Abstract:
Relating to input devices and electronic devices generating a signal corresponding to a position depressed on their input domain, an input device and an electronic device are capable of performing an easy correction. The input device generates the signal corresponding to the position depressed on its input domain, and contains a correction domain and a correction unit. The correction domains are set in several positions in a periphery of and different from the input domain. Based on the signal corresponding to the position depressed on the correction domain, the correction unit corrects the signal corresponding to the position depressed on the input domain.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to input devices and electronic devices, more particularly, to an input device and an electronic device that generate a signal corresponding to a position depressed on their input domains. 
   Recently, the expanding market for information communication apparatuses and terminal units in business use has rapidly increased the demand for touch panels. A touch panel is incorporated suitably in a small apparatus such as a PDA (personal digital assistant), because it is arranged in a stack together with a display device and can be satisfactorily operated on the display device. Among types of touch panels, there has been a stronger demand for a resistance film type touch panel, which is capable of controlling and operating easily not only PDAs but also office computers and personal computers. Normally, a touch panel is arranged on the surface of a display device, and is incorporated so that it can operate together with what is projected on the display device. Here, it is required that relative positions of the touch panel and the display device be accurately aligned. Thus, correcting an input coordinate of the touch panel on the basis of the relative position of the touch panel to the display device, that is, calibration, is usually carried out. 
   2. Description of the Related Art 
     FIG. 1  illustrates a structure of a system incorporating an input device with a resistance film type touch panel. 
   An input device  1  is placed on a screen  3  of a display device  2 . Icons, buttons and so on are projected on the screen  3  of the display device  2 . Depressing positions corresponding to the icons and the buttons projected on the screen  3  of the input device  1  starts applications corresponding to the icons and the buttons. 
   The input device  1  comprises a touch panel  11  and an interface circuit substrate  12 . 
     FIG. 2  is an exploded perspective view of the touch panel  11 . 
   The resistance film type touch panel  11  is constructed in a stack together with a lower substrate  21  and an upper substrate  22  by putting dot spacers, which are not illustrated, between the lower substrate  21  and the upper substrate  22 . A flexible wiring board  4  to be connected with the interface circuit substrate  12  is glued to an edge between the lower substrate  21  and the upper substrate  22 . 
   The lower substrate  21  comprises a glass substrate  31 , a conductive film  32 , electrodes  33  and  34 , and wiring patterns  35  through  38 . The conductive film  32  is formed of a transparent conductive material such as ITO (indium tin oxide), and is set on the glass board  31 . 
   The electrode  33  is formed of a conductive material such as aluminum, and is shaped in the form of a straight line on an edge of the conductive film  32  in the arrow X 1  direction. The electrode  34  is formed of a conductive material such as aluminum, and is shaped in the form of a straight line on an edge of the conductive film  32  in the arrow X 2  direction. The electrodes  33  and  34  are formed in parallel. 
   The wiring pattern  35  is connected with the electrode  33  at its one end, and with a wiring pattern  51  on a flexible wiring board  23  at the other end. The wiring pattern  36  is connected with the electrode  34  at its one end, and with a wiring pattern  52  on the flexible wiring board  23  at the other end. As mentioned above, both the electrodes  33  and  34  are connected with the interface circuit substrate  12 . Also, the wiring pattern  37  is connected with a wiring pattern  53  on the flexible wiring board  23 , and the wiring pattern  38  is connected with a wiring pattern  54  on the flexible wiring board  23 . 
   The upper substrate  22  comprises a film  41 , a conductive film  42 , electrodes  43  and  44 , and wiring patterns  45  and  46 . The film  41  is formed of synthetic resin such as PET (poly-ethylene-telephtalete) shaped in the form of a film, and has flexibility. The conductive film  42  is formed of a transparent conductive material such as TTO (indium tin oxide), and is set on the under surface of the film  41  toward the lower substrate  21 . 
   The electrode  43  is formed of a conductive material such as aluminum, and is shaped in the form of a straight line on an edge of the conductive film  42  in the arrow Y 1  direction. The electrode  44  is formed of a conductive material such as aluminum, and is shaped in the form of a straight line on an edge of the conductive film  42  in the arrow Y 2  direction. The electrodes  43  and  44  are formed in parallel. 
