US1738007A - Television - Google Patents

Description

3, 1929. H. E. lvEs TELEVISION Filed May 2o, 192e;

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TELEVISION Filed May 20, 1926 3 Sheets-meet E 'atenteil Doc. 3, 1929 UNITED.; STATES -I=-ATENT OFFICE `:HERBERTl E. IVRB, l' IONTCLAIR, NRW JERSEY, ABBIGNOR T0 BELL TELEPHONE LABORATORIES, INCORPORATED, 0F NEW YORK, N. Y., .A OQRPORATION 0l'- NRW 'YORK 'rmvrsroir Application lied lay 50, 1926. Serial Ie. 110,878.

This invention relates to the electricaly transmission of scenes or pictures and particularly to the reproduction of such scenes or pictures in their natural colors.

a It is the principal object of the presentinvention to improve the scanning of a picture er view being transmitted. e

It is well known in the art that pictures may be transmitted by means of'an electriwhich is generated corresponding to the light intensity of successive small areas of the pieture, is used to modulate a carrier current. 'Ihis current is demodulated at a receiving station to control the intensity of illumination of a lamp or lamps. A variety of scanning means have been proposed, one commonly used consisting of a rotating disc having a plurality of apertures therein arranged in color it hasbeenlustomary either to make a record of the colds-valuesv in the picture and use these recprds for generating the photoelectric current or to use a plurality of carrier currents for carrying the photoelectric variations where that' current 1s generated directly. In either case the demodulated carrier current has been used to make black and White records -which are subsequently used to control the production of the colored picture. l

According to the present inventlon the scene to be transmitted is scanned repeatedly and successively for each of a plural1ty oi primary colors. At the receiving station images are repeatedly produced in each of the primary colors in turn and pro]ected on a screen at such a speed that the eye combines the colors. According to a modiication of the invention the object is scanned in strips, successive strips being scanned for different colors and the order of the colors being changed for successive complete scannings.

The receiving apparatus is arranged to reproduce the icture in strips of correspondin color an to shift the color 1n the same or er as the transmitting apparatus.

In brief, there is employed, in a system hereinafter described as a specific and illustrattive embodiment of the invention, a plucal system wherein a photoelectric current,.

in a spiral. In the reproduction of pictures rality of photoelectric cells each responsive to a different re 'on of the spectrum with an arrangement o?! rotating mirrors, eachv of which directs the light to all of the vcells in succession. Thev picture or view is scanned by means of a rotating disc having spirally arranged apertures therein and the light which passes through the apertures is directed to the rotating mirror. At the receivmg end a plurality of lamps each emitting light of a different region of the spectrum, are lighted by current received over the line. A mirror arrangement and scanning disc similar to those at the sending station serve to reproduce the picture on a screen at the recelvmg station.

I n the modified form of the invention a series of lenses and mirrors direct the light from the scanning disc to photoelectric cells which respond to light from diierent regions of t e spectrum. A commutating device connects these cells successively to a carrier wave modulator. The scannin disc and the commutator are driven simu taneously so that each cell is associated with the modulator for only a ortion of a revolution of the scanning disc. owever, the scanning disc is geared to the drivin mechanism of the commutator so as to ma e slightly more or slightly less than one revolution per revolution of the commutator, thus shifting the order in which the photoelectric cells are connested to the modulator for successive scannings of the object. At the receiving station the commutatorand scanning disc are similarly arranged and the image is produced in strips.

In the drawings two modifications of such a systemre shown. Figs. 1 and 2 show an organization whereby the icture may be completely scanned for eac color in succession. Fig. 3 shows an organization whereby the picture may be scanned in strips.

Referring to the embodiment shown in Figs. 1 and 2, the picture to be transmitted is represented by film 100 which is illuminated in any suitable manner, for exam le, by lamp 101 4and condensing lens 102. ilm 100 indicates a single picture which may be one from a strip 24 revolutions to one amplifier 222, and

such as used in projecting .a motion picture. Lens 104 produces an lmage of the film upon the scanning disc 105 and lens 106 focuses a beam of light on the fphotoelectric cells 107, 108 and 109 after re ection by the rotating mirror 110.

If the object to be transmitted is not a picture but a natural scene, the lens 104 may be used to form' an image of the scene directly on the disc. The scanning disc and the rotating mirror are driven simultaneously under th control of tuning fork 111. Tuning fork 111 may be driven by means of the usual self- `interrupting circuit orby. any other desirable ,means The tunin fork in vibratin closes obvious circuit f or operating the La Cour motor 112 whici turns the shaft 113. The disc 114, rigidly attached to the shaft 113, is geared to scanning disc 105, discs 114 and 105 beingof the same size so that a single -rotation of the shaft 113 produces a single rotation of the scanning disc. Shaft 113 is also suitably coupled to the Geneva movement 115. From an inspection of the drawing it will be apparent that for each revolution of disc 116, disc 117 will make a quarter turn. The driving disc 118 and driven disc 119, which is rigidly attached to the multifaced mirror 110, are geared in the ratio of 1 to 6. Therefore scanning disc 105 will make complete revolution of mirror 110.

