JP2002318255A - Surface potential detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface potential detector capable of accurately detecting the potential of an object to be measured even when the distance between the detector and the object is fluctuated. SOLUTION: A potential detecting electrode 11 outputs a potential distance signal s1 including a distance component corresponding to the distance to the object 40 to be measured and a potential component corresponding to the potential of the object 40. A distance detecting electrode 12 outputs a distance signal s2 corresponding to the distance to the object 40. The voltage distance signal s1 and the distance signal s2 are inputted to a signal processing circuit 20 that removes the distance component from the potential distance signal s1 and generates a signal s3 corresponding to the potential of the object 40.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a surface potential detecting device.

[0002]

2. Description of the Related Art This type of surface potential detecting device is, for example,
In a copying machine, a laser beam printer, or the like, it is used as a means for detecting the surface potential of a photosensitive drum, which is a surface to be measured, in a non-contact manner. This type of surface potential detection device obtains an AC signal corresponding to the surface potential of the photosensitive drum by mechanically interrupting the electric field between the detection electrode and the photosensitive drum with a tuning fork. And by processing this AC signal,
The surface potential of the photosensitive drum is detected.

A surface potential detecting device that detects a surface potential in a non-contact manner, when the distance between the detection electrode and the photosensitive drum changes,
An error occurs in the detected value of the surface potential. For this reason, it is necessary to attach the detection electrode to the reference position with high accuracy so that the distance between the detection electrode and the photosensitive drum becomes a predetermined value, which causes difficulty in assembly. Moreover, considering that it is practically impossible to maintain the deviation of the detection electrode from the reference position at zero for a long period of time, the detection electrode and the photosensitive drum cannot effectively avoid a detection error. As a means to avoid the measurement error due to the distance fluctuation between
Japanese Patent No. 6467 discloses a surface potential detecting device in which a high voltage is fed back to the detecting electrode so that an error does not occur in the detected value of the surface potential even when the distance between the detecting electrode and the photosensitive drum fluctuates. ing.

However, this surface potential detecting device has a problem that the circuit configuration is complicated because high voltage needs to be fed back, and large and expensive high withstand voltage parts are required.

Further, the surface potential detecting device disclosed in US Pat. No. 4,797,620 reduces the amplitude of the mechanical vibration of the tuning fork, so that even if the distance between the detecting electrode and the photosensitive drum fluctuates, the surface potential can be reduced. An error is not caused in the detected value of the potential.

However, in this surface potential detecting device, since the amplitude of the mechanical vibration of the tuning fork is reduced, there is a problem that the detection sensitivity is lowered and the S / N ratio cannot be increased.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a surface potential detecting device capable of accurately detecting the potential of a measured object even when the distance to the measured object varies. That is.

Another object of the present invention is to provide a surface potential detecting device capable of detecting the potential of a measured object with high sensitivity.

Still another object of the present invention is to provide a surface potential detecting device having a simple circuit configuration.

[0010] Still another object of the present invention is to reduce the size,
An object of the present invention is to provide a lightweight surface potential detecting device.

Still another object of the present invention is to provide an inexpensive surface potential detecting device that does not use high withstand voltage components.

[0012]

In order to solve the above-mentioned problems, a surface potential detecting device according to the present invention includes a potential detecting electrode, a distance detecting electrode, and a signal processing circuit.

The potential detecting electrode is an electrode for capacitively coupling to the measured object. The potential detection electrode outputs a potential distance signal including a distance component corresponding to the distance to the measured object and a potential component corresponding to the potential of the measured object.

The distance detecting electrode is an electrode for capacitively coupling to the object to be measured. The distance detection electrode outputs a distance signal corresponding to the distance to the measured object.

The signal processing circuit receives the potential distance signal and the distance signal, removes the distance component from the potential distance signal using the distance signal, and corresponds to the potential of the measured object. Generate a signal.

As described above, in the surface potential detecting device according to the present invention, the potential detecting electrode outputs the potential distance signal, and the distance detecting electrode outputs the distance signal. Then, the signal processing circuit uses the distance signal, removes a component corresponding to the distance between the potential detection electrode and the device under test from the potential distance signal, and outputs the signal.
Even when the distance between the surface potential detecting device and the object to be measured fluctuates, the potential of the object to be measured can be accurately detected.

