Night vision backlighting system for liquid crystal displays

• US 5,143,433 A
• Filed: 11/01/1991
• Issued: 09/01/1992
• Est. Priority Date: 11/01/1991
• Status: Expired due to Fees

• Current Assignee: 1294339 Ontario, Inc.
• Original Assignee: L3 Technologies ESS, Inc. (L3Harris Technologies, Inc.)
• Inventors: Farrell, James F.
• Primary Examiner(s): Lazarus, Ira S.
• Assistant Examiner(s): Hagarman, Sue
• Application Number:
  US07/786,484
• Time in Patent Office: 305 Days
• Field of Search: 340/784, 359/48, 359/49, 359/50, 362/23, 362/62, 362/31, 362/32, 362/26, 362/27, 362/29, 362/30
• US Class Current: 362/29
• CPC Class Codes: G01D 11/28 Structurally-combined illuminating devices
• CPC Class Codes: G02F 1/133603 with LEDs
• CPC Class Codes: G02F 1/133604 with lamps
• CPC Class Codes: G02F 1/133613 characterized by the sequence of light sources
• CPC Class Codes: G02F 1/133626 providing two modes of illumination, e.g. day-night
• CPC Class Codes: G09G 3/342 using several illumination sources separately controlled corresponding to different display panel areas, e.g. along one dimension such as lines

Abstract

This invention presents a way to provide night vision viewing compatibility of backlit electrooptic modulated light valve or LCD displays designed for daylight viewing. Liquid crystal displays (LCD) designed with backlighting systems which provide a high brightness, good contrast display under daylight conditions are inappropriate for use in dark, night time conditions where viewing of the display is desired utilizing electronic night vision equipment. This invention describes improvements to standard backlighting displays which through the utilization of arrays of low-level intensity light sources such as secondary fluorescent light sources, miniature incandescent lamps or light emitting diodes, the general means used in daylight vision can be turned off and the secondary low-level lighting sources achieve a minimum intensity acceptable for night vision electronic viewing.

Claims

1. A backlit electrooptic modulated light valve display panel which is readable with the unaided eye under bright lighting conditions of day light and is readable with night vision equipment under dark conditions of night which comprises:

an electrooptic modulated light valve panel for controllably modifying light being transmitted therethrough into readable colored patterns of information;

a means for emitting high intensity light through said electrooptic modulated light valve panel and activated for daylight viewing of the display; and

a means for emitting low intensity light through said electrooptic modulated light valve panel for viewing in dark conditions with night vision equipment, and with said means for emitting high intensity light deactivated.

2. A backlit electrooptic modulated light valve display panel according to claim 1 wherein said means for emitting high intensity light is a flat fluorescent lamp.

3. A backlit electrooptic modulated light valve display panel according to claim 1 wherein said means for emitting high intensity light is a side illuminated, internally reflecting, solid state light pipe.

4. A backlit electrooptic modulated light valve display panel according to claim 1 wherein said means for emitting low intensity light is an array of miniature incandescent lamps.

5. A backlit electrooptic modulated light valve display panel according to claim 4 wherein said array of miniature incandescent lamps further comprises:

multiple individual incandescent lamps fitted with filters to controllably further reduce the low intensity light emitted to a preselected level suitable for viewing said display in the dark with night vision equipment.

6. A backlit electrooptic modulated light valve display panel according to claim 1 wherein said means for emitting low intensity light is an array of light emitting diodes.

7. A backlit electrooptic modulated light valve display panel according to claim 6 wherein said array of light emitting diodes further comprises:

multiple individual light emitting diodes fitted with filters to controllably further reduce the low intensity light emitted to a preselected level suitable for viewing said display in the dark with night vision equipment.

8. A backlit electrooptic modulated light valve display panel according to claim 1 wherein said electrooptic modulated light valve panel is a liquid crystal panel.

