the vibrating part leaking to the base of the tuning fork type single crystal oscillator, which causes the vibration of the oscillator. The vibration propagates through the support part, forming a composite resonance system in which the vibrator container is integrated, and the natural frequency of the tuning fork type single crystal vibrator itself and the natural frequency of the composite resonance system may slightly deviate, or the oscillation frequency itself may change. It may become unstable due to fluctuations. Furthermore, since vibration energy leaks, the resonant resistance value (CI value) of the vibrator increases, which increases power consumption and shortens battery life.

Several methods have been devised and put into practical use for adjusting the oscillation frequency, but none have been effective for adjusting and removing unbalanced components of vibration. Therefore, in the past, the base of a tuning fork type single crystal vibrator had to be softly supported with a spring member to prevent the vibrations at the base from leaking to the container, resulting in an increase in the size of the vibrator, a complicated structure, and This resulted in a lack of impact.

The present invention provides a method for mass producing tuning fork type single crystal resonators with excellent characteristics by eliminating unbalanced components of vibration due to processing errors, adjusting the frequency to a target value with high accuracy.

Conventionally, two main methods have been adopted for frequency adjustment methods. One method is to adjust the frequency while adding or removing mass to the vibrator, and the other is to adjust the frequency while slightly changing the dimensions of the vibrator. Methods that belong to the former include methods that utilize vacuum deposition, sputtering, laser, etc., and methods that belong to the latter include methods that utilize grindstone grinding, sandblasting, etc. Methods using vacuum evaporation, lasers, etc. allow frequency adjustment with extremely high resolution, and are suitable for things that require extremely high frequency accuracy, such as vibrators for wristwatches. However, on the other hand, the frequency adjustment range is narrow,
A disadvantage is that coarse frequency adjustment is required in advance by other methods. Furthermore, since these methods always involve heat, the temperature of the workpiece increases, resulting in a deviation between the target frequency and the adjusted frequency based on the temperature characteristics of the vibrator.
Particularly in the case of a laser, if too much energy is supplied to the vibrator, thermal twins or the like will occur inside the crystal, which will deteriorate the characteristics of the vibrator. Another disadvantage is that these methods require fairly expensive equipment. On the other hand, the method of grinding with a whetstone has been well studied, partly because it can be realized with relatively inexpensive equipment, but it has not yet reached the stage of practical use, and manual grinding and adjustment work remains the mainstream. ing. Next, FIG. 1 shows an example of a conventional frequency adjustment method using grinding. In FIG. 1, 1 is a tuning fork type single crystal vibrator, 2 is a vibrator holder, 3 is an oscillation circuit that drives the vibrator, 4 is a frequency counter, and 5 and 6 are grinders driven by a motor (not shown). It is a grindstone for use.

Using the apparatus having the above configuration, frequency adjustment is performed in the following manner. A tuning fork type single crystal vibrator 1 is fixedly clamped with a holder 2, driven to oscillate by an oscillation circuit, the output thereof is input to a frequency counter 4, the frequency of the vibrator is measured, and the value at this time is taken as . Next, a person holds the holder 2, sets the tuning fork type single crystal vibrator at the center of the grinding wheels 5 and 6, moves the holder 2 to the left (or right), and moves the tip 7 of the left vibrating piece ( Or, remove the tip part 8) of the right vibrating piece obliquely and adjust it by '= ₀ -/2 with respect to the target frequency ₀ . Next, move the holder 2 to the right (or left), remove the tip 8 of the right vibrating piece (or the tip 7 of the left vibrating piece) obliquely, adjust the remaining half of the frequency, and set the Set frequency to ₀ .

FIG. 2 shows the relationship between the dimensions of each part of the tuning fork type single crystal resonator and the natural frequency, and there is a certain relationship between the two, which is expressed by the following equation.

