Patent Publication Number: US-2013241845-A1

Title: Touch panel

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a touch panel, and more particularly, to a touch panel having a high signal to noise ratio (SNR) and a high signal sensing density by modifying shapes and allocations of different axis electrodes. 
     2. Description of the Prior Art 
     Since touch sensing technologies may be employed to improve human-computer interaction, electronic products, which have both the touch sensing function and the display function, are commercialized in recent years. There are many diverse technologies of touch panel, and the resistance touch technology, the capacitive touch technology and the optical touch technology are the main touch technologies in use. The capacitive touch technology has become the mainstream touch technology for the high-end and the mid-end consumer electronics, because the capacitive touch panel has advantages such as high precision, multi-touch property, better endurance, and higher touch sensing resolution. 
     In the capacitive touch technology, transparent sensing electrodes are used to detect the variations of electrical capacitances around a touch point, and feedback signals are transmitted via connecting lines, which interconnect all of the transparent sensing electrodes along different axis directions to locate the touch points. Please refer to  FIG. 1 .  FIG. 1  is a schematic diagram illustrating a conventional capacitive touch panel. As shown in  FIG. 1 , a conventional capacitive touch panel  100  includes a plurality of first axis electrodes  110  and a plurality of second axis electrodes  120 . Each of the first axis electrodes  110  extends along a first direction X and the first axis electrodes  110  are repeatedly disposed along a second direction Y. Each of the second axis electrodes  120  extends along the second direction Y and the second axis electrodes  120  are repeatedly disposed along the first direction X. Each of the first axis electrodes  110  includes a plurality of first sensing electrodes  111  and a plurality of first connecting lines  112 . The first sensing electrodes  111  and the first connecting lines  112  are aligned along the first direction X, and each of the first connecting lines  112  is used to electrically connect two adjacent first sensing electrodes  111  in the first direction X. Each of the second axis electrodes  120  includes a plurality of second sensing electrodes  121  and a plurality of second connecting lines  122 . The second sensing electrodes  121  and the second connecting lines  122  are aligned along the second direction Y, and each of the second connecting lines  122  is used to electrically connect two adjacent second sensing electrodes  121  in the second direction Y. In other words, the first axis electrodes  110  are disposed interlacedly with the second axis electrodes  120 . A shape of the first sensing electrode  111  is generally identical to a shape of the second sensing electrode  121 . For example, the first sensing electrode  111  and the second sensing electrode  121  are generally rhombus electrodes. The first sensing electrodes  111  and the second sensing electrodes  121  are disposed alternately and uniformly in the conventional capacitive touch panel  100 . 
     Under a mutual capacitive operation mode of the conventional capacitive touch panel  100 , touch driving signals TX are respectively applied to each of the first axis electrodes  110  by scanning Coupling capacitance effects may occur between the first sensing electrodes  111  and the second sensing electrodes  121 , and touch receiving signals RX may be obtained from each of the second axis electrodes  120 . The touch receiving signals RX may decline when a conductive touch object such as a human finger touches the conventional capacitive touch panel  100  because another coupling path may be generated to absorb some electrical charge due to the conductibility and the lower electrical potential of the human finger. The actual touch point may be figured out by calculating the variation of the touch receiving signals RX. Each of the first sensing electrodes  111  and each of the second sensing electrodes  121  must have specific areas to induce required coupling capacitance effect with the touch object. However, a parasitic capacitance between the first sensing electrode  111  and the second sensing electrode  121  may also be accordingly increased to interfere with the touch signals. In addition, under the structure of the conventional capacitive touch panel  100 , the areas of each of the first sensing electrodes  111  and each of the second sensing electrodes  121  have to be shrunk for increasing the signal sensing density and the touch sensing resolution. However, the coupling capacitance effect may also be reduced and the touch sensitivity may be affected by reducing areas of each of the first sensing electrodes  111  and each of the second sensing electrodes  121 . Generally, the first sensing electrodes  111  and the second sensing electrodes  121  are made of transparent conductive materials such as indium tin oxide (ITO) which is a material with high refractive index and may still absorb some light. Therefore, a visual difference may be generated between a region with the sensing electrodes and a region without the sensing electrodes, an issue of visible sensing electrodes may occur, and an appearance quality of the touch panel may accordingly be affected. 
