JPH09211046A - Non-contact potential detection method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect an unknown potential on an object to be measured by a sensor electrode without being influenced by a distance between the object and the sensor electrode. SOLUTION: While a sensor electrode 1 is vibrated in a direction orthogonal to a plane of an object 101 to be measured, each time potential difference between the object 101 and the electrode 1 is changed, an AC modulation signal is detected from the electrode 1, and a distance between the object 101 and the electrode 1 is estimated from a change in magnitude of the detected AC modulation signal. In addition, an apparent potential on the object 101 at the time when magnitude of the AC modulation signal is zero is detected, and the apparent potential is compensated based on the estimated distance, thereby allowing an actual potential on the object 101 to be detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductor pattern formed on a printed circuit board or a voltage on an electronic part lead when the electronic part such as an IC is mounted on the printed circuit board. Alternatively, the present invention relates to a non-contact potential detection method and device for detecting a potential in a non-contact state.

[0002]

2. Description of the Related Art As is well known, conventionally, in a printed circuit board or the like on which electronic parts such as ICs are mounted, voltage or signal at an input / output pin of an electronic circuit or a test point provided in the vicinity thereof In actuality, measuring instruments such as testers and oscilloscopes are used exclusively for measuring / observing waveforms and the like. During the measurement / observation, the voltage and signal waveform at the measured point are extracted to the outside while the test leads and the probe are mechanically and electrically connected to the measured point (test point etc.). Moreover, it has been measured / observed. In order to enable such measurement / observation, the measured point itself had to have a conductor portion exposed on its outer surface. On the other hand, apart from the above circumstances, recently, the lead pitch of electronic circuit components such as ICs tends to become gradually narrower in order to achieve higher density in component mounting. In such a contact-type signal detection method, it is difficult to make accurate mechanical positioning contact of the test lead or probe to the measured point, and the mechanical contact causes scratches on the measured point, resulting in a printed circuit board. It is undeniable that the overall reliability will decline.

In order to solve the above problems, for example, Japanese Patent Laid-Open No. 5-264672 discloses a method in which a point to be measured and a detection probe are capacitively coupled and a signal is detected in a non-contact state. However, in this case, only the temporal change component of the detected signal, that is, only the AC component is detected, and the detection of the DC component is disabled. Incidentally, the detection method will be briefly described. The intensity of the detection signal is proportional to the coupling capacitance C interposed between the measured point and the detection probe, but if they are approximated as parallel plates, the The coupling capacitance C is obtained by the following mathematical formula 1.

[0004]

[Equation 1]

However, ε is the dielectric constant, S is the electrode area, and d is the distance between the electrodes.

In addition to the above publications, as a method for detecting a signal component that does not change with time in a non-contact state, that is, a DC signal, the Trek Japan general catalog issued by Trek Japan KK ( PRODUCTS A
The "electrostatic measurement surface potential meter" described in ND SYSTEMS CATALOGUE) is known. The measurement principle shown in the catalog will be described below with reference to FIG.

That is, as shown in FIG. 9A, the sensor electrode 901 in the probe unit is designed so that the sensor electrode (Se) 901 and the surface to be measured 902 are coupled by the capacitance (C) 903 during measurement. Indicates that the sensor electrode 901 itself is in a vibrating state in a state of being close to the surface to be measured 902. Since the sensor electrode 901 is attached to the tuning fork 904, if the tuning fork 904 vibrates due to the signal from the oscillator 911, the sensor electrode 901 is accompanied by it.
It itself is also in a vibrating state. Now, if the sensor electrode 901 is placed in a vibrating state, the electrostatic capacitance 903 is also slightly changed accordingly.
1, and an AC modulation signal is obtained from the sensor electrode 901 based on the existence of the potential difference between the measured surfaces 902. This AC modulated signal is then passed through a preamplifier (preamplifier) 905 and an amplifier 906 to the synchronous detector 90.
By performing the synchronous detection at 7, the magnitude signal 908 of the AC modulation signal is obtained from the synchronous detector 907 in a highly accurate state. The magnitude signal 908 is integrated by the integrator 909, and an output voltage corresponding to the integrated output is generated from the high voltage generator 910 and then applied to the sensor electrode 901 as a potential. As a result of the above feedback control, the output voltage from the high voltage generator 910 is controlled so that the potential difference between the sensor electrode 901 and the surface to be measured 902 becomes zero. In other words, the output voltage at the time when the output voltage from the high voltage generator 910 does not change at all is obtained as the potential on the measured surface 902.

