US 3524026 A
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Aug. 11,1970 M PNLANG'EN'DORF 'T L 3, ,0
REMOTE DICTATTQN APPARATUS WITH AUTOMATIC CONTROL TONE ELIMINATION Filed June 17. 1968 2 Sheets-Sheet 1 F IG. 1
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' e1 gas MOTOR DRIVER --v INVEN TORS MATTHEW P. LANGENDORF CHARLES L. RIDINGS WILLIAM H. SEBASTIAN ATTORNEY g- 1970 M. P. LANGE NDORF 3,524,026
REMQTE DICTATION APPARATUS WITH AUTOMATIC CONTROL TONE ELININATIQN Filed June 17. 1968 2 Sheets-Sheet 2 F IG. 3
AUDIO 16 v.0.c. I CUT RECORD TB INHIBIT FUNCTION 3,524,026 REMOTE DICTATION APPARATUS WITH AUTO- MATIC CONTROL TONE ELIMINATION Matthew P. Langendorf, Charles L. Ridings, and William H. Sebastian, Lexington, Ky., assignors to International Business Machines Corporation, Armonk, N.Y., a corporation of New York Filed June 17, 1968, Ser. No. 737,762 Int. Cl. Gllb 19/02, 27/02; H04m 11/10 U.S. Cl. 179-100.2 6 Claims ABSTRACT OF THE DISCLOSURE A control tone elimination system for use with a tone actuated dictation system wherein the control tones are within the audio range and are transmitted over the audio lines to the recording device. The tone elimination system effects the removal of those tones which are recorded on the record media prior to the recording of an additional audio message or the playback of a previously recorded message. The removal of the control tones from the media in no way affects the normal operation of the dictation system.
CROSS REFERENCES TO RELATED APPLICATIONS The following applications are all assigned to the same assignee as the present application.
U.S. patent application Ser. No. 699,259, entitled Dictating and Transcribing Apparatus With Automatic and Semi-Automatic Operator Controlled Facilities, Chester M. Fackler, Fred W. Johnson, and Bruno F. Wehmer, inventors, filed Jan. 19, 1968.
US. patent application Ser. No. 737,643, entitled Tone Actuated Dictation System, Thomas E. Dooley, inventor, filed June 1968, concurrently herewith.
U.S. patent application Ser. No. 737,497, entitled Tone Detection Circuit, Matthew P. Langendorf et a1., inventors, filed June 1968, concurrently herewith.
BRIEF BACKGROUND OF INVENTION Field The invention relates to a tone actuated remote dictation system and, more particularly, to a control tone elimination system for eliminating undesired control tones from the recording media.
Description of the prior art 'Prior art control tone actuated dictation systems generally conform to one of two broad ssytem configurations:
, tone controlled buffered systems and tone controlled nonbuffered systems. Buffered systems utilize an intermediate storage device for temporarily storing all audible messages received from the audio line. The received message is thereafter transferred from the temporary or buffer storage to a recording media. Such prior art buffered systems often have control circuitry associated therewith to eliminate tones which are recorded and temporarily stored by the buffer unit prior to their being recorded on the recording media. This control circuitry often consists of expensive detection circuitry which must first detect the presence of the tones stored by the buffer storage unit and prevent their transfer from the buffer storage to the recording media. Another prior art approach taken to eliminate audible control tones from both buffered and non-bufifered systems is to use a control tone with a frequency above the audio range. Thus, the control tone is recorded on the recording media but is not audible to the dictator or transcriber who plays back the record- United States Patent Patented Aug. 11, 1970 ing media. While such devices eliminate the necessity of complex circuits to eliminate the tone, they must still provide means to insure that a recorded control tone will not initiate an undesired function during playback. Additionally, such a system eliminates any audible feedback to the dictator as he causes the generation of the control tones. Further, such systems are incompatible with present day telephone tone generating equipment.
Another prior art approach to eliminate the playback of undesired control tones has been to record the control tones on the recording media and, thereafter, during playback, pass the audio signal through a highly tuned notch filter network to filter out the tones so that they are not audible to the listener. Because the relative speed of the recording media with respect to the playback transducer can vary from system to system thereby varying the frequency of the sensed tone, such notch filter networks have proved ineffective. Additionally, such notch filter networks are bulky and expensive to incorporate into modern day dictation systems.
