JP4399962B2 - Electrophoretic display device and manufacturing method thereof - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to an electrophoretic display device and a manufacturing method thereof, and more particularly to a flexible and lightweight electrophoretic display device and a method capable of easily manufacturing such an electrophoretic display device.
[0002]
[Prior art]
Conventionally, an electrophoretic display panel using an electrophoretic phenomenon is known. In the electrophoretic display panel, electrophoretic particles having a positive or negative charge are enclosed, and by applying an electric field to the electrophoretic particles, the electrophoretic display panel collects them on the display surface side of the electrophoretic display panel, Alternatively, a desired figure or the like can be displayed by moving away from the display surface side of the electrophoretic display panel.
[0003]
Known electrophoretic particles used in the electrophoretic display panel include titanium oxide, carbon black, bitumen, and phthalocyanine green. Electrophoretic particles made of such materials are mixed in a liquid dispersion medium such as alcohol solvents, esters, aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons, and the like. An electrophoretic display panel is configured by being sandwiched by the lower panel.
[0004]
However, if the liquid dispersion medium in which the electrophoretic particles are mixed is simply sandwiched between the upper panel and the lower panel, the electrophoretic particles are aggregated and display unevenness occurs. For this reason, in a conventional electrophoretic display panel, a lattice-like spacer is interposed between the upper panel and the lower panel, and the liquid dispersion medium mixed with the electrophoretic particles is confined in each cell partitioned by the spacer. As a result, aggregation of the electrophoretic particles is prevented and display unevenness is prevented. Further, as another method for preventing the occurrence of display unevenness due to aggregation of electrophoretic particles, a method using a microcapsule and confining a liquid dispersion medium in which the electrophoretic particles are mixed in the microcapsule is known. (See JP-A-1-86116). According to this method, since the microcapsules themselves do not substantially move, the occurrence of display unevenness can be prevented as in the case of using a lattice spacer.
[0005]
Thus, conventionally, a grid-like spacer is interposed between the upper panel and the lower panel, and the liquid dispersion medium in which the electrophoretic particles are mixed in each cell partitioned by the spacer is used, or a microcapsule is used. By confining the liquid dispersion medium in which the electrophoretic particles are mixed in the microcapsule, the electrophoretic particles are prevented from agglomerating and display unevenness is prevented.
[0006]
[Problems to be solved by the invention]
However, when a lattice-like spacer is interposed between the upper panel and the lower panel, the following problem occurs. In other words, in order to sufficiently prevent the electrophoretic particles from moving from each cell partitioned by the spacer to other cells, it is necessary to increase the airtightness of each cell partitioned by the spacer. Sufficient mechanical strength is required. When a spacer having a sufficient mechanical strength is interposed between the upper panel and the lower panel, a problem arises that the flexibility of the electrophoretic display panel is lost. In addition, since a spacer having sufficient mechanical strength is relatively heavy, there is a problem that the weight of the electrophoretic display panel is increased when such a spacer is interposed. Further, when a lattice-like spacer is interposed between the upper panel and the lower panel, the manufacturing process of the electrophoretic display panel becomes complicated, and there is a problem that the manufacturing cost increases.
[0007]
On the other hand, when microcapsules are used, there is no problem that the flexibility of the electrophoretic display panel is lost or the weight of the electrophoretic display panel is increased, but it is difficult to manufacture the microcapsules themselves. This raises the problem of increasing the manufacturing cost. Also, since the shape of the microcapsule is substantially spherical, the contact area between the display surface of the electrophoretic display panel and the microcapsule is very small. As a result, the electrophoretic particles enclosed in the microcapsule move. There is also a problem that there is little change in brightness due to, and the contrast is low.
[0008]
Therefore, a flexible and lightweight electrophoretic display panel and a method capable of easily manufacturing such an electrophoretic display panel have been desired.
[0009]
Accordingly, an object of the present invention is to provide an electrophoretic display device that is flexible and lightweight.
[0010]
Another object of the present invention is to provide a method capable of easily manufacturing a flexible and lightweight electrophoretic display device.
