JP2008158067A - Display medium, display device, and display method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display medium capable of displaying sharp colors by suppressing decrease in saturation. <P>SOLUTION: The display medium comprises at least a transparent substrate 200, having one surface as a display surface 202, a back transparent substrate 204 disposed opposite the surface of the transparent substrate 200 on the opposite side from the display surface 202; a dispersion medium 302 charged in the gap between the transparent substrate 200 and back substrate 204; one or more kinds of coloring charge transfer particles 300 which are contained in the dispersion medium 302 and develop color, while dispersed in the dispersion medium 302; and a member 400 for gap formation disposed while fixed to the surface of the transparent substrate 200 on the opposite side from the display surface 202 and forming a gap which extends from the surface of the transparent substrate 200 on a side opposite from the display surface 202 to the side of the back substrate 204 and where all the kinds of coloring charge transfer particles 300 move. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a display medium, a display device, and a display method.

  As repetitive rewritable display media, use is made of display media that rotate and display particles colored in two colors, display media that use particle electrophoresis or magnetophoresis, and liquid crystals that have memory properties Such display media are known.

  The display medium using particle electrophoresis includes, for example, a fluid containing a plurality of particles, and at least one electrode arranged to apply an electric field to the fluid and thereby move the particles through the fluid. Is known (see Patent Document 1). The basic configuration of the display medium includes at least one of a pair of substrates made of a transparent substrate and a liquid containing particles sealed in a gap between the pair of substrates, and the substrates of the pair of substrates are Electrodes are provided on the surfaces facing each other.

As the particles used for the display medium, for example, nanoparticles having a diameter smaller than the wavelength of visible light are used. For example, the nanoparticles have an average diameter of 200 nm or less, and metal particles containing gold or silver can be used.
In addition, the display by the display medium basically controls the state in which the nanoparticles are dispersed in the fluid and the state in which the nanoparticles are aggregated by the electric field applied to the fluid, and the difference in the display state in each state It is done using.
Special table 2004-522180 gazette

  It is an object of the present invention to provide a display medium, a display device, and a display method that can display a clear color while suppressing a decrease in saturation.

The above object is achieved by the present invention described below. That is,
The invention according to claim 1
A transparent substrate in which one surface constitutes a display surface;
A rear substrate disposed opposite to the surface opposite to the display surface of the transparent substrate;
A dispersion medium enclosed in a gap between the transparent substrate and the back substrate;
One or more color-forming charge-transfer particles that are contained in the dispersion medium and develop color in a state dispersed in the dispersion medium;
Arranged in a state of being fixed to the surface of the transparent substrate opposite to the display surface, leading from the surface of the transparent substrate opposite to the display surface to the rear substrate side, and all kinds of color-generating charge transfer And a void-forming member that forms a void in which the active particles move.

The invention according to claim 2
A back electrode is provided on a surface of the back substrate on the transparent substrate side, a transparent electrode is provided on a surface opposite to the display surface of the transparent substrate, and the gap forming member is fixed on the surface of the transparent electrode. The display medium according to claim 1, wherein the display medium is arranged in a state of being arranged.

The invention according to claim 3 is:
The display medium according to claim 1, wherein the gap forming member is made of a transparent material.

The invention according to claim 4 is:
The refractive index of the gap forming member made of the transparent material is in the range of the refractive index of the dispersion medium -0.05 to the refractive index of the dispersion medium +0.05. It is a display medium of description.

The invention according to claim 5 is:
The display medium according to claim 1, wherein the gap forming member is white.

The invention according to claim 6 is:
The display medium according to claim 1, wherein the gap forming member is made of a resin material.

The invention according to claim 7 is:
The display medium according to any one of claims 1 to 6, wherein the void forming member is composed of a particle group composed of two or more void forming particles.

The invention according to claim 8 is:
8. The display medium according to claim 7, wherein an average particle diameter of the void-forming particles is within a range of 5 to 20 times an average particle diameter of all kinds of color-forming charge transfer particles. is there.

The invention according to claim 9 is
The display medium according to claim 1, wherein the void forming member is a porous body.

The invention according to claim 10 is:
The one or more color-forming charge-transfer particles are colored in different colors while dispersed in the dispersion medium, and the absolute value of the threshold value of the electric field for electrophoresis in the dispersion medium is also different from each other. The display medium according to claim 1, wherein the display medium is composed of chromogenic charge transfer particles.

The invention according to claim 11 is
In a state where the two or more kinds of color-forming charge-transfer particles are dispersed in the dispersion medium, a color-forming charge-transfer particle that develops red color, a color-form charge-transfer particle that develops green color, and a blue color The display medium according to claim 10, wherein the display medium is composed of color-forming charge-transferable particles that develop color.

The invention according to claim 12 is
In the gap between the transparent substrate and the back substrate, a cell in which a dispersion medium containing one kind of color-generating charge transfer particles is provided by providing a partition partitioning the gap is disposed,
A cell in which a dispersion medium containing color developing charge-transfer particles that develops red color when dispersed in a dispersion medium is encapsulated, and a color-generating charge transport particle that develops green color when dispersed in a dispersion medium Characterized in that it is composed of three types of cells: a cell encapsulating a dispersion medium containing benzene, and a cell encapsulating a dispersion medium containing color-developing charge transfer particles that develop a blue color when dispersed in the dispersion medium. The display medium according to any one of claims 1 to 9.

The invention according to claim 13 is:
A transparent substrate in which one surface constitutes a display surface;
A rear substrate disposed opposite to the surface opposite to the display surface of the transparent substrate;
A dispersion medium enclosed in a gap between the transparent substrate and the back substrate;
And at least two or more types of charge transfer particles that are contained in the dispersion medium and have different absolute values of the threshold value of the electric field for electrophoresis in the dispersion medium,
Among the two or more types of charge transfer particles, the charge transfer particles having the smallest absolute value of the electric field threshold value are present when only the charge transfer particles are present on the surface of the transparent substrate in the dispersion medium. Non-chromogenic charge transfer particles whose display surface shows a background color,
The display medium is characterized in that the other charge-transferable particles excluding the non-color-forming charge-transferable particles are color-forming charge-transferable particles that develop color when dispersed in the dispersion medium.

The invention according to claim 14 is:
14. The display medium according to claim 13, wherein a back electrode is provided on a surface of the back substrate on the transparent substrate side, and a transparent electrode is provided on a surface opposite to the display surface of the transparent substrate. It is.

The invention according to claim 15 is:
The display medium according to claim 13 or 14, wherein the non-color-developing charge transfer particles are made of a transparent material.

The invention according to claim 16 is:
The refractive index of the non-chromogenic charge transfer particles composed of the transparent material is in the range of the refractive index of the dispersion medium -0.05 to the refractive index of the dispersion medium +0.05. A display medium according to claim 15.

The invention according to claim 17 is:
The display medium according to claim 13 or 14, wherein the non-color-developing charge transfer particles are made of a white material.

The invention according to claim 18 is:
The display medium according to any one of claims 13 to 17, wherein the non-color-developing charge transfer particles are made of a resin material.

The invention according to claim 19 is
The average particle diameter of the non-chromogenic charge transfer particles is in the range of 1 to 10 times the average particle diameter of all kinds of chromogenic charge transfer particles. The display medium according to any one of the above.

The invention according to claim 20 is
The mobility of the non-color-generating charge-transfer particles is equal to the mobility of the charge-transfer particles having the highest mobility among other charge-transfer particles excluding the non-color-forming charge-transfer particles or The display medium according to claim 13, wherein the display medium is more than that.

The invention according to claim 21 is
The charge transfer particles other than the non-color-forming charge transfer particles are colored in different colors while being dispersed in the dispersion medium, and the absolute value of the threshold value of the electric field for electrophoresis in the dispersion medium is also The display medium according to any one of claims 13 to 20, wherein the display medium is composed of two or more different color-forming charge transfer particles.

The invention according to claim 22 is
In a state where the two or more kinds of color-forming charge-transfer particles are dispersed in the dispersion medium, the color-form charge-transfer particles that develop red color, the color-form charge-transfer particles that develop green color, and the blue color The display medium according to claim 21, comprising color-forming charge-transfer particles that develop color.

The invention according to claim 23 is
In the gap between the transparent substrate and the back substrate, a cell in which a dispersion medium containing two types of charge transfer particles is enclosed is provided by providing a partition that partitions the gap.
A cell in which a dispersion medium containing a non-chromogenic charge-transfer particle and a color-developing charge-transfer particle that develops a red color when dispersed in the dispersion medium, and the non-chromic charge-transfer particle And a cell encapsulating a dispersion medium containing chromogenic charge transfer particles that develop a green color when dispersed in a dispersion medium, and blue in a state dispersed in non-chromogenic charge transfer particles and a dispersion medium The display medium according to any one of claims 13 to 20, wherein the display medium is composed of three types of cells in which a dispersion medium containing color-generating charge-transfer particles that develop color is enclosed.

The invention according to claim 24 is
A transparent substrate in which one surface constitutes a display surface;
A transparent electrode disposed on a surface opposite to the display surface of the transparent substrate;
A rear substrate disposed opposite to the surface of the transparent substrate opposite to the display surface;
A dispersion medium enclosed in a gap between the transparent substrate and the back substrate;
One or more chromogenic charge transfer particles contained in the dispersion medium and colored in a state dispersed in the dispersion medium,
The transparent electrode is at least one selected from an aspect in which the transparent electrode is discretely arranged on the surface of the transparent substrate and an aspect in which the transparent substrate surface is discretely exposed. The display medium is disposed on a surface of the electrode opposite to the display surface.

The invention according to claim 25 is
The display medium according to claim 24, wherein a back electrode is disposed on a surface of the back substrate on which the transparent substrate is provided.

The invention according to claim 26 is
A transparent substrate in which one surface constitutes a display surface;
A transparent electrode disposed on a surface opposite to the display surface of the transparent substrate;
A rear substrate disposed opposite to the surface of the transparent substrate opposite to the display surface;
A back electrode disposed on the transparent substrate side surface of the back substrate;
A dispersion medium enclosed in a gap between the transparent substrate and the back substrate;
One or more color-forming charge-transfer particles that are contained in the dispersion medium and develop color in a state dispersed in the dispersion medium;
A void forming member that is disposed in a state of being fixed to the transparent electrode surface, and that forms a void that leads from the transparent electrode surface to the back substrate side and in which all kinds of color-generating charge-transfer particles move;
An electric field applying means for applying an electric field to the dispersion medium, connected to the transparent electrode and the back electrode, is at least a display device.

The invention according to claim 27 is
A transparent substrate in which one surface constitutes a display surface;
A transparent electrode disposed on a surface opposite to the display surface of the transparent substrate;
A rear substrate disposed opposite to the surface of the transparent substrate opposite to the display surface;
A back electrode disposed on the transparent substrate side surface of the back substrate;
A dispersion medium enclosed in a gap between the transparent substrate and the back substrate;
Two or more kinds of charge-transfer particles having different absolute values of the threshold value of the electric field for electrophoresis in the dispersion medium;
An electric field applying means connected to the transparent electrode and the back electrode for applying an electric field to the dispersion medium;
Comprising at least
Among the two or more types of charge transfer particles, the charge transfer particles having the smallest absolute value of the electric field threshold value are present when only the charge transfer particles are present on the surface of the transparent substrate in the dispersion medium. Non-chromogenic charge transfer particles whose display surface shows a background color,
The display device is characterized in that the other charge-transfer particles excluding the non-color-developable charge-transfer particles are color-forming charge-transfer particles that develop color when dispersed in the dispersion medium.

The invention according to claim 28 is
A transparent substrate in which one surface constitutes a display surface;
A transparent electrode disposed on a surface opposite to the display surface of the transparent substrate;
A rear substrate disposed opposite to the surface of the transparent substrate opposite to the display surface;
A back electrode disposed on the transparent substrate side surface of the back substrate;
A dispersion medium enclosed in a gap between the transparent substrate and the back substrate;
One or more color-forming charge-transfer particles that are contained in the dispersion medium and develop color in a state dispersed in the dispersion medium;
An electric field applying means connected to the transparent electrode and the back electrode for applying an electric field to the dispersion medium;
Comprising at least
The transparent electrode is at least one selected from an aspect in which the transparent electrode is discretely arranged on the surface of the transparent substrate and an aspect in which the transparent substrate surface is discretely exposed. The display device is disposed on a surface of the electrode opposite to the display surface.

The invention according to claim 29 is
One surface of the transparent substrate constituting the display surface opposite to the display surface is a dispersion medium and one or more types of chromogenic charge transfer that is colored in the dispersion medium and dispersed in the dispersion medium. And a light control layer containing the active particles,
All kinds of color-forming charges that pass from the surface opposite to the display surface of the transparent substrate to the direction away from the surface opposite to the display surface on the surface opposite to the display surface of the transparent substrate It is arranged in a state where a gap forming member that forms a gap in which the mobile particles move is fixed,
When one or more of all kinds of color-forming charge transfer particles are present at a position away from the surface opposite to the display surface of the transparent substrate,
At least one color-forming charge-moving particle selected from one or more kinds of color-forming charge-moving particles existing at a position away from the surface opposite to the display surface of the transparent substrate is the transparent substrate side. A first display switching step of switching a display state of the display surface by applying an electric field that moves in the dispersion medium to the light control layer;
When one or more kinds of all kinds of color-forming charge transfer particles are present on the surface of the transparent substrate opposite to the display surface,
At least one type of chromogenic charge transfer particles selected from one or more chromogenic charge transfer particles present on the opposite side of the display surface of the transparent substrate is the display of the transparent substrate. A second display switching step of switching the display state of the display surface by applying an electric field that moves in the dispersion medium in a direction away from the surface opposite to the surface to the light control layer;
Is a display method characterized by including at least.

The invention according to claim 30 is
Two or more types of charge-transfer particles having different absolute values of the dispersion medium and the threshold value of the electric field for electrophoresis in the dispersion medium on the surface opposite to the display surface of the transparent substrate constituting one display surface And a light control layer including
Among the two or more types of charge transfer particles, the charge transfer particles having the smallest absolute value of the electric field threshold value are present when only the charge transfer particles are present on the surface of the transparent substrate in the dispersion medium. Non-chromogenic charge transfer particles whose display surface shows a background color,
Other charge-transfer particles excluding the non-color-forming charge-transfer particles are color-form charge-transfer particles that develop color when dispersed in the dispersion medium,
When the non-color-developing charge transfer particles and all kinds of color-development charge transfer particles are present at a position away from the surface opposite to the display surface of the transparent substrate,
The non-color-developing charge transfer particles and at least one color-developing charge transfer particles selected from all types of color-developing charge transfer particles are opposite to the display surface of the transparent substrate. A first display switching step of switching the display state of the display surface by applying an electric field that moves in the dispersion medium from a position away from the surface to the transparent substrate side to the light control layer;
The non-color-forming charge-transfer particles are present on the surface of the transparent substrate opposite to the display surface, and one or more color-forming charges among all kinds of color-forming charge-transfer particles. When the mobile particles are present at a position away from the surface opposite to the display surface of the transparent substrate,
The at least one color-forming charge-transfer particle selected from the one or more color-forming charge-transfer particles is moved from the position away from the surface opposite to the display surface of the transparent substrate to the transparent substrate side. A second display switching step of switching a display state of the display surface by applying an electric field that moves in the dispersion medium to the light control layer;
The non-color-forming charge-transfer particles and one or more color-forming charge-transfer particles out of all types of color-forming charge-transfer particles are opposite to the display surface of the transparent substrate. If it exists in
All types of charge transfer particles present on the surface of the transparent substrate opposite to the display surface are removed from the surface of the transparent substrate opposite to the display surface to the surface of the transparent substrate opposite to the display surface. A third display switching step of switching the display state of the display surface by applying an electric field that moves in the dispersion medium to a further distance to the light control layer;
Is a display method characterized by including at least.

The invention according to claim 31 is
One surface constitutes a display surface and a transparent electrode is disposed on the surface opposite to the display surface. The transparent substrate is disposed on the surface on which the transparent electrode is disposed. A light control layer including one or more color-forming charge-transfer particles that develop color in a dispersed state is disposed;
The transparent electrode is at least one selected from an aspect in which the transparent electrode is discretely arranged on the surface of the transparent substrate and an aspect in which the transparent electrode surface is discretely exposed. Disposed on the surface of the electrode opposite to the display surface;
When one or more of all types of color-forming charge transfer particles are present at a position away from the surface of the transparent substrate on which the transparent electrode is disposed,
At least one type of chromogenic charge transporting particles selected from one or more chromogenic charge transporting particles present at a position distant from the surface on which the transparent electrode is disposed on the transparent substrate. A first display switching step of switching a display state of the display surface by applying an electric field that moves in the dispersion medium to the light control layer using at least the transparent electrode;
When one or more of all kinds of color-forming charge transfer particles are present on the surface of the transparent electrode,
A direction in which at least one color-forming charge-transfer particle selected from one or more color-forming charge-transfer particles existing on the surface of the transparent electrode is separated from the surface of the transparent substrate opposite to the display surface A second display switching step of switching a display state of the display surface by applying an electric field that moves in the dispersion medium to the light control layer using at least the transparent electrode;
Is a display method characterized by including at least.

As described above, according to the invention described in claim 1, it is possible to provide a display medium capable of displaying a clear color while suppressing a decrease in saturation as compared with the case where the configuration of the present invention is not provided. Can do.
According to the invention described in claim 2, it is possible to provide a display medium that can be used only by connecting to an external power source.
According to the third aspect of the present invention, it is possible to provide a display medium capable of displaying a clear color with higher saturation as compared with the case where the configuration of the present invention is not provided.
According to the invention described in claim 4, a clear color with higher saturation is displayed compared to the case where the refractive index of the gap forming member made of a transparent material is out of the range described in claim 4. A display medium that can be provided can be provided.
According to the invention described in claim 5, a display capable of displaying white when all kinds of color-generating charge-transfer particles move to the back substrate side as compared with the case of not having the configuration of the present invention. A medium can be provided.
According to invention of Claim 6, the display medium using the member for space | gap formation excellent in insulation can be provided.
According to the seventh aspect of the present invention, as compared with the case where the configuration of the present invention is not provided, all kinds of color development are possible from the surface opposite to the display surface of the transparent substrate to the rear substrate side. It is possible to provide a display medium including a void-forming member having a structure in which voids in which conductive charge transfer particles move are formed.
According to the eighth aspect of the present invention, it is possible to provide a display medium capable of displaying a dark display density and a clear color as compared with the case where the configuration of the present invention is not provided.
According to the ninth aspect of the present invention, as compared with the case where the configuration of the present invention is not provided, all kinds of color development are possible from the surface opposite to the display surface of the transparent substrate to the rear substrate side. It is possible to provide a display medium provided with a void-forming member having a structure in which voids in which the conductive charge-transfer particles move are formed.
According to the invention described in claim 10, a display medium capable of color display can be provided.
According to the invention described in claim 11, a display medium capable of practical color display can be provided.
According to the invention of claim 12, a display medium capable of practical color display can be provided.

