US2882346A - Remote dictation system - Google Patents

Description

' A ril 14, 1959 R. JONES ETAL 2,882,346

- REMOTE DICTATION SYSTEM Filed March 28, 1957 I 2 Sheets-Sheet 1 MACH/NE l AMPLIFIER! F l G I.

TONE GENERATOR lNl/ENTORS LLOYD E. JONES PUDOLF E. FEEU/VD 401m M RA v/vo/P DOUGLAS E. 7/; no?

ATTORNEYS L. R. JONES ET AL REMOTE DICTATION SYSTEM --April 14, 1959- 2 Sheets-Sheet 2 Filed March 28, 1957 /NVEN7'0P5 LLOYD R! JONES ATTORNEYS RUDOLF 5. FEEUND JOHN M. RAY/V01? BY 0006015 5 mywe dam, Hm: $14414 wzmtm WWW \MN gkumkmmu vb wmi 3m United States Patent 6 "ice REMOTE DICTATION SYSTEM Lloyd R. Jones, Monroe, Rudolf E. Freund and John M. Raynor, Bridgeport, and Douglas E. Taylor, Westport, Conn., assignors to Dictaphone Corporation, Bridgeport, Conn.

Application March 28, 1957, Serial No. 649,066

. 23 Claims. (Cl. 179-1001) This invention relates to dictating apparatus. More particularly, this invention relates to remotely-operated dictation systems wherein a number of dictating stations are connected to central recording apparatus, e.g. as disclosed in U.S. patent application Serial No. 457,165, filed by Lloyd R. Jones and Douglas E. Taylor on September 20, 1954. The description herein is directed primarily to improvements over this earlier system, and similar nomenclature has been used to simplify comparison therewith. For detailed information on parts of the system not specifically disclosed herein, reference is made to the above application.

To obtain high-quality recording and reproducing, it is particularly important that the talking circuit between the dictating stations and the central machine be arranged to minimize the effects of extraneous signals such as electrostatic and electromagnetic pickup. This problem is particularly difficult in remote-dictation systems since it is desirable in such systems, as disclosed in the above application, to use the talking circuit for transmitting control information, e.g. in the form of multi-level direct-current signals. It is an important object of the present invention to solve this problem by providing novel circuit arrangements for accomplishing these objectives in a simple and economical manner. Further objects of the invention relate to the providing of improved control functions for facilitating the operation of a remotely-operated dictating machine. Other objects, aspects and advantages of the invention will be in part pointed out in, and in part apparent from, the following description considered together with the accompanying drawings in which:

Figure 1 is a schematic diagram of a remote dictation system comprising a preferred embodiment of this invention; and

Figure 2 is a schematic diagram of the remote dictators instrument used in the system of Figure 1.

In the upper left-hand corner of Figure 1 is shown a telephone-type dictators instrument indicated by a block 10, and which is similar in many respects to the corresponding instrument disclosed in the above application. This instrument, the details of which are shown in Figure 2, is connected by a cable having four lines 12, 14, 16 and 18 to a control unit including a number of relays which selectively condition a dictating machine generally indicated at 20 (see the right-hand portion of the drawing) for operation as desired by the remote dictator. (To simplify the discussion to follow, all of the relays are shown in their de-energized condition.)

As explained in the above application, a dictator may take control of the central machine 20 by lifting the hand-set-of his instrument out of the cradle. This completes a direct-current path within the instrument between lines 12 and 14 which constitute the talking circuit of the system. The direct-current path may be traced (Figure 2) from line 12 through a length-of-letter mar switch 22, contacts 24 and 26 of a privacy r 2,882,346 Patented Apr. 14, 1959- relay generally indicated at 28, a resistor 30, through the carbon-button microphone 32, across contacts 34 and 36 of an attendants call switch generally indicated at 38, across contacts 40 and 42 of the privacy relay, and through contacts 44 of a cradle switch generally indicated at 46 (which is actuated when the hand-set is lifted up) back to line 14.

Outside of the dictators instrument (Figure 1), line 12 is connected through a lead 48 and the winding of a line relay 50 to the positive terminal of a D.-C. power supply generally indicated at 52, and from the negative terminal of this power supply back through the winding of a record relay 54 and a lead 56 to line 14. Ac cordingly, the power supply 52 produces a flow of direct current through these two relays, which have identical windings, i.e. the same number of turns with the same ohmic resistance, and are balanced symmetrically about the power supply 52 in order to minimize stray electrical pickup in the talking circuit 12 and 14 due to external influences.

The line and record relays 50 and 54 are arranged to operate at different current levels, by virtue of differences in their contact spring loading and air gap spacing. The electrical specifications for the line relay are: (1) there will be no operation of the relay with a current through its winding of 3 milliamps., (2) the relay will operate with a current of 7 milliamps., (3) once the relay has pulled in, it will remain held in operated condition with a current of 4 milliamps., and (4) the relay will release when the current drops to 0.5 milliamp. Corresponding electrical specifications for the record relay are as follows: (1) there will be no operation of the relay with a current of 13 milliamps., (2) the relay will operate with a current of 16 milliamps., (3) once the relay has pulled in, it will remain held in operated condition with a current of 13 milliamps., and (4) the relay will release when the current drops to 8 milliamps.

