| 摘要 |
PROBLEM TO BE SOLVED: To provide an intercom system with a simple structure capable of outputting a large-volume alarm sound from a door intercom slave unit without causing distortion in an alarm sound signal, and without allowing an intercom master unit to output a large-volume alarm sound. SOLUTION: An intercom master unit 2 is provided with a display driving signal transmitting means 24 for allowing a display driving signal to include a sound signal gain switching signal and transmitting the signal. A door intercom slave unit 1 is provided with a sound signal gain switching means 15 for detecting the sound signal gain switching signal transmitted from the intercom master unit 2 to amplify the gain of a speaker amplifier A2. COPYRIGHT: (C)2006,JPO&NCIPI
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