[0008]

However, in the case of the above publication, since the coupling capacitance C is in inverse proportion to the inter-electrode distance d, in order to accurately detect the intensity of the detected signal, the coupling capacitance C C, therefore, when detecting a signal, the inter-electrode distance d needs to be accurately measured in advance, or the inter-electrode distance d needs to be controlled so as to be kept constant. Further, according to the above catalog, as shown in FIG. 9B, zero potential calibration needs to be performed prior to potential measurement. Zero potential calibration is performed in a state where the probe 1001 is placed at a position separated by a distance l with respect to the metal plate 1002 connected to the ground of the electrometer 1000, but when measuring the potential on the DUT 1003. Is
When the probe 1001 is arranged at a position separated by the same distance l from the object to be measured 1003, the object to be measured 10
That is, the potential measurement for 03 had to be performed. That is, in any of the above-mentioned conventional techniques, when the signal / potential is measured in the non-contact state, no consideration is given to eliminating the influence of the measured object and the distance between the sensor electrodes.

A first object of the present invention is to provide a non-contact potential detecting method and apparatus capable of detecting an unknown potential on an object to be measured by the sensor electrode without being affected by the distance between the object to be measured and the sensor electrode. To serve. A second object of the present invention is a non-contact potential detecting device capable of detecting an unknown potential on an object to be measured without being affected by the object to be measured and a distance between sensor electrodes as a miniaturized device. To serve. A third object of the present invention is to provide a non-contact potential detection method and apparatus capable of more reliably detecting an unknown potential on a measured object with a sensor electrode without being affected by the distance between the measured object and the sensor electrode. To serve. A fourth object of the present invention is that, as a miniaturized device itself, it is a non-contact device capable of more reliably detecting an unknown potential on the measured object without being affected by the measured object and the distance between the sensor electrodes. It is to provide a potential detection device.

[0010]

The first object is basically to place an arbitrary position facing the object to be measured in a state where the potential difference is made variable between the object to be measured and the sensor electrode. AC modulation generated by vibration of the sensor electrode itself each time the potential difference between the DUT and the sensor electrode is changed while vibrating the arranged sensor electrode in a direction perpendicular to the plane of the sensor electrode at a constant cycle. A signal is detected from the sensor electrode, and based on a change in the magnitude of the AC modulation signal detected corresponding to the potential difference, based on a theoretical formula or error data that is actually measured in advance, between the measured object and the sensor electrode. Is estimated, the apparent potential on the DUT when the magnitude of the AC modulation signal becomes 0 is detected, and the apparent potential is calculated based on the estimated distance between the DUT and the sensor electrode. By being corrected, it is accomplished by the actual potential on the object to be measured is detected in a non-contact state,
In addition, the device configuration includes, as its constituent elements, a sensor electrode arranged at an arbitrary position facing the object to be measured and a vibration generation for vibrating the sensor electrode at a constant cycle in a direction orthogonal to the plane of the sensor electrode. Means, a DC voltage applying means for directly and indirectly applying a DC voltage to the sensor electrode while changing the DC voltage, and each time the DC voltage applied to the sensor electrode is changed by the DC voltage applying means, the sensor electrode AC modulation signal detecting means for detecting an AC modulation signal from the DC voltage applying means and the application of the DC voltage from the DC voltage applying means to the sensor electrode are controlled, while the DC voltage corresponding to the DC voltage is detected from the AC modulation signal detecting means. The distance between the object to be measured and the sensor electrode can be estimated from the change in the magnitude of the AC modulation signal based on the theoretical formula or the error data measured in advance. Together, on the magnitude of the AC-modulated signal is detected the apparent potential on the object to be measured at the time of the 0,
This is achieved by at least including a control / processing unit that detects the actual potential on the measured object in a non-contact state by correcting the apparent potential based on the estimated distance between the measured object and the sensor electrode. . The second purpose is also to provide an insulating structure in which at least the sensor electrode and the vibration generating means have a tip as one end capable of contacting the object to be measured when the non-contact potential detecting device is configured as described above. This is achieved by being configured as a probe for detecting non-contact potential which is housed and arranged inside the other end of a cylinder made of a material.