SUMMARY In order to overcome the above problems and shortcomings of the prior art and to provide a tone free record of audio messages in conjunction with a tone activated dictation system, a unique tone elimination means is provided whereby those control tones which are recorded on the record media along with the desired audio message are automatically erased from the record at the time of recording. That is, the control tones which are transmitted by the dictator While the dictating device is recording audio messages are firstly recorded onto the record media. Thereafter, the control tone elimination system effects the erasure of the tone from the record media and positions the record media with respect to the recording transducer so that the audio message which is thereafter recorded by the dictator immediately follows the preceding audio message, thus eliminating any audio gap between the messages effected by the tone control circuitry.
Additional means are also provided to insure that those tones which place the dictating system into a record mode of operation are not recorded.
The foregoing and other features and advantages of the invention will be apparent from the following more particular description of the preferred embodiments of the invention as illustrated in the accompanying drawmgs.
In the drawings:
FIG. 1 is a schematic block diagram of a tone activated dictation system which incorporates the control tone elimination system of the present invention.
FIG. 2 is a schematic block and circuit diagram of the control tone elimination system of the present invention.
FIG. 3 is a circuit diagram of an alternate embodiment of the control tone elimination system.
Referring now to the drawings, and more particularly to FIG. 1 thereof, a block diagram of a tone activated dictation system which incorporates the control tone elimination system of the present invention is depicted. The tone activated dictation system comprises a telephone subset 11 which is utilized by the dictator who is physically located at a location remote from the recording or dictating device. The telephone subset has associated therewith a plurality of tone generators which are activated upon the depression of corresponding numbered buttons 13 located on the telephone subset. As will be described, the dictation system is responsive to tones generated at the telephone subset to perform various functions normally associated with the dictation and recording of audio messages. Thus, the dictator is 3 able to control the dictation system by depressing an appropriate numbered button. Both the audio message dictated by the dictator into the telephone subset and the tones generated by the tone generator are transmitted in a normal manner by a communication channel to the telephone exchange 17 and thence to the remote dictating system by a communication channel 19. Interface 21, located at the remote dictating location interfaces the communication channel '19 wih the dictation system 23 and insures the proper ring up and seizure procedures as well as performing various other housekeeping functions. The interface 21 provides an audio signal output which includes the audio message to be recorded and the control tones to the dictation system 23 over the communication channel 25. The control tones are sensed by a tone detector 27 which provides output signals to control logic 29. The control logic provides output signals to the motor control logic 31 and to the dictating device 33. The motor control logic controls the relative motion of the record media with respect to the audio transducer. The control logic provides signals which determine the modes (e.g., playback, record, stop), and various functions (e.g. letter lock, attendant required) to be performed by the system.
The audio message from the communication channel is also transmitted to the dictating device 33 so that when it is in record mode, the dictating device records all of the audio including control tones presented by the communication channel 25.
The operation of the tone activated dictation system depicted in FIG. 1 is described in the aforereferenced concurrently filed copending application entitled Tone Actuated Dictation System. A d tailed description of a dictating device such as that generally denoted at 33 of FIG. 1 may be found in the aforereferenced copending application Ser. No. 699,259. A detailed description of a tone detector such as that generally denoted at 27 of FIG. 1 may be found in the aforereferenced concurrently filed copending application entitled Tone Detection Circuit.
As previously described above with respect to FIG. 1, the audio signal presented by communication channel 25 to the dictating device 33 contains both the audio message to be recorded and the control tones which are utilized by the system to initiate a desired system function. When the dictating device is in recorl mode, both the audio message and the control tone signals are recorded on the record media. In order to eliminate the control tones from the record media, a control tone elimination system which is depicted in alternate embodiments in FIGS. 2 and 3 is incorporated in the control logic 29 and the motor control logic 31.
Referring now to FIG. 2, a schematic block and circuit diagram of the control tone elimination system of the present invention is depicted. This system functions to reverse the direction of the record media after a control tone has been recorded and recognized while simultaneously effecting erasure of the record media as it passes under the recording transducer in the reverse direction. The media is reverse driven for a predetermined distance oorresponding to the distance over which the control tone has been previously recorded. Thereafter, the reverse motion of the media is halted with the meida located in a relative position with respect to the recording transducer to receive and record a subsequent audio message.
