KR102619051B1 - Mirror cell and display device comprising the same - Google Patents

Abstract

The present invention provides a mirror cell that can improve haze characteristics and expand the light reflection wavelength band, and a display device including the same. A mirror cell according to an embodiment of the present invention includes a lower substrate, an upper substrate, a central substrate, first and second liquid crystal layers, and a UV absorption layer. The lower substrate includes a lower alignment layer and a lower electrode, and the upper substrate includes an upper alignment layer and an upper electrode facing the lower substrate. The central substrate is disposed between the lower substrate and the upper substrate, and includes a first central alignment layer and a first central electrode on the side facing the lower substrate, and a second central alignment layer and a second central electrode on the side opposite the upper substrate. do. The first liquid crystal layer is disposed between the lower substrate and the central substrate, and the second liquid crystal layer is disposed between the central substrate and the upper substrate. The UV absorbing layer is disposed on at least one side of the central substrate.

Description

Mirror cell and display device including same {MIRROR CELL AND DISPLAY DEVICE COMPRISING THE SAME}

The present invention relates to a display device, and more specifically, to a display device including a mirror cell capable of transmitting or reflecting light.

As the information society develops, the demand for display devices for displaying images is increasing in various forms. The display device field has been rapidly changing toward thin, light, large-area flat panel displays (FPDs) replacing bulky cathode ray tubes (CRTs). Flat panel displays include Liquid Crystal Display Device (LCD), Plasma Display Panel (PDP), Organic Light Emitting Display Device (OLED), and Electrophoretic Display Device. : ED), etc.

Recently, a technology has been developed to selectively use a display mode and a mirror mode by equipping the display device with mirror cells that control the transmission and reflection of light. Liquid crystal cells are a representative example of mirror cells that control the transmission and reflection of light. Liquid crystals used in liquid crystal cells include twisted nematic liquid crystal, semitic liquid crystal, and cholesteric liquid crystal. Among these, cholesteric liquid crystals have been used in reflective display devices.

Cholesteric liquid crystal is a liquid crystal mixture containing a chiral dopant that induces a periodic helical structure, and has the property of selectively reflecting light depending on the twist direction of the helix and the pitch of the repeating structure. At this time, the wavelength of the reflected light is expressed as the product of the average refractive index of the liquid crystal and the pitch of the cholesteric liquid crystal, and a typical cholesteric liquid crystal reflects light in the 50 nm wavelength range. By manufacturing cholesteric liquid crystals with various pitches, the wavelength range of reflected light can be expanded. Therefore, research is continuing to expand the wavelength range of reflected light by manufacturing cholesteric liquid crystals with various pitches.

The present invention provides a mirror cell that can improve haze characteristics and expand the light reflection wavelength band, and a display device including the same.

To achieve the above object, the mirror cell according to an embodiment of the present invention includes a lower substrate, an upper substrate, a central substrate, first and second liquid crystal layers, and a UV absorption layer. The lower substrate includes a lower alignment layer and a lower electrode, and the upper substrate includes an upper alignment layer and an upper electrode facing the lower substrate. The central substrate is disposed between the lower substrate and the upper substrate, and includes a first central alignment layer and a first central electrode on the side facing the lower substrate, and a second central alignment layer and a second central electrode on the side opposite the upper substrate. do. The first liquid crystal layer is disposed between the lower substrate and the central substrate, and the second liquid crystal layer is disposed between the central substrate and the upper substrate. The UV absorbing layer is disposed on at least one side of the central substrate.

The first liquid crystal layer reflects light of either left-circularly polarized light or right-handed circularly polarized light, and the second liquid crystal layer reflects the remaining light of left-circularly polarized light or right-handed circularly polarized light.

The first liquid crystal layer and the second liquid crystal layer include at least a cholesteric liquid crystal, a chiral dopant, and a reactive liquid crystal.

The UV absorption layer is disposed between the first central electrode and the first central alignment layer.

The UV absorption layer is disposed between the second central electrode and the second central alignment layer.

The UV absorption layer is composed of at least one of benzophenone-based, benzotriazole-based, salicylic acid-based, acrylonitrile-based, organic nickel compounds, monobenzoic acid-based, or mixtures thereof.

The UV absorbing layer has a thickness of 0.1 to 100 μm.

Additionally, the mirror cell according to an embodiment of the present invention includes a lower substrate, an upper substrate, a central substrate, a column spacer, first and second liquid crystal layers, and a UV absorber. The lower substrate includes a lower alignment layer and a lower electrode, and the upper substrate includes an upper alignment layer and an upper electrode facing the lower substrate. The central substrate is disposed between the lower substrate and the upper substrate, and includes a first central alignment layer and a first central electrode on the side facing the lower substrate, and a second central alignment layer and a second central electrode on the side opposite the upper substrate. do. The first liquid crystal layer is disposed between the lower substrate and the central substrate, and the second liquid crystal layer is disposed between the central substrate and the upper substrate. Column spacers are disposed between the lower electrode and the lower alignment layer and between the second central electrode and the second central alignment layer, respectively. The UV absorber is included in at least one of the first central alignment layer or the second central alignment layer.

The first liquid crystal layer reflects light of either left-circularly polarized light or right-handed circularly polarized light, and the second liquid crystal layer reflects the remaining light of left-circularly polarized light or right-handed circularly polarized light.

The first liquid crystal layer and the second liquid crystal layer include at least a cholesteric liquid crystal, a chiral dopant, and a reactive liquid crystal.

A UV absorber is included in the first central alignment layer.

A UV absorber is included in the second central alignment layer.

The UV absorber consists of at least one of benzophenone-based, benzotriazole-based, salicylic acid-based, acrylonitrile-based, organic nickel compounds, monobenzoic acid-based, or mixtures thereof.

The UV absorber is included in an amount of 0.1 to 30 wt% based on 100 wt% of the first or second central alignment layer.

Additionally, a display device according to an embodiment of the present invention includes a display panel and a mirror cell. Mirror cells are located on the display panel and implement reflection mode and transmission mode. The mirror cell includes a lower substrate, an upper substrate, a central substrate, first and second liquid crystal layers, and a UV absorption layer. The lower substrate includes a lower alignment layer and a lower electrode, and the upper substrate includes an upper alignment layer and an upper electrode facing the lower substrate. The central substrate is disposed between the lower substrate and the upper substrate, and includes a first central alignment layer and a first central electrode on the side facing the lower substrate, and a second central alignment layer and a second central electrode on the side opposite the upper substrate. do. The first liquid crystal layer is disposed between the lower substrate and the central substrate, and the second liquid crystal layer is disposed between the central substrate and the upper substrate. The UV absorbing layer is disposed on at least one side of the central substrate.

Additionally, a display device according to an embodiment of the present invention includes a display panel and a mirror cell. The mirror cell includes a lower substrate, an upper substrate, a central substrate, a column spacer, first and second liquid crystal layers, and a UV absorber. The lower substrate includes a lower alignment layer and a lower electrode, and the upper substrate includes an upper alignment layer and an upper electrode facing the lower substrate. The central substrate is disposed between the lower substrate and the upper substrate, and includes a first central alignment layer and a first central electrode on the side facing the lower substrate, and a second central alignment layer and a second central electrode on the side opposite the upper substrate. do. The first liquid crystal layer is disposed between the lower substrate and the central substrate, and the second liquid crystal layer is disposed between the central substrate and the upper substrate. Column spacers are disposed between the lower electrode and the lower alignment layer and between the second central electrode and the second central alignment layer, respectively. The UV absorber is included in at least one of the first central alignment layer or the second central alignment layer.

