Electrostatic protection circuit, circuit board, and electrostatic protecting method

Patent metadata

Field	Value
Publication number	US-11057988-B2
Application number	US-201816089201-A
Country	US
Kind code	B2
Filing date	Mar 26, 2018
Priority date	Apr 1, 2017
Publication date	Jul 6, 2021
Grant date	Jul 6, 2021

Abstract

The present disclosure provides an electrostatic protection circuit, a circuit board, and an electrostatic protecting method. The electrostatic protection circuit includes a first relay and a second relay, wherein a control terminal of the first relay and a control terminal of the second relay are configured to be connected to a power supply of a system circuit respectively, and wherein the first relay and the second relay are connected in series between the system circuit and a ground terminal to form a charge release path, and the first relay is switched from an open circuit state to a short circuit state when the system circuit is powered off, and the charge release path is in a turn-on state after the first relay is switched to the short circuit state, thereby releasing an electrostatic charge in the system circuit.

First claim

What is claimed is:

1. An electrostatic protection circuit comprising a first relay and a second relay,
wherein a control terminal of the first relay and a control terminal of the second relay are configured to be connected to a power supply of a system circuit respectively;
wherein the first relay and the second relay are connected in series between the system circuit and a ground terminal to form a charge release path, wherein the first relay is switched from a short circuit state to an open circuit state when the system circuit is powered on and is switched from the open circuit state to the short circuit state when the system circuit is powered off, and wherein the charge release path is in a turn-on state after the first relay is switched to the short circuit state, thereby releasing an electrostatic charge in the system circuit; and
wherein the second relay is switched from the open circuit state to the short circuit state when the system circuit is powered on and after the first relay is in the open circuit state for a first time period, and when the system circuit is powered off and after the second relay is in the short circuit state for a second time period, the second relay is switched to the open circuit state, and wherein the charge release path is in a turn-off state after the second relay is switched to the open circuit state, thereby stopping the release of the electrostatic charge in the system circuit,
wherein the second time period is a delay time of the second relay, and wherein the first time period is a difference between the delay time of the second relay and a delay time of the first relay.

2. The electrostatic protection circuit according to claim 1 , wherein the first relay is a normally-short circuit time relay and the second relay is a normally-open circuit time relay.

3. The electrostatic protection circuit according to claim 1 , further comprising a diode connected in series between the power supply and the system circuit,
wherein when the system circuit is powered on, the diode is in a forward conductive state, and when the system circuit is powered off, the diode is in a reverse cut-off state to cause the electrostatic charge in the system circuit to flow into the charge release path.

4. The electrostatic protection circuit according to claim 1 , further comprising a fuse connected between the charge release path and the ground terminal.

5. A circuit board comprising the system circuit and the electrostatic protection circuit according to claim 1 .

6. An electrostatic protecting method applied to the electrostatic protection circuit according to claim 1 , the method comprising:
when the system circuit is powered on, switching the first relay from the short circuit state to the open circuit state;
after the first time period elapses, switching the second relay from the open circuit state to the short circuit state;
when the system circuit is powered off, switching the first relay from the open circuit state to the short circuit state, such that the charge release path composed of the first relay and the second relay is turned on, thereby the electrostatic charge in the system circuit is released to the ground terminal; and
after the second time period elapses, switching the second relay from the short circuit state to the open circuit state, such that the charge release path is turned off, thereby stopping the release of the electrostatic charge in the system circuit.

7. The method according to claim 6 , wherein the electrostatic protection circuit further comprises a diode connected in series between the power supply and the system circuit, the method further comprising:
when the system circuit is powered off, putting the diode in a reverse cut-off state to cause the electrostatic charge in the system circuit to flow into the charge release path.

8. The method according to claim 6 , wherein the electrostatic protection circuit further comprises a fuse connected between the charge release path and the ground terminal, the method further comprising:
when a current in the charge release path exceeds a set threshold, blowing the fuse to protect the relay.

9. A circuit board comprising the system circuit and the electrostatic protection circuit according to claim 2 .

10. A circuit board comprising the system circuit and the electrostatic protection circuit according to claim 3 .

11. A circuit board comprising the system circuit and the electrostatic protection circuit according to claim 4 .

12. An electrostatic protecting method applied to the electrostatic protection circuit according to claim 2 , the method comprising:
when the system circuit is powered on, switching the first relay from the short circuit state to the open circuit state;
after the first time period elapses, switching the second relay from the open circuit state to the short circuit state;
when the system circuit is powered off, switching the first relay from the open circuit state to the short circuit state, such that the charge release path composed of the first relay and the second relay is turned on, thereby the electrostatic charge in the system circuit is released to the ground terminal; and
after the second time period elapses, switching the second relay from the short circuit state to the open circuit state, such that the charge release path is turned off, thereby stopping releasing the electrostatic charge in the system circuit.

13. An electrostatic protecting method applied to the electrostatic protection circuit according to claim 3 , the method comprising:
when the system circuit is powered on, switching the first relay from the short circuit state to the open circuit state;
after the first time period elapses, switching the second relay from the open circuit state to the short circuit state;
when the system circuit is powered off, switching the first relay from the open circuit state to the short circuit state, such that the charge release path composed of the first relay and the second relay is turned on, thereby the electrostatic charge in the system circuit is released to the ground terminal; and
after the second time period elapses, switching the second relay from the short circuit state to the open circuit state, such that the charge release path is turned off, thereby stopping releasing the electrostatic charge in the system circuit.

14. An electrostatic protecting method applied to the electrostatic protection circuit according to claim 4 , the method comprising:
when the system circuit is powered on, switching the first relay from the short circuit state to the open circuit state;
after the first time period elapses, switching the second relay from the open circuit state to the short circuit state;
when the system circuit is powered off, switching the first relay from the open circuit state to the short circuit state, such that the charge release path composed of the first relay and the second relay is turned on, thereby the electrostatic charge in the system circuit is released to the ground terminal; and
after the second time period elapses, switching the second relay from the short circuit state to the open circuit state, such that the charge release path is turned off, thereby stopping releasing the electrostatic charge in the system circuit.

Assignees

• Beijing Boe Optoelectronics Tech Co Ltd
• Boe Technology Group Co Ltd

Inventors

• Li Pengtao
• Liu Ying
• Yu Yangbing
• Yu Jie
• Tan Qin

Classifications

• G02F1/133 Primary

  Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements (arrangements or circuits for control of liquid crystal elements in a matrix, not structurally associated with these elements G09G3/36) · CPC title

• H02H9/041

  using a short-circuiting device · CPC title

• H02H9/046

  responsive to excess voltage appearing at terminals of integrated circuits · CPC title

• G02F2202/22

  Antistatic materials or arrangements · CPC title

• H02H9/00 Primary

  Emergency protective circuit arrangements for limiting excess current or voltage without disconnection · CPC title