Patent Publication Number: US-9430993-B2

Title: Keyboard lid opening and closing apparatus and keyboard instrument

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2013-265204, filed Dec. 24, 2013, the entire contents of which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a keyboard lid opening and closing apparatus that are used in keyboard instruments such as pianos and organs, and a keyboard instrument provided with the keyboard lid opening and closing apparatus. 
     2. Description of the Related Art 
     A keyboard lid opening and closing apparatus in a keyboard instrument such as an electric piano is known in which a keyboard lid that openably and closably covers a keyboard section provided in an instrument case is constituted by a plurality of plates sequentially connected to one another to be foldable, as shown in, for example, Japanese Patent Application Laid-Open (Kokai) Publication No. 2007-133249. 
     This type of keyboard lid opening and closing apparatus is structured such that, when the keyboard section of the keyboard instrument is to be covered by the keyboard lid, the plurality of plates are sequentially unfolded in a front-rear direction and thereby sequentially arranged above the keyboard section so as to cover this keyboard section. When the keyboard lid is to be opened to expose the keyboard section, the plates are sequentially folded and accommodated in the instrument case so as to expose the keyboard section. 
     However, this keyboard lid opening and closing apparatus for a keyboard instrument has problems in that the plurality of plates are not smoothly folded unless they are all formed in the same size, and do not stand upright stably when they are folded by being held upright, due to which their upper portions easily tilt in the front-rear direction. Accordingly, the folding of the plates of this keyboard lid opening and closing apparatus is bothersome. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a keyboard lid opening and closing apparatus by which a keyboard lid can be stably and smoothly opened or closed, and a keyboard instrument provided with this keyboard lid opening and closing apparatus. 
     In accordance with one aspect of the present invention, there is provided a keyboard instrument comprising: a keyboard section; an instrument case in which the keyboard section is provided; a keyboard lid which has a front lid and a rear lid connected by a coupling member such that the keyboard lid is foldable, and exposes the keyboard section in a folded state; a rotary fulcrum section which is provided above the keyboard section, and rotates a rear end portion of the rear lid so that the rear lid is held above the keyboard section with a front end portion of the rear lid being positioned higher than the rear end portion of the rear lid, when the keyboard lid exposes the keyboard section; and a guide section which guides a front end portion of the front lid toward an area below the rotary fulcrum section so that the front lid is held above the keyboard section with a rear end portion of the front lid being positioned higher than the front end portion of the front lid, when the keyboard lid exposes the keyboard section. 
     The above and further objects and novel features of the present invention will more fully appear from the following detailed description when the same is read in conjunction with the accompanying drawings. It is to be expressly understood, however, that the drawings are for the purpose of illustration only and are not intended as a definition of the limits of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a sectional view of a first embodiment where the present invention has been applied in a keyboard instrument, in which a keyboard lid, has been closed to cover a keyboard section; 
         FIG. 2  is a sectional view of the keyboard instrument shown in  FIG. 1 , in which the keyboard lid has been mountain-folded to expose the keyboard section; 
         FIG. 3  is a sectional view of the main section of a second embodiment where the present invention has been applied in a keyboard instrument, in which a keyboard lid is being closed to cover a keyboard section; 
         FIG. 4  is a sectional view of the main section of the keyboard instrument shown in  FIG. 3 , in which the keyboard lid has been mountain-folded to expose the keyboard section; 
         FIG. 5  is an enlarged view of the main section of the keyboard instrument shown in  FIG. 4 , in which a second braking section and a lock section are shown; 
         FIG. 6  is a sectional view of a third embodiment where the present invention has been applied in a keyboard instrument, in which a state is shown where a musical sound has been emitted with a keyboard lid being mountain-folded to expose a keyboard section; 
         FIG. 7  is a sectional view of the keyboard instrument shown in  FIG. 2 , in which a music stand section has been provided on the surface of the front lid of the keyboard lid; and 
         FIG. 8  is a perspective view of a keyboard lid supporting section that is embedded in each of a pair of side plates. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     (First Embodiment) 
     A first embodiment in which the present invention has been applied in a keyboard instrument will hereinafter be described with reference to  FIG. 1  and  FIG. 2 . 
     As shown in  FIG. 1  and  FIG. 2 , this keyboard instrument includes an instrument case  1 . 
     This instrument case  1  includes abase plate  2 , a front plate  3  provided upright on the front end (left end in  FIG. 1 ) of the base plate  2 , a rear plate  4  provided upright on the rear end (right end in  FIG. 1 ) of the base plate  2 , a pair of side plates  5  provided upright on the sides (near and far side surfaces in  FIG. 1 ) of the base plate  2 , and a top plate  6  provided on the upper ends of the rear plate  4  and the side plates  5 . In this embodiment, the height of the front plate  3  is formed to be equal to or shorter than half the height of the rear plate  4 . 
     The side plates  5  are each formed such that its front side (left side in  FIG. 1 ) is slightly higher than the front plate  3 , and its rear side (right side in  FIG. 1 ) is the same height as the rear plate  4 , as shown in  FIG. 1  and  FIG. 2 . As a result, the upper portion of a boundary area between the front side and the rear side of each side plate  5  forms a descending section  5   a  having a substantially vertical descending surface, and the lower portion below this descending section  5   a  forms a tilted section  5   b  gently inclined toward the lower portion of the front end of the side plate  5 . 
     Also, in this embodiment, a keyboard lid supporting section  5   c  which supports and guides a keyboard lid  14  is embedded in each of the pair of side plates  5 . 
     The top plate  6  is mounted across the rear portions of the upper ends of the side plates  5  and the upper end of the rear plate  4 , as shown in  FIG. 1  and  FIG. 2 . As a result, the instrument case  1  has a substantially box shape whose portion on the side of the front portions of the side plates  5  has been exposed upwardly. In this embodiment, a sound emission lid  6   a  is provided in the area of the rear portion of the top plate  6  such that it is openable and closable, and an auxiliary top plate  9  is formed below this sound emission lid  6   a.    