The mirror cell according to an embodiment of the present invention has first and second liquid crystal layers containing reactive liquid crystals, thereby realizing a mirror cell with a neutral reflective color, simplifying the stacked structure to reduce driving voltage and production costs, and reducing the cell gap. The thickness can also be reduced to achieve a thin design.

In addition, the mirror cell according to an embodiment of the present invention is provided with a UV absorbing layer or a UV absorbing material, thereby preventing scattered UV light from being irradiated to the first liquid crystal layer located below due to the two UV irradiation processes. Therefore, it is possible to prevent the haze of the mirror cell from increasing due to scattered UV light.

1 is a cross-sectional view showing a display device.
Figure 2 is a cross-sectional view showing an organic light emitting display panel.
Figure 3 is a cross-sectional view showing the liquid crystal display panel.
Figure 4 is a cross-sectional view showing a mirror cell.
Figure 5 is a cross-sectional view showing the liquid crystal layer.
Figure 6 is a cross-sectional view showing a mirror cell having multiple liquid crystal layers.
Figure 7 is a cross-sectional view showing a mirror cell according to an embodiment of the present invention.
Figure 8 is a cross-sectional view showing the liquid crystal layer of the present invention.
Figure 9 is a diagram showing the pitch formation mechanism of cholesteric liquid crystal.
Figure 10 is a cross-sectional view showing a mirror cell according to an embodiment of the present invention.
11 to 13 are cross-sectional views showing a mirror cell according to an embodiment of the present invention.
14 to 16 are cross-sectional views showing mirror cells according to another embodiment of the present invention.
Figure 17 is a diagram showing the manufacturing process of the mirror cell of the present invention.
Figure 18 is a graph showing the reflectance by wavelength of the mirror cell manufactured according to Comparative Example 1.
Figure 19 is a graph showing the reflectance by wavelength of the mirror cell manufactured according to Comparative Example 2.
Figure 20 is a graph showing reflectance by wavelength of mirror cells manufactured according to an example.
Figures 21 to 23 are graphs showing the reflectance by wavelength band before UV irradiation, after 10 minutes of UV irradiation, and after 20 minutes of UV irradiation according to the content of the UV absorber in the mirror cell manufactured according to Comparative Example 3.

Hereinafter, some embodiments of the present invention will be described in detail through illustrative drawings. When adding reference numerals to components in each drawing, it should be noted that identical components are given the same reference numerals as much as possible even if they are shown in different drawings. Additionally, when describing embodiments of the present invention, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present invention, the detailed description will be omitted.

Additionally, when describing the components of the invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are only used to distinguish the component from other components, and the nature, order, or order of the component is not limited by the term. When a component is described as being “connected,” “coupled,” or “connected” to another component, that component may be directly connected or connected to that other component, but there is another component between each component. It will be understood that elements may be “connected,” “combined,” or “connected.” In the same context, when a component is described as being formed “on” or “under” another component, that component means that it is formed directly on that other component or indirectly through another component. It should be understood as including.

The display panel of the display device according to the present invention disclosed below may be an organic light emitting display panel, a liquid crystal display panel, an electrophoretic display panel, etc. In the present invention, a liquid crystal display panel is explained as an example. The liquid crystal display panel is made up of a thin film transistor array substrate with pixel electrodes and a common electrode formed on thin film transistors, a color filter substrate, and a liquid crystal layer sandwiched between these two substrates. The liquid crystal is driven by a horizontal electric field. Additionally, the display panel according to the present invention may be an organic light emitting display panel. For example, an organic light emitting display panel includes a first electrode connected to a thin film transistor, a second electrode, and a light emitting layer made of organic material between them. Therefore, holes supplied from the first electrode and electrons supplied from the second electrode combine in the light emitting layer to form excitons, which are hole-electron pairs, and emit light by the energy generated when the excitons return to the ground state.

FIG. 1 is a cross-sectional view showing a display device, FIG. 2 is a cross-sectional view showing an organic light emitting display panel, FIG. 3 is a cross-sectional view showing a liquid crystal display panel, FIG. 4 is a cross-sectional view showing a mirror cell, and FIG. 5 is a cross-sectional view showing a liquid crystal layer. , and Figure 6 is a cross-sectional view showing a mirror cell having multiple liquid crystal layers.

Referring to FIG. 1, the display device 100 includes a display panel 110 and a mirror cell 150 disposed on the display panel 110.

The display panel 110 displays an image and is made of an organic light emitting display panel or a liquid crystal display panel shown in FIGS. 2 and 3, respectively. The display panel 110 will be described with reference to FIGS. 2 and 3 as follows.

Referring to FIG. 2, when the display panel is an organic light emitting display panel, the organic light emitting display panel emits light from a plurality of subpixels to implement full color. Taking one subpixel among a plurality of subpixels as an example, the active layer ACT is located on the first substrate SUB1. The active layer (ACT) may be made of a silicon semiconductor or an oxide semiconductor. The silicon semiconductor may include amorphous silicon or crystallized polycrystalline silicon, and in this embodiment, it may be an active layer (ACT) made of polycrystalline silicon. A gate insulating layer (GI) is located on the active layer (ACT). The gate insulating film (GI) may be silicon oxide (SiOx), silicon nitride (SiNx), or a multilayer thereof. A gate electrode (GAT) is positioned on the gate insulating film (GI) to correspond to the active layer (ACT). The gate electrode (GAT) is selected from the group consisting of molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), and copper (Cu). It is formed from any one or an alloy thereof. In addition, the gate electrode (GAT) is a group consisting of molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), and copper (Cu). It may be a multi-layer made of any one selected from or an alloy thereof. For example, the gate electrode (GAT) may be a double layer of molybdenum/aluminum-neodymium or molybdenum/aluminum.

An interlayer insulating layer (ILD) is located on the gate electrode (GAT). The interlayer insulating layer (ILD) may be a silicon oxide layer (SiOx), a silicon nitride layer (SiNx), or a multilayer thereof. A source electrode (SE) and a drain electrode (DE) electrically connected to the semiconductor layer (ACT) are located on the interlayer dielectric (ILD). The source electrode (SE) and drain electrode (DE) may be made of a single layer or multiple layers. If the source electrode (SE) and drain electrode (DE) are a single layer, molybdenum (Mo), aluminum (Al), chromium ( It may be made of any one selected from the group consisting of Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), and copper (Cu), or an alloy thereof. In addition, when the source electrode (SE) and drain electrode (DE) are multi-layered, they are a double layer of molybdenum/aluminum-neodymium, a triple layer of titanium/aluminum/titanium, molybdenum/aluminum/molybdenum, or a triple layer of molybdenum/aluminum-neodymium/molybdenum. It can be done. Accordingly, a thin film transistor is configured including a semiconductor layer (ACT), a gate electrode (GAT), a source electrode (SE), and a drain electrode (DE).

The color filter (CF) is located on the first substrate (SUB1) including the thin film transistor. The color filter (CF) serves to convert light into red, green, and blue. An organic insulating layer (PAC) is located on the first substrate (SUB1) on which the color filter (CF) is disposed. The organic insulating film (PAC) may be a planarization film to alleviate the level difference in the lower structure, and is made of organic materials such as polyimide, benzocyclobutene series resin, and acrylate. The organic insulating layer (PAC) includes a via hole (VIA) exposing the drain electrode (DE).

