Patent Publication Number: US-2016224149-A1

Title: Touch sensor

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     Korean Patent Application No. 10-2015-0016956, filed on Feb. 3, 2015, in the Korean Intellectual Property Office, and entitled: “Touch Sensor,” is incorporated by reference herein in its entirety. 
     BACKGROUND 
     1. Field 
     The present disclosure relates to a touch sensor, and more particularly, to a touch sensor included in a touch panel. 
     2. Description of the Related Art 
     Display devices, e.g., a liquid crystal display (LCD), an organic light emitting diode (OLED) display, and the like, portable transmitters, other information processing devices, and the like perform functions thereof using various input devices. Recently, as the above-mentioned input devices, an input device including a touch sensing device has been mainly used. 
     The touch sensing function refers to a function detecting touch information, e.g., whether or not an object approaches or touches a screen and a touch location of the object by sensing, by the display device, a change in pressure, charge, and light which are applied to a screen thereof in the case in which a user approaches or touches the screen with a finger or a touch pen, e.g., so as to write letters or make a picture on the screen. The display device may receive an image signal and display an image based on the touch information. 
     The touch sensing function may be implemented by a touch sensor. The touch sensor may be classified depending on various touch sensing types, e.g., a resistive type, a capacitive type, an electromagnetic resonance (EMR) type, and an optical type. 
     For example, in a case of the resistive type touch sensor, two electrodes spaced apart from each other so as to face each other may be in contact with each other by pressure by an external object. When two electrodes are in contact with each other, the resistive type touch sensor may detect a contact position by recognizing a voltage change depending on a resistance change at the contact position. In another example, the capacitive type touch sensor includes a sensing capacitor configured of touch electrodes capable of transmitting a sensing signal, and may sense a change in capacitance of the sensing capacitor generated when a conductor, e.g., the finger, approaches the sensor, so as to detect whether or not the conductor touches the sensor, the touch location thereof, and the like. 
     Such touch sensing sensor may be formed in the touch panel so as to be attached on the display device (add-on cell type), may also be formed out of a substrate of the display device (on-cell type), and may also be formed in the display device (in-cell type). The display device including the touch sensing sensor may detect whether or not the finger of the user or the touch pen touches the screen and the touch location information thereof, and may display an image accordingly. 
     SUMMARY 
     An exemplary embodiment provides a touch sensor including a plurality of touch electrodes on a touch area to sense touch, each of the touch electrodes having a plurality of branch electrodes parallel to each other in a first direction, and connection lines on the touch area and connected to the touch electrodes, the connection lines extending in the first direction in parallel to the branch electrodes, wherein a width of the connection line and a width of the branch electrode are equal to each other. 
     The connection lines and the branch electrodes may be disposed at an equidistant interval in the touch area. 
     A width between the connection lines may be equal to the width of the connection line. 
     A width between the branch electrodes may be equal to the width of the branch electrode. 
     A width between the branch electrodes may be different from the width of the branch electrode. 
     The touch sensor may further include at least one connection electrode connecting neighboring branch electrodes. 
     The connection electrode may be connected to the branch electrode to be perpendicular to the branch electrode. 
     The connection electrode may be disposed at one side of an opening part formed between the neighboring branch electrodes. 
     The connection electrode may connect the neighboring branch electrodes across the opening part. 
     The touch electrodes may be disposed in rows and columns. 
     A plurality of connection lines which are each connected to the touch electrode disposed in any one column among the rows and columns may be disposed between columns of neighboring touch electrodes. 
     Facing sides of the touch electrodes which are adjacent in the column direction may have a step shape. 
     The step shapes of the facing sides may be formed so as to be engaged with each other. 
     The facing sides may have the step shape formed in a direction in which the facing sides are repeatedly increased or decreased as the facing sides become distant from the connection line. 
     The width of the connection line and the width of the branch electrode may be 10 μm to 100 μm. 
     The touch electrode may include at least one of indium tin oxide (ITO), indium zinc oxide (IZO), a metal nanowire, and conductive polymer. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Features will become apparent to those of ordinary skill in the art by describing in detail exemplary embodiments with reference to the attached drawings, in which: 
         FIG. 1  illustrates a schematic layout view of a touch screen panel including a touch sensor according to an exemplary embodiment of the present disclosure. 
