Abstract: A passive infrared sensor has two or more element arrays, each consisting of positive polarity and negative polarity elements. The signals from the arrays are both summed together and subtracted from each other, and if either the sum or difference signal exceeds a threshold, detection is indicated.

Abstract: A temperature detection system for detecting relative or absolute temperatures of objects in a monitored area has at least one infrared (IR) detector and at least one optical element for directing IR radiation within a detector field of view onto the infrared detector. A scanning system is configured to produce relative movement between the optical element and the IR detector such that the detector field of view is scanned across a monitored area to receive IR radiation from objects in the monitored area. A signal processing module for receiving the detector output signal is configured to produce an output profile of the relative temperatures of objects in the monitored area. The IR detector may be a pyroelectric detector.

Abstract: A piezoelectric detector circuit has at least one input line, a piezoelectric transducer in the input line, an amplifier receiving signals on the input line and generating an output, and one or two feedback elements through which the output is sent back to the input line. The circuit may be a discrete time sampled operational amplifier (DTOA) based transconductance or “voltage output mode” circuit. In one embodiment, protection elements are associated with amplifier input lines to establish a reference voltage.

Abstract: A small portable housing has a battery-powered LED and an adhesive layer that can be detachably stuck on a wall near a light switch. A PIR motion detector in the housing activates the LED when the room is dark and motion is sensed.

Abstract: A transconductance monitoring and amplifying circuit for a piezoelectric transducer that may be used in, e.g., a motion detector system includes a FET, with the transducer (and, hence, the signal voltage reference) floating between the gate and source of the FET, as opposed to being connected to the common ground of the circuit. This permits the development of a larger detector signal and concomitantly the use of a relatively inexpensive FET instead of a relatively more expensive high impedance operational amplifier as must be used in conventional transconductance circuits. The FET and transducer can be held in a single four-pin package. A discrete time sampled operational amplifier may also be used.

Abstract: A passive infrared sensor has two detection members established by respective detectors and optical elements, with alternating spatial volumes being monitored by each detection member. No dead space need exist between volumes. The detection members are configured such that a moving object causes the members to output different frequencies, whereas a non-moving stimulus produces the same frequency from both detection members.

Abstract: A passive infrared sensor has two detector elements, each of which has a positive part and a negative part, with each detector element generating respective first and second signals. The signals are added together to render a “sum” signal and are also subtracted one from the other to render a “difference” signal, and a moving object is indicated only when the “sum” signal has a frequency different than the frequency of the “difference” signal.

Abstract: A transconductance monitoring and amplifying circuit for a piezoelectric transducer that may be used in, e.g., a motion detector system includes a FET, with the transducer (and, hence, the signal voltage reference) floating between the gate and source of the FET, as opposed to being connected to the common ground of the circuit. This permits the development of a larger detector signal and concomitantly the use of a relatively inexpensive FET instead of a relatively more expensive high impedance operational amplifier as must be used in conventional transconductance circuits. The FET and transducer can be held in a single four-pin package.