As noted above, the D.-C. current path established when the dictator picks up his handset includes a series resistor 30. This resistor is of relatively high ohmic resistance (3900 ohms) in order to establish a low steady-state current level of about several milliamps. Nevertheless, because of the circuit arrangement described below, the line relay 50 is actuated when the dietator lifts up his handset, and the machine 20 is conditioned for dictating operation from the dictators instrument 10. When the dictator wishes to record, he depresses a clutch button 60 (normally part of the handset) which shorts out the resistor 30 through an inductor 62 and thereby establishes a current level in the talking circuit 12 and 14 sufiiciently high to operate the cuit due to the resistor 30 is too low normally to operate the line relay 50. However, it is not possible, as a practical matter, to reduce the size of the resistor 30 and still obtain an adequate differential between the twocurrent levels established in the talking circuit, nor is it possible to increase the line voltage without introduc-' ing further complications in the system design. Also, the line relay cannot readily be made to operate at this low current level, particularly since its winding is identical to the record relay winding. Consequently, other means must be provided to assure that the line relay is actuated when the dictator lifts his hand-set.

This is accomplished in accordance with one aspect of the present invention by a capacitive circuit in parallel with the resistor 30. This capacitive circuit comprisesa a large capacitor 64 (having a capacitance of 10 micro farads) in series with a small resistor 66 (47 ohms). When'the hand-set is lifted out of its cradle to complete the D.-C. path described above, this capacitive circuit initially presents an effective short circuit across the res'istor' 30, so that there is a momentary surge of current through the line. relay 50 of sufficient magnitude to actuate thisrelay. This current surge is substantially equal iii peak, amplitude to the higher current lever established when the resistor 30 is shorted out by the clutch button 60' (the series resistor 66 having only a minor effect on the current magnitude). It has been found that the record relay 54 will momentarily be actuated by this surge of. current, but this has no important effect on the operation of the system.

"When the line relay 50 is energized, its contacts 68 close to complete an energizing circuit for an in-use relay generally indicated at 70 (and corresponding to the second in-use relay. 136 referred to in the above-mentioned prior, application). The energizing circuit for relay 70 may be traced from a positive terminal 72 of a D.-'C. power supply 74, through contacts 68 of the line relay, through a rectifier 76 and a resistor 78, through thein-use relay winding and back along a lead 80 to the negative terminal 82 of the power supply. Actuation of the in-use relay closes its contacts 84 to complete an 2 energizing circuit for a hold relay generally indicated at86, the circuit passing from the positive terminal 72 of the power supply 74 through the in-use relay contacts-84, through a resistor 88 and the hold relay windiiig, and back along lead 80 to the negative terminal 82 oithe power supply.

Actuation of the hold relay 86 closes its contacts 90 which furnish A.-C. power to a motor 92 in the dictating machine 20. The rotor shaft of this motor is coupled to'a clutch 94 to operate certain elements of the dictatin'g machine in a manner well known in the art. The AFC. power circuit completed by the hold relay also maybe connected to the rectifier power supply typically provided in a dictating machine to furnish D.-C. plate potentials for the vacuum tubes of the audio amplifier.

To commence dictation, the dictator presses the clutch button 60 which as described above shorts out resistor 30 and increases the D.-C. current level flowing through the talking circuit to operate the record relay 54. Contacts 100 of this relay close and complete an energizing circuit to "a clutch relay generally indicated at 102, the energizing current being delivered by the D.-C. power supply 74. Contacts 104 of the clutch relay thereupon close to complete an energizing circuit for a clutch solenoid generally indicated at 106 in the dictating machine This energizing circuit may be traced from the positive terminal 72 of the D.-C. power supply 74, through contactsltltfof the record relay and contacts 104 of the clutch relay, through contacts 108 of a limit relay generally "indicated at 110 (which as described in the above application is normally energized whenever the remote dictation system is available for use), through the clutch solenoid winding and back along a lead 114 to the negative terminal 82 of the DC. power supply. Energization of the'clutch solenoid actuates the clutch 94 which thereupon transmits mechanical power from the motor 92 to 'the dictating machine drive mechanism. Accordingly, by conventional means not shown herein, the machine record belt 116 is caused to move past a recording-head 118 in contact therewith, and the recording head-carriage 120 is caused to traverse relative to the record-belt;

'Voicesignalsspoken into the microphone 32 are fed from the dictators instrument 10 along the talking circuit'jlines 12 and 14 to the balanced primary windings 122 and 124 of an audio transformer generally indicated at 126; these windings are identical and are connected together through a DsC. blocking capacitor 128. .From. thesecnndarywinding= .130 of :this transformer, the voice. signalsiare transmitted. to theinput terminals 132 and 134 of the machine 20 from which they are fed through a conventional amplifier (not shown in detail) the are put circuit of which is coupled to the recording head 118. Consequently, the audio signals developed in the microphone 32 are impressed on the record belt 116.

