Abstract: A smoke detector is disclosed in which smoke particles are detected by the collection and detection of blue light and infra-red radiation which are emitted into a predetermined path through a scattering volume where the particles may be present. The scattered blue light and the scattered infra-red radiation are collected by an ellipsoidal mirror and focussed onto a suitable detector and then compared to produce an output which indicates either that the detected particles are smoke particles or that they are not smoke particles. The radiation collected by the mirror has been scattered through angles substantially less than 45° and preferably between about 10° and 35°.

Abstract: Particle detecting apparatus for detecting other particulate matter comprises a measuring section and an input/output section removably attached together. A measuring chamber receives gaseous fluid by diffusion from a receiving chamber connected via an inlet to an area being monitored. The measuring chamber comprises a cylindrical body housing pairs of light emitting diodes positioned diametrically opposite, and directing light towards, each other through a sampling volume viewed by a photo-diode through a viewing aperture. The photo-diode detects light scattered by particles in the sampling volume. A glass tube protects the LEDs from contamination and can easily be cleaned or removed. Each LED can temporarily be de-energised in turn so as to act as a light detector, its output in response to light received from the opposite LED being thus a measure of any contamination. The measuring and input/output sections can easily be separated for servicing or replacement.

Abstract: A description is given of a rain indicator (1), which has a light source in the form of a light emitting diode (36) and a light detector in the form of a photodiode (37). There is a light guide (20) made from a material transparent to the light of the light source and e.g. glass, which has at least one surface portion (45, 46) exposed to the precipitation and which is so positioned relative to the light source that the light source light is totally reflectable towards the light detector on the surface portion. When the surface portion is dry light passes by total reflection to the light detector. In the case of precipitation a gap (43, 44) adjacent to the surface portion fills with liquid and the light intensity is substantially coupled out of the light guide (20) and no light passes to the light detector. Total reflection again occurs when the gap dries out.

Abstract: A photoelectric smoke detector includes a photoelectric chamber having a housing fabricated from an electrically conductive material.

Abstract: Moisture detection permits moisture removal equipment, such as automotive windshield wipers and defogger systems, to be operated automatically. A system for detecting moisture on a surface includes a light emitter directed at the surface. The presence of moisture is based on the intensity of light from the emitter reflected by the surface and received by a light sensor. The light sensor accumulates charge in response to incident light over a variable integration period.

Abstract: A control device and method provides control of at least one operating feature of a cooking device in response to measured smoke and/or gas produced by item(s) being cooked. The device and method may control the temperature and cooking time of the device, and may also shut off the device or provide a fire alarm.

Abstract: An improved self-cleaning oven (10) is provided having an assembly (12) to control the cleaning cycle time of the oven (10) depending upon the degree of oven contamination and soil present therein. The assembly (12) includes a measuring chamber (16) as well as a passageway (18) communicating the interior (14) of the oven (10) and the chamber (16). A smoke detector (32) (preferably an infrared smoke detector) is associated with the chamber (16) and is coupled with a controller (20) so as to measure a parameter of smoke passing through the chamber during at least a portion of the cleaning cycle. This parameter is then used to determine the proper duration of the cleaning cycle. In preferred forms, measuring chamber (16a) is equipped with an ambient air inlet (52) and outlet (54) so as to draw an ambient air stream through the chamber (16a) between the smoke detector (32) and the oven gas stream.

Abstract: It is prevented that a malfunction occurs because of a noise. A smoke detection section samples as a smoke detection signal a signal digitized after being output from a light reception section when a light emission section glows, and updates a previous smoke detection signal. A noise detection section samples as a noise detection signal a signal output from the light reception section when the light emission section is not driven to glow. When the noise detection signal exceeds a predetermined noise level, a noise de-influence unit disables updating of the previous smoke detection signal with the newly sampled smoke detection signal so as to process a noise.

