Abstract:
An apparatus for detecting the displacement of a movable member of an electronic musical instrument. The apparatus has superior mechanical durability compared to displacement sensors of the past and can withstand long-term use. The apparatus includes a sensor that provides a detectable electrical characteristic having a value and a spring that, when compressed upon displacement of the movable member acts with the sensor, causing the value of the electrical characteristic to change. The value of the electrical characteristic represents the amount of displacement of the movable member and is used by a controller of the electronic musical instrument.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
   This application is a divisional application of U.S. patent application Ser. No. 10/982,116, filed Nov. 5, 2004, entitled “Apparatus and Method for Detecting Displacement of a Moveable Member of an Electronic Musical Instrument”, the entire contents of which are incorporated by reference herein. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates, generally, to electronic musical instruments and, in preferred embodiments, to electronic musical instruments having the capability of detecting the amount of displacement of a pedal or of other movable members. 
   2. Description of Related Art 
   In electronic musical instruments, displacement sensors are used as sensors to detect the amount of displacement of, for example, a pedal. 
   Examples of prior methods for the detection of the amount of displacement are described below. 
   Method 1: This is a method in which, for example, a displacement sensor is configured with a rubber sensor that changes shape in conformance with the amount that a pedal is stepped on and a sensor sheet that is pressed by the rubber sensor as the rubber sensor changes shape. The resistance value of the sensor sheet changes in conformance with the area of the sheet that is pressed. 
   Method 2: This is a method in which the resistance value of a volume control changes in conformance with the amount that a pedal is stepped on. 
   The determination of the amount of displacement is possible with the use of any of the methods discussed above. However, in those cases where the displacement of a pedal is detected, the displacement sensor is required to have the durability to withstand the force that is repeatedly applied from the pedal over a long period of time. Each of the methods mentioned above has problems such as those described below. 
   In Method 1, when the rubber sensor is used over a long period of time and its shape is repeatedly changed in conformance with the stepping operation of the pedal, the rubber sensor becomes deformed in shape such that it becomes impossible to accurately detect the amount that the pedal has been stepped on. 
   In Method 2, when the volume control is used for a long period of time, the mechanical sliding portion is abraded and that becomes a problem. 
   SUMMARY OF THE DISCLOSURE 
   Therefore, it is an advantage of embodiments of the present invention to provide an apparatus and method for providing a displacement sensor that has superior mechanical durability and that can withstand use over a long period of time. 
   An embodiment of the present invention that achieves the object described above is characterized in that the displacement sensor is furnished with a sensor structure, such as a sensor sheet, for which the resistance value changes in conformance with the area that has been pressed and a coil spring that has a conical shape. The wider end of said conical shape is in contact with the previously mentioned sensor sheet and increases the area of pressing of said sensor sheet in proportion to the compression of the spring. 
   The coil spring with which an embodiment of the present invention is furnished possesses durability with respect to the compression force that is received from the object that is displaced. In addition, since the displacement sensor is furnished with a structure in which the mechanical rubbing portion that is the cause of abrasion is excluded, the mechanical durability is superior and long-term use is possible. 
   In addition, it is preferable that an embodiment of the present invention be one in which the above mentioned sensor sheet is furnished with a sheet material that possesses electrical conductivity and with an electrode pattern that is disposed opposite the previously mentioned sheet material and is formed by radial segments extending between the center of the sensor sheet and its periphery. 
   The direction over which the cone shaped coil spring presses the sensor sheet as the spring is compressed is from the outer periphery of the sensor sheet toward the center of the sensor sheet. The degree to which the spring presses the sensor sheet is in proportion to the compression of the coil spring. Since the electrode pattern described above is formed along the direction over which the spring presses the sensor sheet, the resistance value of the above mentioned sensor sheet changes with good efficiency due to the compression of the coil spring. 
   As has been explained above, an embodiment of the present invention is superior in mechanical durability compared to the displacement sensors of the past and can withstand use for a long period of time. 
   These and other objects, features, and advantages of embodiments of the invention will be apparent to those skilled in the art from the following detailed description of embodiments of the invention, when read with the drawings and appended claims. 

