US2343971A - Television studio lighting - Google Patents

Description

March 14, 1944. GOLDSMITH 2,343,971

TELEVISION STUDIO LIGHTING Filed March 5, 1942 2 Sheets-Sheet 1 T1 a .-l

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55AM INTENSITY ZUME/VJ V0.4 7:405

INVENTOR ATTORNEY L March 14, 1944.

A. N. GOLDSMITH TELEVISION STUDIO LIGHTING Filed March 5, 1942 FLASHING CONT/FOL 2 Sheets-Sheet 2 ZAMP 1405a dam/z- GENE/a470 71 INVENTOR 60405407.

ATTORNEY Patented Mar. 14 1944 UNITED STATES PATENT OFFICE 2,343,971 TELEVISION STUDIO LIGHTING Alfred N. Goldsmith, New York, N. Y.

Application March 5. 1842, Serial No. 483,461

20 Claims. (Cl. 1785'.4)

This invention relates to lighting systems and, in particular, to new methods and apparatus particularly useful for television transmission systems and studio lighting of scenes to be transmitted in color.

In the past, transmission of colored pictures by television has utilized a rotating disk in front of a television camera, the disk carrying three filter sectors, each filter sector corresponding to one of the primary colors,-the scene to be transmitted merely being illuminated with incandescent or are light, that is, with white light. Coincident with the light transmitted sequentially by each filter, interlaced scanning of well known types of the scene is performed with the result that, for tricolor television, three trains of television signals were produced, each train representative of one of the primary colors. Various minor variations of the process were possible but in all of them the scene was illuminated by white and its drive motor, generally in necessarily close mechanical and electrical juxtaposition to the senstitve -television camera. The mechanical complications of such a system have militated against an all-electronic method which is extremely desirable because the all-electronic method, being silent, permits the use of high sens t vity m'crophones on the set to provide the sound to accompany the pictures, and also avoids vibration of the camera tube. Moreover, allelectronic transmitting equipment can be made much more compact and so lends .itself more readily to television program production work. By my invention, I eliminate the necessity of the filter disk in front of or near the camera lens. Moreover, all mechanical and moving parts can be eliminated from the camera and yet my invention permits all of the benefits which arise from sequential scanning.

Moreover, my method and apparatus for lighting a scene may be adapted to provide means for obtaining increased depth of field in accordance with the 1R system described in U. 8. Patents No. 2,244,687 and No. 2,244,688, and, in addition, to ofler the advantage of increased efllciency oi the color lighting system for color television In accordance with my invention, the illumination of the set, performed by flashing lamps, gives a selective and eflicient radiation 01 an appropri ately colored light, which with minimum filtering corresponds to the desired color component 11- lumination. The illumination or flashing of lamps takes place during the blanking interval oi the field scanning of the camera mosaic and the cyclic repetition of the red, green and blue flashes from the lamps within the return line period of the field scanning may be made in any desired order within each cycle of operation. Thus,

it will be observed that during the return line time a high intensity of red light will be projectof the field scanning. The mosaic is subsequently scanned to produce a, train of signals which correspond to the red image. After the end of the seaming 'oi the mosaic, a green flash of high intensity takes place during the return line time and the mosaic isthen scanned to produce a train of signals corresponding to the green image. Following this, a high intensity blue flash or H- lumination is provided again during the return line time and the subsequent scanmng provides a wave train of signals corresponding to the blue image. The cycle is then repeated. Since the scene is illuminated for each field by only one primary component of color, it will be understood there is no necessity for providing a filter disk in frontoi the camera, since the light source itself provides suitably color flltered illumination. If it happens that the spectral emission characteristics of the lamps are not identical with that desired for the three component colors, then they may be corrected by placing color filters arfiacent to the lamps or coating the lamps with color flltering material, the absorption of the materials.

providing the proper correction. Since the lamps lights '85 and the spotlight 61.

apparatus for illuminating scenes for the transmission of color television pictures.

Another object of my invention is to provide new and useful apparatus for lighting television.

scenesin which increased efllciency is obtained by restricting the operationor the lamps to the blanking interval or the return linetime of the field scanning of the television camera mosaic. Further increase in lighting eiflciency results, as previously stated, from the use of selectively radieting lamps of inherent colorapproximating to one of the primary or component colors, thus minimizing the amount 01' colorfiltering and the consequent loss'ot light.

