JP5526319B2 - Display sheet, display device, electronic apparatus, and display sheet driving method - Google Patents

Description

  The present invention relates to a display sheet, a display device, an electronic apparatus, and a display sheet driving method.

For example, an electrophoretic display using particle electrophoresis is known as an image display unit of electronic paper (see, for example, Patent Document 1). The electrophoretic display has excellent portability and power saving, and is particularly suitable as an image display unit for electronic paper.
Patent Document 1 discloses a display device having a first electrode (a plurality of pixel electrodes) and a second electrode (a common electrode) arranged opposite to each other, and a plurality of microcapsules provided therebetween. ing. Each microcapsule contains a dispersion liquid in which a plurality of positively charged black particles (second particles) and a plurality of negatively charged white particles (first particles) are dispersed in a liquid phase dispersion medium. Has been. In the display device of Patent Document 1, a desired electric field is applied to each microcapsule, and a black display state in which black particles are unevenly distributed on the display surface side (second electrode side) and white particles are on the display surface side. By selecting one of the unevenly distributed white display states, a desired image is displayed on the display surface.
However, in such a display device of Patent Document 1, an electric field corresponding to the second image is applied to each microcapsule in order to switch the image displayed on the display surface from the first image to the second image. The afterimage resulting from the first image is displayed together with the second image on the display surface.

  Such a problem is considered to occur for the following reason. For example, when describing one microcapsule, when switching from the black display state to the white display state, the black particles are moved from the second electrode side to the first electrode side, and the white particles are moved from the first electrode side to the second electrode side. To the electrode side. At this time, since the white particles are dispersed in the liquid phase dispersion medium, the white particles reach the second electrode side in a short time. Then, while the black particles are still moving near the second electrode, the white particles have moved to the second electrode, and some black particles are surrounded by the plurality of white particles, and the black particles Remains on the second electrode side as it is. As described above, the particles that originally have to move to the first electrode side cannot move but remain on the second electrode side, and this particle affects the display color. Such an afterimage is considered to be one cause.

JP 2009-145873 A

  An object of the present invention is to provide a display sheet, a display device, an electronic apparatus, and a display sheet driving method capable of reliably preventing the occurrence of an afterimage.

Such an object is achieved by the present invention described below.
The display sheet of the present invention includes a plurality of first particles that are positively or negatively charged, and a plurality of colors that are charged at the opposite pole to the first particles and have a light reflectance lower than that of the first particles. It has a display layer provided with a plurality of storage parts for storing the second particles,
It said plurality of housing portions by the action of an electric field, said first particles in the accommodating portion together with the second particles the plurality of accommodating portions to one surface side of each of said display layer is unevenly distributed Is dispersed in the first display state, or the second particles are unevenly distributed on the other surface side of the display layer and the first particles are dispersed in the housing portion. Can be switched to
A display sheet that displays a desired image on the display surface provided on the one surface side of the display layer by selecting the first display state or the second display state in the plurality of storage units, respectively. Because
The plurality of second particles move along the inner surface while being in contact with the inner surface of the housing portion by the action of the electric field,
When switching the first image displayed on the display surface to a second image different from the first image, an electric field for displaying the second image is applied to the plurality of accommodating portions. Prior to the configuration, a reset electric field for causing a second display state to act on at least the housing portion in the first display state among the plurality of housing portions,
The reset electric field includes a first period in which the second particles are moved to the one surface side and the first particles are moved to the other surface side, and after the first period. And a second period for moving the first particles to the one surface side and moving the second particles to the other surface side.
Thereby, the display sheet which can prevent generation | occurrence | production of an afterimage reliably can be provided.

The display sheet of the present invention contains a plurality of first particles that are uncharged and a plurality of second particles that are positively or negatively charged and have a light reflectance lower than that of the first particles. A display layer having a housing portion of
It said plurality of housing portions by the action of an electric field, said first particles in the accommodating portion together with the second particles the plurality of accommodating portions to one surface side of each of said display layer is unevenly distributed Is dispersed in the first display state, or the second particles are unevenly distributed on the other surface side of the display layer and the first particles are dispersed in the housing portion. Can be switched to
A display sheet that displays a desired image on the display surface provided on the one surface side of the display layer by selecting the first display state or the second display state in the plurality of storage units, respectively. Because
The plurality of second particles move along the inner surface while being in contact with the inner surface of the housing portion by the action of the electric field,
When switching the first image displayed on the display surface to a second image different from the first image, an electric field for displaying the second image is applied to the plurality of accommodating portions. Prior to the configuration, a reset electric field for causing a second display state to act on at least the housing portion in the first display state among the plurality of housing portions,
The reset electric field includes a first period in which the second particles are moved to the one surface side and the first particles are moved to the other surface side, and after the first period. And a second period for moving the first particles to the one surface side and moving the second particles to the other surface side.
Thereby, the display sheet which can prevent generation | occurrence | production of an afterimage reliably can be provided.

In the display sheet of the present invention, it is preferable that the reset electric field is applied only to the housing portion in the first display state.
Thereby, since it is possible to prevent an unnecessary electric field from acting on the housing portion that has been in the white display state from the beginning, the reliability of the device is improved and power saving can be achieved.

In the display sheet of the present invention, it is preferable that the reset electric field has a third period in which no electric field is generated between the first period and the second period.
Thereby, since the movement of the first particle and the second particle can be temporarily stopped, the movement of these particles can be smoothly performed in the second period.
In the display sheet of the present invention, the third period is preferably within 2 seconds.
Thereby, it is possible to prevent the first particles attracted to the other side of the display surface during the first period from being dispersed again (returning to the original state).

In the display sheet of the present invention, the first period is preferably 0.2 seconds or longer.
Thereby, 1st particle | grains can fully be moved to the other surface side of a display surface.
In the display sheet of the present invention, the second period is preferably 0.2 seconds or longer.
Accordingly, the first particles can be moved more reliably to one surface side of the display surface, and the second particles can be moved to the other surface side of the display surface.

In the display sheet of the present invention, it is preferable that the strength of the electric field in the first period is equal to the strength of the electric field applied to the housing portion when the housing portion is in the first display state.
This simplifies the device configuration (circuit configuration).
In the display sheet of the present invention, it is preferable that the strength of the electric field in the second period is equal to the strength of the electric field applied to the housing portion when the housing portion is in the second display state.
This simplifies the device configuration (circuit configuration).

In the display sheet of this invention, it is preferable that the said 2nd particle is contacting the inner surface of the said accommodating part with an electrostatic force.
Thereby, easily and reliably, Ru can contact the second particles to the inner surface of the housing portion.

In the display sheet of the present invention, it is preferable that the force for holding the second particles on the inner surface of the housing portion is larger than the electrostatic force acting on the second particles due to the electric field acting on the housing portion. .
Thereby, the 2nd particle can move along the inner surface of a storage part more reliably, contacting the inner surface of a storage part.

In the display sheet of the present invention, it is preferable that the storage portion defines a spherical space, and the plurality of first particles and the plurality of second particles are stored in the space.
Thereby, it is possible to move the second particles along the inner surface of the accommodating portion more smoothly and reliably.
The display device of the present invention includes the display sheet of the present invention.
Thereby, the display apparatus which can prevent generation | occurrence | production of an afterimage reliably can be provided.
An electronic apparatus according to the present invention includes the display device according to the present invention.
Thereby, the electronic device which can prevent generation | occurrence | production of an afterimage reliably can be provided.

The display sheet driving method of the present invention includes a plurality of first particles that are positively or negatively charged, and a color that is charged at a polarity opposite to the first particles and has a light reflectance lower than that of the first particles. A display layer comprising a plurality of storage portions for storing a plurality of second particles of
It said plurality of housing portions by the action of an electric field, said first particles in the accommodating portion together with the second particles the plurality of accommodating portions to one surface side of each of said display layer is unevenly distributed Is dispersed in the first display state, or the second particles are unevenly distributed on the other surface side of the display layer and the first particles are dispersed in the housing portion. Can be switched to
A display sheet that displays a desired image on the display surface provided on the one surface side of the display layer by selecting the first display state or the second display state in the plurality of storage units, respectively. Driving method,
The plurality of second particles move along the inner surface while being in contact with the inner surface of the housing portion by the action of the electric field,
When switching the first image displayed on the display surface to a second image different from the first image, an electric field for displaying the second image is applied to the plurality of accommodating portions. Prior to driving, an electric field for resetting for causing the second display state to act on at least the housing portion in the first display state among the plurality of housing portions,
The reset electric field includes a first period in which the second particles are moved to the one surface side and the first particles are moved to the other surface side, and after the first period. And a second period for moving the first particles to the one surface side and moving the second particles to the other surface side.
According to such a driving method, afterimage generation can be reliably prevented.

The display sheet driving method of the present invention includes a plurality of non-charged first particles and a plurality of second particles that are positively or negatively charged and have a light reflectance lower than that of the first particles. It has a display layer provided with a plurality of accommodating parts to accommodate,
It said plurality of housing portions by the action of an electric field, said first particles in the accommodating portion together with the second particles the plurality of accommodating portions to one surface side of each of said display layer is unevenly distributed Is dispersed in the first display state, or the second particles are unevenly distributed on the other surface side of the display layer and the first particles are dispersed in the housing portion. Can be switched to
A display sheet that displays a desired image on the display surface provided on the one surface side of the display layer by selecting the first display state or the second display state in the plurality of storage units, respectively. Driving method,
The plurality of second particles move along the inner surface while being in contact with the inner surface of the housing portion by the action of the electric field,
When switching the first image displayed on the display surface to a second image different from the first image, an electric field for displaying the second image is applied to the plurality of accommodating portions. Prior to driving, an electric field for resetting for causing the second display state to act on at least the housing portion in the first display state among the plurality of housing portions,
The reset electric field includes a first period in which the second particles are moved to the one surface side and the first particles are moved to the other surface side, and after the first period. And a second period for moving the first particles to the one surface side and moving the second particles to the other surface side.
According to such a driving method, afterimage generation can be reliably prevented.