According to the thirteenth aspect of the present invention, it is possible to provide a display medium capable of displaying a clear color while suppressing a decrease in saturation as compared with the case where the configuration of the present invention is not provided.
According to the fourteenth aspect of the present invention, it is possible to provide a display medium that can be used simply by connecting to an external power source.
According to the invention of claim 15, a display medium capable of displaying a clear color with higher chroma as compared with the case where the non-color-forming charge-transfer particles are composed of a translucent or colored material. Can be provided.
According to the sixteenth aspect of the present invention, the non-chromogenic charge transfer particles composed of a transparent material have a higher saturation than the case where the refractive index is outside the range of the fourth aspect. A display medium capable of displaying various colors can be provided.
According to the seventeenth aspect of the present invention, a bright white color can be displayed when all types of color-generating charge transfer particles move to the back substrate side, compared to the case where the configuration of the present invention is not provided. A display medium can be provided.
According to the eighteenth aspect of the present invention, it is possible to provide a display medium using non-color-forming charge transfer particles having excellent insulating properties as compared with the case where the structure of the present invention is not provided.
According to the nineteenth aspect of the present invention, it is possible to provide a display medium capable of displaying a dark display density and a clear color as compared with the case where the configuration of the present invention is not provided.
According to the invention of claim 20, compared to the case where the configuration of the present invention is not provided, the charge mobility particles having the greatest mobility and the non-color-forming charge mobility particles are present on the back substrate side. In this case, even when an electric field that allows the charge-mobilizing particles having the highest mobility and the non-chromogenic charge-moving particles to simultaneously move to the transparent substrate side is applied, the decrease in saturation is suppressed and clear. A display medium capable of displaying colors can be provided.
According to the twenty-first aspect, a display medium capable of color display can be provided.
According to the twenty-second aspect, a display medium capable of practical color display can be provided.
According to the invention of claim 23, a display medium capable of practical color display can be provided.

According to the twenty-fourth aspect of the present invention, it is possible to provide a display medium capable of displaying a clear color while suppressing a decrease in saturation as compared with the case where the configuration of the present invention is not provided.
According to the invention described in claim 25, it is possible to provide a display medium that can be used only by connecting to an external power source.

According to the twenty-sixth aspect of the present invention, it is possible to provide a display device capable of displaying a clear color while suppressing a decrease in saturation as compared with the case where the configuration of the present invention is not provided.
According to the twenty-seventh aspect of the present invention, it is possible to provide a display device that can suppress a decrease in saturation and display a clear color as compared with the case where the configuration of the present invention is not provided.
According to the twenty-eighth aspect of the present invention, it is possible to provide a display device that can suppress a decrease in saturation and display a clear color as compared with the case where the configuration of the present invention is not provided.

According to the twenty-ninth aspect of the present invention, it is possible to provide a display method capable of suppressing a decrease in saturation and displaying a clear color as compared with the case where the configuration of the present invention is not provided.
According to the invention of claim 30, it is possible to provide a display method capable of displaying a clear color while suppressing a decrease in saturation as compared with the case where the configuration of the present invention is not provided.
According to the invention described in claim 31, it is possible to provide a display method capable of displaying a clear color while suppressing a decrease in saturation as compared with the case where the configuration of the present invention is not provided.

In the case where charge-moving particles made of metal particles are used for an electrophoretic display medium as particles that move in a liquid by an electric field exemplified in Patent Document 1, the display surface side of the display medium is configured by the applied electric field. A first state in which metal particles are present on the surface of the transparent substrate (or the surface of the transparent electrode disposed on the surface), and the surface of the back substrate disposed opposite to the transparent substrate (or the surface of the electrode disposed on the surface) ) To change the display state such as a color pattern displayed on the display medium by controlling the second state in which the metal particles are present.
Here, if the metal particles exhibit coloration due to plasmon resonance, in the first state, the color that the metal particles color is displayed on the display medium.
However, when an electric field is applied to create a state in which metal particles are present on the surface of the transparent substrate, there is a problem that the saturation of the color displayed on the display medium is lowered and any color looks black.

  When the present inventors diligently examined the cause of this problem, the decrease in the saturation of the color displayed on the display medium is caused by the presence density of the metal particles present on the surface of the transparent substrate in the first state. It was found that this was due to the increase. Therefore, the present inventors can solve the above-described problems if the density of the metal particles present on the surface of the transparent substrate can be controlled in the first state so that the saturation of the color displayed on the display medium does not decrease. As a result, the present inventors have found the first to third inventions described below.

(First invention)
In the display method of the first aspect of the present invention, a color is developed in a state in which one surface of the transparent substrate constituting the display surface is opposite to the display surface and is contained in the dispersion medium and dispersed in the dispersion medium. And a light control layer including one or more color-forming charge-transfer particles, and a surface opposite to the display surface of the transparent substrate on a surface opposite to the display surface of the transparent substrate And a void forming member that forms a void that leads from the surface opposite to the display surface to the direction away from the display surface and forms a space in which all kinds of color-generating charge transfer particles move, When one or more of all types of color-forming charge transfer particles are present at a position away from the surface opposite to the display surface of the transparent substrate, the display surface of the transparent substrate is opposite to the display surface. From one or more chromogenic charge-transfer particles present at a position distant from the side surface The display state of the display surface is changed by applying an electric field that moves at least one kind of chromogenic charge transfer particles selected to the transparent substrate side through the dispersion medium. A first display switching step of switching, and (2) when one or more of all kinds of color-forming charge transfer particles are present on the surface of the transparent substrate opposite to the display surface, At least one type of chromogenic charge transfer particles selected from one or more chromogenic charge transfer particles present on the opposite side of the display surface of the transparent substrate is the display of the transparent substrate. A second display switching step of switching a display state of the display surface by applying an electric field that moves in the dispersion medium in a direction away from the surface opposite to the surface to the dimming layer. Including at least (note that In this display method, it is possible to first display switching step and the second display switching step is carried out in any order).

The display medium of the first aspect of the present invention is not particularly limited as long as it has a configuration capable of performing display using the display method of the first aspect of the invention. Specifically, the display medium has the following configuration. It is particularly preferable that the display medium has.
That is, the display medium of the first aspect of the present invention includes a transparent substrate having one surface constituting the display surface, a back substrate disposed opposite to the surface of the transparent substrate opposite to the display surface, and the transparent substrate. A dispersion medium enclosed in a gap between the substrate and the back substrate; one or more color-forming charge-transfer particles that are contained in the dispersion medium and develop color when dispersed in the dispersion medium; Arranged in a state of being fixed to the surface opposite to the display surface, the charge transferable particles of all kinds of color development move from the surface opposite to the display surface of the transparent substrate to the rear substrate side. It is particularly preferable to include at least a gap forming member that forms a gap to be formed.

  In the first aspect of the present invention, since the gap forming member is fixed to the surface opposite to the display surface of the transparent substrate (hereinafter sometimes referred to as “light control layer side surface”), the adjustment is performed. When an electric field is applied to the light layer to move the chromogenic charge transfer particles to the side of the light control layer of the transparent substrate, the color of the displayed color is not reduced on the side of the light control layer of the transparent substrate. It is possible to prevent an increase in the density of existing color-forming charge transfer particles. For this reason, according to 1st this invention, the display method and display medium which can suppress the fall of saturation and can display a clear color can be provided.

Application of an electric field to the dispersion medium sealed between a pair of substrates constituting the display medium is performed by arranging electrodes fixed to the display medium or external electrodes separate from the display medium on both sides of the display medium. It is also possible to do. However, since it can be used simply by connecting to an external power source, the electrodes used for applying the electric field to the dispersion medium are preferably arranged on the side of the pair of substrates facing each other. It is preferable that a back electrode is provided on the surface of the transparent substrate, and a transparent electrode is provided on the surface opposite to the display surface of the transparent substrate.
In this case, the gap forming member is fixed on the surface of the transparent electrode. Moreover, the transparent electrode provided on the transparent substrate surface in the first invention and the second invention described later is provided so as to cover the transparent substrate surface substantially without a gap. Here, “coating the transparent substrate surface substantially without gaps” does not mean that the entire surface of the transparent substrate is completely covered with the transparent electrodes without gaps. For example, the transparent electrodes are driven elements such as TFTs. The surface of the transparent substrate is formed for reasons such as forming a terminal portion for connection to a wiring, wiring, etc., insulating the transparent electrodes corresponding to the pixels to control the display state in units of pixels, or providing a black matrix. This means that there are regions where the transparent electrode is not partially covered, but the other regions are basically covered by the transparent electrode.

In the display medium of the first aspect of the present invention, it is only necessary that the dispersion medium contains one or more color-forming charge-transfer particles, but the color-forming charge-transfer particles contained in the dispersion medium are In addition, it is preferably composed of two or more types of color-transferable charge-transfer particles that are colored in different colors while dispersed in the dispersion medium, and that have different absolute values of the threshold value of the electric field for electrophoresis in the dispersion medium. . Thereby, color display can be performed.
Further, from the viewpoint that practical color display is possible, the above-described two or more color-forming charge-transfer particles are color-developing charge-transfer particles that develop a red color when dispersed in a dispersion medium. And color-forming charge-transfer particles that develop a green color, and color-form charge-transfer particles that develop a blue color.
Here, “the dispersion medium includes one or more color-forming charge transfer particles” means that the dispersion medium enclosed between a pair of substrates is divided into a plurality of cells by partition walls. This means that the dispersion medium contained in the cell contains one or more color-forming charge transfer particles. The “threshold value of the electric field for electrophoresis in the dispersion medium” means that when the electric field applied to the dispersion medium is positive, an electric field equal to or higher than the threshold value (V / m) of the electric field having a positive value is applied to the dispersion medium. In some cases, the color-forming charge-transfer particles can move in the dispersion medium, and when an electric field that is less than a positive electric field threshold is applied to the dispersion medium, the color-forming charge-transfer particles move through the dispersion medium. When the electric field applied to the dispersion medium is negative and the electric field below the threshold value (V / m) of the negative electric field is applied to the dispersion medium, When an electric field that can move through the dispersion medium and exceeds the threshold value of the electric field having a negative value is applied to the dispersion medium, the value means that the color-forming charge-transfer particles cannot move through the dispersion medium.

On the other hand, a practical color in the case where a cell in which a dispersion medium containing one kind of chromogenic charge transfer particles is provided by providing a partition partitioning the gap in the gap between the transparent substrate and the rear substrate is arranged. In the case of displaying, the cell is a cell (R cell) in which a dispersion medium containing color-forming charge transfer particles that develops red color when dispersed in the dispersion medium, and green in the state dispersed in the dispersion medium. A cell (G cell) in which a dispersion medium containing color-forming charge-transfer particles that develop color is encapsulated, and a dispersion medium that contains color-developable charge-transfer particles that produce blue color when dispersed in the dispersion medium are enclosed It is particularly preferable that the cell is composed of three types of cells (B cells).
In this case, color display control can be performed using three cells including R cells, G cells, and B cells as one pixel. These three cells are arranged adjacent to or close to each other.

-Void forming member-
Next, the gap forming member used in the first aspect of the present invention will be described in more detail. “Void forming member” communicates from the surface opposite the display surface of the transparent substrate (the surface of the transparent electrode when a transparent electrode is provided) to the rear substrate side (the direction away from the transparent substrate) and all types of color development The charge transporting particles have a gap to move.
As a result, when the first display switching step is performed, the color-forming charge-transfer particles are compared with the case where the gap-forming member is not arranged in a state of being fixed to the side of the light control layer of the transparent substrate. However, since it can move in the gap of the gap-forming member and exist at a lower density on the surface of the transparent substrate, a decrease in saturation can be suppressed and a clear color can be displayed.

This decrease in density is basically achieved because the color-forming charge transfer particles can exist in a more dispersed state with respect to the plane direction of the transparent substrate surface.
In order to suppress the decrease in saturation and display a clear color, in order to sufficiently exhibit the function of causing the color-transferable charge-transfer particles to be present at a lower density on the transparent substrate surface, the transparent substrate The contact area ratio of the gap forming member to the surface (the surface of the transparent electrode when a transparent electrode is provided) needs to be 20% or more, preferably 30% or more, and preferably 50% or more. Further preferred. When the contact area ratio is less than 20%, the above-described function as the gap forming member cannot be exhibited. On the other hand, the upper limit of the contact area ratio is not particularly limited, but if the contact area ratio is too large, the number of color-forming charge transfer particles that can exist on the transparent substrate surface is extremely small, and a sufficient display density is obtained. Since it may not be obtained, it is preferably 80% or less practically. In addition, the contact area ratio is measured with an electron microscope (SEM) or a transmission electron microscope (TEM) with respect to the cross section of the interface portion between the transparent substrate surface (or transparent electrode surface) and the gap forming member arranged on the surface. Observed, based on the obtained SEM image or TEM image, obtained from the length of the contact of the member itself constituting the gap forming member per unit length of the transparent substrate surface (or transparent electrode surface) .
In addition to this, when the color-forming charge transfer particles move to the surface of the transparent substrate through the voids of the gap-forming member, when some of the color-forming charge transfer particles get caught in the void portions, It becomes possible for the color transferable charge transfer particles to exist in a more dispersed state in the direction perpendicular to the transparent substrate surface. In this case, the dispersibility of the color-forming charge-transfer particles in the direction perpendicular to the transparent substrate surface is improved, which further contributes to the reduction in the density of the color-forming charge-transfer particles on the transparent substrate surface. .

  Moreover, it is necessary for the space | gap formation member to be arrange | positioned in the state fixed to the light control layer side surface of the transparent substrate. If the gap forming member is not fixed to the light control layer side surface of the transparent substrate, the gap forming member may be separated from the light control layer side surface of the transparent substrate, or a part of the light control layer side surface of the transparent substrate may be This is because it moves so as to be unevenly distributed only in the portion, so that the saturation is lowered or the saturation of the color displayed in the display surface is uneven.

  As for the shape of the gap forming member, if it has a structure that leads from the surface on the opposite side of the display surface of the transparent substrate to the back substrate side and has a gap through which all kinds of color-generating charge-transfer particles move. Although not particularly limited, as the member having the above-described structure having voids, a particle group composed of two or more void-forming particles or a porous body can be used.

In addition, when using the particle group which consists of two or more space | gap formation particles as a space | gap formation member, as a method of arrange | positioning in the state which fixed these particle groups to the light control layer side surface of a transparent substrate, it is specifically limited However, for example, a method of bonding and fixing the void-forming particles to the surface of the transparent substrate using heat fusion or the like, a method of filling and fixing the void-forming particles between the pair of substrates at a density that does not move, etc. Is available. Furthermore, when laminating a plurality of void-forming particles on the side of the light control layer of the transparent substrate, the first layer of void-forming particles disposed in contact with the side of the light control layer of the transparent substrate is bonded and fixed as described above. In addition, the void-forming particles in the second and subsequent layers can be bonded and fixed to each other by using heat fusion or the like.
Moreover, in order to suppress the occurrence of color unevenness displayed on the display surface, the particle group composed of two or more void-forming particles usually covers almost the entire side surface of the light control layer of the transparent substrate. Be placed.

  The particle group consisting of two or more void-forming particles arranged on the side of the light control layer of the transparent substrate is composed of charge transfer particles of all kinds that develop from the light control layer side of the transparent substrate to the back substrate side. It must have a moving gap. This void size can be adjusted by adjusting the distance between adjacent void-forming particles when (1) the void-forming particles are discretely arranged on the side of the light control layer of the transparent substrate, (2 In addition, when arranged on the side of the light control layer of the transparent substrate so that the void-forming particles are adjacent to each other or filled, the particle size of the color-forming charge transfer particles and the particle size of the void-forming particles It can be controlled by adjusting the ratio.

The average particle diameter of the void-forming particles is not particularly limited, but particularly in the case shown in the above item (2), all types of color-forming charge transfer are possible from the viewpoint of displaying a vivid color with a high display density. The average particle size of the conductive particles is preferably in the range of 5 to 20 times, and more preferably in the range of 7.5 to 15 times. When the average particle diameter of the void-forming particles is less than 5 times the average particle diameter of all types of color-forming charge-transfer particles, the color-forming charge-transfer particles are formed by void-forming particles that are adjacent to or close to each other. In some cases, it becomes difficult to move through the gaps to the surface of the transparent substrate, and the display density may be reduced.
Further, when the average particle size of the void-forming particles exceeds 20 times the average particle size of all types of color-forming charge transfer particles, the voids formed by the void-forming particles that are adjacent or close to each other become large. Therefore, when the color-generating charge-transfer particles move to the transparent substrate surface, the density of the color-forming charge-transfer particles existing on the transparent substrate surface increases, so that the decrease in saturation can be suppressed. Therefore, a clear color may not be displayed.

  The ratio of the volume of all void-forming particles to the volume of all kinds of color-forming charge transfer particles is preferably in the range of 1: 2 to 2: 1. More preferably within the range of 1.5: 1. When the ratio of the volume of the void-forming particles to the volume of all kinds of color-forming charge-transfer particles is smaller than 1: 2, excessive color-forming charge-transfer particles aggregate in the vicinity of the void-forming particles. In some cases, the saturation of the display color may decrease. On the other hand, when the ratio of the volume of the void-forming particles to the volume of all kinds of color-generating charge-transfer particles is larger than 2: 1, the flow path when the charge-transfer particles move by receiving the force of an electric field. In some cases, the display switching speed becomes slow due to resistance.

The average particle size of the void-forming particles is a particle size obtained from the area of 100 particles based on the obtained SEM image or TEM image by observing the void-forming particles used in the display medium with SEM or TEM. Obtained as an average value. Similarly, for the average particle size of all types of color-forming charge transfer particles, the average value of the particle sizes obtained from the area in the same manner as described above for 100 color development charge transfer particles of each type was determined, Further, the average value was obtained by dividing the sum of the average values of all types by the number of types of the color-forming charge transfer particles.
On the other hand, the volume of all void-forming particles was obtained by calculating the volume per particle from the average particle size obtained by the above-described procedure, and multiplying this by the number of particles per unit area existing on the transparent electrode surface. . In addition, the volume of all types of color-forming charge transfer particles is the volume of the total solids contained in the dispersion medium using solid-liquid separation (that is, the solid content of all types of color-forming charge transfer particles). Was determined by dividing this value by the total area of the transparent electrode surface.
Here, when the dispersion medium enclosed between a pair of substrates is divided into a plurality of cells by partition walls, the shape of particles such as the average particle diameter of void-forming particles and all types of color-forming charge-transfer particles -Parameter values related to size, etc. mean values obtained in cell units.

When two or more layers are formed on the side of the light control layer of the transparent substrate, the thickness of the layer formed of the particles for forming the void stacked on the side of the light control layer of the transparent substrate is 0.1 μm to It is preferably within the range of 10 μm, and more preferably within the range of 0.5 μm to 1 μm. When the thickness of the layer made of the void forming particles is less than 0.1 μm, excessive color-forming charge transfer particles may aggregate near the back surface of the void forming particles and pass through the void forming particle layer. As a result, the aggregated particle color is observed, and the saturation of the display color may be reduced. In addition, when the thickness of the layer made of the void-forming particles exceeds 10 μm, the charge transfer particles may become flow path resistance when moving under the force of an electric field, and the display switching speed may be slow.
Furthermore, the filling rate of the void-forming particles in the layer composed of the void-forming particles is preferably in the range of 30 vol% to 70 vol%, and more preferably in the range of 40 vol% to 60 vol%. When the filling rate is less than 30 vol%, the color-forming charge transfer particles may aggregate in the vicinity of the void-forming particles in the voids, and the saturation of the display color may be reduced. On the other hand, when the filling rate exceeds 70 vol%, the charge transferable particles may have a flow path resistance when moved under the force of an electric field, and the display switching speed may be slow.
In addition, the thickness and the filling rate of the layer made of the void-forming particles were determined by observing 5 points with a SEM on the cross section of the layer made of the void-forming particles, and obtained as an average value of the thickness and the filling rate at each point.

  On the other hand, the method for disposing the porous body as a void forming member in a state in which the porous body is fixed to the side of the light control layer of the transparent substrate is not particularly limited. For example, a method of bonding and fixing using heat fusion or the like can be used.

