EP0143714A1 - Lumineszenter Schirm und Verfahren zur Herstellung desselben - Google Patents

Lumineszenter Schirm und Verfahren zur Herstellung desselben Download PDF

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Publication number
EP0143714A1
EP0143714A1 EP84402396A EP84402396A EP0143714A1 EP 0143714 A1 EP0143714 A1 EP 0143714A1 EP 84402396 A EP84402396 A EP 84402396A EP 84402396 A EP84402396 A EP 84402396A EP 0143714 A1 EP0143714 A1 EP 0143714A1
Authority
EP
European Patent Office
Prior art keywords
grains
layer
screen
blocks
substrate
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.)
Granted
Application number
EP84402396A
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English (en)
French (fr)
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EP0143714B1 (de
Inventor
Daniel Gibilini
Jean-Pierre Galves
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 EP0143714A1 publication Critical patent/EP0143714A1/de
Application granted granted Critical
Publication of EP0143714B1 publication Critical patent/EP0143714B1/de
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    • 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
    • H01J29/02—Electrodes; Screens; Mounting, supporting, spacing or insulating thereof
    • H01J29/10—Screens on or from which an image or pattern is formed, picked up, converted or stored
    • H01J29/18—Luminescent screens
    • H01J29/28—Luminescent screens with protective, conductive or reflective layers
    • 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
    • H01J29/02—Electrodes; Screens; Mounting, supporting, spacing or insulating thereof
    • H01J29/10—Screens on or from which an image or pattern is formed, picked up, converted or stored
    • H01J29/18—Luminescent screens
    • H01J29/185—Luminescent screens measures against halo-phenomena

