DE1028159B - Operating mode switching device for additional key device that can be attached to teleprinters - Google Patents

Description

kl. 21a ¹ 11/06

INTERNAT. KL. H 041

PATENT OFFICE

REGISTRATION DAY:

NOTICE
THE REGISTRATION
AND ISSUE OF THE
EDITORIAL:

S 41774 VIII a / 21a ¹ DECEMBER 1, 1954

APRIL 17, 195S

The invention relates to an operating mode switchover device for attachable to teleprinters with a combined transmitting and receiving device Key accessory.

To simplify an accessory key device with the help To be able to use switching means alternately for encryption and decryption is according to the invention Procure the operating mode switchover device as follows and put it in the circuit of a conventional Teletypewriter switched on:

It is automatically switched on when a transmit button is pressed or the tape dispenser is switched on Transmit-receive switch provided that it is connected to the key device Send contact in the input circuit of the additional key device and the switching status in the output circuit connected to the outgoing line, for example, from the current flow in the consumer circuit the additional key device makes dependent, while with from the sending side unaffected transmit-receive switch control the incoming over the line pulse trains the input circuit of the key device and the Place the receiving magnet in the circuit controlled by the additional key device. To this Way, the key accessory is automatically of use within the sending part a teleprinter for encryption purposes switchable to use for decryption purposes within the receiving part of this machine.

In a preferred embodiment of the invention, when a transmit button is pressed or Switching on the punched tape transmitter, automatically switched on transmitter switch when the key device is connected a changeover relay so that the send contact in the input circuit of the key device and whose consumer circuit determines the switching state in the receiving circuit, while unaffected Changeover relay sends the incoming pulse trains to the input circuit of the additional key device control and the receiving magnet in the controlled by the additional key device Lay the circuit.

Instead, the device can also be designed so that only the one controlled by the key transmitter Send / Receive switch, the switchover in the encoder circuit and in that of the key device controlled, e.g. B. directly controls the circuit connected to the outgoing line, however the transmit switch used for punched tape dispenser operation, the switchover in the transmitter circuit and in the initiated by the key device controlled circuit via a changeover relay.

Operating mode switchover device

for at teleprinters
attachable additional key device

Applicant:
Siemens Sd Halske Aktiengesellschaft,

Berlin and Munich,
Munich 2, Wittelsbacherplatz 2

Dipl.-Ing. Fritz Butzke, Baierbrunn near Munich,

Dipl.-Ing. Herbert Wüsteney, Munich,

Philippe Bekaert, St. Nicolas-lez-Liege,

and Rodolphe Kussener, Brussels (Belgium),

have been named as inventors

According to a further embodiment of the invention is an electrical mode switch for Switchover of the entire machine from unencrypted to encrypted operation and vice versa the position for unencrypted operation is spring-tied, and in particular the switching state of the drive motor The locking element controlled by the teletypewriter holds in the switch position »encrypted« hold this switch in this position until the encrypted transmission has ended. To this Way can be switched from unencrypted to encrypted operation in a very short time, and vice versa, without specially trained staff or a second telex connection with others Machines is required, but also without the risk of mistakes being made when switching over and thereby unwanted or unusable characters are transmitted.

For the last-mentioned purpose, the is preferably in a parallel circuit to the drive motor Teletypewriter the excitation winding of a magnet controlling the locking member with one at position "Encrypted" closed switching contact of the switching device and one that can be operated manually Interrupter button for resetting to clear operation switched in series.

According to another development of the invention, there is a multi-pole switching device in the teleprinter provided, with the help of which transfer devices in print or strip perforation can be selected can be controlled by pulse sequences in front of or behind the key device.

709 960/116

Further details of the invention emerge from what has been described and shown in the drawing Embodiment. It shows

Fig. 1 is a circuit diagram of a very generally usable teletypewriter,

2 shows a circuit diagram of an additional automatic switchover device from encrypted operation Clear operation,

3 shows a perspective view of the essential components of the arrangement according to FIG. 2,

Fig. 4 is a simplified circuit diagram of a variant of the Transmit / receive switching device according to FIG. 1.

The teleprinter according to FIG. 1 enables encrypted and unencrypted operation all common modes of operation with punched tape. In addition, it can also be used as a local encryption and decryption device using punched tape that contain encrypted messages, either produced or converted to plain text.