Further, according to the above configuration, it is not necessary to feed back a high voltage, so that the circuit configuration is simplified, and large and expensive high withstand voltage components such as a high voltage generating transformer and a rectifying high withstand voltage are provided. A diode, a high-voltage capacitor for rectification, and a high-voltage transformer for a DC / DC converter are not required. For this reason, it is possible to configure a simple circuit using a small and inexpensive low withstand voltage component, for example, a surface mount type component with a withstand voltage of about several tens of volts. Become.

Further, since the capacitance between the potential detecting electrode and the object to be measured can be vibrated with a large amplitude, the detection sensitivity is increased and the S / N ratio can be increased.

[0019]

FIG. 1 is a diagram schematically showing a configuration of a surface potential detecting device according to the present invention and an object to be measured. In FIG. 1, a surface potential detecting device 10 includes a potential detecting electrode 11
, A distance detection electrode 12, and a signal processing circuit 20.

The potential detecting electrode 11 is an electrode for capacitively coupling to the surface S to be measured of the object 40 to be measured. The potential detection electrode 11 outputs a potential distance signal s1 including a distance component corresponding to a distance between the potential detection electrode 11 and the surface S to be measured and a potential component corresponding to the potential of the surface S to be measured.

The distance detecting electrode 12 is an electrode for capacitively coupling to the surface S to be measured. The distance detection electrode 12 has a distance signal s corresponding to the distance between the distance detection electrode 12 and the surface S to be measured.
2 is output.

The signal processing circuit 20 receives the potential distance signal s1 and the distance signal s2, removes a distance component from the potential distance signal s1 using the distance signal s2, and outputs a signal corresponding to the potential of the surface S to be measured. Generate s3.

As described above, the surface potential detecting device 10 shown in the embodiment is configured such that the potential distance signal s
1 is output, and the distance signal s2 is output from the distance detection electrode 12. Then, the signal processing circuit 20 removes the distance component corresponding to the distance between the potential detection electrode 11 and the surface S to be measured from the potential distance signal s1 using the distance signal s2 and outputs the signal. Even when the distance to the measured surface S fluctuates, the potential of the measured surface S can be accurately detected.

Further, according to the above configuration, it is not necessary to feed back a high voltage, so that the circuit configuration is simplified, and large and expensive high withstand voltage components such as a high voltage generating transformer and a high withstand voltage for rectification are provided. A diode, a high-voltage capacitor for rectification, and a high-voltage transformer for a DC / DC converter are not required. For this reason, it is possible to configure a simple circuit using a small and inexpensive low withstand voltage component, for example, a surface mount type component with a withstand voltage of about several tens of volts. become.

In the surface potential detecting device 10 shown in the embodiment, the capacitance formed by the potential detecting electrode 11 and the surface S to be measured can be vibrated with a large amplitude, so that the detection sensitivity is increased. The S / N ratio can be increased.

The signal processing circuit 20 may be configured as a dedicated circuit using passive circuit elements and active circuit elements, or may be partially or entirely configured by a computer. The shapes of the potential detection electrode 11 and the distance detection electrode 12 are arbitrary, and various modes such as a plate shape, a linear shape, a circular shape, and a rectangular shape can be adopted. Also, the potential detection electrode 1
There is no particular limitation on the structures of the electrode 1 and the distance detection electrode 12 as long as they satisfy predetermined required characteristics. For example, the potential detection electrode 11 may be a chopper type, or may be a type that changes the coupling capacitance by an electronic circuit method. Further, the surface to be measured S is generally the surface of the photoconductor drum, but may be the surface of an electrostatically charged plastic film.

FIG. 2 is a block diagram more specifically showing the structure of the surface potential detecting device and the object to be measured according to the present invention.
FIG. 2 is a circuit diagram showing a part of the configuration of the surface potential detecting device 10 more specifically. In the embodiment shown in FIG. 2, the surface to be measured S is connected to a DC high-voltage power supply _VDC, and the surface potential Vs of the surface to be measured S is, for example, from 0 V to -1000 V with respect to the first reference potential GND1. Change.

The potential detecting electrode 11 is arranged so as to face the measured surface S and is capacitively coupled to the measured surface S in order to measure the surface potential Vs of the measured surface S by non-contact means.
The distance between the potential detection electrode 11 and the surface S to be measured is L1,
The capacitance becomes C1.

