Illuminator for reflective dichroic liquid crystal displays

• US 4,212,048 A
• Filed: 06/16/1978
• Issued: 07/08/1980
• Est. Priority Date: 06/16/1978
• Status: Expired due to Term

• Current Assignee: Ametek Aerospace Products, Inc. (Ametek Incorporated)
• Original Assignee: General Electric Company
• Inventors: Castleberry, Donald E.
• Primary Examiner(s): Engle, Samuel W.
• Assistant Examiner(s): Walsh, Donald P.
• Application Number:
  US05/916,137
• Time in Patent Office: 753 Days
• Field of Search: 362/19, 362/301, 362/339, 350/337, 350/338, 350/345, 350/352
• US Class Current: 362/19
• CPC Class Codes: G02B 6/0056 for producing polarisation effects, e.g. by a surface with polarizing properties or by an additional polarizing elements
• CPC Class Codes: G02F 1/133615 Edge-illuminating devices, i.e. illuminating from the side
• CPC Class Codes: G02F 1/133616 Front illuminating devices
• CPC Class Codes: G02F 1/13362 providing polarized light, e.g. by converting a polarisation component into another one
• CPC Class Codes: G02F 1/13725 based on guest-host interaction G02F1/13762, G02F1/13737, take precedence
• CPC Class Codes: G02F 2203/02 reflective

Abstract

A device for illuminating, as well as enhancing contrast of, reflective dichroic liquid crystal displays utilizes a polarizing member extending across the thickness of a wedge illuminator. The light emitted from the wedge illuminator is polarized in a single direction, perpendicular to the elongated direction of the dichroic dye molecules in the light-transmitting areas of the display cell.

Claims

1. An illuminator for a reflective dichroic liquid crystal display cell having a planar front surface of predetermined length, said illuminator comprising:

a wedge of light transmissive material having a rear surface disposed adjacent and substantially parallel to, and of length greater than and overlying the length of, the planar front surface of said display cell;

means disposed within the thicker end of said wedge illuminator member for emitting light rays with random polarization and ramdom emission direction;

said randomly-emitted light rays emerging from said wedge illuminator member rear surface at random distances along the length thereof and obliquely entering the front surface of said display cell; and

means positioned within a portion of said thicker member end so as to avoid interference with light reflected from the said display cell front surface for polarizing the light rays emitted from said wedge illuminator to have a polization vector parallel to the plane of said display front surface, to enhance the contrast ratio between light reflected from areas of said display cell respectivey substantially reflecting and substantially absorbing said rays.

2. The illuminator as set forth in claim 1, wherein said polarizing means is a polarization member disposed within said wedge illuminator member and having a polarization vector essentially parallel to the plane of said wedge illuminator member rear surface.

3. The illuminator as set forth in claim 2, wherein said polarization member is planar and is disposed substantially perpendicular to the plane of said wedge illuminator member rear surface.