KR20060010542A - Color filter and liquid crystal display device using the same - Google Patents

Abstract

The present invention relates to a color filter driven by an electron pump method for each pixel by using a light crystal having a predetermined wavelength-specific reflection characteristic, and a liquid crystal display device using the same, wherein the liquid crystal display device includes first and second substrates facing each other. And a plurality of holes spaced apart from each other in the first substrate, a plurality of electrodes formed on a surface of each hole, and formed in the hole in contact with each of the electrodes, and reflecting light having a predetermined wavelength when voltage is applied to the electrodes. And a liquid crystal formed between the photonic crystal and the first and second substrates.

Electron pump, photonic crystal, color filter, photonic bandgap

Description

Color filter and liquid crystal display device using the same}

1 is an exploded perspective view showing a general liquid crystal display device

2 shows two ways of representing color;

3A to 3C show a photonic crystal structure arranged for each dimension

4 is a diagram showing Bragg relation and light transmission accordingly;

5 is a spectrum showing the light transmittance of the opal

6 shows a photonic crystal composed of colloidal particles

7A and 7B show the operation of the off state and the on state of the electronic pump;

8 is a schematic diagram illustrating a liquid crystal display according to a first embodiment of the present invention.

9 is a schematic diagram illustrating a liquid crystal display according to a second embodiment of the present invention.

10A and 10B illustrate on / off driving for each pixel of the liquid crystal display of the present invention.

11 is a schematic diagram illustrating a liquid crystal display according to a third exemplary embodiment of the present invention.

12 is a circuit diagram of FIG.

* Description of symbols on the main parts of the drawings *

40: liquid crystal 50: cavity                 

60 electrode 100 second substrate

110: first substrate 111: first electrode

112: second electrode 113: third electrode

114: first cavity 115: first particle

116: Second Particle 117: Second Cavity

118: Third Joint 119: Third Joint

120: liquid crystal 131: first photonic crystal

132: second photonic crystal 132: third photonic crystal

135 common electrode 140 transparent electrode

151: gate line 152: data line

200: first substrate 210: second substrate

211: first pixel electrode 212: second pixel electrode

213: third pixel electrode 214: first photonic crystal

215: second photonic crystal 216: third photonic crystal

220: liquid crystal 225: protective film

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display, and more particularly, to a color filter driven by an electron pump method for each pixel using a light crystal having a predetermined wavelength-specific reflection characteristic, and a liquid crystal display using the same.

As the information society develops, the demand for display devices is increasing in various forms, and in recent years, liquid crystal display devices (LCDs), plasma display panels (PDPs), electro luminescent displays (ELD), and vacuum fluorescent (VFD) Various flat panel display devices such as displays have been studied, and some of them are already used as display devices in various devices.

Among them, LCD is the most widely used as the substitute for CRT (Cathode Ray Tube) for mobile image display device because of its excellent image quality, light weight, thinness, and low power consumption. In addition to the use of the present invention has been developed in various ways such as a television and a computer monitor for receiving and displaying broadcast signals.

In order to use such a liquid crystal display as a general screen display device in various parts, it is a matter of how high quality images such as high definition, high brightness and large area can be realized while maintaining the characteristics of light weight, thinness and low power consumption. Can be.

Hereinafter, a general liquid crystal display device and a photonic crystal mentioned in recent years will be described with reference to the accompanying drawings.

1 is an exploded perspective view showing a general liquid crystal display.

As shown in FIG. 1, the liquid crystal display device includes a liquid crystal layer formed between the first substrate 1 and the second substrate 2 bonded to each other with a predetermined space, and the first substrate 1 and the second substrate 2. It consists of (3).

In more detail, the first substrate 1 may have a plurality of gate lines 4 in one direction and constant in a direction perpendicular to the gate lines 4 at regular intervals to define the pixel region P. FIG. A plurality of data lines 5 are arranged at intervals. In addition, a pixel electrode 6 is formed in each pixel region P, and a thin film transistor T is formed at a portion where the gate line 4 and the data line 5 intersect each other, thereby forming the thin film transistor. The data signal of the data line is applied to each pixel electrode according to the signal on the gate line.

In addition, a black matrix layer 7 is formed on the second substrate 2 to block light in portions other than the pixel region P, and portions R corresponding to the respective pixel regions are formed to express colors. , G, B color filter layers 8 are formed, and a common electrode 9 for realizing an image is formed on the color filter layers 8.

In the liquid crystal display as described above, the liquid crystal layer 3 formed between the first and second substrates 1 and 2 is oriented by an electric field formed between the pixel electrode 6 and the common electrode 9, The amount of light passing through the liquid crystal layer 3 may be adjusted according to the degree of alignment of the liquid crystal layer 3 to express an image.

On the other hand, the light we can see, namely visible light, is spread in rainbow colors from violet to red with wavelengths between 400 and 700 nm. When all of these wavelengths are combined, our eyes feel like bright light without color, or white light.