     The front end portion of this auxiliary top plate  9  is attached to the lower side of the rear end portion of the top plate  6 , and the rear end portion thereof is attached to the upper inner surface of the rear plate  4 , as shown in  FIG. 1  and  FIG. 2 . In the auxiliary top plate  9 , a sound hole  9   a  is provided penetrating through the auxiliary top plate  9 . In this embodiment, the rear end portion of the sound emission lid  6   a  is rotatably attached to the upper end of the rear plate  4  by a hinge  6   b , and the sound emission lid  6   a  is vertically rotated centering on the hinge  6   b  so as to open or close the sound hole  9   a  of the auxiliary top plate  9 . 
     In the front side of the instrument case  1 , a keyboard section  7  is provided in a state of being exposed upward, as shown in  FIG. 1  and  FIG. 2 . The keyboard section  7  includes a keyboard chassis  7   a  provided on the base plate  2  of the instrument case  1 , and a plurality of keys  8  arranged in parallel on the keyboard chassis  7   a . These keys  8  are constituted by white keys  8   a  and black keys  8   b . The rear end portion of each key  8  is attached to the keyboard chassis  7   a  such that it is rotatable in a vertical direction, and the keys  8  in this state are exposed toward the upper front of the instrument case  1 . 
     In the instrument case  1 , an action mechanism section  10  which applies an action load to each key  8  of the keyboard section  7  is provided to be positioned behind the keyboard section  7 , as shown in  FIG. 1  and  FIG. 2 . This action mechanism section  10  is structured such that , when a key  8  is depressed, a hammer member  10   a  corresponding to the pressed key  8  is rotated and whereby an action load is applied to this key  8 . 
     That is, this action mechanism section  10  is structured such that a key-press feel similar to that of an acoustic piano is achieved by an action load being applied to a key  8 , as shown in  FIG. 1  and  FIG. 2 . in addition, this action mechanism section  10  includes a switching circuit section  11  which performs a switching operation when the hammer member  10   a  is rotated and an action load is applied to a key  8 . The switching circuit section  11  is structured to output an electrical signal that generates a musical sound from a loudspeaker (not shown in the first embodiment) by a switching operation. 
     In this embodiment, in the instrument case  1 , a partition member  12  is provided as a partition between the keyboard section  7  and the action mechanism section  10 , as shown in  FIG. 1  and  FIG. 2 . This partition member  12  includes a cover plate  12   a  that covers the rear end portions of the plurality of keys  8  of the keyboard section  7 , and an upper front plate  12   b  that is provided substantially upright on the rear end portion of the cover plate  12   a . The upper front plate  12   b  is arranged such that it is located at a position shifted rearward from the front end portion of the top plate  6 , and its upper end portion is positioned on the undersurface of the top plate  6 . 
     As shown in  FIG. 1  and  FIG. 2 , in the instrument case  1 , a keyboard lid opening and closing apparatus  13  for openably and closably covering the keyboard section  7  is provided, which includes the keyboard lid  14  that openably and closably covers the keyboard section  7 . The keyboard lid  14  includes a front lid  15  and a rear lid  16  whose lengths in the longitudinal direction of the keyboard section  7  differ from each other, which are foldably connected by a coupling member  17  such as a hinge. 
     That is, the keyboard lid  14  is unfolded to be in a substantially platelike form by the front lid  15  and the rear lid  16  being rotated centering on the coupling member  17 , and arranged above the keyboard section  7  in this state, whereby the front lid  15  covers the front side of the keyboard section  7  and the rear lid  16  covers the rear side thereof, as shown in  FIG. 1  and  FIG. 2 . In this embodiment, the length of the front lid  15  in the longitudinal direction is formed longer than that of the rear lid  16 . 
     The keyboard lid opening and closing apparatus  13  includes rotary fulcrum sections  18  which support the rear end portion of the rear lid  16  such that the rear lid  16  is rotatable with respect to the instrument case  1 , and guide sections  19  which guide the front end portion of the front lid  15  in the front-rear direction of the keyboard section  7 , as shown in  FIG. 1 ,  FIG. 2 , and  FIG. 8 . Each of the rotary fulcrum sections  18  is a hinge section, and includes a shaft section  18   a  provided in one of the keyboard lid supporting sections  5   c  in the pair of side plates  5  and positioned in the lower portion of the upper front plate  12   b  of the partition member  12 , and a cylindrical bearing section  18   b  provided in the upper portion of the rear end of the rear lid  16 . 
     As a result, each rotary fulcrum section  18  is structured such that the shaft section  18   a  provided in one of the keyboard lid supporting sections  5   c  embedded in the pair of side plate  5  is inserted into the bearing section  18   b  of the rear lid  16 , and the rear lid  16  is rotated in this state in the vertical direction, centering on the shaft section  18   a , as shown in  FIG. 1 ,  FIG. 2 , and  FIG. 3 . Also, each rotary fulcrum section  18  is structured such that, when being opened to expose the keyboard section  7  by the front lid  15  and the rear lid  16  being tilted by the coupling member  17 , the keyboard lid  14  is folded such that surfaces of the front lid  15  and the rear lid  16  on the side of the keyboard section  7  come close to each other, and the front lid  15  is held upright above the rear portion of the keyboard section  7 . 
     The guide sections  19  are grooves provided in the inner surfaces of the pair of side plates  5  in the instrument case  1  and guides, in the front-rear direction of the keyboard section  7 , guide projection sections  15   a  provided on the lower portion of the front end of the front lid  15  and inserted into the guide sections  19 , as shown in  FIG. 1 ,  FIG. 2 , and  FIG. 8 . That is, each guide section  19  is continuously formed such that it rises from an area near the front end of the keyboard section  7 , passes through an area above the keyboard section  7 , and reaches an area above the cover plate  12   a  behind the keyboard section  7 . The end portions of these grooves on the side of the cover plate  12   a  are formed to be gradually declined. 
     As a result, the keyboard lid  14  is structured such that, when unfolded to be in a substantially plate-like form by the front lid  15  and the rear lid  16  being rotated centering on the coupling member  17  and arranged above the keyboard section  7  in this state, the guide projection sections  15   a  of the front lid  15  are supported in the front end portions of the guide sections  19  with the front lid  15  being slightly tilted forward and downward, and the rear end portion of the rear lid  16  is supported by the rotary fulcrum sections  18  with the rear lid  16  being substantially horizontalized, as shown in  FIG. 1 . That is, the keyboard lid  14  is structured to cover the keyboard section  7  with the front lid  15  and the rear lid  16  being slightly tilted by the coupling member  17 . 
