Light out-coupling arrangement and a touch sensitive system comprising the out-coupling arrangement

摘要

The disclosure relates to a light out-coupling arrangement for a touch sensitive system comprising a light guide of a material with a refractive index ng and a top surface configured to be exposed to ambient light, and a bottom surface. The out-coupling arrangement comprises at least one detector arranged along the periphery of the light guide and configured to receive the light propagating in the light guide and an optical filter provided between the light guide and the at least one detector. The optical filter has a first side and a second side where the first side is arranged to face the at least one detector, and the second side is arranged to receive light from the light guide. The optical filter is made of a medium with a refractive index nf less than the refractive index ng of the light guide, such that ambient light incident onto the second side at an angle larger than a critical angle θc from a normal of the second side will be reflected on the optical filter by total internal reflection and will not reach the at least one detector. The disclosure also relates to a touch sensitive system comprising a light out-coupling arrangement.

主权项

1. A light out-coupling arrangement for a touch sensitive system, wherein the touch sensitive system comprises a light guide of a material with a refractive index ng and a top surface configured to be exposed to ambient light, and a bottom surface, the touch sensitive system further has an in-coupling arrangement comprising at least one emitter arranged along the periphery of the light guide and is configured to emit light into the light guide whereby the light propagates in the light guide via total internal reflection, TIR,
wherein the out-coupling arrangement comprises at least one detector arranged along the periphery of the light guide and configured to receive the light propagating in the light guide; an optical filter provided between the light guide and the at least one detector, wherein the optical filter has a first side and a second side where the first side is arranged to face the at least one detector, and the second side is arranged to receive light from the light guide, the optical filter is further made of a medium with a refractive index nf less than the refractive index ng of the light guide, such that ambient light incident onto the second side with an angle larger than a critical angle θc from a normal of the second side, will be reflected on the optical filter by total internal reflection and will not reach the at least one detector.