US2250721A - Image storage tube - Google Patents

Image storage tube Download PDF

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Publication number
US2250721A
US2250721A US254592A US25459239A US2250721A US 2250721 A US2250721 A US 2250721A US 254592 A US254592 A US 254592A US 25459239 A US25459239 A US 25459239A US 2250721 A US2250721 A US 2250721A
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United States
Prior art keywords
mosaic
screen
electrons
scanning
elements
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
US254592A
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English (en)
Inventor
Moller Rolf
Machnow Klein
Hartmann Werner
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.)
Robert Bosch Fernsehanlagen GmbH
Original Assignee
Fernseh 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 Fernseh GmbH filed Critical Fernseh GmbH
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Publication of US2250721A publication Critical patent/US2250721A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J31/00—Cathode ray tubes; Electron beam tubes
    • H01J31/08—Cathode ray tubes; Electron beam tubes having a screen on or from which an image or pattern is formed, picked up, converted, or stored
    • H01J31/26—Image pick-up tubes having an input of visible light and electric output
    • H01J31/28—Image pick-up tubes having an input of visible light and electric output with electron ray scanning the image screen
    • H01J31/30—Image pick-up tubes having an input of visible light and electric output with electron ray scanning the image screen having regulation of screen potential at anode potential, e.g. iconoscope
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J31/00—Cathode ray tubes; Electron beam tubes
    • H01J31/08—Cathode ray tubes; Electron beam tubes having a screen on or from which an image or pattern is formed, picked up, converted, or stored
    • H01J31/26—Image pick-up tubes having an input of visible light and electric output
    • H01J31/48—Tubes with amplification of output effected by electron multiplier arrangements within the vacuum space

Definitions

  • Our invention relates to storage pick-up tubes for television purp ses, and particularly to such tubes utilizing a mosaic of insulated photoelectric elements upon'which a charge image is stored in accordance with an optical image, and in which this mosaic is scanned point by point. Under scansion a picture signal is generated and the charges on the-mosaic, elements under scansion neutralized, whereupon recharging takes place.
  • scansion of the mosaic is effected by impact of a high-velocity electron beam which causes secondary electrons to be emitted and the charges on the mosaic elements to become neutralized.
  • the potential which the elements will acquire after neutralization depends upon the secondary emission produced by the scanning beam and adjusts itself to an equilibrium potential which is only several volts below that of the electrode to which the secondary electrons are accelerated. Consequently only a 9 weak accelerating field exists in front of a mosaic during the charge and it becomes extremely diflicult to achieve saturation of the photoelectrons under the influence of the incident optical image. Another consequence thereof is that not all secondary electrons generated at the mosaic by the scanning beam are drawn away, but a substantial portion thereof is drawn to neighboring mosaic elements and prematurely discharge the latter.
  • FIG. 1 schematically illustrates a cross section through a storage tube according to our invention, reduced to the simplest terms for sake of simplicity;
  • Fig. 2 schematically shows a cross section through a mosaic screen embodying our invention;
  • Fig. 3 schematically shows a cross section through a modified type of mosaic screen according to our invention.
  • our invention provides the use of a strong accelerating field in frontof the mosaic and scansion with low-velocity electrons which liberate no or only a few secondary electrons.
  • the low-velocity electrons used for scansion are generated photoelectrically. While it is known in the art to produce trons by photoelectric means, the disadvantage of this method when hitherto used has been that the mosaic needed to be double-sided and that a diiiusion of the scanning electrons would take therefore. provides that the photoelectrically produced scanning electrons impact the mosaic on the same side from which the picture photoelectrons are liberated, and that the fields traversed by the scanning electrons are separated from the field which accelerates. the picture photoelectrons.
  • the impacting velocity of the scanning electrons is determined by the potential difference between the potential of the mosaic elements in discharged condition and the potential produced by the charges caused by exposure to light.
  • the fields traversed by the scanning electrons are preferably separated for each individual picture element, so that the scanning electrons again impact only the corresponding mosaic elements.
  • all mosaic elements can be screened off against each other.
  • Fig. 1 shows a vacuum receptacle l housing an electron gun consisting of a cathode 8, an
  • Reference numeral 2 designates the mosaic screen upon which an optical image ispondered by means of lens 3.
  • A is a wide open wire mesh scanning elec-' screen 4 servesas an accelerating electrode or picture signal collector.
  • Two electron multipliers 5 and 5a each comprising a plurality of secondary-emissive grids and a solid plate collector, may be provided.
  • a voltage source 9 serves to heat the cathode 8.
  • a voltage divided I! in cooperation with a voltage source i8 for supplies anode 6, accelerating screen 4 and electron multipliers 5 and 5a with operating voltages.
  • a signal output resistor l9 across which the signal can be taken off by way of a condenser 20, is connected to the anodes of the electron multipliers 5 and 5a.
  • Fig. 3 shows a modification of the mosaic screen which includes a transparent insulating layer I I, a fluorescent screen l4, a wire mesh screen l2 and the mosaic electrodes l3 which, in this case, are button-like in shape, possessing a photosensitive front surface and side surfaces insensitive to light and secondary emission.
  • Fig. 2 shows a screen comprising two layers H of an insulating material, such as mica, between which a translucent metal layer I6 is disposed.
  • One of the layers II is provided with a fluorescent screen l4, while the other layer II is in close contact with a metal wire mesh screen I2.
  • a metal wire mesh screen I2 In order to secure a close contact it may be preferable to provide the layers H and the metal layer l6 with a slight curvature and to stretch the metal screen l2 across the same.
  • photoelectric mosaic elements l3 are deposited upon the last-mentioned of the layers ll. Portions l5 of the screen l2 are made to be photoemissive.
  • Fig. 3 shows a modification of the mosaic screen which includes a transparent insulating layer II, a fluorescent screen l4, a wire mesh screen I! and mosaic electrodes l3 which. in this case, are button-like in shape, possessing a photosensitive front surface and side surfaces insensitive to light and secondary emission.
  • an optical image is focused upon the right side of a mosaic screen 2, as shown in Fig. l, and photoelectrons emitted by mosaic elements i3 are accelerated toward grid 4, which is held approximately 100 volts positive with respect to the assumed potential of the photomosaic.
  • the accelerating field developed by the potential applied to the electrode 4 reaches into the openings of the screen I2 and exerts In case some photoelectrons should be intercepted by the screen l2, the latter rapidly accumulates a negative charge thereby, hence preventing any further collection of photoelectrons from the mosaic elements l3 and enhancing the focusing above referred to.
  • the cathode ray beam produced by cathode 8 which is deflected by applying sawtooth voltages to deflecting plates 1, as is well-known in the art, is scanned across fluorescent screen l4 and produces light upon impact therewith. Due to the bombardment by high velocity electrons the fluorescent screen l4 will assume a potential which is positive to the cathode 8.
  • the portion of the inner wall of the envelop I surrounding the discharge space between the cathode 8 and the fluorescent screen l4 may, if desired, be provided with a conductive coating (not shown) connected to the anode 6 in order to collect the secondary electrons emitted by the fluorescent screen l4 and anode 6,
  • a mechanical mask can be used during evaporation of the silver, or during oxidation, respectively, which can be removed later on.
  • network H can be made of a material which does not oxidize very readily (nickel, molybdenum, platinum). The work function of the surface will then be considerably higher than that of a silver oxide-caesium layer.
  • Light of a short wave length, particularly ultra violet light, is then used for generation of scanning electrons, The luminescent substance is then so chosen that it has its maximum efficiency, or at least emits suflicient light, in the spectral range following the shortest wave length of the light used in the optical range.
  • elements l3 must have a size of about 0.2x0.2 mm. for 441 lines.
  • the meshsize of network 12 is determined thereby.
  • a separate cathode ray tube can also be optically reproduced in the plane of network l2.
  • a pattern of uniform brilliancy is recorded on the screen of this tube in the known manner so that photoelectrons are emitted from portions l5 point by point. Fluorescent screen I can then be omitted.
  • a television signal generating device comprising a plurality of photoelectric sources, means for developing a spot of light of substantially constant brightness, means for efiecting movements of said spot across said source in accordance with a scanning pattern to cause said sources to emit electrons in successive order, photoelectric mosaic means adapted to have an optical image focused thereon for collecting portions of the electrons emitted from each of said sources in accordance with variations in the illumination over said image, and means for collecting the remainder of said emitted electrons to produce a signal representing said image.
  • a television signal generating device comprising a plurality of photoelectric sources, means for developing a spot of light of subprising a stantially constant brightness, means for scanning said sources by said light spot in accordance with a scanning pattern to cause said sources to emit electrons in successive order, photoelectric mosaic means adapted to have an optical image focused thereon for collecting portions of the electrons emitted from each of said sources in accordance with variations in the illumination over said image, and means for collecting the remainder of said emitted electrons to produce a signal representing said image.
  • a television signal generating device comtranslucent insulating member, a coating of fluorescent material on one side of said member, means facing said one' side for generating an electron beam, means for deflecting said beam across said fluorescent coating in accordance with a scanning pattern, an apertured metallic screen having photosensitive areas adjacent the other side .of said member, photoelectric mosaic elements disposed on said other side of said member within the apertures of said screen and adapted to have an optical image focused thereon from a point facing said other side, and means for collecting electrons emitted from said photosensitive areas and said mosaic elements to produce a signal representative of said image.