=KW/L ² Here: Natural frequency L: Length of the vibration part W: Width of the vibration part K: Indicates a constant specific to the vibrator. Obliquely removing the tips 7 and 8 of the left and right vibrating portions of the tuning fork type single crystal vibrator corresponds to slightly changing L and W in the above equation. However, the conventional method described above cannot be an effective means for removing and adjusting the unbalanced component of vibration, and especially in the grinding method, it depends on the delicate touch of the human hand. The situation was such that automation of the grinding process had not yet been resolved, and there was no way to mass-produce tuning fork-shaped single crystal resonators. In addition, there remained a major problem in terms of quality stability.

The present invention provides a frequency adjustment method that eliminates the above-mentioned conventional drawbacks, and will be described in detail below with reference to FIG. 3. In FIG. 3, 31 is a tuning fork type single crystal resonator, 32 is a left vibrating piece, 33 is a right vibrating piece,
Numerals 34 and 35 are butterfly blade shaped grindstones, which can be driven left and right synchronized or left and right independently. (Figure 3 shows that the grindstone is stopped at its home position.) Reference numerals 36 and 37 are home position detectors for the left and right butterfly-shaped grindstones, 38 is a position correction device having a vibrator holding jig, and 39 is a drive for the vibrator. 40 is a frequency counter; 41 is a device for detecting the unbalance amount of the vibrator; 42 is a control device having a frequency data and unbalance data input processing circuit for the vibrator and a judgment processing function necessary for frequency and unbalance adjustment. , 43 is a drive device for driving the butterfly blade-shaped grindstone according to the command from the control device 42; 44
is a drive body driven by the 43 grindstone drive device.

The position of the vibrator 31 is set by a position correcting device 38 so that the vibrating pieces 32 and 33 are deflected by a deflection limit amount during grinding with respect to the grinding surfaces of the butterfly-shaped grindstones 34 and 35, respectively.

Also, when grinding one side, use the left and right butterfly blade grindstones 34 and 35.
By rotating only one of the vibrating pieces 32,
33, its own deflection reaction force acts on the grinding surface, which becomes a grinding load, and its own mass is removed. At this time, more than half of the circumference of the grinding surface of the grindstone is not in contact with the grinding surface, so the necessary measurements are performed during this period.

Furthermore, if you want to grind both vibrating pieces synchronously, first rotate one of the left and right grindstones 180 degrees from the angle of the grindstone shown in Figure 3, wait, and then rotate the left and right grindstones synchronously. Vibration pieces 32, 33
Grind them alternately. At this time, necessary measurements are performed during a period when the butterfly blade grindstone is not in contact with both the vibrating pieces 32 and 33. This method allows the frequency and unbalance of the vibrator to be measured for each rotation of the grindstone.

Using the apparatus having the above configuration and functions, the unbalance adjustment and frequency adjustment of the vibrator are performed in the following manner.

A tuning fork type single crystal vibrator 31 is fixedly clamped by a holding jig 38 and driven to oscillate by an oscillation circuit 39, and its output is input to a frequency counter 40 to measure the frequency of the vibrator.
Measure the unbalance at . As an initial process, the control device 42 makes an initial judgment for adjustment based on the frequency of the vibrator and the amount of unbalance (the value is set to be the minimum when balance is achieved) obtained by the method described above. In other words, confirm that the frequency of the vibrator to be adjusted is within the adjustment frequency amount range, and if the unbalance amount is already within the tolerance range, immediately command the frequency adjustment operation described below, and if it is outside the tolerance range, proceed as follows. unbalance adjustment operation is performed.

