KR101180118B1 - Display method and device - Google Patents

Abstract

The present invention relates to a display method and a display device for displaying a color of a specific wavelength or realizing a specific light transmittance using photonic crystallinity, wherein an electric field applied to generate a color of a specific wavelength or to implement a specific light transmittance is applied. Provided are a display method and a display device in which a color or a specific light transmittance of a specific wavelength is still maintained even if it disappears.

Description

Display method and device {DISPLAY METHOD AND DEVICE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to a technique for maintaining the spacing between particles in a display method and apparatus using photonic crystallinity.

Recently, as research and development on next-generation displays have been actively conducted, various display means have been introduced. An example of a next-generation display is electronic ink. The electronic ink is a display that displays the specific color by applying an electric field to particles of a specific color (for example, black and white, respectively) having negative charge and positive charge, respectively, and can maintain display information even when the applied voltage is cut off. It has the advantage of minimizing consumption. However, the electronic ink has a limitation in that it is difficult to express various colors because the color of the particles is fixed to a specific color, and there is a limitation that the display switching speed is not suitable for displaying a moving image.

Various methods have been proposed to fundamentally solve the problems of the conventional next generation display, and among them, a method of using the principle of photonic crystal can be considered.

Photonic crystals refer to materials or crystals having a color corresponding to a specific wavelength range by reflecting only light of a specific wavelength range among light incident by a regularly arranged microstructure, and transmitting light of the remaining wavelength range. Representative examples of photonic crystals include butterfly wings and beetle shells. Although they do not contain a pigment, they contain a unique photonic crystal structure, and thus they can give a unique color.

As described above, there is a problem in that the applied electric field must be maintained in order to maintain a specific color or maintain a specific pattern in order to express various colors by adjusting an electric field applied when expressing various colors using photonic crystallinity. Therefore, in the display method and apparatus using the photonic crystallinity, it is necessary to keep the color of the specific wavelength as it is even if the applied electric field disappears.

The present invention relates to a display method and a display device for displaying a color of a specific wavelength or realizing a specific light transmittance using photonic crystallinity, wherein an electric field applied to generate a color of a specific wavelength or to implement a specific light transmittance is applied. It is an object of the present invention to provide a display method and a display device in which a color or a specific light transmittance of a specific wavelength is still maintained even if it disappears.

According to an aspect of the present invention, the color of light reflected from the particles is variable by applying an electric field in a state where a plurality of particles are dispersed in a solvent and controlling at least one of the intensity and the direction of the electric field to control the spacing of the particles. A display method is provided so that the display device can display an electric field in which the particles move in the solvent so that the spacing of the particles reaches a specific range. And blocking the applied electric field maintains the spacing of the particles in the solvent within the specified range.

According to one embodiment, as the electric field is applied, the electrical force generated between the electric field and the particles to cause electrophoresis for the particles and the electrical force generated between the plurality of particles interact with the As the spacing of the particles reaches the specific range, as the spacing of the particles reaches the specific range, light of a specific wavelength is reflected from the plurality of particles.

According to one embodiment, at least one of the particles and the solvent has an electrical polarization characteristic, the electrical polarization is induced when an electric field is applied and the amount of electrical polarization changes as the applied electric field changes.

According to one embodiment, at least one of the particles and the solvent comprises a material that is electrically polarized by any one of electron polarization, ion polarization, interfacial polarization and rotational polarization.

According to one embodiment, the solvent comprises a material having a polarization index of 1 or more.

According to one embodiment, as the electric field is applied, the electrical force generated between the electric field and the particles to cause electrophoresis for the particles, the electrical force generated between the plurality of particles and the electrical polarization The electrical force generated by the interaction interacts so that the spacing of the particles reaches the specific range, and light of a certain wavelength is reflected from the plurality of particles as the spacing of the particles reaches the specific range.

According to one embodiment, blocking the applied electric field maintains the spacing of the particles in the solvent for more than a certain time within the specific range.

According to one embodiment, the threshold is determined by adjusting the viscosity of the solvent to control the migration resistance of the particles in the solvent.

According to one embodiment, the threshold is determined by adjusting the specific resistance of the particles and the solvent to control the migration resistance of the particles in the solvent.

According to one embodiment, the threshold is determined by adding an additive to the solvent to adjust the migration resistance of the particles in the solvent.

According to one embodiment, the additive comprises an anchoring group having affinity with the solvent.

According to one embodiment, the anchor is hydrogen bonded to the surface of the particle.

According to one embodiment, the fixing group is an epoxy group, an epoxide group, a carboxyl group, an anhydride group, an aldehyde group, an aldehyde group, a ketone group, At least one of an ester group and an alcohol group.

According to one embodiment, the fixing group is dioxolane, sorbate, 3-ethyl-6,7-dihydroxy-1,5-dioxocan-3-yl acetate and tetrahydro-4-hydroxymethyl-2 At least one of (2- (hydroxymethyl) -1,3-dioxolan-2-yl) furan-3-yl acetate.

According to one embodiment, the additive comprises a polymer that causes the interparticle steric effect.

According to one embodiment, the polymer comprises an alkyl group or alken group having 10 to 350 carbon atoms.

According to one embodiment, the additive comprises an oxyethylene lauryl ether or polysorbate-based compound.

According to an aspect of the present invention, a display portion including a solution in which a plurality of particles are dispersed in a solvent, an electrode for applying an electric field to the display portion, and the intensity of the electric field applied to the plurality of particles and the solvent through the electrode, There is provided a display device including a control unit which controls a distance of the plurality of particles by adjusting at least one of a direction, an application number, an application time, and an application position to variably display the color of light reflected from the particles on a display unit. Applying an electric field above a threshold required to move the particles in the solvent causes the particles to move in the solvent such that the spacing of the particles reaches a certain range, and blocks the applied electric field in the solvent. The spacing of the particles is maintained within the specific range.

According to the present invention configured as described above, by controlling the wavelength of the light reflected from the particles, the effect of being able to implement a full spectrum of structural colors (full spectrum) is achieved.

In addition, according to the present invention, even after the electric field, which serves to control the spacing of the particles, is blocked, the spacing of the particles can be maintained in a controlled state, thereby realizing a more stable display and implementing a display that is continuously driven. The effect of being able to reduce the power consumed in applying the electric field is achieved.

According to the present invention, the color of the continuous wavelength can be realized by reflecting the light of the continuous wavelength rather than the color (hue) by the mixed color of R, G, and B.

According to the present invention, a display method and an apparatus excellent in viewing angle characteristics and response time can be provided.

The above advantages, features and objects of the present invention and other advantages, features and objects will become apparent upon reading the following detailed description of the invention with reference to the accompanying drawings.
1 and 2 are views exemplarily illustrating a configuration of particles included in a display unit according to an exemplary embodiment of the present invention.
3 is a diagram illustrating a configuration in which particles or a solvent are polarized as an electric field is applied according to an embodiment of the present invention.
4 is a diagram illustrating unit polarization characteristics by an asymmetrical arrangement of molecules according to an embodiment of the present invention.
5 is a diagram showing hysteresis curves of the dielectric, ferroelectric, and superphase dielectrics.
6 is a view exemplarily showing a material having a perovskite structure that may be included in particles or a solvent according to an embodiment of the present invention.
7 is a view conceptually showing a configuration for controlling the spacing of particles according to an embodiment of the present invention.
8 is a view conceptually showing a configuration for controlling the spacing of particles according to an embodiment of the present invention.
9 is a diagram illustrating a configuration of a display device according to an exemplary embodiment of the present invention.
10 and 11 are views conceptually illustrating a configuration of a display device according to example embodiments.
12 is a diagram illustrating a configuration of a display device including a plurality of electrodes according to an exemplary embodiment of the present invention.
13 and 14 illustrate graphs and photographs of light reflected from particles as a result of performing an experiment in which an electric field is applied in a state in which charged particles are dispersed in a solvent having electrical polarization characteristics, according to an embodiment of the present invention. It is a figure which shows.
15 and 16 are graphs showing wavelengths of light reflected from particles when an electric field is applied in a state in which charged particles are dispersed in various solvents having different polarity indexes according to one embodiment of the present invention. It is a figure which shows.
17 and 18 are graphs and photographs showing light reflected from particles when an electric field is applied in a state in which particles having charge and electric polarization characteristics are dispersed in a solvent according to one embodiment of the present invention. Drawing.
19 is a view showing experimental results of the configuration for implementing a transparent display according to an embodiment of the present invention.
20 is a diagram illustrating a result of experimenting with display performance according to an observation angle of a display device according to an exemplary embodiment (that is, an experiment result regarding a viewing angle of a display).
21 and 22 are added to the solvent according to an embodiment of the present invention by adding a predetermined additive in the present invention so that the spacing of the particles can be maintained in a controlled state even after the electric field that serves to control the particle spacing is blocked It is a figure which shows the experiment result about the structure to make as a graph and a photograph.
(A), (b), (c) of FIG. 23 are the figures which showed the color shift which each of FIG. 41 (a), (b), (c) shows by color coordinate.
24 to 26 is according to an embodiment of the present invention by adding a predetermined additive to the solvent according to an embodiment of the present invention the present invention is the gap between the particles even after the electric field that serves to control the particle spacing is blocked It is a figure which shows the experiment result about the structure which can be maintained as it is.
27 is a view showing color coordinates according to the change in the number of hydrogen bonding sites of the fixing group.

