JPH07104019A - Method and device for measuring surface potential - Google Patents

Abstract

PURPOSE:To accurately and easily measure the surface potential with a method and a device for measuring surface potential of a material to be measured with a measuring electrode provided contactless by changing the electrostatic capacity between the material to be measured and the measuring electrode, and detecting two or more of output signals having different output value on the basis of the potential of the measuring electrode, and obtaining the measuring distance on the basis of the output signal to lead out the surface potential. CONSTITUTION:An electrically separated measuring electrode 33 is fluctuated between positions L1, L2 at a different distance from a material 12 to be measured, and chopper electrodes 14 are oscillated so as to be opened and closed to change the electrostatic capacity between the material 12 to be measured and the measuring electrode 33, and the potential of the measuring electrode 33, which is excited in response to the surface potential of the material 12 to be measured and changed with a change of the electrostatic capacity, is detected, and at least two or more of output signal V1, V2 having different output values are detected on the basis of the detecting signal to lead out the surface potential of the material 12 to be measured on the basis of the output signals V1, V2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface potential measuring method and a measuring apparatus for measuring the surface potential of an object to be measured such as an electric conductor or an insulator with a measuring electrode provided in a non-contact manner. The present invention relates to a surface potential measuring method for accurately measuring a surface potential from a distance between a measuring object and a measuring electrode, and a measuring apparatus therefor. For example, it is applied to the control of the charging potential of a photoconductor such as a copying machine, a fax machine, a printing machine, a printer, a plotter, or a developing roller, and its apparatus.

[0002]

2. Description of the Related Art Conventionally, in various fields, it is often necessary to detect and measure the surface potential of an electric conductor, an insulator or the like (object to be measured). Particularly, in the field of electrophotographic copying machines, image quality is improved. For improvement, it is important to accurately detect the surface potential on the photoconductor and control the surface potential. As a means for detecting the surface potential, a non-contact type surface potential measuring means (surface potential sensor) is used so as to prevent the leakage of charges from the object to be measured.

The non-contact type surface potential measuring means can be roughly classified into an electric means and a mechanical means. However, the electric means is expensive because a special functional material is used, and it is charged and adsorbed. Sensitivity decreases due to contamination of the sensor electrode surface due to the polarization and polarization of the insulator used. On the other hand, mechanical means are currently used exclusively in that the sensitivity change due to contamination of the sensor electrode is small and the mechanical means can be manufactured relatively inexpensively.

To measure the surface potential by this mechanical means, the line of electric force incident on the sensor electrode is periodically interrupted to change the amount of charge induced on the sensor electrode to obtain an AC signal. A chopper type and alternating current signal generated in response to the change by periodically changing the capacitance between the measured object and the sensor electrode by periodically vibrating the sensor electrode in the direction of the electric field from the measured object. There is a vibration capacitance type that takes out. Both methods can be made relatively small and stable output values can be obtained, but in both methods, the capacitance between the object to be measured and the sensor electrode is proportional to the reciprocal of the measurement distance between them. Therefore, the obtained output value greatly changes depending on the measurement distance. Therefore, for example, when measuring the surface potential of a moving object such as a photoconductor drum of a copying machine, is the output value change due to the variation of the measurement distance, or is the surface potential of the object measured? There is a problem that it is difficult to determine whether it is due to the distribution and it is difficult to accurately obtain the surface potential of the measured object.

In order to solve such a problem, currently,
Various measurement distance correction type surface potential sensors have been devised, in which the output fluctuation is extremely small even if the measurement distance fluctuates. For example, a surface potential sensor (BTWilliams et.
al.:USPatent 3,852,667 (1974)) has been put to practical use. This surface potential sensor (hereinafter referred to as the first conventional example)
Inputs an output signal to an integral type high voltage generator to generate a high voltage according to the output signal and feeds it back to the sensor probe housing to make the potential of the DUT and the housing the same. The capacitance between them is canceled so that the output value does not depend on the measurement distance.

Further, in Japanese Laid-Open Patent Publication No. 62-118267, a chopper type surface potential sensor is provided with two or more measurement electrodes fixed at a constant distance difference, and an AC output signal between the electrodes is used. By correcting the fluctuation of the measurement distance by
What accurately measures the surface potential of the measured object (hereinafter referred to as the second
A conventional example) is disclosed.

[0007]

However, in the first conventional example, since the high voltage generator is used, the apparatus becomes very expensive, and since the feedback circuit is provided, the apparatus configuration becomes complicated. Further, there is a problem in that the sensor probe has a high voltage and thus requires careful handling.

Further, in the second conventional example, a chopper electrode or the like is provided in front of the sensor electrode for blocking the incident electric force line, and at least two measuring electrodes are provided for correcting the measuring distance. Since it is provided, the device configuration becomes complicated and the size of the entire device becomes large. In addition, the number of parts increases, which causes a cost increase. Further, in the chopper type surface potential sensor, the measurement electrode is always stationary, so if the sensor is used for a long period of time, dust adheres to and accumulates on the measurement electrode due to electrostatic attraction, etc. There is also a problem that the sensitivity is lowered due to the contamination and accurate measurement cannot be performed. This is a particular problem when used in an electrophotographic copying machine that uses toner or the like and has a lot of dust.

Therefore, the invention according to claim 1 changes the electrostatic capacitance between the object to be measured and the measuring electrode to detect two or more output signals having different output values from the potential of the measuring electrode. An object of the present invention is to provide a new measuring distance correction type surface potential measuring method capable of accurately and simply measuring a surface potential by obtaining a measurement distance from an output signal and deriving the surface potential.

According to the second and third aspects of the present invention, by changing the measuring electrode to change the electrostatic capacitance between the object to be measured and the measuring electrode, two or more different output values for obtaining the measuring distance are obtained. It is an object of the present invention to provide a simple method of measuring the surface potential, which is capable of detecting the output signal of 1) and having a small change in sensitivity with time. Further, the invention according to claim 4 changes the capacitance between the object to be measured and the measurement electrode to detect two or more output signals having different output values from the potential of the measurement electrode, and An object of the present invention is to provide an inexpensive surface potential measuring device having a novel measuring distance correcting function of a simple structure capable of accurately measuring the surface potential by obtaining the measuring distance and deriving the surface potential.

According to the fifth and sixth aspects of the present invention, by changing the measurement electrode to change the capacitance between the object to be measured and the measurement electrode, two or more different output values for obtaining the measurement distance are obtained. It is an object of the present invention to provide a surface potential measuring device having a simple structure in which the sensitivity change with time is detected by detecting the output signal of 1. The invention according to claims 7 to 9 provides a compact and cheaper surface potential measuring device by fixing the measuring electrode to the piezoelectric material or the electromagnetic coil so that the measuring electrode can be changed with a simple structure. The purpose is to provide.

Further, according to the invention of claim 10, the voltage for varying and vibrating the measuring electrode is superimposed and applied to the piezoelectric material or the electromagnetic coil on which the measuring electrode is fixed, so that the measuring electrode is moved from the object to be measured. It is an object of the present invention to provide an inexpensive surface potential measuring device having a small size and a simple structure by changing the distance to different positions. Claim 11,
According to the invention described in 12, the measuring electrode is varied in different fluctuation widths by applying a voltage whose magnitude or frequency fluctuates to the piezoelectric material or the electromagnetic coil on which the measuring electrode is fixedly mounted, and thus a small and simple configuration is provided. It is an object of the present invention to provide an inexpensive surface potential measuring device.

