US Patent 10146376 Light coupling in TIR-based optical touch systems

A touch-sensitive apparatus operates by light frustration (FTIR) and comprises a light transmissive panel that defines a front surface and a rear surface, a light emitter optically connected to the panel so as to generate light that propagates by total internal reflection inside the panel, and a light detector optically connected to the panel to receive propagating light from the emitter. The emitter is a VCSEL array including a number of VCSELs driven to collectively form one light emitter, and a light coupling mechanism connecting the emitter to the panel is configured to give light from a plurality of the VCSELs in the VCSEL array substantially the same spread in the panel.