JPH08146065A - Method and device for measuring surface potential - Google Patents

Abstract

PURPOSE: To provide a method for accurately measuring the surface potential of a body to be measured, reducing the measurement error of the surface potential of the body to be measured. CONSTITUTION: At the output part of a signal detection part 25, a signal amplification part 26, V1 and V2 detection parts 27a and 27b, and a signal compensation part 20, signal noises outputted from the output parts are eliminated by a plurality of noise filters 28-32 and at the same time, a measurement electrode 23 is greatly fluctuated between positions with different distances from a body 22 to be measured, thus detecting output signals at the positions of the measurement electrode 23.

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

Further, in the second conventional example, a chopper electrode or the like is provided in front of the sensor electrode for shutting off the line of electric force incident thereon, 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.

To solve these various problems, the present applicant has previously filed Japanese Patent Application No. 246652/1993, which is shown in FIG. In FIG. 30, P
A measuring electrode 1 is fixedly mounted on a single piezoelectric material such as ZT ceramic, and the measuring electrode 1 is moved between measuring distances L ₁ and L ₂ with respect to a measured object such as a conductor or an insulator. By changing the capacitance between the object to be measured and the measuring electrode 1, and the measurement distance L of the measuring electrode 1 which is induced corresponding to the surface potential of the object to be measured and changes with the change in the capacitance.
After detecting the potentials at the positions of ₁ and L ₂ by the signal detecting unit 2, the signal amplifying unit 3 amplifies the potential, and the output signals V ₁ and V having different output values from the signal amplified by the signal amplifying unit 3
_{After 2} were detected by V ₁ signal detection unit 4 and V ₂ signal detecting unit 5 obtains the measured distance L ₁ or L _2, from the output signal V _1, V ₂ by the signal correcting section 6, the measured distance L ₁
Alternatively, the output value of the output signal V ₁ or V ₂ is corrected from L _2, and the accurate surface potential V _S of the measured object is derived from the output value V ₀ .

With this configuration, output signals V ₁ and V ₂ having different output values can be easily detected without increasing the number of measurement electrodes 1, and an accurate surface potential V _S can be derived. Further, since the measuring electrode 1 is changed, it is possible to suppress the adhesion of dust or the like and reduce the contamination.

[0010]

However, in the one described in Japanese Patent Application No. 5-246652 filed earlier, the surface potential of the object to be measured, such as an electric conductor or an insulator, is made non-contact. Although the measurement electrode 1 provided can perform accurate and easy measurement with an extremely simple configuration, the signal detection unit 2 detects the potential induced in the measurement electrode 1 corresponding to the surface potential of the measured object. In this case, since the obtained potential detection signal includes the noise signal and is output, it is difficult to detect the accurate surface potential of the measured object.

Further, when the output signals are detected by the V ₁ signal detection section 4 and the V ₂ signal detection section 5, or by the signal correction section 6, the output signal V ₁ and the output signal V ₂ are output depending on the surface potential V _S. Since noise is included in each output signal even when the value V ₀ is calculated and output, it is difficult to detect the surface potential of the DUT with high accuracy without error, and there is still room for improvement. is there.

Further, in the one described in Japanese Patent Application No. 246652/1993, in order to detect the surface potential with high accuracy, the fluctuation range of the measuring electrode 1 is increased so that the measured object and the measuring electrode 1 are It is necessary to greatly change the electrostatic capacitance between the two, but in order to increase the electrostatic capacitance, the measuring electrode 1 is attached to a piezoelectric material single body such as PZT ceramic, and the measuring electrode 1 is a piezoelectric material single body such as PZT ceramic. Is fluctuated by. However, when the DUT 1 is changed by a single piezoelectric material such as PZT ceramic as described above,
The piezoelectric material may be cracked or broken by mechanical stress, and polarization may be broken when an overvoltage is applied to the piezoelectric material.

Further, in the one described in Japanese Patent Application No. 246652/1993, in order to increase the capacitance, a measuring electrode is attached to the tip of a tuning fork or a vibrating piece, and a plate-shaped piezoelectric element is attached to them. Although the one with the material attached is also applied, in such a case, it is difficult to increase the fluctuation range of the measuring electrode itself, and when the mechanical resonance point is used to increase the fluctuation range. However, since the fluctuation of the measurement electrode 1 is often caused by mechanical vibration such as tuning fork or vibrating piece, the fluctuation range is affected by the surrounding environment (temperature, humidity, etc.) and becomes unstable, and the measurement accuracy is sufficiently improved. There is still room for improvement.

Therefore, the invention according to claim 1 eliminates the noise generated in the potential detection signal of the measurement electrode, the two or more output signals and the signal for guiding the surface potential of the object to be measured, thereby removing the object to be measured. It is an object of the present invention to provide a surface potential measuring method capable of reducing the measurement error of the surface potential and measuring the surface potential of an object to be measured with high accuracy.

According to the second and third aspects of the present invention, the measuring electrode is largely changed to largely change the electrostatic capacitance between the object to be measured and the measuring electrode, so that the accuracy of measuring the surface potential of the object to be measured is significantly improved. It is an object of the present invention to provide a surface potential measuring method that can be improved. According to a fourth aspect of the present invention, a noise filter for removing noise is provided at each output part of the potential detecting means, the output detecting means, and the surface potential deriving means, so that the measurement error of the surface potential of the object to be measured is simple. The invention according to claim 5, which aims at providing an inexpensive surface potential measuring device capable of reducing the surface potential of the object to be measured with high accuracy, and detecting the output potential. By providing a noise filter that passes or amplifies only a necessary signal among the signals output from the means and the surface potential deriving means, it is possible to respond to the signals output from the potential detecting means, the output detecting means, and the surface potential deriving means. Noise can be removed effectively and the surface potential of the object to be measured can be measured with higher accuracy. The invention according to claims 6 and 7 for the purpose of providing the object to be measured has a simple structure by largely changing the measurement electrode to largely change the capacitance between the object to be measured and the measurement electrode. An object of the present invention is to provide a surface potential measuring device capable of significantly improving the accuracy of measuring the body surface potential.

According to an eighth aspect of the invention, the measurement electrode is largely changed while preventing the piezoelectric material from being cracked and broken during the change, such as the one in which the measurement electrode is fixedly attached to the piezoelectric material such as PZT ceramic. An object of the present invention is to provide a surface potential measuring device capable of significantly improving the measurement accuracy of the surface potential of a measured object with a simple structure.

It is an object of the present invention to provide a small-sized and inexpensive surface potential measuring device which can greatly change the measuring electrode. An object of the invention of claim 11 is to provide a small-sized and inexpensive surface potential measuring device capable of largely varying the measuring electrode between positions having different distances from the object to be measured.

It is an object of the present invention to provide a small-sized and inexpensive surface potential measuring device capable of varying the measuring electrode greatly with varying widths of different sizes.

[0019]

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. Detecting the potential of the measurement electrode that changes with the change in capacitance, then detecting at least two output signals having different output values from the detection signal, and then deriving the surface potential of the measured object from the output signal. In the surface potential measuring method described above, at least one or more of noises generated in the potential detection signal of the measurement electrode, two or more output signals and a signal for guiding the surface potential of the object to be measured are removed. .

To achieve the above object, the invention according to claim 2 is the invention according to claim 1, wherein the measuring electrode is used as a method for detecting two or more output signals having different output values from the detection signal. It is characterized in that the capacitance between the object to be measured and the measuring electrode is largely changed by largely changing between positions having different distances from the object to be measured, and the output signal at each position is detected. .

To achieve the above object, the invention according to claim 3 is the invention according to claim 1, wherein the measuring electrode is used as a method for detecting at least two output signals having different output values from the detection signal. It is characterized in that the capacitance between the object to be measured and the measurement electrode is largely changed by making a large change in a change range having a different size, and the output signal in each change range is detected.

In order to achieve the above object, the invention according to claim 4 is a surface potential measuring device in which a measuring electrode electrically independent of the object to be measured is arranged at a position spaced from the object to be measured by a predetermined distance. The capacitance changing means for changing the electrostatic capacitance between the object to be measured and the measuring electrode, and the electric potential of the measuring electrode induced corresponding to the surface potential of the object to be measured and changing with the change in the electrostatic capacity. A potential detecting means for detecting, an output detecting means for detecting at least two output signals having different output values from the detection signal, and a surface potential deriving means for deriving a surface potential of the object to be measured from the output signal. The surface potential measuring device is characterized in that a noise filter for removing noise is provided in at least one of the output parts of the potential detecting means, the output detecting means and the surface potential deriving means.