Abstract: A smoke detector includes a housing defining a dark chamber admitting test atmosphere. A light receiver is disposed within the chamber. A scatter emitter is positioned within the chamber such that light strikes the receiver when reflected off particles suspended in the test atmosphere. An obscuration emitter is positioned within the chamber such that light emitted is directed to the receiver unless obstructed by particles suspended in the test atmosphere. A smoke detect signal is generated responsive to a measurement made responsive to the scatter emitter and/or the obscuration emitter.

Abstract: The invention relates to a method for detecting objects which are located on a transparent panel and which produce light reflexes when illuminated, using a detector unit containing one or more optical sensor arrays.

Abstract: A vehicular rain sensor which senses precipitation at a vehicle window. The rain sensor comprises an imaging array sensor and a control. The imaging array sensor is directed at the vehicle window from inside the vehicle and comprises a camera device capable of imaging precipitation at a surface of the window. The camera is operable to image the precipitation at least in response to ambient light present at the window. The control responds to an output of the imaging array sensor in order to indicate precipitation at the surface of the window. The control determines the presence of precipitation via spatial filtering of the image received by the camera device.

Abstract: Moisture detection permits moisture removal equipment, such as automotive windshield wipers and defogger systems, to be operated automatically. A system for detecting moisture on a surface includes a light emitter directed at the surface. The presence of moisture is based on the intensity of light from the emitter reflected by the surface and received by a light sensor. The light sensor accumulates charge in response to incident light over a variable integration period.

Abstract: A vehicular rain sensor system for detecting precipitation on an exterior surface of a window including a illumination sensor that is decoupled from the window. The illumination sensor is preferably an imaging array sensor which communicates a signal to a control which further determines whether rain is present on the window. The control preferably includes an edge detection function for detecting edges of precipitation droplets on the window and activating the windshield wipers of the vehicle when the number of edges detected exceeds a predetermined threshold value. A smoothing algorithm or filter is provided to account for surface irregularities on the window, thereby substantially precluding such irregularities from being erroneously detected as rain droplets by the edge detection function.

Abstract: A fine particle measuring system for semiconductor cleaning fluid includes a sample tank for holding a sample of the cleaning fluid and a pump that can circulate the sample of cleaning fluid. A return conduit is connected to a filter and a bubble discharge opening member to return a major portion of the sample of cleaning fluid to the sample tank. A minor portion of the cleaning fluid is directed respectively to a cooling unit, and then to a deaerator for eliminating any effects of bubbles on the measurement of fine particles in the cleaning fluid. A first conduit is connected to a measuring cell to return the sample cleaning fluid to the sample tank while a second conduit is connected to the deaerator to draw gas from the bubbles that have been separated from the deaerator.

Abstract: A fire detector which can be observed an operating state thereof from every direction and decrease a cost thereof as possible. The fire detector (10) comprises: the circuit board (32) in which the circuit for detecting a fire is formed; the LED (35) which is surface-mounted on the circuit board (32); and the indication lamp for indicating the fire detector being under detection by emitting the light emitted from the LED (35), wherein the indication lamp comprises the light guide member (20) for introducing the light emitted from the LED (35) to the indication lamp with a ring shape, the light guide member (20) comprises the light incident parts (21) and (21) and the ring member (22), notches (23) and (23) are formed in the vicinity of the light incident parts (21) and (21) of the ring member (22), and a plurality of small grooves (24), and (24) . . . are formed in the bottom surface (22d) of the ring member (22).

Abstract: A photoelectric smoke detector includes a smoke detecting section defining a smoke detecting space, a light emission section holder having a light-emission element disposed in the smoke detecting section, and a light receiving section holder having a light-receiving element disposed in the smoke detecting section. The light-receiving element receives light which has been emitted from the light-emission element and is scattered by smoke flowing in the smoke detecting space. A hybrid circuit board has an integrated circuit mounted thereon and is housed in the light receiving section holder. The integrated circuit including the light-receiving element and at least a received-light signal amplifying circuit. The hybrid circuit board is arranged so that the light-receiving surface of the light-receiving element is directed toward the smoke detecting space.

