JP2001142099A - Color developing device and method of developing color - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color developing device which can transit between a color developing state and a non-color developing state and which can maintain the color developing state even when the device is subjected to mechanical vibration. SOLUTION: The color developing device is equipped with a pair of transparent substrates 11, 12 having transparent electrodes 13, 14 disposed facing each other with a specified with a mixture filling the space between the substrates and consisting of a plurality of fine particles 16 having a smaller size than the specified gap and of an insulating fluid 15 having transparency for visible rays, and with a voltage applying means 17 to apply a voltage between the electrodes. When a voltage is applied on the pair of electrodes by the voltage applying means 17, such a structure that a plurality of the aforementioned fine particles are dispersed in the planes parallel to the aforementioned electrodes is formed, and colors are developed by introducing light into the mixture having the aforementioned structure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color-forming element which emits a color in the visible light range when natural light or artificial light is incident thereon, and a color-forming method thereof. The present invention relates to a color-forming element using a mixture of liquid crystal and fine particles capable of transition and a color-forming method thereof.

[0002]

2. Description of the Related Art In recent years, without using dyes such as dyes and pigments,
Research and development of a coloring structure that produces deeper and more vivid color by utilizing the reflection and interference of natural light and artificial white light has been actively conducted. Among them, there have been reported several methods of developing a color using a structure containing fine particles as a constituent element.
The prior art examples reported are as follows.

First, Japanese Patent Application Laid-Open No. Hei 8-21322 discloses a coloring structure in which a large number of fine particulate substances made of an inorganic substance are dispersed and fixed in a polymer resin. This coloring structure is formed by heating and melting a mixture of a polymer resin and a granular substance, and then cooling the mixture. When light is incident on the obtained coloring structure, a vivid color tone is developed.

Japanese Patent Application Laid-Open No. Hei 8-234007 discloses a color-forming film composed of a single-layer film of fine particles in which micron-order fine particles are arranged in a close-packed hexagonal lattice. This film is formed by lifting a substrate immersed in a liquid in which fine particles are suspended. When light enters this structure, it emits opal-like diffracted light.

Further, JP-A-5-85716 discloses a coloring solution in which silica particles are dispersed in a dispersion medium (water or a mixed solution of water and an organic solvent). This solution is formed by subjecting a solution in which silica particles are dispersed to deionization. After the deionization treatment, the silica particles have a structure resembling a microcrystalline aggregate.
When light enters the silica particle dispersion medium having such a structure, an opal-like color is observed.

[0006] When mechanical vibration is applied to the silica particle dispersion medium exhibiting an opal-like color, the opal-like color disappears. If the dispersion medium is allowed to stand without giving any vibration, the color development phenomenon appears again in a short time.

[0007]

However, the above prior art has the following problems. First, Japanese Patent Laid-Open No.
The coloring structure and the coloring film disclosed in JP-A-212322 and JP-A-8-234007 can produce vivid colors. However, in these structures and films, fine particles are immobilized in a solid or on a substrate, and the color cannot be released except for blocking incident light. For this reason, there has been a problem that it is difficult to freely transition between a colored state and a non-colored state in the presence of incident light.

Further, there is a problem that it takes a long time to produce the color forming solution disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 5-85716. This is because a very long time is required for deionizing the solvent.

The color-forming solution can make a transition between a color-forming state and a non-color-forming state. However, when it is desired to maintain the color-developing state, it is necessary to prevent the transmission of vibration to the container filled with the color-forming solution. That is, there is a problem that the color development state is weak against vibration.

An object of the present invention is to provide a color-forming element which can solve the above-mentioned problems of the prior art. That is, an object of the present invention is to provide a color-forming element capable of transitioning between a color-forming state and a non-color-forming state and maintaining a color-forming state even when exposed to mechanical vibration, and a color-forming method thereof.

[0011]

According to the present invention, there is provided a color-forming element comprising: a pair of transparent substrates having transparent electrode layers opposed to each other with a predetermined gap therebetween; A mixture of a plurality of fine particles smaller than one and an insulating fluid having transparency to visible light, and a color-forming element including voltage applying means for applying a voltage between the electrodes, wherein the voltage applying means is a pair of electrodes. Forming a structure in which the plurality of fine particles are distributed in a plane parallel to the electrode surface by applying a voltage therebetween, and causing the mixture having the structure to be colored by irradiating light to the mixture having the structure. Features.

[0012] Further, according to the present invention, there is provided a color forming method for a color forming element, wherein a pair of transparent substrates having transparent electrode layers opposed to each other with a predetermined gap therebetween, and a size filled between the substrates is smaller than the predetermined interval. A mixture of a plurality of small particles and an insulating fluid having a permeability to visible light, and a method for developing a color-forming element including a voltage applying means for applying a voltage between the electrodes, wherein the method comprises: By applying a predetermined voltage through the voltage applying means, a structure in which the plurality of fine particles are distributed in a plane parallel to the electrode surface is formed, and light is incident on the mixture having the structure. It is characterized by being colored by doing.

The mixture having the above structure is
By selectively transmitting light incident on the mixture, a color in the visible light region is generated. Further, the mixture having the structure emits light in a visible light region by selectively reflecting light incident on the mixture.

There is no particular limitation on the type of the insulating fluid. For example, a liquid crystal can be given. The liquid crystal is preferably a low-molecular liquid crystal showing a nematic liquid crystal or a cholesteric liquid crystal.

On the other hand, it is assumed that the fine particles do not dissolve in the insulating fluid, and that the size of the fine particles does not become larger than the gap between the electrodes due to absorption of the insulating fluid or a chemical change. If this condition is satisfied, the material of the fine solid is not particularly limited. For example, polymer beads or metal oxide fine particles containing a polymer as a main component can be used. The shape is not particularly limited. It may be spherical, flat, or acicular. However, it is desirable that the shape and size of each fine particle be uniform. It is preferable that the fine particles are composed of an organic substance, the shape of the fine particles is spherical, and the size of the fine particles is 10 μm or less. The mixing ratio of the fine particles and the insulating fluid according to the present invention is not particularly limited as long as a desired color-forming state can be formed in the mixture.

In the present invention, it is preferable that an insulating film is laminated on at least one surface of the pair of electrodes. When liquid crystal is used as the insulating liquid, the insulating film may have been subjected to a liquid crystal alignment treatment such as a rubbing treatment.

Further, the predetermined voltage applied between the pair of electrodes via the voltage applying means is such that a peak value on a plus side is not equal to a peak value on a minus side.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an example of a method of forming a color of a color element according to the present invention will be described with reference to FIGS.

FIG. 1 is a schematic diagram showing a non-color-forming state of a color-forming element according to the present invention, and schematically shows a distribution state of fine particles in an insulating fluid when the element is left without applying a voltage. 11 and 12 are transparent substrates, and 1
Reference numerals 3 and 14 are transparent electrodes provided on the substrates 11 and 12, respectively. Reference numeral 15 denotes an insulating fluid. 16 is one of a plurality of fine particles. Reference numeral 17 denotes voltage applying means for applying a voltage between the electrodes 13 and 14. In addition, a spacer sandwiched between the substrates and between the electrodes and an insulating film laminated on the electrode surface are omitted.

When fine particles are dispersed as shown in FIG. 1, no color in the visible light region is observed even when natural light transmitted through the insulating fluid 15 is observed. On the other hand, when natural light transmitted through the insulating fluid is observed with a voltage applied between the electrodes, it is possible to observe the color in the visible light region (i.e., iridescent or opal).

The reason will be described. When a predetermined voltage is applied between the electrodes 13 and 14 by the voltage applying means 17, the fine particles dispersed between the electrodes receive a force from the electric field,
It is attracted to one electrode. As a result, a structure in which a plurality of fine particles are distributed in a plane parallel to the electrode surface is formed. This state is schematically shown in FIG. FIG. 2 is a schematic diagram showing a color-forming state of the color-forming element according to the present invention.
FIG. 2 shows a state where a structure is formed in which the fine particles are attracted to the electrode 13 and are distributed in a plane parallel to the electrode surface of the electrode 13.

When the fine particles have the above-described structure, the structure functions as a filter for incident natural light (white light), and selectively transmits visible light in a certain wavelength region (selective transmission). ). As a result, a color corresponding to the wavelength of the selectively transmitted light is observed, that is, the element appears to be colored.