In the above-described general liquid crystal display or other display devices, the white light incident from the lower backlight during display is displayed using R, G, and B color filters formed for each pixel to display light of a corresponding color. At this time, the R, G, B color filter is composed of a pigment or color film containing a pigment of the color to be displayed.

However, coloring does not always require coloring. In addition to the above-described method of using a dye, there is a method of using a photonic crystal.

Light has particle properties and wave properties. Therefore, the interference phenomenon which is characteristic of the wave is shown. Interference is a phenomenon in which the amplitude is further enhanced when the waves are in phase (interference reinforcement) and disappears when the phases are opposite (interference disappearance). When white light encounters a medium and interferes with it, interference reinforcement occurs in a specific wavelength region, and interference disappears in another wavelength so that only light of a specific wavelength is displayed.

The light structure is a color display method using the particle and wave characteristics of light at the same time.

2 is a view showing two methods of displaying color, that is, a color display method using a dye and a light structure.

The color display method using a dye uses a property of a dye molecule that absorbs part of visible light and reflects the rest to show color. As shown in the left side of Fig. 2, for example, the reason why the leaves are green is that chlorophyll reflects green light and absorbs light in the remaining areas. The absorbed light energy is then used to raise the electrons of the chlorophyll molecules to the ground.

As shown in the right side of FIG. 2, when the cross section of the surface of the Morpho butterfly is magnified with an electron microscope, a regular arrangement such as stacking tiles appears. When light shines onto this regular array of structures, only light of a certain wavelength is reflected and the rest passes through.

This geometric form is called photonic crystal. Photonic crystals reflect only light of a specific wavelength and absorb the rest. The photonic crystal of the morpho butterfly described above is designed to reflect only blue light.

In this case, when the light incident on the wing surface of the flying butterfly is reflected in each layer, the blue light, which is the wavelength, is reflected by constructive interference, and the light of the remaining colors causes destructive interference when it is reflected. Penetrates the layer. This is why the wings of the Morpho butterfly look blue.

The color due to the pigment and the color display due to the photonic crystal have the following differences.

First, the color represented by the dye is a result of the interaction of light and pigment molecules, and thus has no relation to the displayed color and the shape of the dye molecule. That is, the pigment molecules on the surface where the light comes into contact with the pigment, whether powder or lump, give color.

However, the color displayed by the photonic crystal may change or disappear depending on the shape of the structure. If you increase or decrease the spacing of the tile-like tissue on the wing surface of the Morpho butterfly, the path of the light changes, thus reinforcing interference, that is, the wavelength of the reflected light. The reflected color also changes depending on the angle of light entering the wing surface. This is why the color of the butterfly is not the same depending on the viewing angle.

In the case of Opal in nature, this optical structure is spread in three dimensions.                         

Such photonic crystals may be artificially formed as well as natural, and researches for forming photonic crystals with various structures and applying them to display devices have been made.

3A to 3C are diagrams showing photonic crystals arranged in each dimension.

The photonic crystals of FIGS. 3A to 3C have a period of several hundred nanometers (nm) to several micrometers (μm) and have a first dimension 11 and a second dielectric 12 having different refractive indices, respectively. It is characterized by being arranged in two or three dimensions. Such an arrangement of photonic crystals may be artificially formed, such as a structure existing in nature such as a wing of an morpho butterfly, an opal, or the like.

As shown in FIG. 3A, the one-dimensional photonic crystal is formed by alternately arranged in layers on the side surface of the first dielectric 11 and the second dielectric 12. In such a photonic crystal, light of a predetermined wavelength range has reflection characteristics in one dimension.

For example, the wing of the morpho butterfly is a regular arrangement of the first dielectric 11, which is a tiled cuticle, and the second dielectric 12, which is an air component.

As shown in FIG. 3B, the two-dimensional photonic crystal is formed by forming a structure in which a cylindrical first dielectric 11 and a second dielectric 12 are periodically repeated on one side. A plurality of layers are arranged. In such a photonic crystal, light of a predetermined wavelength range has reflection characteristics in two dimensions.

As shown in FIG. 3C, the three-dimensional photonic crystal is formed such that the first dielectric member 11 and the second dielectric member 12 are periodically arranged in a lattice form in a cubic structure. In such a photonic crystal, light of a predetermined wavelength range has reflection characteristics in three dimensions.

For example, minerals such as opal have a first arrangement 11 in the form of particles and a second dielectric 12 filling the periphery of the first dielectric 11 in a periodic arrangement to form an entire cube. .

In this case, the wavelengths of the reflected region can be adjusted by selecting each dielectric material according to the distance between the first dielectric material 11 and the second dielectric material 12 and the refractive index. As described above, light of a predetermined wavelength region is reflected in the photonic crystal manufactured by selecting the dielectric of the first and second dielectric layers 11 and 12 and the dielectric having the corresponding refractive index, and the light of the remaining wavelength region is transmitted. In this case, a predetermined wavelength region reflected by the photonic crystal is called a photonic bandgap.