     Also, the keyboard lid  14  is structured such that, when surfaces of the front lid  15  and the rear lid  16  on the side of the keyboard section  7  come close to each other by being tilted centering on the coupling member  17 , and the keyboard lid  14  is opened thereby to expose the keyboard section  7 , the front lid  15  is supported in a state of being held substantially upright by the guide projection sections  15   a  thereof being positioned in the rear end portions of the guide sections  19 , and the rear lid  16  is held upright by the rear end portion thereof being supported by the rotary fulcrum sections  18 , as shown in  FIG. 2 . Here, weight is added to the rear end portion of the standing front lid  15  from the front end portion of the rear lid  16  which is held upright by the rotary fulcrum sections  18 , whereby the guide projection sections  15   a  stop movement in end portions of the guide sections  19  on the side of the cover plate  12   a.    
     Next , the operation of the keyboard lid opening and closing apparatus  13  in this keyboard instrument is described. 
     When the keyboard lid  14  is closed to cover the keyboard section  7 A, the rear lid  16  is substantially horizontally arranged above the rear portion of the keyboard section  7  by the rear end portion of the rear lid  16  being rotated around the rotary fulcrum sections  18  in the counterclockwise direction, and the front lid  15  and the rear lid  16  forma plate-like shape by being rotated centering on the coupling member  17 , as shown in  FIG. 1 . 
     Here, the guide projection sections  15   a  provided on the front end portion of the front lid  15  are supported by the guide sections  19  with them being guided by the guide sections  19  and positioned in the front end portions of the guide sections  19 , whereby the front lid  15  is arranged above the upper portion of the keyboard section  7  in a state of being slightly tilted forward and downward, as shown in  FIG. 1 . 
     Also, the rear end portion of the rear lid  16  is supported by the rotary fulcrum sections  18 , whereby the rear lid  16  is substantially horizontally arranged above the rear portion of the keyboard section  7 , as shown in  FIG. 1 , As a result, the keyboard lid  14  is arranged above the keyboard section  7  with the front lid  15  and the rear lid  16  being slightly tilted by the coupling member  17 , and covers the keyboard section  7 . 
     On the other hand, when opening the keyboard lid  14  in the state shown in  FIG. 1  so as to expose the keyboard section  7 , the instrument player holds the lower front end of the front lid  15 , and pushes the front lid  15  in the posterior direction of the keyboard section  7  while being pushed upward. As a result, the guide projection sections  15   a  of front lid  15  start moving toward an area posterior to the keyboard section  7  along the guide sections  19 , and the rear end portion of the rear lid  16  start rotating around the rotary fulcrum sections  18  in the clockwise direction. 
     Here, the front lid  15  and the rear lid  16  have been arranged above the keyboard section  7  with them being slightly tilted centering on the coupling member  17  by mountain folding, as shown in  FIG. 1 . Accordingly, when the guide projection sections  15   a  of the front lid  15  start moving toward the area posterior to the keyboard section  7  along the guide sections  19 , the front lid  15  and the rear lid  16  start rotating around the coupling member  17 , whereby they are gradually tilted. 
     Then, when the front lid  15  is further pushed toward the area posterior to the keyboard section  7 , the guide projection sections  15   a  of the front lid  15  are further moved toward the area posterior to the keyboard section  7  along the guide sections  19 , and the rear end portion of the rear lid  16  is further rotated around the rotary fulcrum sections  18  in the clockwise direction. Accordingly, the front lid  15  and the rear lid  16  are further rotated centering on the coupling member  17 , and further tilted thereby. As a result, the rear end portion of the front lid  15  and the front end portion of the rear lid  16  are oriented upward. 
     In this state, when the front lid  15  is further pushed toward the area posterior to the keyboard section  7 , the undersurface (right side surface in  FIG. 2 ) thereof comes close to the undersurface (left side surface in  FIG. 2 ) of the rear lid  16  with them being opposed to each other as shown in  FIG. 2 , and the front lid  15  is held slightly upright with the guide projection sections  15   a  thereof being positioned in the rear end portions of the guide sections  19 . In addition, the rear lid  16  is held upright by its rear end portion being further rotated around the rotary fulcrum sections  18  in the clockwise direction. 
     Here, the guide projection sections  15   a  of the front lid  15  are supported by the rear end portions of the guide sections  19 , whereby the front lid  15  is held slightly upright above the rear end portion of the keyboard section  7 , as shown in  FIG. 2 . As a result , the folded keyboard lid  14  is held upright above the rear end portion of the keyboard section  7  with the undersurface (right side surface in  FIG. 2 ) of the front lid  15  and the undersurface (left side surface in  FIG. 2 ) of the rear lid  16  being positioned opposed to and close to each other, whereby the keyboard section  7  is exposed. Also, here, weight is added to the rear end portion of the standing front lid  15  from the front end portion of the rear lid  16  which is held upright by the rotary fulcrum sections  18 , whereby the guide projection sections  15   a  stop movement in the end portions of the guide sections  19  on the side of the cover plate  12   a.    
     In this state where the keyboard section  7  has been exposed, a musical performance can be performed by the plurality of keys  8  of the keyboard section  7  being depressed. Specifically, when a key  8  is depressed, the hammer member  10   a  of the action mechanism section  10  is rotated and thereby applies an action load to the key  8 . In addition, at this timing, the switching circuit section  11  of the action mechanism section  10  performs a switching action and outputs an electrical signal. Then, a musical sound based on the electrical signal from the switching circuit section  11  is emitted from the loudspeaker (not shown) 
     As described above, the keyboard lid opening and closing apparatus  13  of this keyboard instrument includes the instrument case  1  provided with the keyboard section  7 ; the keyboard lid  14  which is constituted by the front lid  15  and the rear lid  16  whose lengths in the front-rear direction of the keyboard section  7  are different from each other being foldably connected to each other by the coupling member  17 , and openably and closably covers the keyboard section  7 ; the rotary fulcrum sections  18  which support the rear end portion of the rear lid  16  such that the rear lid  16  is rotatable with respect to the instrument case  1 , and by which the keyboard lid  14  is folded and the front lid  15  is held upright above the rear portion of the keyboard section  7  when the keyboard lid  14  is opened to expose the keyboard section  7 ; and the guide sections  19  which guide the front end portion of the front lid  15  in the front-rear direction of the keyboard section  7 . As a result, the keyboard lid  14  can be stably and smoothly opened or closed. 
