KR102706610B1 - Display Device Using Capacitor Characteristics - Google Patents

Abstract

The present invention relates to a display device using capacitor characteristics, comprising: an upper substrate; a lower substrate; a common electrode disposed on one surface of the upper substrate; a lower electrode disposed on one surface of the lower substrate; a display layer having a fluid therein including at least one type of electrophoretic particles between the common electrode and the lower electrode; and a conductive adhesive layer between the display layer and the lower electrode. The lower electrode is composed of a plurality of lower electrodes having independently separated areas of different sizes. The display layer includes segments formed asymmetrically. The segments have non-polar capacitor characteristics and are structurally configured to have different electrostatic capacitances.

Description

{Display Device Using Capacitor Characteristics}

The present invention relates to a panel structure and a control method of a reflective display device structurally having capacitor characteristics, and more particularly, to a technology for designing a panel structure so that each unit cell or segment constituting a display layer structurally has non-polar capacitor characteristics, and selectively forming an electric field in a vertical direction in the unit cells or segments by a voltage supplied to electrodes formed independently on a lower substrate without supplying a separate driving voltage to a common electrode formed on a display portion, and controlling the direction of the formed electric field. In addition, the present invention relates to a method for controlling the intensity of the formed electric field by electrically controlling the capacitance (electrostatic capacity) between the unit cells or segments and selectively adjusting the intensity of the voltage distributed to each unit cell or segment even when the intensity of the driving voltage supplied to the panel from the driving board is equal.

Figures 1a, 1b and 1c are schematic diagrams showing the structure and connection method of a capacitor.

Referring to FIGS. 1A, 1B, and 1C, the basic structure of a capacitor (104) or condenser is a structure in which two conductors (100) face each other, an insulator or dielectric (103) is formed between the two conductors, a voltage is applied to the two conductors, and due to charge polarization within the dielectric (or insulator), positive and negative charges are collected and accumulated on different conductors, thereby forming an electric field inside.

At this time, the capacitance (capacitance: ability to store charge in a capacitor), which directly affects the potential difference and charge accumulation formed at both ends of the two conductors when voltage is applied, is determined by the area (101) of the two conductors (100) facing each other, the distance (102) between the two conductors, the permittivity of the dielectric or insulating material located between the two conductors, etc., and the larger the capacitance (capacitance of the capacitor), the more charge can be stored even at the same voltage.

Referring to FIGS. 1b and 1c, depending on how two capacitors are connected in parallel or in series, the capacity, withstand voltage (maximum voltage that can be used without discharge), voltage or potential difference generated at both ends of each conductor of the capacitor according to a common applied voltage, and polarity (positive or negative) of accumulated charge, etc. are determined. When a plurality of capacitors are connected in parallel, the capacity of the entire capacitors connected in parallel increases and the withstand voltage remains constant, and regardless of the capacity of each capacitor connected in parallel, the polarity (sign of accumulated charge) and intensity (or intensity of electric field) of the voltage generated in each capacitor by the applied voltage are all the same. On the other hand, when a plurality of capacitors are connected in series, the electrostatic capacitance of the entire capacitors connected in series decreases and the withstand voltage increases, and the intensity of the voltage distributed to each capacitor is different according to the electrostatic capacitance of each capacitor and the polarity of the voltage supplied to the capacitors connected in series is determined.

Referring to Fig. 1c, when two capacitors are connected in series and different signs of the voltage (V) applied to the ends of the two capacitors are supplied, voltage is supplied from capacitor C2, and a positive voltage is supplied to the first conductor constituting capacitor C2, so it has a + polarity, and the second conductor constituting capacitor C2 located in the opposite position has a relative - polarity due to charge accumulation.

In addition, since voltage is supplied from capacitor C1 and a negative voltage (or GND voltage) is supplied to the first conductor constituting capacitor C1, it has a - polarity and is located opposite to it, and the second conductor constituting capacitor C1 has a + polarity due to charge accumulation.

That is, in order to connect two capacitors in series, the second conductors in the area where the conductors meet have polarities opposite to those of the first conductors, and the electric fields formed also flow in opposite directions. When multiple capacitors are connected in series, the voltage distributed from the total supply voltage to each capacitor can be calculated by the capacitor voltage division law.

Referring to Fig. 1c, in the case of capacitors connected in series, the voltage across the terminals of capacitor C1 can be calculated by the formula V1 = (C2 / C1 + C2) × V (total input voltage), and the voltage across the terminals of capacitor C2 can be calculated by substituting it into the series capacitor voltage distribution formula of V2 = (C1 / C1 + C2) × V.

Therefore, if the capacities of two capacitors connected in series are different, the voltage distributed to the capacitor with the relatively smaller capacitor capacity is greater according to the capacitor voltage division law.

Reflective displays that display colors by controlling the direction and intensity of an electric field use at least two conductors to form an electric field, and when the display layer located between the two conductors contains a medium such as air (air also has low permittivity but dielectric properties) or a fluid, it has a structure similar to a nonpolar capacitor. A representative example is a reflective display based on electrophoresis technology.

A display device using electrophoresis technology implements specific colors or information by utilizing the phenomenon in which, when an electric field is formed in unit cells or segments by an externally applied voltage, electrophoretic particles move toward an electrode to which a voltage with the opposite polarity to the sign of the charge they carry is applied.

Display devices based on electrophoresis technology are classified into types in which the medium through which positively or negatively charged particles move is air or a fluid. Electrophoresis displays in which the medium is a fluid have been most successfully commercialized to date and are leading the related market.

FIGS. 2A, 2B and 2C are cross-sectional views of an electrophoretic technology-based display device showing a conventional method of controlling electrophoretic particles by vertical/horizontal electric fields.

Referring to FIG. 2a, in an electrophoretic display device in which a medium is a fluid (203), a method for controlling electrophoretic particles (202) having a charge is shown, in which the electrophoretic particles are controlled by a horizontal electric field (electric field).

A display device based on electrophoresis technology has a structure in which electrodes are not formed on an upper substrate (201) and a plurality of lower electrodes (205) are formed in parallel only on a lower substrate (206). A voltage of opposite sign is supplied from a driving unit (207) to two or more of the electrodes formed in parallel on the lower substrate, thereby concentrating electrophoretic particles in a specific electrode direction according to the direction of the horizontally formed electric field to display a color. However, as the interval between the electrodes formed on the lower substrate increases, the driving voltage for forming an electric field in which electrophoretic particles can move increases, and there are many restrictions on the unit cell area and electrode pattern separated by the partition (204) that affect the resolution.

In addition, due to the difference in distance between the edges of the two electrode poles formed, a deviation of the electric field occurs depending on the position of the two electrode surfaces forming the electric field, and the edge region of the two electrodes or the non-conductive region separating the two electrodes requires a relatively high driving voltage to move the electrophoretic particles, which causes a slow response time of the particles and agglomeration of the particles, resulting in a deterioration of the color characteristics and lifespan, etc.

In addition, when electrophoretic particles are concentrated with a specific electrode to display a color, the area where the particles are concentrated structurally reduces the aperture ratio and resolution of the display device.

For this reason, reflective display devices using the technology have not been successfully commercialized to date, and are mainly used in variable transmittance displays, such as transparent displays or smart windows that selectively vary the light transmitted, rather than reflective display devices.

Referring to FIGS. 2b and 2c, a display device based on electrophoresis technology showing a method of controlling electrophoretic particles by a vertical electric field has a structure in which a common electrode is formed on an upper substrate and a plurality of electrodes are formed on a lower substrate at positions facing the common electrode, and a voltage is applied to the upper common electrode and the lower electrode to selectively move electrophoretic particles in the direction of the upper or lower electrodes by the electric field formed vertically, thereby displaying a color.

