Patent Application
20140104674
1. Field of the Invention
The invention relates to a display medium, a manufacturing method thereof, and a display. More particularly the invention relates to a display medium adapted for an electrophoretic display, a manufacturing method thereof, and an electrophoretic display.
2. Description of Related Art
With the development of information technology products, manufacturers aim at equipping future displays with features including lightness, thinness, and flexibility. Among the displays, an electrophoretic display (EPD) has attracted great attention.
An EPD mainly uses an external electrical field to control the charged particles within (i.e. electrophoretic particles) in order to display colors of different gray levels. For example, a display medium is constructed through white and black electrophoretic particles, along with a transparent continuous phase solution. Through the electrical field controlling the distribution of the white and the black electrophoretic particles in the continuous phase solution, different gray levels can be displayed. In detail, when the white electrophoretic particles are next to a side of the user, the light of external light source is reflected by the white electrophoretic particles, and the user can see the white color of the electrophoretic particles. When the distribution of the electrophoretic particles are changed, such as black electrophoretic particles being next to a side of the user, the light of external light source will be absorbed by the black electrophoretic particles, and the user will see the black color of the electrophoretic particles.
Because of the bistability characteristic of EPDs, when no additional electrical field is used, the electrophoretic particles can remain at the same depth. In other words, when the EPD maintains the same gray level, or the display image does not change, no power is consumed. Thus, EPDs have the advantage of saving power. In current manufacturing methods of display mediums, for example, uncharged particles and a single type of monomer can be combined to form charged electrophoretic particles. Next the electrophoretic particles are distributed in a continuous phase solution to form a display medium. However, under this configuration, the display medium will have lower reliability, affecting the bistability of the EPD. This also affects the display quality of the EPD.
The invention provides a display medium, having favorable reliability.
The invention further provides a method of manufacturing a display medium, for producing the display medium with favorable reliability.
The invention provides an electrophoretic display (EPD), having good display quality.
The invention provides a display medium adapted for an EPD. The display medium includes at least one particle and a random copolymer bonded with the particle. The random copolymer includes a structural unit originated from a first monomer and a second monomer. The first monomer is selected from at least one group of consisting of 2-ethylhexyl acrylate (EHA), 2-ethylhexyl methacrylate (EHMA), 2-methylhexyl acrylate (MHA), 2-methylhexyl methacrylate (MHMA), lauryl methacrylate, lauryl acrylate, tetradecyl methacrylate, tetradecyl acrylate, hexadecyl methacrylate, hexadecyl acrylate, octadecyl mechacrylate, and octadecyl acrylate. The second monomer is selected from at least one group consisting of 2,2,2 trifluoroethyl acrylate, 2,2,3,3 tetrafluoropropyl methacrylate, 1,1,1,3,3,3-hexafluoroisopropyl acrylate, 1,1,1,3,3,3-hexafluoroisopropyl methacrylate, 2,2,3,3,3-pentafluoropropyl acrylate, 2,2,3,3-tetrafluoropropyl acrylate, 2,2,3,4,4,4-hexafluorobutyl methacrylate, 2,2,3,3,4,4,4-heptafluorobutyl methacrylate, 2,2,3,3,4,4,5,5-octafluoropentyl acrylate, 2,2,3,3,4,4,5,5-octafluoropentyl methacrylate, 2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoroheptyl acrylate, and 3,3,4,4,5,6,6,6-octafluoro-5-(trifluoromethyl)hexyl methacrylate.
In an embodiment of the invention, the amount of the second monomer constituted in the random copolymer is 1 molar percent to 50 molar percent.
In an embodiment of the invention, the amount of the second monomer constituted in the random copolymer is 5 molar percent to 15 molar percent.
In an embodiment of the invention, the particles include inorganic particles or organic particles.
In an embodiment of the invention, the particle includes a silane coupling agent, and the particle is bonded to the random copolymer through the silane coupling agent group.
