Abstract: In a security system, a transmitter housing and first and second transmitter actuation elements cooperate to define thumb and finger saddles on opposite sides of the housing. The peripheral edge of the housing and the first and second actuation elements have matched configurations aligned at the thumb and finger saddles for guiding a hand to properly operate the transmitter while blocking other objects from accidental operation. The housing extends beyond the actuation elements at the ends of the elements while the actuation elements extend beyond the housing at the center of the elements. The housing has a first texture, such as a rigid plastic, while the actuation elements have a softer feel provided, for example, by an elastomeric material.

Abstract: A smoke detector includes a dark chamber surrounded by a peripheral wall structure having a plurality of nested vanes. The second element of each vane is shorter than the first, and intersects the first element intermediate its ends at an acute angle. Adjacent vanes define a tortuous path that requires a minimum of three, and in most cases four, reflections for light to reach the inside of the chamber. Adjacent vanes define twisted channels leading from outside the chamber into the chamber for blocking light without substantially restricting the flow of air. The channels each include an outer section that extends in a direction toward the center of said chamber to define a channel entrance that admits airborne smoke with approximately equal resistance from opposite directions. The channels also define second and third sections that bend inwardly from the entrance toward said chamber, first in one direction and then sharply in another direction.

Abstract: A passive infrared detection system embodies a new three-element, single-channel, pyroelectric detector. For a given amount of motion by a target in a region under surveillance, the detector provides more complex signature information than conventional two-element detectors, thereby allowing the target to be more readily distinguished from spurious environmental or background sources. Owing to the geometry of the detector electrodes, the false-alarming effects produced by spurious stimuli common to all detector elements are reduced. The detector is particularly adapted for use in infrared detection systems of the type which use pulse-counting techniques to distinguish targets of interest from non-targets.

Abstract: An intruder detection system is provided with circuitry for reducing the risk of false alarms from spurious sources. Such circuitry comprises a pulse generator for producing current pulses of predetermined pulsewidth and amplitude each time the output of an intrusion detecting element exceeds or falls belows a preset threshold level, an integrating circuit for integrating the output of the pulse generator, threshold sensing means for activating an alarm when the integrator output exceeds a preset level, and a timing circuit for establishing a predetermined time interval and for discharging the integrating circuit in the event the integrator output fails to exceed such preset level within such predetermined time interval. According to a preferred embodiment, means are provided for resetting the time interval each time the detector output exceeds or falls below the selected threshold level.