Patent Publication Number: US-9898136-B2

Title: Method for specifying touched position determined by first coordinate along first signal line and second coordinate along second signal line, and circuit for specifying the touched position

Description:
This application is a Divisional of copending application Ser. No. 14/129,068, filed on Dec. 23, 2013, which was filed as PCT International Application No. PCT/JP2012/059823 on Apr. 4, 2012, which claims the benefit under 35 U.S.C. §119(a) to Patent Application No. JP2011-142164, filed in Japan on Jun. 27, 2011, all of which are hereby expressly incorporated by reference into the present application. 
    
    
     TECHNICAL FIELD 
     The present invention is related to a capacitance distribution detection method, a capacitance distribution detection circuit, a touch sensor system, and an information input/output device, each of which detects a distribution of capacitance of a plurality of capacitors that are each formed at intersections of a plurality of first signal lines with a plurality of second signal lines. 
     BACKGROUND ART 
     Patent Literature 1 discloses a capacitance distribution detection circuit that detects a distribution of capacitance of a plurality of capacitors, which capacitors are each formed at intersections of a plurality of first signal lines with a plurality of second signal lines. As shown in FIG. 1 of Patent Literature 1, a positional relationship of (i) drive lines for driving the touch panel with (ii) sense lines for reading out signals from the touch panel is fixed with respect to the touch panel. 
       FIG. 12  is a block diagram illustrating a configuration of a conventional touch sensor system  91 .  FIG. 13  is a schematic view illustrating a configuration of a touch panel  93  provided in the touch sensor system  91 . The touch sensor system  91  includes the touch panel  93  and a capacitance distribution detection circuit  92 . The touch panel  93  includes drive lines HL 1  to HLM arranged parallel to each other in a horizontal direction, sense lines VL 1  to VLM arranged parallel to each other in a vertical direction, and capacitors C 11  to CMM each formed at intersections of the drive lines HL 1  to HLM with the sense lines VL 1  to VLM. 
     The capacitance distribution detection circuit  92  includes a driver  95 . The driver  95  applies a voltage to the drive lines HL 1  to HLM in accordance with a code sequence, to drive the capacitors C 11  to CMM. The capacitance distribution detection circuit  92  includes a sense amplifier  96 . The sense amplifier  96  reads out, via the sense lines VL 1  to VLM, a linear sum of voltages corresponding to the capacitors C 11  to CMM driven by the driver  95 , and supplies this linear sum of voltages to an A/D converter  98 . The A/D converter  98  converts, from analog to digital, the linear sum of voltages corresponding to the capacitors, read out via the sense lines VL 1  to VLM, and supplies the converted linear sum to a capacitance distribution calculation section  99 . 
     The capacitance distribution calculation section  99  calculates a capacitance distribution on the touch panel  93  based on (i) the linear sum of voltages corresponding to the capacitors, supplied from the A/D converter  98 , and (ii) the code sequence, and supplies the calculation result to a touch recognition section  90 . The touch recognition section  90  recognizes a position touched on the touch panel  93  based on the capacitance distribution supplied from the capacitance distribution calculation section  99 . 
     The capacitance distribution detection circuit  92  includes a timing generator  97 . The timing generator  97  generates a signal specifying an operation of the driver  95 , a signal specifying an operation of the sense amplifier  96 , and a signal specifying an operation of the A/D converter  98 , and supplies these signals to the driver  95 , the sense amplifier  96 , and the A/D converter  98 , respectively. 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1 
     U.S. Pat. No. 7,812,827 (Oct. 12, 2010) 
     SUMMARY OF INVENTION 
     Technical Problem 
     The following description considers a case in which entry is received via a touch panel  93  of a touch sensor system  91  with an electrically conductive pen.  FIG. 14  is a view describing phantom noise generated in the touch sensor system  91 . It is preferable that a tip of the electrically conductive pen is sharp having a diameter of around 1 mm to 4 mm, for preventing deterioration in the sense of use. Moreover, for easy writing, it is preferable that the pen can be used in a state in which a palm of the hand is placed on a large-sized touch panel. 
     In the present specification, a region in which a hand holding the electrically conductive pen for input is placed on the touch panel is called a “hand placing region”. 
     By fabricating the capacitance distribution detection circuit  92  so that a signal read out from a capacitor disposed in the hand placing region HDR (illustrated in  FIG. 14 ) via a sense line is not received, it should be possible to input an entry with a pen at a pen input position P in a state in which the hand holding the electrically conductive pen for input is placed on the touch panel. 
     In the foregoing setting, a touch signal of a pen tip of the electrically conductive pen for input is extremely weaker than a touch signal of the hand placed on the touch panel, which hand holds the electrically conductive pen for input, and has a difference in SN ratio of around 10-fold to 20-fold. 
     Furthermore, a human body receives electromagnetic noise that exists in space, and this electromagnetic noise received by the human body from the space is inputted into the touch panel through the hand holding the electrically conductive pen for input. The electromagnetic noise inputted into the touch panel is superposed on a signal flowing through a sense line provided on which the hand holding the electrically conductive pen for input is placed. This causes generation of an error signal in a position of a sense line on which no hand is placed, as illustrated in  FIG. 14  as the phantom noise NZ. As a result, a problem arises that it becomes difficult to detect the signal of the pen. 