The invention provides a method of manufacturing a display medium adapted for an EPD, wherein the method includes the following steps. At least one particle, a first monomer, and a second monomer are provided. The first monomer is selected from at least one group consisting of 2-ethylhexyl acrylate (EHA), 2-ethylhexyl methacrylate (EHMA), 2-methylhexyl acrylate (MHA), 2-methylhexyl methacrylate (MHMA), lauryl methacrylate, lauryl acrylate, tetradecyl methacrylate, tetradecyl acrylate, hexadecyl methacrylate, hexadecyl acrylate, octadecyl mechacrylate, and octadecyl acrylate. The second monomer is selected from at least one group consisting of 2,2,2 trifluoroethyl acrylate, 2,2,3,3 tetrafluoropropyl methacrylate, 1,1,1,3,3,3-hexafluoroisopropyl acrylate, 1,1,1,3,3,3-hexafluoroisopropyl methacrylate, 2,2,3,3,3-pentafluoropropyl acrylate, 2,2,3,3-tetrafluoropropyl acrylate, 2,2,3,4,4,4-hexafluorobutyl methacrylate, 2,2,3,3,4,4,4-heptafluorobutyl methacrylate, 2,2,3,3,4,4,5,5-octafluoropentyl acrylate, 2,2,3,3,4,4,5,5-octafluoropentyl methacrylate, 2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoroheptyl acrylate, and 3,3,4,4,5,6,6,6-octafluoro-5-(trifluoromethyl)hexyl methacrylate. A polymerization reaction is performed by the particle, the first monomer, and the second monomer, so that the first monomer and the second monomer form a random copolymer through the polymerization reaction. The random copolymer is bonded with the particle.
In an embodiment of the invention, in the method of manufacturing the display medium, during the polymerization reaction, the amount of the second monomer relative to the combination of the first monomer and the second monomer is 1 molar percent to 50 molar percent.
In an embodiment of the invention, in the method of manufacturing the display medium, during the polymerization reaction, the amount of the second monomer relative to the combination of the first monomer and the second monomer is 5 molar percent to 15 molar percent.
In an embodiment of the invention, the particle includes a silane coupling agent, and the particle is bonded to the random copolymer formed by the first monomer and the second monomer through the silane coupling agent.
In an embodiment of the invention, the polymerization reaction is performed by the particle, the first monomer, and the second monomer in a nitrogen ambiance.
In an embodiment of the invention, in the method manufacturing the display medium, the method further includes providing a heating temperature during the polymerization reaction by the particle, the first monomer, and the second monomer, wherein the heating temperature is between 50 centigrade to 80 centigrade.
In an embodiment of the invention, the method of manufacturing the display medium further includes distributing the particles and the random copolymer bonded with the particles to a continuous phase solution.
The invention provides an electrophoretic display, including a first electrode layer, a plurality of microcups located on the first electrode layer, a display medium filled in the microcups, and a second electrode layer. The microcups are located between the first electrode layer and the second electrode layer. The display medium includes at least one particle, a random copolymer bonded with the particle, and a continuous phase solution. The random copolymer has a structural unit originated from a first monomer and a second monomer. The first monomer is selected from at least one a group consisting of 2-ethylhexyl acrylate (EHA), 2-ethylhexyl methacrylate (EHMA), 2-methylhexyl acrylate (MHA), 2-methylhexyl methacrylate (MHMA), lauryl methacrylate, lauryl acrylate, tetradecyl methacrylate, tetradecyl acrylate, hexadecyl methacrylate, hexadecyl acrylate, octadecyl mechacrylate, and octadecyl acrylate. The second monomer is selected from at least one group consisting of 2,2,2 trifluoroethyl acrylate, 2,2,3,3 tetrafluoropropyl methacrylate, 1,1,1,3,3,3-hexafluoroisopropyl acrylate, 1,1,1,3,3,3-hexafluoroisopropyl methacrylate, 2,2,3,3,3-pentafluoropropyl acrylate, 2,2,3,3-tetrafluoropropyl acrylate, 2,2,3,4,4,4-hexafluorobutyl methacrylate, 2,2,3,3,4,4,4-heptafluorobutyl methacrylate, 2,2,3,3,4,4,5,5-octafluoropentyl acrylate, 2,2,3,3,4,4,5,5-octafluoropentyl methacrylate, 2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoroheptyl acrylate, and 3,3,4,4,5,6,6,6-octafluoro-5-(trifluoromethyl)hexyl methacrylate. The random copolymer bonded with the particle is distributed in the continuous phase solution.
