Electronically switchable privacy film and display device having same

• US 9,229,261 B2
• Filed: 09/26/2012
• Issued: 01/05/2016
• Est. Priority Date: 09/30/2011
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Schwartz, Evan L., Pellerite, Mark J., Hennen, Daniel W., Radcliffe, Marc D., Steiner, Michael L., Boulos, Marie A., Lauters, Michael E., Boyd, Gary T., Baetzold, John P., Stradinger, John J., Jones, Vivian W.
• Primary Examiner(s): DUONG, THOI V
• Application Number:
  US14/348,373
• Publication Number:
  US 20140226093A1
• Time in Patent Office: 1,196 Days
• Field of Search: 359/265, 359/599, 359/273, 359/641, 359/839, 362/618, 349/112, 349/86, 349/84, 349/110, 349/33, 349/104, 349/105, 349/35, 349/169, 349/179, 349/185, 349/186, 349/12, 252/582
• US Class Current: 1/1
• CPC Class Codes: G02B 26/004 based on a displacement or a deformation of a fluid
• CPC Class Codes: G02F 1/1323 Arrangements for providing a switchable viewing angle
• CPC Class Codes: G02F 1/133377 Cells with plural compartments or having plurality of liquid crystal microcells partitioned by walls, e.g. one microcell per pixel
• CPC Class Codes: G02F 1/1334 based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals
• CPC Class Codes: G02F 1/133524 Light-guides, e.g. fibre-optic bundles, louvered or jalousie light-guides
• CPC Class Codes: G02F 1/13476 in which at least one liquid crystal cell or layer assumes a scattering state

Abstract

An electronically switchable privacy film suitable for use in display devices are described. The electronically switchable privacy film comprises a pair of mutually opposing transparent electrodes; an optically transparent microstructured layer disposed between the transparent electrodes, the microstructured layer comprising a plurality of microstructured ribs extending across a surface thereof such that the microstructured ribs form an alternating series of ribs and channels; and electronically switchable material disposed in the channels, the electronically switchable material being capable of modulation between high and low light scattering states upon application of an electric field across the transparent electrodes.

Claims

1. An electronically switchable privacy film comprising:

a pair of mutually opposing transparent electrodes;

an optically transparent microstructured layer disposed between the transparent electrodes, the microstructured layer comprising a plurality of microstructured ribs extending across a surface thereof such that the microstructured ribs form an alternating series of ribs and channels;

electronically switchable material disposed in the channels, the electronically switchable material being capable of modulation between high and low light scattering states upon application of an electric field across the transparent electrodes;

wherein;

when the electric field is not applied, the film is in a privacy mode such that it has a haze of at least 70% at viewing angles from about 30°

to 45°

;

when the electric field is applied, the film is in the share mode such that it has a haze less than 35% at a viewing angle of about 45°

,

the film has a light transmission of at least about 25% in share and privacy modes at viewing angles from 0 to about 15°

.

2. The electronically switchable privacy film of claim 1, wherein the electronically switchable material comprises a liquid crystal.

3. The electronically switchable privacy film of claim 1, wherein the electronically switchable material has a pitch length of about 800 to about 1500 nm.

4. The electronically switchable privacy film of claim 1, wherein the electronically switchable material comprises liquid crystals dispersed in a polymer matrix.

5. The electronically switchable privacy film of claim 1, wherein a magnitude of the dielectric anisotropy for the electronically switchable material is greater than about 30, 40, 50, or 60 when measured at 1 kHz and 20°

C.

6. The electronically switchable privacy film of claim 1, wherein the electronically switchable material has a refractive index from about 1.52 to about 1.75.

7. The electronically switchable privacy film of claim 1, wherein each rib of the optically transparent microstructured layer has a height from about 25 to about 150 um and a width from about 25 to about 50 um.

8. The electronically switchable privacy film of claim 1, wherein each rib has height H, width W and rib aspect ratio H/W greater than about 1.5.

9. The electronically switchable privacy film of claim 1, wherein each channel of the optically transparent microstructured layer has a height from about 25 to about 150 um and a width from about 1 to about 50 um.

10. The electronically switchable privacy film of claim 1, wherein each channel has height H, width Y and channel aspect ratio H/Y greater than 5.

11. The electronically switchable privacy film of claim 1, wherein the optically transparent microstructured layer has a refractive index from about 1.48 to about 1.75.

12. The electronically switchable privacy film of claim 1, wherein the difference between the refractive indices of the electronically switchable material and the optically transparent microstructured layer is less than about 0.05 when the privacy film is in the share mode.

13. The electronically switchable privacy film of claim 1, wherein the difference between the refractive indices of the electronically switchable material and the optically transparent microstructured layer is greater than about 0.05 when the privacy film is in the privacy mode.

14. The electronically switchable privacy film of claim 1, wherein the distance between the two opposing transparent electrodes is from about 25 to about 150 um.

15. The electronically switchable privacy film of claim 1, wherein each transparent electrode comprises a conductive layer disposed on a transparent substrate, and each conductive layer is adjacent opposing major surfaces of the optically transparent microstructured layer.

16. The electronically switchable privacy film of claim 15, wherein at least one of the conductive layers comprises metallic nanowires, conductive metal oxide, conducting polymer, graphene, or carbon nanotubes.

17. An electronically switchable privacy film device comprising:

the electronically switchable privacy film of claim 1, and

circuitry for supplying the electric field.

18. A display device comprising:

a light transmissive display panel,

a light output substrate adjacent the light transmissive display panel, the light output substrate comprising a viewing surface opposite the light transmissive display panel, and

the electronically switchable privacy film of claim 1 disposed on the viewing surface.

19. A display device comprising:

a light transmissive display panel,

a light output substrate adjacent the light transmissive display panel, the light output substrate comprising a viewing surface opposite the light transmissive display panel, and

the electronically switchable privacy film of claim 1 disposed between the light transmissive display panel and the light output substrate.

20. The display device of claim 19, wherein the light output substrate comprises a touch screen.