JPH03295475A - Surface potential measuring device - Google Patents

Abstract

PURPOSE:To attain exact measurement by fetching the counted value of a counting circuit when a stop signal is received and calculating the charged potential of an object to be measured from digital data and the control value. CONSTITUTION:A line of electric force emitted from the object to be measured is detected by a potential sensor device 1, and the electric field intensity is converted to a voltage signal and made to be a DC voltage signal with the process of a signal rectifying circuit 3. Then, a digital signal is obtained by an A/D converter 7. By an ultrasonic sensor device 2, the ultrasonic wave is generated and emitted to the object to be measured, and also the reflected ultrasonic wave is detected thereby. At this stage, the stop signal is obtained by a signal process circuit 4 from the received signal, and the time interval from the time when the signal is originated by the sensor device 2 till the time when it is received by the circuit 4, is measured by the counting circuit 6. The aforementioned sensor device 2 is excited, the circuits 4, 6 are reset, and the data from the converter 7 are fetched, then the counted value of circuit 6 is fetched when the stop signal from the circuit 4 is received. By means of calculating the charged potential of the object to be measured from the digital data and counted value by an arithmetic control part 8, the exact measurement can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a surface potential measuring device, and more particularly to a surface potential measuring device for measuring the charged potential of objects in printing factories, semiconductors, and the like.

[Conventional technology]

Conventional surface potential measuring devices are provided as devices for measuring the charged potential of objects present in printing factories, semiconductors, and the like.

FIG. 3 is a block diagram showing the configuration of a conventional surface potential measuring device.

The surface potential measuring device shown in FIG. 3 includes a potential sensor device 1 that detects lines of electric force radiated from an object to be measured and converts the electric field strength into a voltage signal, and a potential sensor device 1 that processes the voltage signal from the potential sensor device 1. It has a signal shaping circuit 3 that converts the voltage signal into a DC voltage signal according to the voltage signal, and a display section 5 that displays the output signal.

Here, the potential sensor device 1 includes a potential sensor 11 and a potential sensor drive circuit 12. Potential sensor 11
There are piezoelectric chitsuba type and rotating sector type, which receive electric lines of force radiated from the object to be measured and convert the electric field strength into an alternating current voltage signal. The potential sensor drive circuit 12 drives the potential sensor 1
make it work. The signal shaping circuit 3 includes an amplifier circuit 31, a rectifier circuit 32, and a smoothing circuit 33. The amplifier circuit 31 amplifies the output from the potential sensor 11. The rectifier circuit 32 rectifies the signal amplified by the amplifier circuit 31.

The smoothing circuit 33 smoothes the signal rectified by the rectifier circuit 32.

The operation of such a device will be explained.

The mechanical system of the potential sensor 11 in the potential sensor device 1 is driven by a potential sensor drive circuit 12 . The potential sensor 11 generates an AC voltage signal proportional to the charged voltage of the object to be measured. This AC voltage signal is amplified by an amplifier circuit 31 in the signal forming circuit 3 and supplied to a rectifier circuit 32. The signal rectified by the rectifier circuit 32 is smoothed by a smoothing circuit 33 and then provided to the display section 5. The display unit 5 is displayed using an analog pointer type meter, a digital display, or the like.

[Problem to be solved by the invention]

In the conventional surface potential measuring device described above, the potential sensor 11
However, since the electric field strength in the vicinity of the detection hole of the potential sensor 11 is measured, the output display also changes greatly when the measurement distance changes. This means that the measured value depends on the distance between the object to be measured and the potential sensor 11. Therefore, when measuring the charged potential of the object to be measured, it is necessary to keep the measuring distance constant at all times, and especially when carrying the surface potential measuring device and measuring various objects, the measuring distance must be measured visually. It is necessary to either match the measurements or create a dedicated jig for each object to be measured, which poses problems of low accuracy and lack of versatility.

SUMMARY OF THE INVENTION An object of the present invention is to provide a surface potential measuring device that can eliminate the drawbacks of the prior art and accurately measure the charged potential of an object to be measured.

[Means to solve the problem]

The surface potential measuring device of the present invention includes a potential sensor device that detects electric lines of force radiated from an object to be measured and converts the electric field strength into a voltage signal, and a potential sensor device that processes the voltage signal from the potential sensor device to convert it into a voltage signal. a signal shaping circuit that converts the DC voltage signal into a corresponding DC voltage signal; an analog-to-digital conversion circuit that converts the DC voltage signal output from the signal shaping circuit into a digital signal; an ultrasonic sensor device that detects ultrasonic waves emitted and reflected from an object to be measured; a signal processing circuit that obtains a stop signal from a signal received by the ultrasonic sensor device; a counting circuit for measuring the time from the start to the reception of the signal; and after exciting the ultrasonic sensor device and resetting the signal processing circuit and the counting circuit, the signal is taken in from the analog/digital circuit. The apparatus is characterized by comprising an arithmetic control section that takes in the count value of the counting circuit when receiving a stop signal from the processing circuit and calculates the charged potential of the object to be measured from the digital data and the count value.

