JP2000089261A - Charged particles, display element and display medium - Google Patents

Abstract

(57) [Problem] To provide inexpensive fine-particle charged particles which are close to a true sphere and inexpensive. The charged particles according to claim 1 are positively or negatively charged in a dispersion medium, have a mean particle size of 1 to 100 µm, and have a colorant for coloring the charged particles. It is characterized by consisting of wax.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charged particle having a characteristic of moving in a predetermined electrode direction when an electric field is applied in a dispersion medium, a microcapsule containing the charged particle and the dispersion medium, and The present invention relates to a display medium in which an arrangement layer of the microcapsules is formed on a flexible sheet, and an image is formed by applying a control electric field to the arrangement layer.

[0002]

2. Description of the Related Art Conventionally, as a method for displaying an image or character information, a CRT (Cathode Ray Tube: cathode ray tube) has been used.
There are a wide variety of methods, from a liquid crystal (Liquid Crystal) method, a plasma light emitting method, a method of visualizing using an EL (electroluminescence) method, and the like.

In recent years, with the rapid progress in semiconductor technology, various electronic devices have been miniaturized, and display devices have also been reduced in size, weight, driving voltage, power consumption, and the like.
There is a demand for a thin flat panel.

In order to respond to the above-mentioned request, PDP (Plass)
ma Display Panel) and LCD (L
Numerous types of flat panel electronic display devices, such as a light receiving type represented by an iquid crystal display, have been proposed and put to practical use. In recent years, in particular, reflection type LCDs have been actively studied because of their low power consumption.

[0005] The advantages of the reflective LCD are that it can be made smaller, lighter, lower in driving voltage, lower in power consumption, thinner in a flat panel, and the like. For example, it has a display quality that is easily compatible and has no influence of external light.

[0006]

However, in a reflection type LCD, even if a TFT-panel is combined with a guest-host liquid crystal, theoretically, only an image having a reflectance of 66% and a contrast ratio of 5: 1 can be obtained. Absent.

This has a reflectance of 57% and a contrast ratio of 5:
The image quality is as close as possible to the image of newspaper paper 1 and the reflectivity of the image output by a calendar or laser printer is 80.
% And a contrast ratio of 21: 1, which is far from the image quality. In addition, since the LCD does not have a memory function, the image display cannot be maintained when the control electric field is cut off, and during the image display, it is not necessary to constantly apply an external stimulus such as an electric field to the display surface. However, there is a problem that it is difficult to use and is economically disadvantageous.

[0008]

In order to solve these problems, the present inventor pays attention to "low driving voltage", "high reflectivity and high contrast in the reflection type", and "memory effect when the control electric field is cut off". However, as a result of studying to develop a display mechanism that realizes these functions, the charged particles containing a coloring agent such as a pigment are moved in a predetermined electrode direction by applying an electric field in a microcapsule. The present inventors have found that an image display method for writing an image on a display surface is convenient and feasible, and has previously filed an application for the display mechanism. Then, as a result of further study for the purpose of making the display element used in the above display mechanism cheaper and higher performance, as a result, wax was used as a constituent material of the charged particles to be encapsulated in the microcapsules used as the display element. It has been found that the use of such particles makes it possible to easily and inexpensively produce fine-particle-like charged particles close to a true sphere, and has completed the present invention.

In order to achieve the above object, the charged particles according to claim 1 are positively or negatively charged in a dispersion medium.
Charged particles having an average particle diameter of 00 μm, characterized by comprising a coloring agent for coloring the charged particles and wax.

According to the first aspect of the present invention, the charged particles comprise the coloring agent and the wax.
By the following method, charged particles having a shape close to a true sphere can be produced at lower cost. That is, the wax containing the colorant easily becomes a low-viscosity liquid by giving an external stimulus such as heating, and the spray method (spray dry method)
Or a method of dispersing the above-mentioned liquid wax in a high-temperature liquid can easily produce fine particles close to a true sphere. Therefore, by applying the above method, charged particles having a shape close to a true sphere can be produced at lower cost.

