US3006997A

US3006997A - Keyboard transmitter for telegraph signs of the morse type

Info

Publication number: US3006997A
Application number: US768602A
Authority: US
Inventors: Evensen Leif
Original assignee: INTERNAT AUTOMORSE
Current assignee: INTERNAT AUTOMORSE; INTERNATIONAL AUTOMORSE
Priority date: 1958-10-20
Filing date: 1958-10-21
Publication date: 1961-10-31
Anticipated expiration: 1978-10-31

Description

L. EVENSEN Oct. 31, 1961 KEYBOARD TRANSMITTER FOR TELEGRAPH SIGNS OF THE MORSE TYPE 2 Sheets$heet 1 Filed Oct. 21, 1958 more mw o Oct. 31, 1961 v s 3,006,997

KEYBOARD TRANSMITTER FOR TELEGRAPH SIGNS OF THE MORSE TYPE Filed Oct. 21, 1958 2 Sheets-Sheet 2 3,006,997 1C6 Patented Oct. 31, 1961 3,006,997 KEYBOARD TRANSMITTER FOR TELEGRAPH SIGNS OF THE MORSE TYPE Leif Evensen, Goteborg, Sweden, assignor to International Automorse, Goteborg, Sweden Filed Oct. 21,1958, Ser. No. 768,602 15 Claims. (Cl. 17817) This invention relates to keyboard transmitters for telegraph signals of the Morse type.

Keyboard transmitters of this general type are known and work according to the principle that the current.

pulses are produced by a contact arm which sweeps over a contact are consisting of mutually similar and insulated contacts which are, in combinations corresponding to the individual telegraph signals, connected with potentials by means of a keyboard. The keyboard comprises one key for each telegraph signal. The dashes are produced when the cont-act arm passes over a number of successive contact positions, preferably three, to which contacts are applied potentials, the dots when the arm passes over single contact positions having potential applied thereto and the intervals when the arm passes over positions having no potential applied thereto. The contact point of the contact arm is made a little broader than the insulating layer between adjacent contacts, so that no interruption will occur within the individual dashes.

The keyboard is given a form similar to that of a typewriter, and by a known form of keyboard transmitter, as for instance shown in German Patent 225,397, each individual key is mechanically fixed to an arm which makes contact with cross-bars, each of which are again connected to one are contact. By arranging incisions either in the key-arms or in the cross-bars the desired combinations of signals are obtained.

Known keyboard transmitters have a number of disadvantages. In the type described above, the key in question has to be pressed down until the whole signal has been sent. This requires an experienced operator if parts of the signal are not to be lost. In some other types of keyboard transmitters, the contact-arm has to pass the whole contact-arc for every signal, the contact-arm being either removable in one direction only, or made so as to return from the end position of the are. This is a disadvantage in connection with signals of the Morse type in which the contact-arc must comprise at least nineteen contact positions (in case the dashes are produced by making the contact-arm pass over three successive positions and the dots as well as the intervals between the signal elements by passing over one position)- the signal for (zero) consisting of five dashes and four intervals and thus consisting of nineteen elements. On the other hand, the shortest signal (E) consists of one single dot only, thus just requiring one are contact. If, therefore, the contact-arm is to move each time to the end position, and then back to the home position, or to make one full revolution to reach said home position, the interval between a short signal and the subsequent one will be unnecessarily long as compared with the interval between a long signal and the following one.

I have already made a suggestion to use relays which are operated and locked in distinct combinations according to the individual signals upon operation of a key, which relays serve to apply a voltage to arc-contacts engaged in building up the respective signals. In said construction, the operator could release the key immediately. However, relay contacts do not make such a transmitter sufficiently foolproof, especially when working under unfavorable conditions, and have to be frequently cleaned and adjusted.

The main object of this invention is to improve such types of keyboard transmitters for the purpose of reducing the requirements of experience and attention; a fur-- ther object of the invention is to obtain the greatest possible security of operation combined with a minimum of maintenance costs.

When using a keyboard transmitter according to the invention it will be suiiicient if the operator is a skilled typewriter keyboard operator.

The telegraph signals delivered at the output of the apparatus will be at least as good, if not better than the signals of a very experienced telegraphist sending by hand. The greatest advantage, however, will most likely be the fact that the apparatus in case of distress traific (i.e. from life-boats and similar) may be operated by almost anyone.

