Optical generic switch panel

• US 20080006766A1
• Filed: 07/10/2006
• Published: 01/10/2008
• Est. Priority Date: 07/10/2006
• Status: Active Grant

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Inventors: Chen, Farn Hin, Keh, Kean Loo, Ward, Calvin B., Oon, Chin Hin
• Granted Patent: US 7,351,949 B2
• Time in Patent Office: Days
• US Class Current: 250/221
• 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

A switch panel having a touch plate, light converter, and light analyzer are disclosed. The touch plate includes an optically transparent layer having first and second surfaces, and having an index of refraction greater than that of air. The touch plate conducts light of an excitation wavelength between the first and second surfaces and emits part of that light through the second surface at one of a plurality of emission locations depending on the position at which pressure is applied to the first surface. The light converter is positioned to receive the light emitted through the second surface and generates light having a plurality of distinct location-specific spectra, one of the location-specific spectra corresponding to each of the emission locations. The light analyzer generates a signal indicative of which of the location-specific spectra was generated by the light converter.

Claims

1. A switch panel comprising:

a touch plate comprising an optically transparent layer having first and second surfaces, said optically transparent layer having an index of refraction greater than that of air, said touch plate conducting light of an excitation wavelength between said first and second surfaces and emitting part of said light through said second surface at one of a plurality of emission locations determined by pressure being applied to said first surface at a corresponding location;

a light converter positioned to receive said light emitted through said second surface at each of said plurality of emission locations, said light converter generating light having a plurality of distinct location-specific spectra, one of said location-specific spectra corresponding to each of said emission locations, said one of said location-specific spectra being determined by said emission location; and

a light analyzer that generates a signal indicative of which of said location-specific spectra was generated by said light converter.

2. The switch panel of claim 1 wherein said touch plate comprises an image generator that displays an image comprising a plurality of button positions on said first surface.

3. The switch panel of claim 1 wherein said light converter comprises a layer of phosphor on a third surface, said layer of phosphor having a composition that is a function of position on said third surface.

4. The switch panel of claim 3 wherein said light converter comprises a light collector that collects a portion of said light generated on said third surface and couples said collected portion to said light analyzer.

5. The switch panel of claim 4 wherein said light collector comprises a transparent layer of material positioned to receive light leaving said third surface, a portion of said received light being internally reflected within said transparent layer and leaving said transparent layer through an edge thereof.

6. The switch panel of claim 5 wherein said transparent layer of material comprises a reflective surface over selected portions of said transparent layer, said selected portions being positioned such that light leaving said second surface of said touch plate can still reach said layer of phosphor while a portion of said light emitted by said phosphor is reflected on said reflective surface.

7. The switch panel of claim 1 wherein a portion of said light signal is reflected toward said second surface at an angle greater than the critical angle in said optically transparent layer when a force greater than a predetermined force is applied to a location on said first surface.

8. The switch panel of claim 1 wherein said first surface deforms sufficiently when a predetermined pressure is applied thereto to cause a portion of said light signal to be reflected toward said second surface at an angle greater than the critical angle in said optically transparent layer.