US2596061A - Television and like transmitting apparatus - Google Patents

Television and like transmitting apparatus Download PDF

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Publication number
US2596061A
US2596061A US166369A US16636950A US2596061A US 2596061 A US2596061 A US 2596061A US 166369 A US166369 A US 166369A US 16636950 A US16636950 A US 16636950A US 2596061 A US2596061 A US 2596061A
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US
United States
Prior art keywords
gun
electron
image
target
cathode
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
US166369A
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English (en)
Inventor
Webley Reginald Sidney
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.)
EMI Ltd
Electrical and Musical Industries Ltd
Original Assignee
EMI Ltd
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 EMI Ltd filed Critical EMI Ltd
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Publication of US2596061A publication Critical patent/US2596061A/en
Anticipated expiration legal-status Critical
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Classifications

    • 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
    • H01J31/34—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 cathode potential, e.g. orthicon
    • 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

Definitions

  • This invention relates to television and like transmitting apparatus.
  • the target and the photo-sensitive electrode arev in line.
  • double-sided targets have been found to possess a number of disadvantages.
  • the object of the present invention is to provide improved television or like transmitting apparatus embodying a pick-up tube of the electron image type, which does not involve the use of a double-sided target.
  • television or like transmitting apparatus embodying a television transmission tube having a photoelectric cathode capable of converting a light image into an electron image, a target, and an electron gun mounted in a direct line between said cathode and said target for producing a beam of electrons for scanning said target, means for producing a scanning field between said gun and said target for scanning an electron beam generated by said gun over said target, and means for producing an oppositely directed scanning field between said cathode and gun so that an electron image can be projected from said cathode to said target without substantial deflection at the target.
  • Figure 1 illustrates one example of a television transmitting apparatus in accordance with the present invention
  • Figure 2 illustrates a modification of the apparatus illustrated in Figure 1.
  • the tube illustrated in Figure 1 comprises an evacuated glass envelope I having a window 2 at one end, on which is deposited a photo-electric cathode 3.
  • a target comprising a thin sheet of dielectric material 4 facing the photo-sensitive electrode 3 and having a conductive signal plate 5 applied to the side of the sheet 4 opposite said electrode 3.
  • An electron gun 6 is located between the electrode 3 and the sheet 4, the gun comprising a thermionic cathode 1, modulating electrode 8 and anode 9 which as shown are coaxial and have their common axes disposed transversely of the axis of the envelope l.
  • the gun is also shown centrally disposed between the electrode 3 and the sheet 4, but the central disposition though desirable is not necessary.
  • the electrode 3, the sheet 4 and the gun 6 are arranged in line, and the electrode 3 and sheet 4 are normal to the axis of the envelope I.
  • the anode of the gun extends almost wholly across the envelope l and the diameter-of the gun 6 is arranged to be as small as possible to minimise the shadow cast on the dielectric sheet 4, the gun diameter being relatively enlarged on the drawings for convenience of illustration.
  • Small circular apertures facing the sheet 4 are formed as shown on the modulator electrode 8 and anode 9 where the axis of the envelope l intersects these electrodes and electron emissive material is provided on the thermionic cathode l beneath these apertures.
  • the cathode of the gun 6 is earthed, while the anode 9 is connected to a source IU of positive potential of, say, 300 volts and the modulator electrode is connected to a suitable source of bias potential H.
  • a wall coating 12 of resistive material is provided on the inner surface of the envelope 1 between the gun 6 and the dielectric sheet 4, the coating being connected at the end nearer the gunto theafores'aid potential source it and at the other end to earth, so that there is a uniform fall in potential from left to right (in the drawing) along the wall coating 12, serving to produce efiectively planar equipotential surfaces between the gun 6 and the dielectric sheet 4 normal to the axis of the envelope 1.
  • the equipotential surfaces decelerate the beam of electrons emanating from the electron gun so that the beam approaches the target with a low velocity.
  • a similar resistive wall coating [3 is provided on the inner surface of the envelope likewise connected at the end nearer the gun to the potential source If! and at its other end to asource of negative potential of for example, 500 volts negative, the equipotential surfaces established by the wall coating l3 serving to accelerate elec tron images released from the electrode 3 towards the gun 6.
  • the electrode 3 is connected to the source it, and an optical system indicated diagrammatically at I4 is provided for focussing a light image of the object for transmission on to the electrode 3.
  • the apparatus also comprises scanning coils indicated diagrammatically at It disposed between the gun 6 and the dielectric sheet 4 and supplied with sawtooth waveform currents of line and frame frequency for deflecting the electron beam from the gun 6 in mutually perpendicular directions, so as to cause the beam to scan the dielectric sheet 4 in known manner.
  • the part of the envelope l to the right of the gun 6 is enclosed in a focussing solenoid ll coaxial with the envelope I and the signal plate 5 is connected to ground via a load impedance Hi from which a signal output can be obtained by means of a connection l9.
  • said electron beam from the gun 6 only traverses the deflecting fields produced by the coils 16, said beam scans the dielectric sheet 4 and periodically stabilises it at cathode potential, in the normal manner, setting up signals representative of said charge image across the impedance [8.
  • the solenoid I! focusses the scanning beam.
  • the gun should be symmetrical with respect to the axis of the envelope I.
  • the diameter of the envelope it is necessary for the diameter of the envelope to be at least twice the length of the diagonal of the area of the electrode 3 on which the light image of the object for transmission is projected.
  • a further focussing solenoid may be provided coaxial with the envelope and extending over the region of the gun 6, said further solenoid being arranged to produce an axial magnetic field-twice as strong as that produced by the solenoids l1 and 21 at the dielectric sheet 4 and at the electrode 3. This would also enable the diameter of the tub envelope l to be reduced.
