Patent ID: 7223009
Filing Date: 2007-05-29
Classification: G02B,G02F

Abstract:
1. A backlighting device for an information display element of a portable object said device comprising a light guide plate having a front face and a rear face, a light reflector located on the rear face of the light guide plate, a single source of visible light, which is a light emitting diode for feeding light beams to a boundary or edge of the light guide plate, which spread in the light guide plate and between said rear and front faces, and a layer located from a-side of the front face of the light guide plate intended to face a rear face of the display element of the portable object, said layer having at least one zone with partial opacity decreasing from a limit located close to a boundary area of the light guide plate, which receives the light beams of the light emitting diode located below and close to a visible portion of the display element, in order to attenuate the intensity of the light crossing said zone, wherein the zone with partial opacity is obtained by a shading white or silver dye applied to the layer or integrated into the layer, or by a semi-transparent metal covering of variable thickness, or by a metal covering pierced by a plurality of holes of varying diameter and spacing, which are smaller in size than a resolution of a human eye, or by a metal covering formed from a plurality of metal dots of varying diameter and spacing so that light beams are partially reflected and returned into the light guide plate to reduce the losses of useful photons, and wherein the light guide plate has, on a periphery thereof, a rounded corner covered a light-reflecting layer, said light emitting diode being disposed below the rounded corner in order to feed the light beams in a vertical direction in relation to the rear face of the light guide plate so that said beams are reflected by the reflecting layer at the edge of the light guide plate and spread into the light guide plate between the front and rear faces.