Polarizer and liquid crystal display including the same

A polarizer and a liquid crystal display including the polarizer, the polarizer including a plurality of metal lines extending in one direction and being arranged at regular intervals; and a plurality of low reflection layers on the plurality of metal lines, the plurality of low reflection layers contacting respective upper parts of the plurality of metal lines and having an interval and a width about equal to an interval and a width of the plurality of metal lines, wherein the interval of the plurality of metal lines is smaller than a wavelength of a visible ray, and light incident from an upper side of the plurality of low reflection layers is reflected with reflectivity equal to or smaller than 10%.

CROSS-REFERENCE TO RELATED APPLICATION

Korean Patent Application No. 10-2013-0060448, filed on May 28, 2013, in the Korean Intellectual Property Office, and entitled: “Polarizer and Liquid Crystal Display Having the Same,” is incorporated by reference herein in its entirety.

BACKGROUND

Embodiments relate to a polarizer and a liquid crystal display including the same.

2. Description of the Related Art

A liquid crystal display is a flat panel display that is widely used, and may include two display panels on which electric field generating electrodes such as a pixel electrode and a common electrode are formed and a liquid crystal layer inserted between the two display panels. The liquid crystal display may apply a voltage to the electric field generating electrodes to generate an electric field in the liquid crystal layer, may determine orientations of liquid crystal molecules of the liquid crystal layer, and may control polarization of incident light, so as to display an image through the generated electric field.

SUMMARY

Embodiments are directed to a polarizer and a liquid crystal display including the same

The embodiments may be realized by providing a polarizer including a plurality of metal lines extending in one direction and being arranged at regular intervals; and a plurality of low reflection layers on the plurality of metal lines, the plurality of low reflection layers contacting respective upper parts of the plurality of metal lines and having an interval and a width about equal to an interval and a width of the plurality of metal lines, wherein the interval of the plurality of metal lines is smaller than a wavelength of a visible ray, and light incident from an upper side of the plurality of low reflection layers is reflected with reflectivity equal to or smaller than 10%.

The low reflection layer may be a single layer, the single layer may include a nitride, the nitride including one of AlNx, TiNx, SiNx, CuNx, or MoNx.

The metal line may include aluminum and may have a height of about 150 nm to about 200 nm, and the low reflection layer may have a height of about 40 nm to about 70 nm.

The low reflection layer may be a dual layer, and the dual layer may include a first low reflection layer contacting an upper part of the metal line and a second low reflection layer contacting an upper part of the first low reflection layer.

The first low reflection layer and the second low reflection layer may each include a nitride, the nitride including AlNx, TiNx, SiNx, CuNx, or MoNx, and the nitride of the first low reflection layer may be different from the nitride of the second low reflection layer.

The metal line may include aluminum and may have a height of about 150 nm to about 200 nm, the first low reflection layer may include TiNx and may have a height of about 40 nm to about 70 nm, and the second low reflection layer may include CuNx and may have a height of about 10 nm to about 100 nm.

The metal line may include aluminum and may have a height of about 150 nm to about 200 nm, the first low reflection layer may include MoNx and may have a height of about 10 nm to about 100 nm, and the second low reflection layer may include CuNx and may have a height of about 80 nm to about 100 nm.

The first low reflection layer may include a transparent conductive material, the transparent conductive material including GZO, IZO, ITO, or AZO, and the second low reflection layer may include a metal, the metal including Ti.

The metal line may include aluminum and may have a height of about 150 nm to about 200 nm, the first low reflection layer may have a height of about 50 nm to about 100 nm, and the second low reflection layer may have a height of about 10 nm to about 40 nm.

The first low reflection layer may include an oxide, the oxide including AlOx, TiOx, MoOx, CuOx, or SiOx, and the second low reflection layer may include a metal, the metal including Ti.

The metal line may include aluminum and may have a height of about 150 nm to about 200 nm, the first low reflection layer may have a height of about 40 nm to about 80 nm, and the second low reflection layer may have a height of about 20 nm to about 40 nm.

The embodiments may also be realized by providing a liquid crystal display including a lower display panel including a lower insulation substrate and a lower polarizer attached to one side of the lower insulation substrate; an upper display panel including an upper insulation substrate and an upper polarizer attached to one side of the upper insulation substrate; and a liquid crystal layer between the upper display panel and the lower display panel, wherein the upper polarizer includes a plurality of metal lines extending in one direction and being arranged at regular intervals; and a plurality of low reflection layers on the plurality of metal lines, the plurality of low reflection layers contacting respective upper parts of the plurality of metal lines and having an interval and a width equal to an interval and a width of the plurality of metal lines, an interval of the plurality of metal lines is smaller than a wavelength of a visible ray, and light incident from an upper side of the plurality of low reflection layers is reflected with reflectivity equal to or smaller than 10%.

The low reflection layer may be a single layer, the single layer may include a nitride, the nitride including one of AlNx, TiNx, SiNx, CuNx, or MoNx.

The metal line may include aluminum and may have a height of about 150 nm to about 200 nm, and the low reflection layer may have a height of about 40 nm to about 70 nm.

The low reflection layer may be a dual layer, and the dual layer may include a first low reflection layer contacting an upper part of the metal line and a second low reflection layer contacting an upper part of the first low reflection layer.

The first low reflection layer and the second low reflection layer may each include a nitride, the nitride including AlNx, TiNx, SiNx, CuNx, or MoNx, and the nitride of the first low reflection layer may be different from the nitride of the second low reflection layer.

