TW201930897A - Non-contact static electricity measuring device - Google Patents

Abstract

The invention provides a non-contact type electrostatic measuring device, which comprises: a sensing electrode, a switching circuit and a data capturing unit. The sensing electrode is configured to sense the static quantity of the object to be tested in a non-contact manner, the switch circuit is coupled to the sensing electrode, the switch circuit has an electronic switch and a detecting capacitor connected in parallel with the electronic switch, and the electronic switch has a short circuit In the open state, the detecting capacitor charges the static electricity sensed by the sensing electrode to detect the capacitance outputting an electrostatic voltage signal; in the short circuit state, the sensing electrode is used The electronic switch is coupled to a biasing end, and the detecting capacitor is discharged by the electronic switch; the data capturing unit is coupled to the switching circuit to obtain an electrostatic voltage signal for more accurate measurement.

Description

Non-contact electrostatic measuring device

The invention relates to a non-contact type electrostatic measuring device, in particular to a non-contact type electrostatic measuring device using an electronic switch.

Press, Electro Static Discharge, referred to as ESD. Electrostatic discharge can cause current thermal effects, such as sparks (such as causing fire and explosion, parts breakdown or burnout) and electromagnetic field effects (electromagnetic interference). Therefore, for electronic products, it can be avoided through detection and prevention measures. Damage caused by electrostatic discharge.

In order to measure static electricity, there is a contact static electricity meter or a non-contact electrometer to measure the static electricity of electronic products or equipment to monitor whether the amount of static electricity has an influence on electronic products. Among them, the contact electrostatic meter uses probes and The capacitance between the charged bodies is directly induced and amplified to show the electrostatic voltage, but in some cases where it cannot be contacted, it is not convenient to use. The non-contact electrometer mainly connects the probe to the charged body, and uses the distorted electric field generated between the probe and the charged body to test the surface potential of the charged body, which is essentially the test of the electric field on the surface of the charged body, and the contact static electricity. Compared with the input capacitance and input resistance, the measurement accuracy is higher.

The current non-contact electrometer is like a rotary vane electrometer, which mainly uses a motor to drive a metal blade to rotate, so that the metal blade is exposed or shielded with respect to an external electric field, so as to be charged or discharged, and then charged and discharged. During the process, the value is read and the electrostatic value is measured. However, this type of electrometer has a mechanical aging problem due to the large energy consumption of the motor, and the response speed is slow and cannot be monitored for a long time.

Therefore, how to design a non-contact type electrostatic measuring device to improve the aforementioned shortcomings is one of the problems to be solved by the related industry.

In order to solve the above problems, the present invention discloses a non-contact type electrostatic measuring device, which uses an electronic switch to charge and discharge a capacitor, and extracts an electrostatic voltage signal to observe the change thereof, so that the measurement is more accurate, and the mechanical measurement is solved. The problem that arises.

To achieve the above objective, an embodiment of the present invention provides a non-contact type electrostatic measuring device, comprising: a sensing electrode, a switching circuit, an amplifier, and a data capturing unit. The sensing electrode is configured to sense a test object in a non-contact manner, and the switch circuit is coupled to the sensing electrode. The switch circuit has an electronic switch and a capacitor electrically connected to the electronic switch. When the electronic switch is in an open state, the switch can be The capacitor is charged so that the capacitor outputs a voltage signal, the amplifier is coupled to the electronic switch unit, the amplifier is configured to receive the voltage signal, and the data capture unit is coupled to the amplifier.

Thereby, the electronic switch of the invention has a high switching frequency, which is beneficial for capturing more signal data for more accurate measurement.

In addition, the present invention does not require the use of mechanical measurements, thereby eliminating the disadvantages of poor precision resulting from mechanical aging.

Further, the present invention further includes a holding circuit coupled between the amplifier and the data acquisition unit. When the input static voltage is positive or negative, the holding circuit maintains its highest voltage or the lowest voltage value for easy observation and judgment.

The exemplary embodiments of the present invention are described in detail below with reference to the accompanying drawings, and are not intended to limit the technical principles of the invention to the specific disclosed embodiments, and the scope of the invention is limited only by the scope of the claims Equivalent.

