US2172936A - Television control system - Google Patents

Description

Sept. 12, 1939. A. N. GoLDsMrrH TELEVISION CONTROL SYSTEM Filed July 9, 1957 2 Sheets-Sheet 1 l lNvENToR l LFR GOLDSMI TH BY ATTORNEY Sept. 12, 1939. A. NS GoLDsMlTH 2,172,936

TELEVISION CONTROL SYSTEM Filed July 9, 1957 2 sheets-sheet 2 ,BAC/(GROUND Fakes/zown INVENTOR ATTORNFY letented Sept.' 12, 19739 UNlTED s'la'rllsV .PATENT osi-lcs Application July 9,l ias'z, serial No. 152,740

vl() Claims.

This invention relates to a system for producing composite pictures particularly las ap-v plied to television 'systems wherein it is desired V to combine two or more images to produce a picture having thel objects superimposed in a particular manner.

In the production of television pictures, it is not always feasible or possible to have available all of the natural settings necessary to produce l0 the particular results desired in conformity with the studio production being given, and for this reason it becomes necessary to produce 4the deproduced using a portion or all of the still or moving picture scene with the actors or foreground scene superimposed thereon.

One object of the invention is, therefore; to provide means, for producing composite pictures wherein the foreground, background or any other plane of action may'be combined to produce a single picture having the particular desired portions of each of the separate scenes.

A further purpose of the invention is to provide means whereby a portion of the desired scene may be derived from a still picture or a moving "ppicture lm, the remaining portion being suppilied from material or persons within the studio. y Another purpose of the present invention is to lprovide means whereby each of the diierent individual scenes to be fabricated may be scanned individually and the electrical impulses or signals derived therefrom combined in a particular 40 manner und .r the controlling purely electrical means. y i

A further piurpose of the invention is to provide a system iwherein it is possible to place the actors in the fioreground or background or any other plane of iactiorr and so combine the signals derived fronti scanning the separate scenes as to produce a realistic and natural appearance when the video siginals resulting from scanning each separate e1d"-of acting are combined as will hereinafter be eirplained and from the combined signals or composite picture is reproduced as an electro-optical representation at desired receiving or monitoring points. A further purpose of the invention is to pro- .55 vide means whereby the combining o f the sepl (Cl. 17E-7.2)

arate portions of thescenes and the contours or boundaries of the portions so combined are sharp and well defined in order that ghost-like images .over a portion of one or more of the scenes or along the lines of demarcation between 5 the portions of thescenes may be prevented.

A still further purpose of the invention is to provide a means whereby the means for producing sharp denition of the composite picture may be` adjusted in orde'r that the inherent delays in the operation of the system may be propv erly and suiciently compensated for.

A still further purpose of the invention is to provide means whereby the scanning of the separate views may be carried on independently and simultaneously but may be controlled by appropriate electrical means so that scansion takes place in what is, in effect, aslightly out-of-phase operation.

Still `further objects of the invention `will be come apparent and at once suggest themselves to those skilled in the art 'to which this invention isl related, by reading the following specilication and claims, particularly in connection with the drawings, in which:

Fig. 1 illustrates a system for producing composite pictures and for assuring sharp denition of the resulting composite picture,

Fig. 2 represents schematically a plurality of object areas and illustrates the inherent delay in the operation of a portion of the system, and

Fig. 3 shows a manner in which a plurality of views may be superimposed. e.

In Fig. 1 is shown a plurality of object areas ll, I2 and I3. These areas represent respectively the foreground, intermediate or middleground, and background of a picture that is to be combined to produce one single composite picture. Each of these separate object areas are individually scanned to produce independent series of signalv impulses. These scanningv systems are preferably in the form of cathode ray tube scanning devices, of the type described and disclosed by V. K. Zworykn in the Journal of the Institute of Electrical Engineers (British), vol. '73, Number442 for October, 1933, on page 440 et seq, as well as the Proceedings of the Institute of Radio Engineers for January 1934, and further illustrated by 'his Patent Number 2,021,907. assigned to Radio Corporation of America or the 50 pending application of V.4 K. Zworykn, Serial No. 732,750. The scanning devices have not been shown in detail, but it-is to beunderstcod that each includes a photosensitive mosaic-(prepared, Y

for example, as disclosed in U. S. Patents No.

2,020,305 of November 12, 1935, and No. 2,065,570 of December 29. 1986) upon which the object area is projected, with an electrode associated therewith from which electrical impulses may bederived. Each ot the scanning devices also include means. such as an electron gun, for producing a cathode ray beam and separate means for causing `vertical .and horisontal deflection of the beam in order that the mosaic electrode upon which the optical image is cast may be systematically scanned. Each of the scanning devices also includes a control electrode element for controlling the intensity of the beam 'as generated by the electron gun. v

time in each of the scanning devices, all of the vertical deecting means I1 of the scanning devices Il, I5 and I5 are connected in parallel.