The metal line may include aluminum and may have a height of about 150 nm to about 200 nm, the first low reflection layer may include TiNx and may have a height of about 40 nm to about 70 nm, and the second low reflection layer may include CuNx and may have a height of about 10 nm to about 100 nm.

The metal line may include aluminum and may have a height of about 150 nm to about 200 nm, the first low reflection layer may include MoNx and may have a height of about 10 nm to about 100 nm, and the second low reflection layer may include CuNx and may have a height of about 80 nm to about 100 nm.

The first low reflection layer may include a transparent conductive material, the transparent conductive material including GZO, IZO, ITO, or AZO, and the second low reflection layer may include a metal, the metal including Ti.

The metal line may include aluminum and may have a height of about 150 nm to about 200 nm, the first low reflection layer may have a height of about 50 nm to about 100 nm, and the second low reflection layer may have a height of about 10 nm to about 40 nm.

The first low reflection layer may include an oxide, the oxide including AlOx, TiOx, MoOx, CuOx, or SiOx, and the second low reflection layer may include a metal, the metal including Ti.

The metal line may include aluminum and may have a height of about 150 nm to about 200 nm, the first low reflection layer may have a height of about 40 nm to about 80 nm, and the second low reflection layer may have a height of about 20 nm to about 40 nm.

The lower polarizer may include a plurality of metal lines extending in one direction and being arranged at regular intervals.

DETAILED DESCRIPTION

Hereinafter, a liquid crystal display according to an exemplary embodiment will be described in detail with reference toFIG. 1.FIG. 1illustrates a cross-sectional view of a liquid crystal display according to an exemplary embodiment.

A liquid crystal display according to an exemplary embodiment may include a backlight unit500and a liquid crystal panel.

The backlight unit500may include a light source, a light guide, a reflector, and an optical sheet, which are just integrally illustrated inFIG. 1. Light provided by the light source may be directed to the liquid crystal panel in an upper side through the light guide, the reflector, and the optical sheet. According to an exemplary embodiment, the optical sheet may not include a luminance improving film generated by depositing two layers having different refractive indexes. The luminance improving film may not be included when a lower polarizer11used in the liquid crystal panel is a reflective polarizer, like the exemplary embodiment ofFIG. 1, and not an absorptive polarizer.

The liquid crystal panel may include a liquid crystal layer3, a lower display panel100, and an upper display panel200as illustrated inFIG. 1.

First, the lower display panel100will be described.

A lower polarizer11may be formed on a lower insulation substrate110. The lower insulation substrate110may be made of a transparent glass or plastic.

The lower polarizer11may be a reflective polarizer, and may include a plurality of metal lines111.

The plurality of metal lines111may extend in one direction and may be separated from each other at or by regular intervals. The interval of or between the metal lines111may be smaller than a wavelength of a visible ray and may have a width of tens to hundreds of nm. A width of the metal line111may vary and may correspond to an interval between the metal lines111in the present exemplary embodiment. A height of the metal line111may vary depending on a material forming the metal line111. The height of the metal line111may be, e.g., tens to hundreds of nm. In an implementation, the height of the metal line111may be about triple the width of the metal line111. In an implementation, the metal line111may include aluminum (Al) or silver (Ag). As described above, when the plurality of metal lines111is arranged in one direction, the metal lines111may transmit the light perpendicular to the arrangement direction and may reflect the light parallel to the arrangement direction. In an implementation, the width of the metal line111may be 50 nm, the interval may be 50 nm, and the height of the metal line111may be 150 nm. In an implementation, the height of the metal line111may be equal to or larger than 150 nm and equal to or smaller than 200 nm, e.g., may be about 150 nm to about 200 nm.

Parts or regions between the plurality of metal lines111may be filled with air, or may be filled with a transparent material having a refractive index similar to that of air, according to an exemplary embodiment.

An opposing insulating layer115(covering the plurality of metal lines111and the intervals between the metal lines111) may be formed on the lower polarizer11. The opposing insulating layer115may serve as a layer for supporting formation of a thin film transistor and wiring thereon.

The plurality of metal lines111may be attached to the opposing insulating layer115and the lower insulation substrate110without a separate resin.

FIG. 1illustrates an exemplary embodiment in which the lower polarizer11is formed in an in-cell type on an upper part of the lower insulation substrate110.

In an implementation, the lower polarizer11may be formed in an on-cell type under the lower insulation substrate110, as opposed to the lower polarizer11ofFIG. 1. For example, the lower polarizer11may be formed in an external side of the lower insulation substrate110, and the opposing insulating layer115may be formed under the metal lines111to cover and/or protect the plurality of metal lines111of the lower polarizer11.

In an implementation, the lower polarizer11may be an absorptive polarizer that absorbs light of polarization at one side, and transmits only light of polarization perpendicular to the lower polarizer11.

Referring back toFIG. 1, a thin film transistor and a pixel electrode may be formed on the opposing insulating layer115of the lower display panel100. The thin film transistor and the pixel electrode may be formed in various structures according to an exemplary embodiment, and the following description will be made based on a simple structure thereof.

A gate line and a gate electrode124(receiving a gate voltage from the gate line) may be formed on the opposing insulating layer115. The gate line may extend in a horizontal direction, and the gate electrode124may protrude from the gate line.

A gate insulating layer140made of silicon nitride (SiNx) or silicon oxide (SiOx) may be formed on the gate line and the gate electrode124.

A semiconductor154made of hydrogenated amorphous silicon (also referred to as a-Si) or polysilicon may be formed on the gate insulating layer140. The semiconductor154may be formed on the gate electrode124and may form a channel of the thin film transistor.

