Patent Publication Number: US-2022238084-A1

Title: Actuator for piano, and piano

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation application of International Application No. PCT/JP2019/044498, filed Nov. 13, 2019. The content of the application is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present disclosure relates to an actuator for a piano, and a piano. 
     DESCRIPTION OF RELATED ART 
     Published Japanese Translation No. H04-500735 of the PCT International Publication (hereinafter Patent Document 1) discloses an actuator for a piano that produces a sound by vibrating the soundboard of the piano. In the piano of Patent Document 1, a part of a transmission unit (drive hammer) coupled to a vibrating body of an actuator for a piano is embedded or fixed inside the bridge of the piano to be attached to the bridge of the piano. 
     SUMMARY OF THE INVENTION 
     However, as in Patent Document 1, when a section of the actuator for a piano is to be embedded or fixed in the bridge of the piano, it is necessary to perform processing on a component of the piano such as the bridge or use an adhesive. For that reason, there is a problem that it is troublesome to attach/detach the actuator for a piano to/from the piano. 
     It is also not preferable to perform processing or use adhesive on a component of a piano to attach the actuator for a piano to the piano since doing so may damage components of the piano. 
     The present disclosure has been made in view of the above circumstances, and an object of the present disclosure is to provide an actuator for a piano that can be easily attached to and detached from the piano without processing and without using an adhesive, and a piano including the actuator for a piano. 
     According to a first aspect of the present disclosure, there is provided an actuator for a piano including a bridge and strings. The actuator includes: a vibrating body; and an attachment portion configured to attach the vibrating body to the piano, the attachment portion being configured to be sandwiched between the bridge and at least one string, among the strings of the piano. 
     According to a second aspect of the present disclosure, there is provided a piano including: a bridge; strings; and an actuator including: a vibrating body; and an attachment portion that attaches the vibrating body to the piano, the attachment portion being sandwiched between the bridge and at least one string, among the strings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional view showing essential portions of a piano including an actuator for a piano according to an embodiment of the present disclosure. 
         FIG. 2  is an enlarged cross-sectional view showing a state in which an attachment portion of the actuator for a piano is sandwiched between a bridge and a string in the piano of  FIG. 1 . 
         FIG. 3  is a perspective view showing the actuator for a piano shown in  FIGS. 1 and 2 . 
         FIG. 4  is a view from above of the process for sandwiching the attachment portion of the actuator for a piano of  FIG. 3  between the bridge and the string. 
         FIG. 5  is a view from above of the process for sandwiching the attachment portion of the actuator for a piano of  FIG. 3  between the bridge and the string. 
         FIG. 6  is a view from above of the process for sandwiching the attachment portion of the actuator for a piano of  FIG. 3  between the bridge and the string. 
         FIG. 7  is an enlarged cross-sectional view showing a state in which an attachment portion of an actuator for a piano according to another embodiment of the present disclosure is sandwiched between the bridge and the string of the piano. 
     
    
    
     EMBODIMENTS FOR CARRYING OUT THE INVENTION 
     Hereinbelow, embodiments of the present disclosure will be described with reference to  FIGS. 1 to 6 . 
     As shown in  FIG. 1 , a piano  1  of the present embodiment includes a soundboard  2 , a string  3 , a bridge  4 , and an actuator for a piano  5 . The piano  1  in the present embodiment is a grand piano in which the thickness direction of the soundboard  2  is generally oriented in the vertical direction (Z-axis direction). In  FIGS. 1 to 6 , the X-axis direction mainly corresponds to the longitudinal direction of the string  3 . Further, the Y-axis direction corresponds to the direction in which a plurality of the strings  3  are arranged. 
     The string  3  is stretched across an upper surface  2   a  of the soundboard  2  by being hooked on a pitch pin  61  and a tuning pin (not shown) of a frame  6  of the piano  1 . A plurality of the strings  3  are arranged at an interval from each other (see  FIG. 4 ). 
     The bridge  4  is sandwiched between the upper surface  2   a  of the soundboard  2  and the string  3 . As shown in  FIGS. 1 and 2 , the bridge  4  has an inclined surface  42  extending from a top surface  41  of the bridge  4 , which is in contact with the string  3 , in a direction going away from the string  3  (Z-axis negative direction) when heading in the longitudinal direction of the string  3 . The inclined surface  42  is located on both sides of the top surface  41  in the longitudinal direction of the string  3 . Thereby, on both sides of the top surface  41  of the bridge  4 , there is a gap  7  between the bridge  4  and the string  3  in which the interval between the bridge  4  and the string  3  increases as the distance from the top surface  41  increases in the longitudinal direction of the string  3 . 
