A color electronic paper display device based on metasurface

Abstract

A color electronic paper display device based on a metasurface includes a first substrate and a second substrate spaced apart from each other, a first electrode layer and a second electrode layer, a metasurface filter layer disposed on the first electrode layer, an electrophoretic medium layer disposed between the metasurface filter layer and the second electrode layer, the metasurface filter layer including a micro-nano particle layer having a periodically arranged particle structure, and the electrophoretic medium layer including a dispersant and black electrophoretic particles; the black electrophoretic particles are positively or negatively charged, and voltages of opposite polarity are applied to the first and second electrode layers, respectively, so that the black electrophoretic particles can be adsorbed on or away from the metasurface filter layer. The color electronic paper display device based on a metasurface provided by the present invention, by introducing a metasurface filter layer and utilizing a metasurface unit array structure to control the reflectance spectrum of natural light to achieve a filtering effect, while simultaneously improving reflective output and reducing angular sensitivity.

Description

Technical Field

[0001] The present invention relates to a display device, and in particular to a color electronic paper display device. Background Art

[0002] Electronic paper mainly uses electrophoretic display technology. Because its display effect is very close to that of ordinary paper, it has the characteristics of high contrast, wide viewing angle, low energy consumption and high reading comfort, and is widely used in many fields.

[0003] Electrophoretic display technology is a bi-stable reflective electronic paper display technology. Because it does not require constant driving during display, it has the advantage of ultra-low power consumption and broad application prospects. Existing electronic paper products typically utilize Lambertian reflection of ambient light to achieve their display functions. To further improve display brightness and contrast, for example, Chinese invention patent publication number CN110928098A uses a high-reflectivity material as an optical enhancement layer and utilizes electrophoretic particles with different characteristics to achieve simultaneous display of dark and bright states, while also displaying details in both dark and bright areas. However, this electronic paper display structure can only achieve black and white grayscale display functions and cannot display color.

[0004] Electrophoretic ink particles are driven to rise or fall onto the electrode surface by their positive or negative charge and the direction of the applied voltage. To achieve color display, more particles of the same charge but different colors must be separated, which can increase the image refresh time and affect the display quality. Chinese Invention Patent Publication No. CN110322844A proposes a method for achieving color electrophoretic display. This method controls the three sub-pixels of a color EPD pixel unit, achieving color display through color mixing and shortening the image refresh time of color e-paper.

[0005] Furthermore, using color filters to achieve color electronic paper displays is a relatively mature and mass-produced solution, based on the same principle as LCDs. However, because color filters filter out a significant amount of ambient light, the resulting electronic paper is relatively dim, and the color rendering is difficult to achieve. For example, Chinese invention patent application publication number CN110568691A proposes a solution for designing multiple structural patterns on color filter subpixels, thereby increasing the light transmittance and reflection of the color filter. Chinese invention patent application publication number CN112198732A proposes a solution for using a micro-nanostructured anti-reflection layer to increase the reflective light output and reduce the angular sensitivity of the electronic paper. By adjusting structural parameters such as the height, duty cycle, and period of the micro-nanostructures, the color rendering of the color electronic paper can be effectively improved, enhancing the color rendering effect. However, due to the limitations of the filtering principle, the different color filters within a display pixel cannot overlap, resulting in a small number of pixels per unit display area and the inability to achieve high-resolution display. Therefore, the development of electronic paper technology with inherent wavelength-selective properties that can achieve color display without the need for color filters is essential. Currently, color display technologies that do not require color filters primarily include cholesteric liquid crystal electronic paper, photonic crystal displays, and electrochromic displays. Chinese invention patent application publication number CN111562697A proposes a method to address the low reflectivity of cholesteric liquid crystals in the long-wavelength, broad-spectrum region, providing solutions to the cost, color gamut, and refresh rate issues associated with color electronic paper displays.

[0006] However, existing color e-paper display structures are typically complex. The color filter elements require material deposition through a fine metal mask. This process limits the reduction of the filter element size due to shadowing during deposition. Furthermore, the drooping effect of large, fine metal masks also restricts the increase in overall display size. Consequently, traditional color filters suffer from low display resolution, poor detail, and limited display size, impacting the user experience. Summary of the Invention

[0007] In order to overcome the deficiencies in the background technology, the present invention provides a color electronic paper display device based on a metasurface, which can not only realize color display but also has high resolution and compact size.

[0008] According to one aspect of the present invention, a color electronic paper display device based on a metasurface is provided.

