US2907909A - Light source - Google Patents

Description

Oct. 6, 1959 w. F. KAZUK 2,907,909

LIGHT SOURCE Filed July 5, 1957 2 Sheets-Sheet 1 y HEATTSRY 32 2 2e/ CATHODE ALQJDE 46 Fig INVENTOR. WALTER FRANK KAZUK ATTORNEYS Oct. 6, 1959 V w, KAZUK 2,907,909

LIGHT SOURCE Filed July 5, 1957 2 Sheets-Sheet 2 TO CATHODE Fig. 4

INVENTQR. WALTER FRANK KAZ UK BY a W ATTORNEYS a phosphor which LIGHT SOURCE Walter Frank Kazuk, Preakness, N.J., assignor to Allen B. Du Mont Laboratories, Inc., Clifton, N.J., a corporation of Delaware Application July 5, 1957, Serial No. 670,160 20 Claims. (Cl. 313-109) This invention relates to light sources and particularly to a device for emitting brightly luminous light which may be modulated, pulsed on and oif, or have its spectral composition varied.

In the past, some light sources such as strobe-lights have employed gaseous devices for the production of pulses of light. Performance of these devices has been limited by the enclosed gas characteristics, such as ionization and discharge properties at predetermined voltage levels. Generally, the response has been restricted to pulses within a comparatively low range of frequencies and continuous modulation of the light beam could not be obtained.

Other light sources have made use of plates coated with produced light when bombarded by electrons emitted from a cathode. These light sources utilized conventional cathode ray tube type structures, wherein a small cathode was placed in a transverse plane at one end of a tube envelope, and a phosphor coated faceplate and anode were located at the target end. Ordinarily, the impinging electrons caused light transmission directly through a glass faceplate which Was coated with phosphor. Special tubes have utilized an opaque reflecting faceplate or anode positioned at one end of a cylindrical glass envelope. The phosphor coated anode was placed at an angle to the longitudinal axis of the tube, presenting an elliptical configuration. The electron beam bombarded the phosphors which projected light at an angle to the tube axis, through the glass cylinder Wall. The size of the cathode and anode in these arrangements have had practical limitations resulting in comparatively small light output. Where desired, a control grid positioned in close proximity to the transverse cathode supplies modulating signals to vary the duration, intensity, and/ or frequency of the electron emission, and the resulting light.

' It is therefore the principal object of the present invention .to provide a novel light source.

' It is another object of the invention to provide an improved structure for a light source capable of developing high luminosity.

,An additional object of the invention is to provide a novel configuration which permits greater control over the duration, intensity, and frequency of the light source.

A further object is to provide a light source having an improved modulation frequency response.

Still another object is to furnish a source of visible or invisible light capable of emitting and controlling a multiple number of separate radiations, simultaneously or in sequence.

According to the present invention a light source utilizing a cathode ray tube type structure permits the attainment of increased light outputs. A cylindrical cathode and grid,and,an anode are arranged concentrically to provide maximum, usable surface areas. Electrons are emitted radially by a longitudinally positioned tubular cathode and pass through a control grid which encircles the length of the cathode. The stream of electrons strikes I large coated surface area which luminosity, while the tubular cathode supplies the large 2,907,909 Patented Oct. 6, 1959,

a phosphor coated inner surface of a cylindrical or conical anode, which may be an integral part of a glass or metal outer shell. Light emitted by the phosphors is projected through a transparent glass faceplate which forms the front end or side of the enclosure. The anode supplies a can emit light of high number of electrons that are necessary. The control grid and phosphor coating may be divided into several sections, permitting independent outputs or combinations of various forms of light emission.

The detailed description and accompanying drawings which follow consider the device in several particular configurations. It is to be understood that these embodiments are chosen for the purpose of explanation and illustration and are not to be construed as defining the limits of the invention. The term light as used herein is assumed to include visible luminous energy as well as invisible radiations suchas ultraviolet and infrared.

Fig. 1 represents a view of one embodiment of the invention utilizing a conical structure. In this view part of the envelope is removed, showing the location of thevarious components and a longitudinal arrangement of multiple grid and phosphor sections;

Fig. 2 indicates a radial arrangement of multiple grid and phosphor sections;

Fig. 3 shows a cylindrical configuration Which emits light in a transverse plane through a longitudinal transparent faceplate; and

Fig.4 illustrates a structural variation of a controlgr'id and an added accelerating grid which can be used to control the flow of electrons emitted by the cathode.