The first electrode (ANO) is located on the organic insulating film (PAC). The first electrode (ANO) is an anode and is made of a transparent conductive film such as ITO or IZO with a high work function. When the first electrode (ANO) is a reflective electrode, it may include a reflective layer below the transparent conductive film. The first electrode (ANO) surrounds the via hole (VIA) and is connected to the drain electrode (DE).

The bank layer (BNK) is located on the first substrate (SUB1) including the first electrode (ANO). The bank layer (BNK) may be a pixel defining layer that defines a pixel by exposing a portion of the first electrode (ANO). The bank layer (BNK) is made of organic materials such as polyimide, benzocyclobutene series resin, and acrylate. The bank layer (BNK) is provided with an opening (OP) exposing the first electrode (ANO).

An organic layer (EML) is located on the bank layer (BNK). The organic layer (EML) is a layer that emits light by combining electrons and holes, and includes at least an emitting layer. Additionally, the organic layer (EML) may include one or more of a hole injection layer, a hole transport layer, an electron transport layer, or an electron injection layer, and one or more of the layers may be omitted. The second electrode (CAT) is located on the first substrate (SUB1) on which the organic layer (EML) is formed. The second electrode (CAT) is a cathode electrode and may be made of magnesium (Mg), calcium (Ca), aluminum (Al), silver (Ag), or an alloy thereof with a low work function. The second electrode (CAT) may be thin enough to transmit light and act as a transmission electrode, or may be thick enough to reflect light and act as a reflective electrode. That is, it includes an organic light emitting diode including a first electrode (ANO), an organic layer (EML), and a second electrode (CAT). Although not shown, an encapsulation layer of an inorganic or organic film that encapsulates the devices below may be further included on the second electrode (CAT). Therefore, the white light emitted from the organic layer (EML) is converted into red, green, and blue through the color filter (CF) to implement a full-color image.

Meanwhile, referring to FIG. 3, the display panel of the present invention may be a liquid crystal display panel. In the liquid crystal display panel, a gate electrode (GAT) is located on a first substrate (SUB1), and a gate insulating film (GI) that insulates the gate electrode (GAT) is located on the gate electrode (GAT). The active layer (ACT) is located on the gate insulating layer (GI), the source electrode (SE) contacts one side of the active layer (ACT), and the drain electrode (DE) contacts the other side of the active layer (ACT). . Accordingly, a thin film transistor is formed including a gate electrode (GAT), an active layer (ACT), a source electrode (SE), and a drain electrode (DE).

An organic insulating film (PAC) is located on the first substrate (SUB1) including the thin film transistor. The organic insulating layer (PAC) includes a via hole (VIA) exposing the drain electrode (DE). A pixel electrode (PXL) and a common electrode (COM) are located on the organic insulating film (PAC). The pixel electrode (PXL) is connected to the drain electrode (DE) through a via hole (VIA) formed in the organic insulating layer (PAC). The pixel electrode PXL and the common electrode COM are arranged alternately to form a horizontal electric field between the pixel electrode PXL and the common electrode COM.

A second substrate (SUB2) is located opposite to the first substrate (SUB1). The second substrate SBU2 may be a color filter array substrate, and a color filter may be disposed on the second substrate SBU2. However, the present invention is not limited to this, and a color filter may be disposed on the first substrate SUB1. The liquid crystal layer LC is located between the first substrate SUB1 and the second substrate SUB2. In an embodiment of the present invention, an in-plane switching (IPS) liquid crystal display device in which a pixel electrode and a common electrode are located on the same plane is described as an example. However, the present invention is not limited to this, and the common electrode may be located below the pixel electrode, or the common electrode may be located on the second substrate.

The display device 100 is provided with a mirror cell 150 on the display panel 110 described above. Hereinafter, we will take a closer look at the mirror cell 150.

Referring to FIG. 4, the mirror cell 150 has a liquid crystal layer (CLL) between the lower substrate 151 provided with the lower electrode 152 and the upper substrate 154 provided with the upper electrode 155 (157). It is sealed and constructed.

The lower substrate 151 and the upper substrate 154 are transparent substrates that allow light to pass through, and may be, for example, glass substrates or plastic substrates. Examples of plastic substrates include cellulose resins such as triacetyl cellulose (TAC) or diacetyl cellulose (DAC), cyclic olefin polymers (COP) such as norbornene derivatives, cyclic olefin copolymer (COC), and acrylic resins such as polymethylmethacrylate (PMMA), Polyolefins such as polycarbonate (PC), polyethylene (PE), or polypropylene (PP), polyvinyl alcohol (PVA), poly ether sulfone (PES), polyetheretherketone (PEEK), polyetherimide (PEI), polyethylenenaphthalate (PEN), and polyethyleneterephthalate (PET) Examples include polyester, PI (polyimide), PSF (polysulfone), or fluororesin.

The lower electrode 152 and the upper electrode 155 may also be made of a transparent conductive material that allows light to pass through, for example, ITO, IZO, ITZO, IGO, etc. A lower alignment layer 153 is disposed on the surface of the lower electrode 152, and an upper alignment layer 156 is disposed on the surface of the upper electrode 155. The lower alignment layer 153 and the upper alignment layer 156 are disposed to face each other, and a liquid crystal layer (CLL) is disposed between the alignment layers 153 and 156. The lower alignment layer 153 and the upper alignment layer 156 are made of polyimide and align the cholesteric liquid crystal (CLC) included in the liquid crystal layer (CLL).

Referring to FIG. 5, the liquid crystal layer (CLL) includes cholesteric liquid crystal (CLC), chiral dopant (CD), and matrix (MX). Additionally, the liquid crystal layer (CLL) may additionally contain additives such as photoinitiators.

Cholesteric liquid crystal (CLC) has the characteristic of selectively reflecting light depending on the twist direction of the helix and the pitch of the repeating structure. Therefore, by adjusting the pitch of the cholesteric liquid crystal, the color of the reflected light can be adjusted in various ways. In order to vary the pitch of the cholesteric liquid crystal, as is generally known, the pitch of the liquid crystal is controlled by adjusting the amount of UV light irradiated to the cholesteric liquid crystal, or the concentration of chiral dopant (CD) is adjusted to control the pitch of the liquid crystal. You can control the pitch.

The liquid crystal layer (CLL) may include a matrix (MX) in which cholesteric liquid crystal (CLC) and chiral dopant (CD) are dispersed. The matrix (MX) fixes the cholesteric liquid crystal (CLC) within the liquid crystal layer (CLL). The matrix (MX) is a transparent material and is not particularly limited as long as it is a material that can transmit UV light. The matrix (MX) may be, for example, one or more of polyvinyl alcohol, gelatin, formalin resorcinol resin, polyurethane, (meth)acrylic acid, melamine, formaldehyde, and fluorine-based polyvinylpyrrolidone. The liquid crystal layer (CLL) may contain 30 to 70% by weight of cholesteric liquid crystal (CLC) and 30 to 70% by weight of the matrix (MX).

