Patent Publication Number: US-2012026101-A1

Title: Electric paper associated with touch panel

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of Korean Patent Application No. 10-2010-0072366, filed on Jul. 27, 2010, entitled “Electronic Paper Associated With Touch Panel”, which is hereby incorporated by reference in its entirety into this application. 
     BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention relates to an electronic paper associated with a touch panel. 
     2. Description of the Related Art 
     An electronic paper is a kind of reflective display. The electronic paper has high resolution, wide viewing angle, and excellent readability due to high contrast ratio between bright white background and black particles, and also has bistability that can maintain an image even after the supply of power is interrupted, thereby making it possible to minimize power loss. Therefore, the electronic paper has a long life span of a battery, thereby making it possible to readily reduce costs and reduce weight. In addition, similar to existing paper, the electronic paper can be most easily manufactured to have a large area as compared to any other displays. The electronic paper does not use a glass substrate, a backlight, and a polarizing plate, such that it can be manufactured having a thickness and a weight similar to those of paper. 
     Despite the advantages of the electronic paper as described above, the electronic paper according to the prior art should be operated using a separate key pad, or the like, such that it is difficult to intuitively input information. A touch panel has been in the limelight as the most effective unit for intuitively inputting information. The touch panel is mounted on the display surface of an image display device such as an electronic organizer, a flat panel display including a liquid crystal display (LCD), a plasma display panel (PDP), an electroluminescence (El) element or the like, or a cathode ray tube (CRT) and is used for a user to select the information desired while viewing the image display device. In addition, the touch panel is classified into a resistive type, a capacitive type, an electro-magnetic type, a surface acoustic wave (SAW) type, and an infrared type. Among others, the capacitive type is capable of implementing high transmittance, excellent durability, and a multi-touch, thereby being used in various fields. However, in the prior art, there is no technology capable of integrally combining an electronic paper with a capacitive touch panel, while maintaining a thin thickness, which is the advantage of the electronic paper. 
     SUMMARY OF THE INVENTION 
     The present invention has been in made an effort to provide an electronic paper associated with a touch panel capable of intuitively inputting information by combining an electronic paper with a touch panel in a mutual capacitive scheme. 
     An electronic paper associated with a touch panel according to a preferred embodiment of the present invention includes: an electronic ink provided between an upper substrate and a lower substrate; an upper electrode provided on a bottom surface of the upper substrate to drive the electronic ink and generate a signal; a lower electrode provided on a top surface of the lower substrate to drive the electronic ink; and a sensing electrode formed on a transparent substrate provided on a top side of the upper substrate to form capacitance with the upper electrode due to the signal and senses the change in the capacitance when the transparent substrate is touched by an input unit. 
     Herein, the sensing electrode is formed on the transparent substrate and is then attached to the upper substrate using an adhesive layer. 
     Further, the adhesive layer is an optical clear adhesive (OCA). 
     Further, when the transparent substrate is touched by the input unit, the lower electrode has high-impedance. 
     Further, the electronic ink is a twist ball type or an electrophoresis type. 
     Further, the upper electrode is a thin film transistor (TFT) electrode. 
     Further, the lower electrode is a common electrode. 
     Further, the sensing electrode is made of a conductive polymer. 
     Further, the conductive polymer includes poly-3, 4-ethylenedioxythiophene/polystyrenesulfonate (PEDOT/PSS), polyaniline, polyacetylene, or polyphenylenevinylene. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1 and 2  are cross-sectional views of an electronic paper associated with a touch panel according to a preferred embodiment of the present invention; 
         FIG. 3  is a plan view of the upper electrode and the sensing electrode of  FIG. 1 ; 
         FIGS. 4 and 5  are partially enlarged views enlarging portion “A” of the electronic paper associated with a touch panel of  FIG. 1 ; and 
         FIGS. 6 to 8  are cross-sectional views showing an operation process of the electronic paper associated with a touch panel of  FIG. 1 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Various objects, advantages and features of the invention will become apparent from the following description of embodiments with reference to the accompanying drawings. 
     The terms and words used in the present specification and claims should not be interpreted as being limited to typical meanings or dictionary definitions, but should be interpreted as having meanings and concepts relevant to the technical scope of the present invention based on the rule according to which an inventor can appropriately define the concept of the term to describe most appropriately the best method he or she knows for carrying out the invention. 
     The above and other objects, features and advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings. In the specification, in adding reference numerals to components throughout the drawings, it is to be noted that like reference numerals designate like components even though components are shown in different drawings. In the description, the terms “upper portion”, “lower portion”, “top surface”, “bottom other surface” and so on are used to distinguish one element from another element, and the elements are not defined by the above terms. Further, in describing the present invention, a detailed description of related known functions or configurations will be omitted so as not to obscure the subject of the present invention. 
     For your reference, the term ‘touch’ used throughout the specification is widely interpreted as being in proximity by a considerable distance as well as being in direct contact. In other words, an electronic paper associated with a touch panel according to the present invention should be interpreted as sensing while being in proximity of an input unit by a considerable distance as well as being in direct contact therewith. 
     Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. 
