US1929589A - Electrical transmission of colored pictures - Google Patents

Description

Oct. 10, 1933. H. w. JOY 1,929,589

ELECTRICAL TRANSMISSION OF cm-ontn. PI'cg'UaEs FiI'ed July 30, 1928 2 Sheets-Sheet 1 00k. 10, 1933. w, JOY 1,929,589

ELECTRICAL TRANSMISSION OF COLORED PICTURES Filed July 30, 1928 2 Sheets-Sheet 2 Patented Oct. 10, 1933 UNITED STATES PATENT OFFICE Henry William Joy, Brooklyn, N. Y. Application July so, 1928. Serlal No. 296,183

'lClaims.

My invention relates to what is popularly known as television and particularly to the electrical transmission of visual color, whereby the received image appears in substantially the same colors as that of the original at the moment of transmitting and receiving, life motion where present is also transmitted and reproduced.

The general principles governing our conception of visible colors and the optical illusion of color blending by persistence of direct and complementary color vision are well known and I apply these principles together with certain modifications to my invention for the electrical transmission of visual color. The principles of persistence of direct and complementary color vision have been well demonstrated and made use of in the production of moving pictures in their apparent natural colors.

In order to electrically transmit a focused scene, image or picture, it is necessary to split or divide the image into a multiplicity of dots or parts and transmit electrically the light intensity or value of the parts or dots, singly, in rapid and regular sequence. One or more series of dots or picture parts may be transmitted at one time depending upon the number of electrical circuits or wave systems employed but in order to better describe my invention, I will confine my description to the use of but one circuit or wave path, altho I do not confine its use to such.

Before considering my invention, it must be well understood that light or color cannot be transmitted as is, by any known electrical method; means must be employed to translate any given light or color value or intensity into an equivalent electrical value and for this purpose, it is customary to employ what is termed a photo electric cell or element that shall respond instantly to light or color change. In practice, there are many cells or light sensitive elements bearing the property of changing electrically in ratio to light changes but respond irregularly to change of colored light and this irregularity must be taken into consideration when it is desired to transmit scenes in natural colors. The received image should also be illumined by colors or lights that collectively constitute the visible spectrum. From this, it can be readily seen that defects existing in the transmission of colors can be rectified in the receiver by employing suitable color filters or methods for breaking up the colors in transmission to harmonize with the color filters and lighting as employed in the receiver.

In transmitting a scene in colors, I use a revolving perforated disc or other scanning means bearing light filters arranged to pass the light from or through one dot or picture part, once. for every color filter or unit employed, so that 00 each illumined dot 'is transmitted two or more times in sequence, as each illumination is passed thru color filters of opposing value, it follows that each dot is analyzed by rapidly alternating complementary colors or their equivalents which in turn is resolved into corresponding electrical values by the photo-electric element. This procedure is repeated until the whole picture area has been color analyzed. In constructing such a color filter disc for my purpose, the colors selected may be, say, red-orange and blue-green, the one alternating with the other, but as the usual photo electric cell is not generally equally sensitive to both of these colors, adjustments can be made by varying the color densities or tones until experiment indicates the cell to be passing both opposing colors equally, this can be readily ascertained by transmitting the light reflected from white paper or clear sky. Should it be desired to employ a photo electric cell that is totally so blind to red light, or any distinctive color? this condition can be met by omitting the red filter entirely and so transmit by using the bluegreen or opposing filter alternating with a nonfiltered or white beam, care being taken to maintain similar light intensities which can best be carried out by using a smaller hole for the white beam and adjusting the density of the blue-green or opposing filter to suit. The principles of color balancing in natural color photography are well understood by those skilled in the art, and must also be applied to television practice with certain modifications to compensate for color blind transmission. From this, it can be readily seen that by my method of color transmission an approximation to natural colors can be successfully recorded when one major color only is transmitted; provided a diffeemtial of color values is alternately transmitted at a periodicity well beyond persistence of color vision, any color 100 compensation is possible by the selection of suitable color filters for the receiver, ,i. e., should a red ray be missing in the transmitter, it can be supplied by the receiver, simply because in television actual colors are not transmitted.

In selecting the colors for my receiving filters I use preferably red-orange and blue-green, and a white light as illuminant, same being modified by the picture current actuating a light valve or other-means of light modulation. 110

It must be understood that synchronous operation of transmitter and receiver must be maintained, otherwise picture distortion and color reversals will take place, i. e., transmitted red will be received as green and so on.