The distance detecting electrode 12 is arranged to face the measured surface S so as to measure the distance to the measured surface S by non-contact means, and is capacitively coupled to the measured surface S. In this embodiment, the distance L2 between the distance detection electrode 12 and the surface to be measured S is set to the same value as the distance L1, and the capacitance is C2.

The signal processing circuit 20 includes a potential detecting circuit 21
, A displacement detection circuit 22 and an arithmetic circuit 23. The potential detection circuit 21 includes an impedance conversion circuit 211, a first amplifier 212, a first rectifying / smoothing circuit 213, a first level shift circuit 214, and a modulation signal generation circuit 21.
5 and a mechanical chopper 216.

The displacement detection circuit 22 includes a signal generator 221
A non-inverting amplifier circuit 222, a second amplifier 223,
A second rectifying / smoothing circuit 224, a subtraction circuit 225,
, And a first division circuit 227.

FIG. 3 is a circuit diagram of the signal generator 221.
The signal generator 221 includes an operational amplifier A1 and resistors R1 and R1.
2 and a signal source VG. One end of the signal source VG is grounded to the ground potential GND1. Operational amplifier A1
Has a non-inverting input terminal grounded. Operational amplifier A1
Is connected to the other end of the signal source VG via a resistor R1 and to the output terminal via a resistor R2. The output terminal of the operational amplifier A1 becomes the output terminal of the signal generator 221.

The non-inverting amplifier circuit 222 includes an operational amplifier A2
And a resistor R3. The inverting input terminal of the operational amplifier A2 is connected to the distance detecting electrode 12 and connected to the resistor R3.
Connected to the output terminal. The non-inverting input terminal of the operational amplifier A2 is connected to the output terminal of the signal generator 221. The output terminal of the operational amplifier A2 becomes the output terminal of the non-inverting amplifier circuit 222.

FIGS. 4 and 5 are operation waveform diagrams of the surface potential detecting device 10 shown in FIG. Hereinafter, FIGS. 2, 4, and 5
The operation of the surface potential detecting device 10 will be described with reference to FIG. First, assuming that the dielectric constant is ε ₀ and the effective area is S 2, the capacitance C 2 of the surface potential detecting device 10 is as follows: C 2 = ε ₀ * S 2 / L 2 Here, since only air exists between the distance detection electrode 12 and the surface to be measured S, the dielectric constant ε ₀ is constant, and the effective area S2 is also constant. Therefore, the capacitance C
2 depends only on the change in the distance L2, and the capacitance C2 is
It is proportional to the reciprocal of the distance L2. Since the capacitance C2 changes depending on the change in the distance L2, the signal output from the distance detection electrode 12 is a distance signal s2 corresponding to the distance L2 to the measured surface S.

The signal generator 221 inverts and amplifies the signal input from the signal source VG by the operational amplifier A1, and outputs the signal s2
Outputs 1. FIG. 4A shows the signal s21. Signal s
Reference numeral 21 denotes an AC signal having a constant period and constant amplitude.
The frequency may be a 10 kHz sine wave.

The non-inverting amplifying circuit 222 includes a signal generator 22
The signal s21 input from 1 is amplified and output. Assuming that the frequency of the signal s21 is f, the impedance Xc between the distance detection electrode 12 and the surface S to be measured is Xc = 1 / (2πf * C2), and the amplification factor of the non-inverting amplifier circuit 222 is (Xc + R
3) It becomes / Xc. The voltage Vout output from the output terminal of the non-inverting amplifier circuit 222 can be expressed as Vout = {(Xc + R3) / Xc} * Vm, where Vm is the amplitude of the signal s21.

Since the amplitude Vm and the frequency f of the signal s21 are constant, Vout = {(Xc + R3) / Xc} * Vm = (1 + R3 / Xc) * Vm = (1 + R3 * 2πf * C2) * Vm = (1 + R3 * 2πf * ε ₀ * S2 / L2) * Vm, and the voltage Vout is an AC signal that changes only depending on the change in the distance L2.

The second amplifier 223, the second rectifying / smoothing circuit 224, and the subtraction circuit 225 are grounded to a second reference potential GND2 having the same potential as the signal s21. Second amplifier 2
23 AC-amplifies the AC signal input from the non-inverting amplifier circuit 222 and outputs a signal s22. The signal s22 is shown in FIG.

The second rectifying / smoothing circuit 224 outputs the signal s22
Is rectified and smoothed to output a signal s23. The signal s23 is shown in FIG. This second rectifying and smoothing circuit 224
Because it is grounded to ND2, with reference to GND2,
The signal s22 is rectified and smoothed.

