US1867638A - Telegraph printer - Google Patents

Description

July 19, 1932. WEAVER TELEGRAPH PRINTER Filed June '7, 1950 INVENTOR A WE A VE R ATTORNEY Patented July 19, 1932 ire PHONE AND STATES PATENT,

ALLAN WEAVER, or roar wnsnrneron, NEW YORK, assreuon T AMERICAN mama,

TELEGRAPH. COMPANY, a oonronArron' or'niiw YORK I rnnnannrn PRINTER Application ruse June 7', 1930. Serial No. 459,762.

This invention relates to receivers for.

selective telegraph systems and particularly for those employ ng the Baudot code, that is, those in which the character signals consist of two difierent electrical conditions, such as'permutations of positive and negative impulses or current and no current, extending through a definite number, usually five, of time intervals or units. The features of the invention relate more particu-, larly to the socalled start-stop systems, wherein the rotating member -:or distributor of the receiver is kept in step or in phase with the signals by start-stop mechanism that arrests the rotating member at the end of the signal period or during spacing intervals between signals and again initiates its operation in response at the beginning of each signal.

The present invention is adapted to aselec tor mechanism for a printer of the type disclosed and described in U. S. Patent 1,745 ,633, granted to S. Morton and H. L. Krum on February 4, 1930. ticularly adaptedfor start-stop systems and is one which canbe mechanically operated under the control of a single magnet.

Heretofore in printers wherein the selector mech anism was operated by a single magnet, the magnet was of the neutral type, but it is an object of this equipped with a magnet of the polarized type in an efficient and economical manner. -Another object is to utilize a normal the output circuit of a'current rectifier for operating the polarized magnet in response to received signal impulses.

According to the present invention an alternating current power supply for operatthe transformer onto two opposite points 0 a ll heatstone bridge arrangement, thearms of which each include a suitable rectifier such as disclosed in S. Patent 15 19549, granted to J. Slepian on Marci A, 1930, for producing in a circuit connected to the other two opposite points on": the Wheatstone bridge, a pulsating direct current. Bypassing the pul' sating current through a filter connected to a starting interval or urnt' I This mechanism is par-.

invention to operate a printer 7 voltage in" ing the printer motor is impressed through nating across the circuit,the current pulsations are.

reduced to a minimum. Connected, in series,

in the circuit are two resistances, of relatively high value and at opposite ends ofthese resistances are respectively connected two contacts of a relay, the winding of which isconn-ected to the signal transmissionline. The relay armature is" connected to one side of a winding of the. printer selectormagnet, the other side being connected to the circuit at a point midway between the two resistances. Therefore the drop .in voltage normally across each of the resistancesisutilized for operating the armature of the selector magnet to either of two positions depending on the contact engaged by the relay armature in response to incoming signal impulses.

condenser is connected across eaohresistance for producing a sudden rise" in the current passing through the windings of the magnet I when the relay armature engages either contact.

will appear in Other objects and features forth, when the description hereinafter set taken in conjunction with the accompanying drawing and appended claims.

Of the drawing, Fig. 1 shows theoperating circuit for the printer magnet; Fig. 2 shows asuitable type otrectifier for changing a power supply current; and Figs. 3 and a show fragmentary views of the selector mechanism of the rinter. 1 V

The arrangements herein areshown as us ing an alternating power supply to control the printer operations through a single polar magnet. The power for printing is usually suppliedfrom a 110 volt motor arranged to operate from the electric light or power supply of this voltage. Although an alternate ing current source is shown, this source might just as well be of direct current furnished by a motor generator or a battery. 7

Referring to Fig. 1, the source 11 of alter current is connected through a trans former 12 to opposite points A and Got a Wheatstone bridge arrangement A, which serves as a single rectifier. Each of the arms of the Wheatstone bridgearrangealternating current to a direct so i ment include a suitable rectifier such as illuscurrent in the contacts alternately of the certain metals with respect to current flow across t e junction between the metal and a chemical compound formed directly within the body thereof. In the case Where 2 ly deposited thereon to form two distinct withstand any desired counter-'electromotive force and the whole assembly is clamped by means of an insulating bolt 16 between two end plates 17 and 18 to which terminal concated by arrows. A more detaileddescription of the rectifier unit may be had by referring to Patent N 0. 1,749,549.

