Electrowetting display device and preparation method and application thereofTechnical Field
The invention relates to the technical field of electrowetting display, in particular to an electrowetting display device, a preparation method and application thereof.
Background
With the continuous development of information technology, electrowetting display technology has been greatly advanced, and intensive research is being conducted at home and abroad in order to achieve the purpose of reflective display. At present, a scattering film layer capable of reflecting ambient light is mainly added in electronic paper for displaying a reflective display device, and a visual effect is achieved through reflection of the ambient light. At present, a metal reflecting layer is generally adopted, however, the mirror reflection is remarkable, the visible angle is small, and the display effect of the display device is poor.
Disclosure of Invention
The present invention aims to solve at least one of the technical problems existing in the prior art. Therefore, the invention provides an electrowetting display device which has the characteristics of wide visible angle and good display effect.
The invention also provides a preparation method of the electrowetting display device.
The invention also provides application of the electrowetting display device.
In a first aspect of the present invention, an electrowetting display device is provided, including a reflective support assembly, an electrowetting display layer, and a transmissive support assembly, which are stacked from bottom to top, where the reflective support assembly includes a first substrate and a diffuse reflection layer from bottom to top, and the diffuse reflection layer includes an optical embossing relief microstructure layer disposed on a lower layer and a specular reflection layer disposed on an upper layer, and the optical embossing relief microstructure layer is an undulating micro-scale microstructure layer prepared according to an optical embossing technique.
The electrowetting display device according to the embodiment of the invention has at least the following beneficial effects:
The electrowetting display device is a diffuse reflection electrowetting display device with wider visual angle, wherein the addition of the light embossing relief microstructure layer utilizes the diffuse reflection of the light embossing relief microstructure layer to incident light so that more ambient light can be reflected into human eyes through the diffuse reflection layer, and the particle diffuse reflection generates reflection light with larger reflection angle to the ambient light, so that the visual angle of the diffuse reflection layer device is widened, the visual angle of the electrowetting display device is widened, the display effect of the device is improved, the problem that the display effect of the traditional reflection electrowetting display device is poor is solved, the diffuse reflectance can be effectively improved, the visual angle is widened, the display effect is better when watching, and the device is applicable to outdoor high-brightness environment, green and environment-friendly and has good application prospect.
In some embodiments of the invention, the first substrate comprises a first light transmissive substrate. Optionally, the material of the first light-transmitting substrate may be glass. Optionally, the thickness of the first substrate includes 0.5-0.8mm.
In some embodiments of the invention, the photoimprinting relief microstructure layer is an irregularly undulating microstructure layer. Optionally, the thickness of the photo-embossed relief microstructure layer comprises 0.1-3 μm, further optionally 0.5-2 μm. In order to ensure the paper-like effect of the electronic paper, the photo-embossing relief microstructure layer of the electrowetting display device has smaller thickness, and the thickness can be several micrometers.
In some embodiments of the invention, the reflective support assembly further comprises a first electrode disposed between the first substrate and the diffuse reflective layer, a hydrophobic insulating layer disposed between the diffuse reflective layer and the electrowetting display layer.
In some embodiments of the invention, the first electrode is a transparent material. Optionally, the first electrode includes, but is not limited to, a metal-based electrode or Indium Tin Oxide (ITO). Further, the thickness of the first electrode comprises 20-30nm.
In some embodiments of the invention, the thickness of the hydrophobic insulating layer comprises 0.4-1 μm.
In some embodiments of the present invention, the electrowetting display layer includes a sealing cavity and a pixel wall, the sealing cavity is formed by encapsulation of an encapsulation material between the reflective support component and the transmissive support component, the pixel wall is disposed on the surface of the hydrophobic insulating layer, the sealing cavity is filled with a first fluid and a second fluid which are mutually insoluble, pixel cells arranged in an array are formed by surrounding the pixel walls, and the first fluid is filled in the pixel cells.
In some embodiments of the invention, the distance between the reflective support component and the transmissive support component comprises 50-190 μm, further optionally 54.45-183.85 μm.
In some embodiments of the present invention, the encapsulating material includes, but is not limited to, a pressure sensitive adhesive.
In some embodiments of the invention, one of the first fluid and the second fluid is a polar fluid and the other is a non-polar fluid. Specifically, the first fluid is a nonpolar fluid and the second fluid is a polar fluid. Alternatively, the nonpolar fluids may be inks or other nonpolar fluids, and the polar fluid may be water or polar fluid containing alcohols or the like.
