US2781508A - Intelligence transmission system - Google Patents

Description

Feb. 12, 1957 Filed May 1, 1952 E. E. SUCKLING INTELLIGENCE TRANSMISSION SYSTEM veer/m:

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[as/ace [f Shaw/1 g BY FM 0/?- WW Feb. 12, 1957 E. E. SUCKLING INTELLIGENCE TRANSMISSION SYSTEM 3 Sheets-Sheet 3 Filed May 1, 1952 INVENTOR Eusfare 1?. Sari/ 55f B Km J? MGM United States Patent INTELLIGENQE TRANSMISSION SYSTEM Eustace E. Suckling, Brooklyn, N. Y.

Application May 1, 1952, Serial No. 285,582

3 Claims. (Cl. 340-318) This invention relates to systems of intelligence transmission and particularly to systems for the remote reproduction of transmitted intelligence in the form of clearly visible and easily readable characters on the face of a cathode ray tube.

Systems relating to the remote reproduction of transmitted intell' e in the form of large visible characters have a espread utility inthe signaling art, and many devices directed towards this end, both mechanical and electrical, are well known. In general the mechanical devices known to the art are characterized by dial pointers, number wheels and like arrangements and are of limited utility because of their relatively slow operating characteristics, extensive space requirements, complication of construction, objectionable "limitations of distance over which the intelligence may be mechanically transtitted.

The older mechanical systems have, at the present day, been largely displaced by electrical systems which in general do not have the deficiencies, at least to the same extent, that characterize and limit the utility of the earlier devices. in electrical intelligence transmission systems the utilization of the cathode ray tube for the reproduction of the transmitted intelligence in the form of visible characters is gaining favor and is making inroads into the fields dominated by the earlier electrical systems which usually utilized banks of lights or similar arrangements selectively actuated for character or coded intelligence reproduction devices.

Intelligence transmission or display systems utilizing a. cathode ray tube for the reproduction of transmitted intelligence in the form of readable characters thereon all basically require the application of particularly shaped voltage waves to the vertical and horizontal deflection plates thereof in order to control the disposition of the cathode ray beam for the production of letters, symbols or other intelligence on the lace of the tube. In conventional cathode ray tube systems the required voltage Waves are usually generated by carefullycontoured rotatable capacitors in association with complicated switching mechanisms to effect the presentation of different characters on the face of the tube, and as such. are relatively expensive and are practically limited to the successive presentation of individual characters onthe full tube face. Oth r aptations of the basic cathode ray tube systems utilize a stepped horizontal positioningvoltage for the presentation of a plurality of characters on the face of the tube. However, inclusion of facilities for such type of presentation only adds further complications to the detrimental complications of the existent switching mechanisms as mentioned above. Moreover, present day electrical systems conventionally require auxiliary equipment of complicated nature to code or otherwise transform the intelligence to be transmitted into suitable electrical impulses preparatory to Wave form generation, which wave forms are of such character as to preclude or at least render impracticable, transmission thereof by conventional telephone or telegraphlines.

2,781,508 Patented Feb. 12, 1 957.

In addition to the above, present day device-s are conventionally limited to the successive presentation of individual or a plurality of individual characters at fixed locations on the face of the tube and do not permit the presentation of a continuity of sequentially reproduced intelligence adapted to move across the face of the tube so as to present a continuity of reproduced intelligence similar to that viewed by the eye when scanning a line of print.

This invention may be briefly described as an improved intelligence transmission system of simple and inexpensive construction for the remote reproduction of transmitted intelligence in the form of readily visible and easily readable characters continuously and sequentially presented on the face of a cathode ray tube, including method and apparatus for converting the intelligence desired to be transmitted into simple wave forms readily transmitta'ble over conventional telephone and telegraph lines, in conjunction with apparatus and methods for the remote reproduction of the transmitted intelligence on the face of a cathode ray tube utilizing an external synchronized horizontal sweep thereof as an integral and essential component of the controlling wave form applied to the horizontal deflection plates.

