Patent ID: 6819240
Filing Date: 2004-11-16
Classification: G08B

Abstract:
An anti-thief security sensor assembly which comprises:a beam projecting unit for projecting an infrared beam; and a beam receiving unit for receiving the infrared beam projected by the beam projecting unit and operable to detect a human body in the event that the human body traverses the optical path of travel of the infrared beam from the beam projecting unit towards the beam receiving unit; said beam projecting unit comprising a mounting base provided with a sensor circuit and a projector cover detachably mounted on the mounting base for enclosing and protecting the sensor circuit, an opening detecting switch for detecting a physical opening of the projector cover, and a projected beam suppressing circuit operable in response to detection by the opening detecting switch to reduce a quantity of the infrared beam emitted from the beam projecting unit to thereby reproduce reduction of the amount of the infrared beam caused by the projector cover.