Patent Publication Number: US-10332497-B2

Title: Electronic percussion

Description:
TECHNICAL FIELD 
     The present invention relates to an electronic percussion that detects an impact to a struck surface beaten by a hand, a stick, a beater, or the like to generate an electronic musical sound. 
     BACKGROUND ART 
     Conventionally, there has been provided an electronic percussion that detects an impact to a struck surface beaten by a hand, a stick, a beater, or the like to generate an electronic musical sound. For example, the following Patent Literature 1 discloses an electronic drum (an electronic percussion). This electronic drum (this electronic percussion) includes a laser ranging circuit at a bottom portion of a drum body that supports a vibrating plate (a head) beaten by a stick. In view of this, this electronic drum optically detects a vibration of the vibrating plate to generate an electronic musical sound. 
     CITATION LIST 
     Patent Literature 
     PATENT LITERATURE 1: JP-A-04-116695 
     However, the electronic drum type electronic percussion described in Patent Literature 1 has the following problem. That is, to obtain a reflected light from a back surface of the vibrating plate, a deposition film formed of metal particles is formed on the back surface of the vibrating plate. Accordingly, received damage and deterioration of the deposition film due to hitting of the vibrating plate is significant, thereby detection accuracy of the vibration is likely to be deteriorated. 
     The present invention has been made to deal with the problem. An object of the present invention is to provide an electronic percussion that can maintain detection accuracy of a vibration of a head over a long period of time. 
     SUMMARY OF INVENTION 
     To achieve the object, as a feature of the present invention, a head, an optical sensor, and a sensor cover body are included. The head is configured such that a struck surface beaten by a player has a semi-translucency that causes a part of irradiated light to transmit and reflects another part of the light. The optical sensor is disposed opposed at one surface side of the head. The optical sensor includes respective light emitter and photoelectric converter. The light emitter is configured to irradiate the head with light. The photoelectric converter is configured to photoelectrically convert a received light. The sensor cover body is disposed at a position that is opposed to the optical sensor and at another surface side of the head. The sensor cover body has a size with which the optical sensor is covered. 
     With the feature of the present invention thus configured, the electronic percussion includes the optical sensor at the one surface side of the head. Furthermore, the sensor cover body having the size with which the optical sensor is covered is disposed at the other surface side, the opposite side of the one surface. Accordingly, an amount of light (brightness) at a back surface side of the head part to which the optical sensor is opposed decreases and a change in the faint reflected light from the head with a semi-translucency can be detected. In view of this, the electronic percussion according to the present invention can maintain detection accuracy of a vibration of the head over a long period of time. 
     Another feature of the present invention is as follows. With the electronic percussion, the sensor cover body is disposed opposed at a position separated from the other surface side of the head. 
     With the other feature of the present invention thus configured, with the electronic percussion, the sensor cover body is disposed opposed at a position separated from the other surface side, which is the side opposite to the one surface, of the head. In view of this, the sensor cover body does not affect the vibration of the head, and the sensor cover body itself is unaffected by the vibration, thereby ensuring maintaining the detection accuracy of the vibration of the head over a long period of time. 
     Another feature of the present invention is as follows. With the electronic percussion, the sensor cover body is disposed directly on the other surface of the head. 
     With the other feature of the present invention thus configured, with the electronic percussion, the sensor cover body is disposed directly on the other surface of the head. Therefore, the sensor cover body does not become an obstacle of performance of the electronic percussion and additionally the compact electronic percussion can be configured. 
     Another feature of the present invention is as follows. With the electronic percussion, the sensor cover body is formed into an annular shape along an outer edge portion of the head. 
     With the other feature of the present invention thus configured, with the electronic percussion, the sensor cover body is formed into the annular shape along the outer edge portion of the head. Accordingly, when the optical sensor is attached, this allows reducing a load applied to positioning between the optical sensor and the sensor cover body. Furthermore, the electronic percussion can be constituted so as to have a sophisticated design free from a feeling of a foreign body as an appearance design. 
     Another feature of the present invention is as follows. The electronic percussion further includes a tubular shell and a sensor supporting body. The tubular shell supports the outer edge portion of the head. The sensor supporting body is disposed at a side surface of the shell. The sensor supporting body supports the optical sensor at a position adjacent to the head. 
     With the other feature of the present invention thus configured, with the electronic percussion, the optical sensor is disposed at the side surface of the shell and at the position adjacent to the head by the sensor supporting body. This allows detecting the vibration of the head precisely at a shorter time. Furthermore, the side in the shell opposed to the head is opened, escaping a shock wave caused by hitting of the head to outside of the shell and ensuring preventing an echo. 