The primary object of this invention is the provision of an improved intelligence transmission system for the remote reproduction or. transmitted intelligence.

Another obiect of this invention is the provision of an improved intelligence transmission system wherein the transmitted intelligence may be continuously read as the reproduction thereof is continuously and sequentially dis placed across the face of a cathode ray tube.

Another object of this invention is the provision of an intelligence transmission system whereby the intelligence desired to be transmitted may be readily converted into form for transmission and is conveniently storable in said form.

Another object of this invention is the provision of means and methods for translating the intelligence desired to be transmitted into electrical impulses of simple wave form that may be readily transmitted over conventional telephone and telegraph lines.

Another object of this invention is the provision of methods and means for translating the intelligence desired to be transmitted into convenient form that permits remote reproduction thereof in continuous form and in motion if desired.

A further object of this invention is the provision of methods and apparatus for the production of particularly shaped and contoured wave forms that are adapted to be combined with the locally generated cathode ray tube horizontal sweep voltage at the receiving station to generate a composite controlling wave form for intelligence reproduction purposes.

Other objects and advantages of the invention will be pointed out in the following disclosure and claims and illustrated in the accompanying drawings which disclose, by Way of example, the principles of the invention and the presently preferred embodiments of the intelligence transmission system applying those principles.

Referring to the drawings: I

Fig. 1- schematically illustrates the essentials of a transmitter and receiver unit constructed in accordance with the principles of the'inventiori;

Figs. 2a through 2 d schematically illustrate the wave shape contours of the components of the cathode ray tube deflection voltages for the production of an example character;

Fig. 3 schematically illustrates an alternative construction fora transmitterunit; and

Fig. 4.is a schematic illustration of the essentials of apparatus suitable fortpreparation of a transmitting tape including a schematic circuit diagram of a ratio modulation circuit as utilized in the unit.

Referring to Fig. 1, there is illustrated a receiver unit designated A including a conventional cathode ray tube provided with vertical deflection plates 12 and 12a, horizontal deflection plates 14 and 14a and a beam intensity control grid 16. In the illustrated tube the deflection plates 12a, 14a are grounded forthe purpose of simplicity of explanation. Connected to the vertical deflection plate 12 is an amplifier 18 of conventional construction for suitably amplifying the vertical deflection voltages applied to said plate 12. Similarly connected to the ungrounded horizontal deflection plate 14 is a mixing network 20 adapted to receive the output voltage wave form of a horizontal sweep generator 22 and the transmitted horizontal deflection voltage wave form as amplified by a conventional amplifier 24 and provide a composite horizontal deflection voltage wave form for application to said plate 14. In order to control the intensity of the cathode ray trace for blanking purposes intermediate sequentially presented characters and where desired in the formation of certain characters, the intensity control grid 16 is connected to an amplifier 26 adapted to amplify the transmitted blanking signals prior to ap- I output of the sweep generator 22 and the transmitted and contoured wave form as amplified by the amplifier 24. The polarity of the transmitted wave form amplified by the amplifier 24 is such as to oppose the conventional left-to-right displacement of the cathode ray beam produced by the saw-tooth wave generated by the sweep generator 22 and the transmitted horizontal wave forms are readily produced of such contour and amplitude so as to equal or overcome the sweep voltage and thus cause the trace produced by the cathode ray beam to remain motionless or to be displaced, if desired, from right to left. This method of controlling the horizontal position of the trace readily permits the reproduction of the transmitted intelligence in clear and distinct characters of any desired configuration including scriptv The utilization of a composite horizontal deflection voltage for character reproduction is illustrated in graphical form and for the purpose of example in Figs. 2a through 2d for the production of the letter A on the face of the cathode ray tube. figuration of a portion of the horizontal sweep voltage output of the sweep generator 22. The voltage wave 28, illustrated with the amplitude thereof plotted against time, is the conventionally used saw-tooth wave form.