A display element according to a second aspect of the present invention comprises a microcapsule in which two or more kinds of charged particles and a dispersion medium for dispersing the charged particles are encapsulated. By changing the distribution state under the action of the control electric field, a display element that changes the optical reflection characteristic of a predetermined area of the microcapsule to perform a required display operation, and as the charged particles. , Wherein the charged particles according to claim 1 are used.

According to the display element of the second aspect, since the charged particles of the first aspect are used as the charged particles in the microcapsules, it is possible to realize a cheaper and higher-performance display element. it can.

[0013] In the display medium according to the third aspect, an arrangement layer of microcapsules is formed on a flexible sheet, and a required display is performed by applying a control electric field to each microcapsule in the arrangement layer. A display medium adapted to perform an operation, wherein the display element according to claim 2 is used as the microcapsule.

According to the display medium of the third aspect, since the display element of the second aspect is used as the microcapsule, a more inexpensive and high-performance display medium can be realized.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the charged particles, display element and display medium of the present invention will be described with reference to the drawings. The charged particles of the present invention are positively or negatively charged in a dispersion medium, are charged particles having an average particle diameter of 1 to 100 μm, and include a coloring agent and a wax for coloring the charged particles. Features.

The average particle size of the charged particles is 1 to 100 μm.
When the average particle diameter of the charged particles is less than 1 μm, the charged particles are too small, so that the production of the charged particles becomes difficult and a large number of the charged particles are present in a display element such as a microcapsule. And the average particle diameter of the charged particles exceeds 100 μm, the charged particles become too large,
Since it is difficult to move, it is difficult to function as a display element.

Examples of the coloring agent for coloring the charged particles include generally known colored colloid particles; various organic and inorganic pigments, dyes, metal powders, glass, and fine powders of resins and the like.

The organic pigment is not particularly limited. For example, Hansa Yellow, Benzine Y
yellow pigment such as yellow; Parent Re
d, benzine orange, pyrazol
one orange, vulcan orange,
orange lake, para red, lake
red, toludine red, brill f
ast scarlet, brill carmin
e, brill scarlet, bordo, wa
tchung red, lithol red, bon
maroon, lake bodo, rhoda
red pigments such as mine, madder lake; rh
odamine b lake, dioxazine
violet, crystal violet lak
purple pigment such as e; victoria pure blue
e lake, victoria blue lak
e, phthalocyanine blue, fas
t sky blue, threen blue rs
Blue pigment such as diamond green lac
e, phtalocyanine green, pi
and green pigments such as gment green b and green gold, and black pigments such as diamond black.

The inorganic pigment is not particularly limited.
For example, black pigments such as carbon black; titanium oxide;
Examples include white pigments such as aluminum oxide, zinc oxide, lead oxide, and tin oxide. The inorganic pigment and the organic pigment,
They may be used alone or in combination of two or more.

The above dye is not particularly limited, and examples thereof include azo dyes, metal complex dyes, naphthol dyes, anthraquinone dyes, indigo dyes, carbonium dyes, quinoimine dyes, cyanine dyes, quinoline dyes, nitro dyes, nitroso dyes, and benzoquinone dyes. And naphthoquinone dyes, naphthalimide dyes, penoline dyes, phthalocyanine dyes and the like. The above dyes may be used alone or in combination of two or more.

The wax serves as a so-called binder for dissolving or dispersing the coloring agent. The wax is classified into a synthetic wax composed of a synthetic polymer and a natural wax composed of a natural material.

Examples of the monomer component used for producing the above synthetic wax include methyl acrylate, ethyl acrylate, n-butyl acrylate, i-butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, tetrahydrofuryl acrylate, methyl methacrylate, and ethyl methacrylate. Methacrylate, n
-Butyl methacrylate, i-butyl methacrylate,
2-ethylhexyl methacrylate, stearyl methacrylate, lauryl methacrylate, methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-butyl vinyl ether, n-butyl vinyl ether, styrene, α-methylstyrene, acrylonitrile, methacrylonitrile, vinyl acetate, vinyl chloride, vinyl chloride ,
Examples thereof include vinylidene chloride, vinyl fluoride, vinylidene fluoride, ethylene, propylene, isoprene, chloroprene, and butadiene.