Reverting now to the condition when a dictator has first picked up his hand-setfthe consequent energization of the hold relay .86 closes its contacts v142 and completes an energizing circuit to feed D.-C. power to lines .16 and. 18. This circuit'may be traced from the negative termi nal 144 of a D.-C. power supply 146 (lower. letthand corner of the drawing), through contacts 142 at the hold relay, through a fixed contact 148 and movable arm 150 of the limit relay '110 to line 16; and from line 18 to the positive. terminal 152 of the power supply 146. As described in the above-mentioned application, this power energizes a lamp 154 (Figure 2) at each dictators instrument 10 to indicate that the system has been seized for operation. In addition, the privacy relay 28 will the, energized at the dictators instruments that are. not in use; the privacy relay at the stationin use will. not be, energized because the relay energizing circuit is broken. by contacts 156 of the cradle switch 46 which open the hand-set is lifted out of its cradle. 4' i The D.-C. power supply 146 includes a conventional;

full-wave rectifier circuit (not shown) the output of which? is unfiltered so that the signal fed to lines 16 and 18 cludes a substantial component of 120 cycle hum, Whenever a subsequent dictator picks up his hand-set; while the system is in use, this hum component isifedto the ear-phone 158 of that dictators instrument in order. to warnhim that the system is not available. The warns ing hum circuit may be traced from line 16 through conII- tacts160 of the cradle switch 46 (actuated when the, sub;

sequent dictator lifts'hishand-set), through a fixed cou.-

tact 162 and movable arm 40 of theprivacy relay (which is maintained in energized condition through.

locking contacts 164 of the. privacy relay when thevhand' i set is lifted up), through the attendants switch 38 tofthe, ear-phone 158, through a capacitor 166 and a resistor.

168, through movable arm 26 and a fixed contact 1760f the privacy relay, and through a capacitor 172 back to}. line 18.

To make a length-of-letter mark on the transcription pad normally provided with a dictating machineQthe dictator depresses, switch 22 in the instrument 10. breaks the direct-current path for the talking circuit lines 12 and 14, and the line and record relays 50 and 54 ac-.

cordingly are de-actuated. Contacts 68 of the lineirelay open to break the energizing circuit for the in-use relay 70; after a short time delay produced by a capacitor 1 74. (12 microfarads) in parallel with the winding of this; relay, the in-use relay drops out and its contacts 84 open to de-ene rgize the hold relay 86. The hold relay is of the slow release type because of a capacitor 176 (60 microfarads) in parallel with the relay winding, and the hold relay will not drop out until several seconds after the use relay contacts 84 have opened.

When the in-use relay 70 drops out, its contacts 178 close to complete an energizing circuit from a positive terminal 180 of the power supply 74, through contacts 182 of the hold relay (while it is held actuated by the capacitor 176) to a length-of-letter marking solenoid 184 in the dictating machine 20. The armature of this solenoid is mechanically connected to a marking device generally indicated at 186, the details ofwhich form no part of the present invention, and which includes a marking stylus 188 arranged to make an indication mark-on. a pad of paper 190. The stylus 188, asusual, is mechanically:- driven along the pad 190 in accordance with. the movements of the dictating machine carriage 120, as diagrammatically indicated by the dashed line connection 192;

thus, the mark made. by- .the.stylus. will indicate-thepostin obtains its operating power from the output shaft of the clutch 94, as indicated by the dashed connection line 194. Since de-energization of the record relay 54 opens relay contacts 100 to break the normal energizing circuit for the clutch solenoid 106, an alternate energizing path for the clutch must be established whenever the length-of letter mark switch 22 is depressed.

This is accomplished by a set of contacts 196 of the inuse relay 70 which close when the in-use relay drops out and thereby energize a tone relay 198. Contacts 200 of the tone relay close and establish an energizing circuit through a set of contacts 202 of the hold relay 86 (held actuated while the mark is made by capacitor 176) and contacts 108 of the limit relay to the clutch solenoid 106. Accordingly, the clutch 94 is energized and supplies power to the marking device 186 to make a single mark on the pad of paper 190.

The length-of-letter marking switch 22 is of the springloaded type, and in normal operation will break the talk- -ing circuit 12 and 14 only for a fraction of a second.

The bold relay 86 is arranged so that it will not drop out until several seconds after it has been de-energized, and the length-of-letter mark will be made and the talking circuit re-established before the hold relay drops out. Therefore, the power circuit to lines 16 and 18 will remain activated and all of the privacy relays (except at the users station) will remain energized. Consequently, the dictator cannot lose control of the machine 20 when he makes a length-of-letter mark, even if the hand-set at one of the other stations is out of its cradle.

As described in the above-mentioned application, when a dictator desires to listen back to a substantial portion of the material he has already recorded, he can signal the attendant at the central machine 20, and the attendant will thereupon manually move the machine carriage back to the desired region of the record and place the machinein reproduce condition. Because there is a possibility that a dictator, after listening to all of the recorded material on the record, may hang up his hand-set without having the machine returned to record" condition,

means also are provided in the present system to prevent any subsequent dictator from attempting to record additional material while the machine is in reproduce condition.

