| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide an intercom system which reduces the number of components and has a simple and inexpensive configuration.SOLUTION: An intercom master apparatus 2 comprises: a master apparatus acoustic/electric conversion transducer 20 in which either of a call transmission function of receiving voice of a person in a room as input and generating a master apparatus voice signal and a call reception function of outputting voice of a visitor on the basis of a slave apparatus voice signal transmitted from an intercom slave apparatus 1 is active; a master apparatus voice switch 21 which compares a sound pressure level of the master apparatus voice signal generated by the call transmission function of the master apparatus acoustic/electric conversion transducer with a sound pressure level of the slave apparatus voice signal transmitted from the intercom slave apparatus 1, and detects a call transmission state or call reception state on the basis of difference between the levels; and a master apparatus changeover unit 22 which is controlled by a master apparatus voice switch 21 and is changed over in order to activate either of the call transmission function and call reception function of the master apparatus acoustic/electric conversion transducer 20.</p> |
