High throughput contrast enhancement for polarized displays

• US 5,066,108 A
• Filed: 12/22/1989
• Issued: 11/19/1991
• Est. Priority Date: 12/22/1989
• Status: Expired due to Term

• Current Assignee: Victor Company of Japan Limited (JVC Kenwood Corporation)
• Original Assignee: Hughes Aircraft Company (Rtx Corporation)
• Inventors: McDonald, Mark E.
• Primary Examiner(s): Hille, Rolf
• Assistant Examiner(s): Ho, Tan
• Application Number:
  US07/455,115
• Time in Patent Office: 697 Days
• Field of Search: 350/337, 350/338, 350/345, 350/347 E, 350/347 R, 350/384, 350/388, 350/403, 350/407, 350/352, 353/20, 353/122
• US Class Current: 349/97
• CPC Class Codes: G02F 1/133528 Polarisers

Abstract

A display having a linearly polarized image source, a quarter-wave retarder for transforming the linearly polarized illumination to circularly polarized illumination, imaging elements responsive to the circularly polarized illumination for producing viewable circularly polarized imaging illumination, and a circular imaging illumination to viewable linearly polarized imaging illumination. The circular polarizer includes a quarter-wave retarder for transforming the circular light to linearly polarized light, and a linear polarizer configured to transmit the linearly polarized imaging illumination. Contrast enhancement is achieved by the circular polarizer which functions to block ambient light reflected from the front element of the imaging elements as a result of transmission through the circular polarizer.

Claims

1. A polarized display comprising:

a display source for producing source imaging illumination that includes linearly polarized imaging illumination;

a first quarter-wave retarder having a fast axis for transforming the linearly polarized imaging illumination to circularly polarized imaging illumination;

a second quarter-wave retarder having a fast axis for transforming the circularly polarized imaging illumination to linearly polarized illumination having the same polarization orientation as the source imaging illumination, said second quarter-wave retarder having its fast axis oriented 90 degrees relative to the fast axis of said first quarter-wave retarder; and

a linear polarizer responsive to the linearly polarized imaging illumination provided by said second quarter-wave retarder for providing an image viewable by an observer of the display;

whereby said second quarter-wave retarder and said linear polarizer function to substantially block reflection that results from ambient light that passes through said second quarter-wave retarder and is reflected back through the second quarter-wave retarder toward said linear polarizer.

2. A polarized display comprising:

a display source for producing source imaging illumination that includes linearly polarized imaging illumination;

a first quarter-wave retarder having a fast axis for transforming the linearly polarized imaging illumination to circularly polarized imaging illumination;

a diffusion screen;

imaging means for imaging said circularly imaging illumination on to said diffusion screen which provides diffused circularly polarized imaging illumination;

a second quarter-wave retarder having a fast axis for transforming the diffused circularly polarized imaging illumination to linearly polarized illumination having the same polarization orientation as the source imaging illumination, said second quarter-wave retarder having its fast axis oriented 90 degrees relative to the fast axis of said first quarter-wave retarder; and

a linear polarizer responsive to the linearly polarized imaging illumination provided by said second quarter-wave retarder for providing an image viewable by an observer of the display;

whereby said second quarter-wave retarder and said linear polarizer function to substantially block reflection that results from ambient light that passes through said second quarter-wave retarder and is reflected back through the second quarter-wave retarder toward said linear polarizer.