     That is, in the keyboard lid opening and closing apparatus  13  of this keyboard instrument, when the keyboard lid  14  is to be opened or closed, the rear lid  16  can be rotated around the rotary fulcrum sections  18  with its rear end portion being supported by the rotary fulcrum sections  18 . As a result of this rotation of the rear lid  16 , the front end portion of the front lid  15  is guided by the guide section  19 , whereby the front lid  15  can be held upright. Therefore, even though the lengths of the front lid  15  and the rear lid  16  in the front-rear direction of the keyboard section  7  are different from each other, the keyboard lid  14  can be stably and smoothly opened or closed. In addition, the keyboard lid  14  is not required to be housed in the instrument case  1 , and therefore the instrument case  1  can be made compact. 
     For example, when opening the keyboard lid  14  so as to expose the keyboard section  7 , the instrument player holds the lower front end of the front lid  15 , and pushes the front lid  15  in the posterior direction of the keyboard section  7  while being pushed upward. As a result, the guide projection sections  15   a  of front lid  15  start moving toward an area posterior to the keyboard section  7  along the guide sections  19 , and the rear end portion of the rear lid  16  start rotating around the rotary fulcrum sections  18  in the clockwise direction. Consequently, the front lid  15  and the rear lid  16  are rotated centering on the coupling member  17 , whereby the keyboard lid  14  can be unfailingly and favorably folded. 
     As a result, the guide projection sections  15   a  of the front lid  15  are positioned in the rear end portions of the guide sections  19  so as to be supported therein, and the rear end portion of the rear lid  16  is held upright by the rotary fulcrum sections  18 . Consequently, the guide projection sections  15   a  of the front lid  15  are supported in the rear end portions of the guide sections  19  with the front lid  15  and the rear lid  16  being positioned close to and opposed to each other, whereby the front lid  15  can be held substantially upright above the rear portion of the keyboard section  7 . 
     As a result of this structure, the keyboard lid  14  can be folded and held upright stably above the rear end portion of the keyboard section  7 , and the keyboard section  7  can be favorably exposed from the front side of the instrument case  1 , so that the instrument player can perform a musical performance by depressing the plurality of keys  8  of the keyboard section  7  in this state. In addition, the keyboard section  7  is not required to be housed in the instrument case  1 , and therefore the instrument case  1  can be made compact. 
     Also, when the instrument player is performing a musical performance by depressing the plurality of keys  8  of the keyboard section  7 , the front lid  15  is being held substantially upright above the rear portion of the keyboard section  7 . As a result of this structure, the guide projection sections  15   a  of the front lid  15  can be hidden by the front lid  15 , and the coupling member  17  can be hidden so as not to be seen from the outside, which are favorable in appearance and design. In addition, the instrument player&#39;s hands and fingers are reflected on the standing front lid  15 , whereby a touch of class is added. 
     Also, in this structure, the length of the front lid  15  in the front and rear direction is formed longer than that of the rear lid  16 . As a result, when the front lid  15  is held substantially upright above the rear portion of the keyboard section  7 , the rear lid  16  and the rotary fulcrum sections  18  are unfailingly and favorably hidden by the front lid  15 , which is also favorable in appearance and design. 
     Moreover, the rotary fulcrum sections  18  are provided at positions where they are located higher than the front end portion of the front lid  15  and do not come in contact with the guide projection sections  15   a  when the keyboard lid  14  is folded and the keyboard section  7  is exposed. Accordingly, when the front lid  15  is held substantially upright above the rear portion of the keyboard section  7 , the front end portion of the front lid  15  is positioned below the rotary fulcrum sections  18 , whereby the rotary fulcrum sections  18  are hidden by the front lid  15 , and the front lid  15  is supported in a state of being hanged by the rear lid  16  which is being supported by the rotary fulcrum sections  18 . As a result of this structure, the front lid  15  can be stably and favorably held upright. 
     Note that, although the shaft sections  18   a  and the guide sections  19  in this embodiment are provided in the keyboard lid supporting sections  5   c  embedded in the pair of side plates  5 , they may be provided in the side plates  15  directly. 
     (Second Embodiment) 
     Next, a second embodiment in which the present invention has been applied in a keyboard instrument is described with reference to  FIG. 3  to  FIG. 5 . Note that sections identical to those of the first embodiment shown in  FIG. 1  and  FIG. 2  are provided with the same reference numerals. 
     As shown in  FIG. 3  and  FIG. 4 , the structure of a keyboard lid opening and closing apparatus  20  in this keyboard instrument is substantially the same as that of the first embodiment except that a spring member  21  is included that forces the front lid  15  and the rear lid  16  in their folding directions, and a pair of first braking sections  22  and a pair of second braking sections  23  that brake the movement of the front end portion of the front lid  15 . 
     The spring member  21  is a helical extension spring whose one end portion  21   a  is attached to the undersurface of the front portion of the front lid  15  and the other end portion  21   b  is attached to the undersurface of the front portion of the rear lid  16 , as shown in  FIG. 3  and  FIG. 4 . That is, the spring member  21  forces the front lid  15  and the rear lid  16  in their folding directions by pulling them toward each other. In this embodiment, spring housing grooves  24  for housing the spring member  21  are provided in the undersurface (right side surface in  FIG. 4 ) of the front lid  15  and the undersurface (left side surface in  FIG. 4 ) of the rear lid  16 . 
     As a result of this structure, when the keyboard lid  14  is to be opened to expose the keyboard section  7 , the keyboard lid  14  is lightly mountain-folded by the spring force of the spring member  21 , as shown in  FIG. 3  and  FIG. 4 . Also, when the folded and standing keyboard lid  14  is to be unfolded to be closed, the front lid  15  is prevented by the spring force of the spring member  21  from being rapidly closed. 
     Also, each first braking section  22  is a torsion coil spring structured such that its coil portion is attached to a supporting projection section  25  provided on an inner surface portion of each side plate  5  of the instrument case  1  on the side of the front portion of the keyboard section  7 ; its one end portion  22   a  is attached to the inner surface of the corresponding side plate  5 ; and the other end portion  22   b  is positioned in the upper side of the front end portion of the corresponding guide section  19  in the movement path of the corresponding guide projection section  15   a  of the front lid  15 , and resiliently displaced between the upper side and the lower side of the front end portion of this guide section  19 , as shown in  FIG. 3  and  FIG. 4 . 