   
     BRIEF DESCRIPTION OF THE FIGURES 
       FIGS. 1   a  and  1   b  are oblique view drawings that show a first preferred embodiment of the displacement sensor of the present invention; 
       FIGS. 2   a  and  2   b  are drawings that shows the range in which, when the conical coil spring is compressed and changes shape, the printed resistor sheet is pressed and comes into contact with a substrate having a conductive pattern, such as a printed carbon substrate, due to the shape change; 
       FIG. 3  is a lateral drawing that shows a partial cross-section of the state in which the displacement sensor has been mounted in the pedal system of an electronic musical instrument; 
       FIG. 4  is a lateral drawing that shows a partial cross-section of the state in which the displacement sensor has been mounted between the upper cymbal and the lower cymbal of an electronic high hat cymbal; 
       FIGS. 5   a  and  5   b  are lateral drawings that show an enlarged cross-section of the state in which the displacement sensor is mounted between the upper cymbal and the lower cymbal; 
       FIGS. 6   a  and  6   b  are oblique view drawing that show a second preferred embodiment of the displacement sensor of the present invention; 
       FIGS. 7   a  and  7   b  are schematic drawings that show the state in which a portion of the resistive pattern of the base film has come into contact with the metal pattern on the obverse surface of the substrate; and 
       FIG. 8  is a drawing that shows the change in the distance between the contacted portions of the two locations shown in  FIG. 7  that accompanies the increase in the portion of the conical coil spring that is pushed and impacted on by the base film. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   In the following description of preferred embodiments, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the preferred embodiments of the present invention. 
   An explanation will be given below regarding preferred embodiments of the present invention while referring to the drawings. 
   First, an explanation will be given regarding a first preferred embodiment of the present invention. 
     FIGS. 1(   a ) and  1 ( b ) are oblique view drawings that show a first preferred embodiment of the displacement sensor of the present invention. 
     FIG. 1(   a ) is an exterior oblique view drawing seen from diagonally above the displacement sensor  1  and  FIG. 1(   b ) is a disassembled oblique view drawing of the displacement sensor. 
   The displacement sensor  1  that is shown in  FIGS. 1(   a ) and  1 ( b ) comprises a conical coil spring  11 , a circular cushion sheet  12 , a sensor structure, such as circular sensor sheet section  13 , and a fixing frame  14 . 
   The fixing frame  14  has a cylindrical concave portion  14   e.    
   The sensor sheet  13  is configured with resistive material, such as the circular printed resistor sheet  131 , and a substrate having a conductive pattern, such as the circular printed carbon substrate  132 , on which the circular printed resistor sheet is superposed. On the printed carbon substrate  132 , there is a square shaped protuberant section  132   c  and this is arranged such that, when the printed resistor sheet  131  is superposed on the printed carbon substrate  132 , the protuberant section  132   c  extends beyond the printed resistor sheet  131 . 
   The printed resistor sheet  131  is made from a plastic and like materials, and a conductive ink such as carbon and the like is uniformly printed on the surface that faces the printed carbon substrate  132 . 
   There is a spacer  131   a  between the printed resistor sheet  131  and the printed carbon substrate  132 , and it is arranged such that, when the two are superposed and the conical coil spring  11  is not compressed, there is no direct contact. The spacer  131   a  is in the shape of a ring and is placed on the peripheral edge section of the printed resistor sheet  131  facing the printed carbon substrate  132 . Incidentally, the spacer  131   a  may also be disposed in the center section in addition to the peripheral edge section of the printed resistor sheet  131 . 
   The printed carbon substrate  132  is a printed board on which two independent electrode patterns, the inner peripheral pattern  132   b  and the outer peripheral pattern  132   a , which are formed with copper foil or other electrically conductive material, are disposed. 
   The inner peripheral pattern  132   b  comprises a ring shaped pattern that is disposed in the center of the substrate  132  and a branch form pattern that extends in a radial shape from the outer periphery of the ring shaped pattern toward the outer periphery of the substrate  132 . In addition, in the midst of the branch form pattern, a linear pattern extends from the end section of the pattern that is located closest to the previously discussed protuberant section  132   c  to the protuberant section  132   c  and becomes the electrical terminal  132   e  of the inner peripheral pattern. 
   Also, carbon or another electrically conductive material is printed on the surface of the inner peripheral pattern  132   b.    
   The outer peripheral pattern  132   a  comprises a ring shaped pattern that is disposed on the outer periphery of the substrate  132  and a branch form pattern that extends from the inner circumference of the ring shaped pattern toward the center of the substrate  132 . The branch form pattern of the outer peripheral pattern  132   a  is disposed between the branch form pattern of the inner peripheral pattern  132   b  such that the former branch form pattern does not come into contact with the latter branch form pattern. The ring shaped pattern of the outer peripheral pattern  132   a  is disconnected in one place near the protuberant section  132   c  such that the pattern does not intersect with the terminal  132   e  of the inner peripheral pattern. The linear pattern extends to the protuberant section  132   c  from one end of this pattern that is disconnected and becomes the electrical terminal  132   d  of the outer peripheral pattern. In addition, carbon or another electrically conductive material is printed on the surface of the outer peripheral pattern  132   a  in the same manner as the inner peripheral pattern  132   b.    
   The printed carbon substrate  132 , the printed resistor sheet  131 , and the cushion sheet  12  are received in the concave portion  14   e  of the fixing frame  14  in that order, the printed carbon substrate  132  received first. In addition, the conical coil spring  11  is set into the concave portion  14   e  of the fixing frame  14 , the wider end  11   a  of the conical coil spring  11  first, and the wider end  11   a  of the conical coil spring  11  is in contact with the cushion sheet  12 . 
   With regard to the protuberant section  132   c  of the printed carbon substrate  132 , when the substrate  132  is accommodated in the fixing frame  14 , the protuberant section  132   c  is set into the notched section  14   c  that is disposed in the outer wall of the fixing frame  14 , and by this means, the rotation of the substrate  132  within the fixing frame  14  is prevented. 
   In the displacement sensor that is shown in  FIG. 1(   a ), the attaching hole  1   a  is disposed in a position that is concentric with the axis of the conical coil spring  11 . This attaching hole  1   a  is a hole that passes through all of the components that are shown in  FIG. 1(   b ) in their accommodated state from top to bottom from the cushion sheet  12  through the fixing frame  14 . 
   The displacement sensor  1  is used in order to detect, for example, the displacement of a pedal. In this case, the displacement sensor  1  is mounted in a position that is between the pedal and the facing bottom plate. In addition, the bottom surface of the displacement sensor  1  is in contact with the bottom plate and the front end section of the conical coil spring  11  is in contact with the pedal. When the pedal is stepped on, the displacement sensor  1  is subjected to a compression force from the tip section  11   b  of the conical coil spring  11 . The conical coil spring  11  is compressed and changes shape due to this compression force. 
   One portion of the conical coil spring that has been compressed changes shape. This portion presses and impacts on the cushion sheet  12 . A portion of the printed resistor sheet  131  that is below the cushion sheet  12  is pressed onto the printed carbon substrate  132 . 
   An advantage of using a cushion sheet  12  made of a elastic material such as rubber is, when a pressing force is applied to the surface of the cushion sheet  12  at one point, the pressing force spreads and is also transmitted to the area around the one point to which it was applied. 
   Since the conical coil spring  11  presses the printed resistor sheet  131  onto the printed carbon substrate  132  through the cushion sheet  12 , the force of the wire material of the conical coil spring on the printed resistor sheet  131  is made more uniform than if the sheet were directly pressed by the conical coil spring  11 . The pressing force that has been made uniform is transmitted to the printed carbon substrate  132 . 
   Due to the fact that a portion of the printed resistor sheet  131  is pressed onto the printed carbon substrate  132 , the conductive ink that has been printed on the surface of the printed resistor sheet  131  and the carbon that has been printed on the surface of the inner peripheral pattern  132   b  and the outer peripheral pattern  132   a  of the printed carbon substrate  132  come into contact. 
   At this time, the current that flows in the outer peripheral pattern  132   a  passes through the carbon that has been printed on the surfaces of both patterns and the conductive ink that has been printed on the surface of the printed resistor sheet  131  and flows into the inner peripheral pattern  132   b . Accordingly, the carbon and the conductive ink through which the current passes become an electrical resistance between both patterns. 
   When the pedal is stepped on further, the compression that is applied to the displacement sensor  1  increases and the compression shape change of the conical coil spring  11  becomes greater. 
   When the compression shape change becomes greater, the portions of the printed resistor sheet  131  that up to that point have not been in contact with the printed carbon substrate  132 , are pressed onto the printed carbon substrate  132 . As a result, the current also flows through the portions that have newly come into contact and, since the width of the path for the current that flows from the outer peripheral pattern  132   a  to the inner peripheral pattern  132   b  becomes broader, the electrical resistance between the two patterns decreases. The value of the electrical resistance is transmitted to, for example, the control section of the electronic musical instrument (not shown in the drawing) and the like as the amount that the pedal has been stepped on. 
     FIGS. 2   a  and  2   b  are drawings that show the range in which, when the conical coil spring  11  is compressed and changes shape, the printed resistor sheet  131  is pressed and comes into contact with the printed carbon substrate  132  due to the compression shape change. 
   When the displacement sensor  1  is subjected to the compression force to the tip section  11   b  of the conical coil spring  11  in a direction along the center axis of the conical coil spring  11 , the conical coil spring  11  changes shape. As the conical coil spring  11  compresses, it presses and impacts on the cushion sheet  12  that is shown in  FIG. 1 . 
     FIG. 2(   a ) is a lateral drawing that shows the shape of the conical coil spring  11  when the spring is pressed weakly by a small compression force P 0  that is applied to the tip section  11   b  of the conical coil spring  11 , the shape of the conical coil spring  11  when the spring is pressed to a medium degree by a medium level compression force P 1 , and the shape of the conical coil spring  11  when the spring is pressed strongly by a large compression force P 2 . 
