KR101545922B1 - Electrophoretic Display Device and Method for fabricating the same - Google Patents

Abstract

The present invention relates to an electrophoretic display device and a method of manufacturing the same, and a method of manufacturing an electrophoretic display device according to the present invention is a method of manufacturing an electrophoretic display device including a gate electrode, an active layer and a source / Forming a transistor; Forming a protective film on a lower substrate including the thin film transistor; Forming a contact hole on the protective film to expose a drain electrode of the thin film transistor; Forming a pixel electrode electrically connected to the drain electrode through the contact hole on the protective film; Forming a nanowire conductive film on the protective film including the pixel electrode; Disposing an electrophoretic film on the nanowire conductive film; And disposing an upper substrate on the electrophoretic film.

An electrophoretic film (epd), a reflective luminance, a nanowire conductive film, a pixel electrode

Description

[0001] Electrophoretic Display Device and Method for Fabricating the Same [

The present invention relates to a display device, and more particularly, to an electrophoretic display device (EPD) capable of coating a nanowire conductive layer on a lower substrate or a reflective plate to apply the same to a display device having a high reflection luminance, And a manufacturing method thereof.

In general, an electrophoretic display device is an image display device using a phenomenon in which a pair of electrodes to which a voltage is applied is immersed in a colloid solution so that colloidal particles move to either one of the polarities. As a result, a wide viewing angle, Easy and low power consumption, it is expected that all kinds of electric paper will be popular.

Such an electrophoretic display device has a structure in which an electrophoretic film is interposed between two substrates, and at least one of the two substrates must be transparent so that an image can be displayed in a reflective mode.

When a voltage is applied to the pixel electrode on the lower substrate among the two substrates, the charged particles in the electrophoretic film move toward or away from the pixel electrode, thereby forming a viewing sheet You can see the image through.

A typical electrophoretic display device has a structure in which an upper substrate and a lower substrate on which pixel electrodes are formed are opposed to each other and an electrophoretic film is interposed between the two substrates.

Here, the electrophoretic film is made of a solvent containing charged pigment particles, and is made into a microcapsule by a coacervation method. The microcapsule is coated on a binder And then coating or laminating the base film.

Here, the pigment particles may be colored in different colors. B (Black) and W (White) pigments may be added to render an image. The solvent and the binder may be formed of a transparent material, do.

Since the electrophoretic film is enclosed by the microcapsule film, the electrophoretic film can prevent the pigment particles from moving in an undesired direction due to the field of adjacent pixels, thereby realizing better image quality. At this time, the parasitic field can be completely blocked by further providing a partition wall between adjacent pixels.

In general electrophoretic display devices, when voltage is applied to the pixel electrode, charged pigment particles are moved to an electrode having a polarity opposite to the polarity, and a predetermined image .

On the other hand, when the pigment particles move toward the polarizing electrode, another image is displayed.

From this point of view, the electrophoretic display device according to the prior art will be described with reference to FIG.

1 is a schematic cross-sectional view of an electrophoretic display device according to the prior art.

1, an electrophoretic display device according to the related art includes an upper substrate 51 having a common electrode (not shown) formed on its front surface, a lower substrate 11 having a pixel electrode 29 formed in a matrix form, And an electrophoretic film (40) microencapsulated between the two substrates.

Here, the lower substrate 11 and the upper substrate 51 are made of a thin and flexible film, and the upper substrate 47 and the common electrode (not shown) are made of a material capable of transmitting light . In addition, the lower substrate 11 is formed of a material having a reflection characteristic capable of reflecting light incident from the outside.

In particular, although not shown in the drawing, the common electrode is formed of a transparent conductive material such as ITO (Indium Tin Oxide), and the common electrode is formed on the front surface so that a Vcom signal flows.

In addition, a protective film 25 made of photo-acryl is formed on the entire surface of the substrate including the thin film transistor T of the lower substrate 11.

On the lower substrate 11, a gate wiring (not shown) for transmitting a scanning signal and a data wiring (not shown) for transmitting an image data signal are formed to actively drive the plurality of thin film transistors.

At this time, the gate wiring and the data wiring intersect with each other to define pixels, and each pixel is provided with a thin film transistor T and a storage capacitor (not shown) to control the polarity of the voltage applied to the electrode, It serves to store the voltage.

A pixel electrode 29 electrically connected to the thin film transistor T and applying an electric field to the electrophoretic film 40 is further provided on the protective film 25.

The electrophoretic film 40 is composed of a base film (not shown), a microcapsule 41 and an adhesive film (not shown), and is laminated between the lower and upper substrates 11 and 51. At this time, a conductive film of ITO material is also included in the base film of the electrophoretic film 40. In this case, a common electrode may not be separately formed on the upper substrate.

