WO2007064141A1

WO2007064141A1 - Apparatus for emitting electrowetting display

Info

Publication number: WO2007064141A1
Application number: PCT/KR2006/005087
Authority: WO
Inventors: Jang-Ho Kim; Seung-Rok Shin; Hyun-Ha Hwang
Original assignee: Image Lab Co., Ltd.
Priority date: 2005-11-30
Filing date: 2006-11-29
Publication date: 2007-06-07
Also published as: KR100646810B1

Abstract

An apparatus for light emissive electrowetting display includes: a first and a second substrate arranged apart in parallel with a certain distance; a first and a second fluid which are placed between the first and second substrates, one of them at the least has conductivity or polarity, and does not mix with each other; a first electrode and a second electrode used to apply voltage to each of the first and second fluid respectively; an insulating layer disposed between the second fluid and the first electrode; and since the first substrate is comprised of further including the emissive layer so printed in the inner side thereof with emissive materials as to get color patterns, the present invention is intended to display an image on such a way that a phosphor to emit light by UV irradiation is printed on the surface and the surface area of the fluid is controlled using electrowetting phenomenon.

Description

APPARATUS FOR EMITTING ELECTROWETTING DISPLAY

Technical Field

[1] The invention relates to light emissive electrowetting devices and, more specifically, to light emissive display devices that incorporate a printed phosphor to emit light by UV irradiation with controlling the surface area of fluids using electrowetting phenomenon so as to display an image appropriately. Background Art

[2] Fig. 1 is a schematic diagram to depict a conventional active matrix emissive LCD, a prior art disclosed in the Korean Patent Publication No. 1997-0016689.

[3] As shown in Fig. 1, it is composed of liquid crystal display 30, a light source of bottom-emission 21 to generate excitons disposed at a rear side of the liquid crystal display 30, a front glass 29 placed in the fore side so as to protect the liquid crystal display 30, and a printed active emissive part 27 so as to have color patterns inside the front glass 29.

[4] The liquid crystal display 30 includes a first substrate 31, a second substrate 37 arranged apart facing the first substrate, a first electrode 32 formed with a plurality of striped patterns inside the first substrate 31, a second electrode 36 formed with a plurality of striped patterns inside the second substrate arranged perpendicular to those of the first electrode, a first alignment layer 33 formed on the first substrate 31 while covering the first electrode 32, a second alignment layer 35 formed on the second substrate 37 while covering the second electrode 36, a liquid crystal layer 34 inserted between the first 35 and the second alignment layer 36 and aligned along the predetermined direction by rubbing method.

[5] The conventional technology has improved such characteristics as brightness, contrast ratio and viewing angle through the innovation of manufacturing method, printing a laser paint instead of traditional color filter among a variety of constituent factors in LCD.

[6] However, this kind of the conventional technology had the following problems.

[7] That is, it inherently has a low optical efficiency due to the structure of using a pair of polarizers.

[8] A slow switching time of liquid crystal also deteriorates the performance of emissive materials.

[9] Further, it has some reliability issues that liquid crystal becomes deteriorated due to the exposure of UV light.

[10] As a schematic diagram of display device utilizing the conventional electrowetting phenomenon, Fig. 2 shows a prior art disclosed in the Japanese Patent Publication No. 2004-287008, where (a) is a normal bright state of the colored water droplet when Sl is switched off, (b) is a dark state when S 1 is switched on.

[11] As shown in Fig. 2, it is a display device making use of electro wetting phenomenon, which includes a first transparent substrate 12 placed in the bottom layer of the display device, a first transparent electrode 14 installed on the first substrate 12, an insulating layer 16 consisting of an insulation film 16a and a film of low surface e nergy 16b, a second transparent electrode 15 on the insulating layer 16, a cavity 17 enclosing the second transparent electrode 15 with a certain gap, a second transparent substrate 18 to form the uppermost layer placed upon the cavity 17, a colored water droplet W injected into the gap inside the cavity 17, the size of which the water droplet is varied by the application of electricity.

[12] Where unexplained mark 10 represents a display device, E means a direct current power source, and Sl is a switch.

[13] However, this kind of conventional technology had some drawbacks as follows.

[14] That is, it is difficult to control the location of water droplet precisely since only a first fluid is implemented by the surface tension by which water forms a spherical droplet when no electricity is applied and water spreads when electricity is applied.

