US3391296A - Color-producing tube having screen containing plurality of birefringent materials - Google Patents

Description

ESO'NQOQ ALW/v A. SNA/DER SCREEN CONTAINING PLURALITY S L u@ R6 E m uw P Ml. A .nl N w Smm@ w Anm@ Q AFM m1.. HE ,J Amn n. BBF .k wp s r E, m mw b w w w of w c U wf 3 R ..1 y M M Al\ O D. n QOL 6o 1 9C 1. Q j 2 E V. .M .J H M COLOR-PRODUCING TUBE HAVING SCREEN CONTAINING PLURALITY OF BIREFRING- ENT MATERIALS Alvin A. Snaper, 9722 Casalia Ave., Chatsworth, Calif. 91311 Filed Oct. 1l, 1965, Ser. No. 494,689 1 Claim. (Cl. 313-91) ABSTRACT' 0F THE DISCLQSURE The present invention is concerned with producing an output -beam of light whose color is determined by the point at which an electron beamis incident on a phosphor layer. An` 'embodiment of the invention includes two parallel differently polarized layers between which is sandwiehed a layer of birefringent material, the particular color of the output beam corresponding to the characteristics of either the birefringent material or the polarized layer, or both, behind the phosphor layer whereat the electron beam strikes it.

The present invention relates-in general to apparatus for producing and displaying colors andvcolor patterns in response to electron beams and more particularly relates to apparatus of the kind mentioned in which polarized and birefringement materials are used and form an essential part of the apparatus.

At the present time, different phosphorsare used to convert an electron beam to respectively different colors. This is true, for example, in a color television tube where tri-color phosphors are deposited in a dot pattern or mosaic on the face of the tube, the color or combination of colors visi-bly appearing in any area of the tubes face at any one time being determined by which of the phosphors are being struck by an electron beam at that time. One of the problems involved in the use ,of phosphors is that the phosphors eventually-erode orde'teriorate in quality, with the result that the colors also eventually `deteriorate from their original brightness and sharpness. In addition, phosphors of different color response have different chemical,l electrical and physical properties which makes it necessary in color phosphor cathode ray tubes to adjust the system output to the lowest efficiency phosphor in order to obtain coior balance. This is normally accomplished by downgrading or'reducing the output of the more eliicient phosphors .to the level of the least efficient. Note-red is usually the least eicient. A further ditiiculty encountered in connection with this prior technique is that phosphors are, relatively speaking, not easy to handle or, stated differently, to work with, and, therefore, their use requires the application of special procedures which, in turn, increases the cost of such tubes.

The present invention substantially eliminates these prior art disadvantage by entirely eliminating the requirement for phosphor materials as the primary source of color, and it does so by making use of the phenomenon that colored light is obtained when ordinary white light is successively subjected to the processes of polarization and birefringence. More particularly, the present invention is based on the concept that white light passing through a polarizing plate, then a -birefringent material of uniform characteristics andthereafter viewed through an analyzing polarizer, can be made to produce any color of the spectrum, which portion of the spectrum being dependent upon and controlled by either the specific bireringent materialchosen, its thickness, its uniform strain characteristics, the angle of polarization of the analyzer, or combinations thereof.

Based on this concept, a first embodiment of the invented States Patent tion is provided with a sandwich arrangement of 4 layers, namely, a white phosphor layer followed by a pair of differently polarized layers between which is located a layer made up of materials having respectively different birefringence qualities. As is well known, white phosphor has the quality of producinga beam of white light when a stream of electrons is incident thereon. Accordingly', different colors may be obtained by directing an electron beam toditferent areas on the white phosphor layer. In other embodiments, instead of using a layer Ymade up of different birefringent materials, the same results are obtained by using instead the same birefringent material' throughout the layer but either varying the thickness of the material at different points thereon or varying the plane of polarization over different areas of the outer polarizing layer. Finally, ina last embodiment that is especially adapted for use in a television tube or the like, a mosaic of birefringent material having diverse birefringent qualities corresponding to the desired three-color output is used. In this embodiment, an aperture mask corresponding to and in registration with the mosaic is also employed, the several-electron beams being simultaneously and selectively directed through the holes in the mask to produce the desired colored pattern.

