Abstract: A transducer has a body having an outer region which is generally straight tapered in cross section and an inner region which is generally an arc of a circle in cross section. The inner and outer regions meet along a closed plane tangent curve. The outer region includes a decoupling region which extends around the outer region along at least one closed plane curve.

Abstract: A smoke detector utilizing a pulsing light source, a photo-voltaic cell, and an amplifier, in which the total current output on each light pulse is a function of the smoke concentration. In a preferred embodiment of the invention, the amplifier output current resulting from each light pulse is converted into an output signal which has a duration which is a function of smoke concentration.

Abstract: A self-calibrating obscuration smoke detector is provided along with a method for the operation thereof. A light source and a photodetector are mounted in spaced relation to one another with the output of the photodetector being a function of the amount of light sensed by the detector from the light source. The photodetector analog output is converted into digital signals by an A/D converter and digital signals are then delivered to a digital processor adapted to periodically calibrate the detector and to perform sampling operations between calibrations. Other sensing devices may be connected to the system with automatic self-calibrating capabilities with respect thereto including a temperature responsive element the output of which may be used to compensate for changes in ambient temperature.

Abstract: A smoke detector which responds to the presence of smoke or other aerosol particles within a smoke chamber. The detector includes a photocell and a pair of light sources, one light source aimed directly at the cell and the other light source shielded from direct illumination of the cell, but aimed at an inspection zone to which the cell is visible. The first light source shines in a generally steady state directly against the cell to bias the cell to a predetermined level. Cyclically, the first light source will be turned off and the second light source will be turned on to illuminate any smoke that may be present in the inspection zone. If smoke is present in excess of that which corresponds to the pre-bias of the cell, the output will rise due to reflection of light from the second light source against the smoke and onto the cell. The output will remain the same if the amount of smoke is equal to the pre-bias and the output will drop if the smoke is less than the pre-bias.

Abstract: A self-calibrating obscuration smoke detector is provided along with a method for the operation thereof. A light source and a photodetector are mounted in spaced relation to one another with the output of the photodetector being a function of the amount of light sensed by the detector from the light source. The photodetector analog output is converted into digital signals by an A/D converter and digital signals are then delivered to a digital processor adapted to periodically calibrate the detector and to perform sampling operations between calibrations. Other sensing devices may be connected to the system with automatic self-calibrating capabilities with respect thereto.By using a pair of photodetecting cells directly visible to separate light sources or indirectly visible to a single source, a thermally stable system is provided where one cell provides a reference output for the other cell.

Abstract: A reflected light optical smoke detector includes a thermistor in series with a light emitting diode connected in parallel to a photo-resistive cell. Alarm circuitry is connected to the photocell having a voltage output which is a function of the presence or absence of smoke in an examination zone illuminated by the light source and visible to the cell. The circuit is temperature-compensated automatically by the thermistor since the thermistor will increase the current to the LED in the event of an increase of ambient temperature. The increase in the LED light output will compensate for the loss of photocell sensitivity in the event of an increase in temperature.

Abstract: A smoke detector is provided in which two light sources are employed in conjunction with a single photo responsive device and control circuit elements adapted for sequential operation of the light sources. One light source is directed at the photo responsive device to pre-bias the device while the other is directed at a smoke chamber to which the device is exposed. If smoke is present in the chamber, the light from the second source will strike the smoke particles and be reflected against the photo responsive device changing the output thereof. The light sources in one embodiment are timed to operate in a series of pulses and measurements are made on the declining output of the photo responsive device, such that the presence of smoke in the chamber will produce a longer decay time than will occur in the absence of smoke. A timer connected to the circuit measures the decay time and is adapted to generate a signal under the appropriate conditions.

Abstract: A smoke detector is provided in which two light sources are employed in conjunction with a single photo responsive device and control circuit elements adapted for sequential operation of the light sources. One light source is directed at the photo responsive device to pre-bias the device while the other is directed at a smoke chamber to which the device is exposed. If smoke is present in the chamber, the light from the second source will strike the smoke particles and be reflected against the photo responsive device changing the output thereof. The light sources in one embodiment are timed to operate in a series of pulses and measurements are made on the declining output of the photo responsive device, such that the presence of smoke in the chamber will produce a longer decay time than will occur in the absence of smoke. A timer connected to the circuit measures the decay time and is adapted to generate a signal under the appropriate conditions.

Abstract: A photo-electric smoke detector operating on the reflected light principle which has a rate detector for detecting the rate of increase of smoke concentration. When the rate exceeds a predetermined value, the rate detector causes the intensity of the smoke detector light source to increase, thereby increasing the sensitivity of the detector. In one embodiment of the invention, after the intensity of the light has been increased by the rate detector, it is maintained at the higher intensity for a predetermined time, even if the rate of increase of smoke concentration falls below the predetermined value.

Abstract: A smoke detector system utilizing remote detectors of the photo-electric type connected to a central control panel. In one embodiment means is provided for monitoring both the signal lead and power lead, and in another embodiment, means is also provided for monitoring the condition of the detector light source. A normally illuminated compensating cell is provided in series with the smoke detection cell, with the bottom of the compensating cell being maintained a predetermined voltage above ground to provide a monitor voltage at the junction of the cells. The output signal lead is connected to the junction of the compensating cell and the smoke cell, and feeds a high impedence input amplifier, the output of which goes to the control panel. Means is provided at the panel for responding to the presence of an alarm signal on the signal lead or the absence of the monitor voltage which might be caused by a break in the signal lead, or the power lead.

