US2220889A - Communication system - Google Patents

Description

Nov. l2, 1940. l. E. CQLE COMMUNICATION SYSTEM Filed Sept. 23, 1939 7 Sheets-Sheet l /N VEA/TOR l. E COLE L E. CQLE- GOMMUNICATI'ON SYSTEM Nav. 12, 1940.`

Filed sept. 23, 1939 *I sheets-sheet 2 Qukk A TroRA/EV Nov. 12?.,4 1940. `l. E. COLE `coMMuNIcATIoN SYSTEM Filed sept. 2:5, 1959 7 sheets-sheet 4 A TTORNE Y Nav. l2, 1940. 1 E CQLE 2,220,889

COMMUNICATION SYSTEM v Filed sept. 23. 4w59 7 sheets-sheet 5 /N VEA/71M5 y l. E'. C OLE Nov. 12,1940. l. E. COLE COMMUNICATION SYSTEM Filed Sept. 23, 1939 '7 Sheets-Sheetl 6 INVENTOQ By -1.5601.

A TTORNE Y Nov. 12,` 1940.A L E, COLE COMMUNICATION SYSTEM Filed sept M' 25, 1959 7 Sheets-Sheet '7 ATTQRA/Ev v Patented Nov. 12, 1940 UNITED STATES PATENT OFFICE azzasss comlmNlcA'lToN SYSTEM Application September 23, 1989, serial No. 296,248

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This invention relates to communication systems and particularly to combined telephone and telegraph systems in which the telegraph signals are interpolated in a telephone conversation. This invention is an improvement over the system shown in application Serial No. 219,964 led July 19, 1938.

It is an object of the invention to operate facsimile printing telegraph devices over the telelo graph channel of an interpolated telephone and telegraph system.I

A feature of the invention is a means to move the -tape or other surface on which the composite character is being formed backward when l printing is stopped with a character only paro tially printed. By such means the partial inscription of this Same character will be retraced and then completed with the result that mutilation will be avoided.

As in the Cole-Melhose system referred to the signals representing any one character are recorded and transmitted. If the voice currents take command of the transmission channel the telegraph transmission is interrupted and the character signals are stored for retransmission at the next opportunity. 1f the voice currents take command of the transmission channel within a very short distance from the end of the transmission of the signals of a character, then the voice current responsive means are delayed in their action so as to allow the completion ofy that particular character.

In the specific embodiment of this invention used for purposes of illustration, the character codes are recorded and then translated into what may be termed facsimile code. By use of synchronously operating motors controlled, for example, as shown in Patent No. 2,207,748, 'to L. A. Meacham dated July 16, 1940, a composite printer at the receiving end is actuated by impulses transmitted from the sending end. When the telegraphic transmission of such impulses is interrupted, a clutch is disengaged from the continuously running synchronous motor and the tape or recording surface is moved backwardly so that a character only partially inscribed may be retraced and completed at the next opportunity. While the clutch is thrown out the composite printer is idle and an escapement mechanlsm is rendered inoperative. At this time a resilient connection between the tape moving means and the escapement mechanism'brings the tape back to the point where the inscription of a character is started .and specifically to the point where the partially inscribed character was started. 'When transmission iSresumed it will be started again at the beginning of the code theretofore partially transmitted and the partially inscribed character will be retraced and @u completed unless transmission is again interruptedV before `the complete train of character code signals has been transmitted.

The drawings consist of seven sheets containlng circuit diagrams, schematic representations.

a timing chart and perspective skeleton drawings. 5

Figs. 1, 3 and 4, when placed together as indicatedin Fig. `2, form a circuit diagram of the system with the facsimile transmitter in Fig. 3 shown schematically and the facsimile printer in Fig. 4 also shown schematically; lo

Fig. 5. is a broken side view of certain mechanical details of the facsimile printer Fig. 6 is a perspective Skeletonized view of these same details;

Fig. '1 is a timing chart to explain the sequence 15 of operations both at the transmitter and at the receiver; i l

` Fig. 8 is a perspective skeletonized drawing of the facsimile transmitter; and

Fig. 9 is a perspective skeletonized drawing of 9 the facsimile printer.