In an embodiment of the invention, the particles of the display medium include black particles and white particles.
In an embodiment of the invention, the second electrode layer includes a plurality of sub-electrodes separated from each other, and the sub-electrodes are respectively located on each microcup.
In an embodiment of the invention, the second electrode layer includes a plurality of sub-electrodes separated from each other, and the sub-electrodes are respectively located near or underneath the partition walls of adjacent microcups to allow the charged particles to move to the sides of the microcups during in-plane switching, so as to expose the bottom layer of the microcups.
The invention provides an electrophoretic display, including a first electrode layer, a plurality of microcups located on the first electrode layer, a display medium filled in the microcups, a second electrode layer, and at least one color base layer. The microcups are located between the first electrode layer and the second electrode layer. The color base layer is located between the second electrode layer and the microcups. The display medium includes at least one particle, a random copolymer bonded with the particle, and a continuous phase solution. The random copolymer has a structural unit originated from a first monomer and a second monomer. The first monomer is selected from at least one group consisting of 2-ethylhexyl acrylate (EHA), 2-ethylhexyl methacrylate (EHMA), 2-methylhexyl acrylate (MHA), 2-methylhexyl methacrylate (MHMA), lauryl methacrylate, lauryl acrylate, tetradecyl methacrylate, tetradecyl acrylate, hexadecyl methacrylate, hexadecyl acrylate, octadecyl mechacrylate, and octadecyl acrylate. The second monomer is selected from at least one or a combination of a group of specific compounds consisting of 2,2,2 trifluoroethyl acrylate, 2,2,3,3 tetrafluoropropyl methacrylate, 1,1,1,3,3,3-hexafluoroisopropyl acrylate, 1,1,1,3,3,3-hexafluoroisopropyl methacrylate, 2,2,3,3,3-pentafluoropropyl acrylate, 2,2,3,3-tetrafluoropropyl acrylate, 2,2,3,4,4,4-hexafluorobutyl methacrylate, 2,2,3,3,4,4,4-heptafluorobutyl methacrylate, 2,2,3,3,4,4,5,5-octafluoropentyl acrylate, 2,2,3,3,4,4,5,5-octafluoropentyl methacrylate, 2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoroheptyl acrylate, and 3,3,4,4,5,6,6,6-octafluoro-5-((trifluoromethyl))hexyl methacrylate. The random copolymer bonded with the particle is dispersed in the continuous phase solution.
In an embodiment of the invention, the second electrode layer includes a plurality of sub-electrodes separated from each other, and each of the sub-electrodes are respectively located near or underneath the partition walls of adjacent microcups to allow the charged particles to move to the sides of the microcups during in-plane switching, so as to expose the bottom layer of the microcups.
Based on the above, in the invention, a random copolymer formed by a first monomer selected from a specific compound and a second monomer selected from a specific compound is bonded with particles. This way, the zeta potential of the particles in a continuous phase solution is improved, so that the particles can quickly move according to an external electrical field. Moreover, favorable reliability is achieved, and thus the EPD can have good display quality.
In order to make the aforementioned and other features and advantages of the invention more comprehensible, embodiments accompanying figures are described in detail below.