The whole keyboard with the necessary associated electrical equipment may be concentrated so much that the space required is just that of a common portable typewriter.

Therefore, having the above in mind, the present invention relates to a keyboard transmitter for telegraph signals of the Morse type, in which the current pulses forming the dashes and dots of which the signals consist, are produced by a contact-arm of a driven signal producer passing over a combination of potential-carrying and neutral contacts of a contact-arc, the contacts of which can be connected with a voltage source, said application of potentials to the arc-contacts being controlled by means of the keys of a keyboard; according to the invention the signal producer is provided with an aux iliary contact-arm associated with a contact-arc the contacts of which, when the keys of the keyboard are operated, are connected with the voltage source in such way that when the telegraph sign is completed a stop relay is operated to stop the movement of the sign producer.

This and other features of the invention will appear from the following description of the drawings, in which:

FIG. 1 shows, diagrammatically, one embodiment of the invention,

FIG. 2 shows a part of a keyboard,

FIG. 3 shows, diagrammatically, how some of the telegraph signals are built up,

FIG. 4 is a longitudinal section of a key with holding magnet, and

FIG. 5 is a longitudinal section of a motor driven signal producer.

The keyboard transmitter according to the invention comprises two main parts shown to the left and right respectively in FIG. 1. The first part belongs to the keyboard, the central portion of which is shown in FIG. 2 and numbered 17. The keys surrounded by the broken line in FIG. 2 are the same as shown in the middle left of FIG. 1. The two outer left and the two outer right keys correspond with the two first and two last keys respectively of the keyboard, namely 1, Q, 0 (zero) and (equal sign). In FIG. 1 each of the key plates 14 carrying the designations, such as E, D, 4, C," R, F, 5 are shown fixed to a leaf spring, a spring-loaded arm 15 or the like, the journalled end of which is connected with a common ground. These arms or springs co-operate with contact points electrically connected with one magnet coil 13 each, the other end of which is connected to a common wire numbered 0. The arms or springs 15 are also provided with the corresponding sign as the sign on the key plate 14, so for instance the arm belonging to key C is designated by c', the corresponding maget coil by c and a lead connected with. the upper end of the coil c by c".

The said leads are also numbered 11 and form together with the leads 12 a network of wires of which certain of the crossing points have been interconnected by electrical one-

way valves

16 and 16", in the present case shown as dry surface rectifiers.

The individual leads 12 are numbered 1-9, 1'10', which leads are connected with contact points of two arcs of a rotary switch shown to the right in FIG. 1 and in the following description and claims designated as the signal producer.

As shown in the drawing, the contact points a1-a9 are connected with the leads 1-9 respectively, and the contact points a1'a10' connected with the leads 1'-10' respectively. The signal producer is provided with two contact brushes or arms 18 and 18' which pass over the contact arcs a and a respectively. Said contact arms are fixed to a disc 21. The

arms

18 and 18 also sweep over semi-circular contact bars 19 and 19' respectively.

The disc 21 forms one part of an electromagnetic clutch, and at least the central portion of this disc is made from a ferro-magnetic material. The other part of the clutch comprises an electromagnet 22 which is continuously driven by a motor M and is connected with the outer circuit via

slip rings

23 and 23 and brushes 24 and 2.4 respectively. It is to be understood that the signal producer in FIG. 1 is only diagramatically shown, and a practical embodiment of same will be described in detail with reference to FIG. 5.

'The disc 21 is also provided with an arm 26 protruding from its periphery, the free end of which is connected with a helical spring 27 the other end of which is connected with the chassis of the signal producer as shown. The signal producer is shown in its home position in which the two contact arms 18 and 18' are keeping their respective home contacts 25 and 25' open. Contact 25 is placed in the keying circuit K, and contact 25' in the circuit of a stop relay S with one make contact s1 and one break contact s2. The

contact bars

19 and 19 are interconnected via a rectifier and are individually connected with the relays T and S respectively of which the first one has a break contact t in the above mentioned keyin-g circuit K.

The power for the motor M and the relays S and T is taken from a direct current source B, connected as shown. The speed of the motor M may be regulated byan adjustable resistance R.