In general the operation of the system may be explained with the help of Figs. 1, 3 and 4. A speech path I leads to a hybrid coil 2 from which a path 3 for outgoing speech leads to a vogad 4. 25 The outgoing speech then passes through a transmitting suppressor 5 and by means of an amplier detector operates a chain of relays 1 here labeled Voice operated switching circuit. This voice operated switching circuit controls a trans- 30 mitting singing suppressor 9 so that the outgoing 'speech can pass from the transmitting suppressor 5 `through the delay` and amplier 8 and the transmitting Singing suppressor 9 to the hybrid coil I0. From the hybrid coil III the speech reaches another hybrid coil II and thence goes through the radio transmitter I2 to lan antenna I3. Through radio transmission the speech will be received at some distant point and for purpose of explanation it will be assumed that the 40 distant point has a receiving circuit similar in all respects to the lower part of Fig. 1. The radio frequency modulated speech, therefore, enters antenna I4, passes through a radio receiver I5 and thence demodulated speech passes through 45 the voice frequency repeater I6 to a hybrid coil I'I. From the hybrid coil `I'I the speech goes into hybrid coil I8, thence through the receiving singing suppressor I9, the receiving repeater 20, a low pass filter 2I and a path 22 to a hybrid coil, 50 such as 2, whence it goes to the receiving subscriber over a line such as I.

The voice operated switching circuit l controls a control tone, enabler 23 through the contact and armature of relay 24 so that control tone 65 from a source 25 is passed through the control tone compressor 26 and thecontrol tone filter 21 to `the hybrid coil II and thus accompanies Speech. The voice operated switching circuit 1 also controls a switching point leading from the o0 iss open this circuit during the periods that speech is going out from line I to antenna I3. During this time the voice operated switching circuit 1 also controls the telegraph control circuit shown* in Fig. 3 by operating relay 28 in order to stop the action of the telegraph transmitting circuit during the time the voice is being transmitted from line I out over antenna I3 by the usual modulation means.

At the receiving end the control tone with the usual modulation of the carrier frequency coming in over antenna I4 is demodulated in radio receiver I5 and passes through the hybrid coil I1 and thence through a telegraph band elimination filter and into a control tone amplifier and filter 3I. Through the detector 32 the receiving switching circuit 28 is operated and this circuit performs several functions as follows: First, the receiving switching circuit 28 controls a normally open circuit between the telegraph band elimina ltion filter 30 and the detector 32, this path including a speech amplier 33 so that when control tone is rst received the switching" circuit 28 will be operated thereby and theny held operated thereafter by speech currents owing through the amplifier 33. When the control tone is first transmitted it goes out into antenna I3 at high volume but after an interval determined by the delay and amplifier 8, the speech operates a control tone compressor 28 to reduce the volume of the control tone to avoid overloading the radio transmitter I2 by the combination of control tone and speech. This,` of course, operates to ad- '.vantage at the receiving end by giving an impulse of great strength through the control tone amplifier and filter 3I to operate the receiving switchingcir'cuit 28 before the path to the speech amplifier. 33 is closed.

The receiving-switching circuit 28 also controls the receivingjsinging suppressor I9 to open up the speech path.j '.I'he receiving switching circuit 28 also controls a normally closed path between the band-pass filter 34 and the telegrad 35 so that While speech is being received the telegrad 35 will be disabled. At the"'same time the receiving switching circuit 28 controls the switching relay 36 for controlling the operation of the facsimile printer of Fig. 4.

During the pauses in the speech, either when the subscriber at the distant end is talking linto channel I or during the time when the subscriber on channel I pauses during his talk out over the antenna I3, a telegraph apparatus, shown in Fig.

