US2089546A - Cathode ray tube - Google Patents

Cathode ray tube Download PDF

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Publication number
US2089546A
US2089546A US755336A US75533634A US2089546A US 2089546 A US2089546 A US 2089546A US 755336 A US755336 A US 755336A US 75533634 A US75533634 A US 75533634A US 2089546 A US2089546 A US 2089546A
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US
United States
Prior art keywords
screen
envelope
cathode ray
radius
curvature
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
US755336A
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English (en)
Inventor
Dudding Bernard Phineas
Jesty Leslie Connock
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.)
General Electric Co PLC
Original Assignee
General Electric Co PLC
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by General Electric Co PLC filed Critical General Electric Co PLC
Application granted granted Critical
Publication of US2089546A publication Critical patent/US2089546A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • H01J29/86—Vessels; Containers; Vacuum locks
    • H01J29/861—Vessels or containers characterised by the form or the structure thereof
    • 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
    • H01J29/86—Vessels; Containers; Vacuum locks
    • H01J29/87—Arrangements for preventing or limiting effects of implosion of vessels or containers

Definitions

  • a cathode ray tube we mean a device (a) comprising means for producing a beam of cathode rays, and (b) comprising means for deflecting the beam sothat in the later part of its path it can be made to travel substantially along any line passing through the apex of some cone and lying within that cone, (0) comprising an envelope of which the portion within the intersection of the envelope with the said cone is substantially a segment of a sphere having a radius not substantially less than the distance of the said portion from the apex of the said cone, and (12) such that the image produced by the cathode ray is viewed through the portion of the envelope mentioned in (c).
  • the said portion of the envelope is coated internally with fluorescent material; hereinafter it will be termed for brevity the screen. But it must be understood that it need not actually be a fluorescent screen and that the cathode rays need not actually impinge on it; for in some tubes the fluorescent screen is a memberseparate from the envelope. However, if such tubes possess the four 1 elements (a), (b) (c) (d) above mentioned, then the portion of the envelope defined under (0) will still be termed the screen, and the inven- 0 tion will be applicable to them; for it will appear that the invention is concerned with the shape of the envelope alone.
  • the cathode ray tube When the cathode ray tube is of considerable size (say of length greater than 45 cm. long and with a screen more than 15 cm. in diameter) there is difficulty in making glass envelopes thin enough to stand the thermal changes to .which they are subjected and yet thick enough to withstand the external atmospheric pressure when evacuated. Sometimes the envelope of large tubes will endure during manufacture and will collapse without Warning during use. Such collapse is disastrous, not only because the tubes are expensive, but because the implosion is very dangerous to by-standers; the glass and"the electrodes are liable to be projected with great force.
  • the object of this invention is to reduce greatly the risk of such collapse by suitable shaping of the envelope.
  • the region of greatest strain in the glass is in the end portion. It is particularly severe because tension and compression are liable to occur within a short distance of each other.
  • the general stress is, of course, compressive; but part of the compressive stress on the screen and the parts immediately surrounding it are borne by circumierential tension in the corner where the spherical part joins the conical part. This tension may not be wholly counterbalanced by atmospheric compression; part of the glass here may be in tension while all the remainder is compressed.
  • liability to collapse can be greatly diminished by shaping the envelope so that there is no part in resultant tension, or even by proceeding part of the way in this direction so that the resultant tension is greatly reduced. This can be achieved by rounding the corners at which the dangerous stress occurs and by increasing the radii of curvature here above the values that are at present usual.
  • the radius of curvature of the end portion of a cathode ray tube is everywhere so great that no part of this portion is in substantial tension when the tube is completely evacuated and exposed to atmospheric pressure on the outside.
  • Substantial tension here means a tension so great that its reduction would We have found that the condition according to the invention can generally be attained, and the risk of collapse can be reduced within reasonable bounds, if the ratio of the radius of curvature of the end portion to the radius of curvature of the screen is nowhere less than 1/7.5. In order that tension should be entire]; remoted it is seldom necessary to make the ratio much greater than 1/5;
  • the increase of this ratio over the values used at present can be secured either by decreasing the radius of curvature of the screen or by increasing the radius of curvature of the part surroundingthe screen.
  • the first course has the disadvantage of introducing distortion of the image; for the image is least distorted when the screen is of least curvature. Moreover, if this course were pursued too far, the condition would cease to be fulfilled and the envelope would fall outside the scope of the invention.
  • the second course pursued alone, necessarily makes the tube bulkier by increasing its maximum diameter. But the increase required turns; out not to'be very serious. It is possible to make cathode ray' tubes according to the invention in which the ratio of the maximum diameter; to the diameter of that part of the screen on which an image can be reproduced without substantial distortion is no greater than 4/3. Preferably this ratio is not exceeded.
  • Figure 2 of the accompanying drawingv shows one example of,.an envelope constructed in accordance with the invention.
  • the radius of curvature of thescreen l. is 28 cm.
  • the radius of; curvature at;.the point: marked 2 is 6 cm.
  • the diameter, of; that ,part of the screen on which an image can be, reproduced is 23 cm. and the maximum diameter of the tube is 30 cm.
  • Figure 3 of the accompanying drawing shows another; example.
  • the radiusof curvature of the screen I is 32-cm.
  • the radius of curvature at. the point marked 2 is, 4.8 cm.
  • the diameter of that partof the screen on which the image can be reproduced is 23.5 cm.
  • the maximum diameter of the tube is 29.5 cm.
  • An envelope for a cathode ray tube comprising a main portion, part at least of which is substantially in the form of a. conic frustum, a screen portion having a radius of curvature of 28 cm. and a diameter of 23 cm. and a curved end portion connecting the main portion to the screen portion and having a minimum radius of curvature of 6 cm. the maximum diameter of the envelope being 30 cm.
  • An envelope for a cathode ray tube an envelope comprising a main portion, part at least of which is substantially in the form of a conic frustum, a screen portion having a radius of curvature of 32 cm. and a diameter of 23.5 cm. and a curved end portion connecting the main portion to the screen portion and having a mini mum radiusof curvature of 4.8 cm. the maximum diameter of the envelope being,29.5 cm.
  • An envelope of vitreous material for a cathode ray tube of large size comprising a screen portion. formed as a spherical segment of not less than 15 cm. in diameter, a substantially conical portion symmetrical with said screen portion and connected therewith by a connecting portion formed as. a.
  • An envelope of vitreous material for a large size'cathode ray tube comprising a screen in the form of a spherical segment, the diameter of which is in excess of 15 centimeters and the spherical radius of which is in excess of said diameter, a substantially frusto-conical portion and an end-portion uniting said screen with said frusto-conical portion, said end portion being in the form of a curved surface of revolution, the ratio'of the radius of the uniting end portion to the spherical radius of the screen being not less than 1/'l.5 so that thetensional stresses in the envelope when exhausted shall not exceed a predetermined safe limit for the vitreous material of the'envelope.

