Patent Publication Number: US-7717375-B2

Title: Rotation control device for support arm of a lamp

Description:
FIELD OF THE INVENTION 
   The present invention relates to lamps, in particular to a rotation control device for a support arm of a lamp, wherein the support arm is adjusted to a desired angle for providing a desired illumination, while the support arm can be retained firmly. 
   BACKGROUND OF THE INVENTION 
   Generally, an angle adjustable lamp has a support arm and a rotating arm. The support arm is assembled to a seat which can be seated upon a table surfaces or a platform so as to form as a stand lamp. The support arm can be directly to a wall to form as a suspending lamp. The support arm may be assembled with a lamp head which has a lamp and a lampshade. Moreover, the support arm is pivoted to the rotating arm so that the rotating arm is rotatable with respect to the support arm so as to control the angle of the lamp head. It should be noted that for retaining the rotating arm to a predetermined angle, as illustrated in  FIG. 7 , a prior art lamp has a rubber pad  3  installed between the support arm  1  and the rotating arm  2 . A stud  4  serves to lock it so that the rubber pad  3  has the effect of slide stop to prevent that after adjustment of the angle, the rotating arm  2  will loose. 
   However although the rubber pad  2  has the effect of slide stop, but since the structural design will cause another end of the rotating arm  2  will suffer from a gravitation force so as to convert into a twisting torque to be applied to rubber pad  3  so that the pad  3  must suffer from the twisting torque. The rubber pad  3  is made of rubber. The rubber is easy to weaken as it is used for a longer time and thus deforms. Therefore, after the rubber pad  3  is used for a long time, the slide stop effect is reduced. The lamp cannot be steadily supported and fixed so as to shift and swing. As a result, the lamp cannot be steadily retained to an original position with a desired illumination. 
   SUMMARY OF THE INVENTION 
   Accordingly, the object of the present invention is to provide a rotation control device for a support arm of a lamp, wherein the support arm is adjusted to a desired angle for providing a desired illumination, while the support arm can be retained firmly. 
   To achieve above object, the present invention provides a rotation control device for a support arm of a lamp, comprising; a support arm having a first end and a second end; a rotating arm having a first end and a second end; a lamp head assembled to the second end of the rotating arm; a cambered track fixed to a predetermined position of the support arm; and a cambered slot being formed in the cambered track; a stop sheet installed to a predetermined position of the cambered track; the stop sheet being movable along the cambered slot of the cambered track and is fixable at a predetermined position so that the rotating arm is retained to a predetermined angle. 
   A threaded rotating button screwed to the rotating arm for tightening the rotating arm to a respective portion of the cambered track. 
   The stop sheet has a pressing surface and the cambered track has a pressed surfaces; and the pressing surface is capable of pressing the pressed surface. 
   The stop sheet is a pullable rod capable of tightening the rotating arm and capable of buckling to a respective portion of the cambered track. 
   The second end of the support arm and the first end of the rotating arm is pivotally connected so as to be as a rotation fulcrum; a compressible spring is connected therebetween so as to provide a predetermined rotating pressure to the fulcrum. 
   The cambered track and support arm are retained through two points. 
   A threaded stud and a shaft stud is used to retain the cambered track to the support arm at the two points. 
   A first end of the support arm has a base. 
   A first end of the support arm is directly fixed to a position wall. 
   A pivot head is assembled to a lamp head which is pivoted to the second end of the rotating arm so as to form as a rotation fulcrum. 
   The rotation control device for a support arm of a lamp of the present invention uses a cambered track installed to the support arm with the stop sheet in the cambered track so as to form as a lever fulcrum. Thus a steady and firm support structure is provided to the support arm so that the support arm can be retained to a predetermined angle as a gravitation force is applied thereto for a longer time. Thus the lamp can provide a proper illumination. In the prior art, the rotating arm will loose as it is used for a time period. Next, the present invention has a simple structure and the cost in assembly is low. In operation, it is only necessary to tighten or release the stop sheet, the rotating arm can be adjusted to a predetermined angle rapidly. Thereby, the operation of the present invention is easy and conveniently and is a personal design. 
   The various objects and advantages of the present invention will be more readily understood from the following detailed description when read in conjunction with the appended drawing. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an assembled perspective view of the present invention. 
       FIG. 2  is a partial enlarged view about the cambered track and the stop sheet of the cambered track in the present invention. 
       FIG. 3  is an exploded perspective view showing that the lamp is near the stop sheet of the cambered track according to the present invention. 
       FIG. 4  is a schematic view showing the angle adjustment of the rotating arm and the lamp head according to the present invention. 
       FIG. 5  is a partial lateral cross sectional view showing the relation of the stop sheet and the cambered track according to the present invention. 
       FIG. 6  is a schematic view showing the operation of adjusting the angle of the rotating arm and the lamp head. 
       FIG. 7  is a schematic view showing the pivot connection of a prior art lamp. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   In order that those skilled in the art can further understand the present invention, a description will be provided in the following in details. However, these descriptions and the appended drawings are only used to cause those skilled in the art to understand the objects, features, and characteristics of the present invention, but not to be used to confine the scope and spirit of the present invention defined in the appended claims. 
   With reference to  FIGS. 1 ,  2  and  3 , the rotation control device for a support arm of a lamp according to the present invention is illustrated. The device includes a support arm  10 , a rotating arm  20 , a lamp head  30 , a base  40 , a cambered track  50 , and a stop sheet. 
