US2759995A

US2759995A - Tricolor television picture tube

Info

Publication number: US2759995A
Application number: US269457A
Authority: US
Inventors: Miller Theadore
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1952-02-01
Filing date: 1952-02-01
Publication date: 1956-08-21
Anticipated expiration: 1973-08-21

Description

1956 v T. MILLER TRICOLOR TELEVISION PICTURE TUBE Filed Feb. 1, 1952 Bios Control Potential Applied in Synchronism With Color Signals INVENTOR Theodore Miller.

WITNESSES: wtw Y ATTORNEY United States Patent TRICOLOR TELEVISION PICTURE TUBE Application February 1, 1952, Serial No. 269,457 9 Claims. (Cl. 17s-5.4

My invention relates to cathode ray tubes, and more particularly to a tube for reproducing color television pictures.

In my copending application, Serial No. 243,487, filed August 24, 1951, there is disclosed a method of quenching the luminescence of phosphor materials by subjecting the phosphors to a high frequency electric field.

In accordance with the prior art of which I am aware, a large number of ideas have been expressed for systems for the production of color television pictures. While many of these have some advantages, nevertheless, it isbelieved that most of the proposed systems have certain undesirable characteristics which can not be readily overcome.

It is accordingly an object of my invention to pro- ,vide an improved cathode ray tube.

Another object of my invention is to provide an im' proved color television tube.

Still another object of my invention is to provide a color television tube which controls the colors produced by employing the principle of quenching phosphors with high frequency electric fields.

The novel features which I consider characteristic of my invention are set forth with more particularity in the appended claims. The invention, however, with respect to both the organization and the operation thereof, together with other objects and advantages may be best understood from the following description of specific embodiments when read in connection with the accompanying drawing, in which:

The sole figure is a schematic showing of an apparatus embodying my invention.

In accordance with my invention, I provide an envelope 2 of glass which is substantially larger in diameter at one end than it is at the other end. In the small end of the envelope there is provided an electron gun 4 for producing a beam of electrons, in a ma r well known in the art. In the large end of the glass envelope 2 there is provided a screen 6 oriented so that electrons from the electron gun 4 will impinge upon the screen 6. Deflection coils 8 are provided about the envelope 2 near its center for deflecting the electron beam so as to produce scanning of the screen 6. Between the deflection coils 8 and the screen 6 an anode electrode 10 is provided for accelerating electrons discharged by the gun 4. The screen 6 comprises a layer of transparent conducting material 12 which may be of relatively large thickness so as to support the other elements of the screen. A plurality of red, green and

blue phosphor strips

14, 16, 18 are placed on the transparent conducting layer 12 between that layer and the electron gun 4. The few such strips shown in the drawing are, of course, merely indicative of the orientation of the much larger number of strips which would actually be employed in practice. The

phosphor strips

14, 16, 18 are arranged in rotation so that any color strip; e. g., one of the red strips 14, lies between two strips of different colors; e. g., a green strip 18 on one side and a blue strip 16 on the other. The

phosphor strips

14, 16, 18 are preferably separated by small distances from each other. Opposite each of the

phosphor strips

14, 16, 18 and extending parallel thereto there is a strip of

electrical conductors

20, 22, 24 such as a very thin coating of aluminum. The

aluminum strips

20,22, 24 adjacent the

phosphor strips

14, 16, 18, lie between the phosphor strips and the electron gun 4. It is, therefore, desirable that the

aluminum strips

20, 22, 24 be very thin.

Connections are supplied for providing a first set of electrical oscillations to the aluminum strips 20 adjacent the red phosphor strips, 9. second set of electrical oscillations to the aluminum strips 22 adjacent the blue phosphor strips 16 and a third set of electrical oscillations to the aluminum strips 24 adjacent the green phosphor strips 18. The aforesaid oscillations are preferably in the radio frequency range. For example, in the order of 10 mega cycles. The electrical oscillations to be applied to the

aluminum strips

20, 22, 24 are supplied by a radio frequency oscillator 26 to the grid of three vacuum tubes. The first vacuum tube 28 has its plate 30 connected to the aluminum strips 20 adjacent 'the red phosphors 14, the second vacuum tube 32 has its plate 34 connected to the aluminum strips 22 adjacent the blue phosphors 16 and the third vacuum tube 36 has its anode 38 connected to the aluminum strips 24 back of the green phosphor strips 18. A bias control potential is applied in synchronism with the received color signals to the grids of the three vacuum tubes. These bias control potentials are applied so that when the information being reproduced by the electron gun 4 relates to the red picture, the first vacuum tube 28 is non-conducting and the second and third vacuum tubes 32, 36 are conducting. Thus, when the screen 6 is being scanned with a beam of electrons having red information impressed thereon, a high fre quency field is applied to the

aluminum strips

22, 24 which lie adjacent the blue and green phosphor strips. These high frequency oscillations when applied to the aluminum strips 21), 22, 24 produce a field between the aluminum strips and the transparent conducting layer 12 on the opposite side of the

phosphor strips

14, 16, 18. Therefore, when the high frequency electrical oscillations are applied to the aluminum strip 22 adjacent the blue phosphor strip 16, a high frequency field is produced across the blue phosphor strip 16 which quenches the ability of the phosphor strip 16 to luminesce.

