JP5751352B2 - Electrophoretic display device and electronic apparatus - Google Patents

Description

  The present invention relates to an electrophoretic display device and an electronic apparatus.

  2. Description of the Related Art As an electrophoretic display device, one having a configuration in which an electrophoretic element having a liquid phase dispersion medium and electrophoretic particles is sandwiched between a pair of substrates is known. In this type of electrophoretic display device, an electrode is provided on each of a pair of substrates, and a desired image is controlled by controlling the polarity, waveform, amplitude, application time, frequency, etc. of the voltage applied between the electrodes. Is displayed. As a so-called matrix-type electrophoretic display device in which a plurality of pixels constituting an image are arranged in a matrix, a plurality of pixel electrodes are arranged in a matrix on one substrate as described in Patent Document 1 below. An electrode configuration is generally formed in which a counter electrode is formed on the entire surface of the other substrate. Japanese Patent Application Laid-Open No. 2004-228620 describes that gradation display by area gradation is made possible by configuring one pixel with n (n is an integer of 2 or more) subpixels.

JP 2006-309131 A

  However, in the electrophoretic display device disclosed in Patent Document 1, blurring occurs around an image when a specific image is displayed. In particular, in the case of color display, color blurring occurs, resulting in a deterioration in display quality. There was a problem of doing. Further, when performing gradation display, it is necessary to individually drive an extremely large number of sub-pixels, which causes problems such as a complicated apparatus configuration and a heavy load on a driving circuit. For example, it may be possible to display a different color for each sub-pixel by providing a color filter to perform color display, but in this case, the same problem exists.

  The present invention has been made to solve the above problems, and provides an electrophoretic display device capable of improving display quality by suppressing the occurrence of bleeding (color bleeding in the case of color display). The purpose is to do. Another object of the present invention is to provide an electrophoretic display device capable of gradation display and color display with a simple configuration. It is another object of the present invention to provide an electronic device including an electrophoretic display unit with excellent display quality.

In order to achieve the above object, an electrophoretic display device according to the present invention includes a first substrate, a second substrate, and an electrophoretic element sandwiched between the first substrate and the second substrate. An electrophoretic display device comprising: a plurality of pixel electrodes provided on the first substrate and arranged in a row direction and a column direction; provided on the second substrate; An opening extending in at least one of the row direction and the column direction at a location facing the region between the adjacent pixel electrodes. It is characterized by having.
In this specification, “row direction” means “horizontal direction” on the display screen of the electrophoretic display device, and “column direction” means “vertical direction” orthogonal to the horizontal direction.

  For example, the first voltage is applied to one pixel electrode, and the second voltage (the second voltage is different from the first voltage) is applied to the counter electrode and the adjacent pixel electrodes. Assume a case. At this time, the pixel including the pixel electrode to which the first voltage is applied is in the first display state (for example, black display), and the adjacent pixel including the pixel electrode to which the second voltage is applied is in the second display state ( For example, white display).

  Here, in the case of the conventional electrophoretic display device, since the counter electrode is formed on the entire surface of the substrate, when the voltage application state described above, the voltage between one pixel electrode and the adjacent pixel electrodes is different. A horizontal electric field (electric field in a direction parallel to the substrate surface) is generated between both electrodes, and a vertical electric field (electric field in a direction perpendicular to the substrate surface) generated between one pixel electrode and the counter electrode is confronted accordingly. It is in a state of spreading to both adjacent pixels at a position near the electrodes. Therefore, the distribution of electrophoretic particles moving along the electric field spreading on the counter electrode side also spreads to the adjacent pixel side. As a result, the pixels in the first display state (for example, black display) appear to be blurred and the outline is blurred. The image is visible.

  On the other hand, in the case of the electrophoretic display device of the present invention, the counter electrode is not formed on the entire surface of the substrate, but the counter electrode is located in a row direction and a column direction at a position facing the region between adjacent pixel electrodes. Having an opening extending in at least one direction. In other words, a region where no counter electrode exists in at least one of the row direction and the column direction is provided at a position facing a region between adjacent pixel electrodes. By adopting such an electrode configuration, even when the above-described voltage application state occurs, the counter electrode side of the vertical electric field (electric field in the direction perpendicular to the substrate surface) generated between one pixel electrode and the counter electrode The spread at is suppressed. As a result, display blur can be reduced, and a sharp image with a sharp outline can be displayed.

In the electrophoretic display device according to the aspect of the invention, the counter electrode is provided so as to surround a plurality of island-shaped portions provided at locations facing each of the plurality of pixel electrodes and the periphery of the plurality of island-shaped portions. The structure which has a frame part and the connection part which connects between the said several island-like parts and between the said predetermined island-like part and the said frame part is employable.
According to this configuration, since each island-like portion is provided at a position facing each pixel electrode, the spread of the vertical electric field can be suppressed in both the row direction and the column direction around the pixel electrode. Accordingly, display blur can be reduced in both the horizontal and vertical directions of the screen. In addition, since a plurality of island-shaped portions and between the island-shaped portion and the frame portion are connected by a connecting portion, for example, by supplying a voltage to the frame portion, a common voltage is collectively applied to the entire counter electrode. Can be applied.

In the electrophoretic display device according to the aspect of the invention, the counter electrode is provided in a region corresponding to the first counter electrode having the opening and at least the opening, and a voltage is applied independently of the first counter electrode. A configuration including a possible second counter electrode can be employed.
According to this configuration, a sharp image is displayed by the action of the first counter electrode having the opening by appropriately selecting the combination of the voltage applied to the first counter electrode and the voltage applied to the second counter electrode. An electrophoretic display device capable of switching between a mode and a mode for displaying a soft focus image in which blur is intentionally generated by the action of the first counter electrode and the second counter electrode can be realized.

In the electrophoretic display device of the present invention, the second counter electrode may be provided on the second substrate, and the first counter electrode may be provided on the second counter electrode via an insulating layer.
According to this configuration, the first counter electrode and the second counter electrode are opposed to each other via the insulating layer, and even if they are arranged in a plane, there is no short circuit. It can be formed on the entire surface of the second substrate. In this case, an electrophoretic display device that can switch between the two display modes described above can be manufactured without patterning the second counter electrode in the manufacturing process.