'Ihe signal impulses as produced by each of the scanning devices are ampliiied by appropriate video frequency ampllers 2l, I5 and 26 which may be oi' the general character shown by United States patent of'J. P. Smith, No. 2,045,315', or A. C. Stocker, No. 2,045,316, for exarnple,which are individual to the particular scanning devices Il, I5 and I6 respectively. Theoutputs of the video frequency amplifiers are connected to a combining amplifier 36 and the output of this amplifier,

together with the output of the synchronizing signal amplifier and the oscillator 3| are' fed to a modulator 32 which, in turn, supplies modulated radio frequency oscillations to a transmitter ampliiier 83 to which the aerial network for the television broadcast system is connected.

With the system as so far` described, and with each ofthe scanning devices operating, there will appear at the modulator a series of impulses or signals corresponding to the combined impulses `of all ofthe scanning devices. impulses or signals were transmitted the result would be a ghost-like appearance of the separate views at thereceiving apparatus. In order to prevent this, means are provided for suppressing the signals as generated by the intermediate and background scanning devices whenever an object is being scanned by the foreground scanning device Il. A similar means is also provided for suppressing the signals as generated by the background scanning device I.5 whenever an object is being scanned by the intermediate scanning device I5. These means comprise the amplifier and grid control units Il, l5 and 36. The input of the first of these units is connected to the output of the scanning device Il so that whenever an object is vbeing scanned by this scanning device (which is assumed to be associated with the foreground)- an output will appear at the amplier 34. 'Ihe output of the amplifier and grid control unit 3l is connected to the control grid 2| of the scanning device I5. A similar amplifying and grid control unit $6 is connected to the output of the scanning device Il and the output of this amplifier is connected to the control grid 22 of the scanning device I 5.

amplifier and control devices 34 and 36 supply a voltage to the grid control elements ZI and 22 of the scanners I5 and I6, respectively, in order that the operation of these scanners will be blocked If this train of Whenever there is a pres- -ence of signals from the scanning device I4, the

and, as a result, no signal output will be present from these scanning devices. Likewise, an amplitier and grid control unit 35 is connected to the output of the scanning device I5 which in turn controls the potential of the control grid 22 of the scanning device I5, Because of this unit the presence of signal current from the scanning device I5 blocks the operation of the scanner Il so that no signal impulses are supplied tothe video frequency ampliner 26 whenever signals are present as a result of scanning the intermediate or middleground field.

From the above description, it may be seen Vthat-the presence of an object before the scanning device Il and the scanning of this object will suppress the operation of both of the scanning devices I2 andv I I associated with the intermediate and background area. Likewise, the scanning of an` object in the intermediate area will suppress the operation of the scanner associated with the background area.

In actual operation, it has been found that in using the system as so far described a certain amount of fuzzlness or ghost-like appearance is present along the side boundaries of objects appearing in the diiferent action planes of the composite picture, that is, the line of demarcation between objects in the foreground and objects in the intermediate or background is not sharp and well dened. This fuzziness or ghost-like appearance along the sides of the separate elements of the composite picture is a result of inherent delays in the operation of the ampliiier and grid control unitsand in the circuits associated therewith. Theoretically, as soon as scanning begins on an object in the foreground, the signals from the intermediate scanner should be immediately eliminated, but in view of the rate, at which the scanning is carried out, and the unavoidable electrical lag in the control circuit, the suppression ofthe signals from the intermediate scanner is not immediate. 'Ihis fact may best be explained by referring to Fig. 2 `in which the foreground area being scanned is represented at II, the intermediate or middleground at I2 and the background at I3. Let it be `assumed that the particular line element being scanned in each of the views is represented at II, l2 and l! respectively, and that the particular element of the line II in the `foreground area that the beam is scanning at the particular instant is atpoint 44. Suppose that at this instant an object is encountered in the foreground area and as aresult a train of signals will start from the scanner Il] vice is. .Before the control unit u 11a-finiti` time to take effect on the scanning device.. 'I 5 and prevent the development of a beam therein, the scanning operation will progress a point, for instance, as designated at 45. ng the time between the points u and u iii-tile intermediate area, signals are being supplied to the modulator from both the foreground and intermediate areas due to the lag and delay in opeiyation of the control unit Il and during this interval double images will be produced resulting in ghost-like image. The same situation is also vresent with respect to the background area, the me required for the scanner I5 to be blocked /corresponding to the distance between points d'5 and 45 in the background area I3 of'Flg. 2./

In order to compensatie for the inherent delay in the electrical control circuit means are provided whereby the operations of the separate scanning' devices `Il. II and I3 lare not in exact synchronism and phase. 'Ihe horizontal are suitable for this purpose and one form is schematically shown by the drawings although many other forms are shown by the Bell System Technical Journal for July 1928, commencingl on page 512 et seq., as well as in "Communication Networks, Volume II, by Guillemin, by John Wiley 3: Sons, New York. A ar delay network 38 is also connected between the horizontal deiiecting impulse generator 28 and the deilecting means 20 of the scanning device I3.