Part 22 of the electro-magnetic clutch is continuously rotating, driven by said motor and is to be electromagnetically coupled with the disc.

The keyboard transmitter according to the invention operates in the following way. Provided the motor is running at the desired speed, the keys 14, 15 can be operated in succession according to the telegraph signals to be sent. As appears from FIG. 1, the keying circuit K is arranged for closed circuit working so that the circuit is closed when relay T is inoperative.

Provided the dashes of the signals are represented by three contact positions in the contact arc, and the spaces and the dots by one position each, it is evident that in all events the odd positions within a signal will always represent elements of the signals. Consequently it is only necessary to provide for an operation of relay T in the positions of the signals representing the spaces and this is just what is done.

11f the signal for 4 is to be sent, the provision is as shown in FIG. 3. In FIG. 3 this signal comprises four dots followed by one dash. Consequently, the contact points a1, a2, a3 and a4 must be connected with a voltage so that relay T is operated when the contact arm 18 passes over said contact points.

' When key 4 is depressed, a circuit is closed from -|-B via break contact s2, brush 24, slip ring 23', clutch magnet 22, slip ring 23, brush 24, lead 0, magnet coil 13 and contact 15 of key 4 to ground (frame or chassis), the negative pole of B being also groundedas shown. The electro-magnet 13 belonging to key 4 is magnetized and will keep the contact 15 in its operated position. Simultaneously the clutch magnet 22 is energized and will carry with it the brush-carrying disc 21, so that the brushes 18 and 18' will be moved out of their home positions. As will appear from the drawing, ground potential has been applied to the arc contacts a1, a2, a3 and a4 via the contact arm 15 of key 4 and the corresponding rectifiers 16 as well as leads 1-4 respectively.

Similarly ground potential has been applied to are contact a6 via the same contact arm 15, the corresponding rectifier 16' and lead 6'.

The brush-carrying disc 21 starts rotating and when the brushes leave their home positions contacts 25 and 25' respectively are closed. Since relay T is inoperative, the circuit K is thereby closed. Said circuit will remain closed until relay T operates, and this will occur when brush 18 reaches arc contact al. The operating circuit for T is from battery +B, relay T, bar 19, brush 18, contact a1, lead 1 and the corresponding rectifier 16, contact 15 belonging to key 4 to ground (negative pole of battery B). Relay T remains operated as long as brush 18 sweeps over contact al. A space is thereby produced since, when operating, relay T will open the keying circuit K. During the further travel relay T will be operated when the brush 18 sweeps over contacts a2, a3 and a4, thereby producing four dots. When the brush 18 leaves contact a4, relay T is again released and will remain released until the brush 18' reaches contact a6. Said contact has no potential, but the corresponding contact a6 of the other contact arc has ground potential via lead 6' and the corresponding rectifier 16', as already described. Consequently, stop relay S operates in a circuit from +B via relay S, bar 19', brush 18', contact a6, lead 6, rectifier 16', contact 15 belonging to key 4 to ground. S closes its own holding circuit via make contact s1 and home contact 25.

Simultaneously relay T is operated in a circuit from +B via relay T, bar 19, rectifier 20, bar 19', contact s1 and home contact 25. Thus, the keying circuit is opened, and since the last opening of said circuit the contact brush 18 has passed over three contact positions, namely the space between contacts a4 and a5, contact a5 which was neutral, and the space between a5 and a6. These three positions correspond with a dash, see also FIG. 3. The result is therefore that the signal 4 has been sent.

As appears, stop relay S opens its break contact s2 so that the clutch magnet 22 and the holding coil 13 of key 4 is de-energized. Consequently the brush-carrying disc 21 will stop and is brought back to its home position by spring 27 which was stressed during the sweep of brush 18 from contact a0 to contact a6. During this backward movement of the brush-carrying disc 21 the relays S and T are kept operated so that the keying circuit K is kept open.

When the brushes 18 and 18' reach home position, the home contacts 25 and 25' are opened so that both relays S and T are de-energized. The key transmitter is now in condition for sending a further telegraph signal.

In FIG. 3 is shown how some of the signals are built up. The arc contacts a are shown as black rectangles and the spaces between said contacts as white rectangles. Said spaces have been numbered bl-b10. The shortest Morse signal is E which comprises a dot only.

