US2571991A

US2571991A - Color television tube

Info

Publication number: US2571991A
Application number: US141611A
Authority: US
Inventors: Jr Richard L Snyder
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1950-01-31
Filing date: 1950-01-31
Publication date: 1951-10-16
Anticipated expiration: 1968-10-16

Description

Oct 16, R. L. SNYDER, JR

COLOR TELEVISION TUBE original'Fned oct. 22, 1946 lthe conducting strips. are preferably arranged in substantially parallel `Patented Oct. 16, 1951 UNITED STATES' PATENT oI-rlcs COLOR TELEVISION TUBE Richard L. Snyder, Jr., Aberdeen, Md., assigner to Radio Corporation of America, a corporation of Delaware Continuation of application Serial No. 704,953, October 22, 1946. This application January 31, 1950, Serial No. 141,611

16 Claims.

' copending application.

Color television tubes as vheretofore made and used contained a screen giving white light with a color filter rotating in front of the screen for producing the colors of the picture by synchronizing the movement of the filter with the colors produced at the transmitter. This is not entirely satisfactory as the iilters are mechanically controlled and it is diiiicult to keep the mechanism in synchronism. Also, the initial cost of the apparatus and maintenance expense is relatively high.

It is an object of this invention to produce color television at the receiving station without rotating mechanical parts.

Another object of the invention is to produce the colors of a picture entirely by electron control.

Another object of the invention is to provide a multicolor phosphor target electrode and to direct the cathode ray beams to the phosphor areas of the target producing the color called for by the incoming signals.

Another obiect of the invention is to provide an electron discharge device for color image reproduction comprising a target electrode including a transparent plate and strips of electrically conducting material arranged adacent to the transparent plate and having coatings of phosphor material on surfaces thereof such as the side surfaces which can be hit by the electron beam of the tube and can be observed through the transparent plate without requiring passage of light through the conducting strips. Preferably, alternate strips are connected in one ,group having phosphor coatings fluorescing in one color, the other strins are connected together in a grnm having phosphor coatings unrescing in a second. different color and the transparent plate has thereon a nhosnhor coating uorescing in a third color different irom the coatings on The conducting strins relation edgewise of the plate and substantially et right angles to the direction of scanning of the electron beam.

Other objects of the invention will appear in the following specification, reference being had to the drawing in which:

Fig. 1 is a plan section of a cathode ray tube illustrating the invention, being taken on a plane parallel to the line scansion;

Fig. 2 is an elevation of a small section of the phosphor screen suitably enlarged to show the construction; and

Fig. 3 is a diagrammatic illustration showing the manner in which the beam produces the colored light.

Referring to the drawing, the tube comprises an evacuated envelope I of glass, or other suitable material, containing at one end a gun G of usual construction and at the other end, the phosphor screens of my invention. The gun G may comprise the usual indirectly heated cathode 2, grid 3, and rst anode 4, the last two of which have suitable apertures for the control and passage of the beam. A second anode 5 also may be used. The cathode would be connected to to a negative terminal of the voltage supply and the grid would be maintained slightly more negative. `The rst anode would be connected to a positive terminal of the supply and the second anode to a positive terminal of considerably higher voltage as is well understood in the art. The beam from the gun may be scanned over the target electrode S by horizontal deflection coil 6 and vertical deflection coil 1 but electrostatic detlection may be used when desired. Either electromagnetic or electrostatic focusing means may be used,.\th latter being indicated in the drawings.

The target S comprises a thin transparent plate 8 of glass. for example, on which is a coating 9 of a translucent phosphor material adapted vto fluoresce with one color, say red. On, or

closely adjacent to, the plate 8 is a plurality of metal strips also constituting part of the target S and arranged in spaced relation somewhat like a Venetian blind. The strips are preferably perpendicular to the direction of line scansion. Alternate strips I0 are soldered or otherwise conductively secured together at the right side. as shown in Fig. 2. and strips Il are similarly joined at the left side. Strips lll are coated with ldirectly to the observer.

aluminum berylliate or zinc cadmium sulphide with silver activator with suitable proportions of cadmium fluoresces red; zinc sulphide with silver activator fiuoresces blue, and zinc cadmium sulphide with copper activator iuoresces yellow and these may be usedv on the screen asdescribed.