To achieve the above object, in the invention according to claim 5, in the invention according to claim 4, the noise filter outputs signals output from the potential detecting means, the output detecting means and the surface potential deriving means. The feature is that only the necessary signals are passed or amplified. In order to achieve the above object, the invention according to claim 6 is the electrode according to claim 4 or 5, wherein the capacitance changing means causes the measuring electrode to largely fluctuate between positions having different distances from the object to be measured. The output detecting means is provided with a changing means, and the electrode changing means greatly changes the measuring electrode between positions at different distances from the object to be measured to largely change the electrostatic capacitance between the object to be measured and the measuring electrode. It is characterized in that the means detects two or more output signals having different output values from the detection signals by the potential detecting means at different positions of the measurement electrode.

In order to achieve the above-mentioned object, the invention according to claim 7 is the invention according to claim 4 or 5, wherein the capacitance changing means causes the measuring electrode to change greatly in a changing range of different sizes. Is provided, the measuring electrode is greatly changed by the electrode changing means in a changing range of different sizes, and the capacitance between the object to be measured and the measuring electrode is greatly changed, and the output detecting means changes the measuring electrode. It is characterized in that two or more output signals having different output values are detected from the detection signals by the potential detecting means in each fluctuation range.

In order to achieve the above object, the invention according to claim 8 is the invention according to claim 6 or 7, wherein a unimorph type or bimorph type piezoelectric actuator in which a measuring electrode is fixed to the electrode changing means, or A piezo actuator with a magnifying mechanism or an electromagnetic coil, and a unimorph type or bimorph type piezoelectric actuator with a fixed measuring electrode, or a laminated piezoelectric actuator with a magnifying mechanism, or an electromagnetic coil is used to drive the measuring electrode. Is characterized by a large fluctuation.

To achieve the above object, the invention according to claim 9 is the same as the invention according to claim 8, wherein a unimorph type or bimorph type piezoelectric actuator in which a measuring electrode is fixedly mounted, or a laminated type piezoelectric actuator with an enlarging mechanism,
Alternatively, it is characterized in that a DC voltage or a voltage that changes periodically is applied as a drive voltage of the electromagnetic coil.

To achieve the above object, the invention of claim 10 is characterized in that, in the invention of claim 8 or 9, one end side or both end sides of the unimorph type or bimorph type piezoelectric actuator is supported. . In order to achieve the above object, the invention according to claim 11 is the invention according to claim 8, wherein the unimorph type or bimorph type piezoelectric actuator, the laminated piezoelectric actuator with a magnifying mechanism, or the electromagnetic coil is used as a driving voltage. A voltage in which a first voltage that causes the measurement electrode to fluctuate between positions having different distances from the measurement target and a second voltage that vibrates the measurement electrode that fluctuates between the different positions are superimposed are applied. It is characterized by doing.

In order to achieve the above-mentioned object, the invention according to claim 12 is the invention according to claim 8, characterized in that a unimorph type or bimorph type piezoelectric actuator in which a measuring electrode is fixedly mounted, or a laminated type piezoelectric actuator with an enlarging mechanism,
Alternatively, it is characterized in that a voltage of varying magnitude is applied as the driving voltage of the electromagnetic coil. In order to achieve the above-mentioned object, the invention according to claim 13 is the invention according to claim 8, wherein the unimorph type or bimorph type piezoelectric actuator, the laminated piezoelectric actuator with a magnifying mechanism, or the electromagnetic coil drive frequency is It is characterized in that a varying voltage of is applied.

[0029]

According to the first aspect of the present invention, the electrostatic capacitance between the object to be measured and the measuring electrode is changed, and it is induced corresponding to the surface potential of the object to be measured and changes with the change in the electrostatic capacity. The potential of the measurement electrode is detected, and then two or more output signals having different output values are detected from the detection signal, and then the surface potential of the measured object is derived from the output 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.

Furthermore, the potential detection signal of the measuring electrode, 2
Since at least one or more of the noise generated in the one or more output signals and the signal for guiding the surface potential of the measured object is removed, it is possible to reduce the measurement error of the surface potential of the measured object. The surface potential of the measurement object can be measured with high accuracy. According to a second aspect of the present invention, as a method of detecting two or more output signals having different output values from the detection signal, the measurement electrode is largely changed between positions having different distances from the object to be measured. Capacitance between the body and the measurement electrode is greatly changed, and the output signal at each position is detected. Therefore, the output difference between two or more output signals can be increased, and the accuracy of measuring the surface potential of the measured object can be significantly improved.

According to the 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 greatly changed in a variation range having different sizes, and the measurement target and the object to be measured are changed. The electrostatic capacitance between the measuring electrode and the measuring electrode is largely changed, and the output signal in each fluctuation range is detected. Therefore, the output difference between two or more output signals can be increased, and the accuracy of measuring the surface potential of the measured object can be significantly improved.

According to a fourth aspect of the present invention, there is provided capacitance changing means for changing the electrostatic capacitance between the object to be measured and the measuring electrode, and a change in the electrostatic capacitance induced corresponding to the surface potential of the object to be measured. A potential detection unit that detects the potential of the measurement electrode that changes with the output, an output detection unit that detects at least two output signals having different output values from the detection signal, and derive the surface potential of the object to be measured from the output signal. Surface potential deriving means. 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 object to be measured is derived from the output value. Therefore, an accurate surface potential can be derived with a simple and inexpensive structure without increasing the number of measurement electrodes.

At least one of the output sections of the potential detecting means, the output detecting means, and the surface potential deriving means.
Since one or more noise filters for removing noise are provided, the measurement error of the surface potential of the measured object can be reduced, and the surface potential of the measured object can be measured with high accuracy. In the invention according to claim 5, the noise filter is
Since only necessary signals among the signals output from the potential detecting means, the output detecting means and the surface potential deriving means are passed or amplified, the capacitance changing means, the potential detecting means and the surface potential deriving means are Only the noise corresponding to the output signal can be effectively removed, and the surface potential of the measured object can be measured with higher accuracy with an inexpensive structure.

According to a sixth aspect of the invention, the capacitance changing means is provided with electrode changing means for changing the measuring electrode largely between positions having different distances from the object to be measured, and the electrode changing means measures the measuring electrode. The capacitance between the object to be measured and the measurement electrode is greatly changed by largely changing between the positions at different distances from the body, and the output detection means is configured to detect the potential detection means at different positions of the measurement electrode. Two or more output signals having different output values are detected from the detection signal. Therefore, the output difference between two or more output signals can be increased, and the accuracy of measuring the surface potential of the measured object can be significantly improved.

According to the seventh aspect of the present invention, the capacitance changing means is provided with electrode changing means for changing the measuring electrode to a large extent in different widths, and the measuring electrode is changed in the different width by the electrode changing means. The capacitance between the object to be measured and the measurement electrode is largely changed, and the output detection means has two different output values from the detection signals by the potential detection means in different fluctuation widths of the measurement electrode which are different from each other by a predetermined value or more. The above output signals are detected. Therefore, the output difference between two or more output signals can be increased, and the accuracy of measuring the surface potential of the measured object can be significantly improved.

According to an eighth aspect of the present invention, the electrode changing means is provided with a unimorph type or bimorph type piezoelectric actuator in which the measuring electrode is fixedly mounted, a laminated piezoelectric actuator with an enlarging mechanism, or an electromagnetic coil. By driving a unimorph type or bimorph type piezoelectric actuator in which is fixed, or a laminated type piezoelectric actuator with a magnifying mechanism, or an electromagnetic coil, the measurement electrode is largely changed. Therefore, it is possible to prevent the piezoelectric material from being cracked and broken at the time of change like the conventional electrode changing means in which the measuring electrode is fixedly mounted on the piezoelectric material such as PZT ceramic, and to greatly change the measuring electrode. Therefore, the accuracy of measuring the surface potential of the measured object can be significantly improved with a simple configuration.

According to a ninth aspect of the present invention, a unimorph type or bimorph type piezoelectric actuator in which a measuring electrode is fixedly mounted, a laminated type piezoelectric actuator with a magnifying mechanism, or a DC voltage or a periodical voltage is used as a driving voltage for an electromagnetic coil. Since the changing voltage is applied, the measuring electrode can be largely changed by the small electrode changing means.

