KR100789110B1 - Electronic Paper Display Device - Google Patents

Abstract

The present invention relates to an electronic paper display device, and in particular, a lower substrate and an upper substrate disposed to face each other at a predetermined interval; A lower electrode and an upper electrode inscribed to the lower substrate and the upper substrate, respectively; A partition wall which divides the pixel between the lower electrode and the upper electrode to form a pixel space; And a plurality of particles encapsulated in the pixel space, wherein the particles have a surface that is roughly modified. The electronic paper display device may include an area of a particle contacting a lower electrode or an upper electrode. By reducing the number of contacts using the electrostatic force is reduced, thereby reducing the voltage driving the particles.

Electronic paper, plasma, surface modification

Description

Electronic paper display device

1 is a perspective view showing a cell structure of a microcapsule type electronic paper display device according to the prior art,

2 is a perspective view illustrating a cell structure of a dry electronic paper display device according to the prior art;

3 is a cross-sectional view showing the shape of the dry electronic paper particles according to the prior art,

4 is a cross-sectional view illustrating a cell structure of an electronic paper display device according to an exemplary embodiment of the present invention.

5 is a cross-sectional view showing the structure of the particles before and after surface modification according to an embodiment of the present invention,

6 is a state diagram showing a state in which the particles before and after the surface modification contact the electrode according to an embodiment of the present invention,

7 is a schematic diagram showing a state in which the porosity is formed by plasma treatment on the surface of the particle according to an embodiment of the present invention,

8 is a schematic diagram showing a state in which cross-linking or grafting is formed by performing a plasma treatment on the surface of the particle according to an embodiment of the present invention.

** Description of Symbols for Main Parts of Drawings **

1: lower substrate 2: upper substrate

3: lower electrode 4: upper electrode

5: bulkhead 6: black particles

7: white particle 8: polymer resin

9: colorant 10: charge control agent

11: external additive 12: recess

13: surface of the particle 14: cross-linking

15: grafting

The present invention relates to an electronic paper display device, in particular characterized in that the surface of the particles contained therein are modified. In more detail, the surface of the plurality of particles encapsulated in the pixel space is roughly modified so that the area of the particles in contact with the lower electrode or the upper electrode is reduced.

BACKGROUND ART Conventionally, an electronic paper device using an electrophoretic method, an electrochromic method, a thermal method, a two-color particle rotation method and the like has been proposed as an image display device replacing a liquid crystal (LCD). Such an electronic paper device is considered to be a technology that can be used in the next generation of inexpensive image display devices because of the advantages of having a wider viewing angle closer to a normal printed matter, smaller power consumption, and a memory function than LCDs. Development into terminal image displays, electronic papers, and the like is expected.

In particular, in recent years, electrophoresis-type electronic paper has been proposed, which encapsulates a dispersion liquid composed of dispersed particles and a colored solution and arranges them between opposing substrates. The display incorporates a unique concept of electrophoretic ink encapsulated in the technology. As shown in FIG. 1, the capsule-type electronic paper prepares transparent microcapsules contained in a dielectric fluid in which black fine particles 40 and white fine particles 30 have a color, and then mixed with a binder 50 to form a substrate ( Positioned between the upper and lower transparent electrodes 20 inscribed in 10) and applying a positive voltage, the negatively charged ink fine particles move to the surface to display the color of the fine particles. In addition, when a negative voltage is applied, the ink particles move downward to see the color of the fluid. In this way, the characters or images are displayed.

However, in the electrophoresis method, since the particles move in the liquid, there is a problem that the response speed is slow due to the viscosity resistance of the liquid. In addition, since high specific gravity particles such as titanium oxide are dispersed in a low specific gravity solution, they tend to settle, are difficult to maintain stability in a dispersed state, and suffer from a lack of image repeat stability. Even in the case of microencapsulation, the cell size is set to the microcapsule level so that the above-mentioned defects are not easily seen in appearance.

In the electrophoretic method using the behavior in such a solution, two or more kinds of particles having different colors and charging characteristics are enclosed between at least one transparent substrate without using a solution in recent years, and either one of the substrates or Electronic paper has been proposed to impart an electric field to the particles from an electrode pair formed of both electrodes, and to move the particles by coulomb force to display an image. The operation mechanism of such a dry electronic paper display device is to insert a mixture of two kinds of particles having different colors and charge polarities into an electrode disc, and apply a voltage to the electrode disc to generate an electric field between the pole discs to generate a polarity. It is used as a display element by making different charged particles fly in a different direction. These are dry display devices that consist of particles and substrates and utilize particle behavior in gas, and solve problems such as sedimentation and flocculation of particles, which have been a problem in electrophoresis because no solution is used. This has the advantage of being small and fast in response.

