JPH02193026A - Automatic electrode interval setting apparatus in measurement of characteristics of vibration piece - Google Patents

Abstract

PURPOSE:To enable smooth measurement with a gap being controlled automatically to a fixed value between an electrode for measurement and a vibration piece by arranging an actuator and a pair of an electrode and a capacitance detector. CONSTITUTION:After a vibration piece FR as reference is inserted between electrodes A and D, a reference voltage VR to be applied to an non-inversion input terminal of an operational amplifier OP is adjusted to set a size of a gap G via an increase or decrease in an output voltage of the amplifier OP and an extension of an actuator E so that it becomes suitable for a characteristic test of the vibration piece FX. Then, in the replacing of the vibration FR for a desired vibration piece FX, when a thickness of the vibration piece FX differs from that of the vibration piece FR, the size of the gap G varies to change a capacitance between electrodes if the electrodes are fixed. But as a gain of the amplifier OP is larger than 1, an interval between the electrodes A and D is controlled with an actuator E connected to an output of the amplifier OP so that a DC voltage VT of a capacitance detector DETC is equal to the voltage VR. Therefore, the capacitance between the electrodes is kept constant to maintain the size of the gap G as well.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to automatic setting of electrode spacing used to measure the characteristics of a single moving piece of crystal resonators, ceramic resonators, etc. in the manufacturing process. Regarding equipment.

(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 or ceramic plate, etc.) that is the main component. Bell Tomioka.

The vibration characteristics are examined by inserting a vibrating piece between opposing electrodes that are arranged with a gap greater than the thickness of the vibrating piece and causing it 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 and measure the size of this void to a value suitable for characteristic testing.

A first object of the invention is to provide a device that detects the interelectrode capacitance in a measurement state and automatically sets the electrode spacing so as to be suitable for the characteristic test.

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 piece and the electrode, in the measurement state, and automatically set the electrode spacing so as to be suitable for testing the characteristics of the vibrating piece. The objective is to provide a device that

(Means for Solving the Problems) In order to achieve the first object, the automatic electrode spacing setting device for measuring the characteristics of a vibrating element according to the present invention is capable of adjusting the spacing using an actuator that expands and contracts in response to an applied signal. a pair of electrodes, a capacitance detector that measures the capacitance between the electrodes and generates a signal corresponding to the capacitance value, and a comparison between the magnitude of the output signal of the capacitance detector and the magnitude of a reference signal, and the difference is zero. The actuator is constructed of a circuit that feeds back a signal to the actuator.

In order to achieve the second object, the automatic electrode interval setting device for measuring the characteristics of a vibrating element according to the present 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 a vibrating element. An oscillation circuit that uses the inserted electrode as a vibrator, a detector that generates a signal corresponding to the output amplitude of the oscillation circuit, and a difference between the magnitude of the output signal of the detector and the magnitude of a reference signal. The actuator is comprised of a circuit that feeds back a signal to the actuator so that the signal 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 the area S (nf) are placed facing each other.

In between, the edge has the same shape as the electrode and the same area S (nf)
.

A vibrating piece Fx with a thickness tx (m) has a gap G of t, a, (m)
has been inserted through.

At this time, if the edge capacitance is ignored, the interelectrode capacitance Cr is given by the following equation.

CE = εo S/ (LA+tx/K)
(F) ・(tlHere, ε. is the dielectric constant of air, approximately 8.854xlO-12 (F/m), and K is the vibrating element F.
It is the dielectric constant of x.

When the area S of the electrode and the vibrating element Fx and the dielectric constant K of the vibrating element Fx are constant, the interelectrode volume ICI= is determined by the size tA of the gap G and the thickness tx of the vibrating element Fx.

Rate of change of CE with respect to tA dCε/dtA and t'
When determining the rate of change of CE with respect to x, dCa/dtx, dcH/d tA=-863/ (iA +tx /K
) 2(F/m)...(2) dca/dtx -1εo S / (K (t A + t x /
K ) 2) (F/m) ...(3)

dcs/dtA is twice as large as dcs/dtx, and when the dielectric constant K of the vibrating element Fx is sufficiently larger than 1, the interelectrode volume 1cE is mainly controlled by the size tA of the air gap G.

Therefore, when the condition K>>1 is satisfied, if the interelectrode capacitance C2 is kept constant by controlling the electrode spacing, the size tA of the gap G can be kept constant.

With reference to FIG. 4, the principle of an automatic electrode spacing 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 tA of the air gap G; when tA is small, the amplitude is large, and when tA is large, the amplitude is small. . Therefore, if the oscillation amplitude is kept constant by controlling the electrode spacing, the size of the air gap G tA
is kept constant.

Figure 1 shows the first invention (capacity monitoring method) and the second invention (capacity monitoring method).
1 is a schematic diagram showing an embodiment of an electrode support structure of an electric bridge spacing setting device using an oscillation amplitude monitoring method.

The non-grounded electrode A is fixed to the main body C via an insulator B.

The ground side electrode facing the non-ground side electrode A is attached to the main body C via a piezoelectric actuator E that expands and contracts depending on the magnitude of the 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 are connected to the non-grounded input terminal H and the grounded input terminal I of the capacitive detector DET, respectively, as shown in FIG.

The piezoelectric actuator E is connected to the output terminal of the dual-input operational amplifier OP.

