Liquid crystal display with color backlighting employing light emitting diodes

• US 6,975,369 B1
• Filed: 12/12/2002
• Issued: 12/13/2005
• Est. Priority Date: 12/12/2002
• Status: Active Grant

• Current Assignee: Current Lighting Solutions, LLC (f/k/a GE Lighting Solutions, LLC) (American Industrial Partners)
• Original Assignee: Gelcore (General Electric Company)
• Inventors: Burkholder, Greg Eugene
• Primary Examiner(s): NGUYEN, DUNG T
• Application Number:
  US10/248,037
• Time in Patent Office: 1,097 Days
• Field of Search: 349 61- 71, 345 88- 89
• US Class Current: 349/61
• CPC Class Codes: G02F 1/133603 with LEDs
• CPC Class Codes: G02F 1/133621 providing coloured light G02F1/133617, G02F1/133533 take precedence
• CPC Class Codes: G02F 1/133622 Colour sequential illumination
• CPC Class Codes: G09G 2310/0235 Field-sequential colour display
• CPC Class Codes: G09G 5/026 Control of mixing and/or overlay of colours in general G09G5/022 and G09G5/024 take precedence

Abstract

A color display device (210, 310, 410) includes a backlight (214, 414) that cyclically emits first, second, and third component color backlighting in turn over a cycle period. The cycle period repeats at a cycling frequency (f) that exceeds a maximum human visual response frequency. A liquid crystal display (LCD) (112, 312, 412) generates a first display during the first component color backlighting, a second display during the second component color backlighting, and a third display during the third component color backlighting.

Claims

1. A color display device including:

a light-transmissive liquid crystal display (LCD);

a backlight arranged to illuminate the light-transmissive LCD, the backlight including at least first color component light emitting diodes (first color component LEDs), second color component light emitting diodes (second color component LEDs), third color component light emitting diodes (third color component LEDs), and white color component light emitting diodes (white LEDs);

LED circuitry that cyclically alternates between powering the first color component LEDs to produce first color component backlighting, powering the second color component LEDs to produce second color component backlighting, powering the third color component LEDs to produce third color component backlighting, and powering the white LEDS to produce white light; and

LCD circuitry that updates a display shown on the LCD, the updates being synchronized with color changes of the backlight.

2. The color display device as set forth in claim 1, wherein the LCD is an active matrix LCD with light-transmissive pixels that pass light with substantially no change in color properties of the light.

3. The color display device as set forth in claim 1, wherein the first, second, and third color component LEDs emit primary colors.

4. The color display as set forth in claim 1, wherein the LCD circuitry includes liquid crystal control elements including thin film transistors.

5. The color display as set forth in claim 1, wherein the LED circuitry cyclically alternates the backlight with a cycle period that is less than a response time of a human eye.

6. The color display device as set forth in claim 1, wherein the first, second, and third color component LEDs and the white LEDs are arranged as an array of LED pixels, each LED pixel including a first color component LED, a second color component LED, a third color component LED, and a white LED, the LED pixels corresponding to pixels of the light-transmissive LCD.

7. The color display device as set forth in claim 1, wherein each LED of the backlight corresponds with a pixel of the light-transmissive LCD.