According to a tenth aspect of the invention, a unimorph type,
Alternatively, since one end side or both end sides of the bimorph type piezoelectric actuator are supported, the measurement electrode can be largely changed by a small electrode changing means. In the invention of claim 11, unimorph type, or bimorph type piezoelectric actuator, or a laminated piezoelectric actuator with a magnifying mechanism, or as a driving voltage of an electromagnetic coil, the measurement electrode between the position of different distance from the object to be measured. Since the superimposed voltage of the fluctuating first voltage and the second voltage that vibrates the measured electrode that fluctuates between the different positions is applied, the measurement electrode has a different distance from the measured object. It fluctuates greatly between positions and vibrates.

According to a twelfth aspect of the invention, a unimorph type,
Alternatively, since the bimorph type piezoelectric actuator, the laminated type piezoelectric actuator with a magnifying mechanism, or the electromagnetic coil is applied with a voltage of varying size, the measuring electrode fluctuates greatly in a varying range of different sizes. In the invention according to claim 13, the unimorph type or bimorph type piezoelectric actuator, or the laminated piezoelectric actuator with a magnifying mechanism, or as a driving voltage of the electromagnetic coil, a voltage of which frequency fluctuates is applied. Fluctuates greatly with fluctuation widths of different sizes.

[0040]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. 1 to 14 are views showing a first embodiment of the measuring apparatus for carrying out the surface potential measuring method according to the present invention. This embodiment is any one of claims 1, 2, 4 to 6 and 8 to 10. It corresponds to the invention described in.

First, the structure will be described. In FIG. 1 and FIG. 2, 21 is a chopper type surface potential sensor, and the surface potential sensor 21 is arranged so as to face the object 22 to be measured at a predetermined interval so as to be electrically independent and also to be measured 22. A measurement electrode 23 that periodically fluctuates in the vertical direction with respect to the surface of
A pair of chopper electrodes 24 that vibrate to open and close the space between them
, Signal detector 25 (potential detector), and signal amplifier 26
And V ₁ and V ₂ detection units 27a and 27b (output detection means) that detect output signals V ₁ and V ₂ having different output values from the detection signal amplified by the signal amplification unit 26, and V ₁ and V ₂ detection Part 27
An output signal corresponding to the surface potential V _S of the object 22 to be measured from the output values V ₁ and V ₂ detected by a and 27b to obtain the measurement distance L and correcting the output signal V ₁ or the output signal V _2. The signal correction unit 20 for obtaining V ₀ , the signal detection unit 25, the signal amplification unit 26, the V ₁ and V ₂ detection units 27 a and 27 _b , and the output unit of the signal correction unit 20 are provided and output from these output units. Multiple noise filters 28-32 to remove noise in the signal
It consists of and.

The noise filters 28 to 32 are configured by using only passive elements such as resistors, capacitors and coils, or by a combination of active elements and passive elements such as OP amplifiers. A filter or the like may be used. In addition, as the type, low range (low signal frequency)
Use the pass type, high band (high signal frequency) pass type, band (required center frequency) pass type, etc.
5, it suffices to select ones according to the signals output from the signal amplifying unit 26, V ₁ , V ₂ detecting units 27a and 27b and the signal correcting unit 20.

As shown in FIG. 3, the measuring electrode 23 of the surface potential sensor 21 is fixed near the center of a pair of piezoelectric materials 33a, 33b made of, for example, PZT. A metal leaf spring 34 is sandwiched between the pair of piezoelectric materials 33a and 33b, and both ends are fixed to a fixing member 35 to form a bimorph type piezoelectric actuator supported in a doubly supported beam shape. There is.

The piezoelectric material 33 is driven by applying a cyclically changing voltage by a voltage supply means (not shown), and the measurement electrode 23 is moved vertically to the surface of the object 22 to be measured. To the measured object 22 to L
₁ distance apart (shown by the solid line in Figure 1) and L ₂ (L
₁ + d) Separated position (shown by the alternate long and short dash line in Fig. 1)
It fluctuates between. That is, the bimorph type piezoelectric actuator constitutes the electrode changing means.

The surface potential sensor 21 is a chopper electrode.
24 is vibrated in a sinusoidal shape, and the piezoelectric material 33 is driven to move the measurement electrode 23 to a position separated from the object to be measured 22 by L ₁ and L ₂ to generate electrostatic between the measurement electrode 23 and the object to be measured 22. By changing the capacitance, the V ₁ detection unit 27a detects the object to be measured from the detection signal detected by the signal detection unit 25 at each position of the measurement electrode 23 and amplified by the signal amplification unit 26.
The output signal V ₁ at a distance L ₁ from 22 and the output signal V ₂ at a distance L ₂ from the object 22 to be measured are detected by the V ₂ detection unit 27b.

Since the output values of the output signals V ₁ and V ₂ vary depending on the measuring distance, as shown in FIG. 4, they differ depending on the position of the measuring electrode 23, and the measuring distances are L ₁ and L 2.
_By periodically or aperiodically varying between ₂ and (interval d), signals having different output values which are sinusoidally varied as shown in FIG. 5 are obtained. That is, the chopper electrode 24 and the bimorph type piezoelectric actuator constitute a capacitance changing means. It should be noted that the vibration of the chopper electrode 24 is not limited to the sine wave, and the surface potential can be detected by using periodic or aperiodic vibration such as rectangular wave, trapezoidal wave, triangular wave, sawtooth wave, or pulse wave. Is.

Then, the signal correction section 20 uniquely obtains the measurement distance L ₁ using the obtained output signals V ₁ and V ₂ without depending on the surface potential V _S of the object 22 to be measured, and the measurement distance L ₁ 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 object 22 to be measured is derived from the output value. That is, the signal correction unit 20 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 will be described. First, a conventional method of measuring the surface potential when the measurement electrode 23 is fixed will be briefly described. Chopper electrode 24
By vibrating in the direction of the arrow shown in FIG. 1, the lines of electric force that are incident on the measurement electrode 23 from the object to be measured 22 are periodically interrupted, and electrostatic charges generated between the object to be measured 22 and the measuring electrode 23 are generated. The capacitance C _O is changed, and a minute change in the amount of electric charge induced on the measurement electrode 23 according to the change is detected as an AC signal in the signal detection unit 15, and the detection signal is amplified in the signal amplification unit 26. As a result, an output signal V ₀ corresponding to the surface potential V _S of the object 22 to be measured is obtained, and the surface potential V _S which is known in advance is obtained.
The surface potential V _S is derived from the relationship between the output signal V ₀ and the output signal V ₀ .

[0049] Here, the capacitance C _O is the effective area of the measuring electrode 23 S, the opposing distance between the measuring electrode 13 and the object to be measured 22 L, when the dielectric constant of air and εair, C _O = Ε _air (S / L) (1), the effective area S is changed and the value of C _O is changed. 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 24 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 measuring electrode 24 by the surface potential V _S with the object to be measured 22 is expressed as _{Q C = C C · V S} ...... (3). Therefore, the current I _C generated in the measuring electrode 23 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 VO obtained from the measuring electrode
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.

In this embodiment, the measuring electrode 23 is placed at a distance L ₁
And L ₂ are varied to detect the surface potential of the object 22 to be measured. That is, the chopper electrode 24 is vibrated and the measuring electrode 23 is moved to a position separated from the object to be measured 22 by L ₁ and L ₂ to change the electrostatic capacitance C _O between the measuring electrode 23 and the object to be measured 22. The signal amplification section 26 amplifies the detection signal detected by the signal detection section 25, and the V ₁ detection section 27a detects the distance L from the measured object 22 from the detection signal.
The output signal V ₁ at _1, V ₂ detecting section 27b is the object to be measured
The output signal V ₂ at a distance L ₂ from 12 is detected. Here, in the case of the chopper type, when the change amount of the effective area of the measurement electrode 23 is ΔS, the change rate α _O of the electrostatic capacitance C _O is expressed as α _O = ΔS / S (6) and measured. when the capacitance when a certain electrostatic capacity when the electrode 23 is at a distance from the object to be measured 22 of L ₁ at a distance of C _1, L ₂ and C _2, the output of each output signal V _1, V ₂ ceremony,
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 ₀ · α _O · ω · C ₂ · V _S · cos ωt = A _O · ω · ε _air · (ΔS / L ₂ ) · V _S · cos ωt …… ( 8) is represented.

Since L ₂ is L ₂ = L ₁ + d, the measurement distance L ₁ can be obtained in reverse 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 unit 20 outputs the output signal
V₁ , V₂ Uniquely measured distance L ₁ Seeking L₁ 
And the output value of the output signal for the known measurement distance and
Output signal V₁Or output signal V₂ Output value of
Corrected, surface potential V of DUT 22_S Of the output value corresponding to
Output signal V₀ Get. And this output signal V₀ Is
Known in advance to the output value of the output signal
Output signal V₀ Surface potential corresponding to the output value of
V_S Surface potential V of the object to be measured 22_S Derive exactly
Can be

The obtained measurement 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 22. On the other hand, the signal detector 25, the signal amplifier 26, V ₁ , V ₂
The signals output from the detection units 27a and 27b and the output unit of the signal correction unit 20 include some noise, and this noise causes a measurement error when measuring the surface potential of the DUT 22.