     Another feature of the present invention is as follows. With the electronic percussion, the optical sensor is disposed at an end of the head on a side opposite to the player side. 
     With the other feature of the present invention thus configured, with the electronic percussion, the optical sensor is disposed at the end of the head on the side opposite to the player side. This ensures facilitating the performance and also can prevent received damage of the optical sensor and the sensor cover body. 
     Another feature of the present invention is as follows. With the electronic percussion, the sensor cover body has a side facing the optical sensor. The side is colored with a deep color. 
     According to the other feature of the present invention thus configured, with the electronic percussion, the sensor cover body has the side facing the optical sensor colored with the deep color. Accordingly, the decreased reflected light from the sensor cover body ensures easy detection of the change in the faint reflected light from the head with a semi-translucency, ensuring improving the detection accuracy of the vibration. 
     To achieve the object, as another feature of the present invention, a head, an optical sensor, and a sheet-shaped or plate-shaped sensor-opposed body are included. 
     The head is configured such that a struck surface beaten by a player has a semi-translucency that causes a part of irradiated light to transmit and reflects another part of the light. The optical sensor is disposed opposed at one surface side of the head. The optical sensor includes respective light emitter and photoelectric converter. The light emitter is configured to irradiate the head with light. The photoelectric converter is configured to photoelectrically convert a received light. The sensor-opposed body is disposed directly on the one surface of the head. The sensor-opposed body is configured to reflect the light irradiated by the light emitter. 
     With the other feature of the present invention thus configured, the electronic percussion includes the plate-shaped or sheet-shaped sensor-opposed body as a reflecting body on the one surface of the head to which the optical sensor is opposed. Therefore, partial peeling and a drop due to the hitting of the head can be less likely to occur. Accordingly, the detection accuracy of the vibration of the head can be maintained over a long period of time. The electronic percussion includes the plate-shaped or sheet-shaped sensor-opposed body. In view of this, mounting and exchanging work of the sensor-opposed body to the head can be easily performed. 
     Another feature of the present invention is as follows. With the electronic percussion, the sensor-opposed body is formed into an annular shape along an outer edge portion of the head. 
     With the other feature of the present invention thus configured, with the electronic percussion, the sensor-opposed body is formed into the annular shape along the outer edge portion of the head. Accordingly, when the optical sensor is attached, this allows reducing a load applied to positioning between the optical sensor and the sensor cover body. Furthermore, the electronic percussion can be constituted so as to have the sophisticated design free from the feeling of the foreign body as the appearance design. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view illustrating a schematic external configuration of an electronic percussion according to a first embodiment of the present invention. 
         FIG. 2  is a cross-sectional view schematically illustrating a schematic internal configuration of the electronic percussion illustrated in  FIG. 1 . 
         FIG. 3  is a partially enlarged cross-sectional view illustrating an inside of an enlarged dashed circle A illustrated in  FIG. 2 . 
         FIG. 4  is a partially enlarged plan view to describe a direction of an arrangement of an optical sensor in the electronic percussion illustrated in  FIG. 1 . 
         FIG. 5  is a partially enlarged plan view to describe another direction of the arrangement of the optical sensor in the electronic percussion illustrated in  FIG. 1 . 
         FIG. 6  is a block diagram illustrating a schematic circuit configuration of a sound source coupled to the electronic percussion illustrated in  FIG. 1 . 
         FIG. 7  is a partially enlarged cross-sectional view illustrating enlarged main parts (inside the dashed circle A illustrated in  FIG. 2 ) of an electronic percussion according to a modification of the present invention. 
         FIG. 8  is a partially enlarged cross-sectional view illustrating enlarged main parts (inside the dashed circle A illustrated in  FIG. 2 ) of an electronic percussion according to another modification of the present invention. 
         FIG. 9  is a partially enlarged cross-sectional view illustrating enlarged main parts of an electronic percussion according to another modification of the present invention. 
         FIG. 10  is a partially enlarged cross-sectional view illustrating enlarged main parts (inside the dashed circle A illustrated in  FIG. 2 ) of an electronic percussion according to another modification of the present invention. 
         FIG. 11  is a partially enlarged cross-sectional view illustrating enlarged main parts of an electronic percussion according to another modification of the present invention. 
         FIG. 12  is a partially enlarged cross-sectional view illustrating enlarged main parts (inside the dashed circle A illustrated in  FIG. 2 ) of an electronic percussion according to another modification of the present invention. 
         FIG. 13  is a partially enlarged cross-sectional view illustrating enlarged main parts of an electronic percussion according to another modification of the present invention. 