For this purpose, the machine carriage control lever diagrammatically indicated at 204 (and which is arranged by conventional means not shown herein to place themachine in record, neutral or reproduce conditions) is mechanically connected to a cut-out switch 206 so as to close this switch whenever the machine is in reproduce condition, i.e. with the reproducing head 208 in contact with the record 116 and the recording head 118 out of contact with the record. When a dictator hangs up with the machine in this condition, the limit relay 110 will drop out because of a short-circuit placed across the relay winding. This short-circuit can be traced from the upper terminal of the relay winding through contacts 210 of the tone relay 198 (which is energized whenever the talking circuit 12 and 14 is interrupted) and back through the switch 206 to the lower terminal of the limit relay winding.

When the limit relay 110 drops out, it completes an energizing circuit from the power supply 146 through a. fixed contact 212 and movable arm 150 of this relay to lines 16 and 18. Accordingly, the privacy relays for all of the dictators instruments will be energized, and it will not be possible for any remote dictator to take control of the machine 20. Also, the 120 cycle hum provided by the unfiltered output of the power supply 146 will be fed to the ear-phones of each of the dictators instruments. through the circuit previously described, so that any dictator who lifts his hand-set up will be positively warned that he cannot proceed with dictation until the machine has been reset for proper operation.

' De-actuation of the limit relay 110'also causes a tone signalto be sent to a loud-speaker 214 in the machine 20 to signify to the attendant that the machine must again be reconditioned for dictating operations. For this purpose, contacts 216 of the limit relay close to complete an energizing circuit from a positive terminal 218 of the power supply 74 to a pulse relay generally indicated at 220. Contacts 222 of the pulse relay close and activate a tone generator generallyindicated at 224, the energizing current being supplied from another positive terminal 226 of the power supply 74. An audiofrequency tone signal thereupon is transmitted from the output terminals 228 of the tone generator, through a capacitor 230 and contacts 232 of the limit relay to the loud-speaker 214.

As described in the above-mentioned application, function controls are provided at the dictators instrument 10 to enable the dictator to obtain playback operation (for purposes of obtaining a quick review of the last several words dictated), making a correction mark on the transcription pad associated with the dictating machine, and signalling the attendant. These functions are obtained in a similar manner in the present system by operating a playback push button 234, a correction push button 236, or the attendants push button 38. Each of these push buttons close corresponding switch contacts which establish a direct-current path between lines 14 and 16, and thereby energize certain relays (not shown in detail herein to simplify the presentation) in the control unit which correspondingly operate the dictating machine 20 as desired. To exemplify this portion of the circuitry, there is shown in Figure l a control relay 238 (corresponding to control relay 362 in the above-mentioned prior application) which is connected between lines 14 and 16 and energized by a D.-C. power supply 240 when these lines are shorted together in the instrument 10. As explained in the above application, when the control relay is energized by operating the playback switch 234, it completes additional circuits (not shown) to condition the machine 20 for playback operation.

If lines 14 and 16 are connected directly together, an unbalanced condition would be established in the'talking circuit 12 and 14. This can cause difl'lculty by permitting the flow of hum signals and other extraneous electrical pickup in the talking circuit, especially due to the 120 cycle hum signal fed to lines 16 and 18 by the unfiltered power supply 146. To avoid this difliculty, par ticularly when the machine is conditioned for playback operations, the direct-current connection between lines 14 and 16 (Figure 2) is made through a potentiometer 242. This potentiometer, in series with a D.-C. blocking capacitor 244 is effectively bridged across lines 12 and 14, and its slider 246 is connected to the lower switch sections 248 and 250 of the playback and correction push buttons 234 and 236. Thus, whenever either of these buttons is depressed, a direct-current path is established between line 14, through a portion of the potentiometer 242, through switch contacts 248 or 250 and back to line 16. By properly selecting the position of the slider of the potentiometer, the hum signal fed from lines 16 and 18 to the talking circuit 12 and 14 can be elfectively balanced with respect to this latter circuit so as to substantially eliminate hum signals in the ear-phone 158.

Although a specific preferred embodiment of the invention has been set forth in detail, it is desired to emphasize that this is not intended to be exhaustive or necessarily limitative; on the contrary, the showing herein is for the purpose of illustrating one form of the'invention and thus to enable others skilled in the art to adapt the I invention in such ways as meet the requirements of par ticular applications, it being understood that various modifications may be made without departing from the scope of the invention as limited by the prior art.

