Browse Prior Art Database

Thin Film Electroluminescent Storage Display and Its Screen Fabrication

IP.com Disclosure Number: IPCOM000085942D
Original Publication Date: 1976-Jun-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 3 page(s) / 40K

Publishing Venue

IBM

Related People

Chang, IF: AUTHOR

Abstract

In U.S. Patent 3,796,909 to Chang et al, an electroluminescent (EL) storage display device is described, which separates the storage function and display function by using an AC field-sensitive display medium. This description is directed to a thin film electroluminescent storage display and its screen fabrication. Such a thin film EL screen provides high brightness, contrast and resolution, and long life and image stability.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 46% of the total text.

Page 1 of 3

Thin Film Electroluminescent Storage Display and Its Screen Fabrication

In U.S. Patent 3,796,909 to Chang et al, an electroluminescent (EL) storage display device is described, which separates the storage function and display function by using an AC field-sensitive display medium. This description is directed to a thin film electroluminescent storage display and its screen fabrication. Such a thin film EL screen provides high brightness, contrast and resolution, and long life and image stability.

The cathodoluminescent storage CRT suffers from low brightness and poor contrast. As such, the cathodoluminescent storage CRT has limited use for alphanumeric and graphic display applications. The Chang et al patent, supra, describes a new storage display concept wherein an AC field-sensitive material is used as the display medium.

Image is displayed by electroluminescence, for example, rather than cathodoluminescence. Described here is a thin film EL and bistable storage screen which can be fabricated by thin film technology.

The thin film EL and bistable storage screen is shown in the cross-sectional view of a storage CRT in Fig. 1. In conventional manner, substrate 1 may comprise a transparent material, such as glass. Deposited upon substrate 1 is a thin layer of transparent conducting material 3, such as doped tin or indium oxide. Transparent conductor 3 serves as the back electrode to the screen arrangement. Deposited upon transparent conductor 3 is a transparent insulating layer 5. This layer may, for example, comprise Al(2)O(3), Y(2)O(3), Si(3)N(4), Nb(2)O(5), Ta(2)O(5),TiO(2), ZrO(2) or any of a variety of titanates.

After transparent insulating layer 5 has been deposited, a thin film EL layer 7 is deposited upon the insulating layer. The thin film EL layer 7 may, for example, comprise evaporated ZnS with Mn doping. Thereafter, light-absorbing layer 9 is deposited upon the thin film EL layer 7. The light-absorbing layer 9 may, for example, comprise AS(2)S(3). Insulating layer 11 is then deposited upon the light-absorbing layer 9 which insulating layer serves as a secondary electron- emitting layer. In addition, the insulating layer 11 serves as an additional protection layer for strengthening device high-voltage breakdown and protecting the EL layer 7 during the etching of layer 13, as will be described hereinafter. The insulating layer 11 may typically comprise, for example, MgO, SiO(2) or Al(2)O(3).

Layer 13 acts as a low-capacity (capacitance) insulator (low-dielectric constant and thicker film). Layer 13 may, for example, comprise glasses, sputtered quartz, etc. A dot array (any kind of closely packed two-dimensional lattice) or line pattern may be defined in layer 13, for example, by conventional etching techniques, or the like. Alternatively, this layer may be deposited through a mask such as shown in Figs. 2A-2C.

Finally, conducting film 15 is deposited upon insulator 13. Conducting film 15 is interconnected as a mesh and s...