         FIG. 2  illustrates a plan view of a touch sensor according to an exemplary embodiment of the present disclosure. 
         FIG. 3  illustrates an enlarged view of a portion of  FIG. 2 . 
         FIGS. 4-7  illustrate plan views of touch sensor according to other exemplary embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Example embodiments will now be described more fully hereinafter with reference to the accompanying drawings; however, they may be embodied in 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 exemplary implementations to those skilled in the art. 
     In the drawing figures, the dimensions of layers and regions may be exaggerated for clarity of illustration. It will also be understood that when a layer or element is referred to as being “on” another layer or substrate, it can be directly on the other layer or substrate, or intervening layers or elements may also be present. In addition, when it is described that an element is “coupled” to another element, the element may be “directly coupled” to the other element or “electrically coupled” to the other element through a third element. Further, it will also be understood that when a layer is referred to as being “between” two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present. Like reference numerals refer to like elements throughout. 
     In addition, unless explicitly described to the contrary, the word “comprise” and variations such as “comprises” or “comprising”, will be understood to imply the inclusion of stated elements but not the exclusion of any other elements. 
     Hereinafter, a touch sensor according to an exemplary embodiment of the present disclosure will be described in detail with reference to the accompanying drawings. 
       FIG. 1  illustrates a schematic layout view of a touch panel including a touch sensor according to an exemplary embodiment of the present disclosure. 
     As shown in  FIG. 1 , a touch panel according to an exemplary embodiment of the present disclosure may include a touch sensor  10  formed on a substrate  100  and a sensing signal controlling unit  800  connected to the touch sensor  10 . The touch sensor  10  according to an exemplary embodiment of the present disclosure, which is a touch sensor capable of sensing a touch of an external object, may be any suitable type of touch sensor, but a capacitive type touch sensor will be described in the present exemplary embodiment by way of example. 
     The touch sensor  10  may be included in a display panel or in a separate touch panel, so as to sense the touch. An example in which the touch sensor is included in the touch panel will be mainly described in the present exemplary embodiment. Here, the touch includes a case in which an external object approaches the display panel or the touch panel, as well as a case in which the external object is directly in contact with the display panel or the touch panel. 
     The touch sensor  10  according to an exemplary embodiment of the present disclosure may include a plurality of touch electrodes Sx disposed on an active area AA and a plurality of connection lines RL connected to the touch electrodes Sx. The active area AA, i.e., an area to which the touch may be applied and from which the touch may be sensed, may be overlapped with a display area, on which an image is displayed, in a case of the display panel, for example. In a case of the touch panel, the active area may be a touch area, and in the case in which the touch panel is embedded in the display panel, the touch area may be overlapped with the display area. Hereinafter, the active area AA is also referred to as the touch area. 
     As illustrated in  FIG. 1 , the plurality of touch electrodes Sx may be arranged in rows and columns form, and may be formed on a same layer as each other in a cross-sectional structure. For example, as illustrated in  FIG. 1 , the plurality of touch electrodes Sx may be arranged in a same layer in a matrix pattern along the x-axis and the y-axis. Each touch electrode Sx may include a transparent conductive material, e.g., indium tin oxide (ITO) and indium zinc oxide (IZO), and a metal nanowire, e.g., a silver (Ag) nanowire, but is not limited thereto. 
     The touch electrode Sx may have a quadrangular shape as shown in  FIG. 1 , but is not limited thereto. For example, the touch electrode Sx may have various shapes. Referring to  FIG. 3  to be described below, the touch electrode Sx may have an edge side formed in a step shape in order to increase touch sensitivity. In the case in which the edge side of the touch electrode Sx includes the step shape, the edge side may be engaged, e.g., complementary, with a side having the step shape of a neighboring touch electrode Sx. 
     Referring back to  FIG. 1 , a length of one side of the touch electrode Sx may be approximately several mm. For example, a length of one side of the touch electrode Sx may be about 10 mm or less, e.g., about 4 mm to about 5 mm, but a size of the touch electrode Sx may be adjusted depending on touch sensing resolution. 
