JPH0462484A - Vibration type surface electrometer - Google Patents

Abstract

PURPOSE:To quicken the response by arranging plural detection electrodes and vibrators for a body to be measured and making them different in vibration phase. CONSTITUTION:The vibrators 3 and 4 are given out-of-phase vibration by an oscillator 5 and driving circuits 6 and 7 and then out-of-phase AC signals are induced at the detection electrodes 1 and 2. A synchronous detecting circuit 10 is supplied with a synchronizing signal from the oscillator 5 and sends it out to an OR circuit 11, which adds the signal by composition. The high voltage outputted from a high voltage control circuit 12 is supplied to a metallic case body 14 and the vibrators 3 and 4 and outputted as a detection potential. Then the output voltage is controlled in the direction where the deviation electric field between the intensity of an electric field based upon the surface potential of a body to be measured and the intensity of an electric field based upon the output voltage of the high-voltage control circuit becomes 0.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a surface electrometer for measuring the surface potential of an object to be measured, and particularly to a surface electrometer that measures the surface potential of a surface to be measured. This relates to a vibrating surface electrometer that intermittents the electric field between the surface and the surface.

[Prior Art] A conventional AC type non-contact electrometer uses an electric field generated by a potential difference between the surface potential of the object to be measured or the potential to be measured and another potential, that is, the output high voltage in a negative feedback type, to It was made to fluctuate at a fixed period using a vibrating electrode vibrated by a piezoelectric element or a tuning fork, etc., and was converted into an alternating current voltage signal. Then, the AC voltage signal output from this detection electrode is input to the synchronous detection circuit. A synchronous detection circuit, for example, detects the maximum amplitude value of an AC voltage signal in synchronization with the vibration period of a vibrating electrode, holds that value using an integrating circuit, etc. until it is corrected next time, and detects the maximum amplitude value of an AC voltage signal. Outputs a voltage signal according to the amplitude of. The output high voltage is controlled directly or in feedback type devices using this synchronous detection voltage signal, and the surface potential of the object to be measured is measured using the output high voltage.

[Problem to be solved by the invention] In conventional vibrating electrometers, the AC signal obtained by vibration is rectified and processed as the surface potential of the surface to be measured, but this rectified signal has no amplitude and cannot be detected. There was an impossible time. The response speed of an electrometer can be improved by shortening the fluctuation period of the electric field using a vibrating electrode, etc. that generates a current from the electric field.However, if the fluctuation speed of the vibrating electrode, etc. is increased to shorten the fluctuation period, This may cause the fluctuation amplitude to become small or cause noise to occur.

Furthermore, when an AC signal is smoothed, its response becomes slow due to the time constant for smoothing. Therefore, the present invention has developed a vibrating surface electrometer that eliminates the undetectable time and improves the response speed. be.

[Means for Solving the Problems] The present invention includes a detection electrode for measuring the surface potential of an object to be measured, and a vibrator that intermittents an electric field between the detection electrode and the object to be measured at a predetermined period. In a surface electrometer that detects the potential as an alternating current voltage, a plurality of detection electrodes and vibrators are arranged on the surface to be measured, and each vibrator is given vibration with a different phase except for the inverted phase. This is a vibrating surface electrometer characterized in that a detection force is obtained by adding together a plurality of voltage signals each having a different phase output from the electrodes.

[Function] The present invention arranges a plurality of detection electrodes and vibrators on the object to be measured, and makes the phases of vibration different, so that a plurality of detection electrodes and vibrators with different phases are outputted from each detection electrode. By obtaining voltage signals and subjecting them to addition and synthesis processing, a detection signal with good responsiveness can be obtained.

This will be explained with reference to FIGS. 1 and 2. FIG. 1 is a block diagram showing the principle of the present invention, and FIG. 2 is a diagram showing detected waveforms and vibration waveforms obtained thereby. Moreover, this is a case where two detection electrodes A, A' and two vibrators B, B' are respectively arranged. E is the object to be measured.

