CN108267648B

CN108267648B - Detection equipment with electrostatic protection function

Info

Publication number: CN108267648B
Application number: CN201611262879.2A
Authority: CN
Inventors: 陈麒任; 刘文良
Original assignee: To Mao Electronics Suzhou Co ltd
Current assignee: To Mao Electronics Suzhou Co ltd
Priority date: 2016-12-30
Filing date: 2016-12-30
Publication date: 2020-07-07
Anticipated expiration: 2036-12-30
Also published as: CN108267648A

Abstract

A detection device with an electrostatic protection function is suitable for detecting a device to be detected. The detection equipment with the electrostatic protection function comprises a test circuit, a signal switch circuit, a detection module and a control module. The signal switch circuit is electrically connected with the test circuit and the equipment to be tested. The detection module is electrically connected with the signal switch circuit. The detection module comprises an electrostatic protection element, a sensing resistor and a differential circuit. The electrostatic protection element is used for generating a current signal according to the electrostatic discharge ESD state of the equipment to be tested. The sensing resistor is used for generating a sensing voltage according to the current signal. The differential circuit is used for outputting a first output voltage according to the sensing voltage. The control module is electrically connected with the signal switch circuit and the detection module. The control module selectively conducts the signal switch circuit according to the first output voltage.

Description

Detection equipment with electrostatic protection function

Technical Field

The present disclosure relates to inspection devices, and particularly to an inspection device with electrostatic protection.

Background

A process of testing is often required before the product is formally shipped. For testing Liquid Crystal Module (LCM), due to the requirements of the production line of the client, the tested objects are different, and the frequency of replacing the tested objects is high. In this situation, if the protection measures for the electrostatic discharge on the production line are not perfect, the detection device and the device under test are easily damaged.

Although in the field of testing, electrostatic discharge protection devices are commonly used to prevent the testing equipment and the device under test from being damaged by electrostatic discharge. However, the esd protection devices are mostly disposed in parallel on the transmission path of the test, and when the electrostatic energy is too large or the discharge time is too long, the detection device and the device under test are still damaged by the electrostatic discharge.

Disclosure of Invention

The present invention is directed to a detection apparatus, wherein when an electrostatic voltage is detected, a protection mechanism is automatically activated to disconnect a transmission path, so as to effectively isolate an electrostatic discharge phenomenon on the transmission path, thereby protecting the detection apparatus.

According to an embodiment of the present invention, a testing apparatus with electrostatic protection function is disclosed, which is suitable for testing a device under test. The detection equipment with the electrostatic protection function comprises a test circuit, a signal switch circuit, a detection module and a control module. The signal switch circuit is electrically connected with the test circuit and the equipment to be tested. The detection module is electrically connected with the signal switch circuit. The detection module comprises an electrostatic protection element, a sensing resistor and a differential circuit. The electrostatic protection element is used for generating a current signal according to an electrostatic discharge (ESD) state of the equipment to be tested. The sensing resistor is used for generating a sensing voltage according to the current signal. The differential circuit comprises a plurality of resistors, and is used for adjusting the sensing voltage according to the resistance values of the plurality of resistors so as to output a first output voltage. The control module is electrically connected with the signal switch circuit and the detection module. The control module selectively conducts the signal switch circuit according to the potential of the first output voltage.

In summary, in the detection apparatus of the present invention, the detection module can detect the electrostatic discharge, and the control module controls the signal switch circuit to be turned on. Therefore, when the electrostatic discharge phenomenon occurs, the switch circuit can be set to be non-conductive, so that the electrostatic discharge on the transmission path is effectively isolated, and the effect of protecting the detection equipment is further achieved.

The invention is described in detail below with reference to the drawings and specific examples, but the invention is not limited thereto.

Drawings

FIG. 1 is a circuit architecture diagram of a testing apparatus with electrostatic discharge protection according to an embodiment of the present invention;

FIG. 2 is a timing diagram illustrating voltage variation according to an embodiment of the present invention.

