Liquid crystal display projection system having improved contrast

• US 5,048,931 A
• Filed: 07/13/1989
• Issued: 09/17/1991
• Est. Priority Date: 11/01/1988
• Status: Expired due to Fees

• Current Assignee: North American Philips Corp. (Koninklijke Philips N.V.)
• Original Assignee: North American Philips Corp. (Koninklijke Philips N.V.)
• Inventors: Magocs, Stephen
• Primary Examiner(s): Miller, Stanley D.
• Assistant Examiner(s): Phan, Trong
• Application Number:
  US07/380,699
• Time in Patent Office: 796 Days
• Field of Search: 350/337, 350/342, 350/345, 350/117, 353/20, 353/79, 353/122, 358/61, 358/232
• US Class Current: 349/5
• CPC Class Codes: G02F 1/133528 Polarisers
• CPC Class Codes: H04N 9/3167 for polarizing the light beam polarizing optical systems per se G02B27/28

Abstract

For enhancing the contrast of a picture on a projection scrren derived from a liquid crystal display, the analyzer, which is normally part of the liquid display unit, is incorporated either in front of or in back of the screen relative to the viewing area or may constitute a layer between the front and rear portion of the screen. In any of these positions, the presence of the analyzer will result in darker portions and therefore in enhanced contrast. When it is used in front of the screen relative to the viewing area, protection of the lenticular surface also results.

Claims

1. An electro-optical display system comprising:

an illumination source furnishing light rays;

polarization changing means, for changing the polarization of light in response to a control signal, positioned in the path of said light rays so that said polarization changing means furnishes polarization output light comprising first polarized light in the absence of said control signal and second polarized light in response to said control signal;

means for applying said control signal to said polarization changing means in accordance with information to be displayed;

display means having a first side for displaying said information and a second side substantially parallel to said first side; and

analyzer means positioned to receive said first polarized light and said second polarized light and furnishing only said second polarized light in response thereto, said analyzer means being laminated to said display means.

2. An electro-optical display system as set forth in claim 1, wherein said analyzer means is laminated to said first side of said display means.

3. A electro-optical display system as set forth in claim 1, wherein said analyzer means is laminated to said second side of said display means.

4. An electro-optical display system as set forth in claim 1, wherein said analyzer means forms a layer between said first and second sides of said display means.

5. An electro-optical display system as set forth in claim 2, wherein said display means comprises lenticules on said first side, whereby said analyzer means further constitutes protection for said lenticules.

6. An electro-optical display system as set forth in claim 1, wherein said illumination source comprises a lamp emitting light and polarizer means positioned in the path of said light for polarizing said light thereby creating said light rays.

7. An electro-optical display system as set forth in claim 6, wherein said light rays constitute said first polarized light.

8. An electro-optical display system as set forth in claim 1, wherein said polarization changing means comprises at least one liquid crystal.

9. An electro-optical display system comprising:

an illumination source furnishing light rays;

polarization changing means positioned in the path of said light rays for furnishing output light comprising first polarized light in the absence of a control signal and second polarized light, having a polarization different from said first polarized light, in response to a control signal;

means for furnishing said control signal to said polarization changing means in accordance with information to be displayed;

display means having a first side for furnishing a visual display corresponding to said information to be displayed and a second side substantially parallel to said first side;

lens means arranged in the path of said output light for directing said output light onto said display means; and

analyzer means disposed between said lens means and said display means for receiving said first polarized light and said second polarized light from said lens means and furnishing only said second polarized light to said display means for display thereon, said analyzer means being laminated to said display means.

10. An electro-optical display system as set forth in claim 9, wherein said lens means comprises projection lens means, and wherein said display means is the screen of a projection television.