When this is to be sent, it is only necessary to provide for stopping of the brush-carrying disc 21 after brush 18 has passed through the first position or space b1. As soon as brush 18' reaches contact a1, the stop relay S is operated via rectifier 16 belonging to key B. As soon as said relay S opens its break contact s2, the magnet clutch is de-energized and the brushes are brought back to their home positions by spring 27.

The longest signal of the Morse alphabet is 0 (zero) comprising five dashes. When sending this signal, the

brushes

18 and 18 must pass through their entire contact arcs during which passage relay T is energized when the brush is passing over the arc contacts a2, a4, a6 and a8. Between these contacts are always three positions corresponding to in all four dashes. The last dash of the signal is produced when the brush 18 passes the positions b9, a9 and M0. When brush 18 reaches contact all), the stop relay S is operated via said contact, lead 10', rectifier 16 belonging to key and the corresponding contact 15 to ground.

A practical arrangement of the keys is shown in FIG. 4 in longitudinal section. The finger plate 14 carrying the individual signals engravedthereon is fixed to the upper end of a bolt 15 of ferromagnetic material. The bolt is passed through a magnet core in the form of a hollow cylinder 28 open at the bottom end.

The top wall is provided with a central, threaded portion 29 with a central bore in which the bolt 15 may move axially. The threaded portion 29 may be inserted in an opening in a frame plate not shown and fixed to same by a nut.

The inner chamber of the cylinder 28 is filled by a coil 13, the spool form of which is numbered 37 and windings 38. The outer protecting layer is numbered 36. The spool has a central bore registering with the bore in the top wall of the cylinder 28 for the lower end of bolt 15'. Said bolt has in the middle of it a peripheral groove for a spring clip 32 with a protrusion 33. This clip 32 is urged against the bottom of a recess 31 in the end wall of the cylinder by a spring 35 acting against the upper end of the spool form 37. The protrusion of the clip 32 slides in a slot 34 in the side wall of the recess 31 so as to prevent the bolt 15 from being turned.

As will appear from FIG. 4 the bolt 15 forms a part of the magnetic circuit. The lower end of said bolt is provided with a contact point 39 which cooperates with a contact plate 40 fixed to the center of a ferromagnetic disc 41 which serves to close the magnetic circuit. Said disc 41 does not contact the inner wall of the cylinder 28 and leaves a small air gap between said parts.

Since said disc 41 also forms part of the electric cirouit of the key, the same is also electrically insulated from the cylinder 28 by a disc 42 of insulating material. Said discs 31 .and 42 are kept in place by a resilient ring 43 placed in a peripheral groove in the inner wall of the cylinder 28 as shown. Two connecting lugs 45 and 46 are fixed to the said

discs

41 and 42. The contact lug 45 is placed between the

discs

41 and 42 and in electrical connection with the first of these discs and has a portion led through an aperture in disc 41. The other contact lug 46 is fixed to disc 42 by means of a nail or pin 47 which is driven into a small hole in the discs and into an insulating disc.

The -ferro-magnetic body 28 and thus also the bolt 15 are connected with ground potential via the above ment-ioned frame plate to which said body is fixed by nut 30. One of the leads 11 is connected to lug 45 and the lead 0 to lug 46, see FIG. 1.

When the finger plate 14 is depressed against the -ac tion of the spring 35, the contact point 39 will touch the contact plate 40 and close the circuit for the electro-magnet so that said bolt is kept in this position until the circuit is broken when contact s2 is opened, see FIG. 1.

A practical construction of the signal producer appears in FIG. 5. A cylindric or oval housing 48 has an inner, separating wall 49 and contains an electro-motor M, the shaft of which is passed through a central bore in the separating wall 49 and provided with a pinion 52 which meshes with a gear wheel 53. Said gear wheel is fixed to a shaft 55 which also carries a pinion 54. Said shaft 55 is supported in bearings in the separating wall 49 and a top wall 50 fixed to the housing 48 by screws 51. The pinion 54 meshes with a gear wheel 56 fixed to a shaft 57 which is also rotating in hearings in the walls 49 and 50. The upper end of shaft 57 is in one piece with, or rigidly connected with a shaft journal 58 which is in one piece with a magnetic body 22 in the form of a hollow cylinder open at the upper end and provided with a central core. The cylindric wall of said body is numbered 59. Two slip rings 23 and 23' embedded in a cylindric sleeve of insulating material are fixed to the lower end of the magnetic body as shown. I These slip rings are connected with the outer and inner end respectively of acoil 61, wound on a coil form 60 of insulating material and arranged within the magnetic body 22 between the central core and its outer wall.