As shown in Fig. 1, a conical or funnel shaped glassstructure 10 forms the outer shell or, envelope of the device, with a transparent faceplate 12 completing the enclosure. The entire inner surface of the funnel is coated with a first layer of conductive metallic material forming an anode 14 and a second layer of phosphorescent material. 'Ihe phosphor coating may be applied homo geneous to cover the full surface of structure 10. Alternatively, separate phosphor coatings 16, 18 and 20, each having difierent light emission properties, may be applied 1 to truncated cone-like areas formed by dividing structure 10 longitudinally into separate peripheral strips or sections.

A hollow cylindrical cathode Q2, having an electron emissive layer 24 on the outer surface, is positioned along the longitudinal axis of the device and extends for substantially its full length. Electron emission may be produced in any suitable manner, such as by use of heater filament wires 26, placed in the hollow cathode center or with an emissive coated heater utilized directly without a cathode structure.

Surrounding the cathode are separate Wire mesh control grids 28, 30 and 32, which control electron emission to phosphor sections 16, 13 and 20, respectively. Alter-' natively, a single control grid encircling the cathode for substantially its full length may be utilized in conjunction with a single homogeneous phosphor coating on the tural support for several components. Another variation of the device utilizes a cap over the open end of the,

cathode to provide added support for the grid and cath ode'structures and to shield the center heater filaments from view. Battery 46 represents a voltage potential supplied between cathode 22 and anode 14.

The description of the operation of the instant device may first be confined to one of the several sections illustrated. The cathode 22 takes the form of a long hollow cylinder with heater filaments 26 running through the center. The filament wires 26 heat the cylinder causing copious electron'emission along the en.- tire length of the electrode surface which is coated with emissive layer 24. An electrostatic field between anode 14 and cathode 22 is established by battery 46, causing the electrons to follow a radial path, passing through the interposed control grid.

The grid impresses signal voltages or pulses of varying frequency, duration and/or amplitude. The signal voltage amplitude variation controls the intensity of electron emission. A sutficiently negative control voltage can halt the flow. The potential field produced by battery 46, which places a positive charge on anode 14 with respective to the negative cathode 22, attracts the modulated stream of electrons to the anode where they are collected. During the process of travel toward the anode, the electron stream impinges upon the phosphor coating causing emission of light. The angular position of the conical surface directs the light through the transparent faceplate 12, with the metallic reflective layer forming anode l4 contributing additional light.

The operation of each longitudinal section shown in Fig. l is the same, with partition plates 34 and 36 preventing electron emission in one portion from activating phosphors in another area. The sectionalized arrangement illustrated is particularly suitable for providing light whose color depends upon the signals applied to control grids 28, 3t and 32, which activate separate colored phosphors 16, 18 and 20. Control voltages may be used to combine various colors to give a particular output hue by varying the intensity of each color component. For example, a combination of red, blue and green phosphors would appear to the eye at a distance to be a certain resultant color. The particular shade of the color would depend upon the intensity of signal applied to each individual phosphor. Special phosphors may also be utilized which emit invisible infrared or ultraviolet light.

Commutation or switching systems known in the art may be employed to operate the various grids simultaneously, sequentially, or independently to activate the particular phosphors and project a wide variety of useful signals, colors, or codes. Detection systems in a receiving unit sensitive to particular radiations may be arranged accordingly to combine or separate various signals as desired. This may again be illustrated with a set of red, blue and green phosphors. Separate control grid signals are applied to each color at the same time. The various colors, though transmitted together, are distinguished at the receiver by individual photocells sensitive to only one color, either red, blue or green. Thus, three independent signals are projected simultaneously and separated into three different channels at the receiver. Similarly, the colors may be programmed or multiplexed in a preset sequence, with only one color being transmitted at a time. The information is then reassembled at the receiver by properly coordinating the red, blue and green photosensitive units.

Fig. 2 shows another version of the instant invention wherein control grids 48, 5t and 52 take the form of arcuate portions of a cylinder. The phosphor sections 54, 56 and 58 take the form of arcuate sections of a cone, respective grids and phosphors being arranged radially about the cathode 22 and separated by longitudinal partitions 60, 62 and 64, which in this configuration need not be transparent. The manner of operation is otherwise the same as heretofore described.