     As a result, the first braking section  22  is structured such that, if the guide projection section  15   a  provided on the front end portion of the front lid  15  comes in resilient contact with the other end portion  22   b  of the first braking section  22  when the keyboard lid  14  is closed to cover the keyboard section  7 , the other end portion  22   b  is resiliently displaced from the upper side of the front end portion of the guide section  19  to the lower side in the movement path of the guide projection section  15   a  of the front lid  15 , and thereby brakes the closing movement of the front lid  15  so that the front lid  15  is closed slowly, as shown in  FIG. 3 . 
     Also, the first braking section  22  is structured such that, when the keyboard lid  14  is to be opened by the front lid  15  being pushed upward and moved toward an area posterior to the keyboard section  7 , the front lid  15  starts moving by weak force because the guide projection section  15   a  of the front lid  15  is being pushed upward by the other end portion  22   b  of the first braking section  22  resiliently, as shown in  FIG. 3 . 
     On the other hand, each second braking section  23  is a torsion coil spring structured such that its coil portion is attached to a supporting projection section  26  provided on an inner surface portion of each side plate  5  of the instrument case  1  on the side of the rear portion of the keyboard section  7 ; its one end portion  23   a  is attached to the inner surface of the corresponding side plate  5 ; and the other end portion  23   b  resiliently and retractably protrudes into the movement path of the corresponding guide projection section  15   a  of the front lid  15  in the rear end portion of the corresponding guide section  19 , as shown in  FIG. 4  and  FIG. 5 . 
     In this embodiment, the other end portion  23   b  of the second braking section  23  resiliently and retractably protrudes into the movement path of the guide projection section  15   a  of the front lid  15  in the rear end portion of the guide section  19  in a state of being oriented obliquely upward toward the front side (left side in  FIG. 5 ) of the guide section  19 , as shown  FIG. 4  and  FIG. 5 . 
     As a result, the second braking section  23  is structured such that, if the guide projection section  15   a  of the front lid  15  comes in resilient contact with the other end portion  23   b  of the second braking section  23  when the keyboard lid  14  is opened to expose the keyboard section  7 , the other end portion  23   b  is resiliently displaced toward a direction which is pushed out of the movement path of the guide projection section  15   a  of the front lid  15  in the rear end portion of the guide section  19 , and thereby brakes the opening movement of the front lid  15  so as to rapidly decelerate the movement of the front lid  15 . 
     In this embodiment, the second braking section  23  is structured such that the other end portion  23   b  is resiliently displaced toward the direction which is pushed out of the movement path of the guide projection section  15   a  of the front lid  15  by the guide projection section  15   a  moved from the front side (left side in  FIG. 5 ) of the guide section  19  to the rear side (right side in  FIG. 5 ), and a click feeling is provided to the guide projection section  15   a  by the guide projection section  15   a  surmounting the other end portion  23   b , as shown in  FIG. 4  and  FIG. 5 . 
     That is, this second braking section  23  rapidly decelerates the movement of the front lid  15  when the guide projection section  15   a  of the front lid  15  is moved from the front side of the guide section  19  to the rear side and comes in contact with the tip of the other end portion  23   b  of the second braking section  23 , and rapidly accelerates the movement of the front lid  15  when the guide projection section  15   a  of the front lid  15  surmounts the other end portion  23   b  of the second braking section  23  by resiliently displacing it, so that a click feeling is provided to the guide projection section  15   a , as shown in  FIG. 4  and  FIG. 5 . 
     Also, the second braking section  23  is structured such that, when the guide projection section  15   a  of the front lid  15  surmounts the other end portion  23   b , the other end portion  23   b  protrudes into the movement path of the guide projection section  15   a  by resilient restoration so that the guide projection section  15   a  of the front lid  15  is not undesirably moved toward the front side (left side in  FIG. 5 ) of the guide section  19 , as shown in  FIG. 4  and  FIG. 5 . 
     Moreover, the second braking section  23  is structured such that, when the front lid  15  above the rear portion of the keyboard section  7  is moved frontward to close the keyboard lid  14 , the guide projection section  15   a  of the front lid  15  is moved along the tilt of the other end portion  23   b  of the second braking section  23 , surmounts the other end portion  23   b  by resiliently displacing it by weak force, and thereby passes through the other end portion  23   b , as shown in  FIG. 4  and  FIG. 5 . 
     Also, this keyboard lid opening and closing apparatus  20  includes a lock section  27  which engageably or disengageably locks one of the guide projection sections  15   a  of the front lid  15  when the keyboard lid  14  is opened and the keyboard section  7  is exposed, as shown in  FIG. 4  and  FIG. 5 . This lock section  27  includes a main body section  27   a  which is attached to the inner surface of the corresponding sideplate  5  of the instrument case  1  and positioned behind the rear end portion of the corresponding guide section  19 , and a catch section  27   b  which is retractably provided in the main body section  27   a  and disengageably locks the corresponding guide projection section  15   a  of the front lid  15 . 
     That is, the lock section  27  is structured such that, when the guide projection section  15   a  of the front lid  15  surmounts the other end portion  23   b  of the second braking section  23  and the keyboard lid  14  is opened to expose keyboard section  7 , the catch section  27   b  catches and locks the guide projection section  15   a  of the front lid  15 , whereby the front lid  15  is locked in a state of being held upright above the rear portion of the keyboard section  7 , as shown in  FIG. 3  and  FIG. 4 . 
     Also, this lock section  27  is structured such that, when the front lid  15  is to be moved frontward to close the keyboard lid  14  with the guide projection section  15   a  of the front lid  15  being caught and locked by the catch section  27   b , the lock of the guide projection section  15   a  of the front lid  15  by the catch section  27   b  is released by the front lid  15  being pushed once toward an area posterior to the keyboard section  7 , whereby the guide projection section  15   a  of the front lid  15  is released from the catch section  27   b , as shown in  FIG. 4 . 
     By the keyboard lid opening and closing apparatus  20  of this keyboard instrument as well, operations and effects similar to those of the first embodiment can be provided. In addition, since the spring member  21  is included which forces the front lid  15  and the rear lid  16  in the direction in which they come close to each other by being tilted, the keyboard lid  14  can be folded with little strength by the spring force of the spring member  21  when the keyboard lid  14  is opened to expose the keyboard section  7 . 