     The plurality of touch electrodes Sx may be separated from each other in the touch area, e.g., along the x-axis and the y-axis. Different touch electrodes Sx may be connected to the sensing signal controlling unit  800  through different connection lines RL, e.g., each touch electrodes Sx may be connected to the sensing signal controlling unit  800  through a separate connection lines RL to operate independently of each other. 
     The touch electrodes Sx according to an exemplary embodiment of the present disclosure may receive a sensing input signal from the sensing signal controlling unit  800  through the respective connection lines RL, and generate a sensing output signal according to the touch so as to be transmitted to the sensing signal controlling unit  800 . 
     Each touch electrode Sx may form a self sensing capacitor so as to be charged with a predetermined charge amount after receiving the sensing input signal. Thereafter, when the external object, e.g., a finger, touches the touch panel, the charge amount charged in the self sensing capacitor may be changed, such that a sensing output signal different from the received sensing input signal may be output. Touch information, e.g., whether or not the object touches the touch panel and a touch position, may be detected through the sensing output signal generated as described above. 
     The connection lines RL connect the touch electrodes Sx and the sensing signal controlling unit  800 , so as to transmit the sensing input signal or the sensing output signal. The connection lines RL may be disposed on the same layer as the touch electrodes Sx and may be made of the same material as the touch electrodes Sx. However, the present disclosure is not limited thereto, e.g., the connection lines RL may be disposed on a layer different from the touch electrode Sx and may also be connected to the touch electrode Sx through a separate connection part. 
     Meanwhile, the closer the sensing signal controlling unit  800 , the more the number of connection lines RL disposed between the touch electrodes Sx included in a row disposed so as to be adjacent to the sensing signal controlling unit  800 . Therefore, the closer the sensing signal controlling unit  800 , the smaller a size of the touch electrode Sx or a width of the touch electrode Sx (i.e., a width of a side traversing between neighboring connection lines along the x-axis). 
     A width of a connection line RL may be approximately about 10 μm to about 100 μm, but is not limited thereto. 
     The sensing signal controlling unit  800  is connected to the touch electrodes Sx of the touch panel so as to transmit the sensing input signal to the touch electrodes Sx and to receive the sensing output signal from the touch electrodes Sx. The sensing signal controlling unit  800  may generate the touch information, e.g., whether or not the object touches the touch panel and the touch position, by processing the sensing output signal. 
     For example, the sensing signal controlling unit  800  may also be disposed on a printed circuit board independent of the substrate  100  of the touch panel so as to be connected to the touch panel. In another example, the sensing signal controlling unit  800  may also be attached onto the substrate  100  of the touch panel in a form of an integrated chip or a TCP form, and may also be integrated on the substrate  100 . 
     Hereinafter, a touch sensor according to an exemplary embodiment of the present disclosure will be described in detail with reference to  FIGS. 2-3 . 
       FIG. 2  illustrates a plan view of a touch sensor according to an exemplary embodiment of the present disclosure.  FIG. 3  is an enlarged view of a touch electrode disposed in any one column of  FIG. 2 . 
     For example,  FIG. 2  illustrates a case in which the touch electrodes Sx are disposed in four rows along the x-axis and in three columns along the y-axis, and are separated from each other by a space SP. As an example, one touch electrode Sx is indicated by a dashed frame. However, the present disclosure is not limited thereto, e.g., the touch electrodes may have any suitable number of rows and columns.  FIG. 3  illustrates an enlarged view showing a first column of the touch electrodes Sx in  FIG. 2  along the y-axis. In this case, a direction to which the connection line RL is extended is a column direction, i.e., along the y-axis, and a direction intersecting with the connection line RL is a row direction, i.e., along the x-axis. 
     As shown in  FIGS. 2 and 3 , the touch electrode Sx has a plurality of opening parts T spaced apart from each other. Each of the opening parts T may be formed in a long quadrangle in the same direction as the connection line RL, i.e., along the y-axis, and may be spaced apart from an adjacent opening part T along the x-axis. Therefore, the touch electrode Sx includes a plurality of branch electrodes S 1  disposed between the opening parts T, and a connection electrode S 2  connected to first ends of the branch electrodes S 1 . That is, as illustrated in  FIG. 2 , each branch electrode S 1  extends between two adjacent opening parts T, and the first end of each branch electrode S 1  is connected to the connection electrode S 2 . Since the connection electrode S 2  is disposed, e.g., only, at one side of the opening part T having the quadrangular shape so as to connect the branch electrodes S 1 , the connection electrode S 2  may be connected to the first ends of the branch electrodes S 1  to be perpendicular thereto, i.e., the connection electrode S 2  may extend along the x-axis. 