Alternatively, in the electrophoretic display device of the present invention, the first counter electrode and the second counter electrode may be formed in the same layer.
According to this configuration, since the first counter electrode and the second counter electrode can be formed only by patterning one layer, the insulating layer that insulates between the first counter electrode and the second counter electrode in the manufacturing process. Without being formed, an electrophoretic display device capable of switching between the two display modes described above can be manufactured.

In the electrophoretic display device of the present invention, a configuration including a color filter provided with a color material layer of a different color corresponding to each of the plurality of pixel electrodes can be employed.
According to this configuration, color display is possible, and an electrophoretic display device with less color blur can be realized.

  The electrophoretic display device of the present invention is an electrophoretic display device comprising a first substrate, a second substrate, and an electrophoretic element sandwiched between the first substrate and the second substrate. A plurality of pixel electrodes provided on the first substrate and arranged in a row direction and a column direction, and a counter electrode provided on the second substrate and applying a voltage to the electrophoretic element between the pixel electrodes. And the counter electrode has a plurality of electrodes to which a voltage can be individually applied at a position facing one pixel electrode.

  According to the electrophoretic display device of the present invention, a region (pixel) corresponding to one pixel electrode is selected by appropriately selecting a combination of a voltage applied to the pixel electrode and a voltage applied to each electrode constituting the counter electrode. The movement of the electrophoretic particles can be controlled for each electrode forming region of the counter electrode. Therefore, it is possible to realize an electrophoretic display device capable of gradation display with a simple configuration without forming a pixel with a plurality of subpixels.

In the electrophoretic display device of the present invention, a configuration including a color filter provided with a color material layer of a different color corresponding to each of the plurality of electrodes can be employed.
According to this configuration, an electrophoretic display device capable of color display with a simple configuration can be realized by appropriately selecting a combination of a voltage applied to the pixel electrode and a voltage applied to each electrode constituting the counter electrode. .

An electronic apparatus of the present invention includes the electrophoretic display device of the present invention.
According to the present invention, since the electrophoretic display device of the present invention is provided, it is possible to provide an electronic apparatus including an electrophoretic display unit that is capable of sharp display and excellent in display quality.

1 is an equivalent circuit diagram illustrating an electrophoretic display device according to a first embodiment of the present invention. It is sectional drawing which shows the electrophoretic display device of this embodiment. It is sectional drawing which shows the microcapsule which comprises an electrophoretic element. It is a figure for demonstrating operation | movement of an electrophoretic element. It is a top view which shows the counter electrode of the electrophoretic display device of this embodiment. It is a figure for demonstrating the effect | action of the electrophoretic display device of this embodiment. It is a figure for demonstrating the problem of the conventional electrophoretic display device. It is a top view which shows the other example of a counter electrode. It is a top view which shows the counter electrode in the electrophoretic display device of 2nd Embodiment of this invention. It is a figure for demonstrating the effect | action of the electrophoretic display device of this embodiment. It is a top view which shows the counter electrode in the electrophoretic display device of 3rd Embodiment of this invention. It is a figure for demonstrating the effect | action of the electrophoretic display device of this embodiment. It is a top view which shows the counter electrode in the electrophoretic display device of 4th Embodiment of this invention. It is sectional drawing which shows the electrophoretic display device of this embodiment. It is a figure for demonstrating the effect | action of the electrophoretic display device of this embodiment. It is sectional drawing which shows the electrophoretic display device of 5th Embodiment of this invention. It is a figure which shows embodiment of the electronic device of this invention.

[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
The present embodiment is an example of an active matrix type electrophoretic display device.
FIG. 1 is an equivalent circuit diagram showing an electrophoretic display device of this embodiment. FIG. 2 is a sectional view of the electrophoretic display device. FIG. 3 is a cross-sectional view of a microcapsule constituting an electrophoretic element. 4A and 4B are diagrams for explaining the operation of the electrophoretic element. FIG. 5 is a plan view showing the counter electrode of the electrophoretic display device of this embodiment. 6A and 6B are diagrams for explaining the operation of the electrophoretic display device of this embodiment. 7A and 7B are diagrams for explaining the problems of the conventional electrophoretic display device. FIG. 8 is a plan view showing another example of the counter electrode.
In the following drawings, in order to make each component easy to see, the scale of the size may be varied depending on the component.

As shown in FIG. 1, the electrophoretic display device 100 according to the present embodiment includes a display unit 5 in which a plurality of pixels 40 are arranged in a matrix in the row direction and the column direction. Around the display unit 5, a scanning line driving circuit 61 and a data line driving circuit 62 are arranged. The display unit 5 is provided with a plurality of scanning lines 36 extending from the scanning line driving circuit 61 and a plurality of data lines 38 extending from the data line driving circuit 62, and the pixels 40 correspond to these intersecting positions. Is provided. Each pixel 40 is provided with a selection transistor 41 and a pixel electrode 35.
Note that the “row direction” is the “horizontal direction” in the display unit, and corresponds to the horizontal direction in FIG. The “column direction” is a “vertical direction” orthogonal to the horizontal direction and corresponds to the vertical direction in FIG.

  The scanning line driving circuit 61 is connected to each pixel 40 via m scanning lines 36 (G1, G2,..., Gm), and sequentially selects the scanning lines 36 from the first row to the m-th row. A selection signal defining the timing for turning on the selection transistor 41 provided in the pixel 40 is supplied via the selected scanning line 36. The data line driving circuit 62 is connected to each pixel 40 via n data lines 38 (S1, S2,..., Sn), and receives an image signal that defines pixel data corresponding to each pixel 40. The pixel 40 is supplied.

  As shown in FIG. 2, the electrophoretic display device 100 includes an element substrate 30 (first substrate), a counter substrate 31 (second substrate), and a plurality of sandwiched between the element substrate 30 and the counter substrate 31. An electrophoretic element 32 in which microcapsules 20 are arranged. A scanning line 36, a data line 38, a selection transistor 41, and the like shown in FIG. 1 are formed on the surface of the element substrate 30 on which the electrophoretic element 32 is disposed. FIG. 2 shows a cross-sectional structure of two adjacent pixels.