Referring to FIGS. 2b and 2c, since the distance between the lower electrodes (205) on the lower substrate (206) facing the common electrode (208) of the upper substrate (201) for forming an electric field is all constant, there is no electric field deviation according to the position of the electrode surface, and since information is displayed entirely by the color of the electrophoretic particles (210)(211) that have moved to the common electrode (208) of the display portion, the driving voltage is relatively low, the aggregation phenomenon between the particles is small, and the aperture ratio and resolution are excellent. For this reason, most reflective displays based on electrophoretic technology prefer a method of controlling electrophoretic particles by an electric field formed vertically.

Referring to FIG. 2a, a plurality of patterned lower electrodes (205) formed to form an electric field are formed in parallel without facing each other, and the thickness of the electrodes, which are deposited very thinly and uniformly in the nano-unit thickness, corresponds to the area of the conductor that determines the capacitor capacity, so the electrostatic capacitance is extremely low and far from the capacitor structure and characteristics.

On the other hand, referring to Fig. 2b, electrodes are formed in positions facing each other to form an electric field, the area of the facing conductor is large, so the electrostatic capacitance is relatively large, and it has a structure similar to a non-polar capacitor.

However, in order to form an electric field, the Vcom voltage or GND voltage is supplied to the common electrode (208) through the conductive material (209) formed within the opening from the separate electrode (216), and a separate voltage is supplied to each of the lower electrodes (205) formed independently on the lower substrate (206) facing the common electrode (208), so it does not have the characteristics of a capacitor connected in parallel or series in the circuit. It has the disadvantage of having to apply voltage to each independent capacitor.

Referring to FIG. 2c, when a Vcom voltage corresponding to a GND voltage relative to the common electrode (208) is supplied, and a voltage corresponding to ±15 V relative to the GND voltage is applied to each of the independently separated lower electrodes (2051)(2052)(2053), the voltage at both ends of each unit cell or segment located at the lower electrodes (2051)(2052)(2053) to which the voltage is supplied also becomes 15 V, and the sign of the polarity of both ends of the two conductors located in each unit cell or segment area directly reflects the polarity of the voltage applied to the lower electrode, and a potential difference is formed in proportion to the strength of the applied voltage.

That is, in both methods, the direction of the electric field generated is determined by the polarity of the voltage supplied from the driving unit, and the potential difference generated in the unit cell or segment also increases in proportion to the strength of the supplied voltage.

Figures 3a and 3b are cross-sectional views of a conventional electrophoretic technology-based display device.

FIG. 3c and FIG. 3d are schematic diagrams showing a method for manufacturing a display panel for forming a vertical electric field of a conventional electrophoretic technology-based display device.

Referring to FIG. 3a, a reflective display device that uses a fluid as a medium and controls electrophoretic particles by a vertical electric field has a structure in which a display layer including electronic ink in which charged electrophoretic first particles (304) and second particles (306) are dispersed in a fluid (305) is formed between an upper electrode (302) in contact with an upper substrate (301) and a lower electrode (308) in contact with a lower substrate (309) which are respectively formed on one side, and in order to charge and seal the electronic ink, cells separated by partition walls (303) are formed on the upper substrate (301), and after the electronic ink is charged, the cells are sealed with a sealing layer or a conductive adhesive layer (307) to form a display layer (312).

Referring to FIG. 3b, electronic ink can be microencapsulated (310) and mixed with a binder (311), then applied to an upper substrate (301) and dried/cured to form a display layer (312).

Referring to FIGS. 3a and 3b, in both methods, a panel of a display device can be manufactured by attaching an upper substrate and a lower substrate and using a conductive adhesive material to selectively supply voltage to the display layer between the display layer formed on the upper substrate and the lower electrode.

Referring to FIGS. 3a and 3b, in order to control electrophoretic particles by a vertically formed electric field, conventionally, a common voltage, Vcom or GND voltage, must be supplied to a common electrode (302) formed on an upper substrate (301), and an electric field is formed by controlling a voltage of a negative sign or a positive sign and the intensity of the applied voltage relative to lower electrodes (308) formed on a lower substrate (309), and the intensity and direction of the formed electric field are controlled.

Referring to FIGS. 3c and 3d, a method for manufacturing a display panel for forming a vertical electric field of the display device of FIGS. 3a and 3b is shown. In order to supply Vcom or GND voltage to a common electrode (302) formed on an upper substrate (301) which is a display portion, a process for connecting a separate wire (such as a process for removing and cleaning a portion of a display layer formed on the common electrode) is absolutely necessary, and in order to smoothly supply a driving voltage from a driving board to the panel, a separate electrode (315) for supplying Vcom or GND voltage to a lower substrate (309) constituting the panel must be formed.

Referring to FIG. 3c, in order to supply Vcom or GND voltage to the common electrode (302) through a separate electrode (315) formed on the lower substrate (309), during panel manufacturing, a process of removing and cleaning/drying a portion of the display layer through several processes and then filling or attaching a conductive material (314) to the corresponding opening (313) and connecting it to the electrode (315) formed separately on the lower substrate (309) to which the Vcom or GND voltage is supplied is absolutely required.

In particular, a problem may occur in which the Vcom voltage or GND voltage is not supplied normally due to impurities and electrode damage occurring during the process of securing the opening (313), and a problem may occur in which the surrounding display layer (312) may be contaminated or discolored by solvents/particles included in the electronic ink destroyed during the process of exposing the opening (313).

Referring to FIG. 3d, during the process of charging or attaching a conductive material (314) through the secured opening (313), a short circuit may occur with the adjacent lower electrodes (308), so the area (315) to which the Vcom or GND voltage is supplied must be formed sufficiently apart from the display portion (316) of the panel.

However, these conventional panel structures and manufacturing methods have disadvantages in that material costs and manufacturing costs increase due to an increase in the area of the lower substrate (309), loss of the display layer (312), and an increase in the sealing/finishing area.

In particular, referring to FIG. 3d, as the area of the common electrode increases, wiring to which the Vcom to GND voltage is supplied may be added in order to reduce the driving deviation due to surface resistance, and unnecessary peripheral areas other than the display portion (316) also increase further. Unlike conventional information displays that emphasize readability, there are many restrictions on the design of products to which color, material finish, etc. are important elements, and color wall display materials for furniture/appliances that require emotional design, and thus there are many problems in direct application.

FIG. 4 is a cross-sectional view of a display device including two or more types of color electrophoretic particles having different threshold voltages.

Referring to FIG. 4, in the configuration of a display device that controls electrophoretic particles by a vertically formed electric field (electric field) as described in FIGS. 3a, 3b, 3c and 3d, by using two or more types of electrophoretic particles having different threshold voltages or response times, various colors can be displayed without using a color filter.

Referring to FIG. 4, in order to selectively control color electrophoretic particles (first to fourth particles, 404, 405, 406, 407) having different threshold voltages or response times, a method of supplying a Vcom voltage corresponding to a GND voltage to a common electrode (402) of a display portion and applying a voltage intensity corresponding to the threshold voltage of the electrophoretic particles to be driven to the lower electrode (410) was applied.

That is, in order to control electrophoretic particles having different threshold voltages or response times, driving voltages of different strengths are output from the driving board (412) and supplied to the two electrodes where each unit cell or segment is located, thereby selectively controlling electrophoretic particles having different threshold voltages or response times.

However, conventional technologies must directly control the potential difference formed in a unit cell or segment in proportion to the strength of the voltage output from the driving board (412).