     Also, with this keyboard lid opening and closing apparatus  20 , the front lid  15  can be prevented by the spring force of the spring member  21  from being undesirably closed when the keyboard section  7  is being exposed by the keyboard lid  14  being folded. In addition, when the keyboard lid  14  folded and held upright is to be unfolded and closed, the front lid  15  can be prevented by the spring force of the spring member  21  from being rapidly closed, and whereby the keyboard lid  14  can be safely closed, which improves operability related to the opening and closing of the keyboard lid  14 . 
     Moreover, this keyboard lid opening and closing apparatus  20  includes the first braking sections  22  which resiliently brake the movement of the front end portion of the front lid  15  when the keyboard lid  14  is closed and the keyboard section  7  is exposed. Therefore, when the keyboard lid  14  is to be closed to cover the keyboard section  7 , the closing movement of the front lid  15  can be braked by the first braking sections  22  so that the front lid  15  can be closed slowly. 
     Accordingly, with this keyboard lid opening and closing apparatus  20 , the instrument player does not get his or her hand or finger caught in the keyboard lid  14  when closing the keyboard lid  14  to cover the keyboard section  7 . As a result , the keyboard lid  14  is closed safely and abnormal noise or the like is not made. Also, when opening the keyboard lid  14  to expose the keyboard section  7 , the instrument player can move the front lid  15  with little strength by the action of the first braking sections  22 . 
     In this embodiment, each first braking section  22  is structured such that the coil portion of the torsion coil spring is attached to the supporting projection section  25  provided in each side plate  5  of the instrument case  1 ; the one end portion  22   a  is attached and fixed to the corresponding side plate  5 ; and the other end portion  22   b  is positioned above the front end portion of the corresponding guide section  19  in the movement path of the corresponding guide projection section  15   a  of the front lid  15 , and resiliently displaced between the upper side and the lower side of the front end portion of this guide section  19 . Accordingly, the front lid  15  can be braked reliably. 
     That is, the first braking section  22  is structured such that, if the guide projection section  15   a  of the front lid  15  comes in resilient contact with the other end portion  22   b  of the first braking section  22  when the keyboard lid  14  is closed to cover the keyboard section  7 , the other end portion  22   b  is resiliently displaced from the upper side of the front end portion of the guide section  19  to the lower side in the movement path of the guide projection section  15   a , and thereby brakes the closing movement of the front lid  15  so that the front lid  15  is closed slowly. 
     Also, the first braking section  22  pushes the guide projection section  15   a  of the front lid  15  upward by the resilient return force of the other end portion  22   b  of the first braking section  22  when the keyboard lid  14  is opened by the front lid  15  being pushed upward and moved toward an area posterior to the keyboard section  7 . As a result of this structure, the front lid  15  can be pushed upward and moved with little strength, which improves operability related to the opening and closing of the keyboard lid  14 . 
     Also, this keyboard lid opening and closing apparatus  20  includes the second braking sections  23  which resiliently brake the movement of the front end portion of the front lid  15  when the keyboard lid  14  is opened to expose the keyboard section  7 . Accordingly, when the keyboard lid  14  is to be opened to expose the keyboard, the opening movement of the front lid  15  can be braked by the second braking sections  23  so that the movement of the front lid  15  is decelerated. In addition, when the keyboard lid  14  is to be closed to cover the keyboard section  7 , the closing movement of the front lid  15  can be braked by the second braking sections  23  so that the front lid  15  is prevented from being undesirably closed. 
     In this embodiment, each second braking section  23  is structured such that the coil portion of the torsion coil spring is attached to the supporting projection section  26  provided on each side plate  5  of the instrument case  1 ; the one end portion  23   a  is attached and fixed to the corresponding side plate  5 ; and the other end portion  23   b  resiliently and retractably protrudes into the movement path of the corresponding guide projection section  15   a  of the front lid  15  in the rear end portion of the corresponding guide section  19  in a state of being oriented obliquely upward toward the front side of the corresponding guide section  19 . 
     That is, the second braking section  23  is structured such that, if the guide projection section  15   a  of the front lid  15  comes in resilient contact with the other end portion  23   b  of the second braking section  23  when the keyboard lid  14  is opened to expose the keyboard section  7 , the other end portion  23   b  is resiliently displaced toward the direction which is pushed out of the movement path of the guide projection section  15   a , and thereby brakes the opening movement of the front lid  15  so as to decelerate the movement of the front lid  15 . 
     In this embodiment, since the other end portion  23   b  is oriented obliquely upward toward the front side of the guide section  19 , the second braking section  23  can provide a click feeling to the guide projection section  15   a  by the guide projection section  15   a  of front lid  15  resiliently displacing the other end portion  23   b  in the direction in which the other end portion  23   b  is pushed out of the movement path of the guide projection section  15   a  and surmounts the other end portion  23   b.    
     That is, the second braking section  23  rapidly decelerates the movement of the front lid  15  by the guide projection section  15   a  coming in contact with the other end portion  23   b  for resiliently displacing and surmounting the other end portion  23   b , and rapidly accelerates the movement of the front lid  15  by the guide projection section  15   a  surmounting the other end portion  23   b , whereby a click feeling is provided to the guide projection section  15   a . As a result of this structure, the instrument player can confirm that the guide projection section  15   a  of the front lid  15  has overshot the other end portion  23   b  of the second braking section  23 . 
     Also, the second braking section  23  is structured such that, when the guide projection section  15   a  of the front lid  15  surmounts the other end portion  23   b , the other end portion  23   b  protrudes into the movement path of the guide projection section  15   a  by resilient restoration. As a result, by the other end portion  23   b  resiliently returned and protruding thereinto, the guide projection section  15   a  of the front lid  15  can be prevented from being undesirably moved toward the front side of the guide section  19 , whereby the front lid  15  can be held upright securely. 