The average pore size of the porous material used as the void forming member is not particularly limited as long as it can pass all kinds of color-forming charge-transfer particles, but all kinds of color-forming charge-transfer particles are not limited. The average particle size is preferably in the range of 5 to 20 times, more preferably in the range of 7.5 to 15 times. If the average pore diameter of the porous body is less than 5 times the average particle diameter of all kinds of color-forming charge-transfer particles, it becomes difficult for the color-forming charge-transfer particles to move through the pores of the porous body. For this reason, the display speed may decrease or the clogging of holes may occur, resulting in deterioration of display characteristics over time. In addition, when the average pore diameter of the porous body exceeds 20 times the average particle diameter of all kinds of color-forming charge-transfer particles, it is transparent when the color-forming charge-transfer particles move to the transparent substrate side. In some cases, the density of the color-forming charge-transfer particles on the substrate surface becomes too high, and the saturation is lowered and a vivid color cannot be displayed.
Moreover, it is preferable that the thickness of a porous body exists in the range of 0.1 micrometer-10 micrometers, and it is more preferable that it exists in the range of 0.5 micrometer-1 micrometer. If the thickness of the porous material is less than 0.1 μm, excessive color-forming charge transfer particles may aggregate near the back of the void-forming particles, and the aggregated particles permeate through the void-forming particle layer. The color may be observed and the saturation of the display color may decrease. In addition, when the thickness of the porous body exceeds 10 μm, when the charge-moving particles move by receiving the force of the electric field, the flow resistance is generated, and the display switching speed may be slow.

Furthermore, the porosity of the porous body is preferably in the range of 30 vol% to 70 vol%, and preferably in the range of 40 vol% to 60 vol%. When the porosity is less than 30 vol%, the color-forming charge transfer particles may aggregate in the pores of the porous body, and the saturation of the display color may be lowered. On the other hand, when the porosity exceeds 70 vol%, the charge transferable particles may have a flow path resistance when moved under the force of an electric field, and the display switching speed may be slow.
Here, the average pore diameter, thickness, and porosity of the porous body were determined by SEM observation of the cross section of the porous body. The average pore diameter was determined as an average value of the pore diameters at each point by measuring the pore diameters at arbitrary five points of the pores observed in the cross section of the porous body. In addition, the thickness and the porosity were obtained as an average value of the thickness and the porosity at each point by observing 5 points on the cross section of the porous body with an SEM.
In addition, in order to suppress generation | occurrence | production of the color nonuniformity displayed on a display surface, a porous body is normally arrange | positioned so that the light control layer side surface whole surface of a transparent substrate may be coat | covered.

Next, materials constituting the gap forming member, suitable optical characteristics, and the like will be described. As the material constituting the gap forming member, a known material can be used as long as it has an insulating property and does not dissolve or deteriorate in the dispersion medium. It is particularly preferable that it is configured. Here, “having transparency with respect to visible light” means that the transmittance with respect to light having a wavelength in the visible light range (400 nm to 700 nm) is 50% or more, and the transmittance is 70% or more. It is preferable that it is close to 100%.
When the gap forming member is made of a transparent material, the light scattering caused by the gap forming member can be suppressed compared to the case where the gap forming member is not made of a transparent material, and thus the saturation is higher. A clear color can be displayed.

In addition, the refractive index of the gap forming member made of a transparent material is preferably in the range of the refractive index of the dispersion medium−0.05 to the refractive index of the dispersion medium + 0.05, and the refractive index of the dispersion medium. More preferably, it is within the range of −0.03 to the refractive index of the dispersion medium + 0.03, and most preferably the same as the refractive index of the dispersion medium. In this case, compared to the case where the refractive index of the gap forming member made of a transparent material is out of the above range, light scattering caused by the gap forming member can be further suppressed, and thus a clear color with higher saturation. Can be displayed.
The refractive index can be measured by using a laser measuring instrument, and for particles by the Becke line method, the liquid immersion method, the method of measuring attenuation for each wavelength, the method of measuring the critical angle of refraction, and the like.

  For the reasons described above, the gap forming member is preferably transparent, but may be colored, and is particularly preferably white. In this case, white color can be displayed when all kinds of color-forming charge transfer particles move to the back substrate side.

As a material constituting the gap forming member, an inorganic material or a resin material can be used from the viewpoint of excellent insulation. Here, a known material can be used as the transparent inorganic material or the transparent resin material. Examples of the dispersion medium include silicone oil (refractive index = 1.38 to 1.40), isoparaffin-based organic solvent (refractive index = 1). .39), propylene carbonate (refractive index = 1.42), etc., transparent inorganic materials include magnesium fluoride (refractive index = 1.38), calcium fluoride (refractive index = 1.40). The transparent resin material is preferably a vinylidene fluoride / tetrafluoroethylene copolymer (refractive index = 1.39 to 1.41), a trifluoroethylene / vinylidene fluoride copolymer (refractive index). = 1.35 to 1.41), poly (hexafluoro-2-propyl methacrylate) (refractive index = 1.38), poly (perfluoro i-propyl methacrylate) Refractive index = 1.37), polytetrafluoroethylene (refractive index = 1.35), poly (ethylene trifluoride) chloride (refractive index = 1.42), polymethyl methacrylate resin (PMMA, refractive index = 1.49) Etc. are preferably used.
When the void forming member is made of a porous body, porous glass or porous silica can be used, and when the void forming member is composed of a particle group composed of two or more void forming particles. Resin particles and inorganic particles can be used.

-Color developing charge transfer particles-
The color-forming charge-transfer particles used in the first aspect of the present invention have the property of being charged to either positive or negative polarity so that they can move in the dispersion medium along the electric field gradient direction when placed in an electric field. In addition, it has the property of coloring when dispersed in a dispersion medium.
Here, “coloring in a state where it is dispersed in a dispersion medium” means a state in which the color-forming charge-transfer particles are dispersed in the dispersion medium and in which the color-chargeable charge-transfer particles are dispersed. It means that it shows a hue that can be observed when visually observed. Note that the observation of the hue in this case means that the thickness of the dispersion with respect to the viewing direction is observed within a range of about 10 μm to 1 cm. The hue can be varied by changing the shape, particle size, etc. of the color-forming charge transfer particles and the material constituting the color-forming charge transfer particles.

  In the case of using two or more kinds of chromogenic charge transfer particles, it is necessary that all the chromogenic charge transfer particles are charged to the same polarity. In the case where the dispersion medium sealed between the pair of substrates is divided into a plurality of cells by the partition walls, the polarity of the color-forming charge transfer particles may be at least the same for each cell.

As the color-forming charge transfer particles, metal particles are used, and if necessary, particles whose surface is treated with a silane coupling agent or the like can be used. In addition, as a metal particle, the metal particle containing a noble metal is especially preferable.
The metal particles used as the color-forming charge transfer particles have a plasmon color developing function and have a characteristic that the particles themselves develop color.
Plasmon color development of metal particles is caused by electron plasma oscillation and is due to a color development mechanism called plasmon absorption. Color development due to this plasmon absorption is said to be because free electrons in the metal are shaken by the photoelectric field, electric charges appear on the particle surface, and nonlinear polarization occurs. The coloring by the metal particles has high saturation and light transmittance, and is excellent in durability. The color development by the metal particles is observed in so-called nanoparticles having a particle size of about several nm to several tens of nm. From the viewpoint of vividness of hue, it is advantageous that the metal particles have a narrow particle size distribution. Therefore, the average particle diameter (volume average particle diameter) of the metal particles is preferably in the range of 1 to 100 nm, and preferably in the range of 5 to 50 nm.

  The metal particles can be colored in various colors depending on the type of metal contained in the particles, the shape of the particles, and the volume average particle diameter. Therefore, various hues including RGB coloring can be obtained by using metal particles in which these are controlled. Therefore, color display is possible if a display medium is produced using a dispersion liquid in which metal particles having a plasmon coloring function are dispersed in a dispersion medium, and each color of metal particles corresponding to R, G, and B is dispersed. If the liquid is used, an RGB display medium can be manufactured.

  The volume average particle diameter of the metal particles for exhibiting the RGB colors R, G, and B depends on the metal used, the preparation conditions and the shape of the particles, and can not be particularly limited. In the case of colloidal gold particles, as the volume average particle diameter increases, R color development, G color development, and B color development tend to be exhibited.

  As a method for measuring the volume average particle diameter in the present invention, a laser diffraction scattering method is employed in which a particle group is irradiated with laser light and the average particle diameter is measured from the intensity distribution pattern of diffraction and scattered light emitted therefrom. For example, the particle size can be measured using a Microtrack particle size distribution measuring device MT3300 manufactured by Nikkiso Co., Ltd.

  As the metal contained in the metal particles, known noble metals such as gold, silver, ruthenium, rhodium, palladium, osmium, iridium and platinum are preferable, and gold and / or silver are particularly preferable. Moreover, metals (for example, copper) other than noble metals can be used. Further, the metal particles may contain two or more kinds of metals.

In addition, it is particularly preferable to treat the surface of the metal particles (hydrophilic treatment or hydrophobic treatment).
Examples of the surface treatment method include a chemical treatment method using a surface treatment agent such as a silane coupling agent and a physical treatment method for modifying the surface by imparting some physical stimulus to the surface of the color developing charge transfer particles. In the present invention, it is preferable to use a chemical treatment method.
The usable surface treatment agent can be selected in consideration of the affinity with the material constituting the particle main body of the color-forming charge transfer particles. For example, for the hydrophobic treatment, a silane compound or silicone is used. Compounds, fatty acids and the like can be used.

Here, as the silane compound used for the hydrophobic treatment, a known silane coupling agent having a molecular structure including a reactive portion that reacts with the color-forming charge-transfer particle body and a hydrophobic portion can be used.
Specifically, Octadecyltrimethoxysilane, Phenethyltrimethoxysilane, Aminopropyltriethoxysilane, 3-Aminopropyltrimethoxysilane, Metacryloxytrimethoxysilane, Methoxytrimethylsilane, 3-Aminopropyldiethoxymethylsilane, N- (-2 Aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-Aminoethyl) be exemplified -3-aminopropylmethyldimethoxysilane, etc. Can do.

Examples of the silicone compound used for the hydrophobic treatment include methylpolysiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentanesiloxane, methylcyclopolysiloxane, and methylhydrogenpolysiloxane.
Fatty acids used for hydrophobic treatment include lauric acid, myristic acid, stearic acid, oleic acid, linoleic acid, linoleic acid, hydroxy fatty acid, caproic acid, caprylic acid, palmitic acid, behenic acid, palmitoleic acid, erucic acid, Examples thereof include alkali metal salts such as sodium salt and potassium salt, alkaline earth metal salts such as magnesium salt and calcium salt, esters and the like.

-Dispersion medium-
Dispersion medium, those containing at least insulating liquid, preferably has a The volume resistivity is 10 ³ [Omega] cm or higher, more preferably ^{10 7 Ωcm~10 19 Ωcm, 10 10} ~10 19 Ωcm More preferably. By setting the volume resistance value within this range, the generation of bubbles due to the electrolysis of the dispersion medium due to the electrode reaction can be more effectively suppressed, and the electrophoretic characteristics of the electrophoretic colored particles are impaired every time energization is performed. And excellent repetitive stability can be imparted. In addition to insulating liquids, dispersion media include dispersion stabilizers such as acids, alkalis, salts and surfactants, stabilizers for the purpose of preventing oxidation and ultraviolet absorption, antibacterial agents, antiseptics, etc. Although an agent etc. can be added, it is preferable to add so that it may become in the range of the above-mentioned volume resistance value. The viscosity of the dispersion medium is not particularly limited, but is preferably in the range of 1 to 100 mPa · s.

As the insulating liquid used in the dispersion medium, known water-soluble organic solvents and hydrophobic organic solvents can be used. For example, hexane, cyclohexane, toluene, xylene, decane, hexadecane, kerosene, paraffin, isoparaffin, silicone oil, dioxane. Chloroethylene, trichlorethylene, perchlorethylene, high purity petroleum, ethylene glycol, alcohols, ethers, esters, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, N-methylpyrrolidone, 2-pyrrolidone, N-methylformamide, acetonitrile, Tetrahydrofuran, propylene carbonate, ethylene carbonate, benzine, diisopropylnaphthalene, olive oil, isopropanol, trichlorotrifluoroethane, tetrachloro Tan, and the like dibromotetrafluoroethane, mixtures thereof can be preferably used.
Moreover, water (so-called pure water) can also be suitably used by removing impurities so as to achieve the above volume resistance value.

Among the insulating liquids listed above, it is preferable to use a hydrophobic organic solvent such as hexane, cyclohexane, kerosene, paraffin, or silicone oil that is not easily decomposed even when a voltage is applied. It is particularly preferred.
The reason why silicone oil is particularly suitable is that the dispersion medium can be applied even when a voltage higher than (1) is applied as compared with the dispersion medium such as hexane, cyclohexane, kerosene, and paraffin used for the conventional electrophoretic display medium. (2) Since the viscosity is high, intense convection is unlikely to occur when metal particles are electrophoresed, and contrast deterioration and display disturbance due to this intense convection are unlikely to occur. (3) Display This is because when the medium is manufactured, when the dispersion liquid in which the metal particles are dispersed is filled under reduced pressure in the space in which the dispersion medium of the display medium is sealed, the dispersion medium is less likely to volatilize.

As the silicone oil, any known silicone oil can be used without any particular limitation.
(1) resistance is preferably at 10 ³ [Omega] cm or higher, more preferably 10 ⁷ Ωcm~10 ^{19 Ωcm,} and still more preferably ¹⁰ 10 ~10 ¹⁹ Ωcm. (2) The viscosity is more preferably 1 to 1000 cst and 1 to 100 cst. Specifically, dimethyl silicone oil such as KF-96 manufactured by Shin-Etsu Chemical Co., Ltd., DOW CORNING 200 manufactured by Dow Corning, and TSF451 manufactured by GE Toshiba Silicone Co., Ltd. can be used. In addition, modified silicone oil in which an organic group is introduced into a part of the methyl group of dimethylpolysiloxane (for example, KF-393, X22-3710 manufactured by Shin-Etsu Chemical Co., Ltd.) can be used.

-Substrate and electrode-
Examples of the substrate used in the display medium of the present invention include polyester (for example, polyethylene terephthalate), polyimide, polymethyl methacrylate, polystyrene, polypropylene, polyethylene, polyamide, nylon, polyvinyl chloride, polyvinylidene chloride, polycarbonate, and polyether sulfone. In addition, a polymer film such as a silicone resin, a polyacetal resin, a fluororesin, a cellulose derivative, and a polyolefin, a film substrate, an inorganic substrate such as a glass substrate, a metal substrate, and a ceramic substrate are preferably used.
Note that at least one of the pair of substrates used for the display medium is a transparent substrate that is transparent to visible light. When a transmissive display medium is manufactured, both substrates are transparent. A substrate is used. The transparent substrate preferably has a light transmittance of at least 50% for light in the visible range, and most preferably has a light transmittance of 100%.

  In addition, as a transparent substrate, it is preferable to use the transparent resin substrate which consists of a glass substrate, an acrylic resin, a polycarbonate resin, and a polyethylene terephthalate resin, You may use what combined these. The back substrate may be made of the same material as the transparent substrate, but an opaque or colored substrate can also be used. For example, a resin made of ABS resin (acrylonitrile / butadiene / styrene resin) or glass epoxy resin. A substrate can be used.

  Moreover, an electrode can also be provided in a board | substrate as needed. For example, when an electrode is provided on the surface of the transparent substrate on the light control layer side, a transparent electrode made of ITO (Indium Tin Oxide) or the like can be used. Moreover, when providing an electrode in the surface at the side of the light control layer of a back electrode, the electrode which consists of transparent conductive materials, such as ITO, can also be used, but the electrode which consists of metals, such as copper, can also be provided. The transparent electrode preferably has a light transmittance of at least 50% for light in the visible region, and the light transmittance is most preferably 100%.

These electrodes may be provided in a strip shape on the substrate surface, and the electrodes may be arranged in so-called rows and columns so that the electrode on the transparent substrate side and the electrode on the back substrate side are orthogonal to each other. Further, when an electrode is provided on the surface of the rear substrate on the light control layer side, an insulating film made of a resin or an inorganic material can be provided so as to cover the electrode surface for the purpose of protecting the electrode.
In addition, a switching element for driving such as a wiring, a thin film transistor, a diode having a metal / insulating layer / metal structure, a variable capacitor, or a ferroelectric may be formed on the substrate as necessary.

-Reflective member-
In the present invention, a reflecting member can be disposed between the pair of substrates as necessary. This reflection member is a member having optical reflection characteristics different from those of the color-forming charge transfer particles. In the first aspect of the present invention, it is a member having a gap in which all kinds of color-forming charge transfer particles move between the transparent substrate side and the back substrate side.

  Here, “having an optical reflection characteristic different from that of the color-forming charge transfer particles” means that the dispersion liquid in which only the color transfer charge-transfer particles are dispersed and the reflecting member are visually compared. When observed, it means that there is a difference that can distinguish between the two in terms of hue, brightness, freshness, and the like.

Further, the arrangement position of the reflecting member in the light control layer is basically disposed so as to exist in the entire surface direction of the light control layer. Here, it is particularly preferable that the color of the reflecting member is basically white. In this case, when all kinds of color-forming charge-transfer particles move to the back substrate side, when the display medium is viewed from the display surface side, the reflecting member is caused by the color-forming charge-transfer particles. Therefore, white color can be displayed. Further, when at least one kind of color-forming charge-transfer particles moves to the transparent substrate side, the higher the reflectance of the reflecting member, the clearer the display can be performed. The color of the reflecting member may be colored other than white. In this case, when at least one kind of chromogenic charge transfer particles moves to the transparent substrate side, a secondary color of the color of the chromogenic charge transfer particles and the color of the reflecting member is displayed.

Further, the reflecting member is not particularly limited as long as it has a size and shape that can be disposed between a pair of substrates. For example, a porous body or a particulate member can be used. In particular, it is preferably arranged so as to fill a space between a pair of substrates, and may be bonded and fixed to one or both substrates by thermal fusion or the like, if necessary.
As the porous body, for example, an inorganic porous body such as porous silica or a polymer having a stitch structure such as polyacrylamide can be used. As the particulate member, inorganic particles made of titanium oxide or the like, resin particles made of melamine resin, acrylic resin, polyester resin, polyether sulfone resin, polymethyl methacrylate resin, or the like can be used.
When the reflecting member is made of a resin material, a resin material having a refractive index greater than or equal to 0.1 relative to the dispersion medium is preferable, and a resin material having a refractive index greater than or equal to 0.2 relative to the dispersion medium is more preferable. For example, if the dispersion medium is silicone oil (refractive index = 1.38 to 1.4), polymethyl methacrylate resin (refractive index = 1.49) can be used. The upper limit of the refractive index of the resin material is not particularly limited, but is preferably 3.0 or less for practical use.

  When the reflecting member is a porous body, the average pore diameter is preferably in the range of more than 20 times and less than 1000 times the average particle diameter of all kinds of color-forming charge transfer particles, more than 20 times. More preferably, it is within the range of 200 times or less. The average pore diameter can be determined in the same manner as the porous body used as the void forming member.