         FIG. 14  is a partially enlarged cross-sectional view illustrating enlarged main parts (inside the dashed circle A illustrated in  FIG. 2 ) of an electronic percussion according to another modification of the present invention. 
         FIG. 15  is a partially enlarged cross-sectional view illustrating enlarged main parts (inside the dashed circle A illustrated in  FIG. 2 ) of an electronic percussion according to a second embodiment of the present invention. 
         FIG. 16  is a partially enlarged cross-sectional view illustrating enlarged main parts of an electronic percussion according to a modification of the present invention. 
         FIG. 17  is a partially enlarged cross-sectional view illustrating enlarged main parts (inside the dashed circle A illustrated in  FIG. 2 ) of an electronic percussion according to another modification of the present invention. 
         FIG. 18  is a partially enlarged cross-sectional view illustrating enlarged main parts (inside the dashed circle A illustrated in  FIG. 2 ) of an electronic percussion according to another modification of the present invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     (First Embodiment) 
     The following describes the first embodiment of an electronic percussion according to the present invention with reference to the drawings.  FIG. 1  is a perspective view schematically illustrating a schematic external configuration of an electronic percussion  100  according to the present invention.  FIG. 2  is a cross-sectional view schematically illustrating a schematic internal configuration of the electronic percussion  100  illustrated in  FIG. 1 . The drawings to be referred to in this description are schematically illustrated for ease of understanding of the present invention by exaggeratedly illustrating a part of components and the like. Therefore, dimensions, ratios, and the like between the respective components may differ. This electronic percussion  100  is an electronic drum that detects an impact to a struck surface  101   a  beaten by a player (not illustrated) by a stick (not illustrated) to generate an electronic musical sound. 
     (Configuration of Electronic Percussion  100 ) 
     The electronic percussion  100  includes a head  101 . The head  101  is a component that vibrates and elastically deforms by a beating operation by the player. The head  101  is configured by forming a cloth material or a resin material into a sheet shape or a thin plate shape. This head  101  is constituted so as to have a semi-translucency that causes a part of irradiated light to transmit and reflects the other part of the light. 
     Specifically, the head  101  is constituted of the transparent or semi-translucent sheet material or thin plate material made of resin or the cloth material or the resin material formed into a mesh shape. The head  101  of this embodiment is configured by forming the mesh-shaped sheet body into a circular shape in a plan view. An outer edge portion of this head  101  is held by a head frame  102 . 
     The head frame  102  is a component to dispose the head  101  on a shell  103  with the head  101  being tensioned. The head frame  102  is configured by forming a metal material or a resin material into an annular shape. This head frame  102  is fitted to an outer peripheral portion of the shell  103  while holding the outer edge portion of the head  101 . In this case, a hoop  107  presses the annular top surface of the head frame  102 . 
     The shell  103  is a component that supports the respective head  101  and optical sensor  105 . The shell  103  is configured by forming a metal material, a resin material, or wood into a cylindrical shape. One (the upper side in the drawing) end of this shell  103  is obstructed by the head  101  and the other (the lower side in the drawing) end opens. In view of this, the surface of the head  101  exposed to the outside of the shell  103  constitutes the struck surface  101   a . Furthermore, the surface facing the inside of the shell  103  of the head  101  constitutes a back surface  101   b . A sensor supporting body  104  is disposed at an inner peripheral surface of this shell  103 . 
     As illustrated in  FIG. 3 , the sensor supporting body  104  is a component that supports the optical sensor  105  at a position adjacent to the back surface  101   b  of the head  101 . The sensor supporting body  104  is constituted of a metal plate projecting out from the inner peripheral surface of the shell  103  radially inside. In this case, the sensor supporting body  104  is preferably disposed at a position where the optical sensor  105  is not in contact with the head  101  and a position where the sensor supporting body  104  can support the optical sensor  105  on the head  101  side with respect to the head frame  102 . In this case, the sensor supporting body  104  is mounted to the inner peripheral surface of the shell  103  with an adhesive, a screw (not illustrated), or the like. The optical sensor  105  is disposed on the top surface of this sensor supporting body  104 . 
     As illustrated in respective  FIGS. 3 and 4 , the optical sensor  105  is a detector that optically detects the vibration of the head  101 . The optical sensor  105  is constituted so as to mainly include respective light emitter  105   a  and light receiver  105   b . The light emitter  105   a  is a light emitting element that irradiates light to the head  101 . With this embodiment, the light emitter  105   a  is constituted of an LED that emits infrared. The light receiver  105   b  is constituted of a light receiving element that outputs an electric signal according to an amount of received light. With this embodiment, the light receiver  105   b  is constituted of a phototransistor that receives the infrared. 