DETAILED DESCRIPTION The following detailed description of the invention refers to the accompanying drawings that show, by way of illustration, specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. It should be understood that the various embodiments of the present invention are different, but need not be mutually exclusive. For example, certain features, structures, and characteristics described herein may be implemented in other embodiments without departing from the spirit and scope of the invention in connection with an embodiment. It is also to be understood that the position or arrangement of the individual components within each disclosed embodiment may be varied without departing from the spirit and scope of the invention. When the expression "according to one embodiment" or "in one embodiment" appearing throughout this specification, it is understood that the shapes, structures, properties, manners, configurations, etc. described in one particular embodiment are necessarily all embodiments. The same does not mean that the same applies, nor does it mean that the shapes, structures, properties, methods, configurations, etc. described in the specific embodiments are applied only in this specific embodiment. In addition, the shapes, structures, features, characteristics, configurations, etc. used in certain embodiments may be combined with other embodiments.

Also, the singular forms of nouns used herein do not exclude the presence of a plural form. Also, as used herein, the terms “comprises” and “haves” and “comprises” and their utilization do not exclude the presence of elements or steps other than those described. In addition, the order of the steps of the process used herein is not limited as described herein but other orders are possible. As used herein, an ordinal number "first, second, third," or the like only distinguishes elements or modes or steps from each other and does not give any order meaning.

The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is to be limited only by the appended claims, along with the full scope of equivalents to which such claims are entitled, if properly explained. In the drawings, like reference numerals refer to the same or similar functions throughout the several views.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, in order that those skilled in the art can easily carry out the present invention.

Display part

Composition of Particles and Solvents

1 and 2 are views exemplarily illustrating a configuration of particles included in a display unit according to an exemplary embodiment of the present invention. Meanwhile, in the present specification, the display unit may refer to a portion including a solution in which a plurality of particles are dispersed in a solvent, and may also include electrodes interposed therebetween. In addition, the display device may include such a display unit. However, the present invention is not limited to the detailed configuration of the display unit or the display device, but may also include other configurations capable of realizing the technical idea of the present invention. These other configurations will be understood by those skilled in the art upon reading the following description. It may be obvious to you.

First, referring to FIG. 1, the particles 110 according to an embodiment of the present invention may be dispersed in the solvent 120 and exist in a solution state. According to one embodiment of the invention, the particle 110 may have a positive charge or a negative charge. Therefore, when an electric field is applied to the particles 110, the particles 110 may be moved (ie, electrophoresis) due to electric charges generated by the electric charges and the electric fields of the particles 110. In addition, when the plurality of particles 110 have charges of the same sign, the plurality of particles 110 do not contact each other and maintain a predetermined interval due to mutual electrical repulsion (coulomb repulsion) due to charges of the same sign. It may be arranged as is. In addition, according to an embodiment of the present invention, the particles 110 may be coated in the form of a polymer chain, such that a steric effect may be present due to disordered movement of the polymer chains between particles. Therefore, due to the intergranular hindrance effect, the plurality of particles 110 may be arranged while maintaining a predetermined interval without contacting each other.

Referring to FIG. 2, the particle 110 according to the exemplary embodiment of the present invention may be configured in the form of a core-shell 112 made of different materials as shown in FIG. As shown in (b) of FIG. 2, it may be configured in the form of a multi-core (multi-core) 114 made of heterogeneous materials, and as a cluster 116 of a plurality of nanoparticles as shown in FIG. The charge layer 118 having the above-described charge or the layer 118 exhibiting steric effect may be configured to enclose these particles. Particles according to the present invention is not limited to the above structure, it is possible to use a variety of particles and forms, such as a structure that penetrated or supported heterogeneous material in the core particles, raspberry structure, etc., the cavity such as backlight crystal structure Structures can also be used.

More specifically, the particle 110 according to an embodiment of the present invention is silicon (Si), titanium (Ti), barium (Ba), strontium (Sr), iron (Fe), nickel (Ni), cobalt (Co ), Lead (Pb), aluminum (Al), copper (Cu), silver (Ag), gold (Au), tungsten (W), molybdenum (Mo), zinc (Zn), zirconium (Zr) It may be made of a compound such as oxides, nitrides, and the like containing cow. In addition, the particle 110 according to an embodiment of the present invention comprises at least one unit of styrene, pyridine, pyrrole, aniline, pyrrolidone, acrylate, urethane, thiophene, carbazole, fluorene, vinylalcohol, ethylene glycol, ethoxy acrylate It may be made of an organic polymer or a polymer material such as PS (polystyrene), PE (polyethylene), PP (polypropylene), PVC (polyvinyl chloride), PET (polyethylen terephthalate).

In addition, the particle 110 according to an embodiment of the present invention may be configured as a form in which a material having a charge is coated on particles or clusters having no charge. For example, the surface is processed by an organic compound having particles (carboxylic acid groups, ester groups, acyl groups), the surface is processed (or coated) by an organic compound having a hydrocarbon group ( Or coated) particles, particles whose surfaces are processed (coated) by a complex compound containing halogen (F, Cl, Br, I, etc.) elements, including amines, thiols, and phosphines. Particles whose surface is processed (coated) by the coordination compound, and particles having a charge by forming radicals on the surface may correspond thereto. As such, the surface of the particle 110 may be coated with a material such as silica, a polymer, a polymer monomer, or the like, so that the particle 110 may have high dispersibility and stability in the solvent 120.

Meanwhile, the diameter of the particle 110 may be several nm to several hundred μm, but is not necessarily limited thereto. When the particles are arranged at a constant distance by an external electric field, the refractive index of the particle may be changed by the Bragg law. It can be set to the size of the particles that can be included in the photonic crystal wavelength range of the visible region in conjunction with the refractive index of the solvent.

Meanwhile, according to an embodiment of the present invention, the particle 110 may be configured to reflect light of a specific wavelength, that is, have a unique color. More specifically, the particle 110 according to an embodiment of the present invention may have a specific color through oxidation control or coating of inorganic pigments, pigments, and the like. For example, Zn, Pb, Ti, Cd, Fe, As, Co, Mg, Al, etc., including chromophores, in the form of oxides, emulsions, lactates, etc., are coated on the particles 110 according to the present invention. As the dye coated on the particles 110 according to the present invention, a fluorescent dye, an acid dye, a basic dye, a mordant dye, a sulfide dye, a bat dye, a disperse dye, a reactive dye, and the like may be used. In addition, according to an embodiment of the present invention, the particle 110 may be a material having a specific structural color to display a specific color. For example, particles such as silicon oxide (SiO _x ) and titanium oxide (TiO _x ) may be formed to be uniformly arranged at regular intervals in a medium having a different refractive index to reflect a light having a specific wavelength.

In addition, according to an embodiment of the present invention, the solvent 120 may also be configured to reflect light of a specific wavelength, that is, have a unique color. More specifically, the solvent 120 according to the present invention may include a material having an inorganic pigment, a dye or a material having a structural color by photonic crystal.

In addition, according to an embodiment of the present invention, at least one of a fluorescent material, a phosphor, and a light emitting material may be included in the particles or the solvent to maximize the effect of the present invention.

According to an embodiment of the present invention, the solvent 120 is dispersed in the solvent 120 in order to ensure that the particles 110 are uniformly dispersed in the solvent 120 to ensure colloidal stability. An additive such as a dispersant may be added to the solvent, or the difference in specific gravity between the particles 110 and the solvent 120 may be less than or equal to a predetermined value, the viscosity of the solvent 120 may be greater than or equal to a predetermined value, and the particles 110 The value of the electrokinetic potential (ie, zeta potential) of the colloidal solution consisting of and a solvent 120 may be higher than a predetermined value.

In addition, according to an embodiment of the present invention, in order to increase the reflected light intensity of the visible light region generated through the predetermined arrangement in the solvent 120 when the particle 110 is applied to the electric field, the solvent 120 and the particle 110. The refractive index difference of) may be greater than or equal to a predetermined value, and the size of the particle 110 may be related to the refractive index of the particle and the refractive index of the solvent by Bragg's Law to include the photonic crystal wavelength band of the visible region. Can be set to

For example, the absolute value of the interfacial potential of the colloidal solution may be 10mV or more, the difference in specific gravity of the particle 110 and the solvent 120 may be 5 or less, the difference in the refractive index of the particle 110 and the solvent 120 0.3 or more, the particle size may be between 100nm ~ 500nm, but is not limited thereto.