In this embodiment, the signal detector 25 and the signal amplifier
26, V ₁ , V ₂ detection units 27 a, 27 _b and a signal correction unit 20 are provided with noise filters 28 to 32 at their output units, and the noise filters 28 to 32 pass or amplify necessary signals among the output signals, Remove noise. For example, the measuring electrode
The measurement error of the V ₁ signal output from 23 is caused by the noise filter 2
Assuming that it is improved to 10% or less by 8, 29 and 30, if a signal indicating the calculation result of V ₂ / V ₁ is output by the signal correction unit 20 at the subsequent stage, it is a noise filter.
By 32, it will be further improved to 1% or less, and as a result, the detection accuracy of the measurement distance uniquely obtained from the value of V ₂ / V ₁ will be improved by about 10 times, and more accurate measurement distance can be obtained. You can

Therefore, the detection accuracy of the surface potential of the object to be measured 22 detected by using the obtained measurement distance is also improved by about 10 times, and the surface potential of the object to be measured 22 can be detected with higher accuracy. You can On the other hand, in this embodiment, the piezoelectric element
When the measurement electrode 23 is changed by 33, it is changed greatly. This is because the accuracy of measuring the surface potential can be improved by increasing the slope of the relationship curve in FIGS. 6A and 6B when detecting the surface potential of the object 22 to be measured.

That is, by increasing the output difference between the output signals V ₁ and V ₂ and increasing the slope of the curve, the detection accuracy of the measurement distance L ₁ is improved, and the surface obtained from the detected measurement distance is increased. Since the measurement accuracy of the potential is improved, in order to make the difference between the outputs of the output signals V ₁ and V ₂ large, as is clear from the above equations (9) and (10), the fluctuation range of the measurement electrode 23, That is, the distance d between the measurement distances L ₁ and L ₂ is increased.

FIG. 7 shows the relationship between the distance d between L ₁ and L ₂ and the detection accuracy of the measurement distance L ₁ when the measurement distance L = 3 mm and the measurement error of V ₂ / V ₁ ± 0, 3%. This is the result of calculation.
As shown in the figure, as the distance d between L ₁ and L ₂ is increased from 0.2 mm to 1 mm, the detection accuracy of the measurement distance L ₁ is improved. Therefore, for example, if d is set to 0.6 mm, it becomes possible to detect the measurement distance L ₁ with an accuracy of ± 2% or less, and the surface potential of the object to be measured 22 obtained from the detected measurement distance is also ±. It is possible to detect with an accuracy of 2% or less. In order to further improve the measurement accuracy of the surface potential, the size of d should be increased.

As described above, according to the present embodiment, the chopper power is supplied.
The electrode 24 is vibrated so as to open and close, and the piezoelectric material 33a,
By driving 33b, the measuring electrode 23 is moved to the measuring distance from the measured object.
Distance L ₁ , L₂ By varying between
Capacitance C between 22 and measuring electrode 23₀ Change the
Surface potential V of body 22_S Is induced corresponding to the capacitance C ₀ 
Measurement distance L of the measurement electrode 23 that changes with changes in₁ , L₂ 
Output signal V whose output value differs from the potential when it is located at
₁ , V₂ Can be detected and its output signal V ₁ , V
₂ To measurement distance L₁ , Or L₂ Seek the measurement distance
Distance L₁ Or L ₂ Output signal V from₁ Or V₂ Out of
Correct the force value and use the output value to measure the accurate surface of the DUT 22.
Potential V_S Can be derived. Therefore, the measurement voltage
Output signal V of different output value without increasing pole 23₁ , V
₂ Can be easily detected, and the accurate surface potential V_S To
Can be derived. Also, the measurement electrode 23 is changed.
Therefore, it is possible to suppress the adhesion of dust etc. and reduce the pollution.
Wear.

Further, the signal detecting section 25, the signal amplifying section 26, V
₁ , the output units of the V ₂ detection units 27a and 27b and the signal correction unit 20 are provided with a plurality of noise filters 28 to 32 for removing the noise of the signals output from these output units. The measurement error of the surface potential can be reduced, and the surface potential of the measured object 22 can be measured with high accuracy.
When detecting two or more output signals L ₁ and L ₂ having different output values from the detection signal, the measurement electrode 23 is moved between the positions L ₁ and L _{2 having} different distances from the object 22 to be measured. greatly varied, varying increase the capacitance C ₀ between the object to be measured 22 and the measuring electrode 23, since the detection output signal V _1, V ₂ at each position L _1, L ₂ Two or more output signals V
The output difference between V ₁ and V ₂ can be increased, and the accuracy of measuring the surface potential of the object 22 to be measured can be significantly improved.

Further, as the electrode changing means, the measurement electrode 23 is fixedly provided, and the pair of piezoelectric materials 33 facing each other with the leaf spring 34 interposed therebetween.
Since the bimorph type piezoelectric actuator composed of a and 33b is provided and the bimorph type piezoelectric actuator is driven to largely change the measurement electrode 23, the conventional measurement electrode is fixed to a single piezoelectric material such as PZT ceramic. It is possible to prevent the piezoelectric material from being cracked and broken during the change like the electrode changing means of the above, and it is possible to greatly change the measuring electrode. It is possible to significantly improve the measurement accuracy of the surface potential of 22.

Further, since a voltage that changes periodically or aperiodically is applied as the drive voltage of the bimorph type piezoelectric actuator, the measuring electrode 23 can be greatly changed by a small actuator. Also,
Fix both ends of the bimorph type piezoelectric actuator 35
Since it is supported by, the measuring electrode 23 can be greatly changed by a small actuator.

In this embodiment, the noise detectors 28 to 32 are provided at the output portions of the signal detecting section 25, the signal amplifying section 26, the V ₁ and V ₂ detecting sections 27a and 27b and the signal correcting section 20, respectively. Any of the noise filters may be removed depending on the required measurement accuracy, the installation space, the cost, or the like. Preferably, one or more may be provided on the output side of the signal detection section 25 or the signal amplification section 26, and a combination of a plurality of noise filters may be provided on a desired output section depending on required accuracy. .

Further, in this embodiment, the bimorph type piezoelectric actuator having both ends is used as the electrode changing means, but the invention is not limited to this, and as shown in FIG. A piezoelectric material 36 made of PZT or the like, which is held and fixed, and a unimorph type piezoelectric actuator in which a measuring electrode 23 is fixedly mounted on a metal leaf spring 38 are used.
By applying a voltage to 33, the piezoelectric material 36 may be changed so that the measurement electrode 23 is changed between the positions of the measurement distances L ₁ and L ₂ , and as shown in FIG. Instead, the measurement electrode 23 is attached to the magnet portion of the electromagnetic coil 39,
The magnet in the coil 39 may be changed by passing a time-varying current through the coil 39, and the measurement electrode 23 may be changed between the positions of the measurement distances L ₁ and L ₂ in accordance with the change. Further, as shown in FIG. 10, by driving the leaf spring 41 attached to the enlarging mechanism 40 by the laminated piezoelectric actuator 42, the enlarging mechanism 40 moves the measuring electrode 23 between the positions of the measuring distances L ₁ and L _2. May be changed. The same effect as described above can be obtained by using any of these electrode changing means. Needless to say, the unimorph type or bimorph type piezoelectric actuator may be either cantilever or both-sided.

Further, in this embodiment, the measuring electrode 23 is changed 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 according to, but not limited to a sine wave, a rectangular wave (FIG. 11), a triangular wave (FIG. 12), a sawtooth wave (FIG. 13), or a trapezoidal wave (FIG. 14)
Alternatively, it may be obtained from signals having different output values that fluctuate.

FIGS. 15 to 24 are views showing a second embodiment of the measuring apparatus for carrying out the surface potential measuring method according to the present invention. This embodiment is claimed in claims 1, 2, 4 to 6, 8 to. It corresponds to the invention described in any one of 11. 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 configuration will be described.

