Patent Grant
8018429
This application claims priority to Korean Patent Application No. 10-2007-0074651, filed on Jul. 25, 2007, and all the benefits accruing therefrom under 35 U.S.C. §119, the contents of which in its entirety are herein incorporated by reference.
1. Field of the Invention
The present invention relates to a surface plasmon display device and a method thereof, and more particularly, to a surface plasmon display device having a simple structure and capable of representing colors, and a method of representing colors in the display device.
2. Description of the Related Art
Reflective displays can realize flexible displays with low costs, and have low power consumption. Therefore, a reflective display is used as a display device in low power mobile displays. The reflective displays can be electrophoretic displays (“EPDs”), liquid crystal displays (“LCDs”), electrowetting displays (“EWDs”), and electrochromic displays (“ECDs”). Among the above, the most developed reflective display is the EPD, which uses the movements of particles. However, the most important technical issue of the reflective display is to represent colors.
In order to realize the representation of colors, micro capsules including R (red), G (green), and B (blue) particles are prepared, and then, the micro-capsules respectively including the R, G, and B particles are arranged on a substrate, such as by a method suggested by E-Ink Corp.
Alternatively, a method of coating a color filter on a surface of the microcapsule has been suggested, however, since the color filter absorbs about ⅔ of incident light, the brightness of the reflective display quality is degraded. Otherwise, in order to present the colors, the R, G, and B particles are selectively input into micro-cups or cells that are designated as R, G, and B colors, such as by a method suggested by Sipix Corp. or Bridgestone Corp.
It has been determined herein according to the present invention that the process of inputting color particles respectively into micro-cups or cells as is done in conventional display devices is complex and causes an increase in manufacturing costs.
The present invention provides a surface plasmon display device that can realize colors without using barriers or cells.
The present invention also provides a surface plasmon display device having a simple structure, which can be fabricated easily with low fabrication costs.
The present invention also provides a method of providing a display that can realize colors without using barriers or cells.
According to exemplary embodiments of the present invention, a surface plasmon display device includes a plurality of pixel regions, metal particles formed in the pixel regions, a dielectric layer which generates a surface plasmon resonance by contacting with the metal electrophoretic particles, and an electrode structure which induces electrophoresis of the metal particles in the pixel regions, wherein a wavelength of the surface plasmon resonance in each of the pixel regions is determined by at least one of a thickness of the dielectric layer and a dielectric constant of the dielectric layer, and the metal particles in the pixel regions are formed of a same material having a constant size.
Each of the pixel regions may further include white reflective electrophoretic particles. The pixel regions may be spatially connected to each other.
According to other exemplary embodiments of the present invention, a surface plasmon display device includes a first substrate and a second substrate which form a space in which electrophoretic particles including metal particles are included, an electrode structure including a first electrode and a second electrode respectively formed on the first substrate and the second substrate, a plurality of pixel regions that can be electrically addressed by the electrode structure, and a dielectric layer formed on an inner surface of the first substrate to correspond to each of the pixel regions to generate a surface plasmon resonance with the metal particles, wherein the dielectric layer in each of the pixel regions has physical properties which cause the surface plasmon resonance corresponding to a wavelength designated to a corresponding pixel region.
The electrophoretic particles may further include charged particles reflecting or absorbing the visible rays, and may further include electrophoretic particles reflecting white rays or black electrophoretic particles.
The electrode structure may be an X-Y matrix type arrangement structure or an active matrix type arrangement structure including active devices such as transistors.
According to still other exemplary embodiments of the present invention, a method of representing colors in a display device is provided. The display device includes first and second substrates which form a space therebetween, a plurality of electrophoretic particles formed in the space, an electrode structure including a first electrode and a second electrode respectively formed on the first substrate and the second substrate, and a plurality of pixel regions electrically addressed by the electrode structure. The method includes including a plurality of metal particles amongst the electrophoretic particles, and forming a dielectric layer within each pixel region on the first substrate to generate a surface plasmon resonance with the metal particles, wherein at least one of a thickness or a dielectric constant of the dielectric layer within each pixel region is selectively chosen to cause the surface plasmon resonance to correspond to a particular wavelength designated to each corresponding pixel region.
Including a plurality of metal particles may include including a plurality of metal particles having a constant size and formed of a same material.
Forming a dielectric layer within at least one of the pixel regions may include forming at least two dielectric layers having a dielectric constant different from that of each other.
The above and other features and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which:
The invention will now be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like reference numerals refer to like elements throughout.
It will be understood that when an element is referred to as being “on” another element, it can be directly on the other element or intervening elements may be present therebetween. In contrast, when an element is referred to as being “directly on” another element, there are no intervening elements present. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.
It will be understood that, although the terms first, second, third etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present invention.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” or “includes” and/or “including” when used in this specification, specify the presence of stated features, regions, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, and/or groups thereof.