Interparticle  Attraction: electric Polarization  characteristic

In addition, according to an embodiment of the present invention, the solution containing the solvent in which the particles included in the display portion is dispersed may have a variable electrical polarization characteristic (the electrical polarization amount is changed when an electric field is applied), The electrical polarization characteristic of such a solution may be at least one of the particles or the solvent constituting the solution exhibits electrical polarization characteristics or electrical polarization characteristics by the interaction of the particles and the solvent in the solution. In addition, a solution (consisting of particles and a solvent) exhibiting electrical polarization characteristics may be electrically polarized by any one of electron polarization, ion polarization, interfacial polarization, and rotational polarization as an external electric field is applied due to an asymmetrical charge distribution of atoms or molecules. It may include a substance to be.

Therefore, at least one of the particles or the solvent or the solution composed thereof according to an embodiment of the present invention may cause electric polarization when an electric field is applied, and the induced electric polarization as the intensity or direction of the applied electric field is changed. The amount may change. As such, the electric polarization amount changes as the electric field changes may be referred to as a variable electric polarization characteristic. In the present invention, the greater the amount of electric polarization induced when the electric field is applied, the more advantageous, because the interaction force between the particles is greater by the electric polarization of at least one of the particles, solvents, solutions as the electric field is applied This is because the spacing between particles can be arranged more uniformly.

3 is a diagram illustrating a configuration in which particles or a solvent are polarized as an electric field is applied according to an embodiment of the present invention.

Referring to (a) and (b) of FIG. 3, when the external electric field is not applied, the particles or the solvent maintain the electrical equilibrium to exhibit electrical polarization characteristics, but when the external electric field is applied, As the charge moves in a predetermined direction, polarization may be induced to polarize the particles or the solvent. (C) and (d) of FIG. 3 show that unit polarization is generated by electrically asymmetrical components constituting the particles or the solvent. When the electric field is not applied, the unit polarization is disordered. The total electric polarization does not appear or shows a small value, but when an electric field is applied from the outside, particles or solvents having unit polarization may be rearranged in a predetermined direction according to the direction of the external electric field so that there is no unit polarization as a whole. Compared to the case of FIG. 3 (b) of applying an electric field in a state, a relatively large polarization value may be exhibited. According to one embodiment of the present invention, the unit polarization shown in (c) and (d) of FIG. 3 may occur in an asymmetrical arrangement of electrons or ions or in an asymmetric structure of molecules, and due to such unit polarization, an external electric field is applied. If not, a fine residual polarization value may appear.

4 is a diagram illustrating unit polarization characteristics by an asymmetrical arrangement of molecules according to an embodiment of the present invention. More specifically, Figure 4 shows the case of water molecules (H ₂ O) by way of example, in addition to the water molecules Trichloroethylene, Carbon Tetrachloride, Di-Iso-Propyl Ether, Toluene, Methyl-t-Bytyl Ether, Xylene, Benzene , DiEthyl Ether, Dichloromethane, 1,2-Dichloroethane, Butyl Acetate, Iso-Propanol, n-Butanol, Tetrahydrofuran, n-Propanol, Chloroform, Ethyl Acetate, 2-Butanone, Dioxane, Acetone, Metanol, Ethanol, Acetonitrile, Acetic Acid , Dimethylformamide, Dimethyl Sulfoxide, Propylene carbonate, N, N-Dimethylformamide, Dimethyl Acetamide, N-Methylpyrrolodone and the like may exhibit unit polarization characteristics due to the asymmetry of molecular structure, and thus may be employed as a material constituting the particles or solvent according to the present invention. Could be. For reference, the polarity index (polarity index) used to compare the polarization characteristics of the material, in contrast to the polarization characteristics of the water (H ₂ O) may be an index indicating the relative degree of polarization of the material, one of the present invention According to an embodiment, the solvent may include a material having a polarity index of 1 or more.

In addition, the particles or the solvent according to an embodiment of the present invention, as the external electric field is applied, the electric polarization of the ions or atoms is further induced to increase the polarization amount, even if the external electric field is not applied, the residual polarization amount is present It may include ferroelectric materials that remain hysteresis depending on the direction of electric field application, and when the external electric field is applied, ionic or atomic polarization is additionally induced to increase the amount of polarization, but when no external electric field is applied. It may include superparaelectric materials that do not leave residual polarization and hysteresis. Referring to FIG. 5, a hysteresis curve according to an external electric field of the paraelectric material 510, the ferroelectric material 520, and the superphase dielectric material 530 may be checked.

In addition, the particles or the solvent according to an embodiment of the present invention may include a material having a perovskite structure, a material having a perovskite structure, such as ABO ₃ PbZrO ₃ , PbTiO ₃ , Pb (Zr, Ti) O ₃ , SrTiO ₃ BaTiO ₃ , Examples thereof include (Ba, Sr) TiO ₃ , CaTiO ₃ , LiNbO _3, and the like.

6 is a view exemplarily showing a material having a perovskite structure that may be included in particles or a solvent according to an embodiment of the present invention. Referring to Figure 6, the position of PbZrO ₃ (or PbTiO ₃₎ PbZrO depending on the direction of the external electric field is applied to the _third (or PbTiO ₃₎ Zr (or Ti) (that is, B of the ABO ₃ structure) in the This may cause the polarity of the entire PbZrO ₃ (or PbTiO ₃ ) to be changed. Accordingly, asymmetric electron distribution may be formed by the movement of atoms or ions, thereby forming unit polarization. If such unit polarization is present, the variable electric power is greater when an external electric field is applied than when only the electron polarization is present. Can cause polarization values.

In addition, according to an embodiment of the present invention, since the reflected light control and transmittance control effects of the present invention can be maximized as the interparticle arrangement becomes better, the microparticles are dispersed in the non-conductor fluid so that the electro-rhoheology (ER) characteristics By using a fluid indicating or even a fluid indicating a maximum electro- rheology (GER), such as ferroelectric particles coated with an insulator can maximize the effect of the present invention.

Further, speaking of the aspect of the electrical polarization, if no electric field is applied as the first example, at least one of each molecule and each particle of the solvent has no electric polarization amount, but if the electric field is applied to each molecule and each At least one of the particles is electrically polarized, whereby at least one of the total electrical polarization amount of the plurality of particles and the total electrical polarization amount of the solvent may be increased. In a second example, even if no electric field is applied, at least one of each molecule and each particle of the solvent is electrically polarized, but at least one of the total amount of electrical polarization of the solvent and the total amount of electrical polarization of the plurality of particles is zero. When an electric field is applied, at least one of the total electric polarization amount of the plurality of particles and the total electric polarization amount of the solvent may be increased. As a third example, even if no electric field is applied, at least one of each molecule and each particle of the solvent is electrically polarized such that at least one of the total amount of electrical polarization of the solvent and the total amount of electrical polarization of the plurality of particles is zero. When the electric field is applied, and at least one of the total electric polarization amount of the plurality of particles and the total electric polarization amount of the solvent may be a second value greater than the first value.

Interparticle  Repulsive force: Coulomb effect  Or steric hindrance effect

According to an embodiment of the present invention, the surface of the particles included in the display device is charged with a charge of the same sign to form a coulomb repulsive force, or a polymer chain structure, a functional group, an additive, or the like on the surface of the particles. The steric hindrance repulsion may be formed by forming a three-dimensional structure and the like.

In addition, according to an embodiment of the present invention, in order to maximize the interparticle repulsion, the charge of the same sign and the coating of the particles in the form of a three-dimensional structure may also cause the cologne repulsion and steric repulsion at the same time.

In addition, according to one embodiment of the present invention, the particles include a material that is electropolarized and the surface of the particles through the steric hindrance repulsion, but the charge is weak to configure the electrophoretic effect to minimize the particle or solution, The amount of electric polarization changes according to the external electric field, effectively causing local short range attraction between particles, and the local short range steric hindrance repulsion between particles is effectively caused by the three-dimensional structure formed through particle surface treatment. Although generated, it is possible to minimize a phenomenon that charged particles are attracted to the electrode by long range electophoretic force caused by an external electric field. That is, since the charge is not processed on the surface of the particles, the phenomenon of electrophoresis toward either electrode by an external electric field can be minimized. In order to give a steric hindrance repulsive force, an organic ligand can be treated on the particle surface. In addition, according to an embodiment of the present invention, in order to prevent the charged particles from being attracted to the electrode by the electrophoresis when the charged particles are used, an alternating current voltage may be used in combination.

