Patent Publication Number: US-9886144-B2

Title: Capacitive type touch sensor

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority to and the benefit of Korean Patent Application No. 10-2013-0126450, filed on Oct. 23, 2013, which is hereby incorporated by reference for all purposes as if fully set forth herein. 
     BACKGROUND 
     Field 
     Exemplary embodiments of the present invention relate to a new capacitive type touch sensor which can improve touch sensitivity. 
     Discussion of the Background 
     Recently, a digitizer, a touch screen, and the like are widely used, which can replace existing input devices such as a keyboard and a mouse by directly detecting a contact position of a user&#39;s hand or object. 
     Each of these devices has a touch sensor configured to detect a touch position. The touch sensor may include a capacitive type touch sensor, a resistive overlay type touch sensor, a photosensitive type touch sensor, etc. 
     Among these touch sensors, the capacitive type touch sensor may recognize a touch position by detecting a point at which capacitance has changed according to the contact of a user&#39;s hand or object. The capacitive type touch sensor has recently come into wide use because of its easy detection of a multi-touch and excellent accuracy. 
     The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form any part of the prior art nor what the prior art may suggest to a person of ordinary skill in the art. 
     SUMMARY 
     Exemplary embodiments of the present invention provide a capacitive type touch sensor with improve touch sensitivity. 
     Additional features of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. 
     An exemplary embodiment of the present invention discloses a capacitive type touch sensor, including a plurality of driving electrodes, a plurality of sensing electrodes disposed to overlap the driving electrodes, the sensing electrodes and the driving electrodes being spaced apart from each other, a driving unit configured to supply driving signals to the respective driving electrodes, and a sensing unit configured to detect sensing signals from the sensing electrodes, wherein the driving signals supplied by the driving unit include at least one of a first driving signal having a first frequency and a second driving signal having a second frequency different from the first frequency. 
     An exemplary embodiment of the present invention also discloses a method of operating a capacitive type touch sensor, the method including supplying driving signals to a plurality of driving electrodes wherein the driving signals include a first driving signal having a first frequency and a second driving signal having a second frequency different from the first frequency, detecting sensing signals from a plurality of sensing electrodes corresponding to the supplied driving signals, calculating capacitance at overlap portions of the plurality of driving electrodes and the plurality of sensing electrodes using the sensing signals, and recognizing a touch position using the calculated capacitance. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention, and together with the description serve to explain the principles of the invention. 
         FIG. 1  is a diagram illustrating a capacitive type touch sensor according to an exemplary embodiment of the present invention. 
         FIG. 2  is a diagram illustrating capacitances between driving electrodes and sensing electrodes, shown in  FIG. 1 . 
         FIG. 3  is a waveform diagram illustrating driving signals according to an exemplary embodiment of the present invention. 
         FIG. 4  is a diagram illustrating a sensing unit and a capacitance calculation unit according to the exemplary embodiment of the present invention. 
         FIG. 5  is a flowchart of a process to determine a touch position of a touch input via the capacitance calculation unit, according to exemplary embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     The invention is described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure is thorough, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the size and relative sizes of layers and regions may be exaggerated for clarity. Like reference numerals in the drawings denote like elements. 
     It will be understood that when an element or layer is referred to as being “on” or “connected to” another element or layer, it can be directly on or directly connected to the other element or layer, or intervening elements or layers may be present. In contrast, when an element or layer is referred to as being “directly on” or “directly connected to” another element or layer, there are no intervening elements or layers present. It will be understood that for the purposes of this disclosure, “at least one of X, Y, and Z” can be construed as X only, Y only, Z only, or any combination of two or more items X, Y, and Z (e.g., XYZ, XYY, YZ, ZZ). 
       FIG. 1  is a diagram illustrating a capacitive type touch sensor according to an exemplary embodiment of the present invention.  FIG. 2  is a diagram illustrating capacitances between driving electrodes and sensing electrodes, shown in  FIG. 1 . 
     Referring to  FIG. 1 , the touch sensor  1  according to this exemplary embodiment may include a driving electrode  10 , a sensing electrode  20 , a driving unit  30 , a sensing unit  40 , and a capacitance calculation unit  50 . 
     A plurality of driving electrodes  10  may be formed along the second direction (e.g., a Y-axis direction) extending in a first direction (e.g., an X-axis direction), wherein the second direction intersects the first direction. For example, the driving electrode  10  may include first to n-th driving electrodes Tx 1  to Txn, as illustrated in  FIG. 1 . 
     The sensing electrode  20  is arranged to be spaced apart from the driving electrode  10 , so that the driving electrode  10  and the sensing electrode  20  can be operated as a capacitive type touch sensor. 
     The sensing electrode  20  may be disposed to overlap the driving electrode  10 . Although it has been illustrated in  FIG. 1  that the driving electrode  10  is positioned below the sensing electrode  20 , the driving electrode  10  may be positioned above the sensing electrode  20 . 
     A plurality of sensing electrodes  20  may be formed along the first direction extending in the second direction. For example, the sensing electrode  20  may include first to m-th sensing electrodes Rx 1  to Rxm as illustrated in  FIG. 1 . 
     Through the arrangement of the driving electrode  10  and the sensing electrode  20 , mutual capacitance between the driving electrode  10  and the sensing electrode  20  is formed at a point where the driving electrode  10  and the sensing electrode  20  overlap each other. Each overlap point may operate as a sensing cell to implement touch recognition. For example, capacitance C 11  may be formed between the first driving electrode Tx 1  and the first sensing electrode Rx 1 , and capacitance Cmn may be formed between the n-th driving electrode Txn and the m-th sensing electrode Rxm. 
     The driving electrode  10  and the sensing electrode  20  may be formed of a transparent conductive material. However, the driving electrode  10  and the sensing electrode  20  may be formed of other conductive materials such as an opaque metal. For example, the driving electrode  10  and the sensing electrode  20  may be formed of indium tin oxide (ITO), indium zinc oxide (IZO), graphene, carbon nanotube, silver nanowires (AgNWs), or the like. 
     The driving unit  30  may supply driving signals S 1  to Sn to the driving electrode  10 . In this exemplary embodiment, the driving unit  30  may simultaneously supply the driving signals S 1  to Sn respectively to the plurality of driving electrodes Tx 1  to Txn. To this end, the driving unit  30  is electrically coupled to the plurality of driving electrodes Tx 1  to Txn. 
       FIG. 3  is a waveform diagram illustrating driving signals according to an exemplary embodiment of the present invention. 
     Referring to  FIG. 3 , each driving signal S 1  to Sn according to this exemplary embodiment may include at least one of a first driving signal P 1  having a first frequency f1 and a second driving signal P 2  having a second frequency f2. 
     For example, the driving signal S 1  supplied to the first driving electrode Tx 1  may include the first driving signal P 1  having the first frequency f1, and the driving signal S 2  supplied to the second driving electrode Tx 2  may include the second driving signal P 2  having the second frequency f2. In addition, each of the driving signal S 3  supplied to the third driving electrode Tx 3  and the driving signal Sn supplied to the n-th driving electrode Txn may include the first driving signal P 1  having the first frequency f1 and the second driving signal P 2  having the second frequency f2. 
     Accordingly, the driving electrode  10  can receive the driving signals S 1  to Sn having different frequencies for each driving period t 1  to tn. 
     In this exemplary embodiment, the driving unit  30  may supply the driving signals S 1  to Sn to the driving electrode  10  with reference to a predetermined code matrix Mcode. The code matrix Mcode may be stored in a separate memory (not shown). 
     The code matrix Mcode may include driving codes D set for each driving electrode Tx 1  to Txn and for each driving period t 1  to tn. For example, the code matrix Mcode may include the following n×n matrix. 
     
