US2302016A - Printing telegraph system - Google Patents

Description

5 Sheets-Sheet l Ila C. J. FITCH acz B4 eca Filed Dec/l8, 1940 PRINTING TELEGRAPH SYSTEM v 52-4 l m:

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INVENTOR w ATTORNEY NOV. 17', 1942. Q FITCH I 2,302,016

PRINTING TELEGRAPH SYSTEM Filed Dec. 18, 1940 5 Sheets-Sheet 2 fzzfw A TTORNE Y Nov. 17, 1942. c. J. FITCH PRINTING TELEGRAPH SYSTEM Filed Dec. 18, 1940 5 Sheets-Sheet 5 I In" nan.

3% Y m W mm m Nov. 17, 1942. c. J. FITCH 2,302,016

\ V v PRINTING TELEGRAPH SYSTEM Filed Dec. 18, 1940 5 Sheets-Sheet 4 FIGS.

A TTORNE Y Nov. 17, 1942. J, FITCH 2,302,016

PRINTING TELEGRAPH SYSTEM Filed Dec. 18, 1940 5 Shees-Sheet 5 f I17 m8 6 IN V? OR BY A T TORNE Y Patented Nov. 17, 1942 PRINTING TELEGRAPH SYSTEM Clyde J. Fitch, Endwell, N. Y., assignor to International Business Machines Corporation, New York, N. Y., a corporation of New York Application December 18, 15-10, Serial No. 370,675

12 Claims.

This invention relates to a printing telegraph system, and more particularly to such systems utilizing start-stop impulse distributing means.

In the present application, the code groups of impulses are generated electronically under control of an impulse distributing means, which is actuated, step-by-step, a predetermined number of times, during each signaling cycle. Oscillatory means are provided for effecting energizatiou of the actuating means of the impulse distributing means, and for controlling the conductivity of the electronic discharge devices employed for generating the impulses. Each transmitting and receiving station is provided with the impulse generating and distributing means just mentioned. At the transmitting station, upon each operation of the control switches, the oscillatory means and impulse distributing means are set into operation, for the duration of a signaling cycle, to generate code groups of impulses, during the cycle, in accordance with the settings of the control switches. The generated impulses are effective to control suitable signal transmitting means, the initiated signals of which, in turn are efie'ctive to set into operation, each signaling cycle, these oscillatory means and impulse distributing means at the receiving station for controlling the energization of the control magnets t. ereat in accordance with the character signals received,

Therefore, one of the objects of the present invention resides in the provision of periodically operable means, which can be called into operation at will, for controlling the operations of the distributing means.

Another object of the present invention resides in the provision of oscillatory control means, the

controlling effects of which are started and stopped at will to control the cyclic operations of the distributing means.

Another object of the present invention resides in the pro-vision of electronic oscillation generator means, the operations of which are started and stopped at will to control the cyclic stepping operations of the distributing means.

till another object of the present invention resides in the provision of an improved startstop s gnaling system, wherein the pair of actuating means of the distributor are energized alternately, at \periodic intervals, to produce the cyclic stepping operations of the distributor.

Still another object of the present invention resides in the provision of an improved startstop system, wherein the control circuits are distributor, and wherein the said circuits are rendered conductive, under control of an oscillatory control means which is capable of efiectmg the stepping operations of the distributor.

Other objects of the invention will be pointed out in the following description and claims-and illustrated in the accompanying drawings, which disclose, by way of example, the principle of the invention and the best mode, which has been contemplated, of applying that principle.

In the drawings:

Fig. 1 is a wiring diagram showing the circuit connections of the control elements of a preferred type of signaling system.

Fig. 2 is a right end view of the distributing means.

Fig. 3 is a left end view of the distributing means.

Fig. 4 is a sectional view taken along the lines 4 4 of Fig. 2.

Fig. 5 is a diagrammatic showing of the conducting rings and associated brushes of the distributing means.

Fig. 6 shows the wave forms of the oscillations generated by the start-stop oscillation generator.

Fig, 7 shows the wave forms of the variably timed signals generated by the system.

Fig. 8 is a plan view, shown partly in section, of one form of receiving teleprinter unit.

Fig. 9 is a sectional view showing the control clutch unit assembly.

Fig. 10 is an exploded view of the assembly shown in Fig. 9.

85 Fig. 10a is a detail view of the dog lifting lever of the clutch unit.

Fig. 11 is a wiring diagram of the circuit connections of a modification of the system shown in Fig. 1.

GENERAL DESCRIPTION tributing means, indicated generally by the reference character D, which brushes BlB6, 3?, BS, and BCIBC3 cooperate with a plurality of movable conducting rings ill-l3 which are actuated, step by step, by the control magnets made available successively, by a step by step 25 and 26.

The said contacts CI-CB, and CS, which are controlled permutatively, in accordance with the character selection operations, may be positioned directly by the permutation bars of a suitable transmitting unit, generally designated 65, such as described in U. S. Patents Nos. 1,214,515 and 2,161,564. or as is well known, may be positioned under control of suitable storage relays controlled by the devices referred to, in said patents, as for example, the storage relays described in the latter patent.

An oscillatory means, in the form of an electronic oscillator TI, is provided for controlling the alternate energization of the impulse distributing means actuating magnets 25 and 26, a predetermined number of times, each signaling cycle. An impulse generating device T3 is also provided, and arranged so that the conductivity of the triode sections thereof are controlled by the oscillatory means, in synchronism with the alternate energization of the control magnets 25 and 25. Thus, during the signaling cycle, when the impulse distributing means are released and actuated, upon operation of the control contacts, timed impulses are generated by the device T3, in accordance with the contact settings to control the signal generator 51 accordingly.