However, the composition of the particles and the solvent according to the present invention is not necessarily limited to those listed above, but within the range in which the object of the present invention can be achieved, that is, within the range in which the spacing of the particles can be controlled by an electric field. Note that changes can be made as appropriate.

For example, in order to maximize the effect of the present invention, the difference in refractive index between the particles and the dispersed solution is increased, and when no voltage is applied, the diffuse reflection (scattering) is maximized to increase the opacity and voltage is applied to the structure color. When expressing, the reflectance of the structural color can be increased. In general, since the refractive index of the fluid does not vary greatly depending on the type, a method of maximizing the refractive index of the particles is effective, and a core / shell or raspberry structure in which two or more different materials are combined. By fabricating or the like, the above-described refractive index effect and the repulsive force effect can be maximized simultaneously.

Operating principle of the display

First, according to an embodiment of the display unit according to the present invention, when an electric field is applied to the particles and the solvent in a state in which a plurality of particles having the same sign charges are dispersed in a solvent having electrical polarization characteristics, Due to this, an electric force proportional to the intensity of the electric field and the amount of charge of the particles is applied to the plurality of particles, and thus, the plurality of particles are electrophoresis and move in a predetermined direction, thereby narrowing the spacing of the particles. On the other hand, as the spacing of the particles becomes narrower, the electrical repulsive force generated between the plurality of particles having the same charge with each other increases, so that the spacing of the particles does not continue to be narrowed, thereby achieving a predetermined balance and thus the plurality of particles. The particles of can be arranged at regular intervals. In addition, due to the electrical polarization characteristics of the solvent, the solvents around the charged particles are electropolarized and influence each other. When the external electric field is applied, the electric polarization of the solvent is arranged in the direction of the external electric field. Charge-charged particles that are interrelated with electropolarization can also be arranged in the direction of an external electric field. That is, the unit polarized solvent is arranged in a predetermined direction by the electric field applied from the outside and the electric charges of the surrounding particles, thereby forming a polarization region formed locally around the particles so that a plurality of particles are separated by a predetermined interval. It can be arranged more regularly and stably with the state maintained. According to an exemplary embodiment of the present invention, an electrical force (electrophoretic force) due to an external electric field, an electrical force (coulomb repulsion force) between particles having charges having the same sign as each other, and an electrical force due to polarization (coulomb force) A plurality of particles can be arranged regularly at a distance in which equilibrium is equal to (equilibrium). According to the above principle, the spacing of the particles can be controlled at a predetermined interval, and the plurality of particles arranged at a predetermined interval can function as a photonic crystal. Since the wavelength of the light reflected from the plurality of particles arranged regularly is determined by the spacing of the particles, the wavelength of the light reflected from the plurality of particles can be arbitrarily controlled by controlling the spacing of the particles by controlling the external electric field. . Here, the pattern of the wavelength of the reflected light depends on factors such as the intensity and direction of the electric field, the size and mass of the particles, the refractive index of the particles and the solvent, the amount of charge of the particles, the electrical polarization characteristics of the solvent or particles, and the concentration of dispersed particles in the solvent. It can appear variously.

7 is a diagram conceptually illustrating a configuration of controlling a spacing of particles according to an embodiment of the display unit according to the present invention. Referring to FIG. 7, when no external electric field is applied, the unit polarized solvent 710 around the charged particles 720 interacts with the charges of the particles, so that they are strongly arranged in the direction of the particles, and the distance from the particles is increased. In accordance with this, the unit polarized solvents 710 may be arranged in an orderly manner (see FIG. 7A). In addition, referring to FIG. 7, when an external electric field is applied, the unit polarized solvent 710 located in a region where the influence of the charge of the particles 720 is not affected (that is, a region far from the particles 720). ) Is rearranged in the direction of the electric field, and the charged particles 720 may be rearranged due to the influence of the rearranged solvents. That is, the unit polarized solvent 710 located in the region where the electrical attractive force by the charged particles is strongly acting (that is, the region adjacent to the particle 720) is the electrical attractive force due to the charge of the particles 720. Due to this, the anode or the cathode of the unit polarization may be arranged in a direction facing the particles 720, and thus the unit polarization solvent 710 of the peripheral region of the particles 720 is arranged in the direction facing the particles 720. The region, ie, the polarization region 730, can act as one large particle that is electrically polarized to interact with other surrounding polarization regions, so that charged particles 720 are spaced at a predetermined interval. It can be arranged regularly (see FIG. 7B). FIG. 7 is a schematic diagram of a solvent having residual polarization, but may be similarly applied to a solvent having an electric polarization characteristic as an electric field is applied even in the absence of residual polarization.

Next, according to an embodiment of the display device according to the present invention, when the electric field is applied to the particles and the solvent in a state in which a plurality of particles having the same charge and having the electrical polarization characteristics are dispersed in the solvent, the particles have Due to the electric charge, the electric force is applied to the plurality of particles in proportion to the intensity of the electric field and the amount of charge of the particles. Accordingly, the plurality of particles are electrophoresis and move in a predetermined direction, thereby narrowing the spacing of the particles. On the other hand, as the spacing of the particles becomes narrower, the electrical repulsive force generated between the plurality of particles having the same charge with each other increases, so that the spacing of the particles does not continue to be narrowed, thereby achieving a predetermined balance and thus the plurality of particles. The particles of can be arranged at regular intervals. In addition, the particles exhibiting electrical polarization characteristics are polarized by an electric field to be polarized in the direction of the electric field, and electrical attraction is locally generated between the plurality of polarized particles so that the plurality of particles maintain a predetermined interval. It can be arranged more regularly and stably. That is, according to the embodiments of the display device according to the present invention, the electric attraction force (electrophoretic force) due to the external electric field, the electric repulsive force (Coulomb repulsion force) between the particles having the same charge with each other and the electric attraction force due to polarization A plurality of particles can be arranged regularly at a distance at which the coulombs form an equilibrium. According to the above principle, the spacing of the particles can be controlled at a predetermined interval, and the plurality of particles arranged at a predetermined interval can function as a photonic crystal. Since the wavelength of the light reflected from the plurality of particles arranged regularly is determined by the spacing of the particles, the wavelength of the light reflected from the plurality of particles can be arbitrarily controlled by controlling the spacing of the particles. Here, the pattern of the wavelength of the reflected light depends on factors such as the intensity and direction of the electric field, the size and mass of the particles, the refractive index of the particles and the solvent, the amount of charge of the particles, the electrical polarization characteristics of the particles and the solvent, and the concentration of the dispersed particles in the solvent. It can appear variously.

8 is a view conceptually showing a configuration of controlling the spacing of particles according to an embodiment of the display unit according to the present invention. Referring to FIG. 8, when the external electric field is not applied, the particles 810 are not polarized (see FIG. 8A), but when the external electric field is applied, electricity of the material contained in the particles 810 is applied. Due to the polarization characteristic, the particles 810 may be polarized, and thus the particles 810 may be regularly arranged with a predetermined interval (see FIG. 8B).

In the above embodiments of the present invention, the greater the electrical polarization value of the solvent or particles, the greater the degree of interaction between the polarization zone 730 or the polarized particles 810, so that the particles are arranged more regularly. You can do it. 8 is shown as a particle having no residual polarization, but may be similarly applied to particles having a characteristic in which electrical polarization changes as an electric field is applied even in a state where residual polarization is present.

In the above embodiments, the case in which the particles or the solvent have the electrical polarization characteristics has been described, but it is understood that the particles or the solvents according to the present invention do not necessarily have the electrical polarization characteristics. That is, even when a particle or a solvent does not have electrical polarization characteristics, if the particle has a charge, the plurality of electric charges due to an external electric field and the electric repulsive force between a plurality of particles having a charge of the same sign are balanced with each other. The particles of may be arranged regularly, and the plurality of regularly arranged particles may form a photonic crystal that reflects light of any wavelength.

In the embodiment of the present invention, the spacing between the plurality of particles can be maintained at a constant interval by the balance of the attractive force and the repulsive force between the particles as described above according to the external electric field, but the attractive force and the repulsive force can effectively act between the near particles. However, since the interaction force may not be effective between particles over a certain distance, the arrangement of particles according to the present invention may exhibit short range ordering rather than long range ordering in three dimensions. . In addition, the reflected light reflected by the set of short-range arrays having slightly different arrangements may exhibit the reflected light characteristic having a significantly improved viewing angle dependency compared to the photonic crystal light reflected by the conventional photonic crystal array. In addition, in the above embodiments, the case in which the particles have a charge has been described, but it is noted that the particles according to the present invention do not necessarily have a charge. That is, even if a particle has an electric polarization characteristic and has a three-dimensional structure capable of generating steric hindrance repulsion even when the particle has no electric charge, the electrical attraction between adjacent particles caused by the electric polarization caused by an external electric field and The plurality of particles may be regularly arranged at a distance where the repulsive force due to the steric hindrance effect is balanced, and the plurality of regularly arranged particles may form a photonic crystal that reflects light of any wavelength. In other words, when a plurality of particles exhibit a mutual steric effect, as the electric field is applied, the electrostatic attraction acting between the particles by the variable electric polarization characteristic and the steric impulse acting between the particles are mutually mutual. As a result, the spacing between the particles reaches a specific range, and as the spacing between the particles reaches the specific range, light of a specific wavelength is reflected from the plurality of particles, thereby realizing a specific color.