When the application of the voltage between the electrodes is released, the structure of the fine particles is destroyed, so that the coloring of the element is not observed. That is, by applying and releasing the voltage between the electrodes, it is possible to reversibly transition between the colored state and the non-colored state.

In the above description, a case has been described where a structure in which fine particles are arranged in layers is formed near the electrode. However, the present invention is not limited to this structure. For example, a structure in which fine particles are stacked in the electrode interval direction may be used.

In the present invention, the voltage waveform applied between the device electrodes is not particularly limited as long as a desired color can be obtained. However, a positive-negative symmetric voltage waveform in which the positive peak value and the negative peak value are equal is not preferable. The reason for this is that when a voltage having such a waveform is applied, the fine particles vibrate in the normal direction of the electrode surface, and a structure capable of exhibiting the selective transmission function and selective reflection function of the light cannot be formed. Because there is. However, a positive-negative symmetric voltage waveform can be used when the fine particle structure in the color-developed state is quickly destroyed.

[0026]

The details of the present invention will be described below with reference to examples.

Embodiment 1 FIG. 3 schematically shows the structure of a color-forming element according to this embodiment. In FIG. 3, reference numerals 21 and 22 denote glass substrates. 2
Reference numerals 3 and 24 denote ITO electrodes (size = 1 cm × 1 cm). 25 and 26 are insulating films, which are polyimide thin films. The polyimide thin film 25 has been rubbed in the + x-axis direction. The polyimide thin film 26 is subjected to a rubbing process in the −x-axis direction. 27 is a mixture comprising an insulating fluid and fine particles. In this embodiment, the particles are 3 μm in diameter.
(Trade name: Micropearl BB, manufactured by Sekisui Fine Chemical Co., Ltd.). A nematic liquid crystal (trade name BL9, manufactured by Merck) was used as an insulating fluid. The gap between the electrodes is 5 μm. In FIG. 3, the display of the spacer for maintaining the gap distance is omitted.

[0028] The above mixture is 1 mg of polymer peas.
And 5 mg of liquid crystal were mixed, and then subjected to ultrasonic treatment (processing time = 30
Second) to uniformly disperse the polymer beads in the liquid crystal. The response of the obtained device was observed. Observation of white light transmitted through the mixture 27 in a state where no voltage was applied, no specific color was observed.

Next, a rectangular wave shown in FIG. 4 was applied between the electrodes 23 and 24. The electrode 23 is grounded. When white light transmitted through the mixture 27 was observed with the rectangular wave applied, bright blue was observed over the entire electrode region. That is, the device was observed to emit blue light.

FIG. 5 shows this state. FIG. 5 is a schematic diagram showing a color-developing state, and shows a state in which the color-developing element is observed from the upper surface of one substrate. The square PQRS is the glass substrate 31, and the square ABCD is the electrode region 32, and the entire surface of the electrode region has developed a bright blue color. In FIG. 5, the region emitting blue light is indicated by oblique lines. Note that such blue color began to appear 10 msec after the start of the rectangular wave application.

When a mechanical vibration was applied to the device while the rectangular wave was applied, the blue color did not disappear. However, when the rectangular wave application was released, the blue color disappeared. Thereafter, when the application and release of the rectangular wave were alternately repeated, a state in which blue was developed and a state in which blue was not developed could be formed alternately over the entire electrode region.

The behavior of the polymer beads before and after the application of the rectangular wave shown in FIG. 4 was observed with an optical microscope. Before the application of the rectangular wave, it was observed that the polymer beads were dispersed in the electrode spacing direction and in the electrode plane direction. When a rectangular wave was applied, it was observed that the polymer beads dispersed between the electrodes formed a structure arranged almost regularly in a plane parallel to the electrode surface. When the structure was formed, it was confirmed that the electrode region emitted the blue color.

Embodiment 2 The color-forming element in this embodiment is the same as the element used in Embodiment 1. In this embodiment, a rectangular wave shown in FIG. 6 was applied between the electrodes. The electrode 23 is grounded.

In the state where the rectangular wave is applied, the mixture 27
When the white light transmitted through the electrode was observed, it was observed at first that a vivid blue color was developed on the entire surface of the electrode region, but the blue color region was gradually narrowed. This situation will be described with reference to FIGS. 7 (a) to 7 (c).