3, is in operation. This comprises, in general, a

tape controlled facsimile transmitter similar to that described in Patent 2,000,083, granted May 7, 1935, to Kleinschmidt, and which will be more fully described hereinafter. This tape transmitter operates a telegraph transmitting line relay 31 which, in 'turn, controls the telegraph signal converter 38. This signal converter is a circuit controlling device disclosed in Patent No. 1,749,851 to H. C. Silent, March 11, 1930. When relay 31 is at its marking contact 6, the telegraph signal converter 38 is in such a condition that alternating current coming from the telegraph signal oscillator 39 passes freely into hybrid coil I0 for transmission out over the antenna I3. When relay 31 has its armature driven to its spacing contact, then the telegraph signal converter. 38 blocks off the telegraph signal current and no current will therefore get into hybrid coil I0.

At the distant end these telegraph signalsin radio receiver I5 and thence through repeater I6,

whence they pass through the hybrid coils I 1 and I8 to the band-pass lter, 3'4. Thereafter the signals enter the telegrad 35 and are converted from varying strength alternating current signals to uniform strength direct current signals of approximately the saine strength at which they were received over antenna I4. For a. complete description of the telegrad reference is made to application Serial No. 283,368 filed July 8, 1939, by Barney et al. These direct current signals then pass through the switching relay circuit of Fig. 4 and the rotary distributor shown schematically in the broken line rectangle of Fig. 4 to the facsimile printer. During the reception of telegraph signals the receiving switching circuit 28 is unoperated and the speech path s blocked oif by the receiving singing suppresso I9. The rotary distributor of the facsimile transmitter, here represented by thc motor and synchrono'us equipment 40, is kept in synchronism with the distant rotary distributor of the facsimile printer here represented by the motor andsynchronous equipment 4I by means disclosed in a patent granted to L. A. Meacham No. 2,207,748.

For purposes of the present description it is only necessary to mention the fact that the rotary distributor operated by motor 40 will be kept in perfect synchronism with the distributor represented by motor 4I if there is an occasional transmission from a spacing to Aa. marking impulse, that is, if there is an occasional operation of relay 31 and, therefore, an occasional corresponding operation of relay 42. Such transitions are caused during the normal operation of the facsimile transmitter once for each cycle of operation of the rotary distributor of the facsimile transmitter. Each time that the brush 43 engages the distributor segment 44, relay 31 is driven .from spacing to marking, and similarly relay 42 is driven from the spacing to the marking. If the facsimile printer is in perfect synchronism with the facsimile transmitter, then the three brushes 45, 46 and 41 will be perfectly centered on the segment 48 with the result that as relay 49 moves to its marking contact, the condenser 52 will be discharged equally into both windings of relay 53 and this relay will fail to move its armature. Relay 53, it will be noted, controls a fast and a slow relay 54 and 55, respectively, and these, in turn, control an indicator 56 which here merely represents means to cause the facsimile printer motor and synchronous equipment 4I to speed up or slow down to correct any deviation from the synchronism with the motor 40. If the brushes 45, 46 and 41 are not perfectly centered on the segment 48 when relay 49 moves to its marking contact. then the relay 53 Will be driven either to its left or right-hand contact, as the case may be, and the correction will be properly made to bring the motor 4 I into synchronism withmotorr40 where the brushes 45, 46 and 41 will again be perfectly centered on the segment 48.

In operation, if noA voice currents are being transmitted from line I and the voice operated circuit 1 is, therefore, unoperated, the. telegraph apparatus of Fig. 3 will be fully enabled with relay 29 unoperated as shcwnl c When in the Spacing by'motor 4l, any one of the brushes l1. il or 59 which may have been selected closes a contact to ground through the operation -t the as- Sociated cam, relay '91 will be operated to its marking contact, whereuponthe converter 38 will be placed ln a condition so that telegraph signaling current from the oscillator 99 will pass out through hybrid coil il and over antenna. l2. This marking current is received over antenna I4 and translated by the telegrad 99 into operation of the relay 42. If relay 91 is driven to its contact, then the converter 98 will prevent the telegraph signaling current from oscillator 99 `from transmitting any current into the hybrid coil lli. Thus therelay 42 at the receiving end will be driven to its unoperated or spacing contact.

