Patent ID: 9549151
Date: 2017-01-17
CPC Classifications: H04M,H04N

Claim:
1. A video intercom device, comprising: a front door slave unit; and an indoor master unit or a telephone master unit that performs wireless communication with the front door slave unit, wherein when the front door slave unit is registered in the indoor master unit, the indoor master unit transmits a switching requesting signal for switching to a second communication method with electric power consumption lower than that of a first communication method to the front door slave unit, and is switched from the first communication method by which a synchronous signal is periodically transmitted to the front door slave unit and a signal is periodically received from the front door slave unit, to the second communication method by which a signal is transmitted to the front door slave unit when necessary and a signal is periodically received from the front door slave unit when waiting, wherein when the switching requesting signal is received, the front door slave unit is switched from the first communication method by which a signal is transmitted to the indoor master unit when necessary and the synchronous signal is received from the indoor master unit by periodically turning on a main power source when waiting, to the second communication method by which a signal is transmitted to the indoor master unit when necessary and a signal is received from the indoor master unit by periodically turning on the main power source when waiting, wherein the indoor master unit includes a reception signal strength detector that detects strength of a signal received from the front door slave unit, and requests for switching from the second communication method to the first communication method to the front door slave unit when the reception signal strength detector detects that the strength is less than a predetermined threshold, and wherein the indoor master unit requests for switching from the first communication method to the second communication method to the front door slave unit when the reception signal strength detector detects that the strength is equal to or greater than a predetermined threshold.