Patent Publication Number: US-10311846-B2

Title: Keyboard musical instrument and method of acquiring correction information in keyboard musical instrument

Description:
TECHNICAL FIELD 
     The present invention relates to a keyboard musical instrument having a displacement member that operates by a key depression operation and a method of acquiring correction information in the keyboard musical instrument. 
     DESCRIPTION OF THE RELATED ART 
     Conventionally, keyboard musical instruments are available that have a displacement member, such as a hammer or the like, that is driven and is moved directly or indirectly with a key by the key depression operation. In this kind of musical instrument, a keyboard musical instrument is also available in which the operation of a key or a displacement member is detected, and a musical sound is controlled on the basis of the result of the detection. For example, in the musical instrument of Japanese Laid-Open Patent Publication (Kokai) No. 2013-210451, a musical sound is generated from the key depression speed detected by the two switches, and when one switch detects that the hammer reaches a predetermined turning position, a musical sound is generated. 
     However, since the key and the displacement member such as a hammer usually are turned around different fulcrums, it is difficult to accurately maintain the relative position of the key and the displacement member at the time of manufacturing. In addition, it is also difficult to ensure high relative arrangement accuracy of detection parts such as a key sensor and a hammer sensor that detect the operation of the key and the displacement member. Furthermore, the key and the displacement member can be deformed by long-term use. Thus, the detection result by the sensor can also change. Therefore, in a case where the velocity, sound generation timing, etc. are determined on the basis of the detection result of the operation of the key and the detection result of the operation of the displacement member, they are affected by dimensional accuracy, assembly deviation, and aging of parts and detection parts. 
     For example, in a case where the value obtained by dividing the distance from the detection of the key sensor to the detection of the hammer sensor by the time difference is calculated as the key depression velocity, the positional accuracy between the key sensor and the hammer sensor is important. If the positional accuracy is lowered, musical sound control with high accuracy cannot be expected. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a keyboard musical instrument capable of performing proper musical sound control by correcting variations in detection mechanism and a method of acquiring correction information in the keyboard musical instrument. 
     In order to achieve the above object, according to the present invention, a keyboard musical instrument is provided which includes a key; displacement members ( 11 ) that are directly or indirectly driven and moved by the key due to a depression operation of the key, a first detection unit (SW 1 , SW 2 ) configured to detect at least a position (pSW 1 , pSW 2 ) and a speed (V 21 ) of the key or a first member out of the displacement members; a second detection unit (SW 3 ) configured to detect at least a position (pSW 3 ) of a second member other than the first member out of the displacement members; a storage unit ( 47 ) configured to store correction information (J, calST 32 ); a derivation unit ( 45 ) configured to derive the correction information as an amount to be used for correcting a deviation with respect to a designed value of a physical quantity used for musical sound control (Formula 1) on the basis of a detection timing (rT 2 ) of the position by the first detection unit, the speed (V 21 ) detected by the first detection unit, and a detection timing (rT 3 ) of the position by the second detection unit in a case where the key is operated in a derivation mode, and cause the storage unit to store the correction information; and a musical sound control unit ( 45 ) configured to control a musical sound on the basis of the detection timing of the position by the first detection unit, the detection timing of the position by the second detection unit, and the correction information stored in the storage unit in a performance mode. 
     In order to achieve the above object, according to the present invention, a method of acquiring correction information in a keyboard musical instrument is provided, in which the keyboard musical instrument includes a key, displacement members that are directly or indirectly driven and moved by the key due to a depression operation of the key, a first detection unit configured to detect at least a position of the key or a first member out of the displacement members, a second detection unit configured to detect at least a position of a second member other than the first member out of the displacement members, a storage unit configured to store correction information, and a musical sound control unit configured to control a musical sound on the basis of a detection timing of the position by the first detection unit, a detection timing of a position by the second detection unit, and the correction information stored in the storage unit in a performance mode, and the method includes deriving the correction information as an amount to be used for correcting a deviation with respect to a designed value of a physical quantity used for musical sound control on the basis of the detection timing (rT 2 ) of the position by the first detection unit, and a detection timing (rT 3 ) of the position by the second detection unit in a case where the key is operated in a predetermined operation mode (Vplay) in which an operation speed and a speed change are defined in a derivation mode, and causing the storage unit to store the correction information. 
     In order to achieve the above object, according to the present invention, a method of acquiring correction information in a keyboard musical instrument is provided, in which the keyboard musical instrument includes a key, displacement members that are directly or indirectly driven and moved by the key due to a depression operation of the key, a first detection unit configured to detect at least a position and a speed of the key or a first member out of the displacement members, a second detection unit configured to detect at least a position of a second member other than the first member out of the displacement members, a storage unit configured to store correction information, and a musical sound control unit configured to control a musical sound on the basis of the detection timing of the position by the first detection unit, the detection timing of the position by the second detection unit, and the correction information stored in the storage unit in a performance mode, and the method includes deriving the correction information as an amount to be used for correcting a deviation with respect to a designed value of a physical quantity used for musical sound control on the basis of a detection timing (rT 2 ) of the position by the first detection unit, the speed (V 21 ) detected by the first detection unit, and a detection timing (rT 3 ) of the position by the second detection unit in a case where the key is operated in a derivation mode, and causing the storage unit to store the correction information. 
     It should be noted that the above-mentioned reference numerals in parentheses are examples. 
     According to the present invention, variations in the detection mechanism can be corrected so that appropriate musical sound control can be performed. 
     According to the present invention, highly reliable correction information can be derived, appropriate sound generation control can be performed, and appropriate silencing control can be performed. In addition, according to the present invention, appropriate silencing control can be performed, the determination accuracy of the key velocity can be enhanced, and the reliability of the key depression speed to be detected can be enhanced. Furthermore, according to the present invention, it is possible to prevent the detection result with a large deviation from being used for musical sound control. 
     Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a longitudinal sectional view of a keyboard musical instrument according to an embodiment of the present invention. 
         FIG. 2  is a side view of one action mechanism and its peripheral elements. 
         FIG. 3A  is a side view showing a configuration of a detection section,  FIG. 3B  is a front view showing a configuration of a detection section,  FIG. 3C  is a sectional view showing a configuration of a detection section, and  FIG. 3D  is a sectional view showing a configuration of a detection section. 
         FIG. 4A  is a block diagram showing the overall configuration of the keyboard musical instrument,  FIG. 4B  is a conceptual diagram showing information on a detection result in the detection section. 
         FIG. 5A  is a conceptual diagram of a database, and  FIG. 5B  is a conceptual diagram of data constituting correction information. 
         FIG. 6A  to  FIG. 6C  are diagrams showing the relations between time and key stroke in a key depression/release stroke. 
         FIG. 7A  to  FIG. 7C  are diagrams showing the relations between time and key stroke in the key depression/release stroke. 
         FIG. 8  is a flowchart showing a correction information storage process in a derivation mode. 
         FIG. 9  is a flowchart showing a musical sound control process. 
         FIG. 10A  and  FIG. 10B  are diagrams showing the relations between time and key stroke in the key depression/release stroke. 
         FIG. 11  is a side view of an action mechanism of an upright piano. 
     
    
    
     DESCRIPTION OF THE EMBODIMENT 
     Hereinafter, embodiments of the present invention will be described with reference to the drawings. 
       FIG. 1  is a longitudinal sectional view of a keyboard musical instrument according to an embodiment of the present invention.  FIG. 1  mainly shows the configuration of one key K, a corresponding action mechanism ACT and the like. 