     FIG. 2(   b ) is a drawing that shows the range in which the printed resistor sheet  131 , which had been isolated from the printed carbon substrate  132  by the spacer  131   a , is pressed onto and comes into contact with the printed carbon substrate  132  by the conical coil spring that is shown in  FIG. 2(   a ). 
   The S 0  that is shown in  FIG. 2(   b ) indicates the narrow range in which the printed resistor sheet  131  comes into contact with the printed carbon substrate  132  due to the conical coil spring  11  being pressed weakly by the small compression force P 0 . S 1  indicates the medium range in which the printed resistor sheet  131  comes into contact with the printed carbon substrate  132  due to the conical coil spring  11  being pressed at a medium level by the compression force P 1 , and S 2  indicates the wide range in which the printed resistor sheet  131  comes into contact with the printed carbon substrate  132  due to the conical coil spring  11  being pressed strongly by the large compression force P 2 . 
   Next, an explanation will be given of an example in which the displacement sensor  1  is used in order to detect the displacement of a pedal in the pedal system of an electronic musical instrument as a first utilization example of the present invention. 
     FIG. 3  is a lateral drawing that shows a partial cross-section of the state in which the displacement sensor  1  has been mounted in the pedal system  2  of an electronic musical instrument. 
   The pedal  22  of the pedal system  2  that is shown in  FIG. 3  is supported by the bottom plate  21  so that it can swing and, together with this, is impelled upward by the compression coil spring  26  that has been disposed between the pedal  22  and the bottom plate  21 . The upper end of the compression coil spring  26  is fixed to the back surface of the pedal  22 , and the lower end of the compression coil spring  26  is supported through the intervening support plate  27  by the butterfly nut  25  that has been screwed onto the bolt  28  that has been disposed standing on the bottom plate  21 . When the butterfly nut  25  is turned by hand, the butterfly nut  25  moves in the vertical direction and the degree of compression of the compression coil spring  26  is adjusted by means of the position of the butterfly nut  25 , adjusting the operating weight of the pedal  22 . 
   The lower part of the shaft that is shown in  FIG. 3  passes through the pass-through hole (not shown in the drawing) that has been disposed in the shaft fixing block  210  which has been further fixed to the fixed plate  29  that has been fixed to the pedal  22 , and the tube  211  that has been fixed to the lower surface of the shaft fixing block  210  and extends between the pedal  22  and the bottom plate  21 . In addition, the upper part of the shaft  23  is linked to the controlled section of the electronic musical instrument (not shown in the drawing) that is operated by the pedal system  2 . 
   At this time, the displacement sensor  1  is mounted by being set in the pass-through hole  1   a  in the protuberant section  21   a  that has been disposed on the bottom plate  21  in a position that is opposite the plate  23   a  that is attached to the lower end of the shaft  23 . 
   When the pedal  22  is stepped on, the plate  23   a  on the lower end of the shaft  23  presses downward and pushes on the tip section  11   b  of the conical coil spring  11  of the displacement sensor  1 . Since the conical coil spring  11  that is pressed by the tip section  11   b  is compressed, the electrical resistance of the displacement sensor  1  changes. The value of the electrical resistance is transmitted to the control section of the electronic musical instrument (not shown in the drawing) as the amount that the pedal  22  of the pedal system  2  is stepped on. 
   The initial angle adjustment bolt  212  is furnished on the left part of the pedal system  2  of  FIG. 3  and the fixed plate  29 , which is fixed to the pedal  22 , extends to the lower end of the initial angle adjustment bolt  212 . The height H of the pedal  22  is adjusted by turning the initial angle adjustment bolt and changing the height h of the head of the bolt. 
   In addition, the shaft fixing bolt  24  is furnished in the shaft fixing block  210  that is shown in  FIG. 3  and presses the shaft  23  that passes through from the side fixing the shaft  23 . By changing the length L of the portion of the lower end of the shaft  23  that protrudes from the tube  211 , the amount of change in the electrical resistance of the displacement sensor  1  with respect to the change in the amount that the pedal is stepped on is adjusted. 
   With the displacement sensors of the past, as one example, a rubber sensor is used on the portion that is compressed by the plate  23   a  on the lower end of the shaft  23 , and when used continuously for a long period of time and repeatedly compressed, there is a problem that the shape of the rubber sensor itself becomes deformed and there is a danger that it will become impossible to accurately detect the amount that the pedal has been stepped on. However, with the embodiment of the displacement sensor  1  of the present invention, since a coil spring that is durable with respect to compression and changes in shape in conformance with the degree to which it is compressed is used, the sensor can be used for a long period of time compared to the displacement sensors of the past. 
   Next, an explanation will be given of an example of the use of the displacement sensor  1  to detect the displacement of the cymbals of an electronic high hat cymbal as a second utilization example of the present invention. 