   The wiring pattern  45  is connected with the electrode  43  at its one ends and with the wiring pattern  53  on the flexible wiring board  23  at the other end through the wiring pattern  37  on the lower substrate  21 . The wiring pattern  46  is connected with the electrode  44  at its one end, and with the wiring pattern  54  on the flexible wiring board  23  at the other end through the wiring pattern  38  on the lower substrate  21 . The electrodes  43  and  44  are connected with the interface circuit substrate  12  through the flexible wiring board  23 . 
   Dot spacers are formed of an insulator such as resin, and are placed between the lower substrate  21  and the upper substrate  22 . While there is no depressing action, the dot spacers prevent contact between the conductive film  32  on the lower substrate  21  and the conductive film  42  on the upper substrate  22 . 
   When the upper substrate  22  is depressed, the upper substrate  22  bends and the conductive film  42  on the upper substrate  22  touches the conductive film  32  on the lower substrate  21 . The contact of the conductive film  42  on the upper substrate  22  and the conductive film  32  on the lower substrate  21  provides coordinates of the contact point that can be detected. 
   An explanation of a series of actions for detecting the coordinate will now be given. 
   The interface circuit substrate  12  repeatedly alternates between the following two actions. One action is to apply a predetermined voltage of Vcc between the electrodes  33  and  34  formed on the lower substrate  21  and to detect an electric potential of the electrode  43  of the upper substrate  22 . The other action is to apply a predetermined voltage of Vcc between the electrodes  43  and  44  formed on the upper substrate  22  and to detect an electric potential of the electrode  33  on the lower substrate  21 . 
   If the predetermined voltage of Vcc between the electrodes  33  and  34  formed on the lower substrate  21  is applied, a potential gradient between the electrodes  33  and  34  is caused. Then, detecting an electric potential of the contact point through the electrode  43  of the upper substrate  22  makes it possible to detect a position of the contact point in the X-axis directions. 
   On the other hand, if the predetermined voltage of Vcc between the electrodes  43  and  44  formed on the upper substrate  22  is applied, a potential gradient between the electrodes  43  and  44  is caused. Then, detecting an electric potential of the contact point through the electrode  33  or the electrode  34  of the lower substrate  21  makes it possible to detect a position of the contact point in the Y-axis directions. 
   At this time, the potential gradient between the electrodes  43  and  44  of the upper substrate  22  is different from the potential gradient between the electrodes  33  and  34  on the lower substrate  21 . Accordingly, it is possible to perform detection without the resistance of the conductive films  32  or  42  influencing where the electric potential of the contact point is detected. The interface circuit substrate  12  detects a coordinate in the X-axis directions from the electric potential in the X-axis directions, a coordinate in the Y-axis directions from the electric potential in the Y-axis directions, and sends these coordinates to an information process unit  5 . 
   As illustrated in  FIG. 1 , the touch panel  11  is glued and mounted on the display device  2 . According to what is shown on the screen  3  of the display device  2 , an operator gives inputs. Thus, it is important to accurately position the touch panel  11  relative to the screen  3  of the display device  2 . 
   The touch panel  11  and the display device  2  have been conventionally positioned by fitting outer shapes of the touch panel  11  and the display device  2 . As a result, the relative position of the touch panel  11  to the display device  2  is inaccurate, whereby resulting in poor operation. Thus, it is required that the relative position of the touch panel  11  to the display device  2  be corrected. 
   Conventionally, the relative position of the touch panel  11  to the display device  2  has been commonly corrected by operator&#39;s manipulations. The operator manipulates the input device  1  and others to set the information processing unit  5  in a position correction mode. Once the information processing unit  5  is in the position correction mode, the information processing unit  5  starts to display a position to be depressed on the screen  3  of the display device  2 . The operator depresses the position displayed on the display device  2 . 
   Next, the information processing unit  5  detects a position on the touch panel  11  depressed by the operator on the basis of coordinate information from the interface circuit  12 . 
   Then, the information processing unit  5  compares the position to be depressed on the screen  3  of the display device  2  with the position on the touch panel  11  depressed by the operator, and computes a correction value so that the coordinate information from the interface circuit  12  can be consistent with the coordinate information on the position to be depressed on the screen  3  of the display device  2 . The information processing unit  5  or the interface circuit  12  saves the correction value. Thereafter, the information processing unit  5  or the interface circuit  12  corrects the coordinate information on the basis of the saved correction value. The information processing unit  5  determines a coordinate on the basis of the coordinate information that has just been corrected according to the correction value. 