The subtraction circuit 225 converts the signal s23 to the signal s
21 is subtracted and output. The signal output from the subtraction circuit 225 is a DC signal.

The second level shift circuit 226 adjusts the level of the signal input from the subtraction circuit 225 to
b is output. The signal Vb is shown in FIG.

The second level shift circuit 226 may be configured using a non-inverting amplifier circuit whose gain can be adjusted using a variable resistor. In some cases, it can be omitted.

The first division circuit 227 divides the signal Vb by the reference voltage Vref and outputs a displacement signal Vc. The reference voltage Vref is set to the same value as the signal output from the level shift circuit 226 when the distance detection electrode 12 is at the reference position. Therefore, the displacement signal Vc is
The signal corresponds to the displacement from the reference position. Displacement signal V
c is shown in FIG.

On the other hand, the modulation signal generation circuit 215 of the potential detection circuit 21 outputs a signal of a constant frequency, for example, 700 Hz.
The signal of is output. The mechanical chopper 216 is inserted between the measured surface S and the potential detection electrode 11 at the frequency of the signal input from the modulation signal generation circuit 215. When the mechanical chopper 216 is inserted, the permittivity between the measured surface S and the potential detection electrode 11 changes by Δε, and the capacitance C1 changes by ΔC1.

The electric charge ΔQ generated at the potential detecting electrode 11 is
Assuming that the effective area is S1 and the potential difference between the measured surface S and the potential detection electrode 11 is V1, the following equation can be obtained: ΔQ = (ΔεS1 / L1) * V1 = ΔC1 * V1. Therefore, the modulation current i induced in the potential detection electrode 11 can be expressed as follows: i = ΔQ / Δt = (Δε ₀ S1 / L1) * V1 / Δt = ΔC1 * V1 / Δt The modulation current i includes a distance component L1 corresponding to the distance between the potential detection electrode 11 and the surface S to be measured, and a potential component V1 corresponding to the potential of the surface to be measured. Then, the potential detection electrode 11 outputs the modulation current i as the potential distance signal s1.

The impedance conversion circuit 211 converts the potential distance signal s1 input from the potential detection electrode 11 into a voltage signal, and at the same time converts high impedance into low impedance, and outputs a signal that is easy to handle.

The first amplifier 212 amplifies the signal input from the impedance conversion circuit 211 by AC amplification to obtain a signal s.
11 is output. The signal s11 is shown in FIG. The signal s11 is a substantially sine wave signal having the same frequency as the signal output from the modulation signal generation circuit 215, for example, 700 Hz.

The first rectifying / smoothing circuit 213 outputs the signal s11
Is converted into a DC signal, and a signal obtained by multiplying a component corresponding to the potential of the measured surface S by a component proportional to the displacement signal is output.

The first level shift circuit 214 adjusts the DC level of the signal input from the first rectifying / smoothing circuit 213 and outputs a potential displacement signal Va. FIG. 5B shows the potential displacement signal Va.

The first level shift circuit 214 can be configured using a non-inverting amplifier circuit similar to the second level shift circuit 226. In some cases, it can be omitted.

The arithmetic circuit 23 receives the potential displacement signal Va and the displacement signal Vc and divides the displacement signal Vc from the potential displacement signal Va to generate a signal s3. FIG. 5 shows the signal s3.
It is shown in (c). This signal s3 is a signal corresponding to the surface potential Vs of the surface S to be measured.

Next, the surface potential detecting device 10 and the surface to be measured S
A method of removing and outputting a distance component corresponding to the distance L1 between the potential detection electrode 11 and the surface to be measured S when the distance between the potential detection electrode 11 and the surface to be measured S is changed will be described. FIG. 6 shows a relationship between the surface potential Vs of the surface S to be measured and the signal Vb, and FIG.
Between the surface potential Vs and the potential displacement signal Va.

As shown in FIGS. 6 and 7, the signal Vb does not depend on the surface potential Vs but depends on the distance L2. The potential displacement signal Va is proportional to the surface potential Vs and depends on the distance L1.

In this embodiment, since the distance L1 between the measured surface S and the potential detecting electrode 11 is the same as the distance L2 between the measured surface S and the distance detecting electrode 12, the distance L1 (= L
When 2) changes, the capacitances C1 and C2 change by the same ratio. Therefore, the signal V when the distance L1 fluctuates
The change amount of b is proportional to the change amount of the potential displacement signal Va.