Meanwhile, in order to increase the reflectivity of the mirror cell 150, it is necessary to reflect left-circularly polarized light and right-circularly polarized light in addition to the wavelength range of visible light. Left- and right-circularly polarized light can be reflected by changing the twist direction of the cholesteric liquid crystal. Therefore, a liquid crystal layer is formed that can reflect the wavelength range of left- and right-circularly polarized visible light.

As shown in Figure 6, a red liquid crystal layer (LCR) capable of reflecting left-circularly polarized light in the red wavelength band, a green liquid crystal layer (LCG) capable of reflecting left-circularly polarized light in the green wavelength band, and a left-circularly polarized light in the blue wavelength band. A first liquid crystal layer (LC) capable of reflecting left circularly polarized light of visible light is formed by stacking a blue liquid crystal layer (LCB). And a red liquid crystal layer (RCR) that can reflect right-circularly polarized light in the red wavelength band, a green liquid crystal layer (RCG) that can reflect right-circularly polarized light in the green wavelength band, and a blue liquid crystal layer (RCB) that can reflect right-circularly polarized light in the blue wavelength band. ) are stacked to form a second liquid crystal layer (RC) that can reflect right-circularly polarized light of visible light. Accordingly, the reflectance of the mirror cell 150 can be improved by forming a liquid crystal layer (CLL) by stacking the first liquid crystal layer (LC) and the second liquid crystal layer (RC). However, Figure 6 is only an example, and the positions of the first liquid crystal layer (LC) and the second liquid crystal layer (RC) may be changed.

The display device equipped with the mirror cell 150 maintains a reflection mode when no electric field is applied, i.e., in normal times, and when an electric field is applied, all cholesteric liquid crystals stand up and operate in a transmission mode. Therefore, a mirror cell can be implemented by switching between reflection mode and transmission mode.

In order to implement the mirror cell 150 of FIG. 6 described above with neutral reflective visibility, at least six liquid crystal layers must be stacked. However, when a mirror cell is constructed with the above structure, the structure and process are complicated due to the stacked structure, driving voltage and production costs increase, and the cell gap also increases, making it difficult to implement a thin structure.

The present invention provides a display device that can simplify the structure of a mirror cell.

Figure 7 is a cross-sectional view showing a mirror cell according to an embodiment of the present invention, Figure 8 is a cross-sectional view showing the liquid crystal layer of the present invention, Figure 9 is a diagram showing the pitch formation mechanism of the cholesteric liquid crystal, and Figure 10 is a diagram showing the pitch formation mechanism of the present invention. This is a cross-sectional view showing a mirror cell according to one embodiment. In the following, description of the same configuration as the mirror cell described above will be omitted.

Referring to FIG. 7, the mirror cell 200 of the present invention has a lower electrode 220 disposed on a lower substrate 210 and a lower alignment film 230 is disposed on the lower electrode 220. An upper electrode 250 is disposed on the lower surface of the upper substrate 240, and an upper alignment film 260 is disposed on the lower surface of the upper electrode 250. A liquid crystal layer (CLL) is disposed between the lower alignment layer 230 and the upper alignment layer 260 and sealed with the sealant 270.

The liquid crystal layer (CLL) of the present invention includes cholesteric liquid crystal (CLC). Referring to FIG. 8 in more detail, the liquid crystal layer (CLL) of the present invention includes cholesteric liquid crystal (CLC), chiral dopant (CD), and reactive liquid crystal (RM).

Reactive liquid crystal (RM) maintains the orientation of cholesteric liquid crystal (CLC) and expands the reflection band by varying the pitch of cholesteric liquid crystal (CLC). Reactive liquid crystal (RM) includes polymer liquid crystals that are not aligned by an electric field but can be cured by UV light, and the orientation of the liquid crystals can be maintained while physical properties after curing change compared to before curing.

As shown in Figure 8, the reactive liquid crystal (RM) is mixed in the cholesteric liquid crystal (CLC) before irradiation of UV light. (a), When irradiated with UV light, the reactive liquid crystal (RM) is cured to form a polymer network ( PN) is formed to maintain the orientation of the liquid crystal. (b) The liquid crystal layer (CLL) containing the reactive liquid crystal (RM) has local differences in the degree of curing of the reactive liquid crystal (RM), resulting in cholesteric liquid crystal (RM) The degree of twist of CLC becomes a gradient. Therefore, the reflection band of cholesteric liquid crystal (CLC) can be expanded.

Reactive liquid crystal (RM) can use methacrylate-based and acrylate-based materials. Methacrylates include, for example, Methyl methacrylate (MMA), Ethyl methacrylate (EMA), n-Butyl methacrylate (BMA), 2-Aminoethyl methacrylate hydrochloride, Allyl methacrylate, Benzyl methacrylate, 2-Butoxyethyl methacrylate, 2-(fe /f-Butylamino)ethyl methacrylate, Butyl methacrylate, te/f-Butyl methacrylate, Caprolactone 2-(methacryloyloxy)ethyl ester, 3-Chloro-2-hydroxypropyl methacrylate, Cyclohexyl methacrylate, 2-(Diethylamino)ethyl methacrylate, Di(ethylene) glycol) methyl ether methacrylate, 2-(Dimethylamino)ethyl methacrylate, 2- Ethoxyethyl methacrylate, Ethylene glycol dicyclopentenyl ether methacrylate, Ethylene glycol methyl ether methacrylate, Ethylene glycol phenyl ether methacrylate, 2-Ethylhexyl methacrylate, Furfuryl methacrylate, Glycidyl methac rylate, glycosyloxy ethyl methacrylate, Hexyl methacrylate, Hydroxybutyl methacrylate, 2-Hydroxyethyl methacrylate, 2-Hydroxyethyl methacrylate, Hydroxypropyl methacrylate Mixture of hydroxypropyl and hydroxyisopropyl methacrylates, 2-Hydroxypropyl 2-(methacryloyloxy)ethyl phthalate, Isobornyl methacrylate, Isobutyl methacrylate, 2-lsocyanatoethyl methacrylate, Isodecyl methacrylate, Lauryl methacrylate, Methacryloyl chloride, Methacrylic acid, 2-(Methylthio)ethyl methacrylate, mono-2- (Methacryloyloxy)ethyl maleate, mono-2-(Methacryloyloxy)ethyl succinate, Pentabromophenyl methacrylate, Phenyl methacrylate, Phosphoric acid 2- hydroxyethyl methacrylate ester, Stearyl methacrylate, 3-Sulfopropyl methacrylate potassium salt, Tetrahydrofurfuryl methacrylate, 3- (Trichlorosilyl)propyl methacrylate, Tridecyl methacrylate, 3- (Trimethoxysilyl)propyl methacrylate, 3,3,5-Trimethylcyclohexyl methacrylate, Trimethylsilyl methacrylate or Vinyl meth acrylate I can hear it.

Acrylates include, for example, Acrylic acid, 4-Acryloylmorpholine, [2-(Acryloyloxy)ethyl]thmethylammonium chloride, 2-(4-Benzoyl-3-hydroxyphenoxy)ethyl acrylate, Benzyl 2-propylacrylate, 2-Butoxyethyl acrylate, Butyl acrylate, fe/f-Butyl acrylate, 2- [(Butylamino)carbonyl]oxy]ethyl acrylate, ferf-Butyl 2-bromoacrylate, 4-tert- Butylcyclohexyl acrylate, 2-Carboxyethyl acrylate, 2-Carboxyethyl acrylate oligomers anhydrous, 2 -(Diethylamino)ethyl acrylate, Di(ethylene glycol) ethyl ether acrylate technical grade, Di(ethylene glycol) 2-ethylhexyl ether acrylate, 2-(Dimethylamino)ethyl acrylate, 3-(Dimethylamino)propyl acrylate, Dipentaerythritol penta-/hexa -acrylate, 2-Ethoxyethyl acrylate, Ethyl acrylate, 2-Ethylacryloyl chloride, Ethyl 2-(bromomethyl)acrylate, Ethyl cis- (-cyano)acrylate, Ethylene glycol dicyclopentenyl ether acrylate, Ethylene glycol methyl ether acrylate, Ethylene glycol phenyl ether acrylate , Ethyl 2- ethylacrylate, 2-Ethylhexyl acrylate, Ethyl 2-propylacrylate, Ethyl 2- (trimethylsilylmethyl)acrylate, Hexyl acrylate, 4-Hydroxybutyl acrylate, 2- Hydroxyethyl acrylate, 2-Hydroxy-3-phenoxypropyl acrylate, Hydroxypropyl acrylate, Isobornyl acrylate, Isobutyl acrylate, Isodecyl acrylate, Isooctyl acrylate, Lauryl acrylate, Methyl 2-acetamidoacrylate, Methyl acrylate, Methyl a-bromoacrylate, Methyl 2-(bromomethyl)acrylate, Methyl 3-hydroxy- 2-methylenebutyrate, Octadecyl acrylate, Pentabromobenzyl acrylate , Pentabromophenyl acrylate, Poly(ethylene glycol) methyl ether acrylate, Poly(propylene glycol) acrylate, Poly(propylene glycol) methyl ether acrylate Soybean oil, epoxidised acrylate, 3-Sulfopropyl acrylate potassium salt, Tetrahydrofurfuryl acrylate, 3-(Trimethoxysilyl)propyl acrylate Or 3,5,5-Trimethylhexyl acrylate. However, the present invention is not limited to this and all known reactive liquid crystal materials can be used.

With reference to FIG. 9, the mechanisms of the liquid crystal layer (a) not containing reactive liquid crystal and the liquid crystal layer (b) containing reactive liquid crystal are as follows. The liquid crystal layer (a), which does not contain reactive liquid crystals, exists as a mixture of cholesteric liquid crystals and chiral dopants. When UV light is irradiated, a twist in the cholesteric liquid crystal is formed, and the pitch (P1) of all cholesteric liquid crystals is formed to be the same.

On the other hand, in the liquid crystal layer (b) containing reactive liquid crystals, cholesteric liquid crystals, reactive liquid crystals, and chiral dopants are uniformly mixed. When UV light is irradiated, the reactive liquid crystals begin to harden in the area where the UV light is incident, and the reactive liquid crystals are concentrated in the hardened area. Therefore, the concentration of the reactive liquid crystal becomes lighter as it moves from the area where UV light is incident to the area where UV light is emitted. And the chiral dopant is pushed out by the reactive liquid crystal, so the concentration of the chiral dopant becomes thicker from the area where UV light is incident to the area where UV light is emitted. The twist of the cholesteric liquid crystal varies depending on the concentration of the chiral dopant. If the concentration of the chiral dopant is thick, the twist of the cholesteric liquid crystal increases and the pitch narrows, and if the concentration of the chiral dopant is light, the pitch of the cholesteric liquid crystal becomes narrow. There is less twist and the pitch becomes wider. Therefore, the area where UV light is incident has a low chiral dopant concentration, so the pitch (P2) of the cholesteric liquid crystal is wide, and the area where UV light is emitted has a high chiral dopant concentration, so the cholesteric liquid crystal has a wide pitch (P2). The pitch (P3) is narrow.

Comparing the pitch of the cholesteric liquid crystal in the liquid crystal layer (a) that does not contain reactive liquid crystal with the pitch of the cholesteric liquid crystal in the liquid crystal layer (b) that contains the reactive liquid crystal is as follows. The pitch (P2) of the cholesteric liquid crystal in the area where UV light is incident in the liquid crystal layer (b) containing the reactive liquid crystal is greater than the pitch (P1) of the cholesteric liquid crystal in the liquid crystal layer (a) that does not contain the reactive liquid crystal. wide. In addition, the pitch (P3) of the cholesteric liquid crystal in the area where UV light is emitted in the liquid crystal layer (b) containing the reactive liquid crystal is the pitch (P1) of the cholesteric liquid crystal in the liquid crystal layer (a) that does not contain the reactive liquid crystal. ) is narrower than Therefore, the reflection wavelength band according to the pitch of the cholesteric liquid crystal of the liquid crystal layer (b) containing the reactive liquid crystal becomes wider. That is, the liquid crystal layer (CLL) of the present invention further includes reactive liquid crystal (RM), so that the light reflection wavelength band can be expanded by varying the pitch of the cholesteric liquid crystal. Therefore, the mirror cell of the present invention can reflect all visible light wavelengths in one liquid crystal layer by varying the pitch of the cholesteric liquid crystal.

Meanwhile, in order to increase the reflectivity of the mirror cell 200, the present invention needs to reflect left-circularly polarized light and right-circularly polarized light.

Referring to FIG. 10, the mirror cell 200 of the present invention has a lower electrode 220 and a lower alignment film 230 disposed on the lower substrate 210 described above. A central substrate 280 facing the lower substrate 210 is disposed, a first central electrode 290 is disposed on the lower surface of the central substrate 280, and a first central alignment layer 300 is disposed on the lower surface of the first central electrode 290. ) is placed. A first liquid crystal layer (CLL1) capable of reflecting left circularly polarized light is disposed between the lower substrate 210 and the central substrate 280 and is sealed with the material 270.

A second central electrode 310 is disposed on the upper surface of the central substrate 280, and a second central alignment layer 320 is disposed on the second central electrode 310. An upper substrate 240 is disposed opposite to the central substrate 280. An upper electrode 250 is disposed on the lower surface of the upper substrate 240, and an upper alignment film 260 is disposed on the lower surface of the upper electrode 250. A second liquid crystal layer (CLL2) capable of reflecting right-circularly polarized light is sealed between the central substrate 280 and the upper substrate 240 with the material 270. Although not shown, a column spacer exists between each substrate to maintain a cell gap between the second liquid crystal layer (CLL2) and the first liquid crystal layer (CLL1).

The mirror cell 200 constitutes a mirror cell 200 including a second liquid crystal layer (CLL2) and a first liquid crystal layer (CLL1), thereby reflecting all right-circularly polarized light in the second liquid crystal layer (CLL2) and the first liquid crystal layer (CLL1). All left circularly polarized light is reflected in CLL1). Therefore, there is the advantage of implementing a mirror cell with neutral reflective visibility, simplifying the stacked structure to reduce driving voltage and production costs, and reducing the cell gap to achieve thinness.

Figures 11 to 13 are cross-sectional views showing a mirror cell according to one embodiment of the present invention, Figures 14 to 16 are cross-sectional views showing a mirror cell according to another embodiment of the present invention, and Figure 17 is a manufacturing process of the mirror cell of the present invention. This is a drawing showing . In the following, description of the same components as the mirror cell described above will be omitted.

