Phase difference film, phase difference film composite and liquid crystal display device using the same

• US 6,638,582 B1
• Filed: 03/29/2001
• Issued: 10/28/2003
• Est. Priority Date: 07/29/1999
• Status: Expired due to Term

• Current Assignee: Teijin Limited
• Original Assignee: Teijin Limited
• Inventors: Uchiyama, Akihiko, Kushida, Takashi
• Primary Examiner(s): Huff, Mark F.
• Assistant Examiner(s): Sadula, Jennifer R.
• Application Number:
  US09/806,342
• Time in Patent Office: 943 Days
• Field of Search: 428/1.1, 428/1.2, 428/1.21, 428/1.23, 428/1.25, 428/1.26, 428/1.27, 428/1.28, 428/1.3, 428/1.31, 428/1.32, 428/1.4, 428/1.51, 428/1.6
• US Class Current: 428/1.2
• CPC Class Codes: C09K 2323/00 Functional layers of liquid crystal optical display excluding electroactive liquid crystal layer characterised by chemical composition
• CPC Class Codes: C09K 2323/02 Alignment layer characterised by chemical composition
• CPC Class Codes: C09K 2323/03 Viewing layer characterised by chemical composition
• CPC Class Codes: G02B 5/3083 Birefringent or phase retarding elements G02B5/3008, G02B5/3016 take precedence; systems for polarisation control G02B27/286; manufacturing phase modulating patterns by lithographic processes G03F7/001
• CPC Class Codes: G02F 1/13363 Birefringent elements, e.g. for optical compensation
• CPC Class Codes: G02F 1/133634 the refractive index Nz perpendicular to the element surface being different from in-plane refractive indices Nx and Ny, e.g. biaxial or with normal optical axis
• CPC Class Codes: G02F 1/133637 characterised by the wavelength dispersion
• CPC Class Codes: G02F 2413/02 Number of plates being 2

Abstract

A retardation film that can compensate for the optical properties of the liquid crystal cells of a liquid crystal display device and thereby enhance image quality. The retardation film consists of a single polymer film, which has a wavelength range in which the retardation value is positive and a wavelength range in which it is negative in a wavelength range of 400-800 nm, and which satisfies the following inequality (1) and/or (2) and has a water absorption of no greater than 1% by mass.

|R(400)|≧10 nm  (1)

|R(700)|≧10 nm  (2)

Claims

1. A retardation film consisting of a single polymer film, which has a wavelength range in which the retardation value is positive and a wavelength range in which it is negative in a wavelength range of 400-800 nm, which satisfies the following inequality (1) and/or (2), and which has a water absorption of no greater than 1% by mass,

2. A retardation film according to claim 1, wherein the retardation value is negative at a wavelength of 400 nm and the retardation value is positive at 800 nm.

3. A retardation film according to claim 1 or 2, wherein said polymer film is a polycarbonate film.

4. A retardation film according to claim 3, wherein said polymer film is a polycarbonate film with a fluorene skeleton.

5. A retardation film according to claim 4, wherein the polymer film comprises a polycarbonate composed of a repeating unit represented by the following formula (3):

where R₁-R₈ are each independently selected from among hydrogen, halogen atoms and hydrocarbon groups of 1-6 carbon atoms, and X is the following formula (4)

and a repeating unit represented by the following formula (5);

where R₉-R₁₆ are each independently selected from among hydrogen, halogen atoms and hydrocarbon groups of 1-6 carbon atoms,

and the repeating unit represented by formula (3) constitutes 60-90 mole percent of the total polycarbonate and the repeating unit represented by formula (5) constitutes 40-10 mole percent thereof.

6. A retardation film according to claim 1, wherein the retardation value is positive at a wavelength of 400 nm and the retardation value is negative at 800 nm.

7. A retardation film according to claim 1 or 6, wherein the polymer film is a single polymer blend film comprising polyphenylene oxide and polystyrene.

8. A retardation film according to claim 7, wherein the polymer film is a single polymer blend film comprising 39-25% by mass of polyphenylene oxide and 61-75% by mass of polystyrene.

9. A retardation film according to claim 1, wherein the polymer film further contains up to 20% by mass of a low molecular compound with optical anisotropy.

10. A laminated retardation film formed by laminating a retardation film according to claim 1 as a first retardation film with a second retardation film which has a positive or negative retardation value at wavelengths from 400 to 700 nm.

11. A laminated retardation film according to claim 10, wherein the absolute value of the retardation of said second retardation film is smaller as the wavelength is shorter.

12. A laminated retardation film according to claim 10, wherein the retardation value is 1/4 wavelength at a wavelength of 550 nm.

13. A retardation film integrated polarizing film formed by laminating a retardation film or laminated retardation film according to claim 1 with a polarizing film.

14. A liquid crystal display device employing a retardation film-integrated polarizing film according to claim 13.

15. A liquid crystal display device employing a retardation film or laminated retardation film according to claim 1.