[0013]

In order to achieve the above object, the invention according to claim 1 uses a measuring electrode which is arranged at a position spaced apart from the object to be measured by a predetermined distance and electrically independent of the object to be measured. A surface potential measuring method for measuring a surface potential of an object to be measured, wherein the electrostatic capacitance between the object to be measured and a measuring electrode is changed, and the electrostatic potential is induced corresponding to the surface potential of the object to be measured. A potential of the measurement electrode that changes with a change in capacitance is detected, two or more output signals having different output values are detected from the detection signal, and the surface potential of the object to be measured is derived from the output signal. To do.

According to a second aspect of the present invention, as a method of detecting at least two output signals having different output values from the detection signal, the measurement electrode is moved between positions having different distances from the object to be measured. Then, the capacitance between the object to be measured and the measurement electrode is changed, and the output signal at each position is detected. According to a third aspect of the present invention, as a method of detecting at least two output signals having different output values from the detection signal, the measurement electrode is varied with different variation widths, and the measurement electrode and the measurement electrode are varied. It is characterized in that the electrostatic capacitance of is changed and the output signal in each fluctuation range is detected.

According to a fourth aspect of the present invention, there is provided a surface potential measuring device in which a measuring electrode electrically independent of the measured object is arranged at a position spaced apart from the measured object by a predetermined distance. Capacitance changing means for changing the electrostatic capacitance between the measuring body and the measuring electrode, and potential detection for detecting the electric potential of the measuring electrode which is induced corresponding to the surface potential of the measured object and changes with the change of the electrostatic capacitance. Means, output detection means for detecting at least two output signals having different output values from the detection signal, and surface potential deriving means for deriving the surface potential of the object to be measured from the output signal. It is what

According to a fifth aspect of the present invention, the capacitance changing means is provided with electrode changing means for changing the measuring electrode between positions having different distances from the object to be measured, and the measuring electrode is covered by the electrode changing means. The capacitance between the object to be measured and the measuring electrode is changed by varying between positions having different distances from the measuring object, and the output detecting means is provided by the potential detecting means at different positions of the measuring electrode. It is characterized in that two or more output signals having different output values are detected from the detection signal.

According to a sixth aspect of the present invention, the capacitance changing means is provided with electrode changing means for changing the measuring electrode in different changing widths, and the electrode changing means changes the measuring electrode in different changing widths to be measured. By changing the electrostatic capacitance between the body and the measuring electrode, the output detecting means detects two or more output signals having different output values from the detection signals by the potential detecting means in the respective fluctuation widths of the measuring electrode. It is characterized by doing.

According to a seventh aspect of the present invention, the electrode changing means is provided with a piezoelectric material or an electromagnetic coil in which the measuring electrode is fixed, and the piezoelectric material or the electromagnetic coil is driven to change the measuring electrode. It is characterized by that. The invention according to claim 8 is characterized in that a direct current voltage or a voltage which periodically changes is applied as a drive voltage for the piezoelectric material or the electromagnetic coil.

According to a ninth aspect of the present invention, the piezoelectric material is formed in a plate shape, and one end side or both end sides of the piezoelectric material is supported. Further, in the invention according to claim 10, as a driving voltage of the piezoelectric material or the electromagnetic coil, a voltage for varying the measuring electrode between positions at different distances from the object to be measured and the varying measuring electrode are vibrated. The voltage according to claim 11 is applied to the piezoelectric material or the electromagnetic coil, and a voltage of varying magnitude is applied as the driving voltage of the piezoelectric material or the electromagnetic coil. It is characterized in that the electrodes are varied with different variation widths.

Further, the invention according to claim 12 is characterized in that a voltage having a varying frequency is applied as a driving voltage for the piezoelectric material or the electromagnetic coil to vary the measuring electrode with a different variation range. is there.

[0021]

According to the first aspect of the present invention, the capacitance between the object to be measured and the measuring electrode is changed, and the capacitance is induced in response to the surface potential of the object to be measured and changes with the change in the capacitance. The potential of the electrode is detected, and two or more output signals having different output values are detected from the detection signal. Therefore, an accurate measurement distance can be obtained from the output signal, and by correcting the output value from the measurement distance, the surface potential of the measured object is derived from the output value. Therefore, an accurate surface potential can be derived without increasing the number of measurement electrodes.

According to the second aspect of the present invention, the measuring electrode is moved between positions having different distances from the object to be measured, whereby the capacitance between the object to be measured and the measuring electrode is changed, and the measuring electrode is changed. Potentials at different positions are detected, and two or more output signals having different output values are detected from the detection signals.
Therefore, two or more output signals having different output values can be easily detected and contamination of the measurement electrode can be reduced.

According to the third aspect of the invention, the capacitance between the object to be measured and the measurement electrode is changed by varying the measurement electrode with different variation widths, and the potential of the measurement electrode with different variation width is changed. 2 which is detected and has different output value from the detected signal
More than one output signal is detected. Therefore, two or more output signals having different output values can be easily detected and contamination of the measurement electrode can be reduced.

Further, in the invention of claim 4, the capacitance between the object to be measured and the measuring electrode is changed by the capacitance changing means, and the electrostatic capacitance induced by the surface potential of the object to be measured is changed. The potential of the measuring electrode, which changes with the change, is detected by the potential detecting means, and at least two or more output signals having different output values are detected by the output detecting means from the detection signal. Therefore, an accurate measurement distance can be obtained from the output signal, and by correcting the output value from the measurement distance, the surface potential deriving unit derives the surface potential of the measured object from the output value. Therefore, an accurate surface potential can be derived without increasing the number of measurement electrodes.

According to the fifth aspect of the invention, the capacitance changing means is provided with electrode changing means for changing the measuring electrode between positions having different distances from the object to be measured, and the measuring electrode is moved to different positions by the electrode changing means. The capacitance is changed to change the capacitance, and the potential of the measurement electrode is detected by the potential detection means.
Then, the output detection means detects two or more output signals having different output values from the detection signals by the potential detection means at different positions of the measurement electrode. Therefore, two or more output signals having different output values can be easily detected and contamination of the measurement electrode can be reduced.

According to the sixth aspect of the present invention, the capacitance changing means is provided with electrode changing means for changing the measuring electrode by different changing widths, and the electrode changing means changes the measuring electrode by different changing widths to change the electrostatic capacitance. Then, the potential of the measuring electrode is detected by the potential detecting means. Then, the output detection means detects two or more output signals having different output values from the detection signals by the potential detection means in the respective fluctuation widths of the measurement electrodes different from each other. Therefore, two or more output signals having different output values can be easily detected and contamination of the measurement electrode can be reduced.

In the invention according to claim 7, the electrode varying means is provided with a piezoelectric material or an electromagnetic coil having the measuring electrode fixed thereto, and the piezoelectric material or the electromagnetic coil is driven to vary the measuring electrode. Therefore, the measuring electrode can be changed with a simple structure. In the invention according to claim 8, a DC voltage or a cyclically changing voltage is applied as the driving voltage of the piezoelectric material or the electromagnetic coil. Therefore, the piezoelectric material or the electromagnetic coil is driven by a simple driving voltage, and the measurement electrode is changed.