Keep spacing of particles

On the other hand, according to an embodiment of the present invention, even after the electric field which serves to control the spacing of the particles is blocked, the spacing of the particles can be maintained in a controlled state. That is, according to an embodiment of the present invention, after dispersing a plurality of particles in a solvent, the photonic crystal display, which can control the reflected light by adjusting the spacing of the particles according to an electric field, is applied to the particles by restricting the movement of the particles in various ways. The spacing of particles controlled by the electric field, that is, the photonic crystal color embodied on the display unit may be continuously maintained even after the electric field is blocked.

Hereinafter will be described a specific embodiment for maintaining the particle interval after the applied voltage cut off.

(1) Additives that cause steric hindrance on the surface of particles

A predetermined additive may be added to the solvent in which the particles are dispersed to maintain particle spacing after the applied voltage is interrupted.

The additive may include a fixing group bonded to the surface of the particles by intermolecular force, and a polymer connected to the fixing group and causing an interparticle steric effect.

The fixing group is an epoxy group, an epoxide group, an carboxyl group, anhydride group, an aldehyde group, an ketone group ), An ester group, an alcohol group, and an ester group. For example, the anchoring groups are dioxolane, sorbate, 3-ethyl-6,7-dihydroxy-1,5-dioxocan-3-yl acetate and tetrahydro-4-hydroxymethyl-2 (2 It may include at least one of-(hydroxymethyl) -1,3-dioxolan-2-yl) furan-3-yl acetate.

The polymer may include at least one of an alkyl group having 10 to 350 carbon atoms and an alkene group to cause intergranular steric hindrance.

Therefore, it is preferable to use an oxyethylene lauryl ether or a polysorbate-based compound (eg, polyoxyethylene sorbitan monolaurate, polyoxyethylenesorbitan monooleate, polyoxyethylene sorbitan monostearate, etc.).

The additives comprise multiple layers of polymers. For example, the additive may be a triple layer polymer [poly (styrene) -block- (poly (ethylene-propylene) -block-poly (styrene) copolymer)], a polymer of a heterogenous hetrocyclic group including nitrogen And it may be a polymer containing an amino ester (amino ester).

These additives limit the movement of particles dispersed in the solvent.

In addition, according to an embodiment of the present invention, when the particles having a charge in the polymer having a molecular chain is dispersed, the resistance is increased in the movement of the particles in the solvent, even after the electric field applied from the outside is blocked Its position can be fixed.

In addition, according to an embodiment of the present invention, an additive including a hydrophilic group having a hydrophilic property to enable a chemical bond such as a hydrogen bond and a functional group (functional group, -OH group) on the particle surface By adding it in a solvent, the additive can be continuously adsorbed on the particle surface to form a film around the particle to stabilize the particle.

In addition, according to an embodiment of the present invention, the steric hindrance effect is caused by the alkyl group or the alkene group present in the chain of the liphophilic group (alkyl chain) having a hydrophobicity included in the additive added in the solvent of the solvent It is possible to increase the viscosity, thereby limiting the movement of the particles contained in the solvent. Furthermore, the viscosity of the solution can be further increased by adding a large amount of polymer having a complicated structure into the solvent.

That is, by adding an additive having affinity with the particles or an additive having affinity with the solvent, the particles may be restricted in movement in the solvent. In addition, by adding a polymer having a complex steric structure or chain structure as an additive in the solvent, it is possible to limit the movement of the particles by maximizing the interparticle steric effect by the complex steric structure of the additive.

(2) Formation of coating layer that induces hydrogen bonding on particle surface

Unlike the above-described addition of additives that directly induce hydrogen bonding with the particle surface, after forming a coating layer on the particle surface, color retention is possible by adding the coating layer and the additive causing the hindered effect on the solvent.

For example, the particles are coated with a polymer including a functional group that induces hydrogen bonding. Subsequently, an additive capable of hydrogen bonding with the functional group is added to the solvent. At this time, the additives form a hydrogen bond with the polymer coated on the particles, causing a steric hindrance effect, thereby limiting particle migration.

The functional group of the polymer is an epoxy group, an epoxide group, a carboxyl group, an anhydride group, an aldehyde group, a ketone group, an ester group ), Alcohol group (alcohol group) may include at least one.

The additive may include a triple layer polymer [poly (styrene) -block- (poly (ethylene-propylene) -block-poly (styrene) copolymer).

(3) additives to control the dispersibility of the particles

It is also possible to control the color retention time without increasing the viscosity of the solvent. In this case, the additive may be formed by chemical reaction with the particles to form a bond, or a material that is not physically absorbed. For example, the additive may include at least one of polyolefin, polysiloxane, and polyisobutylene. In this case, it is preferable to use an aliphatic hydrocarbon mixed with an aliphatic hydrocarbon and a halogenated hydrocarbon.

Polyolefins, polysiloxanes, and polyisobutylenes are dispersed in a solvent without being absorbed by the particles, making it difficult to move the particles. Thus, color can be maintained without changing the viscosity of the solvent. However, in order not to be absorbed by a particle | grain and to not change the viscosity of a solvent, it is preferable to use the polymer which has the number average molecular weight more than 20,000 for the said additive.

(4) Color retention by phase change of solvent

By using a phase change material as the solvent, the particle is easily moved (for example, a low viscosity liquid) to apply a voltage to adjust the distance between the particles at a predetermined distance, and light, pressure, The stimulation of temperature, chemical reactions, magnetic fields, electricity, etc. converts the state of the solution into a state in which particles are difficult to move (e.g., solid or viscous liquid). You can also keep it.

(5) voltage intensity control

In order to prevent the particles from gradually becoming disordered after the voltage interruption, the particle spacing may be kept at a constant distance by periodically applying a constant voltage.

In order to maintain the distance after the voltage cut in the above manner, it is advantageous to minimize the specific gravity of the particles and the solvent, it is also possible to coat the material with different specific gravity or to add a different specific gravity to the solvent. have.

Therefore, according to one embodiment of the present invention, particles that are regularly arranged while maintaining a predetermined interval as the electric field is applied can maintain their regular arrangement even when the electric field is blocked. Such bistability is more apparent when the amount of the additive or the molecular weight of the additive is larger, and in particular, the above effects can be increased by reducing the difference in specific gravity between the particles and the solvent. In addition, according to an embodiment of the present invention, it is possible to produce a display device having excellent display characteristics by simply including an additive in a solvent without employing a complex configuration such as a capsule, a cell, a droplet capsule, and the like, which will be described later. In addition, even if a power source for generating an electric field applied to the particles is removed, the pattern and color implemented on the display unit can be maintained for a while, thereby minimizing the power consumption of the reflective display using the photonic crystal.

[Operation principle of display device]

9 is a diagram illustrating a configuration of a display device according to an exemplary embodiment of the present invention.

Referring to FIG. 9, the display device 900 according to an exemplary embodiment may include a display unit 910 and an electrode 920. More specifically, according to an exemplary embodiment of the present invention, the display unit 910 may include a plurality of particles 912 having electric charges having the same sign as being dispersed in the solvent 914 having electrical polarization characteristics. In addition, according to an exemplary embodiment of the present invention, the display unit 910 may include a plurality of particles 912 having electric charges having the same sign and having electric polarization characteristics, dispersed in the solvent 914. Meanwhile, the configuration of the display device according to the exemplary embodiments of the present invention will be conceptually shown in FIGS. 10 and 11, respectively. Since these embodiments have already been described in detail with reference to FIGS. 7 and 8, further description of FIGS. 10 and 11 will be omitted. That is, FIG. 10 shows that the solvent has electrical polarization characteristics, and FIG. 11 shows that the particles have electrical polarization characteristics.

First, according to an embodiment of the present invention, the display unit 910 reflects light of an arbitrary wavelength range (ie, light of any color when viewed in the visible light region) according to the intensity and direction of the applied electric field. As described above, this may be performed by controlling the distance between the particles 912 according to the strength and direction of the electric field applied to the display unit 910.

Next, according to an embodiment of the present invention, the electrode 920 performs a function of applying an electric field of a predetermined intensity and direction to the display unit 910, and the intensity of the electric field applied through the electrode 920. The direction may be appropriately controlled according to the wavelength range of the light desired to be reflected from the display unit 910.

