Patent ID: 8487914

Claim:
An optical finger navigation device comprising a light guide film (LGF) comprising a finger interface surface, wherein at least a portion of the LGF exhibits total internal reflection (TIR); a light source in optical communication with the LGF to provide light from the light source to the finger interface surface, wherein the LGF further comprises a thin film between about 30 microns and about 100 microns thick that is configured for promoting number of internal light reflections and light interaction with a finger in contact with the finger interface surface; a sensor configured to detect light from the LGF in response to contact between the finger and the finger interface surface, wherein the contact between the finger and the finger interface surface modifies reflection of light out of the LGF to the sensor over at least a portion of the sensor; and a navigation engine configured to generate lateral movement information, which is indicative of lateral movement of the finger relative to the sensor, in response to the modification to the detected light.