     SUMMARY OF THE INVENTION 
     It is one of the objectives of the present invention to provide a touch panel. Shapes and allocations of different axis electrodes are modified. Electrodes extending along one axis are disposed to surround sensing electrodes of electrodes extending along another axis. A signal to noise ratio (SNR) and a signal sensing density of the touch panel may be accordingly enhanced. 
     To achieve the purposes described above, a preferred embodiment of the present invention provides a touch panel. The touch panel includes a plurality of first axis electrodes and a plurality of second axis electrodes. The first axis electrodes extend along a first direction and the first axis electrodes are disposed repeatedly along a second direction. Each of the first axis electrodes includes a plurality of first sensing electrodes disposed along the first direction. The second axis electrodes extend along the second direction and the second axis electrodes are disposed repeatedly along the first direction. Each of the second axis electrodes surrounds the first sensing electrodes disposed along the second direction. 
     Another preferred embodiment of the present invention provides a touch panel. Each of the second axis electrodes has a plurality of hollow regions disposed along the second direction, and each of the first sensing electrodes is disposed in the hollow region. 
     Another preferred embodiment of the present invention provides a touch panel. Each of the first axis electrodes further comprises a plurality of first connecting lines to electrically connect the first sensing electrodes within one identical first axis electrode and transmit a touch driving signal, and a touch receiving signal is received from each of the second axis electrodes. 
     Another preferred embodiment of the present invention provides a touch panel. The touch panel further comprises a plurality of third axis electrodes extending along the first direction. The third axis electrodes are disposed repeatedly along the second direction, and each of the third axis electrodes is disposed between two adjacent first axis electrodes. 
     Another preferred embodiment of the present invention provides a touch panel. Each of the third axis electrodes comprises a plurality of second sensing electrodes disposed along the first direction, and each of the second sensing electrodes is disposed between two adjacent second axis electrodes. 
     Another preferred embodiment of the present invention provides a touch panel. Each of the third axis electrodes further comprises a plurality of second connecting lines to electrically connect the second sensing electrodes within one identical third axis electrodes and transmit a touch driving signal, and a touch receiving signal is received from each of the second axis electrodes. 
     Another preferred embodiment of the present invention provides a touch panel. The first sensing electrodes, the second sensing electrodes, and the second axis electrodes are made of an identical transparent conductive material. 
     Another preferred embodiment of the present invention provides a touch panel. An area of the first sensing electrodes and the second sensing electrodes is larger than an area of the second axis electrodes. 
     Another preferred embodiment of the present invention provides a touch panel. Each of the first axis electrodes is electrically isolated from each of the third axis electrodes. 
     Another preferred embodiment of the present invention provides a touch panel. At least one of the first axis electrodes is electrically connected to one adjacent third axis electrode. 
     These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram illustrating a conventional capacitive touch panel. 
         FIG. 2  is a schematic diagram illustrating a touch panel according to a first preferred embodiment of the present invention. 
         FIG. 3  is a schematic diagram illustrating first sensing electrodes, second sensing electrodes, and second axis electrodes of the touch panel according to the first preferred embodiment of the present invention. 
         FIG. 4  is a schematic diagram illustrating a touch panel according to a second preferred embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Please refer to  FIG. 2  and  FIG. 3 .  FIG. 2  is a schematic diagram illustrating a touch panel according to a first preferred embodiment of the present invention.  FIG. 3  is a schematic diagram illustrating first sensing electrodes, second sensing electrodes, and second axis electrodes of the touch panel according to the first preferred embodiment of the present invention. Please note that the figures are only for illustration and the figures may not be to scale. The scale may be further modified according to different design considerations. As shown in  FIG. 2  and  FIG. 3 , the first preferred embodiment of the present invention provides a touch panel  200 . The touch panel  200  includes a plurality of first axis electrodes  210  and a plurality of second axis electrodes  220 . The first axis electrodes  210  extend along a first direction X and the first axis electrodes  210  are disposed repeatedly along a second direction Y. Each of the first axis electrodes  210  includes a plurality of first sensing electrodes  211  disposed along the first direction X. The second axis electrodes  220  extend along the second direction Y and the second axis electrodes  220  are disposed repeatedly along the first direction X. Each of the second axis electrodes  220  surrounds the first sensing electrodes  211  disposed along the second direction Y. The first direction X is preferably perpendicular to the second direction Y, but not limited thereto. In this embodiment, each of the first axis electrodes  210  may further include a plurality of first connecting lines  212 . The first connecting lines  212  may be used to electrically connect the first sensing electrodes  211  within one identical first axis electrode  210  and transmit a touch driving signal TX. A touch receiving signal RX may be received from each of the second axis electrodes  220  by applying the touch driving signal TX to each of the first axis electrodes  210  so as to generate touch positioning effects. 