In some embodiments of the present invention, the electrowetting display layer is filled with two mutually immiscible fluids by means of ink-jet printing, and the contraction and expansion of the nonpolar fluid such as ink is controlled by an applied voltage, so as to control the display of the electrowetting device. Optionally, the first fluid and the second fluid are ink and water, respectively, and the voltage is regulated to cause the ink to contract and expand, thereby controlling the display of the electrowetting device. By the above embodiment, the first fluid may move or deform in the pixel cell under the condition of an applied voltage, such as a spread state or a contracted state in the pixel cell.
In some embodiments of the invention, the transmissive support assembly includes a second electrode and a second substrate stacked along the electrowetting display layer direction.
In some embodiments of the invention, the second electrode is a transparent material. Optionally, the second electrode includes, but is not limited to, a metal-based electrode or ITO. Further, the thickness of the second electrode comprises 20-30nm.
In some embodiments of the invention, the second substrate comprises a second light transmissive substrate. Optionally, the material of the second light-transmitting substrate may be glass. Further, the thickness of the second substrate is 0.5-0.8mm.
In some embodiments of the invention, the electrowetting display device further comprises a power regulation module. Optionally, the device is externally arranged with the power regulation module. The power regulation and control module is used for controlling the voltage between the reflective support component and the transmissive support component. Such as in particular the voltage between the first electrode and the second electrode. Specifically, the voltage generated by the power regulation and control module causes the fluid (such as ink) in the pixel unit cell to shrink, the display layer exposes the light-transmitting area, the ambient light reaches the light-embossing relief microstructure layer through the light-transmitting area of the display layer, and the diffuse reflection of the ambient light by the microstructure diffuse reflection structure (such as the light-embossing relief structure) achieves the effect of widening the display viewing angle.
The invention also provides a preparation method of the electrowetting display device, which comprises the steps of preparing the photo-embossing relief microstructure layer, and specifically comprises the following steps of (1) spin-coating a photopolymer on the surface of a substrate to obtain a photopolymer film, (2) drying the photopolymer film to remove a solvent, (3) performing mask exposure on the photopolymer film to generate a latent image, and (4) heating and developing a sample, and obtaining the photo-embossing relief microstructure layer after full exposure and solidification.
In some embodiments of the invention, the substrate may be the first electrode. Further, the substrate comprises a first substrate and a first electrode which are arranged in a stacked manner, and the silica dispersion liquid is coated on the surface of the first electrode.
In some embodiments of the invention, the photopolymer comprises a polymeric binder, a monomer, a retarder, and a photoinitiator. Alternatively, the polymeric binder comprises polymethyl methacrylate, the monomer comprises acrylic acid ester, the retarder comprises tert-butylhydroquinone, and the photoinitiator comprises Irgacure 819. Specifically, the mass fraction of the polymeric binder in the photopolymer is 10-40%, further optionally 20-30%, the mass fraction of the monomer is 10-30%, further optionally 20-30%, the mass fraction of the retarder is 0.1-20%, further optionally 1-10%, the mass fraction of the photoinitiator is 0.1-20%, further optionally 1-10%, and the mass fraction of the solvent is 30-60%, further optionally 40-50%.
In some embodiments of the invention, the photopolymer comprises polymethyl methacrylate and multifunctional acrylate in a 1:1 ratio, optionally the acrylate comprises dipentaerythritol penta/hexaacrylate.
In addition, the solvent in the photopolymer comprises a mixture of ethoxypropyl acetate and propylene glycol-methyl ethyl acetate in a ratio of 1:1. Specifically, the volume ratio of polymethyl methacrylate, dipentaerythritol penta/hexaacrylate, tert-butylhydroquinone, irgacure 819, ethoxypropyl acetate and propylene glycol-methyl ethyl acetate is selected from (20-30): (20-30): (1-10): (1-10): (40-50).
In some embodiments of the invention, the preparation of the photopolymer comprises the steps of taking the materials used for the photopolymer, mixing, heating and stirring to obtain the photopolymer. Optionally, the temperature of the heating and stirring is selected from 40-60 ℃, and the heating and stirring time is selected from 5-30min.