       
         
           
               
             
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     In other words, each row of the code matrix Mcode includes driving codes corresponding to the respective driving electrodes for each specific period, and each column of the code matrix Mcode includes driving codes corresponding to the respective driving periods for each specific driving electrode. 
     For example, an n-th row of the code matrix Mcode may include driving codes D(tn,Tx 1 ), D(tn,Tx 2 ), . . . , and D(tn,Txn) corresponding to the respective driving electrodes Tx 1  to Txn in a driving period tn. On the other hand, an n-th column of the code matrix Mcode may include driving codes D(t 1 ,Txn), D(t 2 ,Txn), . . . , and D(tn,Txn) corresponding to the respective driving periods t 1  to tn of the n-th driving electrode Txn. 
     Each driving code D included in the code matrix Mcode may have a value of A or −A. Here, the A may be set to a natural number. 
     In this exemplary embodiment, an embodiment of the code matrix Mcode may be shown as follows. 
     
       
         
           
               
             
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     The driving unit  30  may control the driving signals S 1  to Sn with reference to the driving code D of the code matrix Mcode. 
     For example, in a case where the specific driving code is set to A, the driving unit  30  may supply the first driving signal P 1  to a corresponding driving electrode for a corresponding driving period. In a case where the specific driving code is set to −A, the driving unit  30  may supply the second driving signal P 2  to a corresponding driving electrode for a corresponding driving period. 
     According the current exemplary embodiment, the driving codes in the first column of the code matrix Mcode for the first driving electrode Tx 1  during all the driving periods t 1  to tn have A. Therefore, the driving unit  30  may supply the first driving signal P 1  having the first frequency f1 to the first driving electrode Tx 1  during all the driving periods t 1  to tn. 
     In case of the second column of the code matrix Mcode for the second driving electrode Tx 2 , the driving codes during all the driving periods t 1  to tn have −A. Therefore, the driving unit  30  may supply the second driving signal P 2  having the second frequency f2 to the second driving electrode Tx 2  during all the driving periods t 1  to tn. 
     In case of the third column of the code matrix Mcode for the third driving electrode Tx 3 , the driving code has −A in the first driving period t 1 , has A in the second driving period t 2 , has −A in the third driving period t 3 , has A in the (tn−1)-th driving period tn−1, and has −A in the n-th driving period tn. 
     Accordingly, the driving unit  30  may supply the second driving signal P 2  to the third driving electrode Tx 3  during the first driving period t 1 , the first driving signal P 1  to the third driving electrode Tx 3  during the second driving period t 2 , the second driving signal P 2  to the third driving electrode Tx 3  during the third driving period t 3 , the first driving signal P 1  to the third driving electrode Tx 3  during the (n−1)-th driving period tn−1, and the second driving signal P 2  to the third driving electrode Tx 3  during the n-th driving period tn. 
     In case of the n-th column of the code matrix Mcode for the n-th driving electrode Txn, the driving code has A in the first driving period t 1 , has −A in the second driving period t 2 , has A in the third driving period t 3 , has −A in the (n−1)-th driving period tn−1, and has −A in the n-th driving period tn. 
     Accordingly, the driving unit  30  may supply the first driving signal P 1  to the n-th driving electrode Txn during the first driving period t 1 , the second driving signal P 2  to the n-th driving electrode Txn during the second driving period t 2 , the first driving signal P 1  to the n-th driving electrode Txn during the third driving period t 3 , the second driving signal P 2  to the n-th driving electrode Txn, and the second driving signal P 2  to the n-th driving electrode Txn during the n-th driving period tn. 
     In an exemplary embodiment, in order to easily calculate the inverse matrix of the code matrix Mcode, A may be set to 1. 
     In this exemplary embodiment, the code matrix Mcode may be shown as follows. 
     