The above-mentioned monomer components include, for example, a carboxyl group, a hydroxyl group, a methylol group,
It may contain a functional group such as an amino group, an amide group, an acid amide group, and a glycidyl group.

Examples of the monomer having a carboxyl group include acrylic acid, methacrylic acid, and itaconic acid. Examples of the monomer having a hydroxyl group include:
For example, β-hydroxyethyl acrylate, β-hydroxyethyl methacrylate, β-hydroxypropyl acrylate, β-hydroxypropyl methacrylate, allyl alcohol and the like can be mentioned.

Examples of the monomer having a methylol group include N-methylol acrylamide and N-methylol methacrylamide, and examples of the monomer having an amino group include dimethylaminoethyl acrylate and dimethylaminoethyl methacrylate. No.

Examples of the monomer having an acid amide group include acrylamide and methacrylamide, and examples of the monomer having a glycidyl group include glycidyl acrylate, glycidyl methacrylate, and glycidyl allyl ether. These monomer components may be used alone or in combination of two or more.

A synthetic wax is produced by polymerizing these monomer components.
Various methods conventionally used can be adopted. However, the fine particles after polymerization are 80 to 150 ° C.
In this case, it is preferable to adjust the molecular weight at the time of polymerization so as not to have a high viscosity with a high molecular weight.

The natural waxes are classified into plant, animal, mineral, and petroleum. As a vegetable wax,
Examples include candelilla wax, carnauba wax, rice wax, wood wax, jojoba oil and the like. Animal waxes include, for example, beeswax, lanolin, whale wax and the like.

Examples of the mineral wax include montan wax, ozokerite, and ceresin.
As the petroleum wax, for example, paraffin wax,
Microcrystalline wax, petrolam and the like can be mentioned. These natural waxes can be used alone or in combination of two or more.

Among the above waxes, 80 to 150
C., preferably at 80 to 120.degree. C., and those whose viscosity is greatly reduced by melting are preferred. Specifically, those having a viscosity of 5000 cP or less are preferable, and
Those having P or less are more preferable, and those having 500 cP or less are still more preferable.

When a pigment is used as a coloring agent, the pigment is kneaded into wax by using a roll mill or the like, and the pigment is dispersed in the wax. When the above dye is used as a colorant, the dye is mixed with the wax after melting the wax, and the dye is dissolved in the wax. When a dye is used as a colorant, the dye is required to be soluble in wax but not in a dispersion medium for dispersing charged particles.

When a terminal group or a carboxyl group containing fluorine is present in the wax, the charged particles are likely to be negatively charged in the dispersion medium. When an amino group or an amide bond is present in the wax, the charged particles are charged. Since the particles are likely to be positively charged in the dispersion medium, the chargeability of the charged particles can be controlled by using the wax having the above-described chemical structure. When using a synthetic wax, a monomer having the above substituent introduced therein may be used.

As a method for producing the charged particles, for example, a spraying method (spray drying method) or a method of dispersing the liquid wax in a high-temperature liquid and then cooling (hereinafter referred to as a liquid dispersion method). No. As the spraying method, a conventionally known method can be used.For example, first, a wax in which the coloring agent is dissolved or dispersed is heated to be in a liquid state, and then, the diameter is several cm to several tens cm.
The liquid wax is dropped and scattered on the disk surface while rotating the disk whose surface has been roughened at a high speed.

At this time, the temperature of the disk is set slightly higher than the melting point of the wax, and the temperature in the apparatus is set at a temperature several tens of degrees lower than the melting point of the wax. By setting such conditions, the particles scattered into the air from the disk surface are immediately solidified, and charged particles having a shape close to a true sphere having a diameter of about several tens μm can be produced. The particle diameter of the charged particles can be controlled by changing the viscosity of the wax, the rotation speed of the disk, and the like.

