Optical incoupling for touch-sensitive systems

• US 10,151,866 B2
• Filed: 12/09/2016
• Issued: 12/11/2018
• Est. Priority Date: 02/02/2011
• Status: Active Grant

• Current Assignee: FlatFrog Laboratories AB
• Original Assignee: FlatFrog Laboratories AB
• Inventors: Craven-Bartle, Thomas, Bergstrom, Hakan
• Primary Examiner(s): SHENG, TOM V
• Application Number:
  US15/374,446
• Publication Number:
  US 20170090090A1
• Time in Patent Office: 732 Days
• CPC Class Codes: G02B 6/0016 Grooves, prisms, gratings, scattering particles or rough surfaces
• CPC Class Codes: G06F 2203/04103 Manufacturing, i.e. details related to manufacturing processes specially suited for touch sensitive devices
• 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 touch-sensitive apparatus comprises a light transmissive panel (1), an illumination arrangement and a detection arrangement. The illumination arrangement is configured to couple light into the panel (1) via an incoupling site (5B) such that the light propagates by total internal reflection (TIR) in opposite top and bottom surfaces (4, 5) of the panel and such that an object touching the top or bottom surface (4, 5) causes a change in the propagating light. The detection arrangement comprises a light detector arranged to detect the change in the propagating light. A compact and robust incoupling site (5B) is defined by a sheet-like micro-structured surface portion (22) which is fixedly arranged on one of the top and bottom surfaces (4, 5) and configured to transmit light having an angle of incidence that enables light propagation by TIR inside the panel (1). The surface portion (22) may be integrated in the panel or implemented by a thin and flexible film (20) of light transmissive plastic material, formed with the micro-structured surface portion and adapted for attachment to the top or bottom surface (4, 5).

Claims

1. An apparatus, comprising:

a light guide that defines parallel top and bottom surfaces;

an illumination arrangement configured to couple light into the light guide via an incoupling site such that the light propagates by total internal reflection in at least one of the parallel top and bottom surfaces;

wherein

the incoupling site is defined by a sheet-like micro-structured surface portion,

the sheet-like micro-structured surface portion is fixedly arranged on one of the parallel top and bottom surfaces, and

the sheet-like micro-structured surface portion is configured to transmit light having an angle of incidence that enables light propagation by total internal reflection inside the light guide,

the sheet-like micro-structured surface portion includes a plurality of parallel elongate facets configured to collectively mimic a substantially continuous input surface for receiving the light to be coupled into the light guide, and

at least a subset of the plurality of parallel elongate facets include micro-lens elements.

2. The apparatus of claim 1, wherein the sheet-like micro-structured surface portion is included in a thin film attached to the light guide.

3. The apparatus of claim 2, wherein the thin film further comprises:

a sheet substrate of plastic material and facets formed by structuring and curing a resin on the sheet substrate of plastic material.

4. The apparatus of claim 3, wherein the thin film further comprises:

an adhesive backing opposite to the facets.

5. The apparatus of claim 2, wherein the thin film further comprises:

at least one line of weakness that extends in a transverse direction of the incoupling site.

6. The apparatus of claim 1, wherein the incoupling site is defined by a sequence of separate thin films arranged side by side in a longitudinal direction of the incoupling site.

7. The apparatus of claim 1, wherein the sheet-like micro-structured surface portion is further configured to project from said one of the parallel top and bottom surfaces by less than 1 mm.

8. The apparatus of claim 1, wherein all of the plurality of parallel elongate facets have substantially the same angle to a normal of the parallel top and bottom surfaces.

9. The apparatus of claim 1, wherein

each respective parallel elongate facet is bound by elongate release surfaces;

the elongate release surfaces extend parallel to the respective parallel elongate facet; and

the elongate release surfaces are substantially perpendicularly inclined relative to the respective parallel elongate facet.

