Abstract:
According to one embodiment, there is provided an input apparatus comprising a key that is displaceable along a direction; a first detecting circuit that comprises an electrostatic capacitance sensor that detects a variation of an electrostatic capacitance caused by a contact or a proximity of a pressing body with the key; and a second detecting circuit that comprises a first electrode, the second detecting circuit detecting an electric connection of the first electrode to a second electrode that is displaced along the direction as the key is displaced, wherein the input apparatus switches a detecting status thereof exclusively between a first detecting status and a second detecting status to each other in accordance with a displacement variation of the key.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is based upon and claims the benefit of priority from Japanese Patent Applications No. 2015-247182, filed Dec. 18, 2015; No. 2016-192554, filed Sep. 30, 2016; and No. 2016-211534, filed Oct. 28, 2016, the entire contents of all of which are incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The technical field relates to an input apparatus and an electronic apparatus. 
         [0004]    2. Description of the Related Art 
         [0005]    For example, as disclosed in Jpn. Pat. Appin. KOKAI Publication No. 2010-74689, there is conventionally known an electronic apparatus including an input apparatus. The input apparatus includes first detecting means for detecting a key which is touched, and second detecting means for detecting a key on which an operation of displacing a key state was executed. 
         [0006]    In the input apparatus of the conventional electronic apparatus, as a matter of course, when an operation of touching a key is executed, the touch operation is detected by the first detecting means. However, even when an operation of depressing the key is executed (see  FIG. 3(C)  of patent document  3 ), the touch operation is detected by the first detecting means. In other words, it was necessary to adopt such a configuration that even while the key is being displaced in the direction of key depression, a variation of an electrostatic capacitance caused by the key touch operation can be detected. Consequently, the degree of freedom was restricted at a time of designing an input apparatus which can detect both a touch operation on each key and a depression operation on each key. 
       BRIEF SUMMARY OF THE INVENTION 
       [0007]    According to an aspect of the present invention, there is provided an input apparatus comprising: a key that is displaceable along a direction; a first detecting circuit that comprises an electrostatic capacitance sensor that detects a variation of an electrostatic capacitance caused by a contact or a proximity of a pressing body with the key; and a second detecting circuit that comprises a first electrode, the second detecting circuit detecting an electric connection of the first electrode to a second electrode that is displaced along the direction as the key is displaced, wherein the input apparatus switches a detecting status thereof exclusively between a first detecting status and a second detecting status to each other in accordance with a displacement variation of the key, the first detecting status being a status where the variation of the electrostatic capacitance is detected by the first detecting circuit and, at the same time, the electric connection is not detected by the second detecting circuit, the second detecting status being a status where the variation of the electrostatic capacitance is not detected by the first detecting circuit and, at the same time, the electric connection is detected by the second detecting circuit. 
         [0008]    According to another aspect of the invention, there is provided an electronic apparatus comprising: an input apparatus; and a processor, wherein the input apparatus comprises: a key that is displaceable along a direction; a first detecting circuit that comprises an electrostatic capacitance sensor that detects a variation of an electrostatic capacitance caused by a contact or a proximity of a pressing body with the key; and a second detecting circuit that comprises a first electrode, the second detecting circuit detecting an electric connection of the first electrode to a second electrode that is displaced along the direction as the key is displaced, wherein the input apparatus switches a detecting status thereof exclusively between a first detecting status and a second detecting status to each other in accordance with a displacement variation of the key, the first detecting status being a status where the variation of the electrostatic capacitance is detected by the first detecting circuit and, at the same time, the electric connection is not detected by the second detecting circuit, the second detecting status being a status where the variation of the electrostatic capacitance is not detected by the first detecting circuit and, at the same time, the electric connection is detected by the second detecting circuit, and wherein the processor executes at least one function in accordance with detection results by the first detecting circuit and the second detecting circuit. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         [0009]    The components in the drawings are not necessarily scale relative to each other. 
           [0010]      FIG. 1  is a plan view illustrating an electronic calculator  10  as an input apparatus according to an embodiment of the present invention. 
           [0011]      FIG. 2  is a view illustrating a numeric key  110  of an input section  11  of the electronic calculator  10  according to the embodiment of the invention, part (A) of  FIG. 2  being a plan view of the numeric key  110 , part (B) of  FIG. 2  being a II-II cross-sectional view illustrating a key structure of the numeric key  110  at a touch operation detection time, and part (C) of  FIG. 2  being a II-II cross-sectional view illustrating a key structure of the numeric key  110  at a stroke operation detection time. 
           [0012]      FIG. 3  is a transparent plan view illustrating a conductor pattern on a touch detection sheet  120  of the electronic calculator  10  according to the embodiment of the invention. 
           [0013]      FIG. 4  is a block diagram of the electronic calculator  10  according to the embodiment of the invention. 
