Patent ID: 7795576
Filing Date: 2010-09-14
Classification: G01D,G02B

Abstract:
1. A single dome lens reflective optical encoder, comprising: a printed circuit board or lead frame substrate having a top surface with opposing first and second sides; a light emitter mounted on or attached to the first side and configured to emit light therefrom; a single track light detector mounted on or attached to the second side, the single track light detector comprising at least four light detectors corresponding to A, B, A and B data channels and an index channel light detector, the data and index channels being arranged along a common axis; an optically opaque light barrier disposed between the light emitter and the first side and the single track light detector and the second side, the light barrier being configured to prevent or inhibit direct light rays emitted by the light emitter from impinging directly upon the single track light detector, the light barrier being transfer or insert molded directly onto the top surface of the substrate, and a single dome lens comprising an optically transparent material, the single dome lens being formed over and in direct contact with the light emitter and the single track light detector such that no air gap is located between the light emitter and the dome or the light detector and the dome, the lens comprising a curved outer surface that is symmetric along a lens axis intersecting the common axis at a right angle thereto, the lens being transfer molded directly over the light emitter, the light detector and the light barrier; wherein the single dome lens is configured to permit light emitted from the light source to be refracted through portions thereof for reflection from a code scale or code wheel comprising index and data strips and configured to travel along the common axis, the code scale or code wheel being located operably in respect of the single dome lens such that at least a portion of the light reflected from the code strip or code wheel is directed towards the single dome lens and refracted through portions thereof for detection by the light detector, the optical encoder further being configured to provide a first output signal corresponding to the index channel and second output signals corresponding to the A and B data channels, the first output signal having a duration less than that of the second output signals.