10. The apparatus of claim 1, wherein

the plurality of parallel elongate facets extend in a longitudinal direction and are distributed in a transverse direction of the sheet-like micro-structured surface portion;

and

the illumination arrangement is further configured to direct light onto the sheet-like micro-structured surface portion such that the sheet-like micro-structured surface portion receives the light with a main direction that is substantially perpendicular to the plurality of parallel elongate facets at least in the transverse direction.

11. The apparatus of claim 1, wherein at least a subset of the plurality of parallel elongate facets have an individual inclination such that the sheet-like micro-structured surface portion is configured to affect the transmitted light.

12. The apparatus of claim 1, wherein at least the subset of the plurality of parallel elongate facets include a diffusing surface structure.

13. The apparatus of claim 1, wherein at least the subset of the plurality of parallel elongate facets are configured to separate incoming light into a number of distinct beams, the distinct beams having different main directions in a plane of the light guide.

14. The apparatus of claim 13, wherein the plurality of parallel elongate facets have a diffractive grating structure configured to separate the incoming light into the number of distinct beams.

15. The apparatus of claim 1, wherein the illumination arrangement is further configured to direct light onto the sheet-like micro-structured surface portion such that the sheet-like micro-structured surface portion receives collimated light in a transverse direction of the incoupling site.

16. The apparatus of claim 1, wherein the illumination arrangement is further configured to direct light onto the sheet-like micro-structured surface portion such that the sheet-like micro-structured surface portion receives divergent light in a transverse direction of the incoupling site.

17. The apparatus of claim 1, wherein the sheet-like micro-structured surface portion is integrated in the light guide.

18. An optical coupling element for coupling light into a light guide, the light guide having parallel top and bottom surfaces and being arranged to propagate light by total internal reflection, the optical coupling element comprising:

a film of light transmissive plastic material having a micro-structured surface portion and an attachment surface opposite to the micro-structured surface portion, wherein

the film of light transmissive plastic material is configured to attach to one of the parallel top and bottom surfaces to form at least part of an incoupling site,

the micro-structured surface portion is configured to transmit light that has an angle of incidence enabling light propagation by total internal reflection inside the light guide,

the optical coupling element has an elongated structure and is arranged at a peripheral edge surface of the light guide,

the micro-structured surface portion includes a plurality of parallel elongate facets configured to collectively mimic a substantially continuous input surface for receiving the light to be coupled into the light guide, and

at least a subset of the plurality of parallel elongate facets include micro-lens elements.

19. An apparatus, comprising:

a light guide that defines parallel top and bottom surfaces;

an illumination arrangement configured to couple light into the light guide via an incoupling site such that the light propagates by total internal reflection in at least one of the parallel top and bottom surfaces;

wherein the incoupling site is defined by a sheet-like micro-structured surface portion, the sheet-like micro-structured surface portion fixedly arranged on one of the parallel top and bottom surfaces, and the sheet-like micro-structured surface portion configured to transmit light having an angle of incidence that enables light propagation by total internal reflection inside the light guide;

wherein the sheet-like micro-structured surface portion includes a plurality of facets facing outward, away from the one of the parallel top and bottom surfaces; and

wherein at least a subset of the plurality of facets include micro-lens elements.

20. An optical coupling element for coupling light into a light guide, the light guide having parallel top and bottom surfaces and being configured to propagate light by total internal reflection, the optical coupling element comprising:

a film of light transmissive plastic material having a micro-structured surface portion and an attachment surface opposite to the micro-structured surface portion, the micro-structured surface portion including a plurality of facets, wherein

the film of light transmissive plastic material is configured for attachment to one of the parallel top and bottom surfaces with the plurality of facets facing outward away from the one of the parallel top and bottom surfaces, and to form at least part of an incoupling site,

the micro-structured surface portion is arranged to transmit light that has an angle of incidence enabling light propagation by total internal reflection inside the light guide, and

wherein at least a subset of the plurality of facets include micro-lens elements on the plurality of facets.