Fig. 2b in a similar manner graphicaly illustrates the shape of the transmitted vertical deflection voltage 30 which, after suitable amplification in amplifier 18, is applied to the vertical deflection plate 12. Fig. 2c illustrates the contour of the transmitted horizontal deflection voltage 32 which, after suitable amplification in amplifier 24 is introduced together with the sweep voltage 28 into the mixing network 20 and the composite voltage output thereof is applied to the horizontal deflection plate 14. Fig. 2d shows the configuration of the trace produced by the cathode ray tube resulting from the application of the deflection voltages 28, 30 and 32.

For the purposes of example and to more clearly describe the operation of the device and the method of character reproduction employed therein, the formation of the letter A as illustrated in Fig. 2d from the wave forms illustrated in Figs. 2a through 20 will be described in detail. During the time interval t to application of the horizontal sweep voltage a l: and the vertical deflection voltage a b, result in a displacement of the trace 3}. from a to b. During the time interval to t,, appli- Fig. 2a illustrates the conall) cation of the horizontal sweep voltage b c and the vertical deflection voltage [7 c result in a displacement of the trace 34 from b to c. After the trace 34 reaches point 0, it is necessary to return the trace rapidly to point 0!. To accomplish this desired return of the trace 34 to point d, the negative polarity horizontal sweep voltage e o; is applied to the horizontal deflection plate 14 at time t in conjunction with the sweep voltage c and the resultant composite horizontal sweep voltage formed thereby relocates the trace 34 at the desired location a at the desired time t or immediately thereafter. During the subsequent time interval i to 1 application of the vertical deflection voltage 0 d, in conjunction with a composite horizontal deflection voltage formed by the sweep voltage c d and negative polarity horizontal deflection voltage cgi results in a displacement of the trace 34 from d to 0. During the subsequent time interval 1, to 1, application of the voltages d,e,, d e and ri e, results in the displacement of the trace 34 from c to 6 thus completing the reproduction of the desired letter A. At the time t, the removal of the horizontal sweep voltage e as illustrated by e g, results in a very rapid shift of the trace 34 from c to g leaving only a faint trace therebetween in contrast to the heavy trace utilized in the character formation.

The point g may then serve as the commencement of a new character, spaced from the preceding character by a faint interline, which, by prior adjustment of the trace intensity may be rendered less pronounced. In general the existence of faint interlines between two characters is not objectionable and does not detrimentally affect the clarity of the reproduced intelligence. If, however, the presence of any interlining whatsoever is objectionable, a simple wave form is easily produced for application, after suitable amplification in amplifier 26, to the intensity control grid 16 to completely blank out the faint interline or trace in the intervening space between successive letters.

The utilization of an intensity control Wave form is illustrated in Fig. 2e wherein maximum intensity is maintained during the time intervals utilized for character formation and the tube is momentarily blanked out coincident with the application of horizontal deflection voltages c304, and esgs.

Although the above described embodiment of the receiver unit A as illustrated in the drawings utilizes, for the purposes of simplicity and example, a single linear saw-tooth horizontal sweep voltage, it will be apparent to those skilled in this art that locally generated stepped horizontal positioning voltages could be utilized in conjunction with horizontal deflection voltage Wave forms representative of the algebraic sum of a saw-tooth horizontal sweep voltage and a contoured sweep cancelling voltage as illustrated in Figs. 2a and 20 for the example letter A. Either of these methods could be used in conjunction with suitably shaped vertical deflection and positioning voltages, to produce a plurality of lines of characters, one disposed beneath the other, on the face of the cathode ray tube 10 instead of a single line of characters described above for purposes of example. If de sired, vertical displacement of the reproduced characters could be readily obtained by suitably phased vertical positioning voltages.

