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Multicolor Display using Color Filtering Technique

IP.com Disclosure Number: IPCOM000089631D
Original Publication Date: 1977-Nov-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 3 page(s) / 33K

Publishing Venue

IBM

Related People

Chang, IF: AUTHOR [+2]

Abstract

The need for internal memory or long persistence and multicolor capability in displays has become increasingly important. Several display technologies (such as storage CRTs, AC plasma panels, laser beam addressed liquid crystals and EL (electroluminescent) panels or EL memory CRTs) offer memory capability. However, there is no attractive display technology other than the color TV tube or penetration tube which can offer multicolor. The present color TV does not offer adequate resolution as a terminal display, and the penetration tube does not yet give satisfactory color displays.

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Multicolor Display using Color Filtering Technique

The need for internal memory or long persistence and multicolor capability in displays has become increasingly important. Several display technologies (such as storage CRTs, AC plasma panels, laser beam addressed liquid crystals and EL (electroluminescent) panels or EL memory CRTs) offer memory capability. However, there is no attractive display technology other than the color TV tube or penetration tube which can offer multicolor. The present color TV does not offer adequate resolution as a terminal display, and the penetration tube does not yet give satisfactory color displays.

Schemes are described here for achieving multicolor displays based on a new material technology of depositing color glass by evaporation. The basic concept is to use a single light source and multielements of color filters to achieve multicolor capability in a display device rather than using multicolor light sources. The light source may be an E-beam addressed CL (cathodoluminescent) phosphor, a light beam or gas-discharge addressed PL (photoluminescent) phosphor, a plasma panel or an EL phosphor powder or thin film. The filter elements may be any organic or inorganic material with band pass light transmission characteristics and compatibility with light source fabrication processes. One attractive candidate is glass material, such as Schott-glass, with appropriate doping.

Different color filter elements may be deposited on a transparent substrate by evaporations of doped glasses through a set of masks which define discrete dot, stripe, or line patterns. (Etching techniques comprise another alternative but may be a more costly process.) Glass materials are selected for different transmission bands and bandwidth depending on the light source used. If necessary, narrow band-pass or specific band-pass filters may be obtained by superposing multilayers of filters. The experience gained in the evaporation-through-mask process indicates that the desired resolution in the range of 2-5 mils per color element can be easily achieved.

Different multicolor display schemes may be designed depending on the light source and addressing method used. Several arrangements are outlined below:

1. Multicolor CRT.

As shown in Fig. 1, the color filter elements 1 are deposited on the inside of a CRT faceplate 3. A broadband light-emitting phosphor layer 5, such as P4 (white used in B/W TV) or P45 (bluewhite), is coated on top of these filter elements. In operation, the electron beam is deflected to a selected position where the CL phosphor transmits through the selected color filter element, resulting in desired color emission. The arrangement shown utilizes a single gun CRT that is much easier to fabricate than the three-gun multiphosphor shadow mask or slot mask CRTs.

2. Multicolor Matrix Addressed EL Display.

As shown in Fig. 2, the color filter elements 7 are deposited on a transparent substrate 9. In turn, a matrix addresse...