According to the ninth aspect of the invention, the piezoelectric material is formed into a plate shape and one end side or both end sides thereof are supported. Therefore, the piezoelectric material is easily formed, and the measurement electrode is changed by the piezoelectric material. Further, in the invention according to claim 10, a voltage in which a voltage for varying the measuring electrode between positions at different distances from the object to be measured and a varying voltage for vibrating the measuring electrode are applied is applied, The piezoelectric material or the electromagnetic coil is driven. Therefore, the measurement electrode is moved and vibrated between positions having different distances from the object to be measured.

According to the eleventh aspect of the present invention, a voltage having a varying size is applied to the piezoelectric material or the electromagnetic coil to drive the piezoelectric material or the electromagnetic coil. Therefore, the measuring electrodes are changed with different fluctuation ranges. According to the twelfth aspect of the invention, a voltage having a varying frequency is applied to the piezoelectric material or the electromagnetic coil to drive the piezoelectric material or the electromagnetic coil. Therefore, the measuring electrodes are changed with different fluctuation ranges.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. First, the principle of measuring the surface potential by the non-contact type mechanical means will be described from the conventional example shown in FIGS. 23 and 24 in which the measurement electrode is fixed. In FIG. 23, reference numeral 11 is a so-called chopper type surface potential sensor, and the surface potential sensor 11 is a measurement electrode 13 which is arranged so as to face the object to be measured 12 at a predetermined interval and to be electrically independent of each other. A pair of chopper electrodes that are interposed between the measuring body 12 and the measuring electrode 13 and are grounded, and vibrate in parallel with the surface of the measured body 12 to open and close the mutual intervals.
14 and a signal detection unit that detects a change in the charge amount of the measurement electrode 13.
It is composed of 15 and a signal amplification section 16 that amplifies the detection signal.

The surface potential sensor 11 includes a chopper electrode 14
By vibrating in the direction of the arrow shown in
Periodically interrupts the lines of electric force incident on the measurement electrode 13 from
Capacitance C generated between the object to be measured 12 and the measuring electrode 13_OTo
And is induced on the measuring electrode 13 in response to the change.
AC change in the signal detector 15
Signal and the detected signal is increased in the signal amplifier 16.
By increasing the width, the surface potential V of the DUT 12_SAccording to
Output signal V₀Surface potential V which is known in advance _SAnd output
Signal V₀And its surface potential V_STo derive
It has become.

Here, the capacitance C _O is C, where S is the effective area of the measuring electrode 13, L is the facing distance between the object to be measured 12 and the measuring electrode 13, and ε _air is the dielectric constant of _{air. O} = ε _air (S / L) (1), and the value of C _O is changed by changing the effective area S. Then, it is assumed that the change amount C _C of the electrostatic capacitance C _O caused by the periodic mechanical vibration of the chopper electrode 14 is given by C _C = α _O · C _O · sinωt (2) (where t is a change) Time, ω is the angular frequency of vibration, α _O is the rate of change of the capacitance C _O ),
Charge Q _C induced on the measurement electrode 13 by the surface potential V _S with the object to be measured 12 is expressed as _{Q C = C C · V S} ...... (3). Therefore, the current I _C generated in the measuring electrode 13 is expressed by the following formulas (2) and (3): I _C = dQ _C / dt = α _O · ω · C _O · V _s · cos ωt (4) , Thus the output signal V obtained from the measuring electrode
_O is approximately expressed as V _O = A _O · α _O · ω · C _O · V _S · cos ωt (5). However, A _O represents constants related amplification degree.

The output signal V _O is proportional to the surface potential V _S and the electrostatic capacitance C _O of the object to be measured 12 as can be seen from the equation (5), but the electrostatic capacitance C _O is expressed by the equation (1). As can be seen, the facing distance (measurement distance) L between the DUT 12 and the measuring electrode 13
Is proportional to the reciprocal, the output signal V _O which is obtained in proportion to the capacitance C _O, depending on the changes in the measured distance L varies greatly. Therefore, when the measurement distance L fluctuates, there arises a problem that it is difficult to obtain an accurate surface potential V _{S of the} measured object 12 from the output signal V _O.

As the measuring device for measuring the surface potential V _S , a so-called vibration capacitance type surface potential sensor shown in FIG. 24 is used.
There is also 21, but this problem also occurs in the surface potential sensor 21. The surface potential sensor 21 includes the measurement electrode 33 and the measurement object 33.
By periodically oscillating in the vertical direction with respect to the surface of 12, the capacitance C _O generated between the object to be measured 12 and the measuring electrode 33 is periodically changed, and the surface potential V of the object to be measured 12 is changed. making it to obtain an output signal V _O corresponding to the _S, but since measurement principle of varying the capacitance C _O periodically is common, the output signal V obtained in proportion to the capacitance C _{O O} also fluctuates greatly depending on the change of the measurement distance L, and the measured object 12
It is difficult to obtain an accurate surface potential V _S of

Since it is not possible to obtain an accurate surface potential V _S even if the output signal V _O is detected by the measurement electrode 13 fixed in this way, the present invention somehow forms two or more different output values. An output signal is obtained, and the measurement distance L between the object to be measured 12 and the measuring electrode 13 is inverted by using the equation (5) from each output signal without depending on the surface potential V _S of the object to be measured 12. Uniquely obtained, and by correcting the value of any one output signal again from the obtained measurement distance L, it is possible to derive the accurate surface potential V _S of the measured object 12 from the output value. To do.

Next, FIGS. 1 to 6 are views showing a first embodiment of the measuring apparatus for carrying out the surface potential measuring method according to the present invention. , 7 to 9 described above. In this embodiment, the same components as those of the above-described conventional example are designated by the same reference numerals and the description thereof will be omitted. First, the configuration will be described.

In FIGS. 1 and 2, 31 is a chopper type.
The surface potential sensor 31 is a surface potential sensor of
Arranged so as to face each other at a predetermined interval and to be electrically independent
And the vertical direction with respect to the surface of the DUT 12.
The measurement electrode 33, which fluctuates over time, vibrates and opens the space between them.
A pair of chopper electrodes 14 to be closed and a signal detector 15 (potential detection
Output means), the signal amplification section 16, and the signal amplification section 16 amplifies
Output signal V having a different output value from the detected signal₁, V₂
To detect V₁, V₂Detectors 34a, 34b (output detector
Dan) and V₁, V₂Detected by the detectors 34a and 34b
Output signal V₁, V ₂Calculate the measurement distance L from the output signal V₁
Or output signal V₂Is measured and the output value is
Surface potential V_SOutput signal V corresponding to₀Signal correction to get
And a part 35.