Another object 01- my invention is to provide apparatus for illuminating'scenes 'for. the transmission of the colored television pictures which operates in synchronism with a scanning apparatus and in which the setillumination takes place during restricted'time intervals.

Other objects of myinvention will become clear upon. reading the followingv detailed description,

together with the drawings. In the drawings, 1

, Figural showsin graphical form the time relation between the sweep impulses for synchronizing the fleld sweep oscillator, the sweep wave, the light flashes, and the-scanning periods;

Figure 2 shows one arrangement of lamps suitable for use with my method .and system of illuminating scenes: 1

Figure 3 shows a modification of the embodi ment of the lamp arrangement shown in Figure 2:

Figure 4 shows a still further modification of the embodiment of lamps shown inFigure 2; f

Figure 5 shows schematically acircuit arrangement for actuating the lamps sequentially'and' with the scanning apparatus,

in synchronism while a Figure 6 shows diagrammatically thearrange f ments' and apparatus for illuminating 1 a scene taken together with the camera to show the inter-relationof the units used in my invention.

- Turning now to Figure 6, it will be observed In Figure 1 the sweep impulses I, supplied from the synchronizing generator, serve to trigger the field oscillator periodically. The sweep wave of theoscillator has a long linear rising slope 3 and a short steep return portion 5 so as to provide rectilinear scanning in one direction of the mosaic of the camera. tube. During the return line portion 5 pulses are applied to the control grid of the scanning tube to reduce the beam intensity to zero. This interval is known as the blanking interval. Coincident with the turning all of the beam of the scanning tube, one of the lamps of each unit 65 of Figure 8 is flashed, as, for example, at I. The lamp flashed during the interval shown in Figure 1 at 1 corresponding to the red light is of suflicient intensity to produce a stored charge image on the mosaic which thereafter is scanned. during the time interval l3. Following the scanning of this image corresponding to the red image. the green lamp is flashed at the interval 9 and the mosaic is scanned during the interval I5. Following the completion of the scanning interval I5, the blue lamp is flashed at II and the resultant mosaic image scanned during the time interval I1. Thereafter the cycle is repeated. It will be appreciated that the light flashes 1, 9, II corresponding to the flashing of the lamps I1I, I12, I13, respectively, of Figure 2 and of'lamps I15, I16, I11, respectively, of Figure 3, and of lamps I5, I93; I95, respectively, of Figure 4. For spot lighting the lamp systems shown in Figure 2 and Figure 3 may be used advantageously. Thus, in Figure 2 there is shown an assembly of three lamps (red, green, and blue flashing lamps, respectively). Each lamp is mounted in its own container but the three lamps 1 thereof.

anti-parallactic adjustment whereby the axes of The lampscan be provided with an the respective beam can be shifted through a that the studio scene comprises thebackdrops To televise' a scene, a camera 69, which may be of any conventional ty known in theiar't, has its scanning operation controlled from the synchronizing generator II. The scene is illuminated, for example, by a plurality of flood The lighting units are supplied from the lamp supply source '15,'and controlled by the flashing control units .13. The flashing control unit is synchronized from the synchronizing generator 1| so that the flashing takes place in synchronism with the scanning operation of the camera, that is to say, the-flashing oi the lamp is controlled to take place during the blanking interval of the scanning period. The flood lighting units may take the form shown inFigure' 4, in which the three individual lamps III, "3, I I each have a: predeample; red, green, and blue. The reflector-"I91 serves to direct the light iromjI-the lamps "on' the scene being illuminated. ,-'I'he"'-lamps areclosely. djacent to each other; andfsince the-unit isusu'":

ally positioned at some .distance-tromfthe scene, the three lamps flashed sequentiallyappear to he of operation will be F ure 1.

small angle relative to the central axis of the lamp system I1II13 in such fashion that the illuminated areas from each of the colored flashing lamps may be made to coincide with any de- 7 sired degree of accuracy at the normal illumina- 'termined restricted spectral emission, as,- for extion distance.

Figure 3 shows another embodiment of the composite lamps similar to the Figure 2, except that each of the lamps is mounted within the common cylindrical or other container I14 and occupies, or is placed at the end of, a cylindrosectorial solid portion thereof as indicated, for example, by I15-|11. A common condensing lens may be used for each of the three light sources. As before, anti-parallactic adjustments may be provided in this case as well, and these will comprise preferably the shifting of the light source in each sectorial portion in a direction perpendicular to the central axis of I14 (that is, radially outward in a line parallel to one of the bisectrices of the angles between the dividing planes separating 'the respectively colored lamp compartments).