At the receiving station, impulse distributin means, oscillatory control means, and impulse generating means similar to those of the transmitting station are provided. The control magnets MI-MS of a suitable teleprinter means 80, such as described in U. S. Patents Nos. 1,128,422 and 2,165,247, are connected to the stationary brushes of the impulse distributing means, so that the said magnets are energized in different combinations corresponding to the character signals transmitted for effecting recording of the corresponding characters.

Before describing the specific operations of the system, the individual control units will be described flrst. The impulse distributing means will now be explained in detail.

Impulse distributing means Referring now to Figs. 2 to 5, the impulse distributing means is shown to comprise a plurality of conducting rings III, II, I2 and I3 which are fixedly mounted on a common shaft 9 suitably journaled in the supporting frame 2I. Centrally located on said shaft, and secured thereto, is an insulating spacer sleeve I4 to which in turn is secured a driving ratchet I5. Two spring urged actuating pawls I8 and II, which are adapted to cooperate with the teeth I8 of ratchet I5, are pivotally supported by the arms I9 and 20, respectively. The latter are rotatably mounted in the supporting frame 2I and urged by springs 22 to the normal positions shown. Attached to the said arms are the armatures 23 and 24 of actuating magnets 25 and 25, respectively, the latter being suitably mounted on the said supporting frame.

The spacing of the ratchet teeth I8 and the shapes thereof, and the strokes of the actuating pawls I6 and I! are such that alternate operation of the pawls is necessary to advance the ratchet I and shaft 9 step by step. For example, with the described elements in the home position as shown, the stroke of pawl I1 is insuilicient to advance the ratchet one step, therefore, it is understood, that energization of magnet 28 at this particular time is ineffective to ad vance the ratchet. However, energization of vancement of the ratchet one step, by attracting its armature 23, and effecting a partial clockwke rotation of arm I9, thereby urging the spring urged pawl I8 upwardly to engage one of the ratchet teeth. The advancement Just effected is suflicient to position one of the ratchet teeth in the path of the pawl II, whenever the related magnet 26 is energized. Until the latter magnet is energized, additional energizations of magnet 25 are ineffective to cause further advancement of the ratchet.

Attention should also be directed to the fact, that the ratchetteeth are shaped, so that when one of the magnets is energized to attract its related armature and effect partial rotation of the associated arm, the free end 21 of the said arm (at the end of its stroke) engages directly one of the teeth, thereby preventing overthrow of the ratchet and also locking the ratchet in the advanced position, as long as the said magnet is energized. The advantages of this arrangement will be understood as the description progresses. Each of the conducting rings I0 and II are secured on individual insulating collars 22. which collars are suitably secured to the shaft 2. One of the collars is hollowed at one end to receive the conducting ring I2 which ring, as well as ring I3, is secured to the shaft 9 in conductive relationship thereto. The conducting ring I2 is provided with four radially extending conducting segments I2a-I2d. Four equally spaced conducting segments Ina-Hid and Ila-I Id, which are integrally formed extensions of the conducting rings III and II, respectively, are provided to extend across the periphery of the related insulating collar as shown. Two groups of arcuately arranged conducting brushes, namely, BI, B2, B5, BP, BS, BC: and B2, B4, B6, BCI, BC2, are provided, and are supported by the insulating members 29, which in turn are suitably secured to the supporting frame 2|. The said brushes are fixed in different planes, and positioned so as to cooperate with the following sections of the conducting rings: brushes BI, B3, B5, and BP are positioned to extend in the path of the conducting segments Ila-Ild, brush BS is positioned to extend in the path of the conducting segments I2al2d, and brush B03 is positioned to engage continuously the conducting ring II; brushes B2, B4, B6 are positioned to extend in the path of the conducting segments I 0aIld, brush BC2 is positioned to engage continuously the conducting ring I0, and brush BCI is positioned to engage continuously the conducting ring I3.

As mentioned, upon alternate energization of the magnets 25 and 25, the said conducting rings and associated segments are advanced, from thehome P sition shown, to engage different ones of the associated conducting brushes. Each step, of the advanced rings and segments, is equivalent to a distance equal to half the distances separating the conducting tips of the equally spaced brushes BP, BI, B2, B5 and B2, B4, B5. The

I width of each of the conducting segments IIId-IOd and Ila-I Id is approximately equivalent to one half the distances separating the conducting tips of the latter mentioned brushes. The width of each of the conducting segments I2aI2d is approximately half of the width of one of the segments IIiaI0d or Ila-I Id. During eight successive steps of advancement of the said rings and segments. a complete cycle of operation of the associated brushes is effected. At magnet 25 is eflective, at this time, to cause adthe home position shown in Figs. 2 to 4, and diagrammatically indicated in Fig. 5, the brush BS engages the conducting segment l2b, brush BP engages the conducting segment lla. Since brushes BCl, BC2, and BC3 engage continuously the related conducting rings no reference will be made to these brushes during the following analyzation.

Upon completion of the first step, the contact between segment Ila and brush BP is broken, the contact between segment I21) and brush BS is broken, and contact is made between conducting segment llb and brush Bl. Upon the second step, the segment llb remains in contact with brush BI, and contact is made between segment lllb and brush B2; the third step, the contact between segment I lb and brush Bl is broken,

and contact is made between the said segment and brush B3, the segment llib remains in contact with brush B2; fourth step. the contact between segment lllb and brush B2 is broken, and contact is made between this segment and brush B4, the segment llb remains in contact with brush B3; fifth step, the contact between segment llb and brush B3 is broken, and c ntact is made between this segment and brush B5, the segment lllb remains in contact with brush B4: sixth step, the contact between segment lllb and brush B4 is broken, and contact is made between this segment and brush B8. the segment llb remains in contact with brush B5; seventh step. the contact between segment llb and brush B5 is broken. and contact is made between this segment and brush BP, the segment lllb remains in contact with brush B8; eighth step, the contact between segment llib and brush B6 is broken. contact is made between segment I and brush Bs, and the segment llb remains in contact with brush BP. The conducting rings and segments and the related brushes are now in a home position, similar to the one indicated in the figures.

