发明名称 |
Intrusion detection systems employing automatic sensitivity adjustments |
摘要 |
An automatic test circuit for a photo electric intrusion system incorporates an electronic attenuator which serves to reduce the sensitivity of the receiver when a light beam does not impinge on a photocell located at the receiver. As soon as the light beam appears on the photocell, the sensitivity of the receiver is increased to a normal operating value. In this manner, if the beam were misaligned to cause less light to impinge on the photocell, the receiver would indicate an alarm condition to thereby inform a user of the problem.
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申请公布号 |
US4064509(A) |
申请公布日期 |
1977.12.20 |
申请号 |
US19760706210 |
申请日期 |
1976.07.19 |
申请人 |
NAPCO SECURITY SYSTEMS, INC. |
发明人 |
STOCKDALE, ROY |
分类号 |
G08B29/04;(IPC1-7):G08B13/18 |
主分类号 |
G08B29/04 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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