           [0014]      FIG. 5  is a flowchart illustrating an input operation detection process using the electronic calculator  10  according to the embodiment of the invention. 
           [0015]      FIG. 6  illustrates a data structure of touch input patterns stored in a storage unit  400  of the electronic calculator  10  according to the embodiment of the invention. 
           [0016]      FIG. 7  is a view illustrating an example of a user operation using the electronic calculator  10  according to the embodiment of the invention. 
           [0017]      FIG. 8  is a transparent plan view illustrating a conductor pattern on a touch detection sheet  120  of an electronic calculator  10 A according to a first modification of the invention. 
           [0018]      FIG. 9  is a cross-sectional view corresponding a II-II cross-sectional view of an electronic calculator  10 B according to a second modification of the invention, part (A) of  FIG. 9  being a plan view of a numeric key  110 , and part (B) of  FIG. 9  being a II-II cross-sectional view illustrating a key structure of the numeric key  110  at a touch operation detection time. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0019]    To begin with, an embodiment of the present invention will be described with reference to  FIG. 1  to  FIG. 7 . 
         [0020]      FIG. 1  is a plan view illustrating an electronic calculator  10  as an input apparatus according to the embodiment of the invention.  FIG. 2  is a view illustrating a numeric key  110  of an input section  11  of the electronic calculator  10  according to the embodiment of the invention, part (A) of  FIG. 2  being a plan view of the numeric key  110 , part (B) of  FIG. 2  being a II-II cross-sectional view illustrating a key structure of the numeric key  110  at a touch operation detection time (first detecting status), and part (C) of  FIG. 2  being a II-II cross-sectional view illustrating a key structure of the numeric key  110  at a stroke operation detection time (second detecting status). 
         [0021]    As illustrated in  FIG. 1 , the electronic calculator  10  includes an input section  11 , a display  12  and a solar cell panel  13 . The input section  11  includes keys such as an all-clear key [AC], a clear key [C], a plus/minus switching key [+/−], numeric keys [ 0 ] to [ 9 ], and arithmetic keys [+], [−], [×], [÷] and [=]. Each of the keys is configured to be displaceable in a certain direction (a direction perpendicular to the drawing sheet of  FIG. 1 ), and is a stroke key, the stroke of which is detectable. Of the numeric keys [ 0 ] to [ 9 ], nine numeric keys [ 1 ] to [ 9 ]  110  are arranged in a matrix of 3×3. In addition, these numeric keys [ 1 ] to [ 9 ]  110  function not only as the stroke keys, but also as touch keys. 
         [0022]    As illustrated in the cross-sectional views of parts (B) and (C) of  FIG. 2 , a key structure of the input section  11  includes the numeric key  110 , a touch detection sheet  120 , a key urging sheet  130 , and a substrate  140 . 
         [0023]    The numeric key  110  is formed of a material with electrical conductivity, such as a conductive metal. As illustrated in part (A) of  FIG. 2 , the numeric key  110  includes, in plan view, a key top  111  at a central part thereof, and a square-shaped collar portion  112  at a peripheral part thereof, the square-shaped collar portion  112  surrounding the four sides of the key top  111 . In addition, a numeral, which is unique to this numeric key, is printed on an upper surface of the key top  111 . In part (A) of  FIG. 2 , although the numeric key [ 9 ]  110  is illustrated and described, the other numeric keys [ 1 ]  110  to [ 8 ]  110  are the same as the numeric key [ 9 ]  110 , except for the content of printing on the key top  111 . In the description below in this specification, in some cases, each of the “numeric keys [ 1 ] to [ 9 ]  110 ” is referred to simply as “numeric key  110 ”. 
         [0024]    The touch detection sheet  120  includes an insulation sheet  121  and a conductor pattern (see  FIG. 3 ). The insulation sheet  121  is provided with a plurality of holes  121   h,  through which the respective numeric keys  110  are inserted. The conductor pattern includes two touch detection electrodes  122 R and  122 L formed at least at positions at a peripheral edge of each hole  121   h  under the insulation sheet  121 , these positions corresponding to two opposed sides of the square-shaped collar portion  112 . The conductor pattern further includes wiring lines  123 R and  123 L which are connected to the touch detection electrodes  122 R and  122 L. 
         [0025]    The key urging sheet  130  is formed of an elastic member of rubber or the like. The key urging sheet  130  includes a base portion  131  and a key pushing-up portion  132 . The base portion  131  has, as a whole, a substantially rectangular shape in plan view. The key pushing-up portion  132  is formed in such a shape that a part overlapping each numeric key  110  in the substantially rectangular shape is raised upward (to a side on which each numeric key  110  is disposed relative to the key urging sheet  130 ). The key pushing-up portion  132  includes an abutment portion  133  which is disposed immediately under the numeric key  110 , and a skirt portion  134  which deforms in accordance with a stroke operation of the numeric key  110  and causes such an elastic repulsive force as to urge upward the abutment portion  133  and numeric key  110 . A counter-electrode  135  is provided on a lower surface (a surface facing an upper surface of the substrate  14 ) of the abutment portion  133 . 
         [0026]    The substrate  140  includes an insulative base portion  141 , and electrodes, wiring lines, electronic components, etc. which are formed on an upper surface of the base portion  141 . In particular, a stroke detection electrode (first electrode)  142  is provided on that part of the upper surface of the base portion  141 , which is opposed to each counter-electrode  135  of the key urging sheet  130 . 
         [0027]    Referring to parts (B) and (C) of  FIG. 2 , a brief description is given of each key structure at a touch operation detection time and at a scroll operation detection time. As illustrated in part (B) of  FIG. 2 , a touch operation is detected in a state in which a stroll operation of the numeric key  110  is not executed. In this state, the key urging sheet  130  retains its original shape by the elastic repulsive force which the material of the key urging sheet  130  has. Thereby, the upper surface of the abutment portion  133  of the key pushing-up portion  132  abuts on the lower surface of the numeric key  110  (i.e. pushes the lower surface of the numeric key  110 ) and supports the lower surface of the numeric key  110 , and puts the upper surfaces of the two opposed sides of the collar portion  112  in contact with the touch detection electrodes  122 R and  122 L of the touch detection sheet  120 . The key top  111  is connected to one of electrostatic capacitance sensor which a touch detecting circuit (first detecting circuit)  211  (see  FIG. 4 ) includes, via the collar portion  112  and the touch detection electrode  122 R, and is connected to another of the electrostatic capacitance sensors which the touch detecting circuit  211  includes, via the collar portion  112  and the touch detection electrode  122 L. A structure that comprises the key top  111 , the collar portion  112 , the touch detection electrodes  122 R,  122 L, and the touch detecting circuit  211  having the electrostatic capacitance sensors is, hereinafter, referred to as a touch operation detector  210 . 
         [0028]    On the other hand, if a user pushes, by a fingertip, the key top  111  against the elastic repulsive force of the key urging sheet  130 , the numeric key  110  displaces downward along a stroke direction of the numeric key  110  (an up-and-down direction in part (C) of  FIG. 2 ). If the stroke displacement variation of the numeric key  110  by this stroke operation (the amount of movement of the numeric key  110  in the up-and-down direction in parts (B) and (C) of  FIG. 2 ) reaches a certain degree, the counter-electrode  135  of the key urging sheet  130  and the stroke detection electrode  142  of the substrate  140  come in contact with each other, as illustrated in part (C) of  FIG. 2 , and the stroke operation is detected. At this time, the collar portion  112  is spaced apart from the touch detection electrodes  122 R and  122 L, and an electric connection via these components between the key top  111  and the above-described two electrostatic capacitance sensors is released. 
         [0029]      FIG. 3  is a transparent plan view illustrating the touch detection electrodes  122  and wiring lines  123  of the conductor pattern on the touch detection sheet  120  of the electronic calculator  10  according to the embodiment of the invention. In  FIG. 3 , the arrangement of the conductor pattern, as viewed from above the electronic calculator  10  (from the viewer side of the drawing sheet) is depicted as a transparent plan view. However, the actual conductor pattern is formed below the insulation sheet  121  (on the side where the key urging sheet  130  and substrate  140  are disposed relative to the insulation sheet  121 ). The touch detection sheet  120  includes a substantially rectangular key hole formation portion in which nine rectangular holes  121   h   1  to  121   h   9  are provided in a matrix of 3×3; a led-out wiring formation portion extending with a small width from a lower right part of the key hole formation portion; and an electrostatic capacitance sensor formation section (not shown) which is connected to a distal end of the led-out wiring formation portion and in which the electrostatic capacitance sensors are provided. In the description below in this specification, when a feature common to all holes is described, there is a case in which the individual holes are not distinguished and are referred to as “hole  121   h”.    
         [0030]    At a peripheral edge of each hole  121   h,  two touch detection electrodes  122 R and  122 L are provided in a manner to surround this hole. The right-side touch detection electrode  122 R has a right square bracket (]) shape in plan view, and is provided to come in contact with the entire length of the right side of the hole  121   h  and with the right-side parts of the upper and lower sides of the hole  121   h.  The left-side touch detection electrode  122 L has a left square bracket ([) shape in plan view, and is provided to come in contact with the entire length of the left side of the hole  121   h  and with the left-side parts of the upper and lower sides of the hole  121   h.  The two touch detection electrodes  122 R and  122 L are spaced apart at mutually neighboring parts on the upper and lower sides of the hole  121   h.  The right-side touch detection electrode  122 R is connected to one of the electrostatic capacitance sensors via the wiring line  123 R, and the left-side touch detection electrode  122 L is connected to another of the electrostatic capacitance sensors via the wiring line  123 L. 