White particles 45a and black particles 45b are provided in the microcapsules 41 at different voltages and these particles are applied to the pixel electrodes 29 in a predetermined voltage The microcapsules 41 are moved within the microcapsules 41. Accordingly, a monochromatic image is realized on the upper substrate 47 side.

However, there is a fine gap between the electrophoretic films 40. The light that penetrates the electrophoretic film 40 through the gap does not have a layer functioning to absorb light formed on the lower substrate 11 It is reflected by the wiring of the thin film transistor.

Therefore, although not shown in the drawing, in the implementation of a black image, light is reflected through the wirings of the thin film transistor, and there is light coming back, so that the black luminance is lowered, thereby causing a reduction in the contrast ratio.

In addition, even when a white image is implemented, there is a minute gap between the electrophoretic films 40. Light passing through the electrophoretic film 40 through the gap is transmitted through the wiring of the thin film transistor formed on the lower substrate 11 It becomes difficult to realize a clear white screen because it is reflected and returns.

On the other hand, since the electrophoretic display device EPD is a reflection mode and has high reflection luminance and substantially the same reflection brightness per viewing angle, it is preferable to use the embossing profile 25a Is formed on the surface of the protective film 25 of the lower substrate 11.

However, as described above, in the case of forming the embossed cross-sectional structure on the protective film surface of the lower substrate, a vacuum deposition process is required to form the embossed cross-sectional structure, and a patterning process for forming the embossed cross- The manufacturing process becomes complicated and the manufacturing cost is increased.

In addition, since it is difficult to control the size of the embossed cross-sectional structure of a specific size, a luminance difference is generated depending on the viewing angle.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above problems of the prior art, and it is an object of the present invention to provide an electrophoretic display device capable of improving image quality characteristics of a display device using a nanowire conductive film having a high reflection luminance, And a manufacturing method thereof.

According to an aspect of the present invention, there is provided an electrophoretic display device comprising: a lower substrate having a plurality of pixel regions defined therein; A thin film transistor formed on the lower substrate and composed of a gate electrode, an active layer, and a source / drain electrode; A protective film formed on the lower substrate including the thin film transistor; A pixel electrode formed on the protective film and electrically connected to the drain electrode; A nanowire conductive film formed on the protective film including the pixel electrode; An electrophoretic film disposed on the nanowire conductive film; And an upper substrate disposed on the electrophoretic film.

According to an aspect of the present invention, there is provided a method of fabricating an electrophoretic display device, including: forming a thin film transistor including a gate electrode, an active layer, and a source / drain electrode on a lower substrate having a plurality of pixel regions defined therein; Forming a protective film on a lower substrate including the thin film transistor; Forming a contact hole on the protective film to expose a drain electrode of the thin film transistor; Forming a pixel electrode electrically connected to the drain electrode through the contact hole on the protective film; Forming a nanowire conductive film on the protective film including the pixel electrode; Forming an electrophoretic film on the nanowire conductive film; And disposing an upper substrate on the electrophoretic film.

According to an aspect of the present invention, there is provided an electrophoretic display device comprising: a lower substrate having a plurality of pixel regions defined therein; A thin film transistor formed on the lower substrate and composed of a gate electrode, an active layer, and a source / drain electrode; A protective film formed on the lower substrate including the thin film transistor; A nanowire conductive film formed on the protective film and electrically connected to the drain electrode; An electrophoretic film disposed on the nanowire conductive film; And an upper substrate disposed on the electrophoretic film.

According to an aspect of the present invention, there is provided a method of fabricating an electrophoretic display device, including: forming a thin film transistor including a gate electrode, an active layer, and a source / drain electrode on a lower substrate having a plurality of pixel regions defined therein; Forming a protective film on a lower substrate including the thin film transistor; Forming a contact hole on the protective film to expose a drain electrode of the thin film transistor; Forming a nanowire conductive film on the protection film, the nanowire conductive film being electrically connected to the drain electrode through the contact hole; Forming an electrophoretic film on the nanowire conductive film; And disposing an upper substrate on the electrophoretic film.

The electrophoretic display device and the manufacturing method thereof according to the present invention have the following effects.

The electrophoretic display device and the method of manufacturing the same according to the present invention can form a transparent nanowire conductive film having a high transmittance and a large light scattering through a simple solution process on a lower substrate or a reflector, Device can be implemented. In particular, the nanowire conductive film is fabricated through a dispersion in which the conductive nanowires are dispersed in solution, and the nanowires can be arranged to have new work and directionality.

In addition, the nanowire conductive film used in the present invention has a higher transmittance than a transparent electrode formed by general vacuum deposition, a higher luminance uniformity with respect to a viewing angle, and a larger light scattering, do.