Referring to FIG. 11, the mirror cell 400 of the present invention has a lower electrode 420 disposed on a lower substrate 410 and a column spacer (CS) is disposed on the lower electrode 420. A lower alignment layer 430 is disposed on the lower electrode 420 including the column spacer (CS). A central substrate 440 facing the lower substrate 410 is disposed, a first central electrode 450 is disposed on the lower surface of the central substrate 440, and a first central alignment layer 460 is disposed on the lower surface of the first central electrode 450. ) is placed. A first liquid crystal layer (CLL1) capable of reflecting the left side is disposed between the lower substrate 410 and the central substrate 440 and sealed with the seal 470.

A second central electrode 500 is disposed on the upper surface of the central substrate 440, and a UV absorption layer (UVL) is disposed on the second central electrode 500. A column spacer (CS) is disposed on the UV absorption layer (UVL), and a second central alignment layer 510 is disposed on the UV absorption layer (UVL) including the column spacer (CS). An upper substrate 520 is disposed opposite to the central substrate 440. An upper electrode 530 is disposed on the lower surface of the upper substrate 520, and an upper alignment film 540 is disposed on the lower surface of the upper electrode 530. A second liquid crystal layer (CLL2) capable of reflecting right-circularly polarized light is sealed between the central substrate 440 and the upper substrate 520 with the sealant 550.

The mirror cell 400 of the present invention implements a mirror cell with a neutral reflective color by configuring the mirror cell 400 having a second liquid crystal layer (CLL2) and a first liquid crystal layer (CLL1), and simplifies the stacked structure. It is possible to achieve a thinner design by reducing driving voltage and production costs and reducing the cell gap.

The present invention described above includes a UV absorption layer (UVL) between the second central electrode 500 and the second central alignment layer 510. The UV absorption layer (UVL) absorbs light in a specific wavelength range, for example, UV light, and preferably absorbs UV light in the 365 nm wavelength range.

UV absorption layer (UVL) is benzophenone-based (absorption range 300-380 nm), benzotriazole-based (absorption range 300-385 nm), salicylic acid-based (absorption range 260-340 nm), acrylonitrile-based (absorption range 290-400 nm), and It may be made of an organic nickel compound or a monobenzoic acid type. However, the UV absorption layer (UVL) of the present invention is not limited to this and any material that absorbs UV light in the wavelength range of at least 365 nm can be used.

The UV absorption layer (UVL) may have a thickness of 0.1 to 100 μm. Here, if the thickness of the UV absorption layer (UVL) is 0.1 μm or more, UV light irradiated from the top can be blocked from being irradiated to the lower first liquid crystal layer (CLL1), thereby preventing the haze of the mirror cell from increasing. Additionally, if the thickness of the UV absorption layer (UVL) is 100㎛ or less, it is possible to prevent haze from increasing due to the UV absorption layer (UVL).

The UV absorption layer (UVL) of the present invention can be positioned anywhere as long as it absorbs UV light irradiated from the top to the first liquid crystal layer (CLL1).

Referring to Figure 12, the UV absorption layer (UVL) of the present invention is located between the second central electrode 500 and the second central alignment layer 510 of the central substrate 440, and the first central electrode of the central substrate 440. It may be located between the electrode 450 and the first central alignment layer 460. That is, the UV absorption layer (UVL) of the present invention may be provided as two layers adjacent to the central substrate 440.

In addition, referring to FIG. 13, the UV absorption layer (UVL) of the present invention is not located between the second central electrode 500 and the second central alignment layer 510 of the central substrate 440, but is located between the second central electrode 500 and the second central alignment layer 510 of the central substrate 440. It may be located only between the first central electrode 450 and the first central alignment layer 460.

However, the present invention is not limited to this and can be located anywhere as long as it absorbs UV light irradiated from the top to the first liquid crystal layer (CLL1). However, there is cholesterol between the second central alignment layer 510 and the second liquid crystal layer (CLL2) of the central substrate 440 and between the first central alignment layer 460 and the first liquid crystal layer (CLL1) of the central substrate 400. Because the liquid crystals must be oriented, a UV absorption layer (UVL) cannot be placed.

Meanwhile, the mirror cell according to another embodiment of the present invention includes a UV absorber in the first central alignment layer and the second central alignment layer instead of having a UV absorption layer, thereby preventing UV light from being irradiated to the liquid crystal layer located below. .

Referring to FIG. 14, the mirror cell 400 according to another embodiment of the present invention includes a UV absorber (UVA) in the second central alignment layer 510. The UV absorber (UVA) absorbs light in the UV wavelength range in the same way as the above-described UV absorbing layer, and preferably absorbs light in the wavelength range of 365 nm. The UV absorber (UVA) may be made of the same material as the UV absorbing layer described above.

UV absorber (UVA) is included in an amount of 0.1 to 30 wt% based on the total 100 wt% of the second central alignment layer 510. If the content of UV absorber (UVA) is 0.1 wt% or more for the total 100 wt% of the second central alignment layer 510, UV light irradiated from the top can be blocked from being irradiated to the lower first liquid crystal layer (CLL1), Haze can be prevented from increasing. In addition, if the content of the UV absorbing layer (UVA) is 30 wt% or less based on the total 100 wt% of the second central alignment layer 510, haze can be prevented from increasing due to the UV absorbing material (UVA).

The UV absorber (UVA) of the present invention can be positioned anywhere as long as it absorbs UV light irradiated from the top to the first liquid crystal layer (CLL1).

Referring to FIG. 15, the UV absorber (UVA) of the present invention may be included in the second central alignment layer 510 and the first central alignment layer 460. That is, the UV absorber (UVA) of the present invention may be included in alignment films adjacent to the central substrate 400.

Additionally, referring to FIG. 16 , the UV absorber (UVA) of the present invention may be included only in the first central alignment layer 460 rather than in the second central alignment layer 510 . However, the present invention is not limited to this, and the UV absorber (UVA) can be positioned anywhere to absorb UV light irradiated from the top to the first liquid crystal layer (CLL1). However, UV absorber (UVA) cannot be placed on the first central electrode 450 and the second central electrode 500 of the central substrate 400 so as not to deteriorate the properties of the electrodes.

Referring to Figure 17, mirror cells according to the above-described embodiments of the present invention are manufactured through two UV irradiation processes. The first cell (CE1) and the second cell (CE2) are stacked by bonding substrates equipped with electrodes and alignment films. Then, the first liquid crystal injection process is performed in the first cell (CE1). In the first liquid crystal injection process, a liquid crystal layer capable of reflecting left-circularly polarized light (or right-circularly polarized light) is formed in the first cell CE1. Next, a first UV irradiation process is performed on the first cell (CE1). The first UV irradiation process irradiates UV light with a wavelength of approximately 365 nm from the top of the cells. At this time, the UV light passes through the second cell (CE2) and hardens the reactive liquid crystal of the liquid crystal layer of the first cell (CE1).

Next, a second liquid crystal injection process is performed to inject liquid crystal into the second cell (CE2). In the secondary liquid crystal injection process, a liquid crystal layer that can reflect right-circularly polarized light (or left-circularly polarized light) is formed. Then, a secondary UV irradiation process is performed on the second cell (CE2). The secondary UV irradiation process irradiates UV light with a wavelength of approximately 365 nm from the top of the second cell (CE2). At this time, UV light hardens the reactive liquid crystal of the liquid crystal layer of the second cell (CE2). Additionally, UV light may pass through the second cell (CE2) and proceed to the first cell (CE1).

