US2123161A - Television tube - Google Patents

Television tube Download PDF

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Publication number
US2123161A
US2123161A US86608A US8660836A US2123161A US 2123161 A US2123161 A US 2123161A US 86608 A US86608 A US 86608A US 8660836 A US8660836 A US 8660836A US 2123161 A US2123161 A US 2123161A
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US
United States
Prior art keywords
cathode
screen
image
lens
electron
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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
US86608A
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English (en)
Inventor
Schlesinger Kurt
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.)
Loewe Opta GmbH
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Loewe Opta GmbH
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 Loewe Opta GmbH filed Critical Loewe Opta GmbH
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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
    • H01J29/58—Arrangements for focusing or reflecting ray or beam
    • H01J29/62—Electrostatic lenses
    • H01J29/622—Electrostatic lenses producing fields exhibiting symmetry of revolution
    • H01J29/624—Electrostatic lenses producing fields exhibiting symmetry of revolution co-operating with or closely associated to an electron gun

Definitions

  • the subject matter of the invention is a highvacuum television tube with electrostatic concentration and preferably electrostatic deflection.
  • the essential feature of the tube according to the invention is the performance of the electrostatic concentration, operating with two collecting lenses, which are arranged in series, and which reproduce a part of the ray lying in the immediate vicinity of the surface of the cathode.
  • features of the invention are (1) the omission of a diaphragm, (2) the ability of the tube to produce image points of different size on the screen according to the adjustment of the refractive powers of the two lenses, (3) the fact that the lens near the cathode, the so-called first or rear lens (viewed from the screen) is unable alone to project any real image of the cathode on the luminous screen, but produces a virtual image of the cathode, and that it is only by means of the second lens (front lens) that a real, sharp image of the cathode is formed on the luminous screen.
  • a cross-sectional portion of the cathode beam situated adjacent the cathode means a cross-sectional portion of the beam situated either immediately at the surface of the cathode or in close vicinity of this surface.
  • Fig. 1 whereof shows the essential parts of a cathode ray tube designed according to the invention in a schematic longitudinal section together with certain circuit elements and symbols illustrating the electron-optical conditions
  • Fig. 2 is a dimensional longitudinal section through a cathode ray tube designed on the lines illustrated in Fig. 1, the base and the screen portion of the tube being broken away, as these may be of any conventional or other type.
  • Fig. 3 is a diagram illustrating in more detail the electron-optical conditions set forth in connection with Fig. 1.
  • Fig. 4 again is a schematic view similar to Fig. 1, showing a modification
  • Fig. 4a in a similar manner shows a modified form of a certain detail.
  • the hot cathode l consists of a nickel cylinder, in which there is embedded a defined spot of oxide 2, having a diameter of say mm.
  • a defined spot of oxide 2 having a diameter of say mm.
  • the diameters of the apertures of 4 and 3 amount to 1 mm. and the ray current passes therethrough entirely unstopped.
  • the bias of 3 amounts to several hundred volts and may also be directly connected with the tubular member 6.
  • a cylinder 5 Between 3 and 8 there is mounted a cylinder 5.
  • the cylinder is situated nearer to 6 than to 3, and is negative in relation to the last mentioned electrodes.
  • the bias of 5 is varied, commencing with positive values, say, the value 6', which represents the bias of the screening grid 3 and the tubular member 6, and the bias is made always less positive, it will be observed, preferably with the aid of plates coated with luminous salt introduced into the tubular member 6, that the narrowest point of the bundle of rays gradually approaches from the screen more and more towards the cathode. In the case of extremely positive adjustment the ray greatly diverges, and
  • the television tube with condensing lens system described by the applicant under ap plication No. 733,995 was so biased that the cathode image coincided with the main lens 8.
  • the ray in the tube according to the present invention is preliminarily concentrated to a much smaller extent.
  • the preliminary concentration is so weak that the image of the cathode, Which can be made visible on the luminous screen 9 when the anode i is joined up with the tubular member 6 and the refractive force 8 is not present, just disappears again in the direction away from the screen.
  • the wiper of the potentiometer is adjusted somewhat more on thepositive side than would correspond in the case of the grid 4 being maintained positive with a sharp reproduction of the cathode surface on the luminous screen.
  • an actual cathode image i. e., an actual constriction
  • a very sharp and bright image point may be adjusted by producing the second lens 8, which is formed by the edge of the tubular member 6 and the anode I 0. All apertures in the diaphragms within the complete tube should be made so large that these diaphragms do not intercept any electrons of the ray. Further details regarding the diameters which are necessary for this purpose are disclosed by Fig. 2.
  • the two lenses l4 and I5 co-operate according to known optical laws in such fashion as if a single collecting lens were situated at a resulting point between the two, for example in the plane H5.
