EP0056557A1 - Tube à prise de vues - Google Patents

Tube à prise de vues Download PDF

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Publication number
EP0056557A1
EP0056557A1 EP19810402098 EP81402098A EP0056557A1 EP 0056557 A1 EP0056557 A1 EP 0056557A1 EP 19810402098 EP19810402098 EP 19810402098 EP 81402098 A EP81402098 A EP 81402098A EP 0056557 A1 EP0056557 A1 EP 0056557A1
Authority
EP
European Patent Office
Prior art keywords
cathode
target
main
lines
filament
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.)
Withdrawn
Application number
EP19810402098
Other languages
German (de)
English (en)
French (fr)
Inventor
Michel Favreau
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.)
Thales SA
Original Assignee
Thomson CSF SA
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 Thomson CSF SA filed Critical Thomson CSF SA
Publication of EP0056557A1 publication Critical patent/EP0056557A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • 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
    • H01J29/70—Arrangements for deflecting ray or beam
    • H01J29/72—Arrangements for deflecting ray or beam along one straight line or along two perpendicular straight lines
    • H01J29/74—Deflecting by electric fields only
    • 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
    • H01J31/38—Tubes with photoconductive screen, e.g. vidicon

Definitions

  • the present invention relates to analyzer tubes for television cameras, provided with a photoconductive accumulation target storing an amount of electrical charges as a function of the intensity of the light flux received and of the accumulation time, and cameras comprising such tubes.
  • the optical image is focused on the photoconductive layer.
  • the conductivity of each point of the latter varies with the light intensity received, the positive charges due to the positive potential applied to the signal plate diffuse more or less quickly through the layer, so that one obtains on the rear face of the target a relief of positive charges constituting an electric image, faithful reflection of the projected optical image.
  • each point of the target captures the quantity of electrons necessary to reduce its potential to that of the cathode of the gun.
  • the various currents corresponding to the electron contributions of the beam, which cancel the positive charges of the target cross the load resistance placed in the circuit of the signal plate, and create at its terminals variations of potential which constitute the video signal .
  • the electron beam generated by the cathode of the tube is intended to scan the target along main lines of analysis. Between two passages successive of the beam, the illuminated elements of the photoconductive layer of the target gradually take up the power supply potential of the target, this is called accumulation. This positive potential is higher the higher the illumination and the longer the time between two successive passages of the beam.
  • Flickering phenomena are linked to the localized potential difference thus created between the scanned lines and the unscanned areas. Indeed, at the time of its "landing" on the target, the electron beam, instead of scanning again the main lines previously analyzed, is deflected towards the contiguous areas not scanned previously and which are more positively polarized than the lines main. A discharge then takes place, generating an important parasitic signal which is most often periodic.
  • One solution is to vary the focal length of the electrostatic lenses which allow the electron beam to be concentrated. This means increases the size of the electron beam on the target, but in this case the horizontal resolution (in the direction of the main lines) is reduced.
  • Another solution consists in modulating the scanning of the target, either by modulating the vertical scanning signal by a periodic signal of amplitude equal to half a line interval and of frequency at least equal to twice the maximum frequency, or using complementary deflection coils.
  • This method is known under the name of "wobulation of the analysis beam” and has already been implemented for the reproduction of images on receiving tubes.
  • magnetic "wobulation” is difficult to carry out on an analyzer tube, because many shields protect the tube against the actions of the earth's field.
  • the magnetic field which produces the vertical deflection is difficult to modulate by a high frequency signal, because it would be necessary to use coils having too large self-induction coefficients.
  • the use of additional coils is difficult because of the problem of coupling with the main coils.
  • the present invention relates to an analyzer tube avoiding the flickering phenomenon and the aforementioned drawbacks, by controlled modification of the height of the analysis brush at the level of the target scanned using simple means.
  • a photoconductive target analyzer tube comprising a main cathode heated by a main filament and allowing scanning of the target by an electron beam along n lines of analysis (n positive integer), is characterized in that 'It comprises an additional cathode heated by an additional filament and juxtaposed with the main cathode so as to allow the scanning of the line spaces.
  • the analyzer tube shown in the single figure is in the form of a glass cylinder V, a first end of optical glass carrying the photoconductive target.
  • the electronic cannon whose beam is focused by a coil of concentration B 1 arranged around the glass cylinder V, and deflected by deflection coils B 2 and B 3 arranged around the glass cylinder V.
  • the target is formed by a metallic layer thin enough to be transparent constituting a signal plate P. On this metal layer is deposited a photoconductive material C.
  • the electrons generated by the electron gun are accelerated by an acceleration electrode G 1 and focused on the layer, photoconductive C by a focusing electrode G 2 , which allows d 'Obtain together with the focusing coil B 1 a perfect beam concentration.
  • a grid G 3 with fine meshes is placed at a short distance from the photoconductive layer C so as to cause a slowing down of the electrons between this grid G 3 and the sensitive surface C, so that the electron beam strikes the photosensitive layer according to one of its normal.
  • a cylindrical base E placed at the second end of the glass cylinder V is provided with four connection terminals A 1 , A 2 , A 3 , A 4 which make it possible to energize the various internal elements of the analyzer tube.
  • the electron gun of this analyzer tube comprises a main cathode K 1 heated by a main filament F 1 , and a control grid W (called "wehnelt” in English literature).
  • the main cathode K 1 emits an electron beam which is used to scan the target along n main lines of analysis.
  • the electron gun also has an additional cathode K 2 heated by an additional filament F 2 .
  • This additional cathode K 2 is juxtaposed with the main cathode K 1 so as to allow the scanning of the line spaces (that is to say areas not scanned by the beam coming from the main cathode K 1 ).
  • the Flet F 2 filaments are intended to be connected via the connection terminals to a supply device controlled by a two-position switch.
  • the analyzer tube thus formed can be used either for a 625 line television system, or for a 312.5 line television system.
  • a 625 line television system it will suffice to use only the cathode K 1 by placing the switch in its first position; for a television system with 312.5 lines, it will suffice to use the two cathodes K 1 and K 2 by placing the switch in its second position, so as to eliminate flickering phenomena.