However, the mirror cell illustrated in FIGS. 11 to 16 of the present invention includes a UV absorbing layer or a UV absorbing material, thereby preventing UV light from the secondary UV irradiation process from being irradiated to the first cell (CE1). That is, during the secondary UV irradiation process, UV light is scattered from the polymer material (reactive liquid crystal, matrix, etc.) and the column spacer, and the scattered UV light can be prevented from being irradiated to the first cell below. Therefore, it is possible to prevent the haze of the liquid crystal layer located at the bottom of the mirror cell from increasing due to scattered UV light.

Hereinafter, an experimental example of a mirror cell according to an embodiment of the present invention will be disclosed. The following experimental example is only an example of the present invention and the present invention is not limited thereto.

Comparative example One

A mirror cell having the structure of FIG. 10 was manufactured by forming a first liquid crystal layer reflecting left-circularly polarized light between the lower substrate and the central substrate, and forming a second liquid crystal layer reflecting right-circularly polarized light between the central substrate and the upper substrate. At this time, the mirror cell was not equipped with a UV absorbing layer or UV absorbing material.

Comparative example 2

A mirror cell was manufactured in the same manner as in Comparative Example 1, except that the UV absorber was mixed in the first liquid crystal layer and the second liquid crystal layer in an amount of 0.5 wt% based on the total 100 wt% of the cholesteric liquid crystal mixture.

Example

A mirror cell was manufactured in the same manner as in Comparative Example 1, except that a UV absorbing layer was formed between the first central electrode and the first central alignment layer.

After the first liquid crystal injection of the first liquid crystal layer into the mirror cell manufactured according to the above-mentioned Comparative Examples 1 and 2 and the Example, after the first UV irradiation of UV irradiation to the first liquid crystal layer, the second liquid crystal layer After the second liquid crystal injection, the reflectance for each wavelength band after the second UV irradiation was measured and shown in Figures 18 to 20. Figure 18 is a graph showing the reflectance of mirror cells manufactured according to Comparative Example 1 by wavelength, Figure 19 is a graph showing reflectance by wavelength of mirror cells manufactured according to Comparative Example 2, and Figure 20 is a graph showing reflectance of mirror cells manufactured according to Examples. This is a graph showing the reflectance by wavelength.

Referring to FIG. 18, the reflectance of the mirror cell manufactured according to Comparative Example 1 after the first liquid crystal injection was about 50%, and the light reflection wavelength band was expanded after the first UV irradiation. The reflectance after the second liquid crystal injection was about 90%, and the light reflection wavelength band was expanded after the second UV irradiation. Therefore, the final reflectance of the mirror cell manufactured according to Comparative Example 1 was about 90% and the light reflection wavelength band was about 270 nm.

Referring to FIG. 19, the reflectance of the mirror cell manufactured according to Comparative Example 2 after the first liquid crystal injection was about 50%, and the light reflection wavelength band was expanded after the first UV irradiation. The reflectance after the second liquid crystal injection was about 90%, and the light reflection wavelength band was expanded after the second UV irradiation. Therefore, the final reflectance of the mirror cell manufactured according to Comparative Example 2 was about 90% and the light reflection wavelength band was about 330 nm.

Referring to FIG. 20, the reflectance of the mirror cell manufactured according to an embodiment of the present invention after the first liquid crystal injection was about 50%, and the light reflection wavelength band was expanded after the first UV irradiation. The reflectance after the second liquid crystal injection was about 86%, and the light reflection wavelength band was expanded after the second UV irradiation. Therefore, the final reflectance of the mirror cell manufactured according to the example was about 86% and the light reflection wavelength band was about 330 nm.

Through these results, the reflectance and light reflection wavelength range of the mirror cells with or without UV absorbers or absorption layers were found to be at the same level.

In addition, the haze of mirror cells manufactured according to the above-described Comparative Examples 1 and 2 and Examples were measured for each process and are shown in Table 1 below.

Haze (%) After 1st UV irradiation After 2nd liquid crystal injection After 2nd UV irradiation Comparative Example 1 - - 39 Comparative Example 2 5.13 14.48 40.37 Example 4.87 13.04 23.02

Referring to Table 1, the haze of the mirror cell of Comparative Example 1, which was not provided with a UV absorbing layer or absorbing material, was found to be about 39% after secondary UV irradiation. The haze of the mirror cell of Comparative Example 2, in which a UV absorber was mixed in the first liquid crystal layer and the second liquid crystal layer, was about 40% after secondary UV irradiation. The haze of the mirror cell of the example provided with a UV absorption layer was found to be about 23% after secondary UV irradiation.

From these results, the haze of the mirror cell in which the UV absorber was mixed into the liquid crystal layer was no different from the haze of the mirror cell without the UV absorber. On the other hand, it can be seen that the haze of the mirror cell equipped with a UV absorption layer is significantly reduced to half.

Meanwhile, the effect of expanding the light reflection wavelength band when mixing UV absorbers in the liquid crystal layer of the mirror cell was examined.

Comparative example 3

A liquid crystal layer that reflects left- or right-circularly polarized light was formed between two substrates. At this time, the liquid crystal layer was prepared by mixing UV absorbers at different amounts of 0.5, 1.25, and 2.5 wt% based on the total 100 wt% of the cholesteric liquid crystal mixture to prepare a mirror cell.

The reflectance by wavelength of the mirror cell prepared according to Comparative Example 3 before UV irradiation, after 10 minutes of UV irradiation, and after 20 minutes of UV irradiation was measured and shown in Figures 21 to 23, and the light reflection wavelength range by content of UV absorber is as follows. It is shown in Table 2.

Content of UV absorber (wt%) Light reflection wavelength band (nm) note 0.5 360 - 1.25 350 - 2.5 330 Cholesteric liquid crystal defects

Referring to FIGS. 21 to 23 and Table 2, when 0.5 wt% of UV absorber was mixed into the liquid crystal layer, the light reflection wavelength band was expanded to about 360 nm after UV irradiation. When 1.25 wt% of UV absorber was mixed into the liquid crystal layer, the light reflection wavelength band was expanded to about 330 nm after UV irradiation. When 2.5 wt% of UV absorber was mixed into the liquid crystal layer, the light reflection wavelength band was expanded to about 330 nm after UV irradiation, but defects were found in the cholesteric liquid crystal.

Through these results, it was confirmed that as the content of UV absorber in the liquid crystal layer of the mirror cell increases, the effect of expanding the light reflection wavelength band gradually decreases, and defects occur on the cholesteric liquid crystal, reducing reliability.

As described above, the mirror cell according to an embodiment of the present invention has first and second liquid crystal layers containing reactive liquid crystals, thereby implementing a mirror cell with a neutral reflective color and simplifying the stacked structure to increase the driving voltage and production It is possible to achieve a thinner design by reducing costs and reducing the cell gap.

Additionally, the mirror cell according to an embodiment of the present invention is provided with a UV absorbing layer or a UV absorbing material, thereby preventing scattered UV light from being irradiated to the first liquid crystal layer located below due to the two UV irradiation processes. Therefore, it is possible to prevent the haze of the mirror cell from increasing due to scattered UV light.

Through the above-described content, those skilled in the art will be able to see that various changes and modifications can be made without departing from the technical idea of the present invention. Therefore, the technical scope of the present invention should not be limited to what is described in the detailed description of the specification, but should be defined by the scope of the patent claims.