     Moreover, not only limited to the input with use of a pen, there also is a problem with a smart phone when using a software keyboard (application) that if the electromagnetic noise received by the body of the user is great, the phantom noise generates on the sense line that the finger or the like of the user touches, thereby causing a key of the software keyboard that is not pressed to react. 
     In the present specification, error signals generated as such is called “phantom noise”, where electromagnetic noise received by the human body from space is inputted into the touch panel via hands, fingers, or the like and is superposed on a signal flowing in the sense line that is touched by the hand, fingers, or the like. For example, as illustrated in  FIG. 14 , the phantom noise NZ generates in an area between circumscribing lines L 1  and L 2  which circumscribe the hand placing region HDR along the sense lines SL 1  to SLM and which is outside the hand placing region HDR. 
     It is an object of the present invention to provide a capacitance distribution detection method, a capacitance distribution detection circuit, a touch sensor system, and an information input/output device, each of which enables eliminating an effect caused by phantom noise generated by touching a panel with a hand, finger and the like of the human body that has received electromagnetic noise. 
     Solution to Problem 
     A capacitance distribution detection method according to the present invention is a method of detecting capacitance distribution, to detect a distribution of capacitance of a plurality of capacitors that are each formed on intersections of a plurality of first signal lines with a plurality of second signal lines, the method including: driving the first signal lines in a first timing, to output from the second signal lines electric charges that correspond to the capacitors; controlling, in a second timing subsequent to the first timing, a switching of connections of the first signal lines with that of the second signal lines; and driving the second signal lines in a third timing subsequent to the second timing, to output from the first signal lines the electric charges that correspond to the capacitors. 
     According to this feature, in a first timing, first signal lines are driven to output from second signal lines electric charges that correspond to the capacitors, in a second timing subsequent to the first timing, switching of connection of the first and second signal lines are controlled, and in a third timing subsequent to the second timing, the second signal lines are driven to output from the first signal lines the electric charges that correspond to the capacitors. Hence, it is possible to output the electric charges corresponding to the capacitors from both of the first signal lines and the second signal lines. As a result, it is possible to eliminate the effect caused by electromagnetic noise that is inputted into the touch panel via the hand, fingers or the like and is superposed on a signal of a sense line. 
     A capacitance distribution detection circuit according to the present invention is a capacitance distribution detection circuit that detects a distribution of capacitance of a plurality of capacitors that are each formed on intersections of a plurality of first signal lines with a plurality of second signal lines, the capacitance distribution detection circuit including: a multiplexer connected to the plurality of first signal lines and the plurality of second signal lines; a driver connected to the multiplexer; and a sense amplifier connected to the multiplexer; the multiplexer switching a connection state between a first connection state in which the first signal lines are connected to the driver and the second signal lines are connected to the sense amplifier and a second connection state in which the first signal lines are connected to the sense amplifier and the second signal lines are connected to the driver. 
     With this feature, it is possible to switch between a first connection state which connects the first signal lines with the driver and connects the second signal lines with the sense amplifier and a second connection state which connects the first signal lines with the sense amplifier and connects the second signal lines with the driver. This allows for outputting the electric charges corresponding to the capacitors from both the first signal lines and the second signal lines. As a result, it is possible to eliminate the effect caused by electromagnetic noise that is inputted into the touch panel via the hands, fingers and the like and is superposed on the signal of a sense line. 
     Another capacitance distribution detection circuit according to the present invention is a capacitance distribution detection circuit that detects a distribution of capacitance of a plurality of capacitors that are each formed on intersections of a plurality of first signal lines with a plurality of second signal lines, the capacitance distribution detection circuit including: a first multiplexer connected to the first signal lines; a first driver connected to the first multiplexer; a first sense amplifier connected to the first multiplexer; a second multiplexer connected to the second signal lines; a second driver connected to the second multiplexer; a second sense amplifier connected to the second multiplexer; and a control circuit that controls the first multiplexer and the second multiplexer so that a connection state is switchable between a first connection state in which the first signal lines are connected to the first driver and the second signal lines are connected to the second sense amplifier, and a second connection state in which the first signal lines are connected to the first sense amplifier and the second signal lines are connected to the second driver. 
     With this feature, it is possible to switch over between a first connection state which connects the first signal lines with the first driver and connects the second signal lines with the second sense amplifier, and a second connection state which connects the first signal lines with the first sense amplifier and connects the second signal lines with the second driver. This allows for outputting the electric charges corresponding to the capacitors from both the first signal lines and the second signal lines. As a result, it is possible to eliminate the effect caused by electromagnetic noise that is inputted into the touch panel via the hands, fingers and the like and is superposed on the signal of the sense line. 
     Yet another capacitance distribution detection circuit according to the present invention is a capacitance distribution detection circuit that detects a distribution of capacitance of a plurality of capacitors that are each formed on intersections of a plurality of first signal lines with a plurality of second signal lines; the capacitance distribution detection circuit including: a first multiplexer connected to a portion of the plurality of first signal lines; a first driver connected to the first multiplexer; a first sense amplifier connected to the first multiplexer; a second multiplexer connected to another portion of the plurality of first signal lines; a second driver connected to the second multiplexer; a second sense amplifier connected to the second multiplexer; a third multiplexer connected to a portion of the plurality of second signal lines; a third driver connected to the third multiplexer; a third sense amplifier connected to the third multiplexer; a fourth multiplexer connected to another portion of the plurality of second signal lines; a fourth driver connected to the fourth multiplexer; a fourth sense amplifier connected to the fourth multiplexer; and a control circuit that controls the first to fourth multiplexers so that a connection state is switchable between (a) a first connection state in which the portion of the first signal lines is connected to the first driver, the another portion of the first signal lines is connected to the second driver, the portion of the second signal lines is connected to the third sense amplifier, and the another portion of the second signal lines is connected to the fourth sense amplifier, and (b) a second connection state in which the portion of the first signal lines is connected to the first sense amplifier, the another portion of the first signal lines is connected to the second sense amplifier, the portion of the second signal lines is connected to the third driver, and the another portion of the second signal lines is connected to the fourth driver. 