In the central core is provided an axial bore into which is introduced a helical spring 65 and the lower end of a shaft 62 which carries a ferromagnetic disc 21 and a washer 69 of non-magnetic material.

Parts 21 and 22 form together an electro-magnetic clutch as shown diagrammatically in FIG. 1. The nonmagnetic washer 69 prevents sticking. An upper bearing for shaft 62 is numbered 64 and is formed on the free end of a bracket 63 which is fixed to the top wall 50 by one of the screws 51. The bracket 63 forms a double angle, and the leg which is fixed to the top wall 50 is numbered 66.

As will be understood, the shaft 62 is arranged for restricted axial movement between its bearings and is urged to the upper position shown by spring 65. A spiral spring 27' has its inner end fixed to the shaft 62 and its outer end to a boss 68 formed on the bracket 63, by a pin 67.

The ferro-magnetic disc 21 carries two

brushes

18 and 18 which are fixed to the disc by screws 70 and electrically insulated from the same and from one another.

As shown in FIG. 5, the two contact arcs a and a are arranged at the same side of the shaft 62 parallel with one another so as to cooperate with their respective brushes 18 and 18'. These contact arcs may be built up by a lamination of small copper plates alternating with correspondingly shaped insulating plates, similar to a collector of a collector motor. By means of screws electrically insulated from the contact plates, the two contact arcs are fixed to two brackets 71 carried by the top wall 50 andfixed to the same by screws 73.

All the parts located above the top wall 50 may be protected by a removable cover 74.

The motor M rotates the magnetic body 22 at a constant speed dependent upon the speed of the motor and the ratio between the pinions and gears 52, 53, 54 and 56. The slip rings 23 and 23 are in contact with

respective brushes

24 and 24 not visible in FIG. 5. Until the body 22 is magnetized, the other parts will remain in the position shown. When the magnetic circuit is closed (when a key 14, 15, FIG. 1, is depressed) the disc 21 will be moved against the action of spring 65 and brought to rotate together with the magnetic body 22. By this axial movement of the disc 21 the brushes 18 and 18' will be brought in contact with their respective contact ar'cs a and a and sweep over the contact segments. During this rotation the spiral spring 27 is wound up and stressed. As soon .as a complete telegraph signal has been produced, the energizing circuit of the magnetic clutch 21, 22 is opened and the disc 21 pushedaway from the magnetic body 22 by spring 65. Immediately thereupon the stressed spring 27 will bring the disc 21 back to its home position in which the

contacts

25 and 25 which are not visible in FIG. 5, but shown diagrammatically in FIG. 1, are opened.

The sign producer just described has the advantage that the brushes 18 and 18' do not slide over the contact are during the movement back to home position.

This provides the advantage that the wearing of said parts is minimized. A further advantage is that a depression of a new key before the sign producer has reached its home position will not have any influence upon the keying circuit, so that said new key may be depressed in advance, i.e. during the return movement of the disc 21, the holding circuit for the keys and the electromagnetic clutch being open at break contact s2 until relay S is released. When this happens the signal producer may again be started by a key already pushed down or pushed down after the signal producer has reached its home position.

The brushes 18 and 18' are provided with soldering tags for connection of flexible wires instead of the cont-act 7 bars 19 and 19' shown in FIG. 1. shown in FIG. 5.

What is claimed is:

1. A keyboard transmitter for telegraph signals of the Morse type, comprising a contact arm adapted for producing current pulses forming dashes and dots of which the signals consist, a combination of potential-carrying and neutral contacts constituting a contact-arc, means for sweeping said arm across said contact-arc, a voltage source adapted for being coupled to said contacts, keys constituting a keyboard and adapted to connect the contacts selectively to said source, an auxiliary contact-arm, an auxiliary contact-arc operatively associated with said auxiliary contact-arm and including contacts one of which, when the keys of the keyboard are operated, is selectively adapted for connection with the voltage source with the auxiliary contact arm in contact therewith, and a stop relay responsive with said auxiliary contact arm positioned on said one contact for completing a telegraph signal and stopping movement of the first said contact-arm.