These delay networks 31 and 33 are adjustable in order that the very slightdelay in the scanning of the intermediate and background areas may be varied in accordance with the inherent delay in the amplifier and grid control units connected to the two scanners.

By the use of these two delay networks it will be seen, therefore, that the intermediate and background scanning devices I5 and I6 will be caused to operate effectively in synchronism with the foreground'scanner and that the background scanner I6 will be effectively caused to operate in synchronism with the intermediate scanner I2. When the delay networks 3l and 38 are properly adjusted the cut-oil' or suppression of operation of 'the intermediate or background scanners will take place at an instant corresponding to the exact instant at which the foreground scannnig device begins to produce signals as a result of the scanning of an object in the foreground. When these elements are used, therefore, the slight fuzzy or ghost-like appearance along the sides of the foreground objects which are superimposedvon an intermediate ground or along the sides of an intermediate object which is superimposed over a background object, is eliminated with the result that the picture as received in the receiving apparatus is clear and more realistic.

It has been found that this ghost-like appear- 'ance does not 4occur at the top and bottom of superimposed views and the reason for this is obviously because of the fact that the scanning is in a horizontal direction .and that the delay in the control units is materially less than the length of time required for the scanning devices to scan one line element of area. However, if these effects should become evident in pictures having a materially increased number of lines or a higher scanning rate, they can be eliminated by the methods herein disclosed.

Although the separate delay networks 3l and 38 are individually connected to the horizontal signal generator it is obvious that these networks maybe connected in tandem, in which case the input to the delay network 38 would be connected to the output of the delaynetwork 31.

Furthermore, the amplier and grid control units and 36 are shown as individual and separate units. units may be combined into one unit, the input of which is connected tothe signal output of both of the scanning devices Il and I5 in an appropriate manner, and the output of which is conarnese It is conceivable that these twonected to the control grid r22 of the scanning device II.

Pig. 3 is included for the purpose of showing one manner-in which three separate planes of action may be combined. While foreground Il is being scanned. the portions of theintermediateand background lying directly behind the particular spending to f the l.intermediate or background.

planes. 4Illor-` instance, it may be desired to `show a person walking behind a hedge, and in front'of a wooded area. In such an instance, a illm or other picture could be produced for supplying the hedge. A separate and' independent illm or pic-` ture could also be produced for supplying the wooded background. In producing the composite picture, these two illms would be scanned separately and simultaneously by the scanning devices Il and I6, while the scanning device l5 would be used to scan the particular actor as he walks across the television studio. When the signals from the three separate scanning devices are combined, the resulting composite picture is that of a person walking behind a low hedge with a wooded areay as a background. By placing the foreground and background portions of the composite picture on moving picture films as in this particular example, the material necessary in the studio for producing the desired composite effect would be no more than the mere presence of the actor.

It is also to be understood that. so far as this invention is concerned, it is not necessary that the scanning devices be controlled by means of their grids but instead the signals from the par-- ticular scanning devices may be suppressed by making'inoperative their associated video frequency amplifiers through appropriate grid biases or, in fact, by any other means whereby the desired results may be accomplished.

Many other modifications and changes in the invention and its application .to other ilelds of use will of course become apparent to those skilled in the art and it is therefore intended that the invention shall be construed in a broad lscope and shall read upon all modifications such as fall fairly within the spirit and scope of the disclosure and of the hereinafter appended claims. What I claim is:

l. In a composite television system wherein background and foreground areas are provided, means for separately and independently scanning the two areas to produce separate series of video signals, means for reducing4 the signal level of the series of signals resulting from the background scanning operation during time periods of presence of signals in the series fromthe foreground scanning operation, means for delaying the scanning operation of the background area by an amount equal to the inherent time delay in the operation of said `background signal reducing means, and means for producing from the signals representing the foreground area and the controlled level background area signals in a single series of signals representative of the combined background and'foreground areas lwhereby the delay means may insure proper matching of v`foreground will be suppressed. Likewise, when" pictures wherein foreground, middleground and background areas are provided. means for separateLv and simultaneously scanning each of the areas to produce separate series of video signals,

means for suppressing the signals from the middleground and background areas when signals are produced from v,the scanning of the foreground area, means for suppressing the signals from the background area when signals are produced from the .scanning of the middleground area, means for delaying the scanning operation of the middleground and background scanning means by an amount equal tothe inherent timel delay in the operation of said delaying means in order to insure proper-matching of the various areas, and means for combining the unsuppressed signals to form a single series of signals.