[0011]
[Means for Solving the Problems]
An object of the present invention includes an upper panel, a lower panel, and an electrophoretic layer sandwiched between the upper panel and the lower panel, the electrophoretic layer including a first flexible film, and the first A second flexible film having a plurality of bag-like portions closed by one flexible film, and at least electrophoretic particles are enclosed in the internal space of the closed bag-like portion. This is achieved by an electrophoretic display device.
[0012]
According to the present invention, the electrophoretic layer includes a first flexible film and a second flexible film having a plurality of bag-like portions closed by the first flexible film, Since the electrophoretic particles are sealed in the inner space of the bag-shaped portion, the cell structure can be realized without using a spacer. Thereby, aggregation of the electrophoretic particles is prevented and display unevenness is prevented. In addition, according to the present invention, since the bag-like portion that separates the cells is made of a flexible film, the flexibility of the electrophoretic display device itself is not impaired, and the weight of the electrophoretic display device is reduced. The increase can be minimized.
[0013]
In a preferred embodiment of the present invention, an electrode layer is formed on at least one of the upper panel and the lower panel.
[0014]
In a further preferred embodiment of the present invention, the second flexible film is made of at least one material selected from the group consisting of polyethylene, polypropylene, urethane, acrylic, polyester, fluororesin, nylon, and polyvinyl chloride. Composed.
[0015]
The object of the present invention is also to provide a first step of forming a plurality of bag-like portions on a flexible film, a second step of introducing at least electrophoretic particles into the formed bag-like portion, and the bag. A third step of forming an electrophoretic layer by closing the shaped part and sealing the introduced electrophoretic particles, and a fourth step of sandwiching the electrophoretic layer between the upper panel and the lower panel. This is achieved by a method for manufacturing an electrophoretic display device.
[0016]
According to the present invention, since the electrophoretic particles are introduced into a plurality of bag-like portions formed on the flexible film and closed, the cells for sealing the electrophoretic particles are formed. An electrophoretic display device having a cell structure can be manufactured by a simple method. Therefore, the manufacturing cost of the electrophoretic display device can be kept low.
[0017]
In a preferred embodiment of the present invention, the first step is performed by pressing the flexible film.
[0018]
In a further preferred embodiment of the present invention, the third step is performed by adhering another flexible film to the flexible film in which the electrophoretic particles are introduced into the bag-like portion.
[0019]
In a further preferred embodiment of the present invention, the fourth step is performed under reduced pressure.
[0020]
According to a further preferred embodiment of the present invention, since the fourth step of sandwiching the electrophoretic layer between the upper panel and the lower panel is performed under reduced pressure, each cell defined by the bag-like portion is crushed and deformed. In addition, the space between the lower surface panel and the upper surface panel can be filled with cells substantially without a gap. This makes it possible to manufacture an electrophoretic display device with no gap between cells.
[0021]
In a further preferred embodiment of the present invention, the method further comprises a step of applying a binder to the outside of the plurality of bag-like portions of the flexible film.
[0022]
According to a further preferred embodiment of the present invention, since the binder is applied to the outside of the plurality of bag-like portions of the flexible film, the bag-like portions are bonded to each other, thereby increasing the strength of each cell. Therefore, after the electrophoretic display device is completed, even when the electrophoretic display device is greatly bent or strongly pressed in an actual use state and a strong external force is applied to the cell, the bag-like portion is damaged. The risk of the electrophoretic particles enclosed in the cell flowing out of the cell is reduced.
[0023]
Preferred Embodiment of the Invention
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0024]
FIG. 1 is a cross-sectional view showing an electrophoretic display device 1 according to a preferred embodiment of the present invention.
[0025]
As shown in FIG. 1, an electrophoretic display device 1 according to this embodiment includes a substrate 2, a lower layer electrode 3, a first flexible film 4, a second flexible film 5, and an upper layer. An electrode 6 and a protective film 7 are included.
