Auto-gain switching module for acoustic touch systems

• US 20080007543A1
• Filed: 07/06/2006
• Published: 01/10/2008
• Est. Priority Date: 07/06/2006
• Status: Active Grant

• Current Assignee: Elo Touch Solutions, Inc.
• Original Assignee: Tyco Electronics Corporation (TE Connectivity Ltd. (United Kingdom))
• Inventors: D'souza, Henry M.
• Granted Patent: US 8,692,809 B2
• Time in Patent Office: Days
• US Class Current: 345/177
• CPC Class Codes: G06F 3/043 using propagating acoustic waves
• CPC Class Codes: H03G 3/10 having semiconductor devices

Abstract

An apparatus for processing signals received from an acoustic touch surface comprises an analog input receiving an analog input signal having a signal level. The analog input signal comprises data indicative of a touch location on a touch surface. A plurality of gain elements receive the analog input signal and output gain-adjusted analog signals. A gain selection module selects one of the gain-adjusted analog signals based on the signal level of the analog input signal

Claims

1. An apparatus for processing signals received from an acoustic touch surface, comprising:

an analog input receiving an analog input signal having a signal level, the analog input signal comprising data indicative of a touch location on a touch surface;

a plurality of gain elements receiving the analog input signal and outputting gain-adjusted analog signals; and

a gain selection module selecting one of the gain-adjusted analog signals based on the signal level of the analog input signal.

2. The apparatus of claim 1, further comprising a plurality of comparator elements comparing the analog input signal to a plurality of reference voltage levels, the gain selection module selecting the gain-adjusted analog signal based on at least one output of the comparator elements.

3. The apparatus of claim 1, further comprising a comparator element comparing the analog input signal to a reference voltage level, the comparator element outputting a predetermined output when the analog input signal exceeds the reference voltage level, the gain selection module selecting the gain-adjusted analog signal based on at least the output of the comparator element.

4. The apparatus of claim 1, further comprising a plurality of comparator elements comparing the analog input signal to a plurality of reference voltage levels, each of the plurality of comparator elements outputting a predetermined output when the analog input signal exceeds the respective reference voltage level, the gain selection module selecting the gain-adjusted analog signal based on at least one output of the comparator elements.

5. The apparatus of claim 1, further comprising:

a second analog input receiving a second analog input signal having a second signal level, the second analog input signal comprising data indicative of the touch location on the touch surface; and

a second plurality of gain elements receiving the second analog input signal and outputting second gain-adjusted analog signals, the gain selection module selecting one of the second gain-adjusted analog signals based on at least one of the signal level of the analog input signal and the second signal level of the second analog input signal.

6. The apparatus of claim 1, further comprising:

a second analog input receiving a second analog input signal having a second signal level, the second analog input signal comprising data indicative of the touch location on the touch surface; and

a second plurality of comparator elements comparing the second analog input signal to a plurality of reference voltage levels, the gain selection module selecting one of the gain-adjusted analog signals based on at least one output of the second plurality of comparator elements.

7. The apparatus of claim 1, wherein the gain selection module detects a change in the signal level of the analog input signal and selects a different gain-adjusted analog signal based on the change in the signal level.

8. A touch system, comprising:

an acoustic touch pad;

an auto-gain switching module receiving first and second analog input signals from the touch pad, the first and second analog input signals having first and second signal levels and comprising data indicative of a touch location on the touch pad, the auto-gain switching module adjusting gain levels of the first and second analog inputs; and

an analog to digital (A/D) converter, the auto-gain switching module outputting a first and a second gain-adjusted signal to the A/D converter based on at least the first and second signal levels of the first and second analog input signals

9. The touch system of claim 8, the auto-gain switching module further comprising gain elements adjusting the first and second analog input signals by one of increasing the first and second signal levels, decreasing the first and second signal levels, and no adjustment.

10. The touch system of claim 8, the auto-gain switching module outputting the first and second gain-adjusted signals based on a signal level of at least one of the first and second gain-adjusted signals.

11. The touch system of claim 8, the auto-gain switching module selecting the gain of the first and second gain-adjusted signals based on an operating range of the A/D converter.

12. The touch system of claim 8, the auto-gain switching module further comprising first gain elements receiving the first analog input signal and outputting first gain-adjusted signals, the auto-gain switching module further comprising second gain elements receiving the second analog input signal and outputting second gain-adjusted signals, the auto-gain switching module outputting the first and second gain-adjusted signals from the first and second gain elements that have the same gain adjustment.

13. The touch system of claim 8, the auto-gain switching module further outputting the first and second gain-adjusted signals with a different gain based on a detected change in at least one of the first and second signal levels, the auto-gain switching module maintaining the first and second gain-adjusted signals at the different gain for a predetermined period of time.

14. The touch system of claim 8, further comprising a plurality of comparator elements comparing the first and second analog input signals to a plurality of reference voltage levels, the auto-gain switching module selecting the first and second adjusted signal levels based on outputs of the plurality of comparator elements.

15. The touch system of claim 8, wherein the first and second analog input signals further comprise sine waves, the auto-gain switching module further outputting the first and second gain-adjusted signals with a first gain based on a first level of at least one of the first and second signal levels, the auto-gain switching module outputting the first and second gain-adjusted signals with a second gain based on a detected change in at least one of the first and second signal levels, the sine waves having a single point of discontinuity at a point corresponding to a change from the first gain to the second gain.

16. A method for processing signals from an acoustic touch pad, comprising:

receiving an analog input signal having a signal level, the analog input signal comprising data indicative of a touch location on a touch pad;

outputting a plurality of gain-adjusted analog signals by adjusting a gain of the analog input signal with a plurality of different gain responses; and

selecting one of the gain-adjusted analog signals based on the signal level of the analog input signal.

17. The method of claim 16, further comprising:

comparing the analog input signal to a plurality of reference voltage levels; and

selecting the one of the gain-adjusted analog signals based on a result of the comparing step.

18. The method of claim 16, further comprising:

comparing the analog input signal to a plurality of reference voltage levels; and

selecting a second gain-adjusted analog signal based on a result of the comparing step.

19. The method of claim 16, further comprising:

receiving a second analog input signal having a second signal level, the second analog input signal comprising data indicative of the touch location; and

selecting the one of the gain-adjusted analog signals based on at least the second signal level of the second analog input signal.

20. The method of claim 16, further comprising:

receiving a second analog input signal having a second signal level, the second analog input signal comprising data indicative of the touch location; and

outputting a plurality of second gain-adjusted analog signals by adjusting a gain of the second analog input signal with the plurality of different gain responses, the selecting step further comprising selecting one of the second gain-adjusted analog signals based on at least one of the signal level and the second signal level, the one of the gain-adjusted analog signals and the second gain-adjusted analog signal being adjusted by a same gain response.