Landscapes

  • Image-Pickup Tubes, Image-Amplification Tubes, And Storage Tubes (AREA)
  • Analysing Materials By The Use Of Radiation (AREA)
EP19810402098 1981-01-09 1981-12-31 Tube à prise de vues Withdrawn EP0056557A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8100308A FR2498009A1 (fr) 1981-01-09 1981-01-09 Tube analyseur a cible a accumulation et camera comportant un tel tube
FR8100308 1981-01-09

Publications (1)

Publication Number Publication Date
EP0056557A1 true EP0056557A1 (fr) 1982-07-28

Family

ID=9253995

Family Applications (2)

Application Number Title Priority Date Filing Date
EP81402097A Ceased EP0056556A1 (fr) 1981-01-09 1981-12-31 Tube analyseur à cible à accumulation
EP19810402098 Withdrawn EP0056557A1 (fr) 1981-01-09 1981-12-31 Tube à prise de vues

Family Applications Before (1)

Application Number Title Priority Date Filing Date
EP81402097A Ceased EP0056556A1 (fr) 1981-01-09 1981-12-31 Tube analyseur à cible à accumulation

Country Status (4)

Country Link
EP (2) EP0056556A1 (ja)
JP (2) JPS57136749A (ja)
CA (1) CA1186363A (ja)
FR (1) FR2498009A1 (ja)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2135818A (en) * 1983-02-15 1984-09-05 Sony Corp Television receivers

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1373561A (fr) * 1962-11-06 1964-09-25 English Electric Valve Co Ltd Tubes de caméras pour télévision et analogues
US3221208A (en) * 1961-08-01 1965-11-30 Hitachi Ltd Dual-beam, short-line storage-type camera tube
FR1535261A (fr) * 1966-08-29 1968-08-02 Rca Corp Dispositif capteur pour tube à rayons cathodiques

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3040205A (en) * 1960-05-31 1962-06-19 Harold R Walker Electrostatic vidicon
DE1299310B (de) * 1968-04-02 1969-07-17 Fernseh Gmbh Verfahren zur Verringerung des Nachziehens von speichernden Bildaufnahmeroehren vom Photoleitfaehigkeitstyp und Anordnung zur Ausuebung des Verfahrens
NL7804518A (nl) * 1978-04-27 1979-10-30 Philips Nv Kathodestraalbuis.

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3221208A (en) * 1961-08-01 1965-11-30 Hitachi Ltd Dual-beam, short-line storage-type camera tube
FR1373561A (fr) * 1962-11-06 1964-09-25 English Electric Valve Co Ltd Tubes de caméras pour télévision et analogues
FR1535261A (fr) * 1966-08-29 1968-08-02 Rca Corp Dispositif capteur pour tube à rayons cathodiques

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2135818A (en) * 1983-02-15 1984-09-05 Sony Corp Television receivers

Also Published As

Publication number Publication date
CA1186363A (en) 1985-04-30
FR2498009B1 (ja) 1983-07-18
EP0056556A1 (fr) 1982-07-28
FR2498009A1 (fr) 1982-07-16
JPS57136749A (en) 1982-08-23
JPS57136750A (en) 1982-08-23

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Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

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AK Designated contracting states

Designated state(s): DE GB NL

17P Request for examination filed

Effective date: 19821118

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION HAS BEEN WITHDRAWN

18W Application withdrawn

Withdrawal date: 19840723

RIN1 Information on inventor provided before grant (corrected)

Inventor name: FAVREAU, MICHEL