To provide a video intercom system and intercom slave unit, wherein an unstable screen is prevented from being displayed, at a master unit side, without providing presence/absence of a camera for setting a slave unit connecting terminal.
In a slave unit Y without camera that does not include any camera, when a speech is started, an asynchronous signal generator 41 transmits a non-video signal. The non-video signal is different from a video signal that a slave unit X with camera transmits to a master unit Z, and has a higher frequency than that of a horizontal synchronizing signal and a vertical synchronizing signal (synchronizing signals) included in the video signal. Since the non-video signal is made into signal at a higher frequency than that of the synchronizing signals, even if noise is superimposed, the frequency is not reduced, thereby enabling identification as a non-video signal. In the master unit Z, by detecting the non-video signal, blue-back display is performed.
KUWAYAMA AIICHIRO
TOYAMA NAOYUKI
| JP2001285851A | 2001-10-12 | |||
| JPH10178635A | 1998-06-30 | |||
| JPH07177496A | 1995-07-14 |
Hiroki Naito
Daisuke Nagano