       
         
           
               
             
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     The sensing unit  40  may detect sensing signals E 1  to Em from the sensing electrodes  20 . 
     According to an exemplary embodiment, the sensing unit  40  may detect sensing signals E 1  to Em from the respective sensing electrodes Rx 1  to Rxm for each driving period t 1  to tn. 
     The capacitance calculation unit  50  may calculate capacitances C 11  to Cmn between the driving electrode  10  and the sensing electrode  20 , from the sensing signals E 1  to Em detected by the sensing unit  40 , and the code matrix Mcode. 
       FIG. 4  is a diagram illustrating the sensing unit and the capacitance calculation unit according to the exemplary embodiment of the present invention.  FIG. 5  is a flowchart of a process to determine a touch position of a touch input via the capacitance calculation unit, according to exemplary embodiments. 
     Referring to  FIG. 4 , the sensing unit  40  according to this exemplary embodiment may include filtering unit  43  configure to filter the sensing signals E 1  to Em from the sensing electrode  20  into first sensing signals G 11 , G 21 , . . . , Gm−11, and Gm 1  having a first frequency f1 and second sensing signals G 12 , G 22 , . . . , Gm−12, and Gm 2  having a second frequency f2, respectively. 
     More specifically, the filtering unit  43  may separate the sensing signals E 1  to Em from the respective sensing electrodes Rx 1  to Rxm during each driving period t 1  to tn, into the first sensing signals G 11 , G 21 , . . . , Gm−11, and Gm 1  and the second sensing signals G 12 , G 22 , . . . , Gm−12, and Gm 2 , respectively. 
     For example, the sensing signal E 1  from the first sensing electrode Rx 1  may be separated by the filtering unit  43  into the first sensing signal G 11  having the first frequency f1 and the second sensing signal G 12  having the second frequency f2. The sensing signal E 2  from the second sensing electrode Rx 2  may be separated, by the filtering unit  43 , into the first sensing signal G 21  having the first frequency f1 and the second sensing signal G 22  having the second frequency f2. The sensing signal Em from the m-th sensing electrode Rxm may be separated, by the filtering unit  43 , into the first sensing signal Gm 1  having the first frequency f1 and the second sensing signal Gm 2  having the second frequency f2. 
     The sensing unit  40  according to this exemplary embodiment may further include an amplifying unit  41  configured to amplifying the sensing signals E 1  to Em from the sensing electrode  20 . 
     In this exemplary embodiment, the amplifying unit  41  may amplify and transfer the sensing signals E 1  to Em to the filtering unit  43 . 
     Referring to  FIG. 4 , the capacitance calculation unit  50  according to this exemplary embodiment may further include a first calculation unit  51 , a second calculation unit  53 , and a third calculation unit  55 . 
     The first calculation unit  51  may calculate and output representative values Vr 11 ( t ), Vr 21 ( t ), . . . , Vrm−11(t), and Vrm 1 ( t ) of the first sensing signals G 11 , G 21 , . . . , Gm−11, and Gm 1 , and representative values Vr 12 ( t ), Vr 22 ( t ), . . . , Vrm−12(t), and Vrm 2 ( t ) of the second sensing signals G 12 , G 22 , . . . , Gm−12, and Gm 2 , respectively for each driving period. 
     In this exemplary embodiment, the representative value may be determined by the root-mean-square value of the first sensing signal G 11 , G 21 , . . . , Gm−11, or Gm 1  and the second sensing signal G 12 , G 22 , . . . , Gm−12, or Gm 2 , etc. 
     For example, the first sensing signal Gm 1  from the m-th sensing electrode Rxm, may be calculated by the first calculation unit  51  into a representative value Vrm 1 ( t ) for each driving period t 1  to tn. 
     Specifically, the first calculation unit  51  may calculate a representative value Vrm 1 ( t   1 ) of the first sensing signal Gm 1  during the first driving period t 1 , a representative value Vrm 1 ( t   2 ) of the first sensing signal Gm 1  during the second driving period, . . . , and a representative value Vrm 1 ( tn ) of the first sensing signal Gm 1  during the n-th driving period tn. As a result, the first calculation unit  51  may calculate the representative value Vrm 1 ( t   1 ) to Vrm 1 ( tn ) of the first sensing signal Gm 1  for each driving period. 
