Arrangement to remove reflection from liquid crystal displays (LCD's)

• US 4,657,348 A
• Filed: 11/15/1984
• Issued: 04/14/1987
• Est. Priority Date: 03/19/1983
• Status: Expired due to Fees

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Ziegler, Wolfgang
• Primary Examiner(s): Corbin, John K.
• Assistant Examiner(s): Lewis, David
• Application Number:
  US06/683,267
• Time in Patent Office: 880 Days
• Field of Search: 350/399, 350/337, 350/345, 350/276.5 LA, 350/276 R, 350/347 R
• US Class Current: 349/68
• CPC Class Codes: G02B 27/281 used for attenuating light intensity, e.g. comprising rotatable polarising elements
• CPC Class Codes: G02F 1/1335 Structural association of cells with optical devices, e.g. polarisers or reflectors
• CPC Class Codes: G02F 2203/09 transflective
• CPC Class Codes: G09F 9/35 being liquid crystals G09F9/302 takes precedence; liquid crystal materials C09K19/00; liquid crystal panels comprising a number of electrodes in a single cell per se G02F1/13

Abstract

An arrangement to remove reflection from liquid crystal displays is proposed. The arrangement includes a liquid crystal cell (11) and a cover disk (18) disposed obliquely thereto, spaced apart from and in front of the liquid crystal cell (11), the cover disk bearing a circular polarizer (19). In the front, a λ/4 retarding foil (16) is disposed on the liquid crystal cell (11), cooperating with the circular polarizer (19) in such a manner that a practically complete removal of reflection for the light passing through the cover disk (18) from outside takes place (FIG. 1).

Claims

1. Arrangement to remove reflection from liquid crystal displays (10) comprising

a substantially planar liquid crystal cell (11, 11a);

a cover disk (18) disposed spaced apart from, in front of, and at an oblique angle with respect to the plane of the liquid crystal cell (11, 11a);

a circular polarizer (19) applied to a face of said cover disk closest to said liquid crystal cell (11,11a);

and

a λ

/4 retarding foil (16) disposed on a front face of the liquid crystal cell (11, 11a) closest to said cover disk (18), said λ

/4 retarding foil and said circular polarizer, cooperating to linearly polarize light which has passed through both the λ

/4 retarding foil and the circular polarizer.

2. Arrangement according to claim 1, wherein

said liquid crystal cell (11,11a) has a back side, remote from said cover disk (18);

a linear polarizer (14) is disposed on said back side;

a transflector (15) is disposed behind said linear polarizer (14); and

a backlight (21) is provided, disposed behind said transflector (15), and illuminates triggered display elements.

3. Arrangement according to claim 1 or 2, characterized in that the λ

/4 retarding foil (16) is applied together with a linear-polarizing layer (25), as a circular polarizer, to the front of the liquid crystal cell (11a).

4. Arrangement according to claim 3, characterized in that the linear-polarizing layer (25) is applied to the front surface of the liquid crystal cell (11a) and the λ

/4 retarding foil (16) faces the cover disk (18).

5. Arrangement according to claim 1, wherein said circular polarizer (19) on said cover disk (18) comprises

a linear polarizer (19a);

and

a λ

/4 retarding foil (19b), said retarding foil (19b) being disposed between said linear polarizer (19a) and the retarding foil (16) on the front of said liquid crystal cell (11,11a).