A plurality of data lines and a plurality of drain electrodes175may be formed on the semiconductor154and the gate insulating layer140.

The data line may transmit a data voltage and may extend in a vertical line or direction to cross the gate line. Each of the data lines may include a plurality of source electrodes173extending to the gate electrode124. The drain electrode175may be separated from the data line and may face the source electrode173based on the gate electrode124.

One gate electrode124, one source electrode173, and one drain electrode175may form one thin film transistor (TFT), together with the semiconductor154, and the channel of the thin film transistor may be formed on the semiconductor154between the source electrode173and the drain electrode175.

A plurality of ohmic contacts may be formed on the semiconductor154and between the source electrode173and the drain electrode175.

A passivation layer180may be formed on the data line, the drain electrode175, and an exposed part of the semiconductor154. The passivation layer180may be made of an inorganic insulator or organic insulator, and a surface thereof may be flat.

Examples of the inorganic insulator may include silicon nitride and silicon oxide. The organic insulator may have photosensitivity, and a dielectric constant thereof may be equal to or smaller than about 4.0. Further, the passivation layer180may have a dual-layer structure including a lower inorganic layer and an upper organic layer.

A contact hole exposing one end of the drain electrode175may be formed on the passivation layer180.

A plurality of pixel electrodes190may be formed on the passivation layer180. The pixel electrode190may be made of a transparent conductive material, e.g., ITO or IZO.

The pixel electrode190may be physically or electrically connected with the drain electrode175through the contact hole of the passivation layer180, and may receive a data voltage from the drain electrode175. The pixel electrode190(receiving the data voltage) may generate an electric field together with a common electrode270(receiving a common voltage) to determine a direction of a liquid crystal molecule310of the liquid crystal layer3between the two electrodes190and270. According to the direction of the liquid crystal molecule determined as described above, polarization of the light passing through the liquid crystal layer3may be changed. The pixel electrode190and the common electrode270may form a capacitor (hereinafter, referred to as a “liquid crystal capacitor”) to maintain the received voltage after the thin film transistor is turned off.

An alignment layer may be formed on the pixel electrode190.

Hereinafter, the upper display panel200will be described.

An upper polarizer21may be formed under an upper insulation substrate210. The an upper insulation substrate210may be made of a transparent glass or plastic.

The upper polarizer21may be a reflective polarizer, and may include a plurality of metal lines211and a plurality of low reflection layers212deposited and located on an upper part of each of the metal lines211.

The upper polarizer21may be a reflective polarizer that reflects some light provided by the backlight unit500and transmits the remaining light. Meanwhile, reflectivity of the light having passed through the upper insulation substrate210to be incident from the outside may be lowered to a value equal to or smaller than 10%.

The plurality of metal lines211may extend in one direction and may be separated from each other at regular intervals. The interval of the metal lines211may be smaller than a wavelength of a visible ray, and may have a width of tens to hundreds of nm. A direction in which the plurality of metal lines211of the upper polarizer21extends and a direction in which the plurality of metal lines111of the lower polarizer11extends may be the same in an exemplary embodiment, e.g., as shownFIG. 1. However, in an implementation, the directions may have an angle of 90 degrees or a different angle.

The width of the metal line211may vary and may correspond to the interval between the metal lines211in the present exemplary embodiment. A height of the metal line211may be changed according to a material of the metal line211. The height of the metal line211may be, e.g., tens to hundreds of nm. In an implementation, the height of the metal line211may be about triple the width of the metal line211. In an implementation, the metal line211may include aluminum (Al). As described above, when the plurality of metal lines211is arranged in one direction, the metal lines211may transmit the light perpendicular to the arrangement direction and may reflect the light parallel to the arrangement direction. In an implementation, the width of the metal line211may be about 50 nm, an interval may be about 50 nm, and the height may be about 150 nm. In an implementation, the height of the metal line211may be equal to or larger than 150 nm and equal to or smaller than 200 nm, e.g., may be about 150 nm to about 200 nm. When the plurality of metal lines211is arranged in one direction, light perpendicular to the direction may be transmitted and light parallel to the direction may be reflected.

The low reflection layer212may be deposited on each of the plurality of metal lines211. The low reflection layer212may contact an upper part of a respective metal line211and may have a same width and interval as those of the metal line211. A height of the low reflection layer212may vary depending on a material of the low reflection layer212, which will be described in detail with reference toFIG. 5. In an implementation, the width of the low reflection layer212may be about 50 nm and an interval may be about 50 nm. The low reflection layer212may include a nitride or metal nitride. Examples of the nitride or metal nitride may include AlNx, TiNx, SiNx, CuNx, MoNx, and the like. The low reflection layer212may contact only the upper part of the metal line211, and may not be formed on a side surface of the metal line211, so that the low reflection layer212may not cover both the side surface and the upper part of the metal line211. Such an arrangement may help prevent a deterioration in an effect of reflection polarization performed by the metal line211.

Parts or regions between the plurality of metal lines111and between the plurality of row reflection layers212may be filled with air, or may be filled with a transparent material having a refractive index similar to that of air, according to an exemplary embodiment.

The plurality of metal lines211and the plurality of low reflection layers212may directly contact the upper insulation substrate210and a layer under the metal lines211and the low reflection layers212. For example, the plurality of metal lines211and the plurality of low reflection layers212may not adhere to an adjacent substrate or layer through the use of separate resin, thereby reducing optical loss.

In an implementation, the upper polarizer21illustrated inFIG. 1may be formed on a lower part of the upper insulation substrate210in an in cell type.