We claim: 7

1. A remotely-operated dictation system which includes centrally-located recording-and control apparatus daphasari .pmbma n, p nra ity .of remotedictatruments eachincluding a transducer, a commutor illsdlig .sitsu for con ct ng .sa d t an d ce s to said recording and ,contr ol apparatus, a .yoice-jsignal circuit coupled to 881d. ommnnication circuit for 1-feeding the y ks i nal ltht nt sa d rec rding e power pn tneansiW-nmdnq ng current flow ins id commun lon circuit, control means, at each. ofsaid instruments selectively establishing two diiferent current conditronsgn said cornm unieation circuit, firstand second curtslltis srsiz bls W tt P nnected in s co munic circuit and selectively actuable by said two currentjcon- SliEiQPS 139 .2 9 3 rs tqll m ans f onn n .Said 9 72? ar -ns ausi -sa com un cation c rc it 4'. h s e a iaa h t sa pnw r s pply me ns and to ;i -.=Yq isn l c rcu an 0Pt gmeans Sa s l s id rsqm c s i .cntrcntwe ersiz l means sto e ablish pr ,edetennine d r control functions at hid wsenlies an .-9. app ratusin a cor ance with ea sa 9 .o .m n

;-t9 :Pr d.kd c aticm system wh h in- Ell c nt a l -l ate I9QFd BaBd-Qnlrol app a u w ere n-a rssq qtnswh s est e .t at ve travelli l -W l .t$n t a movin r c r app atus p mprising, in combination, a plurality of remote dinner ins rumen sas -inclu an uc a comrnpnication cireuit for 529111;? ingisaid transducers to said .m and rs t p ap arat s; power pp y mean for are uciug c r ent :flqw i .sa d com u cat on circuit, controlmeans at Qflg ,of said instriiments for selectively est hing two, different. steadystate current levels in sai sqmm nisat on i ca nfi an sc n e ay mean ha n .ths ws n s ye w n n conn e in series in 'dcommunieationcireuitfthe lower of "said two cur- ;ent 16 ,615 beingsuflicientlto hold said first relay means ingperated condition but insufiieientjto hold saidsecond relay means in operatedcondition, capacitive means-fortn- .11 5 Par Qf-S id. QQ JUO n ts- 1s to r d c an t a i srals ra of urren in a commun o irc e said gontroimeansis operated, toestablish the lower of sad t wo steady-state current levels, said high-level current s r e bein su ic e I to op ra e sa rs ela means, and operatingmeans selectively under the control of said relay rnean's to establish. predetermined control inac na sa re a n an .c ap am s n a cordanee, with the. setting ofsaid control. means.

3. A dictation system as claimed in claim 2, wherein said'first relay means is arranged when actuated to condit n sai eco d n apparatu o i t n p r .;,4. A dictation ,system aselaimed in claim 2, wherein thewinding impedances of said first and second relay means are equal,; and wherein the ratio of the i operate L0 f irelease currents of said first relay means .issubstantially higher than the ratio of the operate" to release currents of saidsecond relay means.

5. A remotelyoperated dictation system which includes centrally-located recording and eontrol apparatus wherein a recording. headv is arranged for relative travelling movement with respect to a moving record, apparatus comprising, in combination, a plurality of remote dictators instruments, each including a transducer and an on-otfswitch, a communication circuit for connecting said ransd to sai r cor in and control pp atu power; supply means for producing current fiow in said comm n at on circui whe on of: ,s d sit- 9 .SW F has been. plac d in fot r s lienta isma m n a eachof said instruments for establishing arelatively low steady-state currentqlevel in said communication circuit, control switch means at each of said instruments for bypassing said unpeidance meansto produce a relatively high steadystate current level in said communicationcircuit, first and second relay g eans having their-w dings con- 5 assa current, conditions respectively, the ,windings of ear means beingarranged so that. iti svill-hold .in ,opetate'cl icon ition whenjhe loweriotsaid two steady=stateici1rjtiit levels .is established. in said communication .circuit said second relaymeans being arrangedso that it willnot hold in operated condition when said lower current level is establishedbutwill operate when the higher of said levels is established, a reactive circuitconnected .to said impedancemeans to produce an initial high-level surge of currentthrough said communication. circuit when oneof said on-ofiswitches is first moved to .on position, said first ,relay'means being operable by said high-level current surge and operating means selectively under the control of .said current-energizable means to establish predeterminedcontml functions at said recording and control apparatus in accordance with the. setting of. said control means.

6. A remotely-operated dictation system which includes centrally-located recording and control apparatus wherein a recording head is arranged for relative travelling movement ,with respect to amoving record,. apparatus comprising, in combination, a pluralityv of -.remote.;dit:- tators instruments each including ,a microphone, a communication circuit for connectin'gsaid instruments to Sa d recording and controlapparatus, power supply meansrfor producing current flow in said communication circuit, control means. at each of said vinstruments and having first and second positions for selectively establishing two ditferent current conditions in said communication ..ei rcuit, first and second current-energizable meansconnesited in said communication circuit and selectively actuablehy said. two current conditions respectively, -the,e1ectrical impedances of said current .energizable means being Jsuhstantially identical, circuit means for. connectingsaid current energizable .means in said communication '..circuit in balanced relationship to said. power supply. means,. and operatingmeans selectively under the control .ofjlsa'id current-energizable means to performcorresponding con troltunctidns. at said recording and control apparatusin accordancewith the positioning ofsaid controlmeans.

