US2153223A - Cathode ray tube - Google Patents

Cathode ray tube Download PDF

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Publication number
US2153223A
US2153223A US37462A US3746235A US2153223A US 2153223 A US2153223 A US 2153223A US 37462 A US37462 A US 37462A US 3746235 A US3746235 A US 3746235A US 2153223 A US2153223 A US 2153223A
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US
United States
Prior art keywords
cathode
insulator
cathode ray
ray tube
electrode
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US37462A
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English (en)
Inventor
Young Arthur James
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
RCA Corp
Original Assignee
RCA Corp
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Filing date
Publication date
Application filed by RCA Corp filed Critical RCA Corp
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Publication of US2153223A publication Critical patent/US2153223A/en
Anticipated expiration legal-status Critical
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/46—Arrangements of electrodes and associated parts for generating or controlling the ray or beam, e.g. electron-optical arrangement
    • H01J29/48—Electron guns
    • H01J29/488—Schematic arrangements of the electrodes for beam forming; Place and form of the elecrodes

Definitions

  • This invention relates to cathode ray tubes suitable for use for television and similar oscilloraph purposes and wherein the cathode ray beam is required to be brought to a sharply focussed spot which is as small as possible.
  • the invention has for its general object to provide an improved iocussing electrode arrangement.
  • electrostatic means comprises a Wehnelt cylinder which surrounds the cathode and has at or near its outer end, i. e. the end farthest away from the cathode in the direction of the cathode ray stream, an apertured anode electrode.
  • a common arrangement is one wherein the apertured anode is a dished disc arranged at the outer end of the cylinder and at right angles to the axis thereof, the cylinder being concentric with and surrounding the cathode.
  • cathode ray tube arrangements comprising only a Wehnelt cylinder and an apertured anode is that the gas pressure in the tube must be made objectionably high if satisfactory focussing is to be obtained.
  • the object of the present invention is to provide an improved focussing arrangement wherein the above difliculties and disadvantages are all avoided and wherein a reasonably low gas pressure may be used in conjunction with a Wehnelt cylinder which may be either negatively or positively biased in relation to the cathode or be at cathode potential.
  • a Wehnelt cylinder can be dispensed with altogether and satisfactory focussing can be obtained with the aid merely of disc-like electrodes.
  • the invention has been found to be applicable not only to gas filled tubes but also to so-called hard cathode ray tubes.
  • the cathode of a cathode ray tube is held accurately in its desired position by means of a centering insulator or insulators and between this insulator or insulators and the efiective point of emergence of electrons is arranged a disc-like electrode which operates as a focussing device.
  • the disc-like electrode is in contact with the centering insulator and is at cathode potential.
  • Fig. 1 shows an electron gun embodying my invention
  • Fig. 2 shows a modification of the electrode structure
  • Fig. 3 shows a further modification
  • FIG. 4 shows yet a further modification of my invention.
  • a cathode ray tube (not shown as a whole) has a cathode I which projects through a central aperture 2 in a mica, steatite, or other centering insulator 3 of disclike form and which is mounted upon rods 4 of the usual supporting frame of the electron gun" assembly of the tube.
  • the cathode also projects through a central aperture in a shield or focussing disc 6 which lies against and in contact with the insulator disc 3 and is on the side thereof adjacent the tip of the cathode.
  • This shield or focussing disc may be either positively or negatively biased but is preferably directly connected inside the tube to the cathode as shown.
  • the shield or focussing disc is of somewhat smaller diameter than the internal diameter of a Wehnelt cylinder 1 which is arranged concentrically about the cathode, one end of the Wehnelt cylinder lying approximately in the same plane as the shield or focussing disc 6.
  • This Wehnelt cylinder is carried by supporting rods (not shown) as in the usual way, and its outer end projects into a dished-disc-like apertured anode 8 also as in the usual way.
  • a fluorescent screen (not shown) is provided at the far end of the tube envelope.
  • the Wehnelt cylinder may be either negatively or positively biased according to the particular spacing of the electrodes employed and the aforesaid distance a may be made as much as three-quarters of the internal diameter of the Wehnelt cylinder and satisfactory 4 iocussing may still be obtained with these dimensions even with a negatively biased cylinder.
  • the focussing disc or shield substantially assists focussing action and enables a quite small gas filling to be used with satisfactory results. Furthermore with the system shown a large cathode ray mean current may be obtained.
  • the embodiment of Figure 1 is modified by dispensing with the Wehnelt cylinder 1 and the single apertured disc anode 8 and employing instead two or more disc or similar anodes 23 and 25 in conjunction with a suitable control electrode 23, said anodes being, of course, arranged at right angles to the mean direction of the cathode ray beam and with their apertures in said mean direction, said anodes being one behind the other across the path of the beam.
  • the shield electrode 6, which is again connected to the cathode, is mounted on a mica or other suitable insulating disc 9 which is carried in a peripheral groove formed in the Wehnelt cylinder 1.
  • the construction of Figure 2 should be modified in such manner as to allow the tip of the filament to project through the disc 5 without touching it, support for the filament being given by the ,mica or other insulating disc 9 and not by the insulator 3.
  • Figure 3 shows a further modification suitable for a hard cathode ray tube.
  • the cathode l is centered by an insulating disc 3 with an apertured shield disc 5.
  • additional insulating discs I0, I I are shown for supporting the rest of the electron gun system. Suitable practical values of dimensions are: length of cathode structure .625, diameter of cathode structure .050", thickness of cathode ma.- terial in the end of the cathode structure .005", dimensions a, b, c, d, e, and J, .020, .050", .070", .100", .030” and .800 respectively.
  • a cathode ray tube comprising a symmetrical positioning planar insulator, a cathode projecting through and beyond the insulator and supported only therefrom, a symmetrical electrode positioned upon said insulator, said electrode serving as a focusing member, and means for electrically connecting said electrode to said cathode.
  • a cathode ray tube comprising a cathode, an annular cylindrical electrode surrounding said cathode, a positioning insulator supporting said cathode co-axially with said electrode, a disk electrode mounted on said insulator, and means directly connecting said last named electrode to the cathode.
  • a cathode ray tube comprising a cathode, an annular cylindrical electrode surrounding said cathode, a positioning insulator, supporting said cathode co-axially with said electrode, a disk electrode mounted on said insulator, and a direct metallic connection within the tube from said disk electrode to said cathode.
  • a cathode ray tube comprising a positioning insulator, a cathode projecting through and beyond the insulator and supported only therefrom, and conducting means upon the insulator for preventing the accumulation of charges upon the insulator.
  • a cathode ray tube comprising a positioning insulator, a. cathode projecting through and beyond the insulator and supported only therefrom, and an electrostatic shield in contact with the insulator for preventing the accumulation of charges upon the insulator.
  • a cathode ray tube comprising a symmetrical positioning insulator, a cathode projecting through and beyond the insulator, and supported only therefrom, and a single symmetrical focusing and shielding electrode positioned upon the insulator.
  • a cathode ray tube comprising a positioning insulator, a cathode projecting through and beyond the insulator and supported therefrom, conducting means upon the insulator for preventing the accurnulation of charges upon the insulator, and a coaxial annular cylindrical electrode surrounding the cathode and conducting means.
  • a cathode ray tube comprising a positioning insulator, an indirectly heated cathode projecting through and beyond the insulator and supported therefrom, a disk electrode mounted upon the insulator and in electrical conductive relationship to the cathode, and a coaxial annular cylindrical electrode surrounding the cathode and disk electrode.
  • a cathode ray tube comprising a positioning insulator, a cathode projecting through and be yond the insulator and supported only therefrom, a disk electrode mounted upon the insulato-r and connected electrically directly to the cathode, and a plurality of apertured electrodes in register with the cathode.

