US2062538A - Cathode ray tube - Google Patents

Cathode ray tube Download PDF

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Publication number
US2062538A
US2062538A US60371A US6037136A US2062538A US 2062538 A US2062538 A US 2062538A US 60371 A US60371 A US 60371A US 6037136 A US6037136 A US 6037136A US 2062538 A US2062538 A US 2062538A
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plates
cathode
pair
cathode ray
ray tube
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Expired - Lifetime
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US60371A
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Francois Joseph Gerard V Bosch
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Francois Joseph Gerard V Bosch
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Priority to GB462735A priority Critical patent/GB444775A/en
Application filed by Francois Joseph Gerard V Bosch filed Critical Francois Joseph Gerard V Bosch
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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
    • H01J29/70Arrangements for deflecting ray or beam
    • H01J29/72Arrangements for deflecting ray or beam along one straight line or along two perpendicular straight lines
    • H01J29/74Deflecting by electric fields only

Description

Dec. 1, 1936. F. J. G. VAN DEN BOSCH 2,062,538

CATHODE RAY TUBE Filed Jan. 23, 1936 INVENTOR HTTORNEY.

Patented Dec. 1, 1 936 UNITED STATES CATHODE BAY TUBE Francois Joseph Gerard Van den Bosch, London,

Application January 23, 1936, Serial No. 60,371 In Great Britain February 13, 1935 4Claims.

A known form of cathode ray tube comprises a glass envelope in the form of a cylinder flaring out into a frusto-conical bulb, the inner face of the end wall of the bulb being coated with a substance, such as willemite or calcium tungstate, which becomes fluorescent under bombardment by the cathode ray. Within the envelope are arranged, in the order mentioned, a hot emitting cathode surrounded by an open-ended metal cylinder, one or more anodes each in the form of a centrally apertured disc,- a pair of horizontal and a pair of vertical deflecting plates.

Focussing of the ray on the fluorescent screen is achieved by suitably adjusting the relative positions and potentials of these electrodes, and hitherto great difliculty has been experienced in reducing the size of the fluorescent spot on the screen to that required for such purposes as'high definition television.

It is an object of the present invention to provide means whereby the cathode ray may be more accurately and finely focussed upon the screen, giving at the same time an increased light intensity.

With this end in view, and in accordance with the invention, the plates of each of the horizontal and vertical deflecting pairs of plates are coated on their adjacent faces with a substance such as an alkali metal oxide or iodide for example, strontium-oxide, barium-oxide, lime, iodide of calcium, calcium fluoride or caesium, which are known to emit electrons easily when i even slightly heated. Preferably the plates of each of said pairs are parallel over a minor portion of their axial length nearer the cathode and diverge outwardly from the cathode over a major portion farther from the cathode.

By axis of the tube" is meant a line coincident with the centre-line of the beam of rays passing through the tube.

- A preferred form of the invention will now be described with reference to the accompanying drawing, which is a perspective view of the electrodes of a cathode ray tube constructed in accordance with the invention.

A cathode ray tube comprises a cathode l, a Wehnelt cylinder 2 surrounding the cathode, a flrst anode 3 in the form of a centrally apertured disc, a second and similar anode 4, a pair of. vertical" deflecting plates 5 and 6 and a pair of horizontal deflecting plates 1 and 8. The two pairs of plates 5, 6 and I, 8 are termed vertical" and horizontal deflecting plates respectively, since they operate to deflect the ray in the vertical and horizontal planes respectively.

The vertical plate I is earthed and the vertical deflecting potentials are applied between the plates 8 and I. The horizontal plate 5 is maintained at 200 volts negative with respect to plate 1, and the horizontal deflecting potentials are applied between the plates 5 and 6. The second anode 4, the first anode 3, the Wehnelt cylinder 2 and the cathode I are maintained respectively at the following negative potentials with respect to the plate I: 600 volts, 1200 volts, 1435 volts and 1400 volts.