     Accordingly, the second sensing signal Gm 2  from the m-th sensing electrode Rxm, may be calculated by the first calculation unit  51  into a representative value Vrm 2 ( t ) for each driving period. 
     Specifically, the first calculation unit  51  may calculate a representative value Vrm 2 ( t   1 ) of the second sensing signal Gm 2  during the first driving period t 1 , a representative value Vrm 2 ( t   2 ) of the second sensing signal Gm 2  during the second period t 2 , . . . , and a representative value Vrm 2 ( tn ) of the second sensing signal Gm 2  during the n-th driving period tn. As a result, the first calculation unit  51  may calculate the representative value Vrm 2 ( t   1 ) to Vrm 2 ( tn ) of the second sensing signal Gm 2  for each driving period. 
     The representative values Vr 11 ( t ) to Vrm−11(t) of the other first sensing signals G 11  to Gm−11 for each driving period and the representative values Vr 12 ( t ) to Vrm−12(t) of the other second sensing signals G 12  to Gm−12 for each driving period may also be calculated in the same manner. 
     In this exemplary embodiment, in order to facilitate the calculation, the first calculation unit  51  may control at least one of the representative values Vr 11 ( t ), Vr 12 ( t ), . . . , Vrm−11(t), and Vrm 1 ( t ) of the first sensing signals G 11 , G 21 , . . . , Gm−11, and Gm 1 , and the representative values Vr 12 ( t ), Vr 22 ( t ), . . . , Vrm−12(t), and Vrm 2 ( t ) of the second sensing signals G 12 , G 22 , . . . , Gm−12, and Gm 2 . 
     The second calculation unit  53  may calculate output values Ox 1 ( t ), Ox 2 ( t ), . . . , Oxm−1(t), and Oxm(t) of the sensing electrodes Rx 1  to Rxm for each driving period by subtracting the representative values Vr 12 ( t ), Vr 22 ( t ), . . . , Vrm−12(t), and Vrm 2 ( t ) of the second sensing signals G 12 , G 22 , . . . , Gm−12, and Gm 2  from the representative values Vr 11 ( t ), Vr 21 ( t ), . . . , Vrm−11(t), and Vrm 1 ( t ) of the first sensing signals G 11 , G 21 , . . . , Gm−11, and Gm 1 , respectively for each driving period. 
     In other words, the output values Ox 1 ( t ), Ox 2 ( t ), . . . , Oxm−1(t), and Oxm(t) of the sensing electrodes Rx 1  to Rxm for each driving period may be calculated from representative values of the first sensing signals and the second sensing signals, corresponding to the same sensing electrode. 
     For example, the output value Ox 1 ( t ) of the first sensing electrode Rx 1  for each driving period may be calculated from the difference between the representative value Vr 11 ( t ) of the first sensing signal G 11  and the representative value Vr 12 ( t ) of the second sensing signal G 12  from the first sensing electrode Rx 1 . 
     In similar way, the output value Oxm(t) of the m-th sensing electrode Rxm for each driving period may be calculated from the difference between the representative value Vrm 1 ( t ) of the first sensing signal Gm 1  and the representative value Vrm 2 ( t ) of the second sensing signal Gm 2  from the m-th sensing electrode Rxm. 
     The output values Ox 1 ( t ), Ox 2 ( t ), . . . , Oxm−1(t), and Oxm(t) of the sensing electrodes Rx 1  to Rxm for each driving period may be calculated between representative values corresponding to the same sensing electrode. 
     For example, the output values Ox 1 ( tn ), Ox 2 ( tn ), . . . , Oxm−1(tn), and Oxm(tn) during the n-th driving period tn may be respectively calculated from the differences between the representative values Vr 11 ( tn ), Vr 21 ( tn ), . . . , Vrm−11(tn), and Vrm 1  ( tn ) of the first sensing signals G 11 , G 21 , Gm−11, and Gm 1  and the representative values Vr 12 ( tn ), Vr 22 ( tn ), . . . , Vrm−12(tn), and Vrm 2 ( tn ) of the second sensing signals G 12 , G 22 , . . . , Gm−12, and Gm 2 , during the n-th driving period tn. 
     Therefore, the output value Oxm(t 1 ) to Oxm(tn) of the m-th sensing electrode Rxm for each driving period may be calculated as shown in the following Table 1. 
     