The present invention takes in a signal related to the value of the electric line of force from a potential sensor device and a signal related to the value of the distance from the ultrasonic sensor device, calculates a predetermined value from the value of the electric force line and the distance value, and calculates the value of the measured object. We are looking for the actual charged potential of an object.

Another surface potential measuring device of the present invention includes a potential sensor device that detects lines of electric force radiated from an object to be measured and converts the electric field strength into a voltage signal, and a potential sensor device that processes the voltage signal from the potential sensor device. A signal shaping circuit that converts the voltage signal into a DC voltage signal according to the voltage signal, an analog-to-digital conversion circuit that converts the DC voltage signal output from this signal shaping circuit into a digital signal, and a signal shaping circuit that generates light and attaches it to the object to be measured in the air. a light sensor device that detects the light emitted to the object and reflected from the object to be measured; a signal processing circuit that obtains a stop signal from the signal received by the light sensor device; a counting circuit for measuring the time until receiving the reflected wave; and a counting circuit for exciting the light sensor device and resetting the signal processing circuit and counting circuit, and then taking in data from the analog/digital circuit. , comprising an arithmetic control unit that takes in a count value of the counting circuit when receiving a stop signal from a signal processing circuit, and calculates a charged potential of the object to be measured from the digital data and the count value. do.

The present invention takes in a signal related to the value of electric lines of force from a potential sensor device and a signal related to a value of distance from a light sensor device, calculates a predetermined value from the value of electric lines of force and the value of distance, and determines the value of the measured object. We are looking for the actual charging potential of .

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the surface potential measuring device of the present invention. Note that in FIG. 1, the same components as those in FIG. 3 are given the same reference numerals and explained.

The surface potential measuring device shown in FIG. 1 includes a potential sensor device 1 that detects lines of electric force radiated from an object to be measured and converts the electric field strength into a voltage signal, and processes a voltage signal from the potential sensor device 1. a signal shaping circuit 3 that converts the DC voltage signal into a DC voltage signal according to the voltage signal; an analog-to-digital conversion circuit 7 that converts the DC voltage signal output from the signal shaping circuit 3 into a digital signal; an ultrasonic sensor device 2 that detects ultrasonic waves emitted to an object to be measured and reflected from the object; and the ultrasonic sensor device 2
a signal processing circuit 4 that obtains a stop signal from the signal received by the
After exciting the counting circuit 6 for measuring the time from when the ultrasonic sensor device 2 emits a sonic signal to when it receives the sonic signal, and after exciting the ultrasonic sensor device 2 and resetting the signal processing circuit 4 and the counting circuit 6. , when the data from the analog/digital circuit 7 is taken in, the signal processing circuit 6
The control section 8 is configured to take in the count value of the counting circuit 6 when receiving a stop signal from the counter, and calculate the charged potential of the object to be measured from the digital data and the count value.

Here, the potential sensor device 1 includes a potential sensor 11 and a potential sensor drive circuit 12. Potential sensor 11
There are piezoelectric chopper type and rotating sector type, which receive electric lines of force radiated from the object to be measured and convert the electric field strength into an AC voltage signal. The potential sensor drive circuit 12 drives the potential sensor 1
make it work. The signal shaping circuit 3 includes an amplifier circuit 31, a rectifier circuit 32, and a smoothing circuit 33. The amplifier circuit 31 amplifies the output from the potential sensor 11. The rectifier circuit 32 rectifies the signal amplified by the amplifier circuit 31.

The smoothing circuit 33 smoothes the signal rectified by the rectifier circuit 32.

The ultrasonic sensor device 2 also includes an ultrasonic sensor 21 that generates ultrasonic waves, radiates them to an object in the air, and detects the ultrasonic waves reflected from the object, and an It consists of an ultrasonic sensor drive circuit 22 that excites the ultrasonic sensor 21 according to a command. The signal processing circuit 4 includes a voltage amplification circuit 41 that amplifies the signal received by the ultrasonic sensor 21, and a peak hold circuit that peak-bolds the voltage output from the voltage amplification circuit 41 and is reset by a reset signal from the arithmetic control unit 8. It consists of 42. The counting circuit 6 includes a counter 61 that is reset by a reset signal from the arithmetic control unit 8 and measures the time from when the ultrasonic sensor device 2 emits a sonic signal to when it receives the sonic signal;
and an oscillator 62 that provides a reference pulse. The arithmetic control unit 8 includes a central processing unit 81 that performs arithmetic processing,
It includes a ROM 82 that stores necessary programs, and a RAM 12 that stores necessary processing programs and constants.

The operation of the embodiment having such a configuration will be explained.

FIG. 2 is a time chart shown to explain the operation of the above embodiment, and shows signals at various locations in the circuit.

2) Time t when the drive pulse from the central processing unit 81 of the arithmetic control unit 8 is high. -tl), ultrasonic sensor 21
A drive signal (see Fig. 2) is sent from the ultrasonic sensor drive circuit 22.
Time t. -1+), it vibrates.

At this time, the amplifier circuit 41 receives a drive signal (time t in FIG. 2).

