Abstract:
A device includes a bolt, a nut, and a coupling. The bolt includes a head and a shaft, and the bolt has a first longitudinal axis that passes through a center of the head and the shaft. The shaft has a first set of threads that are disposed on a radially outer surface of the shaft, and the head has a substantially convex surface. The nut has a second set of threads that are disposed on a radially inner surface of the nut, and the second set of threads is structured to threadably engage the first set of threads. The coupling is structured to attach the bolt to an object, and the coupling and the nut are structured to maintain the substantially convex surface of the head in an abutting relationship with a substantially concave surface of the object.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application is a continuation-in-part of U.S. patent application Ser. No. 10/722,748, which was filed on 26 Nov. 2003, now U.S. Pat. No. 7,008,083 B2, issued Mar. 7, 2006, which is incorporated by reference in its entirety. 

   BACKGROUND OF THE INVENTION 
   1. Technical Field of the Invention 
   This disclosure relates generally to lighting systems, components, and methods and more particularly to a device for securing a shade to a light fixture. 
   2. Description of the Related Art 
     FIGS. 1-5  are diagrams that illustrate the industry standard device for attaching a shade to a lighting fixture, in this case a lamp. Like reference numerals refer to like parts throughout. With reference to  FIGS. 1-5 , a base unit  2  of the lamp supports a switch/socket assembly  4  and a harp  8 . A light bulb  6  may be inserted and removed from the switch/socket assembly  4  by screwing the base of the light bulb into the socket. A flattened portion at the top of the harp  8  supports a lamp washer  10  and a finial support  12 . 
   The lamp washer  10  is typically crimped to the shaft of the harp  8  at two positions. Prior to crimping, a threaded end of the finial support  12  is inserted through a central hole in the middle of the lamp washer  10 . The other end of the finial support  12  is flattened and keyed to engage the shaft of the harp  8 . Consequently, when the lamp washer is crimped to the shaft of the harp  8 , the threaded end of the finial support  12  is positioned perpendicularly to the shaft of the harp  8 . The lamp washer  10  and the finial support  12  are rigidly connected. That is, a force applied to the finial support  12  causes the lamp washer  10  to move and vice versa. Additionally, the keyed end of the finial support  12  allows one to screw and unscrew a finial  14  (see  FIG. 4 ) from the finial support  12  without causing the finial support  12  to rotate. 
     FIG. 3  illustrates a top, front, and side view of the harp  8 , the lamp washer  10 , and the finial support  12 . The dotted lines in  FIGS. 2 and 3  indicate that the lamp washer  10 , and in turn the finial support  12 , may rotate around the shaft of the harp  8  if enough rotational force is applied. 
   A rotational force is typically applied when there is a shade  16  attached to the lamp fixture by a finial  14 , as shown in  FIG. 4 . Objects, pets, or people may physically contact the shade  16 , thereby causing the shade  16 , the finial  14 , the finial support  12 , and the lamp washer  10  to rotate around the axis of the harp  8 , as illustrated in  FIG. 5 . Of course, if force is applied to the shade  16  in a direction parallel to the axis of the harp  8 , rotation is prevented because the lamp washer  10  may only rotate in directions perpendicular to the harp axis. Thus, in these situations, the entire lamp tends to move. 
   Neither situation outlined above is desirable. In the first case, the shade  16  may stop in a position that is too close, or even touching, a hot light bulb  6 . This is frequently the cause of many fires. In the second case, the shade  16 , the harp  8 , or the entire lamp may be damaged if the force applied to the shade is sufficient to overturn the lamp. 
   Furthermore, the more the shade  16  is jostled over time, the looser the connection between the lamp washer  10  and the harp  8  becomes. This is due to the fact that metal at the crimped portion of the lamp washer  10  is in direct contact with the harp  8 . Thus, the metal will start to wear down with each rotation of the lamp washer  10 , making the overall connection less stable. 