Abstract: A smoke detector of the photo-electric type having a photo-responsive device viewing a volume illuminated by a light beam, in which a test member is provided for being temporarily positioned in the light beam so that one side of said member is exposed to the light and the other side is in the view of the photo-responsive device.The test member has a translucent area at the forward edge which is small in relation to the cross-sectional area of the light beam. The translucent area illuminated by the beam simulates a pre-determined percentage of smoke in the beam with a high degree of accuracy since the transmission characteristics of the translucent area can be consistently maintained within production tolerances, and the exact position of the translucent area in the light beam for the smoke simulation is not critical.

Abstract: A smoke detector and housing assembly therefore in which the housing components are designed to allow rapid assembly of the detector with a minimum amount of labor. In a preferred embodiment of the invention a retainer for a photo-cell and light source is provided with a medial portion retaining the photo-cell and portions extending forwardly from the ends of the medial portion for projecting a light beam through the field of view of the photo-cell. The retainer is molded in two similar halves and fastened together after assembly of the photo-cell, light source, and other components therein.A base plate is provided with suitable apertures for receiving the forwardly projecting portions of the retainer so that after assembly they protrude from the forward face thereof. A cylindrical member and cover are mounted on the forward face of the base plate between the forwardly projecting portions of the retainer, forming a dark chamber across which the light beam projects, and into which the photo-cell views.

Abstract: A smoke detector of the type utilizing a pulsing light source and photo-responsive means producing an output signal in response to the receipt of a pulse of light from said source reflected from smoke particles and means for amplifying said output signal to produce an alarm signal, which has exceptionally low current drain so as to be adapted for being powered by a battery, and exceptional immunity to false alarms even when operated at a high sensitivity. On each pulse, the amplifier is energized and allowed to achieve a stabilized condition, prior to energizing the light source, and after the light source is energized, the amplified output signal is not allowed to create an alarm signal until the circuit has again stabilized from transients caused by the energizing of the light, thereby preventing false alarms from circuit transients resulting from internal and external causes.

Abstract: A particle detector which during periods of high ambient light is responsive to a particle concentration of a predetermined value to provide an output signal and during periods of low ambient light, is responsive to a substantially lesser particle concentration to sound an alarm.

Abstract: A smoke detector having manual means or automatic timing means for changing the sensitivity of response.

Abstract: A smoke detector operating on the reflected light principle, in which the detector housing components are designed to provide recesses in which the light and photo-cell assemblies are retained, with a slot disposed between the light and photo-cell recesses through which ambient air is drawn into a chamber illuminated by the light source and viewed by the photo-cell. When smoke is present in the incoming ambient air, it diffuses throughout the chamber to provide a large volume of illuminated smoke for viewing by the photo-cell thereby giving a fast response to the presence of a small concentration of smoke in the ambient air.The provision of the smoke inlet slot between the light and photo-cell recesses also prevents the accumulation of dust and lint therebetween which could cause a false alarm.

Abstract: A smoke detector operating on the reflected light principle, utilizing a pulsing light source and means requiring several consecutive pulses of light reflected from smoke to actuate an alarm. During normal standby operation, the light pulses at a predetermined slow rate, when smoke is present, the first pulse of light reflected from the smoke causes the time interval to the next pulse to increase, so that if smoke continues to be present, the number of reflected pulses required to actuate the alarm are received in a shorter time. The time to alarm is thereby shortened without increasing the current drain of the device and without shortening the life of the pulsing light source.

Abstract: A smoke detector operating on the reflected light principle, utilizing a pulsing light source and means requiring several consecutive pulses of light reflected from smoke to actuate an alarm. During normal standby operation, the light pulses at a predetermined slow rate. When smoke is present, the first pulse of light reflected from the smoke causes the pulse rate to increase for a predetermined number of pulses or for a predetermined short time, so that the number of reflected pulses required to actuate the alarm are received in a shorter time. The time to alarm is thereby shortened without increasing the current drain of the device and without shortening the life of the pulsing light source.

Abstract: A smoke detector of the type utilizing a photo-responsive device to detect light reflected from smoke particles illuminated by a light source and actuate an alarm, in which a second photo-responsive device is utilized to control the intensity of the light source so that it is continuously exposed to a light intensity from the light source such that its thermal co-efficient of resistance is maintained at a value substantially equal to that of the first photo-resistive device when said first photo-resistive device is exposed to the amount of light that causes an alarm. In one embodiment of the invention identical photo-cells are connected into circuitry which includes two level detectors with the same transfer curve and voltage gain, and means causing the two photo-responsive devices to have the desired resistance at the alarm point. Changes in ambient temperature and line voltage are therefore prevented from affecting the alarm point.

Abstract: A detector of the type utilizing photo-electric detection of reflected light which is almost completely immune to false alarms from changing ambient light and random electrical noise, with a sensitivity that is independent of ambient light, with a power consumption low enough to permit battery operation for a period of over 12 months. The light source is a light emitting diode which is pulsed at a low repetition rate, such as one pulse every two seconds, by an extremely short pulse, such as 20 microseconds. Voltage pulses generated when the reflected pulsed light is received by the photo-generative cell is amplified and applied to a level detector, the output of which is applied to the "set" terminal of a flip-flop circuit. The amplifier is on continuously, however the level detector is pulsed to the on condition simultaneously with the on pulse to the light emitting diode, and for the same period of time.