1 is a longitudinal sectional view schematically showing a first embodiment of a display device of the present invention. It is a schematic diagram for demonstrating operation | movement of the display apparatus shown in FIG. It is a schematic diagram for demonstrating operation | movement of the display apparatus shown in FIG. 2 is a graph (potential curve) showing the relationship between the distance between the surface of the colored particles and the inner surface of the capsule body and the potential of the colored particles in the display device shown in FIG. It is a schematic diagram for demonstrating operation | movement of the display apparatus shown in FIG. It is sectional drawing for demonstrating the conventional problem using the display apparatus shown in FIG. It is a top view for demonstrating the conventional problem using the display apparatus shown in FIG. It is sectional drawing for demonstrating operation | movement of the display apparatus shown in FIG. It is a longitudinal cross-sectional view which shows 2nd Embodiment of the display apparatus of this invention typically. It is a perspective view which shows embodiment at the time of applying the electronic device of this invention to electronic paper. It is a figure which shows embodiment at the time of applying the electronic device of this invention to a display.

Hereinafter, a display sheet, a display device, and an electronic device of the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.
<First Embodiment>
1. First, a display device (display device of the present invention) to which the display sheet of the present invention is applied will be described.

  FIG. 1 is a longitudinal sectional view schematically showing a first embodiment of the display device of the present invention, FIGS. 2 and 3 are schematic diagrams for explaining the operation of the display device shown in FIG. 1, and FIG. In the display device shown in FIG. 1, a graph (potential curve) showing the relationship between the distance between the surface of the colored particles and the inner surface of the capsule body and the potential of the colored particles, FIG. FIG. 6 is a schematic view for explaining the operation, FIG. 6 is a cross-sectional view for explaining a conventional problem using the display device shown in FIG. 1, and FIG. 7 is a cross-sectional view for explaining the conventional problem using the display device shown in FIG. FIG. 8 is a plan view for explaining the operation of the display device shown in FIG.

In the following description, for convenience of explanation, the upper side in FIGS. Further, in FIGS. 2, 3, 5, 6, and 8, the capsule body 401 is simply described in one layer.
As shown in FIG. 1, the display device 20 includes a display sheet (front plane) 21, a circuit board (back plane) 22, an adhesive layer 8 that joins the display sheet 21 and the circuit board 22, and the display sheet 21. And a sealing portion 7 that hermetically seals a gap between the circuit board 22 and the circuit board 22.

The display sheet 21 is provided on a substrate 12 having a flat base 2 and a second electrode 4 provided on the lower surface of the base 2, and on the lower surface (one surface) side of the substrate 12. Part) 40 and a display layer 400 composed of a binder 41.
On the other hand, the circuit board 22 includes a counter substrate 11 including a flat base 1 and a plurality of first electrodes 3 provided on the upper surface of the base 1, and the counter substrate 11 (base 1), for example, And a circuit (not shown) including a switching element such as a TFT.

Hereinafter, the structure of each part is demonstrated sequentially.
The base 1 and the base 2 are each composed of a sheet-like (flat plate) member, and have a function of supporting and protecting each member disposed therebetween. Each of the base portions 1 and 2 may be either flexible or hard, but is preferably flexible. By using the bases 1 and 2 having flexibility, it is possible to obtain a display device 20 having flexibility, that is, for example, a display device 20 useful in constructing electronic paper.

  Moreover, when each base part (base material layer) 1 and 2 shall have flexibility, as the constituent material, for example, polyolefin, such as polyethylene, modified polyolefin, polyamide, thermoplastic polyimide, polyether, Examples include polyetheretherketone, polyurethane-based, chlorinated polyethylene-based thermoplastic elastomers, etc., and copolymers, blends, polymer alloys, etc. mainly composed of these, and one or more of these Can be mixed and used.

  The average thicknesses of the bases 1 and 2 are appropriately set depending on the constituent material, application, etc., and are not particularly limited. However, when having flexibility, it is preferably about 20 to 500 μm, More preferably, it is about 25-250 micrometers. Thereby, size reduction (especially thickness reduction) of the display apparatus 20 can be achieved, aiming at harmony with the softness | flexibility of the display apparatus 20, and intensity | strength.

A first electrode 3 and a second electrode 4 (one pair) forming layers (films) on the surfaces of the bases 1 and 2 on the side of the microcapsule 40, that is, the upper surface of the base 1 and the lower surface of the base 2, respectively. Electrode). That is, the first electrode 3 and the second electrode 4 are disposed to face each other with the display layer 400 interposed therebetween.
When a voltage is applied between the first electrode 3 and the second electrode 4, an electric field is generated between them, and this electric field acts on electrophoretic particles 5 described later in the microcapsule 40.

In the present embodiment, the second electrode 4 is a common electrode, the first electrode 3 is an individual electrode (pixel electrode connected to a switching element) divided in a matrix (matrix), A portion where two electrodes 4 and one first electrode 3 overlap constitute one pixel.
Note that the second electrode 4 may also be divided into a plurality of parts in the same manner as the first electrode 3. Alternatively, the first electrode 3 may be divided into stripes, and the second electrode may be similarly divided into stripes and arranged so as to intersect with each other.

In the present embodiment, as shown in FIG. 1, one microcapsule 40 is included in one pixel. However, the present invention is not limited to this. For example, a plurality of (for example, about ten) microcapsules are included in one pixel. The structure including the capsule 40 may be used.
The constituent materials of the electrodes 3 and 4 are not particularly limited as long as they are substantially conductive, for example, metal materials such as copper, aluminum or alloys containing these, and carbon-based materials such as carbon black. An ion in which an ionic substance such as NaCl, Cu (CF ₃ SO ₃ ) ₂ is dispersed in a material, an electronically conductive polymer material such as polyacetylene, polyfluorene or a derivative thereof, or a matrix resin such as polyvinyl alcohol or polycarbonate. Various conductive materials such as conductive polymer materials and conductive oxide materials such as indium oxide (IO) can be used, and one or more of these can be used in combination.
The average thicknesses of the electrodes 3 and 4 are appropriately set depending on the constituent materials and applications, and are not particularly limited, but are preferably about 0.05 to 10 μm, and about 0.05 to 5 μm. Is more preferable.

  Of the bases 1, 2 and the electrodes 3, 4, the base and the electrodes (in the present embodiment, the base 2 and the second electrode 4) disposed on the display surface 201 side have optical transparency, respectively. That is, it is made substantially transparent (colorless transparent, colored transparent or translucent). Thereby, the state of the colored particles 5b and the white particles 5a described later, that is, the information (image) displayed on the display device 20 can be easily recognized visually.

In the display sheet 21, a display layer 400 is provided in contact with the lower surface of the second electrode 4. The display layer 400 has a configuration in which a plurality of microcapsules (accommodating portions) 40 in which the electrophoretic dispersion liquid 10 is enclosed in a capsule body 401 are held by a binder 41.
As shown in FIG. 1, the microcapsules 40 are formed in a single layer (that is, one by one without overlapping in the thickness direction) between the counter substrate 11 and the substrate 12 so as to be arranged in the vertical and horizontal directions, and are displayed. The layer 400 is disposed in the entire thickness direction. That is, in the display layer 400, the microcapsules 40 adjacent to each other in the surface direction are in contact with each other and are arranged without being stacked in the thickness direction. The microcapsules 40 are substantially spherical (spherical) without being compressed in the vertical direction.

  Here, when the display device 20 is incorporated into electronic paper that requires flexibility, the display device 20 is similarly bent each time the electronic paper is bent. A pressure is applied between the substrate 22 and the display sheet 21. At this time, as shown in FIG. 1, since the microcapsule 40 is in point contact with both the first electrode 3 and the second electrode 4, the load (per unit area) of the contacting portion ( More specifically, a pressure of about 0.2 MPa or more and 1.5 MPa or less is applied. Even if such a pressure is applied between the circuit board 22 and the display sheet 21, the microcapsule 40 has a strength that maintains a spherical shape between the counter substrate 11 and the substrate 12. Is preferred. By adopting such a configuration, both the pressure resistance and bleed resistance of the microcapsule 40 can be improved, so that the display device 20 can operate stably for a long period of time.

  Specifically, the capsule strength of the microcapsule 40 is preferably 0.6 MPa or more, more preferably 1.0 MPa or more, and further preferably 3.0 MPa or more. The upper limit of the capsule strength is not particularly limited, but is about 50 MPa, for example. In addition, the capsule strength of the microcapsule 40 means the compressive strength per microcapsule measured using a micro compression tester (for example, product name: MCT-W500, manufactured by Shimadzu Corporation).

  Further, the microcapsule 40 has a capsule strength that is not crushed even when the steel ball is dropped from a height of preferably 10 cm or more, more preferably 20 cm or more, and even more preferably 30 cm or more in the steel ball drop test. preferable. In general, when the microcapsule 40 has only a capsule strength that is crushed when the steel ball is dropped from a height lower than the above height in the steel ball drop test, the display device 20 using such a microcapsule 40 is used. If it is accidentally dropped, the microcapsule 40 may be crushed by the impact of the drop, and there is a possibility that data display at that portion (pixel) cannot be performed. In the steel ball drop test, after placing the display device 20 on a butadiene rubber having a thickness of 3 mm, a steel ball having a diameter of 11 mm and a mass of 5.468 g is placed on the display layer 400 of the display device 20 from an arbitrary height. It is performed by observing with a light microscope the microcapsules 40 that are vertically dropped and are present at the location where the steel ball hits.

  In addition, the microcapsule 40 has a certain degree of flexibility, and its shape changes depending on the external pressure. Therefore, the microcapsule 40 is not particularly limited. It is preferable that it is a shape. That is, it is preferable that the microcapsules 40 exist between the counter substrate 11 and the substrate 12 while maintaining a more spherical shape.

  The degree of the spherical shape of the microcapsule 40 can be expressed by using the ratio of the width of the microcapsule 40 and the height of the microcapsule 40 (the width of the microcapsule 40 / the height of the microcapsule 40) as an index. The width of the microcapsules 40 / the height (average value) of the microcapsules 40 is, for example, the average value of the particle diameter in the display layer 400 with respect to the height (thickness direction) and width (plane direction) of each microcapsule 40. Each is obtained and the ratio (width / height) of these average values is obtained.

