PURPOSE: To facilitate the open-close operation of a key cylinder at a dark place by detecting the fixing position of a lock and the approach of the hand of a man having a key corresponding to the lock by using a pair of a light- emitting element and a photo-detector.
CONSTITUTION: Light emitted from a light-emitting element 12 is divided into two directions by a beam splitter 14. One light is introduced to the front of a door 1, reflected by the hand 10 of a man having a key 9 when the hand 10 is located within a specified distance L (5-20cm) from the door 1, and received by a photo-detector 18. The periphery of a key cylinder 3 is lit for a fixed time and only once by a lighting means 5 at that time. Accordingly, the position of the key cylinder 3 can be confirmed easily even at a dark place, thus facilitating the open-close operation of the key cylinder 3.
ICHIKAWA MASAMITSU
NAKAMURA SHUICHI