At the receiving end, when the telegraph apparatus is enabled, relay 2l will be operated during periods of telegraph transmission, consequently relays 99 and 8| will be unoperated as shown. With relay 42 operated on incoming marking impulses and unoperated on spacing impulses, groimd will be connected to its armature and relays 49, I9 and 9| will be driven to their marking contacts when relay 42 is in the position shown. Therefore, each marking nnpulse will result in the operation of this chain of three relays. It has generally been explained hereinbefore how the relay 49 causes the discharge of condenser 92 into the windings or either one of them of relay 52. Condenser 52 is -charged during the periods that the relay 49 is` on the spacing contact.

When the voice takes charge of the receiving circuit and the receiving switching circuit 28 is energized, then relay 99, after an appropriate time interval, determined by the condenser 62 and resistances 99 and 84. will become deenergized, whereupon the relays and 8i will become energized. Relays 49, 59 and 5| are then permanently held on their spacing contacts an'd relay 42 is rendered ineiective. Y

When the voice takes charge of the channel the voice operated switching circuit 1 at the transmitting end as well' as the receiving switching circuit 28 at the receiving end, is operated. As a consequence relay 29 is operated. If the transmission of a character is almost completed, then brush will be in contact with segment 66 and as a consequence the control tone delay relay 2t and the transmitting check delay relay 61 will be operated in a circuit to the back contact of the transmitting check relay 69. This will prevent the action of relay 29 from becoming immediately e'ective and hence, the transmission of the character will be completed. If, however, the operation of relay 29 occurs at any other instant than when brush B5 is in contact with segment 6B, alcircuit will be completed from battery through the armature and front contact of relay 29, the back contact and armature of relay 6l, and thence through the windings of relays 68 and 99. Relay 99 opens the circuit of relays 91 and 29, and closes a circuit through the lower winding of relay 'I8 to drive this relay to its spacing contact. Thereupon relay 1i becomes operated to prevent the further operation of the telegraph transmitting line relay 31 and to operate the control magnet 12 to prevent the tape 13 from being advanced. The operation of the control magnet 12 thus effectively stores any code which has been only partially transmitted so that when next this transmitting apparatus is rendered effective, the stored code will be retransmitted in full. So long as relay 19 is'held to its spacing contact the control magnet 12 will remain energized. Once a revolution of the rotary distributor operated by motor 40, brush 18 contacts segment 14 and `by energizing the upper winding of relay 10 tends to drive this relay to marking. However. ii the circuit of the lower winding of this relay .is still closed, it wily stay on spacing. Only when this lower winding is opened will the contactbetween brush 19 and segment 14 be eifective, and thus it will be noted that the control magnet 12 is never deenergized until the rotary distributor has reached such a point that the next code to be transmitted will be transmitted in full.

For a more detailed description of the operation oi the facsimile transmitter;7 reference `should be made to Figs. 5, Snd 8.

The motor 40 through a system oi' gears drives shafts 15, 19 and 11 continuously. Shafts 15 and 11 cause certain cams and rotary distributor segments to rotate. In Fig. 8 the brushes 49, 95 and 18 are indicated as cooperating with rotary distributors carrying segments A44. 88 and 14, respectively. The brushes 91. I9 and 59 are inclicated as cooperating with cams, each of which is cut in such a way as to cause the responsive mechanism at the receiving end to trace a different character. Each brush 91, 59 or 5941s separately movable and is selectable through a system of code bars.