       FIGS. 1 and 2  are cross-sectional views of an electronic paper associated with a touch panel according to a preferred embodiment of the present invention, and  FIG. 3  is a plan view of the upper electrode and the sensing electrode of  FIG. 1 . 
     As shown in  FIGS. 1 to 3 , an electronic paper  100  associated with a touch panel according to the present embodiment may be configured to include an electronic ink  110  provided between an upper substrate  128  and a lower substrate  135 , an upper electrode  120  provided on a bottom surface of the upper substrate  128  to drive the electronic ink  110  and to generate a signal, a lower electrode  130  provided on a top surface of the lower substrate  135  to drive the electronic ink  110 , and a sensing electrode  140  formed on a transparent substrate  145  provided on a top side of the upper substrate  128  to form capacitance with the upper electrode  120  due to the signal of the upper electrode  120  and sensing change in the capacitance when the transparent substrate  145  is touched by an input unit  150 . 
     The electronic ink  110  is driven by voltage from the upper electrode  120  and the lower electrode  130  to implement images that can be sensed by a user. The electronic ink  110  is divided into a twist ball type (see  FIG. 1 ) and an electrophoresis type (see  FIG. 2 ). 
     Herein, the twist ball type coats black/white materials having different charges on hemispheres of particles  111  having a size of about 100 μm, respectively, thereby displaying black/white images through the change in the polarity of voltage applied from the upper electrode  120  and the lower electrode  130 . In the twist ball type, the particles  111  rotate according to a predetermined shaft by the applied voltage to absorb, scatter, or reflect light, thereby displaying images. 
     Meanwhile, the electrophoresis type basically disperses ink microparticles  113  and  115  that scatter light in a dielectric fluid  117  to electrically move them. The electrophoresis type uses a transparent microcapsule  119  having a diameter of 200 μm to 300 μm which includes white microparticles having positive charges, black ink microparticles  115  having negative charges, and a transparent dielectric fluid  117 . When voltage is applied to the upper electrode  120  and the lower electrode  130  by mixing the microcapsule  119  with a binder, the ink microparticles  113  having positive charges move in a negative voltage direction and the ink microparticles  115  having negative charges move in a positive voltage direction, thereby displaying images. 
     The upper electrode  120  is provided on the bottom surface of the upper substrate  128  to serve to drive the electronic ink  110 . In this configuration, the upper electrode  120 , which is a thin film transistor (TFT) electrode, is configured to include a gate line  121 , a data line  122 , a gate electrode  123 , a source electrode  124 , a drain electrode  125 , and a pixel  126  (see  FIG. 3 ). At this time, the gate line  121  is formed in a row direction and the data line  122  is formed in a column direction, thereby intersecting with each other. In addition, the source electrode  124  extended from the date line  122  is arranged opposite to the drain electrode  125  based on the gate electrode  123  extended from the gate line  121 . Herein, the gate electrode  123  functions as a switch determining whether the drain electrode  125  is conducted with the source electrode  124 . In other words, when the gate electrode  123  receives a scan signal from the gate line  121  to form an electric field, electrons flow between the drain electrode  125  and the source electrode  124 , such that a data voltage applied from the data line  122  is finally transferred to the pixel  126  through the source electrode  124  and the drain electrode  125 , thereby driving the electronic ink  110 . Meanwhile, the gate line  121  and the data line  122  may be formed of a single layer made of silver (Ag), a silver (Ag) alloy, aluminum (Al) or an aluminum (Al) alloy, having low specific resistance, wherein a layer made of a material having excellent physical and electrically contact characteristics such as chrome (Cr), titanium (Ti), tantalum (Ta), or the like, may be additionally formed on the single layer. 
     In addition, the upper electrode  120  not only drives the electronic ink  110  but also functions as a driving electrode of a touch panel. In other words, the upper electrode  120  generates a sine signal, a pulse signal, or the like to form capacitance with the sensing electrode  140 , thereby making it possible to implement a mutual capacitive touch panel. Since the upper electrode  120  functions as the driving electrode of the touch panel, there is no need to form a separate driving electrode. As a result, it is possible to simplify a structure of the electronic paper  100  associated with a touch panel and to make the electronic paper  100  associated with a touch panel thin. A detailed process to calculate touched coordinates by using the capacitance between the upper electrode  120  and the sensing electrode  140  will be described below. 
     The lower electrode  130  is provided on the top surface of the lower substrate  135  to serve to drive the electronic ink  110 , together with the upper electrode  120 . Herein, the lower electrode  130  may not only be formed of a TFT electrode but also be formed of a common electrode to which a common voltage having a predetermined magnitude is applied, similar to the upper electrode  120 . 