In FIG. 15, reference numeral 51 is a vibration capacitance type surface potential sensor, and the surface potential sensor 51 has an opening 52a facing the surface of the object 22 to be measured and opening in a predetermined area, and is electrically shielded. In the shield case 52, a measurement electrode 53 is disposed so as to face the object 22 to be measured at a predetermined distance L through the opening 52a of the shield case 52 and to be electrically independent, and one end of the fixing member 54. One side is fixed to the cantilever and the other side is the measuring electrode
53 is fixed, and further comprises a pair of piezoelectric materials 55a and 55b in which a central portion is provided with a metallic leaf spring (not shown), and a voltage is applied by a voltage supply means to drive the measurement electrode 53.
A bimorph type piezoelectric actuator (electrode changing means) 56 for changing between the positions of the measurement distances L ₁ and L ₂ while periodically vibrating in the direction perpendicular to the surface of the object 22 to be measured, and a signal detecting section 25. , And a signal amplifier 25, V ₁ , V ₂ detectors 27a and 27b, a signal corrector 20, and noise filters 28 to 32 (not shown).

The surface potential sensor 51 is shown in FIG. 16 (c) in which the first and second voltages having the sine wave shape shown in FIGS. 16 (a) and 16 (b) are superposed by the voltage supply means. As shown in FIG. 17, by applying a driving voltage waveform to the piezoelectric materials 55a and 55b to drive the piezoelectric materials 55a and 55b, the measurement electrode 53 is periodically oscillated in the vertical direction with respect to the surface of the object 22 to be measured while being measured. The capacitance between the measurement electrode 53 and the object to be measured 22 is changed by changing the distance between the positions of L ₁ and L ₂ .

Then, the measurement distances L ₁ , L _{2 of the} measurement electrode 53
From the detection signals detected by the signal detection unit 25 at each position and amplified by the signal amplification unit 26, the V ₁ and V ₂ detection units 27a and 27b output the output signals V ₁ and V ₂ having different output values as described above. Detection is performed by performing the same processing as the principle of measuring potential (vibration capacitance type). That is, the bimorph type piezoelectric actuator 56 constitutes a capacitance changing means.

Next, the surface potential measuring method of this embodiment will be described. First, the drive voltage waveform is applied to the piezoelectric materials 55a and 55b to vibrate by ΔL, and the measurement electrode 53 is moved to a position separated from the object 22 to be measured by L ₁ and L ₂ to measure the electrode 53 and the object 22 to be measured. The capacitance C _o between the signal amplification unit 26 and the detection signal detected by the signal detection unit 25 is changed.
Is amplified and the V ₁ detection section 27a is detected from the detected signal
The output signal V ₁ at a distance L ₁ from 22 and the output signal V ₂ at a distance L ₂ from the object 22 to be measured are detected by the V ₂ detection unit 27b. Since the output values of the output signals V ₁ and V ₂ detected by the V ₁ and V ₂ detection units 27a and 27b vary depending on the measurement distance, V ₁ shown in FIG. 4 obtained in the first embodiment described above. , V ₂ corresponding to V ₂ , V ₂ are obtained.

Next, in the case of the vibration capacitance type,
Capacitance C between measuring electrode 53_O Rate of change α_O Is the measurement
Distance L₁ , L₂ Against α₁ = ΔL / (L₁ -ΔL) (11) α₂ = ΔL / (L₂ -ΔL) ... (12) Here, the measurement electrode 53 is connected to the object 22 to be measured L₁ 
C when the distance is₁ , L₂ When in the distance
The capacitance of C₂ Then, each output signal V₁ , V ₂ Out 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 ・ εair ・ (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 if the output ratio V ₂ / V ₁ is obtained, the surface potential V L independent of _S
It is possible to uniquely determine ₁ .

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

In this way, the signal correction section 20 outputs the output signal
V₁ , V₂ Uniquely measured distance L ₁ Seeking L₁ 
And the output value of the output signal for the known measurement distance and
Output signal V₁ Or output signal V₂ Output value of
Corrected, surface potential V of DUT 22_S Of the output value corresponding to
Output signal V₀ Get. And this output signal V₀ Is
Known in advance to the output value of the output signal
Output signal V₀ Surface potential corresponding to the output value of
V_S Surface potential V of the object to be measured 22_S Derive exactly
Can be

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 22. Even in this embodiment, the signal detection unit 25 and the signal amplification unit
Since the noise filters 28 to 32 are provided at the output units of the 26, V ₁ , V ₂ detection units 27a and 27b and the signal correction unit 20,
The noise filters 28 to 32 pass or amplify a necessary signal among the output signals to remove noise, reduce the measurement error of the surface potential of the DUT 22, and reduce the surface potential of the DUT 22. It can be measured with high accuracy.

On the other hand, even in this embodiment, the piezoelectric element 55
By greatly varying the measurement electrode 53 with a and 55b, it is possible to increase the slope of the relationship curve in FIGS. 6A and 6B and improve the measurement accuracy of the surface potential. That is, by increasing the output difference between the output signals V ₁ and V ₂ and increasing the slope of the curve, the detection accuracy of the measurement distance L ₁ is improved, and the surface potential measured from the detected measurement distance is measured. Since it is possible to improve the accuracy, the difference between the outputs of the output signals V ₁ and V ₂ is set to be large. Therefore, as is clear from the above equations (9) and (10), the fluctuation range of the fluctuation of the measurement electrode 23 ΔL or the distance d between the measurement distances L ₁ and L ₂ is increased.

FIG. 18 shows the relationship between the variation width ΔL of the measurement electrode 53 and the detection accuracy of the measurement distance L _{1 when} the measurement distance L = 3 mm, the measurement error of V ₂ / V ₁ ± 0, 3%, and L ₁ , L It is the result of calculating the relationship between the distance d between ₂ and the detection accuracy of the measurement distance L ₁ . In FIG. 18 (a), when d = 0 and 2 mm is constant, the measurement distance L increases as ΔL increases from 0 mm to 1 mm.
It can be seen that the detection accuracy of ₁ is improved.

Further, FIG. 18B shows the case where ΔL = 0.1 mm is kept constant, and it can be seen that the detection accuracy of the measurement distance L ₁ is improved as d is increased from 0.2 mm to 1 mm. Therefore, in this case, the method of improving the measurement accuracy of the surface potential may be to increase the value of ΔL or d. Thus, in this embodiment, the piezoelectric materials 55a and 55b are
By applying the drive voltage waveform to
By oscillating and changing to a position separated by L ₁ and L ₂ from the above, the effect of the above-described embodiment can be obtained.

Although not described in detail as another aspect of the present embodiment, the unimorph type actuator shown in FIG. 8 of the first embodiment, the electromagnetic coil 39 shown in FIG. 9, or the electromagnetic coil 39 shown in FIG. Multi-layer piezoelectric actuator with expansion mechanism 42
FIG. 16 in which the driving voltage waveforms shown in FIGS.
The drive waveform shown in (c) may be applied to cause the measurement electrode 53 to vibrate and be moved to a position separated from the object 22 to be measured by L ₁ and L ₂ .

This drive waveform is shown in FIGS. 16 (a) and 16 (b).
Not limited to the sinusoidal waveform as shown in (c), it is a rectangular wave (Fig. 11), a triangular wave (Fig. 12), a sawtooth wave (Fig. 13), a trapezoidal wave (Fig. 14), etc. It is also possible to add an applied voltage waveform according to a waveform that varies with time. Also, the figure
The measurement electrode 53 may be varied while vibrating by appropriately combining a unimorph type piezoelectric actuator as shown in FIGS. 19 to 24, a bimorph type piezoelectric actuator, an electromagnetic coil or a laminated type piezoelectric actuator with an enlarging mechanism. That is, as shown in FIGS. 19A to 21B, the center or one end side of the bimorph or unimorph type piezoelectric actuators 61a to 61f in which the measuring electrode 53 is supported by the fixing member 54 in a two-sided or cantilevered manner. A piezoelectric material in which the bimorph or unimorph type piezoelectric actuators 61a to 61f are fixed to the electromagnetic coils 62a and 62b or the fixed member 60 and are supported on both sides or on one side.
Attached to 63a-63d and shown in FIG. 16 (a) or FIG. 16 (b)
By applying one voltage to the piezoelectric materials 61a to 61f and applying the other voltage to the electromagnetic coils 62a and 62b or the piezoelectric materials 63a to 63d, the measuring electrodes 53 are vibrated and the measurement distances L ₁ and L _{2 are shown.} You may make it fluctuate between the positions of.