     When an area in which the touch electrodes Sx are disposed is defined as a sensing area A and an area in which the connection lines RL are disposed is defined as a line area B, pattern densities of the sensing area A and the line area B may be the same. In this case, the pattern is the branch electrodes S 1  and the connection lines RL, and the pattern density may be determined by a width and an arrangement interval of the branch electrodes S 1  and the connection lines RL. 
     Therefore, in order to allow the pattern density to be equal, a width D 1  of the opening part T is equal to a width D 2  between two neighboring connection lines RL ( FIG. 3 ). Further, a width D 3  of the branch electrode S 1  is equal to a width D 4  of the connection line RL ( FIG. 3 ). In this case, a width D 5  of the connection electrode S 2  may also be equal to the width D 3  of the branch electrode S 1 . The width of each of the connection line RL and the width of the branch electrode S 1  may be about 10 μm to about 100 μm. Although  FIGS. 2 and 3  illustrate the width D 1  of the opening part T, the width D 2  between the neighboring connection lines RL, the width D 3  of the branch electrode S 1 , and the width D 4  of the connection line RL as equal, the present disclosure is not limited thereto. 
     Meanwhile, as illustrated in  FIG. 3 , facing sides of two touch electrodes Sx which are adjacent in a column direction, i.e., along the y-axis, are each formed in a step shape. That is, the facing sides of the two touch electrodes Sx are formed in the step shape by having branch electrodes S 1  adjacent to each other in the row direction, i.e., along the x-axis, increased or decreased by a predetermined length in a column direction, i.e., along the y-axis. 
     The reason is that the length of the branch electrode S 1  or the opening part T of the touch electrode Sx is changed while being repeatedly increased or decreased as the branch electrode S 1  or the opening part T is closer to the connection line RL, and the connection electrode S 2  connects the branch electrodes S 1 . In addition, although  FIG. 3  shows a case in which the sides of neighboring touch electrodes Sx repeat twice a gradual increase or decrease in the row direction, the present disclosure is not limited thereto, e.g., the sides of the neighboring touch electrodes Sx may be formed by repeating once or three or more times the gradual increase or decrease in the row direction. 
     In  FIG. 3 , since the length of the branch electrode S 1  is gradually changed as much as the width of the branch electrode S 1  or the width of the connection electrode S 2 , a height D 6  of the step may be the same as the width D 3  of the branch electrode S 1  or the width D 5  of the connection electrode S 2 . 
     As described above, according to an exemplary embodiment of the present disclosure, since the densities of the patterns disposed in the sensing area A and the line area B are equal to each other by forming the width D 1  of the opening part T so as to be equal to the width D 2  between the connection lines RL, and forming the width D 3  of the branch electrode S 1  so as to be equal to the width D 4  of the connection line RL, a pattern visibility phenomenon due to haze, or the like may be decreased in the touch panel. In addition, according to an exemplary embodiment of the present disclosure, since the length of the connection electrode S 2  is minimized and an area of the connection electrode S 2  is reduced by connecting the connection electrode S 2  to the branch electrode S 1  so as to be perpendicular thereto, the pattern visibility phenomenon due to the haze may be decreased in the touch panel. 
       FIGS. 4-7  illustrate plan views of a touch sensor according to other exemplary embodiments. 
     Referring to  FIG. 4 , the touch sensor is substantially the same as the touch sensor of  FIG. 3 , so only different parts will be described in more detail. 
     As shown in  FIG. 4 , the touch sensor includes the touch electrodes Sx and the connection lines RL connected to the touch electrodes Sx. Each touch electrode Sx has a plurality of opening parts T, and the touch electrode Sx includes the plurality of branch electrodes S 1  disposed between the opening parts T and the connection electrode S 2  connected to the first ends of the branch electrodes S 1 . Since the connection electrode S 2  is disposed only at one side of the opening parts T having the quadrangular shape so as to connect the branch electrodes S 1 , it may be connected to the branch electrode S 1  to be perpendicular thereto. 