That is, in order to control the intensity of the voltage applied to the panel from the driving board (412), the number of different driving voltages that must be output from the driving board (412) increases as electrophoretic particles with different threshold voltages are added, so the circuit of the driving board (412) becomes complex and relatively expensive, high-spec components with high power consumption are used.

In addition, there is a problem that relatively complex driving waveforms and programming are required to output different driving voltages from the manufactured driving board (412).

1. KR 10-2013-0124590 A(2013.11.14.) 2. KR 10-2015-0091190 A(2015.08.07.) 3. KR 10-2016-0041056 A (2016.04.15.) 4. KR 10-2022-0094196 A(2022.07.05.)

The problem to be solved by the present invention is to control a display device by utilizing capacitor characteristics without directly supplying voltage to an upper electrode (common electrode) in order to supplement the limited display area applied to a conventional color conversion display material, and more specifically, to provide a panel structure capable of selectively controlling the intensity of voltage supplied to the panel by structurally setting capacitor electrostatic capacitance between asymmetrically formed unit cells or segments differently, and a display device including the same and methods of controlling the same.

The problem to be solved by the present invention is, in a reflective display device based on electrophoresis technology where the medium is a fluid, problems such as a decrease in characteristics such as an aperture ratio and resolution caused when manufacturing a panel having a plurality of unit cells of uniform specifications by applying conventional technology, contamination/discoloration of the product during the process of exposing an opening in the display layer for supplying voltage to a common electrode to form an electric field, a short circuit problem with adjacent lower electrodes during the process of charging a conductive material, and an increase in power consumption of a high-function/high-price driving board required to control electrophoretic particles having different driving voltages, and the like, to provide a structure for a panel capable of selectively controlling three or more types of multiple color particles, a display device including the same, a manufacturing method therefor, and a control method for fully/selectively driving a display unit.

The problem to be solved by the present invention is to provide a display device in which unit cells or segments are structurally configured to have capacitor characteristics to form an electric field by configuring a panel so that the panel manufacturing process can be simplified, the yield can be improved, and the manufacturing cost can be reduced, in order to solve the problems of the conventional technologies in an electrophoretic technology-based reflective display device in which the medium is a fluid.

The problem to be solved by the present invention is to provide a display device capable of selectively driving a plurality of unit cells or segments by electrically controlling the capacitor capacitance of the unit cells or segments without a connection process that directly supplies voltage to a common electrode.

The problem to be solved by the present invention is to provide a display device having a panel structure and a control method capable of maximizing a display area and minimizing a sealing and finishing area so that it can be applied to various types of designs and products.

The problem to be solved by the present invention is to secure a structure and control methods of a display panel capable of selectively controlling the intensity of the voltage distributed and supplied to each segment or unit cell by utilizing the difference in capacitor electrostatic capacitance between unit cells or segments, even when the intensity of the voltage output from the driving board and supplied to the panel is the same, in a display device that implements color by utilizing the difference in threshold voltage or response time, etc.

The problem to be solved by the present invention is to control a display device by utilizing capacitor characteristics without directly supplying voltage to an upper electrode (common electrode) in order to supplement the limited display area applied to a conventional color conversion display material, and more specifically, to provide a panel structure capable of selectively controlling the intensity of voltage supplied to the panel by structurally setting capacitor electrostatic capacitance between asymmetrically formed unit cells or segments differently, and a display device including the same.

The problems to be solved by the present invention are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

According to one embodiment of the present invention, a display device comprises: an upper substrate; a lower substrate; a common electrode disposed on one surface of the upper substrate; a lower electrode disposed on one surface of the lower substrate; a display layer having a fluid therein including at least one type of electrophoretic particles between the common electrode and the lower electrode; and a conductive adhesive layer between the display layer and the lower electrode, wherein the lower electrode may be formed of a plurality of lower electrodes having independently separated areas of different sizes.

The above display layer includes segments formed asymmetrically, and the segments have non-polar capacitor characteristics and can be configured to have structurally different electrostatic capacitances.

The above segments may comprise a plurality of unit cells or a plurality of microcapsules separated by partitions.

The capacitor capacitance can be controlled by adjusting the dielectric constant of the fluid in which the electrophoretic particles are dispersed, the binder or sealant required to form the display layer, and the conductive adhesive layer, or by forming a dielectric layer on the surface of the upper common electrode or the lower electrode.

A method for controlling a display device according to one embodiment of the present invention comprises applying a material having a relatively high dielectric constant compared to the display layer to the surface of a lower electrode region having a relatively small area compared to other lower electrode regions, so that the capacitor capacitance of a segment region corresponding to the lower electrode region having a relatively small area can be increased.

A method for controlling a display device according to one embodiment of the present invention comprises forming one or more capacitor capacitance-controlling electrodes, each of which is coated with a material having a different permittivity from those of an upper substrate and a display layer, in an area other than a lower electrode for controlling a display portion on a lower substrate, and selectively applying a driving voltage to one or more capacitor capacitance-controlling electrodes, thereby enabling the intensity of an electric field formed in segments to be controlled in detail by a relative capacitor capacitance difference.

A method for controlling a display device according to one embodiment of the present invention comprises: selectively controlling three or more types of electrophoretic particles having different threshold voltages by controlling voltage and polarity applied to asymmetrically formed segments; and saturation of electrophoretic particles having relatively low threshold voltages can be segmented by controlling capacitor capacitance of segments to which voltage of the same sign is supplied.

A method for manufacturing a display device according to one embodiment of the present invention may include the steps of: manufacturing a lower substrate on which a plurality of lower electrodes having various electrode areas are formed in order to form asymmetrically formed segments; and bonding an upper substrate on which a display layer is formed and the lower substrate using a conductive adhesive layer.

When the display layer is configured in the form of a plurality of unit cells, the method may include a step of forming a plurality of unit cells separated by a partition wall on an upper common electrode; a step of preparing a fluid including one or more types of electrophoretic particles; a step of injecting the fluid into the plurality of unit cells; and a step of forming a sealing layer to prevent the fluid from leaking or escaping.

When the display layer is composed of a plurality of microcapsule forms, the method may include the steps of preparing a fluid containing one or more types of electrophoretic particles; sealing the fluid in the form of microcapsules; preparing a slurry by mixing the microcapsules with a binder; and coating the slurry containing the microcapsules on an upper common electrode and then curing or drying it to form a display layer.

The technology of the present invention has the advantage of maximizing the display area and significantly reducing the sealing/finishing area where color is not implemented compared to conventional technologies because there is no need to form a separate channel for supplying voltage to the upper substrate constituting the panel in order to operate the display device, and the panel manufacturing process is simple and the manufacturing cost can also be greatly reduced.

The display device according to the present invention can form a specific electric field in a selected unit cell without supplying the common electrode Vcom to GND voltage of the upper portion, so that a separate process for connecting the common electrode and the Vcom electrode of the lower substrate is not required, and since a separate electrode for supplying the Vcom to GND voltage is not formed on the lower substrate, the display area can be utilized to the maximum regardless of the area of the common electrode compared to the conventional technology, and the manufacturing cost can be greatly reduced along with an improvement in the yield.

The display device according to the present invention has the advantages of being easy to manufacture panels of various shapes compared to conventional technologies, controlling electrophoretic particles having different driving voltages by using a driving board that outputs a uniform voltage without using an expensive driving board with high power consumption, implementing various colors by further segmenting the contrast ratio and saturation compared to conventional technologies, and being applicable to various reflective display devices or variable transmittance devices having capacitor characteristics in addition to display devices based on electrophoretic technology.