     FIG. 4  is a lateral drawing that shows a partial cross-section of the state in which the displacement sensor  1  has been mounted between, for example, the upper cymbal  37  and the lower cymbal  36  of the electronic high hat cymbal  3 . 
   The electronic high hat cymbal  3  is configured with the upper cymbal  37 , the lower cymbal  36 , the extension rod  34 , which is linked to the upper cymbal, the hollow shaft section  35 , which is linked to the lower cymbal, the spring  38 , which is set into the inside lower end of the hollow shaft section  35 , the stepping type pedal  31 , the joint  32 , which is linked to the extension rod  34  and the pedal  31 , and the legs  33 , which are linked to the hollow shaft section  35 . 
   The upper part of the extension rod  34  is linked to the upper cymbal  37 , the lower part is linked to the pedal  31  through the joint  32 , and connecting and detaching is repeated from the upper part of the upper cymbal  37  in conformance with the stepping operation for the pedal  31 . Incidentally, the linkage of the upper cymbal  37  to the extension rod  34  will be discussed later. 
   The hollow shaft section  35  comprises the upper hollow shaft  351  and the lower hollow shaft  352 , which has an inside diameter that is greater that the outside diameter of the upper hollow shaft  351 . The upper hollow shaft  351  is inserted into the lower hollow shaft  352  and the height of the lower cymbal  36  is determined by the depth to which the upper hollow shaft  351  is inserted into the lower hollow shaft. Incidentally, the joint section  352   a  is disposed on the lower end of the lower hollow shaft  352 . The inside diameter of the joint section  352   a  is made somewhat narrow and supports the spring  38  that is set inside from the bottom. 
   The lower section of the extension rod  34  passes through the upper hollow shaft  351  and the lower hollow shaft  352  and, together with this, also passes through the spring  38  that has been set inside the lower hollow shaft  352 . Since due to the fact that the spring  38  is held between the lower surface of the joint section  34   a  of the extension rod  34  and the joint section  352   a  of the lower hollow shaft  352 , the extension rod  34  is always lifted upward, and when a stepping operation of the pedal  31  is not being carried out, the upper cymbal  37  and the lower cymbal  36  are separated at a prescribed interval. 
     FIG. 5  is a lateral drawing that shows an enlarged cross-section of the state in which the displacement sensor  1  is mounted between the upper cymbal  37  and the lower cymbal  36 . 
     FIG. 5(   a ) is a lateral drawing in which the separated state of the upper cymbal  37  and the lower cymbal  36  are shown in cross-section, and  FIG. 5(   b ) is a lateral drawing that shows in cross-section the state in which, as a result of the upper cymbal  37  and the lower cymbal  36  having been brought into contact, the displacement sensor  1  is subjected to a compression force in the vertical direction, and the conical coil spring  11  of the displacement sensor  1  is compressed and changes shape. If the two cymbals are arranged in a different configuration, then the displacement sensor  1  may be subjected to a compression force in an accordingly different direction. 
   The upper felt washer  40 , the lower felt washer  39 , the upper nut  42 , the lower nut  41 , the fixing component  43 , and the securing bolt  44 , provided in order, link the upper cymbal  37  to the extension rod  34 . 
   The fixing component  43  is formed with the lower bolt  43   a  extending on the lower surface of the upper block  43   b  and the pass-through hole  43   c  is disposed in the center in order for the extension rod  34  to pass through. The upper nut  42  is screwed onto the lower bolt  43   a  of the fixing component  43  until the nut connects with and is stopped by the upper block  43   b  of the fixing component  43 . The lower bolt  43   a  of the fixing component  43  is inserted through the pass-through holes that are disposed respectively in, from the bottom of the upper nut  42 , the upper felt washer  40 , the upper cymbal  37 , and the lower felt washer  39 . By additionally screwing the lower nut  41  onto the lower bolt  43   a  from the lower side of the lower felt washer  39 , the upper cymbal  37  is fixed by the fixing component  43 . 
   The tip section  351   b  of the upper hollow shaft  351  has the felt  45  held between the shaft bearer  351   a  and the lower cymbal  36  is supported from the bottom by the upper hollow shaft  351  by the insertion of the shaft into the pass-through hole that is disposed in the center of the lower cymbal  36 . 
   The upper part of the extension rod  34  passes through center of the conical coil spring  11  of the displacement sensor  1  and the displacement sensor  1  attachment hole  1   a  at the upper part of the upper hollow shaft  351  that supports the lower cymbal  36  and additionally, passes through the pass-through hole  43   c  of the fixing component  43  with which the upper cymbal  37  is fixed. The tip section  11   b  of the conical coil spring  11  of the displacement sensor  1  is in contact with the tip section  351   b  of the upper hollow shaft  351 , and the bottom surface  14   d  of the displacement sensor  1  is in contact with the lower end section  43   d  of the fixing component  43 . 