When the above-mentioned liquid dispersion method is used, several μm
It is possible to produce charged particles having a degree and an average particle diameter smaller than in the case of the spray method. In this case, 8
The wax melted by heating to 0 to 150 ° C. is put into a liquid heated to a temperature equal to or higher than the melting temperature of the wax, sufficiently stirred and dispersed, cooled, and then cooled. By solidifying the droplets, finely charged particles are produced. An autoclave or the like may be used to increase the temperature of the liquid. Further, an emulsifier may be added at the time of producing the charged particles in order to improve the dispersibility of the wax. Charged particles produced in the presence of an emulsifier, at least a part of the surface of which is coated with an emulsifier, the emulsifier is not removed from the surface of the charged particles by washing or the like, so the type of the emulsifier is selected. Thereby, the chargeability of the surface of the charged particles can be controlled.

Also, by a method of continuously ejecting a molten wax from a nozzle having a fine diameter,
Charged particles having a uniform particle diameter can be produced. Charged particles using titanium oxide as a coloring agent,
It is excellent in whiteness and hiding power, and carbon black used as a coloring agent shows perfect black. Therefore, the charged particles using carbon black are excellent in blackness.

Therefore, by using charged particles using titanium oxide and carbon black as coloring agents,
A display medium having high reflectivity and contrast ratio and having an easily viewable image and the like can be realized. The content of the coloring agent contained in the charged particles is 5 to 6 in the case of titanium oxide.
0% by weight is preferable, and in the case of carbon black, 3%
~ 30% by weight is preferred.

The dispersion medium for dispersing the charged particles is preferably one having high insulation properties and colorless transparency. Examples of the dispersion medium having such characteristics include:
Examples thereof include aliphatic hydrocarbons, aromatic hydrocarbons, alicyclic hydrocarbons, halogenated hydrocarbons, various esters, alcohols, and other oils. These dispersion media may be used alone or in combination of two or more.

The dispersion medium may contain a surfactant in order to improve the dispersion state of the charged particles.
The above-mentioned surfactants are classified into anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants, and the like, depending on the type of hydroxyl group bonded to a hydrophobic group such as paraffin, olefin, and alkylbenzene. In the present invention, any of the above surfactants can be used.

However, the amount of addition depends on the type of surfactant,
Although it varies depending on the structure, it is preferable to add it within a range that does not extremely lower the insulation degree of the insulating dispersion medium.

The charged particles are used in a state of being dispersed in the dispersion medium, and can be used for various display elements.
It can be used as a display element or a display medium having a structure described below.

FIG. 1 is an explanatory view schematically showing one example of a microcapsule functioning as a display element of the present invention. FIG. 2 is a diagram showing black charged particles and white charged particles after an electric field is applied to the microcapsules. FIG. 3 is an explanatory diagram schematically showing a state of particles.

As shown in FIG. 1, the microcapsules 10 enclose, for example, charged particles 12 composed of a large number of black charged particles 12a and white charged particles 12b, and a liquid dispersion medium 14. The black charged particles 12a are made of, for example, carbon black and natural wax, and the white charged particles 12b are made of, for example, titanium oxide and natural wax. When no electric field is applied, the black charged particles 12a and the white charged particles 12b are randomly dispersed, as shown in FIG.

Next, when an electric field is applied to the microcapsules 10, the black charged particles 12a and the white charged particles 12b dispersed and suspended in the liquid dispersion medium 14 migrate in opposite directions due to the action of the electric field. Then, for example, as shown in FIG. 2, the white charged particles 12b aggregate upward,
Below, the black charged particles 12a aggregate.

Therefore, when the microcapsules 10 are viewed from above, the black charged particles 12 agglomerated on the lower side.
“a” is hidden by the white charged particles 12 b and cannot be seen, and the portion of the microcapsule 10 looks white.

