초록 ▼

The invention is an improvement over the system disclosed in U.S. Pat. No. 3,805,061 for detecting intrusion of a selected area by an object and for operating or terminating operation of an associated apparatus when such intrusion occurs. It consists of improved transmitter and receiver units. The t

The invention is an improvement over the system disclosed in U.S. Pat. No. 3,805,061 for detecting intrusion of a selected area by an object and for operating or terminating operation of an associated apparatus when such intrusion occurs. It consists of improved transmitter and receiver units. The transmitter comprises a plurality of radiant energy sources that are strobed sequentially and repetitively by a clocked counter. The receiver has a plurality of radiant energy detectors, means for enabling the detectors sequentially and in synchronism with the strobing of the radiant energy sources, dual control relay means for operating or terminating operation of an associated apparatus, and cross coupled control circuits for causing the relay means to change states if a radiant energy detector fails to detect a radiant energy beam while it is enabled. The receiver\s control circuits include pulse detection means for determining if the radiant energy detectors produce pulses in response to incident radiant energy beams, and means for accomplishing at least one of the following: (a) deactivating the relay means if a relay driver has a fault, (b) deactivating the relay means if a pair of relay contacts are stuck closed, (c) terminating flow of current to some or all of the solid state components such as counters, switches, etc. of the receiver when a fault occurs in a relay control circuit, and (d) providing visual indications of the state of the relays.

대표청구항 ▼

In an object detecting system for determining when an object intrudes into a given area, said system comprising a transmitter for providing a light barrier that extends along said area and a receiver for detecting when the barrier is encountered by an intruding object, an improved transmitter compri

In an object detecting system for determining when an object intrudes into a given area, said system comprising a transmitter for providing a light barrier that extends along said area and a receiver for detecting when the barrier is encountered by an intruding object, an improved transmitter comprising: a plurality of light sources each adapted when operated to produce a beam of light that extends along said area with each beam transversing a different selected portion of said area; and strobing means for operating said light sources repetitively in a predetermined sequence; said strobing means comprising pulse generating means adapted to produce a train of signal pulses, means coupled to said pulse generating means for operating said light sources in said predetermined sequence in response to signal pulses from said pulse generating means, and control means for varying the output of said pulse generating means so that in each full sequence of operation one of said light sources is operated N times in response to signal pulses at a frequency f1 and the remainder of said light sources are operated Y times in response to signal pulses at a frequency f2, where N and Y are integers, N is greater than Y and F2 is less than f1.