As shown in FIG. 3, the measuring electrode 33 of the surface potential sensor 31 is fixed near the center of a piezoelectric material 36 made of, for example, PZT, which is formed in a plate shape. Both ends are fixed to a fixing member 37 and supported in a doubly supported beam shape. The piezoelectric material 36 is driven by applying a voltage by a voltage supply means (not shown), and the measurement electrode 33
Is moved in the vertical direction to move toward and away from the surface of the object to be measured 12 and a position separated from the object to be measured 12 by L ₁ (shown by a solid line in FIG. 1) and a position separated by L ₂ (L ₁ + d). (Shown by the one-dot chain line in FIG. 1). That is, the piezoelectric material 36 constitutes electrode changing means.

The surface potential sensor 31 includes a chopper electrode 14
Oscillates sinusoidally and drives the piezoelectric material 36
Set the measuring electrode 33 from the measured object 12 to L₁And L₂Distance
The capacitance between the measuring electrode 33 and the object to be measured 12
By varying the amount of each of the measuring electrodes 33
Detected by the signal detector 15 at the position and by the signal amplifier 16
V from amplified detection signal₁Whether the detection unit 34a is the object to be measured 12
Distance L₁Output signal V at₁Again V₂Detector
34b is the distance L from the object to be measured 12.₂Output signal V at₂
The same as the above-mentioned principle of measuring the surface potential (chopper type).
The processing is performed to detect. This output signal V₁, V₂of
The output value fluctuates depending on the measurement distance, so it is shown in Fig. 4.
As shown in the figure, it depends on the position of the measuring electrode 33.
Distance to L ₁And L₂Between (interval d) and
By periodically changing the sine wave, as shown in FIG.
Signals having different output values that are wavy are obtained.
That is, the chopper electrode 14 and the piezoelectric material 36 change in capacitance.
Constitutes a means. The vibration of the chopper electrode 14 is positive.
Not limited to chordal waves, rectangular waves, trapezoidal waves, triangular waves, sawtooth waves
Periodic or aperiodic, such as wavy or pulsed
The surface potential can be detected by using vibration.

Then, the signal correction unit 35 uniquely obtains the measurement distance L ₁ by using the obtained output signals V ₁ and V ₂ without depending on the surface potential V _S of the object to be measured 12, and the measurement distance is obtained. The output signal V ₁ or the output signal V ₁ is calculated from the relationship between L ₁ and the output value of the output signal and the surface potential with respect to the known measurement distance.
The output value of ₂ is corrected and the output signal V ₀ corresponding to the surface potential V _S of the measured object 12 is derived from the output value. That is, the signal correction unit 35 constitutes a surface potential deriving unit that derives the surface potential of the measured object from the output signal.

Next, the surface potential measuring method of this embodiment and
The operation will be described focusing on the processing in the signal correction unit 35. Well
Without vibrating the chopper electrode 14 and the measurement electrode 33.
DUT 12 to L₁And L₂Move it to a remote location
C between the measuring electrode 33 and the object to be measured 12_OChange
Then, the detection signal detected by the signal detection unit 15 is sent to the signal amplification unit 16
Is amplified and V is detected from the detected signal.₁The detection unit 34a is the object to be measured.
Distance L from 12₁Output signal V at ₁To V₂Detector
34b is the distance L from the object to be measured 12.₂Output signal V at₂
To detect.

[0042] Here, the case of the chopper type, when the variation of the effective area of the measuring electrode 33 and [Delta] S, the rate of change alpha _O of the capacitance C _O is, α _O = ΔS / S ...... (6) Table If the electrostatic capacitance when the measuring electrode 33 is at the distance L ₁ from the object to be measured 12 is C ₁ and the electrostatic capacitance when it is at the distance L ₂ is C ₂ , the output signals V ₁ , V The output formula of ₂ is
Using equations (1), (5), and (6), V ₁ = A _O · α _O · ω · C ₁ · V _S · cosωt = A _O · ω · ε _air · (ΔS / L ₁ ) · V _S · cos ωt (7) V ₂ = A _O · α _O · ω · C ₂ · V _S · cos ωt = A _O · ω · ε _air · (ΔS / L ₂ ) · V _S · cos ωt …… ( 8) is represented.

Further, since L ₂ is L ₂ = L ₁ + d, the measurement distance L ₁ can be inversely obtained from the equations (7) and (8), and L ₁ is uniquely determined without depending on the surface potential V _S. The output ratio of V ₁ and V ₂ may be obtained from the equations (7) and (8) to obtain the output ratio. For example, when the output ratio is V ₂ / V ₁ , V ₂ / V ₁ is V ₂ / V ₁ = L ₁ / L ₂ = L ₁ / (L ₁ + d) = F (L ₁ ) ... ( 9), and it is expressed by a linear function F with respect to L ₁ (L _1). At this time, the relationship between L ₁ and V ₂ / V ₁ is represented by a relationship curve as shown in FIG. 6A, and if the output ratio V ₂ / V ₁ is obtained, L 1 does not depend on the surface potential V _S. It is possible to uniquely determine ₁ .

Alternatively, if the output ratio is V ₁ / V ₂ , then V
₁ / V _{2 is, V 1 / V 2 = L} 2 / L 1 = (L 1 + d) / L 1 = F (L 1) '...... (10) , and the likewise linear function with respect to L ₁ F ( L ₁ ) ′, and at this time, the relationship between L ₁ and V ₁ / V ₂ is shown in FIG.
It is represented by a relational curve as shown in (b). Similarly, if the output ratio V ₁ / V ₂ is obtained, L ₁ does not depend on the surface potential V _S.
It is possible to uniquely obtain

In this way, the signal correction section 35 outputs the output signal
V₁, V₂Uniquely measured distance L ₁Seeking L₁
And the output value of the output signal for the known measurement distance and
Output signal V₁Or output signal V₂Output value of
Corrected and the surface potential V of the DUT 12_SOf the output value corresponding to
Output signal V₀To get And this output signal V₀Is
Known in advance to the output value of the output signal
Output signal V₀Surface potential corresponding to the output value of
V_SSurface potential V of the object to be measured 12_SDerive exactly
You can

Further, the obtained measured distance L ₁ is output signal V
Which is an output type ₁ or the output signal V ₂ (7) or (8) are substituted into equation by determining the V _S, may be obtained uniquely the surface potential V _S of the object to be measured 12. As described above, according to the present embodiment, the chopper electrode 14 is vibrated so as to be opened and closed, and the measurement electrode 33 is moved by the driving of the piezoelectric material 36 between the measurement distances L ₁ and L ₂ from the object to be measured. DUT 12 and measuring electrode 33
Varying the capacitance C ₀ between the measured distance L _1, L ₂ of the measuring electrode 33 which varies with the change of the induced capacitance C ₀ corresponding to the surface potential V _S of the object to be measured 12 It is possible to detect the output signals V ₁ and V ₂ having different output values from the potential when they are located at the position, and measure the measurement distance L from the output signals V ₁ and V _2.
1 or L ₂ is obtained, and the measured distance L ₁ or L
_{It is possible} to correct the output value of the output signal V ₁ or V ₂ from ₂ and derive the accurate surface potential V _S of the measured object 12 from the output value. Therefore, the output signals V ₁ and V ₂ having different output values can be easily detected without increasing the number of measurement electrodes 33, and the accurate surface potential V _S can be derived. Further, since the measuring electrode 33 is changed, it is possible to suppress the adhesion of dust and the like and reduce the pollution.

