US2653997A - Teletypewriter - Google Patents

Description

Sept. 29, 1953 A. A. SWEENY ET AL TELETYPEWRITER Filed Sept. 27, 1951 RECEIVER 5 INVENTORS ALFREDAJ'WfENY MAURICE F. .rweeuy STAT/0N A Zita/ways Patented Sept. 29, 1953 TEEE'IYPEWRITEE Alfred A. Sweeny, -Denver, and Maurice F. Sweeny, Silt". Colo.

Application September 27, 19.51,.S.erial-No.'248,57l6

1 Claim. 1

This invention relatestov improvements in teletypewriters and has reference more particularly to a wireless teletypewriter mechanism.

Telety-pewriter machinesv of various kinds are now. inuse for sending and distributing information such asnews, stock reports and/or messages of various kinds. Such machines, being mechanical and operated by electromagnetic devices, including relays, magnets and. escapements of various. kinds, are highly complicated, very costly and-subject to breakdowns.

It is. the object of thisinvention to produce a mechanism that will transmit messages. from one place to another either overmetallic circuits or. by means. of modulated radio carrier waves, and which shall. have a minimum of parts.

Another object is toproduce amechanism of such construction that the message; can be sent by manually operated or perforated paper tape operated keys corresponding to the ordinary typewriter keys and which will receive the message at a distant station. and. print it. ona tape in easily readable form.

Ihe above andany other objects that may become apparent as the description proceeds are attained by means of'a construction and an arrangement of parts that will now be described, for which purpose reforencewill behad' to the'accompanying drawings in which the invention has been illustrated and in which the. single figure is a diagram showing the several elements. in their operative relation showing a manual keyboard control;

In the drawings, reference character M designates a synchronous motor, preferably a two pole motor, and S designates ashait directly con.- nected' with the motor. Secured to the shaitiis 'a slip ring IS" with which brush llj cooperates.

The shaft carries a number of disks [2 'of'inr sulating material; there is a separate disk. for each letter, number and/or other character. to be transmitted, whichpreferably corresponds to the characters on a standard. typewriter. Each disk has a short metal segment. [3, in its. periphery and these are all connected'witha common conductor I I by means of. radial. conductors l5.. A brush [6 is positioned to contact with the periphery of each disk. Brushes. ware all post.- tioned in the same radial plane passing through the shaft axis, as. shown. A, disk. G,. somewhat larger in diameter than disks. L2, is attached to the end of the shaft opposite. from. the motor. If disk G is made. from opaque material, it: has all of the letters numbers and. other characters as indicated at Ll. Disk G may, however,v be made. from/transparent plastic or other suitable transparent material and. covered. with. an. opaque painter other opaque outer film whichmay have Darts removed to form; the-letters. A str0botron" lamp I8 is positioned, preferably, but. not necessarily, in. the radial plane thatcontains brushes t6, and isv provided on one side with a transparent window through which abeam of light emerges whenever the lamp functions, which beam is adjusted to travel in the radial plane above referred to and tov strike disk (3 in a position to project light through. the stencils or through the transparent areas outliningthe letters and/or othersymbols. A lens l9 may be interposed between thelampand disk G tocollimate the rays from the lamp. Positioned on the far side. of disk G. is, a sensitized tape20 thatis moved, from right to left by means 015a step by step mechanism comprising. a ratchet wheel '21 and a pawl 22*operated: by solenoid. 23 when it is energized bya. current. from the: multivibrator trigger circuit 24..

Messages. areinitiated, by means of an. apparatus that will now be described.

Asourceot direct. current, for example a storage battery BAT, oi the desired voltage and capacity is provided and has one pole grounded at E. A conductor 25 is; connected withthe other pole and extends to a keyboard where it forms the commonlead for all of the sending key switches which. will now be described. The sending apparatu has a keyboard similar to that of a typewriter, having one key for each letter, number,.punctuatiommark; and any specialcharactor that. may be desire d;. thereis only one key for each letter, as capital letters only are used. In the drawing. only three keys are shown, one representing, the. letters, one representing the numbers andtheother the punctuation marks and. special characters, if any. Associated with each key isastationary 'switchcontact 21.. For the-purposeof this explanation, the stems ZtA of the-keys will be considered-as made from insulating material. Springs." areassociated with the keys andsnormally hold them in the. elevated position shown in: the drawing. Attached. toeach key stem are switch contacts 29 and 29A that are. moved into engagement. with. the correspondingstationary contacts; Z1; whenever the keys are depressed. Numeral all-designates.- a spacer bar that isheld-in elevated position by springs 3i and which has insulating stems, 32. that carry switch contacts 33 and 33A into. engagement with. concut, therein: as stencils. and arrangedtin. a circle 55. tacts u when the bats are.- depressed.

