Abstract:
A keyboard instrument such as an upright piano is basically constructed by a keyboard, an action, a case assembly, a fall assembly, a back hollow assembly and a top door assembly. Herein, the fall assembly provides a fall cover for covering the keyboard, and the top door assembly having an opening top door is linked to the fall assembly by way of the back hollow assembly. The top door pivotally moves in response to movement of the fall cover of the fall assembly being closed or opened, wherein when the fall cover is opened, the top door opens to produce a small gap in proximity to a lower end of the top door. The small gap allows piano sound to be partially released from a casing to increase loudness of the piano sound and to enhance clarity in tone color of the piano sound. The keyboard instrument further provides a damping mechanism for imparting resistance load to the fall cover being closed or opened. That is, the damping mechanism uses a rotation damper containing viscous fluid that moves in response to pivotal movement of the fall cover to produce torque by which an increasing load is to be automatically imparted to the fall cover being closed.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to keyboard instruments such as upright pianos having loudness increase structures. 
     2. Description of the Related Art 
     In general, upright pianos are constructed to realize opening functions of top covers which are hinged to top places of cases, so users or players are capable of opening the top covers to increase tone volumes of piano sounds. However, because general users tend to place some articles or objects on the top covers, the upright pianos cannot always demonstrate the opening functions for increasing tone volumes of piano sounds. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to provide a keyboard instrument such as an upright piano that is capable of realizing an opening function for increasing tone volume of piano sound without being interrupted by an article or object being placed on a top cover. 
     A keyboard instrument such as an upright piano is basically constructed by a keyboard, an action, a case assembly, a fall assembly, a back hollow assembly and a top door assembly. Herein, the fall assembly provides a fall cover for covering the keyboard, and the top door assembly having an opening top door is linked to the fall assembly by way of the back hollow assembly. The top door pivotally moves in response to movement of the fall cover of the fall assembly being closed or opened, wherein when the fall cover is opened, the top door opens to produce a small gap ( 52 ) in proximity to a lower end of the top door. The small gap allows piano sound to be partially released from a casing to increase loudness of the piano sound and to enhance clarity in tone color of the piano sound. Because the keyboard instrument arranges the top door not to be interrupted by an article or object being placed on a top board by a user or player, it is possible to secure the opening function of the top door being opened in connection with opening of the fall cover, so the keyboard instrument is capable of normally demonstrating a loudness enhancement effect of sound. 
     In addition, the keyboard instrument further provides a damping mechanism for imparting resistance load to the fall cover being closed or opened. That is, the damping mechanism uses a rotation damper containing viscous fluid that moves in response to pivotal movement of the fall cover to produce torque by which an increasing load is to be automatically imparted to the fall cover being closed. Thus, it is possible to avoid occurrence of accident due to slammed shut of the fall cover of the piano. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other objects, aspects and embodiment of the present invention will be described in more detail with reference to the following drawing figures, of which: 
     FIG. 1 is a sectional view showing selected parts in construction of an upright piano in which a fall assembly is placed in a closed position; 
     FIG. 2 is a sectional view showing selected parts in construction of the upright piano in which the fall assembly is placed in an open position; 
     FIG. 3 is a perspective view showing appearance of a damping mechanism that is applicable to the upright piano; 
     FIG. 4 is a sectional view showing internal construction of a rotation damper of the damping mechanism in connection with the fall assembly being closed; 
     FIG. 5 is a sectional view showing internal construction of the rotation damper of the damping mechanism in connection with the fall assembly being opened; 
     FIG. 6 is a fragmentarily exploded perspective view showing selected parts for realizing an example of a damping mechanism for the fall assembly; 
     FIG. 7A is a cross sectional view showing an internal construction of a rotation damper, which is an essential part of the damping mechanism shown in FIG. 6, when the fall assembly is placed in a closing position; 
     FIG. 7B is a cross sectional view showing an internal construction of the rotation damper when the fall assembly is placed in an intermediate position; and 
     FIG. 7C is a cross sectional view showing an internal construction of the rotation damper when the fall assembly is placed in an open position. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     This invention will be described in further detail by way of examples with reference to the accompanying drawings. 
     FIGS. 1 and 2 show an upper portion in cross section of an upright piano in accordance with the preferred embodiment of the invention. The upper portion of the upright piano has a keyboard  2 , an action  4  and a case assembly  6 , wherein FIGS. 1 and 2 merely show only selected parts of an upper portion of the case assembly  6 . A lower portion of the case assembly  6  provides strings and tuning keys, which are conventional parts of the upright piano and are omitted in illustration. Similarly, the keyboard  2  and action  4  are conventional parts of the upright piano, hence, detailed description thereof will be omitted. 