     These light emitter  105   a  and light receiver  105   b  house the exposed light emitting element and light receiving element in one rectangular parallelepiped-shaped housing made of resin. The light emitter  105   a  and the light receiver  105   b  integrally constitute the optical sensor  105 . The sensor supporting body  104  supports this optical sensor  105  to a position opposed to the back surface  101   b  of the head  101 . In this case, the optical sensor  105  is preferably disposed at an outer edge part of the head  101  and a position separated from a sidewall of the shell  103  inside. 
     The light emitter  105   a  and the light receiver  105   b  of the optical sensor  105  are disposed aligned in a radial direction of the head  101 . In this case, disposing the light receiver  105   b  radially outside with respect to the light emitter  105   a  allows the optical sensor  105  to be less likely to be affected by external light. This optical sensor  105  is electrically connected to a sound source  90 , which is disposed separately from the electronic percussion  100 , to be removable. 
     With this optical sensor  105 , the light receiver  105   b  may be disposed radially inside with respect to the light emitter  105   a . Alternatively, as illustrated in  FIG. 5 , the light emitter  105   a  and the light receiver  105   b  may be disposed aligned in a circumferential direction of the head  101 . The light emitter  105   a  may be a light source unit that emits the light with a wavelength other than the infrared, for example, visible light. The light receiver  105   b  may detect, for example, the light receiving position instead of the amount of received light. Alternatively, the light receiver  105   b  may detect a time until the light receiver  105   b  receives the emitted light. 
     Meanwhile, respective rugs  106  and sensor cover body  110  are disposed on an outer peripheral surface of the shell  103 . The rug  106  is a component to press the hoop  107  to the top surface of the head frame  102 . The rugs  106  are disposed projecting out on the outer peripheral surface of the shell  103 . More specifically, the rug  106  is constituted of a metallic block body extending in an axis direction of the shell  103 . A female thread (not illustrated) is formed on an end surface on the head frame  102  side (the upper side in the drawing) of this block body. 
     Tension bolts  108  that penetrate the hoop  107  are screwed into the female threads to securely support the hoop  107  by the rugs  106 . The plurality of rugs  106  is disposed along the circumferential direction of the shell  103 . This embodiment includes the six rugs  106  at approximately uniform intervals mutually along the circumferential direction of the shell  103 . 
     The hoop  107  is a component to stretch the head  101  on the shell  103  by pressing the top surface of the head frame  102  and configured by forming a metal material into a staged cylindrical shape. This hoop  107  is formed into the cylindrical shape where the one (the upper side in the drawing) end side projects out from the upper end of the shell  103  on which the head  101  is stretched and the other (the lower side in the drawing) end side projects out radially outside and then projects out from the lower end of the head frame  102 . The part of the hoop  107  projecting out radially outside at the other end is mounted to the rugs  106  by the tension bolts  108 . 
     The tension bolt  108  is a component to press the hoop  107  to the top surface of the head frame  102 . The tension bolts  108  are constituted of bolts formed of male threads at an outer peripheral portion of a metallic shaft body. These tension bolts  108  are tightened to the female threads of the rugs  106  while penetrating a part of the hoop  107  where the outer diameter projects out. In view of this, by pulling the head frame  102  to the rug  106  side, the head  101  is pressed to the end of the shell  103 , entering a state of being tensioned to be a flat film shape. 
     The sensor cover body  110  is a component to restrain light other than the light emitted by the light emitter  105   a  and reflected by the head  101  from entering the light receiver  105   b  of the optical sensor  105 . The sensor cover body  110  is constituted of a plate-shaped body made of metal (for example, a steel material such as a stainless steel material) or made of resin. More specifically, the sensor cover body  110  is formed so as to have a size with which the sensor cover body  110  covers the optical sensor  105  at the position opposed to the optical sensor  105  at a surface side opposite to the surface of the head  101  facing the optical sensor  105 . With this embodiment, the sensor cover body  110  is disposed at the position on the struck surface  101   a  side of the head  101  opposed to the optical sensor  105  separated from the struck surface  101   a.    
     This sensor cover body  110  mainly includes a light-shielding portion  111  and a supporter  112 . The light-shielding portion  111  is a part disposed above the struck surface  101   a  of the head  101  opposed to the optical sensor  105 . The light-shielding portion  111  is formed into a long plate shape in a plan view extending from the outer edge portion side of the head  101  inside. In this case, the light-shielding portion  111  is formed so as to have a size (an area) larger than a size (an area) of the optical sensor  105  disposed opposed to the light-shielding portion  111  via the head  101  in a plan view. 
