Patent Publication Number: US-7718877-B2

Title: Device and musical instrument

Description:
BACKGROUND OF THE INVENTION 
   Field of the Invention 
   The invention relates to a device for setting skin tension, in particular for use in a musical instrument such as a kettledrum, comprising a tensioning star provided with an engaging element for engaging an operating mechanism for adjusting the tensioning star in an axial adjusting direction, substantially parallel to a central axis of the tensioning star, and provided with a plurality of arms extending substantially in radial directions, of which at least a part is provided with a coupling element for coupling to a tensioning rod construction attachable to the skin. 
   Such a device is known from practice, as part of, for instance, a commercially available kettledrum. 
   SUMMARY OF THE INVENTION 
   The object of the invention is a device according to a type mentioned in the opening paragraph, with which the skin tension can be set independently of a pedal provided on the operating mechanism. To that end, according to the invention, the device further comprises an adjusting device for adjusting the distance between a coupling element and the central axis of the tensioning star. 
   Using an adjusting device for adjusting the distance between coupling element and the central axis of the tensioning star allows for the skin tension to be set independently of the operating mechanism for adjusting the tensioning star in axial direction. Here, the balance between the operating mechanism and the tensioning star is maintained. Thus, the skin tension can be regulated independently of a position of the operating mechanism, so that a user/player can work with standard positions of the operating mechanism, which, in an advantageous manner, can increase the ease of use and/or the player comfort to a considerable extent. 
   In an advantageous embodiment according to the invention, the operating device comprises a first connecting rod which engages with a first end the engaging element of the tensioning star, further a second connecting rod which is attached by a first end to a coupling module which is couplable to a second end of the first connecting rod, while the coupling module comprises a clamping construction which is designed for a clamping coupling to the first connecting rod within a predetermined adjustment range in the axial adjusting direction, between a minimum distance and a maximum distance relative to the skin, and which is designed for releasing the clamping coupling when, through an adjustment of the second connecting rod, the distance between the first connecting rod and the skin becomes smaller than the minimum distance of the adjustment range. 
   As a result, a coupling is obtained between parts of the operating mechanism which can be disassembled relatively simply so that the device can be modularly transported and built up by a user/player. Naturally, the device can also be realized without such a coupling, for instance for obtaining a less expensive construction. 
   In an advantageous embodiment according to the invention, the operating device further comprises a hingedly arranged coupling piece which is coupled to the second connecting rod, to an operating rod attached to a pivotal pedal, and to a biased spring element, with the operating rod oriented substantially transversely to the axial adjusting direction, while the force provided by the biased spring element is oriented from the coupling piece in a direction between the tensioning star and the pedal. Thus, in an elegant manner, a force equilibrium can be obtained between the pedal and the force provided by the skin on the operating mechanism, over a practically usable range of the pedal. 
   The invention further relates to a musical instrument. 
   Further advantageous embodiments of the invention are represented in the subclaims. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be explained in further detail on the basis of exemplary embodiments which are represented in the drawing. In the drawing: 
       FIG. 1  shows a schematic side view of a kettledrum according to the invention; 
       FIG. 2  shows a schematic view of a cross section of the kettledrum of  FIG. 1 ; 
       FIG. 3  shows a schematic perspective view of a tensioning star of the kettledrum of  FIG. 1 ; 
       FIG. 4  shows a schematic side view of the tensioning star as shown in  FIG. 3 ; and 
       FIG. 5  shows a schematic view of a cross section of a coupling module of the kettledrum of  FIG. 1 . 
   

   The Figures are only a schematic representation of a preferred embodiment of the invention. In the Figures, identical or corresponding parts are indicated with the same reference numerals. 
     FIGS. 1 and 2  show a schematic side view and a schematic view, respectively, of a cross section of a kettledrum  100  according to the invention. 