The purpose of the described arrangement of brush connections, during one cycle of operation of the impulse distributing means, will be explained during the description of the circuit diagram in Fig. 1. The oscillatory means for controlling the operation of the said distributing means will now be described.

Oscillatory control means for impulse distributing means Referring now to Fig. 1, one type of oscillatory control means is shown to comprise the electron discharge device Tl, the anode of which is connected to one terminal of the primary winding 3| of transformer 32, the other terminal of which is connected by conductor 33 to the terminal 34 of a suitable power supply. The circuit connected to the grid 35 includes the resistor 36 and the secondary winding 31 of the transformer 32. The latter winding has an intermediate connection from point 38, by conductor 33, to terminal 40 of the said power supply. One terminal of the secondary winding is connected to resistor 4|, which in turn is connected, by conductor 42, to grids 43 and 44 of the electron discharge devices T2 and T3, respectively, which are of the twin triode type. An adjustable capacitance 45 and resistance 45 are connected in shunt relationship with the secondary winding 31. The cathode elements of devices Tl-T3 are connected, by conductor 41, to the terminal 48 of the power supply. The circuit connected to grid 49 of device T2, includes resistor 50, and is connected to resistors 38 and 43 at the point indicated 5l. The grid 52 of device T3 is connected, by conductor 53,

grid 35 of device Tl, and by conductor 54 to brush BCl. The anodes 55 and 55 of device T2 are connected to the actuating magnets 25 and 24 respectively, whereas, the anodes 51 and 53 of device T3 are connected to the brushes B02 and B03, respectively.

The circuit connections of the grid, cathode and anode elements oi device Tlv described are the conventional connections for causing the device TI to operate as an electron oscillator. The frequency of the generated oscillations can be determined by the adjustable capacitance 45, or if desired the magnetic gap of the transformer 32 may be made variable and adjustable, as indicated by the dotted arrow. An additional control circuit can be traced from terminal 34 of the power supply to conductor 59, normally closed contacts CS, resistance 50, brush BS, segment l2b, conducting rings l2 and I3, brush BCl, conductors 54 and 53 to grids 35 and 52 of .devices TI and T3, respectively, resistance 36, secondary winding 31, conductor 39, terminal 40 of the power supply, resistance 5| to terminal 48 of the power supply.

Whenever, the circuit Just traced is open, a biasing potential is impressed upon the said grids 35 and 52, due to the connection from the said grids to terminal 43 of the power supply. However, when the said traced circuit is connected to the grids 35 and 52, the voltage drop across resistance 35 is effective to neutralize the said biasing potential referred to, thereby placing the grids 35 and 52 at substantially zero biasing potential. The values of resistances 35 and Eli are determined and chosen, so that the said voltage drop across the former is suihcient to neutralize the biasing potential impressed by the circuit from terminal 40 of the power supply to grids 35 and 52. H

Under the last mentioned conditions, the device Tl is conductive, causing a constant current flow in the circuit fr am terminal 34 of the power 30. the related cathode element, conductor 41 to terminal? 'of the said power supply, to establish a predetermined and constant magnetic field around the transformer 32, thereby placing the circuits connected to the elements of device Tl in a non-oscillating condition.

Now, whenever the positive potential from terminal 34 is removed from the grid 35, for example, by opening the contacts CS, the neutralizing voltage drop across resistance 36 is removed, and the biasing potential impressed upon the said grid instantly is changed from zero to a negative value, thus rendering the device Tl nonconductiiee momentarily, and thereby cutting oil the flow of current through winding 3 l, and cansing the said magnetic field of transformer 32 to collapse. At this moment, a voltage is induced across winding 31 which tends to render the grid more negative with respect to its cathode, and causes the condenser 45 to be fully charged. Upon discharge of the said condenser the grid 35 becomes positive, with respect to the cathode, to render the device conductive momentarily to energize the winding 3|. In this well known manner, oscillations of a frequency determined by the chosen C and L values of the said capacitance and inductance are generated continuously, while the positive potential from terminal 34 is not impressed upon the grid 35. However, when the said positive potential is impressed thereupon, by closing the contacts CS for example, the generation of the oscillations is interrupted. In this manner, an oscillation generator is provided.

which can be started and stopped in the manner described, whereby the generated oscillations at the very start of its operations are virtually of maximum amplitude, and upon stopping the operationsof the generator, the generation of oscillations is stopped instantly. Fig. 6 shows the voltage wave shapes of the oscillations generated for a chosen cycle of operation, namely, four complete oscillator cycles.

It is noted, that the grids 43 and 49 of device T2 are connected in push-pull relationship to the terminals of winding 31, so that upon operation of the oscillation generator, the two triode sections of device T2 are rendered conductive alternately. In this manner, the actuating magnets 25 and 26 are energized alternately, in the order mentioned, to operate the impulse distributing means, by advancing the conducting rings and segments, step by step, for a chosen cycle of operations.

It should be mentioned, that although the grid 49 of device T2 is connected to the same terminal of winding 31 as grid 35 of device Tl, the potential impressed thereupon normally is negative with respect to its cathode, and not of zero value as in the case of grid 35. The reason for this being, that grid 49 is connected to point through a series resistor 50. Therefore, the triode section of device T2 controlled by grid 49 is not fully conductive, at the times when the positive potential from terminal 34 is impressed upon grid 35 of device TI, to render the latter fully conductive. In fact, at such times, a relatively small and negligible amount of current flow is present in the circuit connected to anode 56, so that normally very little current flow passes through the winding of magnet 26, and consequently a negligible amount of energy for the latter need be dissipated.