Strips I are connected by conductor I4 to a control device I and strips II are connected by conductor I6 to that device. Y

The operation of my improved tubes is as follows:

At the transmitter, alternate frames, or lines, in the pick-up tubes, say the former, are scanned to produce red, blue and yellow colors in regular,

sequence. These may be transmitted' in various ways, say in succession. At the receiver the sigl v nals may be applied to the grid 3 in known ways to intensity modulate the beam in proportion to the amplitude ofthe signals. Since the deflecting saw tooth or other generators are running in synchronism with the deflection ger'ieratorsl of the pick-up tube, device I5 can be connected to the frame scansion generator and made to per-V form in the way given below. l

At the close of the red scansion, conductor I4 will be made positive and conductor I6 negativey so that the beam B is deflected sufficiently to strike the phosphor coating I2 on strips III during this scansion (Fig. 3). The screen therefore will uoresce blue for this scansion and the blue light varying with the strengthl of the signals will be viewed through the thin glass plate 8.

When the blue scansion ends conductors I4 will go negative and conductor I6 positive. This causes the beam B to strike the coating I3 on strips II. Yellow light is thus produced during this scansion. When the yellow scansion ends conductors I4 and I6 will go to the same low potential, say zero, and the beam B will pass between the strips I0 and II and strike the red.

phosphor material 9 on the glass plate 8. During this scansion, red light will be observed. The light of the phosphor 9 in plate 8 is radiated The light from the edges of the phosphore onthe sides of strips I0 and II is also radiated directly to the observer,

l rial.

It will be apparent that a'two color targetmay also be made by connecting all the strips together and alternately directing the beam to the phosphor materials on the strips and the glass plate.

Instead of viewing the image from vthe end of vthe tube, as indicated in Fig. 1, one may view it from thegun side ofthe screen by constructing the tube envelopein a way well known in the art with the gun positioned at an angle to the screen. This has'the advantage oi yiewing'the colors of strips I 0 and II directly Awlthoutthe- 2. In acolor television cathode ray beam tube, a target comprising a foundation having` a phosphor material adapted to produce one color on a.

surface thereof, a plurality of spaced strips positioned edgewise to said foundation surface and closely adjacent thereto, the side surfaces of a rst series of alternate ones of said strips having a phosphor material thereon adapted to produce a second color andthe side surfaces of a second series of alternate ones of said strips having a phosphor material thereon adapted to produce a third color.

3. In a color television cathode ray beam tube,v means for forming and directing an electron beam along a path, a target arranged transversely to saidvbe''m path and comprising a foundawhile the light from the sides of such strips reaches the observer by reflection from adjacentareas. Since the frame scansion frequency is too high to be noted by the eye, the three colors will blend together and produce substantially the true colors of the scene pick-up at the transmitter.

It will thus be apparent that the invention provides a cathode ray tube for color image reproduction. in which the electron beam is controlled atthe target S by electrostatic fields derived from voltages impressed upon the phosphor-coated control vstrips I0 and II and having their maior components transverse to the inci-v dent path of the beam as it approaches the target. Within the regions between adiacent con-- trol elements, the beam is more easily. i. e.hv lower voltages, deflected to, or away from, the

Asurface of a control element than would be the case if the contr-ol elements were hart of the plate 8. Furthermore.'my improved tube does not require accurate or critical registration of the phosphor areas relative to each other. 'That is. the phosphor deposit on the glass plate R may be out down as an over-all 'coating luminescing at one color. and there is no need to register the'nhosnhor areas on strips I0 and II Q with any particular phosphor areas on plate 8.

tion having a phosphor material adapted to produce colored light on a surface thereof, a plu. rality ofspaced strips positioned edgewise to said foundation surface, said spaced stripslhavi'ng'on the side surfaces thereof phosphor material adapted to produce different colored light, vand means for applying potentials `to the strips causing said beam to land selectively on said phosphor material on the surfaces of said strips and on said phosphor material onvsaid foundation.

4. .In a Icolor television cathode ray beam tube, means forl forming and directing an electron beam along a path, a target arrangedtransv versely to said beam path and comprising a foundation 4having a phosphor material adapted to produce one color on a surface -thereof, and a plurality of spaced strips positioned edgewise to said foundation surface and closely adjacent thereto,v the side surfaces ofl a first series of .alternate ones of said strips having a" phosphor material thereon adapted to producev a second colorv and the side surfaces of a second selries of alternate onesof said strips having a phosphor material thereon adaptedto produce'a thi-rd color, and means for varying the potentials applied to said strips to 'cause the` beam toland on the phosphor material on the surfaces of one series of alternate strips during one scansion, on

the phosphor materialon the surface of thev other seriesl of alternate strips during a second scansion, and on the phosphor-material on said foundation during" athird scansion.