In addition, a plate-shaped piezoelectric material 36 that can be easily formed
The measurement electrode is supported only by supporting the piezoelectric element 36 and driving the piezoelectric material 36.
Since 33 is changed, the measurement electrode 33 can be changed with a simple structure that can be easily manufactured, and can be changed only by applying a simple drive voltage. Although not described in detail as another aspect of the present embodiment, as shown in FIG. 7, the measuring electrode 33 is provided on the other end side of the cantilever piezoelectric material 36a whose one end side is fixed to the fixing member 37. It is possible to drive the measurement electrode 33 by fixing it and applying a voltage from the voltage supply means to move the measurement electrode 33 between the positions of the measurement distances L ₁ and L ₂ . Further, as shown in FIG. 8, the measurement electrode is replaced with the piezoelectric material 36.
33 is attached to the magnet portion of the electromagnetic coil 36b, and the time-varying current is passed through the coil to change the magnet in the coil. With the change, the measurement electrode 33 is moved to the positions of the measurement distances L ₁ and L ₂ . It can vary. Although not shown, the measurement electrode is attached to the tip of the tuning fork or the vibrating piece, and the plate-shaped piezoelectric material is attached to them to apply a voltage to the piezoelectric material to change the piezoelectric material. Accordingly, the tuning fork or the vibrating piece may be changed to change the measuring electrode.

Further, in this embodiment, the measuring electrode 33 is varied in a sinusoidal manner (shown in FIG. 5) between the measuring distances L ₁ and L ₂ (interval d) periodically or aperiodically. Output signals V ₁ and V ₂ having different output values are obtained, but the waveforms are not limited to sinusoidal waves, but rectangular waves (FIG. 9), triangular waves (FIG. 10), sawtooth waves (FIG. 11), or trapezoidal waves (FIG. 12)
Alternatively, it may be obtained from signals having different output values that fluctuate.

In this embodiment, two output signals having different output values are detected from one measuring electrode, but the number of output signals from one measuring electrode is not limited to two, and it is necessary to improve the measurement accuracy. In some cases, the surface potential of the object to be measured may be obtained by obtaining two or more output signals from one measuring electrode. In addition, to increase reliability,
You may provide two or more measurement electrodes.

Next, FIGS. 13 to 17 are views showing a second embodiment of the measuring apparatus for carrying out the surface potential measuring method according to the present invention. , 7 to 10 of the invention. In this example,
The same components as those in the above-described embodiment are designated by the same reference numerals and the description thereof will be omitted. First, the configuration will be described. In FIG.
Reference numeral 41 denotes an oscillating capacitance type surface potential sensor, and the surface potential sensor 41 has an electrically shielded shield case 42 having an opening 42a facing the surface of the object to be measured 12 and opening in a predetermined area.
Through the opening 42a of the shield case 42,
A measuring electrode 43 is provided at 12 facing each other at a predetermined interval L so as to be electrically independent, and one end side is fixed to the fixing member 37 in a cantilever shape and the measuring electrode 43 is fixedly provided at the other end side. A piezoelectric element that is driven by being applied with a voltage by a voltage supply means and that fluctuates between the measurement distances L ₁ and L ₂ while periodically vibrating the measurement electrode 43 in the vertical direction with respect to the surface of the object to be measured 12. Material 46
An (electrode changing means) and a signal detecting section 15 are provided, and a signal amplifying section 16, V ₁ , V ₂ detecting sections 34 a and 34 b, and a signal correcting section 35 (not shown) are provided. ing.

The surface potential sensor 41 has a piezoelectric material having a drive voltage waveform shown in FIG. 14 (c) in which a voltage as shown in FIGS. 14 (a) and 14 (b) is superimposed by the voltage supply means. As shown in FIG. 15, the measurement electrodes 43 are oscillated periodically in the vertical direction with respect to the surface of the object to be measured 12 with an amplitude ΔL by driving the electrodes 46 to measure the measurement distances L ₁ , L 2.
_The capacitance between the measurement electrode 43 and the object to be measured 12 is changed by changing between the _two positions. Then, V is detected from the detection signals detected by the signal detection unit 15 and amplified by the signal amplification unit 16 at the respective measurement distances L ₁ and L ₂ of the measurement electrode 43.
₁ , V ₂ detector 34b outputs different output signals V ₁ , V
₂ is detected by performing the same processing as the above-mentioned principle of measuring the surface potential (vibration capacitance type). That is, the piezoelectric material 46 constitutes capacitance changing means.

Next, the surface potential measuring method and operation of this embodiment will be described focusing on the processing in the signal correcting section 35. First, the drive voltage waveform is applied to the piezoelectric material 46 to vibrate at ΔL and the measurement electrode 43 is moved to a position separated from the object to be measured 12 by L ₁ and L ₂ to measure the measurement electrode 43 and the object to be measured.
The capacitance C _o between the sensor 12 and 12 is changed, the detection signal detected by the signal detection unit 15 is amplified by the signal amplification unit 16, and the V ₁ detection unit 34a detects the distance L from the measured object 12 from the detection signal. the output signal V ₁ at ₁ and V ₂ detection section 34b detects the output signal V ₂ at a distance L ₂ from the measured object 12. This V
₁ , V ₂ output signals V ₁ and V detected by the detection units 34a and 34b
_Since the output value of ₂ varies depending on the measurement distance, signals having different output values corresponding to V ₁ and V ₂ shown in FIG. 4 obtained in the first embodiment can be obtained.

Next, in the case of the vibration capacitance type,
Capacitance C between measuring electrode 46_ORate of change α_OIs the measurement
Distance L₁, L₂Against α₁= ΔL / (L₁-ΔL) (11) α₂= ΔL / (L₂-ΔL) ... (12) Here, the measuring electrode 46 is L from the device under test 12₁
C when the distance is₁, L₂When in the distance
The capacitance of C₂Then, each output signal V₁, V ₂Out of
For the force formula, use the formulas (1), (5), (11) and (12)₁= A_O・ Α₁・ Ω ・ C₁・ V_S・ Cosωt = A_O・ ΔL / (L₁-ΔL) ・ ω ・ ε_air・ (S / L₁) ・ V_S・ Cosωt (13) V₂= A_O・ Α₂・ Ω ・ C₂・ V_S・ Cosωt = A_O・ ΔL / (L₂-ΔL) ・ ω ・ ε_air・ (S / L₂) ・ V_S・ Cosωt ・ ・ ・ (14)

Since L ₂ is L ₂ = L ₁ + d, (1
3) and (14), the measurement distance L ₁ can be obtained in reverse. To obtain L ₁ uniquely without depending on the surface potential V _S , V can be obtained from equations (13) and (14). The output ratio of ₁ and V ₂ may be obtained. For example, when the output ratio is V ₂ / V ₁ , V ₂ / V ₁ is V ₂ / V ₁ = L ₁ · (L ₁ −ΔL) / [L ₂ · (L ₂ −ΔL)] = L ₁ · (L _{1 -ΔL)} / _{[(L 1 + d) · (} L 1 + d-ΔL) ] ^{_{= F (L 1 2) ......}} (15) , and the quadratic function with respect to L ₁ F (L ₁ ² ). At this time, the relationship between L ₁ and V ₂ / V ₁ is represented by the relationship curve as shown in FIG. 6A as in the first embodiment, and the surface potential can be calculated by calculating the output ratio V ₂ / V _1. L independent of V _S
It is possible to uniquely determine ₁ .

