Method of making multicolor CRT display screen with minimal phosphor contamination

• US 4,251,610 A
• Filed: 11/02/1979
• Issued: 02/17/1981
• Est. Priority Date: 11/02/1979
• Status: Expired due to Term

• Current Assignee: Tektronix Incorporated (Fortive Corp.)
• Original Assignee: Tektronix Incorporated (Fortive Corp.)
• Inventors: Haven, Duane A., Chitwood, Donald P.
• Primary Examiner(s): Kimlin, Edward C.
• Application Number:
  US06/090,709
• Time in Patent Office: 473 Days
• Field of Search: 430/24, 430/25, 354/1, 427/68, 427/64
• US Class Current: 430/25
• CPC Class Codes: G03F 7/0007 Filters, e.g. additive colour filters; Components for display devices
• CPC Class Codes: H01J 9/2271 by photographic processes final treatment of shadow-mask prior to or after dot deposition H01J9/144

Abstract

An improved method of forming a multicolor cathode-ray tube display screen to minimize phosphor contamination. A light-absorbing matrix is first formed on the inner surface of a CRT faceplate, preferably by photoetching of a substantially black metallic layer. Then, multiple color dot patterns are deposited in the matrix openings by (a) depositing a layer of positive photoresist on the matrix and any previously-deposited dot pattern; (b) exposing the resist through a shadow mask to light from a point source positioned to simulate an electron gun; (c) developing the resist to form an integral mask containing a pattern of holes aligned with the matrix openings for one color phosphor; (d) coating the developed resist layer with a photohardenable phosphor slurry; (e) exposing the slurry coating through the faceplate to light from a diffuse source; (f) developing the slurry to remove the unexposed portions, leaving a pattern of dots of one color; and (g) stripping away the photoresist masking layer. Steps (a) through (g) are then repeated to produce each additional color dot pattern.

Claims

1. A method of manufacturing a display screen for a cathode-ray tube, comprising the steps of:

forming on a transparent support a light-absorbing layer that includes a plurality of light-transmissive openings,

coating the light-absorbing layer with a first continuous layer of a photosensitive material,

exposing portions of said first layer to actinic radiation at locations overlying said light-transmissive openings,

treating said first layer to remove the exposed portions thereof and form a plurality of openings individually aligned with those of said light-absorbing layer,

coating the remaining portions of said first layer with a second continuous layer of a photosensitive material,

passing actinic radiation through said support and light-transmissive openings to expose portions of the second layer defined by the aligned openings, and

treating said second layer to remove the unexposed portions thereof while retaining the exposed portions within said aligned openings.

2. The method of claim 1, wherein said second layer is comprised of a luminescent material dispersed in a photohardenable binder.

3. The method of claim 1 or 2, wherein said first layer comprises a material whose solubility in a solvent is increased by exposure to actinic radiation.

4. A method of manufacturing a display screen for a cathode-ray tube of the type wherein said screen comprises an array of phosphor elements disposed on the inner surface of the tube'"'"'s faceplate, separated from one another by light-absorbing material comprising the steps of:

forming a matrix layer of light-absorbing material on said inner surface, said layer including an array of openings at separated locations on said surface for receiving said phosphor elements,

covering said matrix layer and faceplate surface locations with a first layer of a photosensitive material whose solubility in a solvent is increased by exposure to actinic radiation,

exposing said first layer to actinic radiation at selected locations corresponding to certain of said surface locations,

treating said first layer to remove the exposed portions thereof and uncover said inner surface at the selected locations,

covering the remaining portions of said first layer and the uncovered portions of said surface with a second layer comprising a phosphor material dispersed in a photosensitive binder whose solubility in a solvent is decreased by exposure to actinic radiation,

transmitting actinic radiation through said faceplate to expose said second layer selectively at said certain inner surface locations,

treating said second layer to remove the unexposed portions thereof while retaining the exposed portions, and

removing the remaining portions of said first layer.

5. The method of claim 4, wherein said matrix layer is of a metallic material.

6. A method of manufacturing a display screen for a cathode-ray tube of the type wherein said screen comprises an array of phosphor elements disposed on the inner surface of the tube'"'"'s faceplate, separated from one another by light-absorbing material, and wherein an apertured shadow mask is mounted within said tube in spaced relation to said screen, comprising the steps of:

forming a matrix layer of light-absorbing material on said inner surface, said layer including an array of openings defining separated areas of said surface for receiving said phosphor elements,

covering said matrix layer and faceplate surface areas with a first layer of a photosensitive material whose solubility in a solvent is increased by exposure to actinic radiation,

exposing said first layer to actinic radiation transmitted through certain apertures of a shadow mask mounted adjacent said inner surface to form in said layer a pattern of developable latent images at locations corresponding to certain of said surface areas,

developing said latent images to remove the corresponding portions of said first layer and uncover said inner surface areas at the selected locations,

covering the remaining portions of said first layer and the uncovered areas of said surface with a second layer comprising a phosphor material dispersed in a photosensitive binder whose solubility in a solvent is decreased by exposure to actinic radiation,

transmitting actinic radiation through said faceplate to expose said second layer at the selected inner surface locations,

developing said second layer to remove the unexposed portions thereof while retaining the exposed portions, and

removing the remaining portions of said first layer.

7. The method of claim 6, wherein said matrix layer is formed by steps including:

applying a light-absorbing metallic film to said inner surface,

covering said metallic film with a layer of a photosensitive material whose solubility in a solvent is increased by exposure to actinic radiation,

mounting said shadow mask adjacent said inner surface,

exposing said photosensitive layer to actinic radiation transmitted through the apertures of said mask,

developing said layer to remove the exposed portions thereof and uncover said metallic film at locations corresponding to said separated surface areas,

removing the uncovered portions of said metallic film, and

removing the remaining portions of said photosensitive layer.

8. The method of claim 6, wherein said first layer of photosensitive material is substantially opaque to radiation that is capable of rendering said photosensitive binder insoluble, and wherein said second layer is exposed using such radiation.

9. The method of claim 6, wherein each of the steps following formation of said matrix layer is repeated to deposit multiple, interleaved phosphor element patterns of different emission characteristics.

10. The method of claim 9, wherein said phosphor element patterns comprise dot patterns of different color-emitting phosphors.