[0026]
The substrate 2 is made of polyester, for example, and the thickness is preferably about 100 μm. The lower layer electrode 3 is a transparent electrode made of, for example, ITO or SnO ₂ formed on the substrate 2, and the thickness is preferably about 1 to 10 μm. The first flexible film 4 is a transparent resin film having flexibility such as polyethylene, polypropylene, urethane, acrylic, polyester, fluororesin, nylon, polyvinyl chloride, and the surface thereof is substantially flat. is there. The thickness is preferably about 5 to 50 μm. The 2nd flexible film 5 consists of the same material as the 1st flexible film 4, and has the many bag-shaped parts 8 which protruded on the one surface of the film on the surface. A large number of bag-like portions 8 of the second flexible film 5 are closed by the first flexible film 4 to form cells 9, and each cell 9 includes titanium oxide, carbon black, bitumen, An electrophoretic particle 10 made of phthalocyanine green or the like and a liquid dispersion medium 11 made of alcohol solvent, ester, aliphatic hydrocarbon, alicyclic hydrocarbon, aromatic hydrocarbon, halogenated hydrocarbon or the like are enclosed. Yes. The types of the electrophoretic particles 10 and the liquid dispersion medium 11 are not particularly limited, but need to have different brightness, color, and the like. For example, the electrophoretic particles 10 are white and the liquid dispersion medium 11 is black. As for the thickness of the 2nd flexible film 5 whole containing the bag-shaped part 8, about 100-1500 micrometers is preferable. The upper layer electrode 6 is a transparent electrode made of, for example, ITO or SnO ₂ , and the thickness is preferably about 1 to 10 μm. The protective film 7 is a transparent film made of a PET film, a polycarbonate film, an acrylic resin film, a fluororesin or the like, and the thickness is preferably about 20 to 100 μm.
[0027]
In the electrophoretic display device 1 having such a configuration, for example, when the electrophoretic particles 10 are negatively charged, a positive voltage is applied to the lower electrode 3 and a negative voltage is applied to the upper electrode 6. As a result, the electrophoretic particles 10 move to the lower electrode 3 side due to the Coulomb force, and conversely, when the negative voltage is applied to the lower electrode 3 and the positive voltage is applied to the upper electrode 6, the electrophoretic particles 10 are moved to the Coulomb. It moves to the upper layer electrode 6 side by force. For this reason, for example, when the electrophoretic particles 10 are white and the liquid dispersion medium 11 is black, the electrophoretic particles 10 move to the lower electrode 3 side, so that the portion becomes black, and conversely, the electrophoretic particles By moving 10 to the upper electrode 6 side, the portion becomes white. Therefore, by forming at least one of the lower layer electrode 3 and the upper layer electrode 6 in a matrix and driving each unit electrode independently, it is possible to display a desired figure / character on the electrophoretic display device 1. Become.
[0028]
As described above, the electrophoretic display device 1 according to the present embodiment includes a large number of cells 9 defined by the large number of bag-shaped portions 8 included in the second flexible film 5, and each of the cells 9 is electrophoresed. Since the particles 10 and the liquid dispersion medium 11 are enclosed, the electrophoretic particles 10 are prevented from aggregating, thereby preventing display unevenness. Further, the bag-like portion 8 that defines each cell 9 is a part of the second flexible film 5 having flexibility, and similarly has flexibility, so the electrophoretic display device 1. It is possible to ensure the flexibility of the device itself, and it is possible to minimize an increase in the weight of the electrophoretic display device 1.
[0029]
Next, a method for manufacturing the electrophoretic display device 1 will be described.
[0030]
FIG. 2 is a diagram illustrating a method for manufacturing the second flexible film 5.
[0031]
As shown in FIG. 2, first, a resin film such as polyethylene, polypropylene, urethane, acrylic, polyester, fluororesin, nylon, and polyvinyl chloride, which is a material of the second flexible film 5, is prepared, and a mold is prepared. This is pressed using 12 and 13. The molds 12 and 13 are respectively provided with a convex part and a concave part. When pressed, the convex part of the mold 12 coincides with the concave part of the mold 13, and the concave part of the mold 12 is the same as that of the mold 13. Matches the convex part. For this reason, many bag-like parts 8 are formed in the resin film pressed by the molds 12 and 13, thereby completing the second flexible film 5.