[0009] The invention comprises a first substrate and a second substrate which are spaced apart from each other, wherein a first electrode layer and a second electrode layer are respectively provided on opposite surfaces of the first substrate and the second substrate, and is characterized in that:

[0010] An ultra-surface filter layer is provided on the surface of the first electrode layer facing the second electrode layer, an electrophoretic medium layer is provided between the ultra-surface filter layer and the second electrode, the ultra-surface filter layer includes a micro-nano particle layer, the micro-nano particle layer includes a periodically arranged particle structure, the particle structure is arranged toward the electrophoretic medium layer, and the electrophoretic medium layer includes a dispersant and black electrophoretic particles;

[0011] The black electrophoretic particles are positively or negatively charged, and voltages of opposite polarities are applied to the first electrode layer and the second electrode layer, respectively, so that the black electrophoretic particles can be adsorbed on the supersurface filter layer or away from the supersurface filter layer.

[0012] Preferably, the size of the black electrophoretic particles should be smaller than or equal to the period of the particle structure minus the outer diameter of the particle structure.

[0013] Preferably, the size of the black electrophoretic particles is 10 nm-500 nm.

[0014] Preferably, a plurality of pixel units are formed on the first substrate and the second substrate, and the super-surface filter layer is provided with a plurality of filter units corresponding to the plurality of pixel units, and the filter units include at least one first sub-filter unit reflecting red light, at least one second sub-filter unit reflecting green light, and at least one third sub-filter unit reflecting blue light.

[0015] Preferably, the reflection wavelength of the first sub-filter unit is between 580 nm and 780 nm, and the corresponding array period of the particle structure is between 300 nm and 500 nm, wherein the height or depth of the particle structure is between 50 nm and 200 nm, and the outer diameter of the particle structure is at least 20 nm and at most less than or equal to the period size;

[0016] The reflection wavelength of the second sub-filter unit is 500nm to 580nm, the corresponding array period of the particle structure is 200nm to 400nm, the height or depth of the particle structure is 50nm to 200nm, the minimum outer diameter is 20nm, and the maximum is less than or equal to the period size;

[0017] The reflection wavelength of the third sub-filter unit is 420nm-500nm, the corresponding array period of the particle structure is 100nm-300nm, the height or depth of the particle structure is 50nm-200nm, the minimum outer diameter is 20nm, and the maximum is less than or equal to the period size.

[0018] Preferably, the electrophoretic medium layer further comprises a dispersant, and the dispersant is a transparent material;

[0019] The material of the black electrophoretic particles is at least one of carbon, silicon, a polymer coated with a black dye, and a liquid crystal molecule coated with a black dye;

[0020] The black dye is at least one of carbon black, iron oxide black, copper chrome black, iron chrome black and aniline black;

[0021] The polymer in the black dye-coated polymer is at least one of polyimide (PI), polyethylene terephthalate (PET) and polyethylene naphthalene-2,6-dicarboxylate (PEN);

[0022] The liquid crystal molecules in the liquid crystal molecules coated with the black dye are at least one of nematic liquid crystal, smectic liquid crystal, cholesteric liquid crystal, blue phase liquid crystal and ferroelectric liquid crystal.

[0023] Preferably, the particle structure is a columnar protrusion structure or a columnar concave hole structure.

[0024] Preferably, the material of the granular structure is at least one of a metal material or a dielectric material, and is a material that excites localized surface plasmon resonance (LSPR) in the visible light band. For example, the metal material is gold, silver, copper, or aluminum, and the dielectric material is silicon, silicon oxide, aluminum oxide, titanium dioxide, or zinc oxide.

[0025] Preferably, a plurality of pixel units are formed on the first substrate and the second substrate, the first electrode layer and the second electrode layer have switch electrodes corresponding to each pixel unit, the pixel unit includes at least one red sub-pixel unit, at least one green sub-pixel unit and at least one blue sub-pixel unit, and the sub-filter unit is arranged corresponding to the sub-pixel unit.

[0026] Preferably, the supersurface filter layer also includes a substrate layer, which is arranged between the first electrode layer and the micro-nano particle layer, and the material of the substrate layer is at least one of colorless optical glass, silicon oxide, aluminum oxide, polydimethylsiloxane (PDMS), polymethyl methacrylate (PMMA), SU8 photoresist or polystyrene.