[15] Further, it has a limitation of monochrome display because colored water droplet plays a role of blocking the incident light. Disclosure of Invention

Technical Problem

[16] Accordingly, the present invention is to solve the aforementioned problems of the conventional art, and it is an object of the present invention to provide a light emissive electrowetting display apparatus which incorporates a printed phosphor to emit light by UV irradiation with controlling the surface area of fluids using electrowetting phenomenon so as to display an image appropriately. Technical Solution

[17] In an aspect of the present invention, there is provided an apparatus for light emissive electrowetting display including:

[18] a first and a second substrate arranged apart in parallel with a certain distance; a first and a second fluid which is placed between the first and second substrates, one of them at the least has conductivity or polarity, and does not mix with each other; a first and a second electrode to apply voltage to each of the fluids respectively; an insulating layer placed between the second fluid and the second electrode, and there is a characteristic of technical construction that the first substrate is comprised of an emissive layer where an emissive substance is printed inside to get color patterns. Advantageous Effects

[19] As looked over hereinafter, according to a light emissive electrowetting display apparatus of the present invention, there is an advantage that it can display an image through controlling the surface area of fluids using electrowetting phenomenon incorporated by a phosphor which is printed on the substrate and emits light by UV irradiation.

[20] In the meantime, various kind of conventional display devices like

STN(Super-Twisted Nematic) LCD, TFT(TMn-FiIm Transistor) LCD, PDP(Plasma Display Panel), FED(Field Emission Display), OLED(Organic Light Emitting Diode), Electrophoretic Display and Electrochromic Display, etc. are in mass production or under development. Among them, particularly while LCD is occupying a majority of market in the display devices, it has some problems like low optical efficiency due to use of polarizers, viewing angle dependence, and the emissive devices such as PDP, OLED have also some issues of a limited resolution, brightness, power consumption, and reliability. Thus, the present invention is related to a display device to control the light intensity of aperture region through varying the surface area of fluids using electrowetting phenomenon, more specifically to an emissive structure. According to the present invention, there is another advantage that it has an excellent performance in brightness, viewing angle, power consumption, high resolution, and high contrast ratio, and is good at moving picture representation, as well as being applicable to that of flexible substrate.

[21] Also, compared with the conventional emissive devices, the present invention has another advantage that is superior to PDP in the aspects of power consumption and high resolution, and has much better durability than OLED while OLED shows a sharp deterioration of device characteristics if its luminescent substance is exposed to the moisture or the air. Brief Description of the Drawings

[22] Fig. 1 is a sectional view for illustrating a constitution of the conventional light emissive active liquid crystal display apparatus.

[23] Fig. 2 is schematic drawings of the conventional display device using electrowetting phenomenon, where (a) illustrates a normal bright state of colored water droplet when the switch S 1 is off, and (b) illustrates a dark state when the switch S 1 is on.

[24] Fig. 3 is a schematic diagram to illustrate an apparatus for light emissive electrowetting display embodied by the present invention.

[25] Fig. 4 is a schematic drawing to illustrate an apparatus for light emissive electrowetting display in accordance with one embodiment of the present invention. [26] Fig. 5 is a schematic view showing an operation mechanism of the present invention when a pixel is off-state in Fig. 4.

[27] Fig. 6 is a schematic view showing an operation mechanism of the present invention when a pixel is on-state in Fig. 4.

[28] Fig. 7 is a schematic drawing for illustrating how color is represented in Fig. 4.

[29] Fig. 8 is a schematic view to illustrate an apparatus for light emissive electrowetting display in accordance with another embodiment of the present invention.

[30] Fig. 9 is a schematic view showing an operation mechanism of the present invention when a pixel is on-state in Fig. 8.

[31] Fig. 10 is a schematic view showing an operation mechanism of the present invention when a pixel is off-state in Fig. 8.

[32] Fig. 11 is a schematic drawing for illustrating how color is represented in Fig. 8.

[33] Fig. 12 is a schematic view to illustrate an apparatus for light emissive electrowetting display in accordance with another embodiment of the present invention.

[34] Fig. 13 is a schematic view showing an operation mechanism of the present invention when a pixel is off-state in Fig. 12.

[35] Fig. 14 is a schematic view showing an operation mechanism of the present invention when a pixel is on-state in Fig. 12.

[36] Fig. 15 is a schematic drawing for illustrating how color is represented in Fig. 12.

