Liquid crystal display with a fast warm up

• US 5,164,849 A
• Filed: 10/05/1990
• Issued: 11/17/1992
• Est. Priority Date: 10/05/1990
• Status: Expired due to Term

• Current Assignee: Alliedsignal Inc. (Honeywell International Inc.)
• Original Assignee: Alliedsignal Inc. (Honeywell International Inc.)
• Inventors: Brown, Robert W., Evans, Lansing B.
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): TRICE, RONALD
• Application Number:
  US07/593,160
• Time in Patent Office: 774 Days
• Field of Search: 340/770, 340/784, 359/45, 359/48, 359/86, 359/72
• US Class Current: 349/72
• CPC Class Codes: G02F 1/133382 Heating or cooling of liquid crystal cells other than for activation, e.g. circuits or arrangements for temperature control, stabilisation or uniform distribution over the cell
• CPC Class Codes: G02F 1/1336 Illuminating devices

Abstract

Display apparatus and method having window shade heating. The display has an active matrix LCD with a plurality of elements and a backlight having a variable brightness. During warm-up of the display, the operating temperature will be below the normal operating temperature. To decrease warm-up time, the LCD elements are darkened and the brightness of the backlight is increased.

Claims

1. A display having an internal operating temperature, comprsiing:

a plurality of liquid crystal display elements;

a backlight having variable brightness and positioned for illuminating said plurality of liquid crystal display elements; and

control means connected to said backlight for increasing said brightness of said backlight and darkening said plurality of liquid crystal display elements during an initial warm-up period when the internal operating temperature is below a predetermined threshold.

2. The display as claimed in claim 1, wherein said control means increases said brightness and darkens said plurality of liquid crystal display elements during a warm-up time of predetermined duration.

3. The display as claimed in claim 1, further comprising:

a sensor having an output indicative of lighting conditions external to the display;

wherein said brightness of said backlight is controlled in accordance with said output from said sensor and the internal operating temperature.

4. The display as claimed in claim 1, further comprising:

a first sensor having an output indicative of the internal operating temperature of the display;

wherein said control means darkens said plurality of liquid crystal display elements and increases said brightness if said output of said first sensor is below said predetermined threshold.

5. The display as claimed in claim 4, wherein said brightness is increased to a maximum.

6. The display as claimed in claim 4, further comprising:

a second sensor having an output indicative of the lighting conditions external of the display;

wherein said brightness of said backlight is controlled in accordance with said outputs of said first and second sensors.

7. A method of controlling a display having liquid crystal display elements and a backlight for illuminating the elements, the display having an internal operating temperature, comprising the step of increasing the brightness of the backlight and darkening the elements during an initial warm-up period when the internal operating temperature is below a predetermined threshold.

8. The method as claimed in claim 7, wherein the brightness is increased and teh elements darkened during a warm-up time of predetermined duration.

9. The method as claimed in claim 7, further comprising the steps of sensing lighting conditions external to the display and increasing the brightness of the backlight in accordance with the sensed conditions and the internal operating temperature.