     This keyboard musical instrument is configured as a grand piano type electronic keyboard musical instrument, and a plurality of keys K, which are white keys and black keys, are arranged in parallel. The action mechanism ACT is disposed above the rear end of the key K in correspondence with each key K. Each of the keys K is freely turnably disposed clockwise and counterclockwise in  FIG. 1  around a portion in the vicinity of a balance pin  74  in a key fulcrum portion  70  as a fulcrum. The right side of  FIG. 1  is the player side and the front side, the left side is the back side. The front portion of the key K is depressed/released. 
     This keyboard musical instrument can generate sounds by hitting a string  19  by a hammer  11  and also detect the movement and position of the constituent elements in the action mechanism ACT, or the like to generate sound electronically. It should be noted that a silencing stopper  60  is positionally variably attached to a base  76  including a keyboard comb, and the position of the silencing stopper  60  can be switched by an operation of an operation element (not shown). In a case where music is played in the normal sound generation mode in the performance mode, the silencing stopper  60  can be positioned at a position where the hammer  11  does not come into contact with the silencing stopper  60 , whereas when music is played in the silencing mode in the performance mode, the silencing stopper  60  is positioned so as to come into contact with the hammer  11 , so that the hammer  11  does not come into contact with the string  19 . 
     Front bushing cloths  64 A and  64 B are disposed at the front lower portion of the key K. In the base  76 , front punching cloths  63 A and  63 B are disposed so as to correspond to the positions of the front bushing cloths  64 A and  64 B. By a key depression operation, the front bushing cloths  64 A and  64 B come into contact with the front punching cloths  63 A and  63 B, so that the turning end position (end position) of the key K is restricted. Movement of the front portion of each key K in the key arrangement direction is restricted by front pins  75 A and  75 B during the key depression operation. 
     A conductive unit  66  is disposed at the lower portion of the rear portion of the key K. A back rail cloth  65  is disposed on the base  76  via a back rail under felt in correspondence with the conductive unit  66 . When the lower surface of the rear portion of the key K comes into contact with the back rail cloth  65 , the conductive unit  66  comes into contact with the back rail cloth  65 , and the initial position of the key K in the non key depression state, that is, the turning start position (rest position) is restricted. 
     An electric circuit board  61  is fixedly arranged with respect to the base  76 . In addition, the electric circuit board  62  is fixedly arranged with respect to an action bracket  77 . Although there are other electric circuit boards, illustration thereof is omitted. 
       FIG. 2  is a side view of one action mechanism ACT and its peripheral elements. 
     A capstan screw  4  is implanted onto the upper surface of the rear end of the key K. A back check  35  is disposed on the upper portion of the rear end of the key K. A damper lever  67  is pivotally supported by a damper lever flange  78  located behind the key K. In addition, the damper lever  67  is pivotally supported by a damper block  69 , and a damper  79  is fixed to the damper block  69 . 
     The action mechanism ACT mainly includes a wippen  5 , a jack  6 , a repetition lever  8 , and the like. A turning fulcrum  23  of the rear end  5   a  of the wippen  5  is pivotally supported by a support flange  2  fixed to a support rail  3 , and a front end  5   b , which is a free end, is freely turnable vertically around the turning fulcrum  23 . A hammer shank top felt  20  is disposed on the upper surface of the wippen  5  on the turning fulcrum  23  side. A jack stop  33  protrudes from the upper part of the front half portion of the wippen  5 . 
     A repetition lever flange  7  upwardly protrudes from the center of the wippen  5  in the front-rear direction. The repetition lever  8  is rotatably supported clockwise and counterclockwise around the turning fulcrum  7   a  of the upper end of the repetition lever flange  7 . The jack  6  has a vertical portion  6   a  extending substantially upward and a jack small portion  6   b  extending forward in a substantially horizontal direction, and has a substantially L-shape in a side view. The jack  6  is disposed on the turning fulcrum  36  of the front end  5   b  of the wippen  5  so as to be rotatable clockwise and counterclockwise in  FIG. 2 . 
     The jack stop  33  includes a jack button screw  32  and a jack button  31  disposed at the rear end of the jack button screw  32 . In the non key depression state (key released state), the jack  6  comes into contact with the jack button  31 , the initial position of the jack  6  is restricted, and the initial position can be adjusted by the jack button screw  32 . 
     A shank flange  9  is fixed to a shank rail  10 . A regulating button  25  is disposed so as to be adjustable in height with respect to a regulating rail  100  attached to the shank rail  10 . A repetition screw  34  is provided at the lower portion of the shank flange  9 . The hammer  11  is disposed above the repetition lever  8 . The front end of a hammer shank  16  of the hammer  11  is pivotally vertically supported with respect to the shank flange  9  around the turning center  13 . A hammer wood  17  is attached to the rear end of the hammer shank  16 , in which the rear end of the hammer shank  16  is free. A hammer felt  18  is attached to the upper end of the hammer wood  17 . A hammer roller  14  is disposed in the vicinity of the front end of the hammer shank  16 . 
     In the non key depression state, the repetition lever  8  receives the hammer roller  14  on the upper surface of the front end of the repetition lever  8  from the lower side and restricts the hammer  11  to the initial position. On the other hand, a repetition lever button  15  is disposed on the rear end of the repetition lever  8  so as to be adjustable in height. The button  15  comes into contact with the upper surface of the rear end  5   a  of the wippen  5 , whereby the turning of the repetition lever  8  counterclockwise is restricted, and the repetition lever  8  is restricted to the initial position. An elongated hole  21  is formed at the front end portion of the repetition lever  8 . The vertical portion  6   a  of the jack  6  is inserted into the elongated hole  21  and a top end surface  22  of the vertical portion  6   a  is substantially flush with the upper surface of the repetition lever  8 . 
     In such a configuration, in the normal key depression forward stroke in which the key K is depressed from the non key depression state, the wippen  5  is pushed up by the rise of the capstan screw  4  and is turned counterclockwise, which is the forward direction, around the turning fulcrum  23 . By pushing up the wippen  5 , the repetition lever  8  and the jack  6  is turned upward together with the wippen  5 . Along with these turning, the repetition lever  8  and the vertical portion  6   a  of the jack  6  push up the hammer  11  via the hammer roller  14  to turn it upward while turning or sliding the hammer roller  14 . 
     On the other hand, as the key K is turned in the forward direction, a damper lever cushion  68  disposed at the upper portion of the rear end of the key K pushes up the front end portion of the damper lever  67 . Then, the damper  79  is raised via the damper block  69 , and the damper  79  (more exactly, a damper felt provided at the lower portion of the damper  79 ) is spaced away from the string  19 . In the present embodiment, a damper distance d described later is a distance from the damper  79  to the string  19  at the end of key depression. 
     Next, when the repetition lever  8  comes into engagement contact with the repetition screw  34 , whereby the counterclockwise displacement (upper limit position) of the repetition lever  8  is restricted, the top end surface  22  of the vertical portion  6   a  of the jack  6  protrudes through the elongated hole  21  of the repetition lever  8 , and the hammer roller  14  is driven by the top end surface  22 , so that the hammer  11  is pushed up. 
     When the wippen  5  is further turned in the forward direction, the jack small portion  6   b  of the jack  6  comes into contact with the lower surface of the regulating button  25  (more exactly, a regulating button punching) during the turning thereof and is inhibited from rising. However, since the wippen  5  itself is still turned, the jack  6  is turned clockwise around the turning fulcrum  36 . Therefore, the top end surface  22  of the vertical portion  6   a  of the jack  6  escapes forward from the lower side of the hammer roller  14  forward and moves away from it. As a result, the hammer  11  is disengaged from the jack  6  and strikes the string  19  in a freely turnable state. After the strike, the hammer  11  is turned and returned by its own weight and the repulsive force of the string  19 . It should be noted that in the silencing mode, the silencing stopper  60  restricts the turning of the hammer shank  16  of the hammer  11 , whereby the hammer shank  16  does not come into contact with the string  19 . 