     The sensing electrode  140  is provided on the top side of the upper substrate  128  to sense a touch of an input unit  150  (a user&#39;s finger, a stylus pen, or the like).  FIGS. 4 and 5  are partially enlarged views enlarging portion “A” of the electronic paper associated with a touch panel of  FIG. 1 . A process of sensing a touch of an input unit  150  will be described with reference to  FIGS. 4 and 5 . First, the upper electrode  120  generates a sign signal, a pulse signal, or the like, to form capacitance between the upper electrode  120  and the sensing electrode  140  (see  FIG. 4 ). Thereafter, when a transparent substrate  145  is touched by the input unit  150 , a portion of charges is flowed into the input unit  150  to change the capacitance between the sensing electrode  140  and the upper electrode  120  and the sensing electrode  140  senses and the change in the capacitance (see  FIG. 5 ). The change in the capacitance sensed by the sensing electrode  140  is finally transferred to a controller, thereby making it possible to calculate touched coordinates of the input unit  150 . In addition, it is preferable that the lower electrode  130  is maintained at high-impedance when the transparent substrate  145  is touched by the input unit  150 , in order to prevent the electronic ink  110  from being arbitrarily driven while calculating the touched coordinates. 
     Meanwhile, the sensing electrode  140  may be made of a conductive polymer having excellent flexibility and a simple coating process as well as indium tin oxide (ITO) that is commonly used. At this time, the conductive polymer includes poly-3, 4-ethylenedioxythiophene/polystyrenesulfonate (PEDOT/PSS), polyaniline, polyacetylene, polyphenylenevinylene, or the like. In addition, the sensing electrode  140  may be formed by a dry etching process such as sputtering, evaporation, or the like, a wet etching process such as dip coating, spin coating, roll coating, spray coating, or the like, or a direct patterning process such as screen printing, gravure printing, inkjet printing or the like. 
     Further, although the sensing electrode  140  may be directly formed on the top side of the upper substrate  128 , it is preferable that the sensing electrode  140  is formed on a separate transparent substrate  145  and is then attached to the upper substrate  128  using an adhesive layer  147 , for convenience of the manufacturing process. In this case, the adhesive layer  147  may ensure transparency by using an optical clear adhesive (OCA). In addition, the transparent substrate  145 , which is touched by the input unit  150 , may be made of polyethyleneterephthalate (PET), polycarbonate (PC), polymethylmethacrylate (PMMA), polyethylenenaphthalate (PEN), polyethersulfone (PES), cyclic olefin polymer (COC), triacetylcellulose (TAC) film, polyvinyl alcohol (PVA) film, polyimide (PI) film, polystyrene (PS), biaxially oriented polystyrene (BOPS; containing K resin), glass or reinforced glass, and so on, but is not always limited thereto. Meanwhile, it is preferable that a high frequency treatment or a primer treatment is performed on the transparent substrate  145  in order to improve adhesion between the transparent substrate  145  and the sensing electrode  140 . 
       FIGS. 6 to 8  are cross-sectional views showing an operation process of the electronic paper associated with a touch panel of  FIG. 1 . An operation process of the electronic paper associated with a touch panel according to the present embodiment will be described with reference to  FIGS. 6 to 8 . 
     First, as shown in  FIG. 6 , the electronic paper  100  associated with a touch panel is prepared. At this time, white hemispheres of all the particles  111  of the electronic paper  100  associated with a touch panel face upward, before displaying images. Therefore, a user may sense that the electronic paper  100  associated with a touch panel is entirely white. Meanwhile, the upper electrode  120  generates signals so as to sense the touch of the input unit  150 , such that capacitance is formed between the upper electrode  120  and the sensing electrode  140 . 
     Then, as shown in  FIG. 7 , the touched coordinates of the input unit  150  are calculated. When the transparent substrate  145  is touched by the input unit  150 , a portion of the charges is flowed into the input unit  150  to change the capacitance between the upper electrode  120  and the sensing electrode  140  and the sensing electrode  140  senses and transfers the change in the capacitance to the controller, thereby making it possible to calculate the touched coordinates. In this case, it is preferable to prevent the electronic ink  110  from being arbitrarily driven by maintaining of the lower electrode  130  at high-impedance. 
     Then, as shown in  FIG. 8 , images are implemented by driving the electronic ink  110  according to the calculated touched coordinates. In order to implement images corresponding to the touched coordinates, voltage is applied to the upper electrode  120  and the lower electrode  130 . At this time, the upper electrode  120  is formed of a TFT electrode, thereby making is possible to selectively apply positive voltage only to specific pixels  126 . Therefore, the black hemispheres having negative charges of the particles  111  disposed on the specific pixels  126  rotate to face upward. As a result, the user can sense that images are implemented in black on the white background. 
     The electronic paper  100  associated with a touch panel according to the present embodiment integrally combines an electronic paper with a touch panel, thereby making it possible to intuitively input information, while maintaining a thin thickness, which is the advantage of the electronic paper. In addition, the upper electrode  120  functions as a driving electrode of a touch panel, such that there is no need to form a separate driving electrode, thereby making it possible to simplify a structure of the electronic paper  100  associated with a touch panel. 
     According to the present invention, the electronic paper is integrally combined with the touch panel by using the upper electrode of the electronic paper as a driving electrode of the touch panel, thereby making it possible to intuitively input information, while maintaining a thin thickness, which is the advantage of the electronic paper. 
     Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, they are for specifically explaining the present invention and thus the electronic paper associated with a touch panel according to the present invention is not limited thereto, but those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. Accordingly, such modifications, additions and substitutions should also be understood to fall within the scope of the present invention.