US2277246A - Electron discharge device - Google Patents

Electron discharge device Download PDF

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Publication number
US2277246A
US2277246A US238794A US23879438A US2277246A US 2277246 A US2277246 A US 2277246A US 238794 A US238794 A US 238794A US 23879438 A US23879438 A US 23879438A US 2277246 A US2277246 A US 2277246A
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US
United States
Prior art keywords
screen
mosaic
electron
electrons
image
Prior art date
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Expired - Lifetime
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US238794A
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English (en)
Inventor
Mcgee James Dwyer
Lubszynski Hans Gerhard
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
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EMI Ltd
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Publication date
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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
    • H01J31/40—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

  • Proposals have heretofore been made in which picture signals are generated by causing a con stant beam of electrons to scan a fine grid upon which and insulated therefrom is a photo-sensitive mosaic which on projection of an optical image thereon becomes charged positively owing to the emission of photo-electrons.
  • the primary electron beam is modulated owing to the electrostatic charges accumulated by the grid, the modulated beam being employed for generating picture signals.
  • a primary beam of electrons is caused to scan a mosaic screen and to release secondary electrons some of which serve to restore the elements of the mosaic screen to a datum value and thereby generate picture signals whilst the remaining secondary electrons are collected by an adjacent electrode.
  • an electronfdischarge device comprising an evacuated envelope, a grid structure comprising an a'pertured conducting element having on one side only a storage surface and so constructed and arranged that an optical or an electron image can be applied to said storage surface so as to produce difierences of potential between opposite sides of said grid structure and means for projecting onto the side of said structure opposite to that adapted to receive said image, an electron stream, the arrangement being such that in operation the stream of electrons which passes through the apertures in the grid structure becomes modulated by said potential differences.
  • an electron discharge device comprising an evacuated envelope, a grid structure comprising an apertured conducting element associated with a storage surface, and constructed and arranged so that an optical or an electron image can be applied to.
  • said storage surface so as to produce difierences of potential between opposite sides of said grid structure and means for projecting onto the side of the grid structure op- .posite to that adapted to receive said image, an electron stream which is such as to cause the release of secondary electrons from said grid structure, the arrangement being such that the stream of these secondary electrons which passes through the apertures in the grid structure becomes modulated by the said potential differences.
  • one side of the grid-like structure is provided with a layer of insulating material and upon the insulating material a multiplicity of mutually-insulated photosensitive elements are arranged.
  • a light image is projected onto the photo-sensitive surface of the grid-like structure causing the release of photo-electrons which serve to cause a potential difierence to be established between opposite sides of the grid-like structure.
  • the, grid-like struc-, ture may be provided on one side with a multiplicity of photo-voltaic cells. In this case also when an optical image is projected onto the photo-voltaic cells a difference of potential is established between opposite sides of the grid structure.
  • Other constructions of storage screens will be hereinafter described.
  • the secondary electron stream being thus modulated, the modulated stream being employed to produce, for example, picture signals suitable for television transmission.
  • the modulated electron stream may be projected onto a screen adapted to be rendered luminous under the impact of electrons so that a visible image can be produced.
  • the grid-like structure may be arranged to be scanned by a scanning beam of electrons to release said secondary electrons or, alternatively a high velocity spray of electrons may be continuously projected onto the grid-like structure to release the secondary electrons.
  • Figure 1 illustrates the invention as applied to a television transmitting tube
  • Figure 2 is an enlarged view of the grid structure employed in Figure 1
  • p Figures 3 to 7 illustrate modified forms of the invention.
  • the device comprises an evacuated envelope 3 having at one end a conventional electron gun comprising a cathode a screen 5 and a first anode 5, these elements being arranged in known manner. Focussing of cathode a is also effected by a second anode l which may be formed by silvering the required portion of the interior of the envelope 3.
  • the cathode ray beam is caused to scan a mosaic screen indicated generally at 8, and hereinafter more fully described, by the provision of electromagnetic deflecting coils 9 or electrostatic deflecting plates, in known manner.
  • the mosaic screen as shown in detail in Figure 2, comprises a grid structure such as a mesh of wire or other suitable material or a grille provided on the side opposite to the side.
  • the insulating material may be evaporated on the surface of the grid and may comprise lithium borate, sodium fluoride, an enamel or other suitable insulating
  • the mosaic elements may be formed.
  • photo-electrons will be liberated from the screen according to the intensity of theindividual areas of theprojected image so that a distribution of positive potentials will be accumulated on the mosaic screen corresponding to the distribution of light in the image, the photo-electrons released from the mosaic screen being absorbed by the electrode it.
  • the capacity of the mosaic elements to the metal of the screen may be made as small as possible, consistent with the capacity of each element to the screen remaining larger than the way the voltage to which an element will rise during one frame period under a given illumipossible, since the photo electric charge lost is independent of the capacity of the mosaic elements.
  • electrodes l3 and lt'areiskown conven-l iently as batteries IS, the electrode 13 being connected to the positive pole of its associated batscribed and applied to an amplifier, in known manner.
  • the electrode 13 is connected to the second anode 1.
  • the grid structure is connected to the negative poles of the bat.- If desired,- the electrode 13 may comprise the second anode 1, but where separate electrodes are employed for the second anode and the collecting electrode l3, the secand anode I will be maintained at a few volts negative with respect to the electrode l3.
  • the grid structure has a large shadow ratio, that is to say, the apertures in the screen may be only about 10 to 25 per cent of the total area of the screen.
  • Figure 3 of the drawings illustrates a modified form of the invention in which the secondary electron stream SI instead of being drawn to the electrode i3 is caused to be projected onto one or more target electrodes for the purpose of obtaining electron multiplication.
  • a lateral extension 3A of the envelope 3 in which is arranged in known manner a number of target electrodes 28, 24, 22, 23, and a final electrode 24 connected to the signal resistance it.
