Optical property- and color-variable element, and methods for producing and controlling same

Abstract

Disclosed are a color-variable element, and methods for producing and controlling same. The color-variable element comprises a first electrode, a second electrode, and an electrophoretic layer disposed therebetween, wherein the electrophoretic layer comprises a dispersion medium and charge-coated flat first particles. The color-variable element controls the position of the first particles via voltage and the rotational angle of same via pulsed signals.

Description

Optical characteristic color variable element and its manufacturing method and control method

[0001] An embodiment of the present invention relates to a color variable element, and more specifically, to an element whose color changes by an electric field and a method for manufacturing and controlling the same.

[0002] There exists a material in which, when a magnetic field is applied, particles move along the magnetic field, and accordingly, the wavelength of light reflected by the particles changes, thereby changing the color. Patent Publication No. 10-2187266, 'Method for Manufacturing a Counterfeiting and Modification Prevention Device', discloses a structure that includes a first particle and a second particle, and when an external magnetic field is applied, the second particle moves, and the first particle moves due to the movement of the second particle, thereby reversibly changing the color, etc. However, since the color of a conventional color-changing device changes due to a magnetic field, the moving particles are limited to a magnetic substance, and there is a limitation in implementing various colors, etc.

[0003] The technical problem to be achieved by the embodiment of the present invention is to provide a color variable element, a manufacturing method thereof, and a control method thereof, which can change color or reflection characteristics in various ways by adjusting the position and angle of the particles through an electric field without limitation on the type of particles used to implement color.

[0004] In order to achieve the above technical task, an example of a color variable element according to an embodiment of the present invention includes a first electrode; a second electrode; and an electrophoretic layer positioned between the first electrode and the second electrode; wherein the electrophoretic layer includes plate-shaped first particles coated with charges; and a dispersion medium.

[0005] In order to achieve the above technical task, an example of a method for controlling a color variable element according to an embodiment of the present invention includes a method for controlling a color variable element including a plate-shaped first particle coated with a charge, the method including: a step of controlling a position of the first particle using a voltage intensity; and a step of controlling a rotation angle of the first particle using a pulse signal.

[0006] In order to achieve the above technical task, an example of a method for manufacturing a color variable element according to an embodiment of the present invention includes the steps of: generating first particles by coating flake particles with a charged material; generating an electrophoretic material in which the first particles are dispersed; and forming an electrophoretic layer composed of the electrophoretic material between a first electrode and a second electrode.

[0007] According to an embodiment of the present invention, since charge-coated particles are used, there are no restrictions on the material of the particles themselves, allowing the use of particles with various colors or reflective properties. Furthermore, the plate-shaped particles enable the implementation of not only a variety of colors but also a variety of reflective properties. The color-variable element of the present embodiment can be applied to various fields utilizing color-variable effects, such as display devices and counterfeiting devices.

[0008] FIG. 1 is a diagram illustrating the structure of an example of a color variable element according to an embodiment of the present invention;

[0009] FIG. 2 is a diagram illustrating an example structure of a particle that is moved by an electric field according to an embodiment of the present invention;

[0010] FIG. 3 is a diagram illustrating an example of a method for controlling a color variable element according to an embodiment of the present invention.

[0011] FIG. 4 is a drawing showing an example of color change according to the rotation angle of a color variable element according to an embodiment of the present invention.

[0012] FIG. 5 is a diagram illustrating an example of a change in reflection characteristics according to a change in the position of a color variable element according to an embodiment of the present invention.

[0013] FIG. 6 and FIG. 7 are drawings showing an example of a structure for maintaining a gap in an electrophoretic layer of a color variable element according to an embodiment of the present invention.

[0014] FIG. 8 is a diagram illustrating the structure of another example of a color variable element according to an embodiment of the present invention, and

[0015] FIG. 9 is a drawing illustrating an example of a method for manufacturing a color variable element according to an embodiment of the present invention.

