Display device

Patent metadata

Field	Value
Publication number	US-12396354-B2
Application number	US-202418794409-A
Country	US
Kind code	B2
Filing date	Aug 5, 2024
Priority date	Aug 30, 2023
Publication date	Aug 19, 2025
Grant date	Aug 19, 2025

Abstract

A display device includes: a plurality of pixels arranged in a matrix in a display area, wherein each of the plurality of pixels includes a reflective liquid crystal portion and a self-luminous element portion, in the reflective liquid crystal portion, a first substrate does not include a switching element, a reflector, a pixel electrode, a liquid crystal layer, and an opposite electrode form a reflective liquid crystal display element that operates in bistable liquid crystal display mode, in the self-luminous element portion, the first substrate includes: a switching element; a self-luminous display element including a first electrode, an organic layer, and a second electrode; and a coating layer disposed on a side of the liquid crystal layer of the self-luminous display element, and the coating layer is provided contiguously across the reflective liquid crystal portion and the self-luminous element portion.

First claim

What is claimed is:

1. A display device comprising:
a first substrate including a switching element;
a liquid crystal layer containing liquid crystal molecules; and
a second substrate including an opposite electrode, the first substrate, the liquid crystal layer and the second substrate are provided sequentially,
the display device further comprising a plurality of pixels arranged in a matrix in a display area, wherein
each of the plurality of pixels includes a reflective liquid crystal portion and a self-luminous element portion,

in the reflective liquid crystal portion, the first substrate includes a reflector, a coating layer, and a pixel electrode, which are provided sequentially toward a side of the liquid crystal layer, but does not include a switching element,
the reflector, the pixel electrode, the liquid crystal layer, and the opposite electrode form a reflective liquid crystal display element that operates in bistable liquid crystal display mode,
in the self-luminous element portion, the first substrate includes:
the switching element;
a self-luminous display element including a first electrode, an organic layer, and a second electrode; and

the coating layer disposed on a side of the liquid crystal layer of the self-luminous display element, and
the coating layer is provided contiguously across the reflective liquid crystal portion and the self-luminous element portion.

2. The display device according to claim 1 , further comprising:
a non-display area provided around the display area; and
a wire provided in the non-display area of the first substrate, wherein
in the non-display area, the opposite electrode is connected to the wire, and the pixel electrode is connected to the wire.

3. The display device according to claim 1 , wherein
the liquid crystal layer assumes either one of a first stable state and a second stable state in which the liquid crystal molecules assume different alignment states in absence of applied voltage where a voltage that is lower than a threshold value is applied across the pixel electrode and the opposite electrode, and
the liquid crystal molecules are switched between the first stable state and the second stable state by applying a pulsed voltage across the pixel electrode and the opposite electrode.

4. The display device according to claim 1 , wherein the coating layer is provided contiguously across the plurality of pixels.

5. The display device according to claim 1 , wherein the reflector is disposed in a same layer as the first electrode.

6. The display device according to claim 1 , further comprising:
a vertical alignment film disposed between the first substrate and the liquid crystal layer; and
a grating layer disposed between the second substrate and the liquid crystal layer, wherein
the liquid crystal layer assumes either one of a first stable state in which the liquid crystal molecules assume a vertical alignment and a second stable state in which the liquid crystal molecules assume an HAN alignment in absence of applied voltage where a voltage that is lower than a threshold value is applied across the pixel electrode and the opposite electrode, and
the liquid crystal molecules are switched between the first stable state and the second stable state by applying a pulsed voltage across the pixel electrode and the opposite electrode.

7. The display device according to claim 6 , wherein in the first stable state, the liquid crystal molecules have a pretilt angle of from 85° to 90°, both inclusive, on a side of the first substrate and a pretilt angle of from 85° to 90°, both inclusive, on a side of the second substrate.

8. The display device according to claim 6 , wherein in the second stable state, the liquid crystal molecules have a pretilt angle of from 85° to 90°, both inclusive, on a side of the first substrate and a pretilt angle of from 0° to 5°, both inclusive, on a side of the second substrate.

9. The display device according to claim 1 , further comprising:
a pretilted horizontal alignment film disposed between the first substrate and the liquid crystal layer; and
a grating layer disposed between the second substrate and the liquid crystal layer, wherein
the liquid crystal layer assumes either one of a first stable state in which the liquid crystal molecules assume a TN alignment and a second stable state in which the liquid crystal molecules assume an HAN alignment in absence of applied voltage where a voltage that is lower than a threshold value is applied across the pixel electrode and the opposite electrode, and
the liquid crystal molecules are switched between the first stable state and the second stable state by applying a pulsed voltage across the pixel electrode and the opposite electrode.

10. The display device according to claim 9 , wherein
in the first stable state, the liquid crystal molecules have a pretilt angle of from 3° to 5°, both inclusive, on a side of the first substrate and a pretilt angle of from 0° to 5°, both inclusive, on a side of the second substrate, and
an alignment direction of the liquid crystal molecules on the side of the first substrate and an alignment direction of the liquid crystal molecules on the side of the second substrate make an angle of from 80° to 90°, both inclusive, in a plan view.

11. The display device according to claim 9 , wherein in the second stable state, the liquid crystal molecules have a pretilt angle of from 3° to 5°, both inclusive, on a side of the first substrate and a pretilt angle of from 85° to 90°, both inclusive, on a side of the second substrate.

12. The display device according to claim 1 , further comprising:
a weak anchoring alignment film disposed between the first substrate and the liquid crystal layer; and
a strong anchoring alignment film disposed between the second substrate and the liquid crystal layer, wherein
the liquid crystal layer assumes either one of a first stable state in which the liquid crystal molecules assume a homogeneous alignment and a second stable state in which the liquid crystal molecules on a side of the first substrate assume a twisted alignment in which these liquid crystal molecules are twisted by 180° from the first stable state in a plan view, in absence of applied voltage where a voltage that is lower than a threshold value is applied across the pixel electrode and the opposite electrode, and
the liquid crystal molecules are switched between the first stable state and the second stable state by applying a pulsed voltage across the pixel electrode and the opposite electrode.

13. The display device according to claim 12 , wherein
in the first stable state, the liquid crystal molecules have a pretilt angle of from 0° to 5°, both inclusive, on the first substrate and a pretilt angle of from 5° to 10°, both inclusive, on a side of the second substrate, and
an alignment direction of the liquid crystal molecules on the side of the first substrate and an alignment direction of the liquid crystal molecules on the side of the second substrate make an angle of from 0° to 10°, both inclusive, in a plan view.

14. The display device according to claim 12 , wherein
in the second stable state, the liquid crystal molecules have a pretilt angle of from 0° to 5°, both inclusive, on the side of the first substrate and a pretilt angle of from 5° to 10°, both inclusive, on a side of the second substrate,
an alignment direction of the liquid crystal molecules on the side of the first substrate and an alignment direction of the liquid crystal molecules on the side of the second substrate make an angle of from 0° to 10°, both inclusive, in a plan view, and

Assignees

• Sharp Display Technology Corp

Inventors

• Tsuchiya Hiroshi
• Satoh Takashi

Classifications

• G02F1/133746

  for high pretilt angles, i.e. higher than 15 degrees · CPC title

• G02F1/133769

  comprising an active, e.g. switchable, alignment layer · CPC title

• G02F1/1397

  the twist being substantially higher than 90°, e.g. STN-, SBE-, OMI-LC cells · CPC title

• G02F1/133749

  for low pretilt angles, i.e. lower than 15 degrees · CPC title

• G02F2201/123

  pixel · CPC title