4 is a diagram illustrating a Bragg relationship and transmission of light accordingly.

As shown in FIG. 4, the principle of light transmission in the above-described photonic crystal is similar to the manner in which X-rays are scattered by periodic atomic arrangements revealed by Bragg (the Bragg condition is sinθ = λ / 2d (where , θ is the angle of incidence, λ is the wavelength, and d is the distance between atoms. That is, when light meets the photonic crystal, light of a predetermined wavelength range is reflected from the surface of the particles 21 (first dielectric), and light of the remaining wavelength range passes through the medium 22 of the photonic crystal (second dielectric). Will pass by. At this time, the wavelength region of the reflected light that does not pass through the photonic crystal is called a photonic bandgap.                         

The reflection of light in such a photonic crystal is influenced by the structure of the particles 21 in the photonic crystal or the refractive index of the particles 21 and the medium 22 around the particles. In general, the photonic crystal has a wider optical bandgap as the difference in refractive index between the particles 21 and the medium 22 constituting the photonic crystal is larger. In other words, the area of light that can be controlled is widened.

5 is a spectrum showing the light transmittance of the opal.

The opal can be artificially produced by paying attention to the crystal structure of the opal. In this case, the artificial opal single-scatters spherical SiO ₂ molecules to form the SiO ₂ molecules with regularity to form a crystal structure.

At this time, when the region except for SiO ₂ molecules in the crystal structure of the artificial opal is empty (the empty region is filled with air (air, n = 1)) can be observed in the upper graph of FIG. The transmittance is lower than that of other regions in the wavelength region of about 450 nm.

In addition, the artificial opal crystal structure, respectively (1) was dissolved in methanol in a region other than the SiO ₂ molecules in the (methanol, n = 1.328), (2) Ethanol (ethanol, n = 1.361), (3) cyclohexane (cyclohexane, n = 1.427) and (4) when toluene (n = 1.497) is filled, the light in the wavelength region of about 480 nm to 500 nm is relatively in the other region as can be observed in order from the top of the lower graph of FIG. It can be seen that it has a low transmittance in comparison.

Here, when comparing the case in which the region other than the SiO ₂ molecules in the artificial opal is empty and the case in which something is filled, in particular, the optical bandgap region is relative when the region having the large refractive index is filled in the region except the SiO ₂ molecules in the artificial opal. It can be seen that a wider dip and a larger dip occur in the optical bandgap region in the graph of FIG.

As such, the wavelength range having a relatively low transmittance is the wavelength range in which the artificial opal is reflected.

6 is a view showing a photonic crystal structure composed of colloidal particles.

As shown in FIG. 6, the photonic crystal structure of the colloid is artificially formed such that the particles of the colloid are regularly spaced apart from each other.

Colloids are systems in which spherical solid or liquid particles ranging in size from tens of nanometers to hundreds of micrometers are dispersed in an unmixed solvent. Milk, which we often drink, is also a colloidal solution in which components such as proteins are dispersed in the form of particles. At this time, the particles are stabilized without being entangled with each other by the electrostatic repulsive force or the polymer on the surface of the particles and are disorderly moving by the Brownian motion.

The photonic crystal structure of the colloid is formed through a self-arrangement in which the arrangement between particles gradually changes from a disordered arrangement to a regular crystal structure as the concentration of particles in the colloid increases.

For example, colloids may form photonic crystal structures by collapsing colloidal solutions by gravity, or placing the substrate vertically on a substrate surface by capillary force, and then removing moisture or There is a method of applying a photo-resist onto a photoresist, exposing and developing the photoresist to remove a predetermined region thereof, filling a colloid in the removed region, and evaporating moisture.

Here, reference numeral 21 denotes a colloidal crystal, and reference numeral 22 is a state in which a separate substance is not filled in the photonic crystal structure immediately after colloidal crystallization with air. In addition, the colloidal crystal 21 and the air 22 serve as first and second dielectrics forming a photonic crystal structure, respectively. In this case, the portion filled with the air 22 may be filled by replacing various aqueous solutions.

However, the conventional liquid crystal display device as described above has the following problems.

Since a conventional liquid crystal display uses a color filter including a dye, the color filter of the color absorbs light of the remaining wavelengths except for light of a color to be transmitted among the light emitted from the backlight. Therefore, only about 1/3 of the luminance is used compared to the original luminance of the backlight. Due to this problem of color filters including dyes, research has been made on color filters of another material which has improved color purity. One such effort is the study of photonic crystals.

The present invention has been made to solve the above problems, and provides a color filter driven by an electron pump method for each pixel using a light crystal having a predetermined reflection characteristic for each wavelength, and a liquid crystal display device using the same. There is a purpose.