In detail, the following possible uses of the entire facility result under the assumption the use of a teleprinter with appropriate facilities:

1. Sending and receiving plain text, using either a keyboard or a schematic Fig. 1 dashed punched tape transmitter, as well as printing or perforation in an additional attached receiving hole.

2. Sending and receiving of encrypted text, namely sending using a clear text transmitter Keyboard and possibility of direct generation of clear sheet printing in the receiver or sending a clear punched tape in an additional punched tape transmitter, with the read-along text can be clearly written in the sending machine, although associated with encrypted characters Pulse trains are sent over the line; these can be decrypted directly in the recipient and appear as printed plain text or clear perforated strips.

3. In local operation:

a) Production of clear perforated strips with the possibility of reading along on the sheet on your own machine for the purpose of using these strips in a punched tape transmitter;

b) Production of encrypted punched tape with the help of a built-on receiving perforator at from Transmit circuit controlled encryption device and separate transmit and receive circuits;

c) the conversion of encrypted punched tape into plain text and clear punched tape is corresponding or one of the last two types of recording is possible.

This extremely versatile use of the teleprinting system is made possible by switchings made for each teleprinting machine by means of three switches; A switch KG is provided for switching between »Clear« or »Encrypted« and can be operated alone when operating on lines. The second switch EU controls the switching of the receiver for the production of clear punched tape or encrypted punched tape with the help of a receiving punch to be attached and is to be operated with local encryption or decryption or punched tape production. The third switch LL either connects the teletypewriter to the line or establishes local circuits.

In addition to the usual chart recorder, there are three switches and the Encryption and decryption equipment described in detail later, as well as some purely electrical ones and parts mentioned in the circuit description or evident from the circuit diagram, such as Capacitors and resistors, the following components required:

A transmission switch SU in the teleprinter

is automatically closed for a short time when a button is pressed, a transmission switch LSU in the punched tape transmitter is automatically operated together with the motor starter switch. In this way, when a character begins to be sent, the machine is automatically switched from receiving to sending, thus enabling intermittent two-way traffic with encryption without manual switching.

A release magnet MI for controlling the scanning device for the keyhole strip and a release magnet MV: for the shaft of a correction distributor (not shown) are provided in the key device. This correction distributor controls the switch KV1 in the supply circuit of the rectifier bridge, which has already been explained in detail above, as well as a further switch KV2 for switching off the tripping magnets mentioned.

In Fig. 1, the switch KG is shown with its five movable switch contacts in the position G , which determines the encrypted operation. The entire circuit is chosen so that when this switch is turned to position K (clear) the machine works like a normal chart recorder, whose sending contact and receiving magnet are in series in the subscriber loop fed by the office.

If the system is to be used for the transmission of clear telex characters, the switch Lh must be set to the Ltg position and the ELT switch to the KL position. Line current then flows over from the office

Connection point 7, LL (Ltg), KG2 (K), 10, DK, SK, EU2 (KL), EM, EUA (KL), KG3 (K), 8, back to the line.

If a perforated strip transmitter is to be used in clear operation, then one must be connected to the connection points 9, 10 and 11 in the manner shown in the circuit diagram in FIG the socket contact DK lying at points 9 and 10 is opened. In a known manner, the transmission contact LSK of the perforated strip transmitter is connected in series with a counter write magnet GM to the connection points 9 and 10, while the aforementioned switch LSU comes to lie between the connection points 10 and 11. If print text is to be received and a receiving perforated strip to be punched at the same time, a switch-on button (not shown) of the receiving perforator must be pressed.

If the connection is to be made with the aid of encrypted characters, the connection with the remote station is first established in the "Clear" position of the switch KG , and it is agreed which keyhole strip is to be used. From now on, every character that the sending station sends out using the keyboard or clear perforated tape in the perforated tape transmitter is encrypted on the line. It is assumed that it is desirable to be able to read along in plain text at the sending point and that plain text should be written at the receiving point and, if necessary, a clear perforated strip should be received.

An encrypted transmission comes about as follows: After pressing any key on the keyboard, the transmitter shaft starts running and first actuates the switch SU, which pulls a fast-working relay U :

+, KGS, U, SU, KG2, -.

Contacts u 1 and w2 controlled by relay U switch the line and local circuits to transmit. The local circuit is closed over

+, B ', ul, Wl, KG3, JEI / 4, EM, EUl, SK, 9, DK, 10, KG2, -.