Since the display device according to the present invention does not require direct voltage supply to the common electrode in order to control electrophoretic particles by a vertical electric field, securing an opening for supplying voltage to the common electrode and a process for connecting a conductive material are not required, thereby simplifying the panel manufacturing process compared to conventional technologies and reducing the manufacturing time with improved yield.

The display device according to the present invention can maximize the display area and significantly reduce the sealing/finishing area where color or image is not implemented, thereby reducing the material cost and component cost consumed for manufacturing the panel compared to conventional technologies, and has the advantage of being able to manufacture panels of relatively various shapes regardless of the display area and having fewer restrictions on product design.

The control method of a display device according to the present invention controls the sign and number of voltages supplied to unit cells or segments, thereby electrically controlling the capacitor electrostatic capacitance to variously control the intensity of the voltage distributed to each unit cell or segment, so that even if the intensity of the voltage supplied from a driving unit to a panel is the same, electrophoretic particles having different threshold voltages or response times can be selectively controlled, and has the advantage of being able to control a relatively larger number of electrophoretic particles having different threshold voltages or response times using a driving board with the same performance compared to conventional technologies.

The method for manufacturing a display device according to the present invention has the advantage of reducing manufacturing costs since, since the values of the voltages output from the driving board do not have to be different, a complex driving waveform and control method are not required in order to control electrophoretic particles having different driving voltages, compared to conventional technologies, and a high-performance driving board with relatively high power consumption is not required.

The display device according to the present invention has the advantage of being able to implement various colors by further improving the contrast ratio and saturation compared to conventional technologies.

The display device according to the present invention has the advantage of being applicable to various reflective display devices or variable transmittance display devices that control the display layer by a vertically formed electric field and structurally have capacitor characteristics, such as a twistball type display device that implements color by rotating particles according to the direction of a formed electric field, and an electrowetting type display device that implements color by utilizing the characteristic of changing surface tension when an electric field is applied to a fluid surface.

The display device according to the present invention is applied to packaging materials that change color for products such as interior furniture and home appliances, where the finish of the product is very important, and has the advantage of being able to be used for the external appearance and price reduction of various products that require unit cells or segments having different areas.

Figures 1a, 1b and 1c are schematic diagrams showing the structure and connection method of a capacitor.
FIGS. 2A, 2B and 2C are cross-sectional views of an electrophoretic technology-based display device showing a conventional method of controlling electrophoretic particles by vertical/horizontal electric fields.
Figures 3a and 3b are cross-sectional views of a conventional electrophoretic technology-based display device.
FIG. 4 is a cross-sectional view of a display device including two or more types of color electrophoretic particles having different threshold voltages.
FIG. 5a is a schematic diagram showing the structure of a reflective display device based on electrophoretic technology having capacitor characteristics according to one embodiment of the present invention.
FIGS. 5b and 5c are cross-sectional views showing the structure of a reflective display device based on electrophoretic technology having capacitor characteristics according to one embodiment of the present invention.
FIGS. 5d and e are photographs of a display unit of a reflective display device based on electrophoretic technology having capacitor characteristics according to one embodiment of the present invention.
Figures 6a and b are schematic diagrams showing a capacitor circuit configuration for comparing the capacitor characteristics of each unit cell of a display device.
FIGS. 7a to 7e are photographs of a display unit that drives a display device test panel according to FIGS. 5a to 5e and FIG. 6b of the present invention.
FIG. 8 is a cross-sectional view of a panel or display device composed of unit cells or segments having different areas according to one embodiment of the present invention.
FIG. 9 is a schematic diagram showing the structure of a test panel having segments of different areas manufactured according to one embodiment of the present invention.
FIGS. 10a to 10e are photographs showing a driving method and results of a test panel manufactured by FIGS. 9a to d according to one embodiment of the present invention.
FIGS. 11a and 11b are photographs showing the results of driving a display device capable of selectively controlling capacitor capacity characteristics of a unit cell or segment according to one embodiment of the present invention.
FIG. 12 is a schematic diagram of a display device capable of controlling the relative capacitor capacity difference between unit cells or segments according to one embodiment of the present invention.
FIGS. 13a and 13b are cross-sectional views of a display device showing a method for controlling electrophoretic particles having different threshold voltages of a display device having the same area of unit cells or segments according to one embodiment of the present invention.
FIGS. 14a, b, and c are driving photographs of a display device showing a method for controlling electrophoretic particles having different threshold voltages in a display device having different areas of unit cells or segments according to one embodiment of the present invention.
FIGS. 15a and 15b are cross-sectional views of a display device manufactured in combination with a method of supplying a Vcom voltage or a GND voltage to an upper common electrode according to one embodiment of the present invention.

The present invention can be modified in various ways and has various embodiments, and specific embodiments are illustrated in the drawings and described in detail in the detailed description. The effects and features of the present invention and the methods for achieving them will become clear with reference to the embodiments described in detail below together with the drawings. However, the present invention is not limited to the embodiments disclosed below, and can be implemented in various forms.

Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings. When describing with reference to the drawings, identical or corresponding components are given the same drawing reference numerals and redundant descriptions thereof are omitted.

In the following examples, the terms first, second, etc. are not used in a limiting sense but are used for the purpose of distinguishing one component from another component. Also, in the following examples, singular expressions include plural expressions unless the context clearly indicates otherwise.

In the examples below, terms such as “include” or “have” mean that a feature or component described in the specification is present, and do not exclude in advance the possibility that one or more other features or components may be added.

FIG. 5a is a schematic diagram showing the structure of a reflective display device based on electrophoretic technology having capacitor characteristics according to one embodiment of the present invention.

FIGS. 5b and 5c are cross-sectional views showing the structure of a reflective display device based on electrophoretic technology having capacitor characteristics according to one embodiment of the present invention.

FIGS. 5d and e are photographs of a display unit of a reflective display device based on electrophoretic technology having capacitor characteristics according to one embodiment of the present invention.

Referring to FIG. 5a, the present invention relates to a reflective display device based on electrophoretic technology having capacitor characteristics, wherein an electric field can be formed in selected unit cells or segments without supplying Vcom to GND voltage to an upper common electrode, so that a separate process for connecting the common electrode and the Vcom electrode of the lower substrate is not required, and since a separate electrode for supplying Vcom to GND voltage is not formed on the lower substrate, it is possible to manufacture a panel capable of maximizing the display area (512) and minimizing the sealing and finishing area, regardless of the area of the common electrode, compared to conventional technologies.

That is, the display unit (512) panel of the display device manufactured by attaching the display layer (511) formed on the upper substrate (501) onto the lower electrode (507) for manufacturing the display unit formed on the lower substrate (508) using a conductive adhesive material has the advantage of a simple panel manufacturing process, improved product yield, and significantly reduced manufacturing costs compared to conventional technologies.

In addition, since the sealing/finishing area is greatly reduced, there are fewer restrictions compared to conventional technologies, making it easy to manufacture panels in various shapes, and it has the advantage of being able to be applied to various products that place relative importance on design.

Referring to FIGS. 5b and c, in order for the panel to have capacitor characteristics, a common electrode (upper electrode) (502) formed on the upper substrate (501), which is a display portion, and one or more lower electrodes (507) to which voltage can be applied independently are positioned at positions facing the common electrode (502).

At this time, the sizes of the areas of the independently separated lower electrodes (507) may be the same or different. Between the common electrode (502) and the lower electrodes (507), a display layer (511) is positioned, which has a fluid (505) inside containing at least one type of electrophoretic particles (first particles (504), second particles (506)).