[0016] Hereinafter, a color variable element, a manufacturing method thereof, and a control method thereof according to an embodiment of the present invention will be described in detail with reference to the attached drawings.

[0017] FIG. 1 is a drawing showing the structure of an example of a color variable element according to an embodiment of the present invention.

[0018] Referring to FIG. 1, the color variable element (100) includes a first electrode (110), a second electrode (120), and an electrophoretic layer (130). The electrophoretic layer (130) includes first particles (140) and a dispersion medium (150).

[0019] The first electrode (110) and the second electrode (120) are formed to face each other as front electrodes in a flat shape. The first electrode (110) and / or the second electrode (120) may be implemented with a metal or ITO (Indium Tin Oxide), etc. In addition, the first electrode (110) and / or the second electrode (120) may be implemented with a glass or film material, etc. In one embodiment, the first electrode (110) and the second electrode (120) may be implemented with a transparent electrode of a transparent material. In another embodiment, the first electrode (110) may be implemented with a transparent electrode, and the second electrode (120) may be implemented with an opaque electrode. Or, conversely, the first electrode (110) may be implemented with an opaque electrode, and the second electrode (120) may be implemented with a transparent electrode. Alternatively, at least one of the first electrode (110) and the second electrode (120) may be implemented as a translucent electrode. In addition, the transparency of each electrode (110, 120) may be varied depending on the embodiment.

[0020] The electrophoretic layer (130) is located between the first electrode (110) and the second electrode (120). The first particle (140) of the electrophoretic layer (130) is a particle having a charge that allows movement and / or rotation when an electric field is applied.

[0021] In one embodiment, the first particle (140) itself may be composed of a material having an electric charge. However, electronic ink, which can move by an electric field, has a circular shape, so color changes can be realized through movement, but there are limitations in exhibiting optical properties (e.g., reflection effect, glitter effect, etc.).

[0022] In the present embodiment, the first particle (140) is implemented in a plate shape so as to have optical properties. The plate-shaped first particle (140) can exhibit optical properties such as a reflective effect or a sparkling effect due to light reflected from the surface. In addition, the first particle in the plate shape must be charged with (+) or (-) charges so that it can move and / or rotate due to an electric field to exhibit color changes and / or optical properties. However, although existing liquid materials with charges (e.g., e-ink, etc.) can implement spherical particles, it is difficult to implement them in a plate-shaped structure. Therefore, the present embodiment implements the plate-shaped first particle (140) by coating charges on flake particles. The structure of the first particle (140) will be examined again in FIG. 2.

[0023] The dispersion medium (150) may be implemented with various materials, such as a transparent solvent, a colored solvent, or a colored pigment dispersion. In one embodiment, the specific gravity of the first particle (140) and the dispersion medium (150) may be the same within a predefined error range so that the first particle (140) is dispersed in the electrophoretic layer.

[0024] When an electric field is applied, the first particle (140) moves and / or rotates in the dispersion medium (150). An electric field can be formed in the electrophoretic layer by applying a voltage to the first electrode (110) and the second electrode (120). Depending on the strength of the applied voltage, the movement speed and / or movement position of the first particle (140) can be controlled. The rotation angle of the first particle (140) can be controlled through a pulse signal. Since the first particle (140) is in the shape of a thin plate, various reflection effects and sparkling effects on the surface can appear depending on the movement position and / or rotation angle of the first particle (140). The method for controlling the voltage drive of the first particle (140) will be reviewed again in FIG. 3. In addition, the color change and the optical characteristic change according to the movement and / or rotation of the first particle will be reviewed again in FIGS. 4 and 5.

[0025] FIG. 2 is a drawing illustrating an example structure of a particle that is moved by an electric field according to an embodiment of the present invention.

[0026] Referring to FIGS. 1 and 2, the first particle (140) present in the electrophoretic layer (130) is manufactured by coating a charge on a flake particle (200). The flake particle (200) may be in the form of a thin plate capable of exhibiting a reflection or glitter effect due to the surface. For example, the flake particle (200) may be a particle whose color or reflected light changes depending on the angle of incident light on at least one side, a particle whose at least one side exhibits mirror characteristics, a particle whose at least one side exhibits metallic luster characteristics, or a particle whose color is one color or whose two sides have different colors.