Accordingly, when the distances L1 = x1, x2, the potential displacement signals Va = Va (x1), Va (x
2) If the signal Vb = Vb (x1) and Vb (x2), Va (x1) / Va (x2) = Vb (x1) / Vb (x
2) can be expressed as Here, if x1 is defined as a reference position and Vb (x1) is defined as a reference voltage (Vref), Va (x1) = Va (x2) / (Vb (x2) / Vref) = Va (x2) / Vc. .

In the surface potential detecting device 10, the distance L
When 1 is at x2 which fluctuates from the reference position (x1), V
a (x2) and Vb (x2) are detected. Therefore,
By substituting Va (x2) and Vb (x2) into the above equation, the potential of the surface S to be measured can be accurately detected.

As described above, in the signal processing circuit 20 of the surface potential detecting device 10, the displacement detecting circuit 22 outputs the displacement signal Vc = Vb
/ Vref, and the potential detection circuit 21 outputs the potential displacement signal Va. The arithmetic circuit 23 of the signal processing circuit 20 divides the displacement signal Vc from the potential displacement signal Va to obtain a distance L between the potential detection electrode 11 and the surface S to be measured.
1 can be removed, and a signal s3 corresponding to the surface potential Vs of the surface S to be measured can be output.

FIG. 8 shows the detection result of the surface potential Vs.
FIG. 8 is a diagram illustrating a detection result of the surface potential Vs when the reference distance (x1) is 3 mm and the distance L1 fluctuates from the reference distance. In FIG. 8, a signal s3 detected by the surface potential detecting device 10 according to the present invention is shown by a solid line, and a result detected by a conventional high voltage feedback type potential detecting device is shown by a dashed line.

As shown in FIG. 8, the surface potential detecting device 10 according to the present invention has the potential V of the surface S to be measured even when the distance L1 between the surface S to be measured and the potential detecting electrode 11 fluctuates.
s can be accurately detected.

In the surface potential detecting device according to the present invention, the distance L2 between the distance detecting electrode 12 and the surface to be measured S may be different from the distance L1 between the potential detecting electrode 11 and the surface to be measured S.
However, as shown in the embodiment, when these distances have the same value, signal processing becomes easy.

FIG. 9 is a block diagram showing another example of the surface potential detecting device and the object to be measured according to the present invention. In FIG. 9, the same components as those shown in FIG. 2 are denoted by the same reference numerals.

As shown in FIG. 9, the surface potential detecting device shown in the embodiment comprises a potential detecting electrode 11 and a distance detecting electrode 1.
2, a potential detection circuit 31, a displacement detection circuit 22, and an arithmetic circuit 23.

The potential detecting circuit 31 includes an impedance converting circuit 211, a first amplifier 212, a first rectifying / smoothing circuit 213, a first level shift circuit 214, a modulation signal generating circuit 215, and a shield case 316. , A stationary electrode 317, and an impedance generator 318.
The surface to be measured S and the potential detection electrode 11 face each other via the stationary electrode 317, and the shield case 316 forming the capacitance C1 includes a detection window 319, and the potential detection electrode 11
, An impedance conversion circuit 211 and a first amplifier 2
12, a first rectifying / smoothing circuit 213, a first level shift circuit 214, a modulation signal generation circuit 215, an impedance generator 318, and a stationary electrode 317. The shield case 316 is grounded to GND1. The shield case 316 is provided especially for blocking the influence of an external electromagnetic wave on the potential detection operation of the potential detection electrode 11.

The detection window 319 is a window provided between the stationary electrode 317 and the surface S to be measured, and allows an electric field to pass between the stationary electrode 317 and the surface S to be measured. The stationary electrode 317 is arranged between the surface to be measured S and the potential detection electrode 11. The stationary electrode 317 can be made of a conductive material, for example, a metal material.

One end of the impedance generator 318 is electrically connected to the stationary electrode 317, and the other end is electrically connected to the shield case 316.

The modulation signal generating circuit 215 outputs a signal of a constant frequency, for example, a signal of 700 Hz.

The impedance generator 318 periodically changes the impedance of the stationary electrode 317 at the frequency of the signal input from the modulation signal generation circuit 215. The impedance of the stationary electrode 317 is, for example, 7
It changes like a sine wave of 00 Hz.