  • the secondary electron stream Si is caused to impinge on the target electrode Sill and thence in turn on the electrodes 2i, 22, 23 and 2%, these electrodes being maintained at increasing potentials and arranged so as to cause electron amplification by releasing a larger number of electrons compared with the incident electrons.
  • an electron image may be projected thereon.
  • FIG d of the drawings in which at the end of the envelope 3 facing the side of the screen 8 remote from the cathode 4 there is provided a photo-sensitive cathode 25 onto which an optical image is cast by the lens 92, this optical image causing the release of photo-electrons which areiocussed by an electrostatic lens comprising the electrodes 26, 2'7 and 28 onto the mosaic screen, which, in this case is substantially non-photosensitive.
  • the latter before projecting the electron image onto the mosaic screen 8 the latter is subjected to one or more stages of so called picture multiplication."
  • three grids 29, 30 and 39 are provided for amplifying the electron image in known manner, the electron image being focussed by a focussing coil 32.
  • the electrode 25 may be maintained at a positive potential of 100 volts the electrode Z'lat a positive potential of 250 volts and the electrode 28 at a positive potential of 200 volts.
  • the electron image is focussed onto the grid structure 8 and the secondary electrons which are released when the structure B is scanned are drawn to the electrode 21 which is the most positive electrode of the structure shown in Fig. 4.
  • the use of these additional stages of amplification is more feasible with.
  • the type of device illustrated in the drawings since the geometrical arrange-- ment of the electrodes is more convenient and since the focussing and scanning fields can be well separated.
  • restoration of the screen may be facilitated by spraying the mosaic elements with a constant subsidiary beam of electrons or by applying the mosaic' elements to high resistance dielectric.
  • the electrode I4 is omitted and the end of the envelope remote from the cathode 4 is provided with a screen 33 which is constructed so as to be rendered luminous under the impact of electrons.
  • the secondary electron stream S2 which is an electron image of the light image projected onto the mosaic screen is focussed by a coil 35 and accelerated by an electrode 35 to produce a visible image on thescreen 33.
  • the original optical image may be projected obliquely onto the mosaic screen through the lens 12.
  • Fig. 6 of the drawings illustrates the invention as applied to a so-called image dissector, the secondary electron image S2 being scanned over an apertured electrode it beyond which is arranged a collecting electrode 31.
  • the electron image is accelerated by electrode 35 focussed by a coil 3% and deflected over the electrode 36 by scanning coils 38.
  • the collecting electrode 3! may be associated with one or more stages of electron multiplication in known manner.
  • the secondary electron image S2 is accelerated by an accelerating electrode 35 and focussed by a coil 36 onto a substantially non-photo-sensitive mosaic screen 39 associated with a signal plate 39
  • the mosaic screen 39 acquires electrostatic charges which are periodically restored to a datum potential by scanning with a cathode ray beam generated by an electron gun indicated generally at to and contained within alateral tube M. It is clear that the mosaic 39 may be of the double sided type and scanned from the side opposite to that on which the electron image is formed. Also one or more stages of electron image multiplication may be provided between the grid structure 8 and screen 39.
  • the scanning beam of electrons or a spray of high speed electrons may be projected obliquely on the mosaic screen so as to reduce the possibility of the primary electron passing through the interstices of the mosaic screen.
  • this spray may be generated by providing one or more thermionic emitters in front of the mosaic screen.
  • the electrons which are modulated by the potential differences. between opposite sides of the mosaic screen are secondary electrons, it will be understood that if desired the electrons which become modulated may be primary electrons.
  • one or more there mionic emitters may be provided suitably disposed with respect to the mosaic screen and arranged to be projected towards the grid structure so as to form a virtual cathode in the plane of the grid structure.
  • the electrostatic charges or potential differences accumulated by said structure cause varying numbers of the electrons from the virtual cathode to be drawn through the interstices of the grid structure.
  • the grid structure may be scanned by a scanning beam of electrons which is not of a sufiicient velocity in the vicinity of the mosaic screen to release a substantial number of electrons.
  • a high velocity scanning beam may be used the beam being decelerated in the vicinity .of the mosaic screen.
  • This decelerating may be accomplished, for example, by maintaining the grid structure of the mosaic screen at substantially the same potential as the cathode of the electron gun and in providing adjacent to the grid structure an auxiliary grid maintained, for example, at the potential of the second anode l in Figure 1, that is to say, positive with respect to the grid structure.
  • the beam With such an arrangemaintained substantially in focus up to the auxiliary grid, the beam being then decelerated to a velocity which is such as not to cause the release of a substantial number of secondary electrons.
  • the present invention is not limited to applying to the mosaic screen a, composite electron image or .a composite light image.
  • the storage surface of the mosaic screen may be arranged to be scanned by a modulated electron beam so as to accumulate charges according to the modulation of the beam producing difierences of potential between opposite sides of the screen, this potential difference, in turn, causing modulation of the electron stream incident on the other side of the mosaic screen.
  • the optical image may be applied by scanning the storage surface of the screen with a modulated optical beam.
  • the modulated electron or optical beam may be applied obliquely to the grid structure.
  • the mosaic screen may, in these cases, be replaced by a mosaic screen composed of a multiplicity of photo-yoltaic cells.
  • the bells maybe made by depositing on the grid of the screen a layer of selenium or cuprous oxide'or other suitable material and on such layer .a transparent metal layer of moisaic formation is provided.
  • the storage surface of the screen may comprise a photo-conductive layer or a semiconducting layer, these layers being employed and disposed in the manners well known in the art.
  • the term storage layer is therefore defined in accordance with the present invention as comprising a photo-sensitive mosaic or a substantially non-photosensitive mosaic which may,
  • An electron scanning tube comprising a photoelectric means adapted to release a current image in response to the impingement of an optical image thereon, a double sided mosaic member having interstices therein, means interposed between said photoelectric means and said mosaic for multiplying the value of substantially each element of the current image, means for moving said multiplied image onto and in imon the side of said mosaic remote from said photoelectric means, means for directing said scanning beam onto said mosaic member whereby at -leest a portion thereof is modulated by the sage of the electron image from the photoelectric means to the mosaic member is substantially without impedance thereby.

