| 摘要 |
<p>Auxiliary sensors 51, 52 are disposed on exterior and interior side surfaces 31, 32 of a transom 3. The sensors 51, 52 have detection areas A1, A2, B1, B2 which extend through the doorway 2 and which cross each other in a space vertically above a track 10. While detection signals are produced by both auxiliary sensors 51, 52, the door is kept open. If detection signals are produced from only one of the auxiliary sensors 51 (52) uninterruptedly for a predetermined time, the door closing action is allowed to start. <IMAGE></p> |