For the purposes of the description which follows, it will be assumed that the tone detector has detected a tone which has placed the system in record mode. When such a tone is detected, a signal is provided which sets the record mode latch 41. This effects the gating of OR circuit 42 and also causes. the record media 43 to move with respect to the recording transducer 45 in the recording direction. OR circuit 42 gates recording oscillator 46 which provides a recording signal to transducer 45.
In order to eifect media motion, the output of the record mode latch 41 is supplied to OR circuit 47 which provides an output signal to coincidence circuit 49. Coincidence circuit 49 is gated by the inverted output signal of motor reverse latch 51. Since the motor reverse latch is normally oif, coincidence circuit 49 provides an output signal to the current driver 53 whenever the record mode latch is set. The current driver pumps current from the base of transistor 55 turning it on and thereby allowing the voltage at the emitter electrode 57 of the transistor 55 to be reflected at point 59 in the collector circuit of the transistor. This voltage is applied to one terminal of motor 61. The opposite terminal of the motor is connected to point 63 which in turn is coupled to the collector of transistor 65. The base electrode of transistor 65 is coupled to motor speed control circuit 67 which in turn is coupled to the motor tachometer 69'. The tachometer and motor speed control circuit insure uniform recording speed of the dictating device. The motor is connected to belt drive 71 which in turn drives the record media 43 past the recording transducer 45. The motor speed control circuit 67, motor tachometer 69, motor 61, recording transducer 45 and belt drive 71 all are encompassed in the dictating device and reference is made to the aforereferenced application Ser. No. 699,259 for a detailed description thereof.
When the dictator desires to change the mode of operation, for example, from record mode to playback mode or desires to cause the system to perform a specific function, for example, a letter lock, he causes a corresponding tone to be generated which is recognized by the tone detector. Since the tone detector requires finite time to recognize and hence detect the tone thus transmitted, a portion of the tone is recorded by the transducer 45 onto the record media 43 before the tone detector recognizes the tone. In order to eliminate the recorded tone, the output signal of the tone detector is utilized to initiate a tone erasing operation.
The tone recognition signal is supplied by the tone detector tothe coincidence circuit 73. Coincidence circuit 73 gates the recognition signal with the in-phase output of the record mode latch to thereby set the motor reverse latch 51. The output signal of the motor reverse latch is applied to delay '75 to thereafter reset record mode latch 41. Delay 75 eliminates a latch race condition which would otherwise be present between the motor reverse latch 5-1 and the record mode latch 41. When the motor reverse latch sets, the gating signal to coincidence circuit 49 is removed thereby turning off current driver 51 which in turn removes the positive voltage potential from point 59 thereby causing the motor to stop rotating in the forward direction. Simultaneously, the output signal of the motor reverse latch 51 is applied to turn on current drivers 77, '79 and 8% Current driver 77 pumps current from the base of transistor 81 turning it on which causes point 63 to go positive. Additionally, current driver 77 pumps current into the base of transistor 83 turning it on and thereby providing a current path to ground from point 59. Thus, the polarity of the voltage applied to motor 61 is reversed when the motor reverse latch 51 is set. The reversal of polarity causes the motor to reverse the direction of drive to the belt drive 71 thereby reversing the relative motion between the record media 43 and the recording transducer 45.
As noted above, the output of the motor reverse latch 51 is also applied to current driver 84} which insures that transistor 65 is turned off thereby preventing a leakage path of the positive voltage at point 63. Additionally, the output of the motor reverse latch is applied to OR circuit 42 to thereby gate the recording oscillator 46. The recording oscillator causes an erase signal to thereafter be applied by the recording transducer 45 to the record media 43.
Thus, as described above, the recognition of a control tone when the dictating device is in record mode causes the record media to reverse to its direction of travel past the recording transducer and also causes the recording transducer to apply an erase signal to the media as the media travels in the reverse direction. In order to prevent the erase signal from obliterating a previously recorded message, it is necessary to turn off the erase signal after the previously recorded tone has passed the transducer. Additionally, it is also desirable to stop the system prior to performing the mode change or function designated by the control tone. In the description which follows, the circuitry which stops the dictating device and turns off the erase current to the transducer will be described.