[0032]
3 and 4 are a cross-sectional view and a plan view showing the second flexible film 5 in which the bag-like portion 8 is formed by pressing, respectively.
[0033]
Next, the electrophoretic particles 10 and the liquid dispersion medium 11 are injected into the cell 9 defined by the bag-like portion 8 of the second flexible film 5. The method of injection is not particularly limited, but the electrophoretic particles are formed on the second flexible film 5 while supporting the second flexible film 5 substantially horizontally with the bag-like portion 8 facing downward. The liquid dispersion medium 11 mixed with 10 may be dropped, or the second flexible film 5 may be immersed in the electrophoretic particles 10 and the liquid dispersion medium 11 filled in the container.
[0034]
In this way, after each cell 9 of the second flexible film 5 is filled with the electrophoretic particles 10 and the liquid dispersion medium 11, the second flexible film 5 is formed (the bag-like portion 8 is formed). The first flexible film 4 is covered from the side opposite to the formed side. Next, the contact part of the 1st flexible film 4 and the 2nd flexible film 5 is heated in this state, and these contact parts are thermocompression-bonded. Thereby, each cell 9 of the 2nd flexible film 5 is obstruct | occluded by the 1st flexible film 4, and the electrophoretic particle 10 and the liquid dispersion medium 11 in each cell 9 are sealed. Thus, an electrophoretic layer composed of the first flexible film 4 and the second flexible film 5 is completed.
[0035]
Next, the substrate 2 is prepared, the lower layer electrode 3 is formed on the substrate 2 to manufacture the lower surface panel, the protective film 7 is prepared, and the upper layer electrode 6 is formed on the protective film 7 to manufacture the upper surface panel. To do.
[0036]
Next, the electrophoretic layer composed of the first flexible film 4 and the second flexible film 5 is formed by the lower panel composed of the substrate 2 and the lower layer electrode 3 and the upper panel composed of the upper layer electrode 6 and the protective film 7. Hold it. At this time, a predetermined pressure, for example, 10 ⁵ to 10 ⁶ Pa is applied to the electrophoretic layer composed of the first flexible film 4 and the second flexible film 5, and the pressure is reduced. Thereby, each cell 9 is crushed and deformed, and the adjacent bag-like portions 8 are substantially in close contact with each other. That is, the space between the lower panel composed of the substrate 2 and the lower layer electrode 3 and the upper panel composed of the upper layer electrode 6 and the protective film 7 is substantially filled with the cells 9.
[0037]
Next, while maintaining the reduced pressure state of the electrophoretic layer comprising the first flexible film 4 and the second flexible film 5, the lower panel comprising the substrate 2 and the lower electrode 3, the upper electrode 6 and the protective film. 7 is sealed with a sealing material (not shown), whereby the electrophoretic display device 1 shown in FIG. 1 is completed.
[0038]
When the electrophoretic layer composed of the first flexible film 4 and the second flexible film 5 is sandwiched between the upper panel and the lower panel, the bag-shaped portion 8 of the second flexible film 5 It is preferable to apply a binder to the outside. As described above, when the binder is applied to the outside of the bag-like portion 8 of the second flexible film 5, pressure is applied to the electrophoretic layer composed of the first flexible film 4 and the second flexible film 5. The bag-like portions 8 that are in contact with each other when the adjacent bag-like portions 8 are brought into close contact with each other by being applied with a reduced pressure are bonded to each other, thereby increasing the strength of each cell 9. Become. Therefore, even after the electrophoretic display device 1 is completed, even when the electrophoretic display device 1 is greatly bent or strongly pressed in an actual use state and a strong external force is applied to the cell 9, the bag-shaped portion 8 is damaged, and the risk that the electrophoretic particles 10 and the liquid dispersion medium 11 enclosed in the cell 9 will flow out of the cell 9 is reduced.