2. A keyboard transmitter as claimed in claim 1, comprising a circuit operatively associated with the stop relay and including a contact means which is closed when the first said contact-arm leaves its resting position and an operating circuit operatively associated with the stop relay to prime the first said circuit to operate said relay.

3. A keyboard transmitter as claimed in claim 2, comprising a make contact in the stop relay, an energizing circuit including said make contact, a keying relay in said energizing circuit comprising a contact, said keying relay contact being open with said keying relay energized, a keying circuit coupled to the latter contact, the keying circuit being maintained open with the stop relay operated.

4. A keyboard transmitter as claimed in claim 3, further comprising a contact bar, and an auxiliary contact bar, the keying relay being connected with the make contact of the stop relay via the contact bar and auxiliary contact bar and an electric one-way valve between said bars.

5. A keyboard transmitter as claimed in claim 3, comprising a contact which is kept open in starting position and which is arranged in the keying circuit to close the same.

6. A keyboard transmitter as claimed in claim 5, wherein the contact of the keying relay, is a break contact, the keying circuit conducting only when the contactarm is in positions representing the spaces between the dashes and dots of the single telegraph signals.

7. A keyboard transmitter as claimed in claim 1, comprising a contact in the stop relay operatively associated with the keys of the keyboard whereby with said contact closed said keys are continuously energized and held operative, when the same are operated, and a circuit operatively associated with said stop relay and including the latter said cont-act whereby with said contact open a previously operated key of the keyboard is de-energized.

8. A keyboard tnansmitter as claimed in claim 7, comprising a ferromagnetic bolt coupled to each key, a pot- Said wires are not shaped magnet core comprising an energizing coil accommodating said bolt so that the bolt can be moved into the coil, and a contact coupled to and by means of which the energizing coil is energized so that the bolt is kept in operated position as long as the core is magnetized, the contact being positioned so as to be contacted by said bolt.

9. A keyboard transmitter as claimed in claim 8, comprising a ferromagnetic disc which closes a magnetic circuit between the bolt and the magnetic core, and a further contact, the latter two said contacts being operatively associated for electrical engagement and one of these contacts being mounted on said disc.

10. A keyboard transmitter as claimed in claim 1, the keyboard of which comprises one key for each telegraph signal and each key is associated with a particular combination of potential carrying and neutral contacts for building up respective of the telegraph signals, a voltage source, electric one-way valves coupling said source to the latter said contacts, key-holding magnets operatively associated with said keys, and an energizing circuit operatively associated with said magnets, the contacts of said combination being operatively associated with and adapted to close the energizing circuits of the key-holding magnets.

11. A keyboard transmitter as claimed in claim 10, in which each valve connects one of said keys and one of said contacts of the contact-arc.

12. A keyboard transmitter as claimed in claim 11, comprising a driving means for the contact-arms, and an energizing circuit coupled to said driving means, each contact associated with one of the keys being connected in the circuit of said driving means and in series with the holding magnet of the associated key.

13. A keyboard transmitter as claimed in claim 12, in which the driving means comprises a continuously driven electro-magnetic clutch including a driven part carrying the contact-arms.

14. A keyboard transmitter as claimed in claim 13, in which the electromagnetic clutch comprises a pot-shaped magnet core and an energizing coil, a motor driving said core and coil, said coil being arranged for the magnetization of the core in its axial direction, an armature in the form of a ferromagnetic disc which is axially movable relatively to the core and which is journalled for free rotation and arranged to move the contact-arms to and fro with respect to their respective contact-arcs when the armature is moved to and fro with respect to the magnet core.

15. A keyboard transmitter as claimed in claim 14, comprising two springs operatively associated with and acting on said armature, one spring urging the armature away from the core, and the other spring being stressed when said motor is driving the armature so as to bring the armature back to its starting position when the core is de-energized.

References Cited in the file of this patent UNITED STATES PATENTS 897,454 Cardwell Sept. 1, 1908