Anti-thief security sensor assembly using the opening of the projector cover for beam adjustment

An anti-thief security sensor assembly which includes:

• a beam projecting unit for projecting an infrared beam, said beam projecting unit including a base having a sensor circuit mounted thereon and a projector cover detachably mounted on the base for enclosing and projecting the sensor circuit;
• 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, and further including a level output circuit;
• said beam projecting unit also including an opening detecting switch for detecting a physical opening of the projector cover and a transmission request generating circuit operable in response to the detection of the physical opening of the projector cover by the opening detecting switch for outputting a received beam level transmission request signal to the beam receiving unit;
• said level output circuit being operable in response to receipt of the received beam level transmission request signal to transmit to the beam projecting unit a level display signal indicative of the amount of the infrared beam received by the beam receiving unit.