The cell structure of the dry electronic paper display device is shown in FIG. 2 and briefly described as follows. As shown, the structure includes a top and bottom substrate (160, 110) formed of plastic or glass, and a transparent electrode (ITO) to apply a driving voltage of the device on the top and bottom substrate (160, 110) The upper and lower electrodes 170 and 120 formed thereon, the partition wall 130 separating the cell from the cell, the black positive charged particles 140 and the white negative charged present between the two electrodes. It consists of particles 150.

In the electronic paper display device having the above structure, when sufficient voltage is applied to the upper electrode 170 and the lower electrode 120, charged particles 130 and 140 charged according to the applied electrode polarity are attracted to each electrode. . For example, when-voltage is applied to the lower electrode 120 and + voltage is applied to the upper electrode 170, the black charged particles 140 positively charged by the coulomb force move toward the lower substrate 110. The charged white charged particles 150 move toward the upper substrate 160. Since the white charged particles 150 are located on the upper substrate 160 side, the white charged particles 150 appear to be white when viewed from the outside. On the contrary, when + voltage is applied to the lower electrode 120 and-voltage is applied to the upper electrode 170, the charged white charged particles 150 move toward the lower substrate 110, and the positively charged black charged particles ( 140 moves toward the upper substrate 160 to be displayed in black. Therefore, after applying a voltage so that all the cells appear white at first, only the desired cell is applied with the opposite voltage so that the cells appear black.

In the dry electronic paper display device, two particles of different colors in each cell are charged positively by one particle and negatively charged by another by friction. 3 is related to the particles used in the electronic paper display device according to the prior art, it is a schematic diagram showing a state in which the charge control agent 230 and the external additive 210 is added to the polymer resin 220. This may further include a pigment or dye 240 representing the color of the particles.

Thus, two kinds of particles 140 and 150 which are spherical in shape and differ in color and charging characteristics are displayed by moving in an emergency by the voltage of the electrodes on the upper and lower substrates. However, there is a problem in that the dry electronic paper including the particles of the above type has a higher driving voltage for moving the particles than the conventional wet electronic paper. Accordingly, there is an urgent need for new methods or new types of particles that can lower the magnitude of the voltage applied to the two electrodes to drive the particles. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for modifying the surface of particles as one of methods for reducing driving voltage.

The present invention has been made to solve the above problems, in the electronic paper display device, it is to include a plurality of particles, characterized in that the surface of the surface of the plurality of particles enclosed in a rough rough surface modification. Through this, to reduce the surface area of the particles in contact with the lower electrode or the upper electrode.

Thus, if the surface area of the particles is modified to reduce the surface area of the particles in contact with the lower electrode or the upper electrode, the number of contacts using electrostatic force is reduced, thereby reducing the voltage driving the particles. In addition, the present invention is to reduce the driving voltage by improving the crosslinking force of the polymer resin resin through the surface modification of the particles to adhere the external additives well, thereby increasing the fluidity of the particles.

Furthermore, if there is a lower insulating layer or an upper insulating layer that can be selectively formed on the lower electrode or the upper electrode of the electronic paper display device, the present invention provides an area of the particle contacting the insulating layer through the surface-modified particles. By reducing the, it is intended to provide an effect that can move the particles freely even with a small driving voltage.

As such, the present invention provides a new method or a new type of particles that can reduce the magnitude of the voltage applied to the two electrodes to drive the particles by modifying the surface of the particles, thereby securing more margin of the driving circuit. In addition, it is to provide a device of excellent image quality at a low cost.

The present invention for achieving the above object is a lower substrate and the upper substrate which is arranged facing at a predetermined interval; A lower electrode and an upper electrode inscribed to the lower substrate and the upper substrate, respectively; A partition wall which divides the pixel between the lower electrode and the upper electrode to form a pixel space; And a plurality of particles encapsulated in the pixel space, wherein the particles have a rough surface modified surface.

The electronic paper display device may further include a lower insulating layer and an upper insulating layer inscribed in the lower electrode and the upper electrode, respectively, wherein the particles are surface-modified so that recesses are formed on the surface of the particles. It is possible.