In order to achieve the above object, a liquid crystal display of the present invention includes a first and a second substrate facing each other, a plurality of holes formed spaced apart from each other in the first substrate, and a plurality of electrodes formed on a surface of each hole. And a liquid crystal formed between the first and second substrates and a photo crystal formed in the hole in contact with each electrode and reflecting light having a predetermined wavelength when a voltage is applied to the electrode.

The photonic crystal has a crystal arrangement such that a plurality of particles are regularly arranged inside the hole to form a cavity between the particles.

Particles of the photonic crystal is a material having a refractive index different from that of the liquid crystal.

When a voltage is applied to the electrode, the liquid crystal fills the cavity between the photonic crystal particles.

The photonic crystal is composed of first, second, and third photonic crystals that reflect light of red (R), green (G), and blue (B), respectively, when voltage is applied to the electrodes in contact with each other.

Voltages are selectively or together applied to the respective electrodes in contact with the first, second and third photonic crystals.

An electrical field is formed between the electrode and the liquid crystal when a voltage is applied to the electrode.

The second substrate further includes a gate line and a data line vertically crossing each other and defining a pixel area, a thin film transistor formed between the gate line and the data line, and a pixel electrode formed in the pixel area.                     

The gate line and the data lines correspond to an area between the hole and the hole.

The hole is formed in a portion corresponding to the pixel area.

A common electrode is further formed on the front surface of the first substrate to be electrically connected to the plurality of electrodes.

The plurality of electrodes are electrically connected to each other to serve as a common electrode.

A black matrix layer is further formed between the holes and the holes of the first substrate.

The plurality of electrodes is a transparent conductive metal.

In addition, the liquid crystal display of the present invention for achieving the same object, the first and second substrates facing each other, the gate line and the data line perpendicularly cross each other on the first substrate to define a pixel region, and A protective film formed on the first substrate by having a hole in a portion corresponding to the pixel region, a pixel electrode formed on a surface inside the hole, and formed at an intersection of the gate line and the data line, And a thin film transistor to apply the signal of the data line to the pixel electrode, a photo crystal formed inside the hole, a common electrode formed on an upper surface of the second substrate, and a liquid crystal formed between the first and second substrates. There is another feature to be done.

The photonic crystal has a crystal array in which a plurality of particles are regularly arranged inside the hole to form a cavity between the particles.

It is a material having a refractive index different from the particles of the photonic crystal and the liquid crystal.

When a voltage is applied to the pixel electrode, the liquid crystal fills the cavity between the photonic crystal particles.

An electrical field is formed between the electrode and the liquid crystal when a voltage is applied to the electrode.

The photonic crystal is composed of first, second and third photonic crystals that reflect red (R), green (G), and blue (B) light, respectively, when voltage is applied to adjacent pixel electrodes.

The protective film is a transparent insulating film.

The pixel electrode is a transparent conductive metal.

The color filter of the present invention for achieving the same object is a liquid crystal, an electrode corresponding to the liquid crystal is opened, an electrode whose open end is immersed in the liquid crystal and formed to a predetermined height above the liquid crystal, and the liquid crystal and the gap inside the electrode It is formed to have a, it is characterized by including a photonic crystal that reflects light of a predetermined wavelength when a voltage is applied to the electrode.

The photonic crystal is formed such that a plurality of particles are spaced at equal intervals and have cavities therebetween.

Upon application of a voltage to the electrode, the liquid crystal fills the cavity of the photonic crystal.

The size of the particles of the photonic crystal and the spacing between the particles are adjusted to adjust the wavelength region of the property reflected when the voltage is applied to the electrode.

Hereinafter, a color filter and a liquid crystal display using the same will be described in detail with reference to the accompanying drawings.

7A and 7B are diagrams showing operations of the off state and the on state of the electronic pump.

In the present invention, an electropump, which forms a color filter layer of a liquid crystal display, has an end portion of an electrode 60 having a cavity 50 therein as shown in FIG. 7A. Some are done to get in.

The electro-pump is initially in an off state without a voltage applied to the electrode 60 as shown in FIG. 7A. However, as shown in FIG. 7B, the electropump is provided with a voltage to the electrode 60. When applied to apply an electric field between the liquid crystal 40 and the electrode 60, the electric potential difference between the liquid crystal 40 and the electrode 60 and the inside of the electrode 60 Due to the surface energy change in the cavity of the liquid crystal 40 is introduced into the cavity 50 and rises.

Here, the electrode 60 of the electronic pump has a shape of a tube in which a portion corresponding to the liquid crystal 40 is open.

By using the principle of the electron pump, a photonic crystal structure (see FIGS. 8 and 9) having a regular particle arrangement and interparticle cavities is formed at a predetermined height inside the electrode 60, and this is used as a color filter. It can be applied.