5. An electron discharge device comprising, electron gun means for forming an electron beam along a path, and a target electrode positioned transversely to said beam path, said target electrode including a foundation and a plurality of spaced strips mounted edgewise to a surface of said foundation, and a phosphor coating on the side surfaces of said spaced strips.

6. An electron discharge device comprising', an electron gun means for forming an electron beam along a path, a target electrode spaced from said gun means and positioned transversely to said beam path, deecting field means between said gun and said target for scanning said beam over a surface of said target electrode, and a plurality of spaced strips mounted edgewise to said target surface and perpendicular to the direction of line scansion, and a phosphor coating on the side surfaces of said strips.

7. An electron discharge device comprising,

an electron gun means for forming an electron beam along a path, a target electrode spaced from said gun means and positioned transversely to said beam path, deflecting field means between said gun and said target for scanning said beam over a surface of said target electrode, and a plurality of spaced conductive strips mounted edgewise to said phosphor surface, a phosphor coating on said target surface and on the side surfaces of said strips, and means connecting alternate ones of said strips electrically together.

8. A target electrode for an electron discharge device, said electrode comprising a transparent plate and a plurality of spaced strips mounted edgewise to one surface of said transparent plate, a phosphor coating on the side surfaces of said spaced strips.

9. A target electrode for an electron discharge device, said electrode comprising a transparent plate and a plurality of spaced strips mounted edgewise to one surface of said transparent plate, a phosphor coating on the side surfaces of said spaced strips, and a dierent phosphor coating on said transparent plate surface between said spaced strips.

10. A target electrode for an electron discharge device, said electrode comprising a support plate and a plurality of conductive elements having surfaces extending substantially perpendicularly from a face of said support; plate, and a phosphor coating on said element surface.

11. An electron discharge device comprising, an electron gun means. for forming an electron beam along a path, a target electrode positioned transversely to said beam path, said target electrode including a support plate and a plurality of conductive elements having surfaces extending substantialLv perpendicularly from a face of said support plate, and a phosphor coating on said element surfaces.

12. A target electrode for an electron discharge device, said electrode comprising a support plate and a plurality of conductive elements having surfaces extending from a face of said support plate, a phosphor coating on said element surfaces, and a different phosphor coating on said supporting plate face between said conductive elements.

13. An electron discharge device comprising electron gun means for forming an electron beam along a path, and a target electrode'positioned transversely to said ybeam path and including a transparent plate and a plurality of control means adjacent to (said plate for providing an electrostatic eld with a major component ings on side surfaces thereof.

15. A color television cathode ray tube comprising apparatus for producing an electron beam and directing it along a path, a target electrode arranged transversely to said beam path, said target including a transparent plate member and a plurality of spaced strips positioned edgewise to said plate member and closely adjacent thereto, the side surfaces of a first series of alternate ones of said strips having a phosphor material thereon adapted to produce a colored luminescence and the side surfaces of a second series of alternate ones of said strips having a phosphor material thereon adapted to produce luminescence of a different color, a lead connected substantially equi-potentially to the .strips in the first series of strips and another lead connected substantially equi-potentially to the strips in the second series of strips for varying the potential applied to said strips to cause the beam to land on said surfaces of one or the other of the series of alternate strips dependent on the potentials applied to them.

16. An electron discharge device for color image reproduction having an envelope and apparatus for producing a beam of electrons therein and having associated therewith apparatus for controlling and directing the electron beam. a transparent plate arranged transversely -to the path of the electron beam and having on one side a translucent coating of material which,

when hit by the electron beam, fiuoresces in one of the primary colors and opaque deecting plates interposed between the electron beam producing apparatus and the transparent plate, said deflecting plates including conducting material to which voltage capable of deflecting the electron beam can be applied and having coatings of material uorescing in other primary colors applied to them on surfaces which can be hit by the electron beam and can be observed through the transparent plate.

RICHARD L. SNYDER, JR.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS