Polarizing plate, method for manufacturing polarizing plate, image display device, method for manufacturing image display device, and method for improving transmittance of polarizing plate

Patent metadata

Field	Value
Publication number	US-2016209564-A1
Application number	US-201414917189-A
Country	US
Kind code	A1
Filing date	Aug 6, 2014
Priority date	Sep 10, 2013
Publication date	Jul 21, 2016
Grant date	—

Abstract

The present invention provides a polarizer excellent in transmittance even if it includes a light-transmitting substrate having no in-plane phase difference. The present invention relates to a polarizer configured to be disposed on a backlight source side in an image display device, the polarizer including at least a light-transmitting substrate having in-plane birefringence and a polarizing element layered in said order from the backlight source side, the light-transmitting substrate receiving incidence of polarized light, the light-transmitting substrate and the polarizing element being layered such that a fast axis of the light-transmitting substrate along a direction in which the substrate shows a smaller refractive index and a transmission axis of the polarizing element form an angle of 0°±30° or 90°±30°.

First claim

1 . A polarizer configured to be disposed on a backlight source side in an image display device, the polarizer comprising at least a light-transmitting substrate having in-plane birefringence and a polarizing element layered in said order from the backlight source side,
the light-transmitting substrate having in-plane birefringence receiving incidence of polarized light, the light-transmitting substrate having in-plane birefringence and the polarizing element being layered such that a fast axis of the light-transmitting substrate having in-plane birefringence along a direction in which the substrate shows a smaller refractive index and a transmission axis of the polarizing element form an angle of 0°±30° or 90°±30°.

2 . The polarizer according to claim 1 ,
wherein the light-transmitting substrate having in-plane birefringence and the polarizing element are layered such that the fast axis of the light-transmitting substrate having in-plane birefringence along a direction in which the substrate shows a smaller refractive index and the transmission axis of the polarizing element form an angle of 0° ±15° or 90°±15°.

3 . The polarizer according to claim 1 ,
wherein the light-transmitting substrate having in-plane birefringence has a difference (nx−ny) between the refractive indexes of 0.01 or greater, where nx represents a refractive index in the direction of the slow axis in which the substrate shows a greater refractive index, and ny represents a refractive index in the direction of the fast axis that is orthogonal to the slow axis.

4 . The polarizer according to claim 1 ,
wherein the light-transmitting substrate having in-plane birefringence satisfies the relation of nx>N>ny, where nx represents a refractive index in the direction of the slow axis of the light-transmitting substrate in which the substrate shows a greater refractive index, ny represents a refractive index in the direction of the fast axis that is orthogonal to the slow axis, and N represents an average refractive index of the light-transmitting substrate, and the fast axis and the transmission axis of the polarizing element form an angle of 0°±2°.

5 . A method for producing a polarizer configured to be disposed on a backlight source side in an image display device, the polarizer comprising at least a light-transmitting substrate having in-plane birefringence and a polarizing element layered in said order,
the method comprising the step of layering the light-transmitting substrate having in-plane birefringence and the polarizing element such that a fast axis of the light-transmitting substrate having in-plane birefringence along a direction in which the substrate shows a smaller refractive index and a transmission axis of the polarizing element form an angle of 0°±30° or 90°±30°.

6 . An image display device comprising the polarizer according to claim 1 .

7 . The image display device according to claim 6 ,
wherein a polarization separation film is provided between the backlight source and the light-transmitting substrate having in-plane birefringence.

8 . The image display device according to claim 6 , further comprising, on a viewer side, an upper polarizer including at least an upper light-transmitting substrate having in-plane birefringence and an upper polarizing element, the upper light-transmitting substrate being provided on the upper polarizing element,
wherein the upper light-transmitting substrate having in-plane birefringence and the upper polarizing element are arranged such that a fast axis of the upper light-transmitting substrate having in-plane birefringence along a direction in which the substrate shows a smaller refractive index and a transmission axis of the polarizing element do not form an angle of 90°.

9 . A method for producing an image display device that comprises a polarizer configured to be disposed on a backlight source side in an image display device, the polarizer including a light-transmitting substrate having in-plane birefringence and a polarizing element layered in said order,
the method comprising the step of layering the light-transmitting substrate having in-plane birefringence and the polarizing element such that a fast axis of the light-transmitting substrate having in-plane birefringence along a direction in which the substrate shows a smaller refractive index and a transmission axis of the polarizing element form an angle of 0° ±30° or 90°±30°.

10 . A method for improving the transmittance of a polarizer configured to be disposed on a backlight source side in an image display device, the polarizer comprising at least a light-transmitting substrate having in-plane birefringence and a polarizing element layered in said order,
the method comprising the step of layering the light-transmitting substrate having in-plane birefringence and the polarizing element such that a fast axis of the light-transmitting substrate having in-plane birefringence along a direction in which the substrate shows a smaller refractive index and a transmission axis of the polarizing element form an angle of 0°±30° or 90°±30°.

Assignees

• Dainippon Printing Co Ltd

Inventors

• Kuroda Takashi

Classifications

• G02B5/3083

  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 title

• G02B5/3041 Primary

  comprising multiple thin layers, e.g. multilayer stacks · CPC title

• G02F1/13362

  providing polarized light, e.g. by converting a polarisation component into another one · CPC title

• G02B5/305 Primary

  including organic materials, e.g. polymeric layers · CPC title

• G02F1/133528

  Polarisers · CPC title