In another implementation, the upper polarizer21may be formed on the upper insulation substrate210in an on cell type unlike the upper polarizer21ofFIG. 1, which will be described below with reference toFIG. 30.

Although not illustrated inFIG. 1, a separate opposing insulating layer may be included in lower parts of the plurality of metal lines211. The opposing insulating layer may help prevent the plurality of metal lines211from directly contacting a lower layer (a light blocking member220, a color filter230, or the like), and thus may help protect the plurality of metal lines211during a manufacturing process.

The light blocking member220, the color filter230, and the common electrode270may be formed under the upper polarizer21. In an implementation, at least one of the light blocking member220, the color filter230, and the common electrode270may be formed on the lower display panel100, and all of them may be formed on the lower display panel100. A structure below the upper polarizer21of the upper display panel200ofFIG. 1is as follows.

The light blocking member220may be formed under the upper polarizer21. The light blocking member220may also be called a black matrix and may help reduce and/or prevent light leakage. The light blocking member220may face the pixel electrode190, and may be formed in a part or region corresponding to the gate line and the data line and a part or region corresponding to the thin film transistor to help reduce and/or prevent light leakage between the pixel electrodes190. The light blocking member220may have an opening (indicated as TA inFIG. 1) in a part or region corresponding to the pixel electrode190.

A plurality of color filters230may be formed under the upper polarizer21and the light blocking member220. The color filters230may cover the opening of the light blocking member220and may extend long in a vertical direction. Each of the color filters230may indicate one of the primary colors, e.g., primary colors including red, green and blue.

An overcoat250may be formed under the color filters230and the light blocking member220. The overcoat250may be made of an organic insulator, and may help prevent the color filters230from being exposed and may provide a flat surface. In an implementation, the overcoat250may be omitted.

The common electrode270may be formed under the overcoat250. The common electrode270may be made of a transparent conductor, e.g., ITO, IZO, or the like.

An alignment layer may be formed under the common electrode270.

The liquid crystal layer3may be formed between the upper display panel200and the lower display panel100. The liquid crystal layer3may include a liquid crystal molecule310having dielectric anisotropy. A long axis of the liquid crystal molecule310may be perpendicular to or parallel to surfaces of the two display panels100and200in a state where there is no electric field. An alignment direction of the liquid crystal molecule310may be changed by the electric field generated by the pixel electrode190and the common electrode270.

Hereinafter, a structure of the upper polarizer21according to an exemplary embodiment will be described in detail with reference toFIG. 2.

FIG. 2illustrates an enlarged cross-sectional view of the polarizer according to an exemplary embodiment. For example, and the upper polarizer21and the upper insulation substrate210are illustrated inFIG. 2.

The upper polarizer21may be located in an inner side of the upper insulation substrate210located in an outer side.

The upper polarizer21may include the plurality of metal lines211and may be formed of a metal, e.g., Al. The plurality of metal lines211formed of Al may reflect light incident from the outside with reflectivity of about 45%. As described above, when the reflectivity is large, the user may have a difficulty in viewing an image of the display device due to an external environment (seeFIG. 29). Accordingly, the embodiments may reduce the reflectivity of the upper polarizer21to 10% or smaller by adding the low reflection layer212.

The low reflection layer212in an exemplary embodiment ofFIG. 1may include a nitride or a metal nitride. Examples of the nitride or metal nitride may include AlNx, TiNx, SiNx, CuNx, MoNx, and the like.

A width and an interval of the metal line211may be the same as those of the low reflection layer212. Although not illustrated in lower parts of the metal lines211, a separate opposing insulating layer or film may be formed to protect the metal lines211. The metal lines211and the opposing insulating layer may directly contact without a separate layer (such as resin) to help improve optical efficiency.

The low reflection layer212may directly contact upper parts of the metal lines211. An upper surface of the low reflection layer212may directly contact the upper insulation substrate210(without a separate layer such as resin) to help improve optical efficiency.

In an implementation, a height of the low reflection layer212(to allow reflectivity of the upper polarizer21to be 10% or smaller) will be described with reference toFIGS. 3 to 6.

FIGS. 3 to 6illustrate graphs showing characteristics of the polarizer according to an exemplary embodiment.

As illustrated inFIG. 6, values inFIGS. 3 to 6were generated through an experiment under the following conditions.

In an exemplary embodiment in which the metal lines211were formed of Al and the low reflection layer212was formed of TiNx, an experiment was performed for a wavelength of 550 nm when a period (sum of the width and the interval) of the metal line211and the low reflection layer212was 100 nm and a height of the metal line211was 150 nm.

FIGS. 3 and 4illustrate ER values according to heights of the metal line211and the low reflection layer212, respectively. The ER value refers to a value of “transmittance of light of a penetrated polarization direction/transmittance of light of a blocked polarization direction ofFIG. 6.

In an implementation, the ER may be equal to or larger than 100,000, in order to allow the display device to have a CR value of about 10,000. To this end, referring toFIG. 3, the height of the metal line211formed of Al may have a value equal to or larger than 150 nm and equal to or smaller than 200 nm, e.g., may be about 150 nm to about 200 nm.

In an implementation, the ER value may be equal to or larger than 100,000 by forming the metal line of TiNx, and it may be identified that ER values are equal to or larger than 100,000 in most heights inFIG. 4.

Meanwhile,FIG. 5illustrates reflectivity according to a height of TiNx.

Referring toFIG. 5, a height of TiNx to make reflectivity be 10% (0.1 inFIG. 5) or smaller may be equal to or larger than 40 nm and equal to or smaller than 70 nm, e.g., may be about 40 nm to about 70 nm.