It is, therefore, an object of the present invention to provide electron-beam apparatus that facilitates the production of visual color displays and that is more versatile in terms of its possible applications than prior equipment of this kind.

It is another object of the present invention to provide apparatus for producing color in response to the impingement of an electron beam that is less expensive, less diicult to manufacture, and more eicient relative to existing apparatus.

It is a further object of the present invention to provide apparatus for producing color in response to the impingement of an electron beam without the use of colorproducing phosphors.

The novel features which are believed to be characteristic of the invention, both as to its organization and method of operation, together with further objects and advantages thereof, will be better understood from the following description considered in connection with the accompanying drawing in which several embodiments of the invention are illustrated by way of example. It is to be expressly understood, however, that the drawing is for the purpose of illustration and description only and is not intended as a denition of the limits of the invention.

FIGURE l is a cr0sssectional view of a rst embodiment of the invention in which the birefringent layer is made up of a number of different materials having correspondingly different birefringent qualities;

FIGURE 2 illustrates a modification of the' FIG. l embodiment in which the birefringent layer is made up of the same material throughout but of several different thicknesses to provide the different birefringement effects;

FIGURE 3 illustrates still another modification of the FIG. l embodiment in which the qualities of the polarizing material are varied rather than the birefringent material;

FIGURE 4 is lan exploded view in cross-section of another embodiment of the present invention in which a biretringent dot screen and aperture mask are utilized; and

FIGURE 5 is a perspective view that illustrates how the FIG. 4 apparatus may be extended to provide a structure that is suitable for use iri tubes of the color-television type.

For a consideration of the invention in detail, reference is now made to thedrawing wherein like or similar parts or elements are given like or similar designations throughout the several figures. In FIG. l, the embodiment is shown to basically include a multi-layered formation of materials placed in face-to-face relationship to form a sandwich arrangement of them. More specifically, it includes a pair of inner and outer polarizing layers 10 and 11, respectively, a birefringent layer 12 positioned between the polarizing layers and a white phosphor layer 13 deposited on the front face of polarizing layer 10. Although not essential, layers 10 and 11 are preferably cross-polarized with respect to each other. Regarding these polarizing layers, there are many well known materials that can be used, such as Polaroid, the trade name of a material in sheet .form usually consisting of oriented crystals of herapathite on or in a transparent base or carrier. The patent to R. W. Weeks et al., Patent No. 2,983,824, discloses this fact at column 3, lines 38- 41 thereof. However, by way of further example, suitably oriented crystal film layers of iodoquinine sulfate may also be used. As for layer 12, it is made up of two or more materials having respectively different birefringence characteristics or qualities that respectively occupy different areas or portions of the layer. Layer 12 in FIG. l illustratively includes three different birefringent materials that are respectively designated 12a-12e. Many different transparent materials, such as polymerized ethylene, (CZHQH, commonly known as polyethylene, exhibit the quality of birefringence and may be used herein in layer 12. Some other common materials that are satisfactory for application herein are Celluloid, which is a proprietary product consisting basically of a solid solution of celiulose nitrate and a plasticizer, cellulose acetate butyrate, and Cellophane, which is a form of cellulose acetate. Furthermore, many inorganic and organic crystals exhibit this quality of birefringence. Examples of the inorganic kind are calcite calcium carbonate, a common mineral, and quartz oxide of silicon, another common mineral. The described sandwich or panel arrangement of layers 10-13 requires an electron beam for its operation and, therefore, it is normally mounted i1 a cathode-ray type of tube with phosphor layer 13 facing the tubes electron gun. However, since cathode-ray tubes are standard items, for sake of clarity and expediency such a tube is only schematically represented here by an electron-beam source 14.