. A wiring diagram illustrative of the functioning" of-flashing-lamps and their suitable timin :is shown in vFigurefi. A mechanical system of 'itiiningis illustrated, although it should be understood that electronic timingmethods are also available. For that purpose impulses derived from the blanking impulses in the television system might beemployed. It is believed not necessary, howevento show an electronic timing is illustrated by RI in the upper portion of the ascae'n,

sociated with brush I42 is driven synchronously figure, this beinga conventional full-wave highvoltage rectifier system. The transformer I48. I01 supplies the filaments (cathodes) H3 and H4 of the rectiflers III, II2, which may be of any conveniently available type, e. 8., thyratrons. The high-potential transformer IIO, II, which is center-grounded at '1, is connected to, the anodes H4, N5 of the rectifier. The central point I08 of the secondary of the filament transformer I08. I01 is connected to the anode I26 of the flashing gas lamp I26. These lamps which are well known at this time as applied to stroboscopic illumination, are generally filled with one or more inert rare gases, e. g., neon,

argon. krypton, at low pressure. Connected across the terminals I26, I21, of the lamp is the high potential condenser I28, the periodic discharge of which produces the desired flashes of light from the lamp. The high resistance I29 is connected across I28, whereby the condenser I28 is discharged when the lamp is not in use,

thus minim zing the danger of electric shock to the operating personnel. The cathode I21 is connected through a resistance I36 of appropriate value to the ground I3I. The rectifier RI will rapidly charge the condenser I28 to the desired operating voltage (which is usually of the order of a few hundred to a few thousand volts) provided the frequency of alternator IN is sufficiently high, the applied voltage is sufiicient, and the condenser capacity properly chosen. With 60 fields per second (that is, /3 of a second between successive discharges of the same lamp of a given color), a suitable alternator frequency might be 60 cycles or, preferably I20, IN, or a higher number of cycles. These values are purely illustrative. If the number of fields per second is increased beyond 60, (as will generally be the case for tricolor television), the frequency of alternator IM may be correspondingly increased. It is necessary that there shall be a sufficient number of charging waves between discharges to bring the condenser I28 to a stabilized highpotential adequate for the operation of tube I 25.

The triggering or discharge of such tubes can be accomplished in various manners, one ofthe simplest of which is to provide an auxiliary external or internal electrode I32 as shown in one portion of the tube and then applying a brief high-potential pulse to the electrode I32. The initial ionization thus produced within the tube by the pulse in question will initiate the discharge which rapidly follows and which, in general, lasts only a few microseconds.

In Figure 5 a typical ignition-coil system is shown for producing the high-voltage pulse on the auxiliary or trigger electrode of the lamp.

The circuit of primary I35 of the step-up transformer I34, I35 starts with ground I38. passes through primary I35, to brush I40, through slip ring I49, to conducting segment I, intermittently .to brush I42 through D. C. source I43, and back to ground I44. The condenser I39 is connected across the intermittent contact I, I42 to reduce sparking. Whenever the contact by a motor in the direction I60 at a speed such .that one of the segments I4I, I40, or I45 passes imder I42 once per color field of the scanning and at a time (phase) substantially in the middle of the blanking period preceding the corresponding color scanning, as shown in Figurelat1,9,II.

The lamp I 25 Isassumed to be rich in red light and, if necessary, to be filtered further to produce substantially the primary additive red illumination of the set. Lamps I50 and lil are similar except that .they produce light rich in green and blue respectively, preferably, and are, if necessary, color filtered to produce the corresponding primary additive green and blue respectively. Lamps I25, I50, and IBI correspond to the three flashing lamps which would be used in the assemblies shown in Figures 2 and 3.

The rectifying units R2 (I60) and R3 (I64) are not shown in detail since they are substantially identical with RI. They feed respectively the lamps lit and iii in a manner entirely similar to that in which RI feeds lamp I25; nor have I deemed it necessary to show the connections from I 41 and I48 of the flashing or triggering commutator to the trigger electrodes I54 and I51 respectively of the lamps I50 and Hal, inasmuch as the circuit is identical with that already disclosed in connection with lamp I25.