Accordingly, a height of the low reflection layer212may have a value equal to or larger than 40 nm and equal to or smaller than 70 nm, e.g., may be about 40 nm to about 70 nm, to allow the upper polarizer21to have a low reflection characteristic.

The values ofFIGS. 3 to 5are illustrated by values in a table ofFIG. 6

InFIG. 6, TE is a polarization direction blocked by the upper polarizer21, TM is a penetrated polarization direction, SumR is reflectivity, and SumT is transmittance. Here, ER is a value of SumT in SumT/TE of TM.

Hereinafter, a structure according to another exemplary embodiment will be described based onFIG. 7.FIG. 7illustrates an enlarged cross-sectional view of the polarizer according to another exemplary embodiment.

For example,FIG. 7shows a structure including two low reflection layers212and213, different from the structure ofFIG. 2.

The upper polarizer21may be formed under the upper insulation substrate210(made of a transparent glass or plastic).

The upper polarizer21may be a reflective polarizer, may include the plurality of metal lines211and the two low reflection layers212and213deposited and located on each of the metal lines211, and may reduce reflectivity of light passing through the upper insulation substrate210and incident from the outside to about 10% or smaller.

The plurality of metal lines211may extend in one direction and may be separated from each other at regular intervals. The interval of the metal lines211may be smaller than a wavelength of a visible ray, e.g., the interval may have a width of tens to hundreds of nm. The width of the metal line211may vary, and may have a value corresponding to an interval between the metal lines211in the present exemplary embodiment. A height of the metal line211may vary depending on a material forming the metal line211. The height of the metal line211may be, e.g., tens to hundreds of nm. In an implementation, the height of the metal line211may be about triple the width of the metal line211. The metal line111may include, e.g., aluminum (Al). As described above, when the plurality of metal lines211is arranged in one direction, the metal lines211may transmit the light perpendicular to the arrangement direction and may reflect the light parallel to the arrangement direction. In an implementation, the width of the metal line211may be about 50 nm, the interval may be about 50 nm, and the height may be about 150 nm. The height of the metal line211may be equal to or larger than 150 nm and equal to or smaller than 200 nm, e.g., may be about 150 nm to about 200 nm. When the plurality of metal lines211are arranged in one direction, the metal lines211may transmit light perpendicular to the direction and reflect light parallel to the direction.

The two low reflection layers212and213may be deposited on each of the plurality of metal lines211. The two low reflection layers212and213contact an upper part of one, e.g., respective, metal line211and have the same width and interval as those of the metal line211. A height of each of the low reflection layers212and213may vary depending on a material used to form the low reflection layers212and213. A width of the low reflection layers212and213according to an exemplary embodiment may be about 50 nm, and an interval may be about 50 nm.

The two low reflection layers212and213may contact only upper parts of the respective metal lines211, and may not be formed on side surfaces of the metal lines211. Accordingly, at least one of the two low reflection layers212and213may not cover both the side surface and the upper part of the metal line211. Thus, a deterioration in an effect of reflection polarization performed by the metal lines211may be avoided.

Parts or regions between the plurality of metal lines211and between the plurality of row reflection layers212and213may be filled with air, or may be filled with a transparent material having a refractive index similar to that of air according to an exemplary embodiment.

The plurality of metal lines211and the plurality of low reflection layers212and213may directly contact the upper insulation substrate210and a layer under the metal lines211and the low reflection layers212and213. For example, the plurality of metal lines211and the plurality of low reflection layers212and213may not be adhered to an adjacent substrate or layer through the use of separate resin, thereby reducing optical loss.

The first low reflection layers212may contact upper surfaces of the plurality of metal lines211, and the second low reflection layers213may contact upper surfaces of the first low reflection layers212.

The first low reflection layer212and the second low reflection layer213may have a same width and interval as those of the metal line211.

The first low reflection layer212and the second low reflection layer213may be formed of various materials. A height of each of the layers may be changed according to the various materials. In an implementation, the height may make reflectivity of the upper polarizer21be about 10% or smaller.

In an implementation, the first low reflection layer212and the second low reflection layer213may include a different nitride or metal nitride. Examples of the nitride or metal nitride may include AlNx, TiNx, SiNx, CuNx, MoNx, and the like.

Hereinafter, a height of the low reflection layer213will be described with reference toFIGS. 8 to 11, in which TiNx was used for the first low reflection layer212and CuNx was used for the second low reflection layer213.

When Al was used for the metal line211, the upper polarizer21had a reflectivity of about 45%. However, the reflectivity of the upper polarizer21may be reduced to 10% or smaller by forming the low reflection layers212and213with two layers of nitride or metal nitride (seeFIG. 29).

FIG. 8illustrates ER values according to heights of a CuNx layer. The ER may have a value equal to or larger than 100,000, and it may be identified that all heights have corresponding ER values.

FIG. 9illustrates a graph showing reflectivity according to heights of a CuNx layer. It may be seen that all heights may be used due to the reflectivity being equal to or smaller than 10% (0.1 ofFIG. 9) in all areas.

The data ofFIGS. 8 and 9as described above was obtained under the same experimental conditions as those ofFIG. 10, and the corresponding conditions were as follows.

In an exemplary embodiment in which the metal lines211were formed of Al, the first low reflection layer212was formed of TiNx, and the second low reflection layer213was formed of CuNx, an experiment was performed for a wavelength of 550 nm when a period (sum of the width and the interval) of the metal line211and the low reflection layers212and213was 100 nm, a height of the metal line211was 150 nm, and a height of the first low reflection layer212of TiNx was 40 nm.