As stated above, the induced alternating secondary windings of transformer 12, is impressed on points A and C. When the current in the secondary windings is flowing in an upward direction as indicated by arrow X, the path taken is from A to B, through the windings of retardation coil 21 which has an inductance of about twenty henries, left hand contact of relay 28, through the winding of magnet 29, resistance 26, D to and back to the secondary winding. l/Vhen t is flowing in the opposite The arrangement shown requires less voltage than those em- The telegraph line 27 over which polar signals are transmitted, is connected through the windings of relay 28, the armature of which is arranged to engage its associated in response to the incoming polar signals. 'The relay armature is of the windings of the other side of the windpolar magnet 29, to the output circuit being connected rectifi sistances 25 and 26. In this way, when the er at a point midway between re- 23 and from the right hand side of resistance 25 in parallel. The combined current flows through the left hand contact and armature of relay 28, traverses the magnet windings in say, a right to left direction, and then passes through resistance 26 to point '24. When the engagement with its right hand contact, as for example, after it has just responded to an impulse of negative the potential drop across resistance relay armature is in point 24. Therefore the Condensers are respectively connected across armature engages its contacts.

This manner of operating magnet 29 is suitably adapted for printers designed to beimpulses, particularly operated by polar where the printers are used at a receiver stations in a way transmission or" ever, it may so be used plurality of system employing onepolar signals.

neutral telegraph circuits, that is circuitsconsist of intervals of where the line signals current and no current and a line relay is desirable to improve operating margins. A line relay is particularlydesirable in systems where th printer are'distorted in sl t e printer is operated posited telegraph circuit. The line relay 28 is of the high speed type and requires that direct current be available at the receiving station for operating the receiver magnet 29. The magnet 29 is suitably adapted for operation with the type of printer disclosed in Patent No. 1,745,633, supra, and for a detailed description of the operation of this type of printer reference may be made to that directly in a combe printed, particular parts may be identified in Patent No. 1,745,633. I

he printer is especially adapted for start-stop systems wherein a start and a stop impulse, in addition to the five unit message impulse-s, are received to e incoming signals received by thev iape such as when record each characcams, such as a, b,

' mechanisms to set-up each character.

7 ends, and when it is user/,1; as

rotates in apselection set-up, is printed. The stop impulse coming in over the line, stops the rotation of the receiving shaft until the start impulse tor the next character is received. This stopping of the receiving mechanism after each revolution and restarting by means 0 a signal impulse sent over the line, automatically corrects once in each revolution for any minor variations in the speeds of difierent printers.

In Fig. 3 is shown polar magnet 29 which operates the receiving selecting mechanism of the printer. The magnet is normally in an operated condition. When the start impulse is received the magnet armature 32 is released and a pin 33, fixedly mounted on the armature and acting through an intermediate pivoted lever 34, trips a stop pawl latch 35 which is pivotally mounted on the printer structure (not shown). The stop pawl latch normally engages a stop pawl 36, which blocks a stop arm 37 from rotating. When the latch is tripped the stop pawl rotates slightly due to the pressure of the stop arm against it. The stop arm and the receiving 0, etc. (there being five in all in order to correspond to the five unit code) rotate through power transmitted by friction clutch 38 at the top end of the main shaft 39.

