Light control device and display device using the same

Patent metadata

Field	Value
Publication number	US-9964827-B1
Application number	US-201715652818-A
Country	US
Kind code	B1
Filing date	Jul 18, 2017
Priority date	Jul 18, 2017
Publication date	May 8, 2018
Grant date	May 8, 2018

Abstract

A light control device and a display device using the same. The light control device includes a polymer networked liquid crystal (PNLC) or polymer dispersed liquid crystal (PDLC) display switchable between a scattering state and a first display state, and a guest-host (G-H) liquid crystal display (LCD) switchable between a transparent state and a second display state. A light source of the G-H LCD is disposed at a side of the PNLC or PDLC display and aligned to its liquid crystal layer. In a first operational mode, the PNLC or PDLC display is switched to the first display state, and the G-H LCD is switched to the transparent state and becomes transparent. In a second operational mode, the G-H LCD is switched to the second display state, and the PNLC or PDLC display is switched to the scattering state to function as a light guide layer for the G-H LCD.

First claim

What is claimed is:

1. A display device, comprising:
a black film; and
a light control display stack disposed on the black film, comprising:
a polymer networked liquid crystal (PNLC) or polymer dispersed liquid crystal (PDLC) display disposed on the black film, the PNLC or PDLC display defining a plurality of first pixels and being switchable between a scattering state and a first display state, wherein in the first display state, each of the plurality of first pixels of the PNLC or PDLC display is configured to be turned on to become transparent or be turned off to become translucent, and in the scattering state, each of the plurality of first pixels of the PNLC or PDLC display is configured to be turned off; and
a guest-host (G-H) liquid crystal display (LCD) disposed on the PNLC or PDLC display and facing an outer environment, the G-H LCD defining a plurality of second pixels and being switchable between a transparent state and a second display state, wherein in the second display state, each of the plurality of second pixels of the G-H LCD is configured to be turned off to transmit light emitted internally by a light source of the G-H LCD or be turned on to become opaque, and in the transparent state, each of the plurality of second pixels of the G-H LCD is configured to be turned off to become transparent;

wherein in a first operational mode, the PNLC or PDLC display is configured to switch to the first display state for displaying image data, and the G-H LCD is configured to switch to the transparent state and becomes transparent, such that light from the outer environment is allowed to incident to and pass through the G-H LCD in the transparent state and reflected by the first pixels of the PNLC or PDLC display being turned on in the first display state; and
wherein in a second operational mode, the G-H LCD is configured to switch to the second display state for displaying the image data, and the PNLC or PDLC display is configured to switch to the scattering state to function as a light guide layer for the G-H LCD, such that the light emitted internally by the light source of the G-H LCD is guided by the PNLC or PDLC display in the scattering state toward the G-H LCD in the second display state.

2. The display device of claim 1 , wherein the light control display stack further comprises an adhesive layer disposed between the PNLC or PDLC display and the G-H LCD, such that no air gap exists between the PNLC or PDLC display and the G-H LCD.

3. The display device of claim 1 , further comprising a glass layer disposed on the G-H LCD facing the outer environment.

4. The display device of claim 1 , wherein the PNLC or PDLC display comprises:
a first substrate disposed on the black film;
a second substrate facing the G-H LCD and spaced apart to the first substrate, forming a first cell gap between the first substrate and the second substrate; and
a liquid crystal layer disposed in the first cell gap between the first substrate and the second substrate and having PNLC or PDLC molecules, the liquid crystal layer defining the plurality of first pixels, wherein each of the plurality of first pixels comprises:
a first transparent electrode disposed on the first substrate and facing the liquid crystal layer; and
a second transparent electrode disposed on the second substrate and facing the liquid crystal layer, wherein:
when the PNLC or PDLC display is switched to the first display state, for each of the plurality of first pixels, the first transparent electrode and the second transparent electrode are provided with a voltage difference to form an electric field to control the alignment of the PNLC or PDLC molecules between the first transparent electrode and the second transparent electrode of the first pixel, such that each of the plurality of first pixels is configured to be turned on to become transparent or be turned off to become translucent; and
when the PNLC or PDLC display is switched to the scattering state, for each of the plurality of first pixels, the first transparent electrode and the second transparent electrode are not provided with the voltage difference, such that the PNLC or PDLC molecules of all of the plurality of first pixels are randomly arranged, and the light is scattered and diffused when passing through the PNLC or PDLC display such that the light is guided toward the G-H LCD.

5. The light control device of claim 1 , wherein the G-H LCD comprises:
a third substrate facing the PNLC or PDLC display;
a fourth substrate facing the outer environment and spaced apart to the third substrate, forming a second cell gap between the third substrate and the fourth substrate; and
a G-H liquid crystal layer disposed in the second cell gap between the third substrate and the fourth substrate and having G-H liquid crystal molecules, the G-H liquid crystal layer defining a plurality of second pixels, wherein the G-H liquid crystal molecules comprise negative liquid crystal molecules and dichroic dye molecules dissolved in the negative liquid crystal molecules, such that orientations of the dichroic dye molecules and dipoles are parallel to the negative liquid crystal molecules, and wherein each of the plurality of second pixels comprises:
a third transparent electrode disposed on the third substrate and facing the G-H liquid crystal layer; and
a fourth transparent electrode disposed on the fourth substrate and facing the G-H liquid crystal layer, wherein:
when the G-H LCD is switched to the second display state, the light source is turned on, and for each of the plurality of second pixels, the third transparent electrode and the fourth transparent electrode are either provided with a voltage difference to form an electric field to control alignment of the G-H liquid crystal molecules to turn on the second pixel, or not provided with the voltage difference such that the second pixel is turned off, such that the light emitted by the light source and guided by the PNLC or PDLC display in the scattering state is allowed to pass through at least some of the plurality of second pixels being turned off; and
when the G-H LCD is switched to the transparent state, the light source is turned off, and for each of the plurality of second pixels, the third transparent electrode and the fourth transparent electrode are not provided with the voltage difference, such that the G-H liquid crystal molecules of all of the second pixels are arranged to be transparent.

6. The display device of claim 5 , wherein the light source is configured to emit the light toward the G-H LCD, and the light source is a light-emitting diode (LED) chip disposed at a side of the PNLC or PDLC display.

7. The display device of claim 6 , wherein the LED chip comprises a plurality of LEDs having red (R), green (G) and blue (B) colors.

8. A light control device, comprising:
a first display panel, defining a plurality of first pixels and being switchable between a scattering state and a first display state, wherein in the first display state, each first pixel of the first display panel is configured to be turned on to become transparent or be turned off to become translucent, and in the scattering state, each first pixel of the first display panel is configured to be turned off; and
a second display panel disposed on the first display panel and facing an outer environment, the second display panel defining a plurality of second pixels and being switchable between a transparent state and a second display state, wherein in the second display state, each second pixel of the second display panel is configured to be turned off to transmit light emitted internally by a light source of the second display panel or be turned on to become opaque, and in the transparent state, each second pixel

Assignees

• A U Vista Inc

Inventors

• Lee Seok-Lyul
• Luo Fang-Chen

Classifications

• G02F1/1334 Primary

  based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals · CPC title

• G02F2201/44

  Arrangements combining different electro-active layers, e.g. electrochromic, liquid crystal or electroluminescent layers · CPC title

• G02F1/13476 Primary

  in which at least one liquid crystal cell or layer assumes a scattering state · CPC title

• G02F2202/28

  Adhesive materials or arrangements · CPC title

• G02F1/13475

  in which at least one liquid crystal cell or layer is doped with a pleochroic dye, e.g. GH-LC cell (G02F1/13476 takes precedence) · CPC title