EP0269472B1 - Bildaufnahmeröhre mit einer polarisierten Lichtquelle - Google Patents

Bildaufnahmeröhre mit einer polarisierten Lichtquelle Download PDF

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Publication number
EP0269472B1
EP0269472B1 EP87402278A EP87402278A EP0269472B1 EP 0269472 B1 EP0269472 B1 EP 0269472B1 EP 87402278 A EP87402278 A EP 87402278A EP 87402278 A EP87402278 A EP 87402278A EP 0269472 B1 EP0269472 B1 EP 0269472B1
Authority
EP
European Patent Office
Prior art keywords
tube
light
target
diodes
ring
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
EP87402278A
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English (en)
French (fr)
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EP0269472A1 (de
Inventor
Jean-Luc Ricaud
Bernard Plos
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
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Publication date
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Application filed by Thomson CSF SA filed Critical Thomson CSF SA
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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
    • H01J31/38—Tubes with photoconductive screen, e.g. vidicon

Definitions

  • the present invention relates to a picture tube provided with a light polarization device (see the first part of claim 1).
  • the persistence is the speed of response of the video signal to a change in the level of illumination.
  • the remanence depends on multiple factors. We can however consider that it behaves like an electric circuit RC, in which R is the resistance of the electron beam which sweeps the target and C is the charge storage capacity presented by the target.
  • the resistance R of the beam comes from the energy dispersion A E between the electrons of the beam. Indeed, the beam arrives at the target with a zero average speed since the cathode is at zero potential.
  • the beam reduces the potential of its surface to a slightly negative value - A E / 2. A small part of the beam is accepted by the target and the rest is returned to the cannon.
  • the resistance R therefore increases as the beam lowers the potential of the target towards - A E / 2.
  • the principle of light polarization is to raise the potential of the target to a slightly positive value under the effect of additional illumination.
  • This light polarization can be achieved, not at the level of the shooting tube and of the coil unit which generally surrounds it, but at the level of the camera of which the tube forms a part.
  • the light polarization device then becomes part of the optics of the camera and the light arrives on the front face of the photosensitive target of the tube, that is to say on the face of the target turned towards the outside of the tube. .
  • light polarization devices are known in which a light source external to the tube is used and where glass tubes transmit light inside the tube to the photosensitive target. This is the case, for example, in US Pat. No. 3,751,703.
  • Light polarization devices are also known in which the light source is also internal to the tube and is formed, for example, by the filament of the cathode of the tube electron gun.
  • a final possibility is to carry out the light polarization at the level of the assembly formed by the coil unit and the mechanical covering which surround the tube and without intervening in the tube itself.
  • the light polarization is carried out by illuminating the glass entry face of the tube, laterally, that is to say according to its thickness and perpendicular to the longitudinal axis of the tube.
  • This solution requires a coil block and a tube head (inlet face and neighboring parts) which are particularly suitable because the space available is small.
  • the present invention relates to a shooting tube provided with a light polarization device which belongs to the last category mentioned, that is to say of which the light polarization is carried out at the level of the coil unit.
  • the production of the tube and the camera is therefore absolutely not disturbed by the installation of this focusing device.
  • the invention does not require giving a particular shape to the vacuum enclosure of the tube, as is the case in US-A 4,465,927 (already mentioned), nor of incorporating into the tube a diffuser, such as is the case in US-A 3,925,699.
  • the present invention relates to a shooting tube provided with a light polarization device, said tube comprising a photosensitive target and a vacuum enclosure essentially made of glass, the light polarization device consisting of at least one ring of electro-diodes.
