Intensified visual display

• US 5,903,396 A
• Filed: 10/17/1997
• Issued: 05/11/1999
• Est. Priority Date: 10/17/1997
• Status: Expired due to Fees

• Current Assignee: i-O Display Systems LLC (Ilixco, Inc.)
• Original Assignee: i-O Display Systems LLC (Ilixco, Inc.)
• Inventors: Rallison, Richard Dennis
• Primary Examiner(s): Spyrou, Cassandra
• Assistant Examiner(s): Schuberg, Darren E.
• Application Number:
  US08/953,093
• Time in Patent Office: 571 Days
• Field of Search: 359/13, 359/14, 359/495, 359/497, 359/629, 359/630, 359/631, 359/487, 345/7, 345/8, 345/9
• US Class Current: 359/630
• CPC Class Codes: G02B 2027/0118 comprising devices for improving the contrast of the display / brillance control visibility
• CPC Class Codes: G02B 27/0101 characterised by optical features G02B27/0172 takes precedence
• CPC Class Codes: G02B 5/30 Polarising elements light-modulating devices with active elements G02F1/00

Abstract

The intensified visual display relates to visual displays which combine generated images with the view of the environment surrounding a user and transmit such combined visual information to the eye position of the user. A fold mirror (1) frequently utilized in such displays reflects only a fraction of the light striking it and, similarly, transmits only a different fraction of the light reaching it. The fold mirror (1) will reflect a maximum amount of light when such light is S polarized and transmit a maximum amount of light when the light is P polarized. If the image generator produces S polarized light, one quarter-wave plate (3) is used to assure that image light to be reflected by the fold mirror (1) is S polarized while image light to be transmitted through the fold mirror (1) is P polarized. If the image generator produces P polarized light, a first quarter-wave plate (31) and a second quarter-wave plate (32) are employed.

Claims

1. An intensified user-mounted visual display comprising:

an image generator that produces S polarized light;

a fold mirror wherein said fold mirror is located with respect to said image generator to receive S polarized image light from said image generator without passing said S polarized image light through a relay lens between said image generator and said fold mirror and to reflect such S polarized image light;

a quarter-wave plate positioned so that the S polarized image light reflected from the fold mirror is transmitted through said quarter-wave plate and retarded by one-quarter wave in order to exit the quarter-wave plate as circularly polarized image light; and

a reflective combiner situated to receive the circularly polarized image light from the quarter-wave plate, reflect such circularly polarized image light, combine such circularly polarized image light with environmental light rays transmitted through said reflective combiner from the surrounding environment, and transmit the combined environmental light rays and circularly polarized image light though the quarter-wave plate, which again retards the circularly polarized image light by one-quarter wave so that it exits the quarter-wave plate as P polarized image light which then passes through the fold mirror with the environmental light rays and subsequently reaches the eye position of the user, as also do the environmental light rays with which the image light has been combined.

2. The intensified visual display as recited in claim 1, wherein:

the quarter-wave plate is attached to the reflective combiner.

3. A user-mounted intensified visual display comprising:

an image generator that produces P polarized light;

a first quarter-wave plate located so that the P polarized image light from said image generator is transmitted through said first quarter-wave plate and retarded by one-quarter wave in order to exit the first quarter-wave plate as circularly polarized image light;

a second quarter-wave plate positioned so that the circularly polarized image light from the first quarter-wave plate is transmitted through said second quarter-wave plate and retarded by one-quarter wave in order to exit the second quarter-wave plate as S polarized image light;

a fold mirror wherein said fold mirror is situated with respect to said image generator to receive the S polarized image light from the second quarter-wave plate without passing through a relay lens between said image generator and said fold mirror and to reflect such S polarized image light through the second quarter-wave plate where the S polarized image light will again be retarded by one quarter-wave and, consequently, exit said second quarter-wave plate as circularly polarized image light; and

a reflective combiner placed to receive the circularly polarized image light from the second quarter-wave plate, reflect such circularly polarized image light, combine such circularly polarized image light with light rays transmitted through the reflective combiner from the surrounding environment, and transmit the combined environmental light rays and circularly polarized image light through the second quarter-wave plate, which again retards the circularly polarized image light by one-quarter wave so that it exits the second quarter-wave plate as P polarized image light which then passes through the fold mirror with the environmental light rays and subsequently reaches the eye position of the user, as also do the environmental light rays with which the image light has been combined.

4. The intensified visual display as recited in claim 3, wherein:

the second quarter-wave plate is laminated to the fold mirror.

5. A process for intensifying the image light transmitted to the eye position of the user of a user mounted visual display comprising:

producing image light by an image generator wherein said image light is S polarized

locating a fold mirror with respect to said image generator to receive S polarized image light from the image generator without passing through a relay lens between said image generator and said fold mirror to reflect such S polarized image light;

positioning a quarter-wave plate so that the S polarized image light reflected from the fold mirror is transmitted through said quarter-wave plate and retarded by one-quarter wave in order to exit the quarter-wave plate as circularly polarized image light; and

situating a reflective combiner to receive the circularly polarized image light from the quarter-wave plate, reflect such circularly polarized image light, combine such circularly polarized image light with light rays transmitted through said reflective combiner from the surrounding environment, and transmit the combined environmental light rays and circularly polarized image light through the quarter-wave plate, which again retards the circularly polarized image light by one-quarter wave so that it exits the quarter-wave plate as P polarized image light which then passes through the fold mirror with the environmental light rays and subsequently reaches the eye position of the user, as also do the environmental light rays with which the image light has been combined.