  • a pick-up tube comprising a photoelectric cathode for converting a light image to an electron image, a
  • an electron beam source mounted in a direct line between said cathode and said target, deflecting means for setting up an electron-deflecting field between said source and said target for scanning an electron beam from said source over said target, and further deflecting means for setting up an oppositely directed electron-deflecting field between said cathode and said source proportioned to balance out deflections imparted by said first deflecting means to an electron image projected from said cathode to said target, whereby an electron image so projected is undefiected at said target.
  • a pick-up tube comprising a planar photoelectric cathode surface for converting a light image to an electron image, a planar target surface facing said cathode surface and parallel thereto, an electron gun mounted'in a direct line between said cathode surface and-said target surface for generating an electron beam directed at 'said'target surface, means for setting up a longitudinal magnetic field normal to said surfaces for focussing an electron image from said cathode surface and an electron beam from said gun normally onto said target surface, deflecting means for setting up an electron-deflecting field between said gun and said target surface for scanning an electron beam from saidgun over said target surface, and further deflecting means for setting up an equal and opposite electron-deflecting field between said cathode surface and said gun to balance out deflection imparted by said first deflecting means to an electron image projected from said cathode surface to said target surface, whereby an electron image so projected is focussed without deflection at said
  • a pick-up tube comprising at least a cathode and an anode of tubular form surrounding said cathode with its axis parallel to said photoelectric cathode surface and said target surface, said anode having an aperture to allow emergence of an electron beam directed at said target surface.
  • a pick-up tube comprising a planar photoelectric cathode surface for converting a light image to an electron image, an electrostatic charge storage target having a planar electron-image-receiving surface facing said photocathode surface and parallel thereto, an electron gun including at least a cathode and an anode mounted in a direct line between said photocathode surface and said target surface, means for setting up a longitudinal magnetic field normal to said surfaces for focussing an electron image from said photocathode surface and an electron beam from said gun normally onto said target surface, polarizing means for polarizing the electrodes of said tube to cause an electron image from said photocathode surface to be projected with high velocity on said target surface to form a positive charge image thereon by releasing secondary electrons and to cause an electron beam from said gun to approach said target surface with a low velocity, deflecting means for setting up an electron-deflecting field between said gun and said target surface for scanning an electron beam from
  • a tube comprising a planar photoelectric cathode surface for converting a light image to an electron image, a planar target surface facing said cathode surface and parallel thereto, an electron gun including electrodes polarized with different potentials and mounted in a direct line between said cathode surface and said target surface for generating an electron beam directed at said target surface, means for setting up a longitudinal magnetic field normal to said surfaces for focussing an electron image from said cathode surface and an electron beam from said gun normally onto said target surface, defleeting means for setting up an electron-deflecting field between said gun and said target surface for scanning an electron beam from said gun over said target surface, further deflecting means for setting up an equal and opposite electron-deflecting field between said cathode surface and said gun to balance out deflection imparted by said first deflecting means to an electron image projected from said cathode surface to said target surface, a screening electrode surrounding the electron path between said cathode surface and said gun, a further screening electrode surrounding the electron path
  • a pick-up tube in apparatus for generating electrical signals representive of a light image, said screening electrodes being of substantial resistance, and said polarizing means being arranged to maintain the ends of said screening electrodes nearer said gun at approximately equal potentials and the other ends of said electrodes at more negative potentials, with the latter end of the first-mentioned screening electrode most negative.
  • a planar photoelectric cathode surface for converting a light image to an electron image
  • an elec trostatic charge storage target including a planar electron image receiving surface facing said photocathode surface and parallel thereto and a conductive signal plate in capacitative association with said image-receiving surface, a load impedance connected to said signal plate
  • an electron gun including at least a cathode and an anode mounted in a direct line between said surfaces for generating an electron beam directed at said image-receiving surface
  • deflecting means for setting up an electron-deflecting field between said gun and said image-receiving surface for scanning an electron beam from said gun over said image-receiving surface, further deflecting means for setting up an equal and opposite electron-deflecting field between said photocatho
  • a pick-up tube further comprising a screening electrode surrounding the electron path between said photocathode surface and said gun, and a further screening electrode surrounding the electron path between said gun and said image-receiving surface, and means for pclarizing the ends of said screening electrodes nearer said gun at least as positively as said gun anode.
  • a pick-up tube comprising a planar photoelectric cathode surface, a planar target surface facing said cathode surface and parallel thereto, an electron gun mounted in a direct line between said cathode surface and said target surface, a focussing solenoid with its axis normal to said planar surfaces disposed on the photocathode side of said gun, a second focussing solenoid coaxial with said first solenoid disposed on the target side of said gun, and a third focussing solenoid surrounding said gun for increasing the focussing field for the region of said gun, said solenoids being dimensioned to focus an electron image from said cathode surface and an electron beam from said gun normally on said target surface, deflecting means for setting up an electron-deflecting field between said gun and said target surface for scanning an electron beam from said gun over said target surface, and a further deflecting means for setting up an equal and opposite electron-deflecting field between said cathode