         [0031]    In addition, right-side touch detection electrodes of three holes  121   h  arranged in a row direction (the left-and-right direction in the drawing), for example, right-side touch detection electrodes  122 R 7 ,  122 R 8  and  122 R 9  of three holes  121   h   7 ,  121   h   8  and  121   h   9  of the uppermost row, are connected by one wiring line  123 R 3  in parallel to each other to a third row position-detecting electrostatic capacitance sensor  212 C (see  FIG. 4 ). Similarly, as regards the middle row, right-side touch detection electrodes  122 R 4 ,  122 R 5  and  122 R 6  of three holes  121   h   4 ,  121   h   5  and  121   h   6  are connected by one wiring line  123 R 2  in parallel to each other to a second row position-detecting electrostatic capacitance sensor  212 B. The same applies to the lowermost row, and right-side touch detection electrodes  122 R 1 ,  122 R 2  and  122 R 3  of three holes  121   h   1 ,  121   h   2  and  121   h   3  are connected by one wiring line  123 R 1  in parallel to each other to a first row position-detecting electrostatic capacitance sensor  212 A. 
         [0032]    On the other hand, left-side touch detection electrodes of three holes  121   h  arranged in a column direction (the up-and-down direction in the drawing), for example, if the rightmost column is described, left-side touch detection electrodes  122 L 9 ,  122 L 6  and  122 L 3  of three holes  121   h   9 ,  121   h   6  and  121   h   3 , are connected by one wiring line  123 L 3  in parallel to each other to a third row position-detecting electrostatic capacitance sensor  213 C (see  FIG. 4 ). The same applies to the middle column and the leftmost column. Left-side touch detection electrodes  122 R 8 ,  122 R 5  and  122 R 2  of three holes  121   h   8 ,  121   h   5  and  121   h   2  are connected by one wiring line  123 L 2  in parallel to each other to a second column position-detecting electrostatic capacitance sensor  213 B, and left-side touch detection electrodes  122 L 7 ,  122 L 4  and  122 L 1  of three holes  121   h   7 ,  121   h   4  and  121   h   1  are connected by one wiring line  123 L 1  in parallel to each other to a first column position-detecting electrostatic capacitance sensor  213 A. 
         [0033]    These six electrostatic capacitance sensors, namely the above-described first to third row position-detecting electrostatic capacitance sensors  212 A,  212 B and  212 C and first to third column position-detecting electrostatic capacitance sensors  213 A,  213 B and  213 C, are electrostatic capacitance sensors. These electrostatic capacitance sensors are mutually different, and each can independently detect a variation of an electrostatic capacitance. The six wiring lines  123 R 1 ,  123 R 2 ,  123 R 3 ,  123 L 1 ,  123 L 2  and  123 L 3  are extended to the corresponding electrostatic capacitance sensors provided in the electrostatic capacitance sensor formation section, from between the plural holes  121   h  in the key hole formation portion via the led-out wiring formation portion. 
         [0034]    A description is given of an operation at a touch operation detection time in the key structure of the electronic calculator  10  of the above-described embodiment. The description below is given by taking, as an example, an operation in the case in which a touch operation was executed on any one of the plural numeric keys  110 , to be more specific, the numeric key [ 9 ]  110 . However, the same operation applies to other numeric keys  110 . In this specification, a status (first detecting status) in which a user&#39;s fingertip or the like is in contact with the numeric key  110  or the user&#39;s fingertip or the like is in close proximity to the numeric key  110  to such a position that a variation of an electrostatic capacitance is detectable by the electrostatic capacitance sensor, and in which the collar portion  112  of the numeric key  110  and the touch detection electrode  122 R,  122 L of the touch detection sheet  120  are in contact with each other, is defined as a status in which a touch operation was executed. At the time of this status, that is, at the touch operation detection time, the stroke displacement variation of the numeric key  110  is zero. In addition, the key structure at this time is as illustrated in part (B) of  FIG. 2 , and the counter-electrode  135  of the key urging sheet  130  and the stroke detection electrode  142  of the substrate  140  are spaced apart. 
         [0035]    If a touch operation is executed on the key top  111  of the numeric key [ 9 ]  110 , a variation of an electrostatic capacitance is detected by the third row position-detecting electrostatic capacitance sensor which is connected to the key top  111  of the numeric key [ 9 ] via the collar portion  112 , right-side touch detection electrode  122 R 9  and wiring line  123 R 3 . At the same time, a variation of an electrostatic capacitance is detected by the third column position-detecting electrostatic capacitance sensor which is connected to the key top  111  of the numeric key [ 9 ] via the collar portion  112 , left-side touch detection electrode  122 L 9  and wiring line  123 L 3 . 
