Lighting device with central symmetry for a dial
AssigneeAsulab S.A.
InventorsPascal Winkler, Gian-Carlo Poli, Joachim Grupp
Life of this patent
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Abstract
A light source (15) is housed in a housing (6) of a case, underneath the dial (10) opposite a guide (17) directing the light onto a reflector (20), formed in a hollow in the internal or external face of a crystal (1) the thickness of which decreases regularly from the centre to the periphery thereof for reorienting the light by total internal reflection into the crystal (1) until it emerges towards the dial (10) when the maximum refractive index is exceeded.
Claims14
Lighting device with central symmetry for a dial including at least one information display, said dial being arranged in a case closed at its top part by a crystal delimited by an external face and by an internal face and on its bottom part by a back cover delimiting with the dial a housing for receiving an energy source powering the display control means and a light source located in the housing, wherein the thickness of the crystal decreases regularly from the centre to the periphery thereof and in that a cylindrical light guide passes through the centre of the dial, one end of said guide being opposite the light source and the opposite end being opposite a reflector with axial symmetry formed in a hollow in the centre of the crystal for reorienting the rays from the light source by total internal reflection in the thickness of the crystal, and allowing them to emerge towards the dial when the angle of incidence on the inner face of the crystal is greater than the maximum angle of refraction.
Dependencies are inferred from the claim text.