Signal transmit channel integrated with ESD protection and a touch system

Patent metadata

Field	Value
Publication number	US-9710081-B2
Application number	US-201514680523-A
Country	US
Kind code	B2
Filing date	Apr 7, 2015
Priority date	Nov 28, 2014
Publication date	Jul 18, 2017
Grant date	Jul 18, 2017

Abstract

A signal transmit (TX) channel integrated with electrostatic discharge (ESD) protection includes a transmit switch having a first end coupled to receive a transmit signal, and being controlled by an associated scanning signal such that the transmit switch is closed to pass the transmit signal at a specific time; and an ESD protection circuit having a first input end electrically coupled to a second end of the transmit switch and a second input end coupled to receive the associated scanning signal.

First claim

What is claimed is:

1. A signal transmit channel integrated with electrostatic discharge (ESD) protection, comprising:
a transmit switch having a first end coupled to receive a transmit signal, the transmit switch being controlled by an associated scanning signal such that the transmit switch is closed to pass the transmit signal at a specific time; and
an ESD protection circuit having a first input end electrically coupled to a second end of the transmit switch and having a second input end coupled to receive the associated scanning signal;
wherein the ESD protection circuit comprises:
a first N-type transistor and a first P-type transistor that are connected in series and respectively connected to ground and power;
a second P-type transistor having a source and a drain respectively connected to the power and a gate of the first P-type transistor;
a first resistor-capacitor circuit having an output fed to a gate of the second P-type transistor;
a switching controller and a second N-type transistor that are connected in series and respectively connected to the power and the ground, an input end of the switching controller being coupled to receive the associated scanning signal and an output end of the switching controller being connected to a gate of the first N-type transistor; and
a second resistor-capacitor circuit having an output fed to a gate of the second N-type transistor.

2. The signal transmit channel of claim 1 , wherein the ESD protection circuit does not receive a signal that inverts the associated scanning signal.

3. The signal transmit channel of claim 1 , wherein drains of the first P-type transistor and the first N-type transistor are connected to the first input end and an output end of the ESD protection circuit, a source of the first P-type transistor is connected to the power, and a source of the first N-type transistor is connected to the ground.

4. The signal transmit channel of claim 1 , wherein one end of the switching controller is connected to the power, and another end of the switching controller is connected to a drain of the second N-type transistor.

5. The signal transmit channel of claim 1 , wherein the switching controller comprises a third P-type transistor an a third N-type transistor that are connected in series and respectively connected to the power and a drain of the second N-type transistor.

6. The signal transmit channel of claim 5 , wherein drains of the third P-type transistor and the third N-type transistor act as the output end of the switching controller and are connected to the gate of the first N-type transistor; gates of the third P-type transistor and the third N-type transistor act as the input end of the switching controller and are coupled to receive the associated scanning signal; and sources of the third P-type transistor and the third N-type transistor are respectively connected to the power and the drain of the second N-type transistor.

7. The signal transmit channel of claim 1 , wherein the first P-type transistor and the first N-type transistor comprise large-size transistors, and the second P-type transistor, the second N-type transistor, the third P-type transistor and the third N-type transistor comprise small-size transistors.

8. The signal transmit channel of claim 7 , wherein the large-size transistor is greater than the small-size transistor in width by at least one order of magnitude.

9. The signal transmit channel of claim 7 , wherein the large-size transistor has a width more than 100 micrometers and the small-size transistor has a width less than 10 micrometers.

10. A touch system, comprising:
a touch panel;
a signal transmit circuit including a plurality of signal transmit channels coupled to receive a transmit signal which is allowed to reach an output end via a specific number of channels at a time for driving the touch panel; and
a signal receive circuit coupled to receive output signals induced from the touch panel, the signal receive circuit determining a touch position according to status of the signal transmit channels;
wherein each of the plurality of signal transmit channels comprises:
a transmit switch having a first end coupled to receive the transmit signal, the transmit switch being controlled by an associated scanning signal such that the transmit switch is closed to pass the transmit signal at a specific time; and
an ESD protection circuit having a first input end electrically coupled to a second end of the transmit switch and having a second input end coupled to receive the associated scanning signal;

wherein the ESD protection circuit comprises:
a first N-type transistor and a first P-type transistor that are connected in series and respectively connected to ground and power;
a second P-type transistor having a source and a drain respectively connected to the power and a gate of the first P-type transistor;
a first resistor-capacitor circuit having an output fed to a gate of the second P-type transistor;
a switching controller and a second N-type transistor that are connected in series and respectively connected to the power and the ground, an input end of the switching controller being coupled to receive the associated scanning signal and an output end of the switching controller being connected to a gate of the first N-type transistor; and
a second resistor-capacitor circuit having an output fed to a gate of the second N-type transistor.

11. The system of claim 10 , wherein the ESD protection circuit does not receive a signal that inverts the associated scanning signal.

12. The system of claim 10 , wherein drains of the first P-type transistor and the first N-type transistor are connected to the first input end and an output end of the ESD protection circuit, a source of the first P-type transistor is connected to the power, and a source of the first N-type transistor is connected to the ground.

13. The system of claim 10 , wherein one end of the switching controller is connected to the power, and another end of the switching controller is connected to a drain of the second N-type transistor.

14. The system of claim 10 , wherein the switching controller comprises a third P-type transistor an a third N-type transistor that are connected in series and respectively connected to the power and a drain of the second N-type transistor.

15. The system of claim 14 , wherein drains of the third P-type transistor and the third N-type transistor act as the output end of the switching controller and are connected to the gate of the first N-type transistor; gates of the third P-type transistor and the third N-type transistor act as the input end of the switching controller and are coupled to receive the associated scanning signal; and sources of the third P-type transistor and the third N-type transistor are respectively connected to the power and the drain of the second N-type transistor.

16. The system of claim 10 , wherein the first P-type transistor and the first N-type transistor comprise large-size transistors, and the second P-type transistor, the second N-type transistor, the third P-type transistor and the third N-type transistor comprise small-size transistors.

17. The system of claim 16 , wherein the large-size transistor is greater than the small-size transistor in width by at least one order of magnitude.

18. The system of claim 16 , wherein the large-size transistor has a width more than 100 micrometers and the small-size transistor has a width less than 10 micrometers.

Assignees

• Egalax_Empia Tech Inc

Inventors

• Lin Po-Chuan

Classifications

• G06F2203/04107

  Shielding in digitiser, i.e. guard or shielding arrangements, mostly for capacitive touchscreens, e.g. driven shields, driven grounds · CPC title

• G06F3/0416

  Control or interface arrangements specially adapted for digitisers · CPC title

• G06F3/041 Primary

  Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means · CPC title

• G06F3/04164

  Connections between sensors and controllers, e.g. routing lines between electrodes and connection pads · CPC title

• G06F3/04166 Primary

  Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving (Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally G06F3/04184) · CPC title