     When the key depression state is maintained after the completion of the key depression, the hammer wood  17  of the hammer  11  bounced by the string  19  is received by the back check  35  (more exactly, back check cloth  35   a ), and the hammer wood  17  is stopped there. When the key K is released and the back check  35  is disengaged from the hammer  11 , the repetition lever  8  is turned counterclockwise by the urging force of a repetition urging unit  12   b , and the hammer roller  14  is supported by the repetition lever  8 . 
     In addition, after the string striking action, the jack  6  is released from the regulating button  25  as the wippen  5  is turned and returned. The jack  6  is turned counterclockwise by the urging force of the jack urging portion  12   a , and returned to the initial position. Even if the key K does not completely return to the non-key depression position, the top end surface  22  of the vertical portion  6   a  of the jack  6  quickly returns to the lower side position of the hammer roller  14  so that the next string striking action by the second depression of the key can be performed. That is, fast four-handed performance is possible. 
     In the present embodiment, a member that is directly or indirectly driven by the key K to be displaced (moves) in the forward direction due to the key depression operation, and that moves in the backward direction by releasing the key K is referred to as the “displacement member”. 
     In addition, in this keyboard musical instrument, a constituent element, of which the engagement state with respect to an object to be engaged can be changed in the stroke of the key depression/release operation, will be referred to as the “constituent member”. The constituent member includes not only a single component but also component members configured as an integrated unit or component members movable as an integrated unit. For example, in addition to the key K and the hammer  11 , and elements intervened in the system ranging from the key K to the hammer  11  and elements for restricting the turning start position and the turning stop position of the key K and the hammer  11  correspond to the constituent members. More specifically, in addition to the above-mentioned items, the elements designated by reference numerals  5 ,  6 ,  7 ,  8 ,  9 ,  11 ,  15 ,  19 ,  20 ,  25 ,  31 ,  34 ,  35 ,  60 ,  63 ,  65 ,  79 , etc. can correspond to the constituent members. It should be noted that the elements  64 ,  66  and  68  may be regarded as portions of the key K. The elements  14 ,  16 ,  17 , and  18  may be regarded as portions of the hammer  11 . The movable constituent member other than the key K can correspond to the “displacement member”. It should be noted that the constituent members are not limited to these items taken as examples. 
     The keyboard musical instrument includes a plurality of detection sections SW (detection sections SW 1 , SW 2 , SW 3 , SW 101  to  104 ) for the key K. The detection sections SW detect the operations of the key K and the displacement members or the engagement states of the constituent members to be engageable with each other. The detection section SW 3  is disposed on the lower surface of the silencing stopper  60 . Hence, in the silencing mode, the hammer  11  comes into contact with the detection section SW 3  and indirectly comes contact with the silencing stopper  60  via the detection section SW 3 . 
     In the present embodiment, the hammer  11  is taken as an example of the displacement member, and musical sound information including key velocity is generated on the basis of the detection results by the detection sections SW 1 , SW 2 , and SW 3 , and the sound generation/silencing timing is determined. 
       FIGS. 3A and 3B  are a side view and a front view showing the structures of the detection sections SW 1  and SW 2 . The detection sections SW 1  and SW 2  are photo-interrupter type optical sensors and include a shutter member  121  attached to the lower surface of the key K and an interrupter unit  125  fixed to the base  76 . The interrupter unit  125  has a pair of a light emitting unit  83  and a light receiving unit  84 . The shutter member  121  is integrally formed of resin or the like, and is formed of a material having a light shielding property or has a light shielding material applied to its surface. The shutter member  121  includes a window  122 . The lower edge of the shutter member  121  is a first boundary  123  and the lower edge of the window  122  is a second boundary  124 . When the first boundary  123  and the second boundary  124  pass through an optical path from the light emitting unit  83  to the light receiving unit  84  in the forward direction, the detection sections SW 1  and SW 2  sequentially turn ON. When the first boundary  123  and the second boundary  124  pass through the optical path in the backward direction, the detection sections SW 2  and SW 1  are sequentially turned off. 
       FIG. 3C  is a sectional view showing a configuration of a detection section SW 3 . The detection section SW 3  is configured as a make-switch having a small pressing stroke and has a driven unit  87  on the lower side thereof, in which the driven unit  87  expands downward in a dome shape. When the driven unit  87  is driven by the hammer  11 , a movable contact  85  comes into contact with a fixed contact  86  disposed on the lower surface of the silencing stopper  60 , whereby the detection section SW 3  electrically turns ON. Inside the dome, a stopper unit  88  located farther away from the lower surface of the silencing stopper  60  than the movable contacts  85  in the non key depression state is disposed. 
     The start point of the whole turning stroke serving as the operation range of the hammer  11  in the silencing mode is restricted when the hammer  11  comes into contact with the repetition lever  8 . On the other hand, the end point of the whole stroke is restricted when the stopper unit  88  comes into contact with the lower surface of the silencing stopper  60 . The detection section SW 3  maintains its ON state only when the hammer  11  is located at a position (upper position) deeper than a predetermined position. 
     It should be noted that the detection section for detecting the operation of the key K is not limited to the one illustrated in  FIGS. 3A and 3B . It may be constituted by a resiliently swollen electric contact type switch similar to the switch shown in  FIG. 3C . In this case, the detection section for detecting the operation of the key K may detect the position at one location. For example, as shown in  FIG. 3D , the detection sections may detect at a plurality of different stroke positions, for example, at three or more locations. 
     The detection sections SW 101  to SW 104  may merely be configured so as to be able to detect the operation of the key K and the displacement member, and it is possible to employ a configuration that matches the arrangement location. For example, the detection section SW 104  ( FIG. 2 ) has the same configuration as the detection section SW 3 . The detection section SW 104  is disposed at the lower portion of a stop rail  81 . 
     For detection sections SW 101 , SW 102 , and SW 103 , a switch having an ordinary switch which turns ON by contact or by change in pressure may be employed. In this embodiment, a configuration in which the engagement state of the constituent members is detected depending on the state of the electrical conduction between the constituent members is employed as an example. More specifically, each of the engaged sections of the constituent members, in which the engaged sections are engaged with each other, is configured so as to have conductivity, and a CPU  45  ( FIG. 4A ) detects the engagement state of the constituent members by utilizing the fact that conduction occurs when the constituent members come into contact with each other and that non-conduction occurs when they are spaced away from each other. 
     In order to easily realize the above-mentioned conduction configuration, for example, conductive materials are disposed in the region of the engaged sections, which are engaged with each other. As a conductive material, graphite, conductive rubber, conductive nonwoven fabric, copper plate, conductive coating (conductive grease), or the like is disposed on at least the surface of the engaged region or the engaged surface. In a case where cloth, or the like is used, the entire cloth may be formed of a conductive material. Alternatively, the whole or at least the respective engaged sections of the movable constituent members and the corresponding constituent members may be made of a conductor or a conductive material. For example, the whole or the engaged sections of the constituent members are formed of resin. The configurations having conductivity may be different between the movable constituent members and the corresponding constituent members. 
     For the detection section SW 103 , both (the damper lever cushion  68  of) the key K and (the contact unit  67   a  of) the damper lever  67  are made of conductors. For the detection section SW 102 , both the regulating button  25  and (the jack small portion  6   b  of) the jack  6  are made of conductors. For the detection section SW 101 , both the back rail cloth  65  and (the conductive unit  66  of) the key K are made of conductors. A configuration similar to that described above is applicable to constituent members other than the above constituent members. It should be noted that both the jack  6  and the hammer roller  14  may be made of conductors. 