As shown in FIG. 1 to FIG. 3, the non-contact electrostatic measuring device of the present invention comprises a sensing electrode 10, a switching circuit 20 and a data capturing unit 30. The sensing electrode 10 is used for a metal sheet. The object to be tested 100 is sensed in a non-contact manner to sense the amount of static electricity of the object to be tested 100. among them:

The object to be tested 100 is electrostatically charged to cause the sensing electrode 10 to induce a positive or negative static voltage.

The switch circuit 20 includes an electronic switch 21 and a detecting capacitor 22, and the electronic switch 21 is disposed in parallel with the detecting capacitor 22, and the electronic switch 21 and one end of the detecting capacitor 22 are coupled to the sensing electrode 10, and the electronic circuit The switch 21 and the other end of the detecting capacitor 22 are coupled to a bias terminal 23, wherein the electronic switch 21 can be a bipolar transistor or a metal oxide semiconductor field effect transistor. The electronic switch 21 has a short-circuit state and a disconnected state; in the open state, the detecting capacitor 22 charges the static electricity sensed by the sensing electrode 10 to the detecting object 100, so that the detecting capacitor 22 outputs an electrostatic voltage signal; In the short-circuit state, the sensing electrode 10 is coupled to the bias terminal 23 via the electronic switch 21, and the detecting capacitor 22 is discharged by the electronic switch 21, so that the charge accumulated on the detecting capacitor 22 is biased. 23 Exclude and reset to a fixed bias to complete the reset step for the next measurement. The operating frequency of the electronic switch 21 between the open circuit and the short circuit state can reach 20 MHz.

The data capture unit 30 is coupled to the switch circuit 20 to obtain the electrostatic voltage signal. The data capture unit 30 can output the electronic switch 21 of the digital signal control switch circuit 20 to switch between the open state and the short circuit state, so as to perform charge and discharge of the detection capacitor 22. The data capture unit 30 can be coupled to a host to enable the electrostatic voltage signal to be edited and stored by the data capture unit 30 for display and display on the host. In the embodiment of the present invention, the data capture unit 30 is configured. Design the interface for the LabVIEW program, but not limited to it.

The present invention further includes an amplifier 40 coupled between the switch circuit 20 and the data capture unit 30, and correspondingly amplifying the electrostatic voltage signal into an electrostatic amplification signal, and transmitting the data to the data capture unit 30. In the embodiment of the present invention, the amplifier 40 has a positive terminal 41, a negative terminal 42, an output terminal 43, a first resistor 44, and a second resistor 45. The two ends of the first resistor 44 are respectively coupled to The switch circuit 20 and the negative terminal 42 are respectively coupled to the negative terminal 42 and the output terminal 43 respectively, and the positive terminal 41 is coupled to a reference voltage terminal 46 to form an inverse amplifying circuit structure. The second resistor 45 is a variable resistor for adjusting the magnification of the amplifier 40.

Accordingly, the present invention transmits and discharges the detecting capacitor 22 through the open circuit and short circuit switching of the electronic switch 21 to output an electrostatic voltage signal to the data capturing unit 30 for accurately measuring the object to be tested 100. The amount of static electricity. Moreover, since the invention adopts the non-contact measurement, the accuracy is high, and the problem of the motor wear is effectively used as the static change of the test object 100 for a long time.

FIG. 3 is another embodiment of the present invention. The main purpose is to couple a holding circuit 50 between the data capturing unit 30 and the amplifier 40, which can effectively hold the value for observation and improve measurement accuracy. The holding circuit 50 is a highest voltage holding circuit or a minimum voltage holding circuit. In the embodiment of the present invention, the holding circuit 50 includes a highest voltage holding unit 51 and a minimum voltage holding unit 52, according to which the object to be tested is 100 is input to the switching circuit 20 by a positive static voltage input or a negative static voltage, and the value of the highest voltage or the lowest voltage can be maintained by the holding circuit 50, so as to maintain the numerical value, thereby achieving an effect of observation.

For example, when the object to be tested 100 is input to the switching circuit 20 with a positive static voltage, the detecting capacitor 22 is gradually charged, and the voltage value outputted by the amplifier 40 is gradually increased by the level voltage, and when the detecting capacitor 22 is fully charged, The maximum output voltage, therefore, is maintained by the highest voltage holding unit 51 of the holding circuit 50 to observe its change.