Fig. 1 also includes an embodiment, by way of example, of simply constructed apparatus adapted for production of the desired wave forms for transmission purposes. There is provided a stationary cylindrical disc 40 having a smooth surface 42 of suflicient width to support a length of previously prepared magnetic tape 44 suitably coded to provide a predetermined and desired voltage wave form. The magnetic tape 44 is preferably introduced through the aperture 46, brought out to the surface 42 by means of the slot 48, disposed around said surface 42 as shown, and removed via said slot 48 and the aperture 50. If desired, for the production of moving characters on the face of the cathode ray tube, means,

such as a tapepulling device 52 are provided. to advance the tape 44 relative to said surface 42.

Axially mounted as at 56 on the disc is one end of a rotatable shaft 54, the other end of which is supported by a suitable supporting member such as the bearing block 58. Mounted on theshaft 54 is a suitable pulley 60 connected by a belt 62 engaging a driving pulley 6.4 driven by a motor 66. Mounted on shaft 54 and rotatable therewith is a pick-up unit supporting assembly 68 shaped to dispose a plurality of conventionally constructed magnetic pick-up heads 70 closely adjacent the tape 44 disposed on the surface 42 of the stationary disc 40 and, in position to rotatably scan said tape. The previously prepared tape 44 is magnetized in such a way, described in detail at a later point in this specification, that the pick-up heads 70 have voltages generated therein from which the vertical and horizontal deflection voltages and the blanking orv intensity control voltages required for control of the cathode ray can be reproduced.

In actual operation it is neither necessary nor desirable for the pick-up heads 70 to actually touch the tape 40. I have found that when using a modulation system and particularly the later described ratio modulation system that satisfactory signals are obtained if the magnetic pick-up heads 70 are disposed about fl inch away from ever the relative spacings may be ascertained without difliculty and is primarily an engineering or design problem.

In order to make readily available the electrical impulses. obtained from the continuously rotatable pick-up heads 70, the magnetic pick-up heads 70 are electrically connected to slip rings 72. fixedly mounted on the shaft 54 and rotatable therewith. Disposed against the surface of the slip rings 72 and in conducting relation therewith are a plurality of brushes 74 individually connected to a plurality of conventional video amplifiers '76 to provide an amplified output of the generated signals.

The output of the amplifiers 76 is then introduced into demodulating units 78 which are averaging circuits of the basic type described by R. R. Perron in the November 1950 issue of Electronics magazine. From the demodulators the original wave forms which were recorded on the length of tape being scaned are recovered each time the scanning assembly completes a 360 cycle. The three sets of wave forms, i. e. vertical and horizontal deflection voltages and the blanking or intensity control signal can then be transmitted on separate circuits or can be combined and transmittedby any suitable transmission means including conventional telephone lines.

The receiver system described at an earlier portion of this specification is operable with either an externally synchronized or accurately set free running horizontal sweep generaton It is preferred to operate with an external synchronizing signal but in the event such signal is obscured by noise orother interference, the device will be operable through careful control of the repetition rate of the sweep generator'at the receiving station. However, in order to provide a suitable signal for the external synchronization of the cathode ray tube horizontal sweep generator 22, the output voltage wave of which is utilized as a component of the composite horizontal deflection voltage supplied to the horizontal deflection plates 14, a contact member 84 is suitably located on the pick-up unit supporting assembly 68 so as to trip a switch arm 36 located adjacent the slot 48 in the cylindrical face 42 of the stationary disc 40. It is clear that each time ti the pick-up heads 70 rotate past the slot 48, the contact arm'84 will trip the switch arm 86- andthe actuation thereof may be conveniently used to actuate a pulse gen.- erator 88 the output of which provides a transmittable timed electrical impulse for synchronizing the output of the horizontal sweep generator 22 with the above described tape scanning system.