In operation, when the electron beam produced by source 14 is directed against white phosphor layer 13 in a region thereof that faces birefringent material 12a, such as beam 14a, a corresponding beam of white light is generated by the phosphor at the point of incidence that passes through polarizing layer 10 to birefringent layer 12. Accordingly, the light reaching layer 12 is plane polarized. At this point, various components of the light beam are impeded or shifted in phase by material 12a, with the result that only a spectral portion of the light is allowed to pass through outer polarizing layer 11, thereby producing a color output 15a by what may be termed subtractive filtering of the white light input. The actual color of output light 15a is determined by the particular composition and characteristics of birefringent material 12a. By directing the beam to other regions of phosphor layer 12, as illustrated by beams 14b and 14C, still other colors may be obtained. Thus, for the reasons previously explained, an electron beam 14b ultimately results in an output beam of light 15b whose color is determined by the composition and characteristics of birefringent material 12b and an electron beam 14e` likewise causes an output beam of light 15e to be produced whose color is determined by the composition and characteristics of birefringent material 12C. Since, as was previously mentioned, materials 12a-12e are of different composition and, therefore, have correspondingly different birefringence characteristics, the colors of light beams 15a-15e are likewise different from one another. It will be obvious to those skilled in the art that by successively defiecting the electron beam to different regions of phosphor layer 13 or by alternately widening and narrowing the electron beam, different color combinations. schemes and patterns may be displayed.

A birefringent layer of uniform thickness but of different composition was utilized in the FIG. l embodiment. However, the same kind of output color effects can be obtained by using instead a birefritgent layer made of the same material throughout but of different thicknesses over different areas or regions thereof. Such a modification is illustrated in FIG. 2 wherein the different thicknesses of layer 12 are respectively designated 12a-12c. Hence, in this case also, electron beams 14a- 14e will respectively produce differently colored beams of light 15a-15e.

The FIG. 1 embodiment may be modified in still another way and yet produce the s'ame o utput display of color. More specifically, instead of employing a birefringent layer of uniform thickness and varying composition or a layer of the same material throughout but of varying thickness, a birefringent layer of uniform thickness and uniform composition may be used together with an outer polarizing layer whereon different areas or regions are differently polarized. A modification of this kind is illustrated in FIG. 3 wherein the birefiingent layer of uniform composition and thickness is designated 12' and the outer polarizing layer of varying polarization is designated 11', the three differently polarized regions thereon being designated 11a, 11b and ll'c. Accordingly, as before, in response to the impingement of the electron beam 14a-14C on phosphor layer 13, differently colored beams 15a-15c are produced, the particular colors obtained being primarily controlled by the planes of polarization 11a-11c.

Although obvious, it should nevertheless be mentioned that the several different features of the FIG. l-FIG. 3 devices may also be combined to provide output color effects. Thus, for example, in a single arrangement, a birefringent layer made up of different compositions of material (FIG. 1) or one having regions of different thickness (FIG. 2) may also be combined with a polarizing layer having differently polarized areas (FIG. 3).

An exploded view of a second embodiment of the i1- vention is shown in FIG. 4 wherein a birefringent dot screen 16 is mounted between cross-polarized layers 10 and 11 and an aperture mask 17 is mounted in front of light phosphor layer 13. More specifically, in this ernbodiment, layer 16 is made up of a large number of dots or tiny regions of birefringent material arranged in some sort of pattern or mosaic configuration, these so-called dots or tiny regions being in registration with the holes through mask 17. Thus, the electron beam only has access to a dot or tiny region of birefringent material by first passing through the'` associated mask aperture and when this is done, a corresponding tiny beam of colored light will emerge from polarization layer 11. The same birefringent material may be used in forming the mosaic of screen 16 or, needless to say, different birefringent materials may be used, or a combination of both. In the first case, the same output color would be obtained irrespective of the orientation of the electron beam, whereas in the latter instances the color obtained at any time would depend on which of the mask apertures the beam was then being directed through. Moreover, it will be recognized from the descriptive material presented previously that instead of using different birefringent materials, the desired color effects may also be obtained through the use of a single composition of material, either by varying the thickness of the material in the different dot areas' or if the same thickness is used, by providing an analogous dot array on polarizing layer 11 in which the planes of polarization in the dot areas vary in accordance with the desired color pattern.