[0027] The flake particles (200) can be implemented with various materials having desired colors and desired optical properties. Since the present embodiment controls the movement of the first particles through an electric field rather than a magnetic field, the flake particles do not need to be a material such as a magnetic substance that can move by a magnetic field. In addition, since the first particles (140) are created by coating charges on the flake particles (200), the flake particles themselves do not need to be limited to a material having charges. Therefore, the flake particles (200) of the present embodiment are not limited to a specific material, and thus can be a material that can implement colors (e.g., gold, silver, etc.) that could not be implemented using existing pigments, or can implement desired reflective properties (e.g., glitter effect or mirror effect). In one embodiment, the first particles (140) may have a horizontal length of 5 to 50 μm.

[0028] When an electric field is applied, the surface of the flake particle (200) is coated with a material having a charge so that the flake particle (200) can move and / or rotate. Although the present embodiment shows an example of coating the surface of the flake particle (200) with a material having an anion, the surface of the flake particle (200) may be coated with a material having a cation. Since the method of coating the flake particle (200) with a material having a charge is already a widely known structure, a description of the coating method itself is omitted. The present embodiment can use various conventional materials having a charge and various coating methods, and is not limited to a specific material or a specific coating method.

[0029] In another embodiment, depending on the type of flake particle (200), coating with a charged material may not be successful. In this case, the flake particle (200) may be coated with an inorganic material (210) or an organic material (220), and then a charged material may be coated thereon again.

[0030] FIG. 3 is a drawing illustrating an example of a method for controlling a color variable element according to an embodiment of the present invention.

[0031] Referring to FIGS. 1 and 3, the first particle (140) of the electrophoretic layer (130) of the color variable element (100) moves and / or rotates by the application of an electric field. For example, the control device (not shown) of the color variable element (100) controls the voltage direction, voltage intensity, pulse voltage, etc. applied to the first electrode (110) and the second electrode (120) to change the characteristics of the electric field applied to the electrophoretic layer (130), thereby controlling the movement and / or rotation of the first particle (140).

[0032] In one embodiment, the direction of movement of the first particle (140) can be controlled (302) by controlling the voltage direction (300). For example, if the first particle (140) is a particle with a (-) charge and a (+) voltage is applied to the first electrode (110) and a (-) voltage is applied to the second electrode (120), the first particle (140) moves downwards in the electrophoretic layer (130), and if the directions of the voltages applied to the first electrode (110) and the second electrode (120) are reversed, the second particle (140) can move upwards in the electrophoretic layer (130).

[0033] In another embodiment, the movement position of the first particle can be controlled (312) by controlling the voltage level (310). When a voltage is applied between the first electrode (110) and the second electrode (120) for a certain period of time (e.g., several milliseconds), the movement distance of the first particle (140) can be longer as the applied voltage level increases.

[0034] In another embodiment, the rotation angle of the first particle can be controlled (e.g., PWM (Pulse Width Modulation) control) (322) through a pulse signal (320). In this embodiment, the property of the first particle rotating when a pulse voltage is applied is identified, and the rotation angle of the first particle (140) is controlled through this. The pulse width and size of the pulse voltage for control can be experimentally defined in advance according to the size or type of the first particle (140). After the pulse voltage is applied to rotate the first particle (140), when a DC voltage is applied again for a certain period of time, the first particle (140) moves according to the DC voltage and the flat surface is rearranged in the vertical direction of the electric field (i.e., the horizontal direction in FIG. 1). That is, the first particle (140) returns to its original state where it has not rotated. Therefore, the position and rotation angle of the first particle (140) can be controlled through the pulse voltage and the DC voltage.

[0035] FIG. 4 is a drawing showing an example of color change according to the rotation angle of a color variable element according to an embodiment of the present invention.