     The conductive unit having conductivity are electrically connected to the electric circuit board. In  FIG. 2 , the electric circuit board is not shown. As shown in  FIG. 1 , for example, the conductive unit of the jack  6  is connected to the electric circuit board  62  with a wire  72  such as a flexible lead, and the hammer roller  14  is also connected to the electric circuit board  62  with a wire  73 . In addition, the front bushing cloths  64 A and  64 B are connected to the electric circuit board  61  with a wire  71 , and the front punching cloths  63 A and  63 B are also connected to the electric circuit board  61  with a wire (not shown). The conductive units of other engaged sections are also appropriately connected to the electric circuit boards  61  and  62  or an electric circuit board (not shown) with a wire. 
     Each detection section SW electrically turns ON when it becomes conductive, and electrically turns OFF when it becomes non-conductive. However, in the present embodiment, in a case where it is detected that the key K and the displacement member are located at a position in the forward direction from a certain position in the key depression forward stroke regardless of the electrical ON/OFF, it is defined that each detection section SW switches from OFF to ON. 
     On the other hand, as in the detection section SW 101 , the back rail cloth  65  is spaced away from the conductive unit  66  of the key K when the key is depressed even just a little bit, and the detection section SW 101  turns OFF. In this type of detection section that turns ON electrically in the non key depression state, the key depression operation is detected when the detection section electrically turns OFF. Hence, when the detection section electrically turns OFF, the detection result is regarded as ON. It should be noted that a detection section SW other than the illustrated ones may be provided. 
       FIG. 4A  is a block diagram showing the whole configuration of the keyboard musical instrument. The keyboard musical instrument has a detection circuit  43 , a detection circuit  44 , a ROM  46 , a RAM  47 , a timer  48 , a display device  49 , an external storage device  50 , various interfaces (I/F)  51 , a memory  57 , a sound source circuit  53 , and an effect circuit  54 , all of which are connected to the CPU  45  via a bus  56 . 
     Furthermore, the detection section SW is connected to the detection circuit  44 . Various operation elements  41  include a performing operation element such as the key K. The timer  48  is connected to the CPU  45 , and a sound system  55  is connected to the sound source circuit  53  via the effect circuit  54 . 
     The detection circuit  43  detects the operation states of the various operation elements  41 . The detection circuit  44  detects the conduction states of the detection sections SW and supplies the detection results to the CPU  45 . The CPU  45  controls the whole keyboard musical instrument. The ROM  46  stores control programs to be executed by the CPU  45 , various table data, etc. The RAM  47  temporarily stores various input information such as performance data and text data, various flags, buffer data, operation results, etc. The timer  48  counts an interruption time in a timer interruption process and various times. The various interfaces (I/F)  51  include a MIDI interface and a communication interface. The sound source circuit  53  converts performance data having been input from the various operation elements  41 , preset performance data, etc. into musical sound signals. The effect circuit  54  gives various effects to musical sound signals to be input from the sound source circuit  53 , and the sound system  55  including a DAC (digital-to-analog converter), an amplifier, speakers, etc. converts musical sound signals and the like to be input from the effect circuit  54  into sound. The memory  57  is a nonvolatile readable/writable storage device. 
       FIG. 4B  is a conceptual diagram indicating the information of the detection results in the detection section SW, the information being stored in a register. The information of the detection results in the detection sections SW is information indicating ON/OFF conduction states and change times when ON/OFF switching has occurred, and the information for all the detection sections SW is stored in the register of the RAM  47  for each key K. It should be noted that the information on the detection sections SW which does not use the detection information is not necessary to be stored. 
       FIG. 5A  is a conceptual diagram of a database stored in a correction information storage process. The correction information storage process is a process for implementing a method of acquiring correction information. In this process, as will be described later with reference to  FIG. 8 , correction information J and various parameters are derived from the detection result by the detection section SW when the key K is operated in the correction information derivation mode. Information such as the derived correction information J and the like is databased and stored in the memory  57  for each key K.  FIG. 5B  is a conceptual diagram of data constituting correction information J. In the present embodiment, an example is shown in which these pieces of information are acquired from the detection results by the three detection sections SW 1 , SW 2 , and SW 3 . 
       FIG. 6A  to  FIG. 6C  are diagrams showing the relations between time and key stroke in a key depression/release stroke. The horizontal axis shows the elapsed time from the start of the key depression, and the vertical axis shows the key stroke. On the vertical axis, the detection positions of the objects by the detection sections SW 1 , SW 2 , and SW 3  are written as “pSW 1  and pSW 2 , and pSW 3 ”. In particular,  FIG. 6A  shows a change in operation of the key K in a constant speed key depression in the derivation mode, and  FIGS. 6B and 6C  show changes in operation of the key K in performance in the silencing mode. 
     First, explanation will be made with reference to  FIG. 6A . In the key depression forward stroke, the positions of the key K are detected by the detection sections SW 1  and SW 2  sequentially, and thereafter the position of the hammer  11  is detected by the detection section SW 3 . “pSW 1  and pSW 2 ” on the vertical axis indicate the stroke positions of the key K. “pSW 3 ” on the vertical axis indicate the stroke position of the key K which is assumed at the time when the hammer  11  is detected by the detection section SW 3  in the constant speed key depression. It should be noted that the constant speed key depression described here is a speed at which the hammer  11  is turned with inertia to depress the detection section SW 3  after the jack  6  has come out (escaped) from the hammer roller  14  accompanied by the turning of the key K, and the key depression speed is Vplay. 
     Hereinafter, from the start of the key depression, the time until the key K and the hammer  11  are detected by the detection sections SW 1 , SW 2 , and SW 3  is taken as T 1 , T 2 , and T 3 . The time difference from the time T 1  to the time T 2  is described as a time difference T 21 . Similarly, the time difference from the time T 1  to the time T 3 , and the time difference from the time T 2  to the time T 3  are described as the time differences T 31  and T 32 , respectively. The stroke (the physical quantity corresponding to the movement stroke of the key K moving between the detection timings by the detection sections SW 1  and SW 2 ) between the detection positions of the detection sections SW 1  and SW 2  is described a stroke ST 21 . Similarly, the stroke between the detection positions of the detection sections SW 1  and SW 3 , and the stroke between the detection positions of the detection sections SW 2  and SW 3  are described as strokes ST 31  and ST 32 , respectively. 
     Here, these physical quantities differ between the measured value and the designed value (known). Hereinafter, “r” is added to the head of the measured value or the amount derived from the measured value, and “s” is added to the head of the amount of the designed value to distinguish between the measured value and the designed value. For example, as shown in  FIG. 6A  or  FIG. 6B , measured values corresponding to the times T 1 , T 2 , and T 3  are described as times rT 1 , rT 2 , and rT 3 . The measured values corresponding to the time differences T 31 , T 32 , and T 21  are described as time differences rT 31 , rT 32 , and rT 21 . The physical quantities corresponding to the strokes ST 31 , ST 32 , and ST 21 , and derived on the basis of the measured values are described the strokes rST 31 , rST 32 , and rST 21 . It should be noted that since the detection section SW 3  is used as a sound generation trigger and since the detection position by the detection section SW 3  as the absolute position has high reliability, the time rT 3  and the time sT 3  coincide with each other in a case where the constant speed key depression is performed. 