Referring to FIG. 5b, when the display layer (511) is configured in the form of a plurality of unit cells separated by partition walls (503), after a plurality of unit cells are formed by the partition walls (503) in the upper electrode (502), a fluid (505) containing electrophoretic particles (first particles (504), second particles (506)) is injected or filled into the unit cells, and then a sealing layer (not shown) is formed to prevent the fluid (505) from leaking or escaping.

In addition, a conductive adhesive layer (509) is provided between the sealing layer and the lower electrode (507) so that an electric field is formed in the display layer (511) by a voltage applied from the outside and the display layer (511) and the lower electrode (507) can be attached or bonded. At this time, if an adhesive layer that performs a sealing layer function is applied to the conductive adhesive layer (509), the sealing layer may not be provided.

Referring to FIG. 5b, the display layer may also be formed as a display layer in the form of a microcapsule (not shown). In order to manufacture a panel in which a display layer is formed in the form of a microcapsule, a fluid containing electrophoretic particles is sealed in the form of a microcapsule, the microcapsules are mixed with a binder to manufacture a slurry, and then the slurry containing the microcapsules is coated on an upper electrode and cured or dried to form a display layer, and a conductive adhesive layer is provided between the microcapsule layer and the lower electrode.

Referring to FIG. 5b, the area of the unit cell affecting the resolution depends entirely on the area of the patterned lower electrode (507).

Referring to Fig. 5b, in order to form an electric field for controlling electrophoretic particles, the Vcom to GND voltage is not supplied to the common electrode (502) of the upper substrate (501), and the unit cells or segments can perform the role of conductors for having the characteristics of a capacitor. In addition, the unit cells or segments having each capacitor characteristic can perform the role of conductors that are connected in parallel or series.

Referring to FIG. 5b, the capacitance of the unit cells or segments can be electrically controlled by the voltage applied to the plurality of lower electrodes 1 (5071), 2 (5072), 3 (5073), and 4 (5074) where the unit cells or segments are located, and the strength and direction of the formed electric field can be controlled by controlling the strength of the voltage distributed to the unit cells or segments to be driven.

Referring to FIG. 5b, if the areas of the unit cells or segments constituting the display layer (511) are the same, the area of the lower electrode (507) facing the upper common electrode (502) and the dielectric constant of the material (display layer (511)) located between the two electrodes are all the same, so the electrostatic capacitance of each unit cell or segment having capacitor characteristics is the same.

Accordingly, when the same number of voltages of a positive sign (+V) and a voltage of a negative sign (-V), which is a relative GND voltage, are supplied to the lower electrodes (507) where independently separated unit cells are located, as shown on the right side of Fig. 5b, the unit cells to which voltages of the same sign are applied take on a structure in which multiple capacitors are connected in parallel by a common electrode (502) that also performs the function of a conductor, and have the effect of being connected in series with the unit cells corresponding to the electrodes to which the polarity of the opposite sign is applied.

At this time, since the number of capacitors connected in parallel is the same and the electrostatic capacitance is the same, the voltage distributed to each unit cell is the same, and finally, since two capacitors with the electrostatic capacitance doubled are connected in series, the voltage distributed to the unit cell is half the total supply voltage according to the capacitor formula (V1=V2=V3=V4=V/2).

In addition, when an electric field formed in each unit cell is formed by a voltage distributed by the capacitor characteristics, the area of the common electrode (502) facing the lower electrodes (507) has a polarity opposite to the polarity of the voltage applied to the lower electrode (507).

Referring to FIG. 5d, as an example of FIG. 5b, a display layer (511) was formed on an upper substrate (501) in which negatively charged white electrophoretic particles (506) and positively charged black electrophoretic particles (504) were dispersed in a transparent fluid (505) and then microencapsulated, and a panel was manufactured by attaching four lower electrodes (507) having the same electrode area and spacing between the electrodes to a lower substrate (508). A +15 V voltage and a relative GND voltage were supplied to the lower electrodes (507) on which two segments (seg. 1 and seg. 3) were located.

Referring to Fig. 5d, since the circuit has the characteristic that two capacitors with the same capacity are connected in series, the voltage distributed to each segment is +7.5 V (voltage across the two conductors in the Seg. 3 region) and -7.5 V (voltage across the two conductors in the Seg. 1 region) based on the lower electrode direction, and the direction of the electric field formed in each segment is also determined by the polarity formed at both ends of the conductor in each segment.

As a result, white particles with a negative charge moved in the direction of the lower electrode of the segment to which +15 V was applied due to the vertical electric field formed, and black particles with a positive charge moved to the upper common electrode region located opposite the lower electrode to which +15 V was applied, thereby displaying a black image (Seg. 3) on the display unit. In addition, black particles with a positive charge moved in the direction of the lower electrode of the segment to which -V voltage was applied due to the relative GND voltage, and white particles with a negative charge moved to the common electrode region of the upper substrate located opposite the lower electrode to which -V voltage was applied, thereby displaying a white image (Seg. 1) on the display unit.

Referring to FIG. 5c, when a positive voltage (+V) and a negative voltage (-V), which is a relative GND voltage of the positive voltage, are supplied to unit cells or segments asymmetrically, unit cells to which voltages of the same sign are applied circuitally have the characteristic of multiple capacitors being connected in parallel, so that they have the same capacitance, but have different capacitances from unit cells to which voltages of the opposite sign are applied.

At this time, if the number of unit cells to which voltages of the same sign are applied is large, the total area of the two conductors that determine the capacitor capacitance facing each other is relatively large, so the capacitor capacitance is relatively large in terms of the circuit, and the magnitude of the voltage distributed to the unit cells configured in parallel in the circuit is the same, but the magnitude of the distributed voltage is smaller than that of the unit cells to which voltages of the opposite sign are applied in a relatively small number.

That is, when the unit cells configured in parallel are connected in series according to the polarity of the supplied voltage, the voltage distributed to the unit cells with relatively small total capacitance is large.

Referring to FIG. 5e, as an embodiment of FIG. 5c, +15 V is applied to three segments (Seg. 2, Seg. 3, Seg. 4), and a negative voltage, which is a relative GND voltage, is applied to the lower electrode of one segment. From a circuit perspective, three capacitors having the same capacitance are connected in parallel and one capacitor is connected in series, and since the total capacitance of the capacitors configured in parallel is three times that of one capacitor connected in series, the voltage distributed to the segment (Seg. 1) having a relatively small capacitor capacitance is -10.5 V with respect to the lower electrode direction, and the voltages distributed to the segments (Seg. 1, Seg. 2, Seg. 3) having a large total capacitor capacitance are all +3.5 V.

As a result, in the segment to which -V is applied, black particles with a positive charge move toward the lower electrode due to the vertical electric field formed by the distributed voltage, and white particles with a negative charge move to the common electrode region located at the opposite position, thereby displaying a white image (Seg. 1). On the other hand, in the area of the segments to which +V is applied, the intensity of the distributed voltage is small, so that the electric field intensity is not sufficiently formed for the electrophoretic particles to move, and thus the particles do not move, and the previously implemented images (Seg. 2, Seg. 3, Seg. 4) are maintained as they are.

Figures 6a and b are schematic diagrams showing a capacitor circuit configuration for comparing the capacitor characteristics of each unit cell of a display device.

FIG. 6a is a schematic diagram showing a capacitor circuit configuration in which a voltage of V com to GND is applied to a common electrode according to a conventional driving method in terms of the polarity of the voltage applied to the lower electrode constituting each unit cell of the display device.

FIG. 6b is a schematic diagram showing a capacitor circuit configuration in which, according to an embodiment of the present invention, the polarity of the voltage applied to the lower electrode constituting each unit cell of the display device is such that the V com to GND voltage is not applied to the common electrode according to the driving method of the present invention.