     A bridge nail  43  for hooking the string  3  is provided at a connecting portion between the top surface  41  of the bridge  4  and each inclined surface  42 . The bridge  4  is arranged at a position closer to the pitch pin  61  than the tuning pin in the longitudinal direction of the string  3 . As shown in  FIG. 4 , the bridge  4  extends in the direction in which the plurality of strings  3  are arranged (for example, in the Y-axis direction), and supports the plurality of strings  3 . 
     In the piano  1  of the present embodiment, when the string  3  is struck by a hammer (not shown), the string  3  vibrates mainly in the thickness direction of the soundboard  2 . The vibration of the string  3  is transmitted to the soundboard  2  via the bridge  4 , whereby the soundboard  2  vibrates. 
     The actuator for a piano  5  causes the soundboard  2  to vibrate in the thickness direction of the bridge  4  by vibrating the bridge  4  to produce a sound. As shown in  FIGS. 1 and 3 , the actuator for a piano  5  includes a main body (body)  51 , a vibrating body  52  that vibrates in a predetermined vibration direction (for example, the Z-axis direction) with respect to the main body  51 , and an attachment portion  53  provided in the vibrating body  52  and sandwiched between the bridge  4  and the string  3 . The weight of the main body  51  is sufficiently heavier than the weight of the vibrating body  52  and the attachment portion  53 . 
     The actuator for a piano  5  may be, for example, a voice coil type actuator. 
     The attachment portion  53  of the present embodiment has a first extension portion  531  and a second extension portion  532 . 
     The first extension portion  531  extends from the vibrating body  52  in the vibration direction (Z-axis negative direction). Although the first extension portion  531  of the illustrated example is formed in a square columnar shape, it may be formed in an arbitrary columnar shape such as a cylindrical column, or may be formed in a plate shape, for example. Further, the first extension portion  531  may be positioned on the axis of the vibrating body  52  as shown in the illustrated example, but may also be located, for example, in a manner shifted from the axial line of the vibrating body  52 . 
     The second extension portion  532  extends from the tip end portion of the first extension portion  531  in the extension direction in a direction intersecting the vibration direction of the vibrating body  52 . The second extension portion  532  may for example extend in a direction inclined with respect to the vibration direction of the vibrating body  52 . In the present embodiment, the second extension portion  532  extends in a direction orthogonal to the vibration direction of the vibrating body  52  (Y-axis direction in  FIGS. 1 and 3 ). 
     The second extension portion  532  may for example extend to only one side of the tip end portion of the first extension portion  531  in a direction orthogonal to the vibration direction. That is, the attachment portion  53  may be formed in an L shape, for example. In the present embodiment, a pair of second extension portions  532  extend in opposite directions from the tip end portion of the first extension portion  531 . That is, the attachment portion  53  of this embodiment is formed in a T shape. In the present embodiment, the total length L 1  of the pair of second extension portions  532  is larger than the distance D 1  between the two adjacent strings  3  (refer to  FIG. 6 ). 
     Although the second extension portion  532  of the illustrated example is formed in a cylindrical columnar shape, it may be formed in an arbitrary columnar shape such as a square column, or may be formed in a plate shape, for example. 
     As shown in  FIGS. 1 and 2 , in the present embodiment, the second extension portion  532  of the attachment portion  53  is sandwiched between the bridge  4  and the string  3 . Specifically, the second extension portion  532  is sandwiched in the above-mentioned gap  7  between the bridge  4  and the string  3 . Therefore, the dimension T 1  (thickness dimension T 1 ) of the second extension portion  532  in the vibration direction of the vibrating body  52  is smaller than the maximum dimension D 2  of the gap  7 . 
     The second extension portion  532  has a dimension that is capable of being passed between two adjacent strings  3 . Specifically, as shown in  FIG. 4 , the dimension W 1  (width dimension W 1 ) of the second extension portion  532  in a direction (Y-axis direction in  FIG. 4 ) orthogonal to the extension direction (Z-axis direction) of the first extension portion  531  and the extension direction (X-axis direction in  FIG. 4 ) of the second extension portion  532  is smaller than the distance D 1  between the two adjacent strings  3 . 