   Under the heretofore-described conventional correction of the relative position of the touch panel  11  to the display device  2 , however, operations for correcting the relative position are complicated because of the necessity of operator&#39;s manipulations. 
   On the other hand, the connections between wiring patterns on the touch panel  11  or the touch panel itself and the flexible wiring board  23  deteriorate over time, whereby enlarging the wiring resistance. Under conventional touch panels, however, wiring conditions of the touch panel  11 , the flexible wiring board  23  and others have not been taken into consideration. Thus, we have the problem that the precision of the coordinate detection deteriorates over time. 
   SUMMARY OF THE INVENTION 
   It is a general object of the present invention to provide an improved and useful input device and electronic device in which the above-mentioned problems are eliminated. 
   A more specific object of the present invention is to provide an input device and an electronic device capable of performing corrections easily. 
   In order to achieve the above-mentioned object, there is provided according to one aspect of the present invention an input device generating a signal corresponding to a position depressed on an input domain, comprising: a correction domain that is set in a position different from the input domain, the correction domain generating the signal corresponding to the depressed position. 
   According to the present invention, if the correction domain is set in a position different from the input domain, depression on the correction domain makes it possible to detect a position of the input device. Thus, if a case is mounted so that the correction domain can be depressed through the case, a position of the input device toward the case can be detected automatically without operator&#39;s depression on the input domain. 
   Additionally, in the input device according to the present invention, the correction domains may be set in a plurality of positions around the input domain. 
   Additionally, in the input device according to the present invention, the correction domains may comprise a first correction domain generating a signal corresponding to a coordinate in the X-axis directions and a second correction domain generating a signal corresponding to a coordinate in the Y-axis directions. 
   According to the present invention, if the correction domains are set in a plurality of positions such as the first correction domain and the second correction domain wherein the first correction domain generates the signal corresponding to the coordinate in the X-axis directions and the second correction domain generates the signal corresponding to the coordinate in the Y-axis directions, it is possible to detect misalignment with respect to a plurality of axis directions and perform an accurate correction. 
   Additionally, in the input device according to the present invention, the input device may comprise a correction unit receiving a signal from the input domain and a signal from the correction domain, the correction unit correcting a signal corresponding to a position depressed on the input domain on the basis of a signal corresponding to a position depressed on the correction domain. 
   According to the present invention, it is possible to perform accurate coordinate detection, because the signal corresponding to the position depressed on the input domain can be corrected on the basis of the signal corresponding to the position depressed on the correction domain. 
   In order to achieve the above-mentioned objects, there is provided according to another aspect of the present invention an input device, comprising: a protrusion part that is set in the opposite position to the correction domain, the protrusion depressing the correction domain. 
   According to the present invention, it is possible to position an input domain toward a position of the protrusion automatically, because the mounted protrusion depresses the correction domain. 
   In order to achieve the above-mentioned objects, there is provided according to another aspect of the present invention an input device, comprising: a touch panel generating an amount of voltage corresponding to a depressed position; and a cable connecting the touch panel and an external circuit, the touch panel containing a first connection pad connected with an input and output terminal of the cable and a second connection pad connected with the first connection pad so as to have a connection with an internal circuit of the touch panel; and the cable containing first wiring connected with the first connection pad so as to input and output a signal to the internal circuit of the touch panel, and second wiring connected with the second connection pad so as to detect an electric potential of the second connection pad. 
   According to the present invention, if an amount of voltage is applied to the first connection pad through the first wiring and the electric potential of the second connection pad is detected through the second wiring, a condition of the touch panel can be detected on the basis of resistance of wirings on the touch panel and others. 
   Additionally, in the input device according to the present invention, an electric potential of the second connection pad may be detected through the second wiring. Based on the detection result, a coordinate detection result is corrected with the touch panel. 
   According to the present invention, a condition of the touch panel is detected, whereby the correction of the coordinate detection result makes it possible to perform more accurate coordinate detection. 
   Additionally, in the input device according to the present invention, an electric potential of the second connection pad may be detected through the second wiring, thereby determining a wiring condition of the touch panel and the cable. 
