US1993604A - Electrooptical system - Google Patents

Description

March 5,1935. H. g. lvEs ELECTROOPTICAL SYSTEM Filed. Feb. 5, 1930 A r TURN; Y

Patented Mar. 5, 1935 UNITED STATES PATENT OFFICE Telephone Laboratories, Incorporated,

New

York, N. Y., a corporation of New York Application February 3,

6 Claims;

This invention relates to electro-optical systems and more particularly to the production of an image having -a predetermined color.

' '-It has heretofore been proposed to reproduce '5 an image of moving objects or pictures in their natural colors. In such systems, the light derived from the object scanned at the transmitting station is applied to photoelectridcells each of which is sensitive to light rays lying within 10 :certai-n portions of the light spectrum, i. e. certain colors, 'toproduc'e separate and distinct currents. Each current varies in accordance the'lig h't'intensities o'f elemental "areas of the object possessing the-corresponding color. The 15 currents corresponding to the diltrent portions of the spectrum are separately transmitted to a receiving station, where "they are respectively used to energize sources each adapted to pro- "duce light corresponding to the selected portion 2 of the spectrum.

other words, the current corresponding to one color of the object scanned at the trarmm-itting station is separately transmitted to control the production "of light of the same color at the 25 receiving station, where the colors are blendedor mixed to produce color effects corresponding to the natural colors of the object scanned.

In certain systems currents corresponding to the different primary colors are transmitted over "1 ,0 'difierent channels, as disclosed, for example, in

U. S. Patent 13878147, issued September 20, 1932 to H. E. Ives. In other systems the separate currents are transmitted successively over the same channel,

" 5 as disclosed in U. S. Patent 1,839,361, issued January '5, 1932 to Weaver and Branson.

'In still other systems, voltage discrimination is used to separate the currents arriving at a receiving station, and the respective currents are 40 used to control light sources, each producing :a distinct primary color. y

The present invention provides a system in which a single current )band, varying in accordance with the tone values of elemental areas #45 of an object "or ffi-eldis'canne'd at a transmitting 1930, Serial No. 425,432

object scanned but which is variable in accordance with the tone values of its elemental areas, to produce light radiations giving the effect of a predetermined color which differs from that supplied by the separate sources. I

In one embodiment, which will be hereinafter described in detail by way of example, a current band is supplied to a plurality of light sources connected in parallel. The band is independent of the natural colors of the scanned '10 object, but its .amplitude varies in accordance with the light intensities of elemental areas of the object.

Each source is adapted to produce light of a color different'from the other and varying in intensity with the changingamplitudes of the applied current band. The light radiations supplied "by the respective sources are superposed on each other, or are supplied to color mixing means, to produce illumination which gives the effect of pure white light. Obviously, by properly controlling the color of the light radiations supplied by the respective sources and superposed upon each other, the combined light may give an'effe'ct corresponding to any desired :color. 5

Fig. 1 is a schematic of a television system involving the invention, and

Fig. *2 illustrates apparatus which may be substituted for that to the right of section line -AA in Fig. 1.

The transmitting station T shown in Fig. :1 includes apparatus similar to and operable in the manner disclosed in application Serial No. 227,- 649 filed Oct. 2-1, 1927 by F. Gray. Briefly it comprises a source of light 1 from which light 5 rays are directed by an optical system 2 in the form of a beam upon a peripheral portion of a rotating disc 3 provided with apertures arranged in a spiral, whereby "as the disk rotates, a pencil of light traverses each aperture, as it passes '40 across the beam produced by the system "2, and is directed upon the object or field. 5 to be scanned for transmission, by the movement of the aperture and the action of lens 4.

The apertures in the disc are of such size and. are so arranged that, as the disc rotates, the traveling pencils produce spots of light which traverse successive strips or lines of the object or field 5, which is thus completely illuminated once per complete revolution of the disc.

'lliight is reflected from the object 5 upon the light sensitive system ;6, that may include one or more photoelectric cells, which is thereby activated 'to cause the production of an electric current band the amplitude of which varies in accordance with the tone values of elemental areas of the object.

The current band of variable amplitude, after amplification in the device '7, is transmitted by means of a communicating medium, herein shown as a transmission line 8 but which may be a radio channel, to a remote station R where it is again amplified, by the device 9. The devices 7 and 9 are shown as including space discharge tubes, but any other form of distortionless amplifier may be used.

It is to be understood that in operation heating current will be supplied to the filaments and space current to the filament-anode path or" the tubes included in devices '7 and 9, and, if desirable, biasing potentials to their grids.

The amplified current wave is supplied to three parallel connected. lamps 10, 11 and 12, each of which produces light of a color difierent from that radiated by the others. Any type of lamp may be used, provided the intensity of the light produced by it varies synchronously with variations in value of the current supplied by the amplifier.

Associated with the respective lamps 10, 11 and 12 are color filters 13, 14 and 15 and two semi-transparent mirrors 16 and 1'7.