Alternatively, the output ratio is V₁/ V₂Then V
₁/ V₂Is V₁/ V₂= L₂・ (L₂-ΔL) / [L₁・ (L₁−ΔL)] = (L₁+ D) ・ (L₁+ D-ΔL) / [L₁・ (L₁−ΔL)] = F (L₁ ²) '... (16) and similarly L₁A quadratic function F (L₁ ²)'so
Represented at this time, L₁And V₁/ V₂The relationship with
Similar to the embodiment, it is represented by a relationship curve as shown in FIG.
This is also the output ratio V₁/ V₂Then, the surface potential V
_SL independent of ₁Can be uniquely requested
It

In this way, the signal correction section 35 outputs the output signal
V₁, V₂Uniquely measured distance L ₁Seeking L₁
And the output value of the output signal for the known measurement distance and
Output signal V₁Or output signal V₂Output value of
Corrected and the surface potential V of the DUT 12_SOf the output value corresponding to
Output signal V₀To get And this output signal V₀Is
Known in advance to the output value of the output signal
Output signal V₀Surface potential corresponding to the output value of
V_SSurface potential V of the object to be measured 12_SDerive exactly
You can

In addition, the obtained measurement distance L ₁ is output signal V
Which is an output type ₁ or the output signal V ₂ (13) or (14) substituted into equation by determining the V _S, may be obtained uniquely the surface potential V _S of the object to be measured 12. As described above, according to this embodiment, the drive voltage waveform is applied to the piezoelectric material 46 so that the measurement electrode 43 is moved from the measured object 12 to L
It is possible to obtain the operation and effect of the above-described embodiment by vibrating and changing the position between ₁ and L ₂ apart.

Although not described in detail as another aspect of the present embodiment, the piezoelectric material 36 shown in FIG. 3 of the first embodiment described above.
Alternatively, the drive voltage waveform may be applied to the electromagnetic coil 36b shown in FIG. 8 to cause the measurement electrode 43 to vibrate and be moved to a position separated from the object to be measured 12 by L ₁ and L ₂ . Also, in FIG.
As shown in FIGS. 18 (a) to 18 (f), the measuring electrode 43 is fixed to the fixing member 47 at the center or one end of the piezoelectric materials 44a to 44f supported in a cantilever or cantilever shape. 14, the piezoelectric materials 44a to 44f are attached to the piezoelectric materials 46c to 46f supported by the electromagnetic coils 46a and 46b or the fixing member 37 in a cantilevered beam shape or a cantilevered beam shape, as shown in FIG.
By applying one voltage shown in (b) to the piezoelectric materials 44a to 44f and applying the other voltage to the electromagnetic coils 46a and 46b or the piezoelectric materials 46c to 46f, the measurement electrode 43 is vibrated and the measurement distance L ₁ , L ₂ may be varied. A tuning fork or a vibrating piece to which the plate-shaped piezoelectric material is attached may be used.

In this embodiment, the measuring electrode 43 may be oscillated and changed in a rectangular wave shape, a triangular wave shape, a sawtooth wave shape, a trapezoidal wave shape, or the like as described above.
It goes without saying that two or more output signals may be obtained from one measurement electrode, or two or more measurement electrodes may be provided. Next, FIG. 19 to FIG. 22 are views showing a third embodiment of the measuring apparatus for carrying out the surface potential measuring method according to the present invention. This embodiment is defined in claims 1, 3, 4, 6 to 9, 11, 12
The invention corresponds to any one of the above. In this embodiment, the same components as those in the above-mentioned embodiment are designated by the same reference numerals and the description thereof will be omitted.

First, the structure will be described. In FIG. 19, 51
Is a vibration capacitance type surface potential sensor.
51 is the inside of the shield case 42, the opening of the shield case 42
A measurement electrode 53, which is arranged so as to face the object to be measured 12 via a predetermined distance L via 42a and is electrically independent, and is driven by being applied with a voltage by a voltage supply means to measure the measurement electrode 53. A piezoelectric material 56 (electrode changing means) that periodically changes with a different fluctuation width ΔL ₁ and fluctuation width ΔL ₂ in the vertical direction with respect to the surface of the body 12, and a signal detection unit 15 are provided.
Although not shown, the signal amplifying unit 16, V ₁ and V ₂ detecting unit
34a, 34b, and a signal correction unit 35.

The surface potential sensor 51 is shown in FIG. 21 by driving the piezoelectric material 56 by applying a cyclically varying drive voltage waveform as shown in FIG. As described above, the measurement electrode 53 and the object to be measured 12 are cyclically changed in the vertical direction with respect to the surface of the object to be measured 12 with different fluctuation widths ΔL ₁ and ΔL _2.
Change the capacitance between and. Then, from the detection signals detected by the signal detection unit 15 and amplified by the signal amplification unit 16 with the fluctuation widths ΔL ₁ and ΔL ₂ of the measurement electrodes 53, V ₁ ,
The V ₂ detecting unit 34b detects the output signals V ₁ and V ₂ having different output values by performing the same processing as the above-described principle of measuring the surface potential (vibration capacitance type). That is, the piezoelectric material 56 constitutes capacitance changing means. It should be noted that by applying to the piezoelectric material 56 a voltage whose frequency fluctuates periodically as shown in FIG.
_It may be varied by ₁ and the variation width ΔL ₂ .

Next, the surface potential measuring method of this embodiment and
The operation will be described focusing on the processing in the signal correction unit 35. Well
Without applying the drive voltage waveform to the piezoelectric material 56.
53 different fluctuation range ΔL₁And fluctuation range ΔL₂Fluctuate with
The capacitance C between the measuring electrode 53 and the object to be measured 12_OChange
Then, the detection signal detected by the signal detection unit 15 is sent to the signal amplification unit 16
Is amplified and V is detected from the detected signal.₁The detection unit 34a has a fluctuation range Δ
L₁Output signal V at₁Again V ₂The detector 34b is changed
Width ΔL₂Output signal V at₂To detect. this
V₁, V₂Output signal V detected by the detectors 34a and 34b₁,
V₂Is the variation width ΔL of the fluctuation of the measuring electrode 53.₁, Δ
L₂4 which is obtained in the above-mentioned first embodiment because it is almost proportional to
V shown in₁, V₂Different output values corresponding to
Signal is obtained.