The accompanying drawings constituting a part of this specification are incorporated herein to provide a further understanding of the invention. Here, the drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
The second monomer is selected from at least one or a combination of a group of specific compounds consisting of 2,2,2 trifluoroethyl acrylate, 2,2,3,3 tetrafluoropropyl methacrylate, 1,1,1,3,3,3-hexafluoroisopropyl acrylate, 1,1,1,3,3,3-hexafluoroisopropyl methacrylate, 2,2,3,3,3-pentafluoropropyl acrylate, 2,2,3,3-tetrafluoropropyl acrylate, 2,2,3,4,4,4-hexafluorobutyl methacrylate, 2,2,3,3,4,4,4-heptafluorobutyl methacrylate, 2,2,3,3,4,4,5,5-octafluoropentyl acrylate, 2,2,3,3,4,4,5,5-octafluoropentyl methacrylate, 2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoroheptyl acrylate, and 3,3,4,4,5,6,6,6-octafluoro-5-(trifluoromethyl)hexyl methacrylate.
The particle P can be an inorganic particle or an organic particle. In the embodiment, the particle P is, for example, an inorganic particle. The material of the inorganic particle can be selected from at least one of the following: titanium dioxide (TiO2), zirconium oxide (ZrO2), silicon dioxide (SiO2), and aluminium oxides (Al2O3). In the embodiment, the particle P can form a particle P′ with a silane coupling agent S through silanzation. The silane coupling agent S can be methacryloxypropyltrimethoxysilane (MSMA).
More specifically, the silane coupling agent S can shown as the following compound:
The silane coupling agent S has at least two functional groups on one single molecule for linking particle and polymer, in which one functional group bonds to particle surface, the other functional group bonds to polymer. For example, on this silane coupling agent S, siloxyl group bond to particle surface, and the acrylate functionality will link to a polymer.
Next, a polymerization reaction is performed by the particle P′, the first monomer MA, and the second monomer MB. In the embodiment, the particle P′, the first monomer MA, and the second monomer MB are disposed in a container 110 to perform the polymerization reaction. This way, the first monomer MA and the second monomer MB form a random copolymer RC, and is then bonded with the particle P′. One skilled in the art can select a suitable ambiance and conditions for the polymerization reaction according to the type of product or materials. The invention is not limited thereto. In the container 110 of the embodiment, the amount of the second monomer MB relative to the total amount of the first monomer MA and the second monomer MB is from 1 molar percent to 50 molar percent, or even better from 5 molar percent to 15 molar percent.
In detail, a copolymerization reaction of the particle P′, the first monomer MA, and the second monomer MB is, for example, performed in a nitrogen ambiance. When performing the polymerization reaction, the method can further include a heating process, providing a heating temperature towards the particle P′, the first monomer MA, and the second monomer MB, wherein the heating temperature is between 50 centigrade to 80 centigrade.
Referring to
Next the electrophoretic particle EP is distributed in a continuous phase solution FD to preliminarily complete the fabrication of a display medium 100.
It should be noted that different amounts of the second monomer MB will affect the reliability of the electrophoretic particle EP in the continuous phase solution FD. The following
As seen in
As seen in
As the amount of the second monomer MB is increased, the bistability of the particles greatly improve (i.e. the loss of brightness in the white state and the loss of brightness in the black state decreases as the amount of the second monomer MB increases). However, the actual brightness of the white state and the black state, do not improve as the second monomer MB increases.
When the display is driven under a black state, the lower the brightness is, the higher the degree of blackness is shown by the display. On the other hand, when the display is driven under a white state, the higher the brightness is, the higher the degree of whiteness is shown by the display. As seen in
However, when the amount of the second monomer MB is increased to 25 molar percent (embodiment D), even though the bistability is very good (see
Referring to
It should be noted that the display medium of the embodiment can be adapted to an EPD, so as to display images. The following will describe
In the embodiment, the microcups 220 include a bottom portion 222 and a plurality of support portions 224. The support portions 224 are located between the bottom portion 222 and the second electrode layer 240. The support portions 224 and the bottom portions 222 form a plurality of micro cup shape structures.