The tuning fork 111 also serves to control the synchronous movement of the driving apparatus at the receiving station. This driving apparatus comprises a tuning fork 211, a La Cour motor 212 and a Geneva movement 215 and serves to drive a scanning disc 205' anda multi-faced mirror 210 at speeds bearing the ratio of 1 to 24. A source of current 120, a modulator 121 controlled by fork 11, an amplifier 122, and a filter 123 transmit a synchronizing current to the line At the receiving station a filter 223, an a demodulator 221 cause the energization of a magnet 224 in synchronism with magnet 124 to drive the tuning fork 211. Suitable apparatus for producing and receiving the synchronizing current is described in the patent of Maurice B. Long, No. 1,706,032, issued March 19, 1929.

Considering the optical arrangement in detail for a moment, with the mirror 110 in the osition shown, light from the disc 105 will Ee directed upon photoelectric cell 107. As each aperture of the disc passes across the image of the film, a spot of light of varying intensity will be focused upon cell 107. The b not completely end apertures in disc 105 do circle the disc but are arranged to leave a section of the Vdisc solid. The discs of the Geneva movement 116 and 117 are arranged so that pin 125 engages slot 126 and the mirror is moved forward While no apertures are passing the image of the film. The advance of the lwhich responds to the green region of the spectrum and the third quarter turn brings face 128 into the position which face 127 occu ies `in the drawing.

' he im edance of the photoelectric cells, particular y when not illuminated, is sufiiciently high so that Ythe connection of the dark cells in parallel with the cell receiving the incident light does not materially reduce the photoelectric current. The amplifier 180 amplifies the photoelectric current before its application to modulator 142. As the beam of light is successfully directed upon cells 107, 108 and 109, the photoelectric current will represent the variations of the corresponding color in the image.

Oscillator 141, modulator 142, amplifier 143 and filter 144 serve to transmit a carrier wave modulated by the current in the photoelectric cells to the line L While filter 244, amplifier 2,43 and demodulator 242 receive the modulated waves and direct the signal current to lamps 207, 208 and 209. Reference is made to the above identified Long application for the disclosure of these elements.

At the receiving end lamp 207 emits light from the red end-of the spectrum, lamp 208 from the een region of the spectrum and lamp 209 rom the blue end of the spectrum. These lamps are lighted simultaneously but as mirror 210 rotates, light from only one lamp at a time is directed to the disc 205 and an image of the aperture is projected on the screen 290.

To recapitulate, as the mirror 110 rotates under the control of fork 111, disc 105 is rotated and as each successive aperture in the spiral passes across the image formed on the disc, the spot of light focused on one of the photoelectric cells, say 107, varies inI intensity in accordance with the brightness of the image being scanned. This spot of light will contain all of the colors but, since cell 107 is responsive to red light only, it will produce a variation of current in the modulating circuit in accordance with the variation of red light in the image. At the next revolution of disc 105 the spot of light will e directed to cell 109 and that c ell will prouce a current which represents the strength of blue light in the image. Similarly, on the third revolution the current in the modulating circuit will represent the strength of green light in the image. Successive revolutions will cause a modulating current representing the colors in rotation.

lo vary with the strength of Q green ima e.

igvsspov At the reeeivin end the drivingI apparatus being in sync ronism with that at the sending Station, the light'from lamp 207 will be directed on scanning disc 205" at the .same time that light is focused on cell 107. *The current leaving the demodulator 242 varies in accordance with the variations in v the current reaching modulator 142 and the illumination of lamps 207 208 and 209 will A the red color in the light focused on cel1107. vSince only the light of lamp 207 will be directed on the disc 205 this disc in rotating will cause va spot of light to travel over the screen 290.v This u spot of light will be red in color and will vary in intensity with the red in the original image. During the second revolution of disc 205 a blue image will be thrown on the screen 290 and on the third revolution a These images will follow one another with such rapidity that the eye of the observer cannot distinguish between them and the resultant effect on the retina will be a picture in the colors of the orig- @5 lllal.

Referring now to Fig. 3 a system is disclosed in which the picture or scene is scanned in strips, eachfstrip belng scanned for a different color and the order of the w colors being altered for each complete scanning. For this purpose, the film 311 represents the picture or scene to be scanned., an image of which is formed on the scanning disc 301 by the lens 302. A. series of semi-transparent mirrors and lenses serves to direct a portion of the light from the scanning disc 301 to each of the photoelectric cells303, 304 and 305. These light cells are made responsive to red, green and blue lights respectively b using mirrors which reflect the desired lig t, by the interposition of color'lilters or by making the cells themselves responsive only to the color desired.

