Patent Publication Number: US-2018046278-A1

Title: Touch display panel

Description:
FIELD 
     The subject matter herein generally relates to a touch display panel. 
     BACKGROUND 
     An on-cell or in-cell type touch screen panel can be manufactured by installing a touch panel in a display panel. Such a touch screen panel is used as an output device for displaying images while being used as an input device for receiving a command of a user touching a specific area of a displayed image. However, the touch screen panel cannot sense the pressure of the touch. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Implementations of the present disclosure will now be described, by way of example only, with reference to the attached figures. 
         FIG. 1  is an isometric view of an exemplary embodiment of a touch display panel. 
         FIG. 2  is an exploded view of a first exemplary embodiment of a touch display panel. 
         FIG. 3  is a cross-sectional view of the first exemplary embodiment of the touch display panel of  FIG. 1  along line III-III. 
         FIG. 4  is an exploded view of a second exemplary embodiment of a touch display panel. 
         FIG. 5  is a cross-sectional view of the second exemplary embodiment of the touch display panel of  FIG. 4 . 
         FIG. 6  is an exploded view of a third exemplary embodiment of a touch display panel. 
         FIG. 7  is a cross-sectional view of the third exemplary embodiment of the touch display panel of  FIG. 6 . 
     
    
    
     DETAILED DESCRIPTION 
     It will be appreciated that for simplicity and clarity of illustration, where appropriate, reference numerals have been repeated among the different figures to indicate corresponding or analogous structures. In addition, numerous specific details are set forth in order to provide a thorough understanding of the exemplary embodiments described herein. However, it will be understood by those of ordinary skill in the art that the exemplary embodiments described herein may be practiced without these specific details. In other instances, methods, procedures, and components have not been described in detail so as not to obscure the related relevant feature being described. Also, the description is not to be considered as limiting the scope of the exemplary embodiments described herein. The drawings are not necessarily to scale and the proportions of certain parts may be exaggerated to better illustrate details and features of the present disclosure. 
     The term “coupled” is defined as connected, whether directly or indirectly through intervening components, and is not necessarily limited to physical connections. The connection can be such that the objects are permanently connected or releasably connected. The term “comprising” when utilized, means “including, but not necessarily limited to”; it specifically indicates open-ended inclusion or membership in the so-described combination, group, series, and the like. 
       FIG. 1 ,  FIG. 2 , and  FIG. 3  illustrate a touch display panel  100  according to a first exemplary embodiment. 
     In the present exemplary embodiment, the touch display panel  100  is an in-cell touch liquid crystal display panel.  FIG. 2  does not show a liquid crystal layer of the touch display panel  100 . The touch display panel  100  includes a color filter substrate  110 , a thin film transistor substrate  130  facing the color filter substrate  110 , and a liquid crystal layer  150  between the color filter substrate  110  and the thin film transistor substrate  130 . The thin film transistor substrate  130  is a conventional thin film transistor substrate and includes a substrate (not shown) and a plurality of thin film transistors (not shown) on the substrate. The color filter substrate  110  is a conventional color filter substrate comprising a substrate (not shown) and a color filter layer (not shown) on the substrate. The touch display panel  100  defines a display area  140  and a border area  160  surrounding the display area  140 . 
     The touch display panel  100  further includes a touch sensing structure  30  configured for sensing touch positions and a force sensing structure  50  configured for sensing force of touch. Both the touch sensing structure  30  and the force sensing structure  50  are formed on the color filter substrate  110  and the thin film transistor substrate  130 . The touch sensing structure  30  is positioned in the display area  140 , and the force sensing structure  50  is positioned in the border area  160 . 
     As shown in  FIG. 2  and  FIG. 3 , the touch sensing structure  30  includes a plurality of first touch electrodes  31  and a plurality of second touch electrodes  33 . The plurality of first touch electrodes  31  is formed on a surface of the thin film transistor substrate  130  facing the color filter substrate  110 . The plurality of second touch electrodes  33  is formed on a surface of the color filter substrate  110  away from the thin film transistor substrate  130 . As shown in  FIG. 2 , the plurality of first touch electrodes  31  are spaced apart from each other; and each first touch electrode  31  has a strip shape and extends along a first direction. The plurality of second touch electrodes  33  are spaced apart from each other, and each second touch electrode  33  is substantially U-shaped. Each second touch electrode  33  includes two extending portions  331  parallel to each other and a connecting portion  333  between the two extending portions  331 . Each extending portion  331  extends along a second direction. The second direction is different from the first direction. In the present exemplary embodiment, the first direction is substantially perpendicular to the second direction. The first touch electrodes  31  are used as touch driving electrode for transmitting driving signal, and the second touch electrodes  33  are used to receive touch sensing signals. In the present exemplary embodiment, the first touch electrodes  31  also function as common electrodes of the touch display panel  100  and cooperate with pixel electrodes (not shown) to drive the liquid crystals in the liquid crystal layer  150  to rotate. 