Referring to FIGS. 6a and b, when the areas of the upper and lower electrodes constituting the unit cell according to the driving method of the present invention are all the same, unlike the conventional method of applying Vcom to a common electrode, the polarity of the applied voltage and the number of voltages supplied are controlled to electrically control the electrostatic capacitance of each unit cell or segment having a capacitor characteristic in the circuit, and the intensity of the voltage distributed to each unit cell or segment and the direction of the formed electric field can be controlled.

In addition, by maximizing the difference in capacitor electrostatic capacitance, the intensity of the electric field formed in the unit cells or segments can be generated lower than the minimum threshold voltage at which electrophoretic particles can move, so that only specific unit cells or segments can be selectively driven.

Referring to FIG. 6b, the technology of the present invention can control the contrast ratio and saturation by controlling the amount of electrophoretic particles moving to the display section by a potential difference differently formed by a capacitor electrostatic capacitance difference.

In addition, since the speed at which electrophoretic particles move can be controlled through the time at which voltage is supplied to the unit cells, it has the advantage of being able to further refine the contrast ratio and saturation compared to conventional technologies.

FIGS. 7a to 7e are photographs of a display unit that drives a display device test panel according to FIGS. 5a to 5e and FIG. 6b of the present invention.

Referring to Fig. 7a, for this experiment, a test panel was manufactured by attaching an upper substrate on which an electrophoretic display layer was formed to a lower substrate on which 16 lower electrodes having an area of 2 cm × 2 cm were formed at 0.1 mm intervals using a conductive adhesive layer.

Referring to FIG. 7b, it is a photograph showing the control of the contrast ratio of colors implemented by controlling the number of segments to which voltage is supplied and the time for which voltage is applied to the test panel manufactured in FIG. 7a, thereby controlling the number of electrophoretic particles moving to the display section.

Figures 7c and d are photographs of selectively driving one segment in the test panel manufactured in Figure 7a.

Figure 7e is a photograph of a test panel in which the display portion of the test panel manufactured in Figure 7a is implemented with the same color and each segment is driven sequentially.

FIG. 8 is a cross-sectional view of a panel or display device composed of unit cells or segments having different areas according to one embodiment of the present invention.

Referring to FIG. 8, in order for the panel to have capacitor characteristics, a common electrode (upper electrode) (802) formed on an upper substrate (801), which is a display portion, and one or more lower electrodes (807) to which voltage can be independently applied at positions facing the common electrode (802) are positioned on the lower substrate (808). At this time, the sizes of the areas of the independently separated lower electrodes (807) are different. Between the common electrode (802) and the lower electrodes (807), a display layer (811) is positioned which has a fluid (805) therein, which includes at least one type of electrophoretic particles (first particles, second particles) (804)(806).

Referring to FIG. 8, when the display layer (811) is configured in the form of a plurality of unit cells separated by partition walls (803), after a plurality of unit cells are formed by the partition walls (803) in the upper electrode (802), a fluid (805) containing electrophoretic particles (first particles, second particles) (804) (806) is injected or filled into the unit cells, and then a sealing layer (not shown) is formed to prevent the fluid (805) from leaking or escaping.

Referring to Fig. 8, the display layer may also be formed as a display layer in the form of a microcapsule (not shown). In order to manufacture a panel in which a display layer is formed in the form of a microcapsule, a fluid containing electrophoretic particles is sealed in the form of a microcapsule, the microcapsules are mixed with a binder to manufacture a slurry, and then the slurry containing the microcapsules is coated on an upper electrode and cured or dried to form a display layer.

In addition, a conductive adhesive layer (809) is provided between the sealing layer and the lower electrode (807) so that an electric field is formed in the display layer (811) by a voltage applied from the outside and the display layer (811) and the lower electrode (807) can be attached or bonded. At this time, if an adhesive layer that performs a sealing layer function is applied to the conductive adhesive layer (809), the sealing layer may not be provided.

Referring to Fig. 8, in the case where an electrophoretic technology-based display device is applied as a color-changing packaging material for products such as interior furniture and home appliances where the product finish is very important, unit cells or segments having different areas may be required for the purpose of reducing the appearance and price of various products.

Referring to FIG. 8, the technology of the present invention can also be applied to a panel or display device composed of unit cells or segments having different areas.

If the areas of the unit cells or segments constituting the display portion are different, the capacitor capacitance of the unit cells or segments having a relatively large area of the lower electrode facing the common electrode is large, so when the unit cells or segments exhibit capacitor characteristics due to the applied voltage, the magnitude of the voltage distributed to the unit cells or segments having a relatively large area is low.

At this time, if the intensity of the electric field formed by distributing the supply voltage to the unit cells or segments having a relatively large area is lower than the intensity of the threshold voltage for the electrophoretic particles to move, or if the supply voltage is applied for a time corresponding to the response time of the electrophoretic particles located in the unit cells or segments having a relatively small area, the electrophoretic particles located in the unit cells or segments having a relatively large area may not move to the upper electrode, which is the display portion, or may only move partly.

A method for selectively driving a unit cell or segment having a relatively large area comprises: supplying voltages of the same sign to a plurality of unit cells or segments so that the circuit has capacitor characteristics that are connected in parallel, and making the total electrostatic capacitance greater than the electrostatic capacitance of the unit cells or segments having a relatively large area, thereby increasing the intensity of the voltage distributed to the unit cells or segments having a relatively large area.

FIG. 9 is a schematic diagram showing the structure of a test panel having segments of different areas manufactured according to one embodiment of the present invention.

Referring to Fig. 9, in order to configure segments with different areas, a lower substrate (901) having a plurality of lower electrodes (A, B, C, D) having various electrode areas was formed, and an upper substrate (902) having an electrophoretic display layer formed thereon was bonded/laminated (903) with a conductive adhesive layer to produce a test panel (904). At this time, the total area of the lower substrate was made larger than that of the upper substrate, which is the display portion, so that a voltage can be selectively applied to the lower electrodes where each segment is located, thereby exposing a portion of the lower electrodes.

FIGS. 10a to 10e are photographs showing a driving method and results of a test panel manufactured by FIGS. 9a to d according to one embodiment of the present invention.

Referring to Fig. 10a, when voltage was supplied to the test panel manufactured by Figs. 9a to d and driven, it was confirmed that the voltage intensity distributed to the segment with the largest area was significantly lower than that to the segment with the smallest area.

Referring to Fig. 10b, when voltage was supplied to the test panel manufactured by Figs. 9a to 9d and driven, it was confirmed that when the segments have similar areas, the intensity of the distributed voltage was also similar.

Referring to Fig. 10c, when the test panel manufactured by Figs. 9a to 9d was driven by supplying voltage, when the difference in the areas of the two segments was large, voltages of opposite signs were cross-supplied to the two segments, and it was confirmed that the segment with the largest area did not show any color change because the intensity of the generated electric field was not sufficient to allow the electrophoretic particles to move toward the upper electrode, while only the segment with the smallest area showed a color change.

Referring to Fig. 10d, when the test panel manufactured by Figs. 9a to 9d was driven by supplying voltage, it was confirmed that when a supply voltage of the same sign was applied to multiple segments other than the segment with the largest area and a voltage of the opposite sign was applied to the lower electrode of the segment with the largest area, the color of the segment with the largest area was also changed.

Referring to Fig. 10e, when the test panel manufactured by Figs. 9a to 9d is driven by supplying voltage, when the driving methods in Figs. 10a to 10d are combined, the colors of segments having different areas can be selectively changed or multiple segments can be operated so that all have the same color.

