EP0056556A1 - Tube analyseur à cible à accumulation - Google Patents

Tube analyseur à cible à accumulation Download PDF

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Publication number
EP0056556A1
EP0056556A1 EP81402097A EP81402097A EP0056556A1 EP 0056556 A1 EP0056556 A1 EP 0056556A1 EP 81402097 A EP81402097 A EP 81402097A EP 81402097 A EP81402097 A EP 81402097A EP 0056556 A1 EP0056556 A1 EP 0056556A1
Authority
EP
European Patent Office
Prior art keywords
tube
target
plates
lines
pick
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.)
Ceased
Application number
EP81402097A
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 EP0056556A1 publication Critical patent/EP0056556A1/fr
Ceased 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 electric charges as a function of the intensity of the light flux received and of the accumulation time.
  • 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 successive passages 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 previously scanned 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 two metal plates P and P 2 placed inside the tube and brought to different potentials so as to generate an electrostatic deflection of the electron beam scanning the target.
  • n analysis lines characterized in that the potential difference between the plates P l and P 2 is modulated by a signal whose frequency is at least equal to 2F (F: maximum frequency of the video signal delivered by the analyzer tube), and in that the plates are placed on either side of the electron beam so as to generate a deflection of the beam allowing scanning of the line spaces.
  • the analyzer tube shown in the figure is in the form of a glass cylinder V, a first end of optical glass carrying the photoconductive target.
  • the electronic gun whose beam is focused by a concentration coil B I 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 metallic layer is deposited a photoconductive material C.
  • the electrons generated by the electron gun are accelerated by an acceleration electrode G and focused on the photoconductive layer C by a focusing electrode G 2 , which makes it possible to obtain, together with the focusing coil B I, perfect concentration of the beam.
  • 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 next photosensitive layer, 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 enable the various internal elements of the analyzer tube to be energized.
  • This comprises an electron gun constituted by a cathode K 1 heated by the filament F 1 , and by a control electrode W.
  • the analyzer tube comprises two metal plates P 1 and P 2 placed inside of the tube between the concentration electrode G 2 and the acceleration electrode G 1 . These flat plates are placed horizontally on either side of the beam. When using the tubes in a 625 line television system, the plates P 1 and P 2 are brought to the same potential.
  • the plates P 1 and P 2 are brought to different potentials so as to generate an electrostatic deflection of the beam in the vertical direction, which allows a optimal target scanning.
  • This optimal target scan is obtained by modulating the potential difference between the plates P 1 and P 2 by a periodic signal S of frequency at least equal to twice the maximum frequency of the video signal produced and of amplitude Y, Y being the potential difference that it between plates P 1 and P 2 is necessary to obtain a vertical deflection of the beam which is equal to 1 ⁇ 2 line interval on the target.
  • the electron beam scans the target along curved lines whose shape corresponds to the signal S.
  • the unscanned areas of the target are reduced. This reduction is all the more important as the frequency of the signal S is high.
  • the potentials to which the plates P 1 and P 2 are carried are extremely low, of the order of a few volts.
  • the deflection sensitivity is extremely high because the plates are very close to the beam and the desired vertical deflection is low.
  • the analyzer tube is intended to be connected to a supply device provided with a switch making it possible to cut the supply to the plates P 1 and P 2 , so that the tube can be used for a television system 625 lines without loss of definition.
  • the position of the plates along the path of the beam is of little importance, but as one approaches the target, the amplitude of movement of the beam increases, which makes it necessary to separate the electrostatic deflection plates P 1 and P 2 in proportion, thereby reducing their sensitivity.
  • the vicinity of the electrostatic deflection plates and the target is not recommended because of the possible spurious couplings between these two elements.

Landscapes

  • Image-Pickup Tubes, Image-Amplification Tubes, And Storage Tubes (AREA)
  • Analysing Materials By The Use Of Radiation (AREA)
EP81402097A 1981-01-09 1981-12-31 Tube analyseur à cible à accumulation Ceased EP0056556A1 (fr)

Applications Claiming Priority (2)

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

Publications (1)

Publication Number Publication Date
EP0056556A1 true EP0056556A1 (fr) 1982-07-28

Family

ID=9253995

Family Applications (2)

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

Family Applications Before (1)

Application Number Title Priority Date Filing Date
EP19810402098 Withdrawn EP0056557A1 (fr) 1981-01-09 1981-12-31 Tube à prise de vues

Country Status (4)

Country Link
EP (2) EP0056557A1 (OSRAM)
JP (2) JPS57136750A (OSRAM)
CA (1) CA1186363A (OSRAM)
FR (1) FR2498009A1 (OSRAM)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA1224561A (en) * 1983-02-15 1987-07-21 Takashi Okada Television receiver

Citations (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
GB2020894A (en) * 1978-04-27 1979-11-21 Philips Nv Prevention of comet tail effects in image pick-up tube

Family Cites Families (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

Patent Citations (4)

* 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
GB2020894A (en) * 1978-04-27 1979-11-21 Philips Nv Prevention of comet tail effects in image pick-up tube
FR2424625A1 (fr) * 1978-04-27 1979-11-23 Philips Nv Tube cathodique

Also Published As

Publication number Publication date
CA1186363A (en) 1985-04-30
FR2498009B1 (OSRAM) 1983-07-18
JPS57136749A (en) 1982-08-23
JPS57136750A (en) 1982-08-23
FR2498009A1 (fr) 1982-07-16
EP0056557A1 (fr) 1982-07-28

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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

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Designated state(s): AT BE CH DE GB IT LU NL SE

17P Request for examination filed

Effective date: 19821118

18R Application refused

Effective date: 19850308

RIN1 Information on inventor provided before grant (corrected)

Inventor name: FAVREAU, MICHEL