     The case assembly  6  includes a fall assembly  8  hinged to side arms  10 , which are placed at side ends of the keyboard  2 , a back hollow assembly  12  connected to the fall assembly  8  and a top door assembly  14  whose side ends are connected to side portion  16  of the case assembly  6 . The top door assembly  14  acts as a front panel being closed for hiding the action  4  inside the case assembly  6 . 
     The case assembly  6  also includes a bottom door assembly, a top cover, a base and a rear panel, all of which are conventional parts of the upright piano and are not shown in the drawings. 
     The fall assembly  8  provides an opening cover for covering the keyboard  2 , which includes a cover top  18  and a cover front  20 . The cover top  18  is attached to a pivot mechanism  23  by means of two slender metal arms (namely, pivot arms)  22 . The pivot mechanism  23  is fixed to the side arms  10  which are placed at the side ends of the keyboard  2 . It is possible to provide a damping mechanism to prevent the fall cover from being slammed shut by a user or player. The damping mechanism can be constructed as similar to one disclosed by European patent application publication EP 0697541 A1. In addition, it is possible to employ a fall mechanism as similar to one disclosed by European patent application publication EP 0901117 A2. Incidentally, details of the aforementioned publications will be described later. 
     FIG. 1 shows a closed position of the fall assembly  8 , while FIG. 2 shows an open position of the fall assembly  8 . To realize an interval of distance or angle between the closed position and open position of the fall assembly  8 , the pivot arms  22  are subjected to limited rotation about the pivot mechanism  23 , that is, rotation of approximately 130°. 
     The back hollow assembly  12  includes a cover rear (or a panel)  24  that extends entirely across a width of the keyboard  2 . A front end of the cover rear  24  is connected to a back end of cover top  18  by a strap hinge  28 . Two pins  32  are arranged in proximity to a back end  30  of the cover rear  24  and in contact with an underside of the cover rear  24 . Concretely speaking, the two pins  32  are respectively arranged on side ends of the cover rear  24  and are placed to engage with guide slots  34 , which are elongated along inner surfaces of the side arms  10  in a slanted manner. 
     In the closed position of the fall assembly  8  shown in FIG. 1, the cover rear  24  is supported horizontally and maintained approximately at a same height of the cover top  18  because the front end  26  is supported by the strap hinge  28  while the back end  30  is supported by the pins  32 . From the closed position, the user or player gradually opens the fall cover so that the fall assembly  8  is to be placed in the open position as shown in FIG.  2 . Accompanied with movement of the fall cover being opened, the pins  32 , which are originally placed in proximity to the back end  30  of the cover rear  24 , slide and move rearwards inside of the slanted guide slots  34 . In addition, the front end  26  of the cover rear  24  moves together with the back end of the cover top  18  and rotates about a pivot mechanism  23  along a prescribed arc orbit. In the open position of the fall assembly  8  shown in FIG. 2, the front end  26  of the cover rear  24  is lowered in elevation and moved rearwards as compared with an original position thereof. Thus, the cover rear  24  is slightly inclined in a forward direction. 
     The top door assembly  14  includes an upper top door  36  and a lower top door  38 . Normally, the upper top door  36  is fixed in position to the side portions  16  of the case assembly  6  to cope with use of the upright piano. An upper end  40  of the lower top door  38  is connected to a lower end of the upper top door  36  by a strap hinge  42 . The lower top door  38  can be rotated rearwards about the strap hinge  42 , so that it is to be entered into an inside of the case assembly  6  of the upright piano. To enable tuning of the upright piano, for example, it is possible to remove the upper top door  36  by the conventional method. 
     A lower end  44  of the lower top door  38  is connected to the back end  30  of the cover rear  24  by means of multiple link members  46 . The link members  46  are arranged at side ends of the lower end  44  of the lower top door  38 . It is possible to provide additional link members along an intermediate portion of a tapped board  48 . Each of the link members  46  is very simple in construction and is made by a single tapped board  48 , for example. The tapped board  48  is arranged such that it extends downwards from the lower end  44  of the lower top door  38 . Bolts  50  each constructed by a shaft and a head are placed to engage with tapped holes of the tapped board  48 . Herein, the bolts  50  extend rearwards from the back end  30  of the cover rear  24 . The shafts of the bolts  50  are inserted into the tapped holes of the tapped board  48 . Due to engagement of the bolts  50  and tapped board  48  in the closed position of the fall assembly  8  shown in FIG. 8, it is possible to securely stop the lower top door  38  in a closed position (namely, vertically closed position). When the lower top door  38  is stopped in the closed position, the cover rear  24  is tightly fixed in position together with the lower top door  38  such that substantially no gap would be formed between the back end  30  of the cover rear  24  and the lower end  44  of the lower top door  38 . 