Transmitting circuit arrangement With reference now to the circuit connection shown in the upper half section of Fig. 1, the permutatively controlled contacts Cl-C6 of the transmittng unit 65 are shown connected to the individual brushes Bi--B6 of the impulse distributing means, and by a common conductor 66 are connected to the anode-cathode circuit of electron discharge device 61 and the brush BP. It is well known, that the said contacts can be controlled in a permutative manner in accordance with the selected character operations of the transmitting unit. It is equally well known. that the normally closed contacts CS are opened for each permutative setting or operation of the contacts Cl-C5.

It was explained in detail, that device Tl normally is conductive continuously, whenever the contacts CS are closed, and with the impulse distributing means positioned in the normal home position shown. Grid 52 of device T3 is connected in parallel to grid 35 of device Tl and consequently the triode section controlled thereby is fully conductive, when the contacts CS are closed and with the said distributing means in the said normal position.

For these conditions, a circuit can be traced from terminal 48 of the power supply to conductor 41, cathode and anode 58 of device T3, brush BC3, conducting ring II and segment II a, brush BP to the cathode element of device 61. The electron discharge device 61 is a twin triode type connected as an oscillator, the frequency of which is determined by the C and L values of the capacitance 68 and transformer 69. The center tap of the primary winding of said transformer is connected to terminal 34 of the power supply, and the terminals of said winding are connected to the anode elements of device 61. Each anode is coupled to the opposite grid by means of condensers 10 and 1|, and the grid elements are connected to cathode through the grid leak resistors 12 and 13.

From the foregoing description, it should be evident and adequate for the present purpose to state, that, when sufllcient potential is applied between the center tap of the primary winding of transformer 69 and the cathode of device 61, oscillationsofapredetermined frequency are generated, and that when this potential is removed, the generation of said oscillations is interrupted. The generated carrier oscillations are impressed upon the signal line terminals 14 through the volume control device 15. It has been found desirable, particularly when utilizing the system for telephone line transmission purposes, that the signal carrier frequency should be set for approximately 1800 cycles, and'depending upon the desired speed of operation, the base frequency of the oscillations generated by device Tl can be approximately from 20 to 50 cycles.

Now, so long as the triode section of device T3 controlled by grid 52 is conductive, suiilcient potential is impressed upon the described input circuit of device 61 to render the latter operative to generate the signal oscillations, which in turn, are impressed upon a suitable transmission medium. This signal is indicated at A in Fig. 7, and corresponds to the continuous line signal, or current condition, impressed upon the transmission medium, during the absence of character signals, in the present day start-stop systems.

From the foregoing description, it is understood that, upon each operation of the transmitting unit to position the contacts Cl-CS, contacts CS are opened, momentarily, to render the oscillator device Tl effective to generate oscillations, and effect energization of the magnets 25 and 26, alternately, to cause the conducting rings and segments to sweep across the associated brushes. It was also mentioned that eight steps of the said conducting rings represent a complete signaling cycle, so that the brush BS, at the end of each series of eight steps, engages one of the conducting segments l2a,l2d, and thereby impresses the neutralizing potential upon the input circuit of device Tl, whereupon further generation of oscillations is interrupted (assuming of course, that during the signaling cycle the contacts CS are closed which is the normal practice). It should be stated, at this time, that, it is assum d, the sections indicated I, 3, 5 and 1 of the oscillations in Fig. 6 are effective to render the grid 43 positive, and cause the magnet 25 to be energized during the signaling cycle, and that sections 2, 4, 6 and 8 are efiective to render the grid 49 positive to cause the magnet 26 to be energized, during the said cycle.

In order to complete the description of the transmitting circuit arrangement, it will be explained briefly, how the permutation signals are generated, therefore, assume that the transmitting unit 65 is operated to close the contacts CI, C4 and C5 during the signaling cycle, and that contacts CS are opened momentarily. Normally, the continuous signal indicated at A in Fig. '7 is impressed upon the transmission med um. Upon opening of the contacts CS, grids 43 and 49 are rendered positive, alternately, due to the operation of device Tl as explained. Grids M and 82, similarly are rendered positive, in synchronism with grids 48 and 49, respectively. Therefore, during the first halt cycle of oscillation of device Tl, the potential impressed on grid 52 drops to below a normal plate current cut-oi! value, and the potential impressed on grid 85 is positive to render the related triode section conductive. Thus, during the said first half cycle of operation, when the conducting rings are advanced one step, the oscillator device 81 is rendered inoperative, and consequently no signal oscillations are impressed upon the line terminals 18. This condition is indicated at B in Fig. 7.

Since current flow, in the circuit connected to anode 88, is instantly cut-oi! when contacts CS are opened, during the first half cycle of operation when the conducting rings are advanced one step, there is no current flow through brush 3?, when this. contact is broken. Similarly, when contact is made with brush Bl, even though contact Cl is closed, no current flows through the circuit associated therewith, at this time in the cycle.

During the second half cycle of operation of device Ti, brush Bl remains in contact with its conducting segment, and, since grid 52 is now positive and grid 44 negative with respect to cathode, current iiows from the terminal 34 of the power supply to anode-cathode circuit of device 81, conductor 65, contacts Ci, brush Bi, one of the segments Ila-I Id, conducting ring I i, brush BC3, anode 58 and related cathode, to conductor l1 and terminal 58 of the said power supply, thereby rendering the device 61 conductive, during this said half cycle, which is indicated at C in Fig. 7, to transmit the first signal of the combination. Also, during this half cycle, contact is made with brush B2, however, since contacts C2 are open, and since grid 44 is negative, at this time, the circuit connected to anode 51 is maintained non-conducting.