   According to the present invention, the electric potential of the second connection pad is detected through the second wiring and, thereby determining the wiring condition of the touch panel and the cable. If the wiring condition is in disorder, an alarm is delivered to their superior units, whereby the use in disorder can be prevented. 
   Other objects, features and advantages of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a diagram illustrating a structure incorporating an input device system with a resistance film type touch panel; 
       FIG. 2  is an exploded perspective view of the touch panel of  FIG. 1 ; 
       FIG. 3  is a diagram illustrating a structure of an input device according to a first embodiment of the present invention; 
       FIG. 4  is an exploded perspective view of the touch panel of  FIG. 3 ; 
       FIG. 5  is a block diagram illustrating a structure of an interface circuit substrate of  FIG. 3 ; 
       FIG. 6  is a diagram illustrating a circuit structure of a panel driver switching circuit; 
       FIG. 7  is a diagram illustrating a circuit structure of parts according to a variation of the first embodiment of the present invention; 
       FIG. 8  is a flowchart of a correction process program executed by a control IC according to the present invention; 
       FIG. 9  is a diagram illustrating a structure of an input device according to a second embodiment of the present invention; 
       FIG. 10  is a flowchart of an input device according to the second embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   A description will now be given, with reference to  FIG. 3 , of the first embodiment of the present invention.  FIG. 3  is a diagram illustrating a structure of an input device according to the first embodiment of the present invention. In  FIG. 3 , parts that are the same as the parts shown in  FIG. 1  and  FIG. 2  are given the same reference numerals, and descriptions thereof will be omitted. 
   An input device  100  according to the first embodiment of the present invention differs from the input device  1  shown in  FIG. 1  and  FIG. 2  with respect to the structure of a touch panel  111  and a process action of an interface circuit  112 . Furthermore, the structure of a front case  200 , where the input device  100  is mounted, is different. 
     FIG. 4  is an exploded perspective view of the touch panel  111 . 
   The touch panel  111  according to the first embodiment of the present invention comprises an input domain  121 , a first correction domain  122  and a second correction domain  123  around and apart from the input domain  121 . The first correction domain  122  comprises a first position detection unit in the X-axis directions  131  and a first position detection unit in the Y-axis directions  132 . The second correction domain  123  comprises a second position detection unit in the X-axis directions  133  and a second position detection unit in the Y-axis directions  134 . 
   The first position detection unit in the X-axis directions  131  is mounted separately from the input domain  121  at the outside of the lower-right edge of the input domain  121  on the touch panel  111 , and is lengthened in the X-axis directions. The first position detection unit in the X-axis directions  131  comprises a lower electrode  141  formed on the lower substrate  21  and an upper electrode  142  formed on the upper substrate  22 . The lower electrode  141  is formed of a conductive material with comparatively high resistance such as ITO, and the upper electrode  142  is formed of a conductive material with low resistance such as aluminum. Both ends of the upper electrode  142  and one end of the lower electrode  141  are connected with the interface circuit substrate  112  through a flexible wiring board  151 . 
   The first position detection unit in the Y-axis directions  132  is mounted separately from the input domain  121  at the outside of the lower-right edge of the input domain  121  on the touch panel  111 , and is lengthened in the Y-axis directions. The first position detection unit in the Y-axis directions  132  comprises a lower electrode  143  formed on the lower substrate  21  and an upper electrode  144  formed on the upper substrate  22 . Both ends of the upper electrode  144  and one end of the lower electrode  143  are connected with the interface circuit substrate  112  through the flexible wiring board  151 . 
   The second position detection unit in the X-axis directions  133  is mounted separately from the input domain  121  at the outside of the upper-left edge of the input domain  121  on the touch panel  111 , and is lengthened in the X-axis directions. The second position detection unit in the X-axis directions  133  comprises a lower electrode  145  formed on the lower substrate  21  and an upper electrode  146  formed on the upper substrate  22 . Both ends of the upper electrode  146  and one end of the lower electrode  145  are connected with the interface circuit substrate  112  through the flexible wiring board  151 . 
   The second position detection unit in the Y-axis direction  134  is mounted separately from the input domain  121  at the outside of the upper-left edge of the input domain  121  on the touch panel  111 , and is lengthened in the Y-axis directions. The second position detection unit in the Y-axis directions  134  comprises a lower electrode  147  formed on the lower substrate  21  and an upper electrode  148  formed on the upper substrate  22 . Both ends of the upper electrode  148  and one end of the lower electrode  147  are connected with the interface circuit substrate  112  through the flexible wiring board  151 . 