The pulses sent out by the transmitter contact SK of the keyboard transmitter are also received by the receiving magnet EM of the own machine, and the relay B transmits the plain text characters to the local encryption circuit, which is shown at the bottom in FIG. 1.

During the start-up step, contact b of relay B is switched to the drawing side and actuates the tripping magnets MI and MV, as the following circuits are closed:

-, b, KV2, MI, W2, + and MV, WZ, +, where W2 \ xnaWZ

Represent resistances. Two capacitors C1 and C 2 ensure a rapid current increase in the tripping magnet. Before the end of the start-up step, switch KV2 is triggered by the approaching distributor shaft and these two circuits are switched off. The relatively high excitation current for these magnets does not need to be switched off by relay contact b ; this is therefore spared.

The encryption is done in the following way:
The negative pole of a voltage source, a contact b controlled by relay B in the encoder circuit, a resistor Rb, another resistor Ra, a contact A controllable by the keyhole strip scanner, a contact distributor, of which only one contact KV 1 is shown, and the positive pole of the voltage source are located in row. The contact distributor which is put into operation during the start-up step ensures that the contact KV1 is only closed briefly in each combination step after the contacts yi and b have been set. This results in a perfect center scanning of these contact settings. A connection point s 1 for the input circuit of a rectifier bridge is located between the two resistors mentioned. The second connection point s2 of this bridge is in the middle of a high-resistance voltage divider Sp, which is also connected to the DC voltage source via the contact distributor. The rectifier bridge contains four rectifiers GIl to G14 and in the diagonal consumer circuit a winding of a relay IR and a resistor R in series. A holding winding of this relay is connected in series with a resistor Rh also via the contact distributor to voltage.

The relay IR transmits the result of the encryption to the line via its switching contact ir in that this switching contact is in the following circuit:

Lead, 7, LL, EUl, Dr, EUZ, KGl, u2, ir, 8, lead.

At the end of the transmission shaft revolution, the switch SU opens again and the relay U drops out. At the same time, the contact distributor comes to a standstill in its starting position. The teletypewriter is now switched back to receiving.

If the perforated tape transmitter is to be used for sending instead of the keyboard, the switching contact LSU replaces the switch SU. The relay U remains picked up until the motor switch is switched off manually or, if necessary, automatically at the end of the punched tape, thereby opening the LSU.

ίο In order to ensure in encrypted operation that the unencrypted transmission of the secret message is avoided when the end of the keyhole strip is reached, the punched tape scanner for the keyhole strip contains a sixth sensor lever contact »FK6«. At the end of the strip, this short-circuits the send contacts SK of the button-controlled plain text transmitter and LSK of the clear perforated strip transmitter. When sending the keyboard, you immediately notice the deficiency, as no read-along text is written. In the punched tape encoder, the counterwriting magnet GM drops out and stops the encoder. Likewise, it is not possible to work with the flap of the keyhole strip scanner open and the switch KG in position G if this, as is often the case, is provided with such a flap that must be closed after the keyhole strip has been inserted to ensure proper operation of the scanning device . When the flap is open, the transmitting contact SK and possibly the perforated tape transmitting contact LSK are short-circuited by a switch Kl K. If only the sixth feeler lever contact FK 6 was used, but not the flap contact KK , the short-circuit of the transmitter would only take place after the sixth feeler lever contact had sent the first character. The consequence of this would be that on the opposite station, with the keyhole strip inserted according to the invention on the starting mark, the latter would be indexed further by one division. If the sending station starts sending after inserting the keyhole strip on the starting mark before this false start is noticed on the receiving machine, the keyhole strips on the sending and receiving machine are out of phase and the received text is unusable.

In particular when teletypewriters with encrypted operation are connected to telephone exchange systems, it is necessary that the teleprinter is switched back to clear mode after the encrypted teleprinting has ended. The encrypted operation usually begins, as mentioned earlier, after the exchange of agreements on the type of keyhole strip to be used. This exchange is generally preceded not only by the call but also by the name giver being released. The switchover from clear operation to encrypted operation accordingly usually takes place when the drive motor 12 of the machine is already running. In a circuit that is parallel to this motor, a switching contact 13, which is closed at position G of the operating mode switch KG , a manually operated breaker key 14 and the excitation winding of a blocking magnet 15 are connected in series. It follows that, if the drive motor is running and the button 14 is not pressed, when the switch KG is turned into position G with the help of the hand lever 16, a projection 17 of the locking magnet armature in a recess in the connecting rod 18 between the hand lever 16 and the actual Switch KG occurs. A spring 19, which is also attached to the connecting

