US2484721A - Electrode gun such as is used in cathode-ray tubes - Google Patents

Electrode gun such as is used in cathode-ray tubes Download PDF

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Publication number
US2484721A
US2484721A US4366A US436648A US2484721A US 2484721 A US2484721 A US 2484721A US 4366 A US4366 A US 4366A US 436648 A US436648 A US 436648A US 2484721 A US2484721 A US 2484721A
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anode
electrode
cathode
apertured
aperture
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US4366A
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Moss Hilary
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A C COSSOR Ltd
COSSOR Ltd AC
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COSSOR Ltd AC
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    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01JELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/46Arrangements of electrodes and associated parts for generating or controlling the ray or beam, e.g. electron-optical arrangement
    • H01J29/48Electron guns
    • H01J29/488Schematic arrangements of the electrodes for beam forming; Place and form of the elecrodes
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01JELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/46Arrangements of electrodes and associated parts for generating or controlling the ray or beam, e.g. electron-optical arrangement
    • H01J29/58Arrangements for focusing or reflecting ray or beam
    • H01J29/62Electrostatic lenses
    • H01J29/622Electrostatic lenses producing fields exhibiting symmetry of revolution
    • H01J29/624Electrostatic lenses producing fields exhibiting symmetry of revolution co-operating with or closely associated to an electron gun

Description

H. Mos's 2,484,721

ELECTRODE GUN SUCH AS IS USED IN CATHODE-RAY TUBES Oct. 11, 1949.

Filed Jan. 26, 1948 all] ll W:

5 R 1 0 B MM m m NT 1E m Patented Oct. 11, 1949 ELECTRODE GUN SUCH AS IS USED IN CATHODE-RAY TUBES Hilary Moss, London,

Cossor Limited, Lo company Application January 2.6, 1948, Serial No.

England, assignor to A. C.

ndon, England, a British In Great Britain March 14, 1942 Section 1, Public Law 690, August 8, 1946 Patent expires March 14, 1962 8 Claims.

This invention relates to electron guns such as are used in cathode ray tubes for the purpose (if-generating electron beams, and of focussing them at least mainly by electrostatic fields.

One of the objects of the invention is to produce an exceptionally fine crossover in the electron beam.

In an electron gun according to the invention, the first anode and the control electrode, which serve with the cathode to establish the first electron lens, each consist of an apertured disc electrode having a cup portion surrounding the aperture, formed by dishing and disposed convex towards the cathode, and said anode and control electrode are so arranged that the aperture of the anode issituated within th cup portion 01' the control electrode.

An object of a preferred form of the invention is to focus the electron beam into a fine spot on a target such as a fluorescent screen. This may be effected by employing a single or unipotential lens to produce on the target an image of the crossover. Preferably the potential of the first and last electrodes of this lens is equal to that of the first anode and thereby the introduction of a third lens between the first lens and the unipotential lens is avoided. A direct connection may be made between said electrodes and the first anode, either inside the tube or in an external circuit.

The appended drawing shows in Fig. 1 a crosssectional view of an electron gun structure in a cathode ray tube embodying principles of the present invention, while Fig. 2 shows diagrammatically acathode ray tube embodying a modified form of the invention.

Cathode I is of a conventional type having a flat active surface disposed perpendicular to the axis of the gun. Control electrode 2 comprises a cup portion 2| convex towards the oathode I. This cup is formed by dishing. In the middle of the bottom of the cup is an aperture 22.

The first anode 3 has a cup portion 3| convex towards the cathode, also formed by dishing. In the middle of the bottom of this cup is an aperture 32. This aperture 32 lies within the cup portion 2| of control electrode 2.

In a specific example of a gun according to the invention, which has been found to operate satisfactorily, the cups 2| and 3| of the electrodes 2 and 3 are both of part-spherical form and have equal radii of 3.17 mm. The diameter of the aperture 22 in the control electrode is 0.8 mm. and that *of the aperture 3 in the first 2 anode is 1.8 mm. The depth of the cup in the control electrode is 2.07 mm. and that of the cup in the first anode is 1.87 mm.

The spacing between the aperture of the control electrode and the cathode surface is 0.3 mm. The spacing between aperture of the first anode and that of the control electrode is 1.50 mm.

