Optical film stack including retardation layer

Patent metadata

Field	Value
Publication number	US-10073204-B2
Application number	US-201415038932-A
Country	US
Kind code	B2
Filing date	Nov 24, 2014
Priority date	Nov 25, 2013
Publication date	Sep 11, 2018
Grant date	Sep 11, 2018

Abstract

Optical film stacks are described. More particularly, optical film stacks including a half-wave retardation layer are described. Achromatic half-wave retardation layers, including achromatic half-wave layers formed from a quarter-wave and a three-quarters-wave retardation layer, are described. Film stacks including reflective polarizers tuned to reduce wavelength dispersion of the half-wave retardation layer are also described.

First claim

What is claimed is:

1. An optical film stack, comprising:
a reflective polarizer having a top surface, a bottom surface, a transmission axis, and a reflection axis;
an achromatic half-wave retardation layer having a top surface, a bottom surface disposed on the top surface of the reflective polarizer, and a slow axis oriented substantially 45° with respect to the transmission axis of the reflective polarizer; and
an absorbing polarizer having a bottom surface disposed on the top surface of the achromatic half-wave retardation layer and a transmission axis oriented substantially 90° with respect to the transmission axis of the reflective polarizer.

2. The optical film stack of claim 1 , further comprising a quarter-wave retardation layer disposed on the bottom surface of the reflective polarizer.

3. The optical film stack of claim 1 , wherein a retardation value of the achromatic half-wave retardation layer varies directly with a wavelength of visible light.

4. A roll of film, comprising the optical film stack of claim 1 .

5. An optical film stack, comprising:
a reflective polarizer having a top surface, a bottom surface, a transmission axis, and a reflection axis;
a first retardation layer having a top surface, a bottom surface disposed on the top surface of the reflective polarizer, and a slow axis oriented substantially 45° with respect to the transmission axis of the reflective polarizer;
a second retardation layer having a top surface, a bottom surface disposed on the top surface of the first retardation layer, and a slow axis oriented substantially 45° with respect to the transmission axis of the reflective polarizer and oriented substantially 90° with respect to the slow axis of the first retardation layer; and
an absorbing polarizer having a bottom surface disposed on the top surface of the second retardation layer and a transmission axis oriented substantially 90° with respect to the transmission axis of the reflective polarizer;
wherein together the first and second retardation layers are configured as an achromatic half-wave retardation layer.

6. The optical film stack of claim 5 , wherein the first retardation layer is a three-quarters-wave retardation layer and the second retardation layer is a quarter-wave retardation layer.

7. The optical film stack as in claim 5 , wherein the second retardation layer includes a liquid crystal layer.

8. The optical film stack of claim 7 , wherein the liquid crystal layer has a thickness of between 1 and 1.3 microns.

9. The optical film stack as in claim 5 , wherein the first retardation layer includes a film.

Assignees

• 3M Innovative Properties Co

Inventors

• Park Sun-Yong
• Lee Song-Geun
• Johnson Matthew B
• Haag Adam D

Classifications

• G02B5/3016

  involving passive liquid crystal elements (optical properties of liquid crystals G02F1/0063; polarising elements associated with active liquid crystal devices G02F1/133528) · CPC title

• G02F1/13362

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

• G02F2001/133638

  Physics · mapped topic

• G02F1/13363

  Birefringent elements, e.g. for optical compensation · CPC title

• B32B2457/202

  LCD, i.e. liquid crystal displays · CPC title