     With this feature, it is possible to switch between (a) a first connection state in which a portion of the first signal lines is connected to the first driver, another portion of the first signal lines is connected to the second driver, a portion of the second signal lines is connected to the third sense amplifier, and another portion of the second signal lines is connected to the fourth sense amplifier, and (b) a second connection state in which a portion of the first signal lines is connected to the first sense amplifier, another portion of the first signal lines is connected to the second sense amplifier, a portion of the second signal lines is connected to the third driver, and another portion of the second signal lines is connected to the fourth driver. 
     This allows for outputting the electric charges corresponding to the capacitors from both the first signal lines and the second signal lines. As a result, it is possible to eliminate the effect caused by electromagnetic noise that is inputted into the touch panel via the hands, fingers and the like and is superposed on the signal of the sense line. 
     A touch sensor system according to the present invention includes: the capacitance distribution detection circuit according to the present invention; and a touch panel including the plurality of first signal lines, the plurality of second signal lines, and the plurality of capacitors. 
     An information input/output device according to the present invention includes: the touch sensor system according to the present invention; and a display panel (i) being superposed on a touch panel provided in the touch sensor system or (ii) having the touch panel be built therein. 
     Advantageous Effects of Invention 
     A method according to the present invention of detecting a capacitance distribution drives first signal lines in a first timing to output from second signal lines electric charges that correspond to the capacitors, controls, in a second timing subsequent to the first timing, switching of connection of the first and second signal lines, and drives the second signal lines in a third timing subsequent to the second timing, to output from the first signal lines the electric charges that correspond to the capacitors. This allows for outputting the electric charges that correspond to the capacitors from both the first signal lines and the second signal lines. As a result, it is possible to eliminate the effect caused by electromagnetic noise that is inputted into the touch panel via the hands, fingers and the like and is superposed on the signal of the sense line. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a block diagram illustrating a configuration of a touch sensor system according to Embodiment 1. 
         FIG. 2  is a schematic view illustrating a configuration of a touch panel provided in the touch sensor system. 
         FIG. 3  is a circuit diagram illustrating a configuration of a connection switching circuit between (a) signal lines connected to the touch panel, and (b) drive lines connected to a driver and sense lines connected to a sense amplifier. 
         FIG. 4  is a circuit diagram illustrating a configuration of a multiplexer provided in a capacitor distribution detection circuit of the touch sensor system. 
         FIG. 5  Illustrated in (a) and (b) of  FIG. 5  are schematic views for describing an operation method of the touch sensor system. 
         FIG. 6  Illustrated in (a) and (b) of  FIG. 6  are schematic views for describing another operation method of the touch sensor system. 
         FIG. 7  is a block diagram illustrating a configuration of a touch sensor system according to Embodiment 2. 
         FIG. 8  is a circuit diagram illustrating a configuration of a connection switching circuit between (a) signal lines connected to the touch panel, and (b) drive lines connected to a driver and sense lines connected to a sense amplifier. 
         FIG. 9  is a circuit diagram illustrating a configuration of a multiplexer provided in a capacitor distribution detection circuit of the touch sensor system. 
         FIG. 10  is a block diagram illustrating a configuration of a touch sensor system according to Embodiment 3. 
         FIG. 11  is a block diagram illustrating a configuration of a touch sensor system according to Embodiment 4. 
         FIG. 12  is a block diagram illustrating a configuration of a conventional touch sensor system. 
         FIG. 13  is a schematic view illustrating a configuration of a touch panel provided in the touch sensor system. 
         FIG. 14  is a view for describing phantom noise that generates in the touch sensor system. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Described below is an embodiment related to a touch sensor system of the present invention, with respect to  FIG. 1  through  FIG. 11 . 
     (Embodiment 1) 
     (Configuration of Touch Sensor System  1   a ) 
       FIG. 1  is a block diagram illustrating a configuration of a touch sensor system  1   a  according to Embodiment 1.  FIG. 2  is a schematic view illustrating a configuration of a touch panel  3  provided in the touch sensor system  1   a.    
     The touch sensor system  1   a  includes a touch panel  3  and a capacitance distribution detection circuit  2 . The touch panel  3  includes signal lines HL 1  to HLM (first signal lines) arranged parallel to each other in a horizontal direction, signal lines VL 1  to VLM (second signal lines) arranged parallel to each other in a vertical direction, and capacitors C 11  to CMM each provided at intersections of the signal lines HL 1  to HLM with the signal lines VL 1  to VLM. It is preferable that the touch panel  3  is of a size in which a hand holding the input pen can be placed on the touch panel  3 . However, the touch panel  3  may be of a size that is usable for smart phones. 
     The capacitance distribution detection circuit  2  includes a driver  5 . The driver  5  applies a voltage to drive lines DL 1  to DLM in accordance with a code sequence. The capacitance distribution detection circuit  2  includes a sense amplifier  6 . The sense amplifier  6  reads out, via the sense lines SL 1  to SLM, a linear sum of electric charges that correspond to the capacitors, and supplies the linear sum to an A/D converter  8 . 