Another adaptation of my method of color transmission may be utilized by the employment of but one color only alternating with a balanced white beam and used in receiving; in this instance, a fair approximation to visual natural colors is obtained by complementary color vision. It is well known that when the eye is bombarded by a rapidly occurring color, a sense of complementary color is aroused and. the real and the assumed colors will harmonize to produce a sensation of color unity. It will be noted there are many modifications of my invention, any. of which may be utilized to assist in overcoming the color deficiencies existing in the various light recording and producing elements.

Reference to my drawings will more clearly describe my invention. Fig. 1 illustrates the transmitting and receiving discs which are identical in design and as applied to my method using two opposing or complementary colors, such as redorange and blue-green.

Fig. 2 illustrates the transmitting and receiving discs as applied to my method of using one color only alternating with a balanced non-filtered light.

Fig. 3 illustrates the transmitting and receiving discs which are identical in design, as applied to my method of using more than two colors for the entire color range transmission.

Fig. 4 is a diagrammatic showing of an apparatus which may be used for transmitting.

Fig. 5 is a similar view illustrating one embodiment which may be used for receiving.

On referring again to Fig. 1, as an illustration, G denotes green and R denotes red. C is the natural center of the disc. Taking G I and R I as being the first pair of colors, it will be noted that both are equi-distant from the center C, this applies to each pair of colors on the disc and each pair such as G2 and R2 and so on is located in sequence nearer the center C. It is understood that when using one wave transmission one hole only can be transversing the picture area at one must be provided to cover the entire picture area before the leading hole GI is again in location.

The colored light filters may be small pieces of suitably colored gelatine individually secured to the respective holes. The regular approach of each pair of holes toward the center C is equal to the approximate diameter of one hole. It is desirable that all holes in Fig. 1 and Fig. 3 are of the same diameters in each individual disc.

The disc Fig. 2 is similar to the disc Fig. 1 with the exception of the diameters of the holes, it is preferable to have the color filtered holes R in Fig. 2 of larger diameter than the open holes W, as in this disc if all holes were of same diameter the non-filtered holes W would pass a greater volume of light than the filtered holes R, for which compensation is made by making the W holes of a smaller diameter than the R holes. The object sought in each application of my invention is to transmit and so receive equal alternating light intensities of each color employed; as is well known, the sum total of equal intensities of red-orange and blue-green, is white light, therefore should one color be more intense than its complementary, such color will predominate of any set being equi-distant from the center C.

Fig. 4 illustrates one method of transmitting when applying my invention for color analysis of the object (1" which may be an image, picture, or scene. e is a condensing lens whose function is to throw a condensed image upon the disk ,f, same being an edge view of either Fig. 1, 2, or 3, as required according to the color sensitiveness of the cell h; g is a synchronous motor in phase with the receiving motor 1, Fig. 5; h. is a light sensitive cell having a preferred range of constant sensitiveness to all visible colors; i is the customary transmitting apparatus receiving the amplified current values-as emitted by the cell h through the customary amplifying circuits.

Fig. 5 illustrates one method of receiving when applying my invention for the viewing of received images in colors. "7 is a customary radio receiving set feeding the Kerr cell 0; k is an edge view of either Fig. 1, 2, or 3, as required to agree with the transmission characteristics of the cell 71. and disk "1", Fig. 4; Z is a synchronous motor in phase with the motor g, Fig. 4; m is a screen upon which the image is received; is a magnifying lens; "0 is a Kerr cell, containing polarizing prisms and usual magnetic field rotation coil; p is a collimeter lens, whose function is to throw a parallel beam of white light from the lamp "q, through the Kerr cell, rotating disk, lens, and on to screen m; q is a high intensity lamp or source of white light; r is a reflector to assist the lens p. The Kerr cell as here indicated, functions as a white light transmission valve, but other means may be so employed.

Figs. 4 and 5 together illustrate my invention as applied to the employment of but one wave band. A plurality of wave bands may be employed by repeating the procedure for every wave band, as required.