When the belt drive 71 has moved through a predetermined angle, a position contact switch 85 provides a signal to contact converter 87. The position contact switch may be of any suitable form such as, for example, a slip spring mounted to the belt drive shaft which is driven against a stop during rotation in the forward direction and which is carried with the shaft when its direction of rotation is reversed to make contact with a fixed switch member. Once the position contact switch makes indicating that it has travelled a fixed distance in the reverse direction, the output signal supplied to the contact converter 87 causes the contact converter to supply a signal which resets the motor reverse latch 51. The fixed distance travelled by the switch in the reverse direction corresponds to the maximum length of record media which may contain a control tone. The length of media in turn corresponds to the time it takes for the tone recognition logic to provide a tone recognition signal and upon the speed of the media with respect to the transducer.
When the contact converter resets the motor reverse latch 51, current driver 77 no longer pumps current to the base of transistor 73 and from the base of transistor 81 thereby removing the positive potential from terminal 63 and the ground path from terminal 59 through transistor 83. Further, the input signal to OR circuit 42 is removed thereby degating the recording oscillator 46 which precludes recording head 45 from recording further signals onto the recording media 43. Additionally. when motor reverse latch 51 resets, coincidence circuit 49 is again gated. The output signal of the contact converter 87 is applied to OR circuit 47 and thence to coincidence circuit 49 which gates current driver 53 On. This causes a positive potential to be applied to terminal 59 in a manner similar to that described above when the record mode latch was set. This positive potential thus applied effects positive braking of the motor by causing it to be driven once again in a forward direction. As the motor thus moves in a forward direction, belt drive 71 moves in the forward direction carrying with it the position contact switch 85. When the position contact switch 85 breaks contact, OR circuit 47 is degated thereby degating the current driver 53. When the current driver 53 is degated, the positive potential is removed from point 59 and the system comes to rest. Since both the record mode latch 41 and the motor reverse latch 51 are not set at this time, OR circuit 42 is not gated and thus the recording oscillator is degated thereby preventing the recording of sound by the recording transducer 45 onto the recording media 43. Thus, any control tones thereafter received while in the stop position are not recorded. However, it is to be noted that the control tones thereafter received can be recognized by system to eifect the function correspond ing to the control tone.
Referring now to FIG. 3 of the drawings, a control tone elimination system incorporating additional means to prevent the control tone which places the system into record mode from being recorded is shown. Additionally, an electronic timing device is provided in lieu of the position contact switch described with respect to the tone elimination system of FIG. 2. In operation, the tone recognition logic provides a signal to the base of transistor 101 whenever a recognized tone is present which thereby causes transistor 101 to turn off. Transistor 101 remains off as long as the tone signal is present. The turning off of transistor 101 provides an audio out signal to terminal A which is utilized by the dictating system to decouple the audio line from the recording transducer. If the dictation system were in a stopped mode and if the dictator desired to place it in a .record mode, he would cause an appropriate tone to be generated. Since the tone duration is a function of the time during which the dictator depresses the tone generation button and since the tone detector may supply a signal to start recording prior to the dictators release of the tone generator button, the terminal portion of the tone would be recorded unless the system provided a proper interlock. Transistor 101 provides such an interlock by providing an audio cut signal for the duration of the terminal portion of the record mode tone.
When recording, the circuit depicted in FIG. 3 functions in a manner similar to that described above with respect to FIG. 2. That is, the circuit of FIG. 3 causes the direction of the motor which drives the recording media to be reversed. Thereafter, an erase signal is caused to be recorded on the media over the previously recorded tone signal. Once the previously recorded tone signal has thus been eliminated, the system comes to rest.
When in record mode, transistor 103 is turned on by the 16-volt DC record signal at terminal B. This 16-volt signal is also applied to terminal D of motor 105 which, in conjunction with the signal applied to terminal E of the motor and terminal C connected to the motor control circuit, causes the motor to be driven in a forward record direction. Additionally, the output of transistor 103 is utilized to turn transistors 107, 109, and 111 off.