     On the other hand, since the key K is deformed due to aging, the relative positional relations between the key K and the detection section SW 1 , SW 2  can be changed. In addition, it is difficult to ensure high accuracy with respect to the relative positional relation between the key K and the hammer  11 . Due to these circumstances, the reliability of the absolute value of the detection results by the detection sections SW 1  and SW 2  is not so high, and the reliability of the relative values of the detection results by the detection section SW 1  and the detection section SW 2  with respect to the detection section SW 3  is not so high. Therefore, as illustrated in  FIG. 6B  and  FIG. 6C , a deviation may occur between the measured stroke rST (for example, rST 31  and rST 32 ) and the design stroke sST (for example, sST 31  and sST 32 ). However, since the shutter member  121  is integrally formed, the reliability of the relative positional relation (distance) between the first boundary  123  and the second boundary  124  is high. Therefore, it can be assumed that the stroke rST 21  and the stroke sST 21  coincide with each other. In addition, it can be assumed that the time difference rT 21  coincides with the time difference sT 21  in a case of performing the constant speed key depression. 
     In the database shown in  FIG. 5A , in addition to the correction information J, various parameters include the strokes rST 32  and rST 31 , a deviation Δd, designation of a silencing trigger SW, and others. The deviation Δd is a value indicating a deviation (a deviation from the damper position) between the OFF detection position by the detection section SW 2  and the damper distance d in a case where the silencing trigger SW is regarded as the detection section SW 2 . The starting point of the damper distance d in the key release direction is a position corresponding to the key depression end, for example, the detection position by the detection section SW 3 . The starting point may be any position as long as the distance from the detection position is known. The deviation Δd will be described in detail with reference to  FIGS. 7A to 7C . The silencing trigger SW is information for designating which of the detection sections SW 1  and SW 2  should be used as a trigger for starting silencing. It should be noted that hereinafter, a method of using the detection section SW 3  will be described first, and a method of using the silencing trigger SW will be described later as a modification ( FIGS. 7B and 7C ). 
     These various parameters (the strokes rST 32  and rST 31 , the deviation Δd, the designation of the silencing trigger SW and others) can be derived from the correction information J at the stage of musical sound control by calculation or the like. In the present embodiment, these are also stored for speeding up the process. It is enough to store the correction information J at a minimum, and storage of various parameters is not indispensable. 
     The correction information J is an amount to be used for correcting a deviation with respect to a designed value of a physical quantity used for musical sound control. As shown in  FIG. 5B , the correction information J includes time correction values calT 1 , calT 2  and calT 3 , time difference correction values calT 31  and calT 32 , and stroke correction values calST 31  and calST 32 . In the present embodiment, the stroke correction value calST 32  is used, and since it is not necessary to use values other than the calST 32 , it is not indispensable to store the values other than the calST 32 . In a case where the stroke correction value calST 32  is not stored as the correction information J, the time correction values calT 2  and calT 3  may be stored, or the time difference correction value calT 32  may be stored as a minimum. 
     Although details will be described later with reference to  FIG. 8 , the outline of the derivation of the stroke correction value calST 32  by the CPU  45  will be described. In the derivation mode, the CPU  45  calculates the times rT 3  and rT 2  from the detection results by the detection sections SW 3  and SW 2  in a case where the key is depressed at the key depression speed Vplay with a constant speed. Here, it is assumed that the derivation mode at the key depression speed Vplay is performed before the shipment of the keyboard musical instrument. However, the mode may be performed by a service engineer, or the like after shipment. It should be noted that the configuration of the device for operating at a constant speed is assumed to be capable of depressing the key at a controlled speed by a servo mechanism or the like, but any other configuration may be employed. 
     The CPU  45  calculates a time difference rT 32  from rT 32 =rT 3 −rT 2  using the time rT 3  and rT 2 . Further, the CPU  45  calculates the stroke rST 32  from rST 32 =rT 32 ×Vplay using the time difference rT 32 . Using the stroke rST 32 , a stroke correction value calST 32  is calculated from the following Formula 1 as correction information J.
 
calST32 =r ST32 −s ST32  [Formula 1]
 
     In addition to this, the deviation Δd is calculated from Δd=d−rST 32  using the stroke rST 32 . Then, these values are stored in the memory  57 . 
     It should be noted that in a case where designation of the silencing trigger SW is requested, the stroke rST 31  is also calculated, a value closer to the damper distance d out of the rST 31  value and the rST 32  value is determined, and the detection section SW corresponding to the determined value (SW 1  corresponding to rST 31 , and SW 2  corresponding to rST 32 ) is designated as the silencing trigger SW (described later with reference to  FIGS. 7B and 7C ). 
     It should be noted that when the user controls the musical sound control ( FIG. 9 ), the stroke rST 32  can be used. However in a case where the stroke rST 32  is not stored, the stroke rST 32  is calculated from the following Formula 2 obtained by modifying the Formula 1 using the calST 32  value, and this stroke rST 32  may be used for control.
 
 r ST32 =s ST32+calST32  [Formula 2]
 
     Although parameters and correction information J obtained from other SWs are not shown, they can be calculated in the same way and may be stored in the memory  57  as necessary. 
     In the musical sound control, the key depression speed (velocity) in the key depression stroke by performance is calculated from the detection results by the detection sections SW 2  and SW 3 . The key depression speed V 32  can be calculated from the time difference between the detection timing by the detection section SW 2  and the detection timing by the detection section SW 3 , and the stroke difference between these detection sections SW. Conventionally, it is usual to calculate the key depression speed V 32  from V 32 =sST 32 /rT 32  on the basis of the designed value stroke sST 32  and the time difference rT 32  at the performance operation. In contrast, in the present embodiment, using the stroke rST 32  which is the actual value, the key depression speed V 32  is calculated from the following Formula 3. As a result, it is possible to reduce the influence of a manufacturing deviation and a dimensional deviation.
 
 V 32 =r ST32 /rT 32  [Formula 3]
 
     It should be noted that as a key depression velocity, the key depression speed V 31  obtained from the detection results by the detection sections SW 1  and SW 3  may be used. In the present embodiment, the key depression speed V 32  obtained from the detection results by the detection sections SW 2  and SW 3  will be used. This is because, as illustrated in  FIG. 6C , the key K may be depressed again before returning to the position of the detection section SW 1 , and the ON detection by the detection section SW 1  may not be performed in some cases. It should be noted that the use of the key depression speed V 21  obtained from the detection results by the detection sections SW 1  and SW 2  may be acceptable. However, the distance between the detection sections SW 1  and SW 2  is too small, and the detection sections SW 1  and SW 2  are far away from the position of the detection section SW 3  where a sound generation timing is determined. The key depression speed may change halfway through the key depression and it is preferable to monitor the speed until immediately before the sound generation timing and it is appropriate to use the detection result by the detection section SW 3  to calculate the key depression speed V where the sound generation timing is determined by the detection result. 
     In a case where the time correction values calT 2  and calT 3  are stored as the correction information J, the calT 2  value is calculated from calT 2 =rT 2 −sT 2  and the calT 3  value is calculated from calT 3 =rT 3 −sT 3 . At the stage of the musical sound control in this case, rT 2  value is calculated from rT 2 =calT 2 +sT 2 , and rT 3  value is calculated from rT 3 =calT 3 +sT 3 . Then, rT 32  value is calculated from rT 32 =rT 3 −rT 2 , and stroke rST 32  is calculated from rST 32 =rT 32 ×Vplay. A manner of using the calculated rST 32  value is the same as described above. 
     In addition, in a case where the time difference correction value calT 32  is stored as the correction information J, the calT 32  value is calculated from calT 32 =rT 32 −sT 32 . At the stage of the musical sound control in this case, rT 32  value is calculated from rT 32 =sT 32 +calT 32 , and the stroke rST 32  is calculated from rST 32 =rT 32 ×Vplay. A manner of using the calculated rST 32  value is the same as described above. 