     In the present embodiment, the width dimension of the first extension portion  531  is also smaller than the distance D 1  between the two adjacent strings  3 , similarly to the width dimension W 1  of the second extension portion  532 . It is sufficient that at least at only the section of the first extension portion  531  that can pass between the two strings  3  (for example, the tip end portion of the first extension portion  531 ), the width dimension of the first extension portion  531  is smaller than the distance D 1  between the two strings  3 . In the attachment portion  53  illustrated in  FIGS. 3 and 4 , the width dimension of the first extension portion  531  is smaller than the distance D 1  between the two strings  3  over the entire first extension portion  531 . That is, the width dimension of the attachment portion  53  is smaller than the distance D 1  between the two strings  3 . 
     As shown in  FIGS. 1 and 2 , in the actuator for a piano  5 , the first extension portion  531  is arranged so as to extend above the string  3  (in the positive direction of the Z axis) from the second extension portion  532  in a state of the second extension portion  532  being sandwiched in the gap  7  between the bridge  4  and the string  3 . It is preferable that the extension direction (vibration direction) of the first extension portion  531  coincides with the arrangement direction (Z-axis direction) of the soundboard  2 , the bridge  4 , and the string  3 . 
     As shown in  FIG. 1 , the actuator for a piano  5  of the present embodiment further includes a pulling portion (pulling member)  54 . 
     The pulling portion  54  pulls in the opposite direction of the first direction (positive direction of the X axis in  FIG. 1 ) in the state of the second extension portion  532  being arranged in the gap  7  where the interval between the bridge  4  and the string  3  increases as the second extension portion  532  heads in the first direction (the negative direction of the X axis in  FIG. 1 ) in the longitudinal direction of the chord  3 . That is, the pulling portion  54  pulls the second extension portion  532  in a direction in which the interval of the gap  7  becomes smaller. Specifically, the pulling portion  54  pulls the section of the first extension portion  531  separated from the second extension portion  532  (particularly, a section located above the string  3 ) in the aforementioned direction. 
     The pulling portion  54  of the present embodiment is an elastic body that elastically expands and contracts in a linear direction, and is passed between the first extension portion  531  and a pin that is provided on the piano  1  to hook the string  3 . The pulling portion  54 , which is an elastic body, may be, for example, a coil spring, but in the present embodiment is a rubber string that is easy to suppress interference with the string  3 . 
     In the present embodiment, the pulling portion  54  is passed between the first extension portion  531  and the pitch pin  61 , in the state of the second extension portion  532  being arranged in the first gap  7 A positioned on the opposite side of the pitch pin  61  with respect to the top surface  41  of the bridge  4  in the longitudinal direction of the string  3 . As a result, the elastic force of the pulling portion  54  can pull the second extension portion  532  in a direction in which the interval of the first gap  7 A becomes smaller. By hooking the pulling portion  54  on the pitch pin  61  located near the bridge  4 , the length of the pulling portion  54  can be kept short. 
     Next, an example of a method of sandwiching the attachment portion  53  of the actuator for a piano  5  of the present embodiment between the bridge  4  and the string  3  will be described mainly with reference to  FIGS. 4 to 6 . 
     First, as shown in  FIG. 4 , the actuator for a piano  5  is arranged so that the first extension portion  531  extends downward (Z-axis negative direction) from the vibrating body  52 , and the extension direction of the second extension portion  532  is aligned with the longitudinal direction of the strings  3 . In this state, the width direction of the second extension portion  532 , whose width dimension W 1  is smaller than the distance D 1  between the two strings  3 , is aligned with the arrangement direction (X-axis direction) of the plurality of strings  3 . Thereby, the second extension portion  532  can be passed between the two adjacent strings  3  and moved downward (Z-axis negative direction) from the strings  3 . 
     Next, as shown in  FIG. 5 , the attachment portion  53  is rotated 90 degrees, with the extension direction of the first extension portion  531  serving as the axis. As a result, the pair of second extension portions  532  are located below the strings  3 , respectively. 
     Finally, as shown in  FIG. 6 , the pair of second extension portions  532  are inserted in the gap  7  (first gap  7 A) between each string  3  and the inclined surface  42  of the bridge  4 . As a result, the second extension portion  532  can be sandwiched between the string  3  and the bridge  4 . 