First, the standard vibrating element FR (hereinafter referred to as standard vibrating element)
is inserted between electrodes A and D, and by adjusting the reference voltage vR applied to the non-inverting input terminal of the operational amplifier OP, the output voltage of the operational amplifier OP is adjusted.
Through the expansion and contraction of , the size tA of the air gap G is set to a size appropriate for the characteristic test of the vibrating element Fx.

When the standard vibrating element FR is replaced with an arbitrary vibrating element Fx, if the thickness tx of the vibrating element Fx is different from the standard vibrating element FR, the size tA of the air gap G changes and the inter-electrode capacitance changes if the electrodes are fixed. Although it varies, in this system the operational amplifier OP
Since the gain of is sufficiently larger than 1, the spacing between the electrodes A and D is controlled by the piezoelectric actuator E connected to the output of the operational amplifier OP so that the DC output voltage VT of the capacitive detector DET is always equal to the reference voltage vR. Therefore, the capacitance between the electrodes 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 when measuring characteristics of a photographing piece 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 above-mentioned invention, and the ground side electrode facing the non-ground side electrode A is connected via a piezoelectric actuator E that expands and contracts depending on the magnitude of the applied voltage. It is attached to main body C.

As shown in FIG. 3, the electrodes A and D into which the vibrating element Fx is inserted are connected to an oscillation circuit O using these as one oscillator.
It is connected to the resonator connection terminals H and I of the SC.

The output of the oscillation circuit OSC is input to a detector DETa that outputs a signal corresponding to the amplitude, and the output voltage vT of the detector DETa is input to the inverting input terminal of an operational amplifier op whose gain is sufficiently larger than 1. A DC reference voltage VR is applied to the non-inverting input terminal of the operational amplifier OP.

Further, the output of the operational amplifier op is connected to a piezoelectric actuator E that drives the ground side electrode.

When there is a gap between the vibrating piece and the electrode, the larger the gap, the smaller the oscillation, and the smaller the gap, the larger the oscillation.

This circuit operates in such a way that the two input terminal voltages of the operational amplifier op are kept equal.

Therefore, first, after inserting a standard vibrating element (hereinafter referred to as standard vibrating element) FR between the electrodes, the output voltage is adjusted by adjusting the reference voltage vR applied to the non-inverting input terminal of the operational amplifier OP. .

As a result, the actuator E expands and contracts to change the gap G between the electrode A and the vibrating piece, and the oscillation intensity is set to a size appropriate for testing the characteristics of the vibrating piece.

Next, the standard vibrating piece FR is replaced with the test vibrating piece Fx.

When the thickness tx of the vibrating piece Fx is different from the standard piece FR, if the electrode spacing is fixed, the air gap G changes and the oscillation amplitude changes, but in this system, the gain of the operational amplifier OP is sufficiently larger than 1, so The gap G is kept constant because the electrode spacing is automatically adjusted by the piezoelectric actuator E connected to the output of the operational amplifier OP so that the output voltage V-r of the detector DETa is always equal to the reference voltage VR. ,
The oscillation amplitude is kept at a desired constant amplitude.

(Effects of the Invention) As described above in detail, the automatic electrode spacing setting device for measuring the characteristics of a vibrating element according to the first invention includes electrodes whose relative spacing can be adjusted by an actuator that expands and contracts in response to an applied signal; A capacitance detector measures the interelectrode capacitance and generates a signal corresponding to the capacitance value, and a signal is sent to the actuator so that the magnitude of the output signal of the capacitance detector and the reference signal are compared and the difference becomes zero. It consists of a circuit that feeds back the

The automatic electrode spacing setting device for measuring characteristics of a vibrating element according to a second invention includes: an oscillation circuit that oscillates with the interelectrode capacitance; a detector that generates a signal corresponding to the output amplitude of the oscillation circuit; The actuator is comprised of a circuit that compares the magnitude of the output signal of the actuator with the magnitude of the reference signal and feeds back the signal to the actuator so that the difference becomes zero.

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

Further, 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 imaging width.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an embodiment of an electrode section and its support structure of an automatic electrode spacing setting device for measuring characteristics of a vibrating element according to the present invention. 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 automatic electrode spacing setting device for 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 setting device when measuring characteristics of a vibrating element according to the present invention. A... Non-grounding side electrode B... Insulator C... Body D... Grounding side electrode E... Piezoelectric actuator DETc... Capacitance detector D E T a... Amplitude detector OP ...Double input operational amplifier FR+ Fx...Resonator element patent applicant Humola Laboratory Co., Ltd. agent
Patent Attorney Hisashi Inoro Figure 1 Figure 2 Figure 3 Procedures] Sansho Figure 4 April 28, 1999

Claims (2)

[Claims] (1) An actuator that expands and contracts in response to an applied signal in an electrode spacing automatic 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. 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. An automatic electrode spacing setting device for measuring vibration cantileverity, comprising a circuit that feeds back a signal to the actuator so that the difference becomes zero. (2) An actuator that expands and contracts in response to an applied signal 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 oscillation circuit that uses the electrode as a vibrator into which a vibrating piece is inserted; a detector that generates a signal corresponding to the output amplitude of the oscillation circuit; and an output signal of the output signal of the detector. An apparatus for automatically setting electrode spacing during vibration cantilever measurement, comprising a circuit that feeds back a signal to the actuator so that the difference between the magnitude and the magnitude of a reference signal becomes zero.