Reflective liquid-crystal display device

• US 6,693,690 B2
• Filed: 05/01/2002
• Issued: 02/17/2004
• Est. Priority Date: 05/07/2001
• Status: Active Grant

• Current Assignee: Nitto Denko Corporation
• Original Assignee: Nitto Denko Corporation
• Inventors: Umemoto, Seiji, Kinoshita, Ryoji, Nakano, Yuuki, Kishioka, Hiroaki, Sakaitani, Waka
• Primary Examiner(s): Chowdhury, Tarifur
• Assistant Examiner(s): Wang, George Y.
• Application Number:
  US10/135,438
• Publication Number:
  US 20020180910A1
• Time in Patent Office: 657 Days
• Field of Search: 349/113, 349/65, 349/62, 349/63, 362/31
• US Class Current: 349/113
• CPC Class Codes: G02B 6/0036 2-D arrangement of prisms, protrusions, indentations or roughened surfaces
• CPC Class Codes: G02B 6/005 provided by one optical element, or plurality thereof, placed on the light output side of the light guide
• CPC Class Codes: G02B 6/0053 Prismatic sheet or layer; Brightness enhancement element, sheet or layer
• CPC Class Codes: G02B 6/0061 to provide homogeneous light output intensity
• CPC Class Codes: G02F 1/13338 Input devices, e.g. touch panels
• CPC Class Codes: G02F 1/133504 Diffusing, scattering, diffracting elements associated to illuminating devices G02F1/133606
• 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 2203/02 reflective

Abstract

A lightweight, touch-input-type reflective liquid-crystal display panel having a reflective liquid-crystal display panel. The reflective liquid-crystal display panel being formed in a manner such that external light incident on an outer surface is reflected by the light-reflecting layer so that display light transmitted through the liquid-crystal layer is made to emerge from the visual side cell substrate and viewed.

Claims

1. A reflective liquid-crystal display device comprising:

a reflective liquid-crystal display panel including a liquid-crystal cell and light-reflecting means, said liquid-crystal cell having a back-side cell substrate made of a support substrate containing at least an electrode, a visual-side cell substrate made of a transparent substrate containing at least a transparent electrode, and a layer of liquid crystal between the two cell substrates disposed so that the electrode sides of the two cell substrates face each other, said light-reflecting means being located on a back side with respect to said liquid-crystal layer of said cell, said reflective liquid-crystal display panel being formed in a manner such that external light incident on an outer surface of said visual-side cell substrate is reflected by said light-reflecting means so that display light transmitted through said liquid-crystal layer is made to emerge from said visual-side cell substrate and viewed;

at least one light source disposed on at least one of side surfaces of said reflective liquid-crystal display panel;

an optical path control layer having a thickness in a range of from 10 to 300 μ

m and disposed on an outer surface side of said visual-side cell substrate, said optical path control layer including light output means formed by arrangement of a plurality of fine grooves each made of a concave portion shaped like an approximate triangle in section, each of said fine grooves being having a length of not larger than 250 μ

m and a depth of not larger than 50 μ

m, the depth being not larger than ⅕

as large as the length, each of said fine grooves having an optical path changing slope, and a steep slope facing said optical path changing slope, said optical path changing slopes being provided so that light incident on said side surface from said light source is reflected toward said back-side cell substrate side, each of said optical path changing slopes being inclined at an inclination angle in a range of from 35 to 48 degrees to a reference plane of said liquid-crystal display panel, each of said steep slopes being inclined at an inclination angle of not lower than 60 degrees to said reference plane;

a transparent adhesive layer; and

a transparent touch panel provided with a mechanism for detecting an input position and bonded to an outer side of said optical path control layer through said transparent adhesive layer.

2. A reflective liquid-crystal display device according to claim 1, wherein said visual-side cell substrate further contains a transparent layer lower in refractive index than that of said transparent substrate and disposed between said transparent substrate and said transparent electrode.

3. A reflective liquid-crystal display device according to claim 1, wherein each of said visual-side cell substrate and said back-side cell substrate is made of an optically isotropic material.