  The substrate body 71 constituting the element substrate 30 is made of glass, plastic, or the like. Since the substrate body 71 is disposed on the side opposite to the viewing side, it does not have to be transparent. A semiconductor layer 72 is formed on one surface of the substrate body 71 on the electrophoretic element 32 side, and a gate insulating film 73 is formed so as to cover the semiconductor layer 72. The semiconductor layer 72 includes, for example, non-single-crystal silicon materials such as amorphous silicon and polycrystalline silicon, oxide semiconductor materials, transparent oxide semiconductor materials such as In—Ga—Zn—O, and organic substances such as fluorene-bithiophene copolymers. A semiconductor material or the like can be used. When an oxide semiconductor material is used for the semiconductor layer 72, an oxide insulating material is preferably used for the gate insulating film 73. When an organic semiconductor material is used for the semiconductor layer 72, the gate insulating film 73 is used. It is also desirable to use an organic insulating material.

  On the gate insulating film 73, the scanning line 36 that functions as the gate electrode of the selection transistor 41 is formed. For the scanning line 36, for example, a metal laminated film of an Al—Nd alloy and Mo can be used. In addition, Al alone, ITO, Cu, Cr, Ta, Mo, Nb, Ag, Pt, Pd, In, Nd, and alloys thereof can be used. A first interlayer insulating film 74 is formed on the entire surface of the substrate body 71 so as to cover the scanning lines 36. For the first interlayer insulating film 74, for example, an inorganic insulating material such as a silicon nitride film, a silicon oxide film, or a silicon nitride oxide film, or an organic insulating material can be used. A data line 38 electrically connected to the source region of the semiconductor layer 72 through the contact hole 75 is formed on the first interlayer insulating film 74. The same material as that of the scanning line 36 can be used for the data line 38. 2 has a top gate structure in which the gate electrode is formed above the semiconductor layer 72 in FIG. 2, it has a bottom gate structure in which the gate electrode is formed below the semiconductor layer 72. Also good.

  A second interlayer insulating film 76 is formed on the entire surface of the first interlayer insulating film 74 so as to cover the data line 38. As the first interlayer insulating film 74, for example, an inorganic insulating material such as a silicon nitride film, a silicon oxide film, or a silicon nitride oxide film, or an organic insulating material can be used for the second interlayer insulating film 76. A pixel electrode 35 electrically connected to the drain region of the semiconductor layer 72 through the contact hole 77 is formed on the second interlayer insulating film 76. The pixel electrode 35 is made of, for example, a transparent conductive material such as ITO (indium tin oxide) or a metal material such as Al, and applies a voltage to the electrophoretic element 32 with the counter electrode 37 described later. Electrode. Here, although the planar shape of the pixel electrode 35 is not illustrated, the data line 38 and the scanning line 36 are formed in a substantially rectangular shape in accordance with the substantially orthogonal arrangement.

  On the other hand, the substrate body 79 constituting the counter substrate 31 is a substrate made of glass, plastic, or the like, and is disposed on the viewing side, so that a transparent substrate is used. A counter electrode 37 is formed on one surface of the substrate body 79 on the side of the electrophoretic element 32 so as to face each pixel electrode 35. That is, the counter electrode 37 is formed by being divided for each pixel 40. The counter electrode 37 is an electrode that applies a voltage to the electrophoretic element 32 together with the pixel electrode 35, and is made of a transparent conductive material such as MgAg (magnesium silver), ITO, or IZO (indium / zinc oxide). The planar shape of the counter electrode 37 will be described later.

  The electrophoretic element 32 and the pixel electrode 35 are bonded via an adhesive layer (not shown), whereby the element substrate 30 and the counter substrate 31 are bonded. The electrophoretic element 32 is generally formed in advance on the counter substrate 31 side and is handled as an electrophoretic sheet including the adhesive layer. In the manufacturing process, the electrophoretic sheet is handled in a state where a protective release sheet is attached to the surface of the adhesive layer. Then, the display unit 5 is formed by attaching the electrophoretic sheet from which the release sheet is peeled off to the element substrate 30 on which the pixel electrode 35, the selection transistor 41, various circuits, and the like are separately formed. For this reason, the adhesive layer exists only on the pixel electrode 35 side.

  As shown in FIG. 3, the microcapsule 20 has a particle size of, for example, about 50 μm, and has a dispersion medium 21, a large number of white particles (electrophoretic particles) 27, and a large number of black particles (electrophoresis). Particles) 26 are encapsulated spherical bodies. As shown in FIG. 2, the microcapsule 20 is sandwiched between the counter electrode 37 and the pixel electrode 35, and a plurality of microcapsules 20 are arranged in one pixel 40. 2 shows a configuration in which a plurality of microcapsules 20 are arranged in one pixel 40, a configuration in which one microcapsule 20 is arranged in one pixel 40 may be used. .

  The outer shell portion 20a (wall film) of the microcapsule 20 is formed using an acrylic resin such as polymethyl methacrylate or polyethyl methacrylate, a translucent polymer resin such as a urea resin, or gum arabic. Yes. The dispersion medium 21 is a liquid that disperses the white particles 27 and the black particles 26 in the microcapsules 20.

  Examples of the dispersion medium 21 include water, alcohol solvents (methanol, ethanol, isopropanol, butanol, octanol, methyl cellosolve, etc.), esters (ethyl acetate, butyl acetate, etc.), ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.). ), Aliphatic hydrocarbons (pentane, hexane, octane, etc.), alicyclic hydrocarbons (cyclohexane, methylcyclohexane, etc.), aromatic hydrocarbons (benzene, toluene, benzenes having a long-chain alkyl group ( Xylene, hexylbenzene, hebutylbenzene, octylbenzene, nonylbenzene, decylbenzene, undecylbenzene, dodecylbenzene, tridecylbenzene, tetradecylbenzene)), halogenated hydrocarbons (methylene chloride, chloroform, tetrachloride) Element, and 1,2-dichloroethane), can be exemplified a carboxylate, it may be other oils. These substances can be used alone or as a mixture, and a surfactant or the like may be further blended.

  The white particles 27 are particles (polymer or colloid) made of a white pigment such as titanium dioxide, zinc white, and antimony trioxide, and are used, for example, by being negatively charged. The black particles 26 are particles (polymer or colloid) made of a black pigment such as aniline black or carbon black, and are used by being charged positively, for example.

