REFLECTIVE DISPLAY DEVICE

• US 20180101060A1
• Filed: 07/17/2017
• Published: 04/12/2018
• Est. Priority Date: 10/12/2016
• Status: Active Grant

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Inventors: CHO, Seon Ah, PARK, Young Jin
• Granted Patent: US 10,067,376 B2
• Time in Patent Office: Days
• CPC Class Codes: G02F 1/133504 Diffusing, scattering, diffracting elements associated to illuminating devices G02F1/133606
• CPC Class Codes: G02F 1/133528 Polarisers
• CPC Class Codes: G02F 1/133531 characterised by the arrangement of polariser or analyser axes
• CPC Class Codes: G02F 1/133536 Reflective polarizers G02F1/13362 takes precedence
• CPC Class Codes: G02F 1/133548 Wire-grid polarisers
• CPC Class Codes: G02F 1/133553 Reflecting elements associated to illuminating devices G02F1/133605
• CPC Class Codes: G02F 1/133614 using photoluminescence, e.g. phosphors illuminated by UV or blue light
• CPC Class Codes: G02F 1/133618 for ambient light
• CPC Class Codes: G02F 1/13362 providing polarized light, e.g. by converting a polarisation component into another one
• CPC Class Codes: G02F 1/13363 Birefringent elements, e.g. for optical compensation
• CPC Class Codes: G02F 1/133638 Waveplates, i.e. plates with a retardation value of lambda/n
• CPC Class Codes: G02F 1/1337 Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers
• CPC Class Codes: G02F 1/133742 for homeotropic alignment
• CPC Class Codes: G02F 1/137 characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering
• CPC Class Codes: G02F 2203/02 reflective
• CPC Class Codes: G02F 2203/19 linearised modulation; reduction of harmonic distortions
• CPC Class Codes: G02F 2413/02 Number of plates being 2
• CPC Class Codes: G02F 2413/06 Two plates on one side of the LC cell

Abstract

A reflective display device including: a reflection plate; a liquid crystal layer disposed on the reflection plate, the liquid crystal layer including a liquid crystal aligned vertically in an initial alignment state, a first phase delay layer disposed on the liquid crystal layer; a reflective polarizing element disposed on the first phase delay layer; and an absorptive polarizing element disposed on the reflective polarizing element, wherein external light incident on the absorptive polarizing element is in an unpolarized state.

Claims

1. A reflective display device, comprising:

a reflection plate;

a liquid crystal layer disposed on the reflection plate, the liquid crystal layer further comprising a liquid crystal aligned vertically in an initial alignment state,

a first phase delay layer disposed on the liquid crystal layer;

a reflective polarizing element disposed on the first phase delay layer; and

an absorptive polarizing element disposed on the reflective polarizing element,

wherein the absorptive polarizing element admits external light that is in an unpolarized state.

2. The reflective display device of claim 1, wherein the reflection plate specularly reflects at least a part of light transmitted through the liquid crystal layer and incident on the reflection plate, and diffusely reflects at least a part of light transmitted through the liquid crystal layer and incident on the reflection plate.

3. The reflective display device of claim 2, wherein the liquid crystal layer further comprises an uneven surface, and one surface of the reflection plate faces the uneven surface.

4. The reflective display device of claim 2, wherein the reflection plate further comprises an opaque metal.

5. The reflective display device of claim 1, wherein a transmission axis of the reflective polarizing element is parallel to a transmission axis of the absorptive polarizing element.

6. The reflective display device of claim 5, wherein in a state where an electric field is applied to the liquid crystal layer, a Δ

nd value of the liquid crystal layer is (2k+1)λ

/4, and k is an integer equal to or greater than 0.

7. The reflective display device of claim 6, wherein in a state where an electric field is not applied to the liquid crystal layer, the liquid crystal layer is configured to convert a polarization state of light transmitted through the liquid crystal layer and traveling toward the reflection plate to have a phase delayed by (2k+1)λ

/4, as compared with a polarization state of light transmitted through the absorptive polarizing element and traveling toward the reflective polarizing element, and k is an integer equal to or greater than 0.

8. The reflective display device of claim 6, wherein a phase delay value of the first phase delay layer is (2k+1)λ

/4, and k is an integer equal to or greater than 0.

9. The reflective display device of claim 8, further comprising a second phase delay layer disposed between the liquid crystal layer and the reflective polarizing element,

wherein a phase delay value of the second phase delay layer is (k+1)λ

/2, and k is an integer equal to or greater than 0.

10. The reflective display device of claim 9, wherein in a state where an electric field is not applied to the liquid crystal layer, the liquid crystal layer is configured to convert a polarization state of light transmitted through the liquid crystal layer and traveling toward the reflection plate to have a phase delayed by (2k+3)λ

/4, as compared with a polarization state of light transmitted through the absorptive polarizing element and traveling toward the reflective polarizing element, and k is an integer equal to or greater than 0.

11. The reflective display device of claim 6, further comprising a color conversion layer disposed between the liquid crystal layer and the first phase delay layer.

12. The reflective display device of claim 11, wherein the reflective polarizing element further comprises a first refraction layer and a second refraction layer, wherein the second refraction layer has a refractive index different from that of the first refraction layer, and

wherein the first refraction layer and the second refraction layer are stacked alternately.

13. A reflective display device comprising:

a reflection plate;

a liquid crystal layer disposed on the reflection plate, wherein the liquid crystal layer further comprises a twisted nematic liquid crystal,

a reflective polarizing element disposed on the liquid crystal layer; and

an absorptive polarizing element disposed on the reflective polarizing element,

wherein the absorptive polarizing element admits external light that is in an unpolarized state.

14. The reflective display device of claim 13, wherein the reflection plate specularly reflects at least a part of light transmitted through the liquid crystal layer and incident on the reflection plate, and diffusely reflects at least a part of light transmitted through the liquid crystal layer and incident on the reflection plate.

15. The reflective display device of claim 13, wherein a transmission axis of the reflective polarizing element is parallel to a transmission axis of the absorptive polarizing element.

16. The reflective display device of claim 15, further comprising:

a first alignment layer disposed between the reflection plate and the liquid crystal layer; and

a second alignment layer disposed between the liquid crystal layer and the reflective polarizing element,

wherein in a state where an electric field is not applied to the liquid crystal layer, a major axis direction of the twisted nematic liquid crystal adjacent to the second alignment layer is parallel to a transmission axis direction of the reflective polarizing element.

17. The reflective display device of claim 16, wherein in a state where an electric field is not applied to the liquid crystal layer, a major axis direction of the twisted nematic liquid crystal adjacent to the first alignment layer intersects the transmission axis direction of the reflective polarizing element.

18. The reflective display device of claim 16, wherein in a state where an electric field is not applied to the liquid crystal layer, a Δ

nd value of the twisted nematic liquid crystal layer is (2k+1)λ

/4, and k is an integer equal to or greater than 0.

19. The reflective display device of claim 18, wherein in a state where an electric field is not applied to the liquid crystal layer, the liquid crystal layer is configured to convert a polarization state of light transmitted through the liquid crystal layer and traveling toward the reflection plate to have a phase delayed by (2k+1)λ

/4, as compared with a polarization state of light transmitted through the absorptive polarizing element and traveling toward the reflective polarizing element, and k is an integer equal to or greater than 0.

20. The reflective display device of claim 18, wherein the reflective polarizing element further comprises a wire grid pattern.