Virtual image display system

• US 5,305,124 A
• Filed: 04/07/1992
• Issued: 04/19/1994
• Est. Priority Date: 04/07/1992
• Status: Expired due to Term

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Hughes Aircraft Company (Rtx Corporation)
• Inventors: Stringfellow, Steve A., Newberg, Howard S., Chern, Mao J.
• Primary Examiner(s): Arnold, Bruce Y.
• Assistant Examiner(s): SHAFER, RICKY D
• Application Number:
  US07/864,861
• Time in Patent Office: 742 Days
• Field of Search: 359/13, 359/15, 359/630, 359/631, 359/633, 359/634, 359/858, 359/14, 340/705
• US Class Current: 359/13
• CPC Class Codes: G02B 17/023 for extending or folding an optical path, e.g. delay lines
• CPC Class Codes: G02B 2027/0118 comprising devices for improving the contrast of the display / brillance control visibility
• CPC Class Codes: G02B 2027/0194 with combiner of laminated type, for optical or mechanical aspects
• CPC Class Codes: G02B 27/0101 characterised by optical features G02B27/0172 takes precedence
• CPC Class Codes: H04N 5/7408 Direct viewing projectors, e.g. an image displayed on a video CRT or LCD display being projected on a screen

Abstract

A virtual image display system for displaying a relatively large virtual image to a user derived from a relatively small image source. A lens group is provided for amplifying an image provided by the image source. A plurality of reflecting elements are provided for magnifying the image provided by the lens group and for displaying the relatively large virtual image. Several embodiments are provided that include on-axis and off-axis reflecting versions, and a holographic virtual image version. Conventional lenses and reflecting optics are used to provide the on- and off-axis versions of the system, while a holographic reflecting element is used to provide a holographic virtual image. A window element may also be employed to minimize ambient reflection viewed by the user and eliminates ambient reflection to reduce the user'"'"'s eye fatigue. The display system improves a user'"'"'s viewing comfort by positioning the image at a distance matching the visual requirements of the user'"'"'s eye. The large image size also improves the legibility and readability of the display. The present system is especially useful for computer monitor or TV applications and the color version is useful in applications where selected colors are to be highlighted.

Claims

1. A virtual image display system for displaying a relatively large virtual image to a user, said system comprising:

a relatively small image source for providing an image that is to be viewed by the user;

a concave reflecting mirror;

a lens group for amplifying the image provided by the image source, and for projecting the image by way of the concave reflecting mirror at a comfortable viewing distance relative to the user; and

a magnifying optical system comprising the concave reflecting mirror and further comprising a holographic mirror wherein the holographic mirror comprises two holographic mirror elements having respective predetermined optical powers for different wavelength to provide for a three dimensional display system.

2. The virtual image display system of claim 1 wherein the holographic mirror elements are coherent mirror elements.

3. The virtual image display system of claim 1 wherein the holographic mirror elements are incoherent mirror elements.