JPH03216563A - Potential measuring method and potential sensor - Google Patents

Abstract

PURPOSE:To remove the effect due to the distance from an object to be measured by operating a potential sensor so that the output potential of a potential measuring apparatus of a synchronous detection system becomes the same potential as the potential setting power supply of the object to be measured. CONSTITUTION:An object 8 to be measured emits a line 10 of electric force by the potential of a set power supply 9 and the emitter of the output transistor 18 of a measuring apparatus is floated along with the case 16 of a potential sensor, a mechanical vibrator 1, a vibrator driving circuit 4, an AC amplifying circuit 5, a synchronous detection circuit 6 and an integration circuit 7 to be held to reference potential. When this reference potential is different from the potential of the power supply 9, the electric field between the object 8 to be measured and a detection electrode part 11 is allowed to pitch by the mechanical vibrator 1 and, therefore, a voltage signal is generated in the electrode 11. The output potential of the integration circuit 7 rises on the basis of the voltage signal to raise the base potential of the transistor 18 and an output current increases and the potential of the emitter rises to become the same potential as the power supply 9.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a potential sensor, and more particularly to a potential measuring method and potential sensor for measuring the amount of charge and charged potential on the surface of an object. [Prior Art] Conventionally, this type of potential measurement method and potential sensor
As shown in Figures (a) and (b), a machine driven by a driving piezoelectric ceramic 3 is housed in a case 16 having a detection hole 15 for introducing electric lines of force 10 emitted from the object to be measured. A board on which a vibrator 1 and a detection electrode section 11 are mounted is housed. As shown in FIG. 3, the mechanical vibrator 1 is caused to vibrate at a natural frequency by the vibrator drive unit 4, and the lines of electric force 10 introduced through the detection hole 15 are repeatedly interrupted and unblocked. The uninterrupted electric lines of force are detected by the detection electrode section 11, and the voltage signal generated at the detection electrode section 11 is amplified and impedance-converted by the pre-amplifier section 12, rectified by the rectifier circuit 13, and further integrated by the smoothing circuit 14. I was getting a DC voltage output signal. [Problems to be Solved by the Invention] The conventional potential measurement method and the potential sensor described above have the same characteristics because when measuring the charged potential of the object to be measured, due to the structure of the sensor, it changes in a fractional manner depending on the measurement distance. When measuring surface potential, the measurement distance was long and the output signal tended to be small. In order to overcome this distance dependence and obtain an accurate surface potential, it was necessary to accurately fix the measurement distance and calibrate using a known potential. Furthermore, when detecting the drum potential of electronic copying machines or laser beam printers, the potential sensor needs to be accurately aligned with the measurement distance during calibration, which requires mounting accuracy, and if the drum is eccentric. The drawback was that the distance between the drum surface and the potential sensor changed as the drum rotated, causing the output to fluctuate and making it impossible to measure the potential accurately. The purpose of the present invention is to supply a high-voltage DC power source from the outside, amplify and integrate the potential difference between the object to be measured and the potential sensor, and control the emitter potential of the output transistor to make it the same potential as the surface potential of the object to be measured. The object of the present invention is to provide a potential measuring method and a potential sensor that do not depend on the distance from the object to be measured by outputting the potential.

[Means to solve the problem]

The potential measuring method and potential sensor of the present invention are as follows:1. The electric lines of force radiated by the object to be measured whose potential has been set by the non-measured object potential setting power supply are periodically interrupted, the uninterrupted lines of electric force are extracted, and the uninterrupted lines of electric force are set at the same period as the line of electric force interruption period. In a potential measuring method in a potential measuring device using an output amplifier that amplifies the detected DC output detected and integrated with a period, the potential measuring device operates with a floating power source different from the power source for setting the potential of the object to be measured, and the potential measuring device It has a function of operating so that the output potential of the device becomes the same potential as the power source for setting the potential of the object to be measured.

2. A line of electric force interrupting section that periodically interrupts electric power radiated from an object to be measured whose potential has been set by a non-measured object potential setting power supply, and a detection unit that receives uninterrupted lines of electric force from the line of electric force interrupting section. an electrode section, a pre-amplifier section for invidus conversion of an alternating current voltage signal generated in the detection electrode section, a substrate on which the electric line of force interrupting section, the detection electrode section and the preamplifier section are mounted, a case for accommodating the substrate; In a potential sensor having a drive unit that excites an electric line of force interrupting unit, an AC amplifying unit that amplifies the output of the preamplifier unit, and an AC amplifying unit that outputs the output of the AC amplifying unit with the same period as the period of exciting the electric line of force interrupting unit. It has a synchronous detection section that performs phase detection and rectification, an integration section that integrates the output of the synchronous detection section, a DC amplification section that is controlled by the output of the integration section, and a floating power supply that operates each of the sections, The detection electrode section is configured to operate so that the alternating current voltage signal generated at the detection electrode section becomes zero.

〔Example〕

Next, the present invention will be explained with reference to the drawings. FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 1 shows an object to be measured 8 having a power source 9 for setting the potential of the object to be measured.
It is equipped with a detection piezoelectric ceramic 2 and a drive piezoelectric ceramic 3 that vibrate at a natural vibration frequency in response to electric lines of force 10 emitted by the oscillator drive circuit 4 and periodic signals generated by the vibrator drive circuit 4. A mechanical vibrator 1 that performs interruption control, a detection electrode section 11 that receives non-interruption electric lines of force, and a detection electrode section 11
Amplifying circuits l2 and 5 amplify the uninterrupted electric lines of force received by a to a predetermined level, and an output signal of the amplifying circuit 5 is a! A synchronous detection circuit 6 that switches and rectifies at the timing of a drive signal of a mechanical vibrator, an integration circuit 7 that integrates the output of the rectified synchronous detection circuit and controls an output transistor 18, a load resistor 19, and an output voltage dividing resistor. 20, and a DC/DC converter 21 whose primary side and secondary side have high withstand voltage.

