KR101136177B1 - Method for manufacturing optical filter and liquid crystal display device - Google Patents

Abstract

The present invention discloses an optical filter manufacturing method and a liquid crystal display device capable of displaying a clear image by adjusting the contrast ratio in the liquid crystal display device. The disclosed optical filter manufacturing method includes the steps of forming a photosensitive film on a wafer; Manufacturing a mold on which the master is formed on the wafer after exposing using a mask on the photosensitive film; Forming a molding on the mold to form a first substrate of the optical filter; Bonding a second substrate of the optical filter to the first substrate, injecting conductive droplets whose movement is controlled by an electric field between the first substrate and the second substrate, and forming an electrode to apply an electric field to the conductive droplets; step; Characterized in that it comprises a.

The present invention has the effect of allowing the contrast ratio to be adjusted for each pixel unit.

LCD, Contrast, Droplet, Transmittance, PMDS

Description

Optical filter manufacturing method and liquid crystal display device {METHOD FOR MANUFACTURING OPTICAL FILTER AND LIQUID CRYSTAL DISPLAY DEVICE}

1 is a view schematically showing the structure of a liquid crystal display according to the prior art.

2 is a view for explaining the operation of adjusting the contrast ratio of the liquid crystal display according to the prior art.

3 is a view showing a state in which the thickness of the liquid metal used in the optical filter of the present invention is changed by the surface tension generated by the electric field.

Figure 4a is a view for explaining how the liquid metal changes the contact angle in accordance with the adjustment of the electric field.

Figure 4b is a view showing how the light transmittance is changed as the thickness of the liquid metal in accordance with the control of the electric field.

5 is a view showing a structure of an optical filter attached to a color filter of a liquid crystal display according to the present invention.

6 is a view for explaining the structure and operation principle of each pixel unit of the optical filter according to the present invention.

7A to 7F illustrate a manufacturing process of an optical filter according to the present invention.

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

100: droplet 110a: negative electrode

110b: positive electrode 200: optical filter

200a: first substrate 200b: second substrate

The present invention relates to an optical filter manufacturing method and a liquid crystal display device that can display a clear image by adjusting the contrast ratio (contrast ratio) in the liquid crystal display device.

Recently, liquid crystal display devices, which are rapidly developing, are being manufactured with smaller, lighter weight and more powerful products. Cathode ray tube (CRT), which is widely used in information display devices, has many advantages in terms of performance and price, but has many disadvantages in terms of miniaturization or portability.

On the other hand, liquid crystal displays have been attracting attention as an alternative means of overcoming the shortcomings of CRTs because they have advantages such as miniaturization, light weight, and low power consumption. Currently, almost all information processing devices that require display devices are required. The situation is attached to.

The liquid crystal display device includes a manufacturing process of a color filter substrate and an array substrate, including a process of forming a liquid crystal cell forming a pixel unit, a formation and rubbing process of an alignment layer for liquid crystal alignment, and a color filter substrate and an array substrate. It is completed through a number of processes, such as the bonding process of, and the process of injecting and encapsulating the liquid crystal between the bonded color filter substrate and the array substrate.

1 is a view schematically showing the structure of a liquid crystal display according to the prior art.

As shown in FIG. 1, the structure of a conventional liquid crystal display device is largely divided into a color filter substrate, an array substrate, and a liquid crystal layer 17. The color filter substrate is formed on a first substrate 20 made of a transparent insulating substrate. A black matrix 13 is formed using chromium, and R, G, and B color filter layers 15 are formed in an inner space where the black matrix 13 is formed, and the R, G, and B color filter layers 15 are formed. ) A common electrode 11 for applying a common voltage is disposed.

The array substrate corresponding to the color filter substrate defines a unit pixel region by vertically crossing a plurality of gate lines 1 and data lines 3 on a second substrate 10 formed of a transparent insulating substrate. The TFT 5 and the pixel electrode 9 which perform a switching operation on the unit pixel region are arranged.

In the liquid crystal display having the structure described above, the liquid crystal molecules of the liquid crystal layer 17 are rotated by an electric field generated from the pixel electrode 9 of the array substrate, thereby R, G, and B color filter layers 15 of the color filter substrate. Adjust the transmittance of the light passing through).