As described above, when the second low reflection layer213of CuNx was foinied on a structure in which the first low reflection layer212of TiNx was formed on the metal line211of Al, it may be seen that CuNx (used for the second low reflection layer) had reflectivity equal to or smaller than 10%, regardless of the height thereof.

Hereinafter, the height of the first low reflection layer212of TiNx will be described, based on the height of the second low reflection layer213of CuNx determined as 10 nm with reference toFIG. 11.

As illustrated inFIG. 11, it may be seen that reflectivity equal to or smaller than 10% (0.1) corresponded to a value equal to or larger than 40 nm and equal to or smaller than 70 nm, e.g., of about 40 nm to about 70 nm. The height of the second low reflection layer213may vary (equal to or larger than 10 nm and equal to or smaller than 100 nm), and may have a value of 10 nm in one exemplary embodiment. The height of the metal line211was 150 nm. In an implementation, the height of the metal line211may be equal to or larger than 150 nm and equal to or smaller than 200 nm, e.g., about 150 nm to about 200 nm.

FIGS. 12 to 14illustrate graphs showing experimental data of an exemplary embodiment of the two low reflection layers212and213formed of metal nitride in which the second low reflection layer213included CuNx and the first low reflection layer212included MoNx.

First,FIG. 12illustrates a graph of ER with respect to a height of MoNx. In an implementation, the ER value may equal to or larger than 100,000. It may be seen that the ER had a value equal to or larger than 100,000 with respect to all heights of MoNx.

FIG. 13illustrates reflectivity of the upper polarizer according to a height of CuNx. It may be seen that a height of CuNx having reflectivity equal to or smaller than 10% had a value equal to or larger than 80 nm.

FIG. 14illustrates values according to the height of CuNx, based on a height of MoNx being fixed at 50 nm. Experiment conditions ofFIG. 14were as follows.

In an example in which the metal lines211were formed of Al, the first low reflection layer212was formed of MoNx, and the second low reflection layer213was formed of CuNx, an experiment was performed for a wavelength of 550 nm when a period (sum of the width and the interval) of the metal line211and the low reflection layers212and213was 100 nm, a height of the metal line211was 150 nm, and a height of the first low reflection layer212of MoNx was 50 nm.

InFIG. 14, reflectivity equal to or smaller than 10% corresponds to examples in which the second low reflection layer213of CuNx had a height equal to or larger than 80 nm and equal to or smaller than 100 nm, e.g., about 80 nm to about 100 nm. Although the upper limit was determined as 100 nm, the experiment was not performed for heights larger than 100 nm. Thus, heights larger than 100 nm may have reflectivity equal to or smaller than 10%, and the second low reflection layer213may be actually formed to have a height equal to or larger than 100 nm.

It may be seen inFIG. 14that the reflectivity has a value of about 10.5% when the second low reflection layer213of CuNx was 80 nm. Accordingly, the reflectivity exceeded 10%. However, in consideration of a slight error, it is determined as the height suitable for the reflectivity of about 10% when the upper polarizer21is formed.

When the second low reflection layer213of CuNx and the first low reflection layer212of MoNx are used, CuNx may have a height equal to or larger than about 80 nm and equal to or smaller than about 100 nm, MoNx may have a height (e.g., about 30 nm or about 50 nm) equal to or larger than about 10 nm and equal to or smaller than about 100 nm. The metal line of Al may have a height equal to or larger than 150 nm and equal to or smaller than 200 nm, e.g., about 150 nm to about 200 nm.

Hereinafter, a case in which a transparent conductive material is used for the first low reflection layer212and a metal is used for the second low reflection layer213will be described with reference toFIGS. 15 to 20.

Examples of the transparent conductive material (e.g., transparent conductive oxide: TCO) may include gallium-doped zinc oxide (GZO), indium zinc oxide (IZO), indium-tin oxide (ITO), aluminum doped zinc oxide (AZO), and the like. The metal used for the second low reflection layer213may include, e.g., titanium (Ti) or the like.

In the experiment, IZO was used for the first low reflection layer212and Ti was used for the second low reflection layer213.

Referring toFIG. 15, a change in ER according to a change in a height of Ti is illustrated. ER values equal to or larger than 100,000 corresponded to all heights of Ti, it may be seen that sufficient CR may be secured if Ti is formed, regardless of the height.

FIGS. 16 and 17illustrate results of an experiment under the following conditions. (SeeFIG. 17)

In an example in which the metal line211was formed of Al, the first low reflection layer212was formed of IZO, and the second low reflection layer213was formed of Ti, an experiment was performed at a wavelength of 550 nm when a period (sum of the width and the interval) of the metal line211and the low reflection layers212and213was 100 nm, a height of the metal line211was 150 nm, and a height of the second low reflection layer213of Ti was 20 nm.

Reflectivity of the upper polarizer21according to the height of IZO is illustrated inFIG. 16.

Based onFIGS. 16 and 17, it may be seen that the upper polarizer21had reflectivity equal to or smaller than 10% when the height of IZO had a value equal to or larger than 50 nm and equal to or smaller than 100 nm, e.g., about 50 nm to about 100 nm.

Therefore, in an exemplary embodiment, Al of the metal line211may have a height equal to or larger than 150 nm and equal to or smaller than 200 nm, IZO of the first low reflection layer212may have a height equal to or larger than 50 nm and equal to or smaller than 100 nm, and Ti of the second low reflection layer213may have a height equal to or larger than 10 nm and equal to or smaller than 40 nm.