[0039]
Thus, according to the manufacturing method of the electrophoretic display device 1 according to the present embodiment, the second flexible film 5 having the bag-like portion 8 by pressing the resin film having flexibility. The cell 9 defined by the bag-like portion 8 is filled with the electrophoretic particles 10 and the liquid dispersion medium 11, and then the cell 9 is closed by thermocompression bonding the first flexible film 4. Therefore, the electrophoretic display device 1 having a cell structure can be manufactured by a very simple method.
[0040]
Further, when an electrophoretic layer composed of the first flexible film 4 and the second flexible film 5 is sandwiched between the upper panel and the lower panel, a predetermined pressure is applied to the electrophoretic layer. Since the pressure is reduced, each cell 9 is crushed and deformed, and the space between the lower panel and the upper panel is substantially filled with the cell 9 without any gap. As a result, the electrophoretic display device 1 with no gap between the cells 9 can be manufactured.
[0041]
The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the invention described in the claims, and these are also included in the scope of the present invention. Needless to say.
[0042]
For example, in the electrophoretic display device 1 according to the above embodiment, the second flexible film 5 having the bag-like portion 8 is arranged on the display surface side, and the first flexible film 4 is opposite to the display surface. However, the arrangement order of the first flexible film 4 and the second flexible film 5 is not limited to this, and the first flexible film 4 is arranged on the display surface side. And you may arrange | position the 2nd flexible film 5 which has the bag-shaped part 8 on the opposite side to a display surface.
[0043]
Moreover, in the electrophoretic display device 1 according to the above embodiment, the same material is used for the first flexible film 4 and the second flexible film 5, but it is not necessary to use the same material. Different materials may be used.
[0044]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a flexible and lightweight electrophoretic display device and a method capable of easily manufacturing such an electrophoretic display device.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an electrophoretic display device 1 according to a preferred embodiment of the present invention.
FIG. 2 is a diagram showing a method for manufacturing the second flexible film 5;
FIG. 3 is a cross-sectional view showing a second flexible film 5 in which a bag-like portion 8 is formed by press working.
FIG. 4 is a plan view showing a second flexible film 5 in which a bag-like portion 8 is formed by press working.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Electrophoretic display apparatus 2 Board | substrate 3 Lower layer electrode 4 1st flexible film 5 2nd flexible film 6 Upper layer electrode 7 Protective film 8 Bag-shaped part 9 Cell 10 Electrophoretic particle 11 Liquid dispersion medium 12, 13 Gold Type

Claims (8)

A top panel; a bottom panel; and an electrophoretic layer sandwiched between the top panel and the bottom panel, wherein the electrophoretic layer is formed by a first flexible film and the first flexible film. And a second flexible film having a plurality of closed bag-like portions, wherein at least electrophoretic particles are enclosed in the internal space of the closed bag-like portion. Display device. The electrophoretic display device according to claim 1, wherein an electrode layer is formed on at least one of the upper panel and the lower panel. The second flexible film is made of at least one material selected from the group consisting of polyethylene, polypropylene, urethane, acrylic, polyester, fluororesin, nylon, and polyvinyl chloride. 3. The electrophoretic display device according to 1 or 2. A first step of forming a plurality of bag-like portions on a flexible film; a second step of introducing at least electrophoretic particles into the formed bag-like portion; and the introduction by closing the bag-like portion. A method of manufacturing an electrophoretic display device, comprising: a third step of forming an electrophoretic layer by sealing the electrophoretic particles formed; and a fourth step of sandwiching the electrophoretic layer between an upper panel and a lower panel. The method of manufacturing an electrophoretic display device according to claim 4, wherein the first step is performed by pressing the flexible film. 6. The third step is performed by adhering another flexible film to a flexible film in which the electrophoretic particles are introduced into the bag-like portion. A method for producing the electrophoretic display device according to claim. The method for manufacturing an electrophoretic display device according to claim 4, wherein the fourth step is performed under reduced pressure. The method for manufacturing an electrophoretic display device according to claim 4, further comprising a step of applying a binder to the outside of the plurality of bag-like portions of the flexible film.

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