The crossover is formed within the cup of the control electrode and near the aperture of the first anode.

The beam diverges from the crossover as it passes into a tubular second anode 4. A single lens is formed by the electrostatic field between second anode 4, final anode 5 and the decelerating electrode 6; anodes 4 and 5 being maintained at equal potential, the highest potential in the gun and preferably equal to that of the first anode 3, while electrode 6 is maintained at a lower potential. The arrangement of potentials is indicated generally in Fig. 2 by the sign and number of the polarity marks adjacent the Various leads.

The electron beam leaves the electron gun through aperture 58 of final anode 5 and the beam is now in a form convergent towards a fine spot.

It has been found convenient and efiective to work this tube with the following electrode voltages relative to cathode:

Control electrode 2 2 to volts negative First'anode 3 Second anode 4 Final anode 5 Decelerating electrode 6--- 270 volts positive 2,000 volts positive 42 of diameter 1.8 mm. The divergent beam is masked down by this additional electrode so that electrons do not impinge on the decelerating electrode 6. Undesirable secondary emission from electrode 6 is thus avoided.

In Fig. 2 I have indicated the electron gun structure as being mounted within neck portion of cathode ray tube envelope 6| I claim:

1. A cathode ray tube having an electron gun arrangement including a cathode for generating a stream of electrons and electrostatic means for focussing said stream, said electrostatic in including an apertured disc control else having a cup portion surrounding the aperture thereof and disposed with its convex side adjacent said cathode, and

an apertured disc I anode having a cup portion surrounding the aperture therein and disposed with its convex por= I tion within the cup portion of said control electrode, and means forming .a'i unipotentiail lens for converging said stream to aifiri'e' spot including succession a tubular second anode, an apertured decelerating electrode and an apertured. final anode, said decelerating electrode and final anode being cup-shaped and having their cupped sides adjacent one another.

2. A cathode ray tube having an electron gun.

arrangement including a cathode for generating a stream of electrons and electrostatic means for 4 shaped and having their cupped sides adjacent one another, the first and last electrodes of said lens being connected to said first anode;

5; cathode fay tube Having an electron gun arrangement including a cathode for generating a stream of electrons and electrostatic means for 'focussing said stream, said electrostatic means including anapertured disc control electrode having. a cupportion surrounding the aperture thereof and disposed with its convex side adjacent said cathode, and an apertured disc first anode having a; cupportion" surrounding the aperture therein and disposed with its convex portion within the cup portion. of said control electrode, and

means forming a unipotential lens for converging said stream to a fine spot including in successiona' tubular second anode, an apertured decelera-ting' electrode and an apertured final anode,

ces'sion a tubular second anode, an apertured decelerating electrode and an apertured final anode, said decelerating electrode and final anode being c'up s'h'a'ped and having their cupped sides adja' cent one another, the first and last electrodes of said lens having a potential applied thereto equal to that or said first anode.

3. A cathode ray tube having an electron gun arrangement including a cathode for generating a stream or electrons and electrostatic means for fdcuss'irigsaid stream, said electrostatic means including an apertured disc control electrode having a cup portion surrounding the aperture thereof and disposed with its convex side adjacent said cathode, and an apertured disc first anode having a cup portion surrounding the aperture therein and disposed with its convex portion within the cup portion of said control electrode, and means forming a unipotential lens for converging said stream to a fine spot including in succession a tubular second anode, an apertured decelerating electrode and an apertured finial anode, said decelerating electrode and final anode being cup' shaped and having their cupped sides adjacent one another, the first and last electrodes of said lens liaving a potential applied thereto equal to that of said first anode, the intermediate electrode of saidl en's having alower potential applied thereto;

4. A cathode ray tube having an electron gun arrangement including a cathode for generating a stream of electrons and electrostatic means for focus'sing said stream, said electrostatic means including an apertured 'disc contra] electrode having a cup portion surrounding the aperture there:-

cathode, and an apertured disc first anode having a cup pdrtioh surrounding the aperture therein and disposed with its convex portion within the cup portion of said control. electrode, and means forming a unipotentiallens for converging said stream to a fine spot including in succession a tubular second anode, an apertured decelerating electrode and an apertured final anode, said decelerating electrode and final anode being cupor and disposed with its convex side adjacent said said decelerating electrode and final anode being cup-shaped and having, their cupped sides adjacent one another, the first and last electrodes of said lens being connected to said first anode, the intermediate electrode of said lens being connected to a source of potential lower than that of said first anode.

