JPH0526130B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an automatic setting device for electrode spacing used to measure the characteristics of vibrating elements of crystal resonators, ceramic resonators, etc. in the manufacturing process thereof. .

(Problems to be solved by the prior art and the invention) In the manufacture of crystal resonators, ceramic resonators, etc., the vibration characteristics are determined before attaching electrodes to the vibrating piece (crystal plate, ceramic plate, etc.) that is the main component. Measure.

The measurement of vibration characteristics is performed by inserting a vibrating piece between opposing electrodes that are arranged with a gap greater than the thickness of the vibrating piece and causing the vibrating piece to oscillate.

At this time, the size of the gap remaining between the vibrating element and the electrode affects the oscillation condition, that is, the oscillation frequency and amplitude.

Therefore, it is necessary to set the size of this void to a value suitable for measuring characteristics.

A first object of the present invention is to detect the interelectrode capacitance, which is mainly controlled by the size of the gap between the electrodes of the vibrating element, when measuring the characteristics, and automatically adjust the electrode spacing to be suitable for the characteristic measurement. The goal is to provide a device to configure the settings.

A second object of the invention is to detect the oscillation intensity of the oscillation circuit, which is controlled by the size of the gap between the vibrating element and the electrode, during the characteristic measurement, and automatically set the electrode spacing to be suitable for the characteristic measurement. The objective is to provide a device that

(Means for Solving the Problems) In order to achieve the first object, an automatic electrode spacing setting device for measuring the characteristics of a vibrating element according to the first invention uses an actuator that expands and contracts according to an applied signal. A pair of electrodes whose spacing is adjustable, a capacitance detector that measures the capacitance between the electrodes and generates a signal corresponding to the capacitance value, and compares the magnitude of the output signal of the capacitance detector with the magnitude of a reference signal. The actuator is comprised of a circuit that feeds back a signal to the actuator so that the difference becomes zero.

In order to achieve the second object, the automatic electrode spacing setting device for measuring the characteristics of a vibrating element according to the second invention includes a pair of electrodes whose spacing can be adjusted by an actuator that expands and contracts in response to an applied signal. , an oscillation circuit that uses the electrode into which a vibrating piece is inserted as a vibrator, a detector that generates a signal corresponding to the output amplitude of the oscillation circuit, and a magnitude of the output signal of the detector and a magnitude of a reference signal. The actuator is comprised of a circuit that feeds back a signal to the actuator so that the difference becomes zero.

(Example) The present invention will be described in more detail below with reference to the drawings and the like.

The principle of the automatic electrode spacing setting device when measuring the characteristics of a vibrating element according to the first invention (capacitance monitoring method) will be explained with reference to FIG.

Parallel electrodes A and D for measuring area S (m ² ) are placed facing each other.

In between, the edge has the same shape as the electrode and the same area S
(m ² ) and a thickness tx (m), a vibrating element Fx is inserted through a gap G of t _A (m).

At this time, if the edge capacitance is ignored, the interelectrode capacitance becomes
C _E is given by the following formula.

C _E = ε ₀ S/(t _A + tx/K) (F) ...(1) Here, ε ₀ is the dielectric constant of air, approximately 8.854×10 ^-12 (F/m), and K is the vibrating element. It is the relative dielectric constant of Fx.

Area S of electrode and vibrating element Fx and vibrating element Fx
When the relative dielectric constant K of is constant, the interelectrode capacitance C _E is,
It is determined by the size _tA of the air gap G and the thickness tx of the vibrating element Fx.

The rate of change of _CE with respect to t _A dC _E /dt _A and the rate of change of CE with respect to tx dC _E /dtx are calculated as dC _E /dt _A = -ε ₀ S/(t _A +tx/K) ² (F /m)
...(2) dC _E /dtx = -ε ₀ / [K(t _A +tx/K) ² ] (F/m) ...(3).

dC _E /dt _A is K times larger than dC _E /dtx, and the vibrating element
When the dielectric constant K of Fx is sufficiently larger than 1, the interelectrode capacitance C _E is mainly controlled by the size t _A of the air gap G.