When the reflecting member is a particulate member, the average particle size is preferably in the range of more than 25 times and not more than 1000 times the average particle size of all kinds of color-forming charge transfer particles, and 100 times It is more preferable to be within a range of ˜500 times. For example, if the average particle diameter of all kinds of color-forming charge transfer particles is 50 nm, the average particle diameter of the particulate reflecting member can be set in the range of about 10 μm to about 20 μm, for example.
In addition, when the particle size distribution of the particulate reflecting member is close to monodisperse, the particulate reflecting member may be filled between the pair of substrates in a state close to the closest packing. In this case, in order to improve the concealability by the particulate reflecting member, the particulate reflecting member filled and disposed between the pair of substrates is configured to be laminated at least about 5 to 10 layers in a direction perpendicular to the substrate. preferable.
When the reflecting member is a particulate reflecting member, it is easier to form a path through which the electrophoretic particles move than when a porous body is used, and the choice of resin material is widened. Available as

-Other components-
In the display medium of the present invention, the contents such as the dispersion medium are prevented from flowing out of the display medium, and the light control layer composed of the dispersion medium or the like enclosed between a pair of substrates is divided into a plurality of cells by partition walls. A partition wall is provided between the pair of substrates for sorting.
The height of the partition wall is not particularly limited, and is usually about 20 μm to 1 mm.
Further, the width of the partition wall is not particularly limited, but generally a smaller width is more effective from the viewpoint of the resolution of the display medium, and is usually about 10 μm to 1 mm.
Further, the material of the partition wall is not particularly limited as long as it is an insulating material and does not dissolve in the dispersion medium. For example, a known photosensitive resin or rubber can be used.

In addition, an adhesive can be used to bond the partition wall and the substrate when the display medium is manufactured. The adhesive is not particularly limited, and a thermosetting resin, an ultraviolet light curable resin, or the like can be used, but a material that does not affect the material of the partition wall or the light control layer is selected. Is done.
Furthermore, if necessary, in order to keep the gap width between the pair of substrates constant, ribs may be provided or particles having the same size as the gap width between the pair of substrates may be arranged.

-Manufacturing method of display medium-
Although the manufacturing method of the display medium of the first aspect of the present invention is not particularly limited, for example, it can be manufactured by the following process. First, as a pair of substrates, a transparent substrate in which a gap forming member is bonded and fixed to the surface on the light control layer side in advance and a back substrate are prepared. As these substrates, electrodes may be provided in advance. Then, after forming a partition in the surface by the side of either one of a transparent substrate or a back substrate, both are bonded together. Note that when bonding, a reflective member may be disposed between the pair of substrates in advance if necessary. Subsequently, a display medium can be obtained by injecting a dispersion medium containing one or more color-forming charge transfer particles from a dispersion medium injection port provided in advance when the partition wall is formed, and sealing the injection port. it can.

-Display device-
Next, a display device using the display medium of the first invention described above will be described. The display device of the present invention has a pair of electrodes when the display medium of the first invention incorporates a pair of electrodes at a position where an electric field can be applied to the dispersion medium sealed between the pair of substrates. And an electric field applying means for applying an electric field to the dispersion medium.
For example, when a back electrode is provided on the surface of the back substrate on the transparent substrate side and a transparent electrode is provided on the surface of the transparent substrate opposite to the display surface, an electric field applying unit is connected to the pair of electrodes.
Thereby, when displaying, it can display, without connecting with an external electric field application means. As the electric field applying means, either an AC power source or a DC power source can be used as necessary. When applying an AC voltage and a DC voltage superimposed on the light control layer via electrodes, both are used in combination. You can also

-Specific examples of display media (display devices)-
Hereinafter, specific examples of the display medium of the first aspect of the present invention will be described with reference to the drawings. However, the display medium of the first aspect of the present invention is not limited to the examples described below.
FIG. 1 is a schematic diagram showing an example of the display medium according to the first aspect of the present invention. FIG. 1 (A) shows a state where the first display switching process has been completed, and FIG. 2 shows a state where the display switching step 2 has been completed. Here, in the figure, 100 is a display medium, 200 is a transparent substrate, 202 is a display surface, 204 is a back substrate, 206 is a partition, 210 is a transparent electrode, 220 is a back electrode, 300 is a chromogenic charge transfer particle, Reference numeral 400 denotes void-forming particles, and 500 denotes a power source.

  A display medium 100 shown in FIG. 1 has a transparent substrate 200 in which one surface constitutes a display surface 202 and a transparent electrode 210 is provided on the other surface, and a surface of the transparent substrate 200 on which the transparent electrode 210 is provided. It is arranged at the end of the gap between the transparent substrate 200 and the back substrate 204, and the back substrate 204 provided with the back electrode 220 on the surface on which the transparent substrate 200 is arranged. The entire surface of the partition 206 is arranged on the surface of the transparent electrode 210, the partition 206 disposed so as to stop, the dispersion medium 302 including the color-transferable charge-transfer particles 300 sealed in the gap between the transparent substrate 200 and the back substrate 204. And void-forming particles 400 arranged in a fixed state so as to be covered. The transparent electrode 210 and the back electrode 220 of the display medium 100 are connected to an electric field applying unit 500 so that an electric field can be applied to the dispersion medium 302. A region surrounded by the pair of substrates 200 and 204 and the partition wall 206 corresponds to a light control layer.

Here, for example, when the positively charged red metal particles are used as the color-forming charge transfer particles 300 and the white resin particles (white resin particles) are used as the void-forming particles 400, the display is as follows. It is done as follows.
First, in the state shown in FIG. 1A, since a negative voltage is applied to the transparent electrode 210 side and a positive voltage is applied to the back electrode 220 side, the color-forming charge transfer particles 300 are present on the transparent substrate 200 side. . However, since the void-forming particles 400 are arranged on the surface of the transparent electrode 210 in a fixed state, the chromogenic charge transfer to the gap between the particles 400 or the surface of the transparent electrode 210 not covered with the particles 400. The conductive particles 300 are dispersed and exist at a low density. In this state, a clear red color is displayed on the display surface 202 of the display medium 100.

Subsequently, when a positive voltage is applied to the transparent electrode 210 side and a negative voltage is applied to the back electrode 220 side, the color-forming charge transfer particles 300 move from the transparent substrate 200 side to the back substrate 204 side, and FIG. Changes to the state shown in FIG. 1B (second display switching step).
In the state shown in FIG. 1B, since the color-forming charge transfer particles 300 are present on the surface of the back electrode 220, white is displayed on the display surface 202 of the display medium 100. In this state, when a negative voltage is applied again to the transparent electrode 210 side and a positive voltage is applied to the back electrode 220 side, the color-forming charge transfer particles 300 move from the back substrate 204 side to the transparent substrate 200 side, and FIG. The state shown in FIG. 1B changes to the state shown in FIG. 1A (first display switching step), and a clear red color is displayed on the display surface 202 of the display medium 100.

As the configuration of each part of the display medium 100 shown in FIG. 1, for example, positively charged red metal particles are used as the color-forming charge transfer particles 300, and resin particles made of a transparent material are used as the void-forming particles 400. Using (transparent resin particles), the distance between the transparent electrode 210 and the back electrode 220 can be 50 μm, and the viscosity of the dispersion medium 302 can be 1 mPa · s.
In this case, although depending on the charge amount of the chromogenic charge transfer particles 300, for example, the smallest electric field (the electric field having a positive value) in which the chromogenic charge transfer particles 300 can move in the dispersion medium 302 is used. (Threshold) is less than 3V, when a voltage of about 3-10V is applied, the display state shown in FIG. 1 (B) from the display state shown in FIG. Alternatively, the display state shown in FIG. 1B changes to the display state shown in FIG. In order to shorten the time required for switching the display state, for example, the charge amount of the color-forming charge-moving particles 300 is increased, the interval between the transparent electrode 210 and the back electrode 220 is decreased, or application is performed. It can be controlled by increasing the voltage.

  When the application of the electric field is stopped in the state shown in FIG. 1A or FIG. 1B, the chromogenic charge transfer particles 300 gathered on the transparent electrode 210 or the back electrode 220 side are affected by gravity. The display state changes because it is gradually dispersed in the dispersion medium 302 by natural diffusion. For example, in the state shown in FIG. 1A, the density of red gradually decreases. For this reason, it is preferable to increase the viscosity of the dispersion medium 302 so that the display state before the application of the electric field can be maintained even after the application of the electric field is stopped.

  FIG. 2 is a schematic diagram showing another example of the display medium of the first aspect of the present invention. FIG. 2A shows a state in which color-forming charge transfer particles are present on the entire surface of the transparent substrate. 2 (B) shows a state in which color-forming charge transfer particles are present in a part of the surface of the transparent substrate. Here, in the figure, reference numeral 102 denotes a display medium, 210A and 210B denote transparent electrodes, 500A and 500B denote power supplies, and members indicated by other symbols basically have the same functions as those shown in FIG. It is what you have. However, in FIG. 2, transparent resin particles (transparent resin particles) are used as the void forming particles 400.

The display medium 100 shown in FIG. 1 has a structure in which one electrode is provided on each of a pair of substrates in one cell divided by a partition wall. In this case, for example, two or more electrodes may be provided on the transparent substrate (and / or back substrate) side.
The display medium 102 shown in FIG. 2 basically has the same configuration as the display medium 100 shown in FIG. 1, but the transparent electrode 210 in the display medium 100 is divided into two independent transparent electrodes 210A and 210B. In addition, the second embodiment is different from the first embodiment in that the electric field applying unit 500A connected to the transparent electrode 210A and the back electrode 220 and the electric field applying unit 500B connected to the transparent electrode 210B and the back electrode 220 are provided.

  Next, the display operation in the display medium 102 shown in FIG. 2 will be described. First, in a state where the color-forming charge transfer particles 300 are present on the surface of the back electrode 220 or dispersed in the dispersion medium 302, the back electrode 220 side is positive and the transparent electrodes 210A and 210B are both at the same potential. When a negative voltage is applied, the color-forming charge-moving particles 300 move toward the transparent electrodes 210A and 210B, so that a clear red color is displayed on the entire display surface 202 (FIG. 2A).

  On the other hand, when the color-forming charge transfer particles 300 are present on the surface of the back electrode 220 or dispersed in the dispersion medium 302, a positive voltage is applied to the back electrode 220 side and a negative voltage is applied only to the transparent electrode 210B side. Then, since the chromogenic charge transfer particles 300 move to the transparent electrode 210B side, a clear red color is displayed on a portion of the display surface 202 corresponding to the region where the transparent electrode 210B is provided. In the portion corresponding to the area where the transparent electrode 210A of 202 is provided, the color of the back substrate 204 (however, the back electrode 220 when the back electrode 220 is colored) is displayed (FIG. 2B). . For example, if the back substrate 204 is white and the back electrode 220 is colorless, white is displayed on the portion of the display surface 202 corresponding to the area where the transparent electrode 210A is provided.

Next, an example of a display medium having a configuration in which a reflective member is provided in the gap between the pair of substrates 200 and 204 in the display medium 100 illustrated in FIG. 1 will be described.
FIG. 3 is a schematic diagram showing another example of the display medium of the first aspect of the present invention. FIG. 3 (A) shows a state where the first display switching process has been completed, and FIG. The state which finished implementing the 2nd display switching process is shown. Here, in the figure, reference numeral 104 denotes a display medium, 600 denotes a reflecting member made of a white porous body, and members indicated by other symbols basically have the same functions as those shown in FIG. Is. However, in FIG. 3, transparent resin particles (transparent resin particles) are used as the void-forming particles 400.

The display medium 104 shown in FIG. 3 basically has the same configuration as the display medium 100 shown in FIG. 1, but is made of a white porous body so as to fill the gap between the pair of substrates 200 and 204 without any gaps. This is different in that it has a configuration in which the reflecting member 600 is filled.
The display operation of the display medium 104 shown in FIG. 3 is basically the same as the display operation of the display medium 100 shown in FIG. 1, but as shown in FIG. When the display medium 104 is observed from the display surface 202 side in the state where the surface electrode 220 is present on the surface of the back electrode 220, the color developing charge-transfer particles 300 are concealed by the reflecting member 600 made of a white porous body. In 202, white is displayed. In the state shown in FIG. 3A, a clear red color is displayed.

  FIG. 4 is a schematic diagram showing another example of the display medium of the first aspect of the present invention. FIG. 4 (A) shows a state where the first display switching process has been completed, and FIG. The state which finished implementing the 2nd display switching process is shown. In the figure, reference numeral 106 denotes a display medium, 602 denotes a reflective member made of white particles, and members indicated by other reference numerals have basically the same functions as those shown in FIG. is there. However, in FIG. 4, transparent resin particles (transparent resin particles) are used as the void-forming particles 400.

The display medium 106 shown in FIG. 4 is the same as the display medium 104 shown in FIG. 3, instead of filling the reflective member 600 made of a white porous body between the pair of substrates 200 and 204, the reflective member 602 made of white particles. Is filled in such a manner that a plurality of layers are stacked in the thickness direction of the display medium 106.
The display operation of the display medium 106 shown in FIG. 4 is basically the same as the display operation of the display medium 104 shown in FIG. 3, but as shown in FIG. When the display medium 104 is observed from the display surface 202 side with the surface electrode 220 existing on the surface of the back electrode 220, the color-forming charge-transfer particles 300 are concealed by the reflecting member 602 made of white particles, and thus are displayed on the display surface 202. Will display white. In the state shown in FIG. 4A, a clear red color is displayed.

In the display medium illustrated in FIGS. 1 to 4 described above, the movement of the color-generating charge transfer particles 300 is performed by using a pair of electrodes provided on the surfaces of the pair of substrates 200 and 204 facing each other. Although it is controlled by using a pair of electrodes, a pair of electrodes can be arranged outside or outside the display medium, and control can be performed by using these electrodes.
FIG. 5 is a schematic diagram showing another example of the display medium according to the first aspect of the present invention. Has the same function as that shown in FIG. In FIG. 5, the direction X1-X2 means a direction parallel to the width direction of the display medium 108, and in FIG. 5, this direction is called the medium width direction.

The display medium 108 shown in FIG. 5 basically has a configuration in which the transparent electrode 210 and the back electrode 220 are removed from the display medium 104 shown in FIG. Here, the display state of the display medium 108 is controlled by using the scanning electrode 250 and the back electrode 260 that are arranged on both surfaces of the display medium 108 and connected to the electric field applying unit 500.
The length of the scan electrode 250 in the medium width direction is sufficiently smaller than the length of the transparent substrate 200 in the medium width direction, and can be, for example, the same length as the length of one pixel in the medium width direction. Further, the scanning electrode 250 can move relative to the display medium 108 on the surface of the display medium 108 on the side where the transparent substrate 108 is disposed, at least in the medium width direction.
On the other hand, the length of the back electrode 260 in the medium width direction is the same as the length of the back substrate 204 in the medium width direction, and is basically a region where the dispersion medium 302 sealed between the pair of substrates 200 and 204 exists. The length can be consistent with.

Here, the display state on the display medium 108 corresponds to the image information at a predetermined timing, for example, while moving the scanning electrode 250 relative to the display medium 108 in the direction X1 to X2 in the figure. It can be controlled by applying a voltage to the scan electrode 250 and the back electrode 260.
In this case, when the scan electrode passes through the regions A1 and A3 shown in the drawing, a negative voltage is applied to the scan electrode 250, and a positive voltage is applied to the back electrode 260, and when the scan electrode passes through the region A2, the scan electrode 250 is applied. In addition, by applying a negative voltage to the back electrode 260, a clear red color can be displayed on the portion corresponding to the regions A1 and A3 on the display surface 202, and a white color is displayed on the portion corresponding to the region A2 on the display surface 202. Can be displayed. The voltage application time at any one point in the medium width direction at this time is the minimum time required for the color-forming charge transfer particles 300 to move from one substrate surface to the other substrate surface. It sets so that it may become above.

  Specific specifications of the display medium 108 are not particularly limited. For example, the length of the scanning electrode 250 in the medium width direction is 0.5 mm, and the electrode density (resolution) in this case is 50 dots per inch, the back surface. The electrode 260 can be a sheet-like aluminum plate, and its potential can be a ground potential. In this case, the moving speed of the scanning electrode 250 is 1 mm / s, the pulse frequency of the voltage to be applied is 2 Hz, the pulse width is 0.4 seconds, the voltage to be applied to the scanning electrode 250 is 10 to 50 V, and according to the image information. When a voltage is applied, a desired image can be displayed.

Note that the back electrode 260 may be fixed to the surface of the display medium 108 or may be removable, and is the same size as the scan electrode 250 and is movable in synchronization with the scan electrode 250. There may be. In the example shown in FIG. 5, the back electrode 260 is disposed outside the display medium 108, but can be provided inside the back substrate 204 or on the surface of the back substrate 204 on the side where the transparent substrate 200 is disposed.
A plurality of scanning electrodes 250 can be arranged along a direction perpendicular to the medium width direction (in the drawing, a direction perpendicular to the paper surface, hereinafter referred to as “medium depth direction”). That is, desired image information can be displayed at an arbitrary position on the display surface 202 by dividing the medium depth direction and moving the medium width direction by the plurality of scanning electrodes 250. In the case where the display surface 202 is divided in a direction orthogonal to the medium depth direction, and each of the divided areas is provided with a scan electrode 250 that can scan along the medium width direction, 1 is exemplified as shown in FIG. However, two or more of them may be arranged.

  As a method of relatively moving the scan electrode 250 and the display medium 108, for example, the scan electrode 250 can be moved by hand while the display medium 108 is fixed. However, the scan electrode 250 can be moved at a constant speed. It is preferable to use a method capable of relatively moving 250 and the display medium 108.

For example, the scanning electrode 250 may be moved at a constant speed on the surface in contact with the surface of the display medium 108 so that the scanning electrode 250 can move at a constant speed on the surface of the display medium 108 on which the transparent substrate 200 is disposed. Writing means including a roller whose scanning speed can be controlled so that it can rotate and the scanning electrode 250 can be used.
In addition, a scanning electrode 250 and a back electrode 260 are mounted inside a writing apparatus having a roller for transporting the display medium 108 inside the housing so that the display medium 108 can pass through the gap between the two. Can be controlled so that the display medium 108 can move at a constant speed with respect to the scanning electrode 250. In this case, the scanning electrode 250 and the back electrode 260 may have a roller shape so that the display medium 108 can be conveyed.

  FIG. 6 is a schematic diagram showing another example of the display medium of the first invention, in which 110 is a display medium, 270 is an external electrode, 270A, 270B, 270C, 270D, 270E is an electrode, and 272 is an electrode. The external electrode holding member, 280 represents a back electrode, 282 represents a back electrode holding member, and members denoted by other reference numerals have the same functions as those shown in FIG. In FIG. 6, the direction of reference signs X1-X2 means a direction parallel to the width direction of the display medium 110, and in FIG. 6, this direction is referred to as a medium width direction.

The display medium 110 shown in FIG. 6 basically has a configuration in which the transparent electrode 210 and the back electrode 220 are removed from the display medium 104 shown in FIG. Here, the display state of the display medium 110 is controlled using the external electrode 270 and the back electrode 280 that are arranged on both surfaces of the display medium 110 and connected to the electric field applying unit 500.
In the example shown in FIG. 6, the external electrode 270 is composed of five independently controllable electrodes 270A, 270B, 270C, 270D, and 270E arranged in order along the medium width direction. The length in the direction is smaller than the length of the transparent substrate 200 in the medium width direction, and is basically preferably the same length as the length of one pixel in the medium width direction.
On the other hand, the length of the back electrode 280 in the medium width direction is the same as the length of the back substrate 204 in the medium width direction, and is basically a region where the dispersion medium 302 sealed between the pair of substrates 200 and 204 exists. The length can match.

Here, the display state on the display medium 110 can be controlled, for example, by sequentially applying voltages to these electrodes and the back electrode 260 with a time difference between the individual electrodes constituting the external electrode 270.
As a result, red or white is displayed on the display surface 202 so as to correspond to the area where the respective electrodes 270A, 270B, 270C, 270D, 270E are provided. For example, when the chromogenic charge transfer particles 300 are present on the entire surface of the transparent substrate 200 (that is, when the entire display surface 202 displays red), the electrode 270B has a positive voltage and the back electrode 260 has a negative voltage. Is applied, only the color displayed on the display surface 202 in the region corresponding to the electrode 270B changes from red to white (FIG. 6).