Definitions

  • the present invention relates to luminescent screens. It also relates to a method of manufacturing these luminescent screens.
  • the screens in question in the present invention comprise, in particular, several layers of luminescent material, in the form of grains, which are deposited on a transparent support; generally, it is a glass substrate, with parallel faces.
  • the luminescent material can be catholuminescent, that is to say that it becomes luminescent when it is subjected to the bombardment of an electron beam.
  • Such cathodoluminescent screens are used for example in cathode ray tubes, radiological image intensifiers.
  • the luminescent material can also be, for example, electroluminescent, i.e. it becomes luminescent under the action of an electric field
  • FIG. 1 there is shown schematically an IIR.
  • This tube has a primary screen which converts the X photons it receives into light photons, then into photo-electrons.
  • Electronic optics which are not shown, ensure the focusing of the electronic trajectories and the energy gain of the electrons.
  • a cathodoluminescent secondary screen ensures the conversion of electrons into visible photons. It is this secondary screen that will be discussed later.
  • FIGS. 2a and b an embodiment of the secondary screen in FIG. 1 has been seen in cross section.
  • the cathodoluminophore body used can be, for example, zinc sulfide doped with silver.
  • the diameter of the grains can vary, for example, between 1 and 3 microns, depending on the resolution sought.
  • the thickness of the glass substrate 1 is for example, from 1 to 3 mm approximately, while the thickness of luminescent material is approximately 10 microns.
  • FIG. 4 there is shown a sectional view of the luminescent screen, the thickness of the metallic film 3 and of the layers of luminescent material 2 has been greatly increased in FIG. 4 relative to the thickness of the substrate 1.
  • FIG. 5 the substrate is represented seen in section as well as the path of the light rays, and in particular of those which undergo a total reflection.
  • FIG. 5 also shows the variations in intensity I observed and corresponding to the central spot and to the different halos.
  • the present invention makes it possible to solve this problem and makes it possible, as will be explained in detail below, to obtain an optimized contrast screen without the gain dropping too much and without the resolution being reduced.
  • the present invention as characterized in claim 1, relates to a luminescent screen comprising in particular several layers of luminescent material in the form of grains, deposited on a transparent support, characterized by the presence of blocks, arranged between the grains of the first layer of material and the support, these blocks having a cross section at most equal to the cross section of the grains and having an optical transparency of less than 1.
  • a first solution consists in using a mass-tinted glass substrate whose optical transparency T 1 is less than 1.
  • the gain is the ratio between the light power emitted by the screen and the electric power it receives.
  • a second solution consists in rejecting the halos outside the useful area of the screen by increasing the thickness e of the screen. If we call ⁇ the diameter of the useful area delimited by a cover 4 in FIG. 7, it is clear that for all the halos to be located outside this area it suffices that the following relation is verified: 2e » ⁇
  • FIG. 8 illustrates the solution where this intermediate layer is metallic, of transparency T 2 .
  • An additional disadvantage of the metallic intermediate layer is that for example in the case of the intensity ray A in FIG. 8, there is transmission to the observer of a ray of intensity AT 2 and reflection on the metal layer of a radius of intensity A. (IT 2 ) which is finally transmitted to the observer but contributes to the decrease in the resolution of the screen, because it increases the diameter of the central spot corresponding to the impact of the electron beam.
  • FIG. 9 shows the reflection coefficient R of this layer as a function of the angle of incidence 0. When the angle of incidence is less than the total reflection angle O o , the reflection coefficient is substantially zero. This reflection coefficient becomes substantially equal to 1 for an angle of incidence greater than O o .
  • this layer prevents the exit to the observer of the rays which contribute to the halos.
  • the ray B whose angle of incidence equal O o , propagates laterally in the substrate without going out towards the observer. This ray B undergoes successive total reflections on the two faces of the substrate .
  • This intermediate layer has the disadvantage of causing a drop in resolution by the same phenomenon as that explained for the metallic layer. In addition, it is difficult and expensive to carry out.
  • FIG 11 there is shown in section an embodiment of a screen according to the invention.
  • blocks 6 having a cross section at most equal to the cross section of the grains and having an optical transparency T3 less than 1.
  • the light rays generated in the grains of the first layer but which emerge from these grains in a place other than the point of contact of the grain with the substrate may have to pass through a block 6 as shown in FIG. 11. a BT 3 intensity radius for example. It may also happen that these spokes do not have to cross paving stones.
  • Some of these rays do not undergo total reflection and exit, for example with an intensity BT 3 . Others undergo a total reflection, for example the radius of intensity CT 3 . Such a ray can come out of the substrate with a CT 3 3 intensity after being reflected on another grain and having crossed twice the block supporting this grain.
  • FIG. 6 which relates to the use of a tinted glass support, it can be seen that the rays generated in grains other than those of the first layer are not attenuated.
  • G 3 and C 3 denote the gain and the contrast of the screen according to the invention.
  • the calculation also shows that, assuming a minimum gain is respected, for a screen according to the invention and for a screen with a tinted glass support, the invention allows lower transparency. As when the transparency is the same, the contrast is better with the blocks according to the invention, it is clear that the invention makes it possible, while respecting a minimum gain, to further improve the contrast.
  • Another advantage of the invention is that the presence of blocks does not decrease the resolution, whereas this occurs when there is an intermediate layer between the glass substrate and the first layer of grains.
  • a thin layer 7 of material having the desired transparency is deposited on the substrate 1 - see FIG. 12a.
  • This deposition can be carried out, for example, by vacuum evaporation or by electrochemical means.
  • This layer 7 may for example have a thickness of a few hundred angstroms. ''
  • the material used can be any absorbent material, for example metal or carbon.
  • a first layer of luminescent material is deposited on layer 7.
  • layer 7 By conventional techniques, well-individualized grains are obtained - see Figure 12b.
  • a selective plasma attack on layer 7 is carried out using the grains of the first layer as a mask. This attack is symbolized by vertical arrows in Figure 12b.
  • attack is carried out with Argon ions for example.
  • a carbon layer can be used, for example by evaporation, by using a plasma comprising a hydrocarbon gas or by depositing a single layer of carbon particles with a diameter less than 0.1 microns for example, while the grains of luminescent material have a much larger diameter, of about ten microns for example.
  • an attack is carried out by oxygen plasma.
  • Figure 12c shows the result of this attack. This attack must be stopped on the surface of the substrate in order not to frost it, and thus not to deteriorate the resolution of the screen.
  • FIGS. 13 a, b, c a grain of luminescent material 2 and its block 6 have been shown.
  • the block has a cross section substantially equal to that of the grain
  • the block has a significantly decreasing section, less than that of the grain. It is clear that the more the section of the block is limited to the point of contact between the grain and the block, the more the efficiency and the contrast are improved. Thus, the attenuation of intensity due to the pavement is limited to the rays created at the point of grain-pavement contact.
  • the production method described makes it possible to obtain blocks of section at most equal to the section of the grains.
  • the material used to make the pavers must have good adhesion with the glass of the substrate. It must also be able to be well attacked by plasma while the luminescent material of the grains and the glass are not very attacked.
  • a metal such as silver or gold for example, or carbon.
  • a layer such as that cited above and described in European patent application No. 0.018. 666: This increases gain and efficiency, without reducing the screen resolution. In this case it is also necessary to use for the selective attack, a plasma which very preferably attacks this layer while the luminescent material of the grains and the support are not very attacked.