  The width of the microcapsules 40 thus obtained / the height (average value) of the microcapsules 40 is not particularly limited, but is preferably about 1.0 or more and 1.2 or less, preferably 1.0 or more. More preferably, it is about 1.15 or less. When the width of the microcapsule 40 / the height of the microcapsule 40 is within the above range, the microcapsule 40 exists between the counter substrate 11 and the substrate 12 in a state of maintaining a substantially spherical shape. Can be said. In this way, the microcapsules 40 that maintain a substantially spherical shape are arranged in the display layer 400 such that those adjacent in the surface direction are in contact with each other and are not stacked in the thickness direction. Accordingly, the display device 20 including the display layer 400 exhibits high contrast.

  The particle size of the microcapsule 40 is not particularly limited, but is preferably about 5 μm or more and 300 μm or less, more preferably about 10 μm or more and 200 μm or less, and about 15 μm or more and 150 μm or less. Further preferred. If the particle size of the microcapsule 40 is less than 5 μm, depending on the hue, particle size and amount (number) of the electrophoretic particles 5 accommodated in the microcapsule 40, a sufficient display density may not be obtained. There is. On the contrary, when the particle size of the microcapsule exceeds 300 μm, the capsule strength of the microcapsule 40 may be reduced depending on the configuration of the microcapsule 40 (constituent materials, etc.). The electrophoretic properties of the electrophoretic particles 5 in the electrophoretic dispersion 10 are not sufficiently exhibited, and the driving voltage for display may be increased. The particle size of the microcapsule 40 is a laser diffraction / scattering particle size distribution measuring device (for example, product name: LA-910, manufactured by HORIBA, Ltd., Coulter type (pore electrical resistance method) (for example, Coulter). It means a volume average particle diameter measured with a counter Multisizer 3 (Beckman Coulter, Inc.).

Further, the variation coefficient of the particle size of the microcapsule 40 (that is, the narrowness of the particle size distribution) is not particularly limited, but is preferably 30% or less, more preferably 20% or less, and 10% or less. More preferably. When the variation coefficient of the particle size of the microcapsule 40 exceeds 30%, there are few microcapsules 40 having an effective particle size, and it may be necessary to use a large number of microcapsules. Further, even when the same voltage is applied between the first electrode 3 and the second electrode 4, the magnitude of the applied electric field differs between the plurality of microcapsules 40, and the display characteristics are deteriorated. There is a fear.
Note that the particle size of the microcapsules 40 and the coefficient of variation thereof greatly depend on the particle size and particle size distribution of the dispersion liquid dispersed in the aqueous medium when the microcapsules 40 are manufactured. Therefore, the microcapsule 40 having a desired particle diameter and its coefficient of variation can be obtained by appropriately adjusting the dispersion conditions of the dispersion.

In the present embodiment, as shown in FIG. 1, the capsule main body 401 includes a first capsule layer 402 and a second capsule layer 403 disposed outside the first capsule layer 402. ing. The first capsule layer 402 and the second capsule layer 403 each have a spherical shell shape, and the second capsule layer 403 covers the outer surface of the first capsule layer 402. As a result, the characteristics of the first capsule layer 402 and the second capsule layer 403 can be synergistically imparted to the capsule body 401.
In the capsule body 401, only one of the first capsule layer 402 and the second capsule layer 403 may be charged, or both may be charged. It does not have to be charged.

  The constituent materials of the first capsule layer 402 and the second capsule layer 403 include, for example, a material containing rubber such as gum arabic, a composite material of gum arabic and gelatin, a urethane resin, an acrylic resin, and an epoxy, respectively. Various resin materials such as resin, melamine resin, urea resin, polyamide, and polyether can be used, and one or more of these can be used in combination.

  In addition, as the resins constituting the first capsule layer 402 and the second capsule layer 403, those that form a crosslinked (stereocrosslinked) structure with a crosslinking agent may be used. Thereby, the strength of the first capsule layer 402 and the second capsule layer 403 can be further improved. As a result, it is possible to more reliably prevent the microcapsule 40 from collapsing.

  Here, whether or not each of the first capsule layer 402 and the second capsule layer 403 is charged, the amount of charge, the charge density, the polarity, and the like are also related to the relationship with the liquid phase dispersion medium 6. Therefore, each of the first capsule layer 402 and the second capsule layer 403 has a constituent material (combination of constituent materials), a blending ratio thereof, various conditions at the time of formation, and the like according to the liquid phase dispersion medium 6 to be used. It is set appropriately, and a net charge is given to the inside of the capsule body 401, and its polarity and charge amount are adjusted. In this case, for example, an additive such as a charge imparting agent may be added.

  Further, it is preferable that the first capsule layer 402 and the second capsule layer 403 are chemically bonded at these interfaces. Thereby, even if a pressure is applied between the circuit board 22 and the display sheet 21, it is possible to reliably prevent the separation between the first capsule layer 402 and the second capsule layer 403. . As a result, the microcapsule 40 can be more reliably prevented from collapsing due to the pressure at the time of joining the display layer 400 and the circuit board 22 or the impact or pressure applied during use / storage as a display device. can do.

In the present embodiment, the capsule body 401 has a two-layer configuration including the first capsule layer 402 and the second capsule layer 403. However, the present invention is not limited to such a two-layer configuration. A multi-layer structure having more than one layer may be used.
The electrophoretic dispersion liquid 10 enclosed in the capsule body 401 is obtained by dispersing (suspending) the electrophoretic particles 5 in the liquid phase dispersion medium 6. The electrophoretic particles 5 include a plurality of white particles (first particles) 5a that are positively or negatively charged, and colored particles that are charged to a polarity opposite to that of the white particles 5a and have a light reflectance lower than that of the white particles ( Second particles) 5b.
For example, the electrophoretic particles 5 are dispersed in the liquid phase dispersion medium 6 by combining one or more of paint shaker method, ball mill method, media mill method, ultrasonic dispersion method, stirring dispersion method, and the like. be able to.

  As the liquid phase dispersion medium 6, a medium having a low solubility in the capsule body 401 and a relatively high insulating property is preferably used. Examples of the liquid phase dispersion medium 6 include various types of water (for example, distilled water and pure water), alcohols such as methanol, cellosolves such as methyl cellosolve, esters such as methyl acetate, ketones such as acetone, Aliphatic hydrocarbons such as pentane (liquid paraffin), alicyclic hydrocarbons such as cyclohexane, aromatic hydrocarbons such as benzene, halogenated hydrocarbons such as methylene chloride, and aromatic complex rings such as pyridine. , Nitriles such as acetonitrile, amides such as N, N-dimethylformamide, carboxylates or other various oils such as silicone oil, and the like can be used alone or as a mixture. Among them, the liquid phase dispersion medium 6 is preferably a hydrocarbon or silicone oil having a boiling point of 80 degrees or more.

  Further, in the liquid phase dispersion medium 6 (electrophoretic dispersion liquid 10), for example, a surfactant (anionic or cationic) such as an electrolyte or an alkenyl succinate, a metal soap, a resin material, if necessary. Various additives such as a charge control agent composed of particles such as rubber materials, oils, varnishes, and compounds, a dispersant such as a silane coupling agent, a lubricant, and a stabilizer may be added. When the liquid phase dispersion medium 6 is colored, various dyes such as anthraquinone dyes, azo dyes, and indigoid dyes may be dissolved in the liquid phase dispersion medium 6 as necessary.

The colored particles 5 b in the electrophoretic dispersion 10 are in contact (attached) to the inner surface of the capsule body 401 by being biased in a direction approaching the inner surface of the capsule body 401. In other words, the colored particles 5 b are held so as to be movable along the inner surface of the capsule body 401. Such colored particles 5b are charged with a predetermined polarity (positive or negative).
Further, the net charge inside the capsule body 401 (not including the capsule body 401 itself) (the total value (total) of all charges including the charge of the colored particles 5b) is not zero (there is a net charge) The polarity is the same (same polarity) as the polarity of the charge of the colored particles 5b. Therefore, the colored particles 5b are pressed (biased) on the inner surface of the capsule body 401 mainly by the repulsive force (repulsive force) due to the electrostatic force between the self and the same-polarity charge, and are attached movably. ing. In addition, it seems that the colored particles 5 b are adsorbed on the inner surface of the capsule body 401.
Such colored particles 5b are particles that have a charge and can move in the liquid phase dispersion medium 6 along the inner surface of the capsule body 401 by the action of an electric field. That is, as will be described later, the colored particles 5b move along the inner surface while contacting the inner surface of the capsule body 401.

  In the following description, each force acting on the colored particles 5b in the capsule body 401 is based on the inner surface of the capsule body 401 and is a force in a direction approaching the inner surface of the capsule body 401 unless otherwise specified. (Force toward the outside of the capsule body 401) is referred to as "attraction", and force in a direction away from the inner surface (force toward the center of the capsule body 401) is referred to as "repulsive force".

On the other hand, as described above, the white particles 5a are charged with the opposite polarity to the colored particles 5b, that is, the same polarity as the capsule body 401. Thereby, it can prevent that the white particle 5a is urged | biased in the direction which approaches the inner surface of the capsule main body 401, and contacts (attaches) to the inner surface. In other words, since the polarity of the electric charge of the white particles 5a is opposite to the net electric charge inside the capsule body 401, the phenomenon that the white particles 5a are pressed against the inner surface of the capsule body 401 does not occur. Therefore, the white particles 5 a are in a state of being uniformly dispersed in the liquid phase dispersion medium 6.
Any electrophoretic particle 5 may be used as long as it has a charge. Although there is no particular limitation, at least one of pigment particles, resin particles, or composite particles thereof is preferably used. used. These particles have the advantage that they are easy to manufacture and the charge can be controlled relatively easily.

  Examples of the pigment constituting the pigment particles include black pigments such as aniline black, carbon black, titanium black and copper chromite, white pigments such as titanium oxide and antimony oxide, azo pigments such as monoazo, isoindolinone, Yellow pigments such as yellow lead, red pigments such as quinacridone red and chrome vermilion, blue pigments such as phthalocyanine blue and indanthrene blue, green pigments such as phthalocyanine green, etc. They can be used in combination.