During the third cycle of operation of device Tl, grid 44 becomes positive and grid 52 negative, thus rendering the oscillator device 61 nonconductive. Since contacts C2 are open, no signaling circuit can be completed through brush B2. This condition is indicated at D in Fig. 7.

During the fourth cycle of operation of device Ti, contact is broken with brush B2 and made with brush B4, but no current passes through the latter, even though contacts C4 are closed, due to the negative grid 44, and with contacts C3 open, a circuit cannot completed through brush B3. Thus, no signal is impressed on the transmission medium, at this time, in the signaling cycle, as indicated at E in Fig. '7.

During the fifth cycle of operation of device Ti, brush B4 remains in contact with conducting ring ii, and since contacts C4 are closed, and the grid 44 is positive, at this time, a circuit is completed to render the oscillator device 61 conductive, as indicated at F in Fig. 7. Contact is broken with brush B3 and made with B5, however, current cannot flow through the latter due to grid 52 being negative.

During the sixth cycle of operation of device Ti, current is permitted to flow through brush B5, due to the positive grid 52, thereby rendering the oscillator device 61 conductive, at this time, as indicated at G in Fig. 7.

During the seventh cycle of operation of device Tl, grid 52 becomes negative to render device 61 non-conductive. Contact is made with brush BP, but, due to the condition of grid 52, no current can flow through this circuit at this time. Grid 44 is positive. but no current can flow through brush B8, since contactsC8 are open. This condition is indicated at H in Fig. 7.

During the eighth cycle of operation oi device Ti, contest is made with brush B8 to render the oscillator device Tl conductive continuously. Current also flows through the brush BP, since grid 52 is now positive with respect to cathode, thereby rendering the device 81 conductive to generate the continuous signal condition, which is impressed on the transmission medium, during the absence of character signals. This condition is indicated at A in Fig. 7. In this manner, the permutation signals are initiated and transmitted, during a signaling cycle, by means of the novel distributing means.

Receiving circuit arrangement Referring again to Fig. 1, the receiving circuit connections, shown in the lower halt section 0! the figure, are similar to those of the transmitting circuit, just described. The impulse distributing means, at both transmitting and receiving stations, are identical in structure and operation, as well as, the control circuits associated with the devices Tl, T2 and T8. Similar reference characters are used to denote like elements and circuits. For this reason, it is not deemed necessary to repeat the detailed description of the operation oi these like elements and circuits.

Control magnets Mi-MS of a suitable printing telegraph receiving unit, indicated generally by the reference character 80, are connected to the individual brushes BiB8 of the impulse distributing means. The said magnets are also connected, by a common conductor 8i, to the cathode-anode circuit of electron discharge device 82, and by means of conductor 83 are connected to brush BS through the resistor 68. It is well known, how the control magnets MIM8 are eflective to control the operation of permutation members, for effecting the selection of the character type elements, in accordance with the character code signals received.

In the present system, an additional control magnet MP, for controlling the printing operations, is employed. Thespeciflc control functions of this magnet will be described later. It will suffice to say, for the present, that, this control magnet is energized upon receipt oi the permutation code signals to eiiect the printing operations. One terminal of the said magnet is connected to brush BP, and the other terminal is connected by conductor 86 to terminal 36 01 the power supply.

The terminal apparatus for receiving the signals is shown to comprise a full wave rectifier discharge device 80, the separate anodes of which are connected to the terminals oi the seconaary winding of the transrormer 86, the primary winding 01' which is connected to the terminals 81, and shunted by a signal amplitude limiting resistor 88. A center tap connection is provided from the secondary winding to one terminal of resistor 89, the other terminal of which is connected'to the cathode of device 85, and grid element of device 82. Biasing potential is supplied by battery 98, and impressed upon the grid of device 82 to render the latter non-conductive, when no signals are received.

Assume now, that the continuous signal represented by A in Fig. 7 is impressed upon the terminals 81 and device 85. The signal oscillaimpresses a continuous D. C. rectified voltage across resistor 89, which D. C. potential is of such value, as to overcome the biasing potential impressed-upon the grid of device 82, thereby rendering the latter conductive. A circuit can then be traced from terminal 34 of the power-supply, anode-cathode of device 82, conductor 8|, resistor 88, brush BS, conducting segment l2b and related conducting rings I2 and I3, brush BCI, conductor 84, grids 85 and 52 of devices TI and T8, respectively, resistor 38, winding 81, conductor 88, resistor H to terminal 48 of the said power supply. Thus, as described hereinabove in connection with the transmitting circuit, the biasing potentials impressed on said grids are overcome or neutralized, so that the related triode sections are rendered conductive continuously. Another control circuit can be traced from terminal 34 of the power supply to conductor 84, magnet MP, brush BP, conducting segment lid and ring II, anode 58 and related cathode, to conductor 41 and terminal 48 of the said power supply,

'thus energizing the said magnet, whenever the impulse distributing means is in the home position indicated, and a signal is impressed upon the said signal receiving means.

In order to Simplify the description to follow, it will be assumed, that the described signal combination initiated by the operation of contacts CI, C4 and C5 is impressed upon the signal receiving means. The first signal of the combination is the start signal condition, represented at B in Fig. 7, by having no signal oscillations impressed upon the receiving means. As mentioned, for this condition, no potential is impressed across resistor 89, and consequently device 82 is rendered non-conductive, thereby removing the neutralizing potential impressed upon grids and 52. Device TI now is conditioned to function as an oscillator, and efiective to control the alternate operations of the actuating magnets 25 and 28 of the impulse distributing means. The described circuit connected to anode 58 also becomes non-conducting, due to the said conditioning of grid 52, thereby effecting the deenergization of the print magnet MP. The frequency of the oscillatory means at the receiver is adjusted, so as to approximately be the same as that of the transmitter, and under these conditions, it has been found, that the two impulse distributing means will operate in synchronism.