     The width D 1  of the opening part T of the touch electrode Sx shown in  FIG. 4  is equal to the width D 2  between the connection lines RL, and the width D 3  of the branch electrode S 1  is equal to the width D 4  of the connection line RL. In this case, the width D 1  of the opening part and the width D 2  between the connection lines RL may be different from the width D 3  of the branch electrode and the width D 4  of the connection line RL. 
     That is, as shown in  FIG. 4 , the width D 1  of the opening part and the width D 2  between the connection lines RL may be narrower than the width D 3  of the branch electrode and the width D 4  of the connection line RL. In addition, the width D 1  of the opening part and the width D 2  between the connection lines RL may be wider than the width D 3  of the branch electrode and the width D 4  of the connection line RL (not shown). By forming the widths of the branch electrode S 1  and the connection line S 2  to be equal to each other and disposed at the same interval, densities of patterns in the sensing area A and the line area B may be equal to each other. 
     Referring to  FIG. 5 , the touch sensor is substantially the same as the touch sensor of  FIG. 3 , so only different parts will be described in more detail. 
     As shown in  FIG. 5 , the touch sensor includes the touch electrodes Sx and the connection lines RL connected to the touch electrodes Sx. Each touch electrode Sx has a plurality of opening parts T, and the touch electrode Sx includes the plurality of branch electrodes S 1  disposed between the opening parts T and the connection electrode S 2  connected to one ends of the branch electrodes S 1 . Since the connection electrode S 2  is disposed at only one side of the opening part T having the quadrangular shape so as to connect the branch electrodes S 1 , it may be connected to the branch electrode S 1  to be perpendicular thereto. 
     In this case, since the width D 1  of the opening part T, the width D 2  between the neighboring connection lines RL, the width D 3  of the branch electrode S 1 , the width D 4  of the connection line RL, and the width D 5  of the connection electrode S 2  are all equal, densities of patterns in the sensing area A and the line area B are equal to each other. 
     Meanwhile, the length of the opening part T or the length of the branch electrode S 1  is gradually changed, as much as the width D 5  of the connection electrode S 2  in  FIG. 3 , but the length of the opening part T or the length of the branch electrode S 1  of  FIG. 5  may be changed as much as a width different from the width of the connection electrode S 2 . Therefore, a height D 6  of a step of the facing sides of the neighboring touch electrodes of  FIG. 5  is larger than the width D 5  of the connection electrode S 2 . Further, the height D 6  of the step may be smaller than the width of the connection electrode S 2  (not shown). 
     If the height of the step is changed, an angle θ formed by a virtual diagonal line L connecting vertices of the sides of the touch electrode Sx and the connection line RL is changed. As shown in  FIG. 5 , if the height of the step is increased, the angle formed by the virtual diagonal line L and the connection line RL may be smaller than an angle formed by a virtual diagonal line of the touch electrode and the connection line RL as shown in  FIG. 3 . 
     This is to diverse, e.g., vary, the lengths of the sides of the touch electrode Sx depending on sensing capacity of the touch electrode Sx. The lengths of the touch electrode Sx may be easily changed by changing the length of the opening part T and the length of the branch electrode S 1 . 
     Referring to  FIG. 6 , the touch sensor is substantially the same as the touch sensor of  FIG. 3 , so only different parts will be described in more detail. 
     As shown in  FIG. 6 , the touch sensor includes the touch electrodes Sx and the connection lines RL connected to the touch electrodes Sx. Each touch electrode Sx has a plurality of opening parts T, and the touch electrode Sx includes the plurality of branch electrodes S 1  disposed between the opening parts T and the connection electrode S 2  connected to first ends of the branch electrodes S 1 . Since the connection electrode S 2  is disposed at one side of the opening part T having the quadrangular shape so as to connect the branch electrodes S 1 , it may be connected to the branch electrode S 1  to be perpendicular thereto. 