Landscapes

  • Vessels, Lead-In Wires, Accessory Apparatuses For Cathode-Ray Tubes (AREA)
US755336A 1933-12-19 1934-11-30 Cathode ray tube Expired - Lifetime US2089546A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB35738/33A GB429045A (en) 1933-12-19 1933-12-19 Improvements in or relating to cathode ray tubes

Publications (1)

Publication Number Publication Date
US2089546A true US2089546A (en) 1937-08-10

Family

ID=10381027

Family Applications (1)

Application Number Title Priority Date Filing Date
US755336A Expired - Lifetime US2089546A (en) 1933-12-19 1934-11-30 Cathode ray tube

Country Status (5)

Country Link
US (1) US2089546A (ru)
BE (1) BE406715A (ru)
FR (1) FR781725A (ru)
GB (1) GB429045A (ru)
NL (1) NL49145C (ru)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2533334A (en) * 1945-10-18 1950-12-12 Philco Corp Cathode-ray tube
US2538852A (en) * 1945-12-29 1951-01-23 Rauland Corp Kinescope projection by refractive optical system mounted on tube neck
US2629838A (en) * 1949-08-04 1953-02-24 Technicolor Motion Picture Color television screen with correction for overplay
US2904713A (en) * 1952-07-15 1959-09-15 Heraeus Schott Quarzschmelze Casings for gas discharge tubes and lamps and process
US3128169A (en) * 1953-11-25 1964-04-07 Heraeus Schott Quarzschmelze Process for making quartz glass casings

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2533334A (en) * 1945-10-18 1950-12-12 Philco Corp Cathode-ray tube
US2538852A (en) * 1945-12-29 1951-01-23 Rauland Corp Kinescope projection by refractive optical system mounted on tube neck
US2629838A (en) * 1949-08-04 1953-02-24 Technicolor Motion Picture Color television screen with correction for overplay
US2904713A (en) * 1952-07-15 1959-09-15 Heraeus Schott Quarzschmelze Casings for gas discharge tubes and lamps and process
US3128169A (en) * 1953-11-25 1964-04-07 Heraeus Schott Quarzschmelze Process for making quartz glass casings

Also Published As

Publication number Publication date
NL49145C (ru)
BE406715A (ru)
FR781725A (fr) 1935-05-21
GB429045A (en) 1935-05-23

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