[0027] The metasurface-based color electronic paper display device provided by the present invention achieves a filtering effect by introducing a metasurface filter layer and utilizing a metasurface unit array structure to control the reflection spectrum of natural light. The spectral characteristics of the metasurface units are related to the parameters of the unit structure. By adjusting structural parameters such as the structure's shape, size, and period, the reflection spectral characteristics of the three metasurface sub-filter units can be made consistent with the spectral characteristics of red, green, and blue, respectively, while simultaneously improving the reflective output and reducing angular sensitivity. When natural light enters the metasurface filter layer, the three metasurface sub-filter units reflect red, green, and blue light, respectively, achieving a reflective filtering effect.

[0028] The electrophoretic medium layer includes a dispersant and dark-state particles. When the dark-state particles are driven by voltage and approach the metasurface filter layer, they absorb the evanescent field near the metasurface filter layer, thereby displaying a dark state; when the dark-state particles are driven by voltage and move away from the metasurface filter layer, they do not absorb the evanescent field near the metasurface filter layer, thereby displaying a bright state. In the bright state, the electronic paper displays according to the mixed color of the light reflected by the sub-filter unit in each filter unit.

[0029] The metasurface filter layer is composed of an array of subwavelength-scale units, which offers a high degree of spectral adjustment freedom. Furthermore, subwavelength-scale filter units facilitate the compression of e-paper pixel size, further improving the display resolution and optimizing the display quality.

[0030] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present application, nor is it intended to limit the scope of the present application. Other features of the present application will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the embodiments of the present invention. The same reference numerals are used throughout the accompanying drawings to denote the same components. In the accompanying drawings:

[0032] Figure 1 Schematic diagram of a color electronic paper display device based on a metasurface according to an embodiment of the present invention;

[0033] Figure 2 is a schematic diagram of a filter unit according to a first embodiment of the present invention;

[0034] Figure 3 is a schematic plan view of a filter unit according to a first embodiment of the present invention;

[0035] Figure 4 Schematic diagram of the reflection wavelength of each sub-filter unit of the filter unit in the first embodiment of the present invention;

[0036] Figure 5 Schematic diagram of the reflection wavelength of each sub-filter unit of the filter unit in the second embodiment of the present invention;

[0037] Figure 6 is a schematic diagram of a filter unit according to a third embodiment of the present invention;

[0038] Figure 7 is a schematic plan view of a filter unit according to a third embodiment of the present invention;

[0039] Figure 8 Schematic diagram of the reflection wavelength of each sub-filter unit of the filter unit according to the third embodiment of the present invention. DETAILED DESCRIPTION

[0040] Exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0041] It should be noted that the terms "first" and "second" as used in the embodiments of the present invention are merely used to distinguish similar objects and do not represent a specific ordering of the objects. It is understood that the terms "first" and "second" may interchangeably represent a specific order or precedence where permitted. It should be understood that the objects distinguished by "first" and "second" may interchangeably represent a specific order or precedence where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than that illustrated or described herein.

[0042] like Figure 1 FIG. 1 is a schematic diagram of a color electronic paper display device based on a metasurface according to an embodiment of the present invention, comprising a first substrate 1 and a second substrate 6 arranged relatively spaced apart, wherein a first electrode layer 2 and a second electrode layer 5 are provided on the opposing surfaces of the first substrate 1 and the second substrate 6, respectively, a metasurface filter layer 3 is provided on the surface of the first electrode layer 2 facing the second electrode layer 5, and an electrophoretic medium layer 4 is provided between the metasurface filter layer 3 and the second electrode layer 5. Figure 1 As shown, from top to bottom are the first substrate 1, the first electrode layer 2, the supersurface filter layer 3, the electrophoretic medium layer 4, the second electrode layer 5 and the second substrate 6.

[0043] The first substrate 1 and the second substrate 6 are transparent plastic substrates, such as polyimide (PI), polyethylene terephthalate (PET), polyethylene naphthalene-2,6-dicarboxylate (PEN), etc.

[0044] The first electrode layer and the second electrode layer are both transparent electrodes, and the transparent electrodes can be one or more of indium tin oxide (ITO), graphene, oxide glass (TCO), ultra-thin metal silver, aluminum, and copper. The structure of the first and second substrates and the first and second electrode layers is similar to that of a liquid crystal display. A plurality of pixel units are formed on the first and second substrates. The first and second electrode layers have switch electrodes corresponding to each pixel unit, and then a voltage is applied to the electrophoretic medium layer 4 on a pixel basis. Moreover, each pixel unit can also be divided into sub-pixel units. The sub-pixel units in the multiple pixel units can be driven as a whole or separately, and can be set as needed.