Moreover, when the object to be tested 100 is input to the switch circuit 20 with a negative static voltage, when the detecting capacitor 22 is gradually charged, the output voltage of the amplifier 40 gradually decreases from the level voltage to a minimum value, and when it is discharged, It gradually rises to the level voltage again, and when it is recharged, it drops to the lowest value again. Therefore, the lowest value is a meaningful value at this time, so it is necessary to keep the lowest voltage holding unit 52 of the circuit 50 to keep its voltage value at a minimum. Value for observation.

Therefore, the present invention uses the electronic switch 21 and charges and discharges the detecting capacitor 22 between switching switches, which is beneficial to extract more signal data for more accurate measurement.

In addition, the present invention uses the sensing electrode 10 to sense the object to be tested 100 in a non-contact manner, and the device does not need to use a mechanical measuring voltage, thereby avoiding the disadvantage of poor precision caused by mechanical aging or fatigue.

While the invention has been described in terms of a preferred embodiment, the various embodiments may The above embodiments are merely illustrative of the invention and are not intended to limit the scope of the invention. All modifications or changes made without departing from the spirit of the invention are within the scope of the invention.

100‧‧‧Test object

20‧‧‧Switch circuit

22‧‧‧Detecting capacitance

30‧‧‧Information acquisition unit

41‧‧‧ Positive

43‧‧‧ Output

45‧‧‧second resistance

50‧‧‧keeping circuit

52‧‧‧Minimum voltage holding unit

10‧‧‧Sensing electrode

21‧‧‧Electronic switch

23‧‧‧ biased end

40‧‧‧Amplifier

42‧‧‧ negative end

44‧‧‧First resistance

46‧‧‧reference voltage terminal

51‧‧‧Highest voltage holding unit

1 is a schematic structural view of a non-contact type electrostatic measuring device according to the present invention, showing that the electronic switch is in an open state. 2 is a schematic structural view of the non-contact type electrostatic measuring device of the present invention, showing that the electronic switch is in an on state. FIG. 3 is a schematic structural diagram of another embodiment of the present invention. The display holding circuit is coupled between the amplifier and the data acquisition unit.

Claims (9)

A non-contact type electrostatic measuring device, comprising: a sensing electrode for sensing a static quantity of a test object in a non-contact manner; a switching circuit coupled to the sensing electrode, the switching circuit An electronic switch having a detection capacitor and a parallel connection with the detection capacitor, the detection capacitor and the electronic switch having one end coupled to the sensing electrode and the other coupled to a bias end, the electronic switch having a short circuit state and an open circuit state, wherein the detecting capacitor charges the static electricity sensed by the sensing object by the sensing electrode, so that the detecting capacitor outputs an electrostatic voltage signal, In the short circuit state, the sensing electrode is coupled to the biasing end by the electronic switch, and the detecting capacitor is discharged by the electronic switch; and a data capturing unit is coupled to the electronic switch, To obtain the electrostatic voltage signal. The non-contact electrostatic measuring device of claim 1, further comprising an amplifier coupled between the switching circuit and the data capturing unit, and correspondingly amplifying the electrostatic voltage signal into an electrostatic amplification signal And then transferred to the data capture unit. The non-contact type electrostatic measuring device according to claim 2, wherein the amplifier has a positive terminal, a negative terminal, an output terminal, a first resistor and a second resistor, and the two ends of the first resistor are respectively The two ends of the second resistor are coupled to the negative terminal and the output terminal, and the positive terminal is coupled to a reference voltage terminal to form an inverse amplifying circuit. structure. The non-contact type electrostatic measuring device according to claim 3, wherein the second resistor is a variable resistor, and the magnification of the amplifier can be adjusted. The non-contact electrostatic measuring device of claim 3, further comprising a holding circuit coupled between the amplifier and the data capturing unit. The non-contact type electrostatic measuring device according to claim 5, wherein the holding circuit is a highest voltage holding circuit. The non-contact type electrostatic measuring device according to claim 5, wherein the holding circuit is a lowest voltage holding circuit. The non-contact type electrostatic measuring device of claim 5, wherein the holding circuit comprises a highest voltage holding unit and a lowest voltage holding unit. The non-contact type electrostatic measuring device according to claim 1, wherein the electronic switch is selected from any one of a bipolar transistor and a metal oxide semiconductor field effect transistor.