Conductors 35 connect the movable contacts 29 with the corresponding brushes I6. The one that is connected with the movable contact 29 of the A key extends to brush I6 at the disk nearest disk G and the others follow in regular order.

Station A is provided with a relay comprising solenoid coils 35A and 36. A magnetic core 31 is operatively associated with the solenoids and is connected with two spaced movable spring type relay contacts 43 and 39. Contacts 39 and 49 are normall in engagement. When the solenoid is energized, core 31 will be moved towards the left, thereby opening circuit at 39, 40 and closing contacts at 38, 43.

Let us now assume that key A is depressed. Contacts 29 and 29A will then be moved into engagement with contact 21 and the corresponding conductor 35 will be energized. When contact I3 on the first disk I engages brush I6, current will flow through conductor I4 to slip ring I0, thence through wire 42 and through contact 40 and 39 to multivibrator 24 and to the pulse shaping circuit. Multivibrator 24 operates solenoid 35A which attracts core 31, moving switch members 33 and 39 to the left whereupon circuit 38, 43 will close and 39, 40 open. When key A is moved downwardly, contact 29A also becomes energized by engagement with contact 21, thereby energizing conductors 44, whereupon current flows from 44 to 38, thence through the solenoid 35 to ground, locking the relay.

Attention is called to the fact that the current in wire 42 has a complete conductive path to the pulse shaping circuit after it passes relay contacts 39, 40 and is not delayed by reason of the impedance of coil 35A and the inertia of the armature 31.

The pulse of current which reaches the pulse shaping circuit is modified and passed on to the modulator and radio transmitter. When key A is released, wires 35, 44 are de-energized and the solenoid relay is thereby unlocked, and the parts return to the position shown on the drawing. When another ke is depressed the operation just described is repeated.

When words are to be spaced, bar 30 is moved downwardly, whereupon contacts 33 and 33A engage the live contact 34 in the same manner as explained in connection with contacts 29 and 29A.

The apparatus just described has been designated as Station A. Identical apparatus is located at Station B, and at all other stations if more than two are used.

On the drawing, a few of the elements of Station B have been indicated. The radio receiver is connected by wires to the trigger circuit I24 and conductors project from the trigger circuit, which have been designated by numeral 48.

It must be remembered that the equipments at the two stations are identical. In Station B, the motor has been designated by MB to distinguish'it from motor M at Station A. The two synchronous motors M and MB are connected for synchronous operation by any one of the several methods commonly employed for this purpose, and the shafts S at the two stations therefore rotate in exact synchronism.

Whenever the pulse shaping circuit is energized, which occurs each time a sending ke is pressed down, a pulse is instantly transmitted to the modulator which modulates, keys or interrupts the carrier wave sent out by the radio transmitter. The carrier wave is received at Station B, and the modulations, or interruptions or pulses operate trigger circuit I24 all of which is common in the art of radio. Trigger circuit I24 through conductors 49 cause the strobotron to light. Since such impulses are controlled as to time by the closing of circuit from any one of brushes I6 to the corresponding contact I3, and since the brushes are all in the radial plane which also contains the strobotron, such impulses will take place and the strobotron glow at the instant that the corresponding letter, figure or other symbol on disk G is in line with the light beam from the strobotron; light will therefore pass through the stencil openings of the corresponding letter or figure, etc., and strike the sensitized paper 20 which is positioned in a light-proof compartment.

Brushes I6 and conductors I3 are of a width to allow for engagement through the maximum angle of hunting of the motors.

The strobotron is connected through conductor 58, brush 51, commutator 56, conductor 55, slip ring 54, brush 53, conductor 52, rheostat SI, and conductor 50 to the battery. Battery potential on the strobotron is necessary before it can be fired by the signal from the receiver. Due to the very narrow brush 5! and the size and arrangement of the conductors of commutator 56, the strobotron fires at only the instant when a letter on disk G is at exactly its maximum height of travel, thus reducing distortion.

At the time the strobotron is lighted, solenoid 23 is energized and moves the sensitized tape one space. The tape moves in the same direction as the upper part of disk G, and therefore any distortion due to relative movement is prevented. Since the times here dealt with are exceedingly small, practically no distortion results, even when the tape is stationary at the time the light strikes. The exposed tape is developed by contact with gas in a well known manner, and the characters become visible and readable. A separate symbol, as for example, an open square or oblong figure, may be used to indicate a space between words, and it is possible to leave such spaces blank as on an ordinary teletypewriter tape.

