EP0342900A1 - Herstellungsverfahren für Leuchtschirme - Google Patents

Herstellungsverfahren für Leuchtschirme Download PDF

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Publication number
EP0342900A1
EP0342900A1 EP89304890A EP89304890A EP0342900A1 EP 0342900 A1 EP0342900 A1 EP 0342900A1 EP 89304890 A EP89304890 A EP 89304890A EP 89304890 A EP89304890 A EP 89304890A EP 0342900 A1 EP0342900 A1 EP 0342900A1
Authority
EP
European Patent Office
Prior art keywords
layer
resist
mask
faceplate
electron
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Withdrawn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
EP89304890A
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English (en)
French (fr)
Inventor
Gordon Ronald Bonye
Martin Kavanagh
Nicholas Stephen Bellis
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.)
Rank Brimar Ltd
Original Assignee
Rank Brimar Ltd
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 Rank Brimar Ltd filed Critical Rank Brimar Ltd
Publication of EP0342900A1 publication Critical patent/EP0342900A1/de
Withdrawn legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
    • H01J9/20—Manufacture of screens on or from which an image or pattern is formed, picked up, converted or stored; Applying coatings to the vessel
    • H01J9/22—Applying luminescent coatings
    • H01J9/227—Applying luminescent coatings with luminescent material discontinuously arranged, e.g. in dots or lines
    • H01J9/2271—Applying luminescent coatings with luminescent material discontinuously arranged, e.g. in dots or lines by photographic processes