A better understanding of the operation of o the selecting mechanism will be had by referring to Fig. l wherein the mechanism responsive to one impulse only of the transmitted signal, is shown, there being five such sets of When the main shaft rotates slightly in response to the start impulse the cams which are fixed: ly monted thereon, also rotate. \Vhen cam a, for example, rotates sufficiently, it strikes the end of a code bar operating lever 40 which is pivotally mounted on the printer structure. At this time the armature is either operated or unoperated, depending on the polarity or nature of the message impulse received from the line at that time. Let it be assumed that it is an impulse that-will restore the armature to its normally operated position as shown in the figure. As cam a passes its code bar operating lever 4=(), the latter is rotated slightly in a counter clockwise direc tion, carrying back with it a finger or swordshaped member ll. The sword-shaped member is flat and its two arms have upturned drawn back by lever 40 the right hand upturned end will strike the end of a; T

. relay, adapted right hand "end of armature extension The sword member will be rotated clockwise in its pivot 42, and when the cam projection moves to clear. lever 40, the sword member will movedownward against the {left hand lever &3. The T lever is also pivotally mounted and any pressure on its left hand end will cause code bar 44 130 move to the right as provided for by the pin in slot 45. This completes the'setting of the first code bar'for building-up the combination whichiefiects :the printingiof the-desired character. If it is assumedthat the impulse received tromthe line releases the armature and the armature extension, the sword member when pulled back by the action of the selector cam a rotating the code bar operating lever, will strike the letthandend of the armature extension and will be moved counter clockwise to engage the right end of the Tlever and move. the code bar to its nonselected position. In this manner each of the code bars is made'to occupy either a selected or non-selected positionas a part of the operation of printing each character.

The main or cam shaft 39 rotates through one revolution for each character and the remaining four cams engage their respective code bar operating levers successively, it taking approximately three quarters of a revolution of the shaft to "complete the set up of any combination of code bars. 1

In addition to the, five cams, there are in each printer five code bar operating levers, five sword members, five T levers, five code bars, but only one armature extension bar ll which is T shaped at its free end, the ends of the cross piece being-turned up in order to be in engageable relation with all the sword members.

' What is claimed is:

1. A telegraph receiver having a polar for printing characters in response to groups of signal impulses, a source of voltage, a continuously closed circuit for said source, elements of fixed impedance in said circuit for of potential drops, and electromagnetic means responsive to said signal impulses for selecting one of the elements insaid circuit across which thempotentialdrop. occurs, in order to utilize the potential drop produced producing a plurality r'or operating the polar relay of said receiver local source of alternating current for operating said rece ver, means ut1liz1ng said source for'generating a c1rcu1t,'a palr of impedance elements connected. in series 1n said circuit, a distant source of impulses, means responsive to said impulses, a polarized printer magnet connected in shunt, rst to one and then to the direct current in said I trol device is changing other of said impedance elements under the control of said impulse responsive means whereby the potential drop ac ross either of said impedance elements is eflective t0 oper ate or release the armature of-said printer magnet in accordance with the impulses from said distant source.

3. A telegraph receiver adapted for printing characters in response to groups of signal impulses, a normally closed circuit, a local source of alternating said receiver, means for converting said alternating current into a direct current in said circuit, a pair of resistances connected in series with said circuit, a condenser connect ed across each of said resistances, a single polarized printer magnet arranged to be connected across either of said resistances, an directly responsive to ances alternately, whereby the potential drop across the resistance which happens to be shunted at the time, operates or releases the armature of the printer magnet in accordance with the signal impulses.

4. A system for operating a two-position polar relay to either of its two positions from a source of direct current with a current drain upon the source of current independent of the position of the relay comprising two impedances in series with said source and a circuit making-and-breaking control device connected to said relay by contacts whereby of said lmpedances and then across the other dependent upon the contacts of said control de vice, said impedances being maintained under all operative conditions in series with said source. r

5. A system in accordance with claim 4 wherein said control device upon each change from one of its contacts to the other is arranged toreverse the direction of voltage applied to said relay.

system in accordance with claim 4 wherein a condenser is connected across the terminals or each of said iinpedances to absorb the current during the time said confrom one position to another, the charge stored in said condenser serving to accelerate the operation of said relay. i.

In testimony whereof, I have signed my name to this specification this 3rd day of June, 1930. v V ALLAN WEAVER.

current for operating

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