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  • Cathode-Ray Tubes And Fluorescent Screens For Display (AREA)
US238794A 1937-11-04 1938-11-04 Electron discharge device Expired - Lifetime US2277246A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB30191/37A GB510696A (en) 1937-11-04 1937-11-04 Improvements in or relating to electron discharge devices

Publications (1)

Publication Number Publication Date
US2277246A true US2277246A (en) 1942-03-24

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US238794A Expired - Lifetime US2277246A (en) 1937-11-04 1938-11-04 Electron discharge device

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US (1) US2277246A (enrdf_load_stackoverflow)
FR (1) FR845626A (enrdf_load_stackoverflow)
GB (1) GB510696A (enrdf_load_stackoverflow)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2555424A (en) * 1948-03-09 1951-06-05 Sheldon Edward Emanuel Apparatus for fluoroscopy and radiography
US2645721A (en) * 1952-02-16 1953-07-14 Gen Electric Image intensification apparatus
US2727157A (en) * 1951-12-22 1955-12-13 Westinghouse Electric Corp Fluorescent tube
US2730708A (en) * 1952-10-28 1956-01-10 Gen Dynamics Corp Cathode ray apparatus
US2903596A (en) * 1956-01-18 1959-09-08 Rauland Corp Image transducers
US3040177A (en) * 1956-01-16 1962-06-19 Itt Electron discharge device
US3108202A (en) * 1954-11-17 1963-10-22 Itt Electron image-discharge device
US3191086A (en) * 1960-11-23 1965-06-22 Radames K H Gebel Secondary emission multiplier intensifier image orthicon

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE741899C (de) * 1940-05-29 1943-11-18 Fernseh Gmbh Bildsenderoehre mit einer als Steuergitter wirkenden gitterfoermigen Speicherelektrode
GB740442A (en) * 1950-10-06 1955-11-16 Pye Ltd Improvements in or relating to television apparatus

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2555424A (en) * 1948-03-09 1951-06-05 Sheldon Edward Emanuel Apparatus for fluoroscopy and radiography
US2727157A (en) * 1951-12-22 1955-12-13 Westinghouse Electric Corp Fluorescent tube
US2645721A (en) * 1952-02-16 1953-07-14 Gen Electric Image intensification apparatus
US2730708A (en) * 1952-10-28 1956-01-10 Gen Dynamics Corp Cathode ray apparatus
US3108202A (en) * 1954-11-17 1963-10-22 Itt Electron image-discharge device
US3040177A (en) * 1956-01-16 1962-06-19 Itt Electron discharge device
US2903596A (en) * 1956-01-18 1959-09-08 Rauland Corp Image transducers
US3191086A (en) * 1960-11-23 1965-06-22 Radames K H Gebel Secondary emission multiplier intensifier image orthicon

Also Published As

Publication number Publication date
GB510696A (en) 1939-08-04
FR845626A (enrdf_load_stackoverflow) 1939-08-29

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