Definitions

  • the present invention relates to a method of preparing a phosphor screen.
  • a colour cathode ray tube comprises a screen on which arrays of different phosphors which emit differently coloured light in response to electron beams, are accurately positioned on a screen of the CRT with respect to holes (or slits) in a shadow mask.
  • An electron gun arrangement produces a different electron beam for each colour.
  • Many methods of making the arrays of phosphors are known.
  • U.S. Patent 4251610 discloses an illustrative method in which an opaque layer is first formed on the inner surface of holes in a black opaque layer. Assuming three differently “coloured” phosphors are to be used, three arrays of holes are produced in the opaque layer. This is done by coating the opaque layer with photo resist, and illuminating the coating through a shadow mask with light from a light source which simulates the three electron beams, developing the resist, etching the layer using the developed resist as a mask and then removing the resist.
  • Phosphor of one colour e.g. green is put into one of the arrays using the following process:-­
  • a coating of photo resist is put over the entire opaque layer and the holes.
  • the coating is exposed to ultra-violet (UV) light from a light source simulating the green electron beam through the shadow mask.
  • UV ultra-violet
  • the coating is then developed to expose the "green” array of holes leaving the two other arrays covered by resist.
  • Green phosphor and photosensitive binder are put onto the screen.
  • the phosphor and binder are exposed to ultra violet light through the screen to fix the green phosphor in the green holes. Excess phosphor, binder and photoresist are removed, leaving an array of green phosphor dots.
  • the process is repeated for the other colours. Each repetition begins with a new coating of photo resist which covers the previously laid-down phosphor, thus protecting the previously laid-down phosphor from cross-contamination.
  • an opaque layer is first formed on the inner surface of the screen of a CRT.
  • An array of phosphor is laid down using the following process:-­
  • the layer is coated with electron beam sensitive resist which is exposed to e.g. the "green” electron beam through a shadow mask.
  • the electron beam resist is developed and the layer etched to produce an array of "green” apertures or holes thereon.
  • Green" phosphor plus photosensitive binder is applied and is exposed to UV light through the screen to fix the phosphor in the apertures.
  • the electron beam resist is removed.
  • a new coating of electron beam resist is then laid down and the process repeated for the or each other coloured phosphor.
  • a phosphor screen having accurate placement of the phosphors, and preferably also with reduced cross-contamination of the phosphors.
  • a method of forming a plurality of different interspersed arrays of phosphors on the inside of a faceplate for a colour cathode ray tube in which method, a first mask is formed by irradiating an electron sensitive resist layer through a shadow mask with an electron gun arrangement in a demountable tube substantially at the same positions with respect to the arrays as the electron gun arrangement which will energise those arrays in the completed tube, a layer of light blocking material is formed over the first mask, subsidiary masks are sequentially formed in the blocking layer for respective ones of the arrays of phosphors, each subsidiary mask being formed by irradiating electron beam resist covering the blocking layer through the shadow mask with an electron beam corresponding to the beam which will energise the associated array in use of the tube and removing the irradiated resist and underlying blocking layer, and phosphor is fixed in position in the sub-mask.
  • each sub-mask and phosphor array is covered by the resist layer used for making the next sub-mask before the next sub-mask and phosphor array is formed, all the resist layers being retained until all the phosphor arrays are formed.
  • the phosphors are fixed in position by irradiating them with light through the sub-masks.
  • the light is preferably UV light and the blocking layer blocks UV light.
  • a method of forming a plurality of interspersed colour phosphor arrays on the inside of a faceplate for a colour cathode ray tube comprising;
  • FIG. 1 illustrates a "demountable" CRT system, which accurately simulates the completed CRT, using the actual CRT faceplate 101 and its matching shadow mask 102 and shadow mask frame 103.
  • the envelope 104 which may be made of metal, glass or ceramic and which is connected by a tube 105 to a vacuum pump system 106.
  • a multiple electron gun 108 Inside the neck of the envelope 104 is mounted a multiple electron gun 108 and on the exterior of the neck 107 are mounted the CRT scan coils 109 by which the electron beams emitted by the electron gun 108 can be made to scan by the application of the appropriate voltage waveforms.
  • the whole assembly within the envelope 104 is vacuum tight, the faceplate 101 being joined to the envelope 104 by means of a gasket 110.
  • the faceplate 1 of the CRT is separated from the shadow mask 102 and an opaque coating 2 is applied.
  • the coating which is conductive may be reflective, for example aluminium, or may be a black coating, for example a layer of black chromium (which is non-conductive) together with a conductive material such as indium tin oxide or tin oxide.
  • the black chromium is applied by evaporation in an oxidising gassy atmosphere by methods which are well known and long established.
  • a first layer of electron sensitive resist 3 is then applied to the faceplate 1 for example by spinning.
  • the resist layer is then hardened by baking.
  • the type of resist may be described as "positive” or “negative” according to whether it softens or hardens respectively under the action of an electron beam; for convenience the method here described is the process for the "positive” resist).
  • Various types of electron sensitive resist may be used, for example, one comprising copolymers of methylmethacrylic acid and methacryloyl chloride and other methacrylates i.e. PM type resists.
  • PM type resists Alternatively, PMMA types of electron sensitive resist comprising polymethylmethacrylates in cellusolve acetate may be used.
  • a particular commercially available electron sensitive resist which may be used is ISOFINE E-B positive resist grade P7.
  • the faceplate 1 and the shadow mask 102 are then assembled together and placed on the demountable CRT as in Figure 1. Appropriate voltages are applied and the resist 3 is exposed, through the shadow mask 102 to scanning electron beams from the directions indicated by the arrows in Figure 2-3 from all of the electron guns in the electron gun housing 108. Those parts of the resist 3 which receive the electron beam through the shadow mask holes become softened.
  • the faceplate assembly is then removed from the demountable CRT and the resist layer 3 is treated with developer, whereupon the exposed dots or lines, as appropriate, are removed and the unexposed areas remain to produce an opaque layer 2 on the faceplate 1 with an apertured layer of developed resist 3 superimposed thereon.
  • the exposed parts of the opaque layer 2 are then etched away through the apertures or holes in the resist 3, and the unexposed parts of the opaque layer 2 are allowed to remain, as shown in Figure 2-4, thus forming a mask having apertures 5 therein.