In addition, when applied to an in-plane electrophoretic display (EPD), black particles function as a shutter in a reflection mode, so that the black brightness is independent of light scattering, Improvement in image quality characteristics can be achieved.

In addition, when the nanowire conductive film used in the present invention is applied to a liquid crystal display device, the reflection brightness can be increased, thereby increasing the display brightness.

Hereinafter, an electrophoretic display device according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

2 is a schematic cross-sectional view of an electrophoretic display device according to an embodiment of the present invention.

2, the electrophoretic display device according to an embodiment of the present invention includes a pixel electrode 121a formed in a matrix shape, a thin film transistor T electrically connected to the pixel electrode 121a, And an electrophoretic film 140 microencapsulated between the lower substrate 101 and the upper substrate 151. The electrophoretic display device according to claim 1, do.

Here, the lower substrate 101 and the upper substrate 151 are made of a thin and flexible film, and the upper substrate 151 and the common electrode (not shown) are made of a material capable of transmitting light . In particular, although not shown in the drawing, the common electrode is formed of a transparent conductive material such as ITO (Indium Tin Oxide), and the common electrode is formed on the front surface so that a Vcom signal flows.

In addition, the lower substrate 101 is made of a material having a reflection characteristic for reflecting light.

The thin film transistor T is composed of the gate electrode 103, the active layer 107, and the source / drain electrodes 111 and 113. An ohmic contact layer 109 is interposed between the active layer 107 and the source / drain electrodes 111 and 113.

A protective film 115 is formed on the entire surface of the substrate including the thin film transistor T of the lower substrate 101. The protective film 115 is formed with a contact A hole 119 is formed.

A pixel electrode (not shown) electrically connected to the drain electrode 113 through the contact hole 119 and applying an electric field to the electrophoretic film 140 is formed on the protective film 115 including the contact hole 119 And a nanowire conductive layer 123 having an excellent reflection luminance characteristic is formed on the protective layer 115 including the pixel electrode 121a. At this time, the nanowire conductive film 123 has a higher reflection luminance than a transparent electrode formed by vacuum deposition, and a reflection luminance uniformity with respect to a viewing angle is higher than that of a transparent electrode formed by vacuum deposition. In addition, the nanowire conductive film 123 has a large light scattering, so that the light path changes in various directions.

On the lower substrate 101, a gate wiring (not shown) for transmitting a scanning signal and a data wiring (not shown) for transmitting an image data signal are formed to actively drive the plurality of thin film transistors.

At this time, the gate wiring and the data wiring intersect with each other to define pixels, and each pixel is provided with a thin film transistor T and a storage capacitor (not shown) to control the polarity of the voltage applied to the electrode, It serves to store the voltage.

Although not shown in the figure, the storage capacitor Cst is composed of a capacitor lower electrode and a capacitor upper electrode overlapping the capacitor lower electrode with a gate insulating film therebetween. In the image display, And maintains the voltage charged in the electrophoretic film in the off-period to prevent deterioration of image quality due to parasitic capacitance. At this time, the capacitor lower electrode extends to the outside of the active region to receive a signal, and the capacitor upper electrode is connected to the pixel electrode or the drain electrode to receive a signal.

The electrophoretic film 140 is composed of a base film (not shown), a microcapsule 141 and an adhesive film 131, and is laminated between the lower and upper substrates 101 and 151. At this time, a conductive film of ITO material is also included in the base film of the electrophoretic film 140. In this case, a common electrode may not be separately formed on the upper substrate.

White particles 145a and black particles 145b are formed in the microcapsules 141 at different voltages. These particles are applied to the pixel electrodes 121a at a specific voltage The microcapsules 141 are moved within the microcapsules 141. Accordingly, a monochromatic image is formed on the upper substrate 151 side.

Light passing through the electrophoretic film 140 through the gap is reflected upward through the nanowire conductive film 123 formed on the lower substrate 101. In this case, So that the reflection brightness is further increased.

A method of manufacturing the electrophoretic display device according to an embodiment of the present invention will now be described with reference to FIGS. 3A to 3E.

3A to 3E are cross-sectional views illustrating a method of manufacturing an electrophoretic display device according to an embodiment of the present invention.

As shown in FIG. 3A, a metal film (not shown) is deposited on a lower substrate 101 made of flexible plastic, a flexible base film, or a metal having flexibility, and then a photolithography process and an etching process The metal film (not shown) is selectively patterned to form a gate wiring (not shown) and a gate electrode 103 branched from the gate wiring (not shown).

