Scanning backlight for flat-panel display

• US 20060132423A1
• Filed: 06/04/2004
• Published: 06/22/2006
• Est. Priority Date: 06/06/2003
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Cambridge Flat Projection Displays Limited
• Inventors: Travis, Adrian Robert Leigh
• Granted Patent: US 7,944,428 B2
• Time in Patent Office: Days
• US Class Current: 345/102
• CPC Class Codes: G02B 6/002 by shaping at least a portion of the light guide, e.g. with collimating, focussing or diverging surfaces
• CPC Class Codes: G02B 6/0031 Reflecting element, sheet or layer
• CPC Class Codes: G02F 1/133601 for spatial active dimming
• CPC Class Codes: G02F 1/133615 Edge-illuminating devices, i.e. illuminating from the side
• CPC Class Codes: G09G 2310/0235 Field-sequential colour display
• CPC Class Codes: G09G 2310/024 Scrolling of light from the illumination source over the display in combination with the scanning of the display screen
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• 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

An illuminator for a flat-panel display comprises a tapered slab waveguide 1 co-extensive with the display, a light source 2-4 arranged to inject light into an edge of the waveguide so that it emerges over the face of the waveguide, and means for scanning the light injected into the wedge so that different areas of the panel are illuminated in turn. Preferably the light source is a set of rows of LEDs, each row injecting light at a different range of angles so that it emerges over different areas of the waveguide 1.

Claims

1. An illuminator for a flat-panel display, comprising a tapered slab waveguide (1) co-extensive with the display, a light source (2-4) arranged to inject light into an edge of the waveguide so that it emerges over the face of the waveguide, and means for scanning the light injected into the wedge.

2. An illuminator according to claim 1, in which the light source consists of addressable rows of elements, and the scanning means includes a circuit for addressing these rows.

3. An illuminator according to claim 2, in which the light from the elements is collimated into the display waveguide by a cylindrical mirror (5).

4. An illuminator according to claim 2, in which the light from the elements is collimated into the display waveguide by a further waveguide (8).

5. An illuminator according to claim 2, in which the elements are LEDs.

6. Amended) An illuminator according to claim 1, further including a sheet (6) for guiding the emerging light towards the normal to the display waveguide.

7. A display comprising an illuminator according to claim 1, used as a backlight, and a flat-panel modulator over the display waveguide.

8. A display according to any claim 7, in which the modulator is a liquid-crystal display.

9. A display according to claim 2, in which the scanning addressing circuit is synchronized with the row addressing circuit of the LCD.