  The individual electrodes constituting the external electrode 270 may have a shape corresponding to one pixel, but the direction perpendicular to the medium width direction (in the figure, the direction perpendicular to the paper surface, hereinafter “medium It may be a strip-shaped electrode whose longitudinal direction is referred to as “depth direction”. In the latter case, the back electrode 280 can also have a so-called simple matrix structure by forming a belt-like electrode whose longitudinal direction is the medium width direction.

The back electrode 280 held by the back electrode holding member may be fixed to the surface of the display medium 110 or may be removable. In the example shown in FIG. 6, the back electrode 280 is disposed outside the display medium 110.
The external electrode 270 and the external electrode holding member 272 that holds the external electrode 270 are basically detachable from the display medium 110, and when image information is written on the display medium 110, the display medium 110 is transparent. The substrate 200 is fixedly disposed so as to be in contact with (or close to) the surface on the side on which the substrate 200 is provided. However, when the external electrode 270 and the external electrode holding member 272 that holds the external electrode 270 are formed of a member that transmits visible light, the surface of the display medium 110 on the side where the transparent substrate 200 is provided is provided. It can also be arranged in a fixed state.

In all of the display media exemplified above, a case where one type of color-migrating charge transfer particles is contained in one cell in which a dispersion medium enclosed between a pair of substrates is divided by a partition wall is shown. One cell may contain two or more color-forming charge transfer particles, and a configuration example of this type of display medium will be described below.
FIG. 7 is a schematic diagram showing another example of the display medium of the first invention. In the figure, 112 represents a display medium, 300A, 300B, and 300C represent color-forming charge-transfer particles, The members indicated by reference numerals have the same functions as those shown in FIG.
The display medium 112 shown in FIG. 7 basically has the same configuration as that of the display medium shown in FIG. 4, but in the display medium 106 shown in FIG. This is different in that the conductive particles 300A, 300B, and 300C are used.

The three types of color-forming charge transfer particles 300A, 300B, and 300C are all charged to the same polarity, and develop colors in different colors while being dispersed in the dispersion medium 302, and also perform electrophoresis in the dispersion medium 302. The absolute values of the electric field threshold values are different from each other, and in the following description, all of them are positively charged, and the first color-forming charge-transfer particles 300A are red metal particles and the second color-forming properties. In the following description, it is assumed that the charge transfer particles 300B are made of green metal particles, and the third color-forming charge transfer particles 300C are made of blue metal particles.
Here, the threshold value of the electric field of these three kinds of color-forming charge transfer particles 300A, 300B, and 300C can be set as shown in FIG. 8, for example.

  FIG. 8 is a graph for explaining the relationship between the threshold value of the electric field and the display density of the three types of chromogenic charge transfer particles used in the display medium shown in FIG. Here, the “electric field strength” shown on the horizontal axis in the drawing means a potential (V / cm) per unit distance in a direction perpendicular to the surface of the transparent substrate 202, which is positive on the back electrode 220 side and on the transparent electrode 210 side. When a negative voltage is applied, it means a plus (right side of the graph), and the “display density” shown on the vertical axis indicates that three types of color-forming charge-transfer particles 300A, 300B, and 300C are used individually. In the case of the assumption, it means the density (relative density) of the color shown on the display surface 202, and the state where the color density of the charge-transferring particles moves to the transparent substrate 200 side and the display density becomes higher is the upper direction of the graph. means.

  As will be apparent from FIG. 8, when the color-generating charge transfer particles 300A are described as an example, a positive electric field is applied to the dispersion medium 302, and the intensity is further increased to the positive side. When the electric field threshold E1 or more is reached, the chromogenic charge transfer particles 300A move from the back substrate 204 side to the transparent substrate 200 side, the red display density becomes high, and the red color before the electric field strength reaches E2. The display density of becomes saturated. In this state, a negative electric field is applied to the dispersion medium, and the intensity thereof is further increased to the negative side. When the electric field intensity becomes −E1 or less, which is the threshold value of the electric field, the chromogenic charge transfer particles 300A are It moves from the transparent substrate 200 side to the back substrate 204 side, the red display density becomes lighter, and the red display density becomes the lowest before the electric field strength reaches -E2.

  Similarly, in the chromogenic charge transfer particles 300B, the display density increases (or decreases) when the electric field strength is equal to or higher than the electric field threshold E2 (or lower than -E2), and the electric field strength becomes E3 (or -E3). The display density becomes saturated (or lowest) before reaching, and in the color-generating charge transfer particles 300C, the display density increases (or decreases) when the electric field strength is equal to or higher than the electric field threshold E3 (or lower than -E3). When the intensity reaches E3 + α (or -E3-α), the displayed density is saturated (or becomes the lowest).

Further, as shown in FIG. 8, the absolute value of the threshold value of the electric field of each of the three types of color-forming charge-transfer particles 300A, 300B, and 300C has a relationship of | E1 | <| E2 | <| E3 | ing. For this reason, if a voltage is applied using the difference in the absolute value of the threshold value of the electric field of each of the three types of color-generating charge transfer particles 300A, 300B, 300C, , Red (R), green (G), blue (B), and these RGB secondary and tertiary colors can be displayed.
The method for controlling the threshold value of the electric field is not particularly limited. For example, the difference in adhesion force to the reflecting member 602 made of white particles of each of the three types of color-generating charge transfer particles 300A, 300B, and 300C. For example, the average particle diameter of the color-forming charge transfer particles 300A, 300B, and 300C, the surface treatment state of the particles, and the charge control agent to be treated on the particle surface can be selected.

  In the present invention, the threshold value of the electric field exemplified in FIG. 8 is the gap length between the pair of electrodes used for applying the electric field (the gap length between the transparent electrode 210 and the back electrode 220 in the example shown in FIG. 7). When the voltage applied to the pair of electrodes is changed and the color displayed on the display medium is observed, the display density of a specific color (red, green, blue in the example shown in FIG. 7) starts to change. Can be easily obtained by grasping.

Next, an example of the display operation of the display medium 112 will be described below on the assumption that the three types of color-generating charge transfer particles 300A, 300B, and 300C satisfy the relationship shown in FIG.
First, when a voltage is applied so that the electric field strength becomes E3 + α, all of the color-forming charge transfer particles 300A, 300B, and 300C move to the transparent substrate 200 side, and the display surface 202 is subtracted by subtractive color mixture of R, G, and B. Is displayed in black. Subsequently, when a voltage is applied so that the electric field strength becomes −E3-α, the color-forming charge-transfer particles 300A, 300B, and 300C all move to the back substrate 204 side, and these three kinds of particles are displayed on the display surface. When viewed from the side 202, the display surface 202 displays white because it is concealed by the reflecting member 602 made of white particles.

In addition, when a voltage is applied from the state where white is displayed on the display surface 202 so that the display density due to the color-generating charge transfer particles 300B is saturated when the electric field strength is E2 or more and less than E3, Since the charge transfer particles 300A, 300B move from the back substrate 204 side to the transparent substrate 200 side, secondary colors of red and green are displayed on the display surface 202 (display state shown in FIG. 7).
In this state, when a voltage is applied so that the electric field intensity is more than −E2 and less than or equal to E1, and the display density caused by the color-forming charge-transfer particles 300A is minimized, the color-form charge-transfer particles 300A Since it moves from the transparent substrate 200 side to the back substrate 204 side, among the three kinds of color-forming charge-transfer particles 300A, 300B, and 300C, only the color-forming charge-transfer particles 300B exist on the transparent substrate 200 side. The display surface is displayed in green.

Next, a display medium capable of performing color display in a configuration in which one type of color-generating charge-transfer particles is contained in one cell in which a dispersion medium sealed between a pair of substrates is partitioned by a partition wall A configuration example will be described.
FIG. 9 is a schematic diagram showing another example of the display medium of the first invention. In the figure, 114 is a display medium, 114A, 114B, and 114C are display cells, and 310A, 310B, and 310C are chromogenic. Charge-transfer particles, 210A, 210B, and 210C are transparent electrodes, 220A, 220B, and 220C are back electrodes, and members denoted by other reference numerals have the same functions as those shown in FIG. . In the figure, the description of the power supply connected to each electrode is omitted.

On the other hand, in FIGS. 1 to 7, for convenience of explanation, only one cell portion in which a dispersion medium sealed between a pair of substrates is divided by a partition wall is shown. They can be arranged in one row or arranged two-dimensionally.
Here, the display medium 114 shown in FIG. 9 includes three display cells 114A, 114B, and 114C in which one cell shown in FIG. 4 is arranged in a line with respect to the planar direction of the transparent substrate 200. . However, the color-forming charge transfer particles 310A, 310B, and 310C used in the respective display cells 114A, 114B, and 114C are different from each other in the color that develops when dispersed in the dispersion medium. The chromogenic charge transfer particles 310A are made of red metal particles, the chromogenic charge transfer particles 310B are made of green metal particles, and the chromogenic charge transfer particles 310C are made of blue metal particles. To do.
Therefore, the display medium 114 performs color display by controlling the display state of the individual display cells 114A, 114B, and 114C with these three display cells 114A, 114B, and 114C as one unit, that is, one pixel. Can do.

  For example, in the display cell 114A, the chromogenic charge transfer particles 310A are present on the transparent substrate 200 side, in the display cell 114B, the chromogenic charge transfer particles 310B are present on the back substrate 204 side, and in the display cell 114C. If the display state of each of the display cells 114A, 114B, and 114C is controlled so that the chromogenic charge transfer particles 310C exist on the transparent substrate 200 side, the secondary colors of red and blue can be displayed. (Display state shown in FIG. 9).

In the display medium 114 shown in FIG. 9, the display cell 114A is provided with a transparent electrode 210A and a back electrode 220A so that an electric field can be independently applied to the display cells 114A, 114B, and 114C. The transparent electrode 210B and the back electrode 220B are provided in 114B, and the transparent electrode 210C and the back electrode 220C are provided in the display cell 114C.
However, in order to simplify the structure of the display medium 114, one transparent electrode and one back electrode common to the three display cells 114A, 114B, and 114C may be provided. However, in this case, since an electric field is simultaneously applied to the three display cells 114A, 114B, and 114C, the chromogenic charge transfer particles 310A, 310B, and 310C used in the respective display cells 114A, 114B, and 114C. It is necessary to adjust so that the absolute value of the threshold value of the electric field becomes different from each other. Accordingly, color display can be performed by applying an electric field according to the threshold value of the electric field of the color-forming charge transfer particles 310A, 310B, and 310C.

(Second invention)
In the display method of the second aspect of the present invention, the absolute value of the dispersion medium and the threshold value of the electric field for electrophoresis in the dispersion medium is formed on the surface opposite to the display surface of the transparent substrate in which one surface constitutes the display surface. A light control layer including two or more different types of charge transfer particles is disposed, and among the two or more types of charge transfer particles, the charge transfer particles having the smallest absolute value of the electric field threshold are the charge transfer particles. The non-color-forming charge-transfer particles in which the display surface exhibits a background color when only the color-forming particles are present on the transparent substrate surface side in the dispersion medium, and other than the non-color-forming charge-transfer particles The charge-transfer particles are color-forming charge-transfer particles that develop color when dispersed in the dispersion medium. (1) The non-color-forming charge-transfer particles and all types of color-transfer charge-transfer particles Exists at a position away from the surface opposite to the display surface of the transparent substrate. In this case, the non-color-developing charge-transfer particles and at least one color-developing charge-transfer particles selected from the all types of color-developing charge-transfer particles are used for the transparent substrate. A first state for switching the display state of the display surface by applying an electric field for moving the dispersion medium from a position away from the surface opposite to the display surface to the transparent substrate side to the light control layer. A display switching step, and (2) the non-color-forming charge-transfer particles are present on the surface of the transparent substrate opposite to the display surface, If one or more color-forming charge-transfer particles are present at a position away from the surface opposite to the display surface of the transparent substrate, select from the one or more color-forming charge-transfer particles. At least one color-forming charge transfer particle, The display state of the display surface by applying, to the light control layer, an electric field that moves the dispersion medium from a position away from the surface opposite to the display surface of the transparent substrate to the transparent substrate side. A second display switching step for switching between, and (3) the non-color-forming charge-transfer particles and one or more color-forming charge-transfer particles among all types of color-forming charge-transfer particles. When present on the surface of the transparent substrate opposite to the display surface, all kinds of charge transfer particles existing on the surface of the transparent substrate opposite to the display surface are transferred to the display of the transparent substrate. The display surface by applying an electric field for moving the dispersion medium from the surface opposite to the surface to a position away from the surface opposite to the display surface of the transparent substrate. A third display switching step of switching the display state of at least (In this display method, the first to third display switching steps can be performed in an arbitrary order).

The display medium of the second aspect of the present invention is not particularly limited as long as it has a configuration capable of performing display using the display method of the second aspect of the invention. Specifically, the display medium has the following configuration. It is particularly preferable that the display medium has.
That is, the display medium of the second aspect of the present invention includes a transparent substrate having one surface constituting the display surface, a rear substrate disposed opposite to the surface of the transparent substrate opposite to the display surface, and the transparent substrate. A dispersion medium enclosed in a gap between the substrate and the back substrate; and two or more types of charge-transfer particles included in the dispersion medium and having different absolute values of threshold values of electric fields for electrophoresis in the dispersion medium; Of the two or more types of charge transfer particles, the charge transfer particles having the smallest absolute value of the threshold value of the electric field are only present on the surface of the transparent substrate in the dispersion medium. In this case, the display surface is a non-color-forming charge-transfer particle having a background color, and other charge-transfer particles other than the non-color-forming charge-transfer particle are colored in a state of being dispersed in the dispersion medium. Particularly preferred are chromogenic charge transfer particles. .

In the second aspect of the present invention, an electric field is applied because the non-color-forming charge-moving particles among the two or more types of charge-moving particles contained in the dispersion medium have the smallest absolute value of the electric field threshold. In the case where at least one of the color-forming charge-transfer particles contained in the dispersion medium moves to the transparent substrate side, the non-color-forming charge-transfer particles are previously formed on the side of the light control layer of the transparent substrate. Existing. For this reason, the chromogenic charge transfer particles pass through the gap between the non-chromogenic charge transfer particles present on the side of the light control layer of the transparent substrate and move to the transparent substrate side. In addition, when the non-color-forming charge-transfer particles are present in a state of being laminated on the transparent substrate surface, the color-forming charge-transfer particles that have moved from the back substrate side are non-color-forming charge-transfer particles. It will also get caught in the gap.
Therefore, according to the second aspect of the present invention, it is possible to prevent an increase in the density of the color-forming charge transfer particles present on the side of the light control layer of the transparent substrate to such an extent that the saturation of the displayed color does not decrease. Thus, it is possible to provide a display method and a display medium that can suppress a decrease in saturation and display a clear color.

  Application of an electric field to the dispersion medium sealed between a pair of substrates constituting the display medium is performed by arranging electrodes fixed to the display medium or external electrodes separate from the display medium on both sides of the display medium. It is also possible to do. Since it can be used simply by connecting to an external power source, the electrodes used for applying the electric field to the dispersion medium are preferably arranged on the side of the pair of substrates facing each other, in particular, the transparent substrate of the back substrate It is preferable that a back electrode is provided on the side surface and a transparent electrode is provided on the surface opposite to the display surface of the transparent substrate.

In the display medium of the second aspect of the present invention, since the dispersion medium contains two or more types of charge transfer particles, one of which is non-color-forming charge transfer particles, More than one kind of chromogenic charge transfer particles are included.
In this case, other charge-transfer particles (that is, color-chargeable charge-transfer particles) excluding non-color-formable charge-transfer particles are colored in different colors while being dispersed in the dispersion medium. It is preferable that the absolute value of the threshold value of the electric field for electrophoresis is composed of two or more kinds of color-forming charge-transfer particles that are different from each other. Thereby, color display can be performed.
Further, from the viewpoint that practical color display is possible, the above-described two or more color-forming charge-transfer particles are color-developing charge-transfer particles that develop a red color when dispersed in a dispersion medium. And color-forming charge-transfer particles that develop a green color, and color-form charge-transfer particles that develop a blue color.

On the other hand, a practical color display is performed when a cell in which a dispersion medium containing two kinds of charge transfer particles is enclosed is provided in the gap between the transparent substrate and the rear substrate by providing a partition wall that partitions the gap. In some cases, the cell is a cell (R cell) in which a dispersion medium containing non-color-forming charge-transfer particles and color-forming charge-transfer particles that develop a red color when dispersed in the dispersion medium is encapsulated, non-color development A cell (G cell) in which a dispersion medium containing color-forming charge-transfer particles and green-colored charge-transfer particles that are colored in a dispersed state are encapsulated, and non-color-chargeable charge-transfer particles; It is particularly preferable that the cell is composed of three types of cells (B cells) in which a dispersion medium containing color-forming charge transfer particles that develop blue color when dispersed in a dispersion medium is enclosed.
In this case, color display control can be performed using three cells including R cells, G cells, and B cells as one pixel. These three cells are arranged adjacent to or close to each other.

-Charge transfer particles-
Next, the charge transfer particles used in the second present invention will be described. The charge-transfer particles used in the second aspect of the present invention have the property of being charged to either positive or negative polarity so that they can move in the dispersion medium along the electric field gradient direction when placed in an electric field. In addition, two or more kinds of charge transfer particles having different absolute values of the threshold value of the electric field for electrophoresis in the dispersion medium are contained in the dispersion medium.
Here, among the two or more types of charge transfer particles contained in the dispersion medium, the charge transfer particles having the smallest absolute value of the threshold value of the electric field are only on the transparent substrate surface side in the dispersion medium. When present, the display surface is a non-color-forming charge-transfer particle having a background color, and other charge-transfer particles excluding the non-color-forming charge-transfer particle are colored in a state of being dispersed in a dispersion medium. It is a chromogenic charge transfer particle.
The two or more types of charge transfer particles used in the second present invention require that all types of charge transfer particles are charged with the same polarity. In addition, when the dispersion medium sealed between the pair of substrates is divided into a plurality of cells by the partition walls, the polarity of the charge transfer particles may be at least the same for each cell.
Hereinafter, the charge transfer particles used in the second aspect of the present invention will be described in more detail by dividing them into non-color-forming charge transfer particles and color-forming charge transfer particles.

-Non-chromogenic charge transfer particles-
Non-chromogenic charge-transfer particles suppress the increase in density of the chromogenic charge-transfer particles existing on the side of the light control layer of the transparent substrate, suppress the decrease in saturation, and display a clear color It has the same function as the void-forming particles used in the first aspect of the present invention.
However, the non-chromogenic charge transfer particles are not arranged in a state of being fixed to the side of the light control layer of the transparent substrate like the void-forming particles, but are electrophoresed in the dispersion medium. Further, the non-chromogenic charge transfer particles are composed of a material whose display surface can show a background color when only the particles are present on the surface of the transparent substrate in the dispersion medium.

In the second aspect of the present invention, the “background color” is displayed when all the color-forming charge-moving particles having a different color from the color-forming charge-moving particles have moved to the back substrate side. Means the same color as the color to be printed.
Therefore, for example, as the chromogenic charge transfer particles, three kinds of chromogenic charge transfer particles that color red, green, and blue when dispersed in a dispersion medium are used, and a white color is formed between a pair of substrates. When the reflective member is arranged, transparent or white particles are used as the non-color-forming charge transfer particles. As the chromogenic charge transfer particles, three kinds of chromogenic charge transfer particles that develop red, green, and blue colors when dispersed in a dispersion medium are used, and a sepia reflective member is provided between a pair of substrates. When arranged, the non-chromogenic charge transfer particles are transparent or sepia. As the non-color-forming charge transfer particles, it is usually preferable to use transparent or white particles.