At this time, the metal film material is selected from among Al-based metals such as Al and Al alloys, Ag-based metals such as Ag and Ag alloys, Mo-based metals such as Mo and Mo alloys, and Cr, Ti and Ta.

In addition, they may comprise two membranes of different material properties, namely a bottom membrane and a top membrane thereon. Here, the upper film is made of a metal having a low resistivity, for example, an Al-based metal or an Ag-based metal so as to reduce signal delay and voltage drop of the gate wiring.

Alternatively, the lower film may be made of a material having excellent physical, chemical and electrical contact properties with other materials, particularly indium tin oxide (ITO) or indium zinc oxide (IZO), such as Ti, Ta, Cr, , Or an example of a combination of the lower film and the upper film is Cr / Al-Nd alloy.

Next, a gate insulating film 105 made of an inorganic insulating material such as silicon nitride (SiNx) is formed on the lower substrate 101 including the gate wiring (not shown) and the gate electrode 103.

Although not shown in the drawing, a semiconductor layer (not shown) made of a hydrogenated amorphous silicon layer and a silicide or n-type impurity are doped at a high concentration on the gate insulating film 105, And an impurity layer (not shown) made of a material such as n + hydrogenated amorphous silicon is sequentially formed.

Then, the impurity layer (not shown) and the semiconductor layer (not shown) are selectively patterned by a photolithography process and an etching process to form the active layer 107 and the ohmic contact layer 109.

Next, a metal material for forming a data line is deposited on the lower substrate 101 including the active layer 107 and the ohmic contact layer 109 by a sputtering method, and is selectively patterned by a photolithography process and an etching process A source electrode 111 branched from the data line (not shown), and a drain electrode 113 spaced apart from the source electrode 111 by a predetermined distance are formed.

At this time, the metal material may be an Al-based metal, an Ag-based metal, a Mo-based metal, Cr, Ti, Ta, or the like.

The source electrode 111 and the drain electrode 113 are formed so as to intersect the active layer 107 and the gate electrode (not shown) under the data line (not shown) 103 constitute a thin film transistor T which is a switching element.

The channel of the thin film transistor T is formed in the active layer 107 between the source electrode 111 and the drain electrode 113.

3B, a passivation layer 115 is formed on the entire surface of the lower substrate 101 including the data line (not shown) and the source / drain electrodes 111 and 113. Next, as shown in FIG.

The passivation layer 115 is selectively patterned through a lithography process and an etching process to form a contact hole 119 exposing a portion of the drain electrode 113 of the thin film transistor T. [

3C, a metal material layer 121 made of a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO) is formed on the passivation layer 115 including the contact hole 119, Is deposited by a sputtering method.

Then, as shown in FIG. 3D, the metal material layer 121 is selectively removed by a photolithography process and an etching process, thereby forming a pixel electrode 121a electrically connected to the drain electrode 113. Next, as shown in FIG.

At this time, when a data voltage is applied to the pixel electrode 121a, an electric field is generated together with a common electrode (not shown) to which a common voltage is applied, so that an electric field is generated between the pixel electrode 121a and the common electrode The white particles 145a and the white particles 145b in the electrophoretic film 140 are moved to implement an image from the side of the upper substrate 151. [

3D, the nanowire conductive layer 123 is coated on the protective layer 115 including the pixel electrode 121a using a spin process or a slit coating process.

A method of coating the nano conduction film 123 will now be described with reference to FIG.

4 is a process flow chart for forming a nanowire conductive film of the electrophoretic apparatus according to the present invention.

The nanowire thin film growth method uses a vacuum growth method such as vapor - liquid - solid (VLS), vapor phase (Vapor Phase) and CVD (Chemical Vapor Deposition) and a structure such as Templated - directed - fabrication (Hydrothermal), and virus - based scaffold (VBS).

The nanowire conductive film manufacturing process used in the present invention is a first step (S110), as shown in FIG. 4, in which a liquid material in a colloid state is spin-coated, slit-coated, spray-coated, R2R coating, and an in-plane coating method. Here, a case where a nanowire conductive film is coated by spin coating will be described as an example. At this time, any one of conductive materials such as Ag, Cu, Au, Al, and W may be used as the liquid material used as the nanowire conductive film. The nanowire conductive film is preferably coated to a thickness of about 100 to 1000 angstroms.

 Next, in the second and third steps S120 and S130, the nanowire conductive film coated on the entire surface of the lower substrate is subjected to a first heat treatment process at a temperature of about 100 ° C or lower to remove the solvent remaining on the surface of the nanowire conductive film Remove.

Next, in the fourth and fifth steps (S140 and S150), the nanowire conductive film is subjected to a secondary heat treatment process at a temperature of about 100 to 400 DEG C to have a thin film state having high conductivity and transmittance, .