Abstract: In a method for detecting liquid drops adhering upon a front windshield with superior sensitivity but without obstructing drivers, a light beam emitted from a light emitting element 4 is guided into a light guiding body 7, and after undergoing total internal reflection within light guiding body 7, it is guided into a front windshield G. The light guided into the front windshield G is received by a light receiving element 5 after repeated total internal reflections within the front windshield G. In this instance, when raindrops adhere on the outside surface of the front windshield G and the adhering points are at the total internal reflection points of the light mentioned above, then the light beam guided into the front windshield G passes through and goes out from the windshield G without undergoing total internal reflection therein.

Abstract: An improved self-cleaning oven (10) is provided having an assembly (12) to control the cleaning cycle time of the oven (10) depending upon the degree of oven contamination and soil present therein. The assembly (12) includes a measuring chamber (16) as well as a passageway (18) communicating the interior (14) of the oven (10) and the chamber (16). A smoke detector (32) (preferably an infrared smoke detector) is associated with the chamber (16) and is coupled with a controller (20) so as to measure a parameter of smoke passing through the chamber during at least a portion of the cleaning cycle. This parameter is then used to determine the proper duration of the cleaning cycle. In preferred forms, measuring chamber (16a) is equipped with an ambient air inlet (52) and outlet (54) so as to draw an ambient air stream through the chamber (16a) between the smoke detector (32) and the oven gas stream.

Abstract: A medical installation, having an apparatus for acquiring the position of at least one object located in a room, also has a light transmitter for emitting a light fan and a camera for acquiring at least one object. The signals of the camera are supplied to an evaluation unit that generates 3D data on the basis of these signals corresponding to the at least one object that are utilized for avoiding collisions of the object.

Abstract: An autobalance control circuit for use in a moisture sensor which senses moisture on the surface of a transparent material. The moisture sensor includes detectors for receiving emitter signals which are influenced by moisture on the transparent material. The moisture sensor further includes a pre-demodulation circuit for attenuating unwanted signal components in the detector output signal while amplifying the useful signal components for further processing by a microprocessor. An autobalance circuit is provided for receiving the pre-demodulation circuit signal and providing an autobalance signal to the pre-demodulation circuit input. The autobalance signal at least partially cancels the detector output signal to prevent saturation of the pre-demodulation amplifier when undesirable detector output signal amplitudes are encountered.

Abstract: A control system for automatically detecting moisture on the windshield of a vehicle. The automatic moisture detecting system includes an optical system for imaging a portion of the windshield on to an image array sensor, such as a CMOS active pixel sensor. The voltages of each of the pixels which represents the illumination level is converted to a corresponding gray scale value by an analog digital converter. The gray scale values corresponding to the image are stored in memory. The spatial frequency composition of the gray scale values are analyzed to determine the amount of rain present. In order to provide a control signal to control the operation of the windshield wipers of the vehicle as a function of the amount of moisture present. The system is also adapted to detect the level of fog both on the interior of the windshield as well as the exterior of the windshield.

Abstract: A particle distribution size measuring apparatus incorporates a detector array having a plurality of light detecting elements located on a substrate. A first group of detector elements have a plurality of sectors with a common sector angle, while at least one other detector element is positioned furthest from an optical axis and has a smaller sector angle. Each of the detector elements can be formed on a single substrate and their position and alignment have increased the efficiency of manufacturing the arrays.

Abstract: A smoke detector includes a housing defining a dark chamber admitting test atmosphere. A light receiver is disposed within the chamber. A scatter emitter is positioned within the chamber such that light strikes the receiver when reflected off particles suspended in the test atmosphere. An obscuration emitter is positioned within the chamber such that light emitted is directed to the receiver unless obstructed by particles suspended in the test atmosphere. A smoke detect signal is generated responsive to a measurement made responsive to the scatter emitter and/or the obscuration emitter.