in the operation of the apparatus shown in the drawing, the electron beam has impressed thereon, red information. At this time, r-adio frequency fields are being applied across the blue and

green phosphors

16, 18. Therefore, electrons produced by the electron gun 4 and impinging on the blue and

green phosphors

16, 18, will have substantially no effect because of the quenching effect of the radio frequency fields. On the other hand, no radio frequency fields are applied across the red phosphor 14. Therefore, when the electrons strike the red phosphor strips 14, red light will be emitted by those phosphor strips, in response to the electrons impinging thereon. Thus, when the electron beam is scamiing the screen 6 with red information, only red light can be emitted by the screen.

lthough I have shown and described specific embodiments of my invention, I am aware that other modifications thereof are possible. My invention, therefore, is not to be restricted except insofar as is necessitated by the prior art and the spirit of the invention.

I claim as my invention:

1. In combination, a television tube comprising an envelope of dielectric material, means for producing a beam of electrons near one end of said envelope inside said Patented Aug. 21, 1956 amiable; slayer of transparent conducting material near the other end of said envelope inside-said envelope;-a plurality of fine strips of phosphor material capable of emitting'light of a first frequency located near said transparent """d ucting' :rnate'rial and extendingparallel "to "the surface thereof, a plurality 'of 'phosphors t'rips capable of' produc ingli'glit or a secon ffrequeac said see-aha phosp or strips being'in trposedbetviveen said first phosphor strips, a strip of conducting material near each f said phosphor strips "on the opposite side of said hosphor ships from said transparent conducting 'materia means for applying a' first potential t" said transparent conducting coating, and means for supplying a first -radio frequency potential to the conducting strips in back of said phosphor of a first mat 'rial, and means {or sn 'pl'ying a "second retire fi efiency potential to said emanating strips located in back of fsaia second phosphor 's tiip s.

' 2. Apparatus ntially as described in claim 1, charseemed 'in that means are prov1ded for'varying the radio tre'q'riency power applied to "said conducting strips in aceb rdance with a "signal.

*3. A television tube comprising a plurality of first phosphor "strips capable of emitting light of a first frequency, a plurality of second phosphor strips interspersed among sa'id first strips capable of emitting light of the second frequency, means for impressing a 'fir'st radio frequency field across said first phosphor strips, means for impressing a second radio frequency field across said second phosphor strips independently of the potential applied some said first phosphor strips, and means for causing high velocity'el'ectrons to impinge on said phosphor strips.

'4. Apparatus substantially as described in claim 3 characterize d in that said means 'for i'rfipressinga first field and said means for impressing a second field aie variable injacco'rd'a'nce with a signal.

5. "A color television tube comprising a plurality of phosphor strips, some ofs'aid phosphor strips being capable of producing light of a first color and other of "Said phosphor strips being capable of producing light of a second color, means for applying a radio frequency field across said phosphor strips of 'afirst color during a first time interval and means for applying a radiofrequency field across said phosphor strips of a second color during a second time interval.

'6. A color television tube comprising means for prodnc ing an electron beam, an image screen, said image screen comprising a"transparentconductive layer'of material, a phosphor layer comprising a plurality of'indiv'idual strips deposited on said conductive layer and each of said phosphor strips having an individual electron permeable conductive coating thereon, said transparent conductive layer and said individual coatings being adapted for applying aradio-frequency field thereto to control the luminesoence of said phosphor strips associated with said selected individual conductive layers.

7. A color television tube comprising an image screen, said image screen having a plurality of groups of phosphor coated elemental areas on a conductive surface, said elemental areas comprising a phosphor material capable of emittinglight of a color individual to that area and insulated electron transparent conductive coatings in each of said "elemental phosphor areas, said conductive surface and said insulated coiiducti've coating being adapted for supplying a radio-frequency field thereto to quench the luminescenceof said elemental areas of phosphor material associated with said selected eo'iian'cave earnings.

8. A color television'tube'compri'sih'g an image screen having a plurality of groups of elemental areas of phosphor material, each elemental area of phosphor material within a group being limited in its light representation to one selected component Color, means foiscanning a lumih'e'sc'ent image 'on -said 's'dre'eh, and means for'd'ecre'a'si'ng the luminescence of selected elemental areas of phosphor by impressing a radio frequency field across 'tho'seselected elemental areas of phosphor. I

9. A color' televi'sion tube comprising an image "screen having' a phfifality 'of "groups of substantially parallel phosphor 'sti'ips deposited span a conductive surface, each strip of said groups being limited in its light representa- 'tion to one selected component color, individual insulated coh'diietive pos ings deposited on the exposed surface of said parallel 'strip's '61" phosphor material, 'ineans "connecting together all these individual conductive coatings on said phosphor strips of similar color light representation, an electronicscanr'liiig means for developing an image on said screen by a'scanniiigope'r'ation, and means for modulating s'aid "s'eaiinin g iifeaiis -with s'ig'nal representative of one color while simultaneously irr'ipr'e'ss'in'g a "radiofrequency field'acfos's "said phosphor "strips other than said phosphor st'ripsre'pies'entativ'e oft he color signal impressed on said se'aiinin inea'ns 'to uench the luminescence therefrom.

Referenees'i fited'in the file of this patent UNITED STATES PATENTS