[0036] Referring to FIG. 4, when a pulse voltage is applied to the first electrode (110) and the second electrode (120), a change in the electric field according to the pulse voltage occurs in the electrophoretic layer (130), and the first particle (140) rotates accordingly. The rotation angle of the first particle (140) may vary depending on the magnitude of the pulse voltage or the time for which the pulse voltage is applied (410, 420). In addition, when the pulse voltage is applied, the first particle (140) may move upward or downward. For example, when a (+) pulse voltage is applied, the first particle (140) may move upward and rotate in the first direction, and when a (-) pulse voltage is applied, the first particle may move downward and rotate in the second direction (the direction opposite to the first direction).

[0037] Depending on the rotation angle of the first particle (140), the optical characteristics appearing on the surface of the first particle (140) may vary. For example, if the dispersion medium (150) is black and the first particle (140) is randomly dispersed in the electrophoretic layer (400), the color variable element (100) may appear black. When a pulse voltage is applied and the first particle (140) moves toward the second electrode (120) and rotates clockwise (410) or counterclockwise (420), light incident from the second electrode (120) may be reflected by the surface of the first particle (140) to exhibit a sparkling effect together with the color of the first particle (140). If the first particle (140) is rhombus-shaped, the shape of light reflected from the first particle (140) may be different depending on the clockwise rotation (410) or counterclockwise rotation (420) of the first particle (140), and thus the optical characteristics (reflection effect or sparkling effect, etc.) may be different.

[0038] FIG. 5 is a drawing showing an example of a change in reflection characteristics according to a change in the position of a color variable element according to an embodiment of the present invention.

[0039] Referring to FIG. 5, when a DC voltage is applied through the first electrode (110) and the second electrode (120), the first particle (140) moves upward or downward on the electrophoretic layer (130) depending on the voltage direction and voltage magnitude. The color of the color variable element (100) may vary depending on the movement position of the first particle. For example, when the dispersion medium (150) is black and the first particle (140) is located toward the first electrode (500), the color variable element (100) exhibits a black color. When a DC voltage is applied to move the first particle (140) to the 2 / 3 point of the electrophoretic layer (510), the color variable element (100) partially displays the color of the first particle (140) due to the light reflected by the first particle (140). When the first particle (140) is completely moved toward the second electrode (120) (520), the color variable element (100) clearly displays the color of the first particle (140). In other words, the color displayed by the color variable element (100) may vary depending on where the first particle (140) is positioned in the electrophoretic layer (130). For example, if the dispersion medium (150) has a certain color, the ratio of the light reflected by the dispersion medium (150) and the light reflected by the first particle (140) varies depending on the position of the first particle (140), and the color varies accordingly.

[0040] FIG. 6 and FIG. 7 are drawings showing an example of a structure for maintaining a gap in an electrophoretic layer of a color variable element according to an embodiment of the present invention.

[0041] Referring to Fig. 6, when the color variable element (600) is manufactured in a film form, a capsule (610) may be included to maintain the gap of the electrophoretic layer (130). The first particle (140) and dispersion medium (150) of the electrophoretic layer (130) exist within a plurality of capsules (610).

[0042] Referring to Fig. 7, the color variable element (700) includes a partition wall (710) for maintaining a gap of the electrophoretic layer. The first particle (140) and dispersion medium (150) of the electrophoretic layer (130) exist in the space between each partition wall (710).

[0043] FIG. 8 is a diagram illustrating the structure of another example of a color variable element according to an embodiment of the present invention.

[0044] Referring to FIG. 8, the color variable element (800) includes a first electrode (110), a second electrode (120), a first particle (140), a dispersion medium (150), and a second particle (810). Compared to the color variable element (100) examined in FIG. 1, the color variable element (800) of the present embodiment further includes the second particle (810), and the remaining configuration is the same as that of FIG. 1.

[0045] The second particle (810) is a spherical particle that is not affected by an electric field. For example, the dispersion medium (150) may be a transparent material, and the second particle (810) may be a colored particle. For example, the second particle (810) may be implemented as a colored solvent or a colored pigment dispersion.