     A surface of the light-shielding portion  111  opposed to the head  101 , namely, the internal surface of the light-shielding portion  111  is colored with a deep color. This embodiment colors the internal surface of the light-shielding portion  111  with black. Meanwhile, the supporter  112  is a part that supports the light-shielding portion  111  above the head  101 . The supporter  112  is formed so as to project out from the outer peripheral surface of the shell  103  outside and then bend to the hoop  107  side (the upper side in the drawing) and extend in the vertical direction. This support  112  is mounted to the sidewall of the shell  103  by an attachment tool  113  formed of a bolt and a nut. With this sensor cover body  110 , performing bending work on the metal plate integrally forms the light-shielding portion  111  and the supporter  112 . 
     As illustrated in  FIG. 6 , the sound source  90  is a known electronic circuit that outputs a musical sound signal using a detection signal output from the optical sensor  105  and is constituted separated from the electronic percussion  100 . This sound source  90  is constituted so as to mainly include respective power supply  91 , A/D converter  92 , controller  93 , PCM sound source unit  94 , D/A converter  95 , and amplifier  96 . Among these members, the power supply  91  is an electric circuit to which electric power is supplied from an electric power supply source (for example, 100 V-power supply for household) via a power supply cord (not illustrated) and supplies the electric power to the respective electric circuits of the sound source  90  and the optical sensor  105 . 
     The A/D converter  92  is an electronic circuit that converts the analog detection signal output from the optical sensor  105  into a digital signal and outputs the digital signal to the controller  93 . The controller  93  is constituted of a microcomputer constituted of a CPU, a ROM, a RAM, and the like. The controller  93  executes a control program preliminary stored in a storage device such as the ROM to generate the musical sound signal representing the musical sound using the detection signal output from the optical sensor  105  and the PCM sound source unit  94 . This controller  93  also includes an operation panel  93   a  to input an instruction from the player. 
     The PCM sound source unit  94  is an electronic circuit storing the signal representing the musical sound by an actual musical instrument (also referred to as an “acoustic musical instrument”) preliminary recorded by a pulse code modulation (PCM) method. The D/A converter  95  is an electronic circuit that converts the digital musical sound signal output from the controller  93  into the analog signal and outputs the analog signal to the amplifier  96 . The amplifier  96  is an electric circuit that amplifies the analog musical sound signal output from the D/A converter  95  and outputs the amplified analog musical sound signal. Accordingly, the sound source  90  can generate the musical sound signal to emit the musical sound close to the musical sound by the acoustic musical instrument. In this case, the amplifier  96  includes an output terminal to take out the musical sound signal. In view of this, the amplifier  96  can be electrically connected to an external speaker  97 . 
     The external speaker  97  is a device that converts the musical sound signal formed of the analog electric signal into the musical sound and is constituted separately from the sound source  90 . In view of this, the sound source  90  can generate the musical sound by being electrically connected to the external speaker  97 . With this embodiment, the electronic percussion  100  is configured to be a so-called external type that externally couples the speaker generating the musical sound. Obviously, the electronic percussion  100  may be configured to be a built-in type where the speaker is directly disposed at the electronic percussion  100 . 
     (Operation of Electronic Percussion  100 ) 
     The following describes the operation of the electronic percussion  100  thus configured. First, the player prepares the respective electronic percussion  100 , sound source  90 , and external speaker  97 . Afterwards, the player electrically connects the electronic percussion  100  to the sound source  90  and electrically connects the sound source  90  to the external speaker. Next, after powering-ON the sound source  90 , the player operates the operation panel  93   a  to set the sound source  90  in a performance mode in which the sound source  90  can give a performance. Accordingly, the sound source  90  enters a state in which the sound source  90  detects the vibrations of the head  101  and can output the musical sound. 
     When the electric power is supplied from the sound source  90 , the light emitter  105   a  of the optical sensor  105  of the electronic percussion  100  starts emitting the light. In this case, a part of emitted light L emitted from the light emitter  105   a  transmits the head  101 . Furthermore, a part of the other emitted light L is reflected by the back surface  101   b  of the head  101  and is introduced to the light receiver  105   b . In view of this, the light receiver  105   b  continuously outputs the detection signals to the sound source  90  according to the amount of received emitted light L, the reflected light from the head  101 . 