     As shown in  FIGS. 1 and 2 , when the attachment portion  53  of the actuator for a piano  5  is sandwiched between the bridge  4  and the string  3 , the attachment portion  53  (particularly the second extension portion  532 ) is pressed against the bridge  4 . Therefore, the bridge  4  can be vibrated by the actuator for a piano  5 . The vibration of the bridge  4  is transmitted to the soundboard  2 , so that the soundboard  2  vibrates. In the piano  1  of the present embodiment in which the actuator for a piano  5  vibrates the bridge  4 , compared with the case where the actuator for a piano  5  directly vibrates the soundboard  2 , since the sound production structure by the actuator for a piano  5  is similar to the sound production structure of a normal piano that vibrates a bridge by vibration of the strings, a more piano-like sound can be produced. In particular, since the vibration direction of the vibrating body  52  (extension direction of the first extension portion  531 ) is the same as the main vibration direction of the strings  3 , the sound production structure by the actuator for a piano  5  can further approach the sound production structure arising from vibration of the strings. 
     As described above, according to the actuator for a piano  5  of the present embodiment, the actuator for a piano  5  can be easily attached to the piano  1  by simply sandwiching the attachment portion  53  between the bridge  4  and the strings  3 . Therefore, the actuator for a piano  5  can be attached to the piano  1  without performing processing on the piano  1  or adhering the actuator for a piano  5  to the piano  1 . Further, the actuator for a piano  5  can be easily removed from the piano  1  by simply removing the attachment portion  53  from between the bridge  4  and the strings  3  of the piano  1 . 
     That is, the actuator for a piano  5  can be easily attached to and detached from the piano  1  without performing any processing and without using an adhesive. 
     Further, the attachment portion  53  of the actuator for a piano  5  of the present embodiment has a first extension portion  531  extending in the vibration direction from the vibrating body  52  and a second extension portion  532  extending in a direction intersecting the vibration direction from the tip end portion of the first extension portion  531  and sandwiched between the bridge  4  and the string  3 . Therefore, in the state of the second extension portion  532  being sandwiched between the bridge  4  and the string  3 , the first extension portion  531  can be extended in the direction in which the bridge  4  and the string  3  are aligned (the arrangement direction of the bridge  4  and the string  3 ). Thereby, the main body  51  and the vibrating body  52  can be arranged at positions away from the string  3  in the arrangement direction of the bridge  4  and the string  3 . Accordingly, it is possible to prevent the main body  51  and the vibrating body  52  of the actuator for a piano  5  from interfering with the string  3  and the bridge  4 . 
     In the actuator for a piano  5  of the present embodiment, the pair of second extension portions  532  extend in opposite directions from the tip portion of the first extension portion  531 . As a result, the pair of second extension portions  532  can be sandwiched between the bridge  4  and two strings  3 . Therefore, compared with the case where one second extension portion  532  is sandwiched between the bridge  4  and one string  3 , the force pressing the second extension portion  532  against the bridge  4  is increased by the tension of the strings  3 . Accordingly, the second extension portion  532  can be held more firmly against the bridge  4 . 
     Further, since the first extension portion  531  is located between the pair of second extension portions  532  sandwiched between the bridge  4  and the strings  3 , the actuator for a piano  5  can be stably attached to the piano  1 . 
     In the actuator for a piano  5  of the present embodiment, the thickness dimension T 1  of the second extension portion  532  sandwiched in the gap  7  (for example, the first gap  7 A) between the bridge  4  and the string  3  is smaller than the maximum dimension D 2  of the gap  7 , where the interval between the bridge  4  and the string  3  gradually increases heading in the first direction (for example, the negative direction of the X axis) in the longitudinal direction of the strings  3 . Thereby, the second extension portion  532  can be easily and surely inserted into the gap  7  between the bridge  4  and the string  3 . As a result, the second extension portion  532  can be easily and surely sandwiched between the bridge  4  and the string  3 . 
     The actuator for a piano  5  of the present embodiment includes the pulling portion  54  that pulls the second extension portion  532  in the opposite direction of the first direction (for example, positive direction of the X axis) in the state of the second extension portion  532  being arranged in the gap  7  between the bridge  4  and the string  3 . Therefore, the second extension portion  532  is pulled by the pulling portion  54  in the direction in which the interval in the gap  7  between the bridge  4  and the string  3  becomes smaller. Thereby, the second extension portion  532  can be held in a state of being sandwiched between the bridge  4  and the string  3 , that is, the second extension portion  532  can be prevented from coining out of the gap  7  between the bridge  4  and the string  3 . 
