Optical laminate for front surface of in-cell touch panel liquid crystal element and in-cell touch panel liquid crystal display device using same

• US 9,880,419 B2
• Filed: 10/25/2013
• Issued: 01/30/2018
• Est. Priority Date: 10/29/2012
• Status: Active Grant

• Current Assignee: Dai Nippon Printing Company Limited
• Original Assignee: Dai Nippon Printing Company Limited
• Inventors: Tsunekawa, Masayuki
• Primary Examiner(s): Frost, Anthony J
• Application Number:
  US14/438,818
• Publication Number:
  US 20150301385A1
• Time in Patent Office: 1,558 Days
• Field of Search: None
• CPC Class Codes: B32B 2457/202 LCD, i.e. liquid crystal displays
• CPC Class Codes: B32B 2551/00 Optical elements
• CPC Class Codes: G02B 1/14 Protective coatings, e.g. hard coatings
• CPC Class Codes: G02B 5/3033 in the form of a thin sheet or foil, e.g. Polaroid
• CPC Class Codes: G02B 5/3041 comprising multiple thin layers, e.g. multilayer stacks
• 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 1/13338 Input devices, e.g. touch panels
• CPC Class Codes: G02F 1/133528 Polarisers
• CPC Class Codes: G02F 1/13363 Birefringent elements, e.g. for optical compensation
• CPC Class Codes: G02F 2201/50 Protective arrangements

Abstract

Provided is an optical laminate for a front surface of an in-cell touch panel liquid crystal element in which the thickness can be reduced while necessary functions are ensured, and a liquid crystal screen becoming cloudy can be prevented.

The optical laminate for a front surface of an in-cell touch panel liquid crystal element comprises a phase difference plate, a polarizing film, and a surface protective film in this order, and further comprises a conductive layer. The surface protective film has optical anisotropy that scatters linear polarized light emitted from the polarizing film, and a thickness of the optical laminate is in a range of 90 μm to 450 μm.

Claims

1. An optical laminate for a front surface of an in-cell touch panel liquid crystal element comprising:

a phase difference plate;

a polarizing film;

a surface protective film in this order; and

a conductive layer,

wherein the surface protective film has optical anisotropy that scatters linear polarized light emitted from the polarizing film, and a thickness of the optical laminate is in a range of 90 μ

m to 450 μ

m,

wherein the conductive layer has a bilayer structure of a first conductive layer and a second conductive layer,

wherein the first conductive layer is in contact with the second conductive layer, and

wherein the first conductive layer comprises a thermoplastic resin.

2. The optical laminate for a front surface of an in-cell touch panel liquid crystal element according to claim 1,

wherein the surface protective film comprises a cured layer on a substrate having optical anisotropy that scatters linear polarized light emitted from the polarizing film.

3. The optical laminate for a front surface of an in-cell touch panel liquid crystal element according to claim 2,

wherein the substrate having optical anisotropy is a plastic film having a retardation value in a range of 3000 nm to 30000 nm or a plastic film having a ¼

wavelength phase difference.

4. The optical laminate for a front surface of an in-cell touch panel liquid crystal element according to claim 2,

wherein the substrate having optical anisotropy comprises a plastic film having a ¼

wavelength phase difference attached to an optical isotropic film.

5. The optical laminate for a front surface of an in-cell touch panel liquid crystal element according to claim 4,

wherein the plastic film having a ¼

wavelength phase difference is a biaxially stretched polyester film having a thickness in a range of 4 μ

m to 15 μ

m.

6. The optical laminate for a front surface of an in-cell touch panel liquid crystal element according claim 2,

wherein the substrate having optical anisotropy is in a form of a sheet and the optical laminate comprises the cured layers on both surfaces of the sheet.

7. The optical laminate for a front surface of an in-cell touch panel liquid crystal element according to claim 2,

wherein the cured layer is formed of an ionizing radiation curable resin composition.

8. The optical laminate for a front surface of an in-cell touch panel liquid crystal element according to claim 1,

wherein a surface resistivity of the conductive layer is in a range of 1.0×

10⁸ Ω

/□

to 2.0×

10⁹ Ω

/□

.

9. The optical laminate for a front surface of an in-cell touch panel liquid crystal element according to claim 1,

wherein the first conductive layer comprises fine metal particles or fine metal oxide particles, and the second conductive layer comprises fine coating particles comprising conductive coating layers on surfaces of fine core particles.

10. The optical laminate for a front surface of an in-cell touch panel liquid crystal element according to claim 1,

wherein the optical laminate comprises the conductive layer on a surface of the phase difference plate opposite to the polarizing film.

11. The optical laminate for a front surface of an in-cell touch panel liquid crystal element according to claim 1,

wherein the phase difference plate, the polarizing film, the surface protective film, and the conductive layer are attached together without using an adhesion layer.

12. The optical laminate for a front surface of an in-cell touch panel liquid crystal element according to claim 1,

wherein a thickness of the phase difference plate is in a range of 25 μ

m to 60 μ

m, a thickness of the polarizing film is in a range of 2 μ

m to 30 μ

m, a thickness of the surface protective film is in a range of 60 μ

m to 350 μ

m, and a thickness of the conductive layer is in a range of 0.1 μ

m to 10 μ

m.

15. The optical laminate for a front surface of an in-cell touch panel liquid crystal element according to claim 1,

wherein the thermoplastic resin has no reactive functional group in the molecule.

16. The optical laminate for a front surface of an in-cell touch panel liquid crystal element according to claim 1,

wherein the second conductive layer comprises a thermoplastic resin.

13. An in-cell touch panel liquid crystal display device comprising:

an in-cell touch panel liquid crystal element; and

an optical laminate for a front surface of the in-cell touch panel liquid crystal element, comprising;

a phase difference plate;

a polarizing film;

a surface protective film in this order; and

a conductive layer,

wherein the surface protective film has optical anisotropy that scatters linear polarized light emitted from the polarizing film, and a thickness of the optical laminate is in a range of 90 μ

m to 450 μ

m,

wherein a location of the conductive layer is selected from the group consisting of a surface of the phase difference plate on the polarizing film side, a surface of the phase difference plate on the opposite side to the polarizing film side, and a surface of the surface protective film on the polarizing film side,

wherein the conductive layer has a bilayer structure of a first conductive layer and a second conductive layer,

wherein the first conductive layer is in contact with the second conductive layer, and

wherein a surface of the optical laminate on the opposite side to the surface protective film relative to the polarizing film, is attached onto the in-cell touch panel liquid crystal element.

14. The in-cell touch panel liquid crystal display device according to claim 13,

wherein the conductive layer in the optical laminate is grounded.

17. The in-cell touch panel liquid crystal display device according to claim 13,

wherein the first conductive layer comprises a thermoplastic resin.

18. The in-cell touch panel liquid crystal display device according to claim 13,

wherein the thermoplastic resin has no reactive functional group in the molecule.

19. The in-cell touch panel liquid crystal display device according to claim 13,

wherein the second conductive layer comprises a thermoplastic resin.

20. The in-cell touch panel liquid crystal display device according to claim 13,

wherein the first conductive layer comprises fine metal particles or fine metal oxide particles, and the second conductive layer comprises fine coating particles comprising conductive coating layers on surfaces of fine core particles.