3. A system for producing composite television pictures wherein foreground. middleground and background areas are provided, means for separately and simultaneously scanning eachof the areas to produce individual series of video signais, means for suppressing the signals from they kmiddleground area 'when signals are produced from the scanning oi' the foreground, means for suppressing the signals from the background area when signals are produced from the scanning of the foreground or middleground areas, means for delaying the scanning operation of the middleground and background areas by an amount equal to the inherent time delay in the operation of said delaying' means. and means for combining the unsuppressed signals to produce a single series of signals,the delay means operating to produce proper matching of the unsuppressed signals.

4. In a composite television system wherein a plurality of object areas representing different planes of a composite picture are provided, means for separately and independently scanning each' of the object areas to produce separate series of video signals, means for suppressing the signals from any and all object areas lying in a plane behind an area from which signals are produced. means for delaying the scanning operation of certain of said scanning means by an amount equal to the inherent time delay in the operation of said suppressing means to insure proper time relation between the various signals, and means for combining the unsuppressed signals to produce a single series of signals.

5. In` a system for producingcomposite television pictures, separate means to scan simultaneously two object areas to produce from each scanning an independent series of signals representative of the light values upon successive elemental areas of each object area, means to assemble the signals of each independent series 'into a single composite series o! signals representative of the scanned object areas superimposed, means to reduce the normal output signal level of one signal producing system under the control of the other signal producing system in accordance with the presence of simultaneously produced signals developed in the other signal producing system, and means to delay the operation of said one signal producing system by an amount equal to the inherent time delay in said reducing means toinsure accurate matching of the signals. 6. The method of producing composite television image signals which comprises independently and separately scanning a backgroimd and a foreground area to produce from each scanning a series ofsignals representative of each scannedarea,utilisingoneoftheproducedseries ofsignalstocontrolandobscurethe otherseries during period of presence oi thecontroliing lignal, delaying the scanning of the background area to produce accurate time relation between the series of signals, and combining the output energy resultingfrom each scanning to produce a single series of signals representing` superpositioninss of the scanned areas.

.7. The method of producing composite television image signals which comprises independently and separately scanning in a line by line manner a background'and a foreground area to produce from each scanning a series of signals representative of each scanned area, utilizing one of the produced series of signals to control and obscure the other series during periods of presence of the controlling silnal. adding to the controlling series of signals kthe resultant controlled series of signals, delaying the scanning of the background area by an amount less than the time required to scan one line, and combining the output energy resulting from each scanning to produce a single series of signals representing superpositionings of the scanned areas. the dclaying of the scanning ofthe background area operating to insure proper matching of the series of signals.

8. 'I'he method of producing composite television image signals which comprises independently and separately scanning foreground and background areas, producing from the scannings Aa plurality of independent electric waves representative of the varying intensity of light and shadow on elemental areas of the scanned foreground and background areas. reducing'the signal level of one of the electric waves representing one area to zero value during time periods where the electric wave representing the other area exceeds a predetermined eiiective intensity, 'delaying the production of 'one of the independent electric waves to insure accurate combining of the independent electric waves, and combining the output energy resulting from each scanning to produce a single series of signals representing superpositionings oi the scanned areas.

9. The method of producing composite television image signals which comprises independ-s ently and separately scanning foreground and background areas in a line by line manner, producing from the scannings a plurality of independent electric waves representative of the varying intensity of light and shadow on elemental areas of the scanned foreground and background areas, reducing the signal level of one of the electric waves representing one area to a predetermined threshold value during time periods where the electric wave representing the other area exceeds a predetermined eiective intensity, delaying the production of one ofthe independent electric waves by an amount less than the time required to scan one line, and combining the output energy resulting from each scanning to .produce a single series of signals representing superpositionings of the scanned areas, the delaying operation resulting in accurate combining of the independent electric waves.

10. The method producing composite television image signals which comprises independently and separately scanning in a line by line manner a plurality of areas, producing from the scannings a plurality of independent electric waves representative of the varying intensity of light and shadow on elemental areas of the scanned areas, reducing the signal level of one of the electric waves representing one area to a threshold value during the time periods when the electric wave representing another area exceeds a predetermined eifective intensity, delaying the production of at least one of the independent ing from each scanning to produce a single series of signals representing super-positionings oi.' the 5 scanned areas.

ALFRED N. GOLDSMITH.

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