Patent ID: 6657808
Filing Date: 2003-12-02
Classification: G11B

Abstract:
A sensor system for sensing the presence and absence of an object in an apparatus having a plurality of operating modes, comprising:a light-emitting element for emitting light; a switching element supplying power to said light-emitting element; a light-sensing element receiving the light emitted by said light-emitting element, conditional on the presence of said object, and converting the received light to an electrical signal indicating the presence or absence of said object; and a control unit controlling said switching element, thereby causing said light-emitting element to emit light continuously in one operating mode of said apparatus, and causing said light-emitting element to emit light in a pulsed manner in another operating mode of said apparatus; wherein said object includes a leading edge which is detected at the moment emitted light from said light-emitting element is no longer received by said light sensing element during an operating mode.