In addition, the surface modification is preferably performed by a plasma treatment, and the plasma treatment is more preferably a low temperature plasma or glow discharge treatment.

In addition, in the electronic paper display device according to the present invention, the particles may have a porous surface or cross-linking or grafting may be formed on the surface of the particles by the plasma treatment. The gas used in the plasma treatment is argon (Ar), RF (radio frequency) argon (Ar), helium (He), hydrogen (H ₂ ), oxygen (O ₂ ), nitrogen (N ₂ ), ammonia (NH ₃ ), methane (CH ₄ ), acetylene (acetylene), low-temperature RF mixed with hydrogen and nitrogen or a combination of these gases is more suitable.

Specifically, when the gas used in the plasma treatment is oxygen (O ₂ ) gas, the surface of the particles may be characterized in that the oxidation reaction or volatile oxide is generated, the gas used in the plasma treatment is nitrogen In the case of (N ₂ ) or argon (Ar) gas, it is also possible to generate a functional group containing nitrogen on the surface of the particle, the gas used in the plasma treatment is an argon (Ar) gas, by radio frequency (RF) When generating a plasma, an electronic paper display device may be characterized in that a cone having a height of about 1 μm is formed at a density of 10 ⁹ cm ⁻² or a -CO bond is formed on the surface of the particle.

Subsequently, the surface contact angle of the particles may be 50 ° or less by the plasma treatment, and the surface of the particles may be hydrophilic by the plasma treatment.

Furthermore, in the electronic paper display device as described above, the particles are in the form of a spherical external additive enclosed around the polymer resin, it is preferable to further include at least one or more of the pigments, dyes and charge control agents dyed. More preferably, the particles are charged or uncharged dry particles.

Hereinafter, one preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. The invention can be better understood by the following examples, which are intended for the purpose of illustration of the invention and are not intended to limit the scope of protection defined by the appended claims.

4 is a cross-sectional view illustrating a cell structure of an electronic paper display device according to an exemplary embodiment of the present invention. As shown herein, the present invention provides a lower substrate 1 and an upper substrate (which are disposed to face each other at a predetermined interval). 2); A lower electrode 3 and an upper electrode 4 inscribed in the lower substrate 1 and the upper substrate 2, respectively; Barrier ribs 5 for dividing pixels between the lower electrode 3 and the upper electrode 4 to form a pixel space; And a plurality of particles 6 and 7 encapsulated in the pixel space, wherein the particles 6 and 7 are roughly surface-modified.

First, in the electronic paper display device according to the present invention, the lower electrode 3 is formed on the lower substrate 1, the upper electrode 4 is formed below the upper substrate 2, and the lower electrode 3 and the upper part are formed. At least one of the electrodes 4 is preferably a transparent ITO electrode. In addition, it is preferable that the basic electrode structures of the electronic paper display device according to the present invention have a matrix structure and cross each other.

A lower insulating layer (not shown) and an upper insulating layer (not shown) may be selectively formed on the lower electrode 3 and the upper electrode 4, respectively. Although the lower insulating layer and the upper insulating layer applied on the lower electrode 3 and below the upper electrode 4 are omitted, there is no problem in driving. However, when the charged particles 6 and 7 adhere to the electrode, electron movement occurs. The memory effect is preferably applied because it can be difficult to preserve the image for a long time without applying new power.

In addition, the present invention includes a partition wall 5 for dividing pixels between the lower electrode 3 and the upper electrode 4 to form a pixel space. As shown in FIG. 4, a plurality of barrier ribs 5 are formed on the lower electrode 3 or the lower insulating layer formed on the lower substrate 1, which is formed on the upper electrode 4 or upper insulating layer formed under the upper substrate 2. In contact with the layer, a pixel space for dividing the pixels is formed. In FIG. 4, the barrier rib 5 is formed directly on the lower electrode 3, but as described above, since the lower insulating layer may be omitted in the present invention, in another embodiment of the present invention, the lower electrode 3 is disposed on the lower electrode 3. It is also possible to form the partition wall 5 forming the pixel space on the formed lower insulating layer.

Subsequently, a plurality of particles 6 and 7 are encapsulated in the pixel space to express an image, and the present invention is characterized in that the surfaces of the particles 6 and 7 are roughly surface modified.

