Optical display device having polarizing film

• US 8,379,169 B2
• Filed: 10/27/2011
• Issued: 02/19/2013
• Est. Priority Date: 09/03/2010
• Status: Active Grant

• Current Assignee: Nitto Denko Corporation
• Original Assignee: Nitto Denko Corporation
• Inventors: Kitagawa, Takeharu, Goto, Shusaku, Miyatake, Minoru, Mori, Tomohiro, Kamijo, Takashi, Yoshida, Kentaro, Kunikata, Satoru
• Primary Examiner(s): CALEY, MICHAEL H
• Application Number:
  US13/283,307
• Publication Number:
  US 20120057107A1
• Time in Patent Office: 481 Days
• Field of Search: 349/96, 349/141, 428/1.31, 359/487.02
• US Class Current: 349/96
• CPC Class Codes: B29C 55/026 of preformed plates or sheets coated with a solution, a dispersion or a melt of thermoplastic material
• CPC Class Codes: B29C 65/00 Joining or sealing of preformed parts , e.g. welding of plastics materials; Apparatus therefor general aspects of processes or apparatus for joining preformed parts B29C66/00; using porous material formed by internal pressure generated therein for joining preformed parts B29C44/1228, B29C44/326
• CPC Class Codes: B29D 11/00 Producing optical elements, e.g. lenses or prisms grinding or polishing of optical elements B24B; constructional form of optical elements G02B; optical parts of spectacles G02C7/00
• CPC Class Codes: B29K 2029/04 PVOH, i.e. polyvinyl alcohol B29K2031/04 takes precedence
• CPC Class Codes: B29K 2067/00 Use of polyesters or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2995/0034 Polarising
• CPC Class Codes: C09K 2323/031 Polarizer or dye
• CPC Class Codes: G02B 1/14 Protective coatings, e.g. hard coatings
• CPC Class Codes: G02B 5/30 Polarising elements light-modulating devices with active elements G02F1/00
• CPC Class Codes: G02B 5/3033 in the form of a thin sheet or foil, e.g. Polaroid
• 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 1/133528 Polarisers
• 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 2202/22 Antistatic materials or arrangements
• CPC Class Codes: G02F 2202/28 Adhesive materials or arrangements
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/30107 Inductance
• CPC Class Codes: Y10T 428/2495 Thickness [relative or absolute]
• CPC Class Codes: Y10T 428/265 1 mil or less

Abstract

Provided is an optical display device using a polarizing film which has a thickness of 10 μm or less and exhibits high optical characteristics. The optical display device comprises a continuous web of polarizing film which is made of a polyvinyl alcohol type resin having a molecularly oriented dichroic material, and formed through stretching to have a thickness of 10 μm or less and satisfy conditions expressed by the following formulas: P>−(10^0.929T-42.4−1)×100 (where T<42.3); and P≧99.9 (where T≧42.3), wherein T is a single layer transmittance, and P is a polarization rate. The polarizing film may be prepared by subjecting a laminate comprising a non-crystallizable ester type thermoplastic resin substrate and a polyvinyl alcohol type resin layer formed on the substrate to by 2-stage stretching consisting of preliminary in-air stretching and in-boric-acid-solution stretching.

Claims

1. An optical display device comprising a first polarizing film made of a polyvinyl alcohol type resin including a molecularly oriented dichroic material therein,

the first polarizing film being stretched to have a thickness of 10 μ

m or less and satisfying conditions expressed by the following formulas;

P>

−

(10^0.929T-42.4−

1)×

100 (where T<

42.3); and

P≧

99.9 (where T≧

42.3),

wherein T is a single layer transmittance, and P is a polarization rate,

the first polarizing film having a first surface joined to a surface of a display panel through a first optically transparent adhesive layer, an opposite second surface of the first polarizing film being joined to a protective layer.

2. The optical display device as defined in claim 1, wherein the first polarizing film comprises a polyvinyl alcohol type resin layer coated on a substrate made of an ester type thermoplastic resin material, stretched together with the thermoplastic resin substrate.

3. The optical display device as defined in claim 2, wherein the first polarizing film is stretched based on 2-stage stretching consisting of preliminary in-air stretching and in-boric-acid-solution stretching.

4. The optical display device as defined in claim 1, wherein the protective layer is formed as a ¼

wavelength phase difference layer.

5. The optical display device as defined in claim 1, wherein the display panel is a liquid-crystal display panel, and a second polarizing film equivalent to the first polarizing film is joined to an opposite second surface of the display panel through a second optically transparent adhesive layer.

6. The optical display device as defined in claim 5, wherein the display panel is a transmission type liquid-crystal display panel, and the optical display device is used under a condition that the second polarizing film is located on the side of a backlight.

7. The optical display device as defined in claim 5, wherein the display panel is a reflection type liquid-crystal display panel, and a mirror is disposed on a surface of the second polarizing film opposite the display panel to reflect at least a part of light transmitted through the liquid-crystal display panel.

8. The optical display device as defined in claim 7, wherein the mirror is a half mirror adapted to transmit therethrough at least a part of light transmitted through the liquid-crystal display panel, and a backlight is disposed on a side of the liquid-crystal display panel opposite to the half mirror.

9. The optical display device as defined in claim 5, wherein a ¼

wavelength phase difference layer is disposed in at least one of

(a) a position between the first polarizing film and the display panel, or

(b) a position between the display panel and the second polarizing film.