When non-color-forming charge transfer particles are present on the transparent substrate surface, it is necessary to have a gap that leads from the surface opposite to the display surface of the transparent substrate to the back substrate side.
This gap size is determined when (1) the non-color-forming charge-transfer particles are discretely present on the side of the light control layer of the transparent substrate after the non-color-forming charge-transfer particles move to the transparent substrate surface. Can be adjusted mainly by selecting the content of the non-chromogenic charge transfer particles contained in the dispersion medium, and (2) the non-chromic charge transfer particles are on the side of the light control layer of the transparent substrate. In the case where it is laminated, it can be controlled mainly by adjusting the ratio of the particle size of the color-forming charge transfer particles to the particle size of the non-color-forming charge transfer particles.

The average particle diameter of the non-chromogenic charge transfer particles is not particularly limited, but particularly in the case shown in the above item (2), all kinds of color development are possible from the viewpoint that a clear color can be displayed with a high display density. The average particle diameter of the conductive charge transfer particles is preferably in the range of 1 to 10 times, and more preferably in the range of 1 to 5 times. When the average particle size of the non-chromogenic charge transfer particles is less than 1 times the average particle size of all types of color transfer charge transfer particles, the color developable charge transfer particles are laminated on the transparent electrode surface In this case, it is difficult to move through the gap between the non-color-developing charge transfer particles adjacent to each other and move to the surface of the transparent substrate, and it may not be possible to display a high display density.
Further, when the average particle size of the non-color-forming charge-transfer particles exceeds 10 times the average particle size of all types of color-transferable charge-transfer particles, the non-color development adjacent to each other in a state of being laminated on the transparent electrode surface The density of the chromogenic charge transfer particles existing on the transparent substrate surface when the chromogenic charge transfer particles move to the transparent substrate surface because the gap between the volatile charge transfer particles becomes too large. , The reduction in saturation cannot be suppressed, and a clear color may not be displayed.

  The ratio of the volume of the non-chromogenic charge transfer particles to the volume of all kinds of the color transfer charge transfer particles is preferably in the range of 1: 2 to 2: 1. More preferably, it is in the range of 5-1.5: 1. When the ratio of the volume of the non-chromogenic charge transfer particles to the volume of all types of the chromogenic charge transfer particles is smaller than 1: 2, the excessive chromogenic charge transfer particles become non-chromogenic. Aggregation may occur in the vicinity of the charge transfer particles, and the saturation of the display color may decrease. Conversely, when the ratio of the volume of the non-chromogenic charge transfer particles to the volume of all types of the chromogenic charge transfer particles is greater than 2: 1, the non-chromogenic charge transfer particles near the transparent substrate surface The amount of water increases, and the concentration is not sufficient.

The average particle diameter of the non-chromogenic charge transfer particles is determined by observing the non-chromogenic charge transfer particles used in the display medium with an electron microscope (SEM) or a transmission electron microscope (TEM), It calculated | required as an average value of the particle size calculated | required from the area of 100 particle | grains based on the TEM image. The average particle size of all kinds of color-forming charge transfer particles can be determined in the same manner as in the first aspect of the present invention.
On the other hand, the volume of the non-chromogenic charge transfer particles is obtained by calculating the volume per particle from the average particle size obtained by the above-mentioned procedure, and multiplying this by the number of particles per unit area existing on the transparent electrode surface. Asked. The volume of all types of color-forming charge transfer particles can be determined in the same manner as in the first aspect of the present invention.
Here, when the dispersion medium encapsulated between the pair of substrates is divided into a plurality of cells by the partition walls, the average particle diameter of the non-color-forming charge-transfer particles and all kinds of color-transfer charge-transfer particles, etc. The parameter value relating to the shape and size of the particles means a value obtained in cell units.

Next, materials constituting the non-color-forming charge transfer particles, suitable optical characteristics, and the like will be described. The material constituting the non-color-forming charge transfer particles, suitable optical characteristics, and the like can be basically the same as those of the void forming member used in the first aspect of the present invention.
However, the non-chromogenic charge transfer particles must have an absolute value of the threshold value of the electric field smaller than the absolute value of the threshold value of any electric field of all types of charge transfer particles included in the dispersion medium. Therefore, in order to adjust the absolute value of the threshold value of the electric field so as to satisfy this relationship, it is preferable to adjust the particle diameter or perform surface treatment as necessary in consideration of this point.

In addition, the mobility of the non-color-forming charge-transfer particles is not particularly limited, but the mobility of the non-color-forming charge-transfer particles is other than that of the non-color-forming charge-transfer particles. It is preferable that the mobility is equal to or higher than the mobility of the charge mobility particles having the greatest mobility (that is, the color developing charge mobility particles having the greatest mobility).
If the mobility of the non-chromogenic charge mobility particles is slower than the mobility of the chromogenic charge mobility particles having the greatest mobility, the chromogenic charge mobility having the greatest mobility on the back substrate side In the presence of particles and non-chromogenic charge-transfer particles, an electric field that allows the chromophoric charge-transfer particles having the greatest mobility and the non-chromogenic charge-transfer particles to move simultaneously toward the transparent substrate. Is applied, the color developing charge-transfer particles having the highest mobility reach the transparent substrate side earlier than the non-color-forming charge transfer particles, so that the saturation is lowered. In some cases, clear colors cannot be displayed.
Therefore, the mobility of the non-chromogenic charge transfer particles is preferably at least 1.5 times that of the chromogenic charge transfer particles having the highest mobility, and preferably at least 2 times. Is more preferable. The upper limit of the mobility of the non-color-forming charge-transfer particles is not particularly limited, but is practically 10 times or less the mobility of the color-forming charge-transfer particles having the highest mobility. It is preferable.

  The mobility can be achieved by applying an electric field between parallel plate electrode substrates and measuring the time required for the particles to move. A pair of platinum electrode substrates with smooth surfaces are immersed in a transparent container (for example, a zeta potential measurement cell) with a 1 mm spacer facing each other, and 10 V (that is, an electric field of 100 V / cm) is applied between the electrodes. By repeatedly applying the polarities alternately, the movement of particles is observed from a direction parallel to the electrode surface. The movement of the particles can be observed by moving the concentration peak of the particle color. Alternatively, it can be measured by a zeta electrometer that can measure mobility.

-Color developing charge transfer particles-
As the color-forming charge transfer particles used in the second invention, basically the same ones as those used in the first invention can be used. However, all kinds of color-forming charge transfer particles can be adjusted so that the absolute value of any electric field threshold value is larger than the absolute value of the electric field threshold value of non-color-generating charge transfer particles. is necessary.

-Reflective member-
As the reflecting member used in the second aspect of the present invention, basically the same reflective member as that used in the first aspect of the present invention can be used.
However, the reflecting member used in the second aspect of the present invention has not only all kinds of color-forming charge-transfer particles, but also non-color-forming charge-transfer particles having a gap that moves between the transparent substrate side and the back substrate side. What you have is used.
In the second aspect of the present invention, the non-color-forming charge transfer particles have an average particle size basically equal to or greater than the average particle size of all types of color-transfer charge transfer particles as described above. Therefore, the reflecting member used in the second aspect of the present invention may use a member having a gap in which the non-color-forming charge-transfer particles move between the transparent substrate side and the back substrate side. Particularly preferred.

  Here, when the reflecting member is a porous body, the average pore diameter thereof is preferably in the range of more than 20 times and not more than 1000 times the average particle diameter of all kinds of color-forming charge transfer particles, More preferably, it is in the range of more than 200 times and 200 times or less.

  Further, when the reflecting member is a particulate member, the average particle size thereof is preferably in the range of more than 25 times the average particle size of all kinds of color-forming charge transfer particles and not more than 1000 times, More preferably, it is in the range of 100 times to 500 times. For example, if the average particle diameter of all kinds of color-forming charge transfer particles is 50 nm, the average particle diameter of the particulate reflecting member can be set to a range of about 100 to 500 times, for example.

-Other members, display medium manufacturing method, display device-
As other members such as a dispersion medium, a substrate, and an electrode used in the second invention, the same materials as those in the first invention can be used.
The method for producing the display medium of the second aspect of the present invention is not particularly limited, but for example, it can be produced by the following process. First, a transparent substrate and a back substrate are prepared as a pair of substrates. As these substrates, electrodes may be provided in advance. Then, after forming a partition in the surface by the side of either one of a transparent substrate or a back substrate, both are bonded together. Note that when bonding, a reflective member may be disposed between the pair of substrates in advance if necessary. Subsequently, a display medium can be obtained by injecting a dispersion medium containing two or more kinds of charge transfer particles from a dispersion medium injection port provided in advance when the partition wall is formed and sealing the injection port.
Similarly to the first invention, when the display medium of the second invention incorporates a pair of electrodes at a position where an electric field can be applied to the dispersion medium sealed between the pair of substrates, A display device that is connected to the pair of electrodes and further includes an electric field applying unit that applies an electric field to the dispersion medium can be used.

-Specific examples of display media (display devices)-
Next, specific examples of the display medium of the second aspect of the present invention will be described. As a specific example of the display medium of the second aspect of the present invention, for example, in the display medium of the first aspect of the present invention illustrated in FIGS. In which the charge transfer particles are replaced.
However, in this case, in FIG. 1 to FIG. 7 and FIG. 9, when color-forming charge-transfer particles are present on the back electrode surface, the non-color-forming charge-transfer particles indicated by reference numeral 400 are also on the back electrode surface. In addition, the color-forming charge transfer particles present on the back electrode surface are present on the back electrode surface in a more dispersed and low-density state.

  Further, in FIG. 8, there is further shown a graph of change in electric field intensity-display density of non-color-forming charge-transferable particles having two electric field threshold values in the range exceeding electric field threshold value −E1 and less than E1. Become. Note that the non-color-forming charge-transfer particles are basically white or transparent, and thus the display density with respect to the electric field strength of the non-color-forming charge-transfer particles may not be grasped. In this case, it is approximated not as a display density but as a ratio of the number of non-chromogenic charge transfer particles present on the transparent substrate side or the back substrate side to the total non-chromogenic charge transfer particles contained in the dispersion medium. Can think.

Next, specific examples of the display medium of the second aspect of the present invention will be described in more detail with reference to the drawings.
FIG. 10 is a schematic diagram showing an example of the display medium according to the second aspect of the present invention, and FIG. 10 (A) shows a state where the first display switching step or the second display switching step has been carried out, FIG. 10B shows a state where the third display switching process has been completed. Here, in the figure, 120 represents a display medium, 410 represents a non-color-forming charge transfer particle, and members indicated by other reference numerals have the same functions as those shown in FIG.
The display medium 120 shown in FIG. 10 is a non-chromogenic charge mobility that performs electrophoresis instead of the void-forming particles 400 arranged in a state of being fixed to the surface of the transparent electrode 210 in the display medium 106 shown in FIG. There is a feature in using the particle 410.

  A display operation of the display medium 106 illustrated in FIG. 10 will be described. First, in the state shown in FIG. 10B, the transparent electrode 210 side is added to the transparent electrode 210 side so that an electric field strength larger than the absolute value of the electric field threshold value of the color-forming charge transfer particles 300 is applied to the dispersion medium. Since a negative voltage is applied to the electrode 220 side, the color-forming charge-transfer particles 300 and the non-color-forming charge-transfer particles 410 are present on the back substrate 204 side. When the display medium 120 is observed from the display surface 202 side in this state, the red color-forming charge-transfer particles 300 are concealed by the reflecting member 602 made of white particles, so that white is displayed on the display surface 202. It will be.

  10B, a negative voltage is applied to the transparent electrode 210 side and a positive voltage is applied to the back electrode 220 side. In this case, the non-color-forming charge-moving particles 410 having a smaller absolute value of the electric field threshold value first move from the back substrate 204 side to the transparent substrate 200 side. Therefore, a voltage is applied so as to exceed the absolute value of the threshold value of the electric field of the color-forming charge transfer particles 300, and the color development charge-transfer particles 300 start moving from the back substrate 204 side to the transparent substrate 200 side. At that time, the non-color-developing charge transfer particles 410 are already laminated on the surface of the transparent substrate 200 or have been moved to the vicinity of the surface of the transparent substrate 200.

  Therefore, when the color-forming charge-transfer particles 300 reach the surface of the transparent substrate 200 from the back substrate 204 side, the color-forming charge-transfer particles 300 are not laminated on the surface of the transparent substrate 200. The charge transfer particles 410 move to the surface of the transparent substrate 200 through the gaps between the charge transfer particles 410 or get caught in the gaps between the non-color-forming charge transfer particles 410. Therefore, the color-forming charge transfer particles 300 are dispersed on the surface of the transparent electrode 210 and exist at a low density. In this state, a clear red color is displayed on the display surface 202 of the display medium 120 (FIG. 10A).

  Note that when the state shown in FIG. 10B shifts to the state shown in FIG. 10A, the electric field strength is less than the absolute value of the threshold value of the electric field of the color-forming charge-transferable particles 300 and is not The first step of applying a first electric field strength that is equal to or greater than the absolute value of the electric field threshold value of the chromogenic charge transfer particle 410, and the absolute value of the electric field threshold value of the chromogenic charge transfer particle 300 after the first step. The second step of applying the second electric field strength that is greater than or equal to the value may be performed sequentially, or only the second step may be performed. However, when only the second step is performed, the chromogenic charge transfer is performed so that the mobility of the chromogenic charge transfer particles 300 is slower than the mobility of the non-chromogenic charge transfer particles 410. It is necessary to select the luminescent particles 300 and the non-chromogenic charge transfer particles 410. When the mobility of the color-forming charge-transfer particles 300 is faster than the mobility of the non-color-forming charge-transfer particles 410, the color-forming charge-transfer particles 300 have finished moving to the transparent substrate 200 side. This is because the non-color-developing charge transfer particles 410 later move to the transparent substrate 200 side, and a clear red color may not be displayed.

(Third invention)
In the display method of the second aspect of the present invention, a surface of the transparent substrate in which one surface constitutes a display surface and the transparent electrode is disposed on the surface opposite to the display surface is disposed on the surface on which the transparent electrode is disposed. A light control layer including one or more chromogenic charge transfer particles that are included in the dispersion medium and color in a state of being dispersed in the dispersion medium is disposed, and the transparent electrode is discretely formed on the surface of the transparent substrate. It is arranged on the surface opposite to the display surface of the transparent electrode in at least any one mode selected from a mode of being arranged and a mode of being arranged so as to discretely expose the surface of the transparent substrate. (1) when one or more of all kinds of color-forming charge transfer particles are present at a position away from the surface of the transparent substrate on which the transparent electrode is disposed, the transparent substrate Present at a position away from the surface on which the transparent electrode is disposed Using at least the transparent electrode, an electric field for moving at least one color-forming charge-transfer particle selected from one or more color-forming charge-transfer particles to the transparent electrode side through the dispersion medium. A first display switching step of switching the display state of the display surface by applying to the light control layer, and (2) one or more types of all kinds of color-forming charge-transfer particles, When present on the surface of the transparent electrode, at least one type of chromogenic charge transporting particle selected from one or more chromogenic charge transporting particles present on the transparent electrode surface is added to the transparent substrate. By applying an electric field that moves in the dispersion medium in a direction away from the surface opposite to the display surface to the light control layer using at least the transparent electrode, the display state of the display surface is changed. Switch And second display switching step, characterized in that the at least (Note that in this display method, the first display change step and the second display switching step can be performed in any order).

The display medium of the third aspect of the present invention is not particularly limited as long as it has a configuration capable of performing display using the display method of the third aspect of the present invention. Specifically, the display medium has the following configuration. It is particularly preferable that the display medium has.
That is, the display medium of the third aspect of the present invention includes a transparent substrate having one surface constituting the display surface, a transparent electrode disposed on the surface of the transparent substrate opposite to the display surface, and the transparent substrate. A back substrate disposed opposite to the surface opposite to the display surface, a dispersion medium sealed in a gap between the transparent substrate and the back substrate, and a state of being contained in the dispersion medium and dispersed in the dispersion medium At least one color-developing charge-transferable particle that develops color, wherein the transparent electrode is discretely disposed on the surface of the transparent substrate, and the surface of the transparent substrate is discretely exposed. It is particularly preferable that the transparent electrode is disposed on the surface opposite to the display surface in at least one of the modes selected from the above-described modes.

In the third aspect of the present invention, the transparent electrode is at least one selected from an aspect in which the transparent electrode is discretely arranged on the surface of the transparent substrate and an aspect in which the transparent substrate surface is arranged to be discretely exposed. It arrange | positions in the light control layer side surface of a transparent substrate in the aspect of this. In this case, when an electric field that moves the color-forming charge-transfer particles to the transparent substrate is applied, the color-forming charge-transfer particles cannot be present at any position on the transparent substrate surface. Are dispersed on the surface of the transparent electrode arranged so as to partially cover the surface.
Therefore, it is possible to prevent an increase in the density of the color-forming charge transfer particles present on the side of the light control layer of the transparent substrate to the extent that the saturation of the displayed color does not decrease. Therefore, according to the third aspect of the present invention, it is possible to provide a display method and a display medium that can display a clear color while suppressing a decrease in saturation.

  In the third aspect of the present invention, the electrode paired with the transparent electrode can be implemented by disposing an external electrode different from the display medium, but can be used simply by connecting to an external power source. The electrode (back electrode) paired with the transparent electrode is also preferably disposed on the surface of the back substrate on the side where the transparent substrate is disposed.

In the third aspect of the present invention, the transparent electrode suppresses an increase in the density of the color-forming charge transfer particles present on the side of the light control layer of the transparent substrate, suppresses a decrease in saturation, and displays a clear color. This point has the same function as the void-forming particles used in the first aspect of the present invention.
That is, according to the third aspect of the present invention, the function of the void-forming particles used in the first aspect of the present invention is basically the same as that of the first embodiment of the present invention. The function other than the transparent electrode can be the same as that of the first aspect of the present invention, and the same applies to the display device.
However, when the void-forming particles used in the first aspect of the present invention are colored in white or other colors, there is an effect of concealing the color of the color-forming charge transfer particles that have moved to the back substrate side. However, the transparent electrode used in the third aspect of the present invention cannot provide this concealing effect. For this reason, in the third aspect of the present invention, it is basically preferable to use a reflecting member.

-Transparent electrode-
Next, the transparent electrode used in the third aspect of the present invention will be described. As the transparent electrode used in the third aspect of the present invention, the same electrode as in the first aspect of the present invention can be used.
However, the transparent electrode used in the third aspect of the present invention is not "covers the surface of the transparent substrate substantially without a gap" like the transparent electrode used in the first aspect of the present invention or the second aspect of the present invention, Dimming of the transparent substrate in at least one of the modes selected from “a mode in which the transparent substrate surface is discretely arranged” and “a mode in which the transparent substrate surface is discretely exposed” It needs to be placed on the side of the layer.

  Here, the “mode discretely arranged on the surface of the transparent substrate” means that the area of the surface of the transparent substrate is equivalent to a size corresponding to one pixel (usually a size of about 64 × 64 μm to 10000 × 1000 μm). It means that a plurality of transparent electrodes having a size of 1/10 or less in the ratio are arranged in a separated state. The size of each of these transparent electrodes is not particularly limited as long as a decrease in saturation can be suppressed and a clear color can be displayed. However, the size of each transparent electrode is preferably in the range of 10 to 50 μm, and more preferably in the range of 20 to 30 μm, in terms of the average diameter in terms of area. When the average diameter of each transparent electrode is less than 10 μm, a sufficient display density may not be obtained. When the average diameter of each transparent electrode exceeds 50 μm, the saturation is lowered and clear. The color may not be displayed.

