| 摘要 |
A method of gap scanning wherein a first working member (such as a door) in conjunction with a second working member (such as a door) in conjunction with a second working member (such as another door, a door frame or a fixed surface) serves to define or include the gap to be scanned; the method comprising the steps of: locating on or near the other side of the gap an array of emitters of electromagnetic radiation; location on the other side of the gap an array of receivers of the electromagnetic radiation; each emitter in the array thereof being adapted to provide for the emission of a beam of radiation along an axis of transmission from the emitter across the gap to one or more of the receivers in the array thereof; each receiver in the array thereof being adapted to detect a beam of radiation from one or more of emitters in the array thereof along an axis of reception to the receiver across the gap from the emitters; providing an output channel for each receiver in the array thereof by way of which in the event detects a beam of radiation as aforesaid the receiver emits an output signal; linking a group of at least two receivers by way of their output channels by way of a common line to a switch such that on the switch receiving an output signal along the common line from the group it is unable to discriminate as to which of the receiver or receivers in the group generated or contributed to the output signal. |