Examples of the resin material constituting the resin particles include acrylic resin, urethane resin, urea resin, epoxy resin, polystyrene, polyester, and the like, and one or more of these are combined. Can be used.
The composite particles include, for example, those in which the surface of the pigment particles is coated with a resin material or other pigment, those in which the surface of the resin particles is coated with a pigment, or a mixture in which the pigment and the resin material are mixed at an appropriate composition ratio. The particle | grains comprised by these, etc. are mentioned.

Examples of particles obtained by coating the surface of pigment particles with other pigments include those obtained by coating the surface of titanium oxide particles with silicon oxide or aluminum oxide. Such particles are suitable as white particles 5a. Used. Further, the carbon black particles or particles covering the surface thereof are suitably used as the colored particles (black particles) 5b.
Further, the shape of the electrophoretic particles 5 is not particularly limited, but is preferably spherical.

The average particle diameter of the electrophoretic particles 5 is not particularly limited, but is preferably about 10 nm to 3 μm, more preferably about 20 nm to 2 μm, and most preferably about 20 nm to 800 nm. By setting the average particle diameter of the electrophoretic particles 5 within the above range, aggregation of the electrophoretic particles 5 can be prevented, and precipitation of the white particles 5a in the liquid phase dispersion medium 6 can be reliably prevented. The liquid phase dispersion medium 6 can be dispersed, and as a result, the display quality of the display device 20 can be suitably prevented from deteriorating.
Note that when two different types of particles are used as in this embodiment, there is no particular problem even if the average particle sizes of the two types of particles are different. In the method of the present invention, a high value of the display contrast of the display device 20 is obtained.

  Here, in the display device 20, as described above, the net charge (total value (total) of all charges including the charge of the colored particles 5b) inside the capsule body 401 (not including the capsule body 401 itself) is , It is not zero (there is a net charge), and its polarity is the same (same polarity) as that of the colored particles 5b. Therefore, the attractive force acting between the colored particles 5b and the capsule body 401, that is, the electrostatic force (attractive force) due to the net charge (including the charge of the colored particles 5b) inside the capsule body 401 (not including the capsule body 401 itself). Coloring by the attractive force that is the sum (the resultant force) of van der Waals force (attractive force) between the colored particles 5b and the capsule body 401 and repulsive force due to osmotic pressure (by steric stabilization treatment using a graft polymer) The particles 5b are in contact with the inner surface of the capsule body 401.

As shown in FIG. 2, first, when no voltage is applied between the first electrode 3 and the second electrode 4, the colored particles 5 b contact (adhere) to the inner surface of the capsule body 401. It stops at a predetermined position, and the white particles 5 a are dispersed in the liquid phase dispersion medium 6.
The colored particles 5b may all be in contact with the inner surface of the capsule body 401, but this is not a limitation, and some of the colored particles 5b may not be in contact with the inner surface of the capsule body 401. . For example, when the colored particles 5b are arranged in two layers, the second colored particles 5b are in contact with the first colored particles 5b. This is the same during movement of the colored particles 5b described later.

Next, when a voltage is applied between the first electrode 3 and the second electrode 4, an electric field is generated between the first electrode 3 and the second electrode 4, and the colored particles 5b are encapsulated. While contacting (adhering) to the inner surface of the main body 401, it moves toward one of the electrodes along the inner surface of the capsule main body 401 according to the electric field, and the white particles 5a are dispersed in the liquid phase according to the electric field. It moves in the medium 6 linearly toward one of the electrodes. When the application of the voltage is stopped, the colored particles 5b stop moving, that is, come into contact with the inner surface of the capsule body 401 and stop at a predetermined position, and the white particles 5a are transferred to the liquid phase dispersion medium 6. Return to the distributed state.
The microcapsule 40 has been described above.

The binder 41 is in close contact with the outer surface of the microcapsule 40 and covers the microcapsule 40, and a gap (gap) formed between the microcapsules 40 is filled with the binder 41.
That is, the binder 41 is, for example, for the purpose of bonding the counter substrate 11 and the substrate 12, for the purpose of fixing the microcapsule 40 between the counter substrate 11 and the substrate 12, and between the first electrode 3 and the second electrode 4. For the purpose of ensuring the insulation property of the microcapsule 40 and for the purpose of filling a gap between the microcapsule 40 and the microcapsule 40 to generate a strong electric field. Thereby, durability, reliability, and display performance of the display device 20 can be further improved.

The binder 41 is a resin material (insulating property) having excellent affinity (adhesion) with the electrodes 3 and 4 and the capsule body 401 (microcapsule 40), excellent insulating properties, and a relatively high dielectric constant. Alternatively, a resin material through which only a minute current flows) is preferably used.
Examples of such a binder 41 include various types of thermoplastic resins such as polyethylene, polypropylene, ABS resin, methacrylic ester resin, methyl methacrylate resin, vinyl chloride resin, and cellulose resin, silicone resin, and urethane resin. Examples of the resin material include one or two or more of them.

In the present embodiment, the display sheet 21 and the circuit board 22 are bonded via the adhesive layer 8. Thereby, the display sheet 21 and the circuit board 22 can be more reliably fixed.
Such an adhesive layer 8 is preferably made of, for example, polyurethane as a main material.

  As the polyurethane, for example, at least one of tetramethylxylene diisocyanate (TMXDI), hexamethylene diisocyanate (HMDI) or derivatives thereof is used as an isocyanate component, and polypropylene glycol (PPG), polytetramethylene glycol (PTMG) or these are used. And those having at least one of these derivatives as a polyol component.

The constituent material of the adhesive layer 8 is not limited to polyurethane, and other materials such as polyethylene, chlorinated polyethylene, ABS resin, vinyl-acrylic acid ester copolymer, fluorine resin, silicone resin, etc. Various resin materials can be mentioned, and one or more of these can be used in combination.
Further, a sealing portion 7 is provided between the base portion 1 and the base portion 2 and along the edge portions thereof. The electrodes 3 and 4, the display layer 400, and the adhesive layer 8 are hermetically sealed by the sealing portion 7. Thereby, it is possible to prevent moisture from entering the display device 20 and more reliably prevent display performance deterioration of the display device 20.

Examples of the constituent material of the sealing portion 7 include thermoplastic resins such as acrylic resins, urethane resins, and olefin resins, epoxy resins, melamine resins, thermosetting resins such as phenol resins, and the like. Various resin materials etc. are mentioned, Among these, it can use combining 1 type (s) or 2 or more types.
In addition, the sealing part 7 should just be provided as needed, and can also be abbreviate | omitted.

2. Operation Method of Display Device Such a display device 20 operates as follows.
For example, the display device 20 is configured to place the second electrode 4 in the ground state and apply a predetermined voltage to the first electrode 3 by a voltage application unit (power source) (not shown). When a voltage is applied to the first electrode 3, a potential difference is generated between the first electrode 3 and the second electrode 4, and an electric field corresponding to the potential difference is generated. When the electric field acts on the electrophoretic particles 5 in the microcapsule 40, the electrophoretic particles 5 (the colored particles 5b and the white particles 5a) are either the first electrode 3 or the second electrode 4 according to the direction of the electric field. It moves in the liquid phase dispersion medium 6 toward the electrode.

Hereinafter, when white particles 5a having a positive charge are used, negative particles are used as colored particles (black particles) 5b, and there is a net negative charge in the capsule body 401, one The microcapsule 40 will be described as an example.
-White display state (second state)-
When a voltage at which the first electrode 3 has a positive potential is applied to the first electrode 3, an electric field (white display electric field) generated by the voltage application acts on the electrophoretic particles 5. By the action of this electric field, the white particles 5 a move to the second electrode 4 side and gather on the second electrode 4, and the colored particles 5 b move to the first electrode 3 side along the inner wall of the capsule body 401. As a result, the first electrode 3 gathers. Then, when the voltage application is stopped, the white particles 5a are dispersed again in the liquid phase dispersion medium 6, and the state as shown in FIG.

  In such a state, when the microcapsule 40 is viewed from the display surface 201 side, white, which is the color of the white particles 5a, is displayed. In this state, since white is displayed by reflecting and scattering light by the white particles 5a, a brighter white can be obtained by dispersing the white particles 5a in the liquid phase dispersion medium 6. Can be displayed (that is, high contrast can be exhibited).

-Black display state (first state)-
Contrary to the white display state, when a voltage at which the first electrode 3 has a negative potential is applied to the first electrode 3, the electric field (black display electric field) generated by the voltage application acts on the electrophoretic particles 5. To do. By the action of this electric field, the white particles 5 a move to the first electrode 3 side and gather on the first electrode 3, and the colored particles 5 b move to the second electrode 4 side along the inner wall of the capsule body 401. As a result, the second electrode 4 gathers. Then, when the voltage application is stopped, the white particles 5a are dispersed again in the liquid phase dispersion medium 6 to be in a state as shown in FIG. In such a state, when the microcapsule 40 is viewed from the display surface 201 side, black, which is the color of the colored particles 5b, is displayed.
By performing such an operation on each microcapsule 40, that is, by appropriately combining the microcapsules 40 in the white display state and the microcapsules 40 in the black display state, a desired image is displayed on the display surface 201 of the display device 20. Is displayed.

Here, as shown in FIG. 3, in the display device 20, an electrostatic force (f _{1 in} FIG. 3) that acts on the colored particles 5 b due to the electric field generated between the first electrode 3 and the second electrode 4. Also, the force (attractive force) (f _{2 in} FIG. 3) for holding the colored particles 5b on the inner surface of the capsule body 401 is configured to be larger. The force (attracting force) (f ₂ ) for holding the colored particles 5b on the inner surface of the capsule body 401, when focusing on the predetermined particles 5b, is another colored particle 5b, white particle 5a, liquid phase dispersion medium 6 and capsule. The attractive force due to the interaction with the main body 401 and the like, that is, the electrostatic force (attractive force) due to the net charge (including the charge of the colored particles 5b) inside the capsule main body 401 (not including the capsule main body 401 itself), It is the sum (synthetic force) of van der Waals force (attraction force) between the particles 5b and the capsule body 401 and repulsive force due to osmotic pressure (by steric stabilization treatment using a graft polymer). The force (f ₂ ) for holding the colored particles 5b on the inner surface of the capsule body 401 is larger than the electrostatic force (f ₁ ) acting on the colored particles 5b due to the electric field. It can be realized by appropriately setting the amount (charge amount), the charge density, etc., that is, the net charge amount inside the capsule body 401, the magnitude of the voltage applied to the first electrode 3, and the like.