     The capacitance distribution detection circuit  2  includes a multiplexer  4 .  FIG. 3  is a circuit diagram illustrating a configuration of a connection switching circuit between (a) signal lines HL 1  to HLM and VL 1  to VLM connected to the touch panel  3 , and (b) drive lines DL 1  to DLM connected to the driver  5  and sense lines SL 1  to SLM connected to the sense amplifier  6 . 
     The multiplexer  4  causes a switchover between (a) a first connection state in which the signal lines HL 1  to HLM are connected to the drive lines DL 1  to DLM of the driver  5  and the signal lines VL 1  to VLM are connected to the sense lines SL 1  to SLM of the sense amplifier  6  and (b) a second connection state in which the signal lines HL 1  to HLM are connected to the sense lines SL 1  to SLM of the sense amplifier  6  and the signal lines VL 1  to VLM are connected to the drive lines DL 1  to DLM of the driver  5 . 
       FIG. 4  is a circuit diagram illustrating a configuration of the multiplexer  4  provided in the capacitor distribution detection circuit  2  of the touch sensor system  1   a . The multiplexer  4  includes four CMOS switches SW 1  to SW 4 , which are connected in series. A signal from a timing generator  7  via the control line CL is supplied from (i) one end of the CMOS switch SW 1  opposite of the CMOS switch SW 2 , (ii) between the CMOS switch SW 2  and the CMOS switch SW 3 , (iii) one end of the CMOS switch SW 4  opposite of the CMOS switch SW 3 , and (iv) a terminal input of a reverser inv. The reverser inv has its output be supplied between the CMOS switch SW 1  and the CMOS switch SW 2 , and between the CMOS switch SW 3  and the CMOS switch SW 4 . The signal lines HL 1  to HLM are connected to the CMOS switches SW 1  and SW 2 . The signal lines VL 1  to VLM are connected to the CMOS switches SW 3  and SW 4 . The drive lines DL 1  to DLM are connected to the CMOS switches SW 1  and SW 4 . The sense lines SL 1  to SLM are connected to the CMOS switches SW 2  and SW 3 . 
     When the signal of the control line CL is made Low, the signal lines HL 1  to HLM become connected to the drive lines DL 1  to DLM and the signal lines VL 1  to VLM become connected to the sense lines SL 1  to SLM. When the signal of the control line CL is made High, the signal lines HL 1  to HLM become connected to the sense lines SL 1  to SLM and the signal lines VL 1  to VLM become connected to the drive lines DL 1  to DLM. 
     The A/D converter  8  converts from analog to digital a linear sum of electric charges read out via the sense lines SL 1  to SLM, which electric charges correspond to the capacitors, and supplies the converted linear sum to the capacitance distribution calculation section  9 . 
     The capacitance distribution calculation section  9 , based on the code sequence and the linear sum of the electric charges supplied from the A/D converter  8 , which electric charges correspond to the capacitors, calculates a capacitance distribution on the touch panel  3  and supplies the calculated capacitance distribution to a touch recognition section  10 . The touch recognition section  10  recognizes a touched position on the touch panel  3  based on the capacitance distribution supplied from the capacitance distribution calculation section  9 . 
     The capacitance distribution detection circuit  2  includes the timing generator  7 . The timing generator  7  generates (i) a signal for specifying an operation of the driver  5 , (ii) a signal for specifying an operation of the sense amplifier  6 , and (iii) a signal for specifying an operation of the A/D converter  8 , and supplies these signals to the driver  5 , the sense amplifier  6 , and the A/D converter  8 , respectively. 
     (Operation of Touch Sensor System  1   a ) 
     Illustrated in (a) and (b) of  FIG. 5  is a schematic view for describing an operation method of the touch sensor system  1   a . As described above with reference to  FIG. 14 , there is the problem that the phantom noise NZ generates in an area between the circumscribing lines L 1  and L 2  that circumscribe the hand placing region HDR along the sense lines SL 1  to SLM and which is outside the hand placing region HDR. However, when a pen signal is inputted on a sense line that does not overlap the hand placing region HDR, i.e., on a pen input position P outside the circumscribing lines L 1  and L 2  as illustrated in (a) of  FIG. 5 , this pen signal is detectable since no phantom noise NZ is generated on the sense line that the pen input position P passes, thereby having no deterioration in SNR caused by the phantom noise NZ. 
     Hence, in a case in which the hand placing region HDR and the pen input position P are in a positional relationship as illustrated in  FIG. 14 , the drive lines DL 1  to DLM and the sense lines SL 1  to SLM are switched over therebetween, to have the signal lines HL 1  to HLM in the horizontal direction function as the drive lines DL 1  to DLM and the signal lines VL 1  to VLM in the vertical direction function as the sense lines SL 1  to SLM, as illustrated in (b) of  FIG. 5 , so that the signal is detected outside the area between the circumscribing lines L 3  and L 4 . Consequently, it is possible to detect the pen signal of the pen input position P. 
