Autostereoscopic display system

• US 6,351,280 B1
• Filed: 11/20/1998
• Issued: 02/26/2002
• Est. Priority Date: 11/20/1998
• Status: Expired due to Fees

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Benton, Stephen A.
• Primary Examiner(s): Le, Vu
• Application Number:
  US09/196,981
• Time in Patent Office: 1,194 Days
• Field of Search: 348/39-40, 348/42-44, 348/46-51, 348/54, 348/56-58, 348/59, 359/23, 359/458, 359/462-464, 359/466-467, 359/470, 345/6, 345/139
• US Class Current: 348/51
• CPC Class Codes: H04N 13/31 using parallax barriers
• CPC Class Codes: H04N 13/368 for two or more viewers
• CPC Class Codes: H04N 13/398 Synchronisation thereof; Control thereof

Abstract

An autostereoscopic display system is capable of tracking one or more users within a viewing zone and presenting complementary stereoimages to each of the viewer'"'"'s (or viewers'"'"') eyes. Polarization is used to segregate the images that are to be directed to different spatial regions. The two images are interdigitated within a single display—that is, each band of image points from the first image alternates with a band of image points from the second image on the display. The bands of the first image are polarized in a first mode and the bands of the second image are polarized in a second mode orthogonal to the first, e.g., through use of a liquid-crystal display (LCD) in which alternating, contiguous bands of pixels correspond to bands of one or the other image, and a “patterned polarizer” also organized into bands and aligned with the pixel bands. Autostereoscopic viewing is facilitated by a display (such as an LCD) that is illuminated by light from an outside source whose polarization can be controlled. Illumination from the light source passes through a focusing lens and then through the patterned polarizer and display so as to form a “real” or “aerial” image of the display in the viewing zone, with the different images directed to different regions of the viewing zone.

Claims

1. Apparatus for presenting a plurality of images, the apparatus comprising:

a. means for establishing a target zone for a first image;

b. means for generating a tracking output image, the output image comprising a first region of light polarized in a first polarization mode and substantially correlated to the target zone, and a second region of light polarized in a second polarization mode distinct from the first polarization mode;

c. a display for receiving light from the tracking output image to produce first and second images, each of the images comprising a series of bands, the first-image bands alternating contiguously with the second-image bands;

d. means for polarizing light illuminating the first image in a first polarization mode; and

e. means for polarizing light illuminating the second image in a second polarization mode, the first and second polarization modes being orthogonal to each other, the light from the tracking output image being directed so as to cause the first image to appear in the target zone and the second image to appear elsewhere.

2. The apparatus of claim 1 wherein:

a. the means for establishing a target zone comprises viewer-locating means for acquiring a facial image fragment of a viewer, the facial image fragment including a first one of the viewer'"'"'s eyes;

b. the first region of light is correlated to the facial image fragment;

c. the first and second image sources produce complementary stereoimages; and

d. the means for causing the light from the tracking output image to illuminate the display image sources causes the first region of light to be focused onto a corresponding portion of the viewer'"'"'s face through the display such that the first image is presented to the first eye of the viewer and the second image source to the other eye of the viewer.

3. The apparatus of claim 2 wherein the means for directing the tracking output image comprises a lens, the target zone being located a distance away from the lens, the lens forming a real image at the distance through the display.

4. The apparatus of claim 1 wherein the means for generating a tracking output image comprises:

a. an illumination source; and

b. a display comprising (i) a polarizer to pre-condition light from the illumination source into a single polarization mode, and (ii) a polarization-altering medium, the medium altering the polarization of light between first and second polarization modes in response to an externally applied stimulus, the medium being arranged in a pattern of cells each addressably responsive to the stimulus, the polarizer intervening between the illumination source and the polarization-altering medium.

5. The apparatus of claim 4 wherein the means for polarizing light illuminating the first image in a first polarization mode and the means for polarizing light illuminating the second image in a second polarization mode are, collectively, (i) a patterned half-wave retarder comprising sets of alternating bands, a first set of bands rotating the polarization of light by 90°

and being aligned with the bands of the first image, and a second set of bands not affecting the polarization of light and being aligned with the bands of the second image, and (ii) a polarizer aligned with the pre-conditioning polarizer.

6. The apparatus of claim 4 wherein the means for polarizing light illuminating the first image in a first polarization mode and the means for polarizing light illuminating the second image in a second polarization mode are, collectively, (i) a patterned half-wave retarder comprising sets of alternating bands, a first set of bands not affecting the polarization of light and being aligned with the bands of the first image, and a second set of bands rotating the polarization of light by 90°

and being aligned with the bands of the second image, and (ii) a polarizer aligned with the pre conditioning polarizer.

7. The apparatus of claim 1 wherein the means for polarizing light illuminating the first image in a first polarization mode and the means for polarizing light illuminating the second image in a second polarization mode are, collectively, a patterned polarizer having sets of alternating bands, a first set of bands polarizing light in the first polarization mode and being aligned with the bands of the first image, a second set of bands polarizing light in the second polarization mode and being aligned with the bands of the second image.

13. The method of claim 4 wherein the polarizing steps are performed by a patterned half-wave retarder comprising sets of alternating bands, a first set of bands not affecting the polarization of light and being aligned with the bands of the first image, and a second set of bands rotating the polarization of light by 90°

and being aligned with the bands of the second image, and (ii) a polarizer aligned with the pre-conditioning polarizer.

8. A method of for presenting a plurality of images, the method comprising the

a. establishing a target zone for a first image;

b. generating a tracking output image image comprising a first region of light polarized in a first polarization mode and substantially correlated to the target zone, and a second region of light polarized in a second polarization mode distinct from the first polarization mode;

c. providing a display for receiving light to produce first and second images, each of the images comprising a series of bands, the first-image bands alternating contiguously with the second-image bands;

d. causing light from the tracking output image to illuminate the display;

e. polarizing the light illuminating the first image in a first polarization mode;

f. polarizing the light illuminating the second image in a second polarization mode, the first and second polarization modes being orthogonal to each other; and

g. causing the first image to appear in the target zone and the second image to appear elsewhere.

9. The method of claim 8 wherein the first and second image sources produce complementary stereoimages, and further comprising the steps of:

a. acquiring a facial image fragment of a viewer, the facial image fragment including a first one of the viewer'"'"'s eyes;

b. correlating the first region of light to the facial image fragment;

c. causing the first region of light to be focused onto a corresponding portion of the viewer'"'"'s face through the display such that the first image is presented to the first eye of the viewer and the second image source to the other eye of the viewer.

10. The method of claim 8 wherein the tracking output image is generated according to steps comprising:

a. pre-conditioning light from an illumination source into a single polarization mode, and

b. selectively altering the polarization of light between first and second polarization modes.

11. The method of claim 10 wherein the polarizing steps are performed by a patterned half-wave retarder comprising sets of alternating bands, a first set of bands rotating the polarization of light by 90°

and being aligned with the bands of the first image, and a second set of bands not affecting the polarization of light and being aligned with the bands of the second image, and (ii) a polarizer aligned with the pre-conditioning polarizer.

12. The method of claim 8 wherein the polarizing steps are performed by a patterned polarizer having sets of alternating bands, a first set of bands polarizing light in the first polarization mode and being aligned with the bands of the first image, a second set of bands polarizing light in the second polarization mode and being aligned with the bands of the second image.