FIGS. 11a and 11b are photographs showing the results of driving a display device capable of selectively controlling capacitor capacity characteristics of a unit cell or segment according to one embodiment of the present invention.

Referring to FIGS. 11a and b, a material having a different permittivity from that of the display layer is placed on the surface of some electrodes formed on the lower substrate to set different capacitor capacitances, thereby controlling the intensity of the voltage distributed to each unit cell or segment. By applying this method, only a unit cell or segment having a relatively large area can be selectively driven to change color, or a plurality of segments having a relatively small area can be controlled to operate simultaneously, without electrically coupling a plurality of unit cells or segments.

That is, the capacitor capacitance can be controlled by placing a material having a different dielectric constant from that of the display layer on some of the lower electrodes.

Referring to FIG. 11a, as a driving method for increasing the capacitor capacitance of a lower electrode region having a relatively small area, a material (1102) having a relatively high dielectric constant compared to a display layer was applied to the surface of a lower electrode region A (1101) having a relatively small area compared to a lower electrode region B (1101), and then an upper substrate (1103) on which a display layer was formed was laminated/bonded to produce a test panel (1104).

Referring to Fig. 11b, when a driving voltage was applied to the lower electrodes of two segments having different areas of the test panel (1105) manufactured in Fig. 11a, it was confirmed that the colors of both segments changed according to the direction of the changing electric field. At this time, the area difference of the two segments was larger than that of the segments shown in Fig. 10c, where the segment having a relatively large area did not operate.

In addition, in order to control the capacitor capacitance of each unit cell or segment, the dielectric constant of the fluid in which the electrophoretic particles are dispersed, the binder/sealant, and the conductive adhesive layer required to form the display layer can be adjusted, and the capacitor characteristics can be strengthened by forming a dielectric layer on the upper/lower electrode surfaces.

FIG. 12 is a schematic diagram of a display device capable of controlling the relative capacitor capacity difference between unit cells or segments according to one embodiment of the present invention.

Referring to FIG. 12, in order to control the relative capacitor capacitance difference of unit cells or segments, one or more capacitor capacitance-controlling electrodes (1201) coated with a material different from the permittivity of the upper substrate/display layer (1204) can be formed in an area other than the lower electrode (1203) for display control on the lower substrate (1202), and a driving voltage can be selectively applied to a plurality of capacitor capacitance-controlling electrodes (1201) to control the intensity of an electric field formed in unit cells or segments by the relative capacitor capacitance difference in detail.

That is, even if the voltage intensity applied from the driving unit is the same, the voltage intensity distributed to the unit cells or segments can be controlled by using the electrodes (1201) for controlling the capacitor electrostatic capacitance.

FIGS. 13a and 13b are cross-sectional views of a display device showing a method for controlling electrophoretic particles having different threshold voltages of a display device having the same area of unit cells or segments according to one embodiment of the present invention.

Referring to FIGS. 13a and b, a common electrode (upper electrode) (1302) formed on an upper substrate (1301) which is a display portion, and one or more lower electrodes (1309) to which a voltage can be independently applied at positions facing the common electrode (1302) are positioned on a lower substrate (1310). At this time, the sizes of the areas of the independently separated lower electrodes (1309) are the same. A display layer (1311) having a fluid (1307) therein, which includes at least one type of electrophoretic particles (first particle (1304), second particle (1305), and third particle (1306)), is positioned between the common electrode (1302) and the lower electrodes (1309).

Referring to FIGS. 13a and b, when the display layer (1311) is configured in the form of a plurality of unit cells separated by partition walls (1303), after a plurality of unit cells are formed by the partition walls (1303) on the upper electrode (1302), a sealing layer (not shown) is formed to prevent the fluid from leaking or escaping after a fluid containing electrophoretic particles is injected or filled into the unit cells. In addition, a conductive adhesive layer (1308) is provided between the sealing layer and the lower electrode (1309) so that an electric field is formed in the display layer (1311) by a voltage applied from the outside and the display layer (1311) and the lower electrode (1309) can be attached or bonded. At this time, an adhesive layer performing a sealing layer function may be applied to the conductive adhesive layer (1308).

Referring to FIGS. 13a and b, in a reflective display device that displays colors by selectively controlling one or more types of electrophoretic particles (first particle (1304), second particle (1305), third particle (1306)) having different threshold voltages or response times, in the past, different voltages corresponding to the threshold voltages of each electrophoretic particle were directly supplied to unit cells or segments of a panel to implement various colors.

However, since the conventional technology method requires the direct output of different voltage intensities from the driving board, as the number of different voltages to be output increases, relatively high-performance components with high power consumption and high prices are required, and relatively complex driving circuits, driving waveforms, and programming are required.

Referring to FIGS. 13a and b, even if the intensity of the voltage supplied from the driving board (not shown) to the panel is the same, the intensity of the voltage distributed to the unit cells or segments can be controlled by adjusting the sign and number of the applied voltages supplied to the unit cells or segments of uniform area. In addition, even if the intensity of the voltage supplied from the driving board is the same, the intensity of the electric field formed in the unit cells or segments to be driven can be variously adjusted, so that electrophoretic particles having different threshold voltages or response times can be selectively controlled.

Referring to FIG. 13b, by controlling the number of capacitors connected in parallel in the circuit, the electrostatic capacitance of unit cells or segments can be controlled, thereby dividing the strength of the electric field formed by the distributed voltage, and thus the number of electrophoretic particles (first particle (1304), second particle (1305), third particle (1306)) having different threshold voltages or response times can be controlled to move toward the common electrode (1302), thereby providing an advantage of a wider range of contrast ratios and saturation that can be implemented compared to conventional technologies.

In particular, compared to conventional technologies, a larger number of electrophoretic particles having different threshold voltages or response times can be selectively controlled using a driving board of the same performance.

FIGS. 14a, b, and c are driving photographs of a display device showing a method for controlling electrophoretic particles having different threshold voltages in a display device having different areas of unit cells or segments according to one embodiment of the present invention.

Referring to FIGS. 14a, b, and c, as described in FIGS. 10, 11, and 12 above, the number and polarity of voltages applied to a plurality of unit cells or segments having different areas can be adjusted to control the intensity of the electric field formed in each unit cell or segment, thereby selectively controlling electrophoretic particles having different threshold voltages.

Referring to FIGS. 14a, b, and c, in order to form segments with different areas as fabricated in FIG. 9, a lower substrate (901) having a plurality of lower electrodes (A, B, C, and D) having different electrode areas is formed, and an upper substrate (902) having an electrophoretic display layer including black, white, and red electrophoretic particles with different threshold voltages is formed, and the upper substrate (902) is bonded/laminated (903) with a conductive adhesive layer to fabricate a test panel (904) having different segment areas.

Referring to Figs. 14a, b, and c, white electrophoretic particles have negative charges, red and black electrophoretic particles have positive charges, and black electrophoretic particles have a higher threshold voltage than red electrophoretic particles. The input voltage to the fabricated test panel was fixed at +15 V, and the +15 V voltage supplied from the power supply and the GND voltage were applied crosswise to the segment with the largest area and the segment with the smallest area.

Referring to Fig. 14a, it was confirmed that the color of the segment area with the largest area did not change, while the color of the segment area with the smallest area changed between white and black depending on the polarity of the voltage applied.

Referring to Fig. 14b, in order to operate the segment with the largest area, a voltage of the same sign was applied to the lower electrodes where the remaining multiple segments are located, excluding the segment with the largest area, and a voltage of the opposite sign was applied to the segment with the largest area. As a result, the color in the area of the segment with the largest area changed between white and black depending on the sign of the applied voltage.