Wherein the reference numerals

1: detection equipment with electrostatic protection function

2: device under test

10: detection module

101: electrostatic protection element

103: sensing resistor

105: differential circuit

1051: a first resistor

1052: second resistance

1053: third resistance

1054: fourth resistor

1055: zener diode

12: control module

120: switching element

121: processor with a memory having a plurality of memory cells

123: logic grid

125: light emitting diode

14: test circuit

16: signal switch circuit

Va, Ve, V1: voltage of

Vb: first output voltage

Vc: control voltage

Vd: second output voltage

OP 1: differential amplifier

R: resistance (RC)

S1, S2, S3: node point

t1, t2, t 3: point in time

Detailed Description

The detailed features and advantages of the present invention are described in detail in the following embodiments, which are sufficient for anyone skilled in the art to understand the technical contents of the present invention and to implement the present invention, and the objectives and advantages related to the present invention can be easily understood by anyone skilled in the art according to the disclosure of the present specification, the scope of the claims and the accompanying drawings. The following examples further illustrate aspects of the present invention in detail, but are not intended to limit the scope of the invention in any way.

Referring to fig. 1, fig. 1 is a circuit architecture diagram of a detection apparatus with an electrostatic protection function according to an embodiment of the invention. As shown in fig. 1, a detection device 1 having an electrostatic protection function is applied to a device under test 2. In one example, the device under test 2 is a Liquid Crystal Module (LCM) to be tested, and the detecting device with electrostatic protection 1 is used for detecting the Liquid Crystal Module (LCM) to be tested. In practice, the device to be tested 2 is a semi-finished product on the production line, and the product can be shipped only by the test program of the detection device 1 with the electrostatic protection function. The detecting device 1 with electrostatic protection function includes a detecting module 10, a control module 12, a testing circuit 14 and a signal switching circuit 16. The signal switch circuit 16 is electrically connected to the test circuit 14 and the device under test 2. The test circuit 14 sends a test signal through the signal switch circuit 16, so as to test whether the device under test 2 can operate normally. The detection module 10 is electrically connected to the signal switch circuit 16, and the control module 12 is electrically connected to the signal switch circuit 16 and the detection module 10. The detection module 10 includes an electrostatic discharge protection device 101, a sensing resistor 103, and a differential circuit 105. The ESD protection device 101 is configured to generate a current signal I1 according to an electrostatic discharge (ESD) state of the device under test 2. The sensing resistor 103 is used for generating a sensing voltage according to the current signal I1. The control module 12 selectively turns on the signal switching circuit 16 according to the first output voltage Vb.

Specifically, in the initial state, when the detection device 1 with the electrostatic protection function starts to detect the device under test 2, the signal switch circuit 16 is in the on state, so that the test circuit 14 can transmit the test signal to the device under test 2 to determine whether the function of the device under test 2 is normal. However, during the testing process, the device under test 2 may generate an electrostatic discharge (ESD) phenomenon. When the ESD event occurs, a voltage Va is generated at one end of the signal switch circuit 16, so that the ESD protection device 101 generates a current signal I1. When the current signal I1 passes through the sensing resistor 10, the sensing resistor 10 generates a potential difference, i.e., the sensing voltage. The differential circuit includes a first resistor 1051, a second resistor 1052, a third resistor 1053, and a fourth resistor 1054. The differential circuit 105 is used for adjusting the sensing voltage according to the resistance values of the resistors to output a first output voltage Vb. The control module 12 further selectively turns on the signal switch circuit 16 according to the potential of the first output voltage Vb. In practice, the ESD protection device 101 is a Transient Voltage Suppression (TVS) diode, which is generally connected in parallel with a circuit device to be protected in a circuit architecture, and the basic operation principle is to conduct most of the ESD current to the ground to prevent the device from being affected by a high voltage transient voltage. In one embodiment, the signal switch circuit 16 is composed of high-speed signal switches.