Abstract: A detector includes a sensor of an ambient condition. Outputs from the sensor are sampled at a predetermined rate when the outputs do not represent an alarm condition. The outputs are analyzed using pattern recognition techniques to determine if a predetermined profile, which precedes the presence of an alarm condition, is present. In the event that the profile is detected, the sample rate is increased along with associated sample value processing. The detector includes a programmable processor coupled to the sensor. The processor includes pattern recognition instructions for detecting the presence of the predetermined profile. The processor also includes instructions for altering the sampling rate in response to the detected presence of the profile. A second sensor can be incorporated to provide sample rate altering signals.

Abstract: An assembly (10) for sensing moisture (20) on the exterior surface (22) of a windshield (14) from a position spaced from the interior surface (18) of the windshield (14). The assembly (10) includes a focal plane detector (12) comprising a plurality of pixels (24) adapted for disposition in spaced relationship to the interior surface (18) of the sheet of glass (14), as on the backside of the rearview mirror. An imaging lens (16) is adapted for disposition between the focal plane detector (12) and the interior surface (18) of the sheet of glass (14) for directing light rays from moisture (20) on the exterior surface (22) of the sheet of glass (14) through the imaging lens (16) to produce a real image of the moisture (20) on said focal plane detector (12).

Abstract: The fire detector for sensing a fire, comprises; a smoke chamber, a light emitting element, and a light detecting element for detecting a scattered light caused by scattering a light emitted by the light emitting element with a smoke which enters in the smoke chamber, wherein a wall part of the smoke chamber is formed in a shape based on a circle having a predetermined size, and comprises a projecting portion which projects from at least a part of the circle to an outside of the circle, the light emitting element is disposed on the projecting portion of the smoke chamber, and the light detecting element is arranged out of the smoke chamber and an optical axis thereof is approximately perpendicular to a plane including the circle.

Abstract: A smoke detector (2) which operates on the scattered light principle comprises a detector chamber (4) through which a light beam (10) passes. A series of collimator discs (24, 26, 28) with apertures of progressively increasing size are associated with the light source (6) to prevent glints of light from entering the zone of the chamber at which detection occurs as a result of the presence of scattered light induced by the presence of smoke particles. A light absorber (12) at the end of the detector chamber remote from the light source uses a target surface in the form of an asymmetric cone (42) onto which the beam is directed. The design of the collimator discs and light absorber reduce the occurrence of stray light, leading to increased sensitivity.

Abstract: An optical apparatus for and method of improving collection efficiency and signal strength of optical instruments used in capillary electrophoresis, such as laser-induced fluorescence detectors are provided. The apparatus and method provides a concave reflector positioned at one side of the capillary flow cell as a first high numerical aperture (N.A.) collector, a lens collector positioned at an opposite side of the flow cell as a second high N.A. collector, and an optical fiber positioned at close proximity of the flow cell for delivery of an excitation light to cause a sample contained in the flow cell to emit emission lights. The reflector has a concave surface for reflecting the emission lights, and the collector has a proximal convex surface for collecting the emission lights, and a distal convex surface for collimating the emission lights. This arrangement achieves a larger solid collection angle from both sides of the flow cell and therefore an increased collection efficiency.

Abstract: Provided are a method and apparatus for measuring particles in a liquid sample. The method involves introducing a liquid sample into a heat exchanger, thereby cooling the sample to a predetermined temperature. A particle measurement is performed on the cooled sample by introducing the cooled sample into a particle detector. The method and apparatus in accordance with the invention effectively suppress bubbles present in a liquid chemical sample being measured, thereby allowing for accurate particle measurements. The invention has particular applicability in the semiconductor and pharmaceutical manufacturing industries.

