Patent ID: 6256479
Filing Date: 2001-07-03
Classification: H04M

Abstract:
A door intercom for a dwelling, the intercom being of the type comprising a street panel designed to be used by a visitor and an indoor set designed to be used by an occupier of the dwelling, the street panel being provided with a call button and being connected to an electric latch fitted to a door of the dwelling, the street panel and the indoor set including means enabling a sound link to be established between them, and the indoor set including a button for causing the electric latch to open, the street panel including a radio transmitter and receiver, and means for recognizing a latch-opening code received by said receiver, wherein the street panel further includes a stand-alone electrical power supply having a voltage, means for activating the electric circuit of the latch, and means for controlling electricity consumption firstly to put the street panel in a standby state where its electricity consumption is practically zero while waiting for the call button to be pressed, and secondly to put the panel in an active state enabling a sound link to be established with the indoor set, and enabling the electric circuit of the latch to be activated when the latch-opening code is recognized and the means for activating the electric circuit of the latch have the necessary amount of electrical energy, said means for activating the electric circuit of the latch comprising a capacitor whose nominal capacitance is selected so that in a charged state, said capacitor is capable on being discharged into the electric circuit of the latch, of activating the latch to enable a door to be opened, wherein said capacitor is charged under a voltage that is greater than the voltage of the stand-alone electrical power supply, wherein the charging of said capacitor occurs once the latch-opening code has been recognized.