The display medium 230 is manufactured through the aforementioned method of manufacture. In brief, the display medium 230 includes the particle P′ (shown in
It should be noted that the white particles 232 and the black particles 234 of
The second electrode layer 240 and the first electrode layer 210 are respectively located on the two opposite sides of the microcups 220. In the embodiment, the second electrode layer 240 is, for example, an entire surface electrode structure. However, the embodiment does not limit the structure of the second electrode. In other embodiments, the second electrode can also be a plurality of strip shaped electrodes separated from each other.
In actual implementation, the electrophoretic display 200 can further include a substrate 250 and an encapsulation layer 260. The first electrode layer 210 is disposed on the substrate 250, and the support portions 224 of the microcups 220 are further located between the bottom portion 222 and the encapsulation layer 260. In addition, the encapsulation layer 260 is sealed between the microcups 220 and the second electrode layer 240, so as to protect the display medium 230 in the microcups 220, and prevent the external environment from affecting the display medium 230. The material of the substrate 250 is glass, quartz, organic polymers, plastic, or other suitable materials. In the embodiment, the substrate 250 is a soft material, such as polyethylene terephthalate (PET). Thus, the EPD 200 can not only be manufactured into general rigid material displays (such as e-books), the EPD 200 also can also be manufactured into flexible displays, such as smart cards or price tags.
By providing a voltage difference between the first electrode layer 210 and the second electrode layer 240, the black particles 234 and the white particles 232 are driven by the electric field between the first electrode layer 210 and the second electrode layer 240. This changes the distribution condition between the black particles 234 and the white particles 232 in the microcups 220, so that the EPD 200 displays different images (gray level). In detail, when the black particles 234 and the white particles 232 are driven by the electric field, because the black particles 234 and the white particles 232 have opposite charges, they will move in different directions. The distributions of the particles in the microcups 220 closer to a side of the user U are the picture color of what the user sees. For example, when the white particles 232 of the microcups 220 are on a side closer to the user U, the ambient light will be reflected by the white particles 232, so that the user U sees a white picture. In contrast, when the black particles 234 of the microcups 220 are on a side closer to the user U, the ambient light will be absorbed by the black particles 234, so that the user U sees a black picture. Similarly, when a mixture of white particles 232 and black particles 234 of the microcups 220 are on a side closer to the user U, the user U sees a gray picture. In other words, by adjusting the distribution of the black particles 234 and the white particles 232 within each of the microcups 220, the EPD 200 can display different gray levels.
In order to more precisely control the distribution of the particles (i.e. electrophoretic particles) in each microcup, the first electrode layer and the second electrode layer can have different structures. For example, the first electrode layer and the second electrode layer can respectively include electrodes that are separated from each other (such as strip shaped electrodes), and the first electrode layer and the second electrode layer can be alternately configured. Or, the first electrode layer can be an entire surface electrode and the second electrode layer can be divided to sub-electrodes that are electrically separated from each other. The following will further describe the structure and configuration of the electrode layers through
In addition, the embodiment does not limit the amount of the sub-electrodes 342, 344 between two adjacent support portions 224. Referring to
Further, in other embodiments, the sub-electrodes 342, 344 can also be disposed in other areas of the microcups 220.
With this structure, the white particles 332 can be controlled by the electric field and gather beside the support portion 224, so as to expose the structure behind the encapsulation layer 260. In other words, when the continuous phase solution 336 is replaced as a transparent solution, and the white particles 332 are controlled by the electric field to gather beside the support portions 224, the second electrode layer 340′ behind the encapsulation layer 260 is seen by the user U. With this structure, a color base layer can be further disposed between the encapsulation layer 260 and the second electrode layer 340′, so that the EPD 400 can display different colors.
To sum up, in the invention, a random copolymer formed by a first monomer selected from a specific compound and a second monomer selected from a specific compound is bonded with particles. This way, the zeta potential of the particles in a continuous phase solution is improved, so that the particles can quickly move according to an external electrical field. Moreover, favorable reliability is achieved, and the EPD can have good display quality. In addition, in the embodiments, by changing the structure and configuration of the second electrode layer, and accompanying a color base layer, the EPD can be colorized.
It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.
