WO2016052922A1

WO2016052922A1 - Transparent display device capable of blocking external light if necessary

Info

Publication number: WO2016052922A1
Application number: PCT/KR2015/010076
Authority: WO
Inventors: 김재훈; 이유진; 유창재
Original assignee: 한양대학교 산학협력단
Priority date: 2014-09-29
Filing date: 2015-09-24
Publication date: 2016-04-07
Also published as: KR20160038112A; KR101680426B1

Abstract

A transparent display device capable of blocking external light if necessary is provided. The display device comprises a light-adjustment panel and a transparent display panel disposed on the light-adjustment panel. The light-adjustment panel comprises: a lower substrate; an upper substrate; a lower electrode and an upper electrode respectively disposed on mutually facing surfaces of the upper and lower substrates; and a liquid crystal layer disposed between the upper and lower electrodes and having liquid crystal molecules and black bar-type dyes.

Description

Transparent display device to block external light if necessary

The present invention relates to a display device, and more particularly, to an organic light emitting display device.

Information display apparatuses are developing in various aspects according to the development of technology. Among them, the organic light emitting display device is a self-light emitting device that emits light by itself and has an advantage of not requiring a backlight compared to the liquid crystal display device. Therefore, the organic light emitting display device has been attempted as a transparent display device that can transmit external light.

When the screen is displayed in the transparent organic light emitting display device, external light may be transmitted as it is because black does not emit light from the pixel. Therefore, it is known that it is impossible to implement black in the transparent organic light emitting display device. In order to solve this problem, US Patent No. 2007/0057932 discloses a transparent double-sided light emitting panel and a light control unit, which are stacked organic light emitting devices, and the light control unit includes a liquid crystal layer and polarizing plates at both ends thereof.

However, the polarizing plate may be a factor capable of lowering the transmittance of light, thereby reducing the light transmitting ability of the transparent display device. Accordingly, an object of the present invention is to provide a transparent organic light emitting display device capable of blocking external light only when necessary while maintaining light transmission capability.

Technical problems of the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the following description.

In order to achieve the above technical problem, an aspect of the present invention provides a display device. The display device includes a light control panel and a transparent display panel disposed on the light control panel. The light control panel includes a lower electrode, an upper electrode, and a lower electrode and an upper electrode disposed on surfaces of the upper and lower substrates facing each other, and a liquid crystal molecule and black bar dyes disposed between the upper and lower electrodes. Has a layer.

The liquid crystal molecules may have negative dielectric anisotropy. A lower alignment layer may be disposed between the lower electrode and the liquid crystal layer, an upper alignment layer may be disposed between the upper electrode and the liquid crystal layer, and the upper and lower alignment layers may be vertical alignment layers.

The black rod-type dyes may be black including a plurality of rod-type dyes that absorb light of different regions in the visible ray region. The rod-type dyes are azo dyes, anthraquinone dyes, perylene dyes, quinophthalone dyes, azomethine dyes and tolan Tolane dyes, or combinations thereof.

One of the lower electrode and the upper electrode may have a hole. The hole may be circular. Alternatively, a protrusion may be disposed between the upper substrate and the upper electrode. The protrusion may have a conical shape.

The transparent display panel may be an organic light emitting display panel including a pixel electrode, a common electrode, and an organic light emitting function layer disposed between the pixel electrode and the common electrode.

According to the present invention, the light control panel including the liquid crystal molecules and the black rod-type dye can provide a transparent display device that can block external light when necessary by implementing light transmission and blocking without providing a polarizing plate. .

1 and 2 are cross-sectional views illustrating transparent display devices in accordance with one embodiment of the present invention, and are limited to the unit pixel.

3 is a schematic view showing that the liquid crystal molecules are radially symmetrically arranged around the field distortion means.

4 and 5 are cross-sectional views illustrating transparent display devices in accordance with other embodiments of the present invention, and are shown in a limited manner only in unit pixels.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings in order to describe the present invention in more detail. However, the present invention is not limited to the embodiments described herein but may be embodied in other forms. In the figures, where a layer is said to be "on" another layer or substrate, it may be formed directly on the other layer or substrate, or a third layer may be interposed therebetween.

1 and 2 are cross-sectional views illustrating transparent display devices in accordance with one embodiment of the present invention.

Referring to FIG. 1, a light control panel 100 and a transparent display panel 200 stacked on the light control panel 100 are included. The transparent display panel 200 is a panel capable of emitting display light to both sides of the panel, and may be an organic light emitting display panel.

The light control panel 100 includes a lower substrate 110 and an upper substrate 190 facing each other. The

substrates

110 and 190 may be light transmitting substrates, and may be glass substrates.

The lower electrode 130 and the upper electrode 170 may be disposed on surfaces where the lower substrate 110 and the upper substrate 190 face each other. The upper and

lower electrodes

130 and 170 may be a light transmissive or transparent conductive film such as indium tin oxide (ITO) or indium zinc oxide (IZO). One of the lower electrode 130 and the upper electrode 170 may be provided with electric field distortion means. In detail, the upper electrode 170 may include the hole 170a as an electric field distortion means. The width RR of the lower electrode 130 may be larger than the light emitting region ER or the entire pixel electrode 230 which will be described later. In addition, the hole 170a may overlap the emission region ER or the pixel electrode 230, which will be described later, and may be disposed to correspond to the center of the emission region ER or the pixel electrode 230.

The lower alignment layer 140 may be disposed on the lower electrode 130, and the upper alignment layer 160 may be disposed on the upper electrode 170. The

alignment layers

140 and 160 may be formed using polyamic acid, polyimide, lecithin, nylon, or polyvinylalcohol (PVA). . The

alignment layers

140 and 160 are layers oriented by physical rubbing, photoalignment, or groove patterning, and have a pretilt to align the liquid crystal molecules. The upper and

lower alignment layers

140 and 160 may be vertical alignment layers formed by using a polymer having a high branched density, for example, alignment layers whose polar angle of pretilt is nearly 90 °.

The liquid crystal layer 150 may be disposed between the upper and

lower alignment layers

140 and 160. The liquid crystal layer 150 may include liquid crystal molecules LC and a rod-type dye D. Rod-type dye (D) may be contained in about 1 to 15wt%, specifically 10 to 15wt% based on the total weight of the liquid crystal layer 140.

The rod-type dye (D) is a black dye and may be a dichroic dye having different light absorption in the major axis direction and the minor axis direction. As an example, the rod-type dye (D) may have a very high absorption of light in the long axis direction compared to the short axis direction. The rod-type dyes (D) are dyes each of which absorbs all the light in the visible range to show black, or a plurality of rods, specifically 2 to 5, more specifically 2 to 3 different kinds of rods. The dye D may absorb light of different regions in the visible light region and thus absorb all of the light in the visible light region, that is, black. Such rod-type dyes (D) are azo dyes, anthraquinone dyes, perylene dyes, quinophthalone dyes and azomethine dyes. ), Tolane dyes, or a combination thereof.

The liquid crystal molecules LC may have negative dielectric anisotropy such that their major axis is inclined perpendicular to the electric field. In addition, since the upper and

lower alignment layers

140 and 160 are vertical alignment layers, in the state in which no electric field is applied to the upper and

lower electrodes

130 and 170, the liquid crystal molecules LC with respect to the upper and

lower alignment layers

140 and 160. In the vertical direction, that is, perpendicular to the upper and

lower substrates

110 and 190.

Since the rod-type dye (D) has a rod-like shape like the liquid crystal molecules LC, it has a feature of being arranged along the alignment direction of the liquid crystal molecules LC when mixed with the liquid crystal molecules LC. Therefore, in a state in which an electric field is not applied to the upper and

lower electrodes

130 and 170, the rod-shaped dye D may also be arranged in the vertical direction with respect to the upper and

lower alignment layers

140 and 160. Therefore, in a state in which no electric field is applied to the upper and

lower electrodes

130 and 170, the light control panel 100 may transmit light as it is.

The light control panel 100 may further include a thin film transistor electrically connected to the lower electrode 130. In this case, the light control panel 100 may also be driven by an active matrix. However, the present invention is not limited thereto, and the light control panel 100 may be driven by a passive matrix disposed so that the lower electrode 130 and the upper electrode 170 cross each other in the unit element.

The organic light emitting display panel 200 includes a device substrate 210 disposed on the upper substrate 190, a pixel electrode 230 disposed on the device substrate 210, and an organic light emitting function disposed on the pixel electrode 230. The layer 250, the common electrode 270 disposed on the organic light emitting functional layer 250, and the encapsulation substrate 290 disposed on the common electrode 270 may be provided. An encapsulant 280 may be disposed between the common electrode 270 and the encapsulation substrate 290 to block or absorb moisture and oxygen. The device substrate 210 and the encapsulation substrate 290 may be light transmitting substrates, and may be glass substrates.

A thin film transistor 220 may be disposed on the device substrate 210 to be electrically connected to the pixel electrode 230 and to supply or block an electrical signal to the pixel electrode 230. In detail, the buffer layer 215 may be disposed on the device substrate 210. A semiconductor layer 221 having source / drain regions and a channel region disposed therebetween may be disposed on the buffer layer 215, and a gate insulating layer 223 may be disposed on the semiconductor layer 221. The gate electrode 225 crossing the upper portion of the semiconductor layer 221 may be disposed on the gate insulating layer 223. The first interlayer insulating film 226 may be disposed on the gate electrode 225, and the first interlayer insulating film 226 and the gate insulating film 223 may be disposed on the first interlayer insulating film 226. Source / drain electrodes 227 may be disposed to penetrate and connect the source / drain regions, respectively. A second interlayer insulating film 229 may be disposed on the source / drain electrodes 227 to cover the source / drain electrodes 227, and the pixel electrode 230 may be disposed on the second interlayer insulating film 229. Can be. The pixel electrode 230 may be a light transmissive or transparent conductive film such as indium tin oxide (ITO) or indium zinc oxide (IZO).

The pixel defining layer 235 having an opening exposing the pixel electrode 230 may be disposed on the pixel electrode 230. The opening may define the light emitting area ER. The organic light emitting functional layer 250 may be disposed on the pixel electrode 230 exposed in the opening. The organic light emitting functional layer 250 may include a light emitting layer. The organic light emitting functional layer 250 may further include at least one or more of a hole injection layer, a hole transport layer, an electron transport layer, and an electron injection layer. The common electrode 270 is also used as a light transmitting or transparent electrode, for example, a metal such as aluminum, magnesium, calcium, sodium, potassium, indium, yttrium, lithium, silver, lead, cesium, or a combination of two or more thereof. Can be formed.

In the organic light emitting display panel 200, when an electric field is applied between the pixel electrode 230 and the common electrode 270, holes injected from the pixel electrode 230 and electrons injected from the common electrode 270 recombine to form light. Can emit. Meanwhile, the light control panel 100 may transmit external light as well as display light emitted from the organic light emitting display panel 200 because an electric field is not applied to the upper and

lower electrodes

130 and 160. In this case, the display light can be seen on both sides of the display device 300.

Referring to FIG. 2, an electric field is applied to the upper and

lower electrodes

130 and 160 of the light control panel 100 such that the long axis of the liquid crystal molecule LC is inclined perpendicular to the electric field. That is, the long axis of the liquid crystal molecules LC may be disposed substantially horizontally on the upper and

lower substrates

110 and 190. At this time, the rod-type dye (D) may also be arranged almost horizontally along the liquid crystal molecules (LC). In this case, the light control panel 100 may block light due to the rod-type dye, which is a black dye having a very high light absorption in the long axis direction.

In addition, an inclined electric field having a horizontal component instead of a vertical component in the electric field direction is formed around the hole 170a. The hole 170a may be a circular hole. Accordingly, the inclined electric field by the hole 170a may be radially symmetrically disposed about the hole 170a, and the liquid crystal molecules LC exhibiting characteristics in which the long axis is inclined perpendicularly to the electric field are shown in FIG. 3. , And may be radially symmetrically disposed about the hole 170a, and since the rod-type dye D is also disposed in the same direction as the liquid crystal molecules LC, light leakage may be prevented in almost all directions. As such, the light control panel 100 may implement light transmission and blocking without providing a polarizing plate.

The organic light emitting display panel 200 may not emit light because an electric field is not applied between the pixel electrode 230 and the common electrode 270. In this case, black may be implemented on both sides of the display device 300. However, the present invention is not limited thereto, and the organic light emitting display panel 200 may emit light while the light control panel 100 is in a light blocking state. In this case, the image may be viewed only on one surface of the display device 300.

4 and 5 are cross-sectional views illustrating transparent display devices in accordance with other embodiments of the present invention. The transparent organic light emitting display device according to the present embodiment is similar to the transparent organic light emitting display device described with reference to FIGS. 1 and 2 except for the following description.

4 and 5, in the light control panel 100, a protrusion 185, which is an electric field distortion means, is disposed between the upper substrate 190 facing the lower substrate 110 and the upper electrode 170. Can be. The upper electrode 170 positioned on the protrusion 185 does not have a hole (170a of FIG. 1), as described with reference to FIGS. 1 and 2. The protrusion 185 may overlap the emission area ER or the pixel electrode 230, and may be disposed to correspond to the center of the emission area ER or the pixel electrode 230.