When a tone is recognized, the tone recognition circuit provides an input to the base of transistor 101 which provides an audio cut off signal at terminal A as described heretofore. Additionally, the output signal of transistor 101 gates coincidence circuit 113 which is also gated by the output of the record mode latch thereby firing single shot 115. Simultaneously, the 16-volt DC record signal applied at terminal B is removed thereby turning transistor 103 off. The output signal from the single shot 115 turns on transistors 117 and 119 for the duration of the single shot. The output of transistor 117 is utilized to inhibit reverse scanning, forward scanning, and playback functions for the duration of the Single shot. Transistor 119, in conjunction with the off output of transistor 103 turns on transistors .107, 109, and 111 which in turn cause motor 105 to reverse in a manner similar to the motor reversal described with respect to FIG. 2. Thus, the voltages applied at terminals .1) and E to the motor 105 are reversed by the action of transistors .107, 109, and 111. Additionally, transistor 111 drives an erase oscillator at terminal F which obliterates the tone which was recorded on the media. When the single shot 115 times out, transistor 119 cuts off thereby turning ofl. transistors 107, 109, and 111 which in turn remove the voltage from terminals D and E of the motor 105. Additionally, transistor 117 turns off removing the inhibit function signal thereby allowing playback to proceed if a playback tone signal was received.
OPERATION Referring once again to FIG. 1, a brief summary of the operation of the control tone elimination system in conjunction with the operation of a tone activated dictation system will follow. The dictator is located a remote location from the dictation system 23 and dials up the dictation system by utilizing a telephone subset 11. Once the dictator seizes control of the dictation system under the operation of the telephone exchange 17 and the control interface 21, he is ayle to effect control over the various operations performed by the dictating device 33 by utilizing the control tone generating buttons 13 located on the telephone subset 11. Thus, by depressing an appropriate control button 13, the dictating device 33 is placed into a record mode, a playback mode, a forward or backward scanning mode, or a stop mode. Additionally, the dictator may cause special functions to be performed such as letter lockouts, etc. that are normally associated with such devices. When in record mode, audible sounds transduced by the telephone subset are recorded by the dictation device.
Referring now to FIG. 2, when a tone is transmitted which causes the system to be placed in record mode, record mode latch 41 is set. This latch causes transistor 55 to turn on thereby causing the motor 61 to rotate in a forward or record direction. Rotation of the motor in the forward direction causes the record media 43 to advance past the recording transducer 45. Additionally, the audio line is coupled to the transducer thereby causing audio messages transmitted by the dictator to be recorded. When the dictator is finished dictating, he depresses a tone generator button on his telephone subset to effect a change in mode. Since it takes a finite time for the tone detector system of the dictating device to detect the transmitted tone and to effect an audio cut-off, a portion of the tone is recorded by the transducer 45 onto the moving record media 43. Once the tone is recognized, the tone recognition signal sets the motor reverse latch 51 which resets the record mode latch 41. The setting of motor reverse latch 51 and the resetting of record mode latch 41 cause transistor 55 to turn off and transistors 83 and 81 to turn on. This effects a reversal of the voltage across the motor 61 thereby reversing the direction of motor rotation and the direction of movement of the recording media 43 with respect to the recording transducer 45. Additionally, the setting of motor reverse latch 51 gates on an erase signal through the recording oscillator 46 which is recorded on the record media 43 in the same physical position occupied by that portion of the control tone which was previously recorded. A mechanical switch 85 closes indicating that the record media 43 has travelled a predetermined distance corresponding to the maximum distance over which a tone could have been recorded. The signal provided by the switch 85 causes the motor reverse latch 51 to be reset and simultaneously turns on transistor 55. The resetting of the motor reverse latch turns off transistor 81 and 83. With transistors 55 conducting, the voltage applied to the terminals of the motor is again reversed causing the motor to move in a forward direction thus producing a dynamic brake. The voltage applied to the motor terminals is thereafter removed and the motor comes to rest. At this time, the position of the record media 43 relative to the recording transducer 45 corresponds to the position at which it is desirous to record the next audio message.