Further, as shown in FIGS. 22 (a) to 23 (b), the measuring electrode 53 is fixed to the electromagnetic coils 62c to 62e, and the electromagnetic coils 62c to 62e are supported on both sides or on one side. Fixed to the center or one end of the bimorph or unimorph type piezoelectric actuators 61g, 61h, laminated on the electromagnetic coil 64a, and further fixed to the laminated piezoelectric actuator 65 with an enlarging mechanism with measuring electrodes. The actuator 65 may be laminated on the electromagnetic coil 64b, and as shown in FIGS. 24 (a) and 24 (b), the electromagnetic coil 62f in which the measuring electrode 53 is fixedly mounted on the laminated piezoelectric actuator 66a with the enlarging mechanism. 22 or a bimorph or unimorph type piezoelectric actuator 67 in which the measurement electrode 53 is fixedly mounted on the laminated piezoelectric actuator 66b with an enlarging mechanism is supported by a cantilever. In the case shown in a) to FIG. 23 (b), one of the voltages shown in FIG. 16 (a) or 16 (b) is applied to the electromagnetic coils 62c to 62e or the laminated piezoelectric actuator 65 with an enlarging mechanism. At the same time, the other voltage may be applied to the piezoelectric actuators 61g, 61h or the electromagnetic coils 64a, 64b to vary the distance between the measurement distances L ₁ and L ₂ while vibrating the measurement electrode 53. In the case of 24 (a) and (b), FIG.
One voltage shown in (a) or FIG. 16 (b) is applied to the electromagnetic coil.
62f or piezoelectric actuator 67 and the other voltage is applied to the laminated piezoelectric actuator
By applying the voltage to 66a and 66b, the measurement electrode 53 may be vibrated while being varied between the positions of the measurement distances L ₁ and L ₂ .

In this embodiment, the measuring electrode 53 is housed in the shield case 52, and the signal detected by the measuring electrode 53 is also housed in the shield case 52.
Since the signal process is performed as described above by V _1, V ₂ detection section 27a, 27b and the signal correcting unit 20 and the noise filter 28 to 32 is amplified by the shield case 52 outside the signal amplifier 26 via, the It is possible to detect the surface potential of the measuring body 22 with higher accuracy.

Further, the surface potential measuring device of the first embodiment described above uses the chopper electrode 24 to measure the measuring electrode as shown in FIG.
Although the effective area ΔS of 23 is changed, even in the first embodiment, the chopper electrode 24 and the electrode 23 are housed in the shield case 52 and electrically shielded as in the present embodiment. good. Next, FIG. 25 to FIG. 29 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, 5, 7, 10, 1
It corresponds to the invention described in any one of 2 and 13. 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. 25, 71
Is a vibration capacitance type surface potential sensor.
71 is the inside of the shield case 52, the opening of the shield case 52
A measurement electrode 72, which is arranged so as to face the object 22 to be measured through a predetermined distance L via 52a and is electrically independent, and is driven by being applied with a voltage by a voltage supply means to measure the measurement electrode 72. A pair of piezoelectric materials that periodically fluctuate with different fluctuation widths ΔL ₁ and ΔL ₂ in the vertical direction with respect to the surface of the body 22.
A bimorph type piezoelectric material (electrode changing means) 73a and 73b sandwiching a metal leaf spring (not shown), and a signal detecting section 25.
And a signal amplification section 26, V ₁ , V ₂ detection sections 27a and 27b, and a signal correction section 20, which are not shown.
The noise filters 28 to 32 are provided.

The surface potential sensor 71 is driven by applying a sinusoidal drive voltage waveform, as shown in FIG. 26 (a), which cyclically fluctuates to the piezoelectric materials 73a and 73b, by the voltage supply means. As shown in, the measurement electrode 72 is periodically varied in the vertical direction with respect to the surface of the object 22 to be measured with different fluctuation widths ΔL ₁ and ΔL ₂ so that the distance between the measurement electrode 72 and the object 22 is changed. Change the capacitance. Then, from the detection signals detected by the signal detection unit 25 and amplified by the signal amplification unit 26 with the fluctuation widths ΔL ₁ and ΔL ₂ of the measurement electrodes 72, V ₁ and V ₂ detection units 27a and 27b output different output values. The signals V ₁ and V ₂ are detected by performing the same processing as the principle of measuring the surface potential described above. That is, the bimorph type piezoelectric actuator 74 constitutes a capacitance changing means. In addition,
As shown in FIG. 26 (b), the piezoelectric material 73 is applied with a voltage whose frequency fluctuates greatly periodically or whose magnitude fluctuates greatly.
a and 73b are applied to drive the measuring electrode 72
May be varied with different variation widths ΔL ₁ and ΔL ₂ .

Next, the surface potential measuring method of this embodiment will be described.
Explain. First, the drive voltage is applied to the piezoelectric materials 73a and 73b.
Applying a waveform to the measurement electrode 72 and varying the variation width ΔL₁ and
Variation range ΔL₂Between the measurement electrode 72 and the DUT 22
Capacitance C between_O And the signal detection unit 25 detects
The detection signal is amplified by the signal amplification unit 26
Et V₁ The detection unit 27a has a fluctuation range ΔL.₁ Output signal V at ₁ 
Again V₂ The detection unit 27b has a fluctuation range ΔL.₂ Output signal at
Issue V₂ To detect. This V₁ , V₂ The detectors 27a and 27b
Output signal V to detect₁ , V₂ The output value of the
Variation range ΔL₁ , ΔL₂ Is almost proportional to
V obtained in one example and shown in FIG.₁ , V₂ I will correspond to
Such signals having different output values can be 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 22 and the measuring electrode 72 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 · cos ωt (19) V ₂ = A _O · β ₂ · ω · C _O · V _S · cos ωt = A _O · ΔL ₂ / (L−ΔL ₂ ) · ω · ε _air・ ( S /
L) · 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. 27 (a), and if the output ratio V ₂ / V ₁ is obtained, L will be independent of the surface potential V _S. It is possible to obtain a unique request.

Alternatively, set the output ratio to V₁ / V₂ Then V
₁ / V₂ Is 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/ V₂ The relationship with is as shown in Fig. 27 (b).
It is represented by a curve. Therefore, this is also the output ratio V ₁ / V
₂ Then, the surface potential V_S Uniquely L without depending on
It becomes possible to ask.

In this way, the signal correction section 20 outputs the output signal.
V₁ , V₂ Uniquely measured distance L ₁ Seeking L₁ 
And the output value of the output signal for the known measurement distance and
Output signal V₁ Or output signal V₂ Output value of
Corrected, surface potential V of DUT 22_S Of the output value corresponding to
Output signal V₀ Get. And this output signal V₀ Is
Known in advance to the output value of the output signal
Output signal V₀ Surface potential corresponding to the output value of
V_S Surface potential V of the object to be measured 22_S Derive exactly
Can be

Further, 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 22. Even in this embodiment, the signal detection unit 25 and the signal amplification unit
Since the noise filters 28 to 32 are provided at the output units of the 26, V ₁ , V ₂ detection units 27a and 27b and the signal correction unit 20,
The noise filters 28 to 32 pass or amplify a necessary signal among the output signals to remove noise, reduce the measurement error of the surface potential of the DUT 22, and reduce the surface potential of the DUT 22. It can be measured with high accuracy.

Also in this embodiment, in order to detect the surface potential of the object 22 to be measured with high accuracy and to improve the measurement accuracy of the surface potential, the slope of the relational curve in FIG. Increase. That is, the output difference between the output signals V ₁ and V ₂ is set to be large, and the slope of the curve is increased to improve the detection accuracy of the measurement distance L ₁ and measure the surface potential obtained from the detected measurement distance. The accuracy can be improved.

As is clear from the equations (21) and (22), the change widths ΔL ₁ and ΔL ₂ of the fluctuation of the measuring electrode 72 are increased as a method of increasing the output difference between the output signals V ₁ and V _2. The range of change may be increased. Fig. 29 (a) shows the measurement distance L = 3
mm, V ₂ / V ₁ measurement error ± 0, the relationship between the variation width ΔL ₁ of the fluctuation of the measurement electrode 72 and the detection accuracy of the measurement distance L at 3%
The figure (b) shows the measurement distance L = 3 mm, the measurement error of V ₂ / V ₁ ±
It is the result of calculating the relationship between the variation width ΔL ₂ of the fluctuation of the measurement electrode 72 at 0% and 3% and the detection accuracy of the measurement distance L.

As is clear from FIG. 9A, ΔL ₂ = 0.7
It can be seen that the detection accuracy of the measurement distance L is improved as ΔL ₁ is decreased from 0, 3 mm to 0 mm and the difference from the change width of ΔL ₂ is increased in the case of constant mm. Further, FIG. 7B shows the case where ΔL ₁ = 0.01 mm is constant,
It can be seen that the accuracy of detecting the measurement distance is improved as L ₂ is increased from 0.2 mm to 1 mm. Therefore, in this case, as a method for improving the measurement accuracy of the surface potential,
A large difference between the change widths of ΔL ₁ and ΔL ₂ may be taken.