If necessary, these white pigments and black pigments may include electrolytes, surfactants, metal soaps, resins, rubbers, oils, varnishes, compound charge control agents, titanium-based coupling agents, aluminum-based cups. A dispersing agent such as a ring agent and a silane coupling agent, a lubricant, a stabilizer, and the like can be added.
Further, instead of the black particles 26 and the white particles 27, for example, pigments such as red, green, blue, yellow, cyan, magenta and the like may be used. According to such a configuration, red, green, blue, yellow, cyan, magenta, and the like can be displayed on the display unit 5 without using a color filter.
Instead of the above configuration, a one-particle system in which one type of charged particle is dispersed in the colored dispersion medium 21 may be used. Alternatively, a configuration in which two or more kinds of charged particles are dispersed in the colored dispersion medium 21 may be used.
Further, instead of the configuration in which the dispersion medium and particles are enclosed in the microcapsule, a configuration in which the dispersion medium and particles are filled between a pair of substrates may be used. In this case, a partition wall is provided between the pair of substrates. The dispersion medium and the particles may be filled in the cells partitioned by the partition walls.

  In the electrophoretic element 32 configured as described above, when the pixel 40 is displayed in white, as shown in FIG. 4A, the counter electrode 37 is held at a relatively high potential, and the pixel electrode 35 is relatively lowered. Hold at potential. That is, when the potential of the counter electrode 37 is set as a reference potential, the pixel electrode 35 is held negative. As a result, the negatively charged white particles 26 are attracted to the counter electrode 37, while the positively charged black particles 27 are attracted to the pixel electrode 35. As a result, when this pixel is viewed from the counter electrode 37 side, white is visually recognized.

  On the other hand, when the pixel 40 is displayed in black, as shown in FIG. 4B, the counter electrode 37 is held at a relatively low potential, and the pixel electrode 35 is held at a relatively high potential. That is, when the potential of the counter electrode 37 is set as a reference potential, the pixel electrode 35 is kept positive. Thereby, the positively charged black particles 27 are attracted toward the counter electrode 37, while the negatively charged white particles 27 are attracted to the pixel electrode 35. As a result, when this pixel is viewed from the counter electrode 37 side, black is visually recognized.

Next, the configuration of the counter electrode 37 which is a characteristic part of the present invention will be described.
As shown in FIG. 5, the counter electrode 37 includes a plurality of island-shaped portions 80, a frame portion 81, and a plurality of connecting portions 82, which are formed of an integral transparent conductive film. The island-shaped portion 80 is provided at a location facing each pixel electrode 35 on the element substrate 30. Here, although it is formed in a rectangular shape in accordance with the shape of the pixel electrode 35, it is not necessarily a rectangular shape, and may be an arbitrary shape such as a circle or a polygon. Further, the dimension of one side of the island-shaped portion 80 is set substantially equal to that of the pixel electrode 35. That is, in the present embodiment, the island-shaped portion 80 is formed to have substantially the same shape and the same dimensions as the pixel electrode 35.

  The frame portion 81 is provided so as to surround the periphery of the plurality of island-shaped portions 80. That is, the frame part 81 is provided corresponding to the area outside the display part 5. In addition, between the adjacent island-shaped portion 80 and the island-shaped portion 80 and between the outermost island-shaped portion 80 and the frame portion 81 are integrally connected by a connecting portion 82, and the frame portion 81 and the island-shaped portion are 80 is electrically connected. Therefore, the same common potential can be applied to all island portions 80 by applying a voltage to the frame portion 81. In this example, the connecting portion 82 connects two directions between the island-shaped portion 80 and the island-shaped portion 80 adjacent in the row direction and between the island-shaped portion 80 and the island-shaped portion 80 adjacent in the column direction. ing. Further, the width (dimension in the short direction) of the connecting portion 82 is set to be sufficiently smaller than the dimension of one side of the island-like portion 80. With the above configuration, the counter electrode 37 has the opening 83 extending in the row direction and the column direction at a position facing the region between the adjacent pixel electrodes 35.

Here, problems of the conventional electrophoretic display device and effects of the present invention will be described with reference to FIGS.
FIGS. 6A and 6B show the electric field state in the electrophoretic display device 100 of the present embodiment, and FIGS. 7A and 7B show the electric field state in the conventional electrophoretic display device 200, respectively. It is shown by. These drawings show three adjacent pixels, and FIGS. 6A and 7A show the case where the potential of all three pixel electrodes is + 15V and the potential of the counter electrode is 0V. . FIGS. 6B and 7B show the case where the potential of the central pixel electrode is + 15V, the potential of the pixel electrode on both sides thereof is 0V, and the potential of the counter electrode is 0V.
At this time, in the voltage application state of FIGS. 6A and 7A, all three pixels are displayed in black, while in the voltage application state of FIGS. 6B and 7B, the central pixel is displayed. Black display is performed, and pixels adjacent to both display white.

  As shown in FIG. 7A, in the case of the conventional electrophoretic display device 200, when all the potentials of the three pixel electrodes 235 are + 15V and the potential of the counter electrode 237 is 0V, An electric field is formed between the counter electrode 237 and electric lines of force extending substantially linearly. On the other hand, as shown in FIG. 7B, when the potential of the central pixel electrode 235 is + 15V, the potential of the pixel electrode 235 on both sides thereof is 0V, and the potential of the counter electrode 237 is 0V, In the electrophoretic display device 235, since the counter electrode 237 is formed on the entire surface of the substrate, a horizontal electric field (electric field in a direction parallel to the substrate surface) is generated between the adjacent pixel electrodes 235, so that the central pixel electrode A vertical electric field (an electric field in a direction perpendicular to the substrate surface) generated between 235 and the counter electrode 237 is greatly spread toward both adjacent pixels at a position near the counter electrode 237. As a result, the distribution of electrophoretic particles that move along the electric field that spreads on the counter electrode 237 side also spreads to the adjacent pixel side. As a result, the central pixel that appears black appears to bleed around and an image with a blurred outline appears. It was visually recognized.