On the other hand, although not shown in the figure, when an electric field in the opposite direction to that of FIG. 2 is applied, the black charged particles 12a agglomerate upward and the white charged particles 12b agglomerate downward. The portion of the capsule 10 looks black from above.

By arranging such microcapsules 10 on the surface of a flexible sheet or the like and changing the direction of an electric field applied to the microcapsules 10, a predetermined image can be formed on the display surface. Further, by enclosing the charged particles 12 containing colors such as red, blue, and yellow in the microcapsules 10, it is possible to display an image containing colors such as red, blue, and yellow. In the present invention, since the charged particles 12 having a shape close to a true sphere are used, the charged particles 12 move smoothly when an electric field is applied, and the charged particles 1
Higher-performance display becomes possible without the two being caught.

The microcapsules can be prepared by a method which is already known in the art. As a method for producing microcapsules, for example,
U.S. Pat. Nos. 2,800,457 and 2,800,458, which show a phase separation method from an aqueous solution as disclosed in JP-B-38-19574, JP-B-42-446, and JP-B-4.
No. 2-771, interfacial polymerization method, JP-B-36-9168, JP-A-51-9079, etc., in-situ method by polymerization of monomers, British Patent No. 952807, and the like. There is a melting dispersion cooling method described in Japanese Patent No. 965074, but the present invention is not limited thereto.

The material for forming the outer wall portion of the microcapsule 10 is not particularly limited as long as the outer wall portion can be formed by the above-described capsule manufacturing method. An inorganic material or an organic material may be used. Materials are preferred.

Specific examples of the material for forming the outer wall portion include:
For example, gelatin, gum arabic, starch, sodium alginate, polyvinyl alcohol, polyethylene, polyamide, polyester, polyurethane, polyurea, polystyrene, nitrocellulose, ethylcellulose, methylcellulose, melamine / formaldehyde resin, urea / formaldehyde resin, copolymers thereof, etc. Is mentioned.

Each charged particle 12 in the microcapsule 10
Is preferably 1.5 to 25% by volume with respect to the volume of the microcapsule 10, and the total volume of all the charged particles 12 is 1.5% with respect to the volume of the microcapsule 10. It is preferably from 50 to 50% by volume.

If the volume of each charged particle 12 is less than 1.5% by volume, the opposite color particles which are not the intended display color will also be seen by the observer, and the contrast will appear to be reduced. On the other hand, if it exceeds 25% by volume, the charged particles 1
Since 2 is too large, it is difficult to move inside the microcapsule 10. If the sum of the volumes of all the charged particles 12 is less than 1.5% by volume, the amount of the charged particles 12 is too small, so that no clear image is formed. Since the amount of the particles 12 is too large, it is difficult to move inside the microcapsules 10, and therefore, the response to the control electric field is reduced.

The particle size of the charged particles 12 is preferably 1/1000 to 1/5 with respect to the particle size of the microcapsules 10, and the degree of dispersion of the particle size distribution of the charged particles 12 is expressed as volume average particle size / number When represented by an average particle diameter, it is preferably from 1 to 2. The microcapsules 10 preferably have a particle size of 50 to 500 μm.

FIG. 3 is a cross-sectional view schematically showing one example of a display medium using the display element of the present invention. In this display medium 20, a large number of transparent electrodes 24 are provided in an array shape in a plan view on the upper surface side of a flexible sheet 22 in which a large number of microcapsules 10 are dispersed and arranged, and a transparent or transparent electrode is provided on the lower surface side. An opaque electrode 25 is provided.

The individual transparent electrode 24 and electrode 2
A power supply (not shown) is connected to 5, and a positive or negative voltage is independently applied between each transparent electrode 24 and the electrode 25 based on the voltage of the electrode 25.

The transparent electrode 24 is larger than the shape of the microcapsule 10 in a plan view. At least one microcapsule 10 is provided for each transparent electrode 24.