Moreover, it is particularly preferable that the sizes and shapes of the individual transparent electrodes are the same, and the arrangement thereof may be regular or irregular. On the other hand, the density per unit area of each transparent electrode is not particularly limited, but the area ratio of the transparent electrode per unit area is preferably within a range of 20% to 80%, and is preferably 50% to 60%. More preferably within the range. If the area ratio of the transparent electrode per unit area is less than 20%, sufficient display density may not be obtained. If it exceeds 80%, the transparent electrodes are discretely arranged on the surface of the transparent substrate itself. May become difficult, and the saturation may be lowered, making it impossible to display a clear color.
When an electric field is applied to the dispersion medium, voltages having the same polarity and potential are applied to all the transparent electrodes arranged on the surface of the transparent substrate. However, in the case where the dispersion medium sealed between the pair of substrates is divided into a plurality of cells by the partition walls, it is sufficient that voltages having the same polarity and potential are applied to the individual transparent electrodes in each cell unit.

Next, an example in which the transparent electrode is arranged on the surface of the transparent substrate in a “mode in which the transparent electrode is discretely arranged on the surface of the transparent substrate” will be described with reference to the drawings.
FIG. 11 is a plan view showing an example of the transparent electrode used in the third aspect of the present invention, and shows a state where a plurality of transparent electrodes are arranged on the surface of the transparent substrate. Here, in the figure, 212 represents a transparent electrode, and the area other than the region indicated by reference numeral 212 means a surface made of a transparent substrate. In the example shown in FIG. 11, transparent electrodes 212 having a circular shape and the same size are arranged in a staggered pattern on the surface of the transparent substrate. The plurality of transparent electrodes 212 are connected to the electric field applying means by wires (not shown) arranged in the thickness direction of the transparent substrate, and the same polarity and the same potential voltage are applied to all the transparent electrodes 212. It can be done.

On the other hand, “a mode in which the surface of the transparent substrate is arranged to be discretely exposed” means that the surface of the transparent substrate has a size corresponding to one pixel (usually a size of about 64 × 64 μm to 1000 × 1000 μm). This means that areas not covered with a plurality of transparent electrodes having an area ratio of 1/10 or less (hereinafter referred to as “exposed portions”) are arranged in a state of being separated from each other. Here, the shortest distance between the contour lines of two adjacent exposed portions is preferably within a range of 10 to 50 μm, and more preferably within a range of 20 to 30 μm.
When the shortest distance between the contour lines of two adjacent exposed portions is less than 10 μm, sufficient display density may not be obtained, and when the shortest distance between the contour lines of two adjacent exposed portions exceeds 50 μm In some cases, the saturation is lowered and a clear color cannot be displayed.

  Moreover, it is particularly preferable that the size and shape of each exposed portion are the same, and the arrangement thereof may be regular or irregular. On the other hand, the existence density per unit area of each exposed portion is not particularly limited, but the area ratio of the exposed portion per unit area is preferably within a range of 20% to 80%, and 40% to 50%. It is more preferable to be within the range. When the area ratio of the exposed portion per unit area is less than 20%, the ratio of the transparent electrode becomes too large, and the saturation may be lowered and a vivid color may not be displayed. In some cases, sufficient display density cannot be obtained.

  Next, an example where the transparent electrode is arranged on the surface of the transparent substrate in the “mode of being arranged so as to discretely expose the surface of the transparent substrate” will be described with reference to the drawings. FIG. 12 is a plan view showing another example of the transparent electrode used in the third aspect of the present invention, and shows a state where a transparent electrode having a plurality of exposed portions is arranged on the surface of the transparent substrate. Here, in the drawing, 214 represents a transparent electrode, and 216 represents an exposed portion (a surface made of a transparent substrate). In the example shown in FIG. 12, the exposed portions 216 having a square shape and the same size are provided in a square arrangement on the transparent substrate surface, while the transparent electrodes 214 are arranged in a lattice pattern.

  The method for forming the transparent electrode on the surface of the transparent substrate in a “mode in which the transparent substrate surface is discretely arranged” or “a mode in which the transparent substrate surface is discretely exposed” is particularly limited. Although a known method can be used, it is preferable to use a method of patterning using photolithography and etching after once forming a solid film-like transparent electrode on the surface of the transparent substrate.

-Specific examples of display media (display devices)-
Next, a specific example of the display medium of the third aspect of the present invention will be described. As a specific example of the display medium of the third aspect of the present invention, for example, in the display medium of the first aspect of the present invention illustrated in FIGS. Examples of the transparent electrode 210 include those arranged on the surface of the transparent substrate 200 in the pattern shown in FIGS. 11 and 12, for example.

  EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited only to the examples shown below.

<Preparation of chromogenic charge transfer particles A>
In a 100 ml flask, 2.0 × 10 ⁻⁵ mol of chloroauric acid and 20 mL of silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd., KF-96) were sampled and dispersed by stirring using a magnetic stirrer.
1.7 × 10 ⁻² mol of Octadecyltrimethylsilane was added, and 9.0 × 10 ⁻⁴ mol of 3-Aminopropyltrioxysilane was added. Further, 4.0 × 10 ⁻⁴ mol of ascorbic acid was added as a reducing agent and stirred using a magnetic stirrer to obtain a red gold colloid dispersion.
The resulting dispersion was decanted with silicone oil (KF-96, manufactured by Shin-Etsu Chemical Co., Ltd.) five times to obtain chromogenic charge transfer particles A.
The average particle diameter D2 of the electrophoretic colored particles was 50 nm.

<Void forming particle A>
As the void-forming particles A, a silica dispersion (Mortex Corp. 8050, refractive index 1.40, average particle size 500 nm) was used.

<Void forming particle B>
As the void forming particles B, polystyrene particles (3495A manufactured by Moritex Corporation, average particle size of 500 nm) were used.

<Void forming particle C>
Silicon alkoxide particles (Ube Nitto Kasei UNK High Precisiona SP fine particles, average particle size 500 nm, refractive index 1.45) were used as the void forming particles C.

<Void forming particle D>
As the void forming particles D, PTFE fine particles (manufactured by Shamrock Technologies, average particle size of 500 nm, refractive index of 1.35) were used.

<Void forming particles E>
As the void-forming particles E, PMMA fine particles (manufactured by Bangs Laboratories, microsphere PMMA fine particles PP03N, average particle size 500 nm, refractive index 1.49) were used.

<Void forming particles F>
As the void-forming particles F, sodium fluoride fine particles (Morita Chemical Co., Ltd., average particle diameter of 500 nm, refractive index of 1.32) were used.

<Void forming member (porous body A)>
As the void-forming member (porous body A), porous polyethylene (manufactured by Nitto Denko Corporation, average pore diameter 17 μm) was used.

<Preparation of non-chromogenic charge transfer particles A>
A mixture of 90 parts by weight of styrene monomer and 1 part by weight of azoisobutyronitrile was subjected to ball milling using 10 mmφ zirconia balls for 20 hours to obtain dispersion A-1.
A mixture consisting of 30 parts by weight of calcium carbonate and 70 parts by weight of water was subjected to the same operation as dispersion A-1, to obtain dispersion A-2.
After 18 parts by weight of dispersion A-2 and 50 parts by weight of 20% saline were stirred and mixed, 30 parts by weight of dispersion A-1 was added and emulsified to obtain emulsion A-3.
The obtained emulsion A-3 was heated to 70 ° C. under a nitrogen stream and stirred for 20 hours to obtain solid particles A-4. After 15 parts by weight of 35% hydrochloric acid was added to the obtained solid particles A-4 and stirred to dissolve calcium carbonate, suction filtration and water washing were repeated 5 times to obtain transparent particles A-5.
The obtained transparent particles A-5 were mixed with methyl hydrogen silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd., KF-99) and stirred for hydrophobic treatment to obtain non-chromogenic charge transfer particles A. .
The non-color-forming charge transfer particles A had an average particle diameter D1 of 250 nm and a refractive index n1 of 1.40.

<Preparation of non-chromogenic charge transfer particles B>
A mixture of 90 parts by weight of a styrene monomer, 9 parts by weight of a white pigment (manufactured by Ishihara Sangyo Co., Ltd., TIPEQUE) and 1 part by weight of azoisobutyronitrile was subjected to ball milling using 10 mmφ zirconia balls for 20 hours to obtain a dispersion. A-1 was obtained.
A mixture consisting of 30 parts by weight of calcium carbonate and 70 parts by weight of water was subjected to the same operation as dispersion A-1, to obtain dispersion A-2.
After 18 parts by weight of dispersion A-2 and 50 parts by weight of 20% saline were stirred and mixed, 30 parts by weight of dispersion A-1 was added and emulsified to obtain emulsion A-3.
The obtained emulsion A-3 was heated to 70 ° C. under a nitrogen stream and stirred for 20 hours to obtain solid particles A-4. After 15 parts by weight of 35% hydrochloric acid was added to the obtained solid particles A-4 and stirred to dissolve calcium carbonate, suction filtration and water washing were repeated 5 times to obtain white particles A-5.
The obtained white particles A-5 were mixed with methyl hydrogen silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd., KF-99) and stirred for hydrophobic treatment to obtain non-chromogenic charge transfer particles B. .
The non-chromogenic charge transfer particles had an average particle diameter D1 of 250 nm and a refractive index n1 of 1.49.

<Preparation of particulate reflective member A>
A mixture of 80 parts by weight of methyl methacrylate monomer, 17 parts by weight of titanium oxide (manufactured by Ishihara Sangyo Co., Ltd., Taipei CR63), and 3 parts by weight of hollow particles (manufactured by JSR, SX866 (A)) is used as a zirconia ball having a diameter of 10 mm. Ball milling was performed for 20 hours to obtain dispersion B-1.
A mixture consisting of 40 parts by weight of calcium carbonate and 60 parts by weight of water was subjected to the same operation as dispersion B-1, to obtain dispersion B-2.
8.5 parts by weight of dispersion B-2 and 50 parts by weight of 20% brine were stirred and mixed to obtain mixture B-3.
After mixing 35 parts by weight of dispersion B-1 with 1 part by weight of ethylene glycol dimethacrylate and 0.35 parts by weight of azoisobutyronitrile, the mixture B-3 was added to emulsify, and emulsion B -4 was obtained.
The obtained emulsion B-4 was heated to 65 ° C. under a nitrogen stream and stirred for 15 hours to obtain solid particles B-5.
After 15 parts by weight of 35% hydrochloric acid was added to the obtained solid particles B-5 and stirred to dissolve calcium carbonate, suction filtration and washing with water were repeated 5 times to obtain white particles B-6. The obtained white particles B-6 were classified by sieving to obtain white particles (particulate reflecting member A) having an average particle diameter of 5 μm.

(Example A1)
A display medium having the configuration shown in FIG. 4 was produced by the following procedure.
First, an ITO film having a thickness of 50 nm was formed as a transparent electrode on one side of a transparent substrate made of glass of 50 mm × 50 mm and a thickness of 0.7 mm by a sputtering method.
Next, an ethanol solution in which void-forming particles A are dispersed is applied to the surface of the transparent substrate on the transparent electrode side (in the area surrounded by the partition walls), and then heated at 250 ° C. for 30 minutes to obtain a thickness. A layer made of void-forming particles A having a diameter of 1 μm was formed. In addition, when the cross section and the surface of this layer were observed by SEM, the particle and the surface of the transparent electrode and the particles were heat-sealed, but the shape of each particle was maintained with almost no collapse. It was found that the particle size was the same as before heat fusion treatment.

  On the other hand, copper having a film thickness of 60 nm was formed as a back electrode on one side of a back substrate made of alumina ceramics having a size of 50 mm × 50 mm and a thickness of 0.7 mm by a sputtering method. Subsequently, after applying an epoxy resin (SU-8 manufactured by MicroChem Corp.) to the surface of the back substrate on which the back electrode is provided, exposure and wet etching are performed to increase the height along the outer periphery of the back substrate. A partition wall having a thickness of 50 μm and a width of 20 μm was formed.

  Subsequently, after applying and forming a heat-fusible epoxy adhesive on the upper part of the partition wall, the part partitioned by the partition wall on the back substrate is uniformly filled with the particulate reflective member A, and the electrophoretic colored particles A A dispersion (solid content: 8% by volume) dispersed in silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd., KF-96, refractive index n2 = 1.40) was filled up to the height of the partition walls.

  Finally, the surface of the transparent substrate on which the transparent electrode is provided, the partition provided on the rear substrate, and the transparent substrate and the transparent substrate are adhered to each other so that air does not enter between the transparent substrate and the transparent substrate. A medium was made.

Using the display medium thus produced, the display medium was observed from the side of the display medium on which the transparent substrate was provided, and display characteristics such as saturation, display density, and whiteness were confirmed as follows.
First, a voltage of 15 V was applied to both electrodes so that the transparent electrode side of the display medium immediately after assembly was negative. At this time, since the color-forming charge-transfer particles dispersed in the light control layer were positively charged, the movement to the negative electrode was observed by voltage application, and the display color of the display medium became red ( FIG. 4 (A)). Next, when a voltage of 15 V was applied to both electrodes so that the transparent electrode side became positive, the color-forming charge-transfer particles moved to the back electrode side, and the color of the display medium changed to white (FIG. 4). (B)).
For the display at this time, voltage was applied until the display density was saturated, and the saturation and display density during red display and the whiteness during white display in the state where the display density was saturated were evaluated.

(Example A2)
A display medium was prepared in the same manner as in Example A1 except that the void forming particles B were used in place of the void forming particles A, and evaluated in the same manner.

(Example A3)
A display medium was produced in the same manner as in Example A1 except that the void forming particles C were used in place of the void forming particles A, and the display media were similarly evaluated.

(Example A4)
A display medium was produced in the same manner as in Example A1 except that the void-forming particles D were used instead of the void-forming particles A, and evaluated in the same manner.

(Example A5)
A display medium was produced in the same manner as in Example A1 except that the void-forming particles E were used in place of the void-forming particles A, and evaluated in the same manner.

(Example A6)
A display medium was produced in the same manner as in Example A1 except that the void-forming particles F were used instead of the void-forming particles A, and evaluated in the same manner.

(Example A7)
A display medium was prepared in the same manner as in Example A1, except that void-forming particles (silica dispersion (8000 series manufactured by Moritex Corp.) average particle diameter 350 nm, refractive index 1.40) were used instead of void-forming particles A. Were prepared and evaluated in the same manner.

(Example A8)
A display medium was prepared in the same manner as in Example A1, except that void-forming particles (silica dispersion (8000 series, manufactured by Moritex Corp.) average particle diameter 900 nm, refractive index 1.40) were used instead of void-forming particles A. Were prepared and evaluated in the same manner.

(Example A9)
A display medium was prepared in the same manner as in Example A1, except that void-forming particles (silica dispersion (8000 series, manufactured by Moritex Corp.) average particle diameter 150 nm, refractive index 1.40) were used instead of void-forming particles A. Were prepared and evaluated in the same manner.

(Example A10)
A display medium was prepared in the same manner as in Example A1, except that void-forming particles (silica dispersion (8000 series manufactured by Moritex Corp.) average particle diameter 1250 nm, refractive index 1.40) were used instead of void-forming particles A. Were prepared and evaluated in the same manner.

(Example A11)
A display medium was prepared in the same manner as in Example A1 except that a void-forming member (porous body A) was used instead of the void-forming particles A, and evaluated in the same manner.

(Comparative Example A1)
A display medium was produced and evaluated in the same manner as in Example A1 except that the gap forming member and the particulate reflective member A were not used.

-Evaluation-
The evaluation results of the saturation, display density, and whiteness of Examples A1 to A11 and Comparative Example A1 are shown in Table 1 below.

The evaluation methods and evaluation criteria for saturation, display density, and whiteness shown in Table 1 are as follows.
-Saturation-
The saturation value C * of L * C * h * was measured with X-Rite 939 manufactured by X-Rite. The evaluation criteria shown in Table 1 are as follows.
A: Saturation is 50 or more.
○: Saturation is 40 or more and less than 50.
Δ: Saturation of 30 or more and less than 40.
X: Saturation is less than 30.

−Display density−
The display density was determined from the reflection density at the time of red display measured by X-Rite 939 manufactured by X-Rite. The evaluation criteria shown in Table 1 are as follows.
A: Reflection density is 1.6 or more.
○: Reflection density is 1.3 or more and less than 1.6.
(Triangle | delta): Reflection density is 1.1 or more and less than 1.3.
X: Reflection density is less than 1.0.

-Whiteness-
The display density was determined from the reflection density during white display measured by X-Rite 939 manufactured by X-Rite. The evaluation criteria shown in Table 1 are as follows.
A: Reflection density is less than 0.35.
○: The reflection density is 0.35 or more and less than 0.4.
Δ: The reflection density is 0.4 or more and less than 0.45.
X: Reflection density is 0.45 or more.

(Example B1)
A display medium having the configuration shown in FIG. 10 was produced by the following procedure.
First, an ITO film having a thickness of 50 nm was formed as a transparent electrode on one side of a transparent substrate made of glass of 50 mm × 50 mm and a thickness of 0.7 mm by a sputtering method.

  On the other hand, copper was formed on one side of a back substrate made of alumina ceramic having a size of 50 mm × 50 mm and a thickness of 0.7 mm as a back electrode by a vacuum deposition method so as to have a film thickness of 60 nm. Subsequently, after applying an epoxy resin (SU-8 manufactured by MicroChem Corp.) to the surface of the back substrate on which the back electrode is provided, exposure and wet etching are performed to increase the height along the outer periphery of the back substrate. A partition wall having a thickness of 50 μm and a width of 20 μm was formed.

  Subsequently, after applying and forming a heat-fusible epoxy adhesive on the upper part of the partition wall, the part partitioned by the partition wall on the back substrate is uniformly filled with the particulate reflective member A, and the electrophoretic colored particles A Silicone oil (Shin-Etsu Chemical Co., Ltd.) is dispersed in silicone oil (Shin-Etsu Chemical Co., Ltd., KF-96, refractive index n2 = 1.40) in a dispersion (solid content 6% by volume) and non-chromogenic charge transfer particles A. A solution obtained by mixing a dispersion liquid (solid content: 6% by volume) dispersed in KF-96, manufactured by Kogyo Co., Ltd., with a refractive index of n2 = 1.40) at a volume ratio of 1: 1 was filled up to the height of the partition wall. .

  Finally, the surface of the transparent substrate on which the transparent electrode is provided, the partition provided on the rear substrate, and the transparent substrate and the transparent substrate are adhered to each other so that air does not enter between the transparent substrate and the transparent substrate. A medium was made.

  Using the display medium thus prepared, first, the electric field threshold value and mobility of the non-color-forming charge-transfer particles and the color-forming charge-transfer particles were confirmed by the following procedure.

-Measurement of electric field threshold-
First, a sufficient voltage is applied to a pair of electrodes to display white until the display density is sufficiently saturated (coloring charge-transferable particles and non-colorable charge-transferable particles are present on the copper electrode side) Then, a voltage that forms a potential gradient opposite to the case of displaying a white color on a pair of electrodes was applied while gradually increasing the voltage value.
At this time, a slight change in reflectance caused by the non-color-forming charge-transfer particles on the display surface of the display medium or a color change caused by the color-forming charge-transfer particles (change from white to red) ) Was observed with an optical microscope. When the potential difference between the two electrodes was 5 V, it was estimated that the non-chromogenic charge transfer particles moved from the copper electrode side to the transparent electrode side. A slight change in reflectance was confirmed, and when the potential difference between the two electrodes was 7.5 V, the color change on the display surface caused by the movement of the color-forming charge-transfer particles from the copper electrode side to the transparent electrode side ( (Change from white to red) was confirmed.
From these results and the distance between the pair of substrates constituting the display medium is 50 μm, the absolute value of the threshold value of the electric field of the non-color-forming charge transferable particles is 100 V / mm (= 5 V / 50 μm). The absolute value of the threshold value of the electric field of the chromogenic charge transfer particles was found to be 150 V / mm (= 7.5 V / 50 μm).