Mode for the Invention

[37] Hereinafter, according to the technological initiatives of an apparatus for light emissive electrowetting display, exemplary embodiments of the present invention will be described in detail with reference to the annexed drawings.

[38] Fig. 3 is a schematic diagram to illustrate an apparatus for light emissive electrowetting display embodied by the present invention.

[39] As shown in Fig. 3, it is featured by the construction including: a first and a second substrate 100 and 200 arranged apart in parallel with a certain distance; a light emissive elelctrowetting element 300 to display an image through controlling the surface area of fluids using electrowetting phenomenon, disposed between the first and second substrates 100 and 200.

[40] The apparatus for light emissive electrowetting display is also characterized by the constitution including a light source 400 to be used to generate excitons, installed outside the first or second substrates 100 and 200.

[41] Fig. 4 is a schematic drawing to illustrate an apparatus for light emissive electrowetting display in accordance with one embodiment of the present invention.

[42] As shown in Fig. 4, it is characterized by the constitution including: a first and a second substrate 100 and 200 arranged apart in parallel with a certain distance; a first and a second fluid 311 and 312 which is placed between the first and second substrates 100 and 200, one of them at the least has conductivity or polarity, and does not mix with each other; a first and a second electrode 321 and 322 to apply voltage to each of the fluids 311 and 312 respectively; an insulating layer 331 placed between the second fluid 312 and the second electrode 322, and the first substrate 100 is featured by the construction of an emissive layer 112 where an emissive substance is printed inside to get color patterns.

[43] For the first and second fluid 311 and 312, one is made up of substances to cut off the light and the other is made up of substances to transmit the light.

[44] The substances to cut off the light are characterized in that they are comprised of one or a combination of more than two oxides such as ZnO, TiO , Fe O , MgO.

2 2 3

[45] The apparatus for light emissive electrowetting display is formed to separate the first fluid 311 from the second fluid 312, and each pixel has its own partition 313 on the periphery to play a role of distributing the fluid uniformly.

[46] The partition 313 is made up of hydrophilic materials.

[47] The light emissive layer 112 is formed to have patterns printed with a combination of more than two emissive materials such as Red, Green, Blue, Cyan, Magenta, Yellow and White.

[48] The first substrate 100 further includes a black matrix(BM) 111 disposed between the emissive layers to absorb UV light.

[49] Also, the apparatus for light emissive electrowetting display includes a light source

400 to be used to generate excitons, installed outside the first or second substrates 100 and 200.

[50] The light source 400 is composed of UV light emitting diode.

[51] Fig. 8 is a schematic view to illustrate an apparatus for light emissive electrowetting display in accordance with another embodiment of the present invention.

[52] As shown in Fig. 8, a first and a second substrate 100 and 200 arranged apart in parallel with a certain distance; a first and a second fluid 311 and 312 which is placed between the first and second substrates 100 and 200, one of them at the least has conductivity or polarity, and does not mix with each other; a first and a second electrode 321 and 322 to apply voltage to each of the fluid 311 and 312 respectively; an insulating layer 331 placed between the second fluid 312 and the second electrode 322, and a light emissive material is mixed with one of the first and second fluid.

[53] For the first and second fluid 311 and 312, one is made up of substances to cut off the light and the other is made up of substances to transmit the light.

[54] The substances to cut off the light are characterized in that they are comprised of one or a combination of more than two oxides such as ZnO, TiO 2 , Fe 2 O 3 , MgO.

[55] The apparatus for light emissive electrowetting display is formed to separate the first fluid 311 from the second fluid 312, and each pixel has its own partition 313 on the periphery to play a role of distributing the fluid uniformly.

[56] The partition 313 is made up of hydrophilic materials.

[57] The fluid mixed with light emissive materials is formed to have a combination of more than two emissive materials such as Red, Green, Blue, Cyan, Magenta, Yellow and White.

[58] The first substrate 100 further includes a black matrix(BM) 111 disposed between the emissive layers to absorb UV light.

[59] Also, the apparatus for light emissive electrowetting display includes a light source

[60] The light source 400 is composed of UV light emitting diode.

[61] Fig. 12 is a schematic view to illustrate an apparatus for light emissive electrowetting display in accordance with another embodiment of the present invention.