In order to reduce the capacitance of the capacitors connected in parallel relative to each other and thus lower the voltage distributed to the segment with the largest area, the number of segments to which the same voltage is supplied was reduced while the display was white, and a voltage of +15 V was applied and a voltage of the opposite sign was applied to the lower electrode where the segment with the largest area was located. As a result, the voltage distributed to the segment with the largest area in terms of the circuit was lowered, and red electrophoretic particles with a relatively low threshold voltage moved toward the upper electrode to implement a red color.

Referring to Fig. 14c, it was confirmed that red having different saturation was implemented as a result of further controlling red particles with relatively low threshold voltages by controlling the number of segments supplied with voltage of the same sign (i.e., controlling the capacitor capacitance of the segments).

FIGS. 15a and 15b are cross-sectional views of a display device manufactured in combination with a method of supplying a Vcom voltage or a GND voltage to an upper common electrode according to one embodiment of the present invention.

Referring to FIGS. 15a and b, a reflective display device that uses a fluid as a medium and controls electrophoretic particles by a vertical electric field has a structure in which a display layer (1504) including electronic ink in which charged electrophoretic first particles (1504), second particles (1505), and third particles (1506) are dispersed in a fluid (1507) is formed between an upper electrode (1502) in contact with an upper substrate (1501) and a lower electrode (1509) in contact with a lower substrate (1510) which are respectively formed on one side, and in order to fill and seal the electronic ink, cells separated by partition walls (1503) are formed on the upper substrate (1501), and after filling the electronic ink, they are sealed with a sealing layer or a conductive adhesive layer (1508) to form the display layer (1504). A panel of a display device can be manufactured by attaching a display layer (1504) formed on the upper substrate (1501) and a lower electrode (1509).

Referring to FIG. 15a, in order to control electrophoretic particles having a relatively high threshold voltage by a vertically formed electric field, in order to smoothly supply a driving voltage from a driving board (1511) to a panel, a portion of a display layer (1504) is removed and cleaned/dried, and then a conductive material (1512) is filled or attached to the corresponding opening (1515) to form a separate electrode (1513) on a lower substrate (1510) to which a Vcom or GND voltage is supplied, and a common voltage, Vcom or GND voltage, is supplied to a common electrode (1502) formed on an upper substrate (1501) through the separate electrode (1513) so as to control.

Referring to Fig. 15b, in order to operate electrophoretic particles having a relatively low threshold voltage, the number of voltages of the same sign applied to only a plurality of lower electrodes (1509) can be controlled by adjusting the number of times the common electrode (1502) is not separately supplied with a Vcom voltage or a GND voltage.

At this time, the voltage output from the driving board (1511) and supplied to the panel is the same.

By applying the driving method according to Figs. 15a and b, it has the advantage of being able to further refine the contrast ratio and saturation compared to conventional technology even when using a driving board with the same performance.

In addition, the techniques of the present invention described above have the advantage of being applicable to various reflective display devices or variable transmittance display devices that control the display layer by a vertically formed electric field and structurally have capacitor characteristics, such as a twistball type display device that implements color by rotating particles according to the direction of the formed electric field, and an electrowetting type display device that implements color by utilizing the characteristic of changing surface tension when an electric field is applied to a fluid surface.

The materials and manufacturing process required for manufacturing the display test panel and display device of the present invention are referred to the contents disclosed in the following patent of the same applicant registered prior to this application.

KR 10-1984763 B1 (2019.05.27.)

KR 10-1913709 B1 (2018.10.25.)

KR 10-2102294 B1 (2020.04.13.)

KR 10-2255328 B1 (2021.05.17.)

KR 10-2156044 B1 (2020.09.09.)

KR 10-2156063 B1 (2020.09.09.)

KR 10-2340892 B1 (2021.12.14.)

Claims (10)

upper board;
Substrate;
A common electrode arranged on one surface of the upper substrate;
A lower electrode arranged on one surface of the lower substrate;
A display layer having a fluid inside including at least one type of electrophoretic particles between the common electrode and the lower electrode; and
The display layer and the lower electrode include a conductive adhesive layer between them,
The above lower electrode is composed of a plurality of lower electrodes having different sizes of independently separated areas,
The above display layer includes segments formed asymmetrically,
The above segments have capacitor characteristics and are structurally set to have different electrostatic capacitances.
A display device utilizing capacitor characteristics, characterized in that a separate channel for supplying voltage to the common electrode is not required.
In the first paragraph,
A display device utilizing capacitor characteristics, characterized in that the entire area of the lower substrate is manufactured to be wider than the upper substrate, which is a display portion, so that a portion of the plurality of lower electrodes is exposed so as to selectively apply voltage to the plurality of lower electrodes where each of the above segments is located.
In the second paragraph,
A display device utilizing capacitor characteristics, wherein the above segments include a plurality of unit cells or a plurality of microcapsules separated by partitions.
In the second paragraph,
A display device utilizing capacitor characteristics, characterized in that the capacitor capacitance is controlled by controlling the fluid in which the electrophoretic particles are dispersed, the binder or sealant necessary to form the display layer, and the dielectric constant of the conductive adhesive layer, or by forming a dielectric layer on the surface of the upper common electrode or the lower electrode.
A method for controlling the display device of Article 4,
A method for controlling a display device using capacitor characteristics, characterized in that a material having a relatively high dielectric constant compared to the display layer is applied to the surface of a lower electrode region having a relatively small area compared to other lower electrode regions, thereby increasing the capacitor capacitance of a segment region corresponding to the lower electrode region having a relatively small area.
A method for controlling the display device of Article 4,
A method for controlling a display device using capacitor characteristics, characterized in that one or more capacitor capacitance-controlling electrodes are formed in an area other than a lower electrode for controlling a display portion on a lower substrate, wherein a material having a different permittivity from that of an upper substrate and a display layer is applied, and a driving voltage is selectively applied to one or more capacitor capacitance-controlling electrodes, thereby enabling the intensity of an electric field formed in segments to be controlled in detail by a relative capacitor capacitance difference.
A method for controlling the display device of Article 4,
A method for controlling a display device using capacitor characteristics, characterized in that three or more types of electrophoretic particles having different threshold voltages can be selectively controlled by controlling the voltage and polarity applied to asymmetrically formed segments, and the saturation of electrophoretic particles having relatively low threshold voltages can be segmented by controlling the capacitor capacitance of segments supplied with voltage of the same sign.
A method for manufacturing a display device according to the second paragraph,
In order to form segments that are formed asymmetrically, having various electrode areas
A step of manufacturing a lower substrate on which a plurality of lower electrodes are formed; and
A method for manufacturing a display device utilizing capacitor characteristics, characterized by including a step of bonding an upper substrate having a display layer formed thereon and the lower substrate with a conductive adhesive layer.
In Article 8,
When the above display layer is configured in the form of multiple unit cells,
A step of forming a plurality of unit cells separated by a partition wall on an upper common electrode;
A step of preparing a fluid containing one or more types of electrophoretic particles;
a step of injecting the fluid into the plurality of unit cells; and
A method for manufacturing a display device utilizing capacitor characteristics, characterized by including a step of forming a sealing layer to prevent the fluid from leaking or escaping.
In Article 8,
When the above display layer is composed of multiple microcapsule forms,
A step of preparing a fluid containing one or more types of electrophoretic particles;
A step of sealing the above fluid in the form of a microcapsule; and
A step of preparing a slurry by mixing the above microcapsules into a binder; and
A method for manufacturing a display device utilizing capacitor characteristics, characterized by comprising a step of forming a display layer by coating a slurry containing the microcapsules on an upper common electrode and then curing or drying the same.