     Moreover, when the front lid  15  above the rear portion of the keyboard section  7  is moved frontward to close the keyboard lid  14 , since the other end portion  23   b  of the second braking section  23  is resiliently protruding into the movement path of the guide projection section  15   a  in the rear end portion of the guide section  19  in a state of being oriented obliquely upward toward the front side of the guide section  19 , the guide projection section  15   a  is moved along the tilt of the other end portion  23   b . As a result of this structure, the other end portion  23   b  can be easily displaced resiliently, whereby the guide projection section  15   a  favorably surmounts the other end portion  23   b.    
     Also, this keyboard lid opening and closing apparatus  20  includes the lock section  27  which engageably or disengageably locks the front end portion of the front lid  15  when the keyboard lid  14  is opened and the keyboard section  7  is exposed. As a result, when the keyboard lid  14  is opened to expose the keyboard section  7 , the front end portion of the front lid  15  is locked with the front lid  15  being held upright above the rear portion of the keyboard section  7 . As a result of this structure, the front lid  15  can be securely held upright above the rear portion of the keyboard section  7 . 
     In this embodiment, the lock section  27  includes the main body section  27   a  which is attached to the inner surface of the corresponding side plate  5  of the instrument case  1  and positioned behind the rear end portion of the corresponding guide section  19 , and the catch section  27   b  which is retractably provided in the main body section  27   a  and disengageably locks the corresponding guide projection section  15   a  of the front lid  15 . As a result of this structure, the guide projection section  15   a  of the front lid  15  can be locked by the catch section  27   b , whereby the front lid  15  can be securely held upright above the rear portion of the keyboard section  7 . 
     That is, this lock section  27  is structured such that, when the guide projection section  15   a  of the front lid  15  surmounts the other end portion  23   b  of the second braking section  23  and the keyboard lid  14  is opened to expose keyboard section  7 , the catch section  27   b  catches and locks the guide projection section  15   a  of the front lid  15 . As a result of this structure, the front lid  15  can be securely locked in a state of being held upright above the rear portion of the keyboard section  7 . 
     Also, this lock section  27  is structured such that, when the front lid  15  is to be moved frontward to close the keyboard lid  14  with the guide projection section  15   a  of the front lid  15  being caught and locked by the catch section  27   b , the lock of the guide projection section  15   a  of the front lid  15  by the catch section  27   b  is released by the front lid  15  being pushed once toward an area posterior to the keyboard section  7 . As a result of this structure, the guide projection section  15   a  of the front lid  15  can be easily released from the catch section  27   b  by a simple operation. 
     In the above-described second embodiment, as the energizing member which forces the front lid  15  and the rear lid  16  in the direction in which they come close to each other so that the keyboard lid  14  is mountain-folded, the spring member  21  constituted by a helical extension spring is used. However, the present invention is not limited thereto, and a torsion coil spring or an elastic wire rod such as an elastic cord may be used. 
     Also, in the above-described second embodiment, as the first and second braking sections  22  and  23  which brake the movement of the front end portion of the front lid  15 , the torsion coil springs are used. However, the present invention is not limited thereto, and elastic members, such as rubber or cushioning materials, may be used. 
     Moreover, in the above-described second embodiment, the lock section  27  includes the main body section  24   a  and the catch section  24   b , and the catch section  24   b  catches and locks the corresponding guide projection section  15   a  of the front lid  15 . However, the present invention is not limited thereto, and a structure may be adopted in which a magnet is used as the lock section  27 , and the guide projection section  15   a  of the front lid  15  is magnetically attached by this magnet. In this structure, the guide projection section  15   a  of the front lid  15  is formed of metal containing a magnetic material. 
     (Third Embodiment) 
     Next, a third embodiment in which the present invention has been applied in a keyboard instrument is described with reference to  FIG. 6 . Note that, in this case as well, sections identical to those of the first embodiment shown in  FIG. 1  and  FIG. 2  are provided with the same reference numerals. 
     The structure of this keyboard instrument is substantially the same as that of the first embodiment except that a first loudspeaker  31  and a second loudspeaker  32  are attached, as shown in  FIG. 6 . 
     The first loudspeaker  31  is a full-range speaker, and attached to the base plate  2  of the instrument case  1 , as shown in  FIG. 6 . That is, this first loudspeaker  31  is attached to a portion posterior to the keyboard section  7 , or more specifically, a portion of the undersurface of the base plate  2  below the action mechanism section  10 , in a state of being oriented upward. In this embodiment, a through hole  2   a  for sound emission is provided in the base plate  2 , corresponding to this first loudspeaker  31 . 
     In addition, a loudspeaker box  33  for housing the first loudspeaker  31  is attached to the undersurface of this base plate  2 , as shown in  FIG. 6 . As a result, the first loudspeaker  31  is structured such that high-pitched sounds are emitted toward the inside of the instrument case  1  through the through hole  2   a  of the base plate  2 , and low-pitched sounds are emitted toward the lower side of the instrument case  1  from the loudspeaker box  33 . 
     The second loudspeaker  32  is a tweeter or a woofer, and attached to the inner surface of the upper front plate  12   b  of the partition member  12  that is a partition between the keyboard section  7  and the action mechanism section  10 , as shown in  FIG. 6 . Specifically, the second loudspeaker  32  is attached in a state of being oriented obliquely upward toward the front side by an attachment plate  32   a , and positioned above the front portion of the action mechanism section  10  inside the instrument case  1 . 
     In this embodiment, a first sound hole  34  is provided in a portion of the upper front plate  12   b  of the partition member  12  in an area anterior and superior to the second loudspeaker  32 , as shown in  FIG. 6 . This first sound hole  34  is structured such that its upper portion is positioned above the upper portion of the standing keyboard lid  14  when the keyboard lid  14  is mountain-folded and held upright above the rear portion of the keyboard section  7 . 
     As a result, the first sound hole  34  is structured such that high-pitched sounds emitted toward the inside of the instrument case  1  from the first loudspeaker  31  and passed by the action mechanism section  10  are emitted to the outside of the front side of the instrument case  1 , and sounds emitted from the second loudspeaker  32  are directly emitted to the outside of the front side of the instrument case  1 , as shown in  FIG. 6 . 
     Also, in the area of the rear portion of the top plate  6 , the sound emission lid  6   a  is openably and closably provided as in the case of the first embodiment , and the auxiliary top plate  9  is provided below this sound emission lid  6   a . In this auxiliary top plate  9 , the sound hole  9   a  (referred to as the second sound hole  9   a  in this third embodiment) is provided penetrating through the auxiliary top plate  9  in the vertical direction. In this embodiment, the second sound emission lid  6   a  is structured such that its rear end portion is rotatably attached to the upper end portion of the rear plate  4  by the hinge  6   b , and vertically rotated around the hinge  6   b  so that the second sound hole  9   a  of the auxiliary top plate  9  is exposed or covered. 