Next, in the case of the vibration capacitance type, the rate of change α _O of the electrostatic capacitance C _O between the object to be measured 12 and the measurement electrode 56 is β ₁ = ΔL ₁ with respect to the measurement distances L ₁ and L _2. / (L-ΔL ₁ ) (17) β ₂ = ΔL ₂ / (L-ΔL ₂ ) (18) Therefore, the output formulas of the output signals V ₁ and V ₂ are as follows using the formulas (1), (5), (17) and (18): V ₁ = A _O · β ₁ · ω · C _O · V _S・ cosωt = A _O・ ΔL ₁ / (L-ΔL ₁ ) ・ ω ・ ε _air・ (S / L) ・ V _S・ cosωt …… (19) V ₂ = A _O・ β ₂・ ω ・ C _{O · V S · cosωt = a O} · ΔL 2 / (L-ΔL 2) · ω · ε air · (S / L) is represented as _{· V S · cosωt ...... (20} ). In order to find L uniquely without depending on the surface potential V _S , the output ratio of V ₁ and V ₂ may be found from the equations (19) and (20). For example, when the output ratio is V ₂ / V ₁ , V ₂ / V ₁ is V ₂ / V ₁ = ΔL ₂ · (L-ΔL ₁ ) / [ΔL ₁ · (L-ΔL ₂ )] = F (L) becomes (21) and is represented by a linear function F (L) with respect to L. At this time, the relationship between L and V ₂ / V ₁ is represented by a relationship curve as shown in FIG. 22 (a), and if the output ratio V ₂ / V ₁ is obtained, L is not dependent on the surface potential V _S. It is possible to obtain a unique request.

Alternatively, set the output ratio to V₁/ V₂Then V
₁/ V₂Is V₁/ V₂= ΔL₁・ (L-ΔL₂) / [ΔL₂・ (L-ΔL₁)] = F (L) '... (22), which is similarly expressed by a linear function F (L)' with respect to L.
L and V₁/ V₂The relationship with is as shown in Figure 22 (b)
It is represented by a curve. Therefore, this is also the output ratio V ₁/ V
₂Then, the surface potential V_SUniquely L without depending on
It becomes possible to ask.

In this way, the signal correction section 35 outputs the output signal
V₁, V₂Uniquely measured distance L ₁Seeking L₁
And the output value of the output signal for the known measurement distance and
Output signal V₁Or output signal V₂Output value of
Corrected and the surface potential V of the DUT 12_SOf the output value corresponding to
Output signal V₀To get And this output signal V₀Is
Known in advance to the output value of the output signal
Output signal V₀Surface potential corresponding to the output value of
V_SSurface potential V of the object to be measured 12_SDerive exactly
You can

The obtained measurement distance L ₁ is output signal V
Which is an output type ₁ or the output signal V ₂ (19) or (20) substituted into equation by determining the V _S, may be obtained uniquely the surface potential V _S of the object to be measured 12. As described above, according to the present embodiment, the drive voltage waveform is applied to the piezoelectric material 56 so that the measurement electrode 53 has a different fluctuation width ΔL.
_By varying with ₁ and the variation width ΔL ₂ , it is possible to obtain the operational effects of the above-described embodiment.

Although not described in detail as another aspect of the present embodiment, the piezoelectric material 36 shown in FIG. 3 of the first embodiment described above is used.
Or the variation width ΔL ₁ and the variation width ΔL of the measurement electrode by applying the drive voltage waveform to the electromagnetic coil 36b shown in FIG.
It may be changed by ₂ . The vibration width may be changed by applying a drive voltage waveform in which the magnitude and frequency of the voltage are changed at the same time, or the fluctuation width may be changed aperiodically. Alternatively, a tuning fork or a vibrating piece to which a plate-shaped piezoelectric material is attached may be used.

In this embodiment, the measuring electrode 53 may be oscillated and varied in a rectangular wave shape, a triangular wave shape, a sawtooth wave shape, a trapezoidal wave shape, or the like as described above.
It goes without saying that two or more output signals may be obtained from one measurement electrode, or two or more measurement electrodes may be provided.

[0069]

According to the first aspect of the invention, the capacitance between the object to be measured and the measurement electrode is changed, and at least the output value is changed from the potential of the measurement electrode which changes with the change in the capacitance. Since two or more different output signals are detected, it is possible to derive an accurate surface potential that does not depend on changes in the measurement distance from one measurement electrode. As a result, it is possible to provide an accurate and simple surface potential measuring method.

According to the second aspect of the present invention, the capacitance between the measuring electrodes is changed by varying the measuring electrodes between the positions having different distances from the object to be measured, and the measuring electrodes are respectively moved at different positions. Since the output signal is detected from the potential of, it is possible to easily detect two or more output signals having different output values. Further, it is possible to reduce the contamination of the measurement electrode and reduce the change in sensitivity with time.

According to the third aspect of the invention, the capacitance between the object to be measured and the measurement electrode is changed by varying the measurement electrode with different variation widths, and the measurement electrode with different variation widths is changed. Since the output signal is detected from each potential, it is possible to easily detect two or more output signals having different output values. Further, it is possible to reduce the contamination of the measurement electrode and reduce the change in sensitivity with time.

According to the fourth aspect of the invention, the capacitance between the object to be measured and the measurement electrode is changed, and at least the output value is changed from the potential of the measurement electrode which changes with the change in the capacitance. Since two or more different output signals are detected, it is possible to derive an accurate surface potential independent of the measurement distance without increasing the number of measurement electrodes. As a result, it is possible to provide an inexpensive surface potential measuring device with a simple configuration capable of accurately measuring the surface potential.

According to the fifth aspect of the present invention, the capacitance between the measuring electrodes is varied by varying the measuring electrodes between the positions having different distances from the object to be measured, and the measuring electrodes are respectively varied at different positions. Since the output signal is detected from the potential of, the two or more output signals having different output values can be detected with a simple configuration. Further, it is possible to reduce the contamination of the measurement electrode and reduce the change in sensitivity with time.

According to the sixth aspect of the invention, the capacitance between the object to be measured and the measurement electrode is changed by varying the measurement electrode with different variation widths, and the measurement electrode with different variation widths is changed. Since the output signal is detected from each potential, two or more output signals having different output values can be detected with a simple configuration. Further, it is possible to reduce the contamination of the measurement electrode and reduce the change in sensitivity with time.

According to the invention of claims 7 to 9, the measuring electrode is fixed to the piezoelectric material or the electromagnetic coil and the piezoelectric material or the electromagnetic coil is driven. Therefore, the measuring electrode is changed with a simple structure. It is possible to change the measurement electrode with a simple driving voltage by applying a DC voltage or a voltage that changes periodically. Moreover, the structure can be further simplified by forming the piezoelectric material in a plate shape. Therefore, the size can be reduced and the cost can be reduced.

Further, according to the invention of claim 10,
Since the piezoelectric material or the electromagnetic coil is driven by applying a voltage that fluctuates and oscillates the piezoelectric material or the electromagnetic coil on which the measuring electrode is fixed to drive the piezoelectric material or the electromagnetic coil, it is possible to easily measure the distance from the measured object. It can be varied and vibrated between different positions. Therefore, a smaller and simpler configuration can be achieved.

According to the eleventh and twelfth aspects of the present invention, a voltage varying in size or frequency is applied to the piezoelectric material or the electromagnetic coil on which the measuring electrode is fixed to drive the measuring electrode. It can be changed in different fluctuation ranges. Therefore, a compact and simple structure can be obtained.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing a first embodiment of a measuring apparatus for carrying out a surface potential measuring method according to the present invention.

FIG. 2 is a block diagram showing an overall configuration thereof.

FIG. 3 is a configuration diagram showing a main part thereof.

FIG. 4 is a diagram showing respective output values at different positions of the detection signal of the measurement electrode.

FIG. 5 is a diagram showing detection signals having different output values which are changed in a sine wave shape.