     Accordingly, for example, by alternately switching over with the multiplexer  4  between a first connection state ((b) of  FIG. 5 ) and a second connection state ( FIG. 14 ) every one frame, which first connection state is a state in which the signal lines HL 1  to HLM are connected to the drive lines DL 1  to DLM of the driver  5  and the signal lines VL 1  to VLM are connected to the sense lines SL 1  to SLM of the sense amplifier  6  and the second connection state is a state in which the signal lines HL 1  to HLM are connected to the sense lines SL 1  to SLM of the sense amplifier  6  and the signal lines VL 1  to VLM are connected the drive lines DL 1  to DLM of the driver  5 , it is possible to detect the pen signal at one of timings of the first connection state and the second connection state, even if the phantom noise NZ generates due to the hand placing region HDR. Since the phantom noise NZ is generated in the other timing, the SNR of the pen signal is reduced to half. However, by alternately switching over between the first connection state and the second connection state, it is possible to detect the pen signal even if the phantom noise NZ is generated caused by the hand placing region HDR. 
     Therefore, for example, the touch sensor system  1   a  (i) drives, in a first timing, the signal lines HL 1  to HLM so that the signal lines VL 1  to VLM output electric charges that correspond to the capacitors (first signal line driving step), (ii) controls, with use of the multiplexer  4 , in a second timing subsequent to the first timing, a switching of connection of the signal lines HL 1  to HLM and the signal lines VL 1  to VLM (switching step), and (iii) drives, in a third timing subsequent to the second timing, the signal lines VL 1  to VLM so that the signal lines HL 1  to HLM output the electric charges that correspond to the capacitors (second signal line driving step). 
     The capacitance distribution calculation section  9  is configured so that a signal read out through a sense line from a capacitor disposed in a rectangle circumscribing with the hand placing region HDR, is not received. The hand placing region HDR is a region in which a hand holding the electrically conductive pen for input is placed on the touch panel; the capacitance distribution calculation section  9  can be configured to recognize this region by image recognition means not illustrated. Moreover, the configuration may be provided so that a user of the touch sensor system  1   a  specifies the hand placing region HDR. 
     Moreover, when the switching between the drive lines and the sense lines similarly to the above is carried out in a smart phone with which no hand placing region HDR by pen input occurs, although a signal to be detected generated by touching with a finger is generated in either of the driving states, an error signal caused by the phantom noise is removable since a position in which the phantom noise is generated differs by the switching of the drive lines and the sense lines. 
     Illustrated in (a) and (b) of  FIG. 6  are schematic views for describing another operation method of the touch sensor system  1   a . As illustrated in (a) of  FIG. 6 , after the vertical signal lines VL 1  to VLM are connected to the drive lines DL 1  to DLM and vertical signal lines VL 1  to VLM are driven, and the horizontal signal lines HL 1  to HLM are connected to the sense lines SL 1  to SLM, the phantom noise NZ that generates in an area between circumscribing lines L 5  and L 6  (circumscribing along a horizontal direction of a finger-touched region FR where the finger is touched) and which is outside the finger-touched region FR, is read out via the sense line together with a signal corresponding to the finger-touched region FR. Thereafter, as illustrated in (b) of  FIG. 6 , after the horizontal signal lines HL 1  to HLM are connected to the drive lines DL 1  to DLM and the horizontal signal lines HL 1  to HLM are driven, and the vertical signal lines VL 1  to VLM are connected to the sense lines SL 1  to SLM, the phantom noise NZ generated between the circumscribing lines L 7  and L 8  that circumscribe the finger-touched region FR along the vertical direction, is read out via a sense line together with a signal corresponding to the finger-touched region FR. 
     The phantom noise NZ generated between the circumscribing lines L 5  and L 6  as illustrated in (a) of  FIG. 6  and the phantom noise generated between the circumscribing lines L 7  and L 8  as illustrated in (b) of  FIG. 6  are generated randomly, unrelated to each other. Accordingly, when an AND operation is carried out with use of (i) the signal corresponding to the phantom noise NZ generated between the circumscribing lines L 5  and L 6  as in (a) of  FIG. 6 , read out via the sense line, and corresponding to the finger-touched area FR, and (ii) the signal read out via the sense line, corresponding to the phantom noise NZ generated between the circumscribing lines L 7  and L 8  as in (b) of  FIG. 6 , read out via the sense line, and corresponding to the finger-touched area FR, it is possible to cancel the phantom noise NZ generated between the circumscribing lines L 5  and L 6  with the phantom noise NZ generated between the circumscribing lines L 7  and L 8 . 
     (Embodiment 2) 
     (Configuration of Touch Sensor System  1   b ) 
       FIG. 7  is a block diagram illustrating a configuration of a touch sensor system  1   b  according to Embodiment 2.  FIG. 8  is a circuit diagram illustrating a configuration of a connection switching circuit (multiplexers  4   a  and  4   b ) between (a) signal lines HL 1  to HLM and VL 1  to VLM connected to a touch panel  3 , and (b) drive lines DL 1  to DLM connected to drivers  5   a  and  5   b  and sense lines SL 1  to SLM connected to sense amplifiers  6   a  and  6   b . Components identical to those described above are provided with identical reference signs, and detailed descriptions thereof are not repetitively provided. 
     The touch sensor system  1   b  includes a capacitance distribution detection circuit  2   a . The capacitance distribution detection circuit  2   a  includes two multiplexers,  4   a  and  4   b . The multiplexer  4   a  is connected to the touch panel  3  in a fixed manner, via the signal lines HL 1  to HLM. The capacitance distribution detection circuit  2   a  includes the driver  5   a  and the sense amplifier  6   a . The driver  5   a  is connected to the multiplexer  4   a  via the drive lines DL 1  to DLM, and the sense amplifier  6   a  is connected to the multiplexer  4   a  via the sense lines SL 1  to SLM. 