     As a result, the second sound hole  9   a  is structured such that it is exposed when the sound emission lid  6   a  is vertically rotated and tilted obliquely upward, and high-pitched sounds emitted toward the inside of the instrument case  1  from the first loudspeaker  31  and passed by the action mechanism section  10  are emitted above the instrument case  1  and reflected by the sound emission lid  6   a  toward an area anterior to the instrument case  1 , as shown in  FIG. 6 . 
     By this keyboard instrument as well, operations and effects similar to those of the first embodiment can be provided. In addition, when a musical performance is performed by the plurality of keys  8  of the keyboard section  7  being depressed with the keyboard lid  14  being folded and held upright above the rear portion of keyboard section  7 , musical sounds in accordance with the musical performance are favorably generated by the first loudspeaker  31  and the second loudspeaker  32 . 
     With this keyboard instrument, low-pitched sounds among musical sounds generated in the first loudspeaker  31  can be favorably emitted toward an area inferior to the instrument case  1  from the loudspeaker box  33 . Also, with this keyboard instrument, high-pitched sounds among musical sounds generated in the first loudspeaker  31  can be unfailingly emitted toward the inside of the instrument case  1  from the through hole  2   a  of the base plate  2 , and the high-pitched sound emitted toward the inside of the instrument case  1  can be favorably emitted toward an area anterior to the instrument case  1  from the first sound hole  34  provided in the upper front plate  12   b  of the partition member  12 . 
     That is, with this keyboard instrument, high-pitched sounds emitted toward the inside of the instrument case  1  from the first loudspeaker  31  pass by the action mechanism section  10 . Then, these high-pitched sounds are emitted toward the front side of the instrument case  1  from the first sound hole  34  provided in the upper front plate  12   b  of the partition member  12 , and then favorably emitted toward an area anterior to the instrument case  1  through an area between the standing keyboard lid  14  and the top plates  6 . 
     In this embodiment, when the sound emission lid  6   a  of the top plate  6  is opened and the second sound hole  9   a  is exposed, high-pitched sounds generated in the first loudspeaker  31  and emitted toward the inside of the instrument case  1  pass by the action mechanism section  10  and are emitted toward an area anterior to the instrument case  1  from the first sound hole  34 , while at the same time portions of the high-pitched sounds are emitted above the instrument case  1  from the second sound hole  9   a , and favorably reflected by the sound emission lid  6   a  toward an area anterior to the instrument case  1 . 
     Also, with this keyboard instrument, musical sounds generated in the second loudspeaker  32  are emitted toward the front side of the instrument case  1  from the first sound hole  34  of the upper front plate  12   b  of the partition member  12 , and then favorably emitted toward an area anterior to the instrument case  1  through an area between the standing keyboard lid  14  and the top plates  6 . As a result of this structure, with this keyboard instrument, musical sounds generated in the first loudspeaker  31  and the second loudspeaker  32  can be favorably emitted toward an area anterior to the instrument case  1 . 
     Note that the above-described third embodiment may be structured to include the spring member  21  which forces the front lid  15  and the rear lid  16  in their folding directions, the first and second braking sections  22  and  23  which brake the movement of the front end portion of the front lid  15 , and the lock section  27  which locks the corresponding guide projection section  15   a  of the front lid  15 , as in the case of the second embodiment. 
     Also, in the third embodiment, the first loudspeaker  31  is upwardly provided on the undersurface of the base plate  2  of the instrument case  1 . However, the present invention is not limited thereto, and the first loudspeaker  31  may be downwardly provided on the undersurface of the base plate  2 . Also, the first loudspeaker  31  may be provided inside the instrument case  1 . In this case, the first loudspeaker  31  may be upwardly or downwardly provided on the upper surface of the base plate  2  inside the instrument case  1 , or may be upwardly or downwardly provided on the undersurface of the top plate  6  inside the instrument case  1 . 
     Moreover, in each of the first to third embodiments, the action mechanism section  10  is provided inside the instrument case  1  and positioned behind the keyboard section  7 . However, the present invention is not limited thereto, and a structure may be adopted in which a hammer member that applies an action load is provided for each of the plurality of keys  8  of the keyboard section  7 . Also, the action mechanism section  10  and the hammer members are not necessarily required to be provided. 
     In the above-described first to third embodiments, the keyboard lid  14  covers the keyboard section  7  with the front lid  15  and the rear lid  16  being slightly tilted by the coupling member  17  by mountain folding. This is because, in this way, the keyboard lid  14  can be easily folded only by being pushed upward, which improves operability related to the opening of the keyboard lid  14 . However, a structure may be adopted in which the keyboard lid  14  covers the keyboard section  7  with the front lid  15  and the rear lid  16  being flush with each other. 
     However, in this structure where the front lid  15  and the rear lid  16  are flush with each other, there is a possibility that the keyboard lid  14  is not easily opened as compared to the structure where the front lid  15  and the rear lid  16  are tilted. Therefore, a spring or the like may be provided between the rear end portion of the front lid  15  and the front end portion of the rear lid  16  so as to assist the instrument player in pushing the keyboard lid  14  upward. 
     Also, a structure where a music stand  15   b  is provided on the surface of the front plate  15  may be adopted, as shown in  FIG. 7 . By placing a musical score on the music stand  15   b  with the keyboard section  7  being exposed and the front lid  15  being held substantially upright above the rear end portion of the keyboard section  7 , the instrument player can put the musical score at the center of his or her sight. 
     Moreover, although each rotary fulcrum section  18  is constituted by the shaft section  18   a  and the bearing section  18   b  in the above-described first to third embodiments, the present invention is not limited thereto, and a structure may be adopted in which the rotary fulcrum section  18  is provided with a damper mechanism that applies a load to the closing movement of the keyboard lid  14  when it is closed to cover the keyboard section  7 . 
     While the present invention has been described with reference to the preferred embodiments, it is intended that the invention be not limited by any of the details of the description therein but includes all the embodiments which fall within the scope of the appended claims.