Keypad light guide

• US 20060092619A1
• Filed: 11/01/2005
• Published: 05/04/2006
• Est. Priority Date: 11/04/2004
• Status: Active Grant

• Current Assignee: FIH (Hong Kong) Limited (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: FIH Co., Ltd. (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Hsu, Tung-Ming, Cheng, Wen-Feng
• Granted Patent: US 7,407,314 B2
• Time in Patent Office: Days
• US Class Current: 362/26
• CPC Class Codes: G02B 6/0018 Redirecting means on the surface of the light guide
• CPC Class Codes: G02B 6/006 to produce indicia, symbols, texts or the like
• CPC Class Codes: H01H 13/83 characterised by legends, e.g. Braille, liquid crystal displays, light emitting or optical elements
• CPC Class Codes: H01H 2219/044 Edge lighting of layer
• CPC Class Codes: H01H 2219/06 Reflector
• CPC Class Codes: H01H 2219/062 Light conductor
• CPC Class Codes: H01H 2229/054 CAD
• CPC Class Codes: H04M 1/22 Illumination; Arrangements for improving the visibility of characters on dials

Abstract

A light guide (20) for illuminating keys of a keyboard or keypad of a portable electronic device, includes an array of apertures (22) and a groove (21) at one end of the light guide. The apertures are configured to illuminate the keys via a light source (10). The light source is disposed adjacent to the groove. A peripheral wall around each aperture is configured partially as a reflecting surface, and partially as a transmitting surface. The reflecting angle of the reflecting surface is larger than a critical total internal reflection angle so as to transfer the light farther. The light guide has a desired uniform light by means of a light source. This provides the portable electronic device consuming little power.

Claims

1. An electronic device comprising:

an array of indicators capable of exposing readable information to an outside of said electronic device along a side of said electronic device;

a light source used for providing light to illuminate said array of indicators; and

a light guide installable between said light source and said array of indicators along said side of said electronic device, and capable of receiving said light from said light source and transmitting said light toward said array of indicators, said light guide comprising an array of apertures corresponding to said array of indicators in order for respectively accommodating said array of indicators therein, more than one aperture of said array of apertures configured to form at least one reflecting surface along a peripheral wall thereof so as to reflect said light inside said light guide from said light source toward other apertures of said array of apertures for illumination of said array of indicators therein.

2. The electronic device as claimed in claim 1, wherein said reflecting surface is a selective one of a planar surface and an arcuate surface along said peripheral wall of said more than one aperture of said array of apertures.

3. The electronic device as claimed in claim 1, wherein a reflection angle of each of said at least one reflecting surface is controlled to be larger than a critical total internal reflection angle of said light guide.

4. The electronic device as claimed in claim 1, wherein a groove is formed on said light guide to face said light source and receive said light from said light source, an angle of said groove is in the range of 70-90 degrees.

5. The electronic device as claimed in claim 4, wherein a height of said groove is determined by the following formula:

h=(w₂/2)/tan(θ

/2)

where h is a height of said groove, θ

is an angle of said groove, and w₂ is a width of said groove.

6. The electronic device as claimed in claim 5, wherein said width of said groove is determined by the following formula:

w₂=w₁+(1−

2 mm)

where w₂ is said width of said groove, and w₁ is a width of an effective illuminating area measured from said light source.

7. The electronic device as claimed in claim 1, wherein said light guide is made of a selective one of Polymethyl Methacrylate and Polycarbonate.

8. The electronic device as claimed in claim 1, wherein a thickness of said light guide is in a range of 0.8-1.2 millimeters.

9. A light guide for illuminating keys of a keyboard or keypad of a portable electronic device, comprising:

an array of apertures defined therein, and being configured to illuminate the keys via a light source;

a groove in one end of the light guide, for receiving light from the light source;

a plurality of recesses defined among any three or more of the apertures, each recess having a peripheral wall;

wherein the peripheral wall of each recesses functions as a reflecting surface, and as a transmitting surface;

a reflecting angle of the reflecting surfaces of each recess is greater than a critical total internal reflection angle.

10. The light guide as claimed in claim 9, wherein the reflecting surfaces are planar and/or arcuate.

11. The light guide as claimed in claim 9, wherein an angle of the groove is in the range of 70-90 degrees.

12. The light guide as claimed in claim 9, wherein the light guide is made of Polymethyl Methacrylate or Polycarbonate.

13. The light guide as claimed in claim 9, wherein a thickness of the light guide is in the range of 0.8-1.2 millimeters.

14. A method of manufacturing a light guide for contributing to illuminating an array of indicators, comprising the steps of:

forming a base of a light guide from light-transmissible material;

forming an array of apertures in said base corresponding to arrangement of an array of indicators so that each aperture of said array of apertures is capable of accommodating a respective one of said array of indicators; and

reshaping at least one aperture of said array of apertures in order to create a reflecting surface along a periphery wall of said at least one aperture of said array of apertures.

15. The method as claimed in claim 14, further comprising the step of confirming a position for said each aperture and a number of light sources to be used with said light guide before said aperture-forming step.

16. The method as claimed in claim 15, further comprising the step of simulating an initial design for said light guide so as to perfect said position for said each aperture based on simulated results of light illumination.

17. The method as claimed in claim 14, wherein said reshaping step comprises the step of adjusting a reflecting angle of said reflecting surface of said at least one aperture so as to be larger than a critical total internal reflection angle of said light guide.

18. The method as claimed in claim 17, wherein said reflecting angle of said reflecting surface is determined by the following formula:

γ

=η

+α

−

90

where α

is the reflecting angle of the reflecting surface, η

is an incidence angle of light rays, and γ

is an angle of the reflecting surface relative to an imaginary center line of the light guide.

19. The method as claimed in claim 17, wherein a target angle of the reflecting surface is determined by the following formula:

λ

=90−

γ

−

α

where α

is the reflecting angle of the reflecting surface, λ

is a target angle of the reflecting surface, and γ

is an angle of the reflecting surface relative to an imaginary center line of the light guide.