Adjacent faces of the plates 1, 8, and 5, 8, are coated with a substance, such as potassium or strontium oxide or caesium which emits electrons freely when a current is passed through the tube and these plates are slightly heated. Preferably a current of 5 to 20 milli-amperes is passed to these plates which then become slightly heated. Each pair may consist of parallel rectangular plates or, as shown, each plate such as 5 may be formed from a rectangular plate bent along a line 9 which is perpendicular to the tube axis Ill. The distance II, I2 is about A; of the axial length of the plate 5. The plates of each pair are bent outwardly and disposed symmetrically about the axis Hi.

It is found that by coating the plates as described, a sharply focussed and very small fluorescent spot can be produced on the screen, the focussing efi'ect being increased by inclining the plates as shown in the drawing.

The same eifect is obtained with soft tubes containing a rare gas such as argon, neon, helium or a gas of low molecular weight such as hydrogen.

The relative potentials of the various electrodes may be varied considerably from those quoted above.

The adjacent faces of the plates of each pair I, 8 and 5, 6 may be coated either all over or, as shown, only upon thedivergent portions.

I claim:-

1. A cathode ray tube comprising a cathode, an anode, a pair of vertical deflecting plates and a pair of horizontal deflecting plates, the plates of each of said pairs being coated, on their adjacent sides, with an electron emitting substance.

2. A cathode ray tube comprising a cathode, an anode, a pair of vertical deflecting plates and a pair of horizontal deflecting plates, the plates of each of said pairs being coated, on their adjac'ent sides, with an electron emitting substance selected from strontium oxide, barium oxide, lime, calcium iodide, calcium fluoride and caesium.

3. A cathode ray tube comprising a cathode, an anode, a pair or vertical deflecting plates and a pair of horizontal deflecting plates, the plates of each pair being parallel over a minor portion of their axial length nearer the cathode, diverging outwardly from the cathode 'over the remaining major portion further from the cathode and being coated on their adjacent taces with an electron emitting substance.

4. A cathode ray tube comprising a cathode. an anode, a pair of vertical deflecting plates and a pair oi horizontal deflecting plates, the plates 01' each pair being parallel over a minor portion 4 01' their axial length nearer the cathode diverging outwardly from the cathode over the remaining major portion further from the cathode and being coated on the outwardly divergent pottions or theiradjacent faces with an electron emitting substance.

FRANQOiS JQ SEPH GERARD VAN pm 30868.

US60371A 1935-02-13 1936-01-23 Cathode ray tube Expired - Lifetime US2062538A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB462735A GB444775A (en) 1935-02-13 1935-02-13 Improvements in and relating to cathode ray tubes

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US2062538A true US2062538A (en) 1936-12-01

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US60371A Expired - Lifetime US2062538A (en) 1935-02-13 1936-01-23 Cathode ray tube

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US (1) US2062538A (en)
BE (1) BE412691A (en)
FR (1) FR798992A (en)
GB (1) GB444775A (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2455992A (en) * 1947-01-25 1948-12-14 Du Mont Allen B Lab Inc Cathode-ray tube amusement device
US2530275A (en) * 1946-03-16 1950-11-14 Weingarten Joseph Cathode-ray tube image control
US2709229A (en) * 1950-06-01 1955-05-24 Rca Corp Radioactive monokinetic charged particle generators
US2922069A (en) * 1958-07-15 1960-01-19 Bell Telephone Labor Inc High speed counting and switching tubes

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2530275A (en) * 1946-03-16 1950-11-14 Weingarten Joseph Cathode-ray tube image control
US2455992A (en) * 1947-01-25 1948-12-14 Du Mont Allen B Lab Inc Cathode-ray tube amusement device
US2709229A (en) * 1950-06-01 1955-05-24 Rca Corp Radioactive monokinetic charged particle generators
US2922069A (en) * 1958-07-15 1960-01-19 Bell Telephone Labor Inc High speed counting and switching tubes

Also Published As

Publication number Publication date
FR798992A (en) 1936-05-29
GB444775A (en) 1936-03-27
BE412691A (en)

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