Method and device for position detection

• US 8,970,557 B2
• Filed: 03/29/2012
• Issued: 03/03/2015
• Est. Priority Date: 03/29/2012
• Status: Active Grant

• Current Assignee: eGalax_eMPIA Technology Inc.
• Original Assignee: eGalax_eMPIA Technology Inc.
• Inventors: Yeh, Shang-Tai, Hsieh, Teng-Wei
• Primary Examiner(s): Patel, Kumar
• Assistant Examiner(s): ONYEKABA, AMY
• Application Number:
  US13/433,567
• Publication Number:
  US 20130257819A1
• Time in Patent Office: 1,069 Days
• US Class Current: 345/177
• CPC Class Codes: G06F 3/0436 in which generating transducers and detecting transducers are attached to a single acoustic waves transmission substrate

Abstract

The present invention provides a method and device for position detection. For detection of a touch position, a segment of surface acoustic wave (SAW) is provided multiple times to be propagated on a SAW touch panel, and the multiple SAW segments are received by the SAW touch panel. In addition, during or after reception, partial output electrical signals are provided based on different portions of each received SAW segment to construct a complete output electrical signal.

Claims

1. A position detecting method, comprising:

performing a first detecting stage including;

receiving a partial output electrical signal provided by a different portion of each received surface acoustic wave (SAW) segment and combining all of the partial output electrical signals to form a complete output electrical signal;

detecting one or more first-stage depression in the complete output electrical signal, wherein each first-stage depression is larger than a threshold; and

determining a position based on each first-stage depression, when a first-stage depression spanning over multiple partial output electrical signals, performing a second detecting stage, including;

generating a segment of second-stage SAW based on each first-stage depression spanning over multiple partial output electrical signals, and receiving the second-stage SAW to generate a second-stage output electrical signal based on the received second-stage SAW; and

detecting the position based on a portion in the second-stage output electrical signal corresponding to the first-stage depression.

2. The method of claim 1, wherein the complete output electrical signal when a SAW touch panel is untouched is in the form of a saw-tooth waveform.

3. The method of claim 1, wherein the second-stage output electrical signal is not in the form of a saw-tooth waveform.

4. The method of claim 1, wherein the wave number of the second-stage SAW is generated based on the corresponding first-stage depression spanning over multiple partial output electrical signals.

5. The method of claim 1, wherein the gain of the second-stage SAW is generated based on the corresponding first-stage depression spanning over multiple partial output electrical signals.

11. The method of claim 1, wherein a starting signal of a latter partial output electrical signal is larger than that of an ending signal of a front partial output electrical signal in the complete output electrical signal.

12. The method of claim 1, wherein a wave number of a latter SAW segment is larger than a wave number of a front SAW segment in the multiple SAW segments.

13. The method of claim 1, wherein each segment of partial output electrical signal is generated based on a gain, the gain of a latter partial output electrical signal being larger than the gain of a front partial output electrical signal.

14. The method of claim 1, wherein each segment of partial output electrical signal is within a predefined range.

15. The method of claim 1, wherein the SAW touch panel is laid out with multiple segments of detecting areas, each segment of partial output electrical signal corresponding to a segment of detecting area.

16. The method of claim 1, wherein the multiple detecting areas include multiple segments of detecting areas laid along a vertical axis of the SAW touch panel and multiple segments of detecting areas laid along a horizontal axis of the SAW touch panel.

17. The method of claim 1, wherein each segment of partial output electrical signal corresponds to a period of time, wherein the period of time is in reference to a starting time for receiving the segment of partial output electrical signal or a starting time for providing the segment of partial output electrical signal.

6. A position detecting device, comprising:

a surface acoustic wave (SAW) touch panel including a reflector array distributed on four sides of the SAW touch panel and a sensing device, the sensing device including;

a first vertical-axis transducer element and a first horizontal-axis transducer element for providing multiple SAW segments to be propagated on the SAW touch panel;

a second vertical-axis transducer element and a second horizontal-axis transducer element for receiving the SAWs propagated on the SAW touch panel; and

a control circuit for performing the following;

performing a first detecting stage including;

receiving a partial output electrical signal provided by a different portion of each received SAW segment and combining all of the partial output electrical signals to form a complete output electrical signal;

detecting one or more first-stage depression in the complete output electrical signal, wherein each first-stage depression is larger than a threshold; and

determining a position based on each first-stage depression, when a first-stage depression spanning over multiple partial output electrical signals, performing a second detecting stage, including;

generating a segment of second-stage SAW based on each first-stage depression spanning over multiple partial output electrical signals, and receiving the second-stage SAW to generate a second-stage output electrical signal based on the received second-stage SAW; and

detecting the position based on a portion in the second-stage output electrical signal corresponding to the first-stage depression.

7. The device of claim 6, wherein the complete output electrical signal when the SAW touch panel is untouched is in the form of a saw-tooth waveform.

8. The device of claim 6, wherein the second-stage output electrical signal is not in the form of a saw-tooth waveform.

9. The device of claim 6, wherein the wave number of the second-stage SAW is generated based on the corresponding first-stage depression spanning over multiple partial output electrical signals.

10. The device of claim 6, wherein the gain of the second-stage SAW is generated based on the corresponding first-stage depression spanning over multiple partial output electrical signals.

18. The device of claim 6, wherein a starting signal of a latter partial output electrical signal is larger than that of an ending signal of a front partial output electrical signal in the complete output electrical signal.

19. The device of claim 6, wherein a wave number of a latter SAW segment is larger than a wave number of a front SAW segment in the multiple SAW segments.

20. The device of claim 6, wherein each segment of partial output electrical signal is generated based on a gain, the gain of a latter partial output electrical signal being larger than the gain of a front partial output electrical signal.

21. The device of claim 6, wherein each segment of partial output electrical signal is within a predefined range.

22. The device of claim 6, wherein the SAW touch panel is laid out with multiple segments of detecting areas, each segment of partial output electrical signal corresponding to a segment of detecting area.

23. The device of claim 6, wherein the multiple detecting areas include multiple segments of detecting areas laid along the vertical axis of the SAW touch panel and multiple segments of detecting areas laid along the horizontal axis of the SAW touch panel.

24. The device of claim 6, wherein each segment of partial output electrical signal corresponds to a period of time, wherein the period of time is in reference to a starting time for receiving the segment of partial output electrical signal or a starting time for providing the segment of partial output electrical signal.