By selectively turning on the signal switch circuit 16, when the device under test 2 generates electrostatic discharge (ESD), the signal switch circuit 16 is set to be turned off to prevent ESD from being introduced and damaging the device under test 1 with electrostatic protection function. In a practical example, when the energy of ESD is very small or close to zero, the generated current signal I1 is weak, and the sensing voltage is also very small or close to zero. At this time, the signal switching circuit 16 is still in the on state. On the contrary, when the ESD is raised from the minimum energy state to the certain energy state, the generated current signal I1 is relatively large, the sensing voltage is also large, and the signal switch circuit 16 is in the non-conducting state.

In one embodiment, as shown in fig. 1, the control module 12 includes a switch element 120, a processor 121 and a logic gate 123. The switching element 120 is electrically connected to the signal switching circuit 16. The processor 121 is configured to provide a second output voltage Vd and adjust the output second output voltage Vd according to the level of the first output voltage Vb. In one example, the processor 121 is a Central Processing Unit (CPU), a microcontroller unit (MCU) or other equivalent components with processing functions. The logic gate 123 is electrically connected to the switching element 120. The logic gate 123 outputs the control voltage Vc according to the potential of the second output voltage Vd and the potential of the first output voltage Vb, so as to control the switch element 120 to selectively turn on the signal switch circuit 16. The potential of the control voltage Vc is controlled by the potential of the second output voltage Vd and the potential of the first output voltage Vb. When the control voltage Vc is at the first potential, the switching element 120 is enabled to turn off the signal switching circuit 16, and when the control voltage Vc is at the second potential, the switching element 120 is disabled to turn on the signal switching circuit 16. The enabling means that the current path of the switching element 120 is turned on, and the disabling means that the current path of the switching element 120 is turned off. In this embodiment, the logic gate 123 is an OR gate (OR gate). When the two input voltages (e.g., the first output voltage Vb and the second output voltage Vd) of the logic gate 123 are opposite in potential, the control voltage Vc output by the logic gate 123 is at a high potential, and conversely, the control voltage Vc is at a low potential.

Referring to fig. 1 and fig. 2 together, fig. 2 is a timing diagram illustrating a voltage variation according to an embodiment of the invention. Specifically, fig. 2 shows the voltage variation of each node when the detection device 1 with the electrostatic protection function detects the device under test 2. As shown in fig. 1 and fig. 2, in an embodiment, at a time point t1, an electrostatic discharge (ESD) phenomenon occurs in the device under test, and static electricity is introduced from the outside into the detection device 1 with an electrostatic protection function to generate a transient surge, i.e., a voltage Va. At this time, the electrostatic protection device 101 is configured to discharge electrostatic energy to generate a current signal I1. When the current signal I1 passes through the sensing resistor 103 to generate a sensing voltage, the differential circuit 105 performs voltage conversion according to the sensing voltage, and outputs a first output voltage Vb. At this time, the potential of the first output voltage Vb is adjusted to the first potential. The first output voltage Vb is further transmitted to the processor 121 and the logic gate 123. When the processor 121 receives the first output voltage Vb having the first potential, it is known that an electrostatic discharge (ESD) phenomenon occurs in the device under test 2. At this time, the processor 121 adjusts the potential of the output second output voltage Vd to the second potential. In this embodiment, the first potential is a high potential, and the second potential is a low potential, but the invention is not limited thereto.

Since the first output voltage Vb and the second output voltage Vd received by the logic gate 123 have different potentials, the potential of the output voltage Vc is a high potential based on the element characteristics of the logic gate 123. When the switching element 120 receives the control voltage Vc at a high level and is enabled, the current path thereof is turned on. At this time, the signal switch circuit 16 is switched from the initial conducting state to the non-conducting state due to the conduction of the current path of the switch element 120. More specifically, as shown in fig. 1, the signal switch circuit 16 has a plurality of nodes S1, S2 and S3 therein and is electrically connected to one end of the resistor R. The other end of the resistor R is electrically connected with a voltage V1. When the current path of the switching element 120 is not conducting, the signal switching circuit 16 switches to connect the nodes S1 and S2, so that the current path between the testing device 1 with electrostatic protection function and the device 2 to be tested is conducting. Conversely, when the current path of the switching element 120 is turned on, the signal switching circuit 16 switches to connect the nodes S1 and S3, so that the current path between the device under test 1 and the device under test 2 with electrostatic protection function is blocked. In one embodiment, the switch element 120 may be a Bipolar Junction Transistor (BJT), a Metal-Oxide-Semiconductor Field-effect transistor (MOSFET), or other equivalent element with a switching function.