  On the other hand, in the case of the electrophoretic display device 100 of the present embodiment, as shown in FIGS. 6A and 6B, the island-shaped portions 80 of the counter electrode 37 and the pixel electrodes 35 have substantially the same shape. The islands 80 and the pixel electrodes 35 are disposed so as to face each other with substantially the same dimensions. In this case, as shown in FIG. 6A, when all the potentials of the three pixel electrodes 35 are set to +15 V and the potential of the counter electrode 37 is set to 0 V, each pixel electrode 35 is interposed between the counter electrodes 37. The electric field is formed so that the lines of electric force extend substantially linearly. This state is substantially the same as in the conventional case shown in FIG.

  However, as shown in FIG. 6B, when the potential of the central pixel electrode 35 is +15 V, the potential of the adjacent pixel electrode 35 is 0 V, and the potential of the counter electrode 37 is 0 V, the state of the electric field is as follows. Unlike the prior art, even if a horizontal electric field is generated between adjacent pixel electrodes 35, the counter electrode 37 does not exist in the region corresponding to the adjacent pixel electrodes 35. The spread of the vertical electric field (electric field lines) generated between them on the counter electrode 37 side is smaller than in the conventional case, and does not protrude to the adjacent pixel electrode 35 side. As a result, it is possible to suppress blurring of the central pixel that is displayed in black, and it is possible to display a sharp image having a sharp outline.

  FIG. 5 shows an example of the counter electrode 37 in which two directions of the island-shaped portions 80 adjacent in the row direction and the island-shaped portions 80 adjacent in the column direction are connected by the connecting portion 82. Instead of this configuration, for example, as shown in FIG. 8, the island-like portion 80 and the island-like portion 80 adjacent in the column direction are connected by the connecting portion 82A, and the island-like portion 80 and the island adjacent in the row direction are connected. The counter electrode 37 </ b> A that is not connected to the shape part 80 may be used. In this case as well, substantially the same blur suppression effect as that in the case of adopting the configuration of FIG. 5 can be obtained. However, since there is no connection portion for connecting the island-shaped portions 80 adjacent in the row direction, particularly near the center of the pixel. It is possible to further suppress bleeding in the row direction (left-right direction).

  In FIGS. 5 and 8, openings 83 of the counter electrodes 37 and 37A extending in the column direction and the row direction by providing the island-shaped portion 80 and the connecting portions 82 and 82A (portions where no counter electrode exists) are provided. However, instead of this configuration, the counter electrode is formed with an opening (slit) that extends linearly with a certain width, and the portion where the electrode exists is formed in a band with a certain width. It is good also as an electrode. For example, if an opening extending in the column direction is formed, bleeding in the row direction can be suppressed, and if an opening extending in the row direction is formed, bleeding in the column direction can be suppressed. Yes, but you can't suppress bleeding in other directions. However, in the case where bleeding in one direction is allowed depending on the content and use of the image to be displayed, the above electrode configuration may be employed.

[Second Embodiment]
Hereinafter, a second embodiment of the present invention will be described with reference to FIGS.
The basic configuration of the electrophoretic display device of this embodiment is the same as that of the first embodiment, and the configuration of the counter electrode is different from that of the first embodiment.
FIG. 9 is a plan view of the first counter electrode in the electrophoretic display device of the present embodiment. FIG. 10 is a cross-sectional view of the electrophoretic display device of the present embodiment, showing only the electrode configuration.
9 and 10, the same reference numerals are given to the same components as those used in the first embodiment, and detailed description thereof is omitted.

  In the electrophoretic display device 101 of this embodiment, the configuration on the element substrate 30 side is exactly the same as that of the first embodiment. In the configuration on the counter substrate 45 side, as shown in FIGS. 10A and 10B, the counter electrode 46 includes two layers of electrodes, a first counter electrode 47 and a second counter electrode 48. Specifically, a second counter electrode 48 is formed on one surface of the substrate body 79 on the electrophoretic element 32 side, and a first counter electrode 47 is formed on the second counter electrode 48 via an insulating film 49. . The second counter electrode 48 is formed on the entire surface of the substrate body 79, while the first counter electrode 47 is formed to face each pixel electrode 35. That is, the first counter electrode 47 and the second counter electrode 48 are electrically insulated by the insulating film 49, and the first counter electrode 47 and the second counter electrode 48 can be individually applied with a voltage. Yes.

  That is, as shown in FIG. 9, the first counter electrode 47 has a plurality of island-shaped portions 80, a frame portion 81, and a plurality of connecting portions 82, and is the same as the counter electrode 37 of the first embodiment. It has a configuration. The first counter electrode 47 and the second counter electrode 48 are electrodes that apply a voltage to the electrophoretic element 32 together with the pixel electrode 35, and are transparent conductive materials such as MgAg (magnesium silver), ITO, and IZO (indium / zinc oxide). Formed from material. The insulating film 49 can be made of an inorganic insulating material such as a silicon nitride film or an organic insulating material, and the same material as the first and second interlayer insulating films 74 and 76 of the element substrate 30 can be used. 10A and 10B show an example in which the insulating film 49 is formed only directly below the first counter electrode 47, but instead of this configuration, the entire surface of the second counter electrode 48 is formed. An insulating film may be formed.

  Also in the electrophoretic display device 101 of the present embodiment, by providing the first counter electrode 47 having the opening, it is possible to obtain a bleeding suppression effect by the same action as in the first embodiment. Not only suppresses bleeding but also a mode that suppresses bleeding and displays a sharp image by a combination of voltages applied to the first counter electrode 47 and the second counter electrode 48, and intentionally generates bleeding. In addition, an electrophoretic display device capable of switching between a mode for displaying a soft focus image can be realized.

  For example, as shown in FIG. 10A, the potential of the central pixel electrode 35 is +15 V, the potential of the pixel electrode 35 on both sides thereof is 0 V, the potential of the first counter electrode 47 is 0 V, and the potential of the second counter electrode 48. Is set to 15 V, a lateral electric field (an oblique electric field) is generated between the island-shaped portion 80 and the second counter-electrode 48 at the periphery of the island-shaped portion 80 constituting the first counter electrode 47 on the counter electrode side. Therefore, the spread of the vertical electric field generated between the central pixel electrode 35 and the counter electrode 46 is further reduced as compared with the first embodiment. As a result, bleeding can be suppressed and a sharp image with a sharp outline can be displayed.

