Patent ID: 7476860

Claim:
An active infrared detection apparatus comprising: a light-projecting unit comprising: a light-projector for emitting an infrared light beam; a light-projector drive portion for pulse-driving the light-projector based on a pulse-driving signal with a predetermined period; and a first receiver for dynamically setting the predetermined period of the pulse-driving signal; and a light-receiving unit comprising: a second receiver for receiving the infrared light beam emitted by the light-projector and outputting a corresponding pulse signal; a light interruption judgment portion for judging that the infrared light beam is interrupted when at least a predetermined number of pulses are successively not output by the second receiver; a light-receiving state detection portion for detecting a light-receiving state of the infrared light beam, based on the output of the second receiver; and a wireless transmitter for wirelessly transmitting the light-receiving state information detected by the light-receiving state detection portion to the first receiver; wherein the light-projecting unit is disposed at a first end of an alert territory and the light-receiving unit is disposed at a second end of the alert territory, such that the light-projecting unit and the light-receiving unit face each other, and wherein the first receiver dynamically sets the predetermined period of the pulse-driving signal based on the light-receiving state information from the wireless transmitter, and the predetermined period of the pulse-driving signal in the light-projector drive portion is changed based on the light-receiving state information.