Optical coupler for use in an optical touch sensitive device

• US 9,170,683 B2
• Filed: 07/23/2012
• Issued: 10/27/2015
• Est. Priority Date: 07/22/2011
• Status: Active Grant

• Current Assignee: Beechrock Limited
• Original Assignee: Rapt Ip Limited
• Inventors: Drumm, Owen
• Primary Examiner(s): Petkovsek, Daniel
• Application Number:
  US13/555,862
• Publication Number:
  US 20130021302A1
• Time in Patent Office: 1,191 Days
• Field of Search: 385/15, 385/31, 385/32, 385/39, 345/173, 345/175, 345/176
• US Class Current: 1/1
• CPC Class Codes: G02B 6/0028 Light guide, e.g. taper
• CPC Class Codes: G02F 1/13338 Input devices, e.g. touch panels
• 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
• CPC Class Codes: G06F 3/0428 by sensing at the edges of the touch surface the interruption of optical paths, e.g. an illumination plane, parallel to the touch surface which may be virtual sensing beam interruptions in a planar beam grid of an optical touch-screen G06F3/0421

Abstract

An optical touch-sensitive device is able to determine the locations of multiple simultaneous touch events. The optical touch-sensitive device includes multiple emitters and detectors coupled with an optical coupler assembly through a waveguide on the surface on the optical-touch sensitive device. The coupler may be side coupled or edge coupled to the waveguide. For both the side coupled or edge coupled cases, the coupler may also be configured to reorient beams to accommodate any orientation of emitters and detectors with respect to the waveguide. The coupler may also be configured to translate beams laterally or vertically to accommodate any position of emitters and detectors. The coupler, and touch-sensitive device more generally, are also configured to prevent ambient light entering the waveguide from hitting the emitters and detectors. Each emitter produces optical beams which are received by the detectors. Touch events disturb the optical beams.

Claims

1. An optical touch-sensitive device comprising:

a planar optical waveguide extending over a surface of a display, the waveguide having a top surface and a bottom surface;

emitters and detectors arranged along a periphery of the display and below the bottom surface of the waveguide;

an optical coupler assembly positioned along the periphery of the display coupled below the bottom surface of the waveguide, the optical coupler assembly coupling optical beams produced by the emitters into the waveguide and out of the waveguide to the detectors, the optical beams propagating through the waveguide via total internal reflection (TIR) off of the top and bottom surfaces of the waveguide wherein touches on the top surface of the waveguide disturb the optical beams, the touch-sensitive device determining touch events based on the disturbances, the optical coupler assembly comprising;

an upper surface and a lower surface, both formed parallel to the bottom surface of the waveguide, the upper surface forming an interface at which light enters from or exits to the waveguide,

a diagonal surface joining both the upper and lower surfaces and formed at an acute angle to the lower surface and an obtuse angle to the upper surface, measured within the optical coupler assembly, and

wherein one of the diagonal surface and the lower surface forms an interface at which light enters from or exits to an emitter or a detector, the other one of the diagonal surface and the lower surface being a surface upon which TIR of light occurs within the optical coupler assembly.

2. The optical touch-sensitive device of claim 1 wherein the optical coupler assembly comprises a first portion and a second portion, the first portion side optically coupled to the waveguide, the second portion butt coupled to the first portion, the second portion optically coupled to the emitters and detectors.

3. The optical touch-sensitive device of claim 1 wherein the emitters and detectors are oriented to emit and receive, respectively, optical beams in a direction substantially perpendicular to the plane of the waveguide.

4. The optical touch-sensitive device of claim 1 wherein the optical coupler assembly is configured such that optical beams passing through the optical coupler exit in a direction rotated approximately 90 degrees from the direction they entered the optical coupler.

5. The optical touch-sensitive device of claim 1 wherein the emitters and detectors are oriented to emit and receive, respectively, optical beams in a direction substantially parallel to the plane of the waveguide.

6. The optical touch-sensitive device of claim 1 wherein the optical coupler assembly is configured such that optical beams passing through the optical coupler assembly exit in a same direction that they entered the optical coupler assembly.

7. The optical touch-sensitive device of claim 1 wherein the optical beams entering the optical coupler assembly exit the optical coupler assembly along either a same direction or a reversed direction relative to the direction of entry into the optical coupler assembly.

8. The optical touch-sensitive device of claim 1 wherein the optical coupler assembly, emitters, and detectors are located outside a side edge of the display.

9. The optical touch-sensitive device of claim 1 wherein the optical coupler assembly comprises a light pipe configured to redirect optical beams a distance in a direction substantially perpendicular to the plane of the waveguide.

10. The optical touch-sensitive device of claim 9 wherein the light pipe comprises one or more reflective surfaces.

11. The optical touch-sensitive device of claim 1 wherein the optical coupler assembly comprises:

a planar coupling surface, wherein optical beams couple to the waveguide through the coupling surface at greater than a critical angle with respect to a normal from the bottom surface of the waveguide so that said optical beams are totally internally reflected within the waveguide; and

a planar light rejection surface, wherein ambient light that enters the optical coupler assembly through the coupling surface at less than the critical angle strikes the planar light rejection surface at less than the critical angle and exits the optical coupler assembly.

12. The optical touch-sensitive device of claim 11 wherein the planar light rejection surface is optically parallel to the planar coupling surface, and the optical coupler assembly is constructed of a material that has a same index of refraction as the waveguide.

13. The optical touch-sensitive device of claim 1 comprising an infrared transmissive layer optically coupled between the bottom surface of the waveguide and the optical coupler assembly, the light filtering layer configured to filter visible ambient light.

14. The optical touch-sensitive device of claim 1 wherein the optical coupler assembly comprises:

a planar coupling surface, wherein optical beams couple to the waveguide through the coupling surface at greater than a critical angle with respect to a normal from the bottom surface of the waveguide so that said optical beams are totally internally reflected within the waveguide; and

a light shield surface optical coupled between the bottom surface of the waveguide and the optical coupler assembly, the light shield configured to block ambient light incident on the emitters and detectors through the waveguide at an angle less than the critical angle.