When the impedance of the stationary electrode 317 changes, the capacitance C1 changes, and the potential detecting electrode 11 outputs the potential distance signal s1. This operation is basically performed by the surface potential detecting device 1 described with reference to FIGS.
There is no difference from the operation of 0.

[0069]

As described above, according to the present invention, the following effects can be obtained. (A) It is possible to provide a surface potential detecting device capable of accurately detecting the potential of a measured object even when the distance to the measured object varies. (B) It is possible to provide a surface potential detecting device capable of detecting the potential of the measured object with high sensitivity. (C) A surface potential detecting device having a simple circuit configuration can be provided. (C) A small and lightweight surface potential detecting device can be provided. (D) It is possible to provide an inexpensive surface potential detection device that does not use high withstand voltage components.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a configuration of a surface potential detecting device and a measured object according to the present invention.

FIG. 2 is a block diagram more specifically showing the configurations of the surface potential detecting device and the device under test according to the present invention.

FIG. 3 is a circuit diagram more specifically showing a part of the configuration of the surface potential detecting device according to the present invention.

FIG. 4 is a diagram showing operation waveforms of the surface potential detecting device according to the present invention.

FIG. 5 is another diagram showing an operation waveform of the surface potential detecting device according to the present invention.

FIG. 6 shows the surface potential Vs of the surface potential detecting device according to the present invention.
FIG. 5 is a diagram showing a relationship between the signal and a signal Vb.

FIG. 7 shows the surface potential Vs of the surface potential detecting device according to the present invention.
FIG. 5 is a diagram showing a relationship between the voltage and a potential displacement signal Va.

FIG. 8 shows the surface potential Vs of the surface potential detecting device according to the present invention.
It is a figure showing the detection result of.

FIG. 9 is a block diagram showing another example of the surface potential detecting device and the measured object according to the present invention.

[Explanation of symbols]

 Reference Signs List 10 surface potential detecting device 11 potential detecting electrode 12 distance detecting electrode 20 signal processing circuit 40 measured object s1 potential distance signal s2 distance signal s3 signal corresponding to potential of measured object

[Procedure amendment]

[Submission date] May 22, 2001 (2001.5.2)
2)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0044

[Correction method] Change

[Correction contents]

On the other hand, the modulation signal generation circuit 215 of the potential detection circuit 21 outputs a signal of a constant frequency, for example, 700 Hz.
The signal of is output. The mechanical chopper 216 is inserted between the measured surface S and the potential detection electrode 11 at the frequency of the signal input from the modulation signal generation circuit 215. When the mechanical chopper 216 is inserted, the dielectric constant between the measured surface S and the potential detection electrode 11 changes by Δε ₀ , and the capacitance C1 changes by ΔC1.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0045

[Correction method] Change

[Correction contents]

The electric charge ΔQ generated at the potential detecting electrode 11 is
Assuming that the effective area is S1 and the potential difference between the measured surface S and the potential detection electrode 11 is V1, the following equation can be obtained: ΔQ = (Δε ₀ S1 / L1) * V1 = ΔC1 * V1. Therefore, the modulation current i induced in the potential detection electrode 11 can be expressed as follows: i = ΔQ / Δt = (Δε ₀ S1 / L1) * V1 / Δt = ΔC1 * V1 / Δt The modulation current i includes a distance component L1 corresponding to the distance between the potential detection electrode 11 and the surface S to be measured, and a potential component V1 corresponding to the potential of the surface to be measured. Then, the potential detection electrode 11 outputs the modulation current i as the potential distance signal s1.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0058

[Correction method] Change

[Correction contents]

FIG. 8 shows the detection result of the surface potential Vs.
FIG. 8 is a diagram showing a detection result of the surface potential Vs when the reference position (x1) is 3 mm and the distance L1 fluctuates from the reference position . In FIG. 8, a signal s3 detected by the surface potential detecting device 10 according to the present invention is shown by a solid line, and a result detected by a conventional high voltage feedback type potential detecting device is shown by a dashed line.

[Procedure amendment 4]

[Document name to be amended] Drawing

[Correction target item name] Fig. 1

[Correction method] Change

[Correction contents]

FIG.

