Far-field display

• US 20040130797A1
• Filed: 10/07/2003
• Published: 07/08/2004
• Est. Priority Date: 04/07/2001
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Cambridge Flat Projection Displays Limited
• Inventors: Leigh Travis, Adrian Robert
• Granted Patent: US 6,847,488 B2
• Time in Patent Office: Days
• US Class Current: 359/631
• CPC Class Codes: G02B 2027/0123 comprising devices increasing the field of view
• CPC Class Codes: G02B 27/0081 with means for altering, e.g. enlarging, the entrance or exit pupil
• CPC Class Codes: G02B 27/0101 characterised by optical features G02B27/0172 takes precedence
• CPC Class Codes: G02B 30/27 involving lenticular arrays

Abstract

A flat-panel projection display comprises a transparent slab and integral area grating, a transparent rod with rectangular cross-section and integral linear grating, arranged along the edge of the slab, and a small video projector. The projector is arranged to direct a virtual image into the end of the rod, directly or via mirrors, the light travelling along the rod via total internal reflection. The linear grating diverts the light into the plane of the slab, and the area grating projects it out of the slab towards a viewer, so that the viewer sees an image at infinity.

Claims

1. A flat-panel projection display comprising a transparent slab element and corresponding area grating, a transparent rod element with rectangular cross-section and corresponding linear grating, arranged along the edge of the slab, and a small projector, in which the projector is arranged to direct the image into the end of the rod, the linear grating is adapted to divert it into the plane of the slab, and the area grating is adapted to project it out of the slab towards a viewer.

2. A flat-panel projection display according to claim 1, in which one of the gratings is a stack of transparent plates arranged at about 45°

to the incoming and outgoing light.

3. A flat-panel projection display according to claim 1, in which at least one of the gratings is embossed on the surface of the rod or the slab.

4. A flat-panel projection display according to claim 1, in which at least one of the gratings, preferably that on the slab, is holographic.

5. A flat-panel projection display according to claim 1, in which the rod and slab elements are made of glass.

6. A flat-panel projection display according to claim 1, further including mirrors arranged at the input end of the rod and parallel to its axis, so as to direct substantially the entire output of the projector into the rod.

7. A head-up display incorporating a flat-panel display as claimed in claim 1.

8. A wearable display including a flat-panel display as claimed in claim 1.