Landscapes

  • Image-Pickup Tubes, Image-Amplification Tubes, And Storage Tubes (AREA)
US166369A 1949-06-11 1950-06-06 Television and like transmitting apparatus Expired - Lifetime US2596061A (en)

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Application Number Priority Date Filing Date Title
GB2596061X 1949-06-11

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US2596061A true US2596061A (en) 1952-05-06

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Application Number Title Priority Date Filing Date
US166369A Expired - Lifetime US2596061A (en) 1949-06-11 1950-06-06 Television and like transmitting apparatus

Country Status (3)

Country Link
US (1) US2596061A (de)
DE (1) DE825562C (de)
NL (1) NL153891B (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2678400A (en) * 1950-12-30 1954-05-11 Bell Telephone Labor Inc Photomultiplier utilizing bombardment induced conductivity
US2939026A (en) * 1957-12-23 1960-05-31 Gen Motors Corp Color television pick-up tube

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2189988A (en) * 1937-09-28 1940-02-13 Rca Corp Photoelectric device
US2203734A (en) * 1937-05-20 1940-06-11 Emi Ltd Electron lens
US2251992A (en) * 1938-06-15 1941-08-12 Rca Corp Picture transmitter tube
US2423124A (en) * 1943-01-30 1947-07-01 Bell Telephone Labor Inc Electro-optical device

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2203734A (en) * 1937-05-20 1940-06-11 Emi Ltd Electron lens
US2189988A (en) * 1937-09-28 1940-02-13 Rca Corp Photoelectric device
US2251992A (en) * 1938-06-15 1941-08-12 Rca Corp Picture transmitter tube
US2423124A (en) * 1943-01-30 1947-07-01 Bell Telephone Labor Inc Electro-optical device

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2678400A (en) * 1950-12-30 1954-05-11 Bell Telephone Labor Inc Photomultiplier utilizing bombardment induced conductivity
US2939026A (en) * 1957-12-23 1960-05-31 Gen Motors Corp Color television pick-up tube

Also Published As

Publication number Publication date
DE825562C (de) 1951-12-20
NL153891B (nl)

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