Thus, the light whose transmittance is controlled in the liquid crystal layer 17 passes through the R, G, and B color filter layers 15 to display an image.

As described above, in the case of a transmissive liquid crystal display device, a back light unit for generating a light source is disposed in the transmissive liquid crystal display device. The light source is divided into an edge method and a direct method according to the size of the liquid crystal display device.

In the edge method, a CCFL lamp is disposed on a side of a light guide plate for guiding light to induce light from the side to generate plane light. This method is applied to a liquid crystal display device having a relatively small size, and has good light uniformity, a long durability life, and is advantageous for thinning the liquid crystal display device.

On the other hand, the direct method is a method in which the size of the liquid crystal display device is used for 20 inches or more, a method of directing the light directly to the front of the LCD panel by arranging a plurality of lamps in a row.

Such a direct type is mainly used in a large screen liquid crystal display device requiring high luminance because the light utilization efficiency is higher than that of the edge type.

2 is a view for explaining a calculation process for adjusting the contrast ratio of a liquid crystal display according to the prior art.

As shown in (a) of FIG. 2, when it is determined that the image displayed on the liquid crystal display is not clear, that is, when it is determined that the contrast ratio (C / R) is not good, brightness adjustment is performed to improve this. Analyze for

Here, the contrast ratio C / R is defined as a value obtained by dividing the white luminance values of all pixels by the black luminance values of all pixels.

In order to obtain a clear image by adjusting the contrast ratio, the white luminance should have a higher luminance value and the black luminance should have a lower luminance value.

In particular, since the luminance value in the black state has a smaller value than the luminance value in the white state, it can be seen that the contrast ratio value is largely affected by the black luminance value.

Therefore, when an image with poor contrast is displayed on the liquid crystal display, luminance gray values of each pixel are calculated as shown in (b) to adjust an inverter for supplying power to the lamp.

Usually, the average value of luminance gray scale values corresponding to one frame is calculated and displayed as a histogram.

When the histogram value for each pixel is obtained as described above, a grayscale data stretch graph proportional to the distribution of the luminance grayscale histogram is obtained as shown in (c).

Then, as shown in (d), the current value of the inverter is controlled to the lowest luminance value or the highest luminance value through the analyzed histogram value.

That is, in the dark image, the current value applied to the lamp is lowered to have a darker brightness value, and in the bright image, the current value applied to the lamp is controlled to have a higher brightness value.

Then, as shown in (e), the dark portion of the displayed image has a darker luminance value, and the bright portion has a brighter luminance value, thereby obtaining a clear image.                         

However, in the liquid crystal display device as in the related art, it is difficult to control luminance in each pixel unit because a method of adjusting a current value applied to a lamp by obtaining a luminance gray value corresponding to each pixel in order to obtain a clear image.

That is, there is a problem that the luminance value can be adjusted only in the vertical unit where the lamps are arranged without adjusting the luminance value for each pixel.

In addition, the method of adjusting the current value applied from the inverter to the lamp to adjust the brightness causes a shortening of the lamp life. This is because, if high current is applied to the lamp in order to realize high brightness, the lamp life becomes shorter.

In addition, since the rated current values to be applied to the lamp are determined, there is a limit to the method of adjusting the luminance according to the current control.

The present invention provides an optical filter manufacturing method and a liquid crystal display device that can implement a sharper image by varying the contrast ratio in a desired pixel unit by an optical filter that can control the transmittance in each pixel unit. There is this.

In order to achieve the above object, an optical filter manufacturing method according to the present invention, forming a photosensitive film on the wafer; Manufacturing a mold on which the master is formed on the wafer after exposing using a mask on the photosensitive film; Forming a molding on the mold to form a first substrate of the optical filter; Bonding a second substrate of the optical filter to the first substrate, injecting conductive droplets whose movement is controlled by an electric field between the first substrate and the second substrate, and forming an electrode to apply an electric field to the conductive droplets; step; Characterized in that it comprises a.

In addition, to achieve the above object, the liquid crystal display device according to the present invention, the color filter substrate is formed; An array substrate on which pixel electrodes are formed; A liquid crystal layer interposed between the color filter substrate and the array substrate; And an optical filter attached to the color filter substrate or the array substrate to adjust the amount of light per unit pixel.

Here, the optical filter is characterized in that a plurality of filters corresponding to the unit pixels of the color filter substrate is formed in a grid form.

