Abstract:
A chair for a drummer of the present invention is height-adjustable, thus the chair is suitable for users with different body sizes. The chair can be fastened by pivoting a swaying member rather than screwing a threaded element. As such, the chair is durable and the chair can be easily operated.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a chair, more particularly to a drummer&#39;s chair. 
         [0003]    2. Description of the Prior Art 
         [0004]    Drummer&#39;s chairs are provided for drummers. These chairs are usually height-adjustable, just as the chair shown in U.S. Pat. No. 5,738,326. The chair mainly includes a threaded stem and a clamping device. The clamping device surrounds the threaded stem. The clamping device may secure the threaded stem with a screw and a nut. To avoid sliding of the threaded stem, users usually firmly secure the nut with a very strong force. The force may probably destroy the thread of the screw or the nut, especially when the height of the chair has been adjusted for many times. Thus, the life time of the chair is limited. 
         [0005]    The present invention is, therefore, arisen to obviate or at least mitigate the above mentioned disadvantages. 
       SUMMARY OF THE INVENTION 
       [0006]    The main object of the present invention is to provide a chair, which is height-adjustable and durable. 
         [0007]    To achieve the above and other objects, a chair for a drummer of the present invention includes a main rod, a pad, a first sleeve, a fixation element, a tube, a second sleeve and three racks. 
         [0008]    The main rod has a top end, a threaded section and a bottom end. The threaded section connects the top end to the bottom end. The pad is disposed on the top end. The pad is adapted for a drummer to sit thereon. The first sleeve has an inner surface. A through hole is defined in the inner surface. The main rod is received in the first sleeve. The first sleeve has three first pivoting portions. Each first pivoting portion defines a first pivoting axial. Each first pivoting axial is perpendicular to the longitudinal direction of the main rod. The fixation element comprises a clamping portion, a linking rod, an axial rod, a threaded piece and a swaying member. The clamping portion is disposed on the first sleeve in a rotational operative relationship. The clamping portion has a threaded clamping surface. A penetrating hole is defined in the clamping surface. The penetrating hole and the through hole are coaxial. The main rod is received in the penetrating hole. The penetrating hole mates with the threaded section. The clamping portion has a first abutting portion and a second abutting portion. An opening is defined between the first abutting portion and the second abutting portion. The opening extends from one end of the clamping portion to the other end of the clamping portion. The opening communicates with the penetrating hole and the surrounding. The first abutting portion is formed with a first axial hole. The second abutting portion is formed with a second axial hole. The axial holes are coaxial. The linking rod is received in the axial holes. The axial rod is perpendicularly disposed on one end of the linking rod. The threaded piece is screwed on the other end of the linking rod. The swaying member is disposed between the axial rod and the first abutting portion. The swaying member is rotatable about the axial rod. The abutting portions are located between the threaded piece and the swaying member. The swaying member has an arcuate surface facing the first abutting portion. A first pressing point, a second pressing point and a third pressing point are defined on the arcuate surface. The second pressing point is located between the first pressing point and the third pressing point. Each pressing point defines a pressing distance. Each pressing distance is a distance between the axial rod and its corresponding pressing point. The pressing distance of the second pressing point is greater than the pressing distances of the others. The pressing distance of the third pressing point is greater than the pressing distance of the first pressing point. The tube is firmly disposed on the first sleeve. The bottom end being received in the tube. The tube is slidably received in the second sleeve. The second sleeve has three second pivoting portions. Each second pivoting portion defines a second pivoting axial. Each second pivoting axial is perpendicular to the longitudinal direction of the main rod. Each rack comprises a supporting pole and a linkage. Each supporting pole is rotatably disposed on one of the first pivoting portions about its corresponding first pivoting axial. Each linkage has a first end and a second end. Each first end is rotatably disposed on one of the second pivoting portions about its corresponding second pivoting axial. Each second end is rotatably disposed on one of the supporting poles. 