The third object is to make the potential difference variable between the object to be measured and the sensor electrode, and to arrange the auxiliary electrode having the same potential as the sensor electrode around the vicinity of the sensor electrode. The sensor electrode, which is arranged at an arbitrary position facing the object to be measured, is oscillated at a constant cycle in a direction orthogonal to the plane of the sensor electrode alone or together with the auxiliary electrode, while the sensor electrode is placed between the object to be measured and the sensor electrode. Each time the potential difference is changed, the AC modulation signal generated by the vibration of the sensor electrode itself is detected from the sensor electrode, and from the change in the magnitude of the AC modulation signal detected corresponding to the potential difference, a theoretical formula or a previously measured value is measured. The distance between the object to be measured and the sensor electrode is estimated based on the error data, and the apparent potential on the object to be measured when the magnitude of the AC modulation signal becomes zero. After being emitted, the estimated object to be measured, by correcting the apparent potential based on the distance between the sensor electrodes, the real potential on the object to be measured is achieved by being detected in a non-contact state. As a device configuration, as its constituent elements, a sensor electrode, which is arranged at an arbitrary position facing the object to be measured, and auxiliary electrodes of the same potential are arranged in the vicinity, and the sensor electrode alone or as an auxiliary electrode Vibration generating means for vibrating together with the electrodes at a constant cycle in a direction orthogonal to the plane of the sensor electrode, direct voltage applying means for directly and indirectly applying direct voltage to the sensor electrode in a changed state, and direct voltage applying means AC modulation signal detection means for detecting an AC modulation signal from the sensor electrode each time the DC voltage applied to the sensor electrode is changed by the DC voltage application means. While controlling the application of the DC voltage to the sensor electrode from the above, from the change in the magnitude of the AC modulation signal detected corresponding to the DC voltage from the AC modulation signal detecting means, a theoretical formula or it is measured in advance. Based on the error data, the distance between the object to be measured and the sensor electrode is estimated, and the apparent potential on the object to be measured when the magnitude of the AC modulation signal becomes 0 is detected. This is achieved by at least including control / processing means for detecting the actual potential on the measured object in a non-contact state by correcting the apparent potential based on the distance between the measured object and the sensor electrode. Fourth above
The object of (1) is also made of an insulating material, at least the sensor electrode and the vibration generating means of which the tip as one end can contact the object to be measured when the non-contact potential detecting device is configured as described above. This is achieved by being configured as a probe for detecting non-contact potential which is housed and arranged inside the other end of the cylinder.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below, but the theoretical background thereof will be described below. That is, FIG. 2 shows the principle configuration for carrying out the non-contact potential detection method according to the present invention. The measurement target in this example is the electrode under measurement 101 to which the voltage under measurement (= Vx) 102 is applied. The upper potential. Here, assuming that the variable voltage Vr is applied to the sensor electrode 1, the distance between the electrode 101 to be measured and the sensor electrode 1 is d, the area of both electrodes is S, and the dielectric between these electrodes is S. Rate ε
Then, the coupling capacitance C between both electrodes is obtained as the above-mentioned formula 1. Now, the vibrating body 2 is vibrated by the signal from the oscillator 4, and therefore the vibrating body 2 is vibrated.
If the sensor electrode 1 placed on the upper electrode is also vibrated at the angular frequency ω and the distance between both electrodes is changed by Δd (= ± Δd), the coupling capacitance C thereof is changed by ΔC, and as a result, As a result, the current (i) 10 shown in the following Expression 2 flows on the sensor electrode 1.

[0013]

[Equation 2]

In this case, since the current i is proportional to the potential difference (= Vx-Vr) between the two electrodes, the variable voltage Vr when the current i becomes 0 while changing the variable voltage Vr.
Is obtained, the measured voltage (= Vx) 102 on the measured electrode 101 is calculated as Vx = Vr. Incidentally, the change amount ΔC of the coupling capacitance C accompanying the distance change amount Δd is as shown in the following mathematical expression 3.

[0015]

(Equation 3)

After all, the potential difference between the electrodes (= Vx-Vr)
As shown in FIG. 3 (a), the current i with respect to is dependent on the distance d between the two electrodes, but in obtaining the value of the variable voltage Vr when the current i becomes 0, , Is independent of the distance d between both electrodes. That is, the measured voltage (= Vx) 102 can be detected as Vx = Vr from the value of the variable voltage Vr when the current i becomes 0, regardless of the distance d between both electrodes.