The IZO used in the experiments corresponding toFIGS. 15 to 17had an indium content of 70%. Characteristics of IZO may change according to the indium content. Hereinafter, results of experiments in which IZO having an indium content of 10% was used are illustrated inFIGS. 18 to 20.

Referring toFIG. 18, although having differences fromFIG. 15, it may be seen that ER was totally 100,000 or larger with respect to various heights of Ti.

Meanwhile,FIGS. 19 and 20illustrate results of experiments conducted under the following conditions. (SeeFIG. 20)

In an example in which the metal line211was formed of Al, the first low reflection layer212was formed of IZO, and the second low reflection layer213was formed of Ti, an experiment was performed at a wavelength of 550 nm when a period (sum of the width and the interval) of the metal line211and the low reflection layers212and213was 100 nm, a height of the metal line211was 150 nm, and a height of the second low reflection layer213of Ti was 30 nm.

A graph showing the reflectivity of the upper polarizer21according to the height of IZO is shown inFIG. 19.

Based onFIGS. 19 and 20, it may be seen that the upper polarizer21had reflectivity equal to or smaller than 10% when the height of IZO was equal to or larger than 50 nm and equal to or smaller than 100 nm, e.g., from about 50 nm to about 100 nm.

Referring toFIGS. 15 to 20, although a characteristic change was generated according to the indium content of IZO, it may be seen that there was no significant difference.

Therefore, in an exemplary embodiment, Al of the metal line211may have a height equal to or larger than about 150 nm and equal to or smaller than about 200 nm, IZO of the first low reflection layer212may have a height equal to or larger than about 50 nm and equal to or smaller than about 100 nm, and Ti of the second low reflection layer213have a height (e.g., about 30 nm) equal to or larger than about 10 nm and equal to or smaller than about 40 nm.

Hereinafter, an example in which an oxide or metal oxide was used for the first low reflection layer212and a metal as used for the second low reflection layer213will be described with reference toFIGS. 21 to 26.

Examples of the oxide or metal oxide may include AlOx, TiOx, MoOx, CuOx, SiOx, and the like. The metal used for the second low reflection layer213may include, e.g., titanium (Ti) or the like.

In the experiment, TiOx was used for the first low reflection layer212and Ti was used for the second low reflection layer213.

Referring toFIG. 21, a change in ER according to a change in a height of TiOx is illustrated. ER values equal to or larger than 100,000 corresponded to all heights of Ti equal to or smaller than 100 nm, it may be seen that sufficient CR was secured when TiOx was formed, regardless of the height.

FIGS. 22 and 23illustrate experimental results under the following conditions. (SeeFIG. 23)

In an example in which the metal line211was formed of Al, the first low reflection layer212was formed of TiOx, and the second low reflection layer213was formed of Ti, an experiment was performed at a wavelength of 550 nm when a period (sum of the width and the interval) of the metal line211and the low reflection layers212and213was 100 nm, a height of the metal line211was 150 nm, and a height of the second low reflection layer213of Ti was 20 nm.

A graph showing the reflectivity of the upper polarizer21according to the height of TiOx is illustrated inFIG. 22.

Based onFIGS. 22 and 23, it may be seen that the upper polarizer21had reflectivity equal to or smaller than 10% when the height of TiOx had a value equal to or larger than about 40 nm and equal to or smaller than about 80 nm, e.g., about 40 nm to about 80 nm.

Therefore, in an exemplary embodiment, Al of the metal line211may have a height equal to or larger than about 150 nm and equal to or smaller than about 200 nm, TiOx of the first low reflection layer212may have a height equal to or larger than about 40 nm and equal to or smaller than about 80 nm, and Ti of the second low reflection layer213may have a height of about 20 nm.

Hereinafter, an exemplary embodiment in which a height of Ti was 30 nm will be described with reference toFIGS. 24 to 26.

Referring toFIG. 24,FIG. 24is almost similar toFIG. 21, in spite of a difference in material. ER values equal to or larger than 100,000 corresponded to all heights of Ti equal to or smaller than 100 nm. Thus, it may be seen that sufficient CR was secured when TiOx was formed, regardless of the height.

In an example in which the metal line211was formed of Al, the first low reflection layer212was formed of TiOx, and the second low reflection layer213was formed of Ti, an experiment is performed at a wavelength of 550 nm when a period (sum of the width and the interval) of the metal line211and the low reflection layers212and213was 100 nm, a height of the metal line211was 150 nm, and a height of the second low reflection layer213of Ti was 30 nm.

A graph showing reflectivity of the upper polarizer21according to the height of TiOx is illustrated inFIG. 25.

Based onFIGS. 25 and 26, it may be seen that the upper polarizer21had reflectivity equal to or smaller than 10% when the height of TiOx has a value equal to or larger than about 40 nm and equal to or smaller than about 80 nm.

Referring toFIGS. 21 to 26, it may be seen that the upper polarizer21had reflectivity equal to or smaller than 10% when the height of TiOx was equal to or larger than about 40 nm and equal to or smaller than about 80 nm, regardless of the height of Ti.

Therefore, in an exemplary embodiment, Al of the metal line211may have a height equal to or larger than about 150 nm and equal to or smaller than about 200 nm, TiOx of the first low reflection layer212may have a height equal to or larger than about 40 nm and equal to or smaller than about 80 nm, and Ti of the second low reflection layer213may have a height equal to or larger than about 20 nm and equal to or smaller than about 40 nm.

In the above description, the experiment results are discussed based on the exemplary embodiments in which various low reflection layers were used.