Referring particularly to Fig. 5, a perforated tape |24 is properly engaged with the feed wheel 18 whereby the tape will advance lin step-by-step manner toward the left of the apparatus. 'This lili liti

tape maybe perforated according to any wellknown mthod but for purposes of illustration it will be assumed to be in this case a standard six unit permutation code. Transmission of signals by this transmitter is controlled by the slackness or tautness of the tape or by the operation of the control magnet 12 hereinbefore referred to. So long as the perforated tape is fed -to this transmitter faster than it can be used or the control magnet 12 is not energized, the transmitter will continue to operate. If ,the tape becomes taut, then bar 19 will be lifted into the position shown in full, thus moving ythe level 89 downwardly and carrying the latch 9i into the path of movement of the arm 92 on leve 83. This lever 83 is moved once for each revolution of the shafts 15, 16 and 11 by means of the cam 94 so now upon the next counter-clockwise movement of lever 93 under action of its spring 95 after the tape tightens, when the roller 89 leaves the high portion of cam 94, arm 92 will be latchefi by the latch 9i. The transmission of signals will be suspended since portion 81 of lever 93 cannot rise to release feeler slides 99. With the parts in this position the motor and the driven shaft continue to rotate but the feeler slides 99 are not allowed to rise and, therefore, there is no new selection of a character.

When the voice takes command of the circuit the control magnet 12 is operated. The armature of this magnet operates a lever 99 in a clockwise direction so as to pull down latch 9i through spring 90 and to pull portion 91 out of engage- 7e are left in this position so that the code being 75 transmitted at the time magnet 12 is operated will be effectively stored for retransmission. .A

For further details of the operation of this transmitting device reference may be had to the above-noted Klelnschmidt Patent 2,000,083.

At the receiving end shown in skeletonized form in Fig. 9, themotor 4| is kept continuously running and in synchronism with the distant motor 40 by the means hereinbefore indicated. Motor 4| drives a shaft 92 coupled through a differential adjusting means 93 to the main shaft 94.-

A number ofdistributor discs having segments 48, 95, 96 and 91 are moved by this shaft and cooperate with brushes 45, 46, 41, 98, 99, and |0|. These brushes and distributor segments perform certain control functions as will be more fully explained hereinafter.

'I'he shaft' 94 carries a member having a plurality of helical striking surfaces thereon. This may be termed an anvil and the part |83 moved by the magnet |04 may be termed a hammer. The hammerJ |03 moved in accordance with the incoming code will cause a facsimile character to be inscribed on the surface |05.

Shaft 94 moves aF pinion |00 which meshes with a gear |01 to move the shaft |08. A clutch |09 causes the movement of shaft |08 to be imparted to shaft H0. While this` receiving device is in full operation, the magnet will be operated and shafts |08 and ||0 will be clutched t0- gether so that a roller ||2 will cause the surface to advance between the hammer |03 .and anvil |02 at the proper rate. Also connected to the shaft ||0 there is a member ||3 forming part of an escapement device. Member ||3 carries a pin ||4 which when shaft ||0 is declutched from shaft |08 will engage an arm ||5 through the agency of a spring IIS which tends to move the shaft ||0 in a counter-clockwise direction. With the magnet energizeda link ||1 is interposed between parts ||8 and 9 so that with each revolution of the shaft 94 the cam |20 will cause the pallet |2| of the escapement to execute one complete movement to advance the toothed wheel |22 one step. Under normal conditions the pallet |2| is moved and arm ||5 is brought next to pin ||4 at the beginning of the inscription of a character. As the character is being inscribed the toothed wheel |22 remains stationary and hence the arm ||5 remains stationary. 'I'he shaft ||0, however, continues to rotate and spring ||6 is wound up. Still under normal conditions when the character has been completely inscribed the cam |20 will cause the escapement to move the arm l5 to catch up to the movement of pin 4.

If the transmission is stopped after a character has been partially inscribed, then magnet is deenergized, resulting in the movement of link ||1 to render the action of cam |20 ineffective. At the same time shaft ||0 is declutched from shaft |08 and shaft ||0 now being free will be moved backwardly by spring ||6 until pin ||4 engages arm 5. By this backward movement roller ||2 causes the surface |05 to be moved backward so that the partially inscribed characy ter will be retraced from the beginning when transmission is again resumed.