FIG. 7A shows a state in which the element is observed from the upper surface of the substrate immediately after the rectangular wave is applied. Square AB
CD indicates the electrode region 32, and all the electrode regions have developed a vivid blue color (in the figure, the blue color region is indicated by oblique lines). As the rectangular wave application was continued, it was observed that the region emitting blue color gradually decreased. FIG. 7B shows this state. In FIG. 7 (b), the region emitting blue color is a rectangle ABEF, and a rectangle FEF.
The region indicated by ECD does not emit blue (a specific color is not observed). When the application of the rectangular wave was continued, it was observed that the region for emitting blue color became narrower. FIG. 7C shows the state. In FIG. 7 (c), the region emitting blue color is the square ABGH, and the square HGCD
Is not blue. However, in a part of the area ABJI close to the electrode edge of the square ABGH, areas that developed red and green were mixed. When the state of FIG. 7C was formed, the rectangular wave application was released. As a result, no color development was observed.

The state between the device electrodes in the state shown in FIG. 7C was observed with an optical microscope. As a result, the area indicated by the square HGCD (the area not colored blue)
Almost no polymer beads were observed. In the region indicated by the square ABGH (the region emitting blue color), the polymer beads are almost regularly arranged in a plane parallel to the electrode surface, and the -x shown in FIG.
A state of moving in the axial direction was observed. The moving speed of the polymer beads was about 90 μm / sec. This size was almost equal to the speed at which the border line between the blue coloring region and the non-coloring region moved with the narrowing of the blue coloring region. As the observation was continued, it was observed that all the polymer beads confirmed within the visual field of the microscope moved out of the visual field.
On the other hand, the region ABJI forms a structure in which polymer beads continuously transported from a region corresponding to the square ABGH (a region where red and green colors are mixed) are densely stacked. Was observed.

Further, in the present embodiment, the device was subjected to mechanical vibration while the rectangular wave was applied, but the blue color did not disappear. However, when the rectangular wave application is released,
The blue color disappeared. Thereafter, when the application and release of the rectangular wave were alternately repeated, a state in which blue was developed and a state in which blue was not developed could be formed alternately over the entire electrode region. However, as the rectangular wave was repeatedly turned on / off, the region for emitting blue color gradually became narrower.

Example 3 In this example, a rectangular wave shown in FIG. 8 was applied to the element in the state shown in FIG. 7C described in Example 2. The electrode 23 is grounded. When white light transmitted through the mixture 27 was observed with the rectangular wave applied, it was observed that the region emitting vivid blue gradually expanded. This situation will be described with reference to FIGS. 7 (c) to 7 (e).

FIG. 7C shows a state in which the element is observed from the upper surface of the substrate immediately after the rectangular wave is applied. FIG. 7 (c)
Is a square ABGH (in the figure, a region emitting blue color is indicated by oblique lines). The square HGCD does not emit blue. However, square ABG
In a part of the region ABJI close to the electrode edge of H, a region emitting red or green was mixed. The square ABCD indicates an electrode region.

When the application of the rectangular wave was further continued, it was observed that the region emitting blue color gradually spread and spread over the entire electrode region ABCD. FIG. 7E shows this state. When the state of FIG. 7E was formed, the rectangular wave application was released. As a result, the blue color disappeared.

The state between the device electrodes in the state shown in FIG. 7D was observed with an optical microscope. As a result, in the region indicated by the square ABLK (the region emitting blue color), the polymer beads are arranged almost regularly in a plane parallel to the electrode surface, and in the + x-axis direction shown in the drawing. It was observed that it was moving. The moving speed of the polymer beads was about 9 μm / sec. This size was almost equal to the speed at which the boundary line between the blue coloring region and the non-coloring region moved as the blue coloring region became wider. On the other hand, in the area shown by the area square KLCD (area not emitting blue color), polymer beads could not be confirmed at first,
It was observed that the polymer beads were gradually transported from the region corresponding to the square ABLK.

Further, in this embodiment, mechanical vibration was applied to the element while the rectangular wave was applied, but the blue color did not disappear. However, when the rectangular wave application is released,
The blue color disappeared. Thereafter, when the application and release of the rectangular wave were alternately repeated, a state in which blue was developed and a state in which blue was not developed could be formed alternately over the entire electrode region. However, as the rectangular wave was repeatedly turned on / off, the area for emitting blue color gradually became wider.