         [0009]    The present invention will become more obvious from the following description when taken in connection with the accompanying drawings, which show, for purpose of illustrations only, the preferred embodiment(s) in accordance with the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a combination drawing showing a chair of the present invention; 
           [0011]      FIG. 2  is a combination drawing showing a chair of the present invention; 
           [0012]      FIG. 3  is a partial breakdown drawing showing a chair of the present invention; 
           [0013]      FIG. 4  is a breakdown drawing showing a fixation element of the present invention; 
           [0014]      FIG. 4A  is a profile showing a clamping portion of the present invention; 
           [0015]      FIG. 4B  is a stereogram showing a swaying member of the present invention; 
           [0016]      FIG. 5  is a profile showing a main rod and a fixation element of the present invention; 
           [0017]      FIG. 6  is a profile showing a main rod and a fixation element of the present invention; 
           [0018]      FIG. 7  is a profile showing a main rod and a fixation element of the present invention; 
           [0019]      FIG. 8  is a profile showing a main rod and a fixation element of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0020]    Please refer to  FIG. 1  to  FIG. 4  for a first embodiment of the present invention. The chair for a drummer to sitting thereon of the present embodiment is foldable and height-adjustable. The chair includes a main rod  1 , a pad  2 , a first sleeve  3 , a fixation element  4 , a tube  5 , a second sleeve  6  and three racks  7 . 
         [0021]    The main rod  1  has a top end  11 , a threaded section  12  and a bottom end  13 . The top end  11  is adapted for a pad to be disposed thereon. The threaded section  12  connects the top end  11  to the bottom end  13 . A radial direction is defined perpendicular to the main rod  1 . 
         [0022]    The pad  2  is disposed on the top end  11 . The pad  2  may be disposed on the top end  11  in a rotational operative relationship. The pad  2  is adapted for a drummer to sit there on. 
         [0023]    The first sleeve  3  has an inner surface  31 . A through hole is defined in the inner surface  31 . The main rod  1  is received in the first sleeve  3 . The inner surface may be threaded for the threaded section  12  to mate therewith. The first sleeve  3  is formed with three first pivoting holes  33 . Three first pivoting portions  32  are received in the first pivoting holes  33  respectively. Each first pivoting portion  32  may be a bolt or a rivet. Each first pivoting portion  32  defines a first pivoting axial in its longitudinal direction which is perpendicular to the longitudinal direction of the main rod  1 . In other possible embodiments of the invention, the first pivoting portions  32  may be formed on the first sleeve  3  directly. 
         [0024]    The fixation element  4  includes a clamping portion  41 , a linking rod  42 , an axial rod  43 , a swaying member  44  and a threaded piece  45 . The fixation element  4  may further include a spring  46 . The clamping portion  41  is disposed on the first sleeve  3  in a rotational operative relationship. Preferably, the clamping portion  41  may be directly formed on the first sleeve  3 . The clamping portion  41  has a threaded clamping surface  411 . A penetrating hole is defined in the clamping surface  411 . The main rod  1  is received in the penetrating hole, so that the penetrating hole and the through hole are coaxial. The penetrating hole mates with the threaded section  12 . The clamping portion  41  has a first abutting portion  413  and a second abutting portion  414 . An opening  412  is defined between the first abutting portion  413  and the second abutting portion  414 . The opening  412  extends from one end of the clamping portion  41  to the other end of the clamping portion  41 . The opening communicates with the penetrating hole and the surrounding. The first abutting portion  413  is formed with a first axial hole  415 . The second abutting portion  414  is formed with a second axial hole  416 . The first axial hole  415  and the second axial hole  416  are coaxial. The first axial hole  415  and the second axial hole  416  are perpendicular to the longitudinal direction of the main rod  1 . The first abutting portion  413  is formed with a slant surface  417  in the first axial hole  415 , as shown in  FIG. 4A . The slant surface  417  is located away from the main rod  1 . The first axial hole  415  has two ends. The first axial hole is enlarged gradually from the end which is near to the second axial hole to the other end. The second axial hole  416  has a large diameter section  4161  and a small diameter section  4162 . The small diameter section  4162  is located between the large diameter section  4161  and the first abutting portion  413 . The second abutting portion  414  has a step surface  418  between the large diameter section  4161  and the small diameter section  4162 . The first abutting portion  413  may be formed with an abutting groove  419 . The abutting groove  419  is located on the surface which is located away from the second abutting portion  414 . The longitudinal direction of the abutting groove  419  may be parallel to the longitudinal direction of the main rod  1 . Preferably, the abutting groove  419  can be a cylinder surface. 
         [0025]    The linking rod  42  is received in both of the axial holes  415 ,  416 . The width along the radial direction of each axial hole is greater than the diameter of the linking rod  42 , so that the linking rod  42  is movable along the radial direction. The axial rod  43  is perpendicularly disposed on one end  421  of the linking rod  42 . The threaded piece  45  is screwed on the other end  422  of the linking rod  42 . 