Referring now to FIG. 3, an alternate embodiment of the tone elimination system is depicted. The operational characteristics of this system are similar to that described above with respect to FIG. 2 except that the single shot 115 controls the time duration during which the motor 105 is reversed. Additionally, the tone recognition input is applied to the transistor 101 which effects an audio cut-off whenever a tone is recognized for the duration of the tone. This insures that the tone which causes the system to be placed in record mode is not recorded.
Both of the above embodiments heretofore described have effected the elimination of tones from the record media by reversing the drive direction of the record media and applying an erase current to the magnetic transducer during the reverse movement of the media. It is also possible to effect the elimination of the tone on the media by moving the transducer relative to the media. Thus, the recording transducer could be moved back the required distance relative to the media while simultaneously applying an erase current. In those dictating systems wherein the transducer moves relative to the media, the transducer drive could be reversed in a manner similar to that of the motor reversal described above. A still further method of eliminating the undesired control tones from the record media would be to supply an additional erase winding with a separate pole piece mounted at the rear of the recording transducer. The additional winding would be energized upon the recognition of the tone signal. Thereafter, the media would be moved relative to the recording transducer in the recording direction for the fixed increment thus obliterating the tone. The media could thereafter be repositioned if desired to eliminate the intermessage gap thus created.
A still further modification could be incorporated by adding an additional sensing winding with a separate pole piece mounted at the rear of the recording transducer. The output signal of the sensing Winding during reverse relative motion could be applied to tone detection logic and thus utilized to control the increment of reverse movement.
Various signals and messages have heretofore been described as being audible signals and messages. It is, of course, recognized by those skilled in the art that audible signals refer to those signals which are audible to the human ear generally within the range of 16 cycles per second to approximately 19 kilocycles per second.
While the invention has been particularly shown and described with reference to the preferred embodiments thereof, it should be understood by those skilled in the art that the foregoing and other changes in form and detail may be made therein without departing from the scope of the invention.
What is claimed is:
1. A recorded tone elimination system for a tone actuated audio recording system comprising:
a control tone generating device for generating audible control tones for controlling the tone actuated audio recording system;
an audio input device responsive to said control tone generating device and to audio messages to be recorded for providing an input signal representative of the control tones and the audio messages;
a recording transducer responsive to the output signal of said audio input device for providing an audio recording signal;
a recording media for coacting with the transducer to store a representation of said audio recording signal;
selectively operable erasing means for applying an erase signal to the recording media;
selectively operable motion means for effecting relative motion between the recording media and the transducer, and between the erasing means and the recording media, said means effecting relative motion in a first direction during the transducement of the audio recording signal onto the record media;
tone recognition means responsive to the output signal of the audio input device for recognizing the audible control tones and for providing output recognition signals representative of the recognized tones whenever the audible control tones are present for a predetermined time period;
control means responsive to the transducement of the audio recording signal onto the recording media and the output recognition signals for operating said erasing means to apply said erase signal to the recording media and for operating said motion means to effect relative motion between the erasing means and the recording media over that portion of the media storing a control tone for a distance corresponding to the relative distance travelled by the media with respect to the transducer in said first direction from the time the tone generator was activated until the time the tone was recognized by said tone detection circuit, said erase signal obliterating said stored control tone.
2. The recorded tone elimination system set forth in claim 1 further comprising second control means responsive to said tone recognition device for inhibiting the audio recording signal for the duration of the control tone.
3. The recorded tone elimination system set forth in claim 1 wherein said means for effecting relative motion elTects relative motion in a second direction opposite to the first direction under the control of said control means.
4. The recorded tone elimination system of claim 3 wherein "said means for effecting relative motion is operative upon said record media to move said media in said first and" second directions with respect to said transducer.
5. The recorded tone elimination system set forth in claim 4' further comprising second control means responsive to said tone recognition device for inhibiting the audio recording signal for the duration of the control tone.
6. The recorded tone elimination system of claim 3 wherein said means for effecting relative motion is operative on said transducer to move said transducer with respect to said media in said first and said second directions.
References Cited UNITED STATES PATENTS 4/1969 Blane l79--6 8/1967 Chang 179100.2
US. Cl. X.R. l796, 100.1