Spatially relative terms, such as “beneath”, “below”, “lower”, “above”, “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the exemplary term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
Embodiments of the present invention are described herein with reference to cross section illustrations that are schematic illustrations of idealized embodiments of the present invention. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, embodiments of the present invention should not be construed as limited to the particular shapes of regions illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. For example, a region illustrated or described as flat may, typically, have rough and/or nonlinear features. Moreover, sharp angles that are illustrated may be rounded. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the precise shape of a region and are not intended to limit the scope of the present invention.
Hereinafter, embodiments of a surface plasmon display device according to the present invention will be described with reference to the accompanying drawings.
Briefly, the present invention is based on an electrophoresis of particles and a surface plasmon resonance between a metal, such as metal particles, and a dielectric layer. According to exemplary embodiments of the present invention, a movement of particles corresponds to a switching process of a particular pixel, and the surface plasmon resonance between the moved particles and the dielectric layer corresponds to a process of representing a light of a designated color.
A light emission wavelength of the particular pixel is controlled by conditions of a surface plasmon, that is, a dielectric constant of the dielectric layer and sizes of metal electrophoretic particles (hereinafter, referred to as metal particles). In the exemplary embodiments of the present invention, metal particles having constant sizes are used in all of the pixels, and thus, the light emission wavelength of each of the pixels is determined by selecting a thickness of the dielectric layer. According to an exemplary embodiment of the present invention, a dielectric layer is formed on the entire pixels, or substantially the entire pixels, of an identical material, and according to another exemplary embodiment of the present invention, some of the pixel regions can have the dielectric layer formed of a different material from that of the dielectric layer in other pixel regions. In exemplary embodiments of the present invention, the sizes of the metal particles are formed to be identical so as to exclude the necessity for barrier ribs that define the pixels in a space where the metal particles exist. Instead of various sized metal particles, physical conditions or material characteristics of the dielectric layer can be differentiated in order to generate a surface plasmon emission within a designated wavelength in each of the pixels.
The surface plasmon absorbs the light selectively, and reflects the light of a certain wavelength, see Physical Review B, Vol 35, No. 8, Page 3753, herein incorporated by reference.
The wavelength of the light that is absorbed by the surface plasmon is determined by a shape of the metal particle, a size of the metal particle, a shape of the dielectric layer, a dielectric constant, and a contacting status between the metal particle and the dielectric layer. This is based on a fact that a light of a certain wavelength is absorbed in a visible ray region when the metal particles contact the dielectric layer.
The metal particle can be formed of a material that can induce the surface plasmon phenomenon when the metal particle contacts the dielectric layer, for example, the material of the metal particle may include silver Ag or gold Au. The size of the metal particle ranges from about 1 to about 1000 nm, and the size of the metal particle that is actually used must be smaller than a size of a unit pixel in the display device. Since the metal particle moves by electrophoresis, positive charges and negative charges are formed on a surface of the metal particle.
In exemplary embodiments of the present invention, the dielectric layer must be transparent since the surface plasmon display device of the present invention is a reflective display device. TiO2, SiO2, and lead fluoride are transparent in the visible ray area, and thus, the dielectric layer of the present invention may include such materials. The thickness of the dielectric layer can range from about 1 to about 1000 nm. According to exemplary embodiments of the present invention, since the wavelength absorbed by the surface plasmon is changed according to the thickness of the dielectric layer, the wavelength of the light to be absorbed by the surface plasmon may be selected by adjusting the thickness of the dielectric layer. Therefore, the dielectric constant of the dielectric layer may be changed or the thickness of the dielectric layer may be adjusted in order to control the wavelength of the light that is absorbed by the surface plasmon, and, if necessary, the change of the dielectric constant and the adjustment of the thickness may be performed simultaneously. The dielectric layer may be a single layer or a multi-layered structure.
The size of a unit pixel must be appropriate to realize the display, and, in exemplary embodiments of the present invention, a shape of an electrode structure determines the size of the unit pixel. The size of the unit pixel may range from about 1 to about 1000 μm in width and length.
According to the present invention, the metal particles having a constant size are used on the entire area, or at least substantially an entire area, of the display, and thus, there is no need to divide the space where the metal particles exist into pixel regions. In addition, a spacer, such as a spacer used in general liquid crystal displays (“LCD”) devices, can be used in order to maintain a distance between a front substrate and a rear substrate, where the particles are formed between the front and rear substrates. A height of the spacer can range from about 1 to about 1000 μm.
The substrate used in the display device according to the present invention is not limited to a specific material, for example, the substrate may be a glass substrate or a plastic substrate. The plastic substrate, for example, may include polyethylene terephthalate (“PET”), polyethylene naphthalate (“PEN”), or polyethersulfone (“PES”). In addition, a thickness of the substrate may range from about 10 to about 1000 μm.