The measured object 8 emits electric lines of force 10 at the potential E of the non-measured object potential setting power source 9. The mechanical vibrator 1 vibrates at the same frequency due to the detection piezoelectric ceramic 2, the drive piezoelectric ceramic 3, and the vibrator drive circuit 4, and the mechanical vibrator 1 periodically interrupts the electric force lines 10. The uninterrupted electric line of force reaches the detection electrode section 11, becomes a minute alternating current voltage signal, undergoes impedance conversion in the pre-amplifier 12, and is further amplified to a predetermined level by the alternating current amplifier circuit 5. In the synchronous detection circuit 6, the output of the AC amplifier circuit 5 is switched at the timing of the drive signal of the vibrator to flow V. The rectified DC output is integrated by an integrating circuit 7 to control the base potential of the output transistor 18. The collector of the output transistor 18 serves as an output terminal of the potential sensor, and is supplied with high voltage DC power from the outside. Especially when used in a copier or laser beam printer, the high-voltage power supply for corona discharge inside the device is connected. The emitter of the output transistor 18 is
Potential sensor gauge 16. The mechanical resonator 1, the resonator drive circuit 4, the AC booster circuit 5, the synchronous detection circuit 6, and the integration circuit 7 are all held at a floating reference potential E2. Here, the potential E2 of the potential sensor and the potential E of the object to be measured 8
For example, E2 <E. When a potential difference occurs, the electric field between the non-measurable object 8 and the detection electrode section 11 is pitched by the mechanical vibrator 1, so that a voltage signal is generated at the detection electrode 11. Therefore, the output potential of the integrating circuit 7 increases,
Increase the base voltage of the output transistor 18. Therefore, the current flowing through the output transistor 18 increases, the emitter potential E2 rises, and balance is achieved at the point where El=E2. In other words, the potential E2 of the potential sensor is always the potential E! of the object to be measured!
It operates so that the potential is the same as that of the sensor, and an output that is independent of the measurement distance can be obtained. The output transistor 18 uses a high-voltage product, and the output is divided to a desired potential by a voltage dividing resistor 20 as necessary and output.

In this example, the primary power supply is used for the potential sensor. Although a DC/DC converter with an insulated secondary was used, it goes without saying that it is also possible to use a battery or the like.

〔Effect of the invention〕

As explained above, the present invention has a circuit configuration that supplies a high-voltage DC power supply from the outside to the collector of the high-voltage output transistor in the potential sensor, and amplifies and integrates the potential difference between the object to be measured and the potential sensor to output the output transistor. By controlling the emitter potential, it is possible to obtain an output that does not depend on the distance from the object being measured, and because there is no need for a high voltage generator, the effect is that it has high performance while reducing the number of parts and making it possible to downsize. have

[Brief explanation of drawings]

Fig. 1 is a block diagram of an embodiment of the present invention, Fig. 2 (a>
is a cross-sectional view of the plane of a conventional electric line of force detector. FIG. 2(b) is a side cross-sectional view of a conventional electric line of force detector, and FIG. 3 is a block diagram showing an example of a conventional potential sensor. 1... Mechanical vibrator, 2... Piezoelectric ceramic for detection,
3... Piezoelectric ceramic for drive, 4... Vibrator drive circuit, 5... AC amplifier circuit, 6... Synchronous detection circuit, 7
. . . Integrating circuit, 8 . . . Object to be measured, 9 . . . Power source for establishing the potential of the object to be measured, 10 . . . Lines of electric force, 11 . . . ... Rectifier circuit, 14 ... Smoothing circuit, 15 ... Detection hole, 16 ...
Electric force line detection unit case, 17... Board, 18... Output transistor, 19... Load resistor, 20... Voltage dividing resistor, 21... DC/DC converter.

Claims (1)

[Scope of Claims] 1. Periodically interrupting the lines of electric force radiated by the object to be measured whose potential has been set by a potential setting power supply for the non-measured object, extracting the lines of uninterrupted electric force, and extracting the lines of electric force that are not interrupted. In the potential measuring method in a potential measuring device using an output amplifier that amplifies the detected DC output detected and integrated at the same period as the electric force line interruption period, the potential measuring device is a floating power source different from the measured object potential setting power source. A potential measuring method, characterized in that the potential measuring device is operated by a power source so that the output potential of the potential measuring device is the same potential as the potential setting power source for the object to be measured. 2. A line of electric force interrupting section that periodically interrupts lines of electric force radiated from an object to be measured whose potential has been set by a non-measured object potential setting power source, and a line of electric force that is not interrupted by the line of electric force interrupting section. a detection electrode section that receives the detection electrode section, a preamplifier section that converts the AC voltage signal generated at the detection electrode section into impedance, a board on which the electric line of force interrupting section, the detection electrode section, and the preamplifier section are mounted, and a case that houses the board. and a drive section that excites the electric line of force interrupting section, an AC amplifying section that amplifies the output of the preamplifier section, and a period for exciting the electric line of force interrupting section with the output of the AC amplifying section. A synchronous detection section that performs phase detection and rectification in the same period as the synchronous detection section, an integration section that integrates the output of the synchronous detection section, a DC amplification section that is controlled by the output of the integration section, and a floating power supply that operates each of the above sections. 1. A potential sensor comprising: a potential sensor that operates so that an alternating current voltage signal generated at the detection electrode section becomes zero.