     As shown in  FIG. 2  and  FIG. 3 , the force sensing structure  50  includes a plurality of first force sensing electrodes  51  and a second force sensing electrode  53 . The first force sensing electrodes  51  and the first touch electrodes  31  are formed on a same surface. The first force sensing electrodes  51  are formed on the surface of the thin film transistor substrate  130  facing the color filter substrate  110 . The first force sensing electrodes  51  cooperate to surround the first touch electrodes  31 . The first touch electrodes  31  and the first force sensing electrodes  51  may be defined by a same conductive material layer and be formed by a single patterning process. The first touch electrodes  31  and the first force sensing electrode  51  may be made of a same transparent conductive material, such as indium tin oxide. 
     As shown in  FIG. 2  and  FIG. 3 , the second force sensing electrode  53  and the second touch electrodes  33  are formed on the same surface. The second force sensing electrode  53  is formed on the surface of the color filter substrate  110  away from the thin film transistor substrate  130  and surrounds the second touch electrodes  33 . The second force sensing electrode  53  and the second touch electrodes  33  may be defined by a same conductive material layer and be formed by a single patterning process. The second force sensing electrode  53  and the second touch electrodes  33  may be made of a transparent conductive material, such as indium tin oxide. 
     A projection of the first force sensing electrodes  51  on the color filter substrate  110  overlaps with the second force sensing electrode  53 . 
     The first force sensing electrodes  51  are spaced apart from each other. The first force sensing electrodes  51  cooperate to surround the first touch electrodes  31  and are located in the border area  160 . The second force sensing electrode  53  is continuous and extends to surround the second touch electrodes  33 . In the present exemplary embodiment, the second force sensing electrode  53  is substantially U-shaped. In other embodiments, the second force sensing electrode  53  may have a rectangle shape. 
     In the present exemplary embodiment, each first force sensing electrode  51  has a strip shape and a length of more than 4 mm and a width of more than 100 μm. It is understood that the length of each first force sensing electrode  51  may be adjusted according to a number of the first force sensing electrodes  51 . It is understood that the shape of each first force sensing electrode  51  may be adjusted, not being limited to a strip shape. 
     The touch display panel  100  further includes a touch control circuit  60  in the border area  160 , particularly on the thin film transistor substrate  130 . The touch sensing structure  30  is electrically coupled to the touch control circuit  60  by a plurality of traces (not shown). For example, each first touch electrode  31  may be electrically coupled to the touch control circuit  60  by one trace and each second touch electrode  33  may be electrically coupled to the touch control circuit  60  by one trace. When a finger is touching the display panel  100 , electric signals of the second touch electrodes  33  corresponding to the touch position will vary. The variation of the electric signal is transmitted to the touch control circuit  60  by the traces, thus the touch position can be detected. 
     In the present exemplary embodiment, the second force sensing electrode  53  is grounded. The first force sensing electrodes  51  and the second force sensing electrode  53  cooperatively form a capacitive force sensing structure. When a finger is touching the display panel  100 , a distance between the second force sensing electrode  53  and the first force sensing electrodes  51  corresponding to the touch position may change, thus a capacitance value between the second force sensing electrode  53  and the first force sensing electrodes  51  will vary. The touch force can be calculated by the variation of the capacitance value. 
       FIG. 1 ,  FIG. 4 , and  FIG. 5  illustrate a touch display panel  200  according to a second exemplary embodiment. 
     In the second exemplary embodiment, the touch display panel  200  is an in-cell touch liquid crystal display panel.  FIG. 5  does not show a liquid crystal layer of the touch display panel  200 . The touch display panel  200  includes a color filter substrate  110 , a thin film transistor substrate  130  facing color filter substrate  110 , a liquid crystal layer  150  between the color filter substrate  110  and the thin film transistor substrate  130 , and a dielectric layer  210  stacked at a side of the color filter substrate  110  away from the thin film transistor substrate  130 . The thin film transistor substrate  130  is a conventional thin film transistor substrate and includes a substrate (not shown) and a plurality of thin film transistors (not shown) on the substrate. The color filter substrate  110  is a conventional color filter substrate comprising a substrate (not shown) and a color filter layer (not shown) on the substrate. The touch display panel  200  defines a display area  140  and a border area  160  surrounding the display area  140 . The dielectric layer  210  is elastic and transparent. 
     The touch display panel  200  further includes a touch sensing structure  30  configured for sensing touch position and a force sensing structure  50  configured for sensing force. The touch sensing structure  30  is in the display area  140 , and the force sensing structure  50  is in the border area  160 . 