[0045] The electrophoretic medium layer 4 includes a dispersant 41 and black electrophoretic particles 42. The material of the black electrophoretic particles 42 can be at least one of carbon, silicon, a black dye-coated polymer, and a black dye-coated liquid crystal molecule. The black dye can be carbon black, iron oxide black, copper chromium black, iron chromium black, aniline black, etc. The polymer in the black dye-coated polymer can be polyimide (PI), polyethylene terephthalate (PET), polyethylene naphthalene-2,6-dicarboxylate (PEN), etc. The liquid crystal molecules in the black dye-coated liquid crystal molecule can be at least one of nematic liquid crystal, smectic liquid crystal, cholesteric liquid crystal, blue phase liquid crystal, and ferroelectric liquid crystal. The dispersant is a transparent material, such as water, air, ethanol, halogenated hydrocarbons, aromatic hydrocarbons, etc.

[0046] The size of the black electrophoretic particles is 10 nm to 500 nm. The reason for selecting this size range will be explained in detail in the following part of the specification. Preferably, the mass percentage of the black electrophoretic particles accounts for 1% to 65% of the electrophoretic medium layer 4.

[0047] like Figure 1 As shown, the metasurface filter layer 3 includes a substrate layer 31 and a micro-nano particle layer 32. The substrate layer 31 is provided on the first electrode layer 2, and the micro-nano particle layer 32 is located between the substrate layer 31 and the electrophoretic medium layer 4. That is, the particle structure on the micro-nano particle layer is arranged toward the electrophoretic medium layer 4. It will also be understood by those skilled in the art that the substrate layer 31 can also be omitted, and the micro-nano particle layer 32 can be directly provided on the first electrode layer 2.

[0048] The substrate layer 31 is made of at least one of colorless optical glass, silicon oxide, aluminum oxide, polydimethylsiloxane (PDMS), polymethyl methacrylate (PMMA), SU8 photoresist, or polystyrene. The colorless optical glass may be commonly used materials such as BK7, SF10, or BAK1. The micro-nano particle layer 32 includes a particle structure 321 periodically arranged in a matrix array. The periodicity in two perpendicular directions of the matrix is ​​uniform, the particle structure 321 is subwavelength in size, and the particle structure 321 may be a cylindrical protrusion structure or a cylindrical concave hole structure, i.e., the horizontal cross-section of the particle structure 321 remains consistent. The cylindrical protrusion structure may be a cylinder, a square prism, or a cross-shaped prism. The concave hole structure may be a cylindrical concave hole, a square prism concave hole, or a cross-shaped cylindrical concave hole, etc. The material of the particle structure is at least one of a metal material or a dielectric material, as long as it can excite localized surface plasmon resonance (LSPR) in the visible light band. The metal material can be gold, silver, copper, aluminum, etc. The dielectric material can be at least one of silicon, silicon oxide, aluminum oxide, titanium dioxide, or zinc oxide.

[0049] The metasurface filter layer 3 corresponds to the pixel units and is divided into multiple filter units 33. The size of the filter units 33 ranges from 1μm×1μm to 1000μm×1000μm. Each filter unit 33 corresponds to a pixel unit, and each filter unit 33 also includes multiple sub-filter units, including at least three sub-filter units: a first sub-filter unit 331 that reflects red light and transmits other light, a second sub-filter unit 332 that reflects green light and transmits other light, and a third sub-filter unit 333 that reflects blue light and transmits other light. The array period and size of the particle structure 321 of each sub-filter unit are different, thereby reflecting different wavelengths. The subwavelength structure of the metasurface unit can achieve field enhancement at specific frequency positions. This frequency selectivity of the metasurface can give it a specific reflection spectrum, thereby achieving color display. The sub-filter units are arranged to correspond to the sub-pixel units of each pixel unit. That is, a pixel unit includes at least one red sub-pixel unit (R sub-pixel unit), at least one green sub-pixel unit (G sub-pixel unit), and at least one blue sub-pixel unit (B sub-pixel unit). The filter unit also includes at least one of the three sub-filter units. For example, if a pixel unit includes four sub-pixel units (R, G, and two B), the filter unit includes a first sub-filter unit, a second sub-filter unit, and two third sub-filter units.

