DE224290C - - Google Patents

Description

IMPERIAL

PATENT OFFICE.

PATENT LETTERING

- M 224290 CLASS 21 a. GROUP

is shown.

Patented in the German Empire on March 23, 1909.

For telephone systems where any intercom can be connected using Fixed switch, pushbuttons, levers or the like to the common, over several call stations routed lines are carried out, various devices are known which prevent the occupancy the line should make recognizable, with an interposition in an existing one Connection and eavesdropping is avoided.

ίο These are very common with the individual devices Blocking characters are provided for each of the lines carried out, which either appear, when a call station has switched itself to the line, or during the entire occupation period are visible from all points of the line. Locking devices can also be influenced in a corresponding manner, which make it impossible to connect to a busy line. These arrangements however, they are involved and expensive because each station has so many locking devices must, as lines are carried out. Another arrangement was that everyone Special test buttons were assigned to the line, with the help of which the busy status of the Line was established. The present invention now provides a substantial simplification and cheapening of the devices achieved by the fact that each station for arbitrary many common lines carried through has only one blocking character, with the one used to establish the connection serving push buttons, lever or the like. Simultaneously as test buttons to serve.

The idea of the invention is illustrated in the drawing, for example. As I and II, two of several call stations are shown, which are connected to one of two common, e.g. B. leading to an office double lines La ₁ , Lb ₁ , La ₂ , Lb ₂ can be connected. The individual sections of each common line La ₁ , Lb ₁ and La ₂ , Lb ₂ are connected in series in such a way that when a station I or II is connected to one of the two common lines, the following section is separated from the previous section. The connection of the devices to one or the other common line La ₁ , Lb ₁ or La ₂ Lb ₂ is done by push buttons a _x , a ₂ on each intercom. Switching springs, by means of which the speech sets are connected to the line La, Lb in a known manner, are indicated by δ, c are special contact springs, the purpose of which is evident when the mode of operation is explained. The springs intended for checking the line for occupancy are indicated by d and e , and those by a

on the push button α located projection f are moved. The test leads required are marked with g . A buzzer or similar device can be provided as the busy signal, which receives its current from a battery i , one pole of which is connected to earth.

The mode of operation would be as follows: The call station II has, for example,

10. connected by pressing its button aJ ¹ with the line La ₁ , Lb ₁ in a known manner. Here, one pole of a battery i is connected to the line ^ ₁ through the contact spring c . Call station I now also tries to connect to line La ₁ , Lb ₁ . For this purpose, the key U ₁ ^{1 is} depressed, the projection f closes the contact of the spring β with d. This creates a circuit from the ungrounded pole of the battery i via the closed contact c on the button al ^{1 of} the speech station II, which was switched on earlier, line g _x to speech station I and springs d, e to the buzzing h to earth. This sounds and thus indicates to station I that line La ₁ , Lb _{1 is} busy. If, however, the button a ₂ ^! printed, the buzzing h does not sound, of course, because in this case the contact c on the button a ₂ ^{u is} open. It should be emphasized that when the push button « ₁ ^{/ is} pressed down to the point where the projection f compresses the springs d, e , the springs b are not switched over and the existing connection is not disturbed. If the line La ₁ , Lb _{1 were} free, then the buzzing h would receive no current, and the proper switchover could then be carried out by further pressing the button a /. In this case, however, the precaution has been taken that after the projection f has been switched on, the spring e does not touch any further, so that no incorrect switching can be made for the busy signal.

The essence of the invention lies in the fact that when the push button α is pressed in the first part of its movement , it closes the circuit for the buzzing h , which is prepared when the line is busy and, when the line is free, also switches and connects the intercom causes the line in a known manner. The type of occupancy message is not essential for the concept of the invention and any acoustic or optical signal can be used for this purpose. The device can also be such that, instead of a special signaling device, the telephone serves as such, in that the potential applied to line g causes a cracking sound in the receiver of the testing station.

The representation of two lines carried out shows that for each call station only one blocking character is required for any number of lines.

Claims (1)

Patent claim: Circuit for telephone stations, in which the connection of a telephone station to one of several common lines takes place by means of a switch, which also serves to check the lines for busy, and through which eavesdropping is avoided or other disruption of an existing connection is indicated in that the for connection of a station (I, II) to one of common lines (La _1, Lb _1, La _2, Lb ₂₎ provided switch (a _1; a ₂₎ of its movement in the first part that is on each station for all cables (La ₁ , Lb ₁ , La ₂ , Lb ₂ ) a common optical or acoustic signal (h) containing circuit (i, c, g, d, e, h, earth, i) only with an existing connection . a call station (z. B. II) to this common line (z. B. La ₁ , Lb ₁ ) in per se known. Completed way, and that when the end position of the switch is reached, the own test signal (h) is disconnected and the test circuit (i, c, g, d, e, h, earth, i) of this common line is connected for others while they are busy Intercom stations are being prepared. ... For this purpose ι sheet of drawings.