     FIG. 5  is a block diagram illustrating the structure of the interface circuit substrate  112 . 
   The interface circuit substrate  112  comprises a panel driver switching circuit  311 , a noise filter  312 , a control IC  313 , a ROM  314  and an interface driver circuit  315 . 
   The panel driver switching circuit  311  has applied a source voltage of Vcc and receives a switching control signal from the control IC  313 . The panel driver switching circuit  311  controls an action of the touch panel on the basis of the switching control signal from the control IC  313 . 
     FIG. 6  is a diagram illustrating the circuit structure of the panel driver switching circuit  311 . 
   The panel driver switching circuit  311  comprises a coordinate detection circuit  410  and a coordinate detection circuit for correction  420 . The coordinate detection circuit  410  comprises transistors Tr 1  through Tr 6  and Tr 11  through Tr 14 . 
   When a coordinate in the X-axis directions is detected, the transistors Tr 1 , Tr 3  and Tr 5  turn on and the transistors Tr 2 , Tr 4 , Tr 6  and Tr 11  through Tr 16  turn off. If the transistors Tr 1  and Tr 3  turn on, a predetermined voltage is applied between the electrodes  33  and  34 , thereby causing a potential gradient in the X-axis directions in the conductive film  32  on the lower substrate  21 . Here, when the upper substrate  22  is depressed, the electrode  43  generates a signal corresponding to the depressed position. At this time, the noise filter  312  receives the signal generated by the electrode  43 , because the transistor Tr 5  is on. 
   On the other hand, when a coordinate in the Y-axis directions is detected, the transistors Tr 2 , Tr 4  and Tr 6  turn on and the transistors Tr 1 , Tr 3 , Tr 5  and Tr 11  through Tr 16  turn off. If the transistors Tr 4  and Tr 6  turn on, a predetermined voltage is applied between the electrodes  43  and  44 , thereby causing a potential gradient in the Y-axis directions in the conductive film  32  on the lower substrate  21 . Here, when the upper substrate  22  is depressed, the electrode  33  generates a signal corresponding to the depressed position. At this time, the noise filter  312  receives the signal generated by the electrode  33 , because the transistor Tr 2  is on. 
   Furthermore, the coordinate detection circuit for correction  420  is driven at the time when a correction value is required, for example, at the starting time. The coordinate detection circuit for correction  420  comprises the transistors Tr 11  through Tr 16 . 
   When the correction value is gained, the transistors Tr 11  and Tr 12  turn on, thereby applying a predetermined voltage of Vcc to both ends of the electrodes  141 ,  143 ,  145  and  147 . At the result, a potential gradient is caused in each of the electrodes  141 ,  143 ,  145  and  147   
   At this time, protrusions formed in the front case  200  depress predetermined positions of the electrodes  142 ,  144 ,  146  and  148 , whereby the electrode  142  contacts with the electrode  141 , the electrode  144  contacts with the electrode  143 , the electrode  146  contacts with the electrode  145  and the electrode  148  contacts with the electrode  147 . 
   If the transistor Tr 13  turns on and the transistors Tr 14  through Tr 16  turn off, a first coordinate in the X-axis directions is detected. If the transistor Tr 14  turns on and the transistors Tr 13 , Tr 15  and Tr 16  turn off, a first coordinate in the Y-axis directions is detected. If the transistor Tr 15  turns on and the transistors Tr 13 , Tr 14  and Tr 16  turn off, a second coordinate in the X-axis directions is detected. If the transistor Tr 16  turns on and the transistors Tr 13  through Tr 15  turn off, a second coordinate in the Y-axis directions is detected. 
     FIG. 7  is a diagram illustrating a circuit structure of parts according to a variation of the first embodiment of the present invention. In  FIG. 7 , parts that are the same as the parts shown in  FIG. 3  and  FIG. 4  are given the same reference numerals, and descriptions thereof will be omitted. 
   In the variation, the first position detection unit in the X-axis directions  131  and the first position detection unit in the Y-axis directions  132  share a terminal. 
