US3110841A - Television and like camera tubes - Google Patents

Television and like camera tubes Download PDF

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Publication number
US3110841A
US3110841A US4285A US428560A US3110841A US 3110841 A US3110841 A US 3110841A US 4285 A US4285 A US 4285A US 428560 A US428560 A US 428560A US 3110841 A US3110841 A US 3110841A
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US
United States
Prior art keywords
electrode
mesh
grid
electrons
potential
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
US4285A
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English (en)
Inventor
Callick Eric Brian Butler
Firmin Jervois Campbell
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.)
Teledyne UK Ltd
Original Assignee
English Electric Valve Co 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 English Electric Valve Co Ltd filed Critical English Electric Valve Co Ltd
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Publication of US3110841A publication Critical patent/US3110841A/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
    • H01J31/40—Image pick-up tubes having an input of visible light and electric output with electron ray scanning the image screen having grid-like image screen through which the electron ray passes and by which the ray is influenced before striking the output electrode, i.e. having "triode action"

Definitions

  • the object of the invention is to provide television and like camera tubes which shall be of relatively simple and inexpensive construction and good sensitivity and which shall not impose requirements of extreme precision in manufacture.
  • a further object of the invention is to provide improved camera tubes which will be almost if not quite free of so-called dark current effect and which will in fact give maximum output current for white parts of a subject for transmission and very low (approaching zero) output current for black parts thereof.
  • a television or like camera tube includes a mesh electrode with a photo-sensitive layer on one side thereof positioned to receive optical images of a subject of transmission, an electron gun adapted to scan said side of said mesh electrode with an electron beam, an additional electrode positioned to receive beam electrons which have passed through said mesh electrode and means including a second additional electrode for receiving beam electrons which have been turned back by said mesh electrode.
  • the electrode positioned to receive beam electrons which have passed through the mesh may be the actual output electrode of the tube but preferably it is an accelerating grid for an electron multiplier system of dynodes leading to an output electrode and adapted to supply an increased electron flow thereto.
  • the photo-sensitive layer may be a photo-emissive insulating layer or a photo-conductive layer.
  • the operating potentials on the various electrodes are made such that the number of 'beam electrons passed by said mesh electrode at any particular small area of its surface depends on the light content of the portion of the optical image on said small area.
  • the means including the second additional electrode for receiving beam electrons turned back by the mesh electrode is a grid or mesh (to which, in use, a positive potential is applied) which is adjacent said mesh electrode on the electron gun side thereof and through which the beam passes to reach said mesh electrode and preferably a first additional electrode in the form of a grid or mesh (to which, in use, a higher positive potential is applied) is provided adjacent said mesh electrode on the side thereof remote from the electron gun and between said mesh electrode and the electrode for receiving beam electrons which have passed through said mesh electrode.
  • the camera tube therein represented has an evacuated envelope 1 with a window 2 at one end.
  • a fine metal mesh or apertured screen 3 Transverse with respect to the envelope is a fine metal mesh or apertured screen 3 which is represented by a broken line and on one side of which is a photo-sensitive layer 4 represented by a second broken line.
  • the layer 4 may be either a photo-emissive insulating layer or a photo-conductive layer.
  • Optical images of a subject for transmission are focused by any convenient means represented by the lens 5 through a window 2 at one end of the tube envelope on to the photosensitive layer 4 0n the mesh 3.
  • Adjacent the structure 3 4 and on the window side thereof' is an additional electrode in the form of a grid or mesh 6 and also adjacent the structure 3 4 and on the opposite side thereof is another additonal electrode in the form of a grid or mesh '7.
  • An electron gun 8 is provided to produce an electron beam to scan the photo-sensitive surface 4 on the mesh 3.
  • Behind the mesh 3 and on the other side of the grid 7 therefrom is an electron multiplier system represented conventionally by a sequence of electron multiplying electrodes or dynodes 9 terminating in an output electrode 10.
  • Any convenient scanning arrangement indicated by scanning coil systems 11 and 12 in the ligure is provided for causing the beam from the gun 8 passing through the grid 6 to scan the structure 3-4, electrons of this beam which have passed through said structure and through the grid 7 being caused to be incident upon the list dynode in the sequence of dynodes.
  • a positive voltage of, for example, l0 volts is applied to the mesh 3.
  • the electron beam from the gun 8 is then caused to scan the surface 4 thus reducing that surface to zero (i.e. gun cathode) potential.
  • the mesh 3 is then connected to earth which brings the photo-sensitive surface 4 to a negative potential of about -10 volts (again relative to gun cathode). This is the setting-up process which brings the tube into condition for use and the means for effecting it are conventionally indicated by the switch 13, though it will be understood, of course, that in practice, setting-up will probably be effected by a suitable pulsed waveform.
  • this grid is to collect returned electrons While the purpose of the grid 7 is to draw electrons through the mesh at points where the mesh potential is above cut-off value. Thus the electron ow through the mesh at any point will depend on the light or shade of the image at that point. Electrons passing through the mesh and the grid 7 impinge on the dynode succession each electrode 9 of which produces an electron mutiplication effect, the final amplified electron stream falling upon an output electrode 10. Picture signals are taken olf through condenser 14 from across an output resistance 15. The electron beam is conventionally represented by the chain line 16.
  • the tube above described is relatively simple, of good sensitivity and does not impose excessively stringent requirements as to precision of manufacture-for example, the optical system represented by the external lens 5 need not be exactly co-axial with the gun 8. Furthermore, it will be seen that little or no beam current will reach the electron multiplier section of the tube at points on the structure 3 4 corresponding to dark or black areas of the picture so that there is little or no dark current effect.
  • the electron multiplier included in the tube illustrated is not a theoretical necessity and the electron beam passing through the mesh 3 could be arranged to be incident directly on an output electrode, for example, a plate electrode parallel to and behind the grid 7, i.e. on the side of the grid 7 remote from the gun. However, the illustrated arrangement is preferred.
  • a television camera tube arrangement comprising a tube having a mesh electrode with a photosensitive layer on one side thereof positioned to receive optical images, an electron gun including a cathode adapted to project an electron beam in a direction perpendicular to the surface of said mesh electrode to scan said layer, an electrode positioned to receive beam electrons which have passed through said mesh electrode, a pair of grid electrode means positioned adjacent and parallel to said mesh electrode, one on each side thereof, means for stabilizing the potential of said photosensitive layer at a predetermined value, a source of D.C.
  • a tube as claimed in claim 1 wherein the electrode positioned to receive beam electrons which have passed through the mesh is the first electrode of an electron multiplier system of dynodes leading to an output electrode.