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  • Silicates, Zeolites, And Molecular Sieves (AREA)
  • Electron Sources, Ion Sources (AREA)
US37462A 1934-08-30 1935-08-23 Cathode ray tube Expired - Lifetime US2153223A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB25023/34A GB443730A (en) 1934-08-30 1934-08-30 Improvements in or relating to cathode ray tubes suitable for use for television and similar oscillograph purposes

Publications (1)

Publication Number Publication Date
US2153223A true US2153223A (en) 1939-04-04

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Family Applications (1)

Application Number Title Priority Date Filing Date
US37462A Expired - Lifetime US2153223A (en) 1934-08-30 1935-08-23 Cathode ray tube

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US (1) US2153223A (fr)
BE (1) BE410992A (fr)
FR (1) FR793794A (fr)
GB (1) GB443730A (fr)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2429824A (en) * 1943-10-08 1947-10-28 Du Mont Allen B Lab Inc Gun structure for cathode-ray tubes
US2808527A (en) * 1955-11-22 1957-10-01 Gen Electric Cathode support strap
US2818519A (en) * 1953-11-13 1957-12-31 Telefunken Gmbh Cathode-ray tube
US2877369A (en) * 1955-06-02 1959-03-10 Rca Corp Electron beam tube
US3317981A (en) * 1963-11-18 1967-05-09 Sylvania Electric Prod Expanding hollow plastic posts on opposite sides of electrode apertures for gripping electrodes
US4644219A (en) * 1984-02-29 1987-02-17 Siemens Aktiengesellschaft Beam generating system for electron tubes, particularly travelling wave tubes
US5000215A (en) * 1988-04-27 1991-03-19 Phillips Edwin D Bellows seal for valves and the like
US5851476A (en) * 1996-05-17 1998-12-22 Miner Enterprises, Inc. Method of manufacturing a bellowed seal

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2429824A (en) * 1943-10-08 1947-10-28 Du Mont Allen B Lab Inc Gun structure for cathode-ray tubes
US2818519A (en) * 1953-11-13 1957-12-31 Telefunken Gmbh Cathode-ray tube
US2877369A (en) * 1955-06-02 1959-03-10 Rca Corp Electron beam tube
US2808527A (en) * 1955-11-22 1957-10-01 Gen Electric Cathode support strap
US3317981A (en) * 1963-11-18 1967-05-09 Sylvania Electric Prod Expanding hollow plastic posts on opposite sides of electrode apertures for gripping electrodes
US4644219A (en) * 1984-02-29 1987-02-17 Siemens Aktiengesellschaft Beam generating system for electron tubes, particularly travelling wave tubes
US5000215A (en) * 1988-04-27 1991-03-19 Phillips Edwin D Bellows seal for valves and the like
US5851476A (en) * 1996-05-17 1998-12-22 Miner Enterprises, Inc. Method of manufacturing a bellowed seal

Also Published As

Publication number Publication date
BE410992A (fr)
FR793794A (fr) 1936-01-31
GB443730A (en) 1936-03-02

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