Thus, when a voltage is applied to the first electrode 3 and an electric field generated between them is applied to the colored particles 5b, the electrostatic force (f ₁ ) and the colored particles 5b are held on the inner surface of the capsule body 401. The direction of the sum (f _{3 in} FIG. 3) with the force (f ₂ ) to be applied is as shown in FIG. 3, and the colored particles 5b can be prevented from being separated from the capsule body 401. In this way, the colored particles 5 b can move along the inner surface of the capsule body 401 while reliably contacting the inner surface of the capsule body 401.

When the phenomenon in which the colored particles 5b move along the inner surface of the capsule body 401 while contacting the inner surface is slightly more complicated. This will be described below.
That is, the relationship (attraction, repulsive force, etc.) between the colored particles 5b and the capsule body 401 is a little more complicated, and the predetermined colored particles 5b, the other colored particles 5b, the white particles 5a, the liquid phase dispersion medium 6 and The interaction between the capsule body 401 and the like is described by a potential curve shown in FIG. In this case, the potential dent shown in FIG. 4 is obtained by the sum of the electrostatic force due to the net charge inside the capsule body 401, the van der Waals force between the colored particles 5b and the capsule body 401, and the repulsive force due to the osmotic pressure. Can do.

First, the distance between the inner surface and the capsule body 401 of the colored particles 5b in FIG. 4 when the Z _0, the colored particles 5b are spaced apart and the surface and the inner surface of the capsule body 401 by a distance Z ₀ Although held in position, this distance Z ₀ is a nanometer order distance and is actually in contact with each other's polymer chains.
Here, when an electric field is generated between the first electrode 3 and the second electrode 4, since the slope of the potential curve is zero at the position separated by the distance Z ₀ , the colored particles 5 b can be easily It moves in a direction away from the inner surface of the capsule body 401.

However, when approaching the colored particles 5b are spaced apart by a distance Z ₁ position, the slope of the potential curve is increased, and acts a large attractive force against the colored particles 5b, thereby, the colored particles 5b, the inner surface of the capsule body 401 It is no longer possible to move away from the capsule body 401, and on the contrary, the capsule body 401 moves toward the inner surface.
As a result, when an electric field is generated between the first electrode 3 and the second electrode 4, the colored particles 5b move on the inner surface of the capsule body 401 along the inner surface. At this time, as shown in FIG. 5, the colored particles 5 b change the distance between the surface of the colored particles 5 b and the inner surface of the capsule body 401 slightly (while the colored particles 5 b slightly jump). It moves along the inner surface of 401.

The white display state and the black display state have been described above. However, if the black capsule microcapsule 40 is suddenly switched to the white display state, the following problem occurs.
As shown in FIG. 6A, when an electric field generated by applying a voltage at which the first electrode 3 has a positive potential to the first electrode 3 acts on the microcapsules 40 in a black display state, The particles 5a move from the state dispersed in the liquid phase dispersion medium 6 to the second electrode 4 side, and the colored particles 5b move from the second electrode 4 side to the first electrode 3 side. Since the white particles 5a are dispersed in the liquid phase dispersion medium 6, the distance to the second electrode 4 as a whole is short and reaches the second electrode 4 side in a short time after the electric field action. Therefore, the white particles 5a reach the second electrode 4 side before or after the colored particles 5b start moving toward the second electrode 4 side.
Thereby, as shown in FIG. 6B, several colored particles 5b are surrounded by the plurality of white particles 5a. The colored particles 5b surrounded by the plurality of white particles 5a cannot move to the first electrode 3 side and remain on the second electrode 4 side as they are.

  As shown in FIG. 6C, since the white particles 5a are uniformly dispersed in the liquid phase dispersion medium 6 after the application of voltage is stopped, the surrounding of the colored particles 5b by the plurality of white particles 5a is as follows. Although the color particle 5b is released, the colored particle 5b left on the second electrode 4 side does not move to the first electrode side. Therefore, in such a state, when the microcapsule 40 is viewed from the display surface 201 side, gray (which is an intermediate color between the white particles 5a and the colored particles 5b (depending on the number of the colored particles 5b left on the second electrode 4 side). (Substantially black) will be displayed.

  Thus, if the colored particles 5b are left on the second electrode 4 side, an afterimage of the previous image is generated in the image displayed on the display surface 201, and the visibility of the image is deteriorated. The quality of For example, even when switching from the first checkered pattern image shown in FIG. 7A to the second checkered pattern image shown in FIG. 7B, an image as shown in FIG. 7C, the region (microcapsule 40) S1 that is in the black display state in the first image and in the white display state in the second image is displayed in gray, as shown in FIG. The afterimage resulting from the first image is displayed superimposed on the second image.

Therefore, in order to solve such a problem, the display device 20 is configured to prevent the occurrence of such an afterimage by causing the reset electric field E to act on at least the microcapsules 40 in the black display state. This will be specifically described below.
The reset electric field E is an electric field applied to each microcapsule 40 before an electric field for displaying the second image is applied. The reset electric field V is an electric field for temporarily setting the display surface 201 to the all white display state (the entire region is in the white display state). That is, when switching from the first image shown in FIG. 7 (A) to the second image shown in FIG. 7 (B), the entire white area is between the first image and the second image. A white image will be displayed. The reset electric field E can be generated by applying a predetermined voltage to the first electrode 3.

  As shown in FIG. 8, the reset electric field E is started at the same time as the first period E1, the third period E3 that starts at the end of the first period E1, and the end of the third period E3. And a second period E2. In FIG. 8, the waveform of the voltage applied to the first electrode 3 is shown. The period in which the voltage (−) is applied is the first period E1, and the period in which no voltage is applied is the first. 3 period E3, the period during which the voltage of (+) is applied is the second period E2. Hereinafter, these three periods E1 to E3 will be sequentially described in detail.

  In the first period E1, an electric field in which the first electrode 3 side is negative acts on the microcapsule 40. Therefore, in the first period E1, the white particles 5a dispersed in the liquid phase dispersion medium 6 move to the first electrode 3 side, and the colored particles 5b move to the second electrode 4 side. Here, since the colored particles 5b are originally gathered on the second electrode 4 side, the movement thereof is slight. By having such 1st period E1, the white particle 5a can be kept away from the 2nd electrode 4 (colored particle 5b).

  The time of the first period E1 is not particularly limited, but is preferably 0.2 seconds (200 msec) or longer. Thereby, the white particles 5a can be sufficiently moved to the first electrode 3 side. That is, the white particles 5a can be sufficiently separated from the colored particles 5b. The upper limit value of the first period E1 is not particularly limited, but is preferably within 2 seconds, for example, from the viewpoint of shortening the first period E1 as much as possible.

  The strength (absolute value) of the electric field generated in the first period E1 is not particularly limited, but is preferably 0.1 V / μm or more. Thereby, the white particle 5a can be reliably moved to the 1st electrode 3 side. The upper limit value of the intensity of the electric field generated in the first period E1 is not particularly limited, but is preferably 100 V / μm or less from the viewpoint of device safety problems and power saving driving.

  Moreover, it is preferable that the strength of the electric field generated in the first period E1 is equal to the strength of the electric field applied when the microcapsule 40 is in the black display state. In other words, the voltage applied to the first electrode 3 in the first period E1 is preferably the same as the voltage applied to the first electrode 3 when the microcapsule 40 is in the black display state. . This simplifies the device configuration (circuit configuration).

In the third period E3, no electric field is generated. That is, no voltage is applied to the first electrode 3. Since the reset electric field E has the third period E3, the movement of the electrophoretic particles 5 can be temporarily stopped. Therefore, the electrophoretic particles 5 are smoothly moved in the second period E2 described later. be able to.
The time of the third period E3 is not particularly limited, but is preferably 2 seconds or less. Thereby, it is possible to prevent the white particles 5 a attracted to the first electrode 3 side during the first period E <b> 1 from being dispersed again in the liquid phase dispersion medium 6.

In the second period E2, an electric field with the first electrode side being positive acts on the microcapsule 40. Therefore, in the second period E2, the white particles 5a move to the second electrode 4 side, and the colored particles 5b move to the first electrode 3 side. Here, in the first period E1, the white particles 5a are moved to the first electrode 3 side and are sufficiently moved away from the colored particles 5b. Therefore, before the colored particles 5b start to move or immediately after the movement starts. Further, the white particles 5a can be prevented from reaching the second electrode 4 side. Therefore, some colored particles 5b are taken in by the plurality of white particles 5a on the second electrode 4 side, and the colored particles 5b can be prevented from staying on the second electrode 4 side. All can be reliably moved to the first electrode 3 side.
When such a second period E2 ends, only the white particles 5a are dispersed in the liquid phase dispersion medium 6, and the microcapsules 40 are in a white display state as shown in FIG.

  The time of the second period E2 is not particularly limited, but is preferably 0.2 seconds (200 msec) or longer. Thereby, while being able to move the white particle 5a to the 2nd electrode 4 side more reliably, the colored particle 5b can be moved to the 1st electrode 3 side. The upper limit value of the second period E2 is not particularly limited, but is preferably within 2 seconds, for example, from the viewpoint of shortening the second period E2 as much as possible.

  The strength (absolute value) of the electric field generated in the second period E2 is not particularly limited, but is preferably 1 V / μm or more. Thereby, the white particles 5a and the colored particles 5b can be moved more reliably and smoothly. The upper limit value of the intensity of the electric field generated in the second period E2 is not particularly limited, but is preferably 100 V / μm or less from the viewpoint of safety of the apparatus and power saving driving.

  In addition, the strength of the electric field generated in the second period E2 is preferably equal to the strength of the electric field that is applied when the microcapsule 40 is in the white display state. In other words, the voltage applied to the first electrode 3 in the second period E2 is preferably the same as the voltage applied to the first electrode 3 when the microcapsule 40 is in the black display state. . This simplifies the device configuration (circuit configuration).