  • the opaque layer 30 is black chromium then the etching agent used can be a mixture of ammonium ferric nitrate, perchloric acid and demineralised water. If aluminium forms the opaque layer 30 then this can be etched using dilute caustic soda.
  • a mask containing apertures or holes e.g. dots or lines, for red, green and blue emitting phosphors.
  • the remaining layer of resist 3 and the apertures 5 are coated firstly with a blocking layer of material which blocks (or absorbs) ultra-violet light, and secondly with a layer of electron beam resist over the blocking layer.
  • the coating is indicated by reference 6.
  • the blocking layer is for example a coating called Anti-Reflection Coating (ARC) obtainable from Brewer Science Inc. of (address please).
  • ARC comprises heavily dyed polyimide and is a highly UV light absorbing coating.
  • D ARC also available from Brewer Science Inc.
  • the blocking layer must be compatible with the electron beam resist, survive baking, and block UV light. To be compatible with the resist it must at least not inhibit the resist and preferably also be miscible with the resist.
  • the faceplate 1 is then reunited with the shadowmask 102 and the assembly is placed on the demountable tube shown in Figure 1.
  • the tube is pumped down to vacuum, and one, e.g. green, of the electron guns is energised to expose the resist 6 over the "green" apertures 5 to the "green" beam GB (Fig 2-6).
  • the assembly is then removed from the tube and the resist 6 is developed. Developing the resist 6 removes the resist 6 from the "green” holes; in addition the ARC in the "green” holes may be simultaneously removed. Alternatively, the ARC can be removed from the "green” holes in a separate developing step.
  • Fig 2-6 ARC and resist 6 is left in the "red” and "blue” holes and over the mask of black chrome.
  • U.V. sensitive photobinder for example, polyvinylalcohol sensitised with ammonium bichromate
  • a second layer of electron sensitive resist 8 is now applied.
  • the second layer of resist 8 covers the e.g. green phosphor and the first layer of resist and ARC 6.
  • the faceplate 1 together with the shadow mask 102 are then assembled together and placed on the demountable CRT shown in Figure 1 and the first 6 and second 8 layers of resist are exposed, through the shadow mask 2 to a scanning electron beam from the direction indicated by the arrows in Figure 2-9.
  • a different one of the electron guns is used to generate the beam RB in this case, for example, the gun responsible for the red content on the screen.
  • first and second layers of resist 6, 8 which receive the electron beam RB through the shadow mask holes become softened and, as before, the faceplate assembly is then removed from the demountable CRT and the first and second resist layers 6 and 8 are treated with developer, whereupon the exposed dots or lines 35 of resist 6, 8 are removed and the unexposed areas remain. Additionally, where the apertures 35 of resist 6, 8 are removed, the ARC is also removed.
  • the faceplate is exposed to U.V from a diffuse source shone through the glass faceplate 1 so that the parts of the photoresist and phosphor mixture which are in the apertures 35 are polymerised.
  • the ARC prevents the mixture polymerising elsewhere.
  • Developing the photobinder results in hardened phosphor dots or lines remaining in the apertures 10 as shown in Figure 2-12.
  • the first layer of ARC and electron sensitive resist 6 is retained, and the second layer of resist 8 is also retained.
  • the process is repeated by applying a third layer of resist over the first and second layers and over the red and green phosphors.
  • the third layer is exposed to the "blue" electron gun through the shadow mask, and developed, the opaque layer etched and "blue” phosphor fixed in the apertures as described above. The result is shown in Figure 2-13.
  • arrays of the red, green and blue phosphors 33′, 36 and 37 are arranged in interspersed relation on the faceplate 1 in registry with the points at which the red, green and blue electron beams, respectively, irradiate the faceplate 1 during use.
  • the second repeat of the process may be omitted if required to produce a screen with only two colours of phosphor. Similarly, further repeats may be necessary to produce a screen with more than three colours.
  • each phosphor to be fixed in position is protected from cross-contamination by the other phosphors.
  • Electron-sensitive resists are normally insufficiently absorbent to act as masks to the UV light themselves even when two or more layers of resist are present with U.V absorbing dye.
  • the ARC however, makes possible the process in which all the sets of apertures are formed in the mask simultaneously.
  • red, green and blue phosphors Whilst reference has been made to red, green and blue phosphors, other colours of phosphor can be used, e.g. yellow, magenta and cyan.
  • Figure 3 shows an alternative method, in accordance with a further aspect of the invention, for preparing a phosphor screen and which avoids irradiating phosphor through the black absorbing layer as shown in Figures 2-7 to 2-13.
  • the starting point for the process shown in Figure 3 is a mask of e.g. black chromium formed on the faceplate 1 using the steps shown in Figures 2-1, 2-2, 2-3 and 2-4 as described above.
  • the mask 2 is thus formed using the electron beams to produce three arrays of apertures for the red, green and blue phosphors.
  • the mask is covered in e.g. a slurry of green phosphor 7 as shown in Figure 3-2.
  • the shadow mask 102 is then remounted on the faceplate and the assembly of faceplate and shadow mask is then exposed, in a known form of light house, to ultra violet light corresponding to e.g. the green electron beam.
  • the light irradiates the phosphor slurry 7 through the shadow mask and activates the green phosphor at positions corresponding to positions which would be irradiated by the green elcctron gun in use of the faceplate.
  • the faceplate is disassembled from the light house and shadow mask and the excess phosphor removed with water or the appropriate solvent leaving the green dots or lines 9 as shown in Figure 3-4.
  • the mask 2 and the green dots or lines are then coated with a thin layer or lacquer of material such as methylmethacrylate, a slurry of e.g. red phosphor and photobinder 10 is then laid down.
  • the shadow mask 102 is then reassembled into the faceplate, the assembly is then assembled into a light house and irradiated with ultra violet light corresponding to the red electron beam.
  • the irradiated red phosphor is washed with water or the appropriate solvent leaving the red dot array, a further lacquer of methylmethacrylate provided over the mask 2 and the red and green dots or lines and the process repeated for the third e.g. blue phosphor.
  • the electron beam resist layers, lacquers and photosensitive binders are removed by baking.
  • the phosphor screen is lacquered and aluminised by conventional means.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Formation Of Various Coating Films On Cathode Ray Tubes And Lamps (AREA)
EP89304890A 1988-05-20 1989-05-15 Herstellungsverfahren für Leuchtschirme Withdrawn EP0342900A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8811914 1988-05-20
GB8811914A GB2218846A (en) 1988-05-20 1988-05-20 Manufacture of colour crt phoshor screen