However, in reality, due to various error factors such as the shape of each electrode, the electric field distribution around those electrodes, and the error in the detection system electronic circuit, as shown in FIG. Since the zero point position is displaced depending on the distance d, the variable voltage V when the current i becomes zero is simply
The voltage to be measured (Vx) 102 cannot be accurately detected only by obtaining the value of r, and it is necessary to measure the distance d in advance or to keep the distance d at a constant value. . Therefore, in the present invention, the potential difference (= Vx-
Paying attention to the fact that the degree of change of the current i with respect to Vr) is almost inversely proportional to the distance d between both electrodes, and based on a theoretical formula or error data measured in advance, the distance between the object to be measured and the sensor electrode And the apparent potential on the DUT when the magnitude of the AC modulation signal becomes 0 is detected, and the apparent potential is corrected based on the estimated DUT-sensor electrode distance. By doing so, the actual potential on the measured object is detected in a non-contact state.

Now, the present invention will be described in detail with reference to FIG.
Shows a configuration of an example of the non-contact potential detecting device according to the present invention. As shown, the DUT in this example is
Conductor pattern 10 formed on printed circuit board 20
1 and the potential Vx on the conductor pattern 101
Is assumed to be detected by the non-contact potential detecting device. In addition, the conductor pattern 101
The sensor electrode 1 is provided at an arbitrary position opposite to the device main body 30.
The sensor electrode 1 is arranged as an outer one, but the sensor electrode 1 is placed on the vibrating body 2 via an insulator. A reference signal (basically a sine wave) 16 from the reference signal generator 4 passes through the driver 3 and a drive signal 19 to the vibrating body 2.
The sensor electrode 1 is vibrated by the vibrating body 2 in the direction orthogonal to the electrode plane. The device main body 30 is also provided with the IV conversion amplifier 5, but the voltage designated by the voltage control signal 15 from the control device 9 is D / V.
It is generated by the A converter 6 and then applied as a reference voltage (Vr) 11 to the non-inverting input terminal (+) of the IV conversion amplifier 5 (on the reference voltage Vr and the sensor electrode 1). The relationship with the voltage will be described later). As a result, when the sensor electrode 1 is placed in a vibrating state, the AC modulation signal 10 generated due to the change in the electrostatic capacitance between the sensor electrode 1 and the conductor pattern 101 is the IV conversion amplifier. 5. The voltage signal 12 is detected via the DC blocking capacitor 21. The voltage signal 12 is then synchronously detected by a lock-in amplifier (synchronous detector) 7. For the lock-in amplifier 7, for example, "interface" (published by CQ Publishing Co., January 1994, pp. .79-85),
By previously modulating the signal as the detection target with the reference signal for detection, the detection target signal buried in the noise can be detected in good condition. In this example,
The AC modulation signal 10 is the reference signal 1 from the reference signal generator 4.
Since it is generated based on 6, the reference signal 1
6 is used as it is as a reference signal to the lock-in amplifier 7. By the way, the synchronous detection signal 13 from the lock-in amplifier 7 is taken as a digital signal 14 via the A / D converter 8 into the control device 9 including a microprocessor as a main component, and is then subjected to predetermined processing. Is.

The configuration of the non-contact potential detecting device according to the present invention has been described above. The detecting operation is as follows. That is, first, the sensor electrode 1 is provided with the conductor pattern 10
By arranging the sensor electrode 1 and the conductor pattern 101 so as to face each other, the capacitance is coupled between the sensor electrode 1 and the conductor pattern 101.
In this state, the sensor electrode 1 is in a vibrating state. Due to this vibration, the coupling capacitance between the sensor electrode 1 and the conductor pattern 101 is changed by ΔC, and as a result, the current i expressed by the above-mentioned formula 2 is detected as the AC modulation signal 10. At that time, In addition, the voltage on the sensor electrode 1 is given from the IV conversion amplifier 5. More specifically, the AC modulation signal 10 to the IV conversion amplifier 5 mostly flows into the feedback resistor Rf and flows into the feedback resistor Rf because the input impedance of the OP amplifier (operational amplifier) 22 is high. The voltage represented by the product of the current i is obtained as the output voltage Vo of the OP amplifier 22.

[0020]

(Equation 4)

At this time, since the OP amplifier 22 itself works so that the potential difference between the inverting input terminal (-) and the non-inverting input terminal (+) becomes 0, the inverting input terminal (-).
The potential of is equal to that of the non-inverting input terminal (+). That is, the potential of the inverting input terminal (-) is the same as the reference voltage (Vr) from the D / A converter 6. Therefore, the potential difference (= Vx-Vr) between the sensor electrode 1 and the conductor pattern 101 can be variously changed depending on the voltage control signal 15 from the control device 9. Therefore, the reference voltage (Vr) is changed by the voltage control signal 15.
For example, the synchronous detection signal 13 may be taken into the control device 9 via the A / D converter 8 each time it is changed stepwise. However, when importing it,
It is necessary to wait for the response time determined by the time constant in the lock-in amplifier 7 before the synchronous detection signal 13 is taken in by the control device 9, but in any case, different reference voltages (Vr)
For each of them, the synchronous detection signal 13 may be taken into the control device 9 via the A / D converter 8.