In some embodiments of the invention, in step (1), the spin-coating speed comprises 2000-3000 revolutions per minute and the spin-coating time comprises 10-180 seconds;
in some embodiments of the invention, in step (2), the drying temperature comprises 20-80 ℃ and the drying time comprises 10-180min;
In some embodiments of the invention, in step (3), the exposure light intensity comprises 10-20mW/cm2, the exposure time comprises 10-30s, and the size of the photoetching mask plate is 1 x1 cm. Specifically, the photolithographic mask contained a hexagonal filler material consisting of 30 μm transparent holes, with a spacing of 30 μm between the holes.
In some embodiments of the invention, in step (4), the heating temperature comprises 40-100 ℃ and the heating time comprises 1-10min. In addition, the exposure light intensity is selected from 10-20mW/cm2, and the exposure time is 10-30s.
In some embodiments of the invention, the preparation method of the electrowetting display device comprises the following steps of S1, preparing a photo-embossing relief microstructure layer on the surface of a first electrode to obtain a reflective support component, S2, preparing a pixel wall on the surface of the reflective support component, filling a first fluid in the pixel wall by using an ink-jet printing process, and assembling the pixel wall with a transmissive support component to obtain the electrowetting display device.
In some embodiments of the present invention, in step S1, a photo-embossing relief microstructure layer and a hydrophobic insulating layer are sequentially prepared on the surface of the first electrode, so as to obtain a reflective support assembly.
In some embodiments of the present invention, in step S2, the reflective support assembly includes a hydrophobic insulating layer, and the pixel wall is prepared on a surface of the hydrophobic insulating layer. Optionally, spin-coating photoresist on the surface of the hydrophobic insulating layer, exposing the photoresist through a mask plate, and developing to obtain the pixel wall.
In some embodiments of the present invention, in step S2, the reflective support assembly and the transmissive support assembly may be encapsulated using an encapsulation material according to a phase change lamination technique.
In a third aspect of the present invention, an application of the above electrowetting display device in the technical field of electrowetting display, LED or LCD display is presented.
Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the following description will briefly explain the drawings used in the embodiments or the description of the prior art, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic structural view of an electrowetting display device in embodiment 1 of the present invention;
FIG. 2 is a schematic diagram showing a cross-sectional structure of an electro-wetting display device in example 1 of the present invention when no voltage is applied;
FIG. 3 is a schematic view showing the reflection of a portion of the reflective layer of the electrowetting display device of comparative example 1;
FIG. 4 is a schematic view showing the reflection of a portion of a light beam from a photo-embossed relief microstructure layer in an electro-wetting display device according to embodiment 1 of the present invention;
FIG. 5 is a schematic view showing the light reflection of an electro-wetting display device according to the embodiment 1 of the invention;
FIG. 6 is a graph showing the light reflection effect of the electrowetting display device of comparative example 3;
FIG. 7 is a graph showing the effect of light reflection of the electrowetting display device in example 1 of the present invention;
Fig. 8 is a graph showing the light reflection effect of the electrowetting display device of comparative example 2.
Reference numerals are a reflective support assembly 1, a first substrate 11, a first electrode 12, an optically embossed relief microstructure layer 21, a specular reflection layer 22, a hydrophobic insulation layer 3, a first liquid 4, a second liquid 5, an electrowetting display layer 6, a pixel wall 7, a pixel cell 71, a transmissive support assembly 8, a second electrode 81, a second substrate 82, a power regulation module 9, and a first light transmissive conductive substrate 10.
Detailed Description
The conception and the technical effects produced by the present invention will be clearly and completely described in conjunction with the embodiments below to fully understand the objects, features and effects of the present invention. It is apparent that the described embodiments are only some embodiments of the present invention, but not all embodiments, and that other embodiments obtained by those skilled in the art without inventive effort are within the scope of the present invention based on the embodiments of the present invention.
Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative only and are not to be construed as limiting the invention.
In the description of the present invention, it should be understood that references to orientation descriptions such as upper, lower, front, rear, left, right, etc. are based on the orientation or positional relationship shown in the drawings, are merely for convenience of description of the present invention and to simplify the description, and do not indicate or imply that the apparatus or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the present invention.
In the description of the present invention, the meaning of a number is one or more, the meaning of a number is two or more, and greater than, less than, exceeding, etc. are understood to exclude the present number, and the meaning of a number is understood to include the present number. The description of the first and second is for the purpose of distinguishing between technical features only and should not be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated or implicitly indicating the precedence of the technical features indicated.