In this case, when operating as a color filter, a voltage must be applied to the electrode 60, and at this time, the liquid crystal 40 fills the cavity between the particles inside the photonic crystal structure, whereby the liquid crystal 40 and the photonic crystal The difference in refractive index between the particles in the structure may allow light of a predetermined wavelength to be reflected.

By applying a voltage to the electrode 60 at all times, it can be used like a general color filter, and by applying a voltage to the electrode 60 selectively, it can also be used as a color filter with a switching function.

In this case, by adjusting the size of the particles and the spacing between the particles, it is possible to selectively change the range of the wavelength where the reflection is made. In the same principle, R (red), G (green), and B (blue) The corresponding color filter can be formed.

Hereinafter, various embodiments of a liquid crystal display in which a color filter is formed using a photonic crystal structure will be described.

First Embodiment

8 is a schematic diagram illustrating a liquid crystal display according to a first exemplary embodiment of the present invention.

As shown in FIG. 8, the liquid crystal display according to the first exemplary embodiment of the present invention includes a plurality of first and second substrates 110 and 100, which are opposed to each other, and are spaced apart from each other in the first substrate 110. A hole 121, a plurality of electrodes 111, 112, and 113 formed on a surface of each of the plurality of holes 121, and a plurality of electrodes 111, 112, and 113. When applied, the first, second, and third photonic crystals 131, 132, and 133 reflecting light having a predetermined wavelength and a liquid crystal 120 filled between the first and second substrates 110 and 100. It is done by

Here, the hole 121 on the first substrate 110 may be formed by removing a predetermined portion to a predetermined depth through an etching process. The hole may be deposited on the first substrate 110 to have a predetermined thickness, and an etching process may be performed on a predetermined portion to expose the first substrate 110 at a predetermined portion, thereby obtaining the same structure. have.                     

The electrodes 111, 112, and 113 having a predetermined thickness are formed in the plurality of holes 121 formed in the first substrate 110 of the present invention. Therefore, the hole 121 is formed while maintaining the step with the surface of the first substrate 110 as it is.

The photonic crystals formed on the plurality of electrodes 111, 112, and 113, respectively, are red (R), green (G), and blue ( It consists of the 1st, 2nd, 3rd photonic crystals 131, 132, and 133 which reflect the light of B).

The first, second, and third photonic crystals 131, 132, and 133, like the general color filters, have first and second reflections of red, green, and blue light. An array of the third photonic crystals 131, 132, 133 is regularly formed in contact with the respective electrodes 111, 112, 113.

Here, the first photonic crystal 131 is formed at a predetermined height (smaller than the height of the electrode 111) from the lower surface of the electrode 111, and the first cavity 114 and the first particles ( 115 are alternately arranged.

These particles 115 are arranged such that the spacing between the particles is the same. In the method of forming the particles 115, the colloidal solution is precipitated by gravity to have a regular particle arrangement, or after filling the colloidal particles with a template, the colloidal particles are removed to have an inverted shape. There is a method of forming a particle array, or removing a predetermined portion after applying a photoresist, and filling the removed portion with particles to form the particle.                     

In this case, each particle is formed to be spaced at equal intervals, and has the shape of spheres or crystals having a size of several hundred nanometers (100-990 nm).

When the voltage is applied to the electrode 111, the liquid crystal 120 positioned below the electrode 111 fills the inside of the cavity 114 by the same principle as described above.

Meanwhile, the second photonic crystal 132 is formed at a predetermined height (smaller than the height of the electrode 112) from the lower surface of the electrode 112, and the second cavity 117 and the first particles are formed. 116 are alternately arranged, and the third photonic crystal 133 is formed at a predetermined height (smaller than the height of the electrode 113) from the lower surface of the electrode 113, and is formed in the third cavity. (118, cavity) and the third particles 119 are alternately arranged, and have a structure similar to that of the first photonic crystal 131. However, each of the particles 115, 116, and 119 of the first photonic crystal 131, the second photonic crystal 132, and the third photonic crystal 133 has a different refractive index difference from that of the liquid crystal. When the first, second, and third cavities 114, 117, and 118 are filled, only the red, green, and blue light are reflected, and the light in the remaining areas is transmitted.

A voltage is selectively applied to each of the electrodes 111, 112, and 113 in contact with the first, second, and third photonic crystals 131, 132, and 133, or at the same time.

As such, when a voltage is applied to each of the electrodes 111, 112, and 113, the liquid crystal 120 below the electrodes 111, 112, and 113 enters the electrode to which the voltage is applied, and thus the photonic crystals 131, 132, and 133. Fill cavities 114, 117, and 118.                     

As such, when a voltage is applied to the electrodes 111, 112, and 113, an electric field is formed between the electrodes 111, 112, and 113 and the liquid crystal 120.

The particles 115, 116, and 119 of the first, second, and third photonic crystals 131, 132, and 133 are materials having different refractive indices from those of the liquid crystal 120.