The FIG. 4 embodiment lends itself for use in a colortelevision tube and the manner in which it can be adapted for such use is illustrated in FIG. 5 to which reference is now made. As shown therein, a sandwich or panel arrangement of the same layers 10, 11, 13 and 16 is mounted on the inside surface of the tubes face plate designated 18 and aperture mask 17 is positioned somewhat in front of it. As is well known; television tube generates three basic colors from which all other color gradations are substantially produced. Accordingly, the mosaic of dots in birefringent layer 16 is likewise arranged to produce three different colors and any one of the several techniques previously mentioned may be utilized to do so.' As shown in the ligure, all tli'e dots ultimately producing one color is designated by the capital letter A, those instrumental in producing the second color is designated by the capital letter B and the rest are designated by the letter C. In the fabrication of a birefringent layer for .application in a color television tube, a dot pattern, of birefringent material consisting of three different variations corresponding to the desired three-color outputrnay be produced by a variety of means. Thus, for example, in one manufacturing technique a uniform layer of birefringent plastic is embossed with a heated pattern die to produce the desired pattern in the form of three levels of thickness, each dimension of thickness being that required to produce a specific color when light fromy the electron beam excited phosphor impinges thereon. It is also possible to produce a three-level birefringent layer by conventional means similar to those in use for standard deposition of tricolor phosphors in which patterns of; dots are deposited by silk screening or photographic etching means. Vapor deposition through suitable masks can also be utilized.

Although constructed differently, the operation of the FIG. 5 apparatus is basically the same as would be found in a standard television tube. Thus, when only one electron beam is directed through an aperture in mask 17 to i-mpinge on phosphor layer 13, only one of the three birefringent dots associated with that aperture is illuminated, thereby causing only one of the three colors to be produced. On the other hand, when two electron beams are directed through the aperture, two of the birefringent dots are illuminated and, therefore, two of the three basic colors are produced and, as may be expected, when all three electron beams are generated and directed through the aperture, all three colors are produced. This last instance involving three electron beams is illustrated in FIG. 5, all three beams being shown passing through an aperture of mask 17 to impinge upon three points on the surface of phosphor layer 13 that face an associated cluster of three birefringent dots A, B and C.

Although a number of particular arrangements of the invention have been illustrated above by way of example, it is not intended that the invention be limited thereto. Accordingly, the invention should be considered to include any and all modifications, alterations or equivalent arrangements falling within the scope of the annexed claim.

Having thus described the invention, what is claimed isz.

1. Color-,producing apparatus comprising: a sandwich arrangement of layers including rst and second polarized layers of light-transparent material having different planes of polarization, a plurality of coplanar birefringent layers having respectively different birefringence qualities mounted between said first and second layers, and a third layer of phosphor material for producing white light in response to the incidence of an electron beam thereon; and means for producing an electron beam and selectively directing it for impingement on different areas of said third layer.

References Cited UNITED STATES PATENTS 2,184,999 12/1939 Land et al. 350--158 2,481,622 9/1949 Rosenthal 313-91 X V2,531,823 11/1950 Murray 350-158 X 2,607,272 8/1952 Bond 350-157 2,663,171 12/1953 Boone S50-158 X 2,829,555 4/1958 Keston 350-157 X 2,983,824 5/1961 Weeks et al 313-91 X 3,131,253 5/1964 Zandman et =al. 350-158 X 3,148,281 9/1964 Fyler- 313--91 X '2,598,941 6/1952 Roth B13-92.5

ROBERT SEGAL, Primary Examiner.

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