During the second stepping operation of the distributing means, the first signal of the combination is received to establish the following circuit: From terminal 34 of the power supply to the anode-cathode elements of device 82, conductor 8i, control magnet MI, brush BI, conducting segment IIb and ring II, brush B08, anode 58 and related cathode, to conductor 41 and terminal 48 of the said power supply, energizing said magnet.

During the third and fourth stepping operations of the distributing means, no circuits are established, due to the absence of control signals. But, during the fifth stepping operation, a circuit is established from terminal 34 of the power supply to anode-cathode elements of device 82, conductor 8|, magnet M4, brush B4, conducting segment I8b and ring I8, brush BC2, anode 51 and related cathode to conductor 41 and terminal 48 of the power supply, energizing said magnet. During the sixth stepping operation, a circuit is established to magnet M5, through brushes B5 and BC3 to anode 28, to effect energization of this magnet. During the seventh stepping operation no signals are received, and during the eighth and last stepping operation in this signaling cycle, the conducting rings are positioned to a home position to effect energization of the print magnet MP, through the circuit traced hereinabove, thereby completing the cycle of operations.

Upon energization of the print magnet, the

character is printed in accordance with the selection effected by the energization of the said control magnets. One embodiment of a receiving teleprinter, utilizing a print magnet as referred to, will now b described.

' Receiving teleprinter unit In certain applications of the system just described, the oscillator devices TI may be adjusted to operate at a relatively low frequency rate, and consequently transmit and receive the timed character signals, at too slow a rate, to operate satisfactorily the printer unit, referred to in U. S. Patent No. 2,165,247. To overcome this condition, certain modifications of the structural details of this'unit have been suggested, whereby the received signals are stored by the control clutch units associated with the permutation bars. Upon receipt of the signals of each combination, the print control magnet is energized to effect the selection of the character type elements and recording of the characters. With reference now to Figs. 8-10, the changes referred to will be described.

The rotatable permutation bars I88, of which six are shown, are provided with individual clutch units, comprising an annular member I8I, secured to a related bar, which member is shaped to receive a movable dog I82. The said dog is provided with a single tooth I83 normally held out of engagement with the associated ratchet wheel I84. 7 A pivoted dog lift lever I85 is provided to control the positioning of the dog, and normally is engaged by clutch stop arm I88 secured to armature I 81 of magnet MI, which is one of the control magnets MI-MS referred to.

It is described in detail in Patent No. 2,165,247, how the main drive gears, one of which is indicated by the reference character I 88, are driven to effect continuous rotation of the individual gears I88, and the related stud shafts II8, which shafts in turn cause the rotation of the associated ratchet wheels I84.

Referring now to the dog lift lever I85, it is noted, that two individual stops III and H2 are formed thereon, and arranged one below the other in offset positions with respect to each other. Th upright section of the cooperating stop arm I88 is provided with a U-shaped slot H3 in one side thereof, so that the uppermost section II4 of the stop arm can engage the upper stop I I I of the dog lift lever I 85, whenever the armature I81 is in 9. released position as shown. In this manner, the dog I82 is held in a position, so that its tooth is prevented from engaging the associated rotating Wheel, and consequently, preventing the associated permutation bar from being rotated or operated.

Now, upon energization of the related control magnet, for example magnet MI, the stop arm I88, as viewed in Fig. 10, is partially rotated in a clockwise direction, thereby resulting in the disengagement of the stop section H4 and upper stop III of the dog lift lever, and the engagement of the said stop section with the lower stop II 2 of the dog lift lever. This resultant action is quite similar to actions of well known escapement mechanisms. The escapement action is positive, due to the fact, that the dog I02 is constantly urged, by spring means (not shownin the present application but described in detail in the Patent 2,165,247) in the direction of the ratchet wheel. The stop arm I is retained in the shifted position, by means of a frictional lock, comprising the spring urged ball IIB engaging the uppermost notch I I8 formed in the side opposite the one with the slot N3 of the upright section of stop arm.

It is evident now, that, as the control signals are impressed upon the individual magnets MI--M6 to effect energization thereof, the said signals are eflective to cause the controlled clutch units to be shifted as described, and store the corresponding signals until the clutch units are released completely toefiect rotation of the related permutation bars.

The release of each clutch unit is under control of the print m agnets MP, only one of which is shown, however 'it will be understood, that one print magnet isprovided for each group of three control magnets included in the printer unit. The said print magnet is mounted below the related group of control magnets, and is provided with a pivoted armature II1 to which an extension arm I I8 is secured, there being an extension arm for each related control magnet. extension arms are adapted to engage the displaced or shifted stop arms I06, upon energization of the print magnet MP, to restore the said arms V to the normal position shown Upon restoration of a stop arm I06, the uppermost section Ill thereof is disengaged from the lower stop II2, thereby releasing the dog lift lever I and permitting the tooth of the dog I02 to engage the related ratchet wheel. This operation results in the rotation of the associated permutation bar. Upon completion of a revolution of the bar and clutch unit, the upper stop III of the dog lift lever again engages the uppermost section Ill of the restored stop arm, to effect disengagement of the said dog tooth and ratchet. Thus, it is seen, that all the shifted clutch units are released, upon energization of the associated print magnet MP, to effect rotation of the related permutation bars, after the different signals of the permutation combinations are received and stored.

Each permutation bar I00 is provided with a plurality of diametrically opposed slots I I0, which bars upon rotation, in permutative groups, present certain of the said slots under the control levers I20, so that one control lever is selected and permitted to drop in the channel provided by those slots which are in alignment. The selected control lever is then effective to operate its attached key bar lever (not shown), to cause the character to be recorded, in accordance with the code signals impressed upon the control magnets MIM6.