   In the variation, diodes D 1  and D 2  have mutually homopolar connections with both ends of the electrode  141 , and diodes D 3  and D 4  have mutually homopolar connections with both ends of the electrode  143 . A driver switching circuit for correction  431 , which is a portion of the panel driver switching circuit  311 , controls power supply to the electrodes  141  and  143 , and detects an electric potential of common wiring  432  connecting the electrodes  142  and  144 . 
   The driver switching circuit for correction  431  comprises transistors Tr 21 , Tr 22 , Tr 23  and Tr 24 . If the transistors Tr 22  and Tr 23  turn on and the transistors Tr 21  and Tr 24  turn off, the diodes D 1  and D 2  turn on, thereby causing an electric gradient between both ends of the electrode  141 . At a result, the electrode  142  has an electric potential according to a protrusion  211  in the front case  200 . At this time, an electric potential of the electrode  144  is not generated, because the diodes D 3  and D 4  turn off. Thus, an electric potential of the common wiring  432  turns into the electric potential of the electrode  142 . The detection of the electric potential of the common wiring  432  makes it possible to detect a first position in the X-axis directions. 
   On the other hand, if the transistors Tr 21  and Tr 24  turn on and the transistors Tr 22  and Tr 23  turn off, the diodes D 3  and D 4  turn on, thereby causing an electric gradient between both ends of the electrode  143 . At a result, the electrode  144  has an electric potential according to a protrusion  212  in the front case  200 . At this time, an electric potential of the electrode  142  is not generated, because the diodes D 1  and D 2  turn off. Thus, an electric potential of the common wiring  432  turns into the electric potential of the electrode  143 . The detection of the electric potential of the common wiring  432  makes it possible to detect a first position in the Y-axis directions. 
     FIG. 7  mainly illustrates a structure of the variant of the first position detection unit in the X-axis direction  131  and the first position detection unit in the Y-axis direction  132 . However, if the second position detection unit in the X-axis directions  133  and the second position detection unit in the Y-axis direction  134  are constructed similarly to the above-mentioned structure, it is possible to detect the second position in the X-axis directions and the second position in the Y-axis directions. 
   The noise filter  312  is connected with the panel driver switching circuit  311  and receives a signal from an electrode selected by the panel driver switching circuit  311 . The noise filter  312  removes noise out of the signal generated by the electrode selected by the panel driver switching circuit  311 . Thereafter, the control IC  313  receives the noise-free signal processed by the noise filter  312 . 
   The control IC  313  provides the panel driver switching circuit  311  with a switching control signal and converts a signal from the noise filter  312  into digital data to execute a variety of processes. The control IC  313  executes the processes by using programs saved in the ROM  314 . 
     FIG. 8  is a flowchart of a correction process program executed by the control IC  313 . 
   After making power supply at the step S 1 - 1 , the control IC  313  is initialized at the step S 1 - 2 . 
   At the step S 1 - 3 , the control IC  313  detects a first coordinate in the X-axis directions. If the transistors Tr 1  through Tr 6  and Tr 14  through Tr 16  in the panel driver switching circuit  311  turn off and the transistors Tr 11  through Tr 13  in the panel driver switching circuit  311  turn on, an electric potential of the electrode  142  is detected, whereby the first coordinate in the X-axis directions is detected. 
   At the step S 1 - 4 , the control IC  313  detects misalignment of the touch panel  111  in the X-axis directions on the basis of the first coordinate in the X-axis directions. An amount of the misalignment in the X-axis directions is computed as a difference between the first coordinate in the X-axis directions Xa that has been detected at the step S 1 - 3  and the position coordinate XA of the protrusion  211  in the front case  200 . 
   At the step S 1 - 5 , the control IC  313  detects a first coordinate in the Y-axis directions. If the transistors Tr 1  through Tr 6 , Tr 13 , Tr 15  and Tr 16  in the panel driver switching circuit  311  turn off and the transistors Tr 11 , Tr 12  and Tr 14  in the panel driver switching circuit  311  turn on, an electric potential of the electrode  144  is detected, whereby the first coordinate in the Y-axis directions is detected. 
   At the step S 1 - 6 , the control IC  313  detects misalignment of the touch panel  111  in the Y-axis directions on the basis of the first coordinate in the Y-axis directions. An amount of the misalignment in the Y-axis directions is computed as a difference between the first coordinate in the Y-axis directions Ya that has been detected at the step S 1 - 4  and the position coordinate YA of the protrusion  212  of the front case  200 . 
