Method for coupling light into a thin planar waveguide

• US 8,155,489 B2
• Filed: 11/02/2006
• Issued: 04/10/2012
• Est. Priority Date: 11/02/2006
• Status: Active Grant

• Current Assignee: Nokia Technologies Oy (Nokia Corporation)
• Original Assignee: Nokia Corporation
• Inventors: Saarikko, Pasi Risto Olavi, Levola, Tapani Kalervo, Laitinen, Pauli
• Primary Examiner(s): RAHLL, JERRY T
• Application Number:
  US12/513,255
• Publication Number:
  US 20100220956A1
• Time in Patent Office: 1,986 Days
• Field of Search: 362/628
• US Class Current: 385/49
• CPC Class Codes: G02B 6/0028 Light guide, e.g. taper
• CPC Class Codes: G02B 6/0036 2-D arrangement of prisms, protrusions, indentations or roughened surfaces
• CPC Class Codes: G02B 6/006 to produce indicia, symbols, texts or the like
• CPC Class Codes: H04M 1/22 Illumination; Arrangements for improving the visibility of characters on dials

Abstract

A light distributing device (100) comprises a thin planar waveguide (10) and a waveguiding ridge (20). An incoming light beam (B1) coupled into the ridge (20) forms a second light beam (B2) waveguided in the ridge (20). The ridge (20) and the planar waveguide (10) have a common portion (23) such that light is further coupled from the side of the ridge (20) into the planar waveguide (10) through said common portion (23). Thus, optical power of a broad incoming beam (B1) may be effectively coupled to a relatively thin planar waveguide (10). The planar waveguide (10) may further comprise diffractive out-coupling elements (30) to direct light towards a display (400).

Claims

1. A device comprising:

a ridge,

a substantially planar waveguide having a first surface and a second surface and comprising a plurality of out coupling portions on one of or on both of the first or second surfaces of the substantially planar waveguide,

wherein said ridge has an end for coupling light into said ridge in order to form a light beam waveguided longitudinally within said ridge, said ridge and said substantially planar waveguide having a common portion to couple light out of said ridge sideways into said substantially planar waveguide, and said out-coupling portion being adapted to couple light out of the substantially planar waveguide, the light having substantially non-uniform intensity distribution on the first and second surfaces; and

at least one of;

a set of proximity sensors positioned under the substantially planar waveguide opposite the planar surface, and at least partially transparent touch sensitive elements positioned over the substantially planar waveguide adjacent to the planar surface for providing in the device a keypad or a keyboard.

2. The device according to claim 1, wherein at least one of said out-coupling portions comprises a diffraction grating.

3. The device according to claim 1, wherein said ridge comprises one or more light redistributing features implemented on a wall of the ridge to enhance coupling of the light from the ridge to the substantially planar waveguide.

4. The device according to claim 3, wherein each of the one or more light redistributing features is implemented as a diffraction grating or a prism.

5. The device according to claim 1 further comprising a light source, wherein the end of said ridge is arranged to couple light emitted from said light source into said ridge so as to form the light beam waveguided longitudinally within said ridge.

6. The device according to claim 5 further comprising a keyset, wherein said at least out-coupling element is adapted to direct light out of the plane of said planar waveguide in order to form at least one light beam associated with features of said keyset.

7. The device according to claim 5 further comprising a display, wherein said at least out-coupling element is adapted to direct light out of the plane of said planar waveguide in order to form at least one light beam adapted to provide light to said display.

8. The device according to claim 1, in which the ridge comprises a first ridge and the common portion comprises a first common portion;

the device further comprising;

a second ridge having a second common portion to couple light out of said second ridge sideways into said substantially planar waveguide;

in which the first and second common portions are disposed along opposed sides of the substantially planar waveguide.

9. The device according to claim 1, in which the device comprises the at least partially transparent touch sensitive elements.

10. The device of claim 1, wherein at least two of the plurality of out coupling portions comprise diffraction gratings having a different direction of diffraction features.

11. The device of claim 1, wherein at least one of the plurality of out coupling portions is transmitted through the substantially planar waveguide.

12. The device of claim 1, wherein the light out of the substantially planar waveguide have an average direction at an angle with a perpendicular to the substantially planar waveguide between zero and seventy degrees.

13. A device comprising:

a ridge having two or more bifurcated branches; and

a substantially planar waveguide comprising at least one out-coupling portion, wherein said ridge has an end for coupling light into said ridge in order to form a light beam waveguided longitudinally within said ridge and the bifurcated branches, said ridge and said planar waveguide having a common portion to couple light out of said ridge and the bifurcated branches sideways into said planar waveguide, and said out-coupling portion being adapted to couple light out of the plane of said planar waveguide.

14. A device comprising a light distributing means, said light distributing means comprising:

a first waveguiding means having a first surface and a second surface and comprising a plurality of light out-coupling means on one of or on both of the first or second surfaces of the first waveguiding means, and

a second waveguiding means, wherein the second waveguiding means is thicker than said first waveguiding means,

said second waveguiding means having a light receiving means to couple light into said second waveguiding means to form a light beam waveguided longitudinally in said second waveguiding means,

said first waveguiding means and said second waveguiding means having a common portion to couple light out of said second waveguiding means sideways into said first waveguiding means, and

said out-coupling means being adapted to couple light out of the first waveguiding means, the light having substantially non-uniform intensity distribution on the first and second surfaces;

the device further comprising at least one of a set of proximity sensors positioned under the first waveguiding means opposite the planar surface, and at least partially transparent touch sensitive elements positioned over the first waveguiding means adjacent to the planar surface for providing in the device a keypad or a keyboard.

15. The device according to claim 14 further comprising a light source, wherein said light receiving means is arranged to couple light emitted from said light source into said second waveguiding means.

16. The device according to claim 14, in which the second waveguiding means comprises a first and a second ridge disposed along opposed sides of the first waveguiding means.

17. The device according to claim 14, in which the device comprises the at least partially transparent touch sensitive elements.

18. The device of claim 14, wherein at least two of the plurality of out-coupling means comprise diffraction gratings having a different direction of diffraction features.

19. The device of claim 14, wherein at least one of the plurality of out-coupling means is transmitted through the first waveguiding means.

20. The device of claim 14, wherein the light out of the first waveguiding means have an average direction at an angle with a perpendicular to the first waveguiding means between zero and seventy degrees.