9. A backlit electrooptic modulated light valve display panel which is readable with the unaided eye under bright lighting conditions of daylight and is readable with night vision equipment under dark conditions of night which comprises:

an electrooptic modulated light valve panel for controllably modifying light being transmitted therethrough into readable colored patterns of information;

at least one primary fluorescent lighting means for emitting high intensity backlighting which is transmitted through said electrooptic modulated light valve panel and activated during daylight viewing of the display; and

at least one secondary fluorescent lighting means for emitting low intensity backlighting which is transmitted through deactivated said primary light emitting tubes and therefrom through said electrooptic modulated light valve panel during viewing of the display under low lighting conditions.

10. A backlit electrooptic modulated light valve display panel according to claim 9 further comprising:

a reflecting surface being positioned on a side of said primary fluorescent lighting means opposite the placement of said electrooptic modulated light valve panel whereby light from said primary fluorescent lighting means is reflected through said electrooptic modulated light valve panel, said reflecting surface containing slots of select lengths and widths.

11. A backlit electrooptic modulated light valve display panel according to claim 10 wherein said secondary fluorescent lighting means for emitting low intensity backlighting are positioned and controlled to radiate low-level light through said slots.

12. A backlit electrooptic modulated light valve display panel according to claim 11 further comprising:

a filter means placed between said secondary fluorescent lighting means and said slots.

13. A backlit electrooptic modulated light valve display panel according to claim 12 wherein said primary and secondary fluorescent lighting means are fluorescent light emitting tubes.

14. A backlit electrooptic modulated light valve display panel according to claim 13 wherein said electrooptic modulated light valve panel is a liquid crystal panel.

15. A backlit electrooptic modulated light valve display panel which is readable with the unaided eye under bright lighting conditions of daylight and is readable with night vision equipment under dark conditions of night which comprises:

an electrooptic modulated light valve panel for controllably modifying light being transmitted therethrough into readable colored patterns of information;

at least one fluorescent lighting means for emitting high intensity backlighting which is transmitted through said electrooptic modulated light valve panel and activated during daylight viewing of the display; and

multiple low-level light emitting sources placed near deactivated said fluorescent lighting means for emitting low intensity backlighting which is transmitted through said electrooptic modulated light valve panel during viewing in dark conditions with night vision equipment.

16. A backlit electrooptic modulated light valve display panel according to claim 15 further comprising:

a reflecting surface being positioned on a side of said fluorescent lighting means opposite the placement of said electrooptic modulated light valve panel whereby light from said primary fluorescent lighting means is reflected through said electrooptic modulated light valve panel.

17. A backlit electrooptic modulated light valve display panel according to claim 16 wherein said low-level light emitting sources are imbedded within the surface of said reflecting surface.

18. A backlit electrooptic modulated light valve display panel according to claim 17 wherein said low-level light sources are an array of miniature incandescent lamps.

19. A backlit electrooptic modulated light valve display panel according to claim 18 wherein said miniature incandescent lamps further comprises:

multiple individual incandescent lamps fitted with optical lenses which aid in focusing their emitted low-level light into said fluorescent tubes.

20. A backlit electrooptic modulated light valve display panel according to claim 19 wherein said array of miniature incandescent lamps further comprises:

multiple individual incandescent lamps fitted with filters to controllably further reduce the low intensity light emitted to a preselected level suitable for viewing said display in the dark with night vision equipment.

21. A backlit electrooptic modulated light valve display panel according to claim 17 wherein said low-level light sources are in array of light emitting diodes.

22. A backlit electrooptic modulated light valve display panel according to claim 21 wherein said array of light emitting diodes further comprises:

multiple individual light emitting diodes fitted with filters to controllably further reduce the low intensity light emitted to a preselected level suitable for viewing said display in the dark with night vision equipment.

23. A backlit electrooptic modulated light valve display panel according to claim 17 further comprising:

a diffusing means placed between said fluorescent lighting means and said electrooptic modulated light valve panel.

24. A backlit electrooptic modulated light valve display panel according to claim 17 further comprising:

a filter means placed between said fluorescent lighting means and said electrooptic modulated light valve panel.

25. A backlit electrooptic modulated light valve display panel according to claim 15 wherein said electrooptic modulated light valve panel is a liquid crystal panel.