DE1961015B2 - Circuit preventing shared telephone being engaged by two calls - applies blocking potential to all switching circuits not involved so that only one can be active at any time - Google Patents

Abstract

The circuit prevents a shared telephone being engaged by two or more calls simultaneously by applying a blocking potential to all switching circuits not involved, ie only one switching circuit an be active at any time. This is achieved by inter-connecting all switching circuits and blocking gates so that they are interdependent. The advantage lies in requiring the same circuitry per terminal (coupled to the shared device being protected) irrespective of the number of terminals coupled to the device. The common transistor (T3) is controlled via the diode (D11) and resistor (R8). The common transistor (T3) controls the transistors (T12, T22... Tn2) via the resistors (R17, R27... Rn7).

Description

30th

The invention relates to a circuit arrangement for preventing multiple assignments Devices common to connection points with connection means assigned to the connection points, in particular The invention relates to telephone systems in which when connecting a calling or to be called subscriber to a connection set, such double assignments must be avoided.

There are already locking devices known that prevent several connection points at the same time a common facility can be connected. The disadvantage of these arrangements is that the effort changes for each connection point, depending on the way it is how many connection points are assigned to a common device. This also requires that in the various arrangements in which such locking devices have to be provided again and again, these are equipped differently in their design for each connection point, since the required Effort per connection point always depends on the number of connection points that are shared Facility are assigned.

From the interpretation documents DT-AS 11 19 921, DT-AS & o 51 028 and DE-AS 10 05 567 are also circuit arrangements for electrical test multiples for Telecommunications, in particular telephone systems, are known in which simultaneously checking relays fault current obtain. In the first two documents mentioned, the ratio of fault current to starting current is given by jointly applying voltage division and current splitting using a second test wire set. In the test circuit according to DE-AS 11 51 028, in which also through a current branch in the test wire receives a relay which is testing faulty current at the same time and therefore does not comes to respond, in the event that this relay picks up briefly, by discharging a Capacitor causes a counter-excitation that causes it to drop again.

The basic disadvantage of these test arrangements is the consideration of the response and fault current behavior of the individual test relays, d. H. these relays must be specially adjusted and made safe against fault current will. Since, however, depending on the number of simultaneously checking relays as well as cfer respective Length of the connection line as well as differences in the voltage supply the fault current conditions can change, such arrangements are always fraught with uncertainty, the mostly additional adjustment measures and adaptation circuits make necessary.

The object on which the invention is based is therefore to provide an arrangement for preventing double occupancy of several connection points shared facilities with the connection points to create associated connection means, in which once the effort per connection point is always the is the same, regardless of the number of existing connection points, so that even with the most diverse Systems per connection point the same unit can always be used, and on the other hand in one such an arrangement does not prevent the activation of connection means from any fault current conditions, which can arise due to the different number of possible connection points, to make dependent.

The invention achieves this in that the each controlled by the switching path of an electronic switch Ei'ischaltestromkreise all connection means both with a common to all connection points Locking element as well as each with a locking gate individually assigned to the relevant switch-on circuit are connected in such a way that when switching a switch-on circuit through the common blocking element blocking potential to the respective control inputs of all other switch-on circuits is switched on.

Since it is necessary in telephone systems, a connection set to which a calling party is first to be used is switched on, then interconnect with the subscriber to be called, so that in this case for these differently controlled participants a double assignment of the same connection set in Question comes, the invention further proposes that for the connection of a subscriber in telephone systems to a connection set of the switch-on circuit for the switch-on means of each participant with each is equipped with two control inputs, the control input that can be activated by a subscriber to be called cannot be influenced by the blocking potential of the common blocking element.

An exemplary embodiment of the invention is shown in the drawing.

The connection of the subscriber circuit of a telephone subscriber to a common connection set, not shown, is carried out by the connection relays D 1 to Dn, which are individually assigned to the subscribers.

The control inputs for the switch-on circuits of these relays D 1 to Dn are labeled ANi, AEi, ... ANn,

AEn denotes, whereby the inputs AEi to AEn are activated by calling subscribers and the inputs AN 1 to ANn are activated when the subscribers to be called are activated.

The switch-on circuits of the individual connection relays D 1 to Dn run via the emitter-collector paths of transistors 711 to ThI, the base of which is connected to the inputs AEi to AEn or via resistors R 12 to An 2, R 11 to Rn 1 and R 13 to Rn 3. ANi to ANn is switched on.

Between the resistors R 11 and R 13 ... Rn 1, Rn3 the emitter-collector path is of transistors ΤΊ2 to Tn 2, the opening or closure over the emitter-collector path of the common transistor 73 is carried out In addition, the base of the transistor 712 via the Diode D 12 linked to the collector of transistor 711 In the same way, the collector of transistor 721 acts on the base of transistor 722 and the collector of transistor Tn 1 acts on the base of transistor Tn 2 via diode Dn 2. If a participant who is assigned to the input AEi hangs up his receiver, positive potential appears at this point. The transistor 711 is turned on via the resistors Λ 11 and R 13 and the switch-on relay D 1 switches the relevant microphone on to the connection set.

The common transistor 73 is turned on via the diode D J1 and the resistor R 8 and controls the transistors 712, 722 ... 7n2 via the resistors Λ17, R27 ... Rn7. The transistor 712 cannot turn on because its input is blocked by the transistor 711 via the diode D 12.

The transistors 722 and Tn 2 become conductive and block the inputs AE2 and AEn, so that the speech stations assigned to these and the inputs not shown in between cannot switch on the corresponding through-switch relays by unhooking their receiver.

However, this relay can be switched on when arriving from a selection chain (not shown), which is set in a known manner after a connection set has been assigned by a calling subscriber and switches on positive potential to the input AN 1 ... ANn assigned to the calling subscriber. Since the inputs ANi to ANn assigned to the subscribers to be called are connected directly to the base of the transistors 711 to Tn 1 via the resistors R 12 to Rn 2, the blocking potential of the transistor 73 cannot have any effect during this switching process.

1 sheet of drawings

Claims (2)

Patent claims: 10 15th 1, circuit arrangement to prevent double occupancy of devices common to several connection points with connection means assigned to the connection points, in particular for connecting a connection set to the connection circuit of a calling and to be called subscriber in telephone systems, characterized in that the switching path of an electronic switch (TU ... Tn 1) controlled Einschaltestromkreise all connecting means (Di, Dn) with both an all connecting points (AEI ... / 4 £ ty common locking member (T3) and with one the respective Einschaltestromkreis individually assigned to inhibit gate (T 12, R 15, R 16, D 12 ... Tn 2, Rn 5, Rn 6 _V Dn 2) are connected in such a way that when a switch-on circuit is switched through the common blocking element (T3) blocking potential is connected to the respective control inputs of all other switch-on circuits will. 2. Circuit arrangement according to claim 1, characterized in that for the connection of a subscriber in telephone systems to a connection set, the switch-on circuit of each subscriber is equipped with two control inputs (AEi, ANi ... AEn, ANn) , with the one to be called Subscriber activatable control input (AEi, ... AEn) cannot be influenced by the blocking potential of the common blocking element (T3). 25th