   DETAILED DESCRIPTION 
   The kettledrum  100  comprises a kettle  4  which is borne by a foot  9 . The kettle  4  is manufactured from metal and serves as a sound box. Over the kettle  4  a skin  101  is stretched with the aid of a tensioning ring  1  which is provided adjacent the top edge of the kettle  2 . With the aid of tensioning nuts  102  and tensioning rods  2  connected thereto, the tensioning ring  1  is drawn downwards so that the skin  101  is tensioned. The tensioning rods  2  comprise an upper rod  28  and lower rod  27  hinged thereto. The tensioning rods  2  extend partly along the outside of the kettle  4 , reach via a support  3  and an opening  103  located nearby into the kettle  4  and are coupled via coupling elements to a tensioning star  19  described hereinbelow in more detail. Through adjustment of the tensioning nuts  102 , the effective length of the tensioning rods  2  can be set such that between the tensioning nuts  102  and the tensioning star  19 , the tensioning rods  2  have the same length within a particular accuracy, so that the tensioning star  10  extends at least substantially horizontally. The construction of tensioning rods  2 , including the upper rod  28  and lower rod  27 , the tensioning nuts  102  and the tensioning ring  1  forms a tensioning rod construction for tensioning the skin  101 . 
   The tension in the skin  101  can be adjusted by moving the tensioning ring  19  in an adjusting direction oriented substantially horizontally. The fact is that by moving the tensioning star  19  in the adjusting direction, via the tensioning rods of the tensioning rod construction, also, the tension ring  1  moves in the adjusting direction, so that the skin  101  is pulled tauter or less taut depending on the direction of movement of the tensioning star  19 . The fact is that this movement induces a movement of the tensioning brackets. By playing a tensioned skin, a low-noise, consonant tone can be generated. 
     FIGS. 3 and 4  shows a schematic perspective view and a schematic side view, respectively, of a tensioning star  19 . The tensioning star  19  is present in the kettle  4  such that the central axis H of the tensioning star  19  and the central axis K of the kettle  4  substantially coincide. The tensioning star  19  is further provided with an engaging element  43 , designed as a bolt, for engaging an operating mechanism for adjusting the tensioning star  19  in an axial adjusting direction A, substantially parallel to a central axis H of the tensioning star  19 . The tensioning star  19  is also provided with a plurality of arms  31   a ,  31   b ,  31   c , extending substantially in radial directions R 1 , R 2 , R 3 , which are all provided with a coupling element  30   a ,  30   b ,  30   c  for coupling to the tensioning rod construction attached to the skin  101 . Further, an adjusting device is shown for adjusting the distance between coupling element  30   a ,  30   b ,  30   c  and the central axis H of the tensioning star  19 . 
   The coupling elements  20   a ,  30   b ,  30   c  each comprise a shaft  38  which is guidingly received in a slide bearing  32 , preferably made in bronze which allows an axial adjustment in the substantially axial direction R 1 , R 2 , R 3  relative to the central axis H of the tensioning star  19 . Transversely to the axis  38 , a projecting element  38   a  is attached which, via an opening  38   b , reaches outwards into the slide bearing  32  and bears a tiltable equalizer element  40 , also called tensioning plate, of which both ends are designed for coupling to a respective tensioning rod  2  of the tensioning rod construction. To that end, the ends mentioned are provided with openings  40   a ,  40   b  in which the tensioning rods  2  can hook. Through the use of an equalizer construction, any differences in tensile force between the tensioning rods  2  attached to the coupling element are equalized so that an equal tensile force in circumferential direction is obtained. However, it is also possible to design the coupling elements differently, for instance with a rigid coupling construction to the tensioning rods. 
   A central, annular part  19   a  of the tensioning star  19  forms, together with the arms  31 ,  31   b ,  31   c  an integral tensioning star, preferably formed as a casting piece. Naturally, the annular part  19   a  and the arms can also be designed differently, for instance as separate elements which are coupled to each other with the aid of a connecting technique. 
   The adjusting device comprises a disc  36 , arranged centrally relative to the central axis H of the tensioning star and pivotal about the central axis H, and a number of crankshafts  39   a ,  39   b ,  39   c  pivotally attached to the disc  36  such that the crankshafts are pivotally attached by a first end via a bolt connection  42  to the disc  36  and are connected, by an opposite second end, to a coupling element  30   a ,  30   b ,  30   c  respectively, of an arm  31   a ,  31   b ,  31   c . By pivoting the disc  36  around the central axis H of the tensioning star  19 , the two ends of the crankshafts  39   a ,  39   b ,  39   c  and hence also the coupling elements move away from the central axis H of the tensioning star  19 . As the coupling elements move via the tensioning rod construction, the tension in the skin  102  of the kettledrum  100  changes too. Thus, the skin tension of the skin  102  can be set with the aid of the adjusting device, independently of a position of the operating mechanism for adjusting the tensioning star  19  in an axial adjusting direction A, and without adjusting the operating mechanism. The balance with the pedal described hereinafter remains unadjusted. 