Fig. 3 represents a cylindrical outer container configuration wherein the inner surface of one half of the longitudinal cylinder 110 forms the phosphor coated anode and light is emitted transversely through a transparent longitudinal faceplate 112 which forms the other half of the cylinder. This differs from the conical structure of Fig. l, in that light is projected through the side of the cylinder rather than out of the end of the cone. Again, multiple grid and phosphor sections may be positioned to occupy portions of the length of the envelope or arcuate strips of the periphery of the cylinder. In this instance, the longitudinal partition plates would have to be transparent while the circular plates need not be.

in Fig. 3 the end of the cylinder has been cut away'to show the metallic layer 114 and a single phosphor coating 116 deposited on the first or rear half of cylinder 110. Only one half of cathode 122 is utilized in this configuration and only the useful surface need be coated with electron emissive material. Grid 128 is also positioned to control electron flow from the proper portion of the cathode. The transparent faceplate 112 may take.

the form of a fiat rectangular or planar sheet extending for the length of the cylinder. Correspondingly, the cathode may be constructed in the form of one half a cylinder, having a fiat side along its length. The phosphor coated anode and the faceplate may occupy various arcuate portions of the periphery of the cylinder and extend for various lengths.

Fig. 4 illustrates another control grid arrangement 66 in the form of a helix, which may be employed to supply modulating signals. An additional accelerating grid 68 may be placed around the control grid and cathode to obtain even greater light emission by increasing and speeding the flow of electrons toward the anode. iOther components remain unchanged.

The concentric arrangement of anode and cathode of the instant invention provides larger emissive surfaces and develops greater light output than available from previous phosphorescent devices. The present structure also avoids the frequency and voltage limitations inherent in prior art gas tube devices. The lengthwise controlgrid configuration adjacent to and positioned about the cathode furnishes a large area for improved regulation of electron flow.

Modifications of the invention may employ a metallic shell in place of the glass envelope and conductive coating. In this case, the shell would act as the anode. To facilitate physical handling of the device, the anode may be placed at ground potential. Large areas of metal would have the advantage of providing efficient cooling surfaces and prevent burning of the phosphors. The envelope may have other cross sectional configurations such as rectangular, elliptical, parabolic, etc. The anode and cathode surfaces and the control grid may alsotake various shapes, forms, or curvatures other than those described. For production of multiple radiations, separate cathodes, heaters, and anodes may be utilized. In addition, special purpose faceplates may beemployed to meet individual requirements.

The described invention may be used in a number of ways. Firstly, it may be employed for photographic, stroboscopic, and other light flashing purposes, and will provide a highly luminous pulsed or modulated light at higher repetition rates than heretofore possible. Secondly, the light produced by this invention may be modulated at any given frequency, and by tuning the receiving unit to the modulation frequency, the light or pulses thereof may be distinguished, even in bright daylight. Thirdly, information applied to the various control grids will produce light pulses of different colors or radiations, which will correspond to a particular combination of. input signals. Fourthly, the described invention may' be used in short range visual communication systems where in it is desirable to avoid interception of radio', signals or coded information. The use of intensity and/or fre quency modulated light may be useful for direct communication, with highly directional sensitive light responsive devices such as photocells being employed as sensing elements in the receiving unit to detect and reconvert the modulated light into electrical information.

While only a single embodiment of the invention has been indicated, it will be apparent that the invention is not limited to the exact forms or use illustrated and that many variations may be made in the particular design and configuration without departing from the scope of the invention, as set forth in the appended claims.

What is claimed is:

l. A light source of high luminosity comprising: an outer container having a plurality of separate adjoining peripheral surfaces, each said surface having a different light emission property; a cathode located axially within said container; means for causing electron emission from said cathode; a control grid adjacent to and encircling said cathode; means causing a first portion of said container to act as an anode for attracting and collecting said electrons; at phosphor coating occupying at least one of said surfaces of said container, said coating emitting light upon said collection of said electrons; and means to direct said light, said means comprising said surfaces of said container and a transparent faceplate through which said light is directed, said faceplate enclosing a second portion of said container.

