ADAPTIVE HIGH DYNAMIC RANGE SURFACE CAPACITIVE TOUCHSCREEN CONTROLLER

• US 20120062500A1
• Filed: 09/09/2010
• Published: 03/15/2012
• Est. Priority Date: 09/09/2010
• Status: Active Grant

• Current Assignee: Synaptics Incorporated
• Original Assignee: Conexant Systems Incorporated (Synaptics Incorporated)
• Inventors: Miller, Mark E., Sneed, George C., Vadapalli, Ramakrishna Y., Anumula, Sudhaker R.
• Granted Patent: US 8,847,896 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• CPC Class Codes: G06F 3/04166 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 Class Codes: G06F 3/044 by capacitive means

Abstract

A system for controlling a touch screen. A touch screen element having a plurality of contacts, such as one contact electrode at each of four corners. A multiplexer coupled to the touch screen element for forming a plurality of connections, such as various combinations of the contact electrodes to allow measurements to be made of the impedance of the touch screen element from the left side to the right side, from the top to the bottom, and do forth. A touch screen processor coupled to the touch screen element for determining an oscillation frequency of the touch screen element as a function of the electrode connections.

Claims

1. A system for controlling a touch screen comprising:

a touch screen element having a plurality of contacts;

a multiplexer coupled to the touch screen element for forming a plurality of connections; and

a touch screen processor coupled to the touch screen element for determining an oscillation frequency of the touch screen element.

2. The system of claim 1 wherein the touch screen processor comprises a left-right frequency system for determining a touch location associated with a circuit driving from a left hand side of the touch screen element to a right hand side of the touch screen element as a function of frequency.

3. The system of claim 1 wherein the touch screen processor comprises a right-left frequency system for determining a touch location associated with a circuit driven from a right hand side of the touch screen element to a left hand side of the touch screen element as a function of frequency.

4. The system of claim 1 wherein the touch screen processor comprises a top-bottom frequency system for determining a touch location associated with a circuit driven from a top side of the touch screen element to a bottom side of the touch screen element as a function of frequency.

5. The system of claim 1 wherein the touch screen processor comprises a bottom-top frequency system for determining a touch location associated with a circuit driven from a bottom of the touch screen element to a top of the touch screen element as a function of frequency.

6. The system of claim 1 wherein the touch screen processor comprises a calibration system for calibrating a frequency based on a location at which the touch screen element is being touched.

7. The system of claim 1 wherein the touch screen processor comprises a difference amplifier receiving a touch screen element input signal and a touch screen element output signal and generating a difference signal.

8. The system of claim 7 wherein the touch screen processor comprises an integrator receiving a difference signal input and generating an integrated difference signal output.

9. The system of claim 8 wherein the touch screen processor comprises a reset pulse generator coupled to the integrator for resetting the integrator.

10. The system of claim 8 wherein the touch screen processor comprises an integrator hold coupled to the integrator for compensating for integrator noise signal.

11. The system of claim 10 further comprising a second integrator receiving the output of the integrator and generating an input to a reset pulse generator.

12. The system of claim 1 wherein the touch screen processor comprises a frequency counter for determining a frequency of oscillation of a circuit in which the touch screen element forms an oscillator element.

13. The system of claim 7 wherein the touch screen processor comprises a frequency counter for determining a frequency of oscillation of a circuit in which the touch screen element forms an oscillator element.

14. The system of claim 8 wherein the touch screen processor comprises a frequency counter for determining a frequency of oscillation of a circuit in which the touch screen element forms an oscillator element.

15. The system of claim 9 wherein the touch screen processor comprises a frequency counter for determining a frequency of oscillation of a circuit in which the touch screen element forms an oscillator element.

16. The system of claim 10 wherein the touch screen processor comprises a frequency counter for determining a frequency of oscillation of a circuit in which the touch screen element forms an oscillator element.

17. The system of claim 11 wherein the touch screen processor comprises a frequency counter for determining a frequency of oscillation of a circuit in which the touch screen element forms an oscillator element.

18. A method for controlling a touch screen comprising:

using a multiplexer coupled to the touch screen element to form a plurality of connections;

processing signals generated by a touch screen processor coupled to the touch screen element to determine an oscillation frequency of the touch screen element for each of the plurality of connections; and

determining a location at which the touch screen element has been touched based on the determined oscillation frequencies.

19. The method of claim 18 wherein using the multiplexer coupled to the touch screen element to form the plurality of connections comprises connecting a top right electrode of the touch screen element and a bottom right electrode of the touch screen element to form a right-side input connection and connecting a top left electrode of the touch screen element and a bottom left electrode of the touch screen element to form a left-side output connection.

20. The method of claim 18 wherein using the multiplexer coupled to the touch screen element to form the plurality of connections comprises connecting a top left electrode of the touch screen element and a bottom left electrode of the touch screen element to form a left-side input connection and connecting a top right electrode of the touch screen element and a bottom right electrode of the touch screen element to form a right-side output connection.

21. The method of claim 18 wherein using the multiplexer coupled to the touch screen element to form the plurality of connections comprises connecting a top right electrode of the touch screen element and a top left electrode of the touch screen element to form a top-side input connection and connecting a bottom left electrode of the touch screen element and a bottom right electrode of the touch screen element to form a bottom-side output connection.

22. The method of claim 18 wherein using the multiplexer coupled to the touch screen element to form the plurality of connections comprises connecting a bottom right electrode of the touch screen element and a bottom left electrode of the touch screen element to form a bottom-side input connection and connecting a top left electrode of the touch screen element and a top right electrode of the touch screen element to form a top-side output connection.

23. The method of claim 18 further comprising generating a calibration signal and measuring a plurality of calibration frequencies.