Patent ID: 7986232

Claim:
A security system, comprising: an infrared (IR) sensor configured to be mounted proximate to a reflecting surface of a door to be monitored, the IR sensor having an IR transmitter and an IR receiver, the IR transmitter having an active period and an idle period, the IR transmitter transmitting an intermittent control signal including control data packets during the active period, the intermittent control signal reducing a power consumption of the IR sensor, the IR receiver having an active period for detecting reflected data packets; a processor providing the control data packets to be transmitted by the IR transmitter, the processor determining a level of packet IR reflectivity for each of the reflected data packets; a backlight configured to light an interface device that is configured to receive input from a user, the backlight and the interface device mounted proximate to the door; and a memory storing a level of door IR reflectivity associated with the reflecting surface of the door when the door is closed, the processor comparing the level of packet IR reflectivity to the level of door IR reflectivity to determine that the door is closed when the level of packet IR reflectivity determined by the processor and the level of door IR reflectivity stored in the memory are substantially the same, the processor activating the backlight when the IR sensor senses an object within a predetermined distance of the interface device.