   The disc  36  is accommodated in the annular part  19   a  of the tensioning star. Further, the crankshafts  39   a ,  39   b ,  39   c  reach through the hollow arms  31 ,  31   b ,  31   c  of the tensioning star  19  so that a compact construction is obtained. The annular part of the tensioning star  19  is covered with the aid of a covering plate  35 . 
     FIGS. 3 and 4  further show an operating element which is provided with a worm  37   b  which cooperates with the disc  36  designed as worm wheel. To that end, the disc  36  is provided with a toothing  36   a  provided on the radial outer edge. The worm  37   b  is borne by an operating shaft  37   a  which is rotatable via guide elements  38 , preferably designed in bronze. A first end of the operating shaft  37   a  is located, together with the worm  37   b , in a housing  34   a  covered by a covering plate  34   b . A second end of the operating shaft  37   a  located opposite the first end reaches through an opening of the kettle  4  and is provided with a handle for enabling operation of the adjusting device. Upon pivoting of the operating shaft  37   a , the worm  38   b  drives the worm wheel  36 , so that the distance between the coupling elements  30 ,  30   b ,  30   c  and the central axis H of the tensioning star  19  varies. Through the use of a worm wheel construction, in an advantageous manner, a particularly compact construction is obtained while furthermore, a particularly accurate setting of the skin tension of the skin  101  can be obtained. 
   Thus, the adjusting device is designed for adjusting, preferably simultaneously, the coupling elements  30   a ,  30   b ,  30   c  of a plurality of arms  31   a ,  31   b ,  31   c  so that a tension variation of the skin  101  is realized substantially uniformly over the circumferential direction. However, alternatively, the adjusting device can be designed for separately adjusting the distance between coupling element and central axis H of the tensioning star, so that a specific tensioning rod can be adjusted. The described adjusting device effects an adjustment of the coupling elements in a substantially radial direction relative to the tensioning star. However, in principle, it is also possible to design the tensioning rod construction such that the adjusting device realizes an axial adjustment, virtually parallel to the axial adjusting direction A, for instance when the lower rods  27  run substantially parallel to the axial adjusting direction A. 
   In another embodiment, the adjusting device segment designed differently, optionally without pivotal disc and/or worm, but with, for instance, a slide mechanism. 
   Together with the adjusting device, the tensioning star  19  forms a device according to the invention for setting skin tension. It is noted that all sorts of variations are possible. For instance, in another embodiment according to the invention, not all arms are provided with a coupling element for coupling to the tensioning rod construction. One of the arms can for instance be designed without coupling element when the number of tensioning rods of the tensioning rod construction is smaller than the number of arms of the tensioning star  19 . In the embodiment shown, the tensioning rod construction comprises six tensioning rods  2 ,  28 ,  27  which are evenly distributed in circumferential direction. However, the tensioning rod construction can also comprise a different number of tensioning rods, for instance eight tensioning rods. 
   The lower segment  26  of the kettle  4  is borne by supporting elements  25  which are attached to the upper part  25   a  of a supporting column  25   b . Via a threaded spindle construction  15 , the supporting column  25   b  bears on the foot  9 . The foot  9  is provided with two pivotal bearing arms  10  each equipped with a wheel  5  so that the kettledrum can easily be displaced but can also be stably set down. The foot  9  further comprises a hinged pedal  8  with which a player can set the pitch of the kettledrum. The pedal  8  forms part of the operating mechanism for adjusting the tensioning star in axial adjusting direction. For forming the threaded spindle construction  15 , the bearing column  25   b  is provided with external screw thread which corresponds to internal screw thread in a receiving cavity of the foot  9 . By rotating the foot  9  about the bearing column  25   b , the height of the kettle  4  can be set so that the kettledrum can be played in an ergonomic manner by a player of any length. 