     In the open position of the fall assembly  8  shown in FIG. 2, as the back end  30  of the cover rear  24  moves rearwards, it presses the lower end  44  of the lower top door  38  by means of the tapped board  48  and bolts  50  so that the lower top door  38  is vertically inclined from its vertical stop position. Due to the aforementioned movement, a small gap  52  is to be formed between the back end  30  of the cover rear  24  and the lower end  44  of the lower top door  38 . Such a small gap  52  allows sound waves of piano sound to be released outside of the casing of the upright piano. This brings an increase of tone volume of the piano sound. Accompanied with movement of the fall cover being opened, the bolts  50  are not disengaged from the tapped holes of the tapped board  48 , hence, they merely move inside of the casing of the upright piano. 
     To play the upright piano, the user opens or closes the fall cover of the fall assembly  8  so that the lower top door  38  is correspondingly opened or closed. In the open position of the fall assembly  8 , the small gap  52  appears between the back end  30  of the cover rear  24  and the lower end  44  of the lower top door  38 . In the closed position of the fall assembly  8 , the gap  52  disappears. 
     Next, a description will be given with respect to an example of the damping mechanism as disclosed by the aforementioned European patent application publication EP 0697541 A1. 
     FIG. 3 shows selected parts in construction of a damping mechanism  112 , which contains a rotation damper  120 , an arm  140  and a support base  142 . The arm  140  is capable of pivotally moving about the rotation damper  120 , which is integrally formed together with the support base  142 . A bottom of the support base  142  is fixed to a wooden part  152  of the piano by appropriate fixing means such as a both-side adhesive tape and a wood screw. A roller  146  is attached to a tip end of the arm  140 , about which it is capable of freely rotating. The roller  146  is normally pressed in contact with an interior surface of the cover top  18  of the fall cover of the piano. A lower end of the arm  140  is forked to a pair of arm support portions  148 , which are pivotally supported by the rotation damper  120 . The rotation damper  120  has a shaft  124  having square terminal ends, which engage with the arm support portions  148  respectively. Accompanied with pivotal movement of the arm  140 , the square shaft  124  of the rotation damper  120  rotates about an axis thereof. 
     FIG. 3 excludes detailed illustration in which a plate spring is hooked on a back of the arm  140  from the bottom of the support base  142 . The plate spring (not shown) has elasticity by which the arm  140  is normally forced to move in an opening direction. Due to restoration force of the plate spring, when the user or player starts to open the fall cover of the fall assembly  8 , the arm  140  presses the cover top  18  upwardly to assist the fall cover being opened. When the user of player closes the fall cover of the fall assembly  8 , the plate spring applies a load to the arm  140  to resist against closing of the fall cover, so that the fall cover is to be slowly and softly closed. 
     FIG. 4 shows details of construction of the rotation damper  120  having the shaft  124  which is contained a cylindrical casing  123 . A center ‘O’ of a cross section of the shaft  124  matches with a center of a cylinder of the casing  123 . The casing  123  has an inner space which is filled with viscous fluid  122  having high viscosity such as grease. A casing blade  123   a  is formed together with the casing  123 . The casing blade  123   a  projects inwardly with the casing  123  and also extends lengthwise along a longitudinal direction of the casing  123 . The casing blade  123   a  functions as a stopper for regulating rotation of a rotation member  125  having the shaft  124 . 
     The shaft  124  has a support projection  126  that supports a moving valve  127  to freely rotate. The support projection  126  extends lengthwise along a longitudinal direction of the shaft  124 . Roughly speaking, the support projection  126  has a circular sectional shape. FIG. 4 merely shows a single support projection  126  that is formed integrally together with shaft  124 . However, it is possible to form multiple support projections with respect to the shaft  124 . 
     The moving valve  127  is accompanied with a fluid passage  134  in which the viscous fluid  122  can move in response to rotation of the rotation member  125 , which is shown in FIG.  5 . FIG. 4 shows that the moving valve  127  is placed in tight contact with an interior wall of the casing  123 , so the fluid passage  134  does not perform its functions. Accompanied with movement of the fall cover of the fall assembly  8  to be opened or closed, the rotation member  125  rotates about the axis thereof, so that the moving valve  127  slides and moves about the support projection  126  along a prescribed arc orbit against resistance being produced by the viscous fluid  122 . 