Publications (1)

Publication Number Publication Date
EP0342900A1 true EP0342900A1 (de) 1989-11-23

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP89304890A Withdrawn EP0342900A1 (de) 1988-05-20 1989-05-15 Herstellungsverfahren für Leuchtschirme

Country Status (3)

Country Link
EP (1) EP0342900A1 (de)
JP (1) JPH0221536A (de)
GB (1) GB2218846A (de)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0091163A2 (de) * 1982-04-02 1983-10-12 North American Philips Corporation Positiv arbeitende Photoresistmasse und Verfahren zur Herstellung einer lichtabsorbierenden Schwarzmatrix in einer Farbbildröhre
EP0135965A2 (de) * 1983-09-12 1985-04-03 North American Philips Consumer Electronics Corp. Photographisches Verfahren zum Aufbringen eines Phosphormusters auf eine Schattenmaske eines Farb-Kathodenstrahlungsrohrs
GB2176647A (en) * 1985-03-26 1986-12-31 Rank Electronic Tubes Ltd Manufacture of colour CRT phosphor screens

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0091163A2 (de) * 1982-04-02 1983-10-12 North American Philips Corporation Positiv arbeitende Photoresistmasse und Verfahren zur Herstellung einer lichtabsorbierenden Schwarzmatrix in einer Farbbildröhre
EP0135965A2 (de) * 1983-09-12 1985-04-03 North American Philips Consumer Electronics Corp. Photographisches Verfahren zum Aufbringen eines Phosphormusters auf eine Schattenmaske eines Farb-Kathodenstrahlungsrohrs
GB2176647A (en) * 1985-03-26 1986-12-31 Rank Electronic Tubes Ltd Manufacture of colour CRT phosphor screens

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN, unexamined applications, E field, vol. 8, no. 221, October 9, 1984 THE PATENT OFFICE JAPANESE GOVERNMENT page 121 E 271 *

Also Published As

Publication number Publication date
GB2218846A (en) 1989-11-22
GB8811914D0 (en) 1988-06-22
JPH0221536A (ja) 1990-01-24

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