Display device

Patent metadata

Field	Value
Publication number	US-12164207-B2
Application number	US-202118272490-A
Country	US
Kind code	B2
Filing date	Jan 22, 2021
Priority date	Jan 22, 2021
Publication date	Dec 10, 2024
Grant date	Dec 10, 2024

Abstract

A display device includes: a TFT substrate including a thin film transistor; a light-emitting element including a first electrode and a second electrode overlapping each other in a plan view, and a light-emitting layer placed between the first electrode and the second electrode; a third electrode capable of forming an electrical field between the second electrode and the third electrode; an optical adjustment element overlapping the light-emitting layer in a plan view and having an optical characteristic that changes in accordance with a potential difference between the second electrode and the third electrode; and light scattering bodies included in at least one of the TFT substrate, the light-emitting element, and the optical adjustment element.

First claim

The invention claimed is:

1. A display device comprising:
a TFT substrate including a thin film transistor;
a light-emitting element including a first electrode and a second electrode overlapping each other in a plan view, and a light-emitting layer placed between the first electrode and the second electrode;
a third electrode capable of forming an electrical field between the second electrode and the third electrode;
an optical adjustment element overlapping the light-emitting layer in a plan view and having an optical characteristic that changes in accordance with a potential difference between the second electrode and the third electrode; and
light scattering bodies included in at least one of the TFT substrate, the light-emitting element, and the optical adjustment element,
wherein the optical adjustment element is in one of multiple optical states in accordance with the potential difference,
when the potential difference exceeds a first voltage, the optical adjustment element switches from a light blocking state to a transient state,
when the potential difference exceeds a second voltage, the optical adjustment element switches from the transient state to a light transmitting state,
during a non-light emission period of the light-emitting layer, the optical adjustment element is in the light blocking state,
during a light emission period of the light-emitting layer, the optical adjustment element is in the transient state or the light transmitting state,
a potential of the first electrode and a potential of the third electrode are fixed, and
a potential of the second electrode during the light emission period is higher than a potential of the second electrode during the non-light emission period.

2. The display device according to claim 1 ,
wherein the TFT substrate includes a light scattering layer containing the light scattering bodies.

3. The display device according to claim 1 ,
wherein the light-emitting element includes a charge transport layer containing the light scattering bodies.

4. The display device according to claim 1 ,
wherein the optical adjustment element is an electrophoretic layer containing toner movable by an electrical field between the second electrode and the third electrode.

5. The display device according to claim 4 ,
wherein when the optical adjustment element is in a light blocking state, the toner overlaps the light-emitting layer in a plan view, and
when the optical adjustment element is in a light transmitting state, the toner does not overlap the light-emitting layer in a plan view.

6. A display device comprising:
a TFT substrate including a thin film transistor;
a light-emitting element including a first electrode and a second electrode overlapping each other in a plan view, and a light-emitting layer placed between the first electrode and the second electrode;
a third electrode capable of forming an electrical field between the second electrode and the third electrode;
an optical adjustment element overlapping the light-emitting layer in a plan view and having an optical characteristic that changes in accordance with a potential difference between the second electrode and the third electrode; and
light scattering bodies included in at least one of the TFT substrate, the light-emitting element, and the optical adjustment element,
wherein the optical adjustment element is in one of multiple optical states in accordance with the potential difference,
when the potential difference exceeds a first voltage, the optical adjustment element switches from a light blocking state to a transient state,
when the potential difference exceeds a second voltage, the optical adjustment element switches from the transient state to a light transmitting state,
the optical adjustment element includes a liquid crystal layer, and a first polarizer and a second polarizer having polarization axes parallel to each other, and
the liquid crystal layer is placed between the first polarizer and the second polarizer.

7. The display device according to claim 6 ,
wherein when the optical adjustment element is in the light blocking state, a polarization direction of light incident on the liquid crystal layer is rotated by 90 degrees, and
when the optical adjustment element is in the light transmitting state, a polarization direction of light incident on the liquid crystal layer is maintained.

8. The display device according to claim 6 ,
wherein the TFT substrate is provided below the first electrode and the second electrode,
the third electrode is provided above the first electrode and the second electrode, and
the liquid crystal layer is placed between the second electrode and the third electrode.

9. The display device according to claim 8 ,
wherein between the second electrode and the third electrode, the first polarizer and the second polarizer are disposed.

10. The display device according to claim 8 ,
wherein between the second electrode and the third electrode, the first polarizer is placed, and
the second polarizer is placed above the third electrode.

11. The display device according to claim 6 ,
wherein the second electrode and the third electrode are provided adjacent to each other in a planar direction, and
the liquid crystal layer adopts a transverse electrical field control mode.

12. A display device comprising:
a TFT substrate including a thin film transistor;
a light-emitting element including a first electrode and a second electrode overlapping each other in a plan view, and a light-emitting layer placed between the first electrode and the second electrode;
a third electrode capable of forming an electrical field between the second electrode and the third electrode;
an optical adjustment element overlapping the light-emitting layer in a plan view and having an optical characteristic that changes in accordance with a potential difference between the second electrode and the third electrode; and
light scattering bodies included in at least one of the TFT substrate, the light-emitting element, and the optical adjustment element,
wherein the light scattering bodies are contained in the optical adjustment element,
during a non-light emission period of the light-emitting layer, the optical adjustment element is in a transparent state, and
during a light emission period of the light-emitting layer, the optical adjustment element is in a light scattering state.

13. The display device according to claim 12 ,
wherein the light scattering bodies are made of a material having a quadratic electro-optical effect.

14. The display device according to claim 13 ,
wherein the light scattering state appears due to a quadratic electro-optical effect of the light scattering bodies.

15. The display device according to claim 12 ,
wherein the optical adjustment element includes a light-transmissive layer and the light scattering bodies being particles and distributed in the light-transmissive layer, and
the light-transmissive layer has a thickness of 1.0 μm or less, and the light scattering bodies have a radius of 200 nm or more.

16. The display device according to claim 12 , comprising:
a first subpixel, a second subpixel, and a third subpixel,
wherein each of the first subpixel, the second subpixel, and the third subpixel includes the light-emitting element and the optical adjustment element,
light emitted by a light-emitting layer of the first subpixel has a longer wavelength than light emitted by a light-emitting layer of the third subpixel, and
a density of light scattering bodies in the optical adjustment eleme

Assignees

• Sharp Kk

Inventors

• Kitazawa Tazuko
• Ueta Yoshihiro
• Satoh Eiji
• Kin Zenken

Classifications

• H10K59/877

  comprising scattering means · CPC title

• G02F1/167

  by electrophoresis · CPC title

• G02F1/1368 Primary

  in which the switching element is a three-electrode device {(G02F1/136277 takes precedence)} · CPC title

• G02F1/133528

  Polarisers · CPC title

• G02F1/1677 Primary

  Structural association of cells with optical devices, e.g. reflectors or illuminating devices · CPC title