     When the user or player closes the fall cover of the fall assembly  8 , the shaft  124  rotates in a counterclockwise direction A inside of the casing  123  as shown in FIG.  4 . In that case, the viscous fluid  122  apply resistance to the moving valve  127 . Due to such resistance, the moving valve  127  moves and rotates in a clockwise direction to be placed in tight contact with the interior wall of the casing  123 . Herein, the viscous fluid  122  could flow by passing through a narrow gap  130  between an tip end of the casing blade  123   a  and an exterior wall of the shaft  124 . Flowing speed of the viscous fluid  122  is low so that high rotation torque is to be produced. In short, a damping effect is applied to the fall assembly  8  when the user or player closes the fall cover. 
     In contrast, if the rotation member  125  rotates in a clockwise direction B inside of the casing  123  as shown in FIG. 5, the moving valve  127  moves and rotates about the support projection  126  in a counterclockwise direction against resistance being produced by the viscous fluid  122 . In that case, the moving valve  127  leaves from the interior wall of the casing  123  so that the fluid passage  123  is spaced apart from the interior wall of the casing  123  with a gap. Such a gap allows the viscous fluid  122  to smoothly flow inside of the casing  123 . In short, a damping effect applied to the fall assembly  8  is weakened when the user or player opens the fall cover. 
     In the aforementioned damping mechanism, the moving valve  127  slides on the support projection  126  having a circular sectional shape along the prescribed arc orbit. The sectional shape of the support projection is not necessarily made circular, hence, it is possible to design the support projection having a rectangular sectional shape. That is, it is possible to modify the damping mechanism such that the moving valve  126  slides on the rotation member  125  in its radius direction in response to movement of the fluid inside of the casing  123 . 
     Next, a description will be given with respect to an example of the fall mechanism as disclosed by the foregoing European patent application publication EP 0901117 A2. FIG. 6 shows parts constructing a back end portion of the fall assembly  8 , wherein a fall cover is pivotally connected to a cover rear  214  by means of a strap hinge  28 . In proximity to the strap hinge  28 , a rotation damper  213  is arranged to prevent the fall cover of the fall assembly  8  from being roughly closed. A damper case  213   m  of the rotation damper  213  is buried in an interior wall of a side arm  4  of the piano and is fixed by means of screws  215 . 
     The rotation damper  213  works using viscous resistance of fluid therein. That is, the rotation damper  213  contains a rotation shaft  213   n  that can rotate freely inside of the damper case  213   m  having a cylindrical shape, which is shown in FIGS. 7A to  7 C. A sectional shape of the rotation shaft  213   n  does not correspond to an entire circle but is partially cut by a sector, in which non-compressive damping oil  213   z  is enclosed. Such a sector space inside of the damper case  213  is partitioned into two chambers, namely damping chambers  213   v ,  213   w  by a partition wall  213   u  that projects inwardly from an interior wall of the damper case  213   m.    
     The first damping chamber  213   v  and second damping chamber  213   w  communicate with each other by way of a communication hole  213   xa  that is formed at a selected position of the partition wall  213   u . The partition wall  213   u  provides a check valve  213   y  by which the communication hole  213   xa  can be closed. In addition, the rotation shaft  213   n  has a projection  213   t  having an arc shape in section. When the rotation shaft  213   n  rotates about a center axis AX 2  in a clockwise direction inside of the damper case  213   m , the check valve  213   y  opens the communication hole  213   xa  as shown in FIGS. 7A-7C. This allows the damping oil  213   z  to smoothly flow between the damping chambers  213   v  and  213   w  by way of the communication hole  213   xa . In contrast, when the rotation shaft  213   n  rotates in a counterclockwise direction, the check value  213   y  closes the communication hole  213   xa  in response to flow of the damping oil  213   z , which is caused by counterclockwise rotation of the rotation shaft  213   n . In this case, the damping oil  213   z  is capable of flowing between the damping chambers  213   v  and  213   w  by way of a gap  213   xb  that is formed between an arc-shaped exterior surface of the projection  213   t  and a tip end of the partition wall  213   u . Due to small flowing speed of the damping oil  213   z  by way of the gap  213   xb , a relatively high rotation torque is caused to occur in the rotation damper  213 . Based on such a working principle of the rotation damper  213 , a damping effect is applied to the fall cover of the fall assembly  8  being closed. Such a damping effect is weakened when the user or player opens the fall cover of the piano. 