.7. A remotelyroperated dictationsystemwhich includes centrally-located recording and control apparatus wherein .a recording head is arranged for relative. travelling movement with respect to a movingrecord, apparatus comprising, in combination, a plurality of remote-dietator7s instruments each including a. microphone, ,acommunication' circuit comprisingfirst and. secondlines ior connecting said instruments to said recording and c ntrol. apparatus, power supply means for r duCingcurrent flow in said communication circuit, control means at each of said insta ments and having -fir st a nd second positions for selectively establishing two different current, conditions in said communication circuit,. first. aud sfiCQndrelay means connected in said first and second lines respectively and selectively actuable by said,

laymeans being substantially identicalso as topresent equal impedances in said lines, circuit means v for connecting said power supply means between thewin otsaid first and second relay means in balanced. relat onship theretqand operating means. selectivelyflunde control of said relay means to performcontrol ctionsat said .recordingand control apparatuslin accordance with the positioningof said control'means "8. A remotely-operateddictation system which'i'ncludes ce ntrally locate dv recording and control apparatus where inaIrecording-head is"'arranged for relative.travelling I es'pectto'Ya movingrec'ord,apparatus cording and control apparatus when said circuit means has been completed at one of said instruments, relay interruption of said circuit means.

9. A remotely-operated dictation system which in- "cludes centrally-located recording and control apparatus wherein a recording head is arranged for relative travelling movement with respect to a moving record, apparatus comprising, in combination, a plurality of remote dictators instruments each including a microphone and on-off switch means, circuit means for connecting any one of said instruments to said recording and control apparatus, said circuit means being completed when the on-ofi switch means at said one instrument has been placed in on position, privacy means at said instruments for excluding all other instruments from said recording and control apparatus when said circuit means has been completed at one of said instruments, relay means responsive to the completion of said circuit means for actuating said privacy means, marking means connected to said circuit means to make an indicating mark at said recording apparatus when said circuit means is momentarily. interrupted, and time delay means for said relay means to prevent the de-actuation of said privacy means during the momentary interruption of said circuit means.

'10. A remotely-operated dictation system which includes centrally-located recording and control apparatus wherein a recording head is arranged for relative travelling movement with respect to a moving record, apparatus comprising, in combination, a plurality of remote dictators instruments each including a microphone and on-otf switch means, circuit means for connecting any one of .said instruments to said recording and control apparatus, said circuit means being completed when the on-otf switch means .at said one instrument has been placed in on position, privacy means at said instruments for excluding all other instruments from said recording and control apparatus when said circuit means has been completed to oneof said instruments, relay means responsive to the completion of said circuit means for actuating said privacy means, control switch means at each of said instruments for momentarily interrupting said circuit means, operating means connected to said circuit means and adapted to perform a predetermined function at said recording apparatus when said circuit means is momentarily interrupted by said control switch means, and time delay means for said relay means to prevent the deactuation of said privacy means during the momentary interruption 'of said circuit means.

11. A remotely-operated dictation system which includes centrally-located recording and control apparatus wherein a' recording head is arranged for relative travel- 'lingmovement with respect to a moving record, apparatus (comprising, in combination, a plurality of remote dictator's instruments each including a microphone and on-otf "switch means, communication and energizing circuits for -connecting any one of said instruments to said recording and control apparatus, said communication circuit being completed when the on-ofi switch' means at said one instrument has been placed in on position, a privacy relay at' each of said instruments and arranged when actuated by saidenergizing circuit to exclude the respective instrument from said recording and control apparatus, contrbl relay means, responsive to the completion of said communication circuit for activating said energizing circuit, circuit means forming part of each of said on-ofr' switch means to disconnect the privacy relay corresponding to the respective instrument from said energizing circuit-when" said on-cfi switch means has been placed in on" position, a'holding' circuit for each privacy "relay to by-pass the corresponding circuit means when the privacy relay is energized, operating means connected to said communication circuit and adapted to perform a predetermined function at said recording apparatus when said communication circuit is momentarily interrupted, and time delay means for said control relay means to prevent the de-actuation of said privacy means during said momentary interruption of said communication circuit.

12. A remotely-operated dictation system which includes centrally-located recording and control apparatus wherein a recording head is arranged for relative travel ling movement with respect to a moving record, apparatus comprising, in combination, a plurality of remote dictators instruments each including a microphone, switch means at each instrument for conditioning the instrument for dictating operation when said switch means is in on position, a communication circuit and an energizing circuit for connecting said instruments to said recording and control apparatus, relay means forming part of said control apparatus and connected in said communication circuit, said relay means being activatable when said switch means has been placed in on position, means at said instruments to interrupt said communication circuit to de-activate said relay means, marking means at said recording apparatus and operable by said relay means when said relay means is de-activated, power supply means under the control of said relay means for producing current flow in said energizing circuit when said relay means has been activated, currentresponsive means at each of said instruments to be energized by said energizing circuit and arranged to exclude all instruments from said communication circuit except the instrument first operated for dictation, purposes, and time .delay means for said relay means to prevent the de-energization of said energizing circuit for a predetermined time period after actuation of said interrupting means.

