Reflective liquid crystal display device and reflector

• US 5,691,791 A
• Filed: 05/13/1996
• Issued: 11/25/1997
• Est. Priority Date: 07/30/1993
• Status: Expired due to Term

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Nakamura, Kozo, Tsuda, Kazuhiko, Nakamura, Hisakazu, Mitsui, Seiichi, Kimura, Naofumi
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): TON, MINH TOAN T
• Application Number:
  US08/645,493
• Time in Patent Office: 561 Days
• Field of Search: 349/113, 349/119, 349/75, 349/117
• US Class Current: 349/113
• CPC Class Codes: G02F 1/133553 Reflecting elements associated to illuminating devices G02F1/133605
• CPC Class Codes: G02F 1/133565 inside the LC elements, i.e. between the cell substrates

Abstract

A reflective liquid crystal display device including a first substrate and a second substrate, a liquid crystal layer interposed between the first and second substrates, a polarizing plate, and a reflection layer; wherein the polarizing plate and the reflection layer are located on opposite sides of the liquid crystal layer. A surface of the reflection layer reflecting light has projections, and an occupation of an area of portions where a tilt angle of a tangent line drawn against a profile of the surface with the projections is less than 2° in a total area of the surface is in a range of 20% to 60%.

Claims

1. A reflective liquid crystal display device including a first substrate and a second substrate, a liquid crystal layer interposed between the first and second substrates, a polarizing plate, and a reflection layer;

wherein the polarizing plate and the reflection layer are located on opposite sides of the liquid crystal layer, and

further wherein a surface of the reflection layer reflecting light has projections, and flat portions, the flat portions being areas where a tilt angle of a tangent line drawn against a profile of the surface with the projections is less than 2°

, in the flat portions occupying in a 20% to 60% of the total surface area of the surface.

2. A reflective liquid crystal display device according to claim 1, wherein the liquid crystal layer is driven in an ECB mode.

3. A reflective liquid crystal display device according to claim 1, wherein a retardation variation of the liquid crystal layer due to the projections is 40 nm or less.

4. A reflective liquid crystal display device according to claim 1, wherein the difference in the thickness of the liquid crystal layer due to the projections is 1 μ

m or less.

5. A reflective liquid crystal display device according to claim 1, wherein the light reflection layer is selected so that a degree of polarization V of light reflected from the light reflection layer, represented by:

##EQU9## where S₀, S₁, S₂, and S₃ are Stokes parameters referring respectively to a total light intensity, an excess in intensity of horizontal linearly polarized light, an excess in intensity of 45°

linearly polarized light, and an excess in intensity of right-handed circularly polarized light, is at least 50% or more.

6. A reflective liquid crystal display device according to claim 1, further including electrodes attached to the first and second substrates for applying an electric field to the liquid crystal layer to control a retardation of the liquid crystal layer, wherein

the first substrate positioned between the polarizer and the liquid crystal layer comprises an optical phase compensation means which includes a first region having a first retardation and a second region having a second retardation different from the first retardation, whereby a color of emitted light from each of the first and the second regions is selected to be a specific one, in accordance with the retardations of the optical phase compensation means and the retardation of the liquid crystal layer.

7. A reflective liquid crystal display device according to claim 6, wherein each of a plurality of pixels, which is a smallest area of the device for conducting a color display, includes a portion of one of the first and the second regions.

8. A reflective liquid crystal display device according to claim 6, wherein each of a plurality of pixels, which is a smallest area of the device for conducting a color display, includes each portion of the first and the second regions.

9. A reflective liquid crystal display device according to claim 8, wherein the optical phase compensation means further comprises a third region having a third retardation, and each of the plurality of pixels includes a portion of at least one of the first, the second and the third regions.

10. A reflective liquid crystal display device according to claim 6, wherein the optical phase compensation means includes at least two optical phase compensation members, at least one of the optical phase compensation members overlapping another of the optical compensation members so as to form the first and the second regions.

11. A reflective liquid crystal display device according to claim 6, wherein the retardation of the liquid crystal layer is equal to or less than 1.0 μ

m.

12. A reflective liquid crystal display device according to claim 6, wherein the reflecting means functions as one of the electrodes for applying an electric field to the liquid crystal layer.

13. A reflector for reflecting light, wherein a surface of the reflector reflecting light has projections and flat portions, the flat portions being areas of the surface where a tilt angle of a tangent line drawn against a profile of the surface with the projections is less than 2°

, the flat portions occupying 20% to 60% of the total surface area of the surface.

14. A reflector according to claim 13, wherein the difference in the height of the projections is 1 μ

m or less.

15. A reflector according to claim 13, wherein the light reflection layer is selected so that a degree of polarization V of light reflected from the light reflection layer, represented by:

##EQU10## where S₀, S₁, S₂, and S₃ are Stokes parameters referring respectively to a total light intensity, an excess in intensity of horizontal linearly polarized light, an excess in intensity of 45°

linearly polarized light, and an excess in intensity of right-handed circularly polarized light, is at least 50% or more.