The light radiations supplied by sources 10 and 12 after passing through the filters 13 and 15 are superimposed upon those emanating from source 11. r

The filters serve to determine the exact color of the radiations supplied by the respective sources to the mixing or blending means and hence the color effect given by the light which results from combining the radiations. By properly selecting the filters, the color effect given by the combined light may be any one of a number of tints.

For example, lamp 10 may supply red light, lamp 12 blue light and lamp 11 green light. When these different colored radiations are properly controlled as to their respective intensities and are superimposed upon each other, or are combined, the resultant illumination gives to the human eye the impression of white light.

Obviously by changing the intensities of the light supplied by one or more of the lamps 10,

'11 and 12, or by using lamps producing radiations of other than the above mentioned primary colors, the combined radiations will produce in the human eye the effect of light having a definite color.

The combined radiations may be caused to produce the effect of any fixed tint or color by maintaining substantially invariable the relative intensities of the colors which are blended during non-signaling periods. When the image current wave is supplied to the lamps, the intensity of the light produced by the combined radiations will be varied, but its color will remain the same.

The receiving apparatus includes a scanning disc 18 provided with a spiral row of apertures and operated in synchronism with the disc 3 of the transmitter.

The system of lamps 10, 11 and 12 and disc 18 cooperate to produce, within the field of vision of the observer 19, an image of the object scanned at the transmitter.

In order that no light may be supplied to the observer except through the apertures in the disc 18, the lamp system 10, 11 and 12 should be enclosed or shielded. A shielding element is shown at 20.

Fig. 2 illustrates a simplified apparatus for producing a television image having a selected or predetermined color. This apparatus comprises two lamps 21 and 22 respectively producing light rays of different colors, a single color filter 23, and a single semi-transparent mirror 24 for superposing the radiations from 21 upon those supplied by 22.

As a practical example the lamps 21 and 22 may be glow discharge lamps, one of which is charged with neon and the other with argon. Associated with the argon filled lamp is a filter which emphasizes the blue-green of the spectrum of its radiations and thereby renders them complementary to the orange-red of the neon lamp. Thus the basic color of the image seen by the observer will be white.

Obviously the basic color of the image may be modified, by using a filter which emphasizes certain selected spectral lines of the radiations produced by the argon or neonlamp.

What is claimed is:

1. In an electro-optical system, a receiver comprising a plurality of sources each producing light radiations of a difierent color, means for applying to said sources a current variable with the tone values of elemental areas but independent of the color of an object scanned, means for blending the radiations from said sources to produce illumination giving the effect of a single color diifering from those of the radiations, and-means for utilizing the blended illumination to produce an image having the same color characteristic throughout.

2. An electro-optical receiver comprising a plurality of lamps respectively supplying light radiations of different colors, means for controlling said lamps by a current variable with the tone values of elemental areas but independent of the color of an object scanned, a color filter associated with at least one of said lamps, means for combining unfiltered and filtered radiation to produce light giving the effect of a single color different from that of the constituent radiations, and means for utilizing the combined radiations to produce an image having the same color characteristic throughout.

3. The method of operating the receiver of an electro-optical system which comprises continuously producing from a single current, having variations representative of the tone values of an object an image of which is to be produced, a plurality of currents each of which varies in the same manner as said single current, simultaneously and separately controlling the production of light radiations of different colors by said latter currents respectively, blending the resultant radiations to produce composite light capable of producing the effect of a single color, and utilizing this composite light of unchanging color characteristic to produce an image having this color characteristic throughout.

4. In an electro-optical system, an image producing apparatus comprising a plurality of light sources each producing light radiations of a different color, said radiations when combined giving the effect of substantially white light, means for applying to said sources a current the amplitude of which is representative of the tone values of elemental areas of the object an image of which is to be produced but independent of the color of said object, means for blending the radiations from said sources to produce substantially white illumination, and means for utilizing the blended radiations to produce an image in substantially white and black and intermediate tone values.

5. In an electro-optical system, image producing apparatus comprising a neon filled glow lamp, an argon filled glow lamp, a color filter associated with one of said lamps of such characteristic that the radiations therethrough from said lamp when combined with radiations from the other of said lamps gives the effect of substantially white light, means for simultaneously applying to said lamps a current the amplitude of which is representative of the tone values of elemental areas of the object an image of which is to be produced but independent of the color of said object, means for blending the radiations from said lamps to produce substantially white illumination, and means for utilizing the blended radiations to produce an image in substantially white andblack and intermediate shades;

6. In an electro-optical system, an image producing device comprising three light sources respectively radiating light of different color,

means for applying to said sources a current whose amplitude is representative of tone values of elemental areas of the object the image of which is to be produced but independent of the color of said object, means for blending the resulting radiations, and means for utilizing the blended radiations to produce an image appear-' ing throughout to have said color difierent from that of the radiations from any of said sources.

HERBERT E. IVES.

Images