Here, the electrodes 111, 112, 113 and the first, second, and third photonic crystals 131, 132, and 133 formed in the electrodes 111, 112, and 113 function as color filter layers. In this case, the electrodes 111, 112, and 113 and the first to third photonic crystals 131, 132, and 133 to which the present invention is applied may transmit external light for each wavelength region without loss. Therefore, the display can be performed without requiring a separate light source such as a backlight unit.

8 is a liquid crystal display device driven in a twisted nematic (TN) mode.

The first substrate 110 of the liquid crystal display device functions as a color filter substrate, and the second substrate 100 functions as a thin film transistor array substrate.

A gate line (not shown) and a data line (not shown) intersecting each other perpendicularly to each other on the second substrate 100 to define a pixel region, a thin film transistor (not shown) formed between the gate line and the data line; A pixel electrode (not shown) formed in the pixel area is formed.

The gate line and the data lines are formed to correspond to an area between the hole 121 and the hole 121. This is to prevent light leakage that may occur in an area between the hole 121 and the hole 121.                     

In order to prevent light leakage, a black matrix layer (not shown) may be further formed on the rear surface or the upper surface of the first substrate 110 to correspond to a region between the hole 121 and the hole 121.

The electrodes 111, 112, and 113 are formed to correspond to the pixel area.

The common electrode 135 is further formed in an area excluding the hole 121 on the first substrate 110 to form a vertical electric field between the second substrate 100 when the liquid crystal display is driven. Here, the electrodes 111, 112, 113 and the common electrode 135 are in contact with each other and electrically connected.

The plurality of electrodes 111, 112, and 113 and the common electrode 135 are made of a transparent conductive metal.

In the liquid crystal display of the first embodiment, the second substrate 100 serves as a display surface, and external light incident from the rear surface of the second substrate 100 is determined by the first, second, and third light crystals. In principle, at 131, 132, and 133, light is selectively reflected by red (R), green (G), and blue (B) light to emit light.

Second Embodiment

9 is a schematic diagram illustrating a liquid crystal display according to a second exemplary embodiment of the present invention.

FIG. 9 illustrates a liquid crystal display according to the second exemplary embodiment in which the common electrode 135 and the electrodes 111, 112, and 113 of the first exemplary embodiment are formed at the same time, and include a plurality of spaced apart holes 121. The transparent electrode 140 is deposited on the entire surface of the first substrate 110.

In this case, the first, second, and third photonic crystals 131, 132, and 133 are regularly formed in the hole 121 in which the transparent electrode 140 is deposited. Since a voltage is applied to the transparent electrode 140 regardless of an area, when the voltage is applied to the transparent electrode 140, each cavity 114 of the first, second, and third photonic crystals 131, 132, and 133 is applied. , 117 and 118 are simultaneously filled with liquid crystals, and R, G, and B light is transmitted.

In this case, selectively displaying light of a predetermined color may be achieved through selective driving of gate lines and data lines formed on the second substrate 100.

Similarly, in the liquid crystal display of the second embodiment, the second substrate 100 serves as a display surface, and external light incident from the rear surface of the second substrate 100 is determined by the first, second, and third light crystals. In principle, at 131, 132, and 133, light is selectively reflected by red (R), green (G), and blue (B) light to emit light.

10A and 10B are diagrams illustrating on / off driving for each pixel of the liquid crystal display of the present invention.

As shown in FIG. 10A, the red color filter unit of the liquid crystal display device of the present invention includes an electrode 111 in the hole 121 of the first substrate 110, and the electrode 111 has a first light at a predetermined height from below. Crystal 131 is formed. The first photonic crystal 131 is formed such that the first cavity 114 and the first particles 115 have a periodic arrangement structure. In fact, only the first particles 115 may be formed of a physicochemical (colloidal solution) solution. By using a precipitation method, a reverse phase structure formation method using a mold, a lithography method using a photoresist, or the like).

As shown in FIG. 10A, in the state where no voltage is applied to the electrode 111 of the red color filter unit, the liquid crystal 120 corresponding to the electrode 111 maintains the same height as the surface of the first substrate 110. have. In this case, since the first cavity 114 in the first photonic crystal 131 is in an empty state, the red color filter part should be arranged to have two or more different refractive indices. Does not transmit any light.

Like the red color filter unit, the green color filter unit and the blue color filter unit do not transmit any light when no voltage is applied to the electrode adjacent to the photonic crystal.

As shown in FIG. 10B, when a voltage is applied to the electrode 111, an electrical field is formed between the electrode 111 and the liquid crystal 120, and thus, the electrical field between the liquid crystal 120 and the electrode 111 is formed. Due to a potential difference and a change in surface energy in the first cavity 114 inside the electrode 111, the liquid crystal 120 flows into the hole 121 and rises to the first cavity 114. Will fill the interior.

In this case, due to the difference in refractive index between the liquid crystal 120 and the first particle 115, only red light among the external light incident on the rear surface of the second substrate 100 may cause the first photonic crystal 131 to be separated. Manna is reflected to the outside of the first substrate 110.