     In the actuator for a piano  5  of the present embodiment, the pulling portion  54  pulls the section of the first extension portion  531  separated from the second extension portion  532  in the opposite direction (X-axis positive direction). Therefore, it is possible to prevent the actuator for a piano  5  from rotating (swinging) with respect to the piano  1  about the extension direction of the second extension portion  532 . In particular, when viewed from the direction shown in  FIG. 1 , it is possible to suppress counterclockwise rotation of the actuator for a piano  5 . As a result, the actuator for a piano  5  can be stably attached to the piano  1 . That is, the actuator for a piano  5  can be held at a predetermined position without fixing the main body  51  of the actuator for a piano  5  to the housing of the piano  1  (for example, the frame  6 , a side plate, a support, or the like). By eliminating the need to fix the main body  51  of the actuator for a piano  5  to the housing of the piano  1 , the actuator for a piano  5  can be attached and detached more easily. 
     Further, the actuator for a piano  5  of the present embodiment has a dimension (width dimension W 1 ) that allows the second extension portion  532  to pass between two adjacent strings  3 . As a result, as shown in  FIGS. 4 to 6 , after passing the second extension portion  532  between two strings  3 , by rotating the attachment portion  53  90 degrees with the extension direction of the first extension portion  531  serving as the axis, the second extension portion  532  can be easily inserted into the gap  7  between the bridge  4  and the string  3 . 
     In the actuator for a piano  5  of the present embodiment, the second extension portion  532  is formed in a cylindrical columnar shape. In a state where the second extension portion  532  is sandwiched between the bridge  4  and the string  3 , the outer peripheral surface of the second extension portion  532  comes into contact with the bridge  4  and the string  3 . Therefore, compared with the case where the second extension portion  532  is formed in a square columnar shape, it is possible to prevent the bridge  4  and the string  3  from being damaged by the second extension portion  532 . 
     Although the present disclosure has been described in detail above, the present disclosure is not limited to the above embodiment, and various modifications can be made in a range that does not depart from the spirit of the present disclosure. 
     In the present disclosure, the actuator for a piano  5  may include a cushioning material  55  that covers the surfaces of the attachment portion  53  facing the bridge  4  and the string  3 , as shown in  FIG. 7 , for example. In  FIG. 7 , the cushioning material  55  covers the outer peripheral surface of the second extension portion  532  facing the bridge  4  and the string  3 . The cushioning material  55  may be made of a material that is softer and more easily deformable than the bridge  4  and the string  3 , such as felt or rubber. 
     By interposing the cushioning material  55  between the attachment portion  53  and the bridge  4  or the string  3 , it is possible to prevent the bridge  4  or the string  3  from being damaged by the attachment portion  53  coming into contact with the bridge  4  or the string  3 . That is, the bridge  4  and the string  3  can be protected. 
     In the present disclosure, the pulling portion  54  is not limited to being passed between the first extension portion  531  and the pitch pin  61 , and may, for example, be passed between the first extension portion  531  and the tuning pin or the bridge nail  43 . For example, in the above embodiment, when the second extension portion  532  of the actuator for a piano  5  is arranged in the second gap  7 B (see  FIG. 1 ) located on the pitch pin  61  side with respect to the top surface  41  of the bridge  4  in the longitudinal direction of the string  3 , the pulling portion  54  may be passed between the first extension portion  531  and the tuning pin. 
     In the present disclosure, the main body  51  of the actuator for a piano  5  may be fixed to, for example, the housing of the piano  1 . 
     In the present disclosure, the same (single) piano  1  may be provided with a plurality of the actuators for a piano  5 . In this case, the actuators for a piano  5  may be provided for, for example, a plurality of strings  3  having mutually different sound ranges. The actuators for a piano  5  may be provided for each string  3  corresponding to, for example, a low range, a mid-range, and a high range. Further, the actuators for a piano  5  may be provided on, for example, a long bridge and a short bridge of the piano  1 , respectively. Alternatively, the plurality of actuators for a piano  5  may be provided at mutually different positions in the longitudinal direction of the bridge  4  with respect to the same (single) bridge  4 . 
     When the actuators for a piano  5  are provided in mutually different sound ranges of the piano  1 , each actuator for a piano  5  may vibrate the bridge  4  on the basis of a drive signal with a characteristic corresponding to the respective sound range. 
     For example, the piano of the present disclosure may include an actuator for a piano that directly vibrates the soundboard  2  in addition to the actuator for a piano  5  that vibrates the bridge  4 . 
     The actuator for a piano of the present disclosure is not limited to a grand piano, and may also be applied to, for example, an upright piano in which the thickness direction of the soundboard  2  faces substantially the horizontal direction. 
     According to the present disclosure, the actuator for a piano can be easily attached to and detached from a piano without any processing and without using an adhesive.