     As shown in  FIG. 4  and  FIG. 5 , the touch sensing structure  30  includes a plurality of first touch electrodes  31  and a plurality of second touch electrodes  33 . The plurality of first touch electrodes  31  is formed on a surface of the thin film transistor substrate  130  facing the color filter substrate  110 . The plurality of second touch electrodes  33  is formed on a surface of the dielectric layer  210  away from the thin film transistor substrate  130 . As shown in  FIG. 4 , each of the plurality of first touch electrodes  31  are spaced apart from each other; and each first touch electrode  31  has a strip shape and extends along a first direction. The plurality of second touch electrodes  33  are spaced apart from each other, and each second touch electrode  33  is substantially U-shaped. Each second touch electrode  33  includes two parallel extending portions  331  and a connecting portion  333  between the two extending portions  331 . Each extending portion  331  extends along a second direction. The second direction is different from the first direction. In the present exemplary embodiment, the first direction is substantially perpendicular to the second direction. The first touch electrodes  31  are used as touch driving electrode for transmitting driving signals, and the second touch electrodes  33  are used to receive touch sensing signals. In the present exemplary embodiment, the first touch electrodes  31  also function as common electrodes of the display panel  100  and cooperate with pixel electrodes (not shown) to drive the liquid crystals in the liquid crystal layer  150  to rotate. 
     As shown in  FIG. 4  and  FIG. 5 , the force sensing structure  50  includes a plurality of first force sensing electrodes  51  and a second force sensing electrode  53 . The first force sensing electrodes  51  are formed on a surface of the color filter substrate  110  away from the thin film transistor substrate  130 . The first force sensing electrodes  51  cover a periphery of the color filter substrate  110 . 
     As shown in  FIG. 4  and  FIG. 5 , the second force sensing electrode  53  and the second touch electrodes  33  are formed on the same surface. The second force sensing electrode  53  is formed on the surface of the dielectric layer  210  away from the thin film transistor substrate  130  and surrounds the second touch electrodes  33 . The second force sensing electrode  53  and the second touch electrodes  33  may be defined by a same conductive material layer and be formed by a single patterning process. The second force sensing electrode  53  and the second touch electrodes  33  may be made of transparent conductive material, such as indium tin oxide. 
     A projection of the first force sensing electrodes  51  on the dielectric layer  210  overlaps with the second force sensing electrode  53 . 
     The first force sensing electrodes  51  are spaced apart from each other and located in the border area  160 . The second force sensing electrode  53  is continuous and extends to surround the second touch electrodes  33 . In the present exemplary embodiment, the second force sensing electrode  53  is rectangle shape. In the present exemplary embodiment, each first force sensing electrode  51  has a strip shape, a length of more than 4 mm and a width of more than 100 μm. It is understood that the length of each first force sensing electrode  51  may be adjusted according to a number of the first force sensing electrodes  51 . It is understood that the shape of each first force sensing electrode  51  may be adjusted, not being limited to a strip shape. 
     The display panel  200  further includes a touch control circuit  60  in the border area  160  and on the thin film transistor substrate  130 . The touch sensing structure  30  is electrically coupled to the touch control circuit  60  by a plurality of traces (not shown). For example, each first touch electrode  31  may be electrically coupled to the touch control circuit  60  by one trace and each second touch electrode  33  may be electrically coupled to the touch control circuit  60  by one trace. When a finger is touching the display panel  200 , the electric signals of the second touch electrodes  33  corresponding to the touch position will vary, and the variation of the electric signals is transmitted to the touch control circuit  60  by traces, thus the touch position can be detected. 
     In the present exemplary embodiment, the second force sensing electrode  53  is grounded. The first force sensing electrodes  51  and the second force sensing electrode  53  cooperatively form a capacitive force sensing structure. When a finger is touching the display panel  200 , a distance between the second force sensing electrode  53  and the first force sensing electrodes  51  corresponding to the touch position may change, thus the capacitance value between the second force sensing electrode  53  and the first force sensing electrodes  51  will vary. Thus touch force can be calculated by the variation of the capacitance value. 
       FIG. 1 ,  FIG. 6 , and  FIG. 7  illustrate a touch display panel  300  according to a third exemplary embodiment. 
     In the present exemplary embodiment, the touch display panel  300  is an in-cell touch liquid crystal display panel.  FIG. 6  does not show a liquid crystal layer of the touch display panel  300 . The touch display panel  300  is substantially the same as the display panel  100  of the first exemplary embodiment, except that the touch display panel  300  further includes a cover plate  310  stacked at a side of the color filter substrate  110  away from the thin film transistor substrate  130 . Another difference is that the first force sensing electrodes  51  are formed on a surface of the cover plate  310 . In this exemplary embodiment the first force sensing electrodes  51  are formed on a surface of the cover plate  310  away from the thin film transistor substrate  130 . In other embodiments, the first force sensing electrodes  51  may be formed on a surface of the cover plate  310  adjacent to the thin film transistor substrate  130 . The cover plate  310  is transparent. 
     The first force sensing electrodes  51  cover a periphery of the cover plate  310 . The cover plate  310  is bonded to the color filter substrate  110  by an optical clear adhesive  80 . 
     It is to be understood, even though information and advantages of the present exemplary embodiments have been set forth in the foregoing description, together with details of the structures and functions of the present exemplary embodiments, the disclosure is illustrative only. Changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the present exemplary embodiments to the full extent indicated by the plain meaning of the terms in which the appended claims are expressed.