[62] As shown in Fig. 12, there is provided with the apparatus for light emissive electrowetting display comprising: a first and a second substrate 100 and 200 arranged apart in parallel with a certain distance; a first and a second fluid 311 and 312 which is placed between the first and second substrates 100 and 200, one of them at the least has conductivity or polarity, and does not mix with each other; a first and a second electrode 321 and 322 to apply voltage to each of the fluid 311 and 312 respectively; an insulating layer 331 placed between the second fluid 312 and the second electrode 322; the light source 400 which is used to generate excitons and holds R, G, B patterns to be corresponded to each pixel, installed outside the first or second substrates 100 and 200.

[63] For the first and second fluid 311 and 312, one is made up of substances to cut off the light and the other is made up of substances to transmit the light.

[64] The substances to cut off the light are characterized in that they are comprised of one or a combination of more than two oxides such as ZnO, TiO , Fe O , MgO.

2 2 3

[65] The apparatus for light emissive electrowetting display is formed to separate the first fluid 311 from the second fluid 312, and each pixel has its own partition 313 on the periphery to play a role of distributing the fluid uniformly. [66] The partition 313 is made up of hydrophilic materials.

[67] The light source 400 is formed to have a combination of more than two emissive materials such as Red, Green, Blue, Cyan, Magenta, Yellow and White. [68] The light source 400 is composed of UV light emitting diode.

[69] The operation of the apparatus for light emissive electrowetting display in accordance with the present invention will be described in detail with reference to the annexed drawings. [70] First of all, the present invention is intended to display an image on such a way that a phosphor to emit light by UV irradiation is printed on the surface and the surface area of the fluid is controlled using electrowetting phenomenon.

[71] Fig. 3 schematically shows the diagram of an apparatus for light emissive electrowetting display in accordance with the present invention.

[72] Therefore the first and second substrates 100 and 200 are arranged apart in parallel with a certain distance, thereby being separated with a spacing from each other.

[73] And the light emissive elelctrowetting element 300 disposed between the first and second substrates 100 and 200 is used to display an image through controlling the surface area of fluids using electrowetting phenomenon.

[74] Also, the light source 400 installed outside of the first or second substrates 100 and

200 is used to generate excitons.

[75] The construction and operation of the present invention will be described in detail with reference to the following practiced examples.

[76] <Example 1>

[77] Fig. 4 is a schematic drawing to illustrate the apparatus for light emissive electrowetting display in accordance with one embodiment of the present invention, and Fig. 5 is a schematic view showing an operation mechanism of the present invention when a pixel is off-state in Fig. 4, and Fig. 6 is a schematic view showing an operation mechanism of the present invention when a pixel is on-state in Fig. 4, and Fig. 7 is a schematic drawing for illustrating how color is represented in Fig. 4.

[78] Therefore the first and second substrates 100 and 200 are arranged apart in parallel with a certain distance.

[79] And a first and a second fluid 311 and 312 which is placed between the first and second substrates 100 and 200, one of them at the least has conductivity or polarity, and does not mix with each other. Accordingly the example 1 shows one embodiment of the present invention that the first fluid 311 is disposed in the lower part of the first substrate 100 and the second fluid 312 is disposed on the upper part of the second substrate 200.

[80] Also, a first and a second electrode 321 and 322 are used to apply voltage to each of the fluid 311 and 312 respectively. Therefore, referring to example 1, the first electrode 321 is formed between the first substrate 100 and the first electrode 311 so as to apply voltage to the first fluid 311 and the second electrode 322 is formed between the second substrate 200 and the second electrode 312 so as to apply voltage to the second fluid 312. And these electrodes 321 and 322 function to distribute uniformly the fluid in each pixel. Further a gray scale is performed by varying the magnitude of voltage applied to the electrodes 321 and 322.

[81] Also, an insulating layer 331 is formed between the second fluid 312 and the second electrode 322 so as to do a function of insulation.

[82] Referring to example 1, an emissive layer 112 is also formed to get color patterns, which can be printed on the first substrate 100 with such emissive materials as R, G, B phosphors.

[83] All the distinctive features of the example 1 will be explained more in detail as follows.

[84] 1) For the first and second fluid 311 and 312, one is made up of substances to cut off the light and the other is made up of substances to transmit the light. For example, the first fluid 311 can be composed of substances to cut off the light and the second fluid 312 can be composed of substances to transmit the light. There are two kinds of way to cut off the light(e.g. UV light), one is that the light is absorbed chemically by the substances and the other is that the light is reflected or scattered physically by the substances. Thus as the substances of the second fluid 312 desired to cut off the light, such oxides like ZnO, TiO , Fe O , MgO. can be used, which belongs to the type of reflecting or scattering UV light physically.

[85] 2) Also, the partition 313 which is formed with a certain height so as to separate the first fluid 311 from the second fluid 312 plays a role of distributing the fluid uniformly within each pixel. Therefore, Fig. 4 or Fig. 7 shows an instance of which the partition 313 is formed to distribute the second fluid 312 uniformly. This kind of partition 313 is comprised of hydrophilic materials. And the partition 313 can not only be set up with a height to distinguish the second fluid 312, but also be established with a height to isolate both the first and second fluid 311 and 312. Of course, the present invention can be realized without this physically-constructed partition 313.

[86] 3) Also, referring to example 1, the emissive layer 112 is formed to get patterns printed with a combination of more than two emissive materials among which are included Red(R), Green(G), Blue(B), Cyan(C), Magenta(M), Yellow(Y) and White. It is to be desired that such patterns as RGB, CMY, RGBCMY, RGB + White, RGBCMY + White should be formed. The size of every pixel printed with such emissive materials can be the same or different from each other.

[87] 4) Also, the first substrate 100 is comprised of further including the black matrix(BM) 111 formed with UV cutting-off layer, thereby contributing to improve the display quality of the emissive layer 112.

[88] 5) The light source 400 is installed outside of the first or second substrates 100 and

200 and is used to generate excitons. Fig. 4 or Fig. 7 shows an instance of which excitons are generated from the light source 400 installed outside of the second substrate 200. This light source 400 can be made up of UV emitting diodes or flat fluorescent lamps.

[89] 6) Therefore, the operation principle of example 1 can be described as follows. [90] a) Pixel off

[91] When the voltage is not applied, the second fluid 312 is distributed on the whole area of a pixel and the UV light emitted from the light source 400 is cut off by the second fluid 312 (Refer to Fig. 5).

[92] b) Pixel on

[93] When the voltage is applied to the first and second electrodes 321 and 322, the second fluid 312 is pushed to move by the influence of surface tension of the first fluid 311. Thus the UV light emitted from the light source 400 passes through the pixel and illuminates the emissive layer 312 coated on the first substrate 100, so that the emissive layer 312 emits the fluorescent light of its own proper spectrum. (Refer to Fig. 6)

[94] <Example 2>

[95] Fig. 8 is a schematic drawing to illustrate the apparatus for light emissive elec- trowetting display in accordance with another embodiment of the present invention, and Fig. 9 is a schematic view showing an operation mechanism of the present invention when a pixel is off-state in Fig. 8, and Fig. 10 is a schematic view showing an operation mechanism of the present invention when a pixel is on-state in Fig. 8, and Fig. 11 is a schematic drawing for illustrating how color is represented in Fig. 8.

[96] Therefore the first and second substrates 100 and 200 are arranged apart in parallel with a certain distance.

[97] And a first and a second fluid 311 and 312 which is placed between the first and second substrates 100 and 200, one of them at the least has conductivity or polarity, and does not mix with each other. Accordingly the example 1 shows one embodiment of the present invention that the first fluid 311 is disposed in the lower part of the first substrate 100 and the second fluid 312 is disposed on the upper part of the second substrate 200.

[98] Also, a first and a second electrode 321 and 322 are used to apply voltage to each of the fluid 311 and 312 respectively. Therefore, referring to example 1, the first electrode 321 is formed between the first substrate 100 and the first electrode 311 so as to apply voltage to the first fluid 311 and the second electrode 322 is formed between the second substrate 200 and the second electrode 312 so as to apply voltage to the second fluid 312. And these electrodes 321 and 322 function to distribute uniformly the fluid in each pixel. Further a gray scale is performed by varying the magnitude of voltage applied to the electrodes 321 and 322.

[99] Also, an insulating layer 331 is formed between the second fluid 312 and the second electrode 322 so as to do a function of insulation.

[100] Referring to example 2, the emissive materials, mingled with one of the first and second fluid, are composed of the substances which emit R, G, B spectrum in response to the illumination of UV light or emit C, M, Y spectrum in response to that of UV light.

[101] All the distinctive features of the example 2 will be explained more in detail as follows.

[102] 1) For the first and second fluid 311 and 312, one is made up of substances to cut off the light and the other is made up of substances to transmit the light. For example, the first fluid 311 can be composed of substances to cut off the light and the second fluid 312 can be composed of substances to transmit the light. There are two kinds of way to cut off the light(e.g. UV light), one is that the light is absorbed chemically by the substances and the other is that the light is reflected or scattered physically by the substances. Thus as the substances of the second fluid 312 desired to cut off the light, such oxides like ZnO, TiO , Fe O , MgO. can be used, which belongs to the type of reflecting or scattering UV light physically.

[103] 2) Also, the partition 313 which is formed with a certain height so as to separate the first fluid 311 from the second fluid 312 plays a role of distributing the fluid uniformly within each pixel. Therefore, Fig. 4 or Fig. 7 shows an instance of which the partition 313 is formed to distribute the second fluid 312 uniformly. This kind of partition 313 is comprised of hydrophilic materials. And the partition 313 can not only be set up with a height to distinguish the second fluid 312, but also be established with a height to isolate both the first and second fluid 311 and 312. Of course, the present invention can be realized without this physically-constructed partition 313.

[104] 3) Also, referring to example 2, the emissive materials to be mixed with the fluid are formed to have a combination of more than two emissive substances among which are included Red(R), Green(G), Blue(B), Cyan(C), Magenta(M), Yellow(Y) and White. It is to be desired that such patterns as RGB, CMY, RGBCMY, RGB + White, RGBCMY + White should be formed. The size of every pixel printed with such emissive materials can be the same or different from each other.

[105] 4) Also, the first substrate 100 is comprised of further including the black matrix(BM) 111 formed with UV cutting-off layer, thereby contributing to improve the display quality of the emissive layer 112.

[106] 5) The light source 400 is installed outside of the first or second substrates 100 and

200 and is used to generate excitons. Fig. 8 or Fig. 11 shows an instance of which excitons are generated from the light source 400 installed outside of the second substrate 200. This light source 400 can be made up of UV emitting diodes or flat fluorescent lamps.

[107] 6) Therefore, the operation principle of example 1 can be described as follows.

[108] a) Pixel on

[109] When the voltage is not applied, the UV light emitted from the light source 400 is illuminated into the fluid mixed with the emissive materials and the fluid mingled with the emissive substances radiates their own proper spectrum. (Refer to Fig. 9).

[110] b) Pixel off

[111] When the voltage is applied to the first and second electrodes 321 and 322, the second fluid 312 is pushed to move by the influence of surface tension of the first fluid 311. Thus the UV light emitted from the light source 400 is absorbed into the black matrix 111 which is coated on the first substrate 100 for the purpose of cutting off UV light, so that the dark state is displayed on the pixel. Th fluid, a mixture of emissive materials, is moved to one side and aggregated under the black matrix 111. (Refer to Fig. 10)

[112] <Example 3>

[113] Fig. 12 is a schematic drawing to illustrate the apparatus for light emissive elec- trowetting display in accordance with another embodiment of the present invention, and Fig. 13 is a schematic view showing an operation mechanism of the present invention when a pixel is off-state in Fig. 12, and Fig. 14 is a schematic view showing an operation mechanism of the present invention when a pixel is on-state in Fig. 12, and Fig. 15 is a schematic drawing for illustrating how color is represented in Fig. 12.

[114] Therefore the first and second substrates 100 and 200 are arranged apart in parallel with a certain distance.

[115] And a first and a second fluid 311 and 312 which is placed between the first and second substrates 100 and 200, one of them at the least has conductivity or polarity, and does not mix with each other. Accordingly the example 1 shows one embodiment of the present invention that the first fluid 311 is disposed in the lower part of the first substrate 100 and the second fluid 312 is disposed on the upper part of the second substrate 200.

[116] Also, a first and a second electrode 321 and 322 are used to apply voltage to each of the fluid 311 and 312 respectively. Therefore, referring to example 1, the first electrode 321 is formed between the first substrate 100 and the first electrode 311 so as to apply voltage to the first fluid 311 and the second electrode 322 is formed between the second substrate 200 and the second electrode 312 so as to apply voltage to the second fluid 312. And these electrodes 321 and 322 function to distribute uniformly the fluid in each pixel. Further a gray scale is performed by varying the magnitude of voltage applied to the electrodes 321 and 322.

[117] Also, an insulating layer 331 is formed between the second fluid 312 and the second electrode 322 so as to do a function of insulation.

[118] Referring to example 3, the light source 400 of which is comprised R, G, B patterns corresponding to each of the pixel illuminates R, G, B light from bottom side of each pixel. Both the light source 400 and pixel structures can be constructed with such various configurations as striped type, delta type, and honeycomb type, etc.

[119] All the distinctive features of the example 3 will be explained more in detail as follows.

[120] 1) For the first and second fluid 311 and 312, one is made up of substances to cut off the light and the other is made up of substances to transmit the light. For example, the first fluid 311 can be composed of substances to cut off the light and the second fluid 312 can be composed of substances to transmit the light. There are two kinds of way to cut off the light(e.g. UV light), one is that the light is absorbed chemically by the substances and the other is that the light is reflected or scattered physically by the substances. Thus as the substances of the second fluid 312 desired to cut off the light, such oxides like ZnO, TiO , Fe O , MgO. can be used, which belongs to the type of reflecting or scattering UV light physically.

[121] 2) Also, the partition 313 which is formed with a certain height so as to separate the first fluid 311 from the second fluid 312 plays a role of distributing the fluid uniformly within each pixel. Therefore, Fig. 4 or Fig. 7 shows an instance of which the partition 313 is formed to distribute the second fluid 312 uniformly. This kind of partition 313 is comprised of hydrophilic materials. And the partition 313 can not only be set up with a height to distinguish the second fluid 312, but also be established with a height to isolate both the first and second fluid 311 and 312. Of course, the present invention can be realized without this physical partition 313.

[122] 3) Also, referring to example 1, the emissive layer 112 is formed to get patterns printed with a combination of more than two emissive materials among which are included Red(R), Green(G), Blue(B), Cyan(C), Magenta(M), Yellow(Y) and White. It is to be desired that such patterns as RGB, CMY, RGBCMY, RGB + White, RGBCMY + White should be formed. The size of every pixel printed with such emissive materials can be the same or different from each other. The light source 400 is installed outside of the first or second substrates 100 and 200 and is used to generate excitons. Fig. 12 or Fig. 15 shows an instance of which excitons are generated from the light source 400 installed outside of the second substrate 200. This light source 400 can be made up of UV emitting diodes or flat fluorescent lamps.

[123] 4) Therefore, the operation principle of example 3 can be described as follows.

[124] a) Pixel off

[125] When the voltage is not applied, the second fluid 312 is distributed on the whole area of a pixel and the UV light emitted from the light source 400 is cut off by the second fluid 312 (Refer to Fig. 13).

[126] b) Pixel on

[127] When the voltage is applied to the first and second electrodes 321 and 322, the second fluid 312 is pushed to move by the influence of surface tension of the first fluid 311. Thus the light of specific spectrum illuminated by the external light source 400 is transmitted and is displayed as colors. (Refer to Fig. 14)

[128] Accordingly, the present invention relates to the light emissive display devices that incorporate a printed phosphor to emit light by UV irradiation with controlling the surface area of fluids using electrowetting phenomenon so as to display an image appropriately.

[129] Hereinbefore, while the present invention has been described within the limits of the desired embodiments in accordance with itself, it should be understood that various changes, substitutions, and alterations can be made hereto without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

[1] An apparatus for light emissive electrowetting display comprising: a first and a second substrate arranged apart in parallel with a certain distance; a first and a second fluid which are placed between the first and second substrates, one of them at the least has conductivity or polarity, and does not mix with each other; a first electrode and a second electrode used to apply voltage to each of the first and second fluid respectively; an insulating layer disposed between the second fluid and the second electrode; and an emissive layer which is composed of patterns printed with emissive materials so as to get color patterns on the inner side of the first substrate.

[2] The apparatus for light emissive electrowetting display according to claim 1, wherein the first and second fluid are featured by their constructions that one is made up of the substances to cut off a light, the other is made up of the substances to transmit a light.

[3] The apparatus for light emissive electrowetting display according to claim 2, wherein the substances to cut off the light are comprised of one or a combination of more than two oxides such as ZnO, TiO , Fe O , MgO.

[4] The apparatus for light emissive electrowetting display according to claim 1, wherein the apparatus for light emissive electrowetting display is featured by the construction further including the partition which is so formed with a certain height as to separate the first fluid or the second fluid and plays a role of distributing the fluid uniformly within each pixel.

[5] The apparatus for light emissive electrowetting display according to claim 4, wherein the partition is comprised of hydrophilic materials.

[6] The apparatus for light emissive electrowetting display according to claim 1, wherein the emissive layer is formed to get patterns printed with a combination of more than two emissive materials among which are included Red(R), Green(G), Blue(B), Cyan(C), Magenta(M), Yellow(Y) and White.

[7] The apparatus for light emissive electrowetting display according to claim 1, wherein the first substrate is comprised of further including the black matrix(BM) formed with UV cutting-off layer.

[8] The apparatus for light emissive electrowetting display according to one of claims 1 to 7, wherein the apparatus for light emissive electrowetting display is further comprised of the light source which is installed outside of the first substrate or the second substrate and is used to generate excitons.

[9] The apparatus for light emissive electrowetting display according to claim 8, wherein the light source is composed of UV light emitting diodes.

[10] An apparatus for light emissive electrowetting display comprising: a first and a second substrate arranged apart in parallel with a certain distance; a first and a second fluid which are placed between the first and second substrates, one of them at the least has conductivity or polarity, and does not mix with each other; a first electrode and a second electrode used to apply voltage to each of the first and second fluid respectively; an insulating layer disposed between the second fluid and the first electrode; and emissive materials are mingled with one of the first fluid or the second fluid.

[11] The apparatus for light emissive electrowetting display according to claim 10, wherein the first and second fluid are featured by their constructions that one is made up of the substances to cut off a light, the other is made up of the substances to transmit a light

[12] The apparatus for light emissive electrowetting display according to claim 11, wherein the substances to cut off the light are comprised of one or a combination of more than two oxides such as ZnO, TiO , Fe O , MgO.

[13] The apparatus for light emissive electrowetting display according to claim 10, wherein the apparatus for light emissive electrowetting display is featured by the construction further including the partition which is so formed with a certain height as to separate the first fluid or the second fluid and plays a role of distributing the fluid uniformly within each pixel.

[14] The apparatus for light emissive electrowetting display according to claim 13, wherein the partition is comprised of hydrophilic materials.

[15] The apparatus for light emissive electrowetting display according to claim 10, wherein the fluid mixed with the emissive materials is formed to have a combination of more than two emissive substances among which are included Red(R), Green(G), Blue(B), Cyan(C), Magenta(M), Yellow(Y) and White.

[16] The apparatus for light emissive electrowetting display according to claim 10, wherein the first substrate is comprised of further including the black matrix(BM) formed with UV cutting-off layer.

[17] The apparatus for light emissive electrowetting display according to one of claims 10 or claim 16, wherein the apparatus for light emissive electrowetting display is further comprised of the light source which is installed outside of the first substrate or the second substrate and is used to generate excitons.

[18] The apparatus for light emissive electrowetting display according to claim 17, wherein the light source is composed of UV light emitting diodes.

[19] An apparatus for light emissive electrowetting display comprising: a first and a second substrate arranged apart in parallel with a certain distance; a first and a second fluid which are placed between the first and second substrates, one of them at the least has conductivity or polarity, and does not mix with each other; a first electrode and a second electrode used to apply voltage to each of the first and second fluid respectively; an insulating layer disposed between the second fluid and the second electrode; and the light source installed outside of the first substrate or the second substrate, used to generate excitons, and comprising R, G, B patterns corresponding to each of the pixel.

[20] The apparatus for light emissive electrowetting display according to claim 19, wherein the first and second fluid are featured by their constructions that one is made up of the substances to cut off a light, the other is made up of the substances to transmit a light.

[21] The apparatus for light emissive electrowetting display according to claim 20, wherein the substances to cut off the light are comprised of one or a combination of more than two oxides such as ZnO, TiO , Fe O , MgO.

2 2 3

[22] The apparatus for light emissive electrowetting display according to claim 19, wherein the apparatus for light emissive electrowetting display is featured by the construction further including the partition which is so formed with a certain height as to separate the first fluid or the second fluid and plays a role of distributing the fluid uniformly within each pixel.

[23] The apparatus for light emissive electrowetting display according to claim 22, wherein the partition is comprised of hydrophilic materials.

[24] The apparatus for light emissive electrowetting display according to claim 19, wherein the light source is formed to have a combination of more than two color patterns among which are included Red(R), Green(G), Blue(B), Cyan(C), Magenta(M), Yellow(Y) and White.

[25] The apparatus for light emissive electrowetting display according to one of claims 19 to 24, wherein the light source is composed of UV light emitting diodes.