10. The optical display device as defined claim 5, wherein the second polarizing film is formed by subjecting a polyvinyl alcohol type resin layer formed on a substrate made of an ester type thermoplastic resin material to 2-stage stretching, together with the thermoplastic resin substrate, said protective layer is composed of the thermoplastic resin substrate stretched together with the polyvinyl alcohol type resin layer.

11. The optical display as defined in claim 5, wherein the liquid-crystal display panel is an in-plane switching (IPS) mode liquid-crystal display panel, and the optically transparent adhesive layer and a phase difference film are disposed in at least one of

(a) a position between the first polarizing film and the display panel, or

(b) a position between the display panel and the second polarizing film.

12. The optical display device as defined in claim 11, wherein the phase difference film satisfies the following relationship:

nx>

nz>

ny, where;

nx and ny are refractive indexes in in-plane x-axis and y-axis directions, respectively; and

nz is a refractive index in a thickness direction.

13. The optical display device as defined in claim 11, wherein the phase difference film has a two-layer structure consisting of a first phase difference layer satisfying the following relationship:

nx>

nz>

ny, and a second phase difference layer satisfying the following relationship;

nx>

ny>

nz, where;

nx and ny are refractive indexes in in-plane x-axis and y-axis directions, respectively; and

nz is a refractive index in a thickness direction.

14. The optical display device as defined in claim 5, wherein the liquid-crystal display panel is a vertical alignment (VA) mode liquid-crystal display panel, and a phase difference film is disposed between the display panel and each of the first and second polarizing films, the phase difference film satisfying the following relationship:

nx>

ny>

nz, where;

nx and ny are refractive indexes in in-plane x-axis and y-axis directions, respectively; and

nz is a refractive index in a thickness direction.

15. The optical display device as defined in claim 5 further comprising:

a phase difference film is disposed in at least one of

(a) a position between the first polarizing film and the display panel, or

(b) a position between the display panel and the second polarizing film, wherein

the phase difference film having at least one of an internal reflection-blocking function and a viewing angle compensation function.

16. The optical display device as defined in claim 1, wherein the display panel is an organic electro luminescent (EL) display panel or a reflection type liquid-crystal display panel, and a phase difference film is disposed between the first polarizing film and the display panel.

17. The optical display device as defined in claim 16, wherein the phase difference film is a biaxial phase difference film satisfying the following relationship:

nx>

nz>

ny, where;

nx and ny are refractive indexes in in-plane x-axis and y-axis directions, respectively; and

nz is a refractive index in a thickness direction.

18. The optical display device as defined in claim 16, wherein the phase difference film is a ¼

wavelength phase difference film.

19. The optical display device as defined in claim 1, wherein the first polarizing film is formed by subjecting a polyvinyl alcohol type resin layer formed on a substrate made of an ester type thermoplastic resin material to 2-stage stretching, together with the thermoplastic resin substrate, and the protective layer is composed of the thermoplastic resin substrate stretched together with the polyvinyl alcohol type resin layer.

20. The optical display device as defined in claim 19, wherein the ester type thermoplastic resin material is a non-crystallizable polyethylene terephthalate (PET).

21. The optical display device as defined in claim 1, wherein the protective layer comprises a cellulosic material or an acrylic resin material.

22. The optical display device as defined in claim 1, wherein the protective layer includes a pattern phase difference layer.

23. The optical display device as defined in claim 1, wherein the display panel is a reflection type liquid-crystal display panel, and a phase difference film is disposed between the first polarizing film and the display panel for circularly polarizing light polarized by the first polarizing film.

24. The optical display device as defined in claim 1, wherein a touch panel laminate having a touch sensing function is disposed on a viewing side with respect to the display panel.

25. The optical display device as defined in claim 24, wherein the touch panel laminate is a capacitive touch panel configured such that a plurality of patterned pairs of transparent electrodes are disposed while interposing a dielectric layer therebetween.

26. The optical display device as defined in claim 25, wherein the touch panel laminate is disposed between the first polarizing film and a viewing-side outermost member of the optical display device.

27. The optical display device as defined in claim 25, wherein the touch panel laminate is disposed between the first polarizing film and the display panel.

28. The optical display device as defined in claim 24, wherein the touch panel laminate is a resistive touch panel configured such that a transparent electrode is disposed opposed to a counter electrode through an air gap, the touch panel laminate being disposed between the first polarizing film and the display panel, or between the first polarizing film and a viewing-side outermost member of the optical display device.

29. An optical display device comprising a first polarizing film made of a polyvinyl alcohol type resin including a molecularly oriented dichroic material therein,

the first polarizing film being stretched to have a thickness of 8 μ

m or less and satisfying conditions expressed by the following formulas;

P>

−

(10^0.929T-42.4−

1)×

100 (where T<

42.3); and

P≧

99.9 (where T≧

42.3),

wherein T is a single layer transmittance, and P is a polarization rate,

the first polarizing film having a first surface joined to a surface of a display panel through a first optically transparent adhesive layer, an opposite second surface of the first polarizing film being joined to a protective layer.

30. An optical display device comprising a first polarizing film made of a polyvinyl alcohol type resin including a molecularly oriented dichroic material therein,

the first polarizing film being stretched to have a thickness of 5 μ

m or less and satisfying conditions expressed by the following formulas;

P>

−

(10^0.929T-42.4−

1)×

100 (where T<

42.3); and

P≧

99.9 (where T≧

42.3),

wherein T is a single layer transmittance, and P is a polarization rate,

the first polarizing film having a first surface joined to a surface of a display panel through a first optically transparent adhesive layer, an opposite second surface of the first polarizing film being joined to a protective layer.