According to the present invention, by attaching an optical filter that can control the transmittance in each pixel unit to the color filter substrate, there is an advantage that the contrast ratio can be adjusted in each pixel unit in the liquid crystal display device.

In addition, the optical filter that can adjust the transmittance in each pixel unit can be used to vary the contrast ratio in the desired pixel unit to implement a clearer image.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a view showing the thickness of the conductive droplets used in the optical filter of the present invention is changed by the surface tension generated by the electric field, as shown, the droplets present on one side according to the electric field is seen to spread thinly Can be.

That is, it can be seen that an electric field is formed between the negative electrode and the positive electrode, and the droplet existing in the negative electrode is spreading in a thin thickness as the surface tension is formed in the electric field formation direction.

Since the detailed principle of FIG. 3 is described in detail in "SCIENCE Vol 283, 1999 p41", a detailed description thereof will be omitted.

4A is a view for explaining a state in which the contact angle changes according to the adjustment of the electric field of the conductive droplets.

As shown in (a) and (b) of FIG. 4A, when an electric field is applied to the conductive droplet, it can be seen that the contact angle between the liquid crystal and the surface where the droplet is located changes with the electric field. have.

As in (a), when the electric field is not applied to the conductive droplets, the contact angle between the droplets and the contact surface is somewhat large as in the shape of water droplets, but as in (b), when the electric field is applied to the conductive droplets, the droplets are electric fields. By spreading sideways, the contact angle between the droplet and the contact surface becomes small.

Therefore, the thickness of the droplet becomes thinner when an electric field is applied as in (b) than when an electric field is not applied as in (a).

The conductive droplets used above may use ITO, which is a transparent metal, and even when an opaque metal such as aluminum (Al) or silver (Ag) is used, the conductive droplets are transparent in the case of having a micro thickness. Metals can be used.

FIG. 4B is a view showing a state in which the light transmittance is changed as the thickness of the metal droplet is changed according to the adjustment of the electric field. As shown in (a), when the electric field is not applied to the conductive droplet, the light transmittance is small. Can be seen.

And when the electric field is applied (b) and (c) as the contact angle between the droplet and the contact surface is small it can be seen that the light transmittance gradually increases.

By applying an electric field to the conductive droplets as described above, an optical filter is manufactured on the principle of controlling the amount of light penetrating the droplets, and applied to the liquid crystal display device of the present invention, thereby reducing the amount of light passing through the R, G, and B color filters. I can regulate it.

5 is a diagram illustrating a structure of an optical filter attached to a color filter of a liquid crystal display according to the present invention.

As shown in FIG. 5, one unit pixel (RGB color filter) is formed by attaching the optical filter 200 according to the present invention on a color filter substrate on which R, G, and B color filters and a black matrix BM are formed. It is possible to adjust the amount of light transmitted from the.

However, although not described in detail herein, the optical filter 200 may be attached to the color filter substrate and the array substrate corresponding to the color filter substrate, thereby controlling the transmittance of light traveling from the backlight.

That is, to attach the optical filter 200 on the color filter substrate is to adjust the transmittance of the RGB mixed light source transmitted through the array substrate, the liquid crystal layer and the color filter layer, and to attach the optical filter 200 on the array substrate. It is to adjust the transmittance of the white light of the backlight light source, and then transmit the adjusted light through the liquid crystal layer and the color filter layer.

Therefore, the principle is the same whether the optical filter 200 is attached to the color filter substrate or the array substrate.

Therefore, even if the optical filter 200 according to the present invention is attached on the color filter substrate or on the array substrate, the luminance control per unit pixel can be the same.

Here, the optical filter 200 is divided into a plurality of unit filter regions corresponding to a plurality of unit pixels (RGB color filters) formed on the color filter substrate, and conductive droplets 100 are disposed in each filter region. have.

In addition, an electric field is applied to the conductive droplets 100 disposed on the optical filter 200 to adjust the amount of light passing through the RGB color filter.

That is, in the present invention, by attaching the optical filter 200 that can control the transmittance by the electric field to the liquid crystal display device in which the color filter substrate and the array substrate are bonded with the liquid crystal layer interposed therebetween, the unit pixel unit (unit RGB color filter) It is possible to adjust the brightness with.

