Optical touch detection using input and output beam scanners

• US 8,542,217 B2
• Filed: 06/22/2009
• Issued: 09/24/2013
• Est. Priority Date: 06/23/2008
• Status: Active Grant

• Current Assignee: FlatFrog Laboratories AB
• Original Assignee: FlatFrog Laboratories AB
• Inventors: Wassvik, Ola, Vilhelmsson, Kennet
• Primary Examiner(s): Mengistu, Amare
• Assistant Examiner(s): HOLTON, STEVEN E
• Application Number:
  US12/737,019
• Publication Number:
  US 20110102374A1
• Time in Patent Office: 1,555 Days
• Field of Search: 345173-178, 178 1801- 1811, 3592021-2045, 356/399, 356/400, 356/601, 356/607, 356/608, 356/614, 356/621, 356638-640
• US Class Current: 345/175
• CPC Class Codes: G06F 2203/04109 FTIR in optical digitiser, i.e. touch detection by frustrating the total internal reflection within an optical waveguide due to changes of optical properties or deformation at the touch location
• CPC Class Codes: G06F 3/0423 using sweeping light beams, e.g. using rotating or vibrating mirror

Abstract

An apparatus is controlled to detect a location of an object on a touch surface of a panel. An input scanner arrangement introduces at least two beams of radiation into the panel for propagation by internal reflection, and sweeps the beams inside the panel across a sensing area. An output scanner arrangement is synchronized with the input scanner arrangement so as to receive the beams from the input scanner arrangement while they are swept across the sensing area and to direct the beams onto at least one radiation detector. Thereby, each beam is introduced and received on opposite ends of the sensing area. A data processor is connected to the radiation detector and operated to identify the location based on an attenuation of the beams caused by the object touching the touch surface within the sensing area.

Claims

1. An apparatus for detecting a location of at least one object on a touch surface, said apparatus comprising:

a panel defining the touch surface and an opposite surface;

an input scanner arrangement adapted to introduce at least two beams of radiation into the panel for propagation by internal reflection between the touch surface and the opposite surface, and to sweep the beams along the touch surface across a sensing area of the panel;

an output scanner arrangement which is synchronized with the input scanner arrangement so as to receive the beams from said input scanner arrangement while they are swept across the sensing area and to direct the beams onto at least one radiation detector;

wherein said input and output scanner arrangements are configured to introduce and receive each beam on opposite ends of said sensing area;

said apparatus further comprising a data processor connected to said at least one radiation detector and configured to identify said location based on an attenuation of said beams caused by the object touching the touch surface within said sensing area;

wherein

the output scanner arrangement comprises at least one fixed re-directing element configured to receive and re-direct each beam onto a respective common detection point while the beams are swept across the sensing area,

the output scanner arrangement further comprises at least one movable deflection element which is arranged at said common detection point(s) and is controllable to deflect the beams onto said at least one radiation detector, and

the input scanner arrangement comprises at least one movable beam-sweeping element which is controllable to sweep the beams across the sensing area.

2. The apparatus of claim 1, wherein the data processor is configured to identify said location based on one or more signals indicative of the attenuation of each beam while being swept across the sensing area.

3. The apparatus of claim 1, wherein said at least one re-directing element is arranged at the periphery of the panel.

4. The apparatus of claim 1, wherein said at least one deflection element is arranged underneath the panel, said output scanner arrangement further comprising an optical folding system for directing the beams from the plane of the panel to said at least one deflection element.

5. The apparatus of claim 1, wherein a single movable deflection element is arranged to deflect the beams onto said at least one radiation detector.

6. The apparatus of claim 1, wherein a single movable beam-sweeping element is arranged to sweep the beams across the sensing area.

7. The apparatus of claim 1, further comprising a control device for synchronizing the beam-sweeping element(s) of the input scanner arrangement and the deflection element(s) of the output scanner arrangement.

8. The apparatus of claim 1, wherein the beam-sweeping element and the deflection element of the input and output scanner arrangements are formed by a single movable element.

9. The apparatus of claim 1, wherein the input scanner arrangement further comprises at least one fixed beam-directing element which is arranged to receive the beams from the beam-sweeping element(s) and to cause the beams to have an essentially invariant main direction while being swept across the sensing area.

10. The apparatus of claim 9, wherein said at least one beam-directing element is arranged at the periphery of the panel.

11. The apparatus of claim 1, wherein said at least one beam-sweeping element is arranged underneath the panel, said input scanner arrangement further comprising an optical folding system for directing the beams from said at least one beam-sweeping element to the plane of the panel.

12. The apparatus of claim 1, wherein the input scanner arrangement is configured to sweep the beams by translating each beam across the sensing area.

13. The apparatus of claim 12, wherein said panel is defined by linear periphery portions, and each beam is translated in a direction which is essentially parallel to one of said linear periphery portions.

14. The apparatus of claim 1, wherein said beams are non-parallel within said sensing area.

15. The apparatus of claim 1, wherein the input scanner arrangement is configured to sweep the beams angularly across the sensing area and around a respective axis of scanning.

16. A method of detecting a location of at least one object on a touch surface, said method comprising:

introducing at least two beams of radiation into a panel that defines the touch surface and an opposite surface, said beams propagating by internal reflection between the touch surface and the opposite surface;

sweeping the beams along the touch surface across a sensing area of the panel;

receiving the beams at an opposite end of the sensing area;

directing, synchronously with said sweeping, each of the beams onto a respective common detection point;

deflecting the beams from said common detection point(s) onto at least one radiation detector; and

identifying said location based on an attenuation of said beams caused by the object touching the touch surface within said sensing area, said attenuation being identifiable from an output signal of the radiation detector.

17. A method of operating an apparatus for detecting a location of at least one object on a touch surface, said touch surface being part of a panel that defines the touch surface and an opposite surface, said method comprising:

operating an input scanner arrangement to introduce at least two beams of radiation into the panel for propagation by internal reflection between the touch surface and the opposite surface, and to sweep the beams along the touch surface across a sensing area of the panel;

operating an output scanner arrangement in synchronization with the input scanner arrangement to

receive the beams at an opposite end of the sensing area while the beams are swept across the sensing area,

direct the beams onto a respective common detection point while the beams are swept across the sensing area,

deflect the beams from the common detection point(s) onto at least one radiation detector; and

identifying said location based on an attenuation of said beams caused by the object touching the touch surface within said sensing area, said attenuation being identifiable from an output signal of the radiation detector.