Examples of the flexible sheet 22 include a resin film and paper. When a voltage corresponding to an image or the like to be displayed is applied between each transparent electrode 24 and the electrode 25 of the display device 20, as shown in FIG. 12b
Aggregate to form an image corresponding to the image to be displayed.

Even when the power is turned off, the charged particles 12
Does not change, the display state of the image is maintained unless a voltage corresponding to another image is applied between each transparent electrode 24 and the electrode 25. No electrodes are provided on the display medium, and an external electric field applying device is used.
An electric field may be applied to each microcapsule.

As described above, in the display medium of the present invention, an arrangement layer of microcapsules in which charged particles comprising a colorant and wax and a dispersion medium are encapsulated is formed on a flexible sheet. Since a display medium that performs a required display operation by applying a control electric field to each of the microcapsules is used, a cheaper and higher-performance display medium can be realized.

[0060]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Examples 1 to 5 and Comparative Examples 1 to 3 First, a wax having the properties shown in Table 1 was used.
The colorant was kneaded into the wax using a roll mill so that the colorant shown in (1) was contained at 10% by weight.

Next, charged particles were prepared by using a spraying method. That is, a rotary atomizer equipped with S-100 (diameter: 100 mm) (manufactured by Matsubo, No. 62 type) equipped with S-100 (diameter: 100 mm) was used. Was maintained at a temperature 10 ° C. higher than the melting point of the wax, and the wax heated to 120 ° C. was dropped on an atomizer having a rotation speed of 30,000 rpm to be scattered around, thereby producing charged particles.

When the wax shown in each of the examples in Table 1 was used, charged particles having an average particle diameter shown in Table 1 which were almost perfectly spherical and uniformly arranged could be obtained. On the other hand, when the resin or wax shown in Comparative Example of Table 1 was used, fine particles could not be obtained. That is, when the polyester resin (Comparative Example 1) was used, it was difficult to form fine particles because only a lump of the resin jumped out of the atomizer.

When the polypropylene wax (Comparative Example 2) was used, only fine particles having a shape protruding from the particles could be produced. When polyethylene wax (Comparative Example 3) was used, no fine particles were produced, and the state was like cotton candy.

[0065]

[Table 1]

Next, the white charged particles produced in the above example were placed in 100 cc of a 1: 1 aqueous solution of a 5% polystyrene sulfonic acid sodium salt aqueous solution as an emulsifier and an aliphatic hydrocarbon solvent as a liquid dispersion medium. Then, the mixture was stirred at 6000 rpm for 5 minutes with a homogenizer to obtain an emulsion in which a liquid dispersion medium containing white charged particles and black charged particles was uniformly dispersed in an aqueous solution.

Separately, a commercially available melamine powder was added to a 37% aqueous formaldehyde solution, adjusted to pH 9.0 with a sodium hydroxide solution, and heated at a water temperature of 60 ° C. for 30 minutes to obtain a melamine / formaldehyde prepolymer. Next, a melamine / formaldehyde prepolymer was added to the above emulsion, and 10
While stirring at 0 to 300 rotations, the temperature was maintained for 5 hours while being heated to a water temperature of 80 ° C., and then adjusted to PH7 and cooled to room temperature.

As a result, a wall member composed of a melamine / formaldehyde resin was deposited around the liquid dispersion medium containing the white charged particles and the black charged particles, and microcapsules containing the charged particles were obtained. The average particle size of the microcapsules was 40-70 μm.

Next, the microcapsules produced by the above method are taken out, dispersed and arranged on a flexible sheet, arranged between electrodes, and a control electric field of 100 V / mm is applied to display an image. Then, the images shown below were evaluated.

Evaluation method (1) Reflectance densitometer (RD 914 manufactured by Macbeth) as a white reflectance measuring device
Was used to measure the OD value (optical density), and the reflectance T (%) was calculated by -log ₁₀ T = OD. (2) Contrast ratio Similar to the case of the white reflectance, the reflectance _Tblack is measured also for the black print portion, and the contrast ratio = _Tblack : T
_white = 1: (T _white / T _black ) The above image quality evaluation criteria (threshold values) include an average value (white reflectance 7) of laser printer image samples under various conditions.
2%, contrast ratio 15: 1) was applied.

Table 2 shows the charged particles used (the number of the example in which the charged particles were produced), the volume% (content) of each charged particle in the microcapsules, and the evaluation results.

[0072]

[Table 2]

As is evident from the results shown in Table 2, microcapsules were produced using the charged particles produced in the above Examples, and in a display medium using the microcapsules as a display element, the display medium was almost spherical. Since charged particles are used, an image having a high reflectance and a high contrast ratio is formed.

[0074]

As described above, according to the charged particles of the first aspect, the charged particles are positively or negatively charged in the dispersion medium.
Charged particles having an average particle size of 100 μm, since the charged particles are composed of the colorant and wax,
By the following method, charged particles having a shape close to a true sphere can be produced at lower cost. That is, the wax containing the colorant easily becomes a low-viscosity liquid by giving an external stimulus such as heating, and the spray method (spray dry method)
By dispersing the liquid wax in a liquid of high temperature or high temperature, the particles can be easily converted into fine particles close to a true sphere, so that charged particles having a shape close to a true sphere can be produced at lower cost.

Further, the display element according to claim 2 comprises microcapsules in which two or more kinds of charged particles and a dispersion medium for dispersing these charged particles are encapsulated, and wherein the charged particles in the microcapsules are contained. By changing the distribution state under the action of the control electric field, a display element that changes the optical reflection characteristic of a predetermined area of the microcapsule to perform a required display operation, and as the charged particles. Since the charged particles described in claim 1 are used, a cheaper and higher-performance display element can be realized.

In the display medium according to the third aspect, an arrangement layer of microcapsules is formed on a flexible sheet, and required display is performed by applying a control electric field to each microcapsule in the arrangement layer. Since the display element described in claim 2 is used as the microcapsule in a display medium that is operated, a cheaper and higher-performance display medium can be realized.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram schematically showing an example of a microcapsule functioning as a display element of the present invention.

FIG. 2 is an explanatory view schematically showing states of black charged particles and white charged particles after an electric field is applied to a microcapsule functioning as a display element of the present invention.

FIG. 3 is a cross-sectional view schematically showing one example of a display medium using the display element of the present invention.

DESCRIPTION OF SYMBOLS 10 Microcapsules 12 Charged particles 12a Black charged particles 12b White charged particles 14 Liquid dispersion medium 20 Display medium 22 Flexible sheet 24 Transparent electrode 25 Electrode

 ──────────────────────────────────────────────────続 き Continuing on the front page F term (reference) 4G005 AA01 AB09 AB17 AB27 BA03 BB06 BB12 BB15 DB01X DB27X DC02X DD05Z DD08Z DD10Y DD12W DD34Z DD53W DD70W EA08 5C094 AA02 AA06 AA43 AA44 AA54 AA55 FA76 FA02 FB01 FB04 FB06 FB15 JA08

Claims (3)

[Claims] 1 to 1 which are positively or negatively charged in a dispersion medium.
A charged particle having an average particle diameter of 00 μm, comprising a coloring agent for coloring the charged particle and a wax. 2. A microcapsule in which two or more kinds of charged particles and a dispersion medium for dispersing these charged particles are sealed, and the distribution state of the charged particles in the microcapsules is controlled by an electric field for control. By changing with
2. A display element in which a required display operation is performed by changing the optical reflection characteristic of a predetermined area of the microcapsule, wherein the charged particles according to claim 1 are used as the charged particles. A display element characterized by the above-mentioned. 3. A display medium in which an arrangement layer of microcapsules is formed on a flexible sheet, and a required display operation is performed by applying a control electric field to each microcapsule in the arrangement layer. A display medium, wherein the display element according to claim 2 is used as the microcapsule.