Landscapes

  • Image-Pickup Tubes, Image-Amplification Tubes, And Storage Tubes (AREA)
  • Common Detailed Techniques For Electron Tubes Or Discharge Tubes (AREA)
US4285A 1959-02-02 1960-01-25 Television and like camera tubes Expired - Lifetime US3110841A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB3110841X 1959-02-02

Publications (1)

Publication Number Publication Date
US3110841A true US3110841A (en) 1963-11-12

Family

ID=10921920

Family Applications (1)

Application Number Title Priority Date Filing Date
US4285A Expired - Lifetime US3110841A (en) 1959-02-02 1960-01-25 Television and like camera tubes

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US (1) US3110841A (en))
DE (1) DE1141667B (en))
NL (1) NL247913A (en))

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2256300A (en) * 1936-11-06 1941-09-16 Int Standard Electric Corp Device applicable mainly to television
US2618758A (en) * 1948-07-27 1952-11-18 John M Cage Television camera tube
US2816954A (en) * 1952-10-23 1957-12-17 David A Huffman Infra-red television camera

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE888414C (de) * 1939-02-22 1953-08-31 Telefunken Gmbh Speichernde Bildfaengerroehre

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2256300A (en) * 1936-11-06 1941-09-16 Int Standard Electric Corp Device applicable mainly to television
US2618758A (en) * 1948-07-27 1952-11-18 John M Cage Television camera tube
US2816954A (en) * 1952-10-23 1957-12-17 David A Huffman Infra-red television camera

Also Published As

Publication number Publication date
NL247913A (en))
DE1141667B (de) 1962-12-27

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