-1+) and outputs a square wave with input j- (Fig. 2 ■ Time t.~↑1). However, since the peak hold circuit 42 has been reset during this time, it does not respond (
Figure 2 ■Timekeeper. -1+). When the ultrasonic wave is reflected by the object to be measured and returns, a signal is generated in the ultrasonic sensor 21 (Fig. 2). The signal is amplified by the amplifier circuit 41 and outputs an amplified signal (time t2 to t3 in Fig. 2). Figure ■ Time t2-t3).

The signal amplified by this amplifier circuit 41 is
The peak is held in the peak hold circuit 42. The central processing unit 81 of the arithmetic control unit 8 reads the number of pulses counted by the counter 61 by the signal given from the peak hold circuit 42 at time t2 in FIG.

The central processing unit 81 reads a processing program from the ROM 9 and performs the following processing.

When the output from the potential sensor 11 is V1 and the measurement distance to the object to be measured is d, the charged potential E of the object to be measured is E=f
(v, d)...given by (1).

Therefore, the charged potential E of the object to be measured is
It is expressed as a function using the output V from the V and the measurement side nd up to the object to be measured as parameters.

In other words, in the embodiment of the present invention, the time from when an ultrasonic wave is emitted to when it is received can be measured by counting it with the counter 61, and the measurement distance d can be obtained. This means that even if the measurement distance changes, it can be determined accurately.

In the above embodiment, ultrasonic waves were used to measure distance, but light may also be used. That is, another embodiment includes a counting circuit that measures the time from when the light sensor device emits a light signal to when it receives the light signal, and after exciting the light sensor device and resetting the signal processing circuit and the counting circuit, When the data from the analog/digital circuit 7 is taken in, the count value of the counting circuit 6 when receiving the stop signal from the signal processing circuit 6 is taken in, and the value of the measured object is calculated from the digital data and the count value. It is composed of an arithmetic control section 8 that calculates a charging potential.

This embodiment also provides the same effects as the first embodiment.

〔Effect of the invention〕

As explained above, the present invention is capable of acquiring measured values from electric field strength measurement using a potential sensor device and distance measurement using an ultrasonic sensor device, and performing calculation processing based on these values to determine the charging potential. Even if the measurement distance changes, the charged potential of the object to be measured can always be accurately determined, the accuracy is high, no jig is required for measurement, and there is versatility.

As explained above, the present invention is capable of acquiring measured values from electric field strength measurement with a potential sensor device and distance measurement with a light sensor device, and performing calculation processing based on these values to determine the charged potential. Even if the distance changes, the charged potential of the object to be measured can always be accurately determined, the accuracy is high, no jig is required for measurement, and there is versatility.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing one embodiment of the surface potential measuring device of the present invention, Fig. 2 is a time chart shown to explain the operation of the embodiment of Fig. 1, and Fig. 3 is a block diagram of the conventional device. It is a block diagram. DESCRIPTION OF SYMBOLS 1... Potential sensor device, 2... Ultrasonic sensor device, 3... Signal shaping circuit, 4... Signal processing circuit, 6... Counting circuit, 7... Analog-digital converter. , 8... Arithmetic control unit.

Claims (2)

[Claims] (1) A potential sensor device that detects electric lines of force radiated from an object to be measured and converts the electric field strength into a voltage signal, and a DC voltage signal that processes the voltage signal from the potential sensor device and generates a DC voltage signal according to the voltage signal. A signal shaping circuit that converts the DC voltage signal output from the signal shaping circuit into a digital signal, and an analog-to-digital conversion circuit that generates ultrasonic waves and radiates them to the object to be measured in the air. an ultrasonic sensor device that detects ultrasonic waves reflected from an object; a signal processing circuit that obtains a stop signal from the signal received by the ultrasonic sensor device; After exciting the counting circuit for measuring time and the ultrasonic sensor device and resetting the signal processing circuit and counting circuit, the signal processing circuit stops when data is taken in from the analog/digital circuit. A surface potential measuring device comprising: an arithmetic control section that takes in a count value of the counting circuit when receiving a signal, and calculates a charged potential of the object to be measured from the digital data and the count value. (2) A potential sensor device that detects electric lines of force radiated from an object to be measured and converts the electric field strength into a voltage signal, and a DC voltage signal that processes the voltage signal from the potential sensor device and corresponds to the voltage signal. A signal shaping circuit that converts the DC voltage signal output from the signal shaping circuit into a digital signal, and an analog-to-digital conversion circuit that generates light and radiates it toward the object to be measured in the air. a light sensor device that detects light reflected from the
a signal processing circuit that obtains a stop signal from a signal received by the light sensor device; a counting circuit that measures the time from when the ultrasonic sensor device emits light until it receives a reflected wave thereof; and the light sensor device. , and after resetting the signal processing circuit and the counting circuit, taking in data from the analog/digital circuit,
The method is characterized by comprising an arithmetic control unit that takes in the count value of the counting circuit when receiving a stop signal from the signal processing circuit, and calculates the charged potential of the object to be measured from the digital data and the count value. Surface potential measuring device.