       FIG. 7A  to  FIG. 7C  are diagrams showing the relations between time and key stroke in a key depression/release stroke. The meaning of the horizontal axis and the vertical axis is the same as those in  FIGS. 6A to 6C . In particular,  FIG. 7A  shows how the sound generation timing is determined in the key depression stroke during performance. In particular,  FIGS. 7B and 7C  show how the silencing timing is determined in the key release stroke during performance. 
     First, a manner of determining sound generation timing will be described with reference to  FIG. 7A . In the key depression stroke by performance, the detection section SW 3  is disposed at a position at which the detection section SW 3  turns ON slightly earlier than the timing at which the hammer  11  will strike if there is no silencing stopper  60 . The CPU  45  performs control to start a sound generation at a timing obtained by correcting the detection timing of ON by the detection section SW 3  to a delayed side on the basis of the correction information J. Specifically, the sound generation is started at the timing of T 3 +ΔT, which is later by a delay time ΔT than the time T 3  which is the ON timing of the detection section SW 3 . In the key depression stroke, the delay time ΔT is a time corresponding to a position where the key K is displaced in the key depression end direction by the delay amount ΔD than the stroke position exhibited when the detection section SW 3  is ON. In a case where the key depression speed V 32  calculated on the basis of the detection time interval of the detection sections SW 2 , SW 3  is employed as the key depression velocity during depression, the delay time ΔT is calculated from ΔT=ΔD/V 32 . The key depression speed V 32  is calculated from the above-mentioned Formula 3. In this respect, the stroke rST 32 , which is used in the Formula 3, can be calculated from the above-mentioned Formula 2 using the stroke correction value calST 32 . By using the stroke correction value calST 32  to determine the sound generation timing, the detection timing of ON by the detection section SW 3  is considered to be corrected on the basis of the correction information J. It should be noted that the rST 32  value stored as a parameter may be used. 
     Next, with reference to  FIGS. 7B and 7C , there will be described a manner of determining the silencing timing in a case where the silencing trigger SW is the detection section SW 2 . In the present embodiment, in a key release stroke by performance, the CPU  45  performs control to start silencing at a timing obtained by correcting the timing of switching from ON to OFF by the detection section SW 2  to a delayed side on the basis of the correction information J. Specifically, the silencing is started at the timing of T 2 +ΔT, which is later by the delay time ΔT than the time T 2  which is the OFF timing of the detection section SW 2 . 
     In a case where a key release speed V 23  calculated on the basis of the detection time interval of the detection sections SW 3 , SW 2  is employed as a key release velocity, the delay time ΔT is calculated from ΔT=Δd/V 23 . The time difference rT 23  is calculated from rT 23 =rT 2 −rT 3 . Then, the key release speed V 23  is calculated from the following Formula 4.
 
 V 23 =r ST32 /rT 23  [Formula 4]
 
     In this respect, the stroke rST 32 , which is used in the Formula 4, can be calculated from the above-mentioned Formula 2 using the stroke correction value calST 32 . By using the stroke correction value calST 32  to determine the silencing timing, the switching timing from ON to OFF by the detection section SW 2  is determined to be corrected on the basis of the correction information J. It should be noted that the rST 32  value stored as a parameter may be used. 
     It should be noted that as a variation, there will be described a manner of determining the silencing timing in a case where the designated information of the silencing trigger SW is used. First, as described above, the CPU  45  determines a trigger for starting the silencing on the basis of the rST 31  value or the rST 32  value, whichever is closer to the damper distance d. In the example of  FIG. 7B , since the rST 31  value is closer to the damper distance d, the detection section SW to be used as a trigger for starting silencing is determined to be the detection section SW 1 . In the example of  FIG. 7C , since the rST 32  value is closer to the damper distance d, the detection section SW to be used as a trigger for starting silencing is determined to be the detection section SW 2 . 
     Then, the timing at which the detection section SW to be used as a trigger is switched from ON to OFF is regarded as the silencing timing. Alternatively, the timing when a predetermined time as a fixed value has elapsed from the timing at which the detection section SW to be used as a trigger is switched from ON to OFF may be used as the silencing timing. 
       FIG. 8  is a flowchart showing a correction information storage process in a derivation mode. This process is executed for each key K. In this respect, a process using three detection sections SW 1 , SW 2 , and SW 3  is exemplified. Any or all of the detection sections SW 101  to SW 104  may be additionally used, and the number of detection sections SW to be used is not limited. In this process, in a case where there is a mechanism for operating the key K at a constant speed, a key is depressed at the key depression speed Vplay with a constant speed. In a case where such a mechanism is not provided, the operator (user or service person) depresses the key at the key depression speed Vplay as a target. 
     First, when a key depression is started, the CPU  45  monitors a change in state in each detection section SW (SW 1  to SW 3 ) (step S 101 ), and if there occurs the change in state, the CPU  45  causes the register of the RAM  47  to store the detection result (changing state and time of change) by the detection section SW (step S 102 ), which enables information on the detection result to be held ( FIG. 4B ). It should be noted that, for this detection result, an average value in multiple key depressions may be held. Alternatively, it is also possible to store past states such as the state in the last time or the state in the time before last in multiple key depressions, and hold the current value as a value to be held only when any or all of the difference between the current value and the previous value, the movement average or the movement dispersion are within a predetermined range. 
     Next, the CPU  45  calculates and stores the speed of the stroke section (between the detection sections SWs adjacent to each other) (step S 103 ). Since the design stroke sST 21  between the detection sections SW 1  and SW 2  is reliable, the key depression speed V 21  between the detection sections SW 1  and SW 2  is calculated from V 21 =sST 21 /rT 21  using the time difference rT 21  and the stroke sST 21 . It should be noted that the key depression speeds V 31  and V 32  may also be calculated. 
     Next, the CPU  45  determines whether the key depression stroke has ended (step S 104 ). For example, it can be determined that the key depression stroke has ended when the detection section SW 3 , which is the detection section SW operated last, turns ON. As a result of the determination, in a case where the key depression stroke has not ended (the key depression is in progress), the CPU  45  returns the process to step S 101 , whereas when the key depression stroke has ended, the CPU  45  uses the information stored in step S 102  to calculate a candidate for correction information J (step S 105 ). As the correction information J, there are calculated time correction values calT 1 , calT 2  and calT 3 , time difference correction values calT 31  and calT 32 , and stroke correction values calST 31  and calST 32 . 
     That is, the CPU  45  calculates the time difference rT 32  from rT 32 =rT 3 −rT 2  using the time rT 3  and rT 2 . Then, in a case where the key depression speed is Vplay with a constant speed, stroke rST 32  is calculated from rST 32 =rT 32 ×Vplay. On the other hand, in a case where the key depression speed is not Vplay, the stroke rST 32  is calculated from rST 32 =rT 32 ×V 21  using the key depression speed V 21  and the time difference rT 32 . Using the stroke rST 32 , the stroke correction value calST 32  is calculated from the above-mentioned Formula 1. 
     Next, in order to decide whether the key depression operation was appropriate for acquisition of the correction information J, the CPU  45  determines whether the key depression operation satisfies a “predetermined condition” (step S 106 ). In this respect, examples of the predetermined condition include a condition in which the key depression speed V 21  is within a predetermined range. However, the present invention is not limited to this. For example, the predetermined condition may include a condition in which any or all of the key depression speeds V 21 , V 31 , and V 32  fall within the predetermined range. Alternatively, in place of the decision on the basis of the key depression speed, or in addition to the determination on the basis of the key depression speed, the predetermined condition may include a condition in which a key depression acceleration falls within the predetermined range. In that case, in step S 103 , the key depression acceleration is calculated from the key depression speed of the two sections or by the integral calculation of the key depression speed, and the decision in step S 106  is made on the basis of the calculated key depression acceleration. 