The nanowire conductive film 123 thus manufactured is applicable to both the electrodes of the lower array substrate of the liquid crystal display device, the color filter substrate, and the upper and lower plates of the electrophoretic device (EPD). At this time, when the nanowire conductive film 123 is formed into a pattern, patterning can be performed by a wet etching or a dry etching process.

After the nanowire conductive film 123 is formed as described above, the electrophoretic film 140 is adhered to the upper portion of the lower substrate 101 by an adhesive layer (not shown), as shown in FIG. 3E. The electrophoretic film 140 includes a microcapsule 141 formed of electrophoretic particles (not shown) and a solvent 143, and a binder (not shown).

Here, the electrophoretic particles consist of white particles 145a for reflecting light and black particles 145b for absorbing light. At this time, the white particles 145a may be positively charged, and the black particles 145b may be negatively charged.

Then, an electrophoretic display device is completed by disposing an upper substrate 151 having a transparent electrode (not shown) on the electrophoretic film 140.

At this time, the transparent electrode (not shown) may be formed of a conductive material having durability and corrosion resistance against the external environment, for example, ITO (indium tin oxide) or IZO (indium zinc oxide) .

The electric field generated between the pixel electrode 121a provided on the lower substrate 101 and the transparent electrode (not shown) of the upper substrate 151 is used to perform electrophoresis The white particles 145a and the black particles 145b move, and a monochromatic image is realized on the upper substrate 151 side.

For example, when a negative voltage is applied to the pixel electrode 121a, the transparent electrode (not shown) of the upper substrate 151 has a relatively positive potential. As a result, the black particles 145b charged to the negatively charged state move to the transparent electrode (not shown), while the positively charged white particles 145a move to the pixel electrode 121a.

At this time, a fine gap exists between the electrophoretic films 140. The light passing through the electrophoretic film 140 through the gap is totally reflected through the nanowire conductive film 123 formed on the lower substrate 101, The reflection brightness can be maximized.

In addition, the nanowire conductive film has a higher reflection luminance than that of the transparent electrode formed by general vacuum deposition, reflectance uniformity to a viewing angle is high, light scattering is large and the optical path is changed to various directions, .

When the nanowire conductive film is applied to an in-plane electrophoretic display device due to these characteristics, black particles function as a light blocking function in a reflection mode, so that black brightness is not related to light scattering, The reflection brightness can be improved when this technique is applied.

An electrophoretic display device according to another embodiment of the present invention will be described in detail with reference to the accompanying drawings.

5 is a schematic cross-sectional view of an electrophoretic display device according to another embodiment of the present invention.

As shown in FIG. 5, the electrophoretic display device according to another embodiment of the present invention includes a nanowire conductive film 221a formed in a matrix shape, and a thin film electrically connected to the nanowire conductive film 221a An upper substrate 251 formed with a common electrode (not shown) on the front surface thereof and a lower substrate 201 composed of a transistor T and an electrophoretic film microencapsulated between the lower substrate 201 and the upper substrate 251 240).

Here, the lower substrate 201 and the upper substrate 251 are made of a thin and flexible film, and the upper substrate 247 and the common electrode (not shown) are made of a material capable of transmitting light . In particular, although not shown in the drawing, the common electrode is formed of a transparent conductive material such as ITO (Indium Tin Oxide), and the common electrode is formed on the front surface so that a Vcom signal flows.

Further, the lower substrate 201 is made of a material having a reflection characteristic for reflecting light.

The thin film transistor T is composed of a gate electrode 203, an active layer 207, and source / drain electrodes 211 and 213. An ohmic contact layer 209 is interposed between the active layer 207 and the source / drain electrodes 211 and 213.

A protective layer 215 is formed on the entire surface of the substrate including the thin film transistor T of the lower substrate 201. The protective layer 215 may be formed of a material for exposing a part of the drain electrode 213 constituting the thin film transistor, A hole 219 is formed.

An upper portion of the protective film 215 including the contact hole 219 is electrically connected to the drain electrode 213 through the contact hole 219 to form a nanowire conduction path for applying an electric field to the electrophoretic film 240. [ The nanowire conductive film 221a has a higher reflection brightness than a transparent electrode made of ITO formed by vacuum deposition and reflectance uniformity at a viewing angle to a vacuum deposition Is higher than that of the transparent electrode. In addition, the nanowire conductive film 221a has a large light scattering, so that the light path is changed in various directions.

On the lower substrate 201, a gate wiring (not shown) for transmitting a scanning signal and a data wiring (not shown) for transmitting an image data signal are formed to actively drive the plurality of thin film transistors.