  By applying the resetting electric field E as described above to the microcapsule 40 before applying the electric field for displaying the second image, the display surface 201 is completely whitened before the second image is displayed. The display state can be obtained, and the first image can be completely erased. For this reason, when the second image is written, it is possible to reliably prevent the afterimage resulting from the first image from being derived.

  Here, the reset electric field E may be applied only to the microcapsules 40 in the black display state, or may be applied to all the microcapsules 40, but the microcapsules in the black display state. It is preferable to act only on 40. As a result, it is possible to prevent an unnecessary electric field from acting on the microcapsules 40 that are in the white display state from the beginning, so that the reliability of the apparatus is improved and power saving can be achieved. In the case where the reset electric field is applied only to the microcapsules 40 that are in the black display state, for example, a storage unit that stores the position of the microcapsules 40 that are in the black display state in the immediately preceding image is provided. Based on the information stored in the unit, a reset electric field may be applied to the microcapsules 40 in the black display state.

As described above, according to the display device 20, the colored particles 5 b are always in contact with any part of the inner surface of the capsule body 401 and are in contact with the inner surface of the capsule body 401. Furthermore, since the colored particles 5b and the white particles 5a are not adsorbed, a halftone can be obtained easily and reliably.
In addition, even when no electric field is generated between the first electrode 3 and the second electrode 4, the colored particles 5b are in contact with and held on the inner surface of the capsule body 401. It can be reliably maintained. Thereby, even if the application of voltage is stopped, the display content (image) is stably held without deterioration of the display state.
In addition, since the microcapsule 40 has a spherical shape, the colored particles 5b can be reliably and smoothly moved to either the first electrode 3 or the second electrode 4 along the inner wall of the capsule body 401. Can do.

Second Embodiment
Next, a second embodiment of the display device of the present invention will be described.
FIG. 9 is a longitudinal sectional view schematically showing a second embodiment of the display device of the present invention.
Hereinafter, the display device according to the second embodiment will be described, but the description will be focused on differences from the first embodiment, and description of similar matters will be omitted.

The display device according to the present embodiment is the same as that of the first embodiment except that the white particles 5a ′ are uncharged.
As shown in FIG. 9, each microcapsule 40 encloses an electrophoretic dispersion liquid 10 in which colored particles 5 b and uncharged white particles 5 a ′ are dispersed in a liquid phase dispersion medium 6. Even in such a microcapsule 40, when the black display state is suddenly switched to the white display state, the colored particles 5b are surrounded by the plurality of white particles 5a ′ in the vicinity of the second electrode 4 as in the first embodiment described above. This causes a problem that it is displayed as an afterimage. However, the mechanism is different from that of the first embodiment, and will be briefly described below.

When an electric field in which the first electrode 3 has a positive potential is applied to the microcapsules 40 in the black display state, the colored particles 5b move to the first electrode 3 side by an electric attractive force. On the other hand, since the white particles 5a 'are uncharged, they do not move in any direction of the first and second electrodes 3 and 4 due to an electric force, but the colored particles 5b and the added ions move. It moves to the second electrode 4 side by the convection generated by doing so. Thereby, several colored particles 5b are surrounded by the plurality of white particles 5a ′. In this way, the same problem as in the first embodiment occurs.
Therefore, the display device 20 of the second embodiment is also configured to cause the reset electric field E to act on the microcapsules 40 in the black display state to prevent the occurrence of the afterimage as described above. This will be specifically described below.

  In the first period E1, an electric field in which the first electrode 3 side is negative acts on the microcapsule 40. Therefore, in the first period E1, the colored particles 5b move to the second electrode 4 side. Since the colored particles 5b are originally gathered on the second electrode 4 side, the movement is slight, but the convection (flow of the liquid phase dispersion medium 6) generated by this movement and the movement of the added ions occur. The white particles 5a ′ move to the second electrode 4 side by the convection. By having such a first period E1, the white particles 5a 'can be kept away from the second electrode 4 (colored particles 5b).

In the second period E2, an electric field with the first electrode side being positive acts on the microcapsule 40. Therefore, in the second period E2, the colored particles 5b move to the first electrode 3 side. Here, in the first period E1, the white particles 5a ′ are moved to the first electrode 3 side and are sufficiently away from the colored particles 5b, so that the white particles 5a ′ are generated by convection caused by the movement of the colored particles 5b. Reaching the second electrode 4 in a short time can be prevented. Therefore, some colored particles 5b are taken in by the plurality of white particles 5a ′ on the second electrode 4 side, and the colored particles 5b can be prevented from staying on the second electrode 4 side.
When the second period E2 ends, only the white particles 5a ′ are dispersed in the liquid phase dispersion medium 6, and the microcapsule 40 is in a white display state as shown in FIG.
Also by such 2nd Embodiment, the effect similar to embodiment mentioned above can be exhibited.

<Electronic equipment>
The display device 20 as described above can be incorporated into various electronic devices. Hereinafter, the electronic apparatus of the present invention including the display device 20 will be described.
<< Electronic Paper >>
First, an embodiment when the electronic apparatus of the present invention is applied to electronic paper will be described.
FIG. 10 is a perspective view showing an embodiment when the electronic apparatus of the present invention is applied to electronic paper.
An electronic paper 600 shown in FIG. 10 includes a main body 601 composed of a rewritable sheet having the same texture and flexibility as paper, and a display unit 602.
In such electronic paper 600, the display unit 602 includes the display device 20 as described above.

<< Display >>
Next, an embodiment when the electronic apparatus of the present invention is applied to a display will be described.
FIG. 11 is a diagram showing an embodiment when the electronic apparatus of the present invention is applied to a display. 11A is a cross-sectional view, and FIG. 11B is a plan view.
A display (display device) 800 shown in FIG. 11 includes a main body 801 and an electronic paper 600 that is detachably attached to the main body 801. The electronic paper 600 has the same configuration as described above, that is, the configuration shown in FIG.

  The main body 801 has an insertion port 805 into which the electronic paper 600 can be inserted on its side (right side in FIG. 11A), and two pairs of conveying rollers 802a and 802b are provided inside. Yes. When the electronic paper 600 is inserted into the main body 801 through the insertion port 805, the electronic paper 600 is installed in the main body 801 in a state of being sandwiched between the pair of conveyance rollers 802a and 802b.

  A rectangular hole 803 is formed on the display surface side of the main body 801 (the front side in FIG. 11B), and a transparent glass plate 804 is fitted in the hole 803. . Thereby, the electronic paper 600 installed in the main body 801 can be viewed from the outside of the main body 801. That is, in the display 800, the display surface is configured by visually recognizing the electronic paper 600 installed in the main body 801 on the transparent glass plate 804.

In addition, a terminal portion 806 is provided at the distal end portion (left side in FIG. 11) of the electronic paper 600 in the insertion direction. A socket 807 to which the unit 806 is connected is provided. A controller 808 and an operation unit 809 are electrically connected to the socket 807.
In such a display 800, the electronic paper 600 is detachably installed on the main body 801, and can be carried and used while being detached from the main body 801.

In such a display 800, the electronic paper 600 is configured by the display device 20 as described above.
Note that the electronic apparatus of the present invention is not limited to the application to the above, and for example, a television, a viewfinder type, a monitor direct view type video tape recorder, a car navigation device, a pager, an electronic notebook, a calculator, an electronic Examples include newspapers, word processors, personal computers, workstations, videophones, POS terminals, and devices equipped with touch panels. The display device 20 of the present invention can be applied to the display units of these various electronic devices. It is.

As mentioned above, although this invention was demonstrated based on embodiment of illustration, this invention is not limited to this, The structure of each part can be substituted by the thing of the arbitrary structures which have the same function. Moreover, other arbitrary structures and processes may be added to the present invention.
Further, the present invention may be a combination of any two or more configurations (features) of the above embodiments.

  The above embodiment is a so-called microcapsule type display device. However, the present invention is not limited to this, and for example, a contact particle-containing layer containing contact particles and scatterers or colored bodies is partitioned by a partition wall. In other words, a plurality of cell spaces (spaces) partitioned by partition walls are formed, each cell space is filled with an electrophoretic dispersion, and colored particles are in contact with the inner surface of the cell. It may be.

  Moreover, although the said embodiment demonstrated the form which has an adhesive bond layer, an adhesive bond layer may be abbreviate | omitted and a display sheet and a circuit board may be joined by another method. For example, when the strength of the microcapsules is sufficient and it is not necessary to protect the microcapsules with the adhesive layer, and the binder also has adhesiveness, it is practical even without the adhesive layer. In this case, there is an advantage that the electric field from the electrode is effectively applied to the microcapsule.

Next, specific examples of the present invention will be described.
1. Manufacture of display device (A1) Production of microcapsules (A1-1) Preparation of electrophoretic dispersion liquid A 300 ml separable flask equipped with a stirring blade, a thermometer, and a cooling tube was charged with dodecyl methacrylate and 2-ethylhexyl acrylate. 2 g of an acrylic polymer (mass average molecular weight 3,300) composed of glycidyl methacrylate (composition ratio 80: 15: 5), 20 g of carbon black (MA-100R, manufactured by Mitsubishi Chemical Corporation), Isopar M (Exxon Chemical Co., Ltd.) 78 g), and 800 g of zirconia beads having a diameter of 1 mm. While stirring at a rotational speed of 300 rpm, the polymer grafting was performed by reacting at 160 ° C. for 2 hours. After the treatment, 100 g of Isopar M (Exxon Chemical Co., Ltd.) was further added and mixed thoroughly. Thereafter, beads made of zirconia were separated to obtain a dispersion liquid of carbon black subjected to polymer grafting (here, an epoxy group of an acrylic polymer was reacted with a carboxy group present on the surface of the carbon black). On the other hand, in a separable flask having a capacity of 300 ml equipped with a stirring blade, 50 g of titanium oxide (Taipec CR90, manufactured by Ishihara Sangyo Co., Ltd.), dodecyl methacrylate, 2-ethylhexyl acrylate, methacryloxypropyltrimethoxysilane (composition ratio 80) : 15: 5) Acrylic polymer (mass average molecular weight 6,800) 5 g and hexane 100 g were charged, placed in a 55 ° C. ultrasonic bath (BRANSON 5210, manufactured by Yamato Scientific Co., Ltd.), and ultrasonically dispersed while stirring. The treatment was performed for 2 hours. This separable flask was transferred to a 90 ° C hot water bath, the solvent was distilled off, and the powdered titanium oxide was taken out of the flask and transferred to a vat, followed by heat treatment at 150 ° C for 5 hours in a dryer. It was. The heat-treated titanium oxide was dispersed in 100 g of hexane, centrifuged with a centrifugal settling machine, and washed with titanium oxide three times, and then dried at 100 ° C. A 300 ml separable flask equipped with a stirring blade was charged with 50 g of washed titanium oxide and 50 g of Isopar M (manufactured by Exxon Chemical Co., Ltd.), and placed in an ultrasonic bath (BRANSON 5210, Yamato Scientific Co., Ltd.) at 55 ° C. The mixture was stirred and subjected to ultrasonic dispersion for 2 hours to disperse the polymer-grafted titanium oxide (here, the hydroxy group present on the surface of the titanium oxide was reacted with the silyl group of the acrylic polymer). A liquid was obtained. In a 200 ml mayonnaise bin, 6.0 g of the above polymer grafted carbon black dispersion, 75 g of the above polymer grafted titanium oxide dispersion, and 19 g of Isopar M (Exxon Chemical Co., Ltd.) were charged. To obtain a dispersion for an electrophoretic display device.