FIGS. 27 and 28illustrate materials that may be used for the low reflection layer and characteristics thereof. For example,FIGS. 27 and 28illustrate examples of materials that may be used for the polarizer according to an exemplary embodiment and characteristics thereof.

Based onFIG. 27, oxide, metal oxide, nitride, metal nitride, a transparent conductive material (transparent conductive oxide (TCO), and/or a metal may be used for the low reflection layer, and a detailed material corresponding to each of the above materials is also illustrated.

Further,FIG. 28illustrates values of refractive indexes (n, k) with respect to wavelengths for each material.

Referring toFIGS. 27 and 28, various materials may be used for the low reflection layer according to an exemplary embodiment. It may be seen that one reflection layer may be included as illustrated inFIG. 2or two low reflection layers may be included as illustrated inFIG. 7.

In an implementation, three or more low reflection layers may be formed.

An exemplary embodiment features a structure including the above described low reflection layer(s) and also reflectivity equal to or smaller than 10%.

The feature will be described in comparison with a comparative example ofFIG. 29.FIG. 29illustrates a graph showing reflectivity of the comparative example.

The graph ofFIG. 29illustrates reflectivity according to a height of Ti in a structure where a metal of Ti was included in a metal line formed of Al. A part having the height of Ti of 0 was formed only of the metal line of Al and reflectivity was about 45%. Even though the height was changed by forming Ti on the metal line of Al, the reflectivity converged on a middle value between 10% and 20%. Accordingly, it may not be possible to acquire the reflectivity equal to or smaller than 10% as in the exemplary embodiment.

Hereinafter, a liquid crystal display according to another exemplary embodiment will be described with reference toFIG. 30.FIG. 30illustrates a cross-sectional view of a liquid crystal display according to another exemplary embodiment.

FIG. 30illustrates a liquid crystal display in an on cell type in which the upper polarizer21is located in an outer side of the upper insulation substrate210, unlike the embodiment illustrated inFIG. 1.

Only differences of the upper polarizer21from that ofFIG. 1will be described below.

The upper polarizer21may be formed on the upper insulation substrate210(made of a transparent glass or plastic).

The upper polarizer21may be a reflective polarizer and may include the plurality of metal lines211and the plurality of low reflection layers212deposited and located on the respective metal lines211.

The plurality of metal lines211may extend in one direction and may be separated from each other at or by regular intervals. The interval of the metal lines211may be smaller than a wavelength of a visible ray, e.g., may have a size or width of tens to hundreds of nm. A direction in which the plurality of metal lines211of the upper polarizer21extend and a direction in which the plurality of metal lines111of the lower polarizer11extends may be the same in an exemplary embodiment ofFIG. 1. However, in an implementation, the directions may have an angle of 90 degrees or a different angle.

The width of the metal line211may vary, and may have a value corresponding to the interval between the metal lines211in the present exemplary embodiment. A height of the metal line211may be changed according to a material of the metal line211, and may be tens to hundreds of nm. In an implementation, the height may be about triple the width of the metal line211. In an implementation, the metal line211may include aluminum (Al). As described above, when the plurality of metal lines211is arranged in one direction, the metal lines211may transmit the light perpendicular to the arrangement direction and reflect the light parallel to the arrangement direction. In an implementation, the width of the metal line211may be about 50 nm, an interval may be about 50 nm, and the height may be about 150 nm. In an implementation, the height of the metal line211may be equal to or larger than about 150 nm and equal to or smaller than about 200 nm, e.g., about 150 nm to about 200 nm. When the plurality of metal lines211is arranged in one direction, light perpendicular to the direction may be penetrated and light parallel to the direction may be reflected.

The low reflection layer212may be deposited on each of the plurality of metal lines211. The low reflection layer212may contact an upper part of one, e.g., respective, metal line211and may have the same width and interval as those of the metal line211. A height of the low reflection layer212may vary depending on a material used to form the low reflection layer212. The low reflection layer212may contact only the upper part of the metal line211, and may not be formed on a side surface of the metal line211, so that the low reflection layer212may not cover both the side surface and the upper part of the metal line211. Accordingly, a deterioration in an effect of reflection polarization performed by the metal line211may be avoided.

The opposing insulating layer215may be formed on the plurality of low reflection layers212. The opposing insulating layer215may be a layer for protecting the low reflection layer212from the outside and supporting the low reflection layer212, and may be formed of a film.

Parts or regions between the plurality of metal lines211and between the plurality of low reflection layers212may be filled with air, or may be filled with a transparent material having a refractive index similar to that of air according to an exemplary embodiment.

The plurality of metal lines211and the plurality of low reflection layers212may directly contact the upper insulation substrate210and the opposing insulating layer215. For example, the plurality of metal lines211and the plurality of low reflection layers212may not be adhered through the use of a separate resin, thereby reducing optical loss due to a resin layer.

A number of low reflection layers212of the upper polarizer21used in an exemplary embodiment ofFIG. 30also may be two or more.

By way of summation and review, the liquid crystal display may display an image by using a backlight located at a rear surface of a liquid crystal cell according to a light source. When outside or ambient light is bright, a user may have a difficulty in recognizing an image displayed by the liquid crystal display. For example, the liquid crystal display may reflect external light.

The embodiments provide a polarizer used in an upper part of a liquid crystal display.

The embodiments provide a polarizer having a low reflection characteristic.

According to an embodiment, on a polarizer including a metal line, a single low reflection layer or two or more low reflection layers may be additionally formed on a part of the metal line receiving external light, so that the polarizer may have a low reflection characteristic. As a result, light efficiency may be increased by reflecting and polarizing light through the metal line, and a user may easily view an image due to the low reflection characteristic.