At this time, the gate wiring and the data wiring intersect with each other to define pixels, and each pixel is provided with a thin film transistor T and a storage capacitor (not shown) to control the polarity of the voltage applied to the electrode, It serves to store the voltage.

Although not shown in the figure, the storage capacitor Cst is composed of a capacitor lower electrode and a capacitor upper electrode overlapping the capacitor lower electrode with a gate insulating film therebetween. In the image display, And maintains the voltage charged in the electrophoretic film in the off-period to prevent deterioration of image quality due to parasitic capacitance. At this time, the capacitor lower electrode extends to the outside of the active region to receive a signal, and the capacitor upper electrode is connected to the pixel electrode or the drain electrode to receive a signal.

The electrophoretic film 240 is composed of a base film (not shown), a microcapsule 241 and an adhesive film 231 and is laminated between the lower and upper substrates 201 and 251. At this time, a conductive film of ITO material is also included in the base film of the electrophoretic film 240. In this case, a common electrode may not be separately formed on the upper substrate.

White particles 245a and black particles 245b are provided in the microcapsules 241 at different voltages. These particles are used as a nanowire conductive layer used as a pixel electrode, When a specific voltage is applied to the lower substrate 221a, the microcapsule 241 moves inside the microcapsule 241, thereby realizing a monochrome image on the upper substrate 251 side.

However, there is a fine gap between the electrophoretic films 240. Light passing through the electrophoretic film 240 through the gap is reflected upward through the nanowire conductive film 221a formed on the lower substrate 201, So that the reflection brightness is further increased.

A method of manufacturing an electrophoretic display device according to another embodiment of the present invention will now be described with reference to FIGS. 6A to 6E.

6A to 6E are cross-sectional views illustrating a method of manufacturing an electrophoretic display device according to another embodiment of the present invention.

As shown in FIG. 6A, a metal film (not shown) is deposited on a lower substrate 201 made of flexible plastic, a flexible base film, or a metal having flexibility, and then a photolithography process and an etching process The metal film (not shown) is selectively patterned by a process to form a gate wiring (not shown) and a gate electrode 203 branched from the gate wiring (not shown).

At this time, the metal film material is selected from among Al-based metals such as Al and Al alloys, Ag-based metals such as Ag and Ag alloys, Mo-based metals such as Mo and Mo alloys, and Cr, Ti and Ta.

In addition, they may comprise two membranes of different material properties, namely a bottom membrane and a top membrane thereon. Here, the upper film is made of a metal having a low resistivity, for example, an Al-based metal or an Ag-based metal so as to reduce signal delay and voltage drop of the gate wiring.

Alternatively, the lower film may be made of a material having excellent physical, chemical and electrical contact properties with other materials, particularly indium tin oxide (ITO) or indium zinc oxide (IZO), such as Ti, Ta, Cr, , Or an example of a combination of the lower film and the upper film is Cr / Al-Nd alloy.

Next, a gate insulating film 205 made of an inorganic insulating material such as silicon nitride (SiNx) is formed on the lower substrate 201 including the gate wiring (not shown) and the gate electrode 203.

Although not shown in the figure, a semiconductor layer (not shown) made of a hydrogenated amorphous silicon layer and a silicide or n-type impurity are doped at a high concentration on the gate insulating film 205, And an impurity layer (not shown) made of a material such as n + hydrogenated amorphous silicon is sequentially formed.

Then, the impurity layer (not shown) and the semiconductor layer (not shown) are selectively patterned by a photolithography process and an etching process to form the active layer 207 and the ohmic contact layer 209.

Next, a metal material for forming a data line is deposited on the lower substrate 201 including the active layer 207 and the ohmic contact layer 209 by a sputtering method and selectively patterned by a photolithography process and an etching process A source electrode 211 branched from the data line (not shown), and a drain electrode 213 spaced apart from the source electrode 211 by a predetermined distance are formed, respectively.

At this time, the metal material may be an Al-based metal, an Ag-based metal, a Mo-based metal, Cr, Ti, Ta, or the like.

The source electrode 211 and the drain electrode 213 are formed so as to intersect the active layer 207 and the gate electrode (not shown) under the data line (not shown) 203 constitute a thin film transistor T which is a switching element.

A channel of the thin film transistor T is formed in the active layer 207 between the source electrode 211 and the drain electrode 213.

6B, a passivation layer 215 is formed on the entire surface of the lower substrate 201 including the data line (not shown) and the source / drain electrodes 211 and 213. Next, as shown in FIG.

The passivation layer 215 is selectively patterned through a lithography process and an etching process to form a contact hole 219 exposing a portion of the drain electrode 213 of the thin film transistor T. [

6C, the nanowire conductive material film 221 is coated on the protective film 215 including the contact hole 219 using a spin process or a slit coating process.