More specifically, FIG. 12 is a diagram illustrating a configuration of a display device including a plurality of electrodes according to an exemplary embodiment of the present invention.

Referring to FIG. 12, the electrodes 1222, 1224, 1226, and 1228 according to the exemplary embodiment of the present invention may further include a display unit for more precisely and independently controlling the interval between the particles 1212 included in the display unit 1210. It may be composed of a plurality of electrodes 1222, 1224, 1226, 1228 that can independently apply an electric field to only a portion of the area (1210), the plurality of electrodes 1222, 1224, 1226, 1228 is a thin film It can be individually controlled by a fine driving circuit such as a thin film transistor (TFT). In addition, according to an embodiment of the present invention, the electrodes 1222, 1224, 1226, and 1228 may be made of a light transmissive material, for example, in order not to interfere with the progress of light emitted from the display unit 1210. Permeable electrode materials may be composed of indium tin oxide (ITO), titanium oxide (TiO ₂ ), carbon nanotubes, and other electrically conductive polymer films.

12, the electrodes 1222, 1224, 1226, and 1228, according to an embodiment of the present invention, include a first electrode 1222, a second electrode 1224, a third electrode 1226, and a first electrode 1226. It may include four electrodes 1228. First, since the electric field is not applied to the space covered by the first electrode 1222 to which no voltage is applied, the particles 1212 positioned in the space covered by the first electrode 1222 may be irregularly arranged. have. Accordingly, the display unit 1210 controlled by the first electrode 1222 may not exhibit color due to photonic crystal. Next, an electric field corresponding to the voltage is applied to a space covered by the second electrode 1224, the third electrode 1226, and the fourth electrode 1228 to which voltages of different levels are applied. Electric force due to the electrophoretic force (ie, the force causing electrophoresis), the electric repulsive force between the particles 1212 having the same charge and the electric attraction due to the polarization of the particles 1212 or the solvent 1214 The particles 1212 positioned in the space covered by the second electrode 1224, the third electrode 1226, and the fourth electrode 1228 may be regularly arranged at predetermined intervals. Accordingly, the display unit 1210 controlled by the second electrode 1224, the third electrode 1226, and the fourth electrode 1228 may reflect light having a different wavelength range according to the corresponding region (ie, photonic crystal). Structural color by sex). For example, it may be assumed that the voltage applied to the fourth electrode 1228 is greater than the voltage applied to the third electrode 1226, which is located in the space covered by the fourth electrode 1228. The spacing between the particles 1212 may be narrower than the spacing between the particles 1212 positioned between the third electrodes 1226, so that the display portion 1210 controlled by the fourth electrode 1228 may be formed. It is possible to reflect light having a shorter wavelength than the display portion 1210 controlled by the three electrodes 1226.

Experiment result

First, FIG. 13 and FIG. 14 are graphs and graphs showing light reflected from particles as a result of performing an experiment in which an electric field is applied in a state in which particles having an electric charge are dispersed in a solvent having electrical polarization characteristics, according to an embodiment of the present invention. It is a figure shown as a photograph. For reference, in the experiments of FIGS. 13 and 14, particles having a charge of 100 nm to 200 nm that were negatively charged and coated with a silicon oxide film were used as particles having a charge, and a solvent having a polarity index greater than 1 was used as the electrical polarization characteristic. It was used as a solvent having, and the intensity of the voltage applied to apply the electric field to the particles and the solvent was set variously in the range of 0V to 5V. On the other hand, the graph shown in Figure 13 shows the reflectance of the light reflected from the particle when the electric field of various intensities are applied in the wavelength range of the visible light band, the wavelength pattern of the reflected light according to the change in the intensity of the electric field in FIG. The larger the degree of change, the greater the change in the spacing of the particles, which means that by controlling the intensity of the electric field it is possible to reflect light of more wavelengths from the particles.

Referring to FIG. 13, it can be seen that the wavelength pattern of the light reflected from the particles varies according to the intensity of the applied electric field (ie, the intensity of the voltage). More specifically, the intensity of the applied electric field (ie, It can be seen that as the intensity of the voltage) increases, the wavelength of the light reflected from the particles becomes shorter overall. According to the experimental result of FIG. 13, it can be seen that as the intensity of the applied electric field increases (ie, the intensity of voltage), the color of light reflected from the particles changes from a red color to a blue color. Referring to FIG. The visual change of the reflected light can be visually confirmed.

Next, FIGS. 15 and 16 illustrate wavelengths of light reflected from particles when an electric field is applied in a state in which charged particles are dispersed in various solvents having different polarity indices, according to an embodiment of the present invention. It is a figure which shows as a graph. For reference, in the experiments of FIGS. 15 and 16, particles having a size of 100 nm to 200 nm that are negatively charged and coated with a silicon oxide film were used as particles having a charge, and polarity indices were 0, 2, 4, and 5, respectively. Phosphorus solvent was used as a solvent having electrical polarization properties. More specifically, the graphs (a), (b), (c), and (d) of FIG. 15 show experimental results of solvents having polar indices of 0, 2, 4, and 5, respectively, and the graph of FIG. 16. (a), (b), (c) and (d) mix a solvent having a polarity index of zero and a solvent having a polarity index of 4 at a ratio of 90:10, 75:25, 50:50 and 0: 100, respectively. The results of experiments performed on one solvent are shown. Meanwhile, the graphs shown in FIGS. 15 and 16 show reflectances of light reflected from particles when electric fields of various intensities are applied, in the wavelength range of the visible light band, and indicate the wavelength pattern of the reflected light according to the change in the intensity of the electric field. The larger the degree of change, the greater the change in the spacing of the particles, which means that by controlling the intensity of the electric field, it is possible to reflect light of more wavelengths from the particles.

Referring to FIG. 15, it can be seen from the graph (a) showing an experimental result of a solvent having a polarity index of 0 that the wavelength pattern of the reflected light hardly changes even when the electric field intensity (that is, the voltage intensity) changes. As the polarity index increases (ie, from graph (a) to (d)), it can be seen that the change in the wavelength pattern of the reflected light according to the intensity of the electric field (that is, the intensity of the voltage) is large. In addition, referring to FIG. 16, as the proportion of the solvent having a high polarity index increases (that is, from the graph (a) to (d)), the change in the wavelength pattern of the reflected light according to the intensity of the electric field (ie, the intensity of the voltage) It can be seen that appears large.

In view of the above-described experimental results, according to the exemplary embodiment of the present invention, a light having an arbitrary wavelength may be adjusted by appropriately adjusting the amount of charge or polarization of a particle, the amount of polarization of a solvent, or the intensity of an applied electric field. It can be seen that it is possible to implement a reflective photonic crystal, thereby implementing a display of an arbitrary full spectrum.

Next, FIGS. 17 and 18 are graphs showing light reflected from particles when an electric field is applied in a state in which particles having charge and electric polarization characteristics are dispersed in a solvent, according to an embodiment of the present invention. It is a figure shown as a photograph. For reference, in the experiments of FIGS. 17 and 18, the SrTiO ₃ particles (see FIG. 17A) and the BaTiO ₃ particles (see FIG. 17A), which are charged to have charges, respectively, have electric charge and electric polarization. Used as particles with properties, the particles were dispersed in a solvent with a zero polarity index.

Referring to FIG. 17, it can be seen that as the intensity of the electric field applied to the particles and the solvent increases, the reflectivity of the light generally decreases. As a result of this experiment, as the electric field is applied, the particles dispersed in the solvent may be electrically polarized and arranged in the direction of the electric field (see FIG. 18B), and due to this arrangement, the number of particles that may reflect incident light may be small. It can be interpreted that the reflectivity of light is reduced. Although, in the present experiment, the wavelength of reflected light was not drastically changed by using an electric field applied in a state in which particles having electric polarization characteristics were dispersed in a nonpolar solvent, the particles were arranged in a constant direction as the electric field was applied. From this, it can be seen that the wavelength of the reflected light can be changed by optimizing the conditions such as the charge on the particle surface.

Next, FIG. 19 is a diagram illustrating experimental results of a configuration of implementing a transparent display according to an embodiment of the present invention. For reference, in the present experiment, particles, a solvent, and an electrode made of transparent materials that transmit light in the visible light band were used, and the display was visually visualized while gradually increasing the intensity of the electric field applied to the display device using photonic crystallinity. Observed by.

Referring to FIG. 19, it can be seen that a predetermined color is displayed on the display device as light in the visible light band is reflected by the photonic crystal when the electric field intensity is relatively small (FIGS. 19A and 19B). (b)). However, when the intensity of the electric field is relatively large, it can be seen that as the wavelength range of the light reflected by the photonic crystal is gradually shifted from the visible light band to the ultraviolet band, the color displayed on the display device becomes noticeably pale (Fig. 19 (c)), when the intensity of the electric field is further increased, as the wavelength range of the light reflected by the photonic crystal is completely out of the visible light band, it can be seen that the display device becomes transparent without displaying any color. (See FIGS. 19D and 19E). Using this characteristic, the display device according to the present invention may be utilized as smart glass such as a color variable glass.

