Cerberus Ag

Peter Ryser

Kurt A Muller

Dieter Wieser

Michael T Gale

Rino Ernst Kunz

Peter Steiner

Sigfrid Strassler

Cornel Studach

Markus Rossi

Peter Marki

Christoph Enderli

George Wegmann

Markus Loepfe

In a technique for detecting organic vapors and aerosols, e.g. of amines, hydrazines and nitrogen-containing compounds produced in combustion, molecules condense at a surface of a conductive device. By heating the conductive device in pulsed fashion, e.g. by resistance heating, condensed molecules are thermally ionized and emitted from the conductive device. Emitted ions are collected by a collector electrode, and the resulting ionic current pulse is amplified by a transimpedance circuit. The heat pulse lasts until the ionic current pulse has subsided, by which time the conductive device has become free of residual substances. As a result, the conductive device remains uncontaminated and has a long service life. The time-averaged power consumption of the technique is less than 2 mW. For resistance heating, a meander heater element can be disposed on a silicon nitride membrane across an etched opening in a silicon chip. A separate conductive surface layer can be included in the conductive device, separated from the heater element by an insulating layer.

Method for detecting organic vapors and aerosols

The detector contains a structure-borne sound microphone connected to an electronic evaluation unit with a piezoelectric sensor (18) for structure-borne sound vibrations. This sensor has a vibrating bar (28), which is attached by means of hybrid technology to a carrier (27). The vibrating bar (28) is formed by a bimorph element and the carrier by an electrically conductive ceramic wafer.

Structure-borne sound detector for an intruder alarm system

Optical smoke detectors such as extinction smoke detectors and scattered-light smoke detectors include a radiation source, a radiation detector or receiver, and a measurement volume which is in communication with ambient atmosphere and which is traversed by a light path from the radiation source to the radiation receiver. For compactness and simplicity, such an optical smoke detector is provided with a planar-optical element in the optical path. Suitable as planar-optical elements are diffractive elements, e.g., holographic-optical elements (HOE), and micro-Fresnel elements (MFE), e.g., micro-Fresnel reflectors (MFR).

Optical smoke detector

In fire detector apparatus for monitoring an extended area from an elevated location, and especially for detecting forest fires, a scanning assembly (1) has azimuthal freedom of movement. A row of adjoining infrared detector element pairs (S, S') is disposed on a common support (7) in the focal plane of a reflector (6). Detector extent or area increases from the optical axis upward, and the detectors are connected with decreasingly sensitive circuitry. As a result, detection areas having different elevations have nearly equal distance range, and detection sensitivity is essentially independent of distance so that a remote forest fire is detected with the same degree of certainty as one close by. For the elimination of false alarms due to diffuse thermal radiation, detector elements are arranged in pairs, side-by-side on the same support (7), and connected in differential circuitry. For the elimination of false alarms due to intense sunlight, light-sensitive solar cells are connected in parallel with the infrared detectors in an inhibition circuit.

Apparatus for wide-area fire detection

To improve probability of detection in the early stages of fires, a fire alarm (1) with a temperature sensor (3) is proposed, having a structural member (12) that causes the sensor (3) to react only to temperature changes in the ambient air, and which change with a frequency of from 0.1 to 20 Hz. The fire alarm (1) becomes particularly insensitive to errors when there is a second fire sensor (7) that reacts to fire aerosol, there being a threshold value circuit (9) that lowers the threshold value for the fire aerosol sensor (7) when the temperature sensor (3) exceeds a preset threshold value.

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Stafa, Switzerland

Peter Ryser