| 摘要 |
A light beam transmitter and receiver are located in or near a door opener enclosure, and fiber optics connect the transmitter and receiver to the sides of the door opening. Lens arrangements are attached to the ends of the optic cables and are mounted near the bottom of the door frame. Thus, the transmitter and receiver do not need to be located near the door which eliminates the need for wiring from the enclosure to the door area and protects the transmitter arid detector from physical abuse at the doorway. |