     The capacitance distribution detection circuit  2   a  includes an A/D converter  8   a  and a timing generator  7   a . The A/D converter  8   a  converts an output from the sense amplifier  6   a  from analog to digital, and supplies this converted output to a capacitance distribution calculation section  9 . The timing generator  7   a  generates (i) a signal specifying an operation of the driver  5   a , (ii) a signal specifying an operation of the sense amplifier  6   a , and (iii) a signal specifying an operation of the A/D converter  8   a , and supplies these signals to the driver  5   a , the sense amplifier  6   a , and the A/D converter  8   a , respectively. The timing generator  7   a  supplies a signal for controlling the multiplexer  4   a , via a control line CLa. 
     The multiplexer  4   b  is connected to the touch panel  3  in a fixed manner via the signal lines VL 1  to VLM. The capacitance distribution detection circuit  2   a  includes the driver  5   b  and the sense amplifier  6   b . The driver  5   b  is connected to the multiplexer  4   b  via the drive lines DL 1  to DLM and the sense amplifier  6   b  is connected to the multiplexer  4   b  via the sense lines SL 1  to SLM. 
     The capacitance distribution detection circuit  2   a  includes an A/D converter  8   b  and a timing generator  7   b . The A/D converter  8   b  converts an output from the sense amplifier  6   b  from analog to digital, and supplies this converted output to the capacitance distribution calculation section  9 . The timing generator  7   b  generates (i) a signal specifying an operation of the driver  5   b , (ii) a signal specifying an operation of the sense amplifier  6   b , and (iii) a signal specifying an operation of the A/D converter  8   b , and supplies these signals to the driver  5   b , the sense amplifier  6   b , and the A/D converter  8   b , respectively. The timing generator  7   b  supplies a signal for controlling the multiplexer  4   b , via the control line CLb. 
     The capacitance distribution detection circuit  2   a  includes a sync signal generation section  11 . The sync signal generation section  11  generates a sync signal for the timing generators  7   a  and  7   b  to control the multiplexers  4   a  and  4   b  to cause the switching over between (a) a first connection state in which the signal lines HL 1  to HLM are connected to the driver  5   a  and the signal lines VL 1  to VLM are connected to the sense amplifier  6   b  and (b) a second connection state in which the signal lines HL 1  to HLM are connected to the sense amplifier  6   a  and the signal lines VL 1  to VLM are connected to the driver  5   b , and supplies the generated sync signal to the timing generators  7   a  and  7   b.    
       FIG. 9  is a circuit diagram illustrating a configuration of the multiplexers  4   a  and  4   b  provided in the capacitor distribution detection circuit  2   a  of the touch sensor system  1   b . The multiplexer  4   a  includes two CMOS switches SW 5  and SW 6  that are connected in series. A signal from the timing generator  7   a  via the control line CLa is inputted from (i) one end of the CMOS switch SW 5  opposite of the CMOS switch SW 6 , (ii) one end of the CMOS switch SW 6  opposite of the CMOS switch SW 5 , and (iii) a terminal input of a reverser inv. The reverser inv has its output be inputted between the CMOS switch SW 5  and CMOS switch SW 6 . The signal lines HL 1  to HLM are connected to the CMOS switches SW 5  and SW 6 . The drive lines DL 1  to DLM are connected to the CMOS switch SW 5 . The sense lines SL 1  to SLM are connected to the CMOS switch SW 6 . 
     (Operation of Touch Sensor System  1   b ) 
     When a signal of the control line CLa is made Low, the signal lines HL 1  to HLM become connected to the drive lines DL 1  to DLM. When the signal of the control line CLa is made High, the signal lines HL 1  to HLM become connected to the sense lines SL 1  to SLM. The multiplexer  4   b  is also configured similarly to this. 
     As such, the touch sensor system  1   b  includes the multiplexers  4   a  and  4   b  having similar configurations; the multiplexer  4   a  is connected to the signal lines HL 1  to HLM of the touch panel  3  in a fixed manner, and the multiplexer  4   b  is connected to the signal lines VL 1  to VLM of the touch panel  3  in a fixed manner. Furthermore, the multiplexers  4   a  and  4   b  are operated in sync, based on a sync signal generated by the sync signal generation section  11 . When the multiplexer  4   a  is connected to the driver  5   a , the multiplexer  4   b  is connected to the sense amplifier  6   b , and when the multiplexer  4   a  is connected to the sense amplifier  6   a , the multiplexer  4   b  is connected to the driver  5   b.    
     (Embodiment 3) 
       FIG. 10  is a block diagram illustrating a configuration of a touch sensor system  1   c  according to Embodiment 3. Components identical to those described above are provided with identical reference signs, and detailed descriptions thereof are not repetitively provided. 
     The touch sensor system  1   c  includes a capacitance distribution detection circuit  2   c . The capacitance distribution detection circuit  2   c  includes controllers  12   a  and  12   b . The controller  12   a  includes multiplexers  4   a   1  to  4   a   4 . The multiplexers  4   a   1  to  4   a   4  have configurations similar to that of the multiplexer  4   a  described above with reference to  FIG. 7  through  FIG. 9 , however is connected to a fewer number of signal lines; the multiplexer  4   a   1  is connected to signal lines HL 1  to HL(m 1 ), the multiplexer  4   a   2  is connected to signal lines HL(m 1 +1) to HL(m 2 ), the multiplexer  4   a   3  is connected to signal lines HL(m 2 +1) to HL(m 3 ), and the multiplexer  4   a   4  is connected to signal lines HL(m 3 +1) to HLM, where 1&lt;m 1 &lt;m 2 &lt;m 3 &lt;M. 