In the description of the present invention, unless explicitly defined otherwise, terms such as arrangement, installation, connection, etc. should be construed broadly and the specific meaning of the terms in the present invention can be reasonably determined by a person skilled in the art in combination with the specific contents of the technical scheme.
In the description of the present invention, the descriptions of the terms "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The experimental methods in which specific conditions are not specified in the following examples are generally conducted under the conditions conventional in the art or according to the conditions recommended by the manufacturer, and the raw materials, reagents and the like used, unless otherwise specified, are commercially available from conventional markets and the like.
Example 1
The embodiment discloses an electrowetting display device, the schematic structural diagram is shown in fig. 1-2, including from bottom to top in order the reflective support component 1 that stacks the setting, electrowetting display layer 6 and transmission type support component 8, reflective support component 1 includes from the small first base plate 11 that stacks the setting in proper order up, first electrode 12, light embossing relief (embossing) micro-structure layer 2 and hydrophobic insulating layer 3, transmission type support component 8 includes second base plate 82 and the second electrode 81 that stacks the setting in proper order along the direction towards reflective support component 1, wherein first base plate 11 and second base plate 82 are the light-transmitting plate, first electrode 12 and second electrode 81 are ITO, hydrophobic insulating layer 3 is the super-hydrophobic insulating layer preferably used. The embossed relief microstructure layer 2 comprises a microstructure layer comprising irregular relief.
The electrowetting display layer 6 includes a sealing cavity and a pixel wall 7 disposed on the surface of the hydrophobic insulating layer, the pixel wall 7 encloses to form a pixel cell 71 (simply referred to as a pixel cell, indicated by a dotted line in the figure), the pixel cells 71 are arranged in an array, and each pixel cell 71 forms a pixel unit. The reflective support assembly 1 and the transmissive support assembly 8 are encapsulated by an encapsulation material to form a sealed cavity, the sealed cavity is filled with a first fluid 4 (nonpolar liquid, ink) and a second fluid 5 (polar liquid, water) which are mutually insoluble, and the first fluid 4 is filled in each pixel cell 71. Wherein, alternatively, the first substrate 11 and the second substrate 82 are glass substrates with thickness of 0.7mm, the first electrode 12 and the second electrode 81 are ITO layers with thickness of about 25nm, the hydrophobic insulating layer 3 is about 600nm, the thickness of the photo-embossing micro-structure layer 1 is about 1.5 μm, the thickness of the pixel wall 7 is about 5 μm, and the material is epoxy resin photoresist. The first substrate 11 and the first electrode 12 may constitute a first light-transmitting conductive substrate 10, and the second substrate 82 and the second electrode 81 may constitute a second light-transmitting conductive substrate. Optionally, the distance between the reflective support assembly 1 and the transmissive support assembly 8 is selected from 54.45-183.85 μm.
The electrowetting display device further comprises a power supply control module 9, the power supply control module 9 being arranged to control the voltage between the reflective support assembly 1 and the transmissive support assembly 8. After the electrowetting display device is electrified, the electrode layer and the polar liquid enable the nonpolar liquid to displace and deform, so that the display switch of the device is controlled, and the reflection of ambient light is observed by human eyes. Specifically, according to the electrowetting principle, when the voltage applied by the power supply regulation module 9 is greater than the threshold voltage of the movement of the first fluid 4, the first fluid 4 in the pixel unit is deformed, the first fluid 4 is changed from a first tiling state to a shrinkage state, at this time, the incident light of the external environment can be transmitted to the embossing relief microstructure layer 2 through the light transmission area of the electrowetting display layer 6, the special structure of the embossing relief microstructure layer 2 can reflect the ambient light out of the reflective light source with a larger reflective angle, and if the applied voltage is smaller than the threshold voltage, the first fluid 4 is in the tiling state in the pixel unit, at this time, the incident light of the environment is completely absorbed by the first fluid 4 and cannot be reflected out of the reflective light source through the electrowetting display layer 6.
The preparation method of the electrowetting display device in the embodiment specifically comprises the following steps:
(I) The preparation of the photo-embossing relief template by spin coating comprises depositing a photo-polymer mixed solution into the photo-embossing relief template by spin coating (the spin coating thickness is 1.5 μm and the thickness is 0.5-2 μm), specifically, taking ITO glass (comprising a glass substrate and an ITO layer arranged on the surface of the glass substrate), spin coating the photo-polymer solution on the surface of the ITO layer, setting the initial speed of a spin coater to be 3000 revolutions per minute, and carrying out accelerated spin coating at the acceleration of 1500 revolutions per minute for 60 seconds.