The scannin disc 301 is driven through the agency o a tuning fork controlled La Cour motor which also drivesa commutating arrangement 306. The driving disc 307 bears an unequal ratio to the scanning disc 301, for example, 16 to 15. The fork also sends out impulses which serve to synchronize the driving apparatus at the receiving station 350, which apparatus is a duplicate of that at the sending station 300. The apparatus for transmitting and receiving these synchronizing impulses may be of any desirable ty e, such as that shown in the above identi ed Long application.

Referring to the commutating arrangement, brush 308 serves to connect ring 309 with the ring ofnsegments 310. These segments are connected to the photoelectric cells 303., 304 and 305. The sequence of colors for which the picture will be scanned may be readily determined from an inspection of 05 the drawing. With the suggested ratio of 15v to 16 between the driving and scanning discs it will be apparent that the relation between the stri of the picture scanned and the color for w ich that picture is scanned will be changed at each revolution.

The current produced in each of the cells due to the intensity of the corresponding light in the beam from the scanning disc 301 is transmitted over the line L and received in the usual manner. A lamp is provided for each color and a plurality of semitransparent mirrors and lenses to produce a spot of colored light on the screen. As in the case of the sending station, the color may be controlled either by the color of the lamps or by the colorf the mirrors. The driving arrangement at the receiving end is similar to that at the sending station and a commutating arrangement 356 serves to conneet the lamps with the line in the same order as the photoelectric cells are by the commutating arrangement 306.

The apparatus shown is of course merely suggestive. For example, a single photoelectric cell may be used and a Geneva move ment may be employed to introduce colored filters between the scannin disc 'and the cell at the sending station and etween the lamp and the scanning disc at the receiving station. According to a modication of the arrangement shown in Fig. 3 opaque screens may be used to obscure all but one photoelectric cell and lamp at a time.` It is therefore apparent that it may be possible, without departing from the spirit of thinven tion, to emp oy equivalents for many parts of the system.

What is claimed is:

1. In a system for the transmission. oi

views, means for repeatedly scanning the view including a plurality of selective light responsive elements and means for illuminating said elementsin' succession by light of different colors respectively from said view, sources of light of different colors, means for rendering said light responsive elements successively effective for controlling the light from said sources, and means for synthesizing the light from said sources to produce an image.

2. In a system for the transmission ofy views, a plurality of selective light translating elements, means to repeatedly and successively scan the view for each of a plurality of colors one at a time, and means for reproducing said view in its natural colors by the repeated and successive production of an image for each of said plurality of colors.

3. In a system -or the transmission of Views, means to repeatedly and successively scan the view for each of a plurality of colors one at a time, means for translating the view into an electrical current proportional successively to the amount of each primary color in said view, means for producing light of each primary color, means for actuating said light producing means under the control of said electrical current, and means for synthesizing the light produced by said light pro- 5 ducin means to reproduce said view.

4. liil a system for the transmission of views, means for repeatedly and successively scanning the view for each of a plurality of colors one at a time, a plurality ofphotoelec- 1;, tric cells, each responsive to a particular color, means for rendering said photoelectric cells 'effective in a predetermined order, a plurality of lamps, each lamp emitting a particular color, means for varying the illumination of each lamp in accordance with the current produced by the photoelect'ric cell in response to the corresponding color, and means for synthesizing the colored light from said lamps to reproduce the view in its natural colors.

.5. In a system for the transmission of views, means for scanning elementary areas of said View to produce an electric current corresponding to the Variation of the light value of a primary color in said elementary areas, means for varying the color for the scanning of successive elementary areas,

means for varying the color for successive scannings of the same elementary area, means for transmitting and receiving said current,

' a0 and means for reproducing elementary areas of corresponding color to produce an image in its natural colors.

6. The method of transmitting and reproducing views in color which `consists in scan- 85 ning successive elementary areas of said image for diferent colors, changing the order of said colors for successive scannings of said image, transmitting an electric current varying according to the light value of the colors,

40 and at the receiving end reproducing elementary areas of the image in the corresponding nolors.

7. The combination in a system for transmitting views of a plurality of photoelectric cells selectively responsive to light of different colors, a disc with spirally arranged apertures thereinv for scanning the view, a system of mirrors cooperating with said disc for directing light from said view successively and l0 repeatedly t0 said cells, means for transmitting an e ectric current varied in accordance with the photoelectric response of said cells, a plurality of lamps each emitting light of a diierent color, means responsive to the vtrans- IB mitted current for controlling the intensity of the light from said lamps, and means including a disc with spirally arranged apertures and a mirror system for combining the light from said lamps to form an image of the said W view in its natural colors.

In witness whereof, I hereunto subscribe my name this 19th day7 of May. A. D. 1926. HERBERT E. IVES.

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