Abstract: A system for detecting the presence of rain droplets on a windshield employs a source of radiant energy, such as an LED, and a photodetector installed on the instrument panel of a vehicle. The LED and the photodiode are arranged with respect to one another such that light from the LED cannot reflect directly off the windshield onto the photodiode. Only when the light from the LED is back scattered by an environmental condition, such as the raindrops on the exterior of the windshield, the condensation of moisture on the interior of the windshield, or the presence of smoke in the cabin, will the photodiode receive the light from the LED. Each of these environmental conditions has a predeterminable characteristic signature that permits the processing of data to detect same.

Abstract: An optical mass gauge sensor is disclosed comprising a vessel having an interior surface which reflects radiant energy at a wavelength at least partially absorbed by a fluid contained within the vessel, an illuminating device for introducing radiant energy at such wavelength into the vessel interior, and, a detector for measuring the energy per unit area of illumination within the vessel created by the radiant energy which is not absorbed by the fluid.

Abstract: A particle counter (10) passes a sample stream of a carrier gas or fluid containing particles (72) through an elongated, flattened nozzle (16) and into a view volume (18) formed by an intersection of the sample stream and a laser beam (13). Particles entrained in the sample stream scatter light rays while passing through the view volume. The scattered light is collected by an optical system (26) and focused on to a detector (40). The magnitude of signal coming from the detector is indicative of the particle size. To correct for variances in particle velocity and light beam intensity across the view volume, flow aperturing is used. Flow aperture modeling (Eqs. 1-7) provides a format for designing the nozzle such that the lateral velocity profile matches the laser beam lateral intensity profile, thereby providing uniform detection sensitivity to laser light scattered from monodisperse particles distributed laterally across the view volume.

Abstract: A bubble detector includes a conduit (1) through which a first fluid having a first refractive index is intended to flow, a light source (3) which directs a light beam (4; 41, 42) through a transparent conduit wall-part (12), through the conduit cavity and out through a second transparent conduit wall-part, and a detector means (5; 51, 52, 53) adapted to receive the light beam (4, 41) after the beam has passed through the conduit and the first fluid therein. The two opposing transparent wall-parts (12, 11) of the conduit (1) are trans-illuminated by the light beam and are essentially planar and parallel. The light source (3) is adapted to direct the beam (4) at an oblique angle (.alpha.) to the proximal transparent wall-part (12) of the conduit (1), so that the light source will be broken into different paths (41, 42) depending on whether the beam passes the first fluid or a second conduit-carried fluid having a different refractive index, such as a bubble.

Abstract: A driving unit generates a driving current corresponding to a light generation control signal CTL supplied from a light generation controlling unit. The driving current is supplied to an LED. Light emitted from the LED impinges on a light receiving circuit through a space of a monitoring area. The received light level of the light receiving circuit is converted into a received light level signal RLV in an A/D. The received light level signal RLV is supplied to a smoke detecting unit and the light generation controlling unit. The received light level signal RLV is monitored in a short period by the smoke detecting unit. When the received light level signal RLV is equal to or lower than an alarm level, an alarm signal ALM is output. The light generation controlling unit compares the received light level signal RLV with a reference level in a long period.

Abstract: An optical device on board an aircraft for detecting icing conditions including an optical beam emitter to create at least one illuminated external volume of measurement through which there circulates a flow of air charged with water particles; a collector optical system for the collection of at least a part of the light beam back-scattered by the water particles (the external volume of measurement being located on the optical axis of said collector optical system); a photodetector for detecting back-scattered optical beams; a signal processor for processing the signal delivered by the photodetector to compute the severity of the icing conditions; an information provider for providing information on the calculated severity of the icing conditions. Advantageously, the optical means for the differentiation of device includes a differentiation for differentiating between liquid water particles and solid water particles, based on analysis of the polarization.

Abstract: An allergen particle detecting apparatus has a sample area through which environmental air is directed. A light beam is directed through the air sample so that portions of the beam will be scattered if any particles are present in the path of the beam. A beam blocking device on the opposite side of the air sample is arranged to block all light except light scattered in a predetermined angular range corresponding to a predetermined allergen particle size range. Light transmitted through the blocking device is detected by a light detector and an alarm output signal is produced if the detected amount of light is above a predetermined level.

