Patent ID: 8031186

Claim:
An optical touchpad system comprising: one or more emitters configured to emit electromagnetic radiation; one or more sensors configured to receive electromagnetic radiation and output one or more output signals that correspond to one or more properties of the received electromagnetic radiation; a waveguide that guides a portion of the electromagnetic radiation emitted by the emitters to the sensors, the waveguide comprising: an irradiation layer that is optically coupled to the one or more emitters to receive electromagnetic radiation emitted therefrom, an interface surface spaced apart from the irradiation layer, the interface surface being configured to be engaged by a user with an object; and a signal layer separate from the irradiation layer that is optically coupled to the one or more sensors, wherein the waveguide is configured such that (i) if the interface surface is not deformed, the electromagnetic radiation received by the irradiation layer from the one or more emitters is kept wholly within the irradiation layer by total internal reflection, and (ii) if the interface surface is engaged with the object such that the engagement therebetween causes a local deformation in the irradiation layer, wherein a first portion of an irradiation layer surface is deformed while a second portion of the irradiation layer surface is not deformed, such local deformation of the irradiation layer causing the portion of the electromagnetic radiation incident on the local deformation to be reflected towards the signal layer at an angle such that the portion of the electromagnetic radiation reflected at the local deformation is leaked from the irradiation layer into the signal layer and guided to the one or more sensors at least in part by reflection within the signal layer.