Landscapes

  • Image-Pickup Tubes, Image-Amplification Tubes, And Storage Tubes (AREA)
US254592A 1938-02-08 1939-02-04 Image storage tube Expired - Lifetime US2250721A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE2250721X 1938-02-08

Publications (1)

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US2250721A true US2250721A (en) 1941-07-29

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US254592A Expired - Lifetime US2250721A (en) 1938-02-08 1939-02-04 Image storage tube

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US (1) US2250721A (id)
BE (1) BE432586A (id)
FR (1) FR850034A (id)
NL (1) NL58572C (id)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2462569A (en) * 1946-09-11 1949-02-22 Rca Corp Television receiving tube with storage properties
US2507958A (en) * 1946-02-21 1950-05-16 Emi Ltd Mosaic screen for cathode-ray tubes
US2549072A (en) * 1946-02-27 1951-04-17 Rca Corp Recording apparatus for radar systems
US2558647A (en) * 1947-12-12 1951-06-26 Cinema Television Ltd Storage electrode type cathode-ray tube
US2601452A (en) * 1946-09-27 1952-06-24 Rca Corp Cathode-ray storage tube
US2999177A (en) * 1946-08-19 1961-09-05 Fay E Null Infra-red-sensitive mosaic

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2507958A (en) * 1946-02-21 1950-05-16 Emi Ltd Mosaic screen for cathode-ray tubes
US2549072A (en) * 1946-02-27 1951-04-17 Rca Corp Recording apparatus for radar systems
US2999177A (en) * 1946-08-19 1961-09-05 Fay E Null Infra-red-sensitive mosaic
US2462569A (en) * 1946-09-11 1949-02-22 Rca Corp Television receiving tube with storage properties
US2601452A (en) * 1946-09-27 1952-06-24 Rca Corp Cathode-ray storage tube
US2558647A (en) * 1947-12-12 1951-06-26 Cinema Television Ltd Storage electrode type cathode-ray tube

Also Published As

Publication number Publication date
FR850034A (fr) 1939-12-06
BE432586A (id)
NL58572C (id)

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