Rod 18 attacks, tries to pull the switch KG back into position K , but it is prevented by the collapsed approach 17 from doing so. If, on the other hand, the encrypted telex is ended and the drive motor 12 is de-energized, for example by pressing a key or a mechanical remote switch, the blocking magnet 15 is also de-energized and thus the armature of this magnet is lifted by a return spring 20 and thus also the projection 17 of the armature the associated section of the rod 18 removed. The spring 19 can now reset the switch KG to the position K intended for clear operation. If you want to switch from encrypted operation to clear operation without switching off the engine beforehand, all you need to do is press button 14. Since the locking magnet 15 is also de-energized in this way, the switch K is again returned to the position K.

When receiving encrypted telex characters, the single stream overflows

7, LL, EUl, Dr, EUZ, KGl, ul, B, 8.

The pulses are received by relay B and transmitted via relay contact b into the decryption circuit, which is identical to the encryption circuit mentioned above. The result of the decryption is transmitted from the anchor ir of the relay IR to the receiver part of the telex:

+, ir, «2, Wl ₁ KGZ, EUi, EM, EU2, SK, 9, DK, 10, KG 2, -.

The EM receiving magnet receives plain text characters that are printed on the sheet of the telex by the printer. If the received message is to be punched into clear perforated strips at the same time, a switch-on button for the receiving perforator must be pressed.

During the reception process, the correction distributor contact KVl is again used to control the relay IR in the decryption circuit. The center scanning of the received characters ensures that the relay IR transmits completely corrected characters to the receiving magnet. Its scope is therefore very large, regardless of the relay circuit for reception and decryption. This means that even with encrypted reception, there is the same security as with reception of plain text.

As already mentioned, a machine switched according to FIG. 1 can also be used to produce clear perforated strips with control text in sheet printing. These punched strips can either be used for the subsequent transmission of clear or encrypted characters. When using the machine in this way, switch LL to the "Lok" position and switch KG to the "if" position. By merging one of the two long-distance line cores with one pole of the local power source - here the line to be connected at 8 with the positive pole of the local battery, which is not grounded - the transmit / receive switchover device is simplified so that, despite the possible local operation, only two switchover contacts ul and μ 2 are needed. Local current flows through the sender contacts and the receiver magnet:

+, KGZ (K), EUt (KL), EM, EU2 (KL), SK, 9, 10, KG2 (K), LL (locomotive), -.

The contact SK is controlled by operating the keyboard, the receiving magnet EM receives these impulses, and the printer prints the assigned characters. The activated receiving hole punch punches the five combinations clearly in a punched tape.

An encrypted punched tape can be produced by pressing the keyboard with the help of a keyhole strip, dispensing with a clear read-along text and suppressing the printout of the encrypted text, by setting switch LL to "Lok" , switch KG to "G" and the Switch EU to »VL«, the triggering of the pressure in the position »VL«. the switch EU can, for. B. be suppressed by a linkage coupled to this switch. A circuit is then created for the transmitter:

-, KG2 (G), 10, DK, SK, EUl (VL), Dr, EUZ (VL), KGZ (G), Wl, ul, B, +.

At the same time, the circuit for relay U is closed via:

-, KG2 (G), SU, U, KG5, +.

The receiving part is in a second local circuit:

-, LL (Lok), EU2 (VL), EM, EUA (VL), KGl (G), u2, ir, +.

This method has the advantage that the encrypted punched tape is created immediately when writing and can then be passed on; thereby it can be sent directly from this point through a normal telex or brought to a different position with ¹ to any means of transport.

In the same way, a clear perforated strip can be converted into an encrypted one. This automatic implementation happens at the highest speed and therefore takes proportionally takes little time. It is also possible to use the same clear perforated strip again run through the machine along with another keyhole strip to get the same Message with a different key, for example one to another recipient.

Also in local operation, an encrypted punched tape can be decrypted in a similar circuit as explained above and, for example, printed as plain text. For this purpose, the encrypted punched tape is inserted into the punched tape transmitter; then the device is initially allowed to run in the "K" position of the switch KG up to the agreed distance combinations which indicate the beginning of the encrypted message. An agreed keyhole strip is then inserted into the scanning device for this strip at the agreed location. After switching the KG switch to »G«, the |

encryption of the encrypted message and the

Creation of a clear print text by the recipient.