Abstract: An apparatus and method for controlling the operation of the windshield wipers of a vehicle in response to the deposition of water on the exterior of the windshield; the operation of the air conditioning system in response to the formation of water condensation on the interior of the windshield of the vehicle; and the operation of the ventilation system in response to the presence of smoke in the cabin of the vehicle.

Abstract: An autobalance control circuit for use in a moisture sensor which senses moisture on the surface of a transparent material. The moisture sensor includes detectors for receiving emitter signals which are influenced by moisture on the transparent material. The moisture sensor further includes a pre-demodulation circuit for attenuating unwanted signal components in the detector output signal while amplifying the useful signal components for further processing by a microcomputer. An autobalance circuit is provided for receiving the pre-demodulation circuit signal and providing an autobalance signal to the pre-demodulation circuit input. The autobalance signal at least partially cancels the detector output signal to prevent saturation of the pre-demodulation amplifier when undesirable detector output signal amplitudes are encountered.

Abstract: A dark-field particle monitor and a method for reducing errors due to stray light in the particle monitor provides a particle monitor having (i) an optical element focussed on the laser beam for detecting particles and (ii) a filter for preferentially selecting light incident on said filter in a preferential direction. In one embodiments the filter is implemented by a narrow band filter having maximum transmission for light having a wavelength of the laser beam.

Abstract: In a particle detector, a stream carrying particles to be measured is passed through a laser beam. A pair of optical collection systems are arranged perpendicular to the laser beam, opposing each other. The optical collection system reflects light signals indicative of particles sensed in the sensing region to a pair of detector arrays. Each detector array has a plurality of detectors to detect the particle signals, as well as other noise. One detector from each array monitors the same sensing region. The signals from the detectors are processed through a noise cancellation circuit. The noise cancellation circuit first amplifies each detector signal through a photo-amp. Then, the signals of the detectors in one detector array are paired up with corresponding signals of detectors, spaced at least two detectors away, in the other detector array. The paired-up signals pass through differential amplifiers, which essentially cancel the light fluctuation noise.

Abstract: Smoke alarms that incorporate dust repelling screens exhibit improved performance with fewer false alarms. Effective screens include conductive strands combined with non-conductive elements.

Abstract: System for, and method of, monitoring airborne particulate, including particulate of the PM.sub.2.5 class. The system for monitoring airborne particulate includes an optical sensor to measure size characteristics of sampled airborne particulate and a humidity sensor to measure relative humidity. An adjusted airborne concentration value is then produced in response to the measured size characteristics and to the humidity measurement. According to one embodiment the optical sensor is implemented as a multi-wavelength nephelometer, e.g., two-wavelength nephelometer. According to another embodiment the humidity sensor is placed relatively near the optical sensing region and makes a relative humidity measurement.

Abstract: In an inventive analyzing system (e.g. liquid chromatograph), an analyzing schedule includes data on whether or not to carry out a self-check for each sample, and data on what process to follow the self-check according to the check result, in addition to data on the analyzing order and analyzing condition of a series of analyses on a plurality of samples. In carrying out the analysis according to the schedule, a self-check is carried out after an analysis of a sample for which the self-check is scheduled. In the self-check, a data collecting unit 17 collects data on the degree of degradation of expendable parts and on the wavelength error of a spectrophotometric detector 14, etc., and a checking unit 18 detects abnormality by comparing the data to preset tolerable values. For example, in the case where the process specified to follow the detection of abnormality is "stop analysis on detecting abnormality", a control unit 15 stops each part of the system so that the rest of the analyses are deferred.