Here, the surface of the particles 6 and 7 is roughly surface-modified means that the surface of the particles made of the polymer resin or the polymer resin surrounded by the external additive is not smooth or flat, but is roughly or sharply uneven. In addition, the flat surface has a porous surface or includes a curved shape, it is preferably characterized in that the recess (12) is formed on the surface of the particles (6, 7) as shown in FIG.

Thus, using the particles 6, 7 whose surface is roughly modified according to the present invention, it is possible to reduce the area of the particles (6, 7) in contact with the lower electrode (3) or the upper electrode (4) contact using the electrostatic force The number of the is reduced, thereby reducing the voltage driving the particles (6, 7). The present invention is to reduce the high driving voltage, which is a disadvantage of the conventional dry electronic paper, by reducing the contact area by roughening the surface of the particles (6, 7) that touch the transparent electrode particles (6, 7) by low external voltage ) Is removed from the electrode. The present invention is to modify the surface of the particles (6, 7) made of a high molecular polymer resin for this purpose.

FIG. 6 is a state diagram showing a state in which the particles 6 and 7 come into contact with the electrodes 3 and 4 before and after surface modification, according to an embodiment of the present invention. , 7) and the electrode 3, 4 by reducing the area that the particles (6, 7) can be removed even at a small voltage. Assuming that the charges are evenly distributed throughout the particles 6 and 7, which are high resistivity polymers, they are held together by the imaging force and released by voltages of opposite polarity. Since the charges distributed on the particles are so far apart, they can be held by small forces (voltages) according to Coulomb's law. That is, according to the present invention, since the surface-modified particles are displaced from the surface as much as the charge is surface-modified, Coulomb's law (the force acting between charges is inversely proportional to the square of the distance) is smaller than That means you can drive with a smaller voltage that requires force. In addition, the force stuck by the imaging force is also weakly attached to the surface-modified particles (6, 7) according to the present invention.

As described above, according to the present invention, the particles 6 and 7 whose surface is roughly modified by the surface modification have grooves 12 on the surface, so that the area of contact with the electrodes 3 and 4 is small so that the electrostatic force is used. The fewer the contacts, the less the force required to remove the particles 6 and 7. Then, the voltage for driving the particles 6 and 7 can be reduced, the margin of the driving circuit can be more secured, and the device of excellent image quality can be provided at low cost.

As described above, the electronic paper display device according to the present invention includes particles 6, 7 whose surface is roughly surface-modified, and the method of surface-modifying the particles is not particularly limited, and in the following, conventional particles The case where the surface of the particles 6 and 7 is modified through plasma treatment while using is described as an example.

Plasma treatment to modify the polymer surface of the particles 6 and 7 not only results in a chemically highly active state but also allows the external additive 11 to adhere to the fluidity well. have. When the surface is treated with plasma, the surface properties of the particles 6 and 7, which are polymers or inorganic resins, can be roughly activated without changing bulk properties. That is, the polymer exposed to the plasma changes in wetting property, cross-linking, and molecular weight, and accordingly, the particles 6 and 7 and the electrodes 3 and 4 or the insulating layer and the partition wall ( 5) can reduce the area of contact.

Here, the plasma refers to a gas that is ionized and exhibits electrical neutrality as a whole. Well-known plasmas in nature are lightning and aurora. These occur under relatively high and extremely low pressures, respectively. As such, the plasma may be classified into various types according to its generation method and pressure.

These plasmas can be classified into two types according to temperature: one is a high temperature plasma or thermal plasma, which has a high degree of ionization, its components are thermodynamically balanced, and has an average temperature of tens of thousands of degrees. The other is a 'low temperature plasma or glow discharge' with extremely low ionization (ion concentrations: 10 ^-5 to 10 ^-6 ) and components that are not thermodynamically balanced and whose average temperature is slightly above room temperature. to be.

The present invention preferably performs a low temperature plasma treatment among such high temperature plasma and low temperature plasma. The latter can be plasma-treated at low temperatures and easily obtained by electrically discharging gases or organic vapors at low pressure. In addition, the polymer processing method using low temperature plasma is a dry process that does not use water, compared to the conventional processing method, and is an efficient method that can change only the surface properties without changing the mechanical properties such as strength and elastic modulus with less environmental pollution. . In particular, by using a variety of gases alone or in combination, it is possible to simultaneously provide various various surface properties that could not be obtained by conventional methods.

