Fail transparent electro-luminescent display with backup

• US 4,568,928 A
• Filed: 05/16/1983
• Issued: 02/04/1986
• Est. Priority Date: 05/16/1983
• Status: Expired due to Term

• Current Assignee: Mcdonnell Douglas Corporation (The Boeing Co.)
• Original Assignee: Mcdonnell Douglas Corporation (The Boeing Co.)
• Inventors: Biferno, Michael A.
• Primary Examiner(s): Curtis, Marshall M.
• Application Number:
  US06/494,961
• Time in Patent Office: 995 Days
• Field of Search: 340/716, 340/781, 340/784, 340/705
• US Class Current: 345/5
• CPC Class Codes: G06F 3/147 using display panels
• CPC Class Codes: G09G 2300/023 Display panel composed of stacked panels
• CPC Class Codes: G09G 3/00 Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes

Abstract

This display system comprises, front to rear, an electro-luminescent information bearing display element which is substantially transparent when not energized, a background element which is dark (opaque) when it is energized and substantially transparent when not energized, and a backup display means which is visible when the two front elements are not energized.

Claims

1. A display system comprising:

electro-luminescent display means disposed as the information-bearing element of the system which is closest to a viewer of the system presenting information within at least one information location on the electro-luminescent display means when energized and such that, when the electro-luminescent display is not energized, the electro-luminescent display is effectively transparent wherein the electro-luminescent display means comprises an intermediate layer of a transparent electroluminescent material held between two transparent electrode layers;

background means disposed behind the electro-luminescent display means relative to the viewer such that the background means appears substantially dark to the viewer when the electro-luminescent display is energized and effectively transparent when the electro-luminescent display is not energized wherein the background means comprises a liquid crystal display means comprising a layer of liquid crystal material held between two transparent electrode layers, the liquid crystal display means providing a uniform dark area behind each energized information-bearing area of the electro-luminescent display; and

backup display means disposed behind the background means relative to the viewer such that the backup display is visible to the viewer when the electro-luminescent display means and the background means are not energized.

2. The system of claim 1 wherein the background means comprises twisted nematic liquid crystal cell means.

3. The system of claim 2 wherein the twisted nematic liquid crystal cell means comprises two twisted nematic liquid crystal cells disposed such that, when both cells are energized, their polarization vectors are about 90 degrees apart, resulting in a substantially dark aspect, and, when both cells are not energized, the background means is substantially transparent.

4. The system of claim 1 wherein the electro-luminescent display means comprises an alphanumeric display.

5. The system of claim 1 wherein the electro-luminescent display means comprises a grid of independently energizable pixel elements.

6. The system of claim 1 wherein the electro-luminescent display means comprises a multicolored display.

7. The system of claim 1 wherein the electro-luminescent display means comprises at least one dedicated pictorial image.

8. The system of claim 1 wherein the electro-luminescent display means comprises at least one symbol comprising a plurality of independently energizable segments.