Claims (6)

[Claims] 1. A surface potential detection device including a potential detection electrode, a distance detection electrode, and a signal processing circuit, wherein the potential detection electrode is an electrode for capacitively coupling to an object to be measured, and The potential detection device outputs a potential distance signal including a distance component corresponding to the distance to the measurement object and a potential component corresponding to the potential of the measurement object, and the distance detection electrode is an electrode for capacitively coupling to the measurement object. And outputs a distance signal corresponding to the distance to the object to be measured. The signal processing circuit receives the potential distance signal and the distance signal, and uses the distance signal to calculate the potential signal from the potential distance signal. A surface potential detecting device that removes the distance component and generates a signal corresponding to the potential of the measured object. 2. The surface potential detection device according to claim 1, wherein the signal processing circuit includes a displacement detection circuit, a potential detection circuit, and an arithmetic circuit, and the displacement detection circuit includes the distance. A signal is input, and a displacement signal corresponding to a displacement from a reference position is output. The potential detection circuit receives the potential distance signal and is proportional to a component corresponding to a potential of the measured object and the displacement signal. A potential displacement signal multiplied by the component; and the arithmetic circuit receives the potential displacement signal and the displacement signal, divides the displacement signal from the potential displacement signal, and outputs the potential of the device under test. Surface potential detection device that outputs a signal corresponding to 3. The surface potential detecting device according to claim 2, wherein the displacement detecting circuit includes a signal generator, a non-inverting amplifier, a second amplifier, and a second rectifying / smoothing circuit. , A subtraction circuit, a second level shift circuit, and a first division circuit, wherein the signal generator outputs a signal of a fixed frequency, and the non-inverting amplifier circuit receives an input from the signal generator. Amplifying the output signal at an amplification factor based on the distance signal, and outputting the amplified signal. The second amplifier amplifies and outputs the signal input from the non-inverting amplifier circuit. The second rectifying and smoothing circuit. Rectifies and smoothes the signal input from the second amplifier, and outputs the signal. The subtraction circuit subtracts the signal input from the signal generator from the signal input from the second rectification smoothing circuit. The second level shift circuit outputs the The first division circuit divides the signal inputted from the second level shift circuit by a reference voltage to output a displacement signal Detection device. 4. The surface potential detection device according to claim 2, wherein the potential detection circuit includes an impedance conversion circuit,
, A first rectifying / smoothing circuit, a first level shift circuit, a modulation signal generation circuit, and a mechanical chopper, wherein the modulation signal generation circuit outputs a signal of a fixed frequency, The chopper changes a capacitance between the device under test and the potential detection electrode at a frequency of a signal input from the modulation signal generation circuit, and the impedance conversion circuit converts the potential distance signal into a voltage signal. The first amplifier converts the signal input from the impedance conversion circuit into an AC signal and outputs the amplified signal. The first rectifier and smoothing circuit converts the signal input from the first amplifier into an AC signal. The first level shift circuit adjusts the DC level of the signal input from the first rectifying / smoothing circuit, and outputs the potential displacement signal Surface potential detector that. 5. The surface potential detection device according to claim 2, wherein the potential detection circuit comprises: an impedance conversion circuit;
, A first rectifying / smoothing circuit, a first level shift circuit, a modulation signal generating circuit, a shield case, a stationary electrode, and an impedance generator. The shield case includes a detection window. The potential detection electrode, the impedance conversion circuit, the first amplifier, the first rectifying and smoothing circuit, the first level shift circuit, the modulation signal generation circuit, and the impedance generator. Covering the stationary electrode, the detection window is provided between the stationary electrode and the measured object, the stationary electrode is disposed between the measured object and the potential detection electrode, The modulation signal generation circuit outputs a signal having a constant frequency, and the impedance generator determines an impedance of the stationary electrode at a frequency of a signal input from the modulation signal generation circuit. The impedance conversion circuit converts the potential distance signal into a voltage signal and outputs the voltage signal. The first amplifier performs AC amplification on a signal input from the impedance conversion circuit and outputs the amplified signal. Rectifying and smoothing circuit converts the AC signal input from the first amplifier into a DC signal and outputs the DC signal. The first level shift circuit performs DC conversion on the signal input from the first rectifying and smoothing circuit. A surface potential detecting device for adjusting a level and outputting the potential displacement signal. 6. The surface potential detection device according to claim 1, wherein a distance between the potential detection electrode and the object to be measured, and a distance between the distance detection electrode and the object to be measured. Surface potential detectors having the same distance.