-Mobility measurement-
First, an evaluation in which a pair of platinum electrode substrates having a smooth surface are arranged in a transparent container (cell for measuring zeta potential) so as to face each other using a spacer so that the distance between them is 1 mm. A device was prepared. Subsequently, a transparent container is filled with a solution in which 3.0 parts by mass of non-chromogenic charge transfer particles are dispersed in 100 parts by mass of the dispersion medium used for producing the display medium, and a pair of platinum electrode substrates A voltage was applied so that the electric field strength formed therebetween was 100 V / cm, and non-chromogenic charge transfer particles were collected on one platinum electrode substrate surface. Next, with the same electric field strength, a voltage was applied so that a reverse potential gradient was formed, and the non-chromogenic charge transfer particles were moved to the surface of the other platinum electrode substrate. In this way, the state in which the non-chromogenic charge transfer particles are reciprocated between a pair of platinum electrode substrates is observed with an optical microscope, and the non-color development is performed from one platinum electrode substrate to the other platinum electrode substrate. It was 0.2 seconds when the time required for the conductive charge transferable particles to finish moving was measured. From this, it was found that the mobility of the non-chromogenic charge transfer particles was 5 mm / s (= 1 mm / 0.2 seconds).
Subsequently, from a platinum electrode substrate in the same manner as described above, a solution in which 3.0 parts by mass of color-forming charge transfer particles is dispersed with respect to 100 parts by mass of the dispersion medium used for producing the display medium. It took 0.5 seconds to measure the time required for the chromophoric charge transfer particles to finish moving to the other platinum electrode substrate. From this, it was found that the mobility of the color-forming charge transfer particles was 2 mm / s (= 1 mm / 0.5 second).

−Display test−
Subsequently, the display medium was observed from the side of the display medium on which the transparent substrate was provided, and display characteristics such as saturation, display density, and whiteness were confirmed as follows.
First, a voltage of 10 V was applied to both electrodes so that the transparent electrode side of the display medium was negative. At this time, since the non-color-forming charge-transfer particles and the color-forming charge-transfer particles dispersed in the light control layer were positively charged, the movement to the negative electrode was observed by applying a voltage, and the display medium Was displayed in red (FIG. 10A). Next, when a voltage of 10 V is applied to both electrodes so that the transparent electrode side becomes positive, the non-color-forming charge-moving particles and the color-forming charge-moving particles move to the back electrode side, and the color of the display medium Turned white (FIG. 10B). When this display operation was repeated, the time until the display density was saturated from red to white and from white to red was about 0.5 seconds.
For the display at this time, voltage was applied until the display density was saturated, and the saturation and display density during red display and the whiteness during white display in the state where the display density was saturated were evaluated.

(Example B2)
A display medium was prepared and evaluated in the same manner as in Example B1 except that non-color-forming charge-transfer particles B were used in place of non-color-forming charge-transfer particles A.

(Comparative Example B1)
A display medium was prepared and evaluated in the same manner as in Example B1 except that the non-color-forming charge transfer particles A and the particulate reflecting member A were not used.

-Evaluation-
The evaluation results of the saturation, display density, and whiteness of Examples B1 and B2 and Comparative Example B1 are shown in Table 2 below. Note that the evaluation method and evaluation criteria for saturation, display density, and whiteness shown in Table 2 are the same as those shown in Table 1.

It is a schematic diagram which shows an example of the display medium of 1st this invention. It is a schematic diagram which shows the other example of the display medium of 1st this invention. It is a schematic diagram which shows the other example of the display medium of 1st this invention. It is a schematic diagram which shows the other example of the display medium of 1st this invention. It is a schematic diagram which shows the other example of the display medium of 1st this invention. It is a schematic diagram which shows the other example of the display medium of 1st this invention. It is a schematic diagram which shows the other example of the display medium of 1st this invention. It is a graph explaining the relationship between the threshold value of an electric field and display density of three types of color-forming charge transfer particles used in the display medium shown in FIG. It is a schematic diagram which shows the other example of the display medium of 1st this invention. It is a schematic diagram which shows an example of the display medium of 2nd this invention. It is a top view shown about an example of the transparent electrode used for 3rd this invention. It is a top view shown about the other example of the transparent electrode used for 3rd this invention.

Explanation of symbols

100, 102, 104, 106, 108, 110, 112, 114 Display medium 114A, 114B, 114C Display cell 120 Display medium 200 Transparent substrate 202 Display surface 204 Rear substrate 206 Partition 210, 210A, 210B, 210C, 212, 214 Transparent Electrode 216 Exposed portion 220, 220A, 220B, 220C Rear electrode 250 Scan electrode 260 Rear electrode 270 External electrode 270A, 270B, 270C, 270D, 270E Electrode 272 External electrode holding member 280 Rear electrode 300, 300A, 300B, 300C Charge-transfer particles 302 Dispersion media 310A, 310B, 310C Color-forming charge-transfer particles 400 Void-forming particles 410 Non-color-forming charge-transfer particles 500, 500A, 500B Electric field applying means 600, 602 Reflecting member

Claims (31)

A transparent substrate in which one surface constitutes a display surface;
A rear substrate disposed opposite to the surface opposite to the display surface of the transparent substrate;
A dispersion medium enclosed in a gap between the transparent substrate and the back substrate;
One or more color-forming charge-transfer particles that are contained in the dispersion medium and develop color in a state dispersed in the dispersion medium;
Arranged in a state of being fixed to the surface of the transparent substrate opposite to the display surface, and communicating from the surface of the transparent substrate opposite to the display surface to the back substrate side and all kinds of color-generating charge transfer A void-forming member that forms a void in which the conductive particles move.   A back electrode is provided on the surface of the back substrate on the transparent substrate side, a transparent electrode is provided on the surface of the transparent substrate opposite to the display surface, and the gap forming member is fixed on the surface of the transparent electrode. The display medium according to claim 1, wherein the display medium is arranged in a state where the display medium is placed.   The display medium according to claim 1, wherein the gap forming member is made of a transparent material.   The refractive index of the gap forming member made of the transparent material is in the range of the refractive index of the dispersion medium -0.05 to the refractive index of the dispersion medium +0.05. The display medium described.   The display medium according to claim 1, wherein the gap forming member is white.   The display medium according to claim 1, wherein the gap forming member is made of a resin material.   The display medium according to claim 1, wherein the void-forming member is constituted by a particle group including two or more void-forming particles.   8. The display medium according to claim 7, wherein the average particle diameter of the void-forming particles is in the range of 5 to 20 times the average particle diameter of all kinds of color-forming charge transfer particles.   The display medium according to claim 1, wherein the gap forming member is a porous body.   The one or more color-forming charge-transfer particles are colored in different colors while dispersed in the dispersion medium, and the absolute value of the threshold value of the electric field for electrophoresis in the dispersion medium is also different from each other. The display medium according to any one of claims 1 to 9, wherein the display medium is composed of chromogenic charge transfer particles.   In a state where the two or more kinds of color-forming charge-transfer particles are dispersed in the dispersion medium, a color-forming charge-transfer particle that develops red color, a color-form charge-transfer particle that develops green color, and a blue color The display medium according to claim 10, wherein the display medium is composed of color-forming charge transfer particles that develop a color. In the gap between the transparent substrate and the back substrate, a cell in which a dispersion medium containing one kind of color-generating charge transfer particles is provided by providing a partition partitioning the gap is disposed,
A cell in which a dispersion medium containing color developing charge-transfer particles that develops red color when dispersed in a dispersion medium is encapsulated, and a color-generating charge transport particle that develops green color when dispersed in a dispersion medium Characterized in that it is composed of three types of cells: a cell encapsulating a dispersion medium containing benzene, and a cell encapsulating a dispersion medium containing color-developing charge transfer particles that develop a blue color when dispersed in the dispersion medium. The display medium according to any one of claims 1 to 9. A transparent substrate in which one surface constitutes a display surface;
A rear substrate disposed opposite to the surface opposite to the display surface of the transparent substrate;
A dispersion medium enclosed in a gap between the transparent substrate and the back substrate;
And at least two or more types of charge transfer particles that are contained in the dispersion medium and have different absolute values of the threshold value of the electric field for electrophoresis in the dispersion medium,
Among the two or more types of charge transfer particles, the charge transfer particles having the smallest absolute value of the electric field threshold value are present when only the charge transfer particles are present on the surface of the transparent substrate in the dispersion medium. Non-chromogenic charge transfer particles whose display surface shows a background color,
A display medium, wherein the other charge-transfer particles excluding the non-color-forming charge-transfer particles are color-form charge-transfer particles that develop color when dispersed in the dispersion medium.   14. The display medium according to claim 13, wherein a back electrode is provided on a surface of the back substrate on the transparent substrate side, and a transparent electrode is provided on a surface opposite to the display surface of the transparent substrate. .   The display medium according to claim 13 or 14, wherein the non-color-forming charge transfer particles are made of a transparent material.   The refractive index of the non-chromogenic charge transfer particles composed of the transparent material is in the range of the refractive index of the dispersion medium -0.05 to the refractive index of the dispersion medium +0.05. The display medium according to claim 15.   The display medium according to claim 13 or 14, wherein the non-color-forming charge transfer particles are made of a white material.   The display medium according to claim 13, wherein the non-color-developing charge transfer particles are made of a resin material.   The average particle diameter of the non-chromogenic charge transfer particles is in the range of 1 to 10 times the average particle diameter of all kinds of chromogenic charge transfer particles. The display medium according to any one of the above.   The mobility of the non-color-generating charge-transfer particles is equal to the mobility of the charge-transfer particles having the highest mobility among other charge-transfer particles excluding the non-color-forming charge-transfer particles or The display medium according to claim 13, wherein the display medium is more than that.   The charge transfer particles other than the non-color-forming charge transfer particles are colored in different colors while being dispersed in the dispersion medium, and the absolute value of the threshold value of the electric field for electrophoresis in the dispersion medium is also The display medium according to any one of claims 13 to 20, wherein the display medium is composed of two or more different color-developing charge transfer particles.   In a state where the two or more kinds of color-forming charge-transfer particles are dispersed in the dispersion medium, a color-forming charge-transfer particle that develops red color, a color-form charge-transfer particle that develops green color, and a blue color The display medium according to claim 21, comprising color-forming charge-transfer particles that develop color. In the gap between the transparent substrate and the back substrate, a cell in which a dispersion medium containing two types of charge transfer particles is enclosed is provided by providing a partition that partitions the gap.
A cell in which a dispersion medium containing a non-chromogenic charge-transfer particle and a chromophoric charge-transfer particle that develops a red color when dispersed in the dispersion medium, and the non-chromic charge-transfer particle And a cell encapsulating a dispersion medium containing chromogenic charge transfer particles that develop a green color when dispersed in the dispersion medium, and blue in a state dispersed in the non-chromogenic charge transfer particles and the dispersion medium The display medium according to any one of claims 13 to 20, wherein the display medium is composed of three types of cells in which a dispersion medium containing color-forming charge-transfer particles is encapsulated. A transparent substrate in which one surface constitutes a display surface;
A transparent electrode disposed on a surface opposite to the display surface of the transparent substrate;
A rear substrate disposed opposite to the surface of the transparent substrate opposite to the display surface;
A dispersion medium enclosed in a gap between the transparent substrate and the back substrate;
One or more chromogenic charge transfer particles contained in the dispersion medium and colored in a state dispersed in the dispersion medium,
The transparent electrode is at least one selected from an aspect in which the transparent electrode is discretely arranged on the surface of the transparent substrate and an aspect in which the transparent electrode surface is discretely exposed. A display medium, wherein the display medium is disposed on a surface of the electrode opposite to the display surface.   The display medium according to claim 24, wherein a back electrode is disposed on a surface of the back substrate on which the transparent substrate is provided. A transparent substrate in which one surface constitutes a display surface;
A transparent electrode disposed on a surface opposite to the display surface of the transparent substrate;
A rear substrate disposed opposite to the surface of the transparent substrate opposite to the display surface;
A back electrode disposed on the transparent substrate side surface of the back substrate;
A dispersion medium enclosed in a gap between the transparent substrate and the back substrate;
One or more color-forming charge-transfer particles that are contained in the dispersion medium and develop color in a state dispersed in the dispersion medium;
A void forming member that is disposed in a state of being fixed to the transparent electrode surface, and that forms a void that leads from the transparent electrode surface to the back substrate side and in which all kinds of color-generating charge-transfer particles move;
A display device comprising at least an electric field applying unit that is connected to the transparent electrode and the back electrode and applies an electric field to the dispersion medium. A transparent substrate in which one surface constitutes a display surface;
A transparent electrode disposed on a surface opposite to the display surface of the transparent substrate;
A rear substrate disposed opposite to the surface of the transparent substrate opposite to the display surface;
A back electrode disposed on the transparent substrate side surface of the back substrate;
A dispersion medium enclosed in a gap between the transparent substrate and the back substrate;
Two or more kinds of charge-transfer particles having different absolute values of the threshold value of the electric field for electrophoresis in the dispersion medium;
An electric field applying means connected to the transparent electrode and the back electrode for applying an electric field to the dispersion medium;
Comprising at least
Among the two or more types of charge transfer particles, the charge transfer particles having the smallest absolute value of the electric field threshold value are present when only the charge transfer particles are present on the surface of the transparent substrate in the dispersion medium. Non-chromogenic charge transfer particles whose display surface shows a background color,
A display device, wherein the other charge-transfer particles excluding the non-color-forming charge-transfer particles are color-form charge-transfer particles that develop a color when dispersed in the dispersion medium. A transparent substrate in which one surface constitutes a display surface;
A transparent electrode disposed on a surface opposite to the display surface of the transparent substrate;
A rear substrate disposed opposite to the surface of the transparent substrate opposite to the display surface;
A back electrode disposed on the transparent substrate side surface of the back substrate;
A dispersion medium enclosed in a gap between the transparent substrate and the back substrate;
One or more color-forming charge-transfer particles that are contained in the dispersion medium and develop color in a state dispersed in the dispersion medium;
An electric field applying means connected to the transparent electrode and the back electrode for applying an electric field to the dispersion medium;
Comprising at least
The transparent electrode is at least one selected from an aspect in which the transparent electrode is discretely arranged on the surface of the transparent substrate and an aspect in which the transparent electrode surface is discretely exposed. A display device, wherein the display device is disposed on a surface opposite to the display surface of the electrode. One surface of the transparent substrate constituting the display surface opposite to the display surface is a dispersion medium and one or more types of chromogenic charge transfer that is colored in the dispersion medium and dispersed in the dispersion medium. And a light control layer containing the active particles,
All kinds of color-forming charges that pass from the surface opposite to the display surface of the transparent substrate to the direction away from the surface opposite to the display surface on the surface opposite to the display surface of the transparent substrate It is arranged in a state where a gap forming member that forms a gap in which the mobile particles move is fixed,
When one or more of all kinds of color-forming charge transfer particles are present at a position away from the surface opposite to the display surface of the transparent substrate,
At least one color-forming charge-moving particle selected from one or more kinds of color-forming charge-moving particles existing at a position away from the surface opposite to the display surface of the transparent substrate is the transparent substrate side. A first display switching step of switching a display state of the display surface by applying an electric field that moves in the dispersion medium to the light control layer;
When one or more kinds of all kinds of color-forming charge transfer particles are present on the surface of the transparent substrate opposite to the display surface,
At least one type of chromogenic charge transfer particles selected from one or more chromogenic charge transfer particles present on the opposite side of the display surface of the transparent substrate is the display of the transparent substrate. A second display switching step of switching the display state of the display surface by applying an electric field that moves in the dispersion medium in a direction away from the surface opposite to the surface to the light control layer;
A display method comprising at least: Two or more types of charge-transfer particles having different absolute values of the dispersion medium and the threshold value of the electric field for electrophoresis in the dispersion medium on the surface opposite to the display surface of the transparent substrate constituting one display surface And a light control layer including
Among the two or more types of charge transfer particles, the charge transfer particles having the smallest absolute value of the electric field threshold value are present when only the charge transfer particles are present on the surface of the transparent substrate in the dispersion medium. Non-chromogenic charge transfer particles whose display surface shows a background color,
Other charge-transfer particles excluding the non-color-forming charge-transfer particles are color-form charge-transfer particles that develop color when dispersed in the dispersion medium,
When the non-color-developing charge transfer particles and all kinds of color-development charge transfer particles are present at a position away from the surface opposite to the display surface of the transparent substrate,
The non-color-developing charge transfer particles and at least one color-developing charge transfer particles selected from all types of color-developing charge transfer particles are opposite to the display surface of the transparent substrate. A first display switching step of switching the display state of the display surface by applying an electric field that moves in the dispersion medium from a position away from the surface to the transparent substrate side to the light control layer;
The non-color-forming charge-transfer particles are present on the surface of the transparent substrate opposite to the display surface, and one or more color-forming charges among all kinds of color-forming charge-transfer particles. When the mobile particles are present at a position away from the surface opposite to the display surface of the transparent substrate,
The at least one color-forming charge-transfer particle selected from the one or more color-forming charge-transfer particles is moved from the position away from the surface opposite to the display surface of the transparent substrate to the transparent substrate side. A second display switching step of switching a display state of the display surface by applying an electric field that moves in the dispersion medium to the light control layer;
The non-color-forming charge-transfer particles and one or more color-forming charge-transfer particles out of all types of color-forming charge-transfer particles are opposite to the display surface of the transparent substrate. If it exists in
All types of charge transfer particles present on the surface of the transparent substrate opposite to the display surface are removed from the surface of the transparent substrate opposite to the display surface to the surface of the transparent substrate opposite to the display surface. A third display switching step of switching the display state of the display surface by applying an electric field that moves in the dispersion medium to a further distance to the light control layer;
A display method comprising at least: One surface constitutes a display surface and a transparent electrode is disposed on the surface opposite to the display surface. The transparent substrate is disposed on the surface on which the transparent electrode is disposed. A light control layer including one or more color-forming charge-transfer particles that develop color in a dispersed state is disposed;
The transparent electrode is at least one selected from an aspect in which the transparent electrode is discretely arranged on the surface of the transparent substrate and an aspect in which the transparent electrode surface is discretely exposed. Disposed on the surface of the electrode opposite to the display surface;
When one or more of all types of color-forming charge transfer particles are present at a position away from the surface of the transparent substrate on which the transparent electrode is disposed,
At least one type of chromogenic charge transporting particles selected from one or more chromogenic charge transporting particles present at a position distant from the surface on which the transparent electrode is disposed on the transparent substrate. A first display switching step of switching a display state of the display surface by applying an electric field that moves in the dispersion medium to the light control layer using at least the transparent electrode;
When one or more of all kinds of color-forming charge transfer particles are present on the surface of the transparent electrode,
A direction in which at least one color-forming charge-transfer particle selected from one or more color-forming charge-transfer particles existing on the surface of the transparent electrode is separated from the surface of the transparent substrate opposite to the display surface A second display switching step of switching a display state of the display surface by applying an electric field that moves in the dispersion medium to the light control layer using at least the transparent electrode;
A display method comprising at least:

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