Further, as shown in FIG. 27, in order to detect the surface potential with high accuracy, the measurement electrode 72 is periodically changed in the direction of the object 22 to be measured, and the change width of the change is made different. As the varying means, the unimorph type piezoelectric actuator shown in FIGS. 8 to 10, the laminated piezoelectric actuator with an enlarging mechanism, or the electromagnetic coil is used, and the driving voltage of each voltage varying means is as shown in FIG. It is also possible to apply a varying voltage of different magnitude, or to apply a voltage waveform in which the frequency of the drive voltage waveform is different, with the magnitude of the drive voltage being constant, as shown in FIG. 26 (b). Is. Alternatively, in each of the drive voltage waveforms shown in FIGS. 26A and 26B, a waveform in which the magnitude and frequency of the drive voltage are simultaneously different may be applied to the voltage changing means.

The applied voltage waveform is shown in FIG.
Not only the sinusoidal waveforms shown in (a) and (b), but also waveforms for varying the measurement electrode 72 (rectangular waveform, trapezoidal waveform, triangular waveform, sawtooth waveform, pulse waveform, etc., or aperiodic) Waveform that varies with time) and a waveform that changes the variation width of the measurement electrode 72 (sine wave (FIG. 5), rectangular wave (FIG. 11), triangular wave (FIG. 12), sawtooth wave (FIG. 13), trapezoidal wave) An applied voltage waveform according to a waveform that fluctuates periodically or aperiodically (Fig. 14) can be applied.

As described above, in this embodiment, the piezoelectric material 73a,
By applying the drive voltage waveform to 73b and varying the measurement electrode 72 with different variation widths ΔL ₁ and ΔL ₂ , it is possible to obtain the same effects as the above-described embodiment.

[0097]

According to the first aspect of the invention, the capacitance between the object to be measured and the measuring electrode is changed, and the change in the electrostatic capacitance is induced corresponding to the surface potential of the object to be measured. The electric potential of the measurement electrode that changes with the detection of the electric field is detected, and then at least two or more output signals having different output values are detected from the detection signal, and then the surface potential of the measured object is derived from the output 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 can be derived from the output value. Therefore, an accurate surface potential can be derived without increasing the number of measurement electrodes.

Furthermore, the potential detection signal of the measuring electrode, 2
Since at least one or more of the noise generated in the one or more output signals and the signal for guiding the surface potential of the measured object is removed, it is possible to reduce the measurement error of the surface potential of the measured object. The surface potential of the measurement object can be measured with high accuracy. According to the second aspect of the invention, as a method of detecting at least two output signals having different output values from the detection signal, the measurement electrode is largely changed between positions having different distances from the object to be measured, Since the electrostatic capacitance between the object to be measured and the measurement electrode is largely changed and the output signal at each position is detected, it is possible to increase the output difference between two or more output signals. The accuracy of measuring the body surface potential can be significantly improved.

According to the 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 largely changed in a variation range of different sizes to be measured. Since the electrostatic capacitance between the body and the measurement electrode is largely changed to detect the output signal in each fluctuation range, it is possible to increase the output difference between two or more output signals. It is possible to greatly improve the measurement accuracy of the surface potential of the measurement object.

According to the fourth aspect of the present invention, the capacitance changing means for changing the electrostatic capacitance between the object to be measured and the measuring electrode, and the electrostatic capacitance induced corresponding to the surface potential of the object to be measured. A potential detection unit that detects the potential of the measurement electrode that changes with a change, an output detection unit that detects at least two output signals having different output values from the detection signal, and a surface potential of the object to be measured from the output signal. Since the surface potential deriving means for deriving the surface potential is provided, an accurate measurement distance can be obtained from the output signal, and the surface potential of the measured object can be obtained from the output value by correcting the output value from the measurement distance. Can be derived. As a result, an accurate surface potential can be derived with a simple and inexpensive structure without increasing the number of measurement electrodes.

At least one of the output portions of the potential detecting means, the output detecting means, and the surface potential deriving means.
Since one or more noise filters for removing noise are provided, the measurement error of the surface potential of the measured object can be reduced, and the surface potential of the measured object can be measured with high accuracy. According to the fifth aspect of the present invention, since the noise filter is used to pass or amplify only the necessary signal among the signals output from the potential detecting means, the output detecting means, and the surface potential deriving means, the capacitance is increased. It is possible to effectively remove only the noise corresponding to the signals output from the changing means, the potential detecting means, and the surface potential deriving means, and to measure the surface potential of the object to be measured with a low-cost configuration with higher accuracy. You can

According to the sixth aspect of the present invention, the capacitance changing means is provided with electrode changing means for changing the measuring electrode largely between positions having different distances from the object to be measured, and the measuring electrode is changed by the electrode changing means. The capacitance between the object to be measured and the measuring electrode is largely changed by largely changing between the positions having different distances from the object to be measured, and the output detection means detects the potential at each different position of the measuring electrode. Since two or more output signals having different output values are detected from the detection signal by the means, the output difference between the two or more output signals can be increased, and the surface potential of the measured object can be measured with high accuracy. It can be greatly improved.

According to the seventh aspect of the present invention, the capacitance changing means is provided with an electrode changing means for changing the measuring electrode largely in a changing range of different sizes, and the measuring electrode is changed in a different changing range by the electrode changing means. Then, the electrostatic capacitance between the object to be measured and the measurement electrode is largely changed, and the output detection means changes the output value from the detection signal by the potential detection means in each of the different fluctuation widths equal to or more than the predetermined value of the measurement electrode Since two or more output signals are detected, the output difference between the two or more output signals can be increased and the measurement accuracy of the surface potential of the measured object can be significantly improved.

According to the eighth aspect of the invention, the electrode changing means is provided with a unimorph type or bimorph type piezoelectric actuator in which the measurement electrode is fixedly mounted, a laminated piezoelectric actuator with an enlarging mechanism, or an electromagnetic coil,
The unimorph type or bimorph type piezoelectric actuator in which the measurement electrode is fixedly mounted, or the laminated type piezoelectric actuator with an enlarging mechanism, or the electromagnetic coil is driven to largely change the measurement electrode. It is possible to prevent the piezoelectric material from being damaged by cracks and the like when changing, as in the conventional electrode changing means in which the measuring electrode is fixed to the piezoelectric material alone, and it is possible to greatly change the measuring electrode.
The accuracy of measuring the surface potential of the object to be measured can be significantly improved with a simple configuration.

According to the ninth aspect of the present invention, a unimorph type or bimorph type piezoelectric piezoelectric actuator in which the measurement electrode is fixedly mounted, a laminated piezoelectric actuator with an enlarging mechanism, or a DC voltage is used as a drive voltage for the electromagnetic coil. Since the voltage which changes periodically is applied, the measuring electrode can be largely changed by the small electrode changing means.

According to the tenth aspect of the present invention, since one end side or both end sides of the unimorph type or bimorph type piezoelectric actuator is supported, the measuring electrode can be largely changed by a small electrode changing means. Claim 11
According to the described invention, the unimorph type or bimorph type piezoelectric actuator, or the laminated type piezoelectric actuator with a magnifying mechanism, or the driving voltage of the electromagnetic coil, the measurement electrode is varied between positions at different distances from the measured object. Since a voltage that superimposes the first voltage to be applied and the second voltage that vibrates the electrode to be measured that fluctuates between the different positions is applied, the position where the measurement electrode is at a different distance from the object to be measured is applied. It is possible to greatly fluctuate between them and to vibrate them.

According to the twelfth aspect of the present invention, a unimorph type or bimorph type piezoelectric actuator, a laminated piezoelectric actuator with a magnifying mechanism, or a voltage varying in size is applied as a drive voltage for an electromagnetic coil. Therefore, the measurement electrode can be greatly changed in a variation range of different sizes. According to the invention of claim 13, a unimorph type or bimorph type piezoelectric actuator, or a laminated piezoelectric actuator with a magnifying mechanism, or a voltage varying frequency is applied as a driving voltage of the electromagnetic coil. Can be greatly varied with variation widths of different sizes.

[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. 3A is a configuration diagram of a main portion of the bimorph type piezoelectric actuator and an object to be measured, and FIG. 3B is a configuration diagram of a main portion of the piezoelectric material.