       
         
           
               
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                   
                 Representative 
                 Representative 
                   
               
               
                   
                 value of first 
                 value of second 
               
               
                   
                 sensing signal 
                 sensing signal 
                 Output value of 
               
               
                 Driving 
                 Gm1 for each 
                 Gm2 for each 
                 n-th sensing electrode 
               
               
                 period 
                 driving period 
                 driving period 
                 Rxn for each driving period 
               
               
                   
               
             
            
               
                 t1 
                 Vrm1(t1) 
                 Vrm2(t1) 
                 Oxm(t1) = Vrm1(t1) − 
               
               
                   
                   
                   
                 Vrm2(t1) 
               
               
                 t2 
                 Vrm1(t2) 
                 Vrm2(t2) 
                 Oxm(t2) = Vrm1(t2) − 
               
               
                   
                   
                   
                 Vrm2(t2) 
               
               
                 t3 
                 Vrm1(t3) 
                 Vrm2(t3) 
                 Oxm(t3) = Vrm1(t3) − 
               
               
                   
                   
                   
                 Vrm2(t3) 
               
               
                 — 
                 — 
                 — 
                 — 
               
               
                 tn − 1 
                 Vrm1(tn − 1) 
                 Vrm2(tn − 1) 
                 Oxm(tn − 1) = 
               
               
                   
                   
                   
                 Vrm1(tn − 1) − Vrm2(tn − 1) 
               
               
                 tn 
                 Vrm1(tn) 
                 Vrm2(tn) 
                 Oxm(tn) = Vrm1(tn) − 
               
               
                   
                   
                   
                 Vrm2(tn) 
               
               
                   
               
            
           
         
       
     
     The output values Ox 1 ( t ) to Oxm−1(t) of the other sensing electrodes Rx 1  to Rxm−1 for each driving period may also be calculated in the same manner. 
     The third calculation unit  55  may form an output matrix Mo from the values calculated in the second calculation unit  53 , and calculate capacitances between the driving electrode  10  and the sensing electrode  20  through an operation of the output matrix Mo and the code matrix Mcode. 
     According to an exemplary embodiment, the third calculation unit  55  may form the output matrix for the sensing electrode  20 , from the output values Ox 1 ( t ), Ox 2 ( t ), . . . , Oxm−1(t), and Oxm(t). 
     Therefore, the output matrix Mo of a specific sensing electrode may have following generalized form of n×1 matrix. 
     
       
         
           
               
             
               [ 
               
                 
                   
                     
                       Ox 
                       ⁡ 
                       
                         ( 
                         
                           t 
                           ⁢ 
                           
                               
                           
                           ⁢ 
                           1 
                         
                         ) 
                       
                     
                   
                 
                 
                   
                     
                       Ox 
                       ⁡ 
                       
                         ( 
                         
                           t 
                           ⁢ 
                           
                               
                           
                           ⁢ 
                           2 
                         
                         ) 
                       
                     
                   
                 
                 
                   
                     
                       Ox 
                       ⁡ 
                       
                         ( 
                         
                           t 
                           ⁢ 
                           
                               
                           
                           ⁢ 
                           3 
                         
                         ) 
                       
                     
                   
                 
                 
                   
                     ⋮ 
                   
                 
                 
                   
                     
                       Ox 
                       ⁡ 
                       
                         ( 
                         
                           tn 
                           - 
                           1 
                         
                         ) 
                       
                     
                   
                 
                 
                   
                     
                       Ox 
                       ⁡ 
                       
                         ( 
                         tn 
                         ) 
                       
                     
                   
                 
               
               ] 
             
           
         
       
     
     For example, the output matrix Mom of the m-th sensing electrode Rxm may be shown as the following n×1 matrix. 
     
       
         
           
               
             
               [ 
               
                 
                   
                     
                       Oxm 
                       ⁡ 
                       
                         ( 
                         
                           t 
                           ⁢ 
                           
                               
                           
                           ⁢ 
                           1 
                         
                         ) 
                       
                     
                   
                 
                 
                   
                     
                       Oxm 
                       ⁡ 
                       
                         ( 
                         
                           t 
                           ⁢ 
                           
                               
                           
                           ⁢ 
                           2 
                         
                         ) 
                       
                     
                   
                 
                 
                   
                     
                       Oxm 
                       ⁡ 
                       
                         ( 
                         
                           t 
                           ⁢ 
                           
                               
                           
                           ⁢ 
                           3 
                         
                         ) 
                       
                     
                   
                 
                 
                   
                     ⋮ 
                   
                 
                 
                   
                     
                       Oxm 
                       ⁡ 
                       
                         ( 
                         
                           tn 
                           - 
                           1 
                         
                         ) 
                       
                     
                   
                 
                 
                   
                     
                       Oxm 
                       ⁡ 
                       
                         ( 
                         tn 
                         ) 
                       
                     
                   
                 
               
               ] 
             
           
         
       
     
     The output matrices Mo 1  to Mom−1 of the other sensing electrodes Rx 1  to Rxm−1 may also be configured in the same manner. 
     The third calculation unit  55  may calculate capacitances between the driving electrode  10  and the sensing electrode  20  through following operations of the code matrix Mcode and the output matrices Mo 1 , Mo 2 , . . . , Mom−1, and Mom. 
     The capacitances between the driving electrode  10  and the sensing electrode  20  may be respectively formed at overlap portions of the driving electrode  10  and the sensing electrode  20 . Therefore, the capacitances between a specific sensing electrode and a plurality of driving electrodes Tx 1  to Txn may have following generalized form of n×1 matrix Mc. 
     
