Patent ID: 8585211

Claim:
An optical sensing apparatus with anti-dust structure for sensing a rotation device having a rotation surface encircling and rotating around a rotating axis along a rotation direction, the optical sensing apparatus comprising: a base; an optical sensor, disposed on the base, the optical sensor having a sensing surface opposite to the rotation device, a first distance being formed between the sensing surface and the rotation surface; and a stop block, disposed at a side of the optical sensor, the stop block and the optical sensor being disposed on the base in accordance with an order of the rotation direction to form a narrow flow passage between a stagnation surface of the stop block and the rotation surface, a second distance being formed between the stagnation surface and the rotation surface, wherein the second distance is smaller than or equal to the first distance, and when the rotation device rotates, an air flow induced by the rotation surface passes through the narrow flow passage before the optical sensor.