[0050] The wavelength reflected by the first sub-filter unit 331 is between 580 nm and 780 nm. The array period of the particle structure is between 300 nm and 500 nm, wherein the height or depth of the particle structure is between 50 nm and 200 nm. The outer diameter of the particle structure is at least 20 nm and does not exceed the period. For example, if the particle structure is a cylindrical protrusion or a cylindrical recess, the diameter of the cylindrical protrusion or cylindrical recess is the outer diameter, and the diameter is at least 20 nm and does not exceed the period. If the particle structure is a square prism protrusion structure, the side length of the square prism is the outer diameter, and the diameter is at least 20 nm and does not exceed the period. If the particle structure is a cross-shaped cylindrical protrusion or a cross-shaped cylindrical recess, the length of the cross is the outer diameter, and so on.

[0051] The wavelength reflected by the second sub-filter unit 332 is between 500nm and 580nm, the array period of the particle structure is between 200nm and 400nm, the height or depth of the particle structure is between 50nm and 200nm, the minimum outer diameter is 20nm, and the maximum does not exceed the period size, that is, it is less than or equal to the period size.

[0052] The wavelength reflected by the third sub-filter unit 333 is 420nm-500nm, the array period of the particle structure is 100nm-300nm, the height or depth of the particle structure is 50nm-200nm, the minimum outer diameter is 20nm, and the maximum does not exceed the period size.

[0053] Those skilled in the art will appreciate that the period of the particle structure refers to the spacing between the centers of the particle structures arranged in a matrix, and the outer diameter refers to the outer diameter of the particle structure in the direction of the line connecting the centers of the particle structures, such as the diameter of a cylinder, the side length of a square cylinder, or the length of a cross-shaped cylinder. Preferably, the particle structure is centrally symmetrical.

[0054] Each filter unit has at least one of each of the three sub-filter units. When there is one of each of the three sub-filter units, the different sub-filter units can be of different sizes as needed, or they can be of the same size. Alternatively, the filter unit can include four sub-filter units, with one first sub-filter unit, one second sub-filter unit, and two third sub-filter units, each of which is of the same size. Those skilled in the art can customize these sub-filter units based on the display's desired contrast, brightness, and resolution. Correspondingly, the pixel unit also has multiple sub-pixel units corresponding to the sub-filter units. The driving voltage of each sub-pixel unit is controlled by the first electrode layer and the second electrode layer.

[0055] Taking a single pixel unit as an example, which includes a plurality of sub-pixel units, when no electric field is applied between the first electrode layer 2 and the second electrode layer 5 on the pixel unit, as shown in FIG. Figure 1 As shown, black electrophoretic particles are randomly dispersed in a dispersant. Natural light passes through the first electrode layer 2 and reaches the metasurface filter layer 3. For each filter unit, the first sub-filter unit reflects red light with high efficiency while transmitting visible light in other bands, resulting in a red color (R). The second sub-filter unit reflects green light with high efficiency while transmitting visible light in other bands, resulting in a green color (G). The third sub-filter unit reflects blue light with high efficiency while transmitting visible light in other bands, resulting in a blue color (B). At this point, the entire electronic paper appears as a whiteboard.

[0056] When an electric field is applied between the first electrode layer 2 and the second electrode layer 5 on the pixel unit, as shown in FIG. Figure 2 As shown, for example, a positive voltage is applied to the first electrode layer 2 and a negative voltage is applied to the second electrode layer 5. The black electrophoretic particles 42 are negatively charged and move toward the first electrode layer 2. When natural light is incident on the metasurface filter layer 3 from the side of the first electrode layer 2, an evanescent field exists around the particle structure 321 in the metasurface filter layer 3. When the black electrophoretic particles 42 move into the range of the evanescent field, the evanescent field is absorbed by the black electrophoretic particles, causing the filter unit to not reflect natural light, thereby displaying a dark state.

[0057] When the electrodes are flipped, when a negative voltage is applied to the first electrode layer 2 and a positive voltage is applied to the second electrode layer 5, the black electrophoretic particles 42 are negatively charged, and the black electrophoretic particles 42 move toward the second electrode layer 5. When natural light is incident on the supersurface filter layer 3 from the side of the first electrode layer 2, an evanescent field exists around the particle structure 321 in the supersurface filter layer 3, but the evanescent field is not absorbed, so it is displayed in a bright state. At this time, the filter unit reflects natural light, which is displayed as the composite color of its reflection. Therefore, as long as the voltage on the corresponding electrode layer set on different sub-pixel units is controlled, the color display effect of the color electronic paper can be obtained. By controlling the voltage level, the number of black electrophoretic particles 42 adsorbed on the supersurface filter layer 3 can be controlled, thereby achieving brightness adjustment of different sub-pixel units and color adjustment of the mixed color of each pixel unit.