   Embodiments of the invention address these and other disadvantages of the conventional art. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIGS. 1-5  are diagrams illustrating a conventional lamp shade attachment device. 
       FIGS. 6A and 6B  are diagrams illustrating the components of a shade leveler according to some embodiments of the invention. 
       FIGS. 7A and 7B  are diagrams illustrating how the shade leveler of  FIG. 6  fits together in relationship to conventional lamp fixture components. 
       FIGS. 8A ,  8 B, and  8 C are top, front, and side-view diagrams, respectively, which illustrate how the shade leveler of  FIG. 6  is assembled in relationship to a conventional harp. 
       FIGS. 9A and 9B  are front and side-view diagrams, respectively, illustrating how the shade leveler of  FIG. 6  is positioned after the components shown in  FIG. 7A  are assembled. 
       FIGS. 10A ,  10 B,  10 C, and  10 D are diagrams illustrating the operation of the shade leveler of  FIG. 6  when a force is applied to a conventional shade that is attached to it. 
       FIG. 11  is a diagram illustrating how the shade leveler of  FIG. 6  restricts the movement of a conventional shade attached to a conventional lamp fixture. 
       FIGS. 12A and 12B  are diagrams illustrating shade leveling rings according to other embodiments of the invention. 
       FIGS. 13A and 13B  are front and side-view diagrams, respectively, that illustrate other embodiments of the invention that are used with a conventional S-cluster. 
       FIGS. 14A and 14B  are diagrams illustrating the components of the shade leveler from  FIG. 13  according to alternate embodiments of the invention and how those components fit together with relationship to a conventional S-cluster. 
       FIGS. 15A-15C  are top, front, and side-view diagrams, respectively, that illustrate the components of the shade leveler of  FIG. 14A  after being assembled and affixed to a conventional riser. 
       FIGS. 16A and 16B  are top-view diagrams illustrating an additional component for a shade leveler according to other embodiments of the invention. 
       FIGS. 17A and 17B  are side-view diagrams illustrating how the additional component of  FIGS. 16A and 16B  is assembled in relationship to other components of the shade leveler. 
       FIG. 18  is a side-view diagram illustrating a shade leveler according to some other embodiments of the invention. 
       FIG. 19  is a side-view diagram further illustrating the components of the shade leveler of  FIG. 18 , where some components are illustrated in cross-section. 
       FIG. 20  is a side-view diagram further illustrating the components of the shade leveler of  FIG. 18 , where some components are illustrated in cross-section. 
       FIG. 21  is a side-view diagram illustrating the operation of the shade leveler of  FIG. 18  in conjunction with a conventional lampshade and a conventional finial. 
       FIG. 22A  is a cross-sectional diagram illustrating a shade leveler according to some other embodiments of the invention. 
       FIG. 22B  is a top-view and a side-view diagram further illustrating the tension spring of  FIG. 21A . 
       FIG. 22C  is a side view diagram illustrating the operation of the shade leveler of  FIG. 22A . 
       FIG. 23  is a side-view diagram illustrating the shade leveler of  FIG. 22A  assembled in conjunction with a conventional lampshade and a conventional finial. 
       FIG. 24  is a side-view diagram illustrating the shade leveler of  FIG. 22A  operating in conjunction with the conventional lampshade and the conventional finial. 
       FIG. 25A  is a cross-sectional diagram illustrating a shade leveler  400  according to some other embodiments of the invention. 
       FIG. 25B  is a top-view and a side-view diagram further illustrating the tension spring  406  of  FIG. 25A . 
       FIG. 25C  is a side view diagram illustrating the operation of the shade leveler  400 . 
   

   DETAILED DESCRIPTION 
   In the following detailed description, numerous exemplary embodiments of the invention are described. These embodiments are not limiting, but rather illustrate concepts of the invention that may be applied in many different embodiments. Thus, the scope of the invention should only be limited by the language of the appended claims. Throughout this detailed description, like reference numerals in the FIGURES refer to like elements. 