Modification The said oscillatory control means will now be described with reference to Fig. 11.

In this figure, the control contacts CI-.C6 are shown connected to the brushes BI-BB of the of device TII are connected as an oscillator of the multivibrator type. The anode elements I2I and I22 are connected to,resistors I23 and I24, respectively, which in turn are connected by the conductor I25 to the positive terminal'l20 of the power supply. The grid elements I21 and I28 are connected to the resistors I29 and I30, re-

spectively, which in turn are connected to the grid biasing resistors I3I and I32, A source of grid bias potential I33 is connected, by means of a variable control device I34, to the resistors I3I and I32 to impress suitable potentials upon the grids I21 and I20 to render the related triode sections normally non-conductive. I35 and I36 are connected from the anodes I2I and I22 to the opposite grids I28 and I21. The grids I21 and- I28 are connected directly to the grids I31 and I38 of device TI2, and grids I30 and I40 of device TI3, respectively. The anodes HI and I42 of device TI2 are connected to magnets 25 and 26, and anodes I43 and I04 are connected to brushes BC3 and BC2, respectively.

Now, so long as contacts CS are closed, a circuit can be traced from terminal I20 of the power supply to the primary winding of transformer 69, anode-cathode circuit of device 01, conductor I20, contacts CS, brush BS, segment I2b, conducting rings I2 and I3, brush BCI, resistor I3I, battery I33, conductor I05 to terminal I46 of the power supply. The current flow in this circuit is of relatively low value, however, suflicient to effect neutralization of the biasing potential impressed upon grids I21, I31, and I39 of devices TI I, TI2 and TI 3, respectively, thereby rendering the related triode sections of the said devices conductive. Due to this condition, device TI I is prevented from functioning a an oscillator.

Another circuit can be traced from the power supply terminal I26, device 61, to brush BP, segment IIa, conducting ring II, brush BC3, anode I43 and related cathode to terminal I40 of the said power supply, thereby permitting the device 61 to oscillate and impress the continuous signal upon the output terminals of the transformer 69.

Now, upon operation of the control contacts CI-CG, in different combinations, the contacts CS are opened, as mentioned before, for each operation, to remove the said neutralizing potential from the grids I21, I31, and I39 of devices TI I-TI3.' Device TII immediately starts to function as an oscillator, the triode sections of device TI2 are rendered conductive, alternately, to energize magnets 25 and 26, to render the impulse distributing means D operative for the duration of a signaling cycle.

Removal of the positive potential from grid I30 renders the related triode section of device TI3 non-conductive, thus, in turn, rendering the oscillator device 61 inoperative. It is remembered,

in this manner, the start signal is impressed upon the output terminals of the system.

Now, as the impulse distributing means is ad- Condensers vanced, step by step, to complete the circuits successively from its brushes to the closed contacts of the group Cl-Cl, and, as the triode sections of the impulse generating device Tl! are operated alternately, the conductivity of the device 01 is controlled, similarly as described in detail hereinabove, to initiate variably timed signals to represent the selected characters, which signals are impressed upon the output terminals of transformer 59. Upon completion of each signaling cycle, the neutralizing potential again .is impressed upon the said ds I21, I31 and I, through the closed contats C8, to restore the system to the normal non-signaling condition described, whereby the continuous oscillations of device 6'! are impressed upon the said output terminals, thus preparing the said system for the next signaling cycle.

The impulse distributing means, and modified receiving teleprinter unit are claimed in separate copending applications illed Dec. 18, 1940, having Serial Nos. 370,676 and 370,677, respectively.

While there has been shown and described and pointed out the fundamental novel features of the invention as applied to a single modification it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art, without departing from the spirit of the invention. It is the intention, therefore, to be limited only as indicated by the scope of the following claims.

What is claimed is:

l. A system of the character described comprising, in combination, normally inoperative impulse distributing means including a plurality of conducting segments, and brushes arranged to engage said segments in predetermined order, a pair of electromagnetic means for producing, segments and brushes, a plurality of control circuits connected to said distributing means, means whereby the control circuits are made available successively through said segments and brushes, said last mentioned means including an oscillation generator having means controlled by the distributing means for normally maintainand a plurality or of electron dischargedevices, each group responsive to the oscillations and controlled thereby in push-pull relationship, means whereby one of said groups of devices is effective to energize alternately the electromagnetic actuating means thereby effecting operation of the impulse distributing means in a step by step manner, and means whereby another of said group of devices is effective to control the conductivity of the-said control circuits,

ribed including a cyclically operable sta -stop distributor comprising a plurality of conducting segments, and brushes arranged to engage said segments in predetermined order during each cycle, a pair of electromagnetic means for producing, step by step, relative movement between ing the said generator in a non-oscillatory condition, means for conditioning the said controlled means for causing the generator to be effective to produce oscillations, and a plurality of pairs of electron discharge paths, each pair responsive to the oscillations and controlled thereby in synchronous and push-pull relationship, means whereby one of said pairs of paths are effective to energize alternately the said pair of electromagnetic means thereby producing a step by step relative movement between said segments and brushes for making the control circuits available in succession, and means whereby another of said pairs of paths are eiIective to control the conductivity of the said control circuits in the order of their availability.