  • the image of the cathode 2 on the luminous screen 9 varies in size dependent on whether this resulting lens I6 is situated nearer towards the cathode or nearer towards the luminous screen; The image is smaller if the lens I6 is situated more towards Thisis the case if the refractive force of the rear lens 5/6 is adjusted to be weaker and the refractive force of the front lens 6/10 to be correspondingly stronger. If vice versa the refractive force of the rear lens is made somewhat stronger, and the refractive force of the front lens weaker, by displacing the wiper 5 towards the cathode and the wiper 6' towards the anode, there may be again obtained a sharp cathode image which then has an enlarged diameter.
  • the subject matter of the invention is an operative condition of this type of two-lens system, which reproduces the cathode, or a cross-section between the cathode and the first anode 3, and which lies between the two adjustment limits aforesaid.
  • FIG. 3 there is shown'an optical image construction applicable to the present case, which reveals additional aspectsin accordance with the invention with regard to the dimensioning of the size of the image point.
  • thisfigure I9 is the cathode radius to be reproduced. The location. of the first lens, the rear lens M, and the second.
  • the image screen is designated 9.
  • the focus 20' of the rear lens #4 is so adjusted that it is situated behind the object of reproduction, i. e., behind the cathode surface H), as shown.
  • the virtual intermediate image 23 of the cathode i9 is found by drawing the middlepoint ray 2
  • the factor 6k being the potential of the cathode which is to virtual intermediate image 23 there is projected on to the luminous screen 9 by the front lens IS the real point image, which is found by drawing the middle-point ray 24.
  • the screen image 25 again requires to be multiplied by a new potential factor, viz., by the factor wherein @t is the potential of the electrons in the tubular member and ea that when passing the anode Hi.
  • this factor is approximately 0.6 corresponding with a potential ratio in the main lens of 1:25 (for example, 800 volts potential of the tubular member with 2,000 volts anode potential).
  • a measure for making this difference in potential as large as possible consists in selecting as large as possible the spacing between the two field-generating electrode systems I and Ill in Fig. 1. In this way the intensity of the field in the case of a given difference in potential will be weakened owing to the increased distance over which the field is formed, and in order nevertheless to produce the requisite refractive force the difference in potential must be increased, i. e., the bias of the tubular member 6 reduced, whereby the speed of the electrons in the space of the tubular member is slowed down and the potential factor and accordingly the size of the image point is still further diminished.
  • An additional measure according to the invention for obtaining an image point as small as possible consists in increasing the spacing.
  • FIG. 4 differs from Fig. l merely by the inclusion of a rear tubular member 21, the length of which may be comparatively small, as this tubuluar member is traversed by electrons having a low speed.
  • a rear tubular member 21 By the inclusion of this tubular member the location of the object of reproduction, viz., the cathode surface 2, is removed further away from the location of the rear lens, viz., the plane M of the cylinder 5.
  • 21 and 5 are linked up with a lower potential than 6. 5 may be connected with 21.
  • the tube operates with a virtual intermediate reproduction if the bias of 2'! has value as low as possible.
  • the effect obtained by the rear tubular member 21 may also be accomplished in similar fashion by withdraw ng, as shown in Fig. 4a, the hot cathode 2 into the interior of the guide cylinder 28 surrounding the same.
  • withdraw ng as shown in Fig. 4a
  • the hot cathode 2 into the interior of the guide cylinder 28 surrounding the same.
  • This field ensures that the cross-section of the ray is practically constant from the cathodeZ to the anode 3, the individual rays accordingly running practically parallel.
  • Tubes of the construction according to the invention are admirably suitable for receiving transmitters with different numbers of lines, as it is possible with the same always to adjust that size of image point at which the lines exactly follow one upon the other without intermediate spacing, in order to effect variation of the screen at the receiving end by simple electrical re-adjustment.
  • a cathode ray tube more particularly for television purposes, comprising means including a cathode for producing a beam of electrons, an
  • a first electron-optical lens disposed between said cathode and said screen and adapted to produce a virtual electron optical image of a cross-sectional portion of said beam situated adjacent to said cathode, a second electronoptical lens disposed between said first lens and. said screen and adapted to produce on said screen a sharp real electron-optical image of the virtual electron-optical image produced by said first lens, and electron deflecting means for causing this real image to sweep over said screen.
  • Electric apparatus more particularly for television purposes comprising a cathode ray tube comprising means including a cathode for producing a beam of electrons, an image screen, two electrodes mounted between said cathode and said image screen, means for maintaining said two electrodes at different potentials for causing said two electrodes toform an electron-optical lens adapted to produce a virtual electron-optical image of a cross-sectional portion of a beam situated adjacent to said cathode, two further electrodes mounted between said first electrodes and said screen, means for maintaining said further two electrodes at different potentials for causing said two electrodes to form a second electron-optical lens adapted to produce on said screen a sharp real electron-optical image of the virtual electron-optical image produced by said first lens, and electron deflecting means for causing this real image to sweep over said screen.