     In this embodiment, each of the second axis electrodes  220  has a plurality of hollow regions  220 H disposed along the second direction Y, and each of the first sensing electrodes  211  is disposed in the hollow region  220 H, but the present invention is not limited to this and the second axis electrode  220  may surround each of the first sensing electrodes  211  by other appropriate approaches. In other words, the second axis electrode  220  in this embodiment may be regarded as a reticulate electrode, but not limited thereto. Additionally, the touch panel  200  may further include a plurality of third axis electrodes  230  extending along the first direction X, and the third axis electrodes  230  are disposed repeatedly along the second direction Y. Each of the third axis electrodes  230  is disposed between two adjacent first axis electrodes  210 . In other words, each of the first axis electrodes  210  and each of the third axis electrodes  230  are disposed alternately along the second direction Y, but not limited thereto. Each of the third axis electrodes  230  includes a plurality of second sensing electrodes  231  disposed along the first direction X, and each of the second sensing electrodes  231  is disposed between two adjacent second axis electrodes  220 . An area of each of the first sensing electrodes  211  may be equal to an area of each of the second sensing electrodes  231 , but not limited thereto. A shape of each of the first sensing electrodes  211  may be identical to a shape of each of the second sensing electrodes  231 . For example, the first sensing electrode  211  and the second sensing electrode  231  may be rhombus electrodes, but not limited thereto. Preferably, the first sensing electrodes  211  and the second sensing electrodes  231  are disposed alternately so as to be disposed uniformly in the touch panel  200 . In other words, the second axis electrodes  220  are disposed in spacing between each of the first sensing electrodes  211  and each of the second sensing electrodes  231 . The first sensing electrodes  211 , the second sensing electrodes  231 , and the second axis electrodes  220  are preferably made of an identical transparent conductive material, such as indium tin oxide (ITO), indium zinc oxide (IZO), and aluminum zinc oxide (AZO), but not limited thereto. The related appearance defects such as visible electrodes may be accordingly overcome because the second sensing electrodes  231 , which are made of the same transparent conductive material, are disposed in the spacing between each of the first sensing electrodes  211  and each of the second sensing electrodes  231 . 
     More specifically, each of the third axis electrodes  230  in this embodiment may further include a plurality of second connecting lines  232 . The second connecting lines  232  may be used to electrically connect the second sensing electrodes  231  within one identical third axis electrode  230  and transmit the touch driving signal TX. The touch receiving signal RX may be received from each of the second axis electrodes  220  by applying the touch driving signal TX to each of the third axis electrodes  230 . Additionally, the touch panel  200  may further include a plurality of first signal lines  213 , a plurality of second signal lines  223 , and a plurality of third signal lines  233 . Each of the first signal lines  213  is electrically connected to the first axis electrode  210 , each of the second signal lines  223  is electrically connected to the second axis electrode  220 , and each of the third signal lines  233  is electrically connected to the third axis electrode  230 . Additionally, in this embodiment, each of the first signal lines  213  is separated from each of the third signal lines  233 , and each of the first axis electrodes  210  may be electrically isolated from each of the third axis electrodes  230  accordingly. In the touch panel  200  of this embodiment, the touch driving signals TX may be sequentially applied to each of the first axis electrodes  210  and each of the third axis electrodes  230  respectively via the first signal lines  213  and the third signal lines  233 . The touch driving signals TX may be sequentially applied to each of the first axis electrodes  210  and each of the third axis electrodes  230  by scanning, but not limited thereto. The touch receiving signals RX may be accordingly received from each of the second axis electrodes  220  via the second signal lines  223 . It is worth noting that the first sensing electrodes  211  and the second sensing electrodes  231 , which are disposed alternately in the touch panel  200 , are used to transmit the touch driving signals TX, and the second axis electrodes  220 , which are used to received the touch receiving signals RX, are disposed in the spacing between each of the first sensing electrodes  211  and the each of the second sensing electrodes  231 . Accordingly, the signal sensing density of the touch panel  200  may be enhanced without changing the areas of the first sensing electrodes  211  and the second sensing electrodes  231 . The touch sensing resolution may also be accordingly enhanced. In addition, an area of the first sensing electrodes  211  and the second sensing electrodes  231  is preferably larger than an area of the second axis electrodes  220  so as to lower a parasitic capacitance between the first sensing electrode  211  and the second axis electrode  220 , and lower a parasitic capacitance between the second sensing electrode  231  and the second axis electrode  220 . Accordingly, a little capacitive variation generated by touch objects (not shown) may be recognized more easily, and a signal to noise ratio (SNR) of the touch panel  200  may be increased. Positioning accuracy and touch sensitivity of the touch panel  200  may also be enhanced. 