2. The device of claim 1 wherein said outer container is in the form of a cylinder.

3. The device of claim 2 wherein said light emitting phosphor occupies a first peripheral portion extending along the length of said cylinder.

4. The device of claim 3 wherein said transparent faceplate occupies a second peripheral portion extending along the length of said cylinder.

5. The device of claim 2 wherein said transparent faceplate is planar and extends along the length of said cylinder.

6. The device of claim 1 wherein said outer container is funnel shaped.

7. The device of claim 6 wherein said transparent faceplate encloses the wide end of said funnel shaped container.

8. A light source comprising: containing means having a plurality of separate adjoining surfaces disposed about the inner periphery of said containing means, each said surface having individually distinct light emission characteristics; longitudinally disposed means within said containing means for radially emitting electrons; means for controlling the flow of said electrons; means circumjacent said electron emitting means positioned radially outward of said control means for collecting said electrons; means adjacent said collecting means for emitting light upon said collection of said electrons, said light emitting means occupying at least one of said surfaces of said containing means; and means for directing said light.

9. A source of light having large emissive surface areas comprising: an outer envelope structure; means for emitting electrons radially about the longitudinal axis of said structure, said means comprising an axially located tubular cathode having an electron emissive layer on the surface thereof and heater filaments within said cathode; means for controlling the flow of said electrons, said means comprising a control grid circumjacent to to control said electrons; means for attracting and collecting said electrons, said means comprising said envelope structure surrounding said axial cathode and control grid; means for emitting a plurality of light ratiations upon said collection of said electrons, each said radiation having a discrete spectral composition, said means comprising a plurality of adjoining separate and distinct phosphor coatings on the inner surface of said surrounding envelope structure; and means for directing said light, said means comprising said envelope structure and a transparent faceplate through which said light is directed, said faceplate enclosing a portion of said envelope.

10. The device of claim 9 wherein said means for controlling the flow of said electrons comprises a plurality of control grids. I

11. The device of claim 10 wherein said plurality of control grids are individually positioned circumjacent said cathode in a longitudinal arrangement, each said grid encircling a portion of the length of said cathode.

12. The device of claim 10 wherein said plurality of control grids are individually positioned about said cathode in a radial arrangement, each said grid being adjacent to a peripheral portion of said cathode and extending said cathode, whereby modulating signals may be applied for substantially the full length of said cathode.

13. The device of claim 9 wherein said plurality of phosphor coatings are arranged in separate peripheral strips, each said strip encircling a portion of the length of said envelope structure.

14. The device of'claim 9 wherein said plurality of phosphor coatings are arranged in longitudinal strips, each said strip covering a portion of the periphery of said envelope structure.

15. The device of claim 9 wherein said envelope is partitioned into a plurality of sections, each section having an individual control grid and a coacting individual phosphor coating, whereby each said grid controls electron flow only to said coacting phosphor coating within the same said section, each said section being capable of emitting light independently of other said sections.

16. The device of claim 15 wherein said plurality of sections having said individual control grids and coacting phosphor coatings are arranged to occupy adjacent peripheral areas along the longitudinal axis of said envelope.

17. The device of claim 15 wherein said plurality of sections having said individual control grids and coacting phosphor coatings are arranged radially about the longitudinal axis of said envelope each occupying an angular sector of the periphery of said envelope.

18. The device of claim 9 wherein said envelope is funnel shaped and said faceplate encloses the wide end of said envelope.

19. The device of claim 9 wherein said envelope is in the shape of a cylinder and said faceplate encloses a peripheral portion of said cylinder. n,

20. The device of claim 19 wherein said faceplate is planar.

References Cited in the file of this patent UNITED STATES PATENTS 2,119,309 Batchelor May 31, 1938 2,222,668 Knoll Nov. 26, 1940 2,392,161 Leverenz Jan. 1, 1946 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 2,907,909 October 6, 1959' Walter Frank Kazulc It is hereby certified that error appears in the -printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 2, lines 39 and 40, for "homogeneous" read homogeneously column 5, line 47, after "means" insert cir'cumjacent said electron emitting means lines 48 and 49, after "means" strike out "circumjacent said electron emitting means"; column 6, line 4, for "ratiations" read radiations Signed and sealed this 22nd day of March 1960,

(SEAL) Attest:

KARL H0 AXLINE Attesting Oflicer ROBERT C. WATSON Commissioner of Patents

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