Operation When a message is to be transmitted from Station A to Station B, it is spelled out by striking the keys in the same manner as on a typewriter or teletypewriter machine. The two motors M and MB are operated in synchronism as above explained. If key A, for example, is struck, conductor 35 will be connected with the ungrounded pole of the battery, and when contact I3 engages the brush I 6 on the A disk I 2, relay coil 35 is energized and by means of radio as described above, the trigger circuit and strobotron is activated. Since the source of light, brushes I6 and the stenciled character corresponding to any disk I2 are as previously pointed out, in the same diametrical plane, the image of the character will be projected onto the tape at the same point relative to the two axes of the tape rolls. After or during each exposure, solenoid 23 functions to step the tape ahead one space. Any lag due to the small time constant of solenoid 3G and associated parts can be compensated for by a corresponding angular adjustment of disk G relative to disks I2.

Disk G and tape 20 are preferably enclosed in a light-tight compartment, a portion only of which has been indicated by broken lines, or all equipment at each station with the exception of the keyboard may be enclosed in a light-tight compartment. The tape may be of the type that is developed by contact with a gas, sometimes referred to as Ozaprints. There are several methods being practiced which may be employed for developing the tape, and this has therefore not been shown.

Attention is called to the fact that the circuit illustrated on the drawing is of the block type in which the strobotron, the modulator and the trigger circuit have been identified by name. These elements are well known to and understood by persons versed in this art. In the book entitled Basic Radio by Hoag, Van Nostrand Co., Inc, tenth printing, in chapter 19, on page 127 the circuit contemplated for the trigger circuit is shown. Either the simple counting circuit (Figure 19A) or the self stopping circuit (Figure 193) may be used, the latter being preferred. In chapter 18 beginning on page 120 the circuit and elements indicated on the drawing by the word strobotron are shown and explained (Figure 18D), and in chapter '16 the various embodiments of modulators are shown. The trigger circuit may be a one shot multivibrator as is defined in Principles of Radar, M. I. T. School motors may be synchronized in any of the several Ways now employed for this purpose.

In Figure 1 of the drawing and in the specification, a strobotron and a sensitized tape have been shown and described as the means for recording the message, as this may be efiected by simple mechanical means.

Having described the claimed as new is:

A device for transmitting intelligence to and from two spaced stations comprising, in combination, a set of movable keys, one for each character to be transmitted, a source of direct electric current one pole of which is grounded, a stationary contact electrically connected with the ungrounded pole of the current source, operatively positioned adjacent each key, each key having two electrically insulated contacts positioned thereon for movement into electrical engagement with the corresponding stationary contact, each device having a rotatably mounted shaft, means comprising a synchronous motor invention, what is connected with said shaft to effect synchronous rotation of the shafts of spaced devices, each shaft having a disk attached to one end thereof, said disk having the characters to be transmitted arranged in a circular zone, in angularly spaced relation, the characters having transparent outlines, the shaft having a contact for each character supported thereon for conjoint rotation therewith, each contact moving in a circular path when the shaft turns, a brush positioned in the path of each contact so as to be in conductive engagement therewith once each revolution of the shaft, the several contacts being angularly spaced so that they come into engagement with their corresponding brushes successively when the shaft turns, the angular displacement of the contacts being equal to 360 degrees divided by the number of characters, a strobotron positioned to throw a beam of light on the zone of the disk which contains the outlines of the characters, a slip ring on the shaft, means for electrically connecting all of the said contacts with the slip ring, one of the two contacts on each key being electrically connected with one of said brushes whereby the said contact on the key will be in electric conductive relation with the slip ring once each revolution of the shaft, means effecting an operation of the strobotron at the instant when an energized brush comes into electric engagement with a rotating contact whereby the character on the rotating disk which corresponds to the energized brush will be illuminated, means including a multivibrator and a pulse shaping circuit connected in parallel to the slip ring, a locking relay operatively connected with the multivibrator for breaking the circuit from the slip ring to the multivibrator and the pulse shaping circuit after the multivibrator has functioned to allow only a single operation of the strobotron for each operation of a sending key, and means comprising a photosensitive tape for producing a photographic record of the characters successively illuminated by the strobotron.

ALFRED A. SWEENY. MAURICE F. SWEENY.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,074,037 Watson Mar. 16, 1937 2,104,543 Lemmon Jan. 4, 1938 2,104,544 Lemmon et al Jan. 4, 1938 2,407,336 Young Sept. 10, 1946 2,510,072 Clark June 6, 1950 2,578,025 Sweeny et a1. Dec. 1'1, 1951

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