With the help of a receiving ^{punch, the decrypted 1} message can also be received as a clear punch tape. If this strip be passed on to other places, so it must be ensured that the beginning of the punched tape overall ¹ if necessary cut off and must be supplemented by new sender, recipient and key names.

If the teletypewriter is designed in the manner described above, there is also ⁵

Finally, use for encrypted operation has the advantage that in the position Ä 'of the switch KG all organs of the key addition are switched off. In this way, in the event of a malfunction, it is easy to determine whether the cause of the malfunction is to be found in the actual teletypewriter or in the key extension.

In the first part of the description, a device was already specified by means of which it is avoided that the incoming combination "Whoever there" triggers the name giver and causes malfunctions when dialing and receiving encrypted characters. In particular when using a single rectifier bridge, this device can be replaced by the fact that the name giver is enabled in the "Clear" mode and blocked in the "Encrypted" mode. Depending on the position of the switch KG, this can be done with the aid of a magnet or a mechanically controlled linkage. In practical operation, "Clear" is called in the operating mode, and exit and closing signals are also transmitted when the switch is in the "Clear" position, so that the machine can also call. If the switch is not in the "Clear" position, e.g. B. when the connection collapses, you can make the switch to "Clear" and the associated release of the name giver dependent on the described magnet, which drops out as soon as the high-voltage relay in the commonly used remote control device drops out and de-energizes the motor and the magnet.

The preparation of the "Encrypted" operating mode sometimes takes so long that the mechanical remote switch normally used, for example set to a 30-second switch-off time, switches off during this time. This is particularly uncomfortable when you switch to "encrypted". It is therefore advisable to prevent the switching off of the mechanical remote switch by suitable means, for example by a contact placed parallel to the remote switch or by a mechanical control of this switch in the "encrypted" position of the switch KG.

If necessary, the scanner for the keyhole strip can be used as a punched tape transmitter during clear operation by setting the switch KG to "encrypted" and sending alternating characters (5 x current) continuously. Such a use of the machine will of course only be undertaken if the plain text part contains only a keyboard and no punched tape scanning device, or if the latter device is not operational. The operation of the device can be simplified by using a third position of the switch KG for "Punched Tape Consignment Clear". In this position, the switch mentioned makes the appropriate electrical switchover either by itself or via a relay and also actuates a blocking magnet which holds the letter change key pressed once or a special control key for the desired punched tape shipment. At the end of the strip or when the flap is lifted, the actuated contacts FK 6 or KlK cause the locking magnet to drop again. When using a special key, when this key is pressed, in addition to shifting the selector rails into the position for alternate characters, the start-stop lock can be canceled and the so-called continuous operation can be triggered.

When training the mode switch for three or more positions and using the automatic Return device for the operating mode switch from the position for encrypted Operation in clear operation is possible by any means, for example by adjusting the fixed articulation point the spring 19 in other modes of operation to ensure that this spring is not effective is.

4 it is explained in the following how, for example, to avoid the risk of bouncing of the relay contacts u 1 and κ 2 in the working position during keyboard operation, the relay U can remain unused. In this circuit, the switching options with the aid of the reception switch EU and the local operation line switch LL are omitted for the sake of simplicity. This results in the same connections as in the first embodiment for the position G of the operating mode switch KG and punched tape operation. On the other hand, in the same position of the KG switch and keyboard operation for the plain text, the following circuit is closed:

+, B, ul, SUl, Wl, KG3, EM, SK, DK. KG 2, -.

The encryption result is transmitted to the line via the following circuit through control from the IR relay:

1 (-). Dr, KGl, SU2, u2, ir, 2 (+).

The changeover switches SU1 and SU2 take the place of the switch SU used in the arrangement according to FIG. 1.

The structural design of the teletypewriter can within the scope of the invention in take place in many ways. So the restraint device for the operating mode switch can be on the position for clear operation, which takes effect when an encrypted broadcast ends be influenced by a spring by any other control force. The controls for the switches, e.g. B. the mode switch, can conveniently close to the Keyboard, e.g. B. next to this, be housed.