Thus, in the prior art, although the brightness of the lamp disposed in the backlight is adjusted to increase the sharpness of the image, in the present invention, the amount of brightness can be adjusted for each pixel, so that the contrast ratio of the more precise image can be adjusted.

6 is a view for explaining the structure and operation principle of each pixel unit of the optical filter according to the present invention.                     

As shown in FIG. 6, (a) shows an optical filter 200 corresponding to a unit pixel (RGB color filter) formed on a color filter substrate, and (b) shows the structure of the optical filter 200. A cross-sectional view is shown for clarity.

First, in (a), the unit filter of the optical filter 200 has a structure corresponding to the unit pixel RGB of the color filter substrate, and the optical filter 200 is attached to the color filter substrate. The unit filter structure is 1: 1 matched with a unit pixel (RGB color filter) of the color filter substrate.

In the unit filter of the optical filter 200, the conductive droplet 100 is inserted below the B color filter, because when the liquid crystal panel is used in the upright position, the conductive droplet 100 is positioned under the B color filter by gravity. Because.

As described above, when the electric field is applied in the state in which the conductive droplet 100 is injected into the optical filter 200, the conductive droplet 100 is widened by receiving the surface tension in the electric field direction as shown in FIG. 5B.

At this time, the conductive droplet 100 is spread over the entire area of the optical filter 200 by applying a threshold voltage, and then the transmittance of the conductive droplet 100 is adjusted by adjusting the applied voltage intensity.

That is, when the electric field is applied as described above, the movement of the conductive droplets is generated, and when the electric field is increased, the amount of the conductive droplets moved accordingly increases, so that the thickness of the conductive droplets 100 spread over the optical filter 200. Will increase. Accordingly, the thickness of the conductive droplet 100 can be adjusted by adjusting the electric field, thereby controlling the amount of light transmitted.

As such, if the thickness of the droplet 100 is adjusted by the electric field applied to the conductive droplet 100, and the light transmittance is adjusted by the adjusted thickness, luminance may be adjusted in units of pixels.

Therefore, when the optical filter 200 according to the present invention is used in the liquid crystal display, the light transmittance of the unit pixels of the color filter substrate can be adjusted, thereby improving the contrast of the displayed image.

(b) illustrates the structure of the optical filter 200 according to the present invention, in which the transparent first substrate 200a and the second substrate 200b are bonded to each other with the droplet 100 interposed therebetween.

In addition, a predetermined gap is formed between a region where the droplet 100 is located and the first substrate 200a and the second substrate 200b so that the droplet 100 may move by an electric field. It is.

The first substrate 200a and the second substrate 200b may be made of a glass substrate, or may be made of a transparent material made of polydimethylsiloxane (PDMS).

The PDMS is a material used in nanotechnology, and the foreign material may be manufactured in the form of a mold having a negative shape when mixed with a hardener and sintered in an embossed mold having a specific shape. (FIG. 7A to FIG. 7A). See 7f)

The PDMS has properties such as transparency, permeability, surface energy, inertness, flexibility, lubricity, hydrophobicity and release property.                     

Due to such characteristics, in recent years, nano-patterns, like silicon, form micro-patterns and use them as substrates.

In addition, any one of the first substrate 200a or the second substrate 200b may use a glass substrate, and the other substrate may use PDMS.

A negative electrode 110a and a positive electrode 110b are formed between the first substrate 200a and the second substrate 200b of the optical filter 200, and the droplet 100 is the negative electrode 110a. ) And the positive electrode 110b, respectively.

The power source 250 is connected to the negative electrode 110a and the positive electrode 110b. When an electric field is generated between the negative electrode 110a and the positive electrode 110b, the droplet 100 at the position of the negative electrode 110a is formed. The electric field is moved between the first substrate 200a and the second substrate 200b according to the strength of the electric field.

The droplet 100 disposed between the first substrate 200a and the second substrate 200b of the optical filter 200 moves in a manner similar to that illustrated in FIG. 3.

In this way, by adjusting the thickness of the droplet 100 by the electric field, it is possible to adjust the light transmittance passing through the optical filter 200.

The method of manufacturing the optical filter 200 using the transparent material as described above is as follows.

7A to 7F are views illustrating a manufacturing process of the optical filter according to the present invention.

