Imaging system for a head-mounted display

• US 5,406,415 A
• Filed: 09/22/1992
• Issued: 04/11/1995
• Est. Priority Date: 09/22/1992
• Status: Expired due to Term

• Current Assignee: Shawn L. Kelly
• Original Assignee: Shawn L. Kelly
• Inventors: Kelly, Shawn L.
• Primary Examiner(s): Ben, Loha
• Assistant Examiner(s): NGUYEN, THONG Q
• Application Number:
  US07/948,662
• Time in Patent Office: 931 Days
• Field of Search: 359/13-14, 359/227, 359/229, 359/362-366, 359/503-505, 359/601, 359/602, 359/608, 359/609, 359/614, 359/618, 359/630-634, 359/885, 359/888 , 359/891-894, 359/900, 359/559, 359/560, 359/561, 359/564, 359/637, 340/705, 340/980
• US Class Current: 359/633
• CPC Class Codes: G02B 2027/011 comprising device for correcting geometrical aberrations, distortion
• CPC Class Codes: G02B 2027/012 comprising devices for attenuating parasitic image effects
• CPC Class Codes: G02B 2027/0123 comprising devices increasing the field of view
• CPC Class Codes: G02B 2027/0127 comprising devices increasing the depth of field
• CPC Class Codes: G02B 2027/0143 the two eyes not being equipped with identical nor symmetrical optical devices
• CPC Class Codes: G02B 2027/0152 involving arrangement aiming to get lighter or better balanced devices
• CPC Class Codes: G02B 27/0025 for optical correction, e.g. distorsion, aberration
• CPC Class Codes: G02B 27/017 Head mounted
• CPC Class Codes: G02B 27/0172 characterised by optical features
• CPC Class Codes: G02B 27/46 Systems using spatial filters
• CPC Class Codes: G09B 9/307 by helmet-mounted projector or display G09B9/36 takes precedence; optical parts of head-up displays G02B27/01

Abstract

An imaging system (10) for a Head-Mounted Display (HMD) comprises a projection screen (22) integrally formed with a headgear structure of the HMD. An image source is projected onto the projection screen (22) as an intermediate image. An optical sub-system (24), such as a lens, re-images the intermediate image to form a virtual image as viewed by a user'"'"'s eye (26). The present invention provides improved imaging while reducing the weight and manufacturing cost of the HMD. In accordance with another aspect of the present invention, an optical spatial filter (28) is utilized in an HMD imaging system to remove unwanted image artifacts, and increase the depth of focus of an intermediate projected image.

Claims

1. An imaging system for a head-mounted display, said head-mounted display comprising a headgear structure to be worn on the head of a person, said imaging system comprising:

means for projecting a source image within the headgear structure;

an incurvate projection surface positioned within the headgear structure for displaying the projected source image; and

a first lens proximate the person'"'"'s eye for re-imaging the projected image displayed on said incurvate projection surface as a wide field virtual image, wherein said means for projecting a source image comprises a second lens having an aperture size sufficient to image the projected image onto the incurvate projection surface, said aperture size being independent of an exit pupil of said first lens.

2. The imaging system of claim 1 wherein said incurvate projection surface comprises an inner surface of said headgear structure.

3. The imaging system of claim 1 wherein said incurvate projection surface is integrally formed as part of the headgear structure.

4. An imaging system for a head-mounted display comprising:

means for projecting a source image;

a projection screen for displaying the projected source image;

means for re-imaging the projected image displayed by said projection screen as a virtual image for viewing by a person using the head-mounted display; and

an optical spatial filter located proximate said re-imaging means for decreasing artificial image artifacts in the virtual image, and increasing the depth of focus of the virtual image.

5. An imaging system for a head-mounted display comprising:

means for projecting a source image;

means for displaying the projected source image as a virtual image for viewing by a person using the head-mounted display; and

an optical spatial filter for decreasing artificial image artifacts in the virtual image, and for increasing the depth of focus of the virtual image.

6. The imaging system of claim 5 wherein said means for displaying the projected image source comprises a projection screen.

7. The imaging system of claim 6 wherein said head-mounted display comprises a headgear structure to be worn on the head of the viewer, and said projection screen is integrally formed as part of said headgear structure.

8. An imaging system for a head-mounted display comprising:

means for projecting a source image onto an image surface to form an intermediate image;

means for re-imaging the intermediate image as a virtual image for viewing by a person using the head-mounted display; and

an optical spatial filter for removing unwanted image artifacts from the virtual image.