4. A reflective liquid-crystal display device according to claim 1, wherein an area occupied by said light output means is not larger than ⅛

as large as an area of one surface of said optical path control layer.

5. A reflective liquid-crystal display device according to claim 1, wherein each of said optical path changing slopes in said optical path control layer is inclined at an inclination angle in a range of from 38 to 45 degrees to said reference plane of said liquid-crystal display panel.

6. A reflective liquid-crystal display device according to claim 1, wherein said fine grooves constituting said light output means are arranged to be distributed at random in one surface of said optical path control layer.

7. A reflective liquid-crystal display device according to claim 1, wherein said fine grooves constituting said light output means in said optical path control layer are arranged more densely as they are farther from said light source.

8. A reflective liquid-crystal display device according to claim 1, wherein said fine grooves constituting said light output means in said optical path control layer are arranged more densely as they are nearer to each of side end surfaces based on said side surface on which said light source is disposed.

9. A reflective liquid-crystal display device according to claim 1, wherein said optical path control layer is made of a transparent film coated with a layer for forming said light output means.

10. A reflective liquid-crystal display device according to claim 1, wherein said optical path control layer is made of an optically isotropic material.

11. A reflective liquid-crystal display device according to claim 1, wherein:

said light source disposed on said side surface of said liquid-crystal display panel is made of a linear light source; and

said fine grooves constituting said light output means are arranged in parallel to one another in terms of said optical path changing slopes.

12. A reflective liquid-crystal display device according to claim 1, wherein:

said light source disposed on said side surface of said liquid-crystal display panel is made of a point light source; and

said fine grooves constituting said light output means are arranged concentrically with said point light source as a virtual center.

13. A reflective liquid-crystal display device according to claim 1, wherein said reflective liquid-crystal display panel further includes at least one polarizer disposed on at least one surface of said liquid-crystal cell.

14. A reflective liquid-crystal display device according to claim 13, wherein said reflective liquid-crystal display panel further includes a phase retarder between said liquid-crystal cell and said polarizer.

15. A reflective liquid-crystal display device according to claim 1, wherein said touch panel includes an input side transparent base material containing a transparent electrode, and a pressure-receiving side transparent base material containing a transparent electrode and disposed opposite to said input side transparent base material so that the respective transparent electrodes of the two base materials face each other through a gap.

16. A reflective liquid-crystal display device according to claim 15, wherein said input side base material as one of constituent members of said touch panel is constituted by a transparent film containing a transparent electrode.

17. A reflective liquid-crystal display device according to claim 15, wherein said pressure-receiving side base material as one of constituent members of said touch panel is constituted by a support base material having an in-plane retardation of not larger than 20 nm and containing a transparent electrode.

18. A reflective liquid-crystal display device according to claim 15, wherein said pressure-receiving side base material as one of constituent members of said touch panel is constituted by a support base material having a thicknesswise retardation of not larger than 50 nm and containing a transparent electrode.

19. A reflective liquid-crystal display device according to claim 1, wherein said touch panel further includes an anti-reflection layer in its outermost surface.

20. A reflective liquid-crystal display device according to claim 1, wherein said adhesive layer for bonding said optical path control layer and said touch panel to each other is a tacky layer.

21. A reflective liquid-crystal display device according to claim 1, wherein said adhesive layer for bonding said optical path control layer and said touch panel to each other is formed so that said fine grooves constituting said light output means in said optical path control layer are not filled with said adhesive layer.

22. A reflective liquid-crystal display device according to claim 1, wherein said adhesive layer for bonding said optical path control layer and said touch panel to each other has a refractive index lower than that of said optical path control layer so that a refractive index difference between said adhesive layer and said optical path control layer is not lower than 0.02.

23. A reflective liquid-crystal display device according to claim 1, wherein said adhesive layer for bonding said optical path control layer and said touch panel to each other exhibits a storage elastic modulus of not smaller than 5×

10⁴ N/m² at 20°

C.