Patent ID: 7869718

Claim:
A motorized door opening system comprising; detection means to continuously monitor the obstruction path of said motorized door by periodic signaling, including a wireless photoelectric transmitter means wherein said wireless transmitter monitors its battery power source and selectively switches from a first signaling state to a second signaling state to indicate reduced battery condition in said transmitter; said detection means further including a photoelectric receiver means which continues to monitor obstructions and constructions regardless of whether said transmitter means is in said first or second state; wherein further said second state is comprised of a longer time period between said periodic signaling; wherein further said periodic signaling is comprised of transmission of timed groups of signaling pulses, said groups spaced a predetermined amount to signify a good battery condition in said transmitter, and thereafter changing said transmitted control signal at longer intervals between said pulse groups when said transmitter is in a low battery condition state.