Abstract: An optoelectronic sensor device for detecting precipitation on an outer surface (41) of a transparent pane (4) of a motor vehicle includes a beam guide element (1) having front and rear opposed parallel surfaces (2, 7) and first and second lateral opposed faces (5, 6). The front surface (2) is coupled to an inner surface (42) of a transparent pane (4) of a motor vehicle. Each of the lateral faces (5, 6) has a reflection region (52, 62). The rear surface (7) has first and second cut-out portions (8, 81) extending therefrom toward the front surface (2). Each of the cut-out portions (8, 81) has a reflective region (11). A beam transmitter (13) is disposed adjacent the rear surface (7) to transmit an infrared beam to the reflective region (11) of the first cut-out portion (8). The reflective region (11) of the first cut-out portion (8) reflects a beam transmitted from the beam transmitter (13) to the reflection region (52) of the first lateral face (5) which reflects the beam to the transparent pane (4).

Abstract: A smoke sensor includes a light receiving unit for temporally alternately receiving scattered light of two different wavelengths .lambda..sub.1 and .lambda..sub.2 ; a calculating unit for performing a calculation required for smoke detection, on a scattered light output y of the wavelength .lambda..sub.1 and a scattered light output g of the wavelength .lambda..sub.2 from the light receiving unit; and a smoke detection processing unit for performing a smoke detection process on the basis of a calculation result output from the calculating unit. The calculating unit estimates an output value of one of the scattered light output y of the wavelength .lambda..sub.1 and the scattered light output g of the wavelength .lambda..sub.2 at a sample timing of the other output, and obtains a ratio of the estimated output value of the one scattered light at the sample timing of the other output to an output value of the other scattered light, as a two-wavelength ratio.

Abstract: An analyzer for analyzing chemical properties of a specimen using optical coupling and sensing, has a narrow band light source and an optical probe that is in contact with the specimen. Detectors are used for providing electrical outputs as a function of a parameter of the specimen, and an optical path couples light from the light source to the probe and also couples Raman scattered light from the specimen and Rayleigh scattered light from the specimen to separate detectors. An analyzer circuit is coupled to the detectors to provide outputs as a function of the electrical signals received, and one of the detectors is connected to a signal conditioning circuit for controlling the input of the light source and includes an asymmetric discrimination circuit configured to distinguish positive going fluctuations from negative going fluctuations in the output from the detector.

Abstract: A light beam is directed from a light source through an air sample so that portions of the beam will be scattered if any particles are present in the path of the beam. A beam blocking device on the opposite side of the air sample is arranged to block all light except light scattered in a predetermined angular range corresponding to a predetermined allergen particle size range. A light focusing lens in front of the light source is arranged to focus the unscattered part of the light beam onto the blocking device. Light transmitted through the blocking device is detected by a light detector and an alarm output signal is produced if the detected amount of light is above a predetermined level. The signal may be used to activate filtering or air conditioning devices.

Abstract: A fire detector capable of readily and accurately adjusting the sensitivity there of and of not erroneously outputting any fire signal is provided with a first-stage amplifying circuit having an output adjusting variable resistor and a fire discriminating section having a reference voltage adjusting variable resistor. As a result, it is possible to adjust the amplified output to a predetermined value by the switching level of the fire discriminating section to a predetermined value by the reference voltage adjusting variable resistor.

Abstract: An allergen particle detecting apparatus has a sample area through which environmental air is directed. A light beam is directed through the air sample so that portions of the beam will be scattered if any particles are present in the path of the beam. A beam blocking device on the opposite side of the air sample is arranged to block all light except light scattered in a predetermined angular range corresponding to a predetermined allergen particle size range. Light transmitted through the blocking device is detected by a light detector and an alarm output signal is produced if the detected amount of light is above a predetermined level.

Abstract: An allergen particle detecting apparatus has a sample area through which environmental air is directed. A light beam is directed through the air sample so that portions of the beam will be scattered if any particles are present in the path of the beam. A beam blocking device on the opposite side of the air sample is arranged to block all light except light scattered in a predetermined angular range corresponding to a predetermined allergen particle size range. Light transmitted through the blocking device is detected by a light detector and an alarm output signal is produced if the detected amount of light is above a predetermined level.