In operation of the device with the horizontal sweep generator 22 being externally synchronized by means of the synchronizing pulse generated by each revolution of the rotating scanning assembly and the tape 44 being stationary relative to the surface 42 of the disc 40, the resultant intelligence remotely reproduced on the cathode ray tube will remain stationary on the face thereof since the scanning unit permits'rotation at a sufiicient speed to cause the characters on the face of the tube to appear to be continuously present. If however the tape 44 is moved relative to said surface 42, the scanned material will continuously change and the remotely reproduced characters will be displaced across the face of the tube at a rate determined by the rate of tape advance relative to said surface 42. The permitted displacement of the tape relative to the surface 42 thus results in the permitted introduction of additional characters on the face of the cathode ray tube coincident with the removal of previously scanned characters at a rate determined entirely bythe rate of tape advance over the surface 42. The tape therefore can be of any length and the intelligence desired to be transmitted is in no way limited by the length of tape which of course may be reintroduced on the surface 42 of the disc. 40 for repeat transmissions and also may be conveniently stored for future use.

As described above, the embodiment of the transmitting unit illustrated in Fig. 1 is adapted for utilization of a previously prepared magnetic tape and this invention includes a simple and convenient method and apparatus for forming the transmitting tape. The essentials of the tape preparation unit for a single character are schematically illustrated in Fig. 4 and for simplicity of explanation, only the essentials of the tape preparation unit will be described, it being understood that other and more complicated embodiments utilizing the basic principles may be readily manufactured.

There is provided a typewriter-like unit having a key 94 adapted to actuate a type arm 96. Mounted on the end of the type arm 96is a thin metal mask 98 having a plurality of shaped apertures 100 disposed therein. Depression of the key 94 results in displacement of the type arm 96 moving said metal-mask 98 into and interrupting a beam of light generated by a point source 102 and received through suitableslits 104 in a masking element 106 disposed intermediate said point source 102 and a plurality of photocells 108. The apertures 100 in the metal mask 98 are contoured in accordance with the desired voltagewave forms required for the remote reproauction-of the desired character on the face of the cathode ray tube. The movement of the metal mask 98 across the-path of the beam of light generated by the pointsource 102 results in a progressive interruption of said beam and a progressive variation in the amount of light received by the photocells 108 in accordance With the configuration of the apertures 100. The variations in the light received by the photocells 108 result in the generation of a voltage Wave form therein corresponding to the desired wave shape as determined by the apertures 100 in the mask 8. Coincidently with the introduction of the apertured metal mask 98 across the beam of light, the displacement of the type arm 96 is also utilized to actuate a lever memher 110 to simultaneously advance the tape so as to synchronize the rate of tape advance with depression of the character key 04 and the rate of displacement of said mask 98 across the beam of light.

The electrical output of each of the photocells 108 is applied to aspecial ratio modulating unit to convert the photocell voltage output into the desired magnetization characteristic on the tape. For the purposes of example, the ratio modulation circuit associated with one of the photocells 168 will be described in detail. The voltage output of one of the photocells 108 corresponding to the intelligence desired to be stored on the tape, is connected to the grid 116 of tube 118. The cathode 120 thereof is connected in parallelwith the cathode 122 of the tube 124. The plates 132, of the tubes 118, 124 are connected to a common voltage supply through plate load resistors 126 an 123 respectively. The tubes 118 and 124 are arranged so that the input wave form applied to the grid 116 of tube 118 appears in magnified form at the plate 130 of tube 124 and apears in similarly magnified but inverted form in plate 132 of tube 118. Associated with the above described circuits are a second pair of vacuum tubes 134 and 136 connected as a conventional symmetrical multivibrator unit having the grid resistors 138 and 140 thereof connected directly to the previously described plates 13% and 132 of tubes 124 and 118 respectively. The values of the circuit elements forming the multivibrator must be such that the repetition frequency thereof is higher than the components of the modulating wave form in order to eifect faithful reproduction thereof. With no input wave applied to the grid of tube 118, the