In using my method of transmitting alternating colors, the light receiving element or cell as located in the transmitter should be responsive as far as possible to the entire range of visible spectrum colors, it is, however, possible to provide compensation if necessary by varying the colors of the filters actually employed; in transmitting, the question of correct colors being used is immaterial as any light sensitive cell can only register varying light intensities; it is therefore in practice the function of the transmitting disc to simply pass onto the light cell opposing light values of balanced intensities which it does by being provided with alternating colors or holes of varying areas, alternating with balanced color filtered light beams.

In receiving, the colored picture is reconstructed for direct vision. The source of light used for receiving should be the equivalent of white light and the receiving color disc should be provided with colored filters that are substantially correct, i. e., the sum total of all colored lights when passed equally by the respective receiving disc should be apparently white. For instance, when the source of light in the receiver is deficient in producing the entire spectrum colors, the disc or principles of Fig. 2 may be used to advantage and the sense of complementary color vision relied upon to produce apparent color harmony.

It must be well understood that with so many types of light recording and reproducing cells, tubes or elements at disposal, a selection should be made to meet the required conditions of color transmission as nearly correct as the varying characteristics will permit. An ideal photosensitive cell for transmitting would be one with equal sensitiveness to all visible colors and an ideal source of light for receiving would be a pure white light which obviously would contain all visible colors equally. Failing the ideal, compensation can be effected by resorting to careful color balancing as already indicated.

For the sake of convenience, I shall employ the term object in the claims, although, in so doing, it is to be understood that I do not use this the same distance from the center of the disk word in a technical sense as contrasted to an image, but intend by the word object to cover what in the art are usually termed objects and images or in fact any optical field.

Whilst I have disclosed but a single embodiment of my invention, it is capable of modification therefrom without departure from the spirit and scope thereof, and it is desired therefore that only such limitation shall be imposed on the appended claims as are required by the prior art, or indicated therein.

I claim as my invention:

1. In a picture transmitting system, a scanning member having a plurality of sets of openings therein, all openings in a set being adapted to transmit the same beam of light, and one of said openings transmitting white light and the other a color, said second-named opening being larger than the first-named one.

2. In a picture transmitting or receiving system, a scanning member having a multiplicity of openings therein so arranged in a series that an object is scanned in sequence through said openings, said openings having color filters associated therewith and the filters over successive openings being arranged in successive sets, with the aggregate components of all filters in any set giving to the eye substantially the impression of natural color, and the filters in any one set scanning the same area of the object.

3. In a picture transmitting or receiving system, a rotatable scanning disk having a multiplicity of openings therein so arranged in a se ries that upon rotation of the disk an object is scanned in sequence through said openings, said openings being arranged in successive sets in the series, with the openings in each set adapted to transmit difierent light components and with the aggregate of the components transmitted by all openings in any set giving to the eye substantially the impression of natural color, and the openings in any one set scanning substantially the same area.

4. In a picture transmitting or receiving system, a rotatable scanning disk having a multiplicity of openings therein so arranged in a series that upon rotation of the disk an object is scanned in sequence through said openings, said openings being arranged in successive sets in the series, with the openings in each set adapted to transmit different light components and with the aggregate of the components transmitted by all openings in any set giving to the eye substantially the impression of natural color, all openings in each set being disposed at substantially and the openings in difierent sets being disposed at difierent distances from said center.

5. In a picture transmitting or receiving system, a rotatable scanning disk having a multiplicity of openings therein so arranged in a series that upon rotation of the disk an object is scanned in sequence through said openings, said openings being arranged in successive sets in the series, said sets being located upon arcs of concentric circles with the radiiof said arcs progressively decreasing from one end of the series to the other, and with all the openings in any given set disposed on one of said arcs.

6. In a picture transmitting or receiving system, a rotatable scanning disk having a multiplicity of openings therein so arranged in a series that upon rotation of the disk an object is scanned in sequence through said openings, said openings being arranged in successive sets in the series, said sets being located upon arcs of concentric circles with the radii of said arcs progressively decreasing from one end of the series to the other, all the openings in any given set being disposed on one of said arcs and the openings in each set being adapted to transmit different light components, the aggregate of the components transmitted by all openings in any set giving to the eye substantially the impression of natural color.

7. The method of electrical transmission or reception of a picture which comprises successively scanning difierent small areas of an object, each area being scanned in succession by light components of different values whose resultant gives to the eye substantially the impression of natural color.

HENRY WILLIAM JOY.

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