13. A remotely-operated dictation system which includes centrally-located recording and control apparatus wherein a recording head is arranged for relative travelling movement with respect to a moving record, apparatus comprising, in combination, a plurality of remote dictators instruments each including a transducer unit and an on-ofi device, circuit means for connecting said instruments to said recording and control apparatus, said circuit means being set up for communication with said recording apparatus when the on-off device at one of said instruments is placed in on position, operating means at said recording apparatus for conditioning said apparatus for reproducing operations so that recorded material can be transmitted back to said instruments, switch means at said recording apparatus and actuable when said apparatus has been conditioned for reproducing operations, control means connected to said circuit means and to said switch means, said control means being operable when said switch means is in actuated position and concurrently one of said on-ofi devices is returned to ofF position, and indicating means operable by said control means to indicate that a dictator has placed his on-ofi device in off position with the recording apparatus conditioned for reproduce operations.

14. A remotely-operated dictation system which includes centrally-located recording and control apparatus wherein a recording head is arranged for relative travelling movement with respect to a moving record, ap paratus comprising, in combination, a plurality of remote dictatorsinstruments each including a transducer unit and an on-ofli device, circuit means for connecting said instruments to said recording and control apparatus, said circuit means being completed when the on-ofi device at one of said instruments is placed in on position, operating means at said recording apparatus for conditioning said apparatus for reproducing operations so that recorded material ,can be transmitted back to said instruments, switch means at said recording apparatus and ,ectuable when. said apparatus-thast ass-sass Arinsing.operationsglcontroli. V s cuit means and tosaidfswitch1means, -sa1d,,c"o ntr ol {devicesare in.ofi position,fand signallingumeans operable ,by said control means for transmitting an audio .fsignaljto any dictator who subsequently. places. his .on-

olfdevice in Fon position, to indicate to said subsequent dictator that the recording apparatus is conditioned'for reproduce'operations.

15. A remotely-operated dictation system which cludes centrally-located recording'and 'control apparatus wherein a recording head is arranged for relative travellin'g" movement with respect to 'a moving record, apfiaratus comprising,'in 'combinatioma" plurality of remote dictators instruments each including"aitransducer' unit and an 'on-cfi device, circuitjmeans for conneain satd instruments to said recording and control apparamssaid circuit means being completedwhen "the-as-snneviics at one of said instruments is placed 'in-6n position,

operating means at said 'recording apparat for of) drtioning'f'said'apparatus' for reproducing operat ris sof'tliat recorded matiial can be transniit'tdba ck tds'a'id instru- Highs, "switch means at said" recording s afams'and sesame when said apparatushasbeen conditioned "for reproducing operations,'controlmeans connected to said circuit means and said" switch means, said, control means being operable when said switchi me'ans "isf'in as u'ated position and concurrently an of said auger devicesare in on position, and tone fge'neratin'g jr nea'ns operable by said control means to"prodnce'fanaudib signal at saidreco'rding apparatus towarn the atte I :thata dictator has placed his on-ott'cdevice in @dfi osii- 'tion' with the recording apparatus 'conditioned"fo ,j ijeuce'operations 16; A remotely-operated dictation systern whichwincludes centrally-located recording and fiuorapparams wherein a recording head is arranged for'jrelativ'e trayclling movement with respect we movingr'ecorifapparatus comprising, in combinatiomfa pliiralityl of r'emdte creators instruments each including [a transducer .unit and anon-01f device, circuit means forconn'ecting said instruments to said recording andicontrolf apparatus, said operating means at said recording apparatus foriconditioningsaid apparatus for reproducing operations, so that recorded material can be transmitted back' to said instruments, switch means at said recording apparatus and actuable when said apparatus has been conditioned for reproducing operations, control means connected to said circuit means and said switch means and operable when saidswitch means is in actuated position and concurrentlyall of said on-ofi devices are mean position, saidcontrol means being arranged when operatedto actuatelsaid privacy means to prevent any dictator from establishing communication with 'said""recording apparatusl i 17. A remotely-operated dictation system which includes centrally-located recording'and control apparatus wherein a recording head is arranged forirelative'travelling. movement with. respect to a moiiing' reesrriapparams .com'pris'ingin combination, l' "1 are dictatorsinstr'uments sacs incliiding' icroplionef first, second and'third lines connectingsaid instruments'wsaid Cuit means being completed when the onoff devic at recording and controhappar'at'u's, "said firstand second lines serving as a communication cams; function control means connected to said second and third linesand' a eiwhe 'a DEC. path has been estab 1 w per! h responsive to said function control means forperfgrn ing a predetermined function whenever saidswitch means actuated.

i 18. A remotely-operated dictation system which .includes centrally-located recording and control apparatus .wherein a recording head is arranged for relative travelling movement with respect to a moving rec0rd,fap'paratus comprising, in. combination, a.plurality of remote dictators instruments each including a mic'rophone,,first, second and third lines connecting said instruments ,to said recording and control apparatus, said first and second lines serving as a communication circuit, resistive means coupled between said'first and second 'lines atea1ch ,of's'aid instruments and having an intermediate tap point, switch means at said instruments' for connecting's'aid intermediate tap point to said third line to establishfa D.-C. path between said second and third .lines,"po1wer suppl means for producing a flow or current-through Tsaid D.-C. path, playback control means connected-"to said second and third lines and operable by said current when said -D.-C. path has been established between said secondan'd third lines at one of 'saidinstr'uments,""and playback" means at 'said recording ap aratus'responsive to said control means for conditioningsaid"i'ecdrding apparatus for playback 'operation'whenever' said an means is actuated.

"19. A remotely-operated dictation system which inchides centrally-located recording" nd 'control'apparaus whereina recording'head is arrangedfor relative ling movement with respect to a moving're'cord', appar'atus comprising, in combination, a plurality of neindte dictators instruments each including a microphonajfirs't, second and third lines connecting'said instruments to aid recording and control apparatus, said andsecond lines serving as a communication circuit,'function centre! means connected to said second and third lines 'ando'perable when a D.-C. pathhas been establishedb ween 'said second and third lines at on'efof said instruments'l'a potentiometer coupled between said first and second lines at each of said instruments, one side of 5a 'tiometer being connected directly to said second ine, switch means at said instruments forTconn'fcting the movable arm of said potentiometer "to said thirdv to establish a-D.-C. path hetween'said second and lines, and operating means atjsaidjrecording app responsive to said function -control means for'fp ing a predetermined function whenever said switchrn ns is actuated to complete said D.'-C. path.

20. A remotely-operated dictation ,system ,which includes centrally-located recording and controhapparat us wherein a recording head is arranged for relative tr elling movement with respect to a moving record, apparatus comprising, in combination, a plurality of remo t e dl tators instruments each including a transdncen a munication circuit :for connecting ,said transducers, t o ,sa d recording and control apparatus and including fit ,t,..d second wires, a voice-signal circuit coupled tosaid communication circuit for feeding voice signals therein to said recording head, power supply means for producing cub rent flow in said communication circuit,, control means at, each. of said instruments forselectivelyestablishing two diiferent current conditions in said communication cir uit, firs an se curr t-energizable lmsiansseleictively actuable by said two current conditionsrespectively, first circuit means connecting oneterminal of ;s,aid. .first current-energizable means directly, to said first, communication circuit wire, second circuit means connecting one" terminal of ,said second. tcurre 'ilab elt 8:18

9 r3 S d se=Pn teom u fi0nsl qfiit wirea'thir circuit means connecting the other terminalsv of said first and second current-energizable means in balanced relationship to said power supply means, and operating means selectively under the control of said current-energizable means to establish predetermined control functions at said recording and control apparatus in accordance with the setting of said control means.

21. A remotely-operated dictation system which includes centrally-located recording and control apparatus wherein a recording head is arranged for relative travelling movement with respect to a moving record, apparatus comprising, in combination, a plurality of remote dictators instruments each including a transducer, a communication circuit for connecting said transducers to said recording and control apparatus and including first and second wires, a voice-signal circuit coupled directly across said first and second wires in symmetrical fashion and arranged to feed voice signals to said recording head, power supply means for producing current flow in said communication circuit, control means at each of said instruments for selectively establishing two different current conditions in said first and second communication circuit wires, first and second current-energizable means selectively actuable by said two current conditions respectively, circuit means for connecting said current energi'zable means in series and directly across said first and second wires ofsaid communication circuit in balanced relationship to said power supply means, and operating means selectively under the control of said current-energizable means to establish predetermined control functions at said recording and control apparatus in accordance with the setting of said control means.

22. A remotely-operated dictation system which includes centrally-located. recording and control apparatus of the type wherein a recording head is arranged for relative travelling movement with respect to a moving record, said system comprising, in combination, a plurality of remote dictators instruments each including a microphone, a communication circuit for connecting said microphones to said recording and control apparatus and including first and second electrically-conductive wires extending from said apparatus to said instruments, a voice signal circuit forming part of said communication circuit and arranged to feed audio-frequency signals from said communication circuit wires to said recording head, said voice signal circuit including first and second input connections, first circuit means coupling one of said input connections directly to said first communication circuit wire, second circuit means coupling the other of said input connections directly to said second communication circuit wire, said first and second circuit means having identical impedance characteristics whereby said voice signal circuit is coupled to said communication circuit wires in a balanced fashion, power supply means for producing current flow in said communication circuit wires, first and second relay means connected in series with both said power supply means and said communication circuit wires to be operated by said current flow in said communication circuit wires, control means at each of said instruments for selectively establishing two different current conditions in said first and second communication circuit wires, said first and second relay means being selectively actuable by said two current conditions respectively, and operating means under the control of said first and second relay means to establish predetermined control functions at said recording and control apparatus in accordance with the setting of said control means.

23. A dictation system as claimed in claim 22, wherein said voice signal circuit includes an audio transformer having a pair of primary windings, one terminal of each of said windings defining said first and second input connections respectively, and capacitor means coupling the other terminals of said windings together and serving to prevent the flow of direct current from said power supply means through said windings.

References Cited in the file of this patent UNITED STATES PATENTS

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