   The support arm  10  has a first end  11  and a second end  12 . In the present invention, the support arm  10  is formed by a tube body  13 , a headless stud  15 , and a pivot head  16 . One free end of the tube body  13  is formed as the first end  11 . One free end of the pivot head  16  is formed with the second end  12 . The free end of the pivot head  16  is formed with a pivot portion  161 . An outer surface of the tube joint  14  is extended with a protrusion  141 . The protrusion  141  is installed with a threaded hole  142  and a stud hole  143 . 
   The rotating arm  20  has a first end  21  and a second end  22 . The rotating arm  20  includes a tube body  23 . A tube body  23  of the rotating arm  20  is sequentially arranged with a tube joint  24 , a headless stud  25  and a pivot head  26  corresponding to the support arm  10 . One end of the rotating arm  20  is arranged with a pivot head  27 . A free end of the pivot head  26  and a free end of the pivot head  27  are formed with the first end  21  and the second end  22 , respectively. The free end of the pivot head  26  is formed with a pivot portion  261 . A compression spring  28  is installed between the pivot portion  161  of the support arm  10  and the pivot portion  261  of the pivot head  26 . The two pivot portions are retained by threaded stud  291  and the shaft stud  292  so as to form as a fulcrum. The spring  29  provides a twisting force to resist against the gravitational force applied to the rotating arm  20  as the transient as the rotating arm  20  releases so as not to fall down as the rotating arm  20  rotates too fast. An outer periphery of the tube joint  24  extends with a protrusion  241 . The protrusion  241  is installed with a threaded hole  242 . 
   The lamp head  30  has a pivot head  31 , a lampshade  32  fixed to one end of the pivot head  31  and a lamp body (not shown). The lamp body is at an interior of the lampshade for illumination. Another end of the pivot head  31  is pivoted to the pivot head  27  at the second end  22  of the rotating arm  20  as a rotation fulcrum. A compression spring (not shown) is installed between the pivot head  31  and the pivot head  27  for providing a predetermined pressure in rotation. 
   The base  40  is assembled to the first end  11  of the support arm  10 . A weight (not shown) is installed in the base  40  for stabilizing the support arm  10  so that the lamp can be positioned on a table or platform. 
   The cambered track  50  is fixed to a predetermined position of the support arm  10  and is formed with a cambered slot  51 . In this embodiment, the cambered track  50  has shape like a crescent moon. One end of the cambered track  50  has a through hole  52  and a stud hole  53  corresponding to the threaded hole  142  and stud hole  143  in the tube joint  14  of the support arm  10 . A thread stud  53  and a shaft stud  55  pass through the threaded hole  142  and stud hole  143  to retain the cambered track  50  to the support arm  10  with two fixing points. Moreover, one side of the cambered track  50  is formed with a pressed surface  56  at one side of the cambered slot  51 . 
   A stop sheet  60  is assembled to a predetermined position of the rotating arm  20  to guide the rotating arm  20  to move along the cambered track  50  so that the rotating arm  20  can be controlled to retain at a predetermined angle. The stop sheet  60  of this embodiment may be a rotating button. The stop sheet  60  has a handle  61 , a press plate  62  connected to the handle  61 , and a stud portion  63  connected to the press plate  62 , as illustrated in  FIG. 5 . Moreover, the press plate  62  is formed with a pressing surface  621 . When the stud portion  63  passes through the cambered slot  51  of the cambered track  50  and is screwed to the threaded hole  242  of the tube joint  24 , they form a cambered guide structure and the rotating arm  20  is guided along the cambered track  50  to be at a predetermined angle. When the button is tightened, the pressing surface  621  of the press plate  62  will press the pressed surface  56  of the cambered track  50  so as to control the rotating arm  20  at the angle. Other than the stop sheet  60  having a form of a button, in the present invention, the stop sheet  60  may be an elastic pullable rod (not shown). Normally, the elastic pullable rod is buckled to a respective portion of the cambered track  50  by the elasticity of an elastic element. When the rod is pulled outwards, it is released from the portion of the cambered track  50  so that the rotating arm  20  is rotatable. 
   Next, in the rotation control device of the lamp of the present invention, other than being assembled to the base  40  as a seated lamp, the support arm  10  can be assembled to a wall so as to form as a suspending lamp. 
   Referring to  FIGS. 1 and 2 , in the present invention, the rotation control device for a support arm of a lamp has the function of easily adjusting the swinging of the rotating arm  20 . In operation, it is only necessary to release the stop sheet  60 , as illustrated in  FIG. 5 , so that the stop sheet  60  and the cambered track  50  can in a loose state. Then as illustrated in  FIGS. 4 and 6 , the rotating arm  20  is rotated to a predetermined angle. Then the stop sheet  60  is tightened, as illustrated in  FIG. 5  so that the pressing surface  621  of the press sheet  62  tightly presses the pressed surface  56  of the cambered track  50 . Then the rotating arm  20  is fixed to the cambered track  50  to complete the adjusting operation. The orientation of the lamp head  30  is adjustable by the pivoting structure between the pivot head  31  of the lamp head  30  and the pivot head  27  of the rotating arm  20 . 
   It should be noted that the rotation control device for a support arm of a lamp of the present invention uses a cambered track  50  installed to the support arm  10  with the stop sheet  60  in the cambered track  50  so as to form as a lever fulcrum. Thus a steady and firm support structure is provided to the support arm  10  so that the support arm  10  can be retained to a predetermined angle as a gravitation force is applied thereto for a longer time. Thus the lamp can provide a proper illumination. In the prior art, the rotating arm  20  will loose as it is used for a time period. Next, the present invention has a simple structure and the cost in assembly is low. In operation, it is only necessary to tighten or release the stop sheet  60 , the rotating arm  20  can be adjusted to a predetermined angle rapidly. Thereby, the operation of the present invention is easy and conveniently and is a personal design. 
   The present invention is thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the present invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.