20 is a diagram illustrating a result of experimenting with display performance according to an observation angle of a display device according to an exemplary embodiment of the present invention (that is, an experiment result regarding a viewing angle of a display).

Referring to FIG. 20, even when the observation angle of the display device according to the exemplary embodiment of the present invention changes from 20 ° to 70 °, it is confirmed that there is little change in the color patterns 2010 to 2060 of the reflected light. The conventional photonic display device has a disadvantage in that the color pattern is greatly changed according to the viewing angle, but the display device according to the present invention has the advantage that the color pattern according to the viewing angle is almost constant without any change. have. This advantage can be interpreted as being due to the fact that the photonic crystal formed by the display device according to the present invention is a quasi crystal having a short range order, and thus the display device according to the present invention. The display performance can be significantly improved as compared with the conventional display device that only forms a photonic crystal having a long range order.

Hereinafter, even if the electric field that serves to control the spacing of the particles is blocked, the spacing of the particles can be maintained in a controlled state for this purpose, the experimental example for the configuration including a predetermined additive in the solvent in which the particles are dispersed Let's take a closer look at.

More specifically, according to (1) the concentration of the additive, (2) the molecular weight difference of the alkyl group constituting the polymer, (3) the color retention time and various photonic crystal colors according to the change in the number of hydrogen bonding sites constituting the anchor group It can be implemented, hereinafter will be described with reference to specific experimental examples and data.

(1) Concentration of additive

21 and 22 are added to the solvent according to an embodiment of the present invention by adding a predetermined additive in the present invention so that the spacing of the particles can be maintained in a controlled state even after the electric field that serves to control the particle spacing is blocked It is a figure which shows the experiment result about the structure to make as a graph and a photograph. For reference, in this experiment, propylene carbonate (Propylene Carbonate) was used as a solvent, a substance of the formula C ₆₄ H ₁₂₄ O ₂₆ (aka Tween80 or T-80) was used as an additive to the solvent, Concentrations were set to 0%, 5%, and 20% in each experiment (experiments in Figs. 21B, 21C and 21D, respectively). In this experiment, a voltage of 3.5 V was applied for 10 seconds to apply an electric field to the display device using the photonic crystal. FIG. 21A is a graph showing the pattern of the applied voltage over time. 21 (b), 21 (c) and 21 (d) are graphs showing the intensity of reflected light reflected from the display device over time when a voltage having a pattern as shown in FIG. 40 (a) is applied (for reference, 21 (b), (c) and (d) are graphs of only Hue values through HSV analysis of reflected light). 22 (a), (b) and (c) are photographs showing the results of visual observation of the experimental results of FIGS. 21 (b), (c) and (d).

Referring to FIG. 21, first, when an additive is not added to a solvent in which particles are dispersed, light is reflected by a photonic crystal when an electric field is applied, but when the electric field is removed, a regular array of particles is immediately lost, thereby reflecting light by the photonic crystal. It can be confirmed that not (see FIG. 21B and FIG. 22A). Next, when the additive is added at a concentration of 5% to the solvent in which the particles are dispersed, it can be confirmed that the light by the photonic crystal is reflected for about 9 seconds even after the electric field is removed (FIG. 21 (c) and See FIG. 22 (b)). Next, when the additive is added at a concentration of 20% to the solvent in which the particles are dispersed, it can be seen that the light by the photonic crystal is reflected for about 60 seconds even after the electric field is removed (FIGS. 21D and 22). (C) of).

On the other hand, (b), (c) and (d) of Figure 21 as a whole, when the voltage is cut off showed a large difference in the duration of the reflected light according to the concentration of the additive, when the voltage is applied according to the concentration of the additive It can be seen that there was no difference in the time taken for the reflected light to appear. Therefore, even if the additive is added, it can be evaluated that the response speed of the display device according to the present invention does not slow down, that is, the display performance of the display device does not decrease.

From the experimental results of FIGS. 21 and 22, it is possible to limit or retard the movement of particles in the solvent by adding an additive to the solvent in which the particles are dispersed, and this restriction or retardation phenomenon is more apparent as the amount of the additive is increased. You can check it. Therefore, according to the display device according to the exemplary embodiment of the present invention, since the electric field may be intermittently applied at an appropriate period without continuously applying the electric field in implementing the continuously driven display, it is consumed to drive the display device. The effect of being able to reduce the power to be achieved is achieved.

(A), (b), (c) of FIG. 23 is a figure which showed the color shift which each of (a), (b), (c) of FIG. 22 shows by color coordinate.

Referring to FIG. 23, it is shown that as the concentration of the additive is gradually increased, the original color is restored through various color ranges. Therefore, it was confirmed that not only the color retention time can be adjusted by adjusting the concentration of the additive, but also the reflected light of various wavelength bands can be adjusted.

(2) Molecular weight difference between alkyl groups constituting the polymer

Figures 24 to 26 are added to the solvent according to an embodiment of the present invention according to an embodiment of the present invention by adding a predetermined additive in the present invention the gap between the particles even after the electric field that serves to control the particle spacing is blocked It is a figure which shows the experiment result about the structure which can be maintained as it is.

For reference, in the experiments of FIGS. 24 to 26, propylene carbonate (Propylene Carbonate) was used as a solvent, a substance of the formula C ₅₈ H ₁₁₄ O ₂₆ (aka Tween 20 or T-20), C ₆₄ H ₁₂₆ O ₂₆ phosphorus (aka Tween 60 or T-60) and C ₆₄ H ₁₂₄ O ₂₆ phosphorus (aka Tween 80 or T-80) were used as additives to the solvent, and the concentration of additives varied in each experiment. Was set.

24 and 25 illustrate the effect of the length of the alkyl group constituting the polymer of the additive on the duration of the reflected light after adding 20 wt% of T-20 and 20 wt% of T-60 to the solvent, and then The change in reflected light is measured. Since T-60 has 6 more carbon atoms than T-20, T-60 has a longer alkyl group than T-20.

Referring to FIGS. 24 and 25, as the external additive is added, the photonic crystal color implementation is realized immediately when the external voltage is applied, but when the external voltage is blocked, it takes a certain time for the photonic crystal color to return to the original color. In particular, when the polymer chain is longer, the reaction rate is gradually delayed (that is, the duration of reflected light is longer) when the applied voltage is blocked.

FIG. 26 shows Hue values according to the applied voltage blocking according to the types of additives after adding 20 wt% of T-20, T-40, and T-80 as additives, and there was no significant change as the concentration of the additives changed. However, the longer the polymer length, the more delayed it can be seen. That is, color retention time can be improved as molecular weight of the alkyl group which comprises a polymer becomes large.

(3) Change in the number of hydrogen bond sites constituting the anchor group

Fixers reliably fix polymers that cause steric effects to the surface of the particles. Therefore, the epoxy group, the epoxide group, the carboxyl group, the anhydride group, the aldehyde group, the aldehyde group, As the ketone group, the ester group, and the alcohol group are substituted with the fixing group, the color retention time can be improved. In other words, the more hydrogen bonding sites constituting the anchor group, the more the color retention time can be improved.

27 is a view showing color coordinates according to the change in the number of hydrogen bonding sites of the fixing group.

Referring to Figure 27, (a) is a polyethylene glycol dodecyl ether having a monodentate hydrogen bonding site in the solvent, the molecular formula CH ₃ (CH ₂ ) ₁₀ CH ₂ (OCH ₂ CH ₂ ) _n OH, hereinafter "B35" was added as an additive, (b) sorbitan monooleate having a plurality of hydrogen bonding sites in the solvent [Sorbitan Monooleate, molecular formula C ₆₄ H ₁₂₄ O _{26 ,} hereinafter referred to as "T-80" ] Was added as an additive. Herein, propylene carbonate (Propylene Carbonate) was used as the solvent.

The area of (b) color coordinates that appears when T-80 having a large number of hydrogen bonding sites is added to the solvent is larger than the area of (a) color coordinates that appears when B35 having one-digit hydrogen bonding sites is added to the solvent.

That is, the fixing group having a lot of hydrogen bonding sites appear to be restored to the original color through various color ranges. Therefore, it was confirmed that not only the color retention time can be adjusted by selecting the fixing unit having the hydrogen bonding site, but also the reflected light of various wavelength bands can be controlled.

As described above, according to the present invention, even after the electric field, which serves to control the spacing of the particles, is blocked, the spacing of the particles can be maintained in a controlled state, so that a more stable display can be realized and continuously driven. In implementing the display, the effect of reducing the power consumed to apply the electric field is achieved.