     Next, the player adjusts the direction of the electronic percussion  100  and then starts the performance of the electronic percussion  100 . Specifically, the player adjusts the electronic percussion  100  in the direction such that the side of the head  101  to which the sensor cover body  110  is opposed becomes the near-side (that is, the direction that the sensor cover body  110  is positioned at a position farthest from the player). Afterwards, the player beats the struck surface  101   a  of the head  101  using the stick or the like. Accordingly, the head  101  of the electronic percussion  100  vibrates and warps and deforms according to the performance operation by the player. Accordingly, the amount of light entering the light receiver  105   b  changes. In this case, since the part of the struck surface  101   a  of the head  101  opposed to the light receiver  105   b  is covered with the sensor cover body  110  disposed above the struck surface  101   a , the external light is less likely to be irradiated. In view of this, as illustrated in  FIG. 3 , the light receiver  105   b  easily detects the emitted light L irradiated from the light emitter  105   a  and reflected by the back surface  101   b  of the head  101 , outputting the detection signal according to the amount of the emitted light L. 
     The detection signal output from the light receiver  105   b  is input to the sound source  90 . The sound source  90  generates the musical sound signal using the A/D converter  92 , the controller  93 , the PCM sound source unit  94 , the D/A converter  95 , and the amplifier  96  based on this detection signal and outputs the musical sound signal to the external speaker  97 . The external speaker  97  generates the sound based on the musical sound signal output from the sound source  90 . In view of this, the player can generate the musical sound according to the way of beating the struck surface  101   a  on the head  101 , namely, the performance operation, from the external speaker  97 . 
     As can be understood from the explanation on the operation, with the first embodiment, the electronic percussion  100  includes the optical sensor  105  at the one surface side of the head  101 . Furthermore, the sensor cover body  110  having the size with which the optical sensor  105  is covered is disposed at the other surface side, the opposite side of the one surface. Accordingly, the amount of light (brightness) at the back surface side of the head part to which the optical sensor  105  is opposed decreases and the reflected light from the head  101  is easily detected. In view of this, the electronic percussion  100  according to the present invention can maintain the detection accuracy of the vibration of the head  101  over a long period of time. 
     Furthermore, the implementation of the present invention is not limited to the first embodiment, and various modifications are possible without departing from the object of the present invention. Like reference numerals designate corresponding or identical elements throughout the first embodiment and the following respective modifications, and therefore such elements will not be further elaborated here. 
     For example, with the first embodiment, the sensor cover body  110  is formed so as to extend from the outer peripheral surface of the shell  103 . Meanwhile, it is only necessary that the sensor cover body  110  is disposed on the side opposite to the side where the optical sensor  105  is disposed on the head  101  with the size with which the optical sensor  105  is covered. 
     Accordingly, the sensor cover body  110  can also be mounted to the hoop  107 . In this case, for example, as illustrated in  FIG. 7 , the sensor cover body  110  can also be disposed on the inner peripheral surface of the hoop  107 . According to this, since the sensor cover body  110  is disposed on the inner peripheral part of the hoop  107 , the electronic percussion  100  does not have a projecting-out part, ensuring configuring the compact electronic percussion  100 . 
     The sensor cover body  110  can be disposed directly to the head  101 . For example, as illustrated in  FIG. 8 , the sensor cover body  110  can be formed into a sheet shape and configured to be pasted to the struck surface  101   a  of the head  101 . That is, the sensor cover body  110  is constituted of only the light-shielding portion  111 . Accordingly, the electronic percussion  100  does not have the projecting-out part by the sensor cover body  110 , ensuring configuring the compact electronic percussion  100 . In this case, the sensor cover body  110  is formed into the circular shape in a plan view, allowing the sensor cover body  110  to be less likely to peel off from the head  101 . 
     As illustrated in  FIG. 9 , the sensor cover body  110 , for example, can be constituted of a ring-shaped sheet body having an outer diameter approximately identical to the head  101 . In this case, the outer edge portion of the ring-shaped sensor cover body  110  can be held to the head frame  102  together with the outer edge portion of the head  101 . For example, as illustrated in  FIG. 10 , the sensor cover body  110  can be constituted of a ring-shaped sheet body having an outer diameter approximately identical to an exposed surface of the head  101 . In this case, the ring-shaped sensor cover body  110  can be disposed sandwiched by the two heads  101 . Accordingly, with the electronic percussion  100 , the sensor cover body  110  is formed into an annular shape along the outer edge portions of the heads  101 . When the optical sensor  105  is attached, this allows reducing a load applied to positioning between the optical sensor  105  and the sensor cover body  110 . Furthermore, the electronic percussion  100  can be constituted so as to have a sophisticated design free from a feeling of a foreign body as an appearance design. 
     With the first embodiment the electronic percussion  100  includes the optical sensor  105  at the back surface  101   b  side of the head  101  and the sensor cover body  110  at the struck surface  101   a  side. Meanwhile, it is only necessary that the electronic percussion  100  includes the optical sensor  105  at one surface side of the head  101  and the sensor cover body  110  at the other surface side. Accordingly, the electronic percussion  100  can include the optical sensor  105  at the struck surface  101   a  side of the head  101  and the sensor cover body  110  at the back surface  101   b  side. 