         [0036]    In this manner, if a touch operation is executed on any one of the plural keys  110 , a variation of an electrostatic capacitance is detected by two of the six electrostatic capacitance sensors, and it can be detected which of the numeric keys  110  was touch-operated, based on the combination of two electrostatic capacitance sensors by which the variation was detected. Specifically, when the variation of the electrostatic capacitance was detected by the third row position-detecting electrostatic capacitance sensor and the third column position-detecting electrostatic capacitance sensor, the touched key can be specified by determining that the touch operation was executed on the numeric key [ 9 ]  110 . In addition, when the variation of the electrostatic capacitance was detected by the third row position-detecting electrostatic capacitance sensor and the second column position-detecting electrostatic capacitance sensor, it is understood that the touch operation was executed on the numeric key [ 8 ]  110 . Similarly, when the variation of the electrostatic capacitance was detected by the first row position-detecting electrostatic capacitance sensor and the first column position-detecting electrostatic capacitance sensor, it is understood that the touch operation was executed on the numeric key [ 1 ]  110 . In this manner, in the present embodiment, if six wiring lines are provided, it can be determined which of the nine numeric keys [ 1 ] to [ 9 ]  110  was touched. 
         [0037]    Next, a description is given of, by way of example, an operation in the case in which a stroke operation was executed on any one of the plural numeric keys  110 , to be more specific, the numeric key [ 9 ]  110 . However, the same operation applies to other numeric keys  110 . In this specification, a status (second detecting status) in which a user&#39;s fingertip or the like is in contact with the numeric key  110 , and in which the counter-electrode  135  of the key urging sheet  130  and the stroke detection electrode  142  of the substrate  140  are in contact with each other, is defined as a status in which a stroke operation was executed. At the time of this status, that is, at the stroke operation detection time, the stroke displacement variation of the numeric key  110  is a certain magnitude. In addition, the key structure at this time is as illustrated in part (C) of  FIG. 2 , and the collar portion  112  of the numeric key  110  and the touch detection electrode  122 R,  122 L of the touch detection sheet  120  are spaced apart. 
         [0038]    The stroke detection electrode  142  is connected to a stroke detecting circuit (second detecting circuit)  221  (see  FIG. 4 ) via a wiring line (not shown) on the substrate  140 . If the stroke operation is executed on the numeric key [ 9 ]  110 , a contact between the counter-electrode  135  of the key urging sheet  130  and the stroke detection electrode  142  of the substrate  140  is detected by the stroke detecting circuit  221 . A structure that comprises the counter-electrode  135 , the stroke detection electrode  142 , the wiring line on the substrate  140 , and the stroke detecting circuit  221  is, hereinafter, referred to as a stroke operation detector  220 . 
         [0039]    In the meantime, an intermediate status between the first detecting status at the touch operation detection time and the second detecting status at the stroke operation detection time, that is, a status in which the stroke displacement variation of the numeric key  110  is greater than zero and is less that the above-described prescribed amount, the collar portion  112  of the numeric key  110  and the touch detection electrode  122 R,  122 L of the touch detection sheet  120  are spaced apart, and the counter-electrode  135  of the key urging sheet  130  and the stroke detection electrode  142  of the substrate  140  are spaced apart. In this intermediate status, neither the touch operation nor the stroke operation is detected. 
         [0040]    The electronic calculator  10  of the present embodiment has the above-described configuration. Thus, the electronic calculator  10  has such a novel configuration that both of the touch operation and stroke operation on a certain key can be detected, and, when the stroke operation on this key was detected, the detection of the touch operation by the detecting circuit for detecting the touch operation on this key is not executed. 
         [0041]      FIG. 4  is a block diagram of the electronic calculator  10  according to the embodiment of the invention. The electronic calculator  10  includes an input detection unit  200 , a processor (CPU)  300 , a storage unit  400  and a display  500 . 
         [0042]    The input detection unit  200  includes the input section  11 . The input detection unit  200  includes the touch operation detector  210  and the stroke operation detector  220 . The touch operation detector  210  includes a touch detecting circuit  211 . The touch detecting circuit  211  includes the above-described first row position-detecting electrostatic capacitance sensor  212 A, second row position-detecting electrostatic capacitance sensor  212 B, third row position-detecting electrostatic capacitance sensor  212 C, first column position-detecting electrostatic capacitance sensor  213 A, second column position-detecting electrostatic capacitance sensor  213 B, and third column position-detecting electrostatic capacitance sensor  213 C. The stroke operation detector  220  includes the stroke detecting circuit  221 . 
         [0043]    The processor  300  receives signals from the respective components of the electronic calculator  10 , generates control signals on the basis of the received signals, transmits the control signals to the respective components, and controls the respective components by the control signals. 
         [0044]    The storage unit  400  includes a ROM  410  in which control instructions of the electronic calculator  10  are stored, and a RAM  420 . In the RAM  420 , data to be displayed on the display  500  is temporarily stored, and data is temporarily developed for a calculation process by the processor  300 . 