In addition, according to the present invention, various colors or continuous colors and transmittances can be implemented as a simple structure in a single pixel. According to the present invention, various hue, transmittance, saturation and brightness can be adjusted with a simple structure. According to the present invention, the color of the continuous wavelength can be realized by reflecting the light of the continuous wavelength rather than the color (hue) by the mixed color of R, G, and B. The display method according to the present invention can simultaneously satisfy large area display, simple display method, continuous color implementation, use in a flexible display area, and display of low power consumption. In addition, according to the display device according to the present invention, by controlling the particles having a charge independently, it is possible to implement a variety of precise display, and the effect of facilitating the maintenance and repair of the display device is achieved. In particular, the display device according to the present invention does not use a separate color filter in contrast to conventional displays such as electronic ink, which can display only a specific color and require a separate color filter to display a different color from a specific color. Its utility is recognized in that it can realize a display that can effectively display the structural color of the entire wavelength range without the need.

In the above embodiment, the focus is on the display device using the photonic crystallinity, but the configuration of the present invention is a color variable glass, color variable wallpaper, color variable solar cell, color variable sensor, color variable paper, color variable ink, forgery It may be applied to various fields such as prevention tags. For example, by using the present concept, by converting a chemical signal obtained from a chemical reaction to be detected into an electrical signal and displaying it in an arbitrary color, a portable biosensor capable of detecting without expensive measuring equipment can be manufactured. As a solvent used in a display device, a material that can be phase-changed by light, heat, pressure, or the like may be used to implement an electronic paper or electronic ink that stably and stably reflects an arbitrary color. In addition, by including a material such as a fluorescent material or a quantum dot (QD) in the particles or solvent included in the display device according to the present invention, a display using a photonic crystal is realized in a bright environment and a fluorescent or quantum dot in a dark or ultraviolet environment. It is also possible to implement the display used.

In the present invention as described above has been described by the specific embodiments, such as specific components and limited embodiments and drawings, but this is provided to help a more general understanding of the present invention, the present invention is not limited to the above embodiments. For those skilled in the art, various modifications and variations are possible from these descriptions.

Accordingly, the spirit of the present invention should not be construed as being limited to the embodiments described, and all of the equivalents or equivalents of the claims, as well as the following claims, belong to the scope of the present invention .

110: particle
112: core cell
114: multicore
116: cluster
118: charge layer
120: solvent
510: Genoelectric
520: ferroelectric
530: paraelectric
710: solvent
720: particle
730: polarization region
810: Particles
900, 1000, 1100, 1200, 1300, 1400, 1500, 1900, 2000, 2100, 2200, 2300: display device
910, 1010, 1110: display unit
912, 1012, 1112: particles
914, 1014, 1114: solvent
920, 1020, 1120: electrode
1210: display unit
1212: Particles
1214: solvent
1222, 1224, 1226, 1228: electrode
2010 to 2060: color pattern of reflected light when the observation angle is 20 ° to 70 °

Claims (34)

Applying an electric field in a state in which a plurality of particles are dispersed in a solvent and controlling at least one of the intensity and the direction of the electric field to control the spacing of the particles so that the color of the light reflected from the particles is displayed variably,
At least one of the particles and the solvent has an electric polarization property-an electric polarization is induced when an electric field is applied, and the amount of electric polarization changes as the applied electric field is changed,
By controlling the transfer resistance of the particles in the solvent, applying an electric field above a threshold necessary to move the particles in the solvent causes the particles and particles to be present in the solvent in the state in which the particles and the solvent are electrically polarized. And moving the particles to reach a specific range within the specific range, and blocking the applied electric field, thereby maintaining the interval of the particles within the specific range. delete delete The method of claim 1,
And at least one of the particles and the solvent comprises a material that is electrically polarized by any one of electron polarization, ion polarization, interfacial polarization, and rotational polarization. The method of claim 1,
And the solvent comprises a material having a polarization index of 1 or more. The method of claim 1,
As the electric field is applied, an electric force generated between the electric field and the particles to cause electrophoresis of the particles, an electric force generated between the plurality of particles, and an electric force generated by the electrical polarization And wherein the spacing of the particles reaches the specific range in interaction with each other, and the light having a specific wavelength is reflected from the plurality of particles as the spacing of the particles reaches the specific range. The method of claim 1,
Blocking the applied electric field maintains the interval of the particles in the solvent for more than a certain time within the specific range. The method of claim 1,
And the threshold value is determined by adjusting the viscosity of the solvent to control the transfer resistance of the particles in the solvent. The method of claim 1,
And the threshold value is determined by adjusting specific gravity of the particles and the solvent to control the movement resistance of the particles in the solvent. The method of claim 1,
And said threshold value is determined by adding an additive to said solvent to adjust the migration resistance of said particles in said solvent. The method of claim 10,
And the additive comprises an anchoring group having affinity with the solvent. The method of claim 11,
And the fixing group hydrogen bonds to the surface of the particle. The method of claim 11,
The fixing group is an epoxy group, an epoxide group, a carboxyl group, an anhydride group, an aldehyde group, a ketone group, an ester group And at least one of an alcohol group. The method of claim 11,
The fixing groups include dioxolane, sorbate, 3-ethyl-6,7-dihydroxy-1,5-dioxocan-3-yl acetate and tetrahydro-4-hydroxymethyl-2 (2- (hydroxymethyl) A display method comprising at least one of -1,3-dioxolan-2-yl) furan-3-yl acetate. The method of claim 10,
The additive method of claim 1, wherein the additive comprises a polymer (polymer) that causes the interstereoscopic effect (steric effect). 16. The method of claim 15,
The polymer is a display method comprising an alkyl group or an alken group having 10 to 350 carbon atoms. The method of claim 10,
The additive method according to claim 1, wherein the additive comprises an oxyethylene lauryl ether or a polysorbate-based compound. A display unit including a solution in which a plurality of particles are dispersed in a solvent,
An electrode for applying an electric field to the display unit, and
The color of light reflected from the particles is controlled by controlling the spacing of the plurality of particles by adjusting at least one of the intensity, direction, number of times, application time, and application position of the electric field applied to the plurality of particles and the solvent through the electrode. It includes a control unit to be displayed variably on the display unit,
At least one of the particles and the solvent has an electric polarization property-an electric polarization is induced when an electric field is applied, and the amount of electric polarization changes as the applied electric field is changed,
By controlling the transfer resistance of the particles in the solvent, applying an electric field above a threshold necessary to move the particles in the solvent causes the particles and particles to be present in the solvent in the state in which the particles and the solvent are electrically polarized. And moving the particles to reach a specific range within a specific range, and blocking the applied electric field to maintain the interval of the particles within the specific range within the solvent. delete delete 19. The method of claim 18,
At least one of the particles and the solvent includes a material electrically polarized by any one of electron polarization, ion polarization, interfacial polarization, and rotational polarization. 19. The method of claim 18,
And the solvent includes a material having a polarization index of 1 or more. 19. The method of claim 18,
As the electric field is applied, an electric force generated between the electric field and the particles to cause electrophoresis of the particles, an electric force generated between the plurality of particles, and an electric force generated by the electrical polarization And the distance between the particles reaches the specific range by interacting with each other, and the light having a specific wavelength is reflected from the plurality of particles as the distance between the particles reaches the specific range. 19. The method of claim 18,
And when the applied electric field is blocked, the gap of the particles in the solvent is maintained for a specific time or more within the specific range. 19. The method of claim 18,
The threshold value is determined by adjusting the viscosity of the solvent to control the movement resistance of the particles in the solvent. 19. The method of claim 18,
And the threshold value is determined by controlling specific gravity of the particles and the solvent to control the resistance of movement of the particles in the solvent. 19. The method of claim 18,
The threshold value is determined by adding an additive to the solvent to adjust the resistance of movement of the particles in the solvent. 28. The method of claim 27,
And the additive includes an anchoring group having affinity with the solvent. 29. The method of claim 28,
And the fixing device hydrogen bonds to the surface of the particle. 29. The method of claim 28,
The fixing group is an epoxy group, an epoxide group, a carboxyl group, an anhydride group, an aldehyde group, a ketone group, an ester group And at least one of an alcohol group. 29. The method of claim 28,
The fixing groups include dioxolane, sorbate, 3-ethyl-6,7-dihydroxy-1,5-dioxocan-3-yl acetate and tetrahydro-4-hydroxymethyl-2 (2- (hydroxymethyl) A display device comprising at least one of -1,3-dioxolan-2-yl) furan-3-yl acetate. 28. The method of claim 27,
The additive may include a polymer that induces a steric effect between particles. 33. The method of claim 32,
The polymer display device, characterized in that it comprises an alkyl group or alken group having 10 to 350 carbon atoms. 28. The method of claim 27,
The additive may include an oxyethylene lauryl ether or a polysorbate-based compound.

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