TOUCH PAD SYSTEM

• US 20090122020A1
• Filed: 06/30/2006
• Published: 05/14/2009
• Est. Priority Date: 07/05/2005
• Status: Active Grant

• Current Assignee: FlatFrog Laboratories AB
• Original Assignee: FlatFrog Laboratories AB
• Inventors: Stubbe Ostergaard, Jens Wagenblast, Eliasson, Jonas Ove Philip
• Granted Patent: US 7,995,039 B2
• Time in Patent Office: Days
• US Class Current: 345/173
• 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 3/0421 by interrupting or reflecting a light beam, e.g. optical touch-screen

Abstract

Radiation guided by Total Internal Reflection inside a solid element from a point of engagement of a reflecting/emitting/scattering object and toward a detector reaches an area of the solid element on which the surface has areas preventing reflection of the radiation back into the element. This provides a spatial modulation of the radiation reaching the detector through one of the surfaces of the solid element. From this spatial modulation, the position of engagement may be determined.

Claims

1. A system for determining a position of an object adapted to reflect/scatter/emit radiation, the system comprising:

a radiation transmissive element having a first surface being adapted to be engaged by the object so as to reflect/scatter/emit radiation into the elements and a second surface opposite to the first surface, the radiation transmissive element being adapted to guide reflected/scattered/emitted radiation therein by total internal reflection along a first part of a radiation path extending from the object towards a radiation detector;

said radiation detector having an at least one-dimensional detecting surface and being adapted to detect radiation through the first and/or the second surface, which radiation is reflected/scattered/emitted by the object, and to output a signal relating to the detected radiation; and

at least one radiation modulator being provided in the first part of the radiation path, the modulating means being and adapted to prevent at least a part of the reflected/scattered/emitted radiation from propagating to the radiation detector, said at least one radiation modulator being positioned on or at the first and/or the second surface and defining, in the plane of the first and/or second surface, a plurality of areas,

one or more first of the areas allowing or facilitating reflection of radiation travelling in the radiation transmissive element back into the radiation transmissive element, and

one or more second of the areas preventing reflection of radiation travelling in the radiation transmissive element back into the radiation transmissive element.

2. A system according to claim 1, wherein the detecting surface is at least substantially parallel with the first and/or the second surface.

3. A system according to claim 1, wherein an air cavity is provided between the radiation modulator and the radiation transmissive element.

4. A system according to claim 1, wherein the radiation modulator is provided on or at the same surface of the radiation transmissive element as the radiation detector.

5. A system according to claim 1, wherein the radiation modulator is provided on or at an opposite surface of the radiation transmissive element with respect to the radiation detector.

6. A system according to claim 1, wherein the radiation modulator is provided on an opposite surface of the radiation transmissive element with respect to the radiation detector and wherein

the first area(s) are adapted to reflect radiation towards the detecting surface of the detecting surface;

and

the second area(s) comprises at least one of;

an absorbent area preventing radiation from propagating towards the detecting surface, and

a radiation transmissive outcoupler allowing radiation to be coupled out of the radiation transmissive element and into the transmissive outcoupler, the transmissive outcoupler comprising means for preventing said radiation from propagating back through said opposite surface.

7. A system according to claim 1, wherein the radiation modulator and the radiation detector are provided on the same surface of the radiation transmissive element and wherein

the first area(s) are adapted to reflect radiation in a direction opposite the detecting surface so as to prevent said radiation from propagating towards radiation detector;

and

the second area(s) comprises at least one of;

an absorbent area preventing radiation from propagating towards the detecting surface, and

a radiation transmissive outcoupler allowing radiation to be coupled out of the transmissive element and into the transmissive outcoupler so as propagate towards the detecting surface.

8. A system according to claim 6 or 7, wherein the one or more first and the one or more second of the areas of the radiation modulator are provided in a predetermined pattern.

9. A system according to claim 1, wherein a length of the radiation modulator in a plane substantially parallel with the first and/or the second surface is at least twice the distance between the first and second surfaces at the area of the radiation modulator.

10. A system according to claim 1, wherein the detecting surface is provided on or at the second surface.

11. A system according to claim 1, wherein the detecting surface forms an outer surface of a double- or triple-glazed window.