It will be appreciated of course tliat for spot lighting the lamps may take a form of a helix in which, for example, there may be provided three separate concentric turns, each turn corresponding to one of the primary colors. Again, coaxial or concentric circular lamps may be provided, each ring again corresponding to one of the three primary colors. It will also be-appreciated that while, for example, a mechan cal type of commutator has been shown for supplying pulses to initiate the discharge of the lamps in synchronism with a scanning operation, an electronic commutator of the Shumard or Boys 82 Mayer type described in U, S. Patents 2,146,862 and 2,089,430 may be provided.

Moreover, it will be appreciated that the generator IIII may be an electronic oscillator capable of supplying sufficient power and utilizing, for example, tuned transformers and rectifiers to provide sufiicient, .vo1tage' step-up for charging the condenser. Such oscillators have the advantage of rendering the flashing characteristic of the lamp somewhat more stable in view of the fact that the ripple voltage becomes relatively unimportant when the frequency of the generator becomes large compared with the cyclic time of the discharge of the lamps. It is believed unnecessary to illustrate such an oscillator since such oscillators and rectifying systems are well known in the art.

It will be appreciated that if the storage of the camera tube mosaic is excessive, a spurious signal may be generated following the scannin of one of the colored fields by the next colored is present. then its effects can be obliterated by HI, I42 is made and broken. at the break a high voltage is produced in secondary I34 wh ch trigflooding the mosaic with electrons or light of appropriate intensity to restore it to a datum potential after each scanning and before the next. illuminating flash, as indicated schematically by Fig. l, with the datum level restoration pulse be--.

9 and II for the different primary color lamps .betweenscannlngs and restricting the duration corresponding to the red, green and blue. In addition to flooding the mosaic, any or the other well known means to restore all or the elemental areas of the mosaic to an equilibrium potential may be used. These methods are well known in the art and it is considered unnecessary to illustrate them, it being appreciated, however,'that the restoration of the mosaic to a datum potential must take place following the scanning or the field and before the flashing of the lamp.

Various alterations and modifications of the present invention may become apparent to those skilled in the art and it is desirable that any and all such modifications and alterations be considered within the purview of the present invention except as limited by the hereinafter appended claims.

Having now described my invention, what I claim is:

1. The method 01' transmitting color television pictures which includes the steps of illuminating the scene to be transmitted sequentially with a series of primary component color lights, producing an electric charge image of the scene by each illumination, limiting the illumination duration to a period relatively short compared to a scanning cycle. and scanning the charge image between the illuminaticns of the scene.

2. The method of illuminating scenes for transoi' illumination so that it occurs during a short time period as compared to the time period 01., scanning.

7. Apparatus for transmitting color television pictures comprising means IOr illuminating the scene to be transmitted sequentially with a series or flashing lights 01' primary component color,

' means for producing an electric charge image mission of color television pictures which includes the steps of briefly illuminating sequentially the scene by lights of different colors and controlling the period ot illumination so that it is short as compared to the period between the sequential operation of the lamps.

3. The method of transmitting color television pictures which includes the steps or sequentially illuminating the scene to be transmitted with a series of primary component color lights, producing an electric charge image representative of the scene by each illumination, limiting the illumination duration to a period relatively short compared to a scanning cycle, scanning the charge image between the illuminations of the scene, producing a train of electrical signals representative of each scanning, and transmitting the produced trains of signals.

4. The method of illuminating scenes for transmission of color television pictures which includes the steps oi cyclically illuminating the scene by light of a first, a second, and a third predetermined spectral emission, and controlling the time period of illumination so that it is short as comared to the time duration between the sequential illuminations of the scene.

5. The method of transmitting color television pictures which includes the steps oi sequentially pared to the duration of each illumination, syn chronizing the initiation of illumination with the termination of the scanning of the charge images, and transmitting the produced image signals.

6. The method of illuminating scenes for transmission of color television pictures which includes the steps of briefly illuminating sequen tially the scene to be scanned for transmission by lights of difierent colors, controlling the in ception of illumination to occur duringthe period 01' the scene by each illumination, means for establishing the period of illumination by each primary color to a period relatively short as compared to each scanning cycle, means for scanning the charge image between the illuminations oi the scene, means for producing a train of electrical signals representative of each scanning, and means for transmitting the produced trains of signals. 1 t

8. Apparatus for illuminating scenes for transmission or color television pictures comprising means for cyclically illuminating the scene by light of a first, asecond, and a third predetermined spectral emission, and means for controlling the time period of illumination so that it is short as compared to the time duration between the sequential illuminations of the scene.