     In this case, for example, as illustrated in  FIG. 11 , the sensor supporting body  104  can be constituted of a plate-shaped body bending and extending from the outer peripheral surface of the shell  103  like the sensor cover body  110  according to the first embodiment. In this case, the sensor supporting body  104  can be mounted to the shell  103  by the attachment tool  113 . Like the sensor supporting body  104  according to the first embodiment, the sensor cover body  110  can be constituted of a plate-shaped body extending radially inside from the inner peripheral surface of the shell  103 . This facilitates post-installing the optical sensor  105  to the electronic percussion  100  without the optical sensor  105  and also allows the optical sensor  105  to be less likely to be affected by ambient light such as a spotlight during the performance. Disposing the sensor cover body  110  at the inside of the shell  103  allows cutting off the light from the lower side of the shell  103 . 
     When the optical sensor  105  is disposed on the struck surface  101   a  side of the head  101 , the electronic percussion  100  can be configured similar to the respective electronic percussions  100  illustrated in  FIGS. 8, 9, and 10 . That is, as illustrated in  FIG. 12 , for example, the electronic percussion  100  can be constituted such that the sensor cover body  110  formed into the sheet shape is pasted to the back surface  101   b  of the head  101 . For example, as illustrated in  FIG. 13 , the electronic percussion  100  can be configured such that the sensor cover body  110  is constituted of the ring-shaped sheet body with an outer diameter approximately identical to the head  101  and the outer edge portion is held to the head frame  102  together with the outer edge portion of the head  101 . For example, as illustrated in  FIG. 14 , the electronic percussion  100  can be constituted such that the sensor cover body  110  is constituted of the ring-shaped sheet body having an outer diameter approximately identical to the exposed surface of the head  101  and this sensor cover body  110  is sandwiched between the two heads  101 . 
     (Second Embodiment) 
     The following describes the second embodiment of the electronic percussion according to the present invention with reference to  FIGS. 15 to 20 . This second embodiment mainly describes parts different from the first embodiment. As illustrated in  FIG. 15 , an electronic percussion  200  according to this second embodiment features the following. The electronic percussion  200  includes the optical sensor  105 , which is similar to the first embodiment, disposed opposed at one surface side of the head  101 , and a sensor-opposed body  120  at a part of this head  101 , disposed opposed to the optical sensor  105 . The sensor-opposed body  120  has a plate shape or a flexible sheet shape that reflects the emitted light L irradiated by the light emitter  105   a.    
     In this case, a surface of the sensor-opposed body  120  opposed to the optical sensor  105  is formed so as to have a high reflectivity (reflectance of 50% or more, more preferably 70% or more) such as a light color such as white or a metal color. Furthermore, the sensor-opposed body  120  is formed so as to have a size (an area) larger than a size (an area) of the optical sensor  105  in a plan view. The surface on the side opposite to the surface opposed to the optical sensor  105  of this sensor-opposed body  120  is pasted to the back surface  101   b  of the head  101 . 
     With the electronic percussion  200  thus configured according to the second embodiment, the emitted light L emitted from the light emitter  105   a  is reflected by the sensor-opposed body  120  and a part of the emitted light L is introduced to the light receiver  105   b . In view of this, the light receiver  105   b  continuously outputs the detection signals to the sound source  90  according to the amount of received emitted light L, the reflected light from the sensor-opposed body  120  integrated with the head  101 . With the electronic percussion  200 , while the player gives the performance, the sensor-opposed body  120  vibrates and warps and deforms integrally with the head  101  according to the performance operation by the player. This changes the amount of light entering the light receiver  105   b.    
     In this case, the electronic percussion  200  includes the sensor-opposed body  120  with the high reflectivity at the part of the back surface  101   b  of the head  101  opposed to the light receiver  105   b . In view of this, the light receiver  105   b  easily detects the emitted light L irradiated from the light emitter  105   a  and reflected by the sensor-opposed body  120 ; therefore, the detection signal according to the amount of the emitted light L can be output. 
     As can be understood from the explanation on the operation, with the second embodiment, with the electronic percussion  200 , the sensor-opposed body  120  is less likely to partially peel off and drop due to the hitting of the head  101 . Accordingly, the detection accuracy of the vibration of the head  101  can be maintained over a long period of time. The electronic percussion  200  includes the respective optical sensor  105  and sensor-opposed body  120  at the back surface  101   b  side of the head  101 . Therefore, the appearance can be better. In the case where the head  101  is formed into the mesh pattern in the electronic percussion  200 , since the sensor-opposed body  120  is formed into the planar shape, the sensor-opposed body  120  can efficiently reflect the emitted light L emitted from the light emitter  105   a.    