       
         
           
               
             
               [ 
               
                 
                   
                     
                       C 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       1 
                     
                   
                 
                 
                   
                     
                       C 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       2 
                     
                   
                 
                 
                   
                     
                       C 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       3 
                     
                   
                 
                 
                   
                     ⋮ 
                   
                 
                 
                   
                     
                       Cn 
                       - 
                       1 
                     
                   
                 
                 
                   
                     Cn 
                   
                 
               
               ] 
             
           
         
       
     
     The capacitances C 1 , C 2 , C 3 , . . . , Cn−1, and Cn represent capacitance between the specific sensing electrode and a first driving electrode Tx 1 , a second driving electrode Tx 2 , a third driving electrode Tx 3 , an (n−1)-th driving electrode Txn−1, and an n-th driving electrode Txn, respectively. 
     For example, the m-th sensing electrode Rxm may have capacitances Cm 1 , Cm 2 , Cm 3 , . . . , Cm−1, and Cmn at overlap portions of the m-th sensing electrode Rxm and the first to n-th driving electrodes Tx 1  to Txn, respectively. 
     Accordingly, the capacitances Cm 1 , Cm 2 , Cm 3 , . . . , Cm−1, and Cmn between the m-th sensing electrode Rxm and the plurality of driving electrodes Tx 1  to Txn may be shown as the following n×1 matrix Mcm. 
     
       
         
           
               
             
               [ 
               
                 
                   
                     
                       Cm 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       1 
                     
                   
                 
                 
                   
                     
                       C 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       m 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       2 
                     
                   
                 
                 
                   
                     
                       Cm 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       3 
                     
                   
                 
                 
                   
                     ⋮ 
                   
                 
                 
                   
                     
                       Cmn 
                       - 
                       1 
                     
                   
                 
                 
                   
                     Cmn 
                   
                 
               
               ] 
             
           
         
       
     
     The capacitances between the other sensing electrodes Rx 1  to Rxm−1 and the driving electrodes Tx 1  to Txn may also be shown as matrices Mc 1  to Mcm−1 in the same manner. 
     In this exemplary embodiment, the output matrix Mo of the specific sensing electrode, the code matrix Mcode and the matrix Mc configured with the capacitances between the specific sensing electrode and the driving electrodes Tx 1  to Txn may satisfy the following relation expression.
 
 Mo=M code× Mc   (Formula 1)
 
     Relation Expression 1 may be modified as follows.
 
 Mc=M code −1   ×Mo   (Formula 2)
 
     In other words, the capacitances between the sensing electrode  20  and the driving electrode  10  may be calculated from the multiplication of the inverse matrix of the code matrix Mcode and the output matrix Mo. 
     For example, the capacitances Cm 1 , Cm 2 , Cm 3 , . . . , Cm−1, and Cmn between the m-th sensing electrode Rxm and the driving electrodes Tx 1  to Txn may be calculated from the multiplication of the inverse matrix of the code matrix Mcode and the output matrix Mom. This may be calculated through the following relation expression.
 
 Mcm=M code −1   ×Mom   (Formula 3)
 
     In this case, Formula 3 may be shown as following formula 4. 
     
       
         
           
             
               
                 
                   
                     
 
                   
                   ⁢ 
                   
                     
                       
                         
                           
                             
                               
                                 [ 
                                 
                                   
                                     
                                       
                                         Cm 
                                         ⁢ 
                                         
                                             
                                         
                                         ⁢ 
                                         1 
                                       
                                     
                                   
                                   
                                     
                                       
                                         C 
                                         ⁢ 
                                         
                                             
                                         
                                         ⁢ 
                                         m 
                                         ⁢ 
                                         
                                             
                                         
                                         ⁢ 
                                         2 
                                       
                                     
                                   
                                   
                                     
                                       
                                         Cm 
                                         ⁢ 
                                         
                                             
                                         
                                         ⁢ 
                                         3 
                                       
                                     
                                   
                                   
                                     
                                       ⋮ 
                                     
                                   
                                   
                                     
                                       
                                         Cmn 
                                         - 
                                         1 
                                       
                                     
                                   
                                   
                                     
                                       Cmn 
                                     
                                   
                                 
                                 ] 
                               
                               = 
                                 
                               ⁢ 
                               
                                 [ 
                                 
                                   
                                     
                                       
                                         D 
                                         ⁡ 
                                         
                                           ( 
                                           
                                             
                                               t 
                                               ⁢ 
                                               
                                                   
                                               
                                               ⁢ 
                                               1 
                                             
                                             , 
                                             
                                               Tx 
                                               ⁢ 
                                               
                                                   
                                               
                                               ⁢ 
                                               1 
                                             
                                           
                                           ) 
                                         
                                       
                                     
                                     
                                       
                                         D 
                                         ⁡ 
                                         
                                           ( 
                                           
                                             
                                               t 
                                               ⁢ 
                                               
                                                   
                                               
                                               ⁢ 
                                               1 
                                             
                                             , 
                                             
                                               Tx 
                                               ⁢ 
                                               
                                                   
                                               
                                               ⁢ 
                                               2 
                                             
                                           
                                           ) 
                                         
                                       
                                     
                                     
                                       
                                         D 
                                         ⁡ 
                                         
                                           ( 
                                           
                                             
                                               t 
                                               ⁢ 
                                               
                                                   
                                               