(A1-2) Preparation of aqueous suspension of electrophoretic dispersion 60 g of 10 wt% gum arabic aqueous solution was weighed into a 500 ml beaker, and 50 g of the electrophoretic dispersion obtained in the step (A1-1) was stirred with a disper. Addition and suspension operation were performed to obtain an aqueous suspension of the electrophoretic dispersion.
(A1-3) Formation of first capsule layer A 100 ml round bottom separable flask was charged with 5 g of melamine, 5 g of urea, 20 g of a 27 wt% aqueous formaldehyde solution and 1 g of 25 wt% aqueous ammonia, and the temperature was raised to 70 ° C. while stirring. It was. The whole became transparent at around 65 ° C. during the temperature increase. After raising the temperature to 70 ° C. and holding at that temperature for 1 hour, the mixture was cooled to 30 ° C. to obtain an initial condensation compound of melamine, urea and formaldehyde.

  Next, this initial condensate was added to the aqueous suspension of the electrophoretic dispersion obtained in the step (A1-2) held at 40 ° C., and the mixture was stirred for 2 hours at the same temperature. The temperature was raised and the mixture was aged for 2 hours at the same temperature, and then cooled to room temperature. Through the above steps, a first capsule layer made of melamine resin was formed, and a microcapsule precursor dispersion containing an electrophoretic dispersion was obtained. After adding 1 L of deionized water to the whole microcapsule dispersion and mixing it uniformly, the sedimentation of the microcapsule precursor, which was allowed to stand, was confirmed, and the operation of removing the supernatant was performed several times for washing. As a result of measuring the particle size of the microcapsule precursor, the volume average particle size was 42 μm.

(A1-4) Formation of second capsule layer Deionized water was added to the total amount of the microcapsule precursor obtained in the previous step (A1-3) to a 300 ml separable flask to make the total amount 200 g. The microcapsule precursor dispersion was heated to 40 ° C. with stirring, and 20 g of an epoxy compound [manufactured by Nagase ChemteX Corporation, “Denacol EX521 (polyglycerol polyglycidyl ester)”] was dispersed in 50 g of water. The solution was added dropwise over 10 minutes. After maintaining at the same temperature for 30 minutes, 1 g of 2.5 wt% sodium diethyldithiocarbamate aqueous solution was added as a cross-linking agent and reacted for 2 hours. Next, the temperature was raised to 50 ° C., and aging was performed for 2 hours at the same temperature, whereby a second capsule layer made of an epoxy resin was formed on the surface of the microcapsule precursor (first capsule layer).

  Through the above steps, a microcapsule that encapsulates the electrophoretic dispersion in a capsule body composed of the first capsule layer and the second capsule layer was obtained. This microcapsule dispersion was subjected to wet classification using a mesh having an opening of 38 μm and a mesh having an opening of 32 μm to obtain a microcapsule having a volume average particle size of 37.29 μm (CV value 8.18%). The particle size distribution was measured using a laser diffraction / scattering particle size distribution measuring device (product name: LA-910, manufactured by Horiba, Ltd.). The CV value represents (standard deviation / average particle diameter) × 100.

(A2) Preparation of microcapsule dispersion Next, the microcapsules obtained in the step (A1) and the binder were mixed at a weight ratio of 10: 3 to prepare a microcapsule dispersion. As the binder, a mixture in which butyl acrylate, 2-ethylhexyl acrylate, and polyethylene glycol (Mw = 2000) were mixed at a weight ratio of 50: 47: 3 was used.

Next, the microcapsule dispersion is applied on the second electrode of the substrate on which the second electrode made of ITO is formed, and then dried at 90 ° C. for 10 minutes to form a display layer. A display sheet (1) was obtained.
Subsequently, using the display sheet (1), a display device was manufactured as follows.
There is a portion where the display layer is not formed on one side (conductive portion), and the portion where the display layer is formed is a moving display sheet (1) having a length of 5 cm × 3 cm and a first electrode made of ITO. A circuit board having a length of 6 cm and a width of 4 cm and a thickness of 75 μm is bonded to each other via an adhesive layer (two arbitrary places are fixed with cello tape (cello tape is a registered trademark)) and placed on a glass plate having a thickness of 2 mm. The two rolls of the roll laminator were passed through and joined.

Each roll of the roll laminator was a silicon rubber roll, the roll diameter was 3 inches, and the clearance between the two rolls was 0 mm. The upper roll is heated by a heat medium, the roll surface temperature is 120 ° C., the upper roll is driven to rotate, and the roll position is fixed. Further, the lower roll is not heated, and is free-rotated and pressure-bonded to the upper roll with an air pressure of 0.2 mPas.
In addition, it arrange | positioned so that the display layer side may be located in the upper roll side heated with the heat medium, and the feed rate was 6 cm / min.
Thus, the display device 20 shown in FIG. 1 was obtained.

2. Driving of display device (Example 1)
First, an electric field for black display (0.1 second, 0.33 V / μm) was applied to each microcapsule of the display device, so that the entire display surface was in a black display state. Next, after a lapse of 1 second from the black display state, the black display state was reset, and a reset electric field E was applied to each microcapsule so as to obtain a white display state. Next, an electric field for white display (0.1 second, 0.33 V / μm) was applied to each microcapsule. The strength and time of the reset electric field are as follows.
First period E1: 0.1 second, 0.33 V / μm (absolute value)
Third period E3: 0 second Second period E2: 0.1 second, 0.33 V / μm (absolute value)

(Example 2)
First, an electric field for black display (0.2 seconds, 0.33 V / μm) was applied to each microcapsule of the display device so that the entire display surface was in a black display state. Next, after a lapse of 1 second from the black display state, the black display state was reset, and a reset electric field E was applied to each microcapsule so as to obtain a white display state. Next, an electric field for white display (0.2 seconds, 0.33 V / μm) was applied to each microcapsule. The strength and time of the reset electric field are as follows.
First period E1: 0.2 seconds, 0.33 V / μm (absolute value)
Third period E3: 0 seconds Second period E2: 0.2 seconds, 0.33 V / μm (absolute value)

(Example 3)
First, an electric field for black display (0.4 seconds, 0.33 V / μm) was applied to each microcapsule of the display device so that the entire display surface was in a black display state. Next, after a lapse of 1 second from the black display state, the black display state was reset, and a reset electric field E was applied to each microcapsule so as to obtain a white display state. Next, an electric field for white display (0.4 seconds, 0.33 V / μm) was applied to each microcapsule. The strength and time of the reset electric field are as follows.
First period E1: 0.4 seconds, 0.33 V / μm (absolute value)
Third period E3: 0 seconds Second period E2: 0.4 seconds, 0.33 V / μm (absolute value)

Example 4
First, an electric field for black display (0.2 seconds, 0.33 V / μm) was applied to each microcapsule of the display device so that the entire display surface was in a black display state. Next, after a lapse of 1 second from the black display state, the black display state was reset, and a reset electric field E was applied to each microcapsule so as to obtain a white display state. Next, an electric field for white display (0.2 seconds, 0.33 V / μm) was applied to each microcapsule. The strength and time of the reset electric field are as follows.
First period E1: 0.2 seconds, 0.33 V / μm (absolute value)
Third period E3: 1 second Second period E2: 0.2 second, 0.33 V / μm (absolute value)

(Example 5)
First, an electric field for black display (0.2 seconds, 0.33 V / μm) was applied to each microcapsule of the display device so that the entire display surface was in a black display state. Next, after a lapse of 1 second from the black display state, the black display state was reset, and a reset electric field E was applied to each microcapsule so as to obtain a white display state. Next, an electric field for white display (0.2 seconds, 0.33 V / μm) was applied to each microcapsule. The strength and time of the reset electric field are as follows.
First period E1: 0.2 seconds, 0.33 V / μm (absolute value)
Third period E3: 2 seconds Second period E2: 0.2 seconds, 0.33 V / μm (absolute value)

(Example 6)
First, an electric field for black display (0.2 seconds, 0.33 V / μm) was applied to each microcapsule of the display device so that the entire display surface was in a black display state. Next, after a lapse of 1 second from the black display state, the black display state was reset, and a reset electric field E was applied to each microcapsule so as to obtain a white display state. Next, an electric field for white display (0.2 seconds, 0.33 V / μm) was applied to each microcapsule. The strength and time of the reset electric field are as follows.
First period E1: 0.2 seconds, 0.33 V / μm (absolute value)
Third period E3: 3 seconds Second period E2: 0.2 seconds, 0.33 V / μm (absolute value)

(Example 7)
First, an electric field for black display (0.2 seconds, 0.33 V / μm) was applied to each microcapsule of the display device so that the entire display surface was in a black display state. This voltage application was repeated a total of 6 times. Next, a reset electric field E was applied to each microcapsule to reset the black display state to a white display state after 1 second from the black display state. Next, an electric field for white display (0.2 seconds, 0.33 V / μm) was applied to each microcapsule. The strength and time of the reset electric field are as follows.
First period E1: 0.2 seconds, 0.33 V / μm (absolute value)
Third period E3: 1 second Second period E2: 0.2 second, 0.33 V / μm (absolute value)

(Example 8)
First, an electric field for black display (0.2 seconds, 0.33 V / μm) was applied to each microcapsule of the display device so that the entire display surface was in a black display state. Next, after 1 minute from the black display state, the black display state was reset, and a reset electric field E was applied to each microcapsule so as to obtain a white display state. Next, an electric field for white display (0.2 seconds, 0.33 V / μm) was applied to each microcapsule. The strength and time of the reset electric field are as follows.
First period E1: 0.2 seconds, 0.33 V / μm (absolute value)
Third period E3: 1 minute Second period E2: 0.2 seconds, 0.33 V / μm (absolute value)

(Comparative Example 1)
First, an electric field for black display (0.2 seconds, 0.33 V / μm) was applied to each microcapsule of the display device so that the entire display surface was in a black display state. Next, an electric field for white display (0.2 seconds, 0.33 V / μm) was applied to each microcapsule in order to switch the black display state to the white display state after 1 second from the black display state.