Therefore, when the condition K≫1 is satisfied,
If the interelectrode capacitance C _E is kept constant by controlling the electrode spacing, the size t _A of the air gap G can be kept constant.

With reference to FIG. 4, the principle of an automatic electrode interval setting device for measuring characteristics of a vibrating element according to the second invention (oscillation amplitude monitoring method) will be explained. The arrangement of the electrodes and the shape of the vibrating element are the same as in the first invention described above.

When the electrode into which this vibrating piece is inserted is connected to an oscillator as a vibrator, the oscillation amplitude changes depending on the size of the air gap G, t _A . When t _A is small, the amplitude is large, and when t _A is large, the amplitude is large. The amplitude becomes smaller. Therefore, if the oscillation amplitude is kept constant by controlling the electrode spacing, the size t _A of the air gap G can be kept constant.

Figure 1 shows the first invention (capacity monitoring method) and the second invention.
1 is a schematic diagram showing an embodiment of an electrode support structure of an electrode spacing device according to the invention (oscillation amplitude monitoring method); The non-grounded electrode A is fixed to the main body C via an insulator B.

Grounded electrode D facing this non-grounded electrode A
is attached to the main body C via a piezoelectric actuator E that expands and contracts depending on the magnitude of applied voltage. FIG. 2 is a block diagram showing an embodiment of an automatic electrode spacing setting device for measuring characteristics of a vibrating element according to the first invention (capacitance monitoring method).

The non-grounded electrode A and the grounded electrode D are connected to the non-grounded input terminal H and the grounded input terminal I of the capacitance detection DETc, respectively, as shown in FIG. The piezoelectric actuator E is connected to the output terminal of the dual-input operational amplifier OP.

First, after inserting the standard vibrating element F _R (hereinafter referred to as the standard vibrating element) between electrodes A and D, the operational amplifier
By adjusting the reference voltage V _R applied to the non-inverting input terminal of OP, the size t _A of the air gap G of the vibrating element Fx is adjusted by adjusting the voltage at the output of the operational amplifier OP and expanding and contracting the actuator E. Set the size to be appropriate for the characteristic test.

When the standard vibrating element F _R is replaced with an arbitrary vibrating element Fx, if the thickness tx of the vibrating element Fx is different from the standard vibrating element F _R , the size of the gap G is _{t A} if the electrode is fixed.
changes, and the interelectrode capacitance changes. However, in the present invention, the gain of the operational amplifier OP is sufficiently larger than 1, so the DC output voltage V _T of the capacitance detector DETc is equal to the reference voltage V _R
electrode A by means of a piezoelectric actuator E connected to the output of the operational amplifier OP such that
Since the distance between and D is controlled, the interelectrode capacitance is kept constant, and the size _tA of the gap G is also kept constant.

FIG. 3 is a block diagram showing an embodiment of an automatic electrode spacing setting device for measuring characteristics of a vibrating element according to the second invention (oscillation amplitude monitoring method).

The electrode support structure of the automatic electrode spacing setting device is the same as that of the first invention.

As shown in FIG. 3, electrodes A and D into which the vibrating piece Fx is inserted are connected to vibrator connection terminals J and K of an oscillation circuit OSC which uses the electrodes as a vibrator. The output of the oscillation circuit OSC is input to the detector DETa, which outputs a signal corresponding to the amplitude.
The output voltage V _T of DETa is input to the inverting input terminal of an operational amplifier OP whose gain is sufficiently larger than 1.
A DC reference voltage V _R is applied to the non-inverting input terminal of the operational amplifier OP.

In addition, the output of the operational amplifier OP is connected to the ground side electrode D.
It is connected to a piezoelectric actuator E that drives the. First, after inserting the standard vibrating element F _R (hereinafter referred to as the standard vibrating element) between the electrodes, the operational amplifier OP
By adjusting the reference voltage V _R applied to the non-inverting input terminal of the
Through changes in the gap G between F _{and R} , the oscillation strength is set to a size appropriate for testing the characteristics of the vibrating piece. Next, replace the standard vibrating element F _R with an arbitrary vibrating element Fx.