First, vibrations with a phase difference of 90 degrees are applied to each of the vibrators B and B'. A is the vibration waveform given to B. Then, alternating current signals shown by the solid lines at the top and the second line appear on the detection electrodes A and A', respectively. These are respectively amplified and full-wave rectified by a rectifier circuit C. In this way, the signals with a phase difference of 90 degrees are added and combined by an OR circuit, and the resulting output signal appears as shown in E. This detection signal S is synthesized and added so as to complement the valleys of the output signal waveforms of a and a', so depending on the output signal obtained by a single detection electrode, the potential at the valleys of the signal waveforms may vary. The drawback of not being able to detect fluctuations is eliminated, and responsiveness is improved. That is, with the conventional output signal, the potential fluctuation at the valley could not be detected up to the next peak, and the responsiveness was correspondingly poor.

[Example] An embodiment of the present invention will be described below based on the drawings.

FIG. 3 is a block diagram illustrating the present invention as a feedback non-contact electrometer. Feedback type non-contact electrometers have the advantage that even if there is a change in the distance between the object to be measured and the detection electrode of the contact electrometer, this has little effect on the measured value. In FIG. 3, 1.2 is a detection electrode, and 3.4 is a vibrator. The vibrator 3.4 is given vibrations of different phases by the oscillator 5 and the drive circuit 6.7, thereby inducing alternating current signals of different phases in the detection electrode 1.2. Note that signals of inverted phase (180 degrees) are excluded. 8 is a preamplifier which amplifies the alternating current signal induced in the detection electrode 1.2 and takes it out to the outside.

Further, 9 is an AC amplifier circuit, 10 is a synchronous detection circuit,
A synchronizing signal is given to this synchronous detection circuit 10 from an oscillator 5. The signals output from the synchronous detection circuit 10 are sent to an OR circuit 11 where they are added and combined. A control signal having a magnitude and polarity corresponding to the magnitude and polarity of the deviation electric field is sent out from the OR circuit 11 and is applied to the high voltage control circuit 12 . 13 is a high voltage circuit. The high voltage output from the high voltage control circuit 12 is applied to the metal case body 1
4 and vibrator 3.4, and is output as a detection potential. This feedback type non-contact electrometer uses the strength of the electric field based on the surface potential of the object to be measured and the high voltage control circuit of the non-contact electrometer. Based on the output voltage (deviation from the electric field strength), the output voltage is controlled in the direction in which the electric field becomes zero.

[Effects of the Invention] In the present invention, a plurality of detection electrodes and vibrators are arranged on a surface to be measured, vibrations having different phases except for inverted phase are applied to each vibrator, and vibrations from each detection electrode are applied to each vibrator. Since we decided to obtain the detection output by adding together multiple output voltage signals with different phases, it is possible to detect potential fluctuations at the troughs of the signal waveform depending on the output signal obtained by a single detection electrode. This has the effect of eliminating the previously existing drawbacks and improving responsiveness.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the principle of the present invention, FIG. 2 is a signal waveform diagram thereof, and FIG. 3 is a specific schematic block diagram showing the structure of the present invention. A, A'...detection electrode, B, mover, c, c'...rectifier circuit, circuit, E... object to be measured, a, a signal, b... composite output signal, 1 piezo electrode, 3.4. - Vibrator, 5 6.7... Drive circuit, 8. 9... AC amplifier circuit, 10. Circuit, 11... OR circuit, 12. Control circuit, 13... High voltage Circuit, metal case body. B' ・ ・ ・ Vibration D ・ ・ ・ OR ・Output, 2...Detection...Oscillator, Preamplifier, Synchronous detection, High voltage 14 a′ Output signal waveform Combined pressure signal waveform

Claims (1)

[Claims] In a surface electrometer that detects the potential as an alternating current voltage using a detection electrode for measuring the surface potential of a measured object and a vibrator that intermittents an electric field between the detection electrode and the measured object at a predetermined period. , a plurality of detection electrodes and vibrators are arranged on the surface to be measured, vibrations with different phases are applied to each vibrator except for inverted phase, and a plurality of voltages with different phases are outputted from each detection electrode respectively. A vibrating surface electrometer that performs signal addition processing to obtain a detection output.