The green color filter part and the blue color filter part are also driven on the same principle as the red color filter part described above.

As described above, the color filter unit (consisting of the electrode and the photonic crystal) of the present invention exhibits a black state before applying voltage to the electrode, and implements light of color according to the photonic crystal after applying the voltage.

Third embodiment

FIG. 11 is a schematic diagram illustrating a liquid crystal display according to a third exemplary embodiment of the present invention, and FIG. 12 is a circuit diagram of FIG. 11.

11 and 12, the liquid crystal display according to the third exemplary embodiment of the present invention vertically crosses the first and second substrates 200 and 210 facing each other and perpendicularly to each other on the first substrate 200. And a gate line (see 151 of FIG. 12, not shown in FIG. 11 and included in the first substrate 200) and a data line (see 152 of FIG. 12, not shown in FIG. 11, and a first substrate) defining a pixel region. (Included in the inside of the cell 200), a protective layer 225 having a hole in a portion corresponding to the pixel area, and having a predetermined thickness on the data line 152, and first and second layers formed on a surface of the hole. First, second and third photonic crystals formed in a hole in which the second and third pixel electrodes 211, 212 and 213 and the first, second and third pixel electrodes 211, 212 and 213 are formed. 214, 215, and 216, a common electrode 215 formed on an upper surface of the second substrate 210, and a liquid crystal 220 formed between the first and second substrates 200 and 210. Is done.

The first, second, and third photonic crystals 214, 215, and 216 are formed in a crystal array in which a plurality of particles are regularly spaced inside the hole, and have a refractive index different from that of the liquid crystal 220. admit.

The first, second, and third photonic crystals 214, 215, and 216 are respectively red (R) when voltage is applied to the first, second, and third pixel electrodes 211, 212, and 213, which are in contact with each other. And first, second and third photonic crystals having a property of reflecting light of green (G) and blue (B). The first, second, and third photonic crystals may be formed by regularly spaced particles having different sizes from the inside of the first, second, and third pixel electrodes 214, 215, and 216, respectively. The spaces between the particles form a cavity.

A voltage is selectively applied to each of the first, second, and third pixel electrodes 211, 212, 213 in contact with the first, second, and third photonic crystals 214, 215, and 216.

When voltage is applied to the first to third pixel electrodes 211, 212 and 213, the liquid crystal 220 below the pixel electrode fills the cavity in the photonic crystal inside the pixel electrode. In this case, an electric field is formed between the corresponding pixel electrode and the liquid crystal.

The data line 152 is electrically connected to the pixel electrode. To this end, a thin film transistor TFT is formed at a portion where the gate line 151 and the data line 152 cross each other, and the thin film transistor TFT is turned on according to a scan signal applied to the gate line 151. on / off to transmit the data signal of the data line 152 to the corresponding pixel electrode.

Here, the protective film 225 formed on the first substrate 200 is a transparent insulating film. The first to third pixel electrodes 211, 212, and 213 are transparent conductive metals.

In the liquid crystal display according to the third exemplary embodiment, pixel electrodes 211, 212, and 213 formed for each pixel are formed in a hole in the passivation layer, and light crystals of a corresponding color are formed in the pixel electrodes 211, 212, and 213. By forming (214, 215, 216), the display function according to the pixel voltage filling of the pixel electrode and the color filter function of the corresponding color can be performed simultaneously.

In this case, a signal is applied to the pixel electrodes 211, 212, and 213 through corresponding data lines 152 electrically connected to each other. In this case, the pixel electrodes 211, 212, and 213 are different from the data lines 152, unlike the electrodes 111, 112, and 113 of the first and second embodiments, which only perform on / off driving for each pixel. Since the gray level voltage may be applied, various gray colors may be displayed.

The color filter part according to the third exemplary embodiment of the present invention includes the pixel electrodes 211, 212, and 213 and the photonic crystals 214, 215, and 216.

In the liquid crystal display of the third exemplary embodiment, the second substrate 210 serves as a display surface, and external light incident from the rear surface of the second substrate 210 receives the first, second, and third light crystals ( In 214, 215, and 216, red (R), green (G), and blue (B) light is selectively reflected to emit light.

Meanwhile, as the flat panel display device is gradually enlarged in size, competition for high brightness, low cost, light weight, and slimness is accelerating.

The liquid crystal display of the present invention has described a method of omitting a back light unit in order to secure an independent price competitiveness, and simultaneously forming and driving a color filter unit with a new concept of photonic crystal to have high brightness performance.

According to an embodiment of the present invention, a color filter part includes an electrode or a pixel electrode and a photonic crystal formed inside the electrode or the pixel electrode, and when a voltage is applied to the electrode or the pixel electrode, a liquid crystal is filled in the photonic crystal, and a liquid crystal and the photonic crystal The difference in refractive index between the particles and the liquid crystal is maximized to form a photo bandgap to selectively filter the red (R), green (G), and blue (B) wavelengths, respectively.