         [0045]    The display  500  displays information such as various calculation results, based on control signals received from the processor  300 . 
         [0046]    At a touch operation detection time, in accordance with the numeric key  110  with which the user&#39;s fingertip was put in contact, or in proximity to which the user&#39;s fingertip was moved, a variation of an electrostatic capacitance is detected by one of the first to third row position-detecting electrostatic capacitance sensors  212 A,  212 B and  212 C and one of the first to third column position-detecting electrostatic capacitance sensors  213 A,  213 B and  213 C. According to whether the variation amount of each electrostatic capacitance is greater than a predetermined threshold or not, the touch detecting circuit  211  transmits a corresponding detection signal to the processor  300 . 
         [0047]    At a stroke operation detection time, in accordance with the numeric key  110  on which the stroke operation was executed, the stroke detecting circuit  221  transmits each corresponding detection signal to the processor  300 . 
         [0048]    Based on the detection signal received from the input detection unit  200 , the processor  300  can detect the numeric key  110  on which the input operation was executed, and the kind of the operation (either the touch operation or the stroke operation) which was executed on the numeric key  110 . 
         [0049]      FIG. 5  is a flowchart illustrating an input operation detection process using the electronic calculator  10  according to the embodiment of the invention. The processor  300  determines, in predetermined cycles (for example, at intervals of  10  ms), whether a detection signal corresponding to either the touch operation or the stroke operation on any one of the keys was received or not.  FIG. 6  illustrates a data structure of information stored in the RAM for specifying functions corresponding to touch operations. This information includes a plurality of numerical sequences {9, 5, 1}, {8, 5, 2}, {7, 5, 3} and {4, 5, 6} as first, second, third and fourth numerical sequences Pi 1 ˜Pi 4  (hereinafter referred to as “touch input patterns Pi 1 ˜Pi 4 ”), and search flags and specific functions, which are associated with the respective numerical sequences. At the time of power-on of the electronic calculator  10 , as one of initializing processes, the search flags are set to “1” for all touch input patterns, and the values of variables i and j (to be described later) are written to 1. 
         [0050]    If a detection signal corresponding to an operation other than a touch operation is received (hereinafter, for the purpose of simple description, the wording “an operation is detected” is used), that is, if a stroke operation is detected (step S 10 : Yes), or if some other operation is detected (step S 10 : No, step S 15 : No, step S 85 : Yes), the processor  300  rewrites the search flags stored in the RAM to “ 1 ” and also rewrites the variable i to 1 (step S 90 , S 95 ), and the processor  300  executes a process corresponding to the detected stroke operation or other operation (step S 100 ). If no operation is detected (step  10 : No, step S 15 : No, step S 85 : No), the present input operation detection process is terminated. Accordingly, if a stroke operation on a key other than the numeric keys [ 1 ] to [ 9 ]  110 , that is, any one of the keys, a touch operation on which is undetectable (e.g. all-clear key [AC], clear key [C], etc.), is detected (step S 10 : Yes), a process corresponding to this stroke operation is executed by the processor  300  (step S 100 ). Although not illustrated, in step S 100 , the processor  300  determines whether the accepted operation is the same as the previous detection result. If the processor  300  determines that the accepted operation is the same as the previous detection result, the processor  300  terminates the present input operation detection process without performing the corresponding process. 
         [0051]    If the processor  300  determines that a stroke operation is not detected but a touch operation is detected (step S 10 : No, step S 15 : Yes), the processor  300  specifies, based on the detection signal, the numeric key on which the touch operation was executed (step S 20 ). At this time, the same numerical value as the number printed on the key top  111  of this numeric key  110  is acquired as key information. The processor  300  determines whether the key information acquired this time is identical to the previously acquired key information (step S 22 ). If the key information acquired this time is identical to the previously acquired key information, the processor  300  terminates the present input operation detection process (step S 22 : Yes). If the key information acquired this time is different from the previously acquired key information (step S 22 : No), the processor  300  then determines whether this key information is one of some predetermined keys. 
         [0052]    Specifically, the processor  300  first acquires a number Ma of registered touch input patterns (step S 25 ) and initializes the variable j (step S 30 ), and then determines whether the search flag is “1” or not, in the order beginning from the first touch input pattern (step S 32 ). If the search flag is “1” (step S 32 : Yes), the processor  300  determines whether the key information acquired in step S 20  is equal to a numerical value Pij of an i-th digit of a j-th pattern from the first one of the touch input patterns stored in the RAM (step S 35 ). If the key information agrees with the numerical value Pij (step S 35 : Yes), the search flag of the j-th pattern is rewritten to “1” (step S 40 ). If the key information disagrees with the numerical value Pij (step S 35 : No), the search flag is rewritten to “0”(step S 45 ). If the search flag is not “1” in step S 32  (step S 32 : No), the processor  300  increments the variable j (step S 33 ) and transitions to a determination process of the search flag of the next touch input pattern (step S 32 ). 
