NL8900167A - SWITCHING FOR TELEPHONE TERMINALS. - Google Patents

Description

* ί -1 “VO 1389

Title: Circuit for telephone terminals

The invention relates to a circuit for telephone terminals, which are connected via a mains termination unit (NT) to the service-integrating digital message network (ISDN), according to the preamble of the main claim.

5 Standard terminals are required for terminals connected to the service-integrating remote signaling network (ISDN). Between the interface on the panel side, e.g. U-interface, and the interface on the side of the participant, S-interface, also referred to as S-bus, a mains termination unit (NT) is switched (fig. 1).

The mains disconnection unit (NT) supplies the interface on the participant's side, and some of the terminals, especially the telephone terminals, with electrical energy. Further connected terminals, such as e.g. teletext, facsimile, 15 data transfer, screen text devices, etc. are provided with their own voltage supply. In the event of a power failure, it must be ensured that a telephone terminal is supplied with voltage from the exchange via the mains termination unit (NT), in order to maintain the basic function of the telephone 20. In addition, a maximum power consumption is prescribed by the system administrator for such a telephone terminal in emergency operation.

The object of the invention was to guarantee a voltage supply for the emergency operation of the telephone terminal and not to exceed a certain power consumption (e.g. typically 25 mW in passive (idle) state). This problem has been solved by the invention, as described in the characterizing part of the first claim. Further advantageous measures are the subject of the sub-claims.

The invention will be further described hereinafter with reference to the drawing, in which: Fig. 1 shows the block circuit diagram of a remote reporting network, and Fig. 2 shows an extract from the switching device 8900 167-2 of a telephone. terminal device.

The telephone terminal, which must operate in emergency mode, is equipped with additional switches (NS1, NS2). Of the possible eight connected devices of an S-bus 5 or a mains terminating unit (NT), this is always only one device. During normal operation, the telephones draw their power from the mains disconnection unit (NT), with the positive potential at the supply line (1) and the negative potential at the supply line (2). When the telephones are installed, the switches (NS1, NS2) of the telephone terminal intended for emergency operation are closed. The supply potential is applied via the switches (NS1, NS2) to the supply lines (3,4), which lead to a DC converter. The DC voltage converter serves to obtain the supply voltages for the hardware of the telephone terminal. The positive potential via the diode (G1) on the supply line (3) and the negative potential via the diode (G2) on the supply line (4) are in active and in passive (resting) state.

In emergency operation, all terminals are switched off, with the exception of the telephone terminal intended for emergency operation, as a criterion for emergency operation, for which, in passive (idle) state, the power value of e.g.

25 25 mW must not be exceeded, the potential reverse must be applied to the supply lines (1,2). The negative potential of the supply line (1) then lies via the diode (G3) on the supply line (4). The DC converter does not receive a positive potential. The positive potential is only switched when the passive state is switched to the active state. This is done in an outgoing connection by switching the telephone hook switch (GU), wherein the thyristor (T) control electrode acquires a positive potential and ignites the thyristor (T). A current flows to the supply line (3) through the first transistor (T1), the thyristor (T) and the switch (NS1).

With an incoming connection, the active- 8900167:

V

• V

-3- ring routine of the mains termination unit (NT) replace the quiescent potential on the S-bus with a pulse series and apply it to the pulse input (7), the first pulse driving the second transistor (T2) and thus the potential of the supply line (2) to the thyristor (T) control electrode. As described above, the thyristor (T) ignites.

The same effect can also be achieved by an auxiliary pulse source, e.g. a stored charge in the telephone terminal, which e.g. arrives at point (6) via a button operation.

When the telephone terminal of the active is driven in the passive state, a signal from the central processor of the telephone terminal reaches the control electrode of the third transistor (T3) via the control input (5). The third transistor (T3j is turned on and turns off the first transistor (T1). By falling below the holding current of the thyristor (T), it is switched off, so that in emergency operation the potential of the supply line (3) is separated. The remaining power consumption in passive state in emergency operation is then determined exclusively by the high-resistance voltage divider (R1, R2).

8900167,

Claims (4)

1. Circuit for telephone terminals, which are connected via a mains termination unit to the service-integrated digital message network (ISDN) and are thereby supplied with power during normal operation, and which always have a DC converter for providing internal supply voltages, in the event of the power supply to the mains termination unit failing, a telephone terminal unit associated with this mains termination unit obtains energy from the exchange, the central processing unit of the telephone terminal unit having a potential reversal on the supply and signal lines as the criterion of emergency operation, characterized in that the power consumption during emergency operation is determined by a high-ohmic voltage divider (R1, R2) on the supply lines 15 (1,2); that with closed emergency power switches (NS1, NS2) a series arrangement of a first transistor (T1) and a thyristor (T) is connected between the one supply line (2) and a supply line (3) to the DC converter; 20 that a contact of the telephone hook switch (GU) and a second transistor (T2) for ignition control of the thyristor (T) and for interrupting the current between the supply line (2) and the supply line ( 3) by blocking the thyristor (T) the control electrode of the first transistor (T1) is connected via a third transistor (T3) to a control signal input (5) of the central processing unit. , Circuit according to claim 1, characterized in that the telephone hook switch contact (GU) and the second transistor (T2) are connected between the control electrode of the thyristor (T) and the one supply lead (2). Circuit according to claim 1, characterized in that the second transistor (T2) is controlled via pulse input (7) by pulse delivery from the bus receiver unit. 8900167 / * ’-5- Circuit according to claim 1, characterized in that the second transistor (T2) is driven by a pulse from a stored charge or from an obtained voltage pulse (6). 890 0 167 /