   At the step S 1 - 7 , the control IC  313  detects a second coordinate in the X-axis directions Xb. If the transistors Tr 1  through Tr 6 , Tr 13 , Tr 14  and Tr 16  in the panel driver switching circuit  311  turn off and the transistors Tr 11 , Tr 12  and Tr 15  in the panel driver switching circuit  311  turn on, an electric potential of the electrode  146  is detected, whereby the second coordinate in the X-axis directions Xb is detected. 
   At the step S 1 - 8 , the control IC  313  detects a second coordinate in the Y-axis directions Yb. If the transistors Tr 1  through Tr 6  and Tr 13  through Tr 15  in the panel driver switching circuit  311  turn off and the transistors Tr 11 , Tr 12  and Tr 16  in the panel driver switching circuit  311  turn on, an electric potential of the electrode  148  is detected, whereby the second coordinate in the Y-axis directions Yb is detected. 
   At the step S 1 - 9 , the control IC  313  computes a rotation angle θ of the touch panel  111  with the front case  200 . The rotation angle of the touch panel  111  to the front case  200  is computed on the basis of an amount of misalignment of the first coordinate in the X-axis directions Xa, the second coordinate in the X-axis directions Xb, the first coordinate in the Y-axis directions Ya and the second coordinate in the Y-axis directions Yb with the protrusions  211  through  214  of the front case  200 . For example, if a reference table of rotation angles according to amounts of misalignment is prepared, the rotation angle θ is gained by referring to the table. 
   At the step S 1 - 10 , the control IC  313  saves the amount of misalignment in the X-axis directions ΔX computed at the step S 1 - 4 , the amount ΔY of misalignment in the Y-axis directions computed at the step S 1 - 6  and the rotation angle θ computed at the step S 1 - 9  in its internal register and others. 
   Based on the amount of misalignment in the X-axis directions ΔX, the amount ΔY of misalignment in the Y-axis directions and the rotation angle θ that have been saved at the step S 1 - 10 , the control IC  313  corrects coordinate information provided by the touch panel  111  at a normal coordinate detection. The corrected coordinate information is delivered to the interface driver circuit  315 . The interface driver circuit  315  converts the coordinate information from the control IC  313  in a predetermined interface form, and delivers it to the information processing unit  5 . The information processing unit  5  comprises a computer and others, wherein the driver software  320  is installed. On the basis of the coordinate information provided by the input device  100 , the information processing unit  5  controls the position of a pointer and others, and an execution of an application by driver software  320 . 
   In this embodiment of the present invention, the correction is executed through the interface circuit substrate  112 . On the other hand, the above-mentioned correction may be executed through the driver software  320  installed in the information processing unit  5 . 
   A description of a second embodiment of the present invention will now be given. 
     FIG. 9  is a diagram illustrating a structure of an input device according to a second embodiment of the present invention. In  FIG. 9 , parts that are the same as the parts shown in  FIG. 4  are given the same reference numerals, and descriptions thereof will be omitted. 
   An input device  500  according to the second embodiment of the present invention detects deterioration of a conductive film over time and carries out a correction. The input device  500  comprises a touch panel  511  and an interface circuit substrate  512 . 
   The touch panel  511  according to the second embodiment of the present invention contains cables to connect a lower substrate  521  with the touch panel  511  and the interface circuit substrate  512 . Namely, the touch panel  511  has first connection pads  541 ,  542 ,  543  and  544  connected with an input and output terminal of a flexible wiring board  531 , and second connection pads  551 ,  552 ,  553  and  554  connected with the first connection pad  541  so as to have a connection with an internal circuit of the touch panel  511 . The first connection pad  541  is connected with the second connection pad  551  through a connection pattern  561  formed on the lower substrate  521 . The first connection pad  542  is connected with the second connection pad  552  through a connection pattern  562  formed on the lower substrate  521 . The first connection pad  543  is connected with the second connection pad  553  through a connection pattern  563  formed on the lower substrate  521 . The first connection pad  544  is connected with the second connection pad  554  through a connection pattern  564  formed on the lower substrate  521 . 
   The flexible wiring board  531  contains first wirings  571  through  574  and second wirings  581  through  584 . The first wirings  571  through  574  are connected with the first connection pads  541  through  544  to input and output signals to the internal circuit of the touch panel  511 . The second wirings  581  through  584  are connected with the second connection pads  551  through  554  so as to detect electric potentials of the second connection pads  551  through  554 . 