     The controller  12   b  includes multiplexers  4   b   1  to  4   b   4 . The multiplexers  4   b   1  to  4   b   4  have configurations similar to that of the multiplexer  4   b  described above with reference to  FIG. 7  through  FIG. 9 , however is connected to a fewer number of signal lines; the multiplexer  4   b   1  is connected to signal lines VL 1  to VL(k 1 ), the multiplexer  4   b   2  is connected to signal lines VL(k 1 +1) to VL(k 2 ), the multiplexer  4   b   3  is connected to signal lines VL(k 2 +1) to VL(k 3 ), and the multiplexer  4   b   4  is connected to signal lines VL(k 3 +1) to VLM, where 1&lt;k 1 &lt;k 2 &lt;k 3 &lt;M. 
     The multiplexers  4   a   1  to  4   a   4  and the multiplexers  4   b   1  to  4   b   4  each include respective drivers, sense amplifiers, timing generators, and ADC, and operate in sync based on a sync signal generated by a sync signal generation section. The controllers  12   a  and  12   b  may be fabricated as an integrated circuit (IC). 
     In the touch sensor system  1   c , control is carried out to switch between (a) a first connection state in which the signal lines HL 1  to HL(m 1 ), the signal lines HL(m 1 +1) to HL(m 2 ), the signal lines HL(m 2 +1) to HL(m 3 ), and the signal lines HL(m 3 +1) to HLM are connected to a driver and the signal lines VL 1  to VL(k 1 ), the signal lines VL(k 1 +1) to VL(k 2 ), the signal lines VL(k 2 +1) to VL(k 3 ), and the signal lines VL(k 3 +1) to VLM are connected to a sense amplifier, and (b) a second connection state in which the signal lines HL 1  to HL(m 1 ), the signal lines HL(m 1 +1) to HL(m 2 ), the signal lines HL(m 2 +1) to HL(m 3 ), and the signal lines HL(m 3 +1) to HLM are connected to a sense amplifier and the signal lines VL 1  to VL(k 1 ), the signal lines VL(k 1 +1) to VL(k 2 ), the signal lines VL(k 2 +1) to VL(k 3 ), and the signal lines VL(k 3 +1) to VLM are connected to a driver. 
     (Embodiment 4) 
       FIG. 11  is a block diagram illustrating a configuration of a touch sensor system  1   d  according to Embodiment 4. Components identical to those described above are provided with identical reference signs, and detailed descriptions thereof are not repetitively provided. 
     A sense amplifier of the touch sensor system  1   d  includes a configuration to read out a signal from adjacent sense lines upon subtraction, allowing for canceling noise from a liquid crystal panel and the like and improve SNR. 
     The touch sensor system  1   d  includes a capacitance distribution detection circuit  2   d . The capacitance distribution detection circuit  2   d  includes controllers  13   a  and  13   b . The controller  13   a  includes multiplexers  14   a   1  to  14   a   4 . The multiplexers  14   a   1  to  14   a   4  have configurations similar to that of the multiplexer  4   a  described above with reference to  FIG. 7  to  FIG. 9 , however is connected to a fewer number of signal lines, and adjacent multiplexers share a signal line that is disposed on their common boundary. 
     The multiplexer  14   a   1  is connected to signal lines HL 1  to HL(m 1 ), the multiplexer  14   a   2  is connected to signal lines HL(m 1 ) to HL(m 2 ), the multiplexer  4   a   3  is connected to signal lines HL(m 2 ) to HL(m 3 ), and the multiplexer  4   a   4  is connected to signal lines HL(m 3 ) to HLM, where 1&lt;m 1 &lt;m 2 &lt;m 3 &lt;M. As such, adjacent multiplexers  14   a   1  and  14   a   2  share the signal line HL(m 1 ) disposed on their common boundary, adjacent multiplexers  14   a   2  and  14   a   3  share the signal line HL(m 2 ) disposed on their common boundary, and adjacent multiplexers  14   a   3  and  14   a   4  share the signal line HL(m 3 ) disposed on their common boundary. 
     The controller  13   b  includes multiplexers  14   b   1  to  14   b   4 . The multiplexers  14   b   1  to  14   b   4  have configurations similar to that of the multiplexer  4   b  described above with reference to  FIG. 7  to  FIG. 9 , however is connected to a fewer number of signal lines, and adjacent multiplexers share a signal line disposed on their common boundary. 
     The multiplexer  14   b   1  is connected to signal lines VL 1  to VL(k 1 ), the multiplexer  14   b   2  is connected to signal lines VL(k 1 ) to VL(k 2 ), the multiplexer  14   b   3  is connected to signal lines VL(k 2 ) to VL(k 3 ), and the multiplexer  14   b   4  is connected to signal lines VL(k 3 ) to VLM, where 1&lt;k 1 &lt;k 2 &lt;k 3 &lt;M. As such, adjacent multiplexers  14   b   1  and  14   b   2  share the signal line VL(k 1 ) disposed on their common boundary, adjacent multiplexers  14   b   2  and  14   b   3  share the signal line VL(k 2 ) disposed on their common boundary, and adjacent multiplexers  14   b   3  and  14   b   4  share the signal line VL(k 3 ) disposed on their common boundary. 