[0058] Alternatively, it can be an adjustment commonly used by those skilled in the art. The above-mentioned black electrophoretic particles 42 are negatively charged, or can be set to be positively charged. At this time, when a positive voltage is applied to the first electrode layer 2 and a negative voltage is applied to the second electrode layer 5, it is displayed as the composite color reflected by it, and when a negative voltage is applied to the first electrode layer 2 and a positive voltage is applied to the second electrode layer 5, it is displayed in a dark state.

[0059] In other words, the black electrophoretic particles 42 can be set to a positive or negative charge. By applying voltages of different polarities to the first and second electrode layers, the black electrophoretic particles will move toward the electrode layer with the opposite polarity, allowing them to adsorb onto the surface of the supersurface filter layer 3 or move away from it. When the first electrode layer 2 (i.e., the electrode layer on the side of the supersurface filter layer 3) has an opposite voltage, the black electrophoretic particles can move toward the supersurface filter layer 3 and adsorb around the particle structures 321 of the supersurface filter layer 3. The evanescent field around the particle structures 321 in the supersurface filter layer 3 is absorbed by the black electrophoretic particles, causing the entire electronic paper to appear dark. When the electrode layer on the side of the supersurface filter layer has the same voltage as the black electrophoretic particles, the black electrophoretic particles will move away from the supersurface filter layer 3, achieving a bright state for the electronic paper. Simultaneously, the supersurface filter layer acts as a reflective filter, displaying reflected colors.

[0060] In order for the black electrophoretic particles 42 to be adsorbed around the particle structure when power is applied, the particle structure and the electrophoretic particles must match in size. That is, the size of the black electrophoretic particles 42 should be smaller than that of the particle structure. For example, if the particle structure has a period of 420 nm and a diameter of 220 nm, and the intergranular gap is 200 nm, the size of the electrophoretic particles should be no larger than 200 nm to enable adsorption around the particle structure under voltage control. In other words, the size of the black electrophoretic particles should be less than or equal to the period of the particle structure minus the outer diameter of the particle structure.

[0061] Example 1:

[0062] like Figure 1 As shown in FIG, a schematic diagram of the structure of the color electronic paper display device based on the metasurface of this embodiment is shown in FIG. Figure 2 、 3 Figure 2 shows a schematic diagram of a filter unit in the metasurface filter layer 3. The filter unit comprises four sub-filter units: a first sub-filter unit 331, a second sub-filter unit 332, and two third sub-filter units 333. The four sub-filter units are arranged in a matrix of equal size, with the two third sub-filter units 333 arranged diagonally. Each sub-filter unit measures 1.2 μm x 1.2 μm. The particle structure 321 is a cylindrical protrusion. The material of the substrate layer 31 of the metasurface filter layer 3 is SiO2, and the particle structure is made of Si.

[0063] The particle structure of the first sub-filter unit 331 has a height of 80 nm, a diameter of 220 nm, and a period of 420 nm. The particle structure of the second sub-filter unit 332 has a height of 80 nm, a diameter of 160 nm, and a period of 360 nm. The particle structure of the third sub-filter unit 333 has a height of 80 nm, a diameter of 120 nm, and a period of 180 nm. Accordingly, the material of the dispersant 41 in the electrophoretic medium layer 4 is air, and the size of the black electrophoretic particles 42 in the electrophoretic medium layer is 10 nm. The reflection spectra of the three sub-filter units are shown in FIG. Figure 4 shown.

[0064] Example 2:

[0065] In this embodiment of the metasurface-based color electronic paper display device, the metasurface filter layer does not include a substrate layer; the granular structure is located directly on the first electrode layer 2. The filter unit includes four sub-filter units: a first sub-filter unit 331, a second sub-filter unit 332, and two third sub-filter units 333. The four sub-filter units are arranged in a matrix of equal size, with the two third sub-filter units 333 arranged diagonally. Each sub-filter unit measures 1.2 μm x 1.2 μm. The granular structure 321 is a cylindrical protrusion, and the material of the granular structure of the metasurface filter layer 3 is Si.

[0066] The particle structure of the first sub-filter unit has a height of 70 nm, a diameter of 160 nm, and a period of 370 nm. The particle structure of the second sub-filter unit has a height of 70 nm, a diameter of 140 nm, and a period of 300 nm. The particle structure of the third sub-filter unit has a height of 70 nm, a diameter of 120 nm, and a period of 180 nm. Accordingly, the material of the dispersant 41 in the electrophoretic medium layer is water, and the size of the electrophoretic particles 42 in the electrophoretic medium layer is 10 nm. The reflection spectra of the three sub-filter units are shown in FIG. Figure 5 .