  On the other hand, as shown in FIG. 10B, the potential of the central pixel electrode 35 is +15 V, the potential of the pixel electrode 35 on both sides thereof is 0 V, the potential of the first counter electrode 47 is 0 V, and the potential of the second counter electrode 48. Is set to 0 V, the first counter electrode 47 and the second counter electrode 48 are at the same potential, so that it is equivalent to the conventional counter electrode formed in a solid shape on the entire surface, and the center pixel electrode 35 and The spread of the vertical electric field generated between the counter electrode 46 occurs. As a result, display blur occurs and a soft focus image can be displayed. Therefore, in the above case, after the potential of the first counter electrode 47 is set to 0V, the above two display modes are switched depending on whether the potential of the second counter electrode 48 is set to 0V or + 15V. It becomes possible.

  In the case of the present embodiment, an electrophoretic display device capable of switching between the two display modes described above is formed without patterning the second counter electrode 48, although the process of forming the insulating film 49 is required in the manufacturing process. be able to.

[Third Embodiment]
Hereinafter, a third embodiment of the present invention will be described with reference to FIGS.
The basic configuration of the electrophoretic display device of this embodiment is the same as that of the first embodiment, and the point of having a switching function between the sharp image display mode and the soft focus image display mode is the same as that of the second embodiment. The configuration of the counter electrode is different from that of the second embodiment.
FIG. 11 is a plan view of first and second counter electrodes in the electrophoretic display device of the present embodiment. FIG. 12 is a cross-sectional view of the electrophoretic display device of the present embodiment, showing only the electrode configuration.
In FIG. 11 and FIG. 12, the same reference numerals are given to the same components as those used in the first embodiment, and the detailed description is omitted.

  In the second embodiment, the first counter electrode 47 is formed on the second counter electrode 48 via the insulating film 49. In contrast, in the electrophoretic display device 102 of the present embodiment, as shown in FIGS. 12A and 12B, the counter electrode 51 includes two electrodes, a first counter electrode 52 and a second counter electrode 53. The first counter electrode 52 and the second counter electrode 53 are juxtaposed on one surface of the substrate body 79. The first counter electrode 52 and the second counter electrode 53 have a shape that meshes in a comb shape. That is, after forming a transparent conductive film on the substrate body 79, the first counter electrode 52 and the second counter electrode 53 can be formed by patterning the transparent conductive film.

  As shown in FIG. 11, the first counter electrode 52 includes a plurality of island portions 80, a frame portion 81 </ b> A, and a plurality of connection portions 82, as in the second embodiment. However, the frame portion 81A does not surround the entire periphery of the plurality of island-shaped portions 80, and is formed so as to surround three sides (the upper side, the left side, and the right side in FIG. 11) of the four sides of the display unit 5. On the other hand, it is not formed on the remaining one side (the lower side in FIG. 11). The second counter electrode 53 is provided in a portion corresponding to the opening of the first counter electrode 52, that is, a portion corresponding to between the adjacent pixel electrodes 35. The first counter electrode 52 and the second counter electrode 53 are electrically insulated by being spaced apart with a minute interval. Thus, the first counter electrode 52 and the second counter electrode 53 can be individually applied with a voltage.

  The voltage application pattern when switching between the sharp image display mode and the soft focus image display mode is the same as in the second embodiment. That is, as shown in FIG. 12A, the potential of the central pixel electrode 35 is +15 V, the potential of the pixel electrode 35 on both sides thereof is 0 V, the potential of the first counter electrode 52 is 0 V, and the potential of the second counter electrode 53. When the voltage is set to 15 V, the spread of the vertical electric field is reduced, so that bleeding is suppressed and a sharp image can be displayed. On the other hand, as shown in FIG. 12B, the potential of the central pixel electrode 35 is +15 V, the potential of the pixel electrode 35 on both sides thereof is 0 V, the potential of the first counter electrode 52 is 0 V, and the potential of the second counter electrode 53. When 0 is set to 0 V, the vertical electric field spreads, so that display blur occurs and a soft focus image can be displayed.

  In the case of this embodiment, the process for forming the insulating film used in the second embodiment is not necessary, and an electrophoretic display device capable of switching between two display modes can be manufactured with a simple manufacturing process.

  In the above first to third embodiments, the configuration in which monochrome display is performed using the white particles 27 and the black particles 26 has been described. However, between the substrate body 79 on the counter substrate side and the counter electrode 51, or A configuration including a color filter between the counter electrode 51 and the electrophoretic element 32 may be employed. Thereby, an electrophoretic display device capable of color display with less color blur can be realized.

[Fourth Embodiment]
Hereinafter, a fourth embodiment of the present invention will be described with reference to FIGS.
The basic configuration of the electrophoretic display device of this embodiment is the same as that of the first embodiment, and the configuration of the counter electrode is different from that of the first embodiment.
FIG. 13 is a plan view of the counter electrode in the electrophoretic display device of this embodiment. FIG. 14 is a cross-sectional view of the electrophoretic display device of this embodiment. FIG. 15 is a diagram for explaining the operation of the electrophoretic display device of this embodiment.
13 to 15, the same reference numerals are given to the same components as those used in the first embodiment, and detailed description thereof will be omitted.

  In the electrophoretic display device 103 of this embodiment, the configuration on the element substrate 31 side is exactly the same as that of the first embodiment. On the counter substrate 55 side, as shown in FIGS. 13 and 14, the counter electrode 56 includes three electrodes, a first counter electrode 57, a second counter electrode 58, and a third counter electrode 59. The first counter electrode 57, the second counter electrode 58, and the third counter electrode 59 are formed so that these three counter electrodes 57, 58, and 59 are substantially contained in a region that faces one pixel electrode 35. Yes. The first counter electrode 57, the second counter electrode 58, and the third counter electrode 59 can be individually applied with voltages.