plates 132 and 130 are at identical voltages and the output of the symmetrical multivibrator provides a wave form having equal mar and space durations. Upon application of a photocell output voltage to the grid 116 of tube 118, the plate voltage of tube 118 decreases and the plate voltage of tube 124 increases. The variation of plate potentials results in an accompanying variation in the mark to space ratio in the output of the multivibrator although the total cycle length thereof remains unchanged. The output of the multivibrator is then preferably applied to conventional squaring and shaping circuits schematically designated as 142, and the shaped output thereof is utilized to drive a power amplifier 144 and a demodulator 148. The output of demodulator 148 is connected to grid 150a of tube 124 for the purpose of giving negative feedback in order to improve the fidelity of the modulator system. The output of the power amplifier 144 feeds current into a magnetic tape recording head 7 146 so that during the mark time interval the recorder is magnetized in one direction, while during the space interval the recorder is magnetized in the opposite direction. By the above described means, the output wave form of the photocell is recorded on the magnetic tape as a ratio modulated wave.

All the embodiments of the invention as described above utilize a ratio modulated magnetic tape for control of the transmitter unit. However, other means for storing the desired wave forms, such as variations in transparency of a film or a paper tape, responsive to a photocell scanning system can also be used. Fig. 3 illustrates an alternative embodiment utilizing a photocell scanning system that is responsive to the variations in tape transparency. There is provided a stationary annular ring 150 having a smooth transparent surface 152 of sufiicie-nt width to support a length of previously prepared light transmittable tape 154. The tape 154 is preferably introduced to the annular ring 150 and surface 152 thereof by means of the diagonally disposed roller 156 and removed therefrom by means of the adjacent diagonally disposed roller 15$.

Axially disposed within the ring 150 is a rotatable shaft 160 having mounted thereon a scanning head supporting assembly 162. Mounted on the end of the scanning head supporting assembly and positioned adjacent the surface 152 of the supporting ring 150 are a plurality of point light sources 164. The light sources 164 are adapted to rotatably scan the tape 154 disposed on the surface 152 upon rotation of the shaft 160 effected by the drive assembly including the drive motor 166, pulley 168, belt and pulley 172 fixedly mounted on said shaft 160.

,lviounted on the rotatable shaft 160 and positioned thereon to continuously receive the light emitted by the rotating point sources 164 are a plurality of photocells 174 connected to amplifying units 186 which are in turn connected to the slip rings 188. Disposed intermediate the photocells 174 and the light sources 164 and rotatable in conjunction therewith is a masking element having a plurality of slits 182 included therein and positioned to limit the light received by the individual photocells 174 to that emitted by their respective point sources 164. In the absence of any tape disposed onthe surface 152 of the ring 15% light from the point sources 164 passes to the photocells 174 through said slits 182 in the masking unit 130. When tape of predetermined varying transparency or with suitably contoured apertures disposed therein is mounted on the surface 152 of the supporting ring 150 the wave forms represented on the tape are scanned by the slits 182 in the masking unit 180 during rotation of the shaft 160 with the light source, slit and photocell assemblies mounted thereon. Thus rotation of the shaft 160 results in the production of a varying potential output of the photocell corresponding in shape to the contour of the wave form recorded on the tape. The varying potential output of the photocells 174 is then preferably amplified in a preamplifier unit schematically shown as 186 and presented for removal at the slip rings 188. As described above in conjunction with the embodiment illustrated in Fig. 1, displacement of the tape 154 relative to the surface 152 will effect a corresponding displacement of the reproduced intelligence on the face of the cathode ray receiver tube.

In operation of the system, the number of characters or letters presented on the oscilloscope at any given time depends upon the number of characters which can be represented along the length of tape scanned in one scanning cycle. This length of tape is determined by the length of the scanned surface, which in the described embodiment is substantially circular, but which with other optical or mechanical systems could assume varied configurations.