Y Looking now at the circuit diagram Fig. 4, it will be noted that a relay |23 controls the energization of the magnet Relay |23 is a polar relay and will stay in its marking or spacing position until energized again. As shown, relay |23 is on its marking contact. Energization through its lower winding will drive it to spacing also indicated the point at which the holding and energization through its upper windingwill drive it to marking. Under normal conditions,

that is, with the facsimile printer in full operation and with relay 36 energized whereby relay 8| is deenergized, relay |23 gets one impulse to spacing 5 per revolution of shaft 94 and that is when brush 99 contacts segment 95. However, immediately thereafter a circuit is set up through brush 98 and the armature and marking contact of relay 50 to the upper winding of relay |23Y to drive it 10 back to marking and to start the movement of shaft 0 at a point where the 'character now to be inscribed will be properly begun. In order to prevent the deenergization of the magnet periodically when the facsimile printer is in constant operation, a substitute circuit is provided by brush |0| and segment 91. Therefore, magnet will be released only ifl brush 0| leaves segment 91 and relay |23 has been driven to spacing. But if relay 50 is on its 20 marking contact, as it will be at this time if the telegraph channel is functioning, then brush 98 will contact segment 95 and drive relay |23 to marking before brush |0| leaves segment 91.

Now when the voice takes charge of the channel and relay 36 becomes deenergized, relay 6| is energized and then a circuit is completed through brush |00 and'segment 9G for holding relay |23 on its spacing contact.

Reference to Fig. Twill show the time relation between the various brushes and the distributor segments both at the transmitting and at the receiving ends, when the motors at these two ends are in synchronism with each other. There is shoulder` on the escapement cam engages. This is a function which is provided so that if the voice takes charge near the end of the inscrip- ,tion of a character and the apparatus at the transmitting end has functioned to complete that character, then` the receiving apparatus will also complete the character and move the tape on to receive the next character. At this point, within a short distance of the end of a character code, a shoulder on escapement cam |20 makes rm cont-act between parts ||1, ||8 and ||9 so that even should magnet I I be deenergized, the clutch |09 will not disengage shafts |08 and ||0 until .the pallet |2| has caused the wheel |22 to move forward another tooth. This point is also indicated on the time chart Fig. '1.

Other details of the working of the facsimile transmitter and the facsimile printer can be had from the before-mentioned Klelnschmidt Patent 2,000,083. A

What is claimed is:

1. In a communication system, atransmission channel, means at one end'of said channel for transmitting character code signals, means at the other end of said channel responsive to said signals for inscribing corresponding characters, means for interrupting the transmission of vsignals at any point in the character code whereby a character may be left only partially inscribed, means responsive to the interruption of a character code at any point other than the end thereof for starting transmission again at the beginning of said partially transmitted code, and means at the receiving end of said channel for repositioning said inscribing means for retracing said partially inscribed character.

2. In a communication system, a transmission channel, means at one end of said channel for transmitting character code signals. means at the other end of said channel for recording corre- 75 assenso spending characters on a constantly forwardly moving surface, means for interrupting the transmission of signals at any point in the character code whereby a character may be left only partially recorded, means responsive to the interruption of a character code at any point other than the end thereof for starting 'transmission again at the beginning of said partially transmitted code, and/ means at the receiving end of said channel for reversing the direction of travel of said surface for a distance equal to the length of the partially recorded character whereby the character when retransmitted will be retraced on said surface.

3. In a communication system, a transmission channel, means at one end of said channel for transmitting character code signals, means at the other end of said channel responsive to said signals for inscribingcorresponding characters on a moving tape, means for interrupting the transmission of signals at any point in the` character code whereby a character may be left only partially inscribed, means responsive to the interruption of a character code at any point other than the end thereof for starting transmission again at the beginning of said partially transmitted code, and means at the receiving end of said channel for moving said tape backward a distance suiiicient for repositioning said tape for retracing said partially inscribed character.