  As shown in FIG. 13, each of the first counter electrode 57, the second counter electrode 58, and the third counter electrode 59 includes an electrode portion 64 provided at a position facing a part of each pixel electrode 35 and a row direction. The first counter electrodes 57, the second counter electrodes 58, and the third counter electrodes 59 are connected to each other across the pixels 40 adjacent to each other in the left-right direction (FIG. 13). The area of the electrode part 64 of each counter electrode 57, 58, 59 is substantially equal, and occupies approximately 1/3 of the area of the pixel 40. However, the area of the electrode part 64 of each counter electrode 57, 58, 59 does not necessarily need to be equal, and may differ intentionally. Even if a configuration is adopted in which the area of the electrode portion of each counter electrode is different, gradation display described later is possible.

  The connecting portion 65 of the first counter electrode 57 is disposed on one end side (the upper side in FIG. 13) of the pixel 40, and the connecting portion 65 of the second counter electrode 58 and the connecting portion 65 of the third counter electrode 59 are the other end of the pixel 40. It arrange | positions to the side (lower side of FIG. 13). Due to this arrangement, the second counter electrode 58 and the third counter electrode 59 have a portion that intersects in a planar manner. For example, one of the counter electrodes is opposed to the other through an insulating film. By adopting a configuration that three-dimensionally intersects the upper layer side or the lower layer side of the electrode, the second counter electrode 58 and the third counter electrode 59 are electrically insulated. With such a configuration, the first counter electrode 57, the second counter electrode 58, and the third counter electrode 59 can be independently applied with voltages.

Hereinafter, a method of performing gradation display in the electrophoretic display device 103 having the above configuration will be described with reference to FIG.
As described in the first embodiment, a case where display is performed with positively charged black particles 26 and negatively charged white particles 27 will be described. In addition, since the moving direction and arrangement | positioning of the black particle 26 and the white particle 27 are mutually opposite, it pays attention only to the black particle 26 here, and the description about the white particle 27 is abbreviate | omitted. 15 (a) to 15 (d) show four pixels 40. The pixels PX1, PX2, PX3, and PX4 are sequentially arranged from the left side, and the three counter electrodes corresponding to one pixel 40 are as follows. The first counter electrode 57, the second counter electrode 58, and the third counter electrode 59 are sequentially formed from the left side. In addition, although a large number of black particles 26 actually exist in the electrophoretic element 32, here, in order to simplify the explanation of the gradation, each counter electrode 57, 58, 59 is 1 for the corresponding region. Assume that there are individual black particles 26.

In the initial state, as shown in FIG. 15A, the black particles are attracted to all the pixel electrodes 35, and all the pixels are displayed in white. In order to achieve such a state, for example, the potentials of all the pixel electrodes 35 may be set to 0V, and the potentials of all the counter electrodes 57, 58, and 59 may be set to 15V.
As the first step, as shown in FIG. 15B, the potential of the pixel electrode 35 of the pixel PX1, the pixel PX2, and the pixel PX3 is 0V, the potential of the pixel electrode 35 of the pixel PX4 is + 15V, and the potential of the first counter electrode 57. Is 0 V, and the potentials of the second counter electrode 58 and the third counter electrode 59 are +15 V, only the region corresponding to the first counter electrode 57 of the pixel PX4 has a low potential on the counter electrode 57 side. Only the black particles 26 in this region move to the counter electrode 57 side by the Coulomb force toward the counter electrode 57 side. At this time, in each pixel PX1 to PX4, the number of black particles 26 existing on the side of the counter electrodes 57, 58, 59 (viewing side) is 0 for the pixel PX1, 0 for the pixel PX2, 0 for the pixel PX3, There will be one PX4.
Note that the arrows in FIGS. 15B to 15D indicate the direction of the Coulomb force from the high potential side to the low potential side, and the hatched electrodes indicate the electrodes to which a voltage of +15 V is applied.

  Next, as a second step, as shown in FIG. 15C, the potential of the pixel electrode 35 of the pixel PX1 is 0V, the potential of the pixel electrode 35 of the pixel PX2, the pixel PX3, and the pixel PX4 is + 15V, and the first counter electrode. If the potential of 57 is + 15V, and the potential of the second counter electrode 58 and the third counter electrode 59 is 0V, the region corresponding to the first counter electrode 57 of the pixel PX1 has a low potential on the pixel electrode 35 side. Although a Coulomb force is generated from the side toward the pixel electrode 35 side, the black particles 26 in this region are originally on the pixel electrode 35 side and thus do not move. Further, the region corresponding to the second counter electrode 58 of the pixel PX2, the region corresponding to the third counter electrode 59 of the pixel PX2, the region corresponding to the second counter electrode 58 of the pixel PX3, and the third counter electrode 59 of the pixel PX3. In the corresponding region, the region corresponding to the second counter electrode 58 of the pixel PX4, and the region corresponding to the third counter electrode 59 of the pixel PX4, the counter electrode 58, 59 side has a low potential. , 59 side, the black particles 26 in these regions move to the counter electrodes 58, 59 side. Note that the black particles 26 in the region corresponding to the first counter electrode 57 of the pixel PX4 moved in the first step do not receive the Coulomb force and remain on the counter electrode 57 side. At this time, in each of the pixels PX1 to PX4, the number of black particles 26 existing on the counter electrodes 57, 58, and 59 (viewing side) is 0 for the pixel PX1, 2 for the pixel PX2, 2 for the pixel PX3, There are three PX4s.

  Next, as a third step, as shown in FIG. 15D, the potentials of the pixel electrodes 35 of the pixels PX1 and PX2 are 0V, the potentials of the pixel electrodes 35 of the pixels PX3 and PX4 are + 15V, and the first counter electrode 57 and the second counter electrode 58 have a potential of +15 V and the third counter electrode 59 has a potential of 0 V, the region corresponding to the first counter electrode 57 and the second counter electrode 58 of the pixel PX1, the first counter electrode of the pixel PX2. Since the pixel electrode 35 side has a low potential in the region corresponding to 57, a Coulomb force is generated from the counter electrode 57, 58 side to the pixel electrode 35 side. The black particles 26 in these regions are originally from the counter electrode 57, 58 side. Because it is, do not move. Further, since the region corresponding to the second counter electrode 58 of the pixel PX2 has a low potential on the pixel electrode 35 side, the black particles 26 in this region are moved to the pixel electrode 35 by the Coulomb force from the counter electrode 58 side to the pixel electrode 35 side. Move to the side. The black particles 26 in other areas remain at their current positions. At this time, in each of the pixels PX1 to PX4, the number of black particles 26 existing on the counter electrodes 57, 58, and 59 (viewing side) is 0 for the pixel PX1, 1 for the pixel PX2, 2 for the pixel PX3, There are three PX4s.