FIG. 6 is a diagram showing the relationship between the measured distance and the output ratio, and FIGS. 6A and 6B are diagrams when the way of taking the output ratio is changed.

FIG. 7 is a configuration diagram showing a main part of another aspect.

FIG. 8 is a configuration diagram showing a main part of another aspect different from FIG. 7.

FIG. 9 is a diagram showing a detection signal in the case of being changed into a rectangular wave shape different from that of FIG.

FIG. 10 is a diagram showing a detection signal in the case of being changed in a triangular wave shape different from that of FIG. 5.

11 is a diagram showing a detection signal in the case of being changed in a sawtooth shape different from that in FIG.

FIG. 12 is a diagram showing a detection signal in the case of being changed into a trapezoidal wave shape different from that in FIG. 5.

FIG. 13 is an overall configuration diagram showing a second embodiment of the measuring apparatus for carrying out the surface potential measuring method according to the present invention.

14A and 14B are diagrams showing drive voltage waveforms applied to the piezoelectric material, where FIG. 14A is a voltage waveform for varying the measurement electrode, and FIG. 14B is a voltage waveform for varying the measurement electrode.
(C) is a figure which shows the voltage waveform which superimposed the voltage shown to (a) and (b).

FIG. 15 is an explanatory diagram illustrating a variation of the measurement electrode.

16A and 16B are diagrams showing another aspect, and FIGS. 16A and 16B are examples of a combination of a piezoelectric material and an electromagnetic coil.

17A and 17B are views showing another embodiment, and FIGS. 17C and 17D are examples in which piezoelectric materials are combined and the supporting method is changed.

18 is a diagram showing another aspect different from FIG. 17,
(E) and (f) are examples of combinations of piezoelectric materials and different support methods.

FIG. 19 is an overall configuration diagram showing a third embodiment of the measuring apparatus for implementing the surface potential measuring method according to the present invention.

FIG. 20 is a diagram showing a drive voltage waveform applied to the piezoelectric material, where (a) shows a voltage waveform when the magnitude of the voltage is changed, and (b) shows a voltage waveform when the frequency is changed. FIG.

FIG. 21 is an explanatory diagram illustrating a variation of the measurement electrode.

FIG. 22 is a diagram showing the relationship between the measured distance and the output ratio, and (a) and (b) are diagrams when the way of taking the output ratio is changed.

FIG. 23 is a conceptual diagram of an overall configuration of a chopper type surface potential sensor for explaining a principle of measuring a chopper type surface potential of a conventional example.

FIG. 24 is a conceptual diagram of the overall configuration of a vibrating surface potential sensor for explaining the principle of measuring a vibrating surface potential of a conventional example.

[Explanation of symbols]

12 object to be measured 14 chopper electrode (capacitance changing means) 15 signal detecting section (potential detecting section) 16 signal amplifying section 31, 41, 51 surface potential sensor 33, 43, 53 measuring electrode 34a V ₁ detecting section (output detecting section) 34b V ₂ detecting section (output detecting means) 35 Signal correcting section (surface potential deriving means) 36, 36a, 44a to 44f, 46, 46c to 46f, 56 Piezoelectric material (electrode changing means, capacity changing means) 36b, 46a, 46b Electromagnetic coil (electrode changing means, capacity changing means) V ₀ , V ₁ , V ₂ output signals L, L ₁ , L ₂ measurement distance ΔL ₁ , ΔL ₂ fluctuation range

Claims (12)

[Claims] 1. A surface potential measuring method for measuring a surface potential of an object to be measured by a measuring electrode which is arranged at a position spaced apart from the object to be measured and is electrically independent of the object to be measured, said method comprising: By changing the capacitance between the object to be measured and the measurement electrode,
The potential of the measurement electrode that is induced in response to the surface potential of the object to be measured and that changes with a change in the capacitance is detected, and at least two or more output signals having different output values are detected from the detection signal to detect the potential. A surface potential measuring method, which comprises deriving a surface potential of an object to be measured from an output signal. 2. A method of detecting at least two output signals having different output values from the detection signal, by varying the measurement electrode between positions having different distances from the object to be measured. Change the capacitance between the measurement electrode,
The surface potential measuring method according to claim 1, wherein an output signal at each position is detected. 3. A method of detecting two or more output signals having different output values from the detection signal, by varying the measuring electrode with different fluctuation widths to measure electrostatic capacitance between the object to be measured and the measuring electrode. 2. The surface potential measuring method according to claim 1, wherein the capacitance is changed and the output signal in each fluctuation range is detected. 4. A surface potential measuring device in which a measuring electrode electrically independent of the object to be measured is arranged at a position spaced apart from the object to be measured by a predetermined distance, and between the object to be measured and the measuring electrode. Capacitance changing means for changing the electrostatic capacitance of the measuring object, potential detecting means for detecting the potential of the measuring electrode induced corresponding to the surface potential of the object to be measured and changing with the change of the electrostatic capacitance, and at least the detection signal from the detection signal. A surface potential measuring device comprising: output detecting means for detecting two or more output signals having different output values; and surface potential deriving means for deriving the surface potential of the object to be measured from the output signals. 5. The capacitance changing means is provided with electrode changing means for changing the measuring electrode between positions having different distances from the object to be measured, and the electrode changing means changes the distance of the measuring electrode from the object to be measured. By varying between different positions to change the capacitance between the object to be measured and the measurement electrode, the output detection means, the output value from the detection signal by the potential detection means at each different position of the measurement electrode Different 2
5. Detecting more than one output signal.
The surface potential measuring device described. 6. The capacitance changing means is provided with electrode changing means for changing the measuring electrode in different changing widths, and the measuring electrode is changed in different changing widths by the electrode changing means so that the measured object and the measuring electrode are changed. The capacitance between the output electrodes is changed, and the output detection means detects two or more output signals having different output values from the detection signals by the potential detection means in the different fluctuation widths of the measurement electrodes. The surface potential measuring device according to claim 4. 7. The electrode changing means is provided with a piezoelectric material or an electromagnetic coil on which the measuring electrode is fixed, and the piezoelectric material or the electromagnetic coil is driven to change the measuring electrode. Alternatively, the surface potential measuring device according to item 6. 8. The surface potential measuring device according to claim 7, wherein a DC voltage or a voltage which changes periodically is applied as a driving voltage for the piezoelectric material or the electromagnetic coil. 9. The surface potential measuring device according to claim 7, wherein the piezoelectric material is formed in a plate shape, and one end side or both end sides of the piezoelectric material are supported. 10. A driving voltage for the piezoelectric material or the electromagnetic coil, wherein a voltage for varying the measuring electrode between positions at different distances from the object to be measured and a varying voltage for vibrating the measuring electrode are superimposed. The surface potential measuring device according to claim 7, wherein the applied voltage is applied. 11. The surface potential measuring device according to claim 7, wherein a voltage of varying magnitude is applied as a driving voltage of the piezoelectric material or the electromagnetic coil to vary the measuring electrode in different varying widths. . 12. The surface potential measuring device according to claim 7, wherein a voltage having a varying frequency is applied as a driving voltage for the piezoelectric material or the electromagnetic coil to vary the measuring electrode with a different variation range.