When the signal switch circuit 16 is not turned on, the signal switch circuit 16 is in an open state and the voltage Ve is in a low-potential state. In this case, since the signal switch circuit 16 is not turned on, the transmission path between the detection device 1 with the electrostatic protection function and the device under test 2 is disconnected, and the ESD cannot enter the detection device 1 with the electrostatic protection function. At the next time point t2, the voltage Va is in the low-potential state, and the potential of the first output voltage Vb is adjusted from the first potential (high potential) to the second potential (low potential). At this time, the processor 121 adjusts the potential of the output second output voltage Vd to the first potential (high potential), so that the logic gate 123 enables the switching element, and the signal switching circuit 16 is kept non-conductive. More specifically, at the time point t2, the voltage Va is in the low state because the signal switch circuit 16 is not turned on. When the signal switch circuit 16 is not turned on, the static electricity generated by the device under test 2 cannot be introduced into the detecting device 1 with the static electricity protection function. At this time, the esd protection device 101 does not generate the current signal I1, and the sensing voltage generated by the sensing resistor is in a low-level state. Since the sensing voltage is in the low state, the potential of the first voltage Vb outputted by the differential circuit 105 is adjusted from the first potential (high potential) to the second potential (low potential). That is, when the first voltage Vb is adjusted to the second voltage (low voltage) state, the processor 121 adjusts the second output voltage Vd to the first voltage (high voltage), so that the signal switch circuit 16 can be kept off to prevent ESD from entering the detection device 1 with ESD protection function.

The phenomenon due to electrostatic discharge usually lasts for a time period, for example, 1 ms. Therefore, the processor 121 further adjusts the potential of the output second output voltage Vd to the first potential (high potential) at the time point t2, which is mainly for keeping the signal switch circuit 16 non-conductive within the time period (e.g. 1 ms), so as to ensure that the detection apparatus 1 with the electrostatic protection function is not damaged by the static electricity. When the processor 121 adjusts the level of the second output voltage Vd to the first level (high level) and the high level state lasts for a time period (e.g., 1 ms), the ESD phenomenon is eliminated. Therefore, at the time point t3, the processor 121 adjusts the output second output voltage Vd from the first potential (high potential) to the second potential (low potential), so that the logic gate 123 disables the switch element 120 to turn on the signal switch circuit 16. At this time, the transmission path between the detection device 1 with the electrostatic protection function and the device 2 to be detected is conducted again, so that the detection device 1 with the electrostatic protection function can continue to perform the detection procedure on the device 2 to be detected. In one embodiment, as shown in fig. 1, the control module 12 includes a light emitting diode 125 electrically connected to the processor 121. The led 125 is used to indicate the current state of the processor 121, so that a user can know whether the transmission path between the testing apparatus 1 and the device under test 2 is conducted.

In one embodiment, the differential circuit 105 includes a differential amplifier OP1 electrically connected to the first resistor 1051, the second resistor 1052, the third resistor 1053 and the fourth resistor 1054. The differential amplifier OP1 is used for adjusting the sensing voltage according to the resistance values of the resistors to output a first output voltage Vb, wherein the first output voltage Vb is greater than the sensing voltage. Specifically, the differential amplifier OP1 has a function of amplifying the sense voltage. For example, the sensing voltage can be amplified by adjusting the resistances of the first resistor 1051, the second resistor 1052, the third resistor 1053 and the fourth resistor 1054. Based on the circuit architecture of the differential circuit 105 in fig. 1, a person skilled in the art can understand that the resistance values of the first resistor 1051, the second resistor 1052, the third resistor 1053 and the fourth resistor 1054 can be freely adjusted according to actual requirements to obtain the required first output voltage Vb, and therefore the details are not repeated herein.

