Fail transparent LCD display with backup

• US 4,371,870 A
• Filed: 09/02/1980
• Issued: 02/01/1983
• Est. Priority Date: 09/02/1980
• 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:
  US06/183,346
• Time in Patent Office: 882 Days
• Field of Search: 340/715, 340/716, 340/365 VL, 340/765, 340/784, 340/712
• US Class Current: 345/4
• CPC Class Codes: G06F 3/147 using display panels
• CPC Class Codes: G09F 9/00 Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements in which the variable information is permanently attached to a movable support G09F11/00; abacus G06C1/00; slide-rules G06G1/00
• CPC Class Codes: G09G 3/18 using liquid crystals
• CPC Class Codes: H03M 11/18 wherein the shift keys are operated before the operation of the multifunction keys
• CPC Class Codes: Y10S 345/904 Display with fail/safe testing feature

Abstract

A display system is constructed such that upon failure of the primary display which comprises a Liquid Crystal Display (LCD) that becomes transparent upon failure, a backup display located directly beneath the primary display becomes visible to the display user.

Claims

1. A display system comprising:

a primary liquid crystal display comprising a first liquid crystal display means located closest to a viewer wherein information is presented to the viewer within an at least one information location on the first display means, and a second liquid crystal display means located an effective distance behind the first display means wherein substantially all of the second liquid crystal display means operates in a reflective mode; and

a secondary display wherein the secondary display is located directly behind the primary display such that, upon a termination of power to the primary display, the primary display becomes substantially transparent and the secondary display then becomes visible to the viewer.

2. The system of claim 1 wherein the first liquid crystal display means comprises a field effect type liquid crystal display.

3. The system of claim 1 wherein the second liquid crystal display means comprises a dynamic scattering type liquid crystal display.

4. The system of claim 1 wherein the secondary display comprises a key having a first symbol depicted thereon indicative of a first function of a machine operated by the key and wherein the information presented upon the primary display comprises a second symbol indicative of a second function of the machine wherein the second function is activated substantially concurrently with an application of power to the primary display.

8. The display system of claim 1 or claim 5 further comprising edge lighting means for illumination of the second liquid crystal display means.

5. A display system comprising:

a primary liquid crystal display comprising a plurality of first liquid crystal display means disposed in a stack wherein at least one first display means is selectively energized such that information is presented to a viewer on said energized first display means, and a second liquid crystal display means disposed directly behind the plurality of first liquid crystal display means wherein substantially all of the second liquid crystal display means operates in a reflective mode; and

a backup display wherein the backup display is located directly behind the primary display such that, upon termination of power to the primary display, the primary display becomes substantially transparent and the backup display then becomes visible to the viewer.

6. The display system of claim 5 wherein the first liquid crystal display means comprise field effect type liquid crystal displays.

7. The display system of claim 5 wherein the first liquid crystal display means comprises a dynamic scattering type liquid crystal display.