   The first wiring  571  is connected with the first connection pad  541  formed on the lower substrate  521 . The first wiring  572  is connected with the first connection pad  542  formed on the lower substrate  521 . The first wiring  573  is connected with the first connection pad  543  formed on the lower substrate  521 . The first wiring  574  is connected with the first connection pad  544  formed on the lower substrate  521 . 
   The second wiring  581  is connected with the second connection pad  551  formed on the lower substrate  521 . The second wiring  582  connected with the second connection pad  552  formed on the lower substrate  521 . The second wiring  583  connected with the second connection pad  553  formed on the lower substrate  521 . The second wiring  584  connected with the second connection pad  554  formed on the lower substrate  521 . 
   Also, the interface substrate  512  differs from that of the first embodiment in processes executed by the control IC  313 . The control IC  313  detects electric potentials of the second connection pads  551  through  554  by the second wirings  581  through  584 , and determines wiring conditions of the touch panel  511  and the flexible wiring board  531 . If the wiring conditions of the touch panel  511  and the flexible wiring board  531  are determined to be in disorder, the control IC  313  delivers an alarm to the information processing unit  5 . Also, the control IC  313  corrects a coordinate detection result relating to the touch panel  511 , which is delivered to the information processing unit  5 . 
   Processes executed in the control IC  313  will now be explained. 
     FIG. 10  is a flowchart of an input device according to the second embodiment of the present invention. 
   At the step S 2 - 1 , the input device is started. At the step S 2 - 2 , the control IC  313  applies a predetermined voltage to the first wirings  571  through  574 , and detects electric potentials of the second wirings  581  through  584 . Based on a voltage decreasing between the first wirings  571  through  574  and the second wirings  581  through  584 , the control IC  313  detects resistances ΔR 1  through ΔR 4  between the first connection patterns  541  through  544  and the second connection patterns  551  through  554 . At the step S 2 - 3 , the control IC  313  determines whether the resistances ΔR 1  through ΔR 4  gained at the step S 2 - 2  are in disorder or not. For example, in the case that the resistances ΔR 1  through ΔR 4  do not fall in a predetermined range, the resistances ΔR 1  through ΔR 4  are determined to be in disorder. 
   If the resistances ΔR 1  through ΔR 4  are determined to be in disorder at the step S 2 - 3 , the control IC  313  delivers an alarm to the information processing unit  5  at the step S 2 - 4 . On the other hand, if the resistances ΔR 1  through ΔR 4  are determined not to be in disorder at the step S 2 - 3 , the control IC  313  saves values of the resistances ΔR 1  through ΔR 4  and performs normal coordinate detection. Under the normal coordinate detection, the control IC  313  reads a coordinate x in the X-axis directions and a y coordinate in the Y-axis directions from the touch panel  111  at the step S 2 - 5 . 
   From the coordinate x in the X-axis directions read at the step S 2 - 6 , the control IC  313  gains a corrected coordinate X in the X-axis directions and a corrected coordinate Y in the Y-axis directions, where the corrected coordinate X in the X-axis directions is involved in coordinate information resulting from correcting the coordinate x in the X-axis directions on the basis of the resistances ΔR 1  through ΔR 4 . 
   At the step S 2 - 7 , the control IC  313  delivers the coordinate x in the X-axis directions and the y coordinate in the Y-axis directions to the information processing unit  5 . 
   According to the second embodiment of the present invention, it is possible to detect conditions of patterns on the touch panel  511  and perform accurate coordinate detection, because the detected coordinates are corrected on the basis of the pattern conditions. Especially, even if the touch panel  511  deteriorates over time, it is always possible to perform accurate coordinate detection through the correction of the touch panel  511 . 
   Furthermore, when it becomes impossible to correct the touch panel  511 , the alarm is delivered and indicates that the touch panel  511  has reached its limit. Accordingly, the touch panel  511  can be exchanged before malfunction, and it is always possible to carry out an input operation in a satisfactory condition. 
   The present invention is not limited to the specifically disclosed embodiments, and variations and modifications may be made without departing from the scope of the present invention. 
   The present application is based on Japanese priority application No. 2002-081588 filed Mar. 22, 2002, the entire contents of which are hereby incorporated by reference.