The electrode arrangement structure of a passive matrix type includes a first electrode arrangement X having a plurality of electrodes (X1, X2, X3, ˜, Xm) in a first direction and a second electrode arrangement Y having a plurality of electrodes (Y1, Y2, Y3, ˜, Yn) in a second direction that crosses the first direction at a right angle. In an exemplary embodiment of the electrode arrangement structure of the passive matrix type, the unit pixels may be defined relative to portions where the electrodes of the first electrode arrangement X and the electrodes of the second electrode arrangement Y cross each other.
The electrode arrangement structure of the active matrix type, as shown in
While exemplary passive and active matrix types of electrode arrangements have been described with respect to
Referring to
As shown in
On the other hand, when the polarities of the voltages that are applied to the first and second electrodes 11 and 12 are changed, the metal particles 14 move toward the second electrode 12 and the reflective particles 15 move toward the first electrode 11. Therefore, the external light may be reflected by the reflective particles 15 and output through the first electrode 11. If the reflective particles 15 are white, the reflected light becomes the white light. Alternatively, if the reflective particles 15 are black, the external light is not reflected by the reflective particles 15, and is instead absorbed, and thus, the display becomes black when the display is seen from the outside.
The emission of two colors using the two kinds of particles, metal particles and reflective particles, is described as above. The present invention uses such principle to provide the exemplary surface plasmon display device that does not include barrier ribs, which are generally used in conventional color display structures and are considered to be essential in the display field.
Referring to
According to exemplary embodiments of the present invention, the emission of light in the certain wavelength band from the regions defined as R, G, and B pixels is controlled by the thickness of the dielectric layer 16r, 16g, 16b, and/or the dielectric constant of the dielectric layer 16r, 16g, 16b, respectively. Physical Review B, Vol 35, No. 8, Page 3753, herein incorporated by reference, can be referred to in regard to the controlling of wavelength using the thickness of the dielectric layer and the dielectric constant.
According to exemplary embodiments of the present invention, in order to control the emission of the light in the certain wavelength band from the R, G, and B pixels, for each dielectric layer 16r, 16g, and 16b, two or more dielectric layers that are different from each other can be deposited in a direction perpendicular to the substrate 10a. That is, for each pixel, two or more dielectric layers that are different from each other can be deposited and layered on the substrate 10a.
According to exemplary embodiments of the present invention, in order to control the emission of the light in the certain wavelength band from the R, G, and B pixels, different types of dielectric materials used in the unit pixels R, G, and B can be mixed in a direction in parallel with the substrate 10a. That is, dielectric layers that are different from each other may be formed on the substrate 10a within adjacent pixels and within a same pixel.
Therefore, the present invention does not require barrier ribs for defining the R, G, and B unit pixel regions. Thus, complex processes of forming the barrier ribs and of injecting certain metal particles into unit pixel regions defined by such barrier ribs are not required.
Exemplary materials forming the dielectric layers 16r, 16g, and 16b in the pixels R, G, and B and exemplary thicknesses of the dielectric layers 16r, 16g, and 16b, and the sub-layers within the dielectric layers 16r, 16g, and 16b, and types and sizes of the metal particles 14 according to exemplary embodiments of the present invention may be as follows.
It should be understood that while particular examples of materials and dimensions are provided for exemplary purposes, such examples are not presented to limit the scope of the invention. That is, alternate materials and dimensions are also within the scope of these embodiments.
As shown in
While a particular exemplary arrangement has been described, alternate arrangements are within the scope of these embodiments. For example, the dielectric layers 16r, 16g, or 16b shown in
According to exemplary embodiments of the present invention, barrier ribs for defining pixels are not required. However, a spacer for maintaining a distance between the first substrate and the second substrate is required. Various types of spacers such as a bar type spacer and a ball type spacer, such as that used in a general LCD, may be used. The usage of the spacer and the type of the spacer do not limit the technical scope of the present invention.
According to exemplary embodiments of the present invention, the barrier ribs for defining the pixels are not required, and in particular, identical metal particles having a constant size can be used throughout all of the pixels. Therefore, fabrication of the surface plasmon display device is simplified and may be accomplished with low fabrication costs.
In addition, according to exemplary embodiments of the present invention, the light of a desired color can be selectively emitted using the movements of particles and the surface plasmon resonance of the moved particles. Therefore, the present invention can be applied to a color display device, in particular, a color display device using the above-described principle.
While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by one of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2007-0074651 | Jul 2007 | KR | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 3682528 | Apfel et al. | Aug 1972 | A |
| 6017584 | Albert et al. | Jan 2000 | A |
| 7295364 | Yamamoto | Nov 2007 | B2 |
| 20070279378 | Takeuchi et al. | Dec 2007 | A1 |
| Number | Date | Country | |
|---|---|---|---|
| 20090027329 A1 | Jan 2009 | US |