7 and 8 are schematic diagrams showing a state before and after plasma treatment on the surface of the particles according to an embodiment of the present invention. Surface modification of the particles by plasma treatment may be of two types for example. FIG. 7 is a schematic diagram showing a state in which a porous is formed before and after plasma treatment on the surface of the particle, and FIG. 8 is cross-linked before and after plasma treatment on the surface of the particle. It is a schematic diagram which shows the state in which linking) or grafting was formed.

First, as shown in FIG. 7, in the case of performing a plasma treatment on the surface 13 of the particles 6 and 7, the porosity is increased on the surface 13 of the particles 6 and 7 by the plasma treatment. The electronic paper display device, characterized in that formed to reduce the surface area of the particles (6, 7). Porosity on the surface of a smooth particle means that the surface area of the particle is reduced, which reduces the area of the particle in contact with the electrode or the insulating layer. Plasma treatment of flat surfaces of particles of polymers involves physical ablation of polymer materials. In this type of plasma treatment method, the surface 13 of the particles 6 and 7 can be made porous.

In order to form porosity by physical melting according to the present invention, it is preferable to shorten the plasma treatment time, and when the plasma treatment time is too long, porosity may be blocked by polymerization of the melted material. In the case of the inorganic polymer material as well as the polymer polymer material of the particles 6 and 7, when the general polymer is deposited on the surface and subjected to plasma treatment, porosity is applied to the surface 13 of the particles 6 and 7 by physical melting. Can be formed.

As shown in FIG. 8, the present invention cross-links the surface 13 of the particles 6 and 7 when the surface 13 of the particles 6 and 7 is plasma treated. (14) or a grafting (15) is an electronic paper display device characterized in that the surface area is reduced by modifying the surface is formed. In the present invention, there are two methods of modifying the surface of the polymer with plasma, one of which is a process called casing, which is cross-linked to the surface of the polymer or to an already deposited film by bombardment of high-energy particles in the plasma. cross-linking) 14.

Another method is to change the chemical properties of the particle surface 13 through deposition or grafting. As the precursor precursor in the plasma dissociates, it grows as a variety of active films are formed. In the surface activation of the polymer, when the high-energy particles of the plasma bombard the surface, covalent bonds of the polymer surface are broken, and active species are generated on the surface. The active species react with the active species in the plasma, and the functional group having various chemical activities on the surface is present. Make them. These functional groups modify the surface of the polymer of the particles to hydrophilic to increase the active energy, thereby reducing the surface area of the particles.

The polymer surface treatment effect of the low temperature plasma according to the present invention may vary depending on the shape of the reactor, electrode type, high frequency output and frequency, type of gas used, gas flow rate, processing pressure, exhaust rate, treatment time, and the like. Depending on whether it is or non-polymeric, other aspects of surface modification such as simple modification or surface graft occur.

Gas used for the plasma treatment according to the present invention is argon (Ar), RF (radio frequency) argon (Ar), helium (He), hydrogen (H ₂ ), oxygen (O ₂ ), nitrogen (N ₂ ) Preferred is a gas consisting of ammonia (NH ₃ ), methane (CH ₄ ), acetylene, low-temperature RF mixed with hydrogen and nitrogen, or a combination thereof.

In a specific embodiment, when the gas used for the plasma treatment is oxygen gas, the surface 13 of the particles 6 and 7 may undergo an oxidation reaction or volatile oxides to modify the surface. In addition, when oxygen is added to the plasma reaction gas helium or argon, a reaction occurs between the oxygen and the broken polymer chain, thereby volatile oxides are made to activate the polymer surface. In this case, the activation degree increased about three times in the plasma to which oxygen was added than that treated in an inert gas. The degree of activation is improved because the polymer chains are broken to make the surface rougher.

When the gas used in the plasma treatment is nitrogen or argon gas, functional groups containing nitrogen may be generated on the surface 13 of the particles 6 and 7 to modify the surface. In addition, when the gas used for the plasma treatment is an argon (Ar) gas, and when plasma is generated by RF (radio frequency), a cone having a height of about 1 μm is formed at a density of 10 ⁹ cm ⁻² on the upper surface of the partition wall or -CO bonds can be formed.

Furthermore, ammonia plasma or low-temperature RF plasma mixed with hydrogen and nitrogen as the plasma gas is used for surface modification of polypropylene, polyethylene terephtlate (PET), polycarbonate (PC), PVC, and polymethyl methacrylate (PMMA). Excellent, amino groups formed in the plasma are adsorbed on the surface of the polymer to improve the wettability of the surface. Thus, the wettability of the surface of the particles is improved by physical and chemical changes, and thus high surface energy and excellent activation energy can be obtained.

As such, when the surface 13 of the particles 6, 7 is subjected to plasma treatment according to the present invention, the surface 13 of the particles 6, 7 may be roughly surface modified. When the present inventors did not perform the plasma treatment through experiments, the inventors observed that the surfaces 13 of the particles 6 and 7 were smooth, and fine irregularities were generated on the surface of the foam according to the plasma treatment. The phenomenon that minute irregularities appear on the surface of the polymer material is due to plasma etching.

Specifically, when nitrogen or oxygen was used as the plasma generating gas, the surface etching effect was superior to argon. This phenomenon is presumably because argon gas is an inert gas, but nitrogen and oxygen are active gases, and the effect of breaking the chemical bond on the surface of the polymer is greater than that of argon gas. In addition, it was shown that the use of oxygen gas was more excellent in the surface etching effect than the use of nitrogen gas. Therefore, in order to etch the surface 13 of the particles 6 and 7, it was confirmed that it is more effective to use the active gas than to use the inert gas as the plasma generating gas.

Another embodiment of the present invention may be that the contact angle of the surface 13 of the particles 6, 7 is 50 ° or less or the surface of the particles is hydrophilic by such plasma treatment. Contact angle refers to the angle formed when a liquid is thermodynamically equilibrated on a solid surface, and the contact angle is a measure of the wettability of a solid surface. A low contact angle indicates high wettability and high surface energy, which means that the active energy is large and the surface is roughly modified. It means.

The present inventors have found that the contact angle of the surface is reduced by plasma treatment of the surface 13 of the particles 6, 7. Although the contact angle of the untreated plasma barrier surface was 97 °, the contact angle of the surface 13 of the plasma-treated particles 6 and 7 for 30 seconds tended to decrease rapidly to about 50 °. The reason why the initial contact angle is significantly decreased by the low temperature plasma treatment is that the surface of the untreated particles is microscopically very smooth and hydrophobic, but the surface is etched by the initial plasma treatment and the surface smoothness is significantly reduced, so that the liquid may adhere. This is due to the occurrence of small voids. It was also confirmed that the surface was changed from hydrophobic to hydrophilic with the change in the chemical structure of the surface 13 of the particles 6, 7.

The present invention also improves the crosslinking force of the polymer resin resin (8) through surface modification of the particles (6, 7) as described above, so that the external additive (11) sticks well, and thus the particles (6, 7) By increasing the fluidity of the drive voltage can be lowered. To this end, the particles (6, 7) of the electronic paper display device according to the invention is preferably a form in which the external additive 11 is surrounded by a sphere around the polymer resin (8) as shown in FIG.

The roughly surface modified particles 6, 7 according to the invention can have a larger surface area at the same size as compared to conventional general spherical particles. Here, the large surface area means that the surface area of the particles 6 and 7 itself becomes wider, and the area where the particles 6 and 7 come into contact with the electrodes 3 and 4 or the insulating layer is further reduced. When the surface area of the particles 6 and 7 is increased by the surface modification and the crosslinking force of the polymer resin is increased, a larger amount of the external additive 11 may be coated around the polymer resin 8. At the same time, the surface 13 of the particles 6, 7 is roughened by crosslinking, grafting or grooves 12 formed by surface modification, and the surface area can be reduced than that of ordinary spherical particles because of the uneven surface.

Here, the polymer resin 8 used in the present invention is any component capable of being charged or obtaining a charge, and the external resin 11 is coated on the surface of the polymer resin 8, Dyed pigments or dyes, ie colorants 9 or charge control agents 10 may also be included.

Particles 6 and 7 used in the present invention are for image expression, and two kinds of charged particles having different colors and charging characteristics may be mixed and injected, respectively. The particles 6 and 7 may be charged with charged or non-chargeable particles. The kind of the particles 6 and 7 is not particularly limited, and any particles used for image expression in the technical field of the present invention may be used. That is, not only a solid but also particles of an electrolyte solution, a suspension, a sol, a gel, a capsule, and a twist ball may be included. Preferably, it is preferable to inject dry particles having no viscous properties such as liquid, suspension and the like. That is, it is more preferable to use dry collision type charged particles in which charged particles are formed by applying a voltage to the upper and lower electrodes after injecting uncharged particles to collide the particles with each other to form a charge due to a collision. .