The color filter of the present invention and the liquid crystal display using the same have the following effects.

First, by using a light crystal having a light reflection characteristic selective to a predetermined wavelength in the color filter instead of a color filter using a conventional dye that absorbs the light of the remaining colors except for the light of the predetermined color to filter, the light efficiency is improved. It is possible to increase the purity of light in display.

Second, the light efficiency is increased, so that display can be performed using only external light without requiring a backlight unit.

Third, by adjusting the size and size of the particles constituting the inside of the photonic crystal, it is possible to increase the optical bandgap by increasing the refractive index difference with the liquid crystal, thereby widening the color adjustment range.

Fourth, the filling function of the pixel voltage and the function of the color filter can be simultaneously performed using only the electrode and the photonic crystal, thereby simplifying the structure of the liquid crystal display device.

Claims (26)

First and second substrates facing each other; A plurality of holes formed spaced apart from each other in the first substrate; A plurality of electrodes formed on the surface of each hole; A light crystal formed in a hole in contact with each electrode and reflecting light having a predetermined wavelength when a voltage is applied to the electrode; And And a liquid crystal formed between the first and second substrates. The method of claim 1, And the photonic crystal is arranged in a crystal array such that a plurality of particles are regularly arranged inside the hole to form a cavity between the particles. The method of claim 2, Particles of the photonic crystal is a liquid crystal display, characterized in that the material having a refractive index different from the liquid crystal. The method of claim 2, And the liquid crystal fills the cavity between the photonic crystal particles when a voltage is applied to the electrode. The method of claim 1, Wherein the photonic crystal is composed of first, second and third photonic crystals that reflect red, green, and blue light, respectively, when a voltage is applied to the electrodes in contact with each other; Device. The method of claim 5, And a voltage is applied to each of the electrodes in contact with the first, second, and third photonic crystals selectively or together. The method of claim 5, And an electrical field is formed between the electrode and the liquid crystal when a voltage is applied to the electrode. The method of claim 1, A gate line and a data line crossing the second substrate perpendicularly to each other and defining a pixel area; A thin film transistor formed between the gate line and the data line; And a pixel electrode formed in the pixel region. The method of claim 8, And the gate line and the data lines correspond to an area between the hole and the hole. The method of claim 8, And the hole is formed in a portion corresponding to the pixel area. The method of claim 1, And a common electrode further formed on an entire surface of the first substrate so as to be electrically connected to the plurality of electrodes. The method of claim 1, And the plurality of electrodes are electrically connected to each other to be used as a common electrode. The method of claim 1, And a black matrix layer is further formed between the hole of the first substrate and the hole. The method of claim 1, And the plurality of electrodes are transparent conductive metals. First and second substrates facing each other; A gate line and a data line vertically crossing each other on the first substrate and defining a pixel area; A passivation layer formed on the first substrate with a hole in a portion corresponding to the pixel region; A pixel electrode formed on a surface of the hole; A thin film transistor formed at an intersection of the gate line and the data line and applying a signal of the data line to the pixel electrode according to a signal of the gate line; A photonic crystal formed inside the hole; A common electrode formed on an entire upper surface of the second substrate; And And a liquid crystal formed between the first and second substrates. The method of claim 15, And the photonic crystal comprises a crystal array in which a plurality of particles are regularly arranged inside the hole to form a cavity between the particles. The method of claim 16, And a material having a refractive index different from the particles of the photonic crystal and the liquid crystal. The method of claim 18, And the liquid crystal fills the cavity between the photonic crystal particles when a voltage is applied to the pixel electrode. The method of claim 18, And an electrical field is formed between the electrode and the liquid crystal when a voltage is applied to the electrode. The method of claim 15, The photonic crystal is composed of first, second, and third photonic crystals that reflect red (R), green (G), and blue (B) light when voltage is applied to adjacent pixel electrodes, respectively. Display device. The method of claim 15, The protective film is a liquid crystal display device, characterized in that the transparent insulating film. The method of claim 15, The pixel electrode is a transparent conductive metal. Liquid crystals; An electrode corresponding to the liquid crystal is opened, and an open end is immersed in the liquid crystal and formed at a predetermined height on the liquid crystal; And The color filter is formed to have a gap with the liquid crystal inside the electrode, and comprises a light crystal that reflects light of a predetermined wavelength when a voltage is applied to the electrode. The method of claim 23, wherein Wherein the photonic crystal is formed such that a plurality of particles are spaced at equal intervals and have a cavity between the particles. The method of claim 24, And the liquid crystal fills the cavity of the photonic crystal when voltage is applied to the electrode. The method of claim 24, And adjusting the size of the particles of the photonic crystal and the spacing between the particles to adjust the wavelength range of the characteristic reflected when the voltage is applied to the electrode.

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