     As a result of the determination in step S 106 , in a case where the key depression operation does not satisfy the predetermined condition, the CPU  45  discards the correction information J obtained as a candidate (step S 109 ) and returns the process to step S 101 . On the other hand, in a case where the key depression operation satisfies the predetermined condition, the CPU  45  determines that the correction information J obtained as a candidate is officially employed, and causes the memory  57  to store it (step S 107 ). As a result, the correction information J is derived and stored ( FIGS. 5A and 5B ). Further, various parameters (strokes rST 32  and rST 31 , deviation Δd, designation of the silencing trigger SW) are calculated on the basis of the correction information J that has been employed and causes the memory  57  to store them (step S 108 ) ( FIG. 5A ). Thereafter, the process in  FIG. 8  is terminated. 
     It should be noted that the process in  FIG. 8  is not limited to the key depression stroke. It may be executed during the key release stroke. Further, in a case where the process in  FIG. 8  can be executed by key depression at a controlled speed by a mechanism for operating the key K at a constant speed, the process in steps S 106  and S 109  may be omitted. 
       FIG. 9  is a flowchart a showing musical sound control process. This process is started when preparation for performance in the silencing mode is completed and is executed at predetermined time intervals (for example, every 100 μsec). It should be noted that the musical sound control can be performed on the basis of the detection results by the plurality of detection sections SW. In addition, the detection results by these detection sections SW are not limited to be used for musical sound control, and can also be used to record performance as performance data for musical sound control. There is no limit to the number of detection sections SW used for musical sound control and performance data recording. Here, control using three detection sections SW 1 , SW 2 , and SW 3  will be exemplified. 
     First, the CPU  45  scans the states of the detection sections SWs for each key K, and stores the scanning result (ON or OFF) and the change in state (the presence or absence of switching between ON and OFF, time of change) in the register for each key K (Step S 201 ). As a result, the information on the detection result ( FIG. 4B ) is stored for each key K and is updated as needed. It should be noted that a process of scanning each state by the detection section SW and a process of storing the state in the register may be automatically performed sequentially by hardware. 
     Next, the CPU  45  determines whether the detection state of the detection section SW 3  has switched from OFF to ON (step S 202 ). As a result of the determination, in a case where the detection state of the detection section SW 3  has switched from OFF to ON, the CPU  45  executes a sound generation process for each key K (step S 203 ) and advances the process to step S 204 . On the other hand, in a case where the detection state of the detection section SW 3  has not switched from OFF to ON, the process proceeds to step S 204  without performing the sound generation process. 
     In this sound generation process, the CPU  45  generates musical sound information, and at the same time, decides the sound generation timing and the key depression velocity. First, for the key depression velocity, the CPU  45  calculates the time difference rT 32  from rT 32 =rT 3 −rT 2  (see  FIGS. 6B and 6C ) and acquires the stroke rST 32  by reading it from the database ( FIG. 5A ) or by calculating it from the correction information J. Then, the CPU  45  calculates and determines the key depression speed V 32  as the key depression velocity according to the above-mentioned Formula 3. 
     In addition, for the sound generation timing, as described above, the CPU  45  calculates the delay time ΔT from ΔT=ΔD/V 32 , and determines the timing of T 3 +ΔT as the sound generation timing (see  FIG. 7A ). Then, the CPU  45  starts sound generation on the basis of the generated musical sound information at the determined key depression velocity and sound generation timing. In other words, the CPU  45  controls the sound source circuit  53 , the effect circuit  54 , and the like to generate a musical sound with the pitch of the key K to be processed this time at the currently determined velocity and sound generation timing for the key K. 
     Next, the CPU  45  determines whether the detection state of the detection section SW 2  has switched from OFF to ON (step S 204 ). As a result of the determination, the CPU  45  ends the process in  FIG. 9  without performing a silencing process in a case where the detection state of the detection section SW 2  has not switched from OFF to ON. On the other hand, in a case where the detection state of the detection section SW 2  has switched from ON to OFF, the CPU  45  determines whether the pitch corresponding to the key K to be processed this time is being sounded (step S 205 ), and if not, ends the process in  FIG. 9 , whereas if so, executes the silencing process of the musical sound being sounded (step S 206 ). 
     In this silencing process, the CPU  45  decides the key release velocity and the silencing timing. First, for the key release velocity, the CPU  45  calculates the time difference rT 23  from rT 23 =rT 2 −rT 3  (see  FIGS. 7B and 7C ) and acquires the stroke rST 32  by reading it from the database ( FIG. 5A ) or by calculating it from the correction information J. Then, the CPU  45  calculates and determines the key depression speed V 23  as the key release velocity according to the above-mentioned Formula 4. 
     In addition, for the silencing timing, as described above, the CPU  45  calculates the delay time ΔT from ΔT=Δd/V 23 , and determines the timing of T 2 +ΔT as the silencing timing (see  FIGS. 7B and 7C ). Then, the CPU  45  starts silencing of the musical sound which is being sounded at the determined key release velocity and silencing timing, followed by terminating the process in  FIG. 9 . 
     According to the present embodiment, on the basis of the detection timing (rT 2 ) by the detection section SW 2 , the detected key depression speed (V 21 ), and the detection timing (rT 3 ) by the detection section SW 3  in a case where the key is depressed in the derivation mode, after the rST 32  value is calculated, the stroke correction value calST 32  is derived as the correction information J and stored in the memory  57 . In the performance mode, the musical sound is controlled on the basis of the detection timing by the detection sections SW 1 , SW 2 , and SW 3  and the stroke correction value calST 32 . As a result, variations in the detection mechanism can be corrected so that appropriate musical sound control can be performed. 
     In addition in the derivation mode, the correction information J is calculated on the basis of the rT 2  value, the rT 3  value, and the V 21  value in the operation stroke in which the operation speed (or the operation acceleration) of the key is within a predetermined range, so that correction Information with high reliability can be derived. 
     In addition, in the sound generation control, since the sound generation is started at the timing (T 3 +ΔT) obtained by correcting the detection timing of the detection section SW 3  used for the sound generation trigger to a delay side on the basis of the correction information J, appropriate sound generation control can be performed. In addition, in the silencing control, since the silencing is started at a timing (T 2 +ΔT) obtained by correcting the detection timing of the detection section SW 2  used for the silencing trigger to a delay side on the basis of the correction information J, appropriate silencing control can be performed. 
     In addition, since the shutter member  121  is integrally formed, the reliability of the distance (sST 21 ) between the two detection positions of the first boundary  123  and the second boundary  124  is high, and the time difference rT 21  and the time difference sT 21  substantially coincide with each other, a highly reliable key depression speed V 21  can be obtained from the sST 21  value and the rT 21  value. 
     It should be noted that the derivation mode can also be performed in the performance mode. To give an example, for example, in a case where the derivation mode is performed in the performance mode, the correction information J is derived before the musical sound is controlled, and the correction information J is reflected in the musical sound control in the performance mode. In this case, since the musical sound control is performed in real time while the correction information J is derived as needed, it is not necessary to store the correction information J. It should be noted that the correction information J derived in the performance mode may be stored so that the correction information J can be used for musical sound control in the subsequent performance modes. 