If a seven inch diameter drum is used and one inch of tape is allowed for each character, then 22 letters or letter spaces will appear on the oscilloscope at any given time. If the scanning system is making ten revolutions in a second, then each letter or letter space occupies a time duration of 5 of a second in every scanning cycle. The generation of easily readable characters on the tube face under these specific operating conditions requires a reproduction of wave form frequency components up to about 1000 cycles a second for both the vertical and horizontal deflection voltages. Using conventional methods the above described two 1000 cycle bands can be disposed for transmission as a frequency spectrum having components between about 50 and 2500 cycles a second with an unoccupied space a few hundred cycles wide in the center of this band. The intensity signals are placed within this space as modulation of a 1200 cycle carrier. Spread of this carrier into the vertical and horizontal bands is unimportant as it occurs when no character signals are being transmitted. Synchronizing pulses occupy the whole band at the commencement of a'scan cycle when the band is not yet being used as the scanning heads have not revolved to the'point in their scan opposite to the first letter they will read 011. V

The utilization of the horizontal sweep voltage as a component of the composite horizontal deflection voltage applied to the deflection plates'14 in conjunction with the described method and apparatus for preparation of the transmitted wave forms obviates the need of any complicated switching mechanisms and other constructions that characterize the devices of the art and results in the reproduction of the transmitted intelligence in the form of characters having improved clarity, definition and readability. Moreover the system through its permissive simplification of structure also results in the utilization of simple'wave forms that may readily be transmitted over conventional telephone lines without detrimental distortion thereof and additionally may be readily formed and stored in a convenient manner.

In accordance with the provisions of the patent statutes, I have herein described the principle of operation of this invention, together with the elements which I now consider to constitute a workable embodiment thereof, but I desire to have it understood that the structure disclosed is only illustrative and the invention can be carried out by other means. Also, while it is designed to use the various features and elements in the combinations and relations described, some of these may be altered and modified without interfering with the more general results outlined.

Having thus described my invention, I claim:

1. In an intelligence transmission system a transmitting unit comprising a stationary tape supporting surface for supporting a length of previously prepared tape having the intelligence desired to be transmitted incorporated thereon, means positioned to repetitively scan the portions of said tape disposed on said supporting surface for providing electrical signals representative of the scanned intelligence incorporated in said tape and means responsive to said electrical signals for generation of transmittable signals representative of the scanned intelligence.

2. The combination as set forth in claim 1 including means for effecting relative motion between said tape and said stationary tape supporting surface independent of said scanning means.

3. An intelligence transmission system for the visual presentation of a displaceable continuity of transmitted intelligence on the face of a cathode ray tube at a location remote from the source thereof comprising a stationary tape supporting surface for supporting a portion of the length of a previously prepared tape having the intelligence desired to be transmitted incorporated therein, displaceable means positioned to repetitively scan the portions of said tape disposed on said supporting surface for providing repeated electrical signals selectively representative of the deflection voltages required to visually reproduce the scanned intelligence at said remotely located cathode ray tube and means permitting displacement of said tape relative to said supporting surface at a rate appreciably less than the rate of displacement of the scanning means coincidently with the scanning thereof to provide a scanning means output representative of the displaceaole continuity of scanned intelligence.

References Cited in the file of this patent UNITED STATES PATENTS 1,870,989 Eldred Aug. 9, 1932 1,941,618 Nemirovsky Jan. 2, 1934 2,165,307 Skellett July 11, 1939 2,359,617 Bryce Oct. 3, 1944 2,369,662 Deloraince et al Feb. 20, 1945 2,408,049 De Rosa Sept. 24, 1946 2,424,218 Begun July 22, 1947 2,429,787 Young Oct. 28, 1947 2,511,121 Murphy June 13, 1950 2,539,837 Howell Jan. 30, 1951 2,552,761 Baker May 14, 1951 2,556,640 Baker June 12, 1951 2,560,474 Potts July 10, 1951 2,561,476 Lang July 24, 1951 2,594,731 Connolly Apr. 29, 1952 2,628,539 De Neergaard Feb. 17, 1953 2,656,415 Terlecki Oct. 20, 1953 2,657,377 Gray Oct. 27, 1953 2,657,378 Gray Oct. 27, 1953 FOREIGN PATENTS 986,473 France Aug. 1, 1951

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