         [0053]    The processor  300  repeats the determination process (step S 35 ) of one or more touch input patterns stored in the RAM and the rewrite process (step S 40 , S 45 ) of the search flag (step S 50 , step S 55 : No). If the processor  300  finishes the processes of all (Ma) touch input patterns (step S 50 , step S 55 : Yes), the processor  300  acquires a number Mb of touch input patterns with the search flag “ 1 ”. If the number Mb is equal to 1 (step S 65 : Yes), the processor  300  executes a specific function which is stored in the RAM in association with the touch input pattern with the search flag “ 1 ”(step S 80 ). If the number Mb is not equal to 1 (step S 65 : No), the processor  300  increments the variable i (step S 75 ) and terminates the present process. 
         [0054]    The above-described input operation detection process is summarized. If the order of touch-operated keys is equal to a pre-registered touch input pattern (step S 10 : No, S 15 : Yes, S 20 , S 25 , S 30 , S 35 : Yes/No, S 40 , S 45 , S 50 , S 55 : Yes/No, S 60 , S 65 : Yes/No, S 70 , S 75 ), the processor  300  executes the specific function corresponding to this pattern (step S 80 ). If an operation other than the touch operation, that is, a stroke operation or other operation, is executed before the order of touch-operated keys becomes equal to a pre-registered touch input pattern (step S 10 : Yes/No, S 15 : No, step S 85 : Yes), the processor  300  initializes the variable for touch input pattern detection (step S 90 , S 95 ), and executes the process associated with this operation (step S 100 ). 
         [0055]    A further description is given based on touch input patterns of concrete examples, which are stored in the RAM.  FIG. 7  is a view illustrating an example of a user operation on the input section  11  of the electronic calculator  10 . A first touch input pattern is {9, 5, 1}. This pattern corresponds to an input operation of sliding a finger in a straight line from the upper right to lower left over a substantially rectangular area in which the numeric keys [ 1 ] to [ 9 ]  110  are arranged. This touch input pattern is associated with a function of calculating a percentage with a numerical value displayed on the display  12 . Similarly, a second touch input pattern is {8, 5, 2}. This pattern corresponds to an input operation of sliding a finger from above to below over the substantially rectangular area. This second touch input pattern is associated with the same function as an [M+] key. A third touch input pattern is {7, 5, 3}. This pattern corresponds to an input operation of sliding a finger from the upper left to lower right over the substantially rectangular area. This third touch input pattern is associated with the same function as an [M−] key. A fourth touch input pattern is {4, 5, 6}. This pattern corresponds to an input operation of sliding a finger from the left to right over the substantially rectangular area. This fourth touch input pattern is associated with the same function as an [MRC] key. 
         [0056]    It is now assumed that a touch operation was detected in the initial state, that is, in the state in which all search flags are “1” and the variable i is 1. If the touched numeric key  110  is any one of [ 9 ], [ 8 ], [ 7 ] and [ 4 ], the search flag of the touch input pattern corresponding to this numeric key is rewritten to “1”. Specifically, if the touched numeric key  110  is [ 9 ], the search flag of the first touch input pattern {9, 5, 1} is rewritten to “1” and the search flags of the second to fourth touch input patterns are rewritten to “0”. Next, it is assumed that a touch operation was detected before a stroke operation or other operation is detected. In this case, if the touched numeric key  110  is not [ 5 ], the search flag of the first touch input pattern {9, 5, 1} is rewritten to “0”. On the other hand, if the touched numeric key  110  is [ 5 ], the value of the search flag of the first touch input pattern {9, 5, 1} is unchanged. Next, it is assumed that a touch operation on the numeric key [ 1 ]  110  was detected before a stroke operation or other operation is detected. In this case, since the touch input pattern agrees with the first touch input pattern {9, 5, 1}, the processor  300  executes the function of calculating a percentage, which is the specific function associated with the first touch input pattern. 
         [0057]    Thereby, in the electronic calculator  10  of the present embodiment, the functions corresponding to at least four keys [M+], [M−], [MRC] and [%] can be executed by touch operations, without providing these keys. Therefore, the input section  11  and the electronic calculator  10  can be reduced in size. In the meantime, the touch input patterns are not limited to straight-line-shaped input operations, and may include various patterns such as “[7]→[4]→[1]→[2]→[3]” (L-shaped input operation) and “[7]→[4]→[1]→[2]→[3]→[6]→[9]” (U-shaped input operation). By associating such touch input patterns with functions of other keys, the functions corresponding to a greater number of keys can be executed by touch operations, without providing these keys. 