As described above, the reference voltage (Vr) needs to be changed stepwise over a plurality of stages within a certain voltage range assumed in advance, but within that voltage range,
For example, the reference voltage (Vr) may be changed stepwise with the same voltage change. At that time,
It is expected that the smaller the voltage change, the higher the measurement accuracy, but on the other hand, it takes much time to capture the synchronous detection signal 13. In any case, the control device 9 sequentially obtains the synchronous detection signals 13 corresponding to the potential difference (= Vx-Vr) between the sensor electrode 1 and the conductor pattern 101. However, from the change in the magnitude of these synchronous detection signals 13, The distance between the sensor electrode 1 and the conductor pattern 101 can be estimated. That is, the rate of change a of the output voltage Vo of the IV conversion amplifier 5 when the reference voltage Vr is changed from Vr ₁ to Vr ₂ , for example, is obtained from Equation 4 as follows. .

[0023]

(Equation 5)

However, β in the equation is β = −ω · ε · S ·
Rf. Also, assuming that d >> Δd, β = β ′ ×
Assuming Δd, the rate of change a is expressed as a = β ′ / (d ² ). Therefore, the potential Vx on the conductor pattern 101 can be detected by correcting the previously measured error with respect to the distance d between the sensor electrode 1 and the conductor pattern 101. Even if the conductor portion is not exposed on the surface, the potential can be detected from the conductor (pattern) covered with a protective film such as a solder resist.

Here, assuming that the electronic component mounted on the printed circuit board 20 is a so-called TTLIC, T
An example of measuring the signal voltage of the TL IC will be described below, and a more specific numerical example will be described below. That is, if the diameter of each of the sensor electrode 1 and the conductor pattern 101 is 1.6 mm, and the distance between the sensor electrode 1 and the conductor pattern 101 is about 2 mm, the capacitance between them is 9 fF (f: femto (= 10 ^-15 )). If a piezoelectric element such as a piezo element is used for the vibrating body 2, the sensor electrode 1 can be vibrated with a vibration frequency of 4 kHz and a vibration amplitude Δd of about 3 μm. Therefore, ΔC is 0.0133 fF from Equation 3. By the way, since the power supply voltage of a general TTL IC is set to 5V, the maximum value of the input / output voltage is considered to be 5V or less.
Assuming that the reference voltage (Vr) to be applied to is within the voltage range of 0 to 5V, the value of the reference voltage (Vr) is, for example, 0.
V, 1V, 2V, 3V, 4V, 5V are sequentially changed in this order. If the voltage on the conductor pattern 101 is 3V and the voltage on the sensor electrode 1 is 0V, the magnitude of the AC modulation signal 10 when the sensor electrode 1 is in a vibrating state is From Equation 2 1
pA, therefore, if the feedback resistance Rf in the IV conversion amplifier 5 is set to 10 MΩ, as shown in FIG.
A voltage of 10 μV is obtained as the output of the IV conversion amplifier 5. Similarly, if the voltage on the sensor electrode 1 is 5V, a voltage of −6.68 μV is obtained as the output of the IV conversion amplifier 5 in the same manner.
As shown by the dotted line in FIG. 4, theoretically, when the voltage on the sensor electrode 1 is 3V, the output voltage of the IV conversion amplifier 5 should be 0V. , 0V, 1V, 2V, 3V, 4 on the sensor electrode 1
When sequentially changed in the order of V, 5V, the state deviates from the ideal state as shown by the solid line display in FIG. 4 due to various error factors. From the measured values for each of these 6 points, the voltage at the sensor electrode 1 (or the sensor electrode 1, conductor pattern 1
When the relationship between the voltage between 01) and the output voltage of the IV conversion amplifier 5 is obtained, the slope of the solid line shown in FIG.
36 × 10 ⁻⁶ is obtained, and as described using the above-mentioned Equation 5, the sensor electrode 1 and the conductor pattern 101 in this case are obtained.
It is known that the distance d between them is 2 mm. Therefore, the error data when the distance d measured in advance is 2 mm, that is, the error value of the detected voltage when the potential difference between the sensor electrode 1 and the conductor pattern 101 is 0, is known. To correct the detected voltage data (for example,
By subtracting), the reference voltage Vr when the originally detected voltage becomes 0 is known, and from this, the conductor pattern 1
The voltage Vx on 01 is required.