  In this way, from the initial state in which all the pixels PX1 to PX4 are in white display, the voltage application in the first to third steps is performed, so that the white display is performed from the pixel PX1 side toward the pixel PX4 side. In other words, gradation display that changes to black display can be performed.

  According to the electrophoretic display device 103 of the present embodiment, by changing the combination of applied voltages to the pixel electrode 35 of each pixel PX1 to PX4 and the corresponding first to third counter electrodes 57, 58, 59, one by one. The movement of the electrophoretic particles can be controlled for each region where the counter electrodes 57, 58, 59 are formed in one pixel. Therefore, it is possible to realize an electrophoretic display device capable of gradation display with a simple configuration without forming a pixel with a plurality of subpixels.

[Fifth Embodiment]
Hereinafter, a fifth embodiment of the present invention will be described with reference to FIG.
The basic configuration of the electrophoretic display device of this embodiment is the same as that of the fourth embodiment, and is different from the fourth embodiment in that a color filter is provided on the counter substrate.
FIG. 16 is a cross-sectional view of the electrophoretic display device of this embodiment.
In FIG. 16, the same components as those in FIG. 2 used in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the electrophoretic display device 104 of the present embodiment, as shown in FIG. 16, a color filter 91 is provided on one surface of the counter substrate 90 on the electrophoretic element 32 side of the substrate body 79. The color filter 91 is a color material layer of a different color for each of the first counter electrode 57, the second counter electrode 58, and the third counter electrode 59, for example, a color material layer of red (R), green (G), and blue (B). have. Further, on each color material layer of the color filter 91, the same first counter electrode 57, second counter electrode 58, and third counter electrode 59 as those in the fourth embodiment are provided. Other configurations are the same as those of the fourth embodiment.

  In the fourth embodiment, the method of performing gradation display has been described. However, the electrophoretic display device 104 according to the present embodiment includes the color filter 91, so that the pixel electrode 35 of each pixel 40 and the corresponding first to first electrodes. By changing the combination of applied voltages to the three counter electrodes 57, 58, 59, the movement of the electrophoretic particles is controlled in each pixel 40 for each region where the counter electrodes 57, 58, 59 are formed, and color display is performed. It can be carried out. Therefore, an electrophoretic display device capable of color display with a simple configuration can be realized without forming one pixel with a plurality of sub-pixels.

  The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention. In the above embodiment, the configuration in which the openings of the counter electrode are provided in all the regions between the adjacent pixel electrodes has been described. However, instead of this configuration, some of the regions between the adjacent pixel electrodes For example, a configuration in which the opening of the counter electrode is not provided, for example, a region in which the opening is provided and a region in which the opening is not provided may be alternately arranged. In that case, pixel blur occurs in the area between the pixel electrodes where the opening of the counter electrode is not provided, but such a configuration is adopted if the blur can be allowed when the entire image is viewed. It doesn't matter. In addition, the specific configuration such as the material, shape, number, and the like of each constituent member of the electrophoretic display device is not limited to the above embodiment, and can be changed as appropriate.

  In the above embodiment, an example of an active matrix type electrophoretic display device has been described. However, the present invention can also be applied to a simple matrix type (passive matrix type) electrophoretic display device.

[Electronics]
Next, the case where the electrophoretic display devices 100 to 104 of the above embodiment are applied to an electronic device will be described.
FIG. 17A is a perspective view illustrating a configuration of the electronic paper 1100. An electronic paper 1100 includes the electrophoretic display device of the above embodiment in a display area 1101. The electronic paper 1100 is flexible and includes a main body 1102 made of a rewritable sheet having the same texture and flexibility as conventional paper.

  FIG. 17B is a perspective view showing the configuration of the electronic notebook 1200. An electronic notebook 1200 is obtained by bundling a plurality of the electronic papers 1100 and sandwiching them between covers 1201. The cover 1201 includes display data input means (not shown) for inputting display data sent from an external device, for example. Thereby, according to the display data, the display content can be changed or updated while the electronic paper is bundled.

According to the electronic paper 1100 and the electronic notebook 1200 described above, since the electrophoretic display device according to the present invention is employed, an electronic apparatus including a display unit with less display blur and excellent display quality can be realized. .
In addition, said electronic device illustrates the electronic device which concerns on this invention, Comprising: The technical scope of this invention is not limited. For example, the electrophoretic display device according to the present invention can be suitably used for a display portion of an electronic device such as a mobile phone or a portable audio device.

  30 ... Element substrate (first substrate) 31, 45, 55, 90 ... Counter substrate (second substrate), 32 ... Electrophoretic element, 35 ... Pixel electrode, 37, 37A, 46, 51, 56 ... Counter electrode, 47, 52, 57 ... first counter electrode, 48, 53, 58 ... second counter electrode, 49 ... insulating film, 59 ... third counter electrode, 80 ... island-shaped portion, 81, 81A ... frame portion, 82, 82A DESCRIPTION OF SYMBOLS ... Connection part, 83 ... Opening part, 91 ... Color filter, 100, 101, 102, 103, 104 ... Electrophoretic display device, 1100 ... Electronic paper (electronic device), 1200 ... Electronic notebook (electronic device).

Claims (2)

An electrophoretic display device comprising a first substrate, a second substrate, and an electrophoretic element sandwiched between the first substrate and the second substrate,
A plurality of pixel electrodes provided on the first substrate and arranged in a row direction and a column direction; a counter electrode provided on the second substrate and applying a voltage to the electrophoretic element between the pixel electrodes; With
The counter electrode has a plurality of electrodes to which a voltage can be individually applied at a position facing one pixel electrode,
An electrophoretic display device that performs gradation display through a plurality of voltage application steps in which combinations of potentials at the plurality of pixel electrodes and potentials at a plurality of electrodes constituting the counter electrode are different. An electronic apparatus comprising the electrophoretic display device according to claim 1 .

Images