Abstract:
The invention relates to a micromechanical sensor device and a corresponding production method. The micromechanical sensor device comprises a substrate (1) having a front (VS) and a rear (RS), a plurality of pillars (S1, S2) being formed on the front (V) of the substrate (1). On each pillar a respective sensor element (P1, P2) is formed, which has a greater lateral extent than the associated pillar (S1, S2), a cavity (H) being provided laterally to the pillars (S1, S2) beneath the sensor elements (P1, P2). The sensor elements (P1, P2) are laterally spaced apart from each other by means of respective separating troughs (G1, G2) and make electrical contact with a respective associated rear contact (V6, E1; V7, E1) via the respective associated pillar (S1, S2).
Abstract:
Thermal radiation detection apparatus is provided comprising an array of pyroelectric detectors 1,2,3,4 in which compensation is provided for the effect of ambient temperature changes on the detector outputs and also for d.c. offsets which occur in source follower impedance converters 13 necessarily used with each detector. Single element detectors are used, the end pair of elements 3,4 being shielded from radiation and used as reference elements. Each element has a pair of diodes 11,12 connected in parallel in opposite sense to provide a d.c. path across the element. The reference element outputs are averaged 16,17,18 and fed via a high gain negative feedback loop 19 to the common connection 10 of all the elements. Offset voltages and element signals generated by ambient temperature changes are thereby compensated to the extent that the reference offsets and thermal voltages equal those of the active detector elements.
Abstract:
A miniature passive infrared motion detector contains an optical system, a pyroelectric polymer film and an electronic circuit. The optical system is made of a curved Fresnel lens (3) and an elongated wave guide having reflective inner surfaces (1, 4). This affords a very wide field of view by the optical system with the energy (9) of an intruder, for example, focused to a small point on the polymer film (8) which is also curved with the same radius as the lens (3) and has two interdigitized electrodes (6, 7) on the rear surface and one uniform electrode (33) on the front surface. The front electrode (33) is covered with infrared absorbent material. The electronic circuit contains a differential amplifier (14) and a threshold network (22).
Abstract:
A thermal radiation detection apparatus has an array of pyroelectric detector devices (10) for receiving radiation from a scene whose outputs, e.g. from associated source followers (12) are supplied via a multiplexer (14) in turn to a processing circuit (20) which is responsive to each detector device signal to produce an output which substantially faithfully reproduces the received radiation signal without requiring that a chopper be used. The processing circuit operates with a correction factor to produce an output signal with first and second components proportional respectively to the device signal and its rate of change, the relative proportions of the components being in a ratio according to the device's thermal time constant. Initial device voltage level and the device's electrical time constant effects can be corrected by additional processing in the circuit (20), producing a third component of the output proportional to the integral of the device's output and in a ratio to the first component according to the electrical time constant.
Abstract:
A thermal pattern sensor comprising a plurality of pixels, each pixel comprising at least one pyroelectric capacitor formed by at least one portion of pyroelectric material arranged between a lower electrode and an upper electrode, in which one of the lower and upper electrodes corresponds to an electrode for reading the pixel and in which a heating element that can heat the portion of pyroelectric material of the pyroelectric capacitor of the pixel by Joule effect during a measurement of the thermal pattern by the pyroelectric capacitor of the pixel is formed by the other of the lower and upper electrodes.
Abstract:
A motion sensor has at least two tiers of monitored volumes that are offset from each other. Electromagnetic radiation, such as infrared light, is directed from the monitored volumes onto at least two sets of detector elements having separate outputs on a pyroelectric substrate of an infrared detector. As a warm object, such as a human or an animal, moves through the monitored volumes, the warmth from the object causes the voltage on the outputs of the infrared detector to change. The resultant waveforms are compared and if the two waveforms have a phase relationship corresponding to a critical phase angle that is based on the pitch of the monitored volumes and the offset between the tiers of monitored volumes, an animal-immune motion indication is generated.