Infrared intrusion detector with pyroelectric sensor and charge amplifier
First Claim
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1. An infrared intrusion detector comprising:
- a pyroelectric detector element;
an evaluation circuit serving for giving an alarm signal in the event of a change in radiation of the detector element caused by a moving object;
said evaluation circuit being operatively connected with said pyroelectric detector element;
said evaluation circuit containing a charge amplifier;
said detector element having an output;
said charge amplifier having an input; and
the input of the charge amplifier being connected with the output of the detector element.
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Abstract
An infrared intrusion detector, utilizing as a sensor element a pyroelectric detector element, accomplishes evaluation of the output signal of the detector element with a charge amplifier, for instance by means of a capacitive feedback coupled operational amplifier, the output signal of which is reset at certain time intervals. The evaluation circuit operates independently of the detector capacitance and therefore enables optimum utilization of the pyroelectrical properties. By virtue of the short-circuit operation and the low ohmic properties of the circuit there is obtained a particularly good non-sensitivity against external disturbances and low noise and increased sensitivity.
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12 Claims
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1. An infrared intrusion detector comprising:
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a pyroelectric detector element; an evaluation circuit serving for giving an alarm signal in the event of a change in radiation of the detector element caused by a moving object; said evaluation circuit being operatively connected with said pyroelectric detector element; said evaluation circuit containing a charge amplifier; said detector element having an output; said charge amplifier having an input; and
the input of the charge amplifier being connected with the output of the detector element. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification