KR20130062792A - Electrophoretic fluid and electronic paper panel having the same - Google Patents

Abstract

PURPOSE: An electrophoretic fluid and an electronic paper panel including the same are provided to realize an environmentally-friendly electrophoretic fluid by including paraffinic oil and isopropyl alcohol in the electrophoretic fluid. CONSTITUTION: An electrophoretic fluid(140) includes dispersion medium(142) and charged particles(141). The dispersion medium includes paraffinic oil and isopropyl alcohol. The charged particles are dispersed in the dispersion medium. The charged particles include black particles(141b) and white particles(141a). The paraffinic oil and the isopropyl alcohol have chemical resistance to polymers or organic pigments.

Description

Electrophoretic fluid and electronic paper panel having the same

The present invention relates to an electronic paper, and to an electrophoretic fluid and an electronic paper panel including the same that can simultaneously improve the dispersion stability and chemical resistance at high temperatures.

Recently, as electronic paper has superior flexibility and portability compared to other display devices, it is radically developing into a next generation display device having paper and display characteristics.

Such electronic paper may include an electrophoresis method and a twist ball method. Here, the electrophoretic electronic paper has excellent advantages in stability and response speed.

Electrophoretic electro paper includes an electrophoretic fluid interposed between an anode and a cathode. Here, the electrophoretic fluid includes a dispersion medium and charged particles dispersed in the dispersion medium. In addition, the charged particles may include white particles and black particles charged with opposite charges to each other. In this case, when an electric field is applied between the anode and the cathode, the white particles and the black particles are moved to electrodes having opposite charges, respectively, to display an image to the user.

Herein, in order to stably disperse the charged particles in the dispersion medium, a polymer is provided on the surface of the charged particles to reduce the specific gravity of the charged particles. This is because the charged particles can settle in the dispersion medium due to the large specific gravity difference between the charged particles and the dispersion medium.

However, as the dispersion medium dissolves or swells the polymer of the charged particles in a high temperature environment, deformation of the charged particles or aggregation between the charged particles may occur. In particular, the agglomeration phenomenon between the charged particles has become a factor that lowers the driving performance or image stability. Furthermore, since the charged particles can be formed of organic pigments, it is more urgent to develop a dispersion medium having both the dispersion stability for the charged particles and the chemical resistance at high temperature.

The present invention is to solve the problems that may occur in the electronic paper, and specifically to provide an electrophoretic fluid and an electronic paper including the same that can improve the dispersion stability and thermal stability at the same time.

It provides an electrophoretic fluid of the solution according to the invention. Electrophoretic fluid according to the present invention is a dispersion medium comprising a paraffinic oil and isopropyl alcohol; And charged particles dispersed in the dispersion medium.

It provides an electronic paper panel of another solution according to the present invention. An electronic paper panel according to the present invention comprises: an array substrate including a first electrode; And an electrophoretic member disposed on the array substrate, the electrophoretic member including a dispersion medium including paraffinic oil and isopropyl alcohol and an electrophoretic fluid including charged particles dispersed in the dispersion medium.

The electrophoretic fluid according to an embodiment of the present invention includes paraffinic oil and isopropyl alcohol, which is environmentally friendly, and can ensure thermal stability and dispersion stability.

In addition, the electronic paper according to the embodiment of the present invention is provided with the electrophoretic fluid, thereby preventing the deterioration of driving performance and image stability in a high temperature environment, it is possible to shorten the driving time.

1 is a schematic cross-sectional view of an electrophoretic member according to a first embodiment of the present invention.
2 is a partial plan view of an array substrate provided in an electronic paper panel according to a second embodiment of the present invention.
3 is a cross-sectional view of an electronic paper panel according to a second embodiment of the present invention.

Embodiments of the present invention will be described in detail with reference to the drawings of the electrophoretic member and the electronic paper panel. The following embodiments are provided by way of example so that those skilled in the art can fully understand the spirit of the present invention.

Therefore, the present invention is not limited to the embodiments described below, but may be embodied in other forms. In the drawings, the size and thickness of the device may be exaggerated for convenience. Like reference numerals designate like elements throughout the specification.

1 is a schematic cross-sectional view of an electrophoretic member according to a first embodiment of the present invention.

Referring to FIG. 1, the electrophoretic member 100 according to the first embodiment of the present invention is interposed between the first and second base layers 110 and 120 and the first and second base layers 110 and 120. The electrophoretic fluid 140 may be included.

Here, one or both of the first and second base layers 110 and 120 may be a film or a substrate. The film may be in a flexible state, and the substrate may be in a rigid state. Here, the first and second base layers 110 and 120 may be the same material or different materials. The material may be a polymer material or glass. Examples of the polymer material may be any one of polycarbonate (PC), polyethylene terephthalate (PET), polyether sulfone (PES), and polyimide film.

However, embodiments of the present invention do not limit the materials of the first and second base layers 110 and 120.

The first and second base layers 110 and 120 may be spaced apart from each other and may face each other.

A partition layer 130 having a receiving portion for accommodating the electrophoretic fluid 140 for each region may be disposed between the first and second substrate layers 110 and 120. The area may be a pixel area that is a minimum unit for displaying an image. In this case, the partition layer 130 may partition the electrophoretic fluid 140 into pixel regions to prevent movement of the electrophoretic fluid 140 between the pixel regions.

The partition layer 130 may be formed of a polyimide-based resin as the photosensitive resin, but is not limited thereto. Here, the partition layer 130 is formed by applying a photosensitive resin on any one of the first substrate layer 110 and the second substrate layer 120 to form a photosensitive resin film, and then using a mask for the photosensitive resin film. An exposure process and a development process may be performed to form a partition wall for forming an accommodation part. Here, the receiving part may be formed to expose the base layer. The partition wall may be formed of a resin.

The electrophoretic fluid 140 may include a dispersion medium 142 and charged particles 141 dispersed in the dispersion medium 142. Here, the charged particles 141 may include black particles 141b and white particles 141a. Here, the charged particles 141 may be made of an inorganic pigment. For example, the black particles 141b may include any one of carbon black, copper oxide, zinc oxide, aniline black, and activated carbon. In addition, the white particles 141a may include any one of barium sulfate, zirconium oxide, aluminum oxide, magnesium oxide, iron oxide, titanium dioxide (TiO 2), and antimony trioxide.

Here, the black particles 141b and the white particles 141a may be charged with opposite charges to each other. For example, the black particles 141b may be charged with a negative charge, and the white particles 141a may be charged with a positive charge.

In addition, the charged particles 141 may include a polymer that is stably dispersed on the dispersion medium 142 or chemically bonded to the surface of the inorganic pigment to control adhesion to the substrate layer. Here, the polymer may be any one of an acrylic urethane resin, an acrylic silicone resin, an acrylic fluorine resin, an acrylic urethane silicone resin, an acrylic urethane fluorine resin, a fluorine resin, a silicone resin, a polyether resin, and a polyurethane resin.

In the embodiment of the present invention, the charged particles 141 is described as being formed of an inorganic pigment, but is not limited thereto, and organic pigments such as phthalocyanine blue and phthalocyanine green may be used.

 The dispersion medium 142 may be made of a transparent liquid. Here, the dispersion medium 142 may select a solvent having better thermal stability than the halocarbon oil used as a conventional dispersion medium. This is because halocarbon-based oils used as conventional dispersion media have chemical resistance at high temperatures, that is, polymers or organic pigments contained in charged particles are dissolved or swelled by a solvent at high temperatures, thereby deteriorating driving performance and image stability. In addition, the dispersion medium 142 may select a solvent that can stably disperse the charged particles 141.

In this case, the dispersion medium 142 may include paraffinic oil and isopropyl alcohol. Here, as an example of the paraffinic oil, any one of isophage (Isopar G, brand name) and isolator (ISOL G, brand name) can be selected. The paraffinic oil and the isopropyl alcohol may have chemical resistance to polymers or organic pigments included in the charged particles 141. Here, when the paraffinic oil is used alone, the driving time of the electronic paper can be increased compared to the conventional due to the viscosity of the paraffinic oil at room temperature. This is because the conventional dispersion medium used halocarbon-based oil, because the paraffinic oil at room temperature has a greater viscosity than halocarbon-based oil.

That is, the dispersion medium is formed by mixing the paraffinic oil and isopropyl alcohol, thereby improving thermal stability and dispersibility, and can also prevent the driving time of the electronic paper from being shortened.

In addition, when isopropyl alcohol is replaced with another alcohol such as methanol or ethanol, there is a problem that the dispersion stability of the charged particles is lowered. That is, the dispersion medium was formed by mixing paraffinic oil and isopropyl alcohol, it was possible to ensure the dispersion stability of the charged particles.

In addition, paraffinic oil and isopropyl alcohol are not only excellent in thermal stability and dispersion stability than conventional halocarbon-based oils, but also have environmentally friendly advantages.

The mixing ratio of paraffinic oil and isopropyl alcohol may be 95/5 to 70/30. That is, the isopropyl alcohol may be mixed at 5 wt% to 30 wt% based on the total weight of the dispersion medium 142, that is, the total weight of paraffinic oil and isopropyl alcohol. At this time, when isopropyl alcohol is mixed at less than 5wt%, the driving time is increased due to the viscosity of the paraffinic oil and there is a problem that the dispersion stability is lowered. In addition, when the isopropyl alcohol exceeds 30wt%, not only the dispersion stability is lowered but also the handleability of the electrophoretic fluid may be lowered because the isopropyl alcohol is a volatile solvent.

The sealing layer 150 may be further disposed between the second base layer 120 and the partition layer 130. Here, the sealing layer 150 may be in close contact with the partition wall covering the receiving portion. Accordingly, the sealing layer 150 may prevent the electrophoretic fluid 140 accommodated in the receiving part from being released to the outside. Here, the sealing layer 150 may be attached on the partition layer 130 through thermocompression bonding. Here, an example of the sealing layer 150 may be a silicone resin or an epoxy resin, but the embodiment is not limited thereto.

In addition, the sealing member 160 is provided along the outer edges of the first and second base layers 110 and 120 facing each other, thereby increasing the bonding force between the first and second base layers 110 and 120. .

In addition, although not shown in the drawing, the electrophoretic member 100 may include a pixel electrode disposed on the inner side of the first base layer 110 and a common electrode disposed on the inner side of the second base layer 120. It may be. In this case, the pixel electrode and the common electrode may be connected to an external circuit, respectively, so that the electrophoretic member 100 may display an image.

The electrophoretic member 100 may further include a common electrode (170 in FIG. 3) on an inner side surface of the second base layer 120. Here, when the electrophoretic member 100 includes the common electrode 170, the first base layer 110 may have a double structure of a release layer and an adhesive layer (110a of FIG. 3). In this case, the electrophoretic member 100 may separate the release layer, and then attach the adhesive layer 110a on the array substrate, thereby easily forming the electronic paper panel.

Hereinafter, an electronic paper display device including an electrophoretic member attached to an array substrate will be described in more detail with reference to FIGS. 2 and 3.

2 is a partial plan view of an array substrate provided in an electronic paper panel according to a second embodiment of the present invention.

3 is a cross-sectional view of the electronic paper display device according to the second embodiment of the present invention corresponding to the line II ′ of FIG. 2. In an embodiment of the present invention, it may include the electrophoretic member of the first embodiment described above. Accordingly, repeated description with respect to the first embodiment will be omitted, and the same reference numerals will be given to the same technical configuration.

Referring to FIG. 2, an electronic paper display device according to an exemplary embodiment of the present invention may include an array substrate 200 and an electrophoretic member 100.

Here, the array substrate 200 may include a plurality of wirings, switching elements, and pixel electrodes disposed on the substrate 210.

The substrate 210 may be made of any one of a plastic film, a plastic substrate, a metal substrate, and a glass substrate, but is not limited thereto.

The plurality of wirings may include a gate wiring 201 and a data wiring 202 disposed to cross each other. The gate line 201 and the data line 202 may be insulated from each other by the gate insulating layer 220. Here, the substrate 210 may include a plurality of pixel regions defined by the intersection of the gate line 201 and the data line 202.

The switching element Tr may be disposed in each pixel area. The switching element Tr may be electrically connected to the gate line 201 and the data line 202. In detail, the switching element Tr may include a gate electrode 203 electrically connected to the gate wiring 201, a gate insulating film 220 disposed on the substrate 210 including the gate electrode 203, and a gate electrode 203. And the source and drain electrodes 205 and 206 disposed on the semiconductor pattern 204 with the channel region interposed between the semiconductor pattern 204 disposed on the gate insulating layer 220 and the semiconductor pattern 204. It may include. Here, the source electrode 205 may be electrically connected to the data line 202.

The passivation layer 230 may be provided on the substrate 210 including the switching element Tr. The passivation layer 230 may be formed of an inorganic layer or an organic layer. The passivation layer 230 may include a contact hole exposing a part of the switching element Tr, particularly a part of the drain electrode 206.

The pixel electrode 240 electrically connected to the drain electrode 206 through the contact hole may be disposed on the passivation layer 230. Here, the pixel electrode 240 may be disposed on each pixel area. The pixel electrode 240 may be made of an alloy including any one or any one of ITO, IZO, copper, and aluminum. However, the material of the pixel electrode 240 is not limited in the embodiment of the present invention.

Here, the switching element Tr is turned on or off by a gate signal applied through the gate line 201 to apply the data voltage supplied through the data line 202 to the pixel electrode 240. Switch.

The electrophoretic member 100 is disposed on the substrate 210 including the pixel electrode 240. Here, the electrophoretic member 100 is disposed on the adhesive layer 110a and the adhesive layer 110a of the first base layer and defined by the barrier layer 130 and the barrier layer 130 defining each pixel region. It may include an electrophoretic fluid 140 disposed in each pixel region, a second base layer 120 disposed on the partition layer 130 including the electrophoretic fluid 140.

Here, the electrophoretic member 100 may include a first base layer formed of a two-layer structure of the adhesive layer 110a and the release layer. In the process of attaching the electrophoretic member 100 on the array substrate 200, the release layer of the first base layer is separated from the electrophoretic member 100 including the adhesive layer 110a. Thereafter, by attaching the electrophoretic member 100 having the release layer removed thereon on the array substrate 200, the electronic paper panel can be easily manufactured.

Here, examples of the material for forming the adhesive layer 110a may include any one or two or more of acrylic resin, epoxy resin, urethane resin, polyester resin, silicone resin, and phenol resin. However, the embodiment of the present invention is not limited thereto.

The electrophoretic fluid 140 may include a dispersion medium 142 including paraffinic oil and isopropyl alcohol, and charged particles 141 dispersed in the dispersion medium 142. Here, isopropyl alcohol may be mixed in an amount of 5 wt% to 30 wt% based on the total weight of the dispersion medium 142.

Accordingly, the electrophoretic fluid 140 may secure dispersion stability and thermal stability.

The charged particles 141 may include white particles 141a and black particles 141b that are charged with mutually opposite charges.

The common electrode 170 is disposed on the inner surface of the second base layer 120. The common electrode 170 may be formed of ITO or IZO.

Here, when the data voltage and the common voltage are applied to the pixel electrode 240 and the common electrode 170, respectively, the black particles 141b and the white particles 141a move toward the electrodes having opposite polarities. Can display black and white.

The sealing layer 150 may be further disposed between the second base layer 120 and the partition layer 130. The sealing layer 150 may seal the electrophoretic fluid 140 accommodated in the accommodation part to prevent the sealing layer 150 from being released to the outside.

In the exemplary embodiment of the present invention, the electrophoretic member 100 is attached to the array substrate 210 to manufacture the electronic paper display, but the present invention is not limited thereto. For example, an electronic paper display device forms a partition layer through a photolithography process on an array substrate, fills an electrophoretic fluid in each pixel region defined by the partition layer, and then includes a common electrode on the partition layer. It may also be produced by attaching a base layer.

Accordingly, as in the embodiment of the present invention, the electronic paper panel includes an electrophoretic fluid including a dispersion medium having thermal stability and dispersion stability, thereby ensuring driving performance and image stability in a high temperature environment, and driving time. This can be shortened as compared with the conventional.

100 electrophoretic member 110 first substrate layer
110a: adhesive layer 120: second substrate layer
130: partition layer 140: electrophoretic fluid
141: charged particle 142: dispersion medium
150: sealing layer 160: sealing member
170: common electrode 200: array substrate
210: substrate Tr: switching element
240: pixel electrode

Claims (8)

Dispersion mediums containing paraffinic oil and isopropyl alcohol; And
Electrophoretic fluid comprising; charged particles dispersed in the dispersion medium.
The method of claim 1,
The isopropyl alcohol is electrophoretic fluid is mixed in 5wt% to 30wt% based on the total weight of the dispersion medium.
The method of claim 1,
The charged particles further comprise an electrophoretic fluid comprising an inorganic pigment and a polymer coated on the surface of the inorganic pigment.
The method of claim 1,
The charged particles are electrophoretic fluid containing an organic pigment.
An array substrate including a first electrode; And
An electrophoretic member disposed on the array substrate, the electrophoretic member including a dispersion medium including paraffinic oil and isopropyl alcohol and an electrophoretic fluid including charged particles dispersed in the dispersion medium;
Electronic paper panel comprising a.
The method of claim 5, wherein
The isopropyl alcohol is an electronic paper panel is mixed in 5wt% to 30wt% based on the total weight of the dispersion medium.
The method of claim 5, wherein
The electrophoretic member is
A first base layer;
A barrier layer disposed on the first base layer and divided into pixel regions;
The electrophoretic fluid filled in the pixel region defined by the barrier layer; And
A second base layer bonded to the partition layer including the electrophoretic fluid;
Electronic paper panel comprising a.
The method of claim 7, wherein
The array substrate includes the first electrode patterned for each pixel region,
The electrophoretic member is an electronic paper panel including a second electrode disposed on the inner surface of the second base layer.

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