Liquid crystal display device

• US 6,738,117 B2
• Filed: 08/15/2001
• Issued: 05/18/2004
• Est. Priority Date: 08/31/2000
• Status: Expired due to Term

• Current Assignee: Sumitomo Chemical Company Limited
• Original Assignee: Sumitomo Chemical Company Limited
• Inventors: Minakuchi, Keiichi
• Primary Examiner(s): Niebling, John F.
• Assistant Examiner(s): LINDSAY JR, WALTER LEE
• Application Number:
  US09/929,067
• Publication Number:
  US 20020047969A1
• Time in Patent Office: 1,007 Days
• Field of Search: 349/118, 349/18, 349/119, 349/176, 349/202, 349/120, 349/106
• US Class Current: 349/118
• CPC Class Codes: G02F 1/13338 Input devices, e.g. touch panels
• CPC Class Codes: G02F 1/133502 Antiglare, refractive index matching layers
• CPC Class Codes: G02F 1/13363 Birefringent elements, e.g. for optical compensation
• CPC Class Codes: G02F 1/133637 characterised by the wavelength dispersion
• CPC Class Codes: G02F 1/133638 Waveplates, i.e. plates with a retardation value of lambda/n
• CPC Class Codes: G02F 2201/50 Protective arrangements
• CPC Class Codes: G02F 2413/02 Number of plates being 2

Abstract

The present invention provides a liquid crystal display device comprising: a laminated protection panel composed of a λ/4-plate, a polarizing plate and a transparent protection plate; a liquid crystal display; and a phase retarder;

wherein the laminated protection panel is disposed to a top surface of a liquid crystal display with a distance, the phase retarder is disposed between the laminated protection panel and the liquid crystal display, and the sum (α_A+α_B) of a wavelength dispersion (α_A) of the λ/4-plate and a wavelength dispersion (α_B) of the phase retarder is in the range of 1.11 to 1.95. In this liquid crystal display device having a transparent protection plate such as a touch panel, coloring of a displayed view looked at in an oblique direction is improved while maintaining a display quality in a front direction.

Claims

1. A liquid crystal display device comprising:

a laminated protection panel composed of a λ

/4-plate, a polarizing plate and a transparent protection plate;

a liquid crystal display; and

a phase retarder;

wherein the laminated protection panel is disposed to a top surface of the liquid crystal display with a distance, the phase retarder is disposed between the laminated protection panel and the liquid crystal display, and the sum (α

_A+α

_B) of a wavelength dispersion (α

_A) of the λ

/4-plate and a wavelength dispersion (α

_B) of the phase retarder is in the range of 1.11 to 1.95.

2. The liquid crystal display device according to claim 1, wherein a direction of an orientation axis of the phase retarder is in the range of 0±

45 degrees with respect to a direction of an orientation axis of the λ

/4-plate which forms the laminated protection panel.

3. The liquid crystal display device according to claim 1, wherein a direction of an orientation axis of the phase retarder is in the range of 95±

45 degrees with respect to a direction of an orientation axis of the λ

/4-plate which forms the laminated protection panel.

4. The liquid crystal display device according to any one of claims 1 to 3, wherein the transparent protection plate is disposed to the liquid crystal display side within the laminated protection panel.

5. The liquid crystal display device according to any one of claims 1 to 3, wherein the λ

/4-plate is disposed to the liquid crystal display side within the laminated protection panel.

6. The liquid crystal display device according to any one of claims 1 to 3, wherein an upper polarizing plate does not exist in the liquid crystal display.

7. The liquid crystal display device according to any one of claims 1 to 3, wherein the transparent protection plate is a touch panel.

8. The liquid crystal display device according to any one of claims 1 to 3, wherein the laminated protection panel has a hard coat layer at the outer-most surface of the laminated protection panel.

9. The liquid crystal display device according to any one of claims 1 to 3, wherein the laminated protection panel has an anti-reflection layer at the outer-most surface of the laminated protection panel.