  • Electric apparatus more particularly for television purposes comprising a cathode ray tube comprising means including a cathode for producing a beam of electrons, an image screen, two electrodes mounted between said cathode and said image screen, adjustable means for maintaining said two electrodes at different potentials for causing said two electrodes to form an electron-optical lens adapted to produce a virtual electron-optical image of a cross-sectional portion of a beam situated adjacent to said cathode, two further electrodes mounted between said first electrodes and said screen, adjustable means for maintaining said further two electrodes at different potentials for causing said two electrodes to form a second electron-optical lens adapted to produce on said screen asharp real electron-optical image of the virtual electronoptical image produced by said first lens, and
  • a cathode ray tube more particularly for television purposes comprising means including a cathode for producing a beam of electrons, an image screen, an electrode system comprising electrodes for forming an electron-optical lens disposed between said cathode and said screen and adapted to produce a virtual electron-optical image of a cross-sectional portion of said beam situated adjacent to said cathode, a second electron-optical lens disposed between said first lens and said screen and adapted to produce on said screen a sharp real electron-optical image of the virtual electron-optical image produced by said first lens, and electron deflecting means for causing this real image to sweep over said screen, any such of the electrodes of which said electrode system consists which are disposed in the path of said electron beam having apertures for allowing said passage of said beam, each of said apertures being at least as large as the crosssection of said beam in the plane of said aperture so that no electrons of said beam are shuttered ofi.
  • the method of adjusting the size of the electronoptical image point on the image screen mentioned more particularly for adapting, in a television receiving set, the size of the image point to the number of transmitted scanning lines and a desired picture size, without impairing the sharpness of the image point, comprising the steps of adjusting the potential difierence between the first mentioned two electrodes and of adjusting simultaneously with said potential difference the potential difierence between the second mention-ed two electrodes by an alteration opposite in sense to the alteration by which the first said potential difierence is adjusted.
  • a cathode ray tube more particularly for television purposes, comprising means including a cathode for producing a beam of electrons, an image screen, a first electron-optical collecting lens disposed between said cathode and said screen and adapted to produce a virtual electron-optical image of a cross-sectional portion of said beam situated adjacent to said cathode, a second electron-optical collecting lens disposed between said first lens and said screen and adapted to produce on said screen a sharp real electron-optical image of the virtual electron-optical image produced by said first lens, and electron deflecting means for causing this real image to sweep over said screen.
  • a cathode ray tube more particularly for television purposes, comprising means including a cathode for producing a beam of electrons, an image screen, a first electron-optical lens disposed between said cathode and said screen and adapted to produce a virtual electron optical image of a cross-sectional portion of said beam situated adjacent to said cathode, a tubular member interposed between said cathode and said first electron-optical lens, the length of said tubular member being large in comparison withthe extension of said first electron-optical lens in the direction from said cathode to said image screen, a second electron-optical lens disposed between said first lens and said screen and adapted to produce on said screen a sharp real electronoptical image of the virtual electron-optical image produced by said first lens, and electron deflecting means for causing this real image to sweep over said screen.
  • a cathode ray tube more particularly for television purposes, comprising means including a cathode and an anode for producing a beam of electrons, a Wehnelt-cylinder surrounding said cathode, a control grid mounted inside said Wehnelt cylinder, an image screen, said anode being mounted near said Wehnelt cylinder at the side thereof facing said image screen, said cathode and said control-grid being withdrawn into the interior of said Wehnelt-cylinder so that a preliminary concentration field is formed between said anode and the surface facing said anode of said cathode, a first electron-optical lens disposed between said anode and said screen and adapted to produce a virtual electron-optical image of a crosssectional portion of said beam situated adjacent to said cathode, a second electron-optical lens disposed between said first lens and said screen and adapted to produce on said screen a sharp real electron-optical image of the virtual electron-optical image produced by said first lens, and electron deflecting means for
  • Electric apparatus more particularly for television purposes comprising a cathode ray tube comprising means including a cathode for pro-- ducing a beam of electrons, an image screen, two electrodes mounted between said cathode and said image screen, means for maintaining said two electrodes: at different potentials for causing said two electrodes to form an electron-optical lens adapted to produce a virtual electron-optical image of a cross-sectional portion of said beam situated adjacent to said cathode, two further electrodes mounted between said first electrodes and said screen at a large distance from each other, means for applying a large potential difference between said further two electrodes for causing said two electrodes to form a second electron-optical lens adapted to produce on said screen a sharp real electron-optical image of the virtual electron-optical image produced by said first lens, and electron deflecting means for causing this real image to sweep over said screen.