     Furthermore, the implementation of the present invention is not limited to the second embodiment, and various modifications are possible without departing from the object of the present invention. Like reference numerals designate corresponding or identical elements throughout the second embodiment and the following respective modifications, and therefore such elements will not be further elaborated here. 
     For example, with the second embodiment, the sensor-opposed body  120  can be formed into the circular shape in a plan view. Meanwhile, as illustrated in  FIG. 16 , the sensor-opposed body  120 , for example, can be constituted of a ring-shaped sheet body having an outer diameter approximately identical to the head  101 . In this case, the outer edge portion of the ring-shaped sensor-opposed body  120  can be held to the head frame  102  together with the outer edge portion of the head  101 . 
     With the second embodiment, the electronic percussion  200  includes the respective optical sensor  105  and sensor-opposed body  120  at the back surface  101   b  side of the head  101 . Meanwhile, it is only necessary that the electronic percussion  200  includes the respective optical sensor  105  and sensor-opposed body  120  at one surface side of the head  101 . Accordingly, the electronic percussion  200  can also be configured such that the respective optical sensor  105  and sensor-opposed body  120  are disposed at the struck surface  101   a  side of the head  101 . 
     In this case, for example, as illustrated in  FIG. 17 , the optical sensor  105  is supported to a position separated from the struck surface  101   a  of the head  101  by the sensor supporting body  104  formed of the plate-shaped body bending and extending from the outer peripheral surface of the shell  103  similar to  FIG. 11 . Similar to the second embodiment, the sensor-opposed body  120  can be constituted so as to be formed into the plate shape or the sheet shape and be directly pasted on the struck surface  101   a  of the head  101  to which the optical sensor  105  supported by the sensor supporting body  104  is opposed. 
     As illustrated in  FIG. 18 , the sensor-opposed body  120 , for example, can be constituted of the ring-shaped sheet body having an outer diameter approximately identical to the head  101  similar to  FIG. 16 . In this case, the outer edge portion of the ring-shaped sensor-opposed body  120  can be held to the head frame  102  together with the outer edge portion of the head  101 . 
     The first embodiment and the second embodiment integrally configure the light emitter  105   a  and the light receiver  105   b  in the optical sensor  105 . Meanwhile, the respective light emitter  105   a  and light receiver  105   b  may be constituted separately in the optical sensor  105 . 
     The first embodiment and the second embodiment include the optical sensor  105  at the end of the head  101  on the side opposite to the player side. In view of this, the electronic percussions  100  and  200  include the optical sensor  105  at the end of the head  101  on the side opposite to the player side. This ensures facilitating the performance and also can prevent received damage of the optical sensor  105 , the sensor cover body  110 , and the sensor-opposed body  120 . Meanwhile, as long as the optical sensor  105  is at the position where the vibration of the head  101  can be optically detected, the position is not always limited to the respective embodiments. 
     Accordingly, the optical sensor  105 , for example, may be disposed at one or both of right and left end sides with respect to the player. That is, the one electronic percussion  100  can include the plurality of optical sensors  105 . In this case, the electronic percussion  100  can be constituted so as to generate the musical sound according to an addition of the respective detection signals from the plurality of optical sensors  105  or the musical sound according to the respective detection signals. 
     With this embodiment, the electronic percussion  100  is constituted of a snare drum type electronic drum. Meanwhile, the electronic percussion  100  is widely applicable to an electronic musical instrument that detects the vibration and the pressure change on the struck surface when the struck surface is beaten and rubbed by the hand, the stick, or the like to generate the electronic musical sound. Accordingly, the electronic percussion  100  can be configured as an electronic bass drum or an electronic percussion. 
     DESCRIPTION OF REFERENCE SIGNS 
     
         
         L: Emitted light 
           90 : Sound source 
           91 : Power supply 
           92 : A/D converter 
           93 : Controller 
           93   a : Operation panel 
           94 : PCM sound source unit 
           95 : D/A converter 
           96 : Amplifier 
           97 : External speaker 
           100 ,  200 : Electronic percussion 
           101 : Head 
           101   a : Struck surface 
           101   b : Back surface 
           102 : Head frame 
           103 : Shell 
           104 : Sensor supporting body 
           105 : Optical sensor 
           105   a : Light-emitting device 
           105   b : Light receiver 
           106 : Rug 
           107 : Hoop 
           108 : Tension bolt 
           110 : Sensor cover body 
           111 : Light shielding portion 
           112 : Supporter 
           113 : Attachment tool 
           120 : Sensor-opposed body