Claims (12)

Patent claims 1. Operating mode-Umschalteeinrichtuug for add-on key to teleprinters, characterized in that a send / receive switch is automatically switched on when a send button is pressed or the punched tape encoder is switched on so that it switches the send contact (SK or LSK) in with the keypad connected sets the input circuit of the additional key device and makes the switching state in the output circuit connected, for example, with the outgoing line dependent on the current flow in the consumer circuit of the additional key device, while in the case of the transmit / receive switch that is not influenced by the transmission side, the pulse trains arriving via the line control the input circuit of the key device and Place the receiving magnet in the circuit controlled by the additional key device. 2. mode switching device according to claim 1, characterized in that a when 709 960/116 I 028 Pressing a transmission button or switching on the punched tape transmitter automatically switched on transmission switch (SU or LSU) with the key device connected controls a switchover relay (U) so that the transmission contact is in the input circuit of the key device and its consumer circuit determines the switching state in the receiving circuit, while with uninfluenced Changeover relay (U) control the incoming pulse trains via the line to the input circuit of the additional key device and place the receiving magnet in the circuit controlled by the additional key device. 3. Operating mode switching device according to claim 1, characterized in that only the transmitter / reception switch (SU 1, SUZ) controlled by the key transmitter, the switchings in the transmitter circuit and in the controlled by the key device, for. B. directly controls the circuit connected to the outgoing line, on the other hand the transmitter switch (LSU) used in punched tape dispenser operation causes the switching in the transmitter circuit and in the circuit controlled by the key device via a switching relay (U, ul, u2) . 4. Operating modes - switching device according to one of claims 1 to 3, characterized in that an electrical operating mode switch (KG) for switching the entire machine from unencrypted to encrypted operation and vice versa is spring-tied to the position for unencrypted operation and that a particular from the switching state of the drive motor of the teletypewriter controlled locking element in the switch position »encrypted« holds this switch in this position until the encrypted transmission is finished. 5. mode switching device according to claim 4, characterized in that in a parallel circuit to the drive motor of the teletype machine, the excitation winding of a locking member controlling the magnet with a "Encrypted" closed switching contact of the switching device (KG) and a manually operable breaker button for resetting Clear operation is in series. 6. Operating mode switchover device according to one of claims 1 to 5, characterized in that a multi-pole switchover device (EU) is provided in the teleprinter, with the aid of which conversion devices in print or strip perforation can be controlled optionally by pulse sequences in front of or behind the key device. 7. Operating mode switching device according to one of claims 1 to 6, characterized in that a switch (LL) is provided, with the aid of which the remote line can be switched off and instead a local circuit can be closed. for the purpose of producing encrypted, decrypted or corresponding messages supplied by the transmitting part, in particular punched tapes, in local operation. 8. Operating mode switching device liach one of claims 1 to 7, characterized in that a replica of the receiving magnet, preferably designed as a choke coil (Dr) , is inserted into a circuit when the circuit in question is used to control the key device and the receiving magnet of the teletypewriter is in the circuit controlled by the key device or when the receiving magnet is in the circuit controlling the key device and the circuit containing the replica of the receiving magnet "is controllable by the key device. 9. Teletypewriter with mechanical remote switch and with operating mode switchover device according to one of claims 1 to 8, characterized in that the mechanical remote switch mechanically locked or electrically in the on position for encrypted operation is bridged. 10. The Telegraph Alphabet NY. Teletype machine using 2 with a plain text keyboard according to one of claims 1 to 9, characterized in that the machine can be used as a punched tape transmitter for plain text, that a clear punched tape is inserted in place of the keyhole strip, that the other settings are made as in encrypted transmission and, for example, by continuously pressing the letter change ^{key or a special key that controls the pulse combination "5 X current":} this pulse combination is added by the keyboard, which is actually plain text. 11. Teletypewriter according to claim 1O ₁ , characterized in that the switch "Clear / Encrypted" (KG) has a third position "Perforated tape transmission Clear", in which, in addition to the line connections in the "Encrypted" position, a magnet changes the letters or changes. Insert special key or block this key, which is to be inserted once, and that reaching the end of the strip or lifting of the flap of the paper tape scanner interrupts the circuit of this magnet. 12. Operating mode switching device according to one of claims 1 to 11, characterized in that in encrypted operation when pressing a transmit button or switching on the 'tape encoder automatically a trigger magnet * ■ (MI) to control the scanning device for the keyhole strip and a trigger magnet (MV ) are excitable for the wave of a correction distributor. ., ■ - '■■ 1 sheet of drawings © 709 960/116 4.