[0067] Example 3:

[0068] In the color electronic paper display device based on the metasurface of this embodiment, the metasurface filter layer does not include a substrate layer, and the particle structure is directly located on the first electrode layer 2. The filter unit of the metasurface filter layer 3 is shown in FIG. Figure 6 、 7 As shown, the filter unit includes four sub-filter units: a first sub-filter unit 331, a second sub-filter unit 332, and two third sub-filter units 333. The four sub-filter units are arranged in a matrix of equal size, with the two third sub-filter units 333 arranged diagonally. Each sub-filter unit measures 0.9 μm x 0.9 μm. The particle structure 321 is a cross-shaped raised structure, and the material of the particle structure of the super-surface filter layer 3 is Si.

[0069] The particle structure height of the first sub-filter unit is 140 nm, the length L of the cross-shaped protrusion structure is 190 nm, the width W of the cross-shaped protrusion structure is 100 nm, and the period is 300 nm. The particle structure height of the second sub-filter unit is 140 nm, the length L of the cross-shaped protrusion structure is 210 nm, the width W is 40 nm, and the period is 300 nm. The particle structure height of the third sub-filter unit is 140 nm, the length L of the cross-shaped protrusion structure is 120 nm, the width W is 40 nm, and the period is 180 nm. Accordingly, the material of the dispersant 41 in the electrophoretic medium layer is water, and the size of the electrophoretic particles 42 in the electrophoretic medium layer is 10 nm. The reflection spectra of the three sub-filter units are shown in Figure 1. Figure 8 .

[0070] Optical metasurfaces, as a new type of artificial composite subwavelength structure, possess unique physical properties. They enable the manipulation of optical parameters such as amplitude, phase, and polarization state. Metasurfaces offer the advantages of high design freedom, high control precision, and ultra-thin structures, allowing for low-cost nanofabrication. Therefore, metasurfaces can be used as filter layers in color electronic paper displays, not only facilitating large-scale, high-resolution color displays but also further reducing the thickness of electronic paper and improving the integration of the structure.

[0071] The metasurface-based color electronic paper display device provided by the present invention achieves a filtering effect by introducing a metasurface filter layer and utilizing a metasurface unit array structure to control the reflection spectrum of natural light. The spectral characteristics of the metasurface units are related to the parameters of the unit structure. By adjusting structural parameters such as the structure's shape, size, and period, the reflection spectral characteristics of the three metasurface sub-filter units can be made consistent with the spectral characteristics of red, green, and blue, respectively, while simultaneously improving the reflective output and reducing angular sensitivity. When natural light enters the metasurface filter layer, the three metasurface sub-filter units reflect red, green, and blue light, respectively, achieving a reflective filtering effect.

[0072] The electrophoretic particles in the electrophoretic medium layer include dark state particles, which can absorb the evanescent field at the interface between the supersurface filter layer and the electrophoretic medium layer, thereby displaying a dark state; when the dark state particles are away from the supersurface filter layer and do not absorb the evanescent field, in the bright state, the electronic paper displays according to the mixed color of the reflected light of the sub-filter unit in each filter unit.

[0073] The metasurface filter layer is composed of an array of subwavelength-scale units, which offers a high degree of spectral adjustment freedom. Furthermore, subwavelength-scale filter units facilitate the compression of e-paper pixel size, further improving the display resolution and optimizing the display quality.

[0074] It should also be noted that the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, commodity, or apparatus that includes a series of elements includes not only those elements but also other elements not explicitly listed, or includes elements inherent to such process, method, commodity, or apparatus. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not exclude the presence of other identical elements in the process, method, commodity, or apparatus that includes the element.

[0075] It should be understood that the various forms of the processes shown above can be used to reorder, add, or delete steps. For example, the steps described in the present disclosure can be performed in parallel, sequentially, or in a different order, as long as the desired results of the technical solutions disclosed in the present disclosure can be achieved. This is not limited herein.

[0076] The above are merely embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should all be included within the scope of the claims of the present application.

