| 摘要 |
PROBLEM TO BE SOLVED: To provide an intercom system which can reduce its development charge and cost. SOLUTION: The intercom system is equipped with a handset unit, a door phone, and a switch. The handset unit is equipped with a receiver and a microphone. The intercom is equipped with a speaker and a microphone. The intercom is installed, for instance, at a front door. The switching functions as a switch for connecting the input/output of the handset unit, to either the input/output of a telephone line or the input/output of the intercom, and can be switched manually by user. According to this setup, the intercom system is capable of making its circuit simpler than that of a door phone system equipped with a holding circuit, without significantly spoiling the operability or reducing its development charge and cost. COPYRIGHT: (C)2007,JPO&INPIT
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