       First Modification 
       [0058]      FIG. 8  is a transparent plan view illustrating touch detection electrodes  122  and wiring lines  123  in a conductor pattern on a touch detection sheet  120 A of an electronic calculator  10 A according to a first modification of the invention. The same structural components as in the above-described embodiment are denoted by identical or similar reference numerals, and a description thereof is omitted for the purpose of simple description. In the present modification, only one touch detection electrode  122  is provided at a peripheral edge of each hole  121   h  provided in the touch detection sheet  120 A. In addition, one wiring line  123  is connected to each touch detection electrode  122 . Each wiring line  123  is connected to any one of nine electrostatic capacitance sensors (not shown) which can mutually independently detect variations of electrostatic capacitances. If a touch operation is executed on any one of the key tops  111  of the numeric keys [ 1 ] to [ 9 ]  110 , a variation of an electrostatic capacitance is detected by one of the electrostatic capacitance sensors for detection, which is connected to the key top  111  via the collar portion  112  of the numeric key  110 , one corresponding touch detection electrode  122  and one corresponding wiring line  123 . 
         [0059]    In this manner, in the first modification, the number of electrodes, which are formed in a touch electrode formation portion that is a region where the touch detection electrodes  122  are formed in the touch detection sheet  120 A, and the number of wiring lines extending to these electrodes, can be reduced compared to the above-described embodiment. Thereby, like the above embodiment, the electronic calculator  10 A of this modification has such a novel configuration that both of the touch operation and stroke operation on a certain key can be detected, and, when the stroke operation on this key was detected, the detection of the touch operation by the detecting circuit for detecting the touch operation on this key is not executed. Moreover, the touch electrode formation portion of the touch detection sheet  120 A can be reduced in size, and the degree of freedom of design can be enhanced when the electrodes and the wiring lines extending to the electrodes are formed on the touch electrode formation portion. 
       Second Modification 
       [0060]      FIG. 9  is a cross-sectional view corresponding a II-II cross-sectional view of an electronic calculator  10 B according to a second modification of the invention. Part (A) of  FIG. 9  is a plan view of a numeric key  110 , and part (B) of  FIG. 9  is a II-II cross-sectional view illustrating a key structure of the numeric key  110  at a touch operation detection time. The same structural components as in the above-described embodiment are denoted by identical or similar reference numerals, and a description thereof is omitted for the purpose of simple description. In the present modification, an insulation film  13  is formed by an insulative resin being coated in a manner to cover the entirety of the key top  111  of the numeric key  110 . This insulation film  113  may be, for example, a resin ink which is coated in order to impart a desired color to the surface of the key top  111 , If a touch operation is executed on any one of the key tops  111  of the numeric keys [ 1 ] to [ 9 ]  110 , a variation of an electrostatic capacitance is detected by two of the electrostatic capacitance sensors for detection, which are connected to the key top  111  via the collar portion  112  of the numeric key  110 , two corresponding touch detection electrode  122 R and  122 L and two corresponding wiring line  123 R 3  and  123 L 3 . It can be detected which of the numeric keys  110  was touch-operated, based on the combination of the two electrostatic capacitance sensors by which the variation was detected. If the thickness of the insulation film  113  is large, the variation amount of the electrostatic capacitance, which is detected by the electrostatic capacitance sensors for detection, decreases, and the sensitivity of the touch detecting circuit  211  lowers. It is thus necessary to properly design the thickness so that a proper detection sensitivity can be obtained while a desired color can be imparted. Besides, the insulation film  113  does not need to impart a color. The insulation film  113  may be visually transparent or semitransparent, or may bring about a desired visual or tactual effect by imparting glossness or roughness. 
         [0061]    As described above, like the above embodiment, the electronic calculator  10 B of this second modification has such a novel configuration that both of the touch operation and stroke operation on a certain key can be detected, and, when the stroke operation on this key was detected, the detection of the touch operation by the detecting circuit for detecting the touch operation on this key is not executed. Moreover, a desired color can be imparted to the key top  111 . Needless to say, the second modification is applicable, not only to the case in which two touch detection electrodes  122 R and  122 L are provided to the peripheral edge of each hole  121   h  of the numeric keys [ 1 ] to [ 9 ]  110 , as described above, but also to the case in which only one touch detection electrode  122  is provided to the peripheral edge of each hole  121   h  of the numeric keys [ 1 ] to [ 9 ]  110 , as in the above-described first modification. 
         [0062]    The present invention is not limited to the above-described embodiments. In practice, various modifications may be made without departing from the spirit of the invention. In addition, the embodiments include inventions in various stages, and various inventions can be derived from proper combinations of structural elements disclosed herein. For example, even if some structural elements are omitted from all the structural elements disclosed in the embodiments or some structural elements are combined in other forms, if the problem described in this specification can be solved and the advantageous effects described in this specification can be achieved, the structure, from which such structural elements are omitted or in which such structural elements are combined, can be derived as an invention. 
         [0063]    While various embodiments have been described herein above, it is to be appreciated that various changes in form and detail may be made without departing from the spirit and scope of the invention(s) presently or hereafter claimed.