   The upper block  43   b  of the fixing component  43  with which the upper cymbal  37  has been fixed is furnished with the securing bolt  44  that presses the extension rod  34  that passes through from the side and fixes the extension rod  34 . The upper cymbal  37  is linked to the extension rod  34  through the fixing component  43  by means of the securing bolt  44 . 
   When the upper cymbal  37 , which is linked to the extension rod  34  by the fixing component  43 , moves downward in conformance with the stepping on the pedal  31  that is shown in  FIG. 4 , the displacement sensor  1  is subjected to a compression force on the bottom surface  14   d  from the lower end section  43   d  of the fixing component  43  that moves as a single unit with the upper cymbal  37 . On the other hand, since the tip section  11   b  of the conical coil spring  11 , which lies on the other end of the displacement sensor  1 , is in contact with the tip section  352   b  of the upper hollow shaft  351 , which supports the lower cymbal  36 , and does not move, the conical coil spring of the displacement sensor  1  is compressed by the compression force that has been applied to the bottom surface  14   d  of the displacement sensor  1 . The electrical resistance of the displacement sensor  1  changes due to this compression. The value of the electrical resistance is transmitted to the control section of the electronic high hat cymbal (not shown in the drawing) as the amount of displacement of the upper cymbal  37  of the electronic high hat cymbal  3 . 
   As has been explained above, the displacement of the upper cymbal in conformance with the stepping operation of the pedal  31  of the high hat cymbal  3  that is shown in  FIG. 4  can be detected using the displacement sensor  1  of the present invention. 
   Incidentally, in those cases where the displacement sensor  1  is mounted on the electronic high hat cymbal  3 , since it is possible to attach the electronic high hat cymbal  3  and the displacement sensor  1  to an ordinary acoustic high hat stand without the addition of any other special components, in those cases where the user already possesses an acoustic high hat, an acoustic high hat stand can be used. Then, it is possible to plan for a reduction of the mounting expense. 
   Next, an explanation will be given regarding a second preferred embodiment of the present invention. 
     FIG. 6  is an oblique view drawing that shows a second preferred embodiment of the displacement sensor of the present invention. 
     FIG. 6(   a ) is an exterior oblique view drawing seen from diagonally above the displacement sensor  5  and  FIG. 6(   b ) is a disassembled oblique view drawing of the displacement sensor  5 . The displacement sensor  5  that is shown in  FIG. 6  here is furnished with the same conical coil spring and fixing frame as the conical coil spring  11  and fixing frame  14  with which the displacement sensor  1  that is shown in  FIG. 1  is furnished but is furnished with components between the conical coil spring and fixing frame that are different from the components that are furnished between the conical coil spring  11  and the fixing frame  14  of the displacement sensor  1  that is shown in  FIG. 1 . The displacement sensor  5 , except for the areas in which the components with which the sensor is furnished differ from those of the displacement sensor  1  that is shown in  FIG. 1 , has a structure that is the same as that of the displacement sensor  1  that is shown in  FIG. 1 . Therefore, for the components that are the same as the components of the displacement sensor  1  that is shown in  FIG. 1 , (the conical coil spring  11  and the fixing frame  14 ), the same keys are assigned and shown in  FIG. 6 , and an explanation of these components and that duplicates a structure that is equivalent to that of the displacement sensor  1  that is shown in  FIG. 1  has been omitted. 
   The displacement sensor  5  that is shown in  FIG. 6  is furnished with the base film  511  and the substrate  512  between the conical coil spring  11  and the fixing frame  14 . These two components comprise the sensor sheet  51 . 
   The base film  511  and the substrate  512  respectively have the protuberant sections  511   a _ 1  and  512   c  and, when the base film  511  and the substrate  512  are accommodated in the fixing frame  14 , the protuberant sections  511   a _ 1  and  512   c  are in a mutually superposed state set into the concave portion  14   e  of the fixing frame  14 . Because of this, the base film  511  and the substrate  512  are prevented from turning in the fixing frame  14  and the relative positional relationships between the two are maintained. 
   The pressing film  511   b  is furnished with the two bridge sections  511   b _ 1  and  511   b _ 2  along the center line of the circular plastic sheet  511   a . The pressing film  511   b , which is affixed to the circular plastic sheet  511   a , forms the thick convex portion of the pressing film  511   b  on the conical coil spring  11  side surface of the base film  511 . When the conical coil spring  11  is compressed, a portion of the conical coil spring  11  pushes and impacts particularly strongly against the two bridge sections  511   b _ 1  and  511   b _ 2  and, as a result, the area below the portion of these two bridge sections  511   b _ 1  and  511   b _ 2  of the base film  511  that is pressed and impacted by the conical coil spring  11  is pressed strongly on the substrate  512 . 
   The conductive pattern  511   c  is printed with a conductive ink such as carbon and the like on the substrate  512  side surface of the plastic sheet  511   a  and is a ring shaped pattern that surrounds the attachment hole  1   a  of the displacement sensor  5 . 
   The resistive pattern  511   d  is a pattern in which a resistive material such as carbon and the like is printed superposed on the conductive pattern  511   c  described above on the substrate  512  side surface of the plastic sheet  511   a . The resistive pattern  511   d  is furnished with the branch shaped patterns  511   d _ 1  and  511   d _ 2  that faces the outer edge of the plastic sheet  511   a  from the ring shaped pattern that is superposed on the conductive pattern  511   c  under the two bridge sections  511   b _ 1  and  511   b _ 2  of the pressing film  511   b . When the conical coil spring  11  is compressed, a portion of each of the two branch shaped patterns  511   d _ 1  and  511   d _ 2  is pressed onto the substrate  512  through the above mentioned two bridge sections  511   b _ 1  and  511   b _ 2 . 
   The spacer film  511   e  is affixed on the resistive pattern  511   d  on the substrate  512  side surface of the plastic sheet  511   a . The two openings  511   e _ 1  and  511   e _ 2  are disposed in two locations in positions that correspond to the two branch shaped patterns  511   d _ 1  and  511   d _ 2  of the resistive pattern  511   d  described above. When the conical coil spring is compressed, the two branch shaped patterns  511   d _ 1  and  511   d _ 2  are pressed onto the substrate  512  through the openings  511   e _ 1  and  511   e _ 2  in the two corresponding locations. However, it should be noted that, in a state in which the conical coil spring  11  is not compressed, the two branch shaped patterns  511   d _ 1  and  511   d _ 2  described above are separated from the substrate only by the thickness of the spacer film  511   e.    
   The substrate  512  is configured with a circular base material on which a metal pattern is disposed on both sides. On the spacer film  511   e  side obverse surface, the two metal patterns  512   a  and  512   b , which are mutually independent, are disposed in positions that correspond respectively to the two branch shaped patterns  511   d _ 1  and  511   d _ 2  of the resistive pattern  511   d . On the other hand, on the reverse surface, the two terminal patterns  512   d  and  512   e , which extend to the protuberant section  512   c  of the substrate  512  and form electrical terminals on the protuberant section  512   c , are disposed respectively below the two branch shaped patterns  511   d _ 1  and  511   d _ 2  described above. In addition, the two branch shaped patterns  511   d _ 1  and  511   d _ 2  described above are respectively conducted through by through holes not shown in the drawing to the corresponding terminal patterns  512   d  and  512   e . When the conical coil spring  11  is compressed, a portion of each of the two branch shaped patterns  511   d _ 1  and  511   d _ 2  described above comes into contact respectively with the corresponding metal pattern  512   a  and  512   b.    
   In the same manner as the displacement sensor of the first preferred embodiment discussed previously, the displacement sensor  5  of the second preferred embodiment also is used, for example, in order to detect the displacement of a pedal and the like. In this case, when the conical coil spring  11  is compressed by stepping on the pedal, as was discussed above, a portion of the resistive pattern  511   d  of the base film  511  comes into contact with the metal patterns  512   a  and  512   b  on the obverse surface of the substrate  512 . At this time, when the current is conducted through the metal patterns  512   a  and  512   b  and flows between the terminal patterns  512   d  and  512   e  on the reverse surface of the substrate  512 , the current flows passing through the resistive pattern  511   d  described above, the ring shaped pattern on the resistive pattern  511   d , and the conductive pattern  511   c  described above that is printed on the plastic sheet  511   a  on which the patterns are superposed. Accordingly, the resistive pattern  511   d  and the conductive pattern  511   c  through which the current passes become an electrical resistance between the terminal patterns  512   d  and  512   e.    
     FIGS. 7(   a ) and  7 ( b ) are schematic drawings that show the state in which a portion of the resistive pattern of the base film has come into contact with the metal pattern on the obverse surface of the substrate. 
   In  FIG. 7(   a ), the condition is shown in which, in a case in which the displacement sensor  5  is utilized to detect the displacement of, for example, a pedal and the like, the conical coil spring  11  is compressed by the pedal being stepped on, the base film  511  is pushed and impacted on by a portion of the conical coil spring  11  and, in addition, a portion of the base film  511  is pushed and impacted on by the obverse side of the substrate  511  through the openings  511   e _ 1  and  511   e _ 2  of the spacer film  511   e . By this means, as was discussed above, a portion of the resistive pattern  511   d  comes into contact with the metal patterns  512   a  and  512   b  on the obverse surface of the substrate  512 . 
   In  FIG. 7(   b ), the two metal patterns  512   a  and  512   b  on the obverse surface of the substrate  512  and the resistive pattern  511   d , which is in contact with these metal patterns  512   a  and  512   b , are shown. As discussed above, when the base film  511  is pushed and impacted on by the substrate  512 , a portion of each of the branch shaped patterns  511   d _ 1  and  511   d _ 2  of the resistive pattern  511   d  come into contact, respectively, with the corresponding metal patterns  512   a  and  512   b . In addition, the portions of the resistive pattern  511   d  that are in between these two locations (excluding  511   d _ 5 ), the contact portions  511   d _ 3  and  512   d _ 4 , which are indicated by the diagonal lines in  FIG. 7(   b ), and the conductive pattern  511   c  become an electrical resistance between the metal patterns  512   a  and  512   b  as well as between the terminal patterns  512   d  and  512   e  that are shown in  FIG. 6 . 
   When the pedal described above is stepped on further and the conical coil spring  11  is further compressed, the portions of the resistive pattern  511   d  that, up to this point, have not been in contact with the metal patterns  512   a  and  512   b  also are pressed on by the metal patterns  512   a  and  512   b . As a result, the distance La+Lb between the two locations described above, the contacted portions  511   d _ 3  and  511   d _ 4 , is shortened and the value of the electrical resistance described above is reduced. 
     FIG. 8  is a drawing that shows the change in the distance between the contacted portions of the two locations shown in  FIG. 7  that accompanies the increase in the portion of the conical coil spring that is pushed and impacts on the base film. 
   In  FIG. 8 , the condition in which the conical coil spring  11  is weakly pressed with a small compression force P 0  and the base film is slightly pushed and impacted on by the conical coil spring  11  is shown. At this time, the portion that corresponds to the long distance La 0 +Lb 0  between the contacted portions described above of the resistive pattern  511   d  (refer to  FIG. 7 ) becomes the electrical resistance between the terminal patterns  512   d  and  512   e  that are shown in  FIG. 6  and the value of the electrical resistance is large. In addition, when the compression force that is applied to the conical coil spring  11  is increased and becomes the medium level compression force P 1 , the base film is pushed and impacted on to a medium degree by the conical coil spring  11  and the value of the electrical resistance described above becomes a medium level value that is proportional to the medium level distance La 1 +Lb 1  shown in  FIG. 8 . When the compression force that is applied to the conical coil spring  11  is increased and becomes the large compression force P 2 , a larger portion of the base film is pushed and impacted on by the conical coil spring  11  and the value of the electrical resistance described above becomes a small value that is proportional to the short distance La 2 +Lb 2  shown in  FIG. 8 . 
   That is to say, when the displacement of a pedal such as that discussed above is detected by means of the utilization of the displacement sensor  5 , in the same manner as in the first preferred embodiment discussed previously, the value of the electrical resistance is transmitted to, for example, the control section of the electronic musical instrument (not shown in the drawing) and the like as the amount that the pedal has been stepped on. 
   The second preferred embodiment, in the same manner as in the first preferred embodiment discussed previously, is utilized to detect the displacement of the pedal of the pedal system  2  of an electronic musical instrument shown in  FIG. 3  or to detect the displacement of the cymbal in the electronic high hat cymbal  3  shown in  FIG. 4  and  FIG. 5  and the like. However, with regard to these kinds of utilization embodiments for the second preferred embodiment described above, since they are the same as the utilization embodiments of the first preferred embodiment for which explanations were given referring to  FIG. 3  through  FIG. 5 , the duplicated explanations have been omitted. 
   In addition, as has been discussed previously, by means of the first preferred embodiment, advantageous results are that durability is increased with the use of a coil spring and that, when the displacement sensor  1  is installed in the electronic high hat cymbal  3  that is shown in  FIG. 4 , the installation expenses are reduced. It need scarcely be said that advantageous results that are the same as these advantageous results can also be obtained by means of the displacement sensor  5  of the second preferred embodiment of the present invention. 
   Incidentally, in the above preferred embodiments, as illustrations of the sensor sheet of the present invention, an example in which a printed carbon substrate  132  and a printed resistor sheet  131  having as conductive ink such as carbon and the like printed uniformly on a strong plastic sheet such as polyester have been combined, and an example in which a substrate  512  having metal patterns disposed on both surfaces and a base film  511  having a resistive pattern  511   d  printed on a plastic sheet have been combined were given. However, the sensor sheet in the embodiments of the present invention is not limited to these examples and, for example, a pressure sensitive printed resistor sheet in which the resistance value changes in accordance with the pressing force and the like may be used.