6. A cathode ray tube having an electron gun arrangement including a cathode for generating a stream of electrons and electrostatic means for focussi'ng said stream, said -electrostatic means including an apertured disc control electrode having a cup portion surrounding the aperture' thereof and disposed with its convex side adjacent said cathode, and an ,apertured disc first anode having a cup portion surrounding the aperture therein and disposed with, its convex portion within the cup portion of said control electrode, and means forming a unipoten tial lens for converging said stream to a fine spot including in succession a tubular second anode, an apertured decelerating electrode and an apertured final anode, said decelerating elec trode and final anode being cup-shaped andhaving their cupped sides adjacent one another, and means for preventing said stream from impinging on the intermediate electrode of said lens.

7. A cathode ray tube having an electron gun arrangement including a cathode for generating a stream of electrons and electrostatic means for focussing said stream, said electrostatic means including an apertured disc control electrode having a cup portion surrounding the aperture thereof and disposed with its convex side adjacent said cathode, and an apertured disc first anode having a cup portion surrounding the aperture therein and disposed with its convex portion within the cup portion of said control electrode, and means forming a unipotential lens for converging said stream to. a fine spot including in succession a tubular second anode, an apertured decelerating electrode andv an apertured final anode, said decelerating electrode and final anode being cup-shaped and having their cupped sides adjacent one another, and means for preventing said stream from impinging on the intermediate electrode of said lens, includingan apertured disc electrode following said first anode and connected to said tubular anode. I

8. A cathode ray tube having an e1ectrcn=gun arrangement including a cathode for generat ing a stream of electrons and electrostatic means for focussing said stream, said electrostatic means including an apertured disc controlelectrode having a cup portion surrounding tlie 5 aperture thereof and disposed with its convex side adjacent said cathode, and an apertured disc first anode having a cup portion surrounding the aperture therein and disposed with its convex portion within the cup portion of said control electrode, and means forming a unipotential lens for converging said stream to a fine spot including in succession a tubular second anode, an apertured decelerating electrode and an apertured final anode, said decelerating electrode and final anode being cup-shaped and having their cupped sides adjacent one another, and means for preventing said stream from impinging on the intermediate electrode of said lens, including an apertured disc electrode following said first anode and having a potential applied thereto equal to that of said tubular anode.

HILARY MOSS.

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

US4366A 1942-03-14 1948-01-26 Electrode gun such as is used in cathode-ray tubes Expired - Lifetime US2484721A (en)

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Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2540537A (en) * 1948-12-18 1951-02-06 Rca Corp Vacuum tube current amplifier
US2540621A (en) * 1948-02-19 1951-02-06 Rca Corp Electron gun structure
US2575835A (en) * 1950-05-09 1951-11-20 Du Mont Allen B Lab Inc Cathode-ray tube centering device
US2583500A (en) * 1948-11-25 1952-01-22 Cathodeon Ltd Cathode-ray tube
US2633553A (en) * 1948-11-26 1953-03-31 Siemens Ag Cathode-ray oscillograph
US2673305A (en) * 1951-05-31 1954-03-23 Rauland Corp Image-reproducing device
US2719243A (en) * 1951-07-03 1955-09-27 Du Mont Allen B Lab Inc Electrostatic electron lens
US2773212A (en) * 1953-08-14 1956-12-04 Westinghouse Electric Corp Electron gun
US2792515A (en) * 1951-06-22 1957-05-14 Thomas Electrics Inc Cathode ray tube
US2825837A (en) * 1954-03-02 1958-03-04 Hazeltine Research Inc Electrostatic focusing system
US2839703A (en) * 1956-01-03 1958-06-17 Columbia Broadcasting Syst Inc High resolution image cathode ray tube system
US2935636A (en) * 1955-10-31 1960-05-03 Rca Corp Electron gun structure
US2939980A (en) * 1956-01-30 1960-06-07 Sylvania Electric Prod Image reproduction device structure
US3394279A (en) * 1967-03-23 1968-07-23 Kentucky Electronics Inc Support and electrical connection for grid cup in electron gun
US3628077A (en) * 1970-02-26 1971-12-14 Sylvania Electric Prod Electron gun having concave coined grid and annular rib
FR2535522A1 (en) * 1982-10-29 1984-05-04 Philips Nv Cathode ray tube
US20030006689A1 (en) * 2001-07-06 2003-01-09 Matsushita Electric Industrial Co., Ltd. Electron gun,cathode ray tube using the same, and method of manufacturing electron gun