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US86608A 1935-06-25 1936-06-22 Television tube Expired - Lifetime US2123161A (en)

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Application Number Priority Date Filing Date Title
DE203820X 1935-06-25

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US2123161A true US2123161A (en) 1938-07-05

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US (1) US2123161A (d)
BE (1) BE416227A (d)
CH (1) CH203820A (d)
FR (1) FR808566A (d)
GB (1) GB480672A (d)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2792515A (en) * 1951-06-22 1957-05-14 Thomas Electrics Inc Cathode ray tube
US2930931A (en) * 1955-09-28 1960-03-29 Kaiser Ind Corp Electronic device
US3863091A (en) * 1972-12-29 1975-01-28 Hitachi Ltd Electron gun assembly with improved unitary lens system

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5543660Y2 (d) * 1972-04-12 1980-10-14
ES475304A1 (es) * 1977-11-22 1979-03-16 Tokyo Shibaura Electric Co Perfeccionamientos en canones electronicos para tubos de ra-yos catodicos.

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2792515A (en) * 1951-06-22 1957-05-14 Thomas Electrics Inc Cathode ray tube
US2930931A (en) * 1955-09-28 1960-03-29 Kaiser Ind Corp Electronic device
US3863091A (en) * 1972-12-29 1975-01-28 Hitachi Ltd Electron gun assembly with improved unitary lens system

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Publication number Publication date
FR808566A (fr) 1937-02-10
GB480672A (en) 1938-02-25
CH203820A (de) 1939-03-31
BE416227A (d)

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