     In addition, the touch sensor further includes an auxiliary connection electrode S 3  connecting two neighboring branch electrodes S 1  and the branch electrode S 1 . The auxiliary connection electrode S 3  is disposed in the opening part T, and the opening part T may be divided into a plurality of small opening parts T 1  by the auxiliary connection electrode S 3 . 
     Since the auxiliary connection electrode S 3  connects the branch electrodes S 1 , a current flows through the auxiliary connection electrode S 3  even when some of the branch electrodes S 1  are disconnected. Therefore, when some of the branch electrodes S 1  are disconnected, RC delay may be reduced by minimizing a movement path of the current in the touch electrode. Further, since haze may occur as the number of auxiliary connection electrodes S 3  is increased, the number of auxiliary connection electrodes S 3  formed in the opening part T may be 0 to 4. 
     Referring to  FIG. 7 , the touch sensor is substantially the same as the touch sensor of  FIG. 3 , so only different parts will be described in more detail. 
     As shown in  FIG. 7 , the touch sensor includes the touch electrodes Sx and the connection lines RL connected to the touch electrodes Sx. The touch electrode Sx has a plurality of opening parts T, and the touch electrode Sx includes the plurality of branch electrodes S 1  disposed between the opening parts T and the connection electrode S 2  connected to first ends of the branch electrodes S 1 . Since the connection electrode S 2  is disposed at one side of the opening part T having the quadrangular shape so as to connect the branch electrodes S 1 , it may be connected to the branch electrode S 1  to be perpendicular thereto. 
     A touch electrode Sx having a relatively low resistance among the touch electrodes of  FIG. 7  may be connected to the connection line RL and one connection electrode S 2 . That is, a touch electrode Sx having a relatively high resistance is connected to the connection line RL and two connection electrodes S 2 . However, the touch electrode Sx having the relatively low resistance has a portion P which is not connected and disconnected, and the branch electrode S 1  and the connection line RL are connected to one connection electrode S 2 . As such, if the number of connection electrodes connected to the connection line is different, the movement path of the current is decreased or increased, such that a decrease and increase phenomenon of resistance due to the movement path occurs. 
     Since the touch sensor according to the present disclosure is the self sensing capacitor capable of detecting the touch information such as whether or not the touch occurs, the touch location, or the like from a change in a resistance value when a touch operation occurs, the touch electrodes are designed so as to have the same resistance value. 
     In the case in which the touch electrode is formed using the plurality of branch electrodes or opening parts as in the exemplary embodiments of the present disclosure, the resistance value of the touch electrode may be changed. Therefore, in the touch electrode having the relatively low resistance value, by disconnecting one of the plurality of connection electrodes S 2  connected to the connection line RL so as to increase the resistance value, it is possible to maintain the resistance value to be equal to that of other touch electrodes. 
     Hereinabove, although the case in which the two connection electrodes and the connection line are connected has been described by way of example, the present disclosure is not limited thereto. For example, in the case in which the opening parts having various sizes are provided as shown in  FIG. 6 , more than two connection electrodes and the connection line may be connected, and the resistance value of the touch electrode may be easily adjusted by adjusting the number of connections of the connection electrodes and the connection line. 
     By way of summation and review, electrodes in a conventional sensing sensor may be formed of a transparent conductive film, e.g., indium tin oxide (ITO), or the like, coated with a thin film. However, since the electrodes have weak twist property due to a thin film made of an inorganic material, it is disadvantageous to implement flexibility of a finished product. Attempts have been made to make the thin film of the electrodes with a highly transparent and conductive silver nanowire ink technology. However, a coating layer formed by the silver nanowire ink has increased pattern visibility due to haze. Therefore, the present disclosure provides a touch panel having decreased haze, thereby providing improvised visibility even when the sensing electrodes are formed of a silver nanowire. 
     Example embodiments have been disclosed herein, and although specific terms are employed, they are used and are to be interpreted in a generic and descriptive sense only and not for purpose of limitation. In some instances, as would be apparent to one of ordinary skill in the art as of the filing of the present application, features, characteristics, and/or elements described in connection with a particular embodiment may be used singly or in combination with features, characteristics, and/or elements described in connection with other embodiments unless otherwise specifically indicated. Accordingly, it will be understood by those of skill in the art that various changes in form and details may be made without departing from the spirit and scope of the present invention as set forth in the following claims.