Display panel and display device including the same

• US 10,451,918 B2
• Filed: 05/11/2018
• Issued: 10/22/2019
• Est. Priority Date: 10/11/2017
• Status: Active Grant

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Inventors: Yoon, Hyungguen, Park, Jaehong, Park, Jiyun, Lee, Kyunghee, Chang, Jaebok
• Primary Examiner(s): Duong, Thoi V
• Application Number:
  US15/978,006
• Publication Number:
  US 20190107752A1
• Time in Patent Office: 529 Days
• CPC Class Codes: G02F 1/1334 based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals
• CPC Class Codes: G02F 1/133514 Colour filters
• CPC Class Codes: G02F 1/133528 Polarisers
• CPC Class Codes: G02F 1/133617 Illumination with ultraviolet light; Luminescent elements or materials associated to the cell
• CPC Class Codes: G02F 1/1343 Electrodes reflective electrodes G02F1/133553
• CPC Class Codes: G02F 1/134363 for applying an electric field parallel to the substrate, i.e. in-plane switching [IPS]
• CPC Class Codes: G02F 1/1347 Arrangement of liquid crystal layers or cells in which the final condition of one light beam is achieved by the addition of the effects of two or more layers or cells
• CPC Class Codes: G02F 1/13471 in which all the liquid crystal cells or layers remain transparent, e.g. FLC, ECB, DAP, HAN, TN, STN, SBE-LC cells G02F1/13475 takes precedence
• CPC Class Codes: G02F 2201/121 common or background
• CPC Class Codes: G02F 2201/123 pixel

Abstract

A display device includes a display panel and a light source providing light to the display panel. The display panel includes a first polarizing layer to which the light is incident, a first base layer disposed on the first polarizing layer, a first liquid crystal layer disposed on the first base layer and including a plurality of first nanocapsules, a second liquid crystal layer disposed on the first liquid crystal layer and including a plurality of second nanocapsules, a second polarizing layer disposed between the first liquid crystal layer and the second liquid crystal layer, a second base layer disposed on the second liquid crystal layer, and a third polarizing layer disposed on the second base layer. Each of the first and second liquid crystal layers controls a transmittance of the light based on an intensity of an electric field between pixel electrodes and a common electrode.

Claims

1. A display device comprising:

a display panel; and

a light source configured to provide a light to the display panel, wherein the display panel comprises;

a first polarizing layer, the light being incident on the first polarizing layer;

a first base layer on the first polarizing layer, the first base layer comprising a pixel electrode and a common electrode;

a first liquid crystal layer on the first base layer and comprising a plurality of first nanocapsules;

a second liquid crystal layer on the first liquid crystal layer and comprising a plurality of second nanocapsules;

a second polarizing layer between the first liquid crystal layer and the second liquid crystal layer;

a second base layer on the second liquid crystal layer; and

a third polarizing layer on the second base layer,

wherein each of the first and second liquid crystal layers controls a transmittance of the light based on an intensity of an electric field between the pixel electrode and the common electrode.

2. The display device of claim 1, wherein the first and third polarizing layers have a first polarization axis parallel to a first direction, and the second polarizing layer has a second polarization axis parallel to a second direction perpendicular to the first direction.

3. The display device of claim 2, wherein the display panel displays a black gray scale when the intensity of the electric field is less than a reference electric field intensity.

4. The display device of claim 3, wherein the light transmitted through the first polarizing layer is blocked by the second polarizing layer when the intensity of the electric field is less than a threshold electric field intensity.

5. The display device of claim 3, wherein, when the intensity of the electric field is less than the reference electric field intensity, the first nanocapsules rotate a polarization direction of the light transmitted through the first polarizing layer to allow the rotated polarization direction to be parallel to the second polarization axis, and the light transmitted through the second polarizing layer is blocked by the third polarizing layer.

6. The display device of claim 2, wherein the display panel displays a color gray scale higher than a black gray scale when the intensity of the electric field is greater than a reference electric field intensity.

7. The display device of claim 6, wherein, when the intensity of the electric field is greater than the reference electric field intensity, the first nanocapsules rotate a first polarization direction of the light transmitted through the first polarizing layer to allow the rotated first polarization direction to be parallel to the second polarization axis, and only some of the second nanocapsules rotate a second polarization direction of the light transmitted through the second polarizing layer to allow the rotated second polarization direction to be parallel to the first polarization axis.

8. The display device of claim 6, wherein, when the intensity of the electric field is greater than the reference electric field intensity, the first nanocapsules rotate a first polarization direction of the light transmitted through the first polarizing layer to allow the rotated first polarization direction to be parallel to the second polarization axis, and the second nanocapsules rotate a second polarization direction of the light transmitted through the second polarizing layer to allow the rotated second polarization direction to be parallel to the first polarization axis.

9. The display device of claim 1, wherein each of the first nanocapsules comprises a plurality of first liquid crystal molecules and each of the second nanocapsules comprises a plurality of second liquid crystal molecules, and

wherein the first and second liquid crystal molecules rotate a polarization direction of the light, depending on the intensity of the electric field.

10. The display device of claim 9, wherein a positive dielectric anisotropy of the second nanocapsules is greater than a positive dielectric anisotropy of the first nanocapsules.

11. The display device of claim 9, wherein a refractive index of the second nanocapsules is greater than a refractive index of the first nanocapsules.

12. The display device of claim 1, wherein the pixel electrode and the common electrode are disposed on different layers.

13. The display device of claim 1, wherein the pixel electrode and the common electrode are disposed on the same layer.

14. The display device of claim 1, wherein the light provided from the light source has a first color, and

wherein the second base layer comprises a conversion part absorbing the light of the first color to emit light of a color different from the first color.

15. The display device of claim 14, wherein the conversion part comprises:

a first conversion part including a first illuminant emitting light of a second color different from the first color;

a second conversion part including a second illuminant emitting light of a third color different from the second color; and

a third conversion part transmitting the light of the first color.

16. The display device of claim 1, wherein the first liquid crystal layer further comprises an organic layer in which the first nanocapsules are dispersed, and

wherein the first liquid crystal layer is provided in a film type.

17. The display device of claim 1, wherein the second liquid crystal layer further comprises an organic layer in which the second nanocapsules are dispersed, and

wherein the second liquid crystal layer is provided in a film type.

18. The display device of claim 1, wherein a sum of thicknesses of the first to third polarizing layers is equal to or less than 10 μ

m.

19. A display panel comprising:

a first base layer comprising a pixel electrode and a common electrode;

a first liquid crystal film on the first base layer, the first liquid crystal film comprising a plurality of first nanocapsules and a first buffer layer in which the first nanocapsules are dispersed;

a second liquid crystal film on the first liquid crystal film, the second liquid crystal film comprising a plurality of second nanocapsules and a second buffer layer in which the second nanocapsules are dispersed; and

a polarizing layer disposed between the first liquid crystal film and the second liquid crystal film.

20. The display panel of claim 19, wherein a thickness of the polarizing layer is equal to or less than 3 μ

m.