[0046] FIG. 9 is a drawing illustrating an example of a method for manufacturing a color variable element according to an embodiment of the present invention.

[0047] Referring to FIGS. 1, 2, and 9 together, first particles (140) are generated by coating flake particles (200) with a charged material (S900). The charged material may be coated directly onto the flake particles (200), or the charged material may be coated on the flake particles (200) after coating them with an inorganic material (210) or an organic material (220). An example of generating first particles (140) using charged coating is illustrated in FIG. 2.

[0048] An electrophoretic material is created by mixing a first particle (140) and a dispersion medium (150) (S910). The dispersion medium (150) may be a transparent or colored material. In another embodiment, an electrophoretic material may be created by further including a second particle (810) in the dispersion medium (150), as shown in FIG. 8.

[0049] An electrophoretic layer (130) composed of an electrophoretic material is formed between the first electrode (110) and the second electrode (120) (S920). In one embodiment, in order to form a gap between the first electrode (110) and the second electrode (120), a capsule (610) including an electrophoretic material may be created as shown in FIG. 6, and the electrophoretic layer (130) may be implemented with the capsule (610). In another embodiment, as shown in FIG. 7, a partition wall (710) may be formed between the first electrode (110) and the second electrode (120), and then the electrophoretic material may be filled in the space between the partition walls (710) to form the electrophoretic layer (130).

[0050] The present invention has been described above, focusing on preferred embodiments thereof. Those skilled in the art will appreciate that the present invention can be implemented in modified forms without departing from its essential characteristics. Therefore, the disclosed embodiments should be considered illustrative rather than limiting. The scope of the present invention is set forth in the claims, not the foregoing description, and all differences within the scope equivalent thereto should be construed as being encompassed by the present invention.

Claims

1. First electrode; a second electrode; and An electrophoretic layer positioned between the first electrode and the second electrode; The above electrophoretic layer is, A first plate-shaped particle coated with a charge; and A color variable element characterized by including a dispersion medium.

2. In paragraph 1, The color variable element characterized in that the first particle is a flake particle coated with an inorganic or organic material and then coated with a material having a charge.

3. In paragraph 1, A color variable element characterized in that the first particle and the dispersion medium have different colors.

4. In paragraph 1, A color variable element characterized in that the horizontal length of the first particle is 5 to 50 μm.

5. In paragraph 1, A color variable element characterized in that the above dispersion medium is a colored solvent or a colored pigment dispersion.

6. In the first paragraph, the electrophoretic layer, A color variable element characterized by further comprising second circular particles dispersed in the dispersion medium.

7. In the first paragraph, the first particle, The direction of movement is controlled by the voltage direction, The position is controlled by the voltage, A color variable element characterized in that the rotation angle is controlled by a pulse signal.

8. In the first paragraph, the electrophoretic layer, A color variable element characterized by further comprising a barrier rib for maintaining a gap between the first electrode and the second electrode.

9. In the first paragraph, the electrophoretic layer, further comprising a capsule for maintaining a gap between the first electrode and the second electrode; A color variable element characterized in that the first particle and the dispersion medium are present within the capsule.

10. A method for controlling a color variable element including a first particle in a plate shape coated with a charge, A step of controlling the position of the first particle using voltage; and A control method characterized by comprising a step of controlling the rotation angle of the first particle using a pulse signal.

11. A step of generating a first particle by coating a flake particle with a charged material; A step of generating an electrophoretic substance in which the first particle is dispersed; and A method for manufacturing a color variable element, characterized by comprising the step of forming an electrophoretic layer composed of the electrophoretic material between a first electrode and a second electrode.

12. In the 11th paragraph, the step of generating the first particle comprises: A step of first coating the above flake particles with an inorganic or organic material; and A method for manufacturing a color variable element, characterized by comprising a step of secondarily coating a material having a charge on the inorganic or organic material.

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