     In this embodiment, the first sensing electrodes  211 , the second sensing electrodes  231 , and the second axis electrodes  220  are preferably formed by patterning an identical transparent conductive layer, but not limited thereto. The first connecting lines  212 , the second connecting lines  232 , the first signal lines  213 , the second signal liens  223 , and the third signal lines  233  preferably include metal materials, such as, aluminum (Al), copper (Cu), silver (Ag), chromium (Cr), titanium (Ti), molybdenum (Mo), a stack layer of the above-mentioned materials, or an alloy of the above-mentioned materials, but the present invention is not limited to this and other appropriate conductive materials may also be employed. Additionally, the first connecting lines  212  may partially overlap the second axis electrodes  220 , and the second connecting lines  232  may partially overlap the second axis electrodes  220 . An insulating pattern (not shown) is preferably disposed in a region wherein the first connecting lines  212  partially overlap the second axis electrodes  220  and in a region wherein the second connecting lines  232  partially overlap the second axis electrodes  220 . The insulating layer may be disposed between the first connecting lines  212  and the second axis electrodes  220  so as to electrically isolate the first connecting lines  212  and the second axis electrodes  220 , the insulating layer may be disposed between the second connecting lines  232  and the second axis electrodes  220  so as to electrically isolate the second connecting lines  232  and the second axis electrodes  220 , and the interference issue may be accordingly avoided. 
     The following description is based on different embodiments of the touch panel in the present invention. To simplify the description, the following description will focus on the differences among embodiments rather than similar parts. Furthermore, the same reference numbers are used in each description of embodiments for the convenience of cross-reference. 
     Please refer to  FIG. 4 .  FIG. 4  is a schematic diagram illustrating a touch panel  300  according to a second preferred embodiment of the present invention. As shown in  FIG. 4 , the touch panel  300  includes a plurality of first axis electrodes  210  and a plurality of second axis electrodes  220 . The difference between the touch panel  300  of this embodiment and the touch panel  200  of the first preferred embodiment is that, at least one of the first axis electrodes  210  is electrically connected to one adjacent third axis electrode  230  via the first signal line  213  and the third signal line  233 . Accordingly, the first axis electrode  210  and the third axis electrode  230 , which are electrically connected to each other, may be applied with the same touch driving signal TX. An amount of driving channels in a driving device (not shown) may be relatively decreased without affecting the performances such as the appearance quality improvement, the positioning accuracy enhancement, and the touch sensitivity enhancement mentioned above. The driving device may be accordingly simplified. Apart from the electrical connection between the first signal line  213  and the third signal line  233  in this embodiment and the method of applying the touch driving signal TX in this embodiment, the other components, allocations and material properties of this embodiment are similar to those of the first preferred embodiment detailed above and will not be redundantly described. 
     To summarize the above descriptions, in the touch panel of the present invention, the second axis electrodes, which are used to receive the touch receiving signals, are disposed in the spacing between the sensing electrodes, which are used to transmit the touch driving signals, so as to reduce the parasitic capacitance between the sensing electrodes and the second axis electrodes. The signal to noise ratio and the signal sensing density of the touch panel may be accordingly enhanced. Additionally, the signal sensing density of the touch panel is increased without changing the area of each of the sensing electrodes. The appearance quality may be enhanced by disposing the second axis electrodes in the spacing between the sensing electrodes. 
     Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention.