OPTICAL DISPLAY SYSTEMS

• US 3,620,592 A
• Filed: 06/29/1970
• Issued: 11/16/1971
• Est. Priority Date: 07/03/1969
• Status: Expired due to Term

• Current Assignee: N/A
• Original Assignee: N/A
• Primary Examiner(s): David Schonberg
• Assistant Examiner(s): Ronald J. Stern
• Application Number:
  US05/050,836
• Time in Patent Office: 505 Days
• Field of Search: 350/169,174,9,103,104,55 35/12N 353/99,28,11,12 178/7.85,7.88 356/251,252
• US Class Current: 359/631
• CPC Class Codes: G02B 27/0101 characterised by optical features G02B27/0172 takes precedence
• CPC Class Codes: G09B 9/32 by projected image G09B9/307, G09B9/36 take precedence

Abstract

Collimated light carrying visual information is projected via a partial reflector on to a reflex-reflector which returns the light to the partial reflector for viewing by an observer who sees an image of the visual information at infinity. A flight simulator and a head-up display apparatus employing this system are described.

Claims

1. An optical system for displaying visual information comprising projection means adapted to project collimated light carrying information to be displayed, partial reflector means positioned to receive light from the projection means, and reflex-reflector means positioned to receive light from the partial reflector means and adapted to reflect light incident on the reflex-reflector means in a direction opposite to its direction of incidence back towards the partial reflector means so that an observer viewing in a direction towards the partial reflector means can see an image, which appears at infinity, of said information.

2. An optical system as claimed in claim 1 wherein said partial reflector means and said reflex-reflector means are so disposed that light from the projection means is reflected by the partial reflector means towards the reflex-reflector means, and light reflected from the reflex-reflector means is transmitted through the partial reflector means towards the observer.

3. An optical system as claimed in claim 1 wherein said reflex-reflector means is adapted to maintain an angular relationship between an incident and a reflected ray of less than 5 milliradians.

4. An optical system as claimed in claim 3 wherein said reflex-reflector means comprises an array of lenses arranged in front of concave mirrors.

5. An optical system as claimed in claim 3 wherein said reflex-reflector means comprises an array of corner-cube reflectors.

6. An optical system as claimed in claim 1 wherein said projection means is arranged to project diverging beams of collimated light, and said reflex-reflector means is arranged to return the light in converging mode.

7. An optical system as claimed in claim 1 wherein said partial reflector means and said reflex-reflector means are so disposed that light from the projection means is transmitted through the partial reflector means towards the reflex-reflector means, and light reflected from the reflex-reflector means is reflected by the partial reflector means towards the observer.

8. An optical sysTem for displaying visual information to an observer comprising primary projection means adapted to project light carrying information to be displayed, primary partial reflector means positioned to receive light from the primary projection means, primary reflex-reflector means positioned to receive light from the primary partial reflector means so that an image of the information is formed on the primary reflex-reflector means, the latter being adapted to reflect light incident thereon generally in a direction opposite to the direction of incidence but to effect divergence of the reflected light such that diverging light bundles are reflected from each image point, secondary projection means positioned to receive said diverging light bundles and to project collimated light, secondary partial reflector means positioned to receive light from the secondary projection means, and secondary reflex-reflector means positioned to receive light from the secondary partial reflector means, said secondary reflex-reflector means being adapted to reflect light incident thereon in a direction opposite to the direction of incidence back towards said secondary partial reflector means so that an observer viewing in a direction towards said secondary partial reflector means can see an image, which appears to be at infinity, of said information.

9. An optical system as claimed in claim 8 wherein said primary reflex-reflector means comprises a beaded screen.

10. An optical system as claimed in claim 8 wherein the primary partial reflector means and the primary reflex-reflector means are so disposed that light from the primary projection means is reflected from the primary partial reflector means towards the primary reflex-reflector means, and light reflected from the latter is transmitted through the primary partial reflector means to the secondary projection means.

11. An optical system as claimed in claim 8 wherein the secondary partial reflector means and the secondary reflex-reflector means are so disposed that light from the secondary projection means is reflected from the secondary partial reflector means towards the secondary reflex-reflector means, and light reflected from the latter is transmitted through the secondary partial reflector means to the observer.

12. An optical system as claimed in claim 8 wherein said primary reflex-reflector means is adapted to effect a divergence of at least 10* of light reflected therefrom.

13. An optical system as claimed in claim 8 wherein said primary reflex-reflector means is adapted to effect a divergence of no more than 30* of light reflected therefrom.

14. An optical system as claimed in claim 8 wherein said secondary reflex-reflector means is adapted to maintain an angular relationship between an incident and a reflected ray of less than 5 milliradians.