   The operating mechanism for adjusting the tensioning star  19  in axial adjusting direction A comprises a first connecting rod  18  engaging by a first upper end the engaging element  43  of the tensioning star  19 . The operating mechanism further comprises a second connecting rod  16  attached by a first upper end to a coupling module  17  which is couplable to a second, lower end of the first connecting rod  18  reaching downwards through an opening at the underside of the kettle  4 . The second connecting rod  16  comprises two segments  16 ,  18  mutually connected via an additional screw spindle  25   c . The lower segment  18  of the second connecting rod is hingedly attached to a coupling piece  13 , which is hinged to the foot  9 . Through the use of the additional screw spindle  25   c , the height of the kettle  4  can be set, independently of the balance between the pedal  8  and the tensioning star  19 . The operating mechanism further comprises a pedal connecting rod  11  which is arranged between the coupling piece  13  and the pedal. The operating mechanism also comprises a biased spring element arranged in a bushing  23 , of which an engaging point  21  is also connected to the coupling piece  13 . Here, the bushing is rigidly attached to the foot  9 . The bias of the spring element  22  is adjustable with the aid of a rotatable handle  24 . 
   By tilting the pedal  8 , the pedal connecting rod  11  adjusts and hence, via the coupling piece  13  functioning as tumbler element, also both segments  14 ,  16  of the second operating rod, and the first operating rod  18  adjust in the axial adjusting direction A. As a result, the tensioning star  19  too will adjust in axial adjusting direction. Then, by means of the tensioning rod construction, the tension of the skin is varied. As the spring element  22  too engages the coupling piece  13 , a balance of forces is formed, dimensioned such that the pedal remains in any arbitrary position, also without application of a static force thereto. 
   The coupling module  17  comprises a hollow block  59  rotatably included in the supporting column  25   b  and attached to the second operating rod  16 . The coupling module  17  further comprises a first substantially cylindrical body  51  with a bore in which a spring element  58  is provided. The first cylindrical body  51  is rigidly attached to the block  59  via a bolt connection and substantially horizontal bores  54 ,  60  provided with internal screw thread in the body  51  and the block  59 . The coupling module also comprises a second substantially cylindrical body  53  provided with a continuous bore with varying diameter. The lower part of the bore accommodates the spring element  58 , while the upper part of the bore tapers upwards and outwards for accommodating the second end  57  of the first connecting rod  18 . The second substantially cylindrical body  53  is further provided with a clamping construction for clampingly coupling the second end  57  of the first connecting rod  18 . The coupling module  17  also comprises a sleeve  55  which surrounds the second substantially cylindrical body  53 . 
   The clamping construction of the coupling module  17  is designed for a clamping coupling on the first connecting rod within a predetermined range of adjustment of the first connecting rod in the axial adjusting direction A, between a minimum distance and a maximum distance relative to the skin, and for releasing the clamping coupling when, through an adjustment of the second connecting rod  16 , the distance between the first connecting rod  18  and the skin becomes smaller than the minimum distance of the range of adjustment. 
   To that end, the clamping construction comprises a series of balls  56  arranged in circumferential direction around the second cylindrical body  53  for a radially inwards clamping engagement of the second end  57  of the first connecting rod  18 , further comprising a ring  52  slideable in axial adjusting direction A for radially confining the balls  56  under a bias, while the ring  52  is provided in axial direction A with a tapering inner profile  50 , while the tapering part  61  of the ring  52  is pressed, in the predetermined range of adjustment of the first connecting rod  18 , under spring action, towards the balls  56  with the ring  52  designed to adjust away from the balls  56  with the tapering part  61  of the inner profile  50  when the distance between the first connecting rod  18  and the skin becomes smaller than the minimum distance of the range of adjustment. The slideable ring  52  in manufactured substantially from a resilient material. 
   During use of the kettledrum  100 , the balls  56  are pressed inwards under spring action of the ring  52 , to clampingly engage the end  57  of the first connecting rod  18 . As a result, the first and second connecting rod  16 ,  18  are coupled to each other. Here, the first connecting rod  16  is height variable in the range of adjustment, so that the kettledrum can be operated normally. 