6D, the nanowire conductive film 221 is selectively removed by a photolithography process and an etching process to form a nanowire conductive film 221a electrically connected to the drain electrode 213 . At this time, the nanowire conductive film 221a is used instead of the pixel electrode.

At this time, when a data voltage is applied to the nanowire conductive film 221a, an electric field is generated together with a common electrode (not shown) to which a common voltage is applied, so that the nanowire conductive film 221a and the common electrode The white particles 245a and the white particles 245b in the electrophoretic film 240 between the upper substrate 251 and the upper substrate 251 are moved.

A method of coating the nanowire conductive film 221a in this manner has been described above with reference to FIG. 4. Here, a brief description will be given below.

4 is a process flow chart for forming a nanowire conductive film of the electrophoretic apparatus according to the present invention.

The nanowire conductive film manufacturing process used in the present invention is a first step (S110), as shown in FIG. 4, in which a liquid material in a colloid state is spin-coated, slit-coated, spray-coated, R2R coating, and an in-plane coating method. Here, a case where a nanowire conductive film is coated by spin coating will be described as an example. At this time, any one of conductive materials such as Ag, Cu, Au, Al, and W may be used as the liquid material used as the nanowire conductive film. The nanowire conductive film is preferably coated to a thickness of about 100 to 1000 angstroms.

 Next, in the second and third steps S120 and S130, the nanowire conductive film coated on the entire surface of the lower substrate is subjected to a first heat treatment process at a temperature of about 100 ° C or lower to remove the solvent remaining on the surface of the nanowire conductive film Remove.

Next, in the fourth and fifth steps (S140 and S150), the nanowire conductive film is subjected to a secondary heat treatment process at a temperature of about 100 to 400 DEG C to have a thin film state having high conductivity and transmittance, .

The nanowire conductive film 221a thus manufactured is applicable to both the electrodes of the lower array substrate of the liquid crystal display device, the color filter substrate, and the upper and lower plates of the electrophoretic device (EPD). At this time, when the nanowire conductive film 221a is formed as a pattern, patterning can be performed by a wet etching or a dry etching process.

After the formation of the nanowire conductive film 221a as described above, the electrophoretic film 240 is adhered to the upper portion of the lower substrate 201 by an adhesive layer (not shown), as shown in FIG. 6E. The electrophoretic film 240 includes a microcapsule 241 formed of electrophoretic particles (not shown) and a solvent 243, and a binder (not shown).

Here, the electrophoretic particles consist of white particles 245a reflecting light and black particles 245b absorbing light. At this time, the white particles 245a may be positively charged, and the black particles 245b may be negatively charged.

Next, an electrophoretic display device is completed by disposing an upper substrate 251 having transparent electrodes (not shown) on the electrophoretic film 240.

At this time, the transparent electrode (not shown) may be formed of a conductive material having durability and corrosion resistance against the external environment, for example, ITO (indium tin oxide) or IZO (indium zinc oxide) .

By the electric field generated between the nanowire conductive film 221a provided on the lower substrate 201 and the transparent electrode (not shown) of the upper substrate 251, the electrophoretic film 240 contained in the electrophoretic film 240 The electrophoretic particles, that is, the white particles 245a and the black particles 245b move, and a monochromatic image is realized on the upper substrate 251 side.

For example, when a negative voltage is applied to the pixel electrode 221a, the transparent electrode (not shown) of the upper substrate 251 has a relatively positive potential. As a result, the negatively charged black particles 245b move to the transparent electrode (not shown), while the positively charged white particles 245a move to the nanowire conductive film 221a.

At this time, a minute gap exists between the electrophoretic films 240. The light passing through the electrophoretic film 240 through the gap is totally reflected through the nanowire conductive film 221a formed on the lower substrate 201, The reflection brightness can be maximized.

As described above, since the nanowire conductive film according to the present invention is used in place of the pixel electrode, a separate pixel electrode is not needed, thereby reducing manufacturing steps and manufacturing costs.

In addition, the nanowire conductive film has a higher reflection luminance than that of the transparent electrode formed by general vacuum deposition, reflectance uniformity to a viewing angle is high, light scattering is large and the optical path is changed to various directions, .

When the nanowire conductive film is applied to an in-plane electrophoretic display device due to these characteristics, black particles function as a light blocking function in a reflection mode, so that black brightness is not related to light scattering, The reflection brightness can be improved when this technique is applied.
Meanwhile, the nanowire conductive film according to the present invention is applied to an electrophoretic display device, but it is also applicable to a display device such as a reflective / transmissive FPD (flat panel display) or a liquid crystal display device.