         [0026]    The swaying member  44  is disposed between the axial rod  43  and the first abutting portion  413 , so that the abutting portions  413 ,  414  are located between the swaying member  44  and the threaded piece  45 . The swaying member  44  is rotatable about the axial rod  43 . The swaying member  44  has an arcuate surface  441  facing the first abutting portion  413 , as shown in  FIG. 4B . The arcuate surface  441  abuts against the abutting groove  419 . Preferably, the arcuate surface  441  can be a cylinder surface. 
         [0027]    The distance between the axial rod  43  and the arcuate surface  441  is not uniform. Thus, a first pressing point, a second pressing point and a third pressing point can be defined on the arcuate surface  441 . Each pressing point defines a pressing distance between itself and the axial rod  43 . The second pressing point is located between the first pressing point and the third pressing point. The pressing distance of the second pressing point is greater than the pressing distances of the others. The pressing distance of the third pressing point is greater than the pressing distance of the first pressing point. 
         [0028]    The spring  46  is disposed between the threaded piece  45  and the second abutting portion  414 . Preferably, the spring  46  may be received in the large diameter section  4161 , and may abut against the step surface  418 . 
         [0029]    The tube  5  is firmly disposed on the first sleeve  3 . The bottom end  13  is received in the tube  5 . The main rod  1  is slidable and rotatable with respect to the tube  5 . The tube  5  may include a stretching section  51  and a stopping section  52 . The stretching section  51  connects the first sleeve  3  to the stopping section  52 . The outer diameter of the stopping section  52  is greater than the outer diameter of the stretching section  51 . 
         [0030]    The tube  5  is slidably received in the second sleeve  6 . More specifically, the stretching section  51  is slidably received in the second sleeve  6 . The stopping section  52  can block the second sleeve  6 , so that the second sleeve  6  can not depart from the tube  5 . The second sleeve  6  is formed with three second pivoting holes  62 . Three second pivoting portions  61  are received in the second pivoting holes  62  respectively. Each second pivoting portion  61  may be a bolt or a rivet. Each second pivoting portion  61  defines a second pivoting axial in its longitudinal direction which is perpendicular to the longitudinal direction of the main rod  1 . In other possible embodiments of the invention, the second pivoting portions  61  may be formed on the second sleeve  6  directly. The second sleeve  6  and the tube  5  may be secured by a screw  63 , so that the position of the second sleeve  6  is adjustable. 
         [0031]    Each rack  7  includes a supporting pole  71  and a linkage  72 . Each supporting pole  71  is disposed on one of the first pivoting portions  32 . Each supporting pole  71  is rotatable about its corresponding first pivoting axial. Each linkage  72  has a first end  721  and a second end  722 . Each first end  721  is disposed on one of the second pivoting portions  61 . Each first end  721  is rotatable about its corresponding second pivoting axial. Each second end  722  is rotatably disposed on one of the supporting poles  71 . 
         [0032]    Accordingly, the chair can be folded by moving the second sleeve  6 . Also, the height of the pad  2  is adjustable. The swaying member  44  and the threaded piece  45  can be release, as shown in  FIG. 5 . The main rod  1  is not clamped by the clamping portion  41 , so the distance between the top end  11  and the first sleeve  3  is changeable. After the distance is determined, the threaded piece  45  is softly secured, and the swaying member  44  is moved to a first position, as shown in  FIG. 6 . At the same time, the first pressing point abuts against the first abutting portion  413 . The swaying member  44  can be moved to a second position, as shown in  FIG. 7 . The second pressing point abuts against the first abutting portion  413 . The pressing distance of the second pressing point is greater than the same of the first pressing point. Thus, the swaying member  44  presses the first abutting portion  413 . The clamping portion  41  clamps the main rod  1  to prevent the main rod  1  from rotating or sliding. The swaying member  44  can be kept moving to a third position, as shown in  FIG. 8 . The third pressing point abuts against the first abutting portion  413 . The pressing distance of the third pressing point is greater than the pressing distance of the first pressing point, but smaller than the pressing distance of the second pressing point. As such, the swaying member  44  can still press the first abutting portion  413 . The swaying member  44  can not move to the second position or the first position without a pull. 
         [0033]    To conclude, the chair can be secured by rotating the swaying member  44  rather than screwing a threaded element.