Telephone line switch
AssigneeAlcatel
InventorsPeter A. Goode, David R. Stevenson
Life of this patent
Estimating the term…
Abstract
A solid state multi-function line switch for a telephone subset in which a controllable solid state switch in the subset's loop current circuit is controlled by a control circuit responsive to the telephone subset's signal functions such as hook-switch operation signals and loop current interrupt signals. An embodiment of a telephone subset circuit arrangement incorporating the line switch is disclosed.
Claims28
A telephone subset line switch comprising a first semiconductor switch means adapted to be connected in series with the loop circuit formed by the transmission circuit of a telephone subset and an exchange line, and wherein control means, responsive to two or more selected functions of the subset, generates signals to control the switching of the first semiconductor switch means to selectively switch the loop circuit open and closed appropriately for the selected functions, the first semiconductor switch means having a control element, and wherein one of the selected functions is hook-switch operation, the control means comprising second semiconductor switch means connected to the control element of the first semiconductor switch means, the second semiconductor switch means being controlled by function signal generating means in the telephone subset, the function signal generating means requiring operating power for operation and receiving the operating power when the subset is in the OFF-HOOK mode via the first semiconductor switch means, and wherein a capacitor bridges the function signal generating means to maintain the operating power for the function signal generating means during interruptions caused by function signalling when the first semiconductor switch means selectively switches the loop circuit open.
A telephone subset for connection to a telephone line having at least first and second conductors, comprising:
- control means, having first and second power supply terminals, having input terminals for receiving a hook-switch signal and telephone dialing information signals, and having output terminals, for providing telephone function signals at the output terminals in response to signals applied to the input terminals of the control means;
- first path means for defining a first current path between the first conductor of the telephone line and the first power supply terminal of the control means, the first current path having an initial portion which is connected to the first conductor of the telephone line and having a final portion which is connected to the first power supply terminal of the control means, the first path means including a semiconductor switch between the initial and final portions of the first current path, the semiconductor switch having a control element;
- means for providing a current bleed path between the initial and final portions of the first current path;
- second path means for defining a second current path between the second conductor of the telephone line and the second power supply terminal of the control means;
- a telephone subset transmission circuit connected between the final portion of the first current path and the second current path;
- means, connecting an output terminal of the control means and the control element of the semiconductor switch, for selectively opening and closing the semicondcutor switch in response to a telephone function signal;
- and
- a storage capacitor connected between the final portion of the first current path and the second current path.
Dependencies are inferred from the claim text.