Claims

1. A color electronic paper display device based on a metasurface, comprising a first substrate (1) and a second substrate (6) arranged relative to each other with a spacing therebetween, wherein a first electrode layer (2) and a second electrode layer (5) are respectively provided on opposing surfaces of the first substrate (1) and the second substrate (6), and characterized in that: An ultra-surface filter layer (3) is provided on the surface of the first electrode layer (2) facing the second electrode layer (5); an electrophoretic medium layer (4) is provided between the ultra-surface filter layer (3) and the second electrode (5); the ultra-surface filter layer (3) comprises a micro-nano particle layer (32); the micro-nano particle layer (32) comprises a periodically arranged particle structure (321); the particle structure (321) is arranged toward the electrophoretic medium layer (4); and the electrophoretic medium layer (4) comprises a dispersant (41) and black electrophoretic particles (42); The black electrophoretic particles (42) are positively or negatively charged, and voltages of opposite polarities are applied to the first electrode layer (2) and the second electrode layer (5), respectively, so that the black electrophoretic particles can be adsorbed on the ultrasurface filter layer (3) or away from the ultrasurface filter layer (3); The size of the black electrophoretic particles (42) is less than or equal to the period of the particle structure minus the outer diameter of the particle structure.

2. The color electronic paper display device based on a metasurface according to claim 1, wherein: The size of the black electrophoretic particles (42) is 10 nm to 500 nm.

3. The color electronic paper display device based on a metasurface according to claim 1, wherein: A plurality of pixel units are formed on the first substrate and the second substrate, and the super-surface filter layer (3) is provided with a plurality of filter units (33) corresponding to the plurality of pixel units. The filter units include at least one first sub-filter unit (331) reflecting red light, at least one second sub-filter unit (332) reflecting green light, and at least one third sub-filter unit (333) reflecting blue light.

4. The color electronic paper display device based on a metasurface according to claim 3, wherein: The reflection wavelength of the first sub-filter unit (331) is between 580nm and 780nm, and the array period of the corresponding particle structure is between 300nm and 500nm, wherein the height or depth of the particle structure is between 50nm and 200nm, and the outer diameter of the particle structure is at least 20nm and at most less than or equal to the period size; The reflection wavelength of the second sub-filter unit (332) is between 500nm and 580nm, the array period of the corresponding particle structure is between 200nm and 400nm, the height or depth of the particle structure is between 50nm and 200nm, the minimum outer diameter is 20nm, and the maximum is less than or equal to the period size; The reflection wavelength of the third sub-filter unit (333) is between 420nm and 500nm, the array period of the corresponding particle structure is 100nm-300nm, the height or depth of the particle structure is 50-200nm, the minimum outer diameter is 20nm, and the maximum is less than or equal to the period size.

5. The color electronic paper display device based on a metasurface according to claim 1, wherein: The dispersant (41) is a transparent material; The material of the black electrophoretic particles (42) is at least one of carbon, silicon, a polymer coated with a black dye, and a liquid crystal molecule coated with a black dye; The black dye is at least one of carbon black, iron oxide black, copper chrome black, iron chrome black and aniline black; The polymer in the black dye-coated polymer is at least one of polyimide (PI), polyethylene terephthalate (PET) and polyethylene naphthalene-2,6-dicarboxylate (PEN); The liquid crystal molecules in the liquid crystal molecules coated with the black dye are at least one of nematic liquid crystal, smectic liquid crystal, cholesteric liquid crystal, blue phase liquid crystal and ferroelectric liquid crystal.

6. The color electronic paper display device based on a metasurface according to any one of claims 1 to 5, characterized in that: The particle structure (321) is a columnar protrusion structure or a columnar concave hole structure.

7. The color electronic paper display device based on a metasurface according to any one of claims 1 to 5, characterized in that: The material of the particle structure (321) is at least one of a metal material and a dielectric material, and is a material that excites localized surface plasmon resonance (LSPR) in the visible light band.

8. The color electronic paper display device based on a metasurface according to any one of claims 1 to 5, characterized in that: A plurality of pixel units are formed on the first substrate and the second substrate, and the first electrode layer and the second electrode layer have switch electrodes corresponding to each pixel unit. The pixel unit includes at least one red sub-pixel unit, at least one green sub-pixel unit and at least one blue sub-pixel unit, and the sub-filter unit is arranged corresponding to the sub-pixel unit.

9. The color electronic paper display device based on a metasurface according to any one of claims 1 to 5, characterized in that: The supersurface filter layer (3) further comprises a substrate layer (31), wherein the substrate layer (31) is arranged between the first electrode layer (2) and the micro-nano particle layer (32), and the material of the substrate layer (31) is at least one of colorless optical glass, silicon oxide, aluminum oxide, polydimethylsiloxane (PDMS), polymethyl methacrylate (PMMA), SU8 photoresist or polystyrene.

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