(Comparative Example 2)
First, an electric field for black display (0.2 seconds, 0.33 V / μm) was applied to each microcapsule of the display device so that the entire display surface was in a black display state. This voltage application was repeated a total of 6 times. Next, an electric field for white display (0.2 seconds, 0.33 V / μm) was applied to each microcapsule in order to switch the black display state to the white display state after 1 second from the black display state.

(Comparative Example 3)
First, an electric field for black display (0.2 seconds, 0.33 V / μm) was applied to each microcapsule of the display device so that the entire display surface was in a black display state. Next, an electric field for white display (0.2 seconds, 0.33 V / μm) was applied to each microcapsule in order to switch the black display state to the white display state after 1 minute from the black display state.

3. Evaluation of Display Device For display switching drive of the display device in each example and each comparative example, the reflectance of the display color was measured 3 seconds after the application of the white display electric field was completed. The reflectance of the display color of each display device indicates the ratio of the reflection amount of the display color of the display device when the reference white (standard sample) reflection amount is 100. In addition, the reflectance was measured using a color luminance meter ("BM-5A" manufactured by Topcon Corporation). Table 1 shows the reflectivity in each example and each comparative example obtained as described above.

As is clear from Table 1, each example has a high reflectivity of 40% or more, whereas each comparative example has a reflectivity of only about 30%. I found that it was not. That is, it was found that afterimages due to the black display state were prevented in each example.
In addition, the electric field strength (absolute value) in the first period E1 and the second period E2 was changed between 1 V / μm and 10 V / μm, and the same experiment as each example and each comparative example was performed. As a result, similar results were obtained. Similar results were obtained when white particles were used as uncharged particles.

DESCRIPTION OF SYMBOLS 1 ... Base 2 ... Base 3 ... 1st electrode 4 ... 2nd electrode 5 ... Electrophoretic particle (display particle) 5a, 5a '... White particle 5b ... Colored particle (black particle) 6 Liquid phase dispersion medium 7 Sealing part 8 Adhesive layer 10 Electrophoresis dispersion liquid 11 Counter substrate 12 Substrate 20 Display device 201 Display surface 21 Display sheet 22 Circuit board 40 Microcapsule 41 Binder 400 Display layer 401 Capsule body 402 First capsule layer 403 Second capsule layer 600 Electronic paper 601 Main body 602 Display unit 800 Display 801 Main body 802a, 802b Transport roller pair 803 Hole 804 Transparent glass plate 805 Insertion port 806 Terminal 807 Socket 80 ‥‥ controller 809 ‥‥ operating unit E ‥‥ reset field E1 ‥‥ first period E2 ‥‥ second period E3 ‥‥ third period Z _{0, Z 1} ‥‥ distance

Claims (16)

A plurality of first particles that are positively or negatively charged and a plurality of second particles that are charged at the opposite pole of the first particles and have a light reflectance lower than that of the first particles Having a display layer comprising a plurality of accommodating portions,
It said plurality of housing portions by the action of an electric field, said first particles in the accommodating portion together with the second particles the plurality of accommodating portions to one surface side of each of said display layer is unevenly distributed Is dispersed in the first display state, or the second particles are unevenly distributed on the other surface side of the display layer and the first particles are dispersed in the housing portion. Can be switched to
A display sheet that displays a desired image on the display surface provided on the one surface side of the display layer by selecting the first display state or the second display state in the plurality of storage units, respectively. Because
The plurality of second particles move along the inner surface while being in contact with the inner surface of the housing portion by the action of the electric field,
When switching the first image displayed on the display surface to a second image different from the first image, an electric field for displaying the second image is applied to the plurality of accommodating portions. Prior to the configuration, a reset electric field for causing a second display state to act on at least the housing portion in the first display state among the plurality of housing portions,
The reset electric field includes a first period in which the second particles are moved to the one surface side and the first particles are moved to the other surface side, and after the first period. And a second period in which the first particles are moved to the one surface side and the second particles are moved to the other surface side. A display layer including a plurality of storage portions that store a plurality of first non-charged particles and a plurality of second particles that are positively or negatively charged and have a light reflectance lower than that of the first particles. Have
It said plurality of housing portions by the action of an electric field, said first particles in the accommodating portion together with the second particles the plurality of accommodating portions to one surface side of each of said display layer is unevenly distributed Is dispersed in the first display state, or the second particles are unevenly distributed on the other surface side of the display layer and the first particles are dispersed in the housing portion. Can be switched to
A display sheet that displays a desired image on the display surface provided on the one surface side of the display layer by selecting the first display state or the second display state in the plurality of storage units, respectively. Because
The plurality of second particles move along the inner surface while being in contact with the inner surface of the housing portion by the action of the electric field,
When switching the first image displayed on the display surface to a second image different from the first image, an electric field for displaying the second image is applied to the plurality of accommodating portions. Prior to the configuration, a reset electric field for causing a second display state to act on at least the housing portion in the first display state among the plurality of housing portions,
The reset electric field includes a first period in which the second particles are moved to the one surface side and the first particles are moved to the other surface side, and after the first period. And a second period in which the first particles are moved to the one surface side and the second particles are moved to the other surface side.   The display sheet according to claim 1, wherein the reset electric field is applied only to the housing portion in the first display state.   The display sheet according to claim 1, wherein the reset electric field has a third period in which no electric field is generated between the first period and the second period.   The display sheet according to claim 4, wherein the third period is within 2 seconds.   The display sheet according to claim 1, wherein the first period is 0.2 seconds or more.   The display sheet according to claim 1, wherein the second period is 0.2 seconds or more.   The display sheet according to claim 1, wherein the strength of the electric field in the first period is equal to the strength of the electric field applied to the housing portion when the housing portion is in the first display state.   The display sheet according to claim 1, wherein the strength of the electric field in the second period is equal to the strength of the electric field applied to the housing portion when the housing portion is in the second display state. The display sheet according to claim 1, wherein the second particles are in contact with the inner surface of the housing portion by electrostatic force. Than the electrostatic force acting on the second particle by the electric field that acts on the receiving portion, wherein the second particles in any one of the claims 1 larger force 10 holding the inner surface of the housing part Display sheet. The receiving portion is defining a spherical space, according to any one of claims 1 to 11 wherein the plurality of first particles and the plurality of second particles are accommodated in the space Display sheet. Display device characterized by comprising a display sheet according to any one of claims 1 to 12. An electronic apparatus comprising the display device according to claim 13 . A plurality of first particles that are positively or negatively charged and a plurality of second particles that are charged at the opposite pole of the first particles and have a light reflectance lower than that of the first particles Having a display layer comprising a plurality of accommodating portions,
It said plurality of housing portions by the action of an electric field, said first particles in the accommodating portion together with the second particles the plurality of accommodating portions to one surface side of each of said display layer is unevenly distributed Is dispersed in the first display state, or the second particles are unevenly distributed on the other surface side of the display layer and the first particles are dispersed in the housing portion. Can be switched to
A display sheet that displays a desired image on the display surface provided on the one surface side of the display layer by selecting the first display state or the second display state in the plurality of storage units, respectively. Driving method,
The plurality of second particles move along the inner surface while being in contact with the inner surface of the housing portion by the action of the electric field,
When switching the first image displayed on the display surface to a second image different from the first image, an electric field for displaying the second image is applied to the plurality of accommodating portions. Prior to driving, an electric field for resetting for causing the second display state to act on at least the housing portion in the first display state among the plurality of housing portions,
The reset electric field includes a first period in which the second particles are moved to the one surface side and the first particles are moved to the other surface side, and after the first period. And a second period for moving the first particles to the one surface side and moving the second particles to the other surface side. A display layer including a plurality of storage portions that store a plurality of first non-charged particles and a plurality of second particles that are positively or negatively charged and have a light reflectance lower than that of the first particles. Have
It said plurality of housing portions by the action of an electric field, said first particles in the accommodating portion together with the second particles the plurality of accommodating portions to one surface side of each of said display layer is unevenly distributed Is dispersed in the first display state, or the second particles are unevenly distributed on the other surface side of the display layer and the first particles are dispersed in the housing portion. Can be switched to
A display sheet that displays a desired image on the display surface provided on the one surface side of the display layer by selecting the first display state or the second display state in the plurality of storage units, respectively. Driving method,
The plurality of second particles move along the inner surface while being in contact with the inner surface of the housing portion by the action of the electric field,
When switching the first image displayed on the display surface to a second image different from the first image, an electric field for displaying the second image is applied to the plurality of accommodating portions. Prior to driving, an electric field for resetting for causing the second display state to act on at least the housing portion in the first display state among the plurality of housing portions,
The reset electric field includes a first period in which the second particles are moved to the one surface side and the first particles are moved to the other surface side, and after the first period. And a second period for moving the first particles to the one surface side and moving the second particles to the other surface side.

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