As shown in FIG. 4, when no electric field is applied between the upper electrode 170 and the lower electrode 130, the liquid crystal molecules LC and the rod-type dye D may be applied to the upper and

lower substrates

110 and 170. The long axis may be arranged in the vertical direction with respect to. Therefore, in a state in which no electric field is applied to the upper and

lower electrodes

130 and 170, the light control panel 100 may transmit light as it is. Meanwhile, since the upper alignment layer 160 has an inclined surface by the protrusion 185, the liquid crystal molecules LC and the rod-type dye D adjacent to the protrusion 185 are inclined at a predetermined angle with respect to the upper substrate 190. Can be arranged.

On the other hand, as shown in Figure 5, the electric field is applied to the upper and

lower electrodes

130, 160 of the light control panel 100, the long axis of the liquid crystal molecules LC is inclined perpendicular to the electric field. That is, the long axis of the liquid crystal molecules LC may be disposed substantially horizontally on the upper and

lower substrates

110 and 190. At this time, the rod-type dye (D) may also be arranged almost horizontally along the liquid crystal molecules (LC).

In addition, since the upper electrode 170 has an inclined surface around the protrusion 185, an inclined electric field having a horizontal component instead of a vertical component in the electric field direction is made. The protrusion 185 may have a conical shape. Accordingly, the inclined electric field by the protrusion 185 may be radially symmetrically disposed about the protrusion 185, and the liquid crystal molecules LC and the rod-shaped dye D may be radially symmetrically disposed about the protrusion 185. Can be. Therefore, light leakage can be prevented in almost all directions. In this case, the light control panel 100 may block light.

Meanwhile, in the organic light emitting display panel 200, when no light is emitted because an electric field is not applied between the pixel electrode 230 and the common electrode 270, black may be implemented on both sides of the display device 300. have. However, the present invention is not limited thereto, and the organic light emitting display panel 200 may emit light while the light control panel 100 is in the light blocking state. In this case, the image may be viewed only on one surface of the display device 300.

While the invention has been described above with reference to specific preferred embodiments, it is intended that the specific modifications and variations of the invention fall within the scope of the invention and the specific scope of the invention will be apparent from the appended claims.

Claims

A light having a lower electrode and an upper electrode disposed on the lower substrate, the upper substrate, and upper and lower substrates facing each other, and a liquid crystal layer disposed between the upper and lower electrodes and including liquid crystal molecules and black bar dyes. Control panel; And

And a transparent display panel disposed on the light control panel.
The method of claim 1,

The liquid crystal molecules have negative dielectric anisotropy.
The method of claim 2,

A lower alignment layer disposed between the lower electrode and the liquid crystal layer; And

An upper alignment layer disposed between the upper electrode and the liquid crystal layer;

The upper and lower alignment layers are vertical alignment layers.
The method of claim 1,

The black bar-type dyes display black including a plurality of bar-type dyes absorbing light of different regions in the visible light region.
The method according to claim 1 or 4,

The rod-type dyes are azo dyes, anthraquinone dyes, perylene dyes, quinophthalone dyes, azomethine dyes and tolan Display device containing tolane dyes, or a combination thereof.
The method of claim 1,

Any one of the lower electrode and the upper electrode has a hole.
The method of claim 6,

The hole is a circular display device.
The method of claim 1,

And a protrusion disposed between the upper substrate and the upper electrode.
The method of claim 8,

The projection portion has a conical shape.
The method of claim 1,

The transparent display panel is an organic light emitting display panel including a pixel electrode, a common electrode, and an organic light emitting function layer disposed between the pixel electrode and the common electrode.
The lower and upper electrodes, the lower and upper electrodes disposed on the lower substrate, the upper substrate, and the upper and lower substrates facing each other, respectively; A light control panel having liquid crystal layers disposed between them and having liquid crystal molecules having negative dielectric anisotropy and black rod-type dyes, and having electric field distortion means for distorting electric fields generated between the upper and lower electrodes; And

And a transparent display panel disposed on the light control panel.
The method of claim 11,

And the field distortion means is a hole provided in one of the lower electrode and the upper electrode.
The method of claim 12,

The hole is a circular display device.
The method of claim 11,

And the field distortion means is a protrusion disposed between the upper substrate and the upper electrode.
The method of claim 14,

The projection portion has a conical shape.
The method of claim 11,

The transparent display panel is an organic light emitting display panel including a pixel electrode, a common electrode, and an organic light emitting function layer disposed between the pixel electrode and the common electrode.