     FIGS. 6A and 6B  are diagrams illustrating the components of a shade leveler according to some embodiments of the invention. 
     FIG. 6A  is a diagram with two side views of a post  100 . The bottom portion of the post  100  has a groove that corresponds to the curved shaft of the harp  8  (see  FIGS. 7A and 7B ). This grooved, or keyed, portion of the post  100  allows a finial  14  (see  FIG. 4 ) to be screwed or unscrewed from the threads of the post without causing the post to rotate. 
     FIG. 6B  is a diagram with a top view and a side view of a shade leveling ring  110 . As seen in  FIG. 6B , there is a hole in the central portion of the shade leveling ring  110 . The inner, central portion of the shade leveling ring  110  is raised with respect to the outermost portion of the shade leveling ring  110 . 
   The post  100  and the shade leveling ring  110  may be manufactured from any number of conventionally known materials such as metals, plastics, ceramics, or wood. 
     FIGS. 7A and 7B  are diagrams illustrating how the shade leveler of  FIG. 6  fits together in relationship to conventional lamp fixture components. The grooved end of the post  100  is placed against the horizontal portion of the harp  8 . The shade leveling ring  110  is then placed over the post  100  so that the threaded end of the post goes through the hole in the shade leveling ring. Next, a shade bracket  16 A from a conventional shade  16  (see  FIG. 4 ) is laid over the shade leveling ring  110 , such that the threaded end of the post  100  goes through the hole in the shade bracket  16 A. Finally, the finial  14  is screwed onto the threaded end of the post  100 . The finial  14  holds the shade bracket  16 A against the shade leveling ring  110  and prevents the shade bracket  16 A (and thus, the shade  16 ) from falling off the threaded end of the post  100 . 
   The difference between  FIGS. 7A and 7B  is that in  FIG. 7A  the shade leveling ring  110  has a dome-shaped profile that is completely smooth while the shade leveling ring  110  of  FIG. 7A  has a dome-shaped profile with a raised edge at the uppermost portion of the dome. 
     FIGS. 8A ,  8 B, and  8 C are top, front, and side-view diagrams, respectively, which illustrate how shade levelers in accordance with some embodiments of the invention are assembled in relationship to a conventional harp. As seen in  FIGS. 8A-8C , a portion of the flat, outer portion of the shade leveling ring  110  is in contact with the harp  8 . At this junction between the harp  8  and the shade leveling ring  110 , the shade leveling ring  110  is affixed to the harp  8 . The shade leveling ring  110  may be permanently affixed to the harp  8  by any number of conventional methods, such as spot welding. The shade leveling ring  110  may also be detachably affixed to the harp  8  using any number of conventional methods, such as adhesive or screws. This would allow a damaged harp  8  or shade leveling ring  110  to be separately replaced. 
     FIGS. 9A and 9B  are front and side-view diagrams, respectively, illustrating how the shade leveler of  FIG. 6  is positioned after the components shown in  FIG. 7A  are assembled. It is easily seen in  FIGS. 9A and 9B  how the dome-shaped portion of the shade leveling ring  110  contacts the circular edge on the bottom of the shade bracket  16 A. When the finial  14  is tightened, the grooved portion of the post  100  contacts the harp  8  and prevents the post from rotating in the same direction that the finial is tightened. Similarly, the finial  14  may be loosened without rotating the post  100 . However, the grooved portion of the post  100  is only loosely held against the harp  8  by the shade leveling ring  110 . In other words, no portion of the post  100  is rigidly connected to the harp  8 . Tightening the finial  14  only serves to hold the circular edge on the bottom of the shade bracket  16 A more tightly to the dome-shaped portion of the shade leveling ring  110 . 
     FIGS. 10A ,  10 B,  10 C, and  10 D are diagrams illustrating the operation of the shade leveler of  FIG. 6  when a force is applied to a conventional shade  16  that is attached to it. This occurs when some object, pet, or person bumps or contacts the shade  16  (see  FIG. 4 ).  FIGS. 10A and 10B  are front-view diagrams, and  FIGS. 10C and 10D  are side-view diagrams. 
