Inventors:
James W. Cross - Livonia MI
Assignee:
Unisys Corporation - Blue Bell PA
International Classification:
G01N 904
Abstract:
An optical sensor for detecting a document moving along a document path. The invention provides at least two light paths across the document path, so that the document breaks at least one of the light paths as it moves along the document path, and this broken light path indicates the presence of the document. In an exemplary embodiment, the optical sensor comprises a photo-emitter that emits light across the document path to provide the first light path. A first reflector is optically coupled to the photo-emitter, and receives and reflects the light emitted by the photo-emitter. At least a second reflector is optically coupled to the first reflector to receive the light from the first reflector and to reflect that light across the document path to provide the second data path. A photo-detector is disposed across the light path from the second reflector and is optically coupled to the second reflector. The photo-detector is operable to detect the presence of the document by detecting when the document has broken at least one of the light paths.