9. Apparatus for transmitting color television pictures comprising means for illuminating sequentially the scene to be transmitted with a series of primary component color lights, means for producing an electric charge image by each illumination, means for scanning the charge image between the illuminations of the scene. and

means for maintaining said scanning period rel-' atively long compared to the duration or each illumination.

10. Apparatus for illuminating scenes lor transmission or color television pictures comprising means for briefly illuminating sequentially the scene by lights of different colors and means for controlling the period oi. illumination so that it is short as compared to the period between the sequential operation oi'the lamps.

11. Apparatus for transmitting color television pictures comprising means for illuminating the scene to be transmitted sequentially witha series 01. primary component lights, means for producing an electric charge image representative of the primary color light value or the scene for each illununation in the separate colors, means for scanning the charge image between the illuminations of the scene to produce electrical image signals, means-for maintaining the scanning period relatively long compared to theduration of each illumination, means for synchronizing the initiation of illumination with the termination of the'scanning or the charge images, and means for transmitting the produced image signals.

the scene to be scanned for transmission by lights.

or difl'erent colors, means for controlling the inception of illumination to occur during the period betweenscannings, and means for restricting the duration of illumination to a short time period as compared to the' tim period 01' scanning.

13. Color image apparatus comprising a scene of which a colored ima e is desired, a bank 0! light sources for illuminating the scene, each source having a predetermined restrictedspectral emission, means for scanning said scene at a predetermined scanning repetition cycle, means to synchronize the initiation'oi' the illumination of the scene with a predetermined portion or the operational cycle of the scanning means, and means for restricting the duration of the illumination to a minor fractional part of the scanning cycle.

14. Color image apparatus comprising a scene or which a colored imag is desired, a bank of light sources for illuminating the scene, each source having a predetermined restricted spectral emission, means for scanning said scene, commutator means to synchronize the illumination of the scene with the scanning means and means for restricting the duration of the illumination to a minor fractional part of the scanning cycle.

15. Color image apparatus comprising a scene of which a colored image is desired, a bank of light sources for illuminating the scene, each source having a predetermined restricted spectral emission, means for scanning said scene, electric commutator means to synchroniz the illumination of the scene with the scanning means and means for restricting the duration of the illumination to a minor fractional part of th scanning cycle.

16. Color image apparatus comprising a scene of which a colored image is-desired, a bank of light sourcesfor illuminating the scene, each source having a predetermined restricted spectral emission, means for scanning said scene, a common synchronizing means to initiate cyclic operation of said sources and said scanning means and means for restricting the duration of the illumination to a minor fractional part of the scanning cycle.

17. Color image apparatus comprising a scene of which a colored image is desired, a bank of light sources for illuminating the scene, each source having a predetermined restricted spectral emission, means for successively scanning said scene, and control means to initiate said scanning means and to restrict, the operation of said agrees to time periods between successive scan- 18. The method of illuminating scenes tor transmission of color television pictures which includes the steps or briefly illuminating sequentially the scene by lights or diflerent primary colors and controlling the period or illumination so that it is short as compared to the period between the sequential illuminations of the scene.

19. A method of television transmission which comprises illuminating a scene of action by a seriesof lights of primary component colors sequentially. illuminated, producing on a scanning element an electric charge image of the scene of action as a result of each illumination, interrupting the illumination period by each of the primary component lights promptly after initiation, scanning the produced charge image during periods of illumination interruption to produce output electrical image signals'representative oi the scene of action, restoring all charge images to a predetermined datum level immediately subsequent to each scanning, then repeating the cycle of illuminating, scanning and datum level restoration, synchronizing the sequence of datum level restoration and the initiation and termination of illumination with predetermined periods of the scanning cycle, and transmitting the produced signal energy.

20. A television transmission system comprising a plurality of light sources of each of a plurality of primary colors, means forilluminating a scene of action by sequentially illuminating the said lights, an image scanning element, means for producing on said scanning element an electric charge image of the scene of action-tor each illumination, means for interrupting the illumination period of each of the primary component lights, said scanning element including means for scanning the produced charge image during periods of illumination interruption to produce output electrical image signals representative of the scene of action, electric means for restoring all charge images to a predetermined datum level immediately subsequent to each scanning, distributor means for causing the cycle of illuminating, scanning and datum level restoration to repeat in sequence, means for synchronizing the sequence of datum level restoration and the initiation and termination of illumination with predetermined periods or the scanning cycle, and means for transmitting the produced signal energy.

ALFRED N. (EIOLIJSMI'I'H.

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