Patent ID: 6998982

Claim:
An anti-thief security sensor assembly which comprises: a radiation beam projecting unit for projecting a radiation beam; and a radiation beam receiving unit for receiving the radiation beam projected by the radiation 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 radiation beam from the radiation beam projecting unit towards the radiation beam receiving unit; said anti-thief security sensor assembly further comprising a mode switching device for switching a mode between an adjustment mode for adjusting an optical axis and an operation mode for performing a security operation, said radiation beam receiving unit comprising a received beam amount detector for detecting an amount of the radiation beam received and a request signal outputting device for, when the amount of the received radiation beam detected in the adjustment mode is larger than a predetermined value, which is larger than an optimum value of the received radiation beam amount in the operation mode, transmitting a projecting power decrease request signal to the radiation beam projecting unit with a wireless transmitter; said radiation beam projecting unit comprising a projecting power step decreasing device for decreasing an amount of the radiation beam emitted by a predetermined amount each time the radiation beam projecting unit receives the projecting power decrease request signal with a receiver unit, and means for adjusting an optical axis between the radiation beam projecting unit and the radiation beam receiving unit.