In order to fabricate an optical filter in which substrates made of transparent materials are bonded, first, a mold must be manufactured. There are various methods of casting, injection, and embossing.

As shown in FIG. 7A, first, a photosensitive film 310 called SU-8 is formed on a silicon wafer 300 to fabricate a mold.

Since SU-8 is a photosensitive material capable of selectively irradiating exposure using a mask to form a desired pattern, such as photoacryl, there is no need to further develop and etch after exposure.

When the photosensitive film 310 is formed on the silicon wafer 300 as described above, as shown in FIG. 7B, an exposure process is performed using the photomask 400.

As such, when the photoresist layer 310 is patterned by the photomask 400, a mold pattern 310a is formed to form a mold including a wafer 300 and a mold pattern 310a, as shown in FIG. 7C. A master is formed.

When the mold in which the mold pattern 310a is formed on the silicon wafer 300 is completed as described above, as illustrated in FIGS. 7D and 7E, a mold made of a substrate material of an optical filter on the silicon wafer 300 is formed. Is formed to cast the first substrate 320.

The mold material of which the first substrate 320 is a transparent material may use a transparent insulating material such as PDMS material or glass material.

As described above, in order to form the substrate of the optical filter, the first substrate 320 of the optical filter having the desired pattern is manufactured by casting the substrate material into a mold including the master 310a and the silicon wafer 300.                     

When the first substrate 320 is completed as described above, as shown in FIG. 7F, the optical filter is completed by molding the second substrate 340 made of a transparent insulating material.

The method of molding the second substrate 340 and the first substrate 320 may include microcontact printing, replica molding, microtransfer molding, micromolding using capillaries, and the like.

As shown in FIG. 6 in the molding process as described above, an electrode forming process for forming droplets and an electric field is performed together.

Therefore, in the present invention, the transparent optical filter is manufactured in the manufacturing process used in nanotechnology, and then, by applying an electric field to the droplet to adjust the light transmittance, the liquid crystal display device can adjust the luminance in pixel units (RGB) There is an advantage to that.

As described in detail above, the present invention has an effect that can be adjusted in each pixel unit when the contrast ratio is adjusted by attaching an optical filter that can control the transmittance in each pixel unit to the color filter substrate.

In addition, there is an advantage that a sharper image can be realized by varying the contrast ratio by an optical filter that can control the transmittance in each pixel unit.

The present invention is not limited to the above-described embodiments, and various changes can be made by those skilled in the art without departing from the gist of the present invention as claimed in the following claims.

Claims (12)

Forming a photoresist film on the wafer; Manufacturing a mold on which the master is formed on the wafer after exposing using a mask on the photosensitive film; Forming a molding on the mold to form a first substrate of the optical filter; Bonding a second substrate of the optical filter to the first substrate, injecting conductive droplets whose movement is controlled by an electric field between the first substrate and the second substrate, and forming an electrode to apply an electric field to the conductive droplets; step; Optical filter manufacturing method comprising a. The method of claim 1, The photosensitive film is an optical filter manufacturing method, characterized in that the SU-8. The method of claim 1, The wafer is an optical filter manufacturing method, characterized in that the silicon. The method of claim 1, The molding is an optical filter manufacturing method, characterized in that formed of a transparent insulating material. The method of claim 1, The second substrate is bonded to the first substrate is an optical filter manufacturing method, characterized in that formed of a transparent insulating material. A color filter substrate on which color filters are formed; An array substrate on which pixel electrodes are formed; A liquid crystal layer interposed between the color filter substrate and the array substrate; And An optical filter attached to the color filter substrate or the array substrate and controlling an amount of light per unit pixel; In the optical filter, a plurality of filters corresponding to unit pixels of the color filter substrate are formed in a lattice form. And liquid crystals controlled by an electric field are disposed in the filters formed in the optical filter. delete delete The method of claim 6, The amount of transmitted light can be adjusted in units of pixel units of the liquid crystal display by applying an electric field to the droplets disposed on the filters of the optical filter, thereby adjusting the amount of light passing through the filter. A color filter substrate on which color filters are formed; An array substrate on which pixel electrodes are formed; A liquid crystal layer interposed between the color filter substrate and the array substrate; And An optical filter attached to the color filter substrate or the array substrate to adjust the amount of light per unit pixel; And the optical filter comprises droplets controlled by an electric field. delete delete

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