If the thickness tx of the vibrating piece Fx is different from the thickness of the standard piece F _R , the air gap G will change and the oscillation amplitude will change if the electrode spacing is fixed, but in the present invention, the operational amplifier
Since the gain of OP is sufficiently larger than 1, the operational amplifier
The output voltage V of the detector DETa is set to the reference voltage V _R by the piezoelectric actuator E connected to the output of OP.
Since the electrode spacing is automatically adjusted so that it is always equal to , the gap G is kept constant and the oscillation amplitude is also kept at a desired constant width.

(Effects of the Invention) As explained in detail above, the automatic electrode spacing setting device when measuring the characteristics of a vibrating element according to the first invention has the following features:
a pair of electrodes whose spacing can be adjusted by an actuator that expands and contracts in response to an applied signal; a capacitance detector that measures the interelectrode capacitance of the electrodes and generates a signal corresponding to the capacitance value; and an output of the capacitance detector. It is comprised of a circuit that compares the magnitude of the signal with the magnitude of the reference signal and feeds back the signal to the actuator so that the difference becomes zero.

The automatic electrode interval setting device when measuring the characteristics of a vibrating element according to a second invention includes a pair of electrodes whose interval can be adjusted by an actuator that expands and contracts in response to an applied signal, and the electrode into which the vibrating element is inserted. An oscillation circuit used as a vibrator, a detector that generates a signal corresponding to the output amplitude of the oscillation circuit, and a magnitude of the output signal of the detector and a reference signal are compared so that the difference becomes zero. It consists of a circuit that feeds back a signal to the actuator.

Therefore, in any of the inventions, the gap between the measurement electrode and the vibrating piece is automatically controlled to a constant value, allowing smooth measurement.

Furthermore, in the second invention, the electrode spacing is automatically adjusted so that the gap between the vibrating element and the electrode is constant, and the oscillation amplitude is also maintained at a constant amplitude.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an embodiment of an electrode and its support structure of an automatic electrode spacing setting device for measuring characteristics of a vibrating element according to the first and second inventions. FIG. 2 is a block diagram showing an embodiment of an automatic electrode spacing setting device for measuring characteristics of a vibrating element according to the first invention. FIG. 3 is a block diagram showing an embodiment of an apparatus for automatically setting electrode spacing when measuring characteristics of a vibrating element according to the second invention. FIG. 4 is a schematic diagram for explaining the operating principle of the automatic electrode spacing estimation device when measuring the characteristics of a vibrating element according to the present invention. A...Non-grounded electrode, B...Insulator, C...Body, D...Grounded electrode, E...Piezoelectric actuator, G...Gap, DETc...Capacitance detector, DETa
...Amplitude detector, OP...Double input operational amplifier, F _R ,
Fx... vibrating piece.

Claims (1)

[Scope of Claims] 1. In an automatic electrode spacing setting device for eliminating errors caused by variations in the thickness of a vibrating piece when measuring the characteristics of a vibrating piece inserted between electrodes, a pair of electrodes whose spacing can be adjusted by an actuator that expands and contracts, a capacitance detector that measures the interelectrode capacitance of the electrodes and generates a signal corresponding to the capacitance value, and the magnitude and standard of the output signal of the capacitance detector. An automatic electrode spacing setting device for measuring vibrating reed characteristics, comprising a circuit that compares signal magnitudes and feeds back signals to the actuator so that the difference becomes zero. 2. In an automatic electrode spacing setting device for eliminating errors caused by variations in the thickness of the vibrating piece when measuring the characteristics of the vibrating piece inserted between the electrodes, an actuator that expands and contracts according to an applied signal is used. a pair of electrodes whose spacing is adjustable; an oscillation circuit that uses the electrodes into which a vibrating piece is inserted as a vibrator; a detector that generates a signal corresponding to the output amplitude of the oscillation circuit; and an output signal of the detector. An automatic electrode spacing setting device for measuring vibrating reed characteristics, comprising a circuit that compares the magnitude of the reference signal with the magnitude of the reference signal and returns a signal to the actuator so that the difference becomes zero.