2. A system of the character described comprising, in combination, normally inoperative impulse distributing means, a pair of electromagnetic actuating means which, upon alternate energization thereof, are capable of operating the said distributing means step by step, a plurality of control circuits connected to said distributing means, an oscillation generator having means controlled by the distributing means for normally maintaining the said generator in a non-oscillatory condition, means for conditioning the said controlled means for causing the generator to be effective to produce oscillations,

said segments and brushes, a plurality of control circuits and means whereby the control circuits are made available successively through said segments and brushes, said last mentioned means including an oscillation generator, means controlled by one of said circuits for maintaining the generator in a non-oscillatory condition, means for rendering both the last mentioned circuit and means effective at the end oi each cycle, and additional means for disabling them, upon operation of the distributor and during the entire cycle of operation thereof, so as to be inefiective, means for conditioning the said controlled means, between cycles, for causing the generator to be effective to produce oscillations, a plurality of pairs of electron discharge means, each pair responsive to the positive and negative potentials of the said oscillations and rendered conductive at alternate intervals, means whereby one of said pairs of means are eflective to energize at alternate intervals the said pair of electromagnetic means thereby producing a step by step relative movement between said segments and brushes for making the control circuits available in succession, and means whereby another of said pairs oi means are eil'ective to control the conductivity, at successive intervals, 01' the said control circuits in the order of their availability.

4. A system of the character described including a cyclically operable start-stop distributor comprising a plurality of conducting segments, and brushes arranged to engage said segments in predetermined order during each cycle, a pair of electromagnetic means for producing, step by step, relative movement between said segments and brushes, an oscillation generator having means controlled by the distributor and made effective thereby at the end of each cycle for maintaining the generator in a non-oscillatory condition and which means is adapted to be disabled by the distributor during each cycle so as to be ineffective, means for conditioning the said controlled means, between cycles, for causing the generator to be effective to produce oscillations, and means responsive to the positive and negative potentials of said oscillations for energizing, at alternate intervals, the said pair of electromagnetic means thereby eflfecting operation 01' the distributor for a complete cycle.

5. A system of the character described including a cyclically operable start-stop distributor comprising a plurality of conducting segments, and brushes arranged to engage said segments in predetermined order during each cycle, actuating means capable of producing relative movement between said segments and brushes, an oscillation generator having means controlled by the distributor to be effective at the end of each cycle for maintaining the said generator ina non-oscillatory condition and disabled during each cycle so as to be ineffective, means for conditioning the said controlled means,. between cycles, for causing the generator to be efiective to produce oscillations, and means responsive to the oscillations for effecting energization of the said actuating means thereby operating the distributor for a complete cycle.

6. A system of the character described including a cyclically operable start-stop distributor means, actuating means for eflecting, step by step, cyclic operation of the distributor means, an oscillation generator capable of controlling the energization of the said actuating means, means for normally rendering the saidgenerator ineffective, between cycles, to energize the actuating means, means under control of the distributor for disabling the last mentioned means during the cyclic operations of the distributor, and means for nullifying the controlling effects of the said last mentioned means whereby the oscillation generator is eflective to energize the actuating means to start and maintain the cyclic operations of the distributor means.

7. A cyclically operable signaling system comprising, in combination, impulse distributing means, means for controlling the operation of the said distributing means, oscillatory control means having means for normally maintaining the oscillatory control means in a non oscillatory condition, means for rendering ,th' last mentioned means ineffective, duringsignaling cycles, thereby restoring the oscillatory control means to an oscillatory condition, and means controlled by the oscillatory control means for rendering the said controlling means effective to operate the impulse distributing means during the said signaling cycle.

8. A cyclically operable signaling system comprising, in combination, impulse distributing means, electromagnetic means for controlling the operation of the said distributing means, oscillatory control means, means under control of the last mentioned means capable of energizing, at periodic times, the said electromagnetic means, means for rendering'the oscillatory control means effective, during signaling cycles, for causing the electromagnetic means to be energized periodically, and means under control of the impulse distributing means for rendering the oscillatory control means incapable of exercising any control over the said electromagnetic means and impulse distributing means at all times exclusive of the said signaling cycles.

9. A signaling system comprising, in combination, impulse distributing means, means for controlling the operation of the said distributing means, oscillatory control means, means for rendering the oscillatory means effective. at predetermined times, for causing the said controlling means to operate the impulse distributing means, and means under control of the impulse distributing means for rendering the oscillatory control means incapable of exercising any control over the said controlling means and impulse distributing means at other than the said predetermined times.

10. A cyclically operable signaling system comprising, in combination, distributor means and actuating means therefor, an oscillation generator, means for rendering the latter effective to exercise control over the actuating means for a signaling cycle thereby rendering the said distributor means operative during the said signaling cycle, and means for preventing the oscillation generator to exercise further control operations over the said actuating means including means for rendering the last mentioned means eflfective upon completion of the signaling cycle.

11. A cyclically operable signaling system comprising, in combination, start-stop distributor means, a pair of alternately operable actuating means therefor, oscillatory means for alternately controlling, at periodic intervals, the energization of said actuating means during each signaling cycle, and means for starting and stopping the oscillatory means thereby eflecting cyclic operations of the distributor means,

12. A cyclically operable signaling system comprising, in combination, start-stop distributor means and actuating control means therefor, a source of periodic impulses, means for impressing said impulses upon the said control means for electrically energizing, at periodic intervals, the actuating control means during each signaling cycle, and means for starting and stopping the controlling eflfects of the said energizing means thereby effecting cyclic operations of the distributor means.

CLYDE J. FITCH.

I CERTIFICATE OF CORRECTION. Y Patent No. 2,502,016; Kovember 17, 19112.

cm J. FITCH.

It is hereby certified that error appears in th o pr1nted specification of the above numbered patent requiring correction as follows: Page 8, first column,'l1ne 1 .O, claim 1, before "cements" insert "step bi 'atep, relative movement between said--; and that the said Letters Patent should be read with this correction therein that the some may conform to the record of 'the case inflme Patent Office;

si ns; and sealed this 9th da of February, A. 1). 1915.

Henry Van Aradale, (Seal) .,ct1ng Commissioner of Patents.

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