                                               ⁢ 
                                               1 
                                             
                                             , 
                                             
                                               Tx 
                                               ⁢ 
                                               
                                                   
                                               
                                               ⁢ 
                                               3 
                                             
                                           
                                           ) 
                                         
                                       
                                     
                                     
                                       ⋯ 
                                     
                                     
                                       
                                         D 
                                         ⁡ 
                                         
                                           ( 
                                           
                                             
                                               t 
                                               ⁢ 
                                               
                                                   
                                               
                                               ⁢ 
                                               1 
                                             
                                             , 
                                             Txn 
                                           
                                           ) 
                                         
                                       
                                     
                                   
                                   
                                     
                                       
                                         D 
                                         ⁡ 
                                         
                                           ( 
                                           
                                             
                                               t 
                                               ⁢ 
                                               
                                                   
                                               
                                               ⁢ 
                                               2 
                                             
                                             , 
                                             
                                               Tx 
                                               ⁢ 
                                               
                                                   
                                               
                                               ⁢ 
                                               1 
                                             
                                           
                                           ) 
                                         
                                       
                                     
                                     
                                       
                                         D 
                                         ⁡ 
                                         
                                           ( 
                                           
                                             
                                               t 
                                               ⁢ 
                                               
                                                   
                                               
                                               ⁢ 
                                               2 
                                             
                                             , 
                                             
                                               Tx 
                                               ⁢ 
                                               
                                                   
                                               
                                               ⁢ 
                                               2 
                                             
                                           
                                           ) 
                                         
                                       
                                     
                                     
                                       
                                         D 
                                         ⁡ 
                                         
                                           ( 
                                           
                                             
                                               t 
                                               ⁢ 
                                               
                                                   
                                               
                                               ⁢ 
                                               2 
                                             
                                             , 
                                             
                                               Tx 
                                               ⁢ 
                                               
                                                   
                                               
                                               ⁢ 
                                               3 
                                             
                                           
                                           ) 
                                         
                                       
                                     
                                     
                                       ⋯ 
                                     
                                     
                                       
                                         D 
                                         ⁡ 
                                         
                                           ( 
                                           
                                             
                                               t 
                                               ⁢ 
                                               
                                                   
                                               
                                               ⁢ 
                                               2 
                                             
                                             , 
                                             Txn 
                                           
                                           ) 
                                         
                                       
                                     
                                   
                                   
                                     
                                       
                                         D 
                                         ⁡ 
                                         
                                           ( 
                                           
                                             
                                               t 
                                               ⁢ 
                                               
                                                   
                                               
                                               ⁢ 
                                               3 
                                             
                                             , 
                                             
                                               Tx 
                                               ⁢ 
                                               
                                                   
                                               
                                               ⁢ 
                                               1 
                                             
                                           
                                           ) 
                                         
                                       
                                     
                                     
                                       
                                         D 
                                         ⁡ 
                                         
                                           ( 
                                           
                                             
                                               t 
                                               ⁢ 
                                               
                                                   
                                               
                                               ⁢ 
                                               3 
                                             
                                             , 
                                             
                                               Tx 
                                               ⁢ 
                                               
                                                   
                                               
                                               ⁢ 
                                               2 
                                             
                                           
                                           ) 
                                         
                                       
                                     
                                     
                                       
                                         D 
                                         ⁡ 
                                         
                                           ( 
                                           
                                             
                                               t 
                                               ⁢ 
                                               
                                                   
                                               
                                               ⁢ 
                                               3 
                                             
                                             , 
                                             
                                               Tx 
                                               ⁢ 
                                               
                                                   
                                               
                                               ⁢ 
                                               3 
                                             
                                           
                                           ) 
                                         
                                       
                                     
                                     
                                       ⋯ 
                                     
                                     
                                       
                                         D 
                                         ⁡ 
                                         
                                           ( 
                                           
                                             
                                               t 
                                               ⁢ 
                                               
                                                   
                                               
                                               ⁢ 
                                               3 
                                             
                                             , 
                                             Txn 
                                           
                                           ) 
                                         
                                       
                                     
                                   
                                   
                                     
                                       ⋮ 
                                     
                                     
                                       ⋮ 
                                     
                                     
                                       ⋮ 
                                     
                                     
                                       
                                           
                                       
                                     
                                     
                                       ⋮ 
                                     
                                   
                                   
                                     
                                       
                                         D 
                                         ⁡ 
                                         
                                           ( 
                                           
                                             
                                               tn 
                                               - 
                                               1 
                                             
                                             , 
                                             
                                               Tx 
                                               ⁢ 
                                               
                                                   
                                               
                                               ⁢ 
                                               1 
                                             
                                           
                                           ) 
                                         
                                       
                                     
                                     
                                       
                                         D 
                                         ⁡ 
                                         
                                           ( 
                                           
                                             
                                               tn 
                                               - 
                                               1 
                                             
                                             , 
                                             
                                               Tx 
                                               ⁢ 
                                               
                                                   
                                               
                                               ⁢ 
                                               2 
                                             
                                           
                                           ) 
                                         
                                       
                                     
                                     
                                       
                                         D 
                                         ⁡ 
                                         
                                           ( 
                                           
                                             
                                               tn 
                                               - 
                                               1 
                                             
