Keypad light guide
AssigneeSutech Trading Limited
InventorsTung-Ming Hsu, Wen-Feng Cheng
Life of this patent
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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.
Claims12
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 positioned at one side of said array of indicators along said side of said electronic device, said light source disposed at one end of said light guide, and said light guide 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, wherein a reflecting angle of said at least one reflecting surface is determined by the following formula:
- γ=η+α−90
- where α is said reflecting angle of said at least one reflecting surface, η is an incidence angle of light rays, and γ is an angle of said at least one reflecting surface relative to an imaginary center line of said light guide.
A method of manufacturing a light guide for contributing to illuminating an array of indicators, the method comprising the steps of:
- forming a base of a light guide from light-transmissible material;
- defining a groove in one end of the light guide, for receiving light from a light source;
- forming an array of apertures in said base corresponding to an 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, said reshaping step comprising 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, and said reflecting angle of said reflecting surface is determined by the following formula:
- δ=η+α−90
- where α is said reflecting angle of said reflecting surface, η is an incidence angle of light rays, and γ is an angle of said reflecting surface relative to an imaginary center line of said light guide.
Dependencies are inferred from the claim text.