     The aforementioned technique provides a so-called deviation absorption structure by which positional deviation between a rotation center of the strap hinge  28  and a rotation center of the rotation damper  213  is absorbed to suppress noise or to avoid occurrence of abrasion or damage in FIG.  6 . Concretely speaking, such a deviation absorption structure is embodied by a deviation absorption member  218  that engages with a connection member  217  fixed to a side wall of the back end portion of the fall assembly  8 . Herein, the rotation shaft  213   n  of the rotation damper  213  engages with the deviation absorption member  218 . 
     A pair of through holes  219  are formed to penetrate through the connection member  217  in thickness and are placed to match with a pair of tapped holes  220  formed on the side wall of the fall cover respectively. By engaging screws  216  into the tapped holes  220  by way of the through holes  219 , it is possible to securely fix the connection member  217  onto the side wall of the fall assembly  8 . The connection member  217  has a cylindrical portion  217   e  having an inner space  217   h , into which the deviation absorption member  218  is inserted to engage with. Two projections  217   j  project from an circumferential interior wall of the inner space  217   h  and are arranged linearly in opposite directions. A center axis of the cylindrical portion  217   e  approximately matches with the rotation center AX 1  of the strap hinge  28  of the fall assembly  8 . 
     The deviation absorption member  218  is formed in a cylindrical shape whose outer diameter is smaller than an inner diameter of the cylindrical portion  217   e  of the connection member  217 . One terminal end of the deviation absorption member  218  is partially cut to form a pair of recesses  218   ra , which are formed at circumferentially opposite positions. When the deviation absorption member  218  engages with the inner space  217   h  of the cylindrical portion  217   e , the recesses  218   ra  match with the projections  217   j  respectively. As compared with the projections  217   j , the recesses  218   ra  are slightly elongated to allow a small linear sliding movement of the deviation absorption member  218  along the projections  217   j  in the inner space  217   h.    
     A channel (not shown) is formed on another terminal end of the deviation absorption member  218  to extend in a direction perpendicular to a direction of linear arrangement of the recesses  218   ra . A projecting member  213   q  is formed integrally with the rotation shaft  213   n  of the rotation damper  213  and is linearly elongated to match with a diameter of the rotation shaft  213   n . When the rotation damper  213  is assembled together with the deviation absorption member  218 , the projecting member  213   q  engages with the aforementioned channel within which it can freely slide and move. That is, relative movement is realized between the rotation shaft  213   n  of the rotation damper  213  and the deviation absorption member  218  in the direction along which the channel extends. As described above, an assembly of the connection member  217 , deviation absorption member  218  and rotation shaft  213   n  function as an Oldham&#39;s coupling. 
     In response to pivotal movement of the fall cover of the fall assembly  8  being opened or closed, the connection member  217  pivotally moves together with the fall assembly  8 . This occasionally causes the deviation absorption member  218  to move within the inner space  217   h  of the cylindrical portion  217   e , so that rotation torque is transmitted to the rotation shaft  213   n  of the rotation damper  213 . Therefore, the rotation shaft  213   n  rotates inside of the damper case  213   m  that is fixed to the side arm of the piano. Thus, it is possible to obtain a damping effect, which is described before with reference to FIGS. 7A-7C. Due to operation of the Oldham&#39;s coupling, even if positional deviation emerges between the rotation center AX 1  of the strap hinge  28  of the fall assembly  8  and the rotation center AX 2  of the rotation damper  213   n , the aforementioned parts smoothly operate to secure the damping effect. As a result, it is possible to suppress noise or avoid occurrence of abrasion or damage. 
     It may be needless to say that various types of modifications can be proposed for the upright piano of the present invention within the scope of the invention. That is, the damping mechanism is not necessarily limited in position as described in the present embodiment. For example, it is possible to arrange the damping mechanism for prevention of slammed opening of the fall cover in contact with an underside of the cover rear  24 . In addition, it is possible to employ various structures for the link members  46 . The present embodiment describes the top door assembly being constructed by a fixed upper top door and an opening lower top door. Instead of such construction, it is possible to construct the top door assembly by a single top door that can be opened in connection with opening of the fall cover of the piano. 
     As this invention may be embodied in several forms without departing from the spirit of essential characteristics thereof, the present embodiment is therefore illustrative and not restrictive, since the scope of the invention is defined by the appended claims rather than by the description preceding them, and all changes that fall within metes and bounds of the claims, or equivalence of such metes and bounds are therefore intended to be embraced by the claims.