                                             , 
                                             
                                               Tx 
                                               ⁢ 
                                               
                                                   
                                               
                                               ⁢ 
                                               3 
                                             
                                           
                                           ) 
                                         
                                       
                                     
                                     
                                       ⋯ 
                                     
                                     
                                       
                                         D 
                                         ⁡ 
                                         
                                           ( 
                                           
                                             
                                               tn 
                                               - 
                                               1 
                                             
                                             , 
                                             Txn 
                                           
                                           ) 
                                         
                                       
                                     
                                   
                                   
                                     
                                       
                                         D 
                                         ⁡ 
                                         
                                           ( 
                                           
                                             tn 
                                             , 
                                             
                                               Tx 
                                               ⁢ 
                                               
                                                   
                                               
                                               ⁢ 
                                               1 
                                             
                                           
                                           ) 
                                         
                                       
                                     
                                     
                                       
                                         D 
                                         ⁡ 
                                         
                                           ( 
                                           
                                             tn 
                                             , 
                                             
                                               Tx 
                                               ⁢ 
                                               
                                                   
                                               
                                               ⁢ 
                                               2 
                                             
                                           
                                           ) 
                                         
                                       
                                     
                                     
                                       
                                         D 
                                         ⁡ 
                                         
                                           ( 
                                           
                                             tn 
                                             , 
                                             
                                               Tx 
                                               ⁢ 
                                               
                                                   
                                               
                                               ⁢ 
                                               3 
                                             
                                           
                                           ) 
                                         
                                       
                                     
                                     
                                       ⋯ 
                                     
                                     
                                       
                                         D 
                                         ⁡ 
                                         
                                           ( 
                                           
                                             tn 
                                             , 
                                             Txn 
                                           
                                           ) 
                                         
                                       
                                     
                                   
                                 
                                 ] 
                               
                             
                           
                         
                         
                           
                             
                                 
                               ⁢ 
                               
                                 
                                   [ 
                                   
                                     
                                       
                                         
                                           Oxm 
                                           ⁡ 
                                           
                                             ( 
                                             
                                               t 
                                               ⁢ 
                                               
                                                   
                                               
                                               ⁢ 
                                               1 
                                             
                                             ) 
                                           
                                         
                                       
                                     
                                     
                                       
                                         
                                           Oxm 
                                           ⁡ 
                                           
                                             ( 
                                             
                                               t 
                                               ⁢ 
                                               
                                                   
                                               
                                               ⁢ 
                                               2 
                                             
                                             ) 
                                           
                                         
                                       
                                     
                                     
                                       
                                         
                                           Oxm 
                                           ⁡ 
                                           
                                             ( 
                                             
                                               t 
                                               ⁢ 
                                               
                                                   
                                               
                                               ⁢ 
                                               3 
                                             
                                             ) 
                                           
                                         
                                       
                                     
                                     
                                       
                                         ⋮ 
                                       
                                     
                                     
                                       
                                         
                                           Oxm 
                                           ⁡ 
                                           
                                             ( 
                                             
                                               tn 
                                               - 
                                               1 
                                             
                                             ) 
                                           
                                         
                                       
                                     
                                     
                                       
                                         
                                           Oxm 
                                           ⁡ 
                                           
                                             ( 
                                             tn 
                                             ) 
                                           
                                         
                                       
                                     
                                   
                                   ] 
                                 
                                 . 
                               
                             
                           
                         
                       
                       
                         - 
                         1 
                       
                     
                     × 
                   
                 
               
               
                 
                   Formula 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   4 
                 
               
             
           
         
       
     
     Therefore, the third calculation unit  55  may calculate capacitances Cm 1  to Cmn between the m-th sensing electrode Rxm and the driving electrodes Tx 1  to Txn, respective, using Formula 4. 
     The capacitances C 11  to Cm−1n between the other sensing electrodes Rx 1  to Rxm−1 and the driving electrodes Tx 1  to Txn may also be calculated in the same manner. 
     The touch sensor  1  according to this exemplary embodiment may further include a touch detection unit  60  configured to detect a touch position, using the capacitance calculated by the capacitance calculation unit  50 . 
     In this exemplary embodiment, the touch detection unit  60  may detect a touch position by recognizing a change in capacitance. 
     For example, in a case where the capacitance Cm 2  among the capacitances Cm 1  to Cmn has a value that is lower than the other capacitances or a specific reference value, the touch detection unit  60  may recognize a touch at the overlap portion of the m-th sensing electrode Rxm and the second driving electrode Tx 2 . 
     In a similar manner, a touch position generated in the other sensing electrodes Rx 1  to Rxm−1 may also be recognized. 
     According to an exemplary embodiment, the code matrix Mcode, the output matrix Mo, and matrix Mc, may be transposes of the respective matrices. 
     The touch sensor  1  according to this exemplary embodiment simultaneously supplies driving signals S 1  to Sn having different frequencies, and the touch sensitivity of the touch sensor  1  can be improved, compared to the related art touch sensor which supplies a driving signal sequentially. 
     As described above, according to the present invention, it is possible to provide a new capacitive touch sensor with improve touch sensitivity. 
     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.