  • -luminescent positioned around the vacuum enclosure, characterized in that a diffuser is also positioned around the vacuum enclosure, the diffuser being closer to the photosensitive target than the crown of diodes.
  • Figure 1 shows a longitudinal sectional view of a shooting tube, with electron gun; the FEMDEM type, which means Focus Electro Magnetic Deflection and Electro Ma- g neti q level. This is the most common type of electron gun. It is common practice in this field to consider shooting tubes as consisting of two parts: the electron gun and the photosensitive target. The electron gun then designates the electron gun itself as well as the focusing and deflection devices of the electron beam.
  • the shooting tube represented in FIG. 1 comprises a glass envelope 1, provided at one of its ends with connection pins 2 and at the opposite end of an entry face 3 made of glass which bears on its internal face to the tube a photosensitive target 4.
  • the output signal Is of the tube is supplied by a connection connected to this target.
  • the vacuum vessel of this type of tube is generally almost entirely made of glass. This enclosure is symmetrical in revolution around the longitudinal axis of the tube. It is generally cylindrical. At connection pins 2, however, there are often a few ceramic parts.
  • the cathode and its filament 5 are shown inside the glass envelope 1 of the tube. G 4 .
  • One of the positions of the electron beam which scans the photosensitive target has also been shown in thin lines.
  • the light polarization device according to the prior art which is shown here is internal to the shooting tube.
  • the light source is formed by the filament of the cathode of the electron gun and glass tubes 14 transmit light inside the tube to the photosensitive target.
  • Figure 2 shows a longitudinal sectional view of a tube which differs from that of Figure 1 only by its light polarization device.
  • this light polarization device is placed around the vacuum enclosure 1 of the tube, between this vacuum enclosure and the coil unit.
  • This light polarization device is constituted by a ring of light-emitting diodes 10 and by a diffuser 11. The diffuser is closer to the photosensitive target 4 than the crown of diodes.
  • the vacuum chamber 1 of the tube is essentially made of glass and therefore allows the light coming from the ring of diodes to pass through.
  • the electrodes of the tube are generally made of a metallic material, opaque to light.
  • the invention exploits the fact that there are often interstices between the electrodes of sufficient size for the light coming from the ring of diodes to penetrate into the space internal to the electrodes and to strike the photosensitive target.
  • the invention also provides, if necessary, for producing orifices 12, of small dimensions, in one or more grids or electrodes, to allow the passage of light without disturbing the operation of the tube.
  • the holes made are small enough not to deform the equipotential surfaces in the part of the internal space of the tube used by the electron beam.
  • the light coming from the ring of diodes 10 penetrates inside the vacuum enclosure 1 through the interval between the field grid G 4 and the target 4, through the interval between the wall electrode G 3 and the field grid G 4 and by orifices 12 made in the wall electrode G ⁇ .
  • the wall electrode G 3 is very long, for example 90 mm. It is without problem to produce on this equipotential surface orifices of small dimensions, for example, slots arranged along the length of G 3 , of width 1 mm and distributed regularly over the circumference of G ⁇ , without disturbing the operation.
  • the light from the ring of diodes reaches the rear face of the photosensitive target 4 which is directed towards the electron gun of the tube, either directly or after reflection.
  • the reflection and light scattering properties of the gun parts can be improved.
  • the light-emitting diodes are positioned, regularly, around the circumference of the tube enclosure and in the same plane perpendicular to the longitudinal axis of the tube. They are oriented so as to send most of the light they emit into the diffuser.
  • the diffuser improves the uniformity of the illumination sent to the target by spreading the light from the diodes in all directions.
  • the diffuser also makes it possible to move the ring of diodes away from the target so as not to introduce noise on the electrical signal coming from the target. It can consist for example of PLEXIGLAS (registered trademark).
  • the integration sequence which corresponds to the acquisition of light information on the target during one or more scanning frames
  • the light polarization level written on the target increases with the number of integration frames, which varies the level of afterglow and causes a drift in the video signal level.
  • the tube has an external diameter of 25 mm and the coil block has an internal diameter of 33 mm, while it is d '' ordinary 29 mm.
  • FIG. 3 Another embodiment of the invention is shown in FIG. 3.
  • Figure 3 is a sectional view of a shooting tube with electron gun type FES-DEM, Electro Static Focus and Electro Magnetic Deviation.
  • Focusing is achieved by three electrodes Gs, G 6 and G 7 , which are either massive pieces of revolution as in FIG. 4, or deposited on the internal face of the vacuum chamber of the tube, then etched.
  • the coil unit only has one deflection coil 9.
  • the light polarization device consists, starting from the photosensitive target, of a diffuser 11, a ring of light-emitting diodes 10, then again a diffuser 11 and a ring of light-emitting diodes 10.
  • the light from the light polarization device can enter the vacuum enclosure of the tube through the space between the grid G 4 and the target 4, and through the space between the grids G 4 and G 7 , G 6 and G 7 and G 5 and Gs.
  • the advantage of using several rings of light-emitting diodes is that it is thus possible to increase the intensity of the illumination sent to the photosensitive target.
  • the use of several diode rings makes it possible to improve the uniformity of illumination of the target.
  • the diodes are positioned so as to modify the angle of incidence of the light coming from each diode on the target so as to obtain the desired result.
  • the invention therefore covers the embodiments in which there are, around the vacuum enclosure of the tube, several assemblies constituted by a diffuser and a ring of light-emitting diodes, the diffuser being closer to the photosensitive target than the diode crown.
  • a diffuser can be placed on the right of the ring of diodes, but the result obtained as regards the illumination of the photosensitive target is not very interesting because the light-emitting diodes emit essentially towards their front face, and little towards their connection tabs.
  • the diffuser it is a part of revolution, for example a cylinder, the various parameters of which can be modified so as to improve its performance.
  • a material diffusing in its mass but which does not absorb light too much is chosen.
  • plexiglass registered trademark
  • the surface condition of the diffuser is important. Thus, it is possible to etch certain zones of the diffuser to increase the light diffusion.
  • a mirror on the external surface of the diffuser in order to return the light towards the inside of the tube and thus increase the illumination.
  • FIG. 4 where the external surface of the diffuser which carries a mirror 15 is shown in thick lines.
  • the end of the diffuser which is closest to the target is conical.
  • the shape of the diffuser is studied so as to improve the uniformity of the illumination of the target because the light is partially reflected on the surface of the diffuser.
  • the term diffusor designates any part used to diffuse and return the light towards the interior of the tube and towards the target.
  • the diffuser is an initially liquid part, which fills the space between the enclosure of the tube and the coil block. It is for example a transparent resin which polymerizes under the effect of temperature and in which powder can be included to increase its diffusion property.
  • the powder of a material with an index higher than the index of the resin so that each grain reflects the light. Glass powder can be used, for example.
  • FIG. 6 represents a sectional view of a shooting tube with an electron gun of the FESDES, Electro Static Focus and Electro Static Deviation type.
  • the deflector consists of electrodes 13, deposited on the internal face of the tube and separated by insulating lines.
  • the focusing device is formed by the electrodes G 8 and G 9 which are shown in profile view while the rest of the tube is seen in section.
  • the light polarization device is constituted, as in the case of FIG. 2, by a diffuser 11 followed by a ring of light-emitting diodes 10.
  • the light from the diodes enters the vacuum enclosure of the tube through the space between the grid G 4 and the target 4, through the space between the grids G 4 and Ga, between the deflector 13 and the grid Ga , and between the deflector and the grid G 9 . Light also enters the tube through the gaps left between the four electrodes 13 of the deflector.

Landscapes

  • Image-Pickup Tubes, Image-Amplification Tubes, And Storage Tubes (AREA)

Claims (6)

1. Bildaufnahmeröhre mit einer Grundlichtquelle, mit einer lichtempfindlichen Auftreffplatte (4) und einer im wesentlichen aus Glas aufgebauten, evakuierten Hülle (1), wobei die Grundlichtquelle durch wenigstens einen Lumineszenzdiodenkranz (10) aufgebaut ist, der rings um die evakuierte Hülle (1) angeordnet ist, dadurch gekennzeichnet, daß die Grundlichtquelle ferner wenigstens einen Diffusor (11) umfaßt, der um die evakuierte Hülle (1) näher angeordnet ist, wobei sich der Diffusor (11) herum als der Diodenkranz (10) an der lichtempfindlichen Auftreffplatte (4) befindet.
2. Röhre gemäß Anspruch 1, dadurch gekennzeichnet, daß die Grundlichtquelle rings um die evakuierte Hülle (1) mehrere von aus einem Diffusor (11) und einem Lumineszenzdiodenkranz (10) aufgebauten Einheiten umfaßt, wobei sich jeder Diffusor (11) näher als der ihm zugeordnete Diodenkranz (10) an der lichtempfindlichen Auftreffplatte (4) befindet.
3. Röhre gemäß einem der Ansprüche 1 oder 2, dadurch gekennzeichnet, daß in wenigstens einem der Gitter oder der Elektroden der Röhre Öffnungen (12) verwirklicht sind, um den Durchgang des von den Lumineszenzdioden kommenden Lichts in das Innere der evakuierten Hülle zu erlauben.
4. Röhre gemäß einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, daß die äußere Oberfläche wenigstens eines der Diffusoren (11) einen Spiegel (15) umfaßt.
5. Röhre, gemäß einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, daß das Ende wenigstens eines der Diffusoren (11), das der Auftreffplatte (3) am nächsten ist, konisch ist.
6. Röhre, gemäß einem der Ansprüche 1 bis 5, dadurch gekennzeichnet, daß wenigstens einer der Diffusoren (11) aus lichtempfindlichem Harz, das ein dessen Diffusionseigenschaft erhöhendes Pulver enthält, aufgebaut ist.
EP87402278A 1986-10-17 1987-10-13 Bildaufnahmeröhre mit einer polarisierten Lichtquelle Expired - Lifetime EP0269472B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8614414A FR2605456B1 (fr) 1986-10-17 1986-10-17 Tube de prise de vue muni d'un dispositif de polarisation lumineuse
FR8614414 1986-10-17

Publications (2)

Publication Number Publication Date
EP0269472A1 EP0269472A1 (de) 1988-06-01
EP0269472B1 true EP0269472B1 (de) 1990-08-08

Family

ID=9339925

Family Applications (1)

Application Number Title Priority Date Filing Date
EP87402278A Expired - Lifetime EP0269472B1 (de) 1986-10-17 1987-10-13 Bildaufnahmeröhre mit einer polarisierten Lichtquelle

Country Status (6)

Country Link
US (1) US4823045A (de)
EP (1) EP0269472B1 (de)
JP (1) JPS63158734A (de)
DE (1) DE3764244D1 (de)
FR (1) FR2605456B1 (de)
MA (1) MA21048A1 (de)

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3628076A (en) * 1968-12-24 1971-12-14 Philips Corp Photoconductive screen deriving light thorugh light conductor from tube filament
GB1299288A (en) * 1970-07-30 1972-12-13 English Electric Valve Co Ltd Improvements in or relating to pick-up tubes
JPS5913827B2 (ja) * 1976-07-02 1984-04-02 株式会社日立製作所 撮像装置
JPS534418A (en) * 1976-07-02 1978-01-17 Hitachi Ltd Pick up unit
US4259609A (en) * 1978-10-20 1981-03-31 Rca Corp. Pick-up tube having light controllable furcated light pipes
GB2093265B (en) * 1981-02-12 1985-02-06 English Electric Valve Co Ltd Light-blassed image pick-up tubes

Also Published As

Publication number Publication date
FR2605456B1 (fr) 1988-12-09
JPS63158734A (ja) 1988-07-01
DE3764244D1 (de) 1990-09-13
US4823045A (en) 1989-04-18
FR2605456A1 (fr) 1988-04-22
MA21048A1 (fr) 1988-04-01
EP0269472A1 (de) 1988-06-01

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