In one embodiment, as shown in FIG. 1, the differential circuit 105 includes a Zener diode 1055 electrically connected to the differential amplifier OP 1. More specifically, two ends of the zener diode 1055 are electrically connected to the output terminal (the terminal outputting the first output voltage Vb) of the differential amplifier OP1 and the ground terminal. The purpose is to clamp the voltage level of the first output voltage Vb by the voltage stabilizing function of the zener diode 1055. That is, as shown in fig. 2, by the zener diode 1055, the first output voltage Vb can be clamped at a stable voltage value, so as to prevent the first output voltage Vb from continuously rising with the voltage Va.

In summary, by using the detection apparatus of the present invention, the detection module can detect the electrostatic discharge during the process of testing the device under test. When the electrostatic discharge phenomenon occurs, the signal switch circuit is not conducted through the control module and is maintained for a period of time, and the switch circuit is reset to be conducted when the electrostatic discharge phenomenon is eliminated. Therefore, electrostatic discharge on the transmission path can be effectively isolated, and elements in the detection equipment are prevented from being damaged by electrostatic energy, so that the effect of protecting the detection equipment is achieved.

The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof, and it should be understood that various changes and modifications can be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A detection device with electrostatic protection function is suitable for detecting a device to be detected, and is characterized by comprising:

a test circuit;

a signal switch circuit electrically connected with the test circuit and the device to be tested;

a detection module, this signal switch circuit of electrical connection, this detection module contains:

an electrostatic protection element for generating a current signal according to the electrostatic discharge state of the device under test;

a sensing resistor for generating a sensing voltage according to the current signal; and

the differential circuit comprises a plurality of resistors, and is used for adjusting the sensing voltage according to the resistance values of the plurality of resistors so as to output a first output voltage; and

and the control module is electrically connected with the signal switch circuit and the detection module and selectively conducts the signal switch circuit according to the potential of the first output voltage.

2. The detecting apparatus with electrostatic protection function according to claim 1, wherein the control module comprises:

a switch element electrically connected to the signal switch circuit;

the processor is used for providing a second output voltage and adjusting the potential of the second output voltage according to the potential of the first output voltage; and

and the logic gate is electrically connected with the switch element and is used for outputting a control voltage to control the switch element according to the potential of the second output voltage and the potential of the first output voltage so as to selectively conduct the signal switch circuit.

3. The detecting apparatus of claim 2, wherein the potential of the control voltage is controlled by the potential of the second output voltage and the potential of the first output voltage, when the potential of the control voltage is the first potential, the switch element is enabled to turn off the signal switch circuit, and when the potential of the control voltage is the second potential, the switch element is disabled to turn on the signal switch circuit.

4. The detecting apparatus of claim 2, wherein when the device under test is under electrostatic discharge, the first output voltage is adjusted to a first voltage level, and the processor adjusts the second output voltage to a second voltage level, so that the logic gate enables the switch element to turn off the signal switch circuit.

5. The detecting apparatus of claim 3, wherein when the first output voltage is adjusted from a first voltage to a second voltage, the processor adjusts the output voltage to the first voltage, so that the logic gate enables the switch device to turn off the signal switch circuit.

6. The detecting apparatus of claim 4, wherein after the second output voltage is adjusted from the second voltage level to the first voltage level for a period of time, the processor adjusts the output voltage from the first voltage level to the second voltage level, so that the logic gate disables the switch element to turn on the signal switch circuit.

7. The detecting device of claim 1, wherein the differential circuit further comprises:

the differential amplifier is used for adjusting the sensing voltage according to the resistance values of the plurality of resistors so as to output the first output voltage, wherein the first output voltage is greater than the sensing voltage.

8. The detecting device of claim 7, wherein the differential circuit further comprises:

a Zener diode electrically connected to the differential amplifier for clamping the potential of the first output voltage.