In the above description, the process of obtaining the inter-electrode distance from the relationship between the inter-electrode voltage and the detected voltage is explained as being estimated from the theoretical formula shown in Formula 5, but it is obtained by measuring in advance. It is acceptable. When the change rate of the detected voltage when the inter-electrode voltage is changed with the distance d as a parameter is obtained by actual measurement, improvement in measurement accuracy is expected.

Further, a non-contact potential detecting device in which auxiliary electrodes are arranged around the vicinity of the sensor electrode will be described. FIG. 5 shows an example of the configuration. As shown in the figure, the probe main body 32 is positioned manually with respect to the measured point, for example, like a probe of an oscilloscope, or by some mechanical means, and is shown as a cross-sectional state in this example. It has become a thing. It should be understood that the constituent elements within the probe body 32 should include the sensor electrode 1 and the vibrating body 2, and in this example, in addition to these constituent elements, an auxiliary electrode 31 is further provided inside the probe body 32. It has been set. The auxiliary electrode 31 is provided in the vicinity of the sensor electrode 1 in a predetermined manner, and FIG. 6 shows an arrangement of the auxiliary electrode 31 as a plane. As shown in the figure, in this example, the sensor electrode 1 has a circular shape, and the auxiliary electrode 31 has a donut shape and is arranged concentrically with the sensor electrode 1. The shape of the auxiliary electrode 31 may be, for example, a rectangular shape as long as the shape is such that it surrounds the sensor electrode 1 in the state of being closest to the electrode 1. Now, with respect to the auxiliary electrode 31, the same voltage as that of the sensor electrode 1 is applied thereto. In this example,
The specified voltage from the D / A converter 6 to the IV conversion amplifier 5 is applied via the buffer 35. Incidentally, the buffers 35 and 36 are provided for electrically isolating the IV conversion amplifier 5 and the auxiliary electrode 31, and their characteristics are the same, but they are indispensable components in the device configuration. It cannot be called an element.

The effect of the provision of the auxiliary electrode 31 is as follows. That is,
The sensor electrode 1 and the object to be measured are electrostatically coupled to each other, but the coupling state when the auxiliary electrode 31 is not present,
That is, the distribution of electric lines of force is as shown in FIG. As can be seen from this, the lines of electric force are not parallel in the peripheral portion of the electrode as in the central portion of the electrode, which is one factor of the above-mentioned measurement error factors. However, the distribution of electric force lines when the auxiliary electrode 31 is provided around the vicinity of the sensor electrode 1 is as shown in FIG. 7B, and the electric force lines are not disturbed at least at the peripheral portion of the electrode. As a result, the measurement error can be suppressed. In the configuration shown in FIG. 5, the auxiliary electrode 31 is arranged so as not to vibrate, but it may be arranged so as to be in a vibrating state together with the sensor electrode 1. Further, in this example, the signal processing circuit and the control device 9 as the device main body 30 are provided outside the probe main body 32, but only the signal processing circuit or the signal processing circuit and the control device 9 are also included in the probe main body 32. It can also be built in and integrated as a single unit. In the case of being integrated, not only the size of the device itself can be reduced, but also it is easy to handle.

Finally, the desirable tip construction of the probe main body 32 will be described. As shown in FIG. 8, a tip guard 33 is provided at the tip.
The tip guard 33 itself is made of rubber, plastic, or the like, and is made of an insulator having a suitable elasticity so as not to damage the solder, the conductor pattern, and the printed circuit board. By providing the tip guard 33, it is possible to easily position the probe main body 32 at the measured point during measurement. That is, the tip guard 33
When is pressed against the measurement site, the probe tip position does not deviate from the pressing position. If the tip guard 33 is made of a soft material such as rubber, the distance between the sensor electrode and the object to be measured may change. However, as described above, the distance between the electrodes may be corrected by the correction of the distance between the electrodes. The change does not cause an error.