     The multiplexers  14   a   1  to  14   a   4  and the multiplexers  14   b   1  to  14   b   4  each include respective drivers, sense amplifiers, timing generators, and ADC, and operate in sync based on a sync signal generated by a sync signal generation section. The controllers  13   a  and  13   b  may be fabricated as an integral circuit (IC). 
     As such, in a case in which the sense amplifier is configured so as to read out a signal from adjacent sense lines upon subtraction, to allow for canceling noise from the liquid crystal panel and the like and improve SNR, by sharing a signal line disposed on a common boundary of adjacent multiplexers, it is possible to continuously carry out differential read-out of sense lines disposed on the boundary of the sense lines corresponding to the adjacent multiplexers in a manner exceeding that boundary. 
     The touch sensor systems according to Embodiments 1 to 4 may be constituted in a media blackboard (information input/output device) capable of receiving input by being handwritten thereon while a plurality of persons touch the blackboard, by superposing the touch sensor system with a liquid crystal display panel or by building the touch sensor system inside a liquid crystal display panel. 
     With the capacitance distribution detection method according to the present embodiment, it is preferable that the plurality of first signal lines, the plurality of second signal lines, and the plurality of capacitors constitute a touch panel, the touch panel being of a size allowing for a hand that holds a pen for input to be placed thereon. 
     According to the configuration, it is possible to eliminate an effect caused by electromagnetic noise inputted into a touch panel via a hand touched on the touch panel while holding a pen for input, and which electromagnetic noise is superposed on a signal of a sense line. 
     With the capacitance distribution detection circuit according to the present embodiment, it is preferable that the plurality of first signal lines, the plurality of second signal lines, and the plurality of capacitors constitute a touch panel, the touch panel being of a size allowing for a hand that holds a pen for input to be placed thereon. 
     According to the configuration, it is possible to eliminate an effect caused by electromagnetic noise inputted into a touch panel via a hand touched on the touch panel while holding a pen for input, and which electromagnetic noise is superposed on a signal of a sense line. 
     With yet another capacitance distribution detection circuit according to the present embodiment, it is preferable that the portion of the plurality of first signal lines and the another portion of the plurality of first signal lines share a signal line disposed on their common boundary, and the portion of the plurality of second signal lines and the another portion of the plurality of second signal lines share a signal line disposed on their common boundary. 
     With the foregoing configuration, it is possible to continuously carry out differential read-out of a sense line disposed on a common boundary of portions of adjacent multiplexers, exceeding the common boundary. 
     With a touch sensor system according to the present embodiment, it is preferable that the capacitance distribution detection circuit detects a distribution of capacitance in accordance with an input with use of a pen. 
     With an information input/output device according to the present embodiment, it is preferable that the capacitance distribution detection circuit detects a distribution of capacitance in accordance with an input with use of a pen. 
     The present invention is not limited to the description of the embodiments above, but may be altered by a skilled person within the scope of the claims. An embodiment based on a proper combination of technical mans disclosed in different embodiments is encompassed in the technical scope of the present invention. 
     INDUSTRIAL APPLICABILITY 
     The present invention is applicable to a capacitance distribution detection method, a capacitance distribution detection circuit, a touch sensor system, and an information input/output device, each of which detects a distribution of capacitance of a plurality of capacitors each formed on intersections of a plurality of first signal lines with a plurality of second signal lines. 
     Moreover, the present invention can be used in a touch sensor system including a large-sized touch panel in which a hand placing region would occur when entering with use of a pen, for example, a media blackboard, a tablet terminal, and the like, which is capable of receiving entry via handwriting on the blackboard by a plurality of persons. 
     REFERENCE SIGNS LIST 
       1   a  touch sensor system 
       2  capacitance distribution detection circuit 
       3  touch panel 
       4  multiplexer 
       4   a  multiplexer (first multiplexer) 
       4   b  multiplexer (second multiplexer) 
       4   a   1  multiplexer (first multiplexer) 
       4   a   2  multiplexer (second multiplexer) 
       4   b   1  multiplexer (third multiplexer) 
       4   b   2  multiplexer (fourth multiplexer) 
       14   a   1  multiplexer (first multiplexer) 
       14   a   2  multiplexer (second multiplexer) 
       14   b   1  multiplexer (third multiplexer) 
       14   b   2  multiplexer (fourth multiplexer) 
       5  driver 
       5   a  driver (first driver) 
       5   b  driver (second driver) 
       6  sense amplifier 
       6   a  sense amplifier (first sense amplifier) 
       6   b  sense amplifier (second sense amplifier) 
       7  timing generator 
       7   a  timing generator (control circuit) 
       7   b  timing generator (control circuit) 
       8  A/D converter 
       9  capacitance distribution calculation section 
       10  touch recognition section 
       11  sync signal generation section (control circuit) 
       12   a ,  12   b ,  13   a ,  13   b  controller 
     HL 1 -HLM signal line (first signal line) 
     VL 1 -VLM signal line (second signal line) 
     C 11 -CMM capacitor 
     DL 1 -DLM drive line 
     SL 1 -SLM sense line 
     SW 1 -SW 4  switch 
     HDR hand placing region 
     L 1 -L 4  circumscribing line 
     P pen input position 
     NZ phantom noise