     It should be noted that when deriving the correction information J, the detection result of the key K except for the hammer  11  was used for the detection timing and speed to be used. However, there is not restriction in the combination of the key K and the hammer  11 , and it is not indispensable that one member is the key K. That is, the combination may be employed as long as a configuration includes a first detection unit for detecting at least a position and a speed of the key K or a first member out of a displacement member, and a second detection unit for detecting at least a position of a second member other than the first member among displacement members. 
     It should be noted that the detection section SW used for the correction information storage process in the derivation mode and the detection section SW used for musical sound control need not completely match with each other. In addition, while the number of detection sections SW used for musical sound control is three, it may be four or more. Furthermore, in musical sound control, any combination out of the plurality of detection sections SW may be used for calculating the velocity of key depression and/or key release. In a case where the detection results by a large number of detection sections SW can be used, it is preferable to determine the velocity of key depression/release on the basis of the detection timing at two detection positions not adjacent to each other out of the plurality of detection positions sequentially detected by the plurality of detection sections SW. At this time, the velocity of key depression/release may be determined on the basis of the detection timing at two detection positions not adjacent to each other out of the detection positions detected by the detection sections SW detecting the operation of the key K. Alternatively, the velocity of key depression/release may be determined on the basis of the detection timing at two detection positions not adjacent to each other out of the detection positions detected by the detection sections SW detecting the operation of the displacement member. Since the time interval between adjacent detection positions is short, by employing a combination of the detection timings of the detection sections SW having long time intervals, the accuracy with which the key velocity is determined is enhanced. 
     It should be noted that not all of the detection sections SW shown in  FIG. 1  and  FIG. 2 , etc. are necessary. For example, in a case where the correction information storage process can be performed at the controlled key depression speed, one detection section SW capable of detecting the position of both the key K and the hammer  11  may be provided at a minimum. 
     It should be noted that in the correction information storage process, as an operation mode of the managed key K, the key depression at the key depression speed Vplay with a constant speed is exemplified. The present invention is not limited to this. The operation speed and the speed change of the key K may be predetermined operation modes. That is, in the pre-shipment stage, or the like, the amount of designed values (time T 1 , T 2 , and T 3 , time difference T 31 , T 32 , and T 21 , etc.) is obtained in advance in a predetermined operation mode. The predetermined operation mode may not have a constant speed as long as the same operation mode as the then operation can be reproduced in the correction information storage process in the derivation mode. 
     In a case where a large number of detection sections SW are provided, the detection section SW used for musical sound control may be selected on the basis of the stroke rST, which will be described below with reference to  FIGS. 10A and 10B . 
       FIG. 10A  and  FIG. 10B  are diagrams showing the relations between time and key stroke in the key depression/release stroke. The meaning of the horizontal axis and the vertical axis is the same as those in  FIGS. 6A to 6C . The plurality of detection sections SWa to SWf are disposed at positions where objects are sequentially detected at the detection positions pSWa to pSWf. In this respect, the order of the detection positions pSWa to pSWf is a detection order specified in a case where it is assumed that the key K and the displacement member are interlocked. The CPU  45  converts the detection positions pSWa to pSWf into the stroke positions of the key K, and performs musical sound control on the basis of the converted stroke positions. The position to which the key K returns from the detection position pSWf by a distance e in the non key depression direction corresponds to an escapement position at which the jack  6  escapes from the hammer roller  14 . The distance e is acquired before product shipment and stored in the memory  57 , the ROM  46 , or the like. The stroke corresponding to the detection timing difference between the detection position pSWf and the detection position pSWd is a stroke rSTfd. Similarly, the stroke corresponding to the detection timing difference between the detection position pSWf and the detection position pSWc is a stroke rSTfc, and the stroke corresponding to the detection timing difference between the detection position pSWf and the detection position pSWb is a stroke rSTfb. 
     Due to aging, deformation such as warping of the key K and the displacement member, which and objects, may occur. Hence, the detection timing by the detection section SW for detecting the position of these objects changes. For example, suppose that the state of the detection positions pSWa to pSWf, which were in the state shown in  FIG. 10A  at the time of delivering the product, have become the state as shown in  FIG. 10B  due to long-term use of the product. Although, in  FIG. 10A , the escapement position was located between the stroke rSTfd and the stroke rSTfc, it is located between the stroke rSTfc and the stroke rSTfb in  FIG. 10B . 
     Normally, friction increases mechanically at the escapement position, so that a slight change in the key depressing force causes a large change in the key depression speed in the vicinity of the escapement position. Thus, since the reliability of the detection result detected near the escapement position is not so high, it is preferable not to use the detection result for musical sound control. 
     Therefore, the detection results at the two detection positions sandwiching a position corresponding to the escapement position may be excluded from the detection result used for musical sound control. In particular, it is preferable not to use it to calculate the velocity. For example, in the example of  FIG. 10A , the detection results at the detection position pSWc and the detection position pSWd by the detection sections SWc and SWd are not used. In the example of  FIG. 10B , detection results at the detection position pSWb and detection position pSWc by the detection sections SWb and SWc are not used. Thus, it is possible to prevent the detection result with a large deviation from being used for musical sound control. 
     In the embodiments described above, although application of the present invention to a keyboard musical instrument having the grand piano type action mechanism ACT is taken as an example, the configuration of the keyboard musical instrument according to the present invention is not limited to such a configuration having the action mechanism ACT. In other words, the key depression operation may merely have a displacement member that is moved by the key depression operation and may not be required to have the action mechanism. 
     In addition, the present invention is also applicable to a keyboard musical instrument having an upright type action mechanism ACT shown in  FIG. 11 . 
       FIG. 11  is a side view showing an action mechanism ACT 2  of an upright piano. In normal key depression operation, when the key K is depressed down, a wippen  112  is pushed up and turned, whereby a jack  120  is raised. In addition, when the jack  120  is raised, a bat  126  is pushed up by the jack  120 , whereby a hammer  130  is turned counterclockwise as shown in  FIG. 11 . The jack  120  is raised and turned. In the middle of being raised and turned, the jack  120  comes into contact with a regulating button  140  and is turned clockwise, thereby moving temporarily away from the lower portion of the bat  126 . In addition, when the wippen  112  is raised and turned, a damper spoon  156  turns a damper lever  152  clockwise, whereby a damper  155  is spaced away from the string  19 . 
     After the damper  155  is spaced away from the string  19 , the hammer  130  strikes the string  19 . The hammer  130  is then bounced back, and a catcher  133  is elastically received by a back check  144 . The jack  120  is released from the regulating button  140  by the turning and lowering of the wippen  112  accompanied by the key release operation, so that the jack  120  is turned and then returned to its original position, and the upper end of the jack  120  again enters the lower portion of the bat  126 . Hence the next string striking action can be carried out using the same key K. A key back rail cloth  165  is disposed so as to be fastened to a shelf board  106 , and a conductive unit  166  is provided at the rear lower portion of the key K. Like the silencing stopper  60 , a silencing stopper  82  is configured so that its position can be switched for use in the silencing mode. 
     In the above-mentioned configuration, for example, the silencing stopper  82  may be provided with the detection section SW 3 . The detection sections SW may be provided between the bat  126  and the jack  120 , between the regulating button  140  and the jack  120 , between the lower surface (conductive unit  166  thereof) of the key K and the key back rail cloth  165 , and the like. 
     Although the present invention has been described above on the basis of the preferred embodiments thereof, the present invention is not limited to these specific embodiments. Various embodiments within the scope not departing from the gist of the present invention are also included in the present invention. 
     This application is a bypass continuation application of PCT International Application PCT/JP2016/083005, filed on Nov. 1, 2016, which is based on and claims priority from Japanese Patent Application No. 2015-216746, filed on Nov. 4, 2015, the entire contents of which are incorporated herein by reference.