The electronic paper display device according to the present invention is configured such that when sufficient voltage is applied to the upper electrode and the lower electrode, charged particles 9 charged according to the applied electrode polarity are attracted to each electrode. In addition, although not shown, a color filter may be provided on the top plate to implement red, green, and blue colors for each pixel, and a desired color may be obtained by filtering light transmitted from the charged particles.

In the above description, it should be understood that those skilled in the present invention can only make modifications and changes to the present invention without changing the gist of the present invention as merely illustrative of a preferred embodiment of the present invention.

As described above, according to the present invention, a lower substrate and an upper substrate are disposed to face each other at a predetermined interval; A lower electrode and an upper electrode inscribed to the lower substrate and the upper substrate, respectively; A partition wall which divides pixels between the lower electrode and the upper electrode to form a pixel space; And a plurality of particles encapsulated in the pixel space, wherein the particles have a rough surface modified surface.

According to the present invention, the area of the particles in contact with the lower electrode or the upper electrode can be reduced, the number of contacts using the electrostatic force is reduced, thereby reducing the voltage for driving the particles. In addition, through the surface modification of the particles to improve the crosslinking force of the polymer resin resin to adhere the external additives well, thereby increasing the fluidity of the particles may lower the driving voltage.

Furthermore, if there is a lower insulating layer or upper insulating layer that can be selectively formed on the lower electrode or the upper electrode, the particles can move freely even with a small driving voltage by reducing the area of the particles in contact with the insulating layer. It has an effect.

As such, the present invention provides a new method or a new type of particles that can reduce the magnitude of the voltage applied to the two electrodes to drive the particles by modifying the surface of the particles, thereby securing more margin of the driving circuit. Therefore, it is possible to provide a device of excellent image quality at low cost.

Claims (15)

delete delete delete A lower substrate and an upper substrate disposed to face each other at a predetermined interval; A lower electrode and an upper electrode inscribed to the lower substrate and the upper substrate, respectively; A partition wall which divides the pixel between the lower electrode and the upper electrode to form a pixel space; And It includes; a plurality of particles encapsulated in the pixel space, The particle is an electronic paper display device, characterized in that the surface is rough surface modification by the plasma treatment. The electronic paper display device of claim 4, wherein the plasma treatment is a low temperature plasma or glow discharge treatment. The electronic paper display device according to claim 4, wherein the particles have a porous surface by the plasma treatment. The electronic paper display device according to claim 4, wherein cross-linking or grafting is formed on the surface of the particles by the plasma treatment. The gas used in the plasma treatment is argon (Ar), RF (radio frequency) argon (Ar), helium (He), hydrogen (H ₂ ), oxygen (O ₂ ), nitrogen (N ₂₎ ), Ammonia (NH ₃ ), methane (CH ₄ ), acetylene, acetylene (acetylene), electronic paper display device, characterized in that the gas consisting of a low-temperature RF mixed with hydrogen or nitrogen or a combination thereof. The electronic paper display device according to claim 4, wherein when the gas used for the plasma treatment is an oxygen (O ₂ ) gas, an oxidation reaction occurs or a volatile oxide is generated on the surface of the particle. The electronic paper display device according to claim 4, wherein when the gas used for the plasma treatment is nitrogen (N ₂ ) or argon (Ar) gas, functional groups containing nitrogen are generated on the surface of the particles. The method of claim 4, wherein the gas used in the plasma treatment is argon (Ar) gas, the plasma having a radio frequency (RF), the cone having a height of about 1 ㎛ on the surface of the particle density of 10 ⁹ cm ^-2 Electronic paper display device, characterized in that formed or -CO bond is formed. The electronic paper display device according to claim 4, wherein the surface contact angle of the particles is 50 degrees or less by the plasma treatment. The electronic paper display device according to claim 4, wherein the surface of the particles is hydrophilic by the plasma treatment. The method according to any one of claims 4 to 13, wherein the particles are in a form in which an external additive is spherically enclosed around the polymer resin, and further comprises at least one of dyed pigments, dyes and charge control agents. Electronic paper display device. The electronic paper display device according to any one of claims 4 to 13, wherein the particles are charged or uncharged dry particles.

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