   When uncoupling the kettle  4 , the second connecting rod  16 , including the coupling module  17 , is pressed upwards relatively far, so far that the distance between the first connecting rod  18  and the skin becomes smaller than a predetermined minimum marginal value of the range of adjustment. Here, the pedal  8  is brought into an extreme rearward position. With the coupling module  17  in the high position, an element of the foot pushes the second cylindrical body  53  downwards, against spring action, so that the ring  52  relative to the body  53  moves away from the spring, whereby the force applied by the ring to the balls  56  is reduced and even disappears, yet with the balls remaining between the ring  52  and the body. As a result, the clamping action of the balls is released. The kettle  4  can then be disassembled. 
   When assembling the kettle  4 , the procedure takes place in reverse order. When forcing the second connecting rod  16  downwards from the high position of the coupling module  17 , the ring  52  moves under spring action relative to the second cylindrical body  53 , so that the balls  56  are confined and clampingly engage the second end of the first connecting rod. 
   Through the use of the above-described coupling module  17 , the kettle  4  can be relatively simply be separated from the foot, while still, during use of the kettledrum, the operating mechanism is not hindered. 
   The operating rod  11  is oriented substantially transversely relative to the axial adjusting direction A. Further, the force provided by the biased spring element  22  is oriented from the coupling piece  13  in a direction between the tensioning star  19  and the pedal  8 . As a result, the pedal can be held in balance in various positions. It appears to be preferred here that the direction of the force provided by the spring element makes a smaller angle with the axial adjusting direction A than with the orientation of the operating rod  11 . 
   The operating rod  11  further comprises two spring elements which cooperate with stops mounted on the inside of the foot  9 . Here, a first spring  12   a  enters into operation when the pedal  8  is tilted so far that the coupling module  19  starts releasing the second end of the first connecting rod  18 . Then, a second spring  12   b  enters into operation when the uncoupling actually starts, to prevent an undesired adjustment by unbalance of the pedal  8 . 
   After disassembly of the kettle  4 , the pivotal arms  10  can be pivoted in the direction of the foot  9 , so that the dimensions of the foot as a whole decrease even further. Optionally, the wheels  5  are designed as castor wheels and, with the arms  10  in collapsed condition, are collapsible, which effects a still further reduction of the foot as a whole. Further, the foot can be provided with a grip, so that the whole can easily be transported by hand. The grip can be of stationary design, such as a fixed grip, or in another manner, for instance as a telescopic grip, such as with a trolley, so that the foot can easily be lifted on one side and be rolled forward with the aid of the castors. 
   Upon assembly of the kettledrum  100 , the arms  10  are folded out and the kettle  4  is set on the supporting elements  25 , whereupon the lower end  57  of the first connecting rod  18  is attached to the coupling module  17  as described hereinabove. The supporting elements  25  are rigidly attached to the top part  25   a  of the supporting column  25   b . The underside of the kettle  4  is provided with clamping elements  26  having a shape matching the supporting elements  25  so that the kettle can find the position relative to the foot  89  in a self-seeking manner. The supporting column further comprises a clamping disc with an internal thread profile which cooperates with the outer thread profile of the upper part  25   a  of the supporting column  25   b . The clamping disc is provided with upstanding clamping elements (not shown) which reach through slot-shaped openings  61   a ,  62   b  of the supporting elements  25  and the profile elements  26  of the kettle. By pivoting the clamping disc relative to the supporting elements  25  and the profile elements  26 , a strong coupling is effected between the kettle and the foot. To this end, the thread profile of the upper part of the supporting column  25   b  has a relatively great pitch. 
   As the described kettledrum is designed so it can be disassembled, it is highly suitable for transport in compact modules. Owing to the easy to adjust height of the kettle, the kettledrum is also, in principle, suitable for users of different lengths. 
   The invention is not limited to the exemplary embodiments described here. Many variants are possible. 
   For instance, all sorts of adaptations can be realized with regard to form and design of, for instance, the kettle, the coupling between the tensioning star and the skin etc. The coupling between the kettle and the foot can also be designed differently. 
   In addition, a device for setting skin tension can be of multiple design, for a plurality of skins to be tensioned. 
   Also, such a device can be utilized with a percussion instrument or for instance in measuring equipment where use is made of tensioned skins. 
   Further, slide bearings and/or bearing bushes can be manufactured not only from bronze but also from other materials, for instance from specific raw materials. Such variants will be clear to the skilled person and are understood to fall within the scope of the invention, as set forth in the following claims.