发明名称 |
DOCUMENT SENSING APPARATUS |
摘要 |
In a stop-and-display station in document-handling equipment wherein a document in a track is stopped and viewed through a transparent first wall, whereagainst it is supported by a non-transparent second wall, a reflective photosensor assembly is angled relative to the back wall such that a light beam from a light-emitting diode cannot be specularly reflected onto a phototransistor either from a document or from the inner surface of the transparent first wall. The phototransistor intercepts a portion of the scatter-reflected light from the document. The light from the light-emitting diode is modulated with a predetermined frequency, and the output signal from the phototransistor is filtered by a band-pass filter before threshold detection to provide indication of the presence of a document. A turn-off delay circuit prevents loss of indication of the presence of a document unless signals from the phototransistor have been absent for longer than a predetermined period. The apparatus resists false alarms of the presence of a document in consequence of extraneous light and extraneous reflections. The turn-off delay circuit prevents marks on the back face of the document inadvertently causing loss of signal indicative of document presence. |
申请公布号 |
DE3473657(D1) |
申请公布日期 |
1988.09.29 |
申请号 |
DE19843473657 |
申请日期 |
1984.10.09 |
申请人 |
UNISYS CORPORATION |
发明人 |
WONG, PHILIP;ROGER, STEPHEN JOHN;BRYANT, JOHN DAVID |
分类号 |
B65H7/14;G06K13/067;H04N1/00;(IPC1-7):G06K7/10;G06K5/00 |
主分类号 |
B65H7/14 |
代理机构 |
|
代理人 |
|
主权项 |
|
地址 |
|