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL66519C (en) * 1944-12-28
DE1073638B (en) * 1953-02-19

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2111231A (en) * 1934-06-27 1938-03-15 Radio Patents Corp Recording device
US2223040A (en) * 1937-06-30 1940-11-26 Gen Electric Electron discharge device
US2227034A (en) * 1937-08-30 1940-12-31 Loewe Radio Inc Cathode ray tube
US2268196A (en) * 1939-12-02 1941-12-30 Bell Telephone Labor Inc Electron discharge device
US2310811A (en) * 1940-03-29 1943-02-09 Schantl Erich Cathode-ray tube
US2355795A (en) * 1942-08-17 1944-08-15 Bell Telephone Labor Inc Electrode system

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2111231A (en) * 1934-06-27 1938-03-15 Radio Patents Corp Recording device
US2223040A (en) * 1937-06-30 1940-11-26 Gen Electric Electron discharge device
US2227034A (en) * 1937-08-30 1940-12-31 Loewe Radio Inc Cathode ray tube
US2268196A (en) * 1939-12-02 1941-12-30 Bell Telephone Labor Inc Electron discharge device
US2268197A (en) * 1939-12-02 1941-12-30 Bell Telephone Labor Inc Electron discharge device
US2268195A (en) * 1939-12-02 1941-12-30 Bell Telephone Labor Inc Electron discharge device
US2310811A (en) * 1940-03-29 1943-02-09 Schantl Erich Cathode-ray tube
US2355795A (en) * 1942-08-17 1944-08-15 Bell Telephone Labor Inc Electrode system

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2540621A (en) * 1948-02-19 1951-02-06 Rca Corp Electron gun structure
US2583500A (en) * 1948-11-25 1952-01-22 Cathodeon Ltd Cathode-ray tube
US2633553A (en) * 1948-11-26 1953-03-31 Siemens Ag Cathode-ray oscillograph
US2540537A (en) * 1948-12-18 1951-02-06 Rca Corp Vacuum tube current amplifier
US2575835A (en) * 1950-05-09 1951-11-20 Du Mont Allen B Lab Inc Cathode-ray tube centering device
US2673305A (en) * 1951-05-31 1954-03-23 Rauland Corp Image-reproducing device
US2792515A (en) * 1951-06-22 1957-05-14 Thomas Electrics Inc Cathode ray tube
US2719243A (en) * 1951-07-03 1955-09-27 Du Mont Allen B Lab Inc Electrostatic electron lens
US2773212A (en) * 1953-08-14 1956-12-04 Westinghouse Electric Corp Electron gun
US2825837A (en) * 1954-03-02 1958-03-04 Hazeltine Research Inc Electrostatic focusing system
US2935636A (en) * 1955-10-31 1960-05-03 Rca Corp Electron gun structure
US2839703A (en) * 1956-01-03 1958-06-17 Columbia Broadcasting Syst Inc High resolution image cathode ray tube system
US2939980A (en) * 1956-01-30 1960-06-07 Sylvania Electric Prod Image reproduction device structure
US3394279A (en) * 1967-03-23 1968-07-23 Kentucky Electronics Inc Support and electrical connection for grid cup in electron gun
US3628077A (en) * 1970-02-26 1971-12-14 Sylvania Electric Prod Electron gun having concave coined grid and annular rib
FR2535522A1 (en) * 1982-10-29 1984-05-04 Philips Nv Cathode ray tube
US20030006689A1 (en) * 2001-07-06 2003-01-09 Matsushita Electric Industrial Co., Ltd. Electron gun,cathode ray tube using the same, and method of manufacturing electron gun

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BE480334A (en)

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