4. In a composite printer, means responsive to a train of character code signals for inscribing a compositely formed character, said means in-l cluding a constantly moving surface on which said character is inscribed, means responsive to the interruption of said train of signals before completion thereof for moving said surface backwardly whereby when transmission of said train of character code signals is resumed at the beginning thereof the inscription of said characte will be retraced. I

5. In a composite printer, a hammer and anvil, n

said hammer responding to a train of character code impulses and said anvil constantly moving to present a different striking surface to said hammer, and a constantly moving surface `to be affected by the joint action oi said hammer and anvil, and means for reversing the direction of movement of said surface responsive to an interruption of said train of impulses.

6. In a composite printer system, a hammer, an anvil, a moving tape and a motor for moving said anvil and said tape, means operating' synchronously with said motor for transmitting character code impulses for operating said hammer, a clutch connection between said motor and said tape, and means for moving said tape backwardly, said last means being rendered free to operate when said clutch has disengaged said tape from said motor.

7. In a composite printer, a hammer actuated by character code impulses, a motor driven at a rate synchronous with incoming character code impulses, an anvil driven by said motor, a surface acted upon by said hammer and anvil, a surface moving mechanism, a clutch for operatively connecting said mechanism to said motor, a stepby-step device operated by said motor to advance one step for each complete train of character code impulses, and a. resilient connection between said step-by-step device land said surface moving mechanism for moving said surface backwardly upon'operation of said clutch in disengaging said by character code impulses, a motor operating at a rate synchronous with incoming character code impulses, an anvil driven by said motor, a mechanism for constantly moving a surface between said hammer and anvil, a clutch for operatively connecting said mechanism to said motor, a stepby-step device operated by said motor to advance one step for each complete train of character code impulses, a resilient connection between said step-by-step device and said mechanism for moving said surface backwardly upon operation of said clutch in` disengaging said mechanism from said motor, and means for, disabling said step-bystep device.

9. In a composite printer, means for moving a tape steadily forward, a step-by-step device advancing with the movementof said tape a distance equal to the length of a character upon the reception by said printer of each complete train of character code impulses, a resilient connection between said tape moving means and said stepby-step device, and means for operatively disconnecting said tape moving means whereby said resilient connection acts to return said tape a distance equal to that part of a step which said tape had advanced since said step-by-step device last acted.

10. In a composite printer, a tape moving mechanism comprising an escapement device for advancing a tape step by step, an impeller for steadily moving a tape, and a resilient connection between said impeller and said escapement for returning a tape a fraction of a step upon relaxation of said impeller.

11. In a communication system, a transmission channel, means at one end of said channel for transmitting character code signals, a composite printer at the other end of said channel responsive to said signaling means, said printer including a motor, a tape moving means and an anvil driven by said motor, a hammer responsive to signals, an escapement driven by said motor and a resilient connection between said escapement and said tape moving means for imparting a backward movement to said tape moving means, and means for holding said motor in synchronism with said signaling means.

12. In a. communication system, a transmission channel, means at one end of` said channel to transmit character code signals, means at said end to interrupt the transmission of such signals and alternately connect voice current circuits to said channel, means `at the other end of said channel responsive to said character code signals, means at said other end of said` channel responsive to said interrupting means for disconnecting said code signal responsive means auditor alternately connecting thereto voice current circuits, means operative over said channel for maintaining synchronism between said codel signaling means and said code signal responsive means. said code signal responsive means comprising a composite printer having a motor, a hammer responsive to character code signals, an anvil and a tape moving device driven by said motor, a tape escapement operatedby said motor, a clutch for disengaging said tape moving device from saidmotor, a. resilient connection between said escapement and said tape moving device forY baekwardly adjusting-said tape moving device reengaging said tape moving device from said motor. and means responsive to said interrupting means for operating said clutch.

IBA E. C'OLE.

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