[0030]

As described above, according to claims 1 to 6, the following effects can be obtained. Claims 1 and 2 provide a non-contact potential detection method and apparatus capable of detecting an unknown potential on a measured object with a sensor electrode without being affected by the distance between the measured object and the sensor electrode. Claim 3: As a miniaturized device, it is possible to obtain a non-contact potential detecting device capable of detecting an unknown potential on a measured object without being affected by the distance between the measured object and sensor electrodes. Claims 4 and 5: When the unknown potential on the measured object is detected by the sensor electrode in a non-contact state, the unknown potential on the measured object is more reliable without being affected by the distance between the measured object and the sensor electrode. A non-contact potential detection method and apparatus capable of detecting the non-contact potential are obtained. Claim 6: A non-contact potential detection device capable of more reliably detecting an unknown potential on an object to be measured without being influenced by the object to be measured and a distance between sensor electrodes as a miniaturized device. To be

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an example of a non-contact potential detecting device according to the present invention.

FIG. 2 is a diagram showing a principle configuration for implementing a non-contact potential detection method according to the present invention.

3 (a) and 3 (b) are views for explaining the principle of non-contact potential detection.

FIG. 4 is a diagram for explaining an operation in a specific example.

FIG. 5 is a diagram showing a configuration of an example of a non-contact potential detecting device according to the present invention in which an auxiliary electrode is arranged around the vicinity of a sensor electrode.

FIG. 6 is a diagram for explaining an arrangement mode of auxiliary electrodes provided around the vicinity of the sensor electrode.

7 (a) and 7 (b) are views for explaining the effect of the auxiliary electrode.

FIG. 8 is a diagram showing the desirable tip configuration of the probe body.

9A and 9B are views for explaining a non-contact potential detection method according to a conventional technique.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Sensor electrode, 2 ... Oscillator, 3 ... Driver, 4 ... Reference signal generator, 5 ... IV conversion amplifier, 6 ... D / A converter, 7 ... Lock-in amplifier, 8 ... A / D converter , 9 ...
Control device, 31 ... Auxiliary electrode, 32 ... Probe body, 33
… Tip guard, 101… Conductor pattern

Claims (6)