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] Measurement distance L = 3 mm, measurement error of V ₂ / V ₁ ± 0.3
FIG. 6 is a diagram showing the relationship between the detection accuracy of the measurement distance L ₁ of the surface potential and the variation distance d of the measurement electrode when%.

FIG. 8 (a) is a main part configuration diagram of the unimorph type piezoelectric actuator and an object to be measured showing another embodiment, and FIG. 8 (b) is a main part configuration diagram of the piezoelectric material.

FIG. 9 is a front view of an electromagnetic coil showing another aspect.

FIG. 10A is a top view of the magnifying mechanism laminated piezoelectric actuator showing another embodiment, and FIG. 10B is a front view thereof.

FIG. 11 is a diagram showing a detection signal in the case of being changed in a rectangular wave shape different from that in FIG. 5.

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

FIG. 13 is a diagram showing a detection signal when it is changed in a sawtooth shape different from that in FIG. 5.

FIG. 14 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. 15 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.

16A and 16B are diagrams showing a drive voltage waveform applied to the piezoelectric material, wherein FIG. 16A is a voltage waveform for varying the measurement electrode, and FIG. 16B 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. 17 is an explanatory diagram illustrating a variation of the measurement electrode.

FIG. 18A is a diagram showing the relationship between the variation width ΔL of the measurement electrode and the detection accuracy of the measurement distance L ₁ when the measurement distance L = 3 mm and the measurement error of V ₂ / V ₁ is ± 0.3%; 8] is a diagram showing the relationship between the detection accuracy of the measurement distance L ₁ and the variation distance d of the measurement electrode at that time.

19A and 19B are diagrams showing another aspect, and FIGS. 19A and 19B are examples of a combination of a piezoelectric material and an electromagnetic coil.

FIG. 20 is a diagram showing another embodiment, and FIGS. 20 (a) and 20 (b) are examples in which piezoelectric materials are combined and the supporting method is changed.

FIG. 21 is a diagram showing another embodiment, and FIGS. 21 (a) and 21 (b) are examples in which piezoelectric materials are combined and the supporting method is changed.

22A and 22B are views showing another embodiment, and FIGS. 22A and 22B are examples of a case where a supporting method is changed by combining an electromagnetic coil and a piezoelectric material.

23A and 23B are views showing another aspect, in which FIG. 23A shows an example in which electromagnetic coils are combined with each other, and FIG. 23B shows an example in the case where electromagnetic coils and a laminated piezoelectric actuator with an enlarging mechanism are combined.

24A and 24B are diagrams showing another embodiment, FIG. 24A is an example of a combination of an electromagnetic coil and a laminated piezoelectric actuator with an enlarging mechanism, and FIG. 24B is a laminated material piezoelectric actuator and a laminated piezoelectric actuator with an enlarging mechanism. This is an example of a combination of.

FIG. 25 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. 26 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. 27 is an explanatory diagram illustrating a variation of the measurement electrode.

FIG. 28 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. 29 (a) is a diagram showing the relationship between the variation width ΔL ₁ of the measurement electrode and the detection accuracy of the measurement distance L ₁ when the measurement distance L = 3 mm and the measurement error of V ₂ / V ₁ is ± 0.3%; FIG. 6B is a diagram showing the relationship between the detection accuracy of the change width ΔL ₂ of the fluctuation of the measurement electrode and the measurement distance L at that time.

FIG. 30 is a conceptual diagram of a surface potential measuring device previously proposed by the applicant.

[Explanation of symbols]

20 Signal correction section (surface potential deriving means) 21, 51, 71 Surface potential sensor 22 DUT 23, 53, 72 Measuring electrode 24 Chopper electrode (capacity changing means) 25 Signal detecting section (potential detecting means) 26 Signal amplifying section 27a V ₁ detection section (output detecting means) 27b V ₂ detection section (output detecting section) 28 to 32 noise filter 33a, 33b, 36,55a, 55b piezoelectric material (electrode variation means, the capacitance change means) 61a to 61h, 63a ~ 63d, 67, 73a, 73b Piezoelectric actuator (electrode changing means, capacity changing means) 39, 62a ~ 62f, 64a, 64b Electromagnetic coil (electrode changing means, capacity changing means) 42 Multilayer piezoelectric actuator with expansion mechanism 56, 74 Bimorph type piezoelectric actuator V ₀ , V ₁ , V ₂ output signal L, L ₁ , L ₂ measuring distance ΔL ₁ , ΔL ₂ fluctuation range

Claims (13)

[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, which is induced corresponding to the surface potential of the object to be measured and changes with the change in the capacitance, is detected, and then two or more output signals having different output values are detected from the detection signal. After that, in the surface potential measuring method adapted to derive the surface potential of the measured object from the output signal, a potential detection signal of the measurement electrode, two or more output signals and a signal for guiding the surface potential of the measured object are obtained. A surface potential measuring method, characterized in that at least one or more of the generated noise is removed. 2. As a method for detecting at least two output signals having different output values from the detection signal, the measurement electrode is largely changed between positions having different distances from the measurement object to measure the measurement object. 2. The surface potential measuring method according to claim 1, wherein the electrostatic capacitance between the measuring electrode and the measuring electrode is largely changed, and the output signal at each position is detected. 3. As a method of detecting at least two output signals having different output values from the detection signal, the measurement electrode is largely changed in a variation range of different sizes, and the measurement object and the measurement electrode are changed. 2. The surface potential measuring method according to claim 1, wherein the electrostatic capacitance between the two is greatly 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 capacitance of the measuring electrode, 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 capacitance, and at least 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. A surface potential measuring device, wherein a noise filter for removing noise is provided in at least one of the output sections of the output detecting means and the surface potential deriving means. 5. The noise filter according to claim 4, wherein the noise filter passes or amplifies only a necessary signal among the signals output from the potential detecting means, the output detecting means and the surface potential deriving means. Surface potential measuring device. 6. The capacitance changing means is provided with an electrode changing means for changing the measuring electrode largely between positions having different distances from the object to be measured, and the electrode changing means moves the measuring electrode from the object to be measured. By greatly varying between different positions, the capacitance between the measured object and the measurement electrode is greatly changed, the output detection means, from the detection signal by the potential detection means at each different position of the measurement electrode Different output value 2
5. Detecting more than one output signal.
Alternatively, the surface potential measuring device according to item 5. 7. The capacitance changing means is provided with an electrode changing means for changing the measuring electrode largely in a changing range of different sizes, and the electrode changing means changes the measuring electrode in a large changing range of different sizes. The electrostatic capacitance between the object to be measured and the measurement electrode is largely changed, and the output detection means outputs two or more outputs having different output values from the detection signal by the potential detection means in the respective fluctuation widths of the measurement electrode different from each other. The surface potential measuring device according to claim 4 or 5, wherein a signal is detected. 8. A unimorph type or bimorph type piezoelectric actuator in which a measuring electrode is fixedly mounted on the electrode changing means, or a laminated type piezoelectric actuator with an enlarging mechanism,
Alternatively, a unimorph type or bimorph type piezoelectric actuator in which an electromagnetic coil is provided and a measurement electrode is fixedly installed,
8. The surface potential measuring device according to claim 6 or 7, wherein the measuring electrode is largely changed by driving a laminated piezoelectric actuator with an enlarging mechanism or an electromagnetic coil. 9. A unimorph type or bimorph type piezoelectric actuator having a fixed measurement electrode, a laminated type piezoelectric actuator with a magnifying mechanism, or a DC voltage or a cyclically varying voltage is applied as a driving voltage for an electromagnetic coil. The surface potential measuring device according to claim 8, wherein 10. The surface potential measuring device according to claim 8, wherein one end side or both end sides of the unimorph type or bimorph type piezoelectric actuator is supported. 11. A driving voltage for the unimorph type or bimorph type piezoelectric actuator, the laminated piezoelectric actuator with a magnifying mechanism, or the electromagnetic coil,
A voltage obtained by superimposing a first voltage that varies the measurement electrode between positions having different distances from the measurement target and a second voltage that vibrates the measurement electrode that varies between the different positions from each other 9. The surface potential measuring device according to claim 8, which is applied. 12. A unimorph type or bimorph type piezoelectric actuator having a fixed measurement electrode, a laminated piezoelectric actuator with a magnifying mechanism, or a voltage varying in size is applied as a driving voltage for an electromagnetic coil. The surface potential measuring device according to claim 8. 13. A driving voltage for the unimorph type or bimorph type piezoelectric actuator, the laminated piezoelectric actuator with a magnifying mechanism, or the electromagnetic coil,
9. The surface potential measuring device according to claim 8, wherein a voltage whose frequency fluctuates is applied.