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While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments.

Therefore, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concept of the present invention defined in the following claims are also within the scope of the present invention.

1 is a schematic cross-sectional view of an electrophoretic display device according to the prior art.

2 is a schematic cross-sectional view of an electrophoretic display device according to an embodiment of the present invention.

3A to 3E are cross-sectional views illustrating a method of manufacturing an electrophoretic display device according to an embodiment of the present invention.

FIG. 4 is a flowchart illustrating a manufacturing process of a nanosecond coating film of an electrophoretic apparatus according to an embodiment of the present invention.

5 is a cross-sectional view of an electrophoretic display device according to another embodiment of the present invention.

6A to 6E are views showing an electrophoretic display manufacturing apparatus according to another embodiment of the present invention
Fig. 3 is a process sectional view for explaining the method.

DESCRIPTION OF THE REFERENCE SYMBOLS

101: lower substrate 103: gate electrode

105: gate insulating film 107: active layer

109: ohmic contact layer 111: source electrode

113: drain electrode 115: protective film

119: Contact hole 121: Transparent material layer

121a: pixel electrode 123: nanowire conductive film

140: electrophoresis film 141: microcapsule

143: Solvent 145a: Black particles

145b: white particles 151: upper substrate

Claims (13)

A lower substrate having a plurality of pixel regions defined therein; A thin film transistor formed on the lower substrate and composed of a gate electrode, an active layer, and a source / drain electrode; A protective film formed on the lower substrate including the thin film transistor; A pixel electrode formed on the protective film and electrically connected to the drain electrode; A nanowire conductive film formed on the protective film including the pixel electrode; An electrophoretic film disposed on the nanowire conductive film; And And an upper substrate disposed on the electrophoretic film. The electrophoretic display device according to claim 1, wherein the nanowire conductive film is formed using any liquid material selected from the group consisting of Ag, Cu, Au, Al, and W as a conductive material. The electrophoretic display device according to claim 1, wherein the nanowire conductive film is formed to a thickness of 100 to 1000 ANGSTROM. Forming a thin film transistor including a gate electrode, an active layer, and a source / drain electrode on a lower substrate on which a plurality of pixel regions are defined; Forming a protective film on a lower substrate including the thin film transistor; Forming a contact hole on the protective film to expose a drain electrode of the thin film transistor; Forming a pixel electrode electrically connected to the drain electrode through the contact hole on the protective film; Forming a nanowire conductive film on the protective film including the pixel electrode; Disposing an electrophoretic film on the nanowire conductive film; And And disposing an upper substrate on the electrophoretic film. ≪ Desc / Clms Page number 20 > The electrophoretic display device according to claim 4, wherein the nanowire conductive film is formed using any one of liquid materials selected from the group consisting of Ag, Cu, Au, Al, and W as a conductive material. [5] The method of claim 4, wherein the nanowire conductive film is formed to a thickness of 100 to 1000 ANGSTROM. 5. The electrophoretic display device according to claim 4, wherein the nanowire conductive film is formed by any one of spin coating, slit coating, spray coating, ink jet coating, R2R coating, and in- A method of manufacturing a display device. [7] The method of claim 7, wherein the nanowire conductive film is formed by spin coating, slit coating, spray coating, inkjet coating, R2R coating, or in- Removing the remaining solvent by performing a primary heat treatment at a temperature of 100 ° C or less and then performing a secondary heat treatment at a temperature of 100 to 400 ° C to form a nanowire conductive film. delete Forming a thin film transistor including a gate electrode, an active layer, and a source / drain electrode on a lower substrate on which a plurality of pixel regions are defined; Forming a protective film on a lower substrate including the thin film transistor; Forming a contact hole on the protective film to expose a drain electrode of the thin film transistor; Forming a nanowire conductive film on the protection film, the nanowire conductive film being electrically connected to the drain electrode through the contact hole; Disposing an electrophoretic film on the nanowire conductive film; And And disposing an upper substrate on the electrophoretic film. ≪ Desc / Clms Page number 20 > The electrophoretic display device according to claim 10, wherein the nanowire conductive film is formed using any liquid material selected from the group consisting of Ag, Cu, Au, Al, and W as a conductive material. The method of claim 11, wherein the nanowire conductive film is formed by coating a nanowire thin film by selecting one of spin coating, slit coating, spray coating, inkjet coating, R2R coating, or in- Removing the remaining solvent by performing a primary heat treatment at a temperature of 100 ° C or less and then performing a secondary heat treatment at a temperature of 100 to 400 ° C to form a nanowire conductive film. 11. The method of claim 10, wherein the nanowire conductive film is formed to a thickness of 100 to 1000 ANGSTROM.

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