[Claims] 1. A non-contact potential detection method for detecting an unknown potential on an object to be measured in a non-contact state, wherein a potential difference is variable between the object to be measured and a sensor electrode. The sensor electrode arranged at an arbitrary position facing the object to be measured, while vibrating at a constant cycle in the direction orthogonal to the plane of the sensor electrode, every time the potential difference between the object to be measured and the sensor electrode is changed, The AC modulation signal generated by the vibration of the sensor electrode itself is detected from the sensor electrode, and from the change in the magnitude of the AC modulation signal detected corresponding to the potential difference, based on the theoretical formula or the error data measured in advance, The distance between the object to be measured and the sensor electrode is estimated, and the apparent potential on the object to be measured when the magnitude of the AC modulation signal becomes 0 is detected. Sensor electrode A non-contact potential detecting method, in which the apparent potential is corrected based on the distance between the two, so that the actual potential on the DUT can be detected in a non-contact state. 2. A non-contact potential detecting device for detecting an unknown potential on an object to be measured in a non-contact state, the sensor electrode being disposed at an arbitrary position facing the object to be measured, and the sensor electrode. By means of a vibration generating means for vibrating the sensor electrode in a direction perpendicular to the plane of the sensor electrode at a constant cycle, a DC voltage applying means for directly and indirectly applying a DC voltage to the sensor electrode in a changed state, and a DC voltage applying means. AC modulation signal detecting means for detecting an AC modulation signal from the sensor electrode each time the DC voltage applied to the sensor electrode is changed, and application of the DC voltage from the DC voltage applying means to the sensor electrode is controlled. On the other hand, based on a change in the magnitude of the AC modulation signal detected corresponding to the DC voltage from the AC modulation signal detecting means, based on a theoretical formula or error data actually measured in advance. When estimating the distance between the object to be measured and the sensor electrode and detecting the apparent potential on the object to be measured when the magnitude of the AC modulation signal becomes 0, the estimated object to be measured, A non-contact potential detecting device comprising at least a control / processing means for detecting the actual potential on the object to be measured in a non-contact state by correcting the apparent potential based on the distance between the sensor electrodes. 3. A non-contact potential detecting device for detecting an unknown potential on an object to be measured in a non-contact state, the non-contact potential detecting device being arranged at a position facing the object to be measured. An electrode, a vibration generating means for vibrating the sensor electrode at a constant cycle in a direction orthogonal to the plane of the sensor electrode, and a direct voltage applying means for directly and indirectly applying a direct voltage to the sensor electrode in a changed state, AC modulation signal detection means for detecting an AC modulation signal from the sensor electrode each time the DC voltage applied to the sensor electrode is changed by the DC voltage application means, and from the DC voltage application means to the sensor electrode. While controlling the application of the DC voltage, the theoretical expression or the actual measurement is made in advance from the change in the magnitude of the AC modulation signal detected by the AC modulation signal detecting means corresponding to the DC voltage. Based on the error data, the distance between the object to be measured and the sensor electrode is estimated, and the apparent potential on the object to be measured when the magnitude of the AC modulation signal becomes 0 is detected. At least the sensor electrode when it is configured to include at least a control / processing unit that detects the actual potential on the DUT in a non-contact state by correcting the apparent potential based on the distance between the DUT and the sensor electrode. The vibration generating means is configured as a non-contact potential detection probe that is housed and arranged inside the other end of a cylinder made of an insulating material, the one end of which is in contact with the object to be measured. Potential detection device. 4. A non-contact potential detection method for detecting an unknown potential on an object to be measured in a non-contact state, wherein the potential difference between the object to be measured and the sensor electrode is variable, and the sensor electrode is provided. In the state where the auxiliary electrode having the same potential as the sensor electrode is arranged around the vicinity of the sensor electrode, the sensor electrode placed at an arbitrary position facing the object to be measured is independently or together with the auxiliary electrode, is orthogonal to the plane of the sensor electrode. Each time the potential difference between the object to be measured and the sensor electrode is changed while vibrating in a constant cycle in the direction of From the change in the magnitude of the detected AC modulation signal, the distance between the object to be measured and the sensor electrode is estimated based on the theoretical formula or the error data measured in advance, and the The apparent potential on the measured object when the magnitude of the flow modulation signal becomes 0 is detected, and the apparent potential is corrected based on the estimated distance between the measured object and the sensor electrode. A non-contact electric potential detecting method in which an actual electric potential on a measured object is detected in a non-contact state. 5. A non-contact potential detecting device for detecting an unknown potential on a measurement object in a non-contact state, the non-contact potential detection device being arranged at an arbitrary position facing the measurement object and having the same potential in the vicinity of the vicinity. A sensor electrode in which an auxiliary electrode is disposed, a vibration generating means for vibrating the sensor electrode alone or together with the auxiliary electrode in a direction perpendicular to the plane of the sensor electrode at a constant cycle, and a direct current directly or indirectly to the sensor electrode. DC voltage applying means for applying the voltage in a changed state, and an AC modulation signal for detecting an AC modulation signal from the sensor electrode each time the DC voltage applied to the sensor electrode is changed by the DC voltage applying means. The detection means and the application of the direct current voltage from the direct current voltage applying means to the sensor electrode are controlled, while the alternating current detected by the alternating current modulation signal detecting means corresponding to the direct current voltage is detected. When the distance between the object to be measured and the sensor electrode is estimated from the change in the magnitude of the modulation signal based on the theoretical formula or the error data actually measured in advance, and the magnitude of the AC modulation signal becomes zero. In addition to detecting the apparent potential on the DUT, the actual potential on the DUT is detected in a non-contact state by correcting the apparent potential based on the estimated DUT and sensor electrode distance. A non-contact potential detection device including at least a control / processing means. 6. A non-contact potential detecting device for detecting an unknown potential on an object to be measured in a non-contact state, wherein the non-contact potential detecting device is arranged at an arbitrary position facing the object to be measured. And a sensor electrode in which auxiliary electrodes of the same potential are arranged in the vicinity of the vicinity, and vibration generating means for vibrating the sensor electrode alone or together with the auxiliary electrode in a direction perpendicular to the plane of the sensor electrode at a constant cycle, DC voltage applying means for directly or indirectly applying a DC voltage to the sensor electrode, and AC modulation from the sensor electrode each time the DC voltage applied to the sensor electrode is changed by the DC voltage applying means. AC modulation signal detecting means for detecting a signal and application of a DC voltage from the DC voltage applying means to the sensor electrode are controlled, while DC voltage from the AC modulation signal detecting means is controlled. From the change in the magnitude of the AC modulation signal detected corresponding to the pressure, the distance between the object to be measured and the sensor electrode is estimated based on the theoretical formula or the error data measured in advance, and the AC modulation signal After detecting the apparent potential on the measured object when the size becomes 0,
When it is configured to include at least a control / processing unit that detects the actual potential on the measured object in a non-contact state by correcting the apparent potential based on the estimated measured object and the distance between the sensor electrodes. , At least the sensor electrode and the vibration generating means are configured as a non-contact potential detection probe in a state of being housed inside the other end of a cylinder made of an insulating material, the one end of which is in contact with the object to be measured. A non-contact potential detecting device.