First, in order to determine which side of the left and right vibrating pieces requires adjustment grinding, trial grinding is performed on one of the vibrating pieces 32 or 33 using the left or right butterfly blade-shaped grindstone 34 or 35. As a result, if the amount of unbalance becomes smaller than the initial value, the unbalance measurement is continued while the vibrating piece continues grinding as a balanced vibrating piece. If the value becomes larger than the initial value, the grinding wheel being ground is stopped at the origin, and the butterfly-shaped grinding wheel on the opposite side is immediately driven to grind the vibrating element on the opposite side, and the unbalance measurement is continued. If the grinding of the vibrating element, which is balanced in the manner described above, is continued, there will be a point where the unbalance becomes minimum, and if the vibrator is ground beyond that point, the unbalance will increase again. Therefore, when the vibrator unbalance amount exceeds the minimum inflection point (the point where the balance is completely achieved) within the allowable value, it is determined that the unbalance adjustment is complete (balance peak), and the grinding wheel is moved to the origin 36.
Or stop at 37. This completes the unbalance adjustment operation.

Next, the frequency adjustment operation will be explained with reference to FIG. First, as a preparatory step, the left grindstone 34 is rotated 180 degrees from the angle shown in FIG. Later, in order to alternately and continuously grind the left and right vibrating pieces, the left and right grindstones are ground by synchronous rotation 1 based on grinding timing 3 in Figure 4, and at the same time, the frequency and unbalance amount are measured at measurement timing 4 by one revolution of the left and right grindstones. The grinding adjustment is monitored by measuring each time. Proceed with the grinding adjustment using the above method, and if the amount of unbalance exceeds the allowable range,
The frequency adjustment operation is immediately stopped, and the unbalance adjustment operation is performed again to finely correct the unbalance caused by the unevenness of the polishing force between the left and right grindstones and other causes.
After the correction is completed, the operation returns to the frequency adjustment operation, and when the predetermined frequency is reached, the left and right grinding wheels 34, 35 are moved to the origin 36,
Stop at 37 to complete all adjustments.

By grinding and adjusting a tuning fork type single crystal vibrator in the manner described above, the balance between the left and right vibrating pieces 32 and 33 in the vibrator to be adjusted can be adjusted to near its limit.
In addition, since the grinding force is derived from the reaction force of the deflection of the vibrating element itself, cracks in the vibrator and breakage of the vibrating element that occur during grinding adjustment are extremely rare, and it is possible to improve the production process. Furthermore, as the grinding progresses, the amount of deflection decreases, so the amount of mass removed by grinding per revolution becomes extremely small, and by stably achieving continuous high resolution, it is possible to achieve high precision at the set frequency. It can be adjusted.

Since the unbalance caused by vibration leakage is removed from the vibrator adjusted using this method, rigid support is possible as a supporting method for the tuning fork type single crystal vibrator, making the tuning fork type single crystal vibrator smaller. This makes the structure simpler and improves impact resistance. Furthermore, in the method of the present invention, the butterfly-shaped grinding wheel reduces the number of moving parts in the device, and there is very little wear and tear on the various parts of the device due to long-term operation. Since stable frequency adjustment can be performed, it is possible to supply a large quantity of high quality and inexpensive tuning fork type single crystal vibrators.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing an example of conventional frequency adjustment, Fig. 2 is a conceptual diagram showing the relationship between dimensions of each part of a tuning fork type single crystal resonator and natural frequency, and Fig. 3 is an adjustment device in the present invention. FIG. 4 is an explanatory diagram of the grinding pattern in the present invention. 31... Tuning fork type single crystal resonator, 36, 37...
Butterfly wing shaped whetstone.

Claims (1)

[Claims] 1 In a method of adjusting the unbalance between the frequency and the vibration of both arms of the vibrator by polishing and removing the ends of both arms of a tuning fork type single crystal vibrator and changing the dimensions of the vibrator, the vibrator is A step of alternately adjusting the frequency of both arms of the vibrator by a rotational phase difference between two narrow butterfly-shaped grindstones, and a step of grinding using the elastic reaction force of the vibrator itself; A tuning fork comprising the steps of: measuring the frequency and unbalance of the vibrator for each revolution of the butterfly blade grinding wheel; and adjusting the unbalance by operating each of the two butterfly blade grindstones independently. How to adjust a type single crystal resonator.