PURPOSE: To prevent such an accident as unlocking an electric lock of a doorphone being not in the course of speech, etc., and also, to curtail the operating member related to unlocking and locking of the electric lock by unlocking the electric lock corresponding to the doorphone being in the course of speech in plural doorphones.
CONSTITUTION: When a call button 14c of a doorphone 14 is operated, and a channel selection button 8a of an indoor terminal 6 is operated, a speech cable L1 is connected to a speech path network 9, and it is possible to speak with a visitor. When the doorphone 14 and the indoor terminal 6 are speaking, a comparator 2a of a speech detecting circuit 2 operates, and a delivery of the comparator 2a becomes an H level. When an electric lock driving circuit 3 operates, an electric lock 17 of a door 16 is unlocked through an electric lock cable L3. In this regard, in this case, the other entry of an AND circuit 5b becomes an H level together with the other entry of an AND circuit 5a, but since a comparator 2b is not operating, the AND circuit 5b remains non-active. in such a way, such an accident as unlocking the electric lock being not in the course of speech, etc., can be prevented.
ICHIKAWA TOSHIMITSU
ISHII KINJI
| JPH0220777A | 1990-01-24 | |||
| JPH0260384B2 | 1990-12-17 |