6. The process for intensifying the image light transmitted to the eye position of the user of a visual display when the image light produced by the image generator with which the process is used is S polarized, as recited in claim 5, further comprising:

attaching the quarter-wave plate to the reflective combiner.

7. A process for intensifying the image light transmitted to the eye position of the user of a user-mounted visual display comprising:

producing image light by an image generator wherein said image light is P polarized;

locating a first quarter-wave plate so that the P polarized image light from an image generator is transmitted through said first quarter-wave plate and retarded by one-quarter wave in order to exit the first quarter-wave plate as circularly polarized image light;

positioning a second quarter-wave plate so that the circularly polarized image light from the first quarter-wave plate is transmitted through said second quarter-wave plate and retarded by one-quarter wave in order to exit the second quarter-wave plate as S polarized image light;

situating a fold mirror to receive the S polarized image light from the second quarter-wave plate without passing through a relay lens between said image generator and said fold mirror and to reflect such S polarized image light through the second quarter-wave plate where the S polarized image light will again be retarded by one quarter-wave and, consequently, exit said second quarter-wave plate as circularly polarized image light; and

placing a reflective combiner to receive the circularly polarized image light from the second quarter-wave plate, reflect such circularly polarized image light, combine such circularly polarized image light with light rays transmitted through the reflective combiner from the surrounding environment, and transmit the combined environmental light rays and circularly polarized image light through the second quarter-wave plate, which again retards the circularly polarized image light by one-quarter wave so that it exits the second quarter-wave plate as P polarized image light which then passes through the fold mirror with the environmental light rays and subsequently reaches the eye position of the user, as also do the environmental light rays with which the image light has been combined.

8. The process for intensifying the image light transmitted to the eye position of the user of a visual display when the image light produced by the image generator with which the process is used is P polarized, as recited in claim 7, further comprising:

laminating the second quarter-wave plate to the fold mirror.

9. User-mounted apparatus for providing image light comprising:

an image generator;

a fold mirror which has greater transmissivity for light of a first polarity than for light of a second polarity, said fold mirror positioned, with respect to said image generator, to receive, from said image generator, image light substantially in said second polarity without passing through a relay lens between said image generator and said fold mirror and to reflect said image light in a first reflected direction;

a reflector positioned to receive image light reflected from said fold mirror and redirect at least a portion in a second reflected direction towards said fold mirror;

a polarization converter positioned to change the polarization of image light such that image light redirected from said reflector toward said fold mirror is substantially in said first polarity upon reaching said fold mirror for transmission of at least a portion of said image light through said fold mirror for subsequent transmission to a user'"'"'s eye.

10. Apparatus, as claimed in claim 9, wherein said first polarization is S and said second polarization is P.

11. Apparatus, as claimed in claim 9, wherein said first polarization is P and said second polarization is S.

12. Apparatus, as claimed in claim 9, wherein said reflector is partially transmissive to provide for combining environmental light with said image light.

13. Apparatus, as claimed in claim 9, wherein said polarization converter includes a waveplate.

14. Apparatus, as claimed in claim 9, wherein said polarization converter includes a holographic optical element.

15. Apparatus, as claimed in claim 9, wherein said polarization converter includes a non-holographic optical element.

16. User-mounted apparatus for providing image light to a user'"'"'s eye comprising:

an image generator;

first light direction-changing means positioned, with respect to said image generator, to receive image light from said image generator without passing through a relay lens between said image generator and said fold mirror and to reflect said image light in a first reflected direction wherein said direction changing means has at least partial transmissivity and which has greater transmissivity for light of a first polarity than for light of a second polarity wherein said image light, when received at said first light direction-changing means from said image generator, is substantially in said second polarity;

second light direction changing means positioned to receive image light reflected from said first direction changing means and redirect at least a portion in a second reflected direction towards said first direction-changing means;

means for changing the polarization of image light such that image light redirected from said second direction-changing means toward said first direction-changing means is substantially in said first polarity upon reaching said first direction-changing means for transmission of at least a portion of said image light through said first light direction-changing means for subsequent transmission to a user'"'"'s eye.

17. Apparatus as claimed in claim 16, wherein said first direction-changing means include a fold mirror.

18. Apparatus as claimed in claim 16, wherein said second direction-changing means is partially transmissive to provide for combining environmental light with said image light.

19. Apparatus, as claimed in claim 16, wherein said second direction-changing means is substantially reflective to substantially avoid combining environmental light with said image light.

20. A method for conveying light to a user'"'"'s eye, comprising:

providing an image generator;

providing a first reflector which has greater transmissivity for light of a first polarity than for light of a second polarity;

positioning said first reflector with respect to said image generator so as to receive at least a portion of image light from said image generator without passing through a relay lens, said image light having substantially said second polarity, and reflect said image light in a first reflected direction, using said first reflector;

redirecting said image light toward said first reflector;

changing the polarization of image light such that image light redirected toward said first reflector is substantially in said first polarity upon reaching said first reflector for transmission of at least a portion of said image light through said first reflector for subsequent transmission to a user'"'"'s eye.