And (II) drying the solvent, namely forming a photopolymer coating on the surface of the ITO glass after spin coating, setting the drying temperature to be 80 ℃ and the drying time to be 10-20 minutes so as to remove the residual solvent and form a photo-embossing relief template (called photo-embossing template for short), wherein the template contains photopolymer.
(III) exposure to a photolithographic mask the sample was exposed through a photolithographic mask having a size of 1X 1cm and comprising a hexagonal close-packing of 30 μm transparent holes with a spacing of 30 μm between the holes at a light intensity of 10-20mW/cm2.
And (IV) heating the template, namely forming a relief image after exposure of the photoetching mask, and baking the obtained sample in an air oven at 110 ℃ for 1-10min. Finally, the sample is put under the light intensity of 10-20mW/cm2 for full exposure to solidify the obtained microstructure diffuse reflection layer.
And (V) packaging the device, namely continuously spin-coating the hydrophobic insulating layer 3 on the microstructure diffuse reflection layer, spin-coating the photoresist and developing to obtain the pixel wall 7, respectively filling the mutually-insoluble ink and the mutually-insoluble ink into the electrowetting display layer 6, assembling the electrowetting display layer and the transmission type support component 8, and packaging by adopting a packaging material to obtain the electrowetting display device.
Comparative example 1
This comparative example discloses an electrowetting display device which differs from example 1 in that the optically embossed relief microstructure layer 2 in example 1 is replaced by a conventional reflective layer of equal thickness. Wherein, the conventional reflecting layer is a metal reflecting film (an aluminum layer).
Comparative example 2
This comparative example discloses an electrowetting display device which differs from example 1 in that the photo-embossed relief microstructure layer 2 is located on the side of the first substrate 11 facing away from the first electrode 12.
Comparative example 3
This comparative example discloses an electrowetting display device which differs from example 1 in that the optically embossed relief microstructure layer 2 is absent in this comparative example.
Test examples
The present test example compares and tests the performance of the electrowetting display devices in the examples and comparative examples, and specifically includes:
(1) The conventional reflective layer used in the electrowetting display device of comparative example 1, the light reflection schematic diagram of which is shown in fig. 3, and the electrowetting display device of example 1, the light reflection schematic diagram of which is shown in fig. 4 to 5, are shown in the photo-embossed relief microstructure layer 2, and the reflection effect of the electrowetting display devices of comparative example 3 and example 1 on light are shown in fig. 6 to 7, respectively. It can be seen that, the light embossing relief microstructure layer 2 generates reflected light with a larger reflection angle to ambient light, so that the visible angle of the diffuse reflection layer device is widened, and the problems of small visible angle and poor display effect of the conventional electrowetting display device can be solved.
(2) As shown in fig. 8, the light reflection diagram of the electrowetting display device of comparative example 2 is shown, and compared with the light embossing relief microstructure layer 2 of comparative example 2 located on the side of the first substrate 11 away from the first electrode 12, the light embossing relief microstructure layer 2 of example 1 is located between the first electrode 12 and the hydrophobic insulating layer 3, so that the incident optical path is reduced, the light loss is reduced, and more emergent light is obtained, thereby achieving a better reflection effect.
(3) The diffuse reflectance of the electrowetting display device of example 1 was increased by 20% to 30% compared to the electrowetting display device of comparative example 1, 10% to 20% compared to the electrowetting display device of comparative example 2, and 35% to 50% compared to the electrowetting display device of comparative example 3.
In summary, by adding the light embossing relief microstructure layer 2, the electrowetting display device utilizes diffuse reflection of the light embossing relief microstructure layer 2 on incident light, so that more ambient light can pass through the light embossing relief microstructure layer 2 to human eyes, and the particle diffuse reflection generates reflection light with larger reflection angle on the ambient light, so that the visible angle of the electrowetting display device is widened, the display effect of the device is improved, and the problem that the conventional reflection type electrowetting display device has poor display effect due to small visible angle is solved. Therefore, the electrowetting display device can be also suitable for outdoor high-brightness environments, is green and environment-friendly and protects eyes, and has good application prospect.
In this context, the meaning of "about" with respect to a numerical value is an error of ±5%.
The embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of one of ordinary skill in the art without departing from the spirit of the present invention. Furthermore, embodiments of the invention and features of the embodiments may be combined with each other without conflict.