Landscapes

  • Cathode-Ray Tubes And Fluorescent Screens For Display (AREA)
  • Image-Pickup Tubes, Image-Amplification Tubes, And Storage Tubes (AREA)
  • Formation Of Various Coating Films On Cathode Ray Tubes And Lamps (AREA)
EP84402396A 1983-11-29 1984-11-23 Lumineszenter Schirm und Verfahren zur Herstellung desselben Expired EP0143714B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8319019A FR2555806B1 (fr) 1983-11-29 1983-11-29 Ecran luminescent et procede de fabrication d'un tel ecran
FR8319019 1983-11-29

Publications (2)

Publication Number Publication Date
EP0143714A1 true EP0143714A1 (de) 1985-06-05
EP0143714B1 EP0143714B1 (de) 1987-01-21

Family

ID=9294638

Family Applications (1)

Application Number Title Priority Date Filing Date
EP84402396A Expired EP0143714B1 (de) 1983-11-29 1984-11-23 Lumineszenter Schirm und Verfahren zur Herstellung desselben

Country Status (5)

Country Link
US (1) US4661742A (de)
EP (1) EP0143714B1 (de)
JP (1) JPS60133638A (de)
DE (1) DE3462199D1 (de)
FR (1) FR2555806B1 (de)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5137598A (en) * 1990-06-04 1992-08-11 Itt Corporation Thin film phosphor screen structure

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0018666A1 (de) * 1979-05-07 1980-11-12 Optical Coating Laboratory, Inc. Bildschirmaufbau für Kathodenstrahlröhren zur Unterdrückung der Lichthofbildung und Verfahren

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2599739A (en) * 1950-04-12 1952-06-10 American Optical Corp Cathode-ray tube
NL6905835A (de) * 1969-04-16 1970-10-20
US3726678A (en) * 1970-08-24 1973-04-10 Zenith Radio Corp Method of screening a color picture tube
JPS607344B2 (ja) * 1976-03-08 1985-02-23 株式会社東芝 カラー受像管
US4251610A (en) * 1979-11-02 1981-02-17 Tektronix, Inc. Method of making multicolor CRT display screen with minimal phosphor contamination
US4485158A (en) * 1983-10-17 1984-11-27 Rca Corporation Method for preparing a mosaic luminescent screen using a mosaic precoating

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0018666A1 (de) * 1979-05-07 1980-11-12 Optical Coating Laboratory, Inc. Bildschirmaufbau für Kathodenstrahlröhren zur Unterdrückung der Lichthofbildung und Verfahren

Also Published As

Publication number Publication date
DE3462199D1 (en) 1987-02-26
EP0143714B1 (de) 1987-01-21
JPS60133638A (ja) 1985-07-16
US4661742A (en) 1987-04-28
FR2555806B1 (fr) 1986-03-28
FR2555806A1 (fr) 1985-05-31

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