400: mirror cell 410: lower substrate
420: lower electrode 430: lower alignment film
440: Central substrate 450: First central electrode
460: first central alignment layer 470: actual
500: second central electrode 510: second central alignment layer
520: upper substrate 530: upper electrode
540: Top alignment layer CLC: Cholesteric liquid crystal
RM: Responsive liquid crystal CD: Chiral dopant
CLL1: first liquid crystal layer CLL2: second liquid crystal layer
CS: Column spacer UVL: UV absorption layer

Claims (16)

A mirror cell is disposed in front of a display panel on which an image is displayed and implements a transmission mode that transmits light so that the image of the display panel is visible and a reflection mode that functions as a mirror by reflecting light incident on the front of the display panel. Because,
A lower substrate including a lower alignment layer and a lower electrode;
an upper substrate including an upper alignment layer and an upper electrode facing the lower substrate;
It is disposed between the lower substrate and the upper substrate, and includes a first central alignment layer and a first central electrode on a side opposite to the lower substrate, and a second central alignment layer and a second central electrode on a side opposite to the upper substrate. A central substrate containing;
a first liquid crystal layer disposed between the lower substrate and the central substrate and a second liquid crystal layer disposed between the central substrate and the upper substrate; and
Comprising a UV absorbing layer disposed on at least one side of the central substrate,
Each of the lower electrode, the upper electrode, the first central electrode, and the second central electrode consists of one electrode continuously disposed on the lower substrate, the upper substrate, and the central substrate,
The liquid crystals forming the first liquid crystal layer and the second liquid crystal layer are mirror cells in which the pitch in the area where UV light is incident is wider than the pitch in the area where the UV light is emitted. According to claim 1,
A mirror cell in which the first liquid crystal layer reflects light of either left-circularly polarized light or right-handed circularly polarized light, and the second liquid crystal layer reflects the remaining light of left-circularly polarized light or right-handed circularly polarized light. According to claim 1,
The first liquid crystal layer and the second liquid crystal layer include at least a cholesteric liquid crystal, a chiral dopant, and a reactive liquid crystal. According to claim 1,
The UV absorption layer is a mirror cell disposed between the first central electrode and the first central alignment layer. According to claim 1,
The UV absorption layer is a mirror cell disposed between the second central electrode and the second central alignment layer. According to claim 1,
The UV absorption layer is a mirror cell made of at least one of benzophenone-based, benzotriazole-based, salicylic acid-based, acrylonitrile-based, organic nickel compounds, monobenzoic acid-based, and mixtures thereof. According to claim 1,
The UV absorbing layer is a mirror cell with a thickness of 0.1 to 100㎛. A mirror cell is disposed in front of a display panel on which an image is displayed and implements a transmission mode that transmits light so that the image of the display panel is visible and a reflection mode that functions as a mirror by reflecting light incident on the front of the display panel. Because,
A lower substrate including a lower alignment layer and a lower electrode;
an upper substrate including an upper alignment layer and an upper electrode facing the lower substrate;
It is disposed between the lower substrate and the upper substrate, and includes a first central alignment layer and a first central electrode on a side opposite to the lower substrate, and a second central alignment layer and a second central electrode on a side opposite to the upper substrate. A central substrate containing;
a first liquid crystal layer disposed between the lower substrate and the central substrate and a second liquid crystal layer disposed between the central substrate and the upper substrate;
Column spacers disposed between the lower electrode and the lower alignment layer and between the second central electrode and the second central alignment layer; and
Comprising a UV absorber included in at least one of the first central alignment layer or the second central alignment layer,
Each of the lower electrode, the upper electrode, the first central electrode, and the second central electrode consists of one electrode continuously disposed on the lower substrate, the upper substrate, and the central substrate,
The liquid crystals forming the first liquid crystal layer and the second liquid crystal layer are mirror cells in which the pitch in the area where UV light is incident is wider than the pitch in the area where the UV light is emitted. According to clause 8,
A mirror cell in which the first liquid crystal layer reflects light of either left-circularly polarized light or right-handed circularly polarized light, and the second liquid crystal layer reflects the remaining light of left-circularly polarized light or right-handed circularly polarized light. According to clause 8,
The first liquid crystal layer and the second liquid crystal layer include at least a cholesteric liquid crystal, a chiral dopant, and a reactive liquid crystal. According to clause 8,
The UV absorber is a mirror cell included in the first central alignment layer. According to clause 8,
The UV absorber is a mirror cell included in the second central alignment layer. According to clause 8,
The UV absorber is a mirror cell made of at least one of benzophenone-based, benzotriazole-based, salicylic acid-based, acrylonitrile-based, organic nickel compounds, monobenzoic acid-based, and mixtures thereof. According to clause 8,
The mirror cell wherein the UV absorber is included in an amount of 0.1 to 30 wt% based on 100 wt% of the first central alignment layer or the second central alignment layer. A display panel that displays an image on the front; and
It is located on the front of the display panel and includes a mirror cell that implements a reflection mode that functions as a mirror by reflecting light incident on the front of the display panel and a transmission mode that transmits light so that the image of the display panel is visible,
The mirror cell,
A lower substrate including a lower alignment layer and a lower electrode;
an upper substrate including an upper alignment layer and an upper electrode facing the lower substrate;
It is disposed between the lower substrate and the upper substrate, and includes a first central alignment layer and a first central electrode on a side opposite to the lower substrate, and a second central alignment layer and a second central electrode on a side opposite to the upper substrate. A central substrate containing;
a first liquid crystal layer disposed between the lower substrate and the central substrate and a second liquid crystal layer disposed between the central substrate and the upper substrate; and
Comprising a UV absorbing layer disposed on at least one side of the central substrate,
Each of the lower electrode, the upper electrode, the first central electrode, and the second central electrode consists of one electrode continuously disposed on the lower substrate, the upper substrate, and the central substrate,
The liquid crystals forming the first liquid crystal layer and the second liquid crystal layer have a pitch wider in the area where UV light is incident than the pitch in the area where the UV light is emitted. A display panel that displays an image on the front; and
It is located on the front of the display panel and includes a mirror cell that implements a reflection mode that functions as a mirror by reflecting light incident on the front of the display panel and a transmission mode that transmits light so that the image of the display panel is visible,
The mirror cell,
A lower substrate including a lower alignment layer and a lower electrode;
an upper substrate including an upper alignment layer and an upper electrode facing the lower substrate;
It is disposed between the lower substrate and the upper substrate, and includes a first central alignment layer and a first central electrode on a side opposite to the lower substrate, and a second central alignment layer and a second central electrode on a side opposite to the upper substrate. A central substrate containing;
a first liquid crystal layer disposed between the lower substrate and the central substrate and a second liquid crystal layer disposed between the central substrate and the upper substrate;
Column spacers disposed between the lower electrode and the lower alignment layer and between the second central electrode and the second central alignment layer; and
Comprising a UV absorber included in at least one of the first central alignment layer or the second central alignment layer,
Each of the lower electrode, the upper electrode, the first central electrode, and the second central electrode consists of one electrode continuously disposed on the lower substrate, the upper substrate, and the central substrate,
The liquid crystals forming the first liquid crystal layer and the second liquid crystal layer have a pitch wider in the area where UV light is incident than the pitch in the area where the UV light is emitted.

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