As described above, the embodiment of the present invention has been described by taking as an example a color-forming element capable of reversibly changing between a color-forming state and a non-color-forming state by an electric signal. However, these elements can be two-dimensionally arranged and applied to a color display element, an advertising panel, an optical shutter, and the like. Alternatively, application to an optical element such as a wavelength conversion element or a photonic crystal is also applicable.

[0044]

As described above, according to the present invention,
It is possible to provide a coloring element capable of transitioning between a coloring state and a non-coloring state by an electric signal and maintaining the coloring state even when exposed to mechanical vibration, and a coloring method thereof.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a non-color-forming state of a color-forming element according to the present invention.

FIG. 2 is a schematic diagram illustrating a color development state of a color development element according to the present invention.

FIG. 3 is a schematic view showing a color-forming element according to Example 1.

FIG. 4 is a diagram showing electric signals for driving an element used in the first embodiment.

FIG. 5 is a schematic diagram showing a color development state in Example 1.

FIG. 6 is a diagram showing an electric signal for driving an element used in Example 2.

FIG. 7 is a schematic diagram showing a color development state in Examples 2 and 3.

FIG. 8 is a diagram showing an electric signal for driving an element used in Example 3.

[Explanation of symbols]

 11, 12 Transparent substrate 13, 14 Transparent electrode 15 Insulating fluid 16 Fine particles 17 Voltage applying means 21, 22 Glass substrate 23, 24 ITO electrode 25, 26 Insulating film 27 Mixture 28 Voltage applying means 31 Glass substrate 32 Electrode area

Claims (16)

[Claims] 1. A pair of transparent substrates having transparent electrode layers opposed to each other with a predetermined gap therebetween, a plurality of fine particles filled between the substrates and having a size smaller than the predetermined gap, and visible light. A mixture comprising an insulating fluid having transparency and a color-developing device comprising voltage applying means for applying a voltage between the electrodes, wherein the voltage applying means applies a voltage between a pair of electrodes to form the plurality of electrodes. A color-forming element, wherein the color-forming element forms a structure in which fine particles are distributed in a plane parallel to the electrode surface, and emits light by entering light into the mixture having the structure. 2. The color-forming element according to claim 1, wherein the mixture having the structure emits a color in a visible light region by selectively transmitting light incident on the mixture. 3. The color-forming device according to claim 1, wherein the mixture having the structure emits a color in a visible light region by selectively reflecting light incident on the mixture. 4. The color developing device according to claim 1, wherein said insulating fluid is a liquid crystal. 5. The color developing device according to claim 1, wherein the fine particles do not dissolve in the insulating liquid. 6. The color developing device according to claim 1, wherein said fine particles are made of an organic substance. 7. The color-forming element according to claim 1, wherein said fine particles have a spherical shape. 8. The color developing device according to claim 1, wherein the size of the fine particles is 10 μm or less. 9. The color developing device according to claim 1, wherein an insulating film is provided on at least one surface of the pair of electrodes. 10. The color developing device according to claim 4, wherein the insulating film is subjected to a liquid crystal alignment treatment. 11. The color developing device according to claim 10, wherein said liquid crystal alignment processing is a horizontal alignment processing. 12. A pair of transparent substrates each having a transparent electrode layer opposed to each other with a predetermined gap, a plurality of fine particles filled between the substrates and having a size smaller than the predetermined distance, and visible light. A mixture of an insulating fluid having permeability and a voltage applying means for applying a voltage between the electrodes, wherein the color developing element has a predetermined voltage via the voltage applying means between the pair of electrodes. Is applied to form a structure in which the plurality of fine particles are distributed in a plane parallel to the electrode surface, and the mixture is colored by entering light into the mixture having the structure. Coloring method of the coloring element. 13. The method of claim 12, wherein the mixture having the structure selectively emits light incident on the mixture to produce a color in a visible light region. 14. The color forming method according to claim 12, wherein the mixture having the structure causes a color in a visible light region to be colored by selectively reflecting light incident on the mixture. 15. The color forming method according to claim 12, wherein the peak value of the predetermined voltage is not equal to the peak value of the positive side. 16. The method according to claim 12, wherein the insulating fluid is a liquid crystal.