Color selectable liquid crystal display system

• US 4,867,536 A
• Filed: 04/21/1988
• Issued: 09/19/1989
• Est. Priority Date: 02/05/1986
• Status: Expired due to Fees

• Current Assignee: Ford Motor Company
• Original Assignee: Ford Motor Company
• Inventors: Porter, Frederick J., Pidsosny, Richard A.
• Primary Examiner(s): Miller, Stanley D.
• Assistant Examiner(s): Pellman, Anita E.
• Application Number:
  US07/184,568
• Time in Patent Office: 516 Days
• Field of Search: 350/335, 350/337, 350/338, 350/339 F, 350/334, 350/341, 350/388, 350/408
• US Class Current: 349/78
• CPC Class Codes: G02F 1/133533 Colour selective polarisers G02F1/1347 takes precedence
• CPC Class Codes: G02F 1/13473 for wavelength filtering or for colour display without the use of colour mosaic filters
• CPC Class Codes: G02F 1/1396 the liquid crystal being selectively controlled between a twisted state and a non-twisted state, e.g. TN-LC cell G02F1/141 takes precedence

Abstract

A system in which several colors of the spectrum are selectable to be displayed having common polarity and with high contrast against a black background, utilizing liquid crystal cells along with linear and color polarizers disposed along an optical axis so that comparable results in either reflective or transmissive modes are achieved, with appropriate light sources.

Claims

1. A selectable color display system comprising:

means providing a source of electrical energy suitable for establishing an energization field in liquid crystal cells;

a first liquid crystal display cell means containing a twisted nematic liquid composition having defined front and back surfaces for passing light therethrough;

a common electrode disposed on one surface thereof and a segmented electrode disposed on the opposite surface for defining an energizable area adjacent to a deenergized area of said cell when said electrodes are selectively connected to said source;

a first linear polarizer means disposed adjacent said front surface of said first liquid crystal cell means for passing only those components of light polarized in a plane parallel to a first plane of polarization;

a second linear polarizer means disposed adjacent said back surface of said first liquid crystal cell means for passing only those components of light polarized in a plane parallel to said first plane of polarization;

a second liquid crystal cell means having defined front and back surfaces with said front surface disposed adjacent said second polarizer means opposing said back surface of said first liquid crystal display cell means and also having electrodes disposed thereon for establishing at least one area that is selectively energizable and deenergizable by said source;

a first color polarizer means adjacent the defined back surface of said second liquid crystal cell, for passing predetermined components of light of a defined first relatively narrow band of light frequencies to define a predetermined first color polarized in a plane parallel to said first plane of polarization and for passing predetermined components of light of a defined separate second band of light frequencies polarized in a plane of polarization orthogonal to said first plane of polarization, and thereby allowing orthogonally polarized bands of light frequencies to be passed to the defined back surface of said second liquid crystal display cell,

whereby the energization and deenergization of said first and second liquid crystal cells provides corresponding selection between said first and second bands of light frequencies to be transmitted only through the energized area of said first liquid crystal cell and said first linear polarizer.

2. A system as in claim 1, wherein said deenergized areas of said first liquid crystal cell means appear as black when viewed through said first linear polarizer means against said selectable bands of light frequencies in said energized areas of said first liquid crystal cell means.

3. A system as in claim 1, wherein said color polarizer means includes a pair of dichroic polarizer films each providing light absorption of separate portions of the visible spectrum having polarization components parallel to a predetermined color absorption plane, disposed in tandem with and behind the back surface of said second liquid crystal cell means and having respective planes of color absorption disposed orthogonally to each other, wherein one of said planes of color absorption is parallel to said first plane.

4. A system as in claim 1, wherein said color polarizer means includes a pair of dichroic polarizer films each providing light absorption of a portion of the visible spectrum having polarization components parallel to a predetermined color absorption plane, and a third liquid crystal cell means disposed between said films and having front and back surfaces with electrodes disposed thereon for establishing at least one area that is selectively energizable and deenergizable by said source.

5. A system as in claim 4, wherein said films are disposed so that their respective planes of color absorption are parallel to each other.

6. A system as in claim 5, wherein said planes of color absorption are parallel to said first plane of polarization.

7. A selectable color display system comprising:

means providing a source of electrical energy suitable for establishing an energization field in liquid crystal cells;

a first liquid crystal display cell means containing a twisted nematic liquid composition having defined front and back surfaces for passing light therethrough;

a common electrode disposed on one surface thereof and a segmented electrode disposed on the opposite surface for defining an energizable area adjacent to a deenergized area of said cell when said electrodes are connected to said source;

a first linear polarizer means disposed adjacent said front surface of said first liquid crystal cell means for passing only those components of light polarized in a plane parallel to a first plane of polarization;

a second linear polarizer means disposed adjacent said back surface of said first liquid crystal cell means for passing only those components of light polarized in a plane orthogonal to said first plane of polarization;

a second liquid crystal cell means having defined front and back surfaces with said front surface disposed adjacent said second polarizer means opposing said back surface of said first liquid crystal display cell means and also having electrodes disposed thereon for establishing at least one area that is selectively energizable and deenergizable by said source;

a first color polarizer means adjacent the defined back surface of said second liquid crystal cell, for passing predetermined components of light of a defined first relatively narrow band of light frequencies to define a predetermined first color polarized in a plane parallel to said first plane of polarization and for passing predetermined components of light of a defined separate second band of light frequencies polarized in a plane of polarization orthogonal to said first plane of polarization, and thereby allowing orthogonally polarized bands of light frequencies to be passed to the defined back surface of said second liquid crystal display cell,

whereby the energization and deenergization of said first and second liquid crystal cells provides corresponding selection between said first and second bands of light frequencies to be transmitted only through the deenergized area of said first liquid crystal cell and said first linear polarizer.

8. A system as in claim 7, wherein said energized areas of said first liquid crystal cell means appear as black when viewed through said first linear polarizer means against said selectable colors in said deenergized areas of said first liquid crystal cell means.