   As seen in  FIGS. 10A-10D , when a force is applied to the shade bracket  16 A it causes the shade bracket  16 A, the finial  14 , and the post  100  to move in relationship to the shade leveling ring  110  and the harp  8 . The dome-shaped portion of the shade leveling ring  110  allows the shade bracket  16 A to slide over the dome in the direction of any applied force. This is a significant improvement over conventional devices, where movement of the shade  16  is limited to a rotational direction about the axis of the harp  8  (see  FIGS. 2 and 3 ). With the dome-shaped profile of the shade leveling ring  110 , force can be applied in all directions to the shade  16  and the shade  16  will move in that direction. 
   Furthermore, as mentioned above, only a tiny portion of the shade bracket  16 A is in contact with the shade leveling ring  110 . Thus, regardless of how tight the finial  14  is screwed onto the post  100 , it is relatively easy to move the shade bracket  16 A over the dome-shaped profile of the shade leveling ring  110 . 
   In fact, when the finial  14  is merely tightened to the point where it prevents the shade bracket  16 A from falling off the post  100 , an additional advantage is achieved. The equally distributed weight of the shade  16  will cause the shade bracket  16 A to seek a naturally balanced point on the shade leveling ring  110 . Thus, if the shade  16  is bumped, the dome-shaped profile of the shade leveling ring  110  imparts a self-leveling action. 
   Of course, at some point further movement of the shade bracket  16 A, the finial  14 , and the post  100  in relation to the harp  8  and the shade leveling ring  110  will not be possible due to the shade bracket  16 A or the post  100  impinging against the shade leveling ring  110 . Consequently, unlike the conventional shade attachment device, the shade  16  will never come to rest in a position where it is too close to the light bulb  6 , as shown in  FIG. 11 . 
   Although the embodiments of the invention described above possess a shade leveling ring  110  with a dome-shaped profile, many other profiles and shapes are possible depending on the range of motion that the designer wishes to impart to the shade bracket  16 A. 
   For example, raising the dome-shaped portion further from the flattened portion would result in the shade leveling ring  110  shown in  FIG. 12A . This design would allow the shade bracket  16 A (not shown) a greater degree of movement because of the additional clearance between the shade bracket  16 A and the flattened portion of the shade leveling ring  110 . Of course, the length of the post  100  would also need to be increased. 
     FIG. 12B  is a shade leveling ring according to other embodiments of the invention. In this design, the raised portion of the shade leveling ring  110  is substantially cone-shaped. 
   Other embodiments of the invention may alter the range of motion of the shade bracket  16 A by having a shade leveling ring  110  that has a larger diameter hole than the diameter of the post  100 . Still other embodiments of the invention may have a shade leveling ring that has a central hole that is not circular, but some other shape that allows more movement in certain directions and less movement in others. For example, the central hole may be substantially star-shaped or cross-shaped. 
     FIGS. 13A and 13B  are front and side-view diagrams, respectively, that illustrate other embodiments of the invention that are used with a conventional S-cluster  18 . An S-cluster  18  has two sockets  20  that are used to hold lightbulbs (not shown). The S-cluster  18  also includes a riser  22 . The shade leveler  120  according to these embodiments of the invention sits atop the riser  22 . 
     FIGS. 14A and 14B  are diagrams illustrating the components of the shade leveler from  FIG. 13  according to alternate embodiments of the invention and how those components fit together with relationship to a conventional S-cluster. Like the embodiments described above, the shade leveler  120  includes a post  100  and a shade leveling ring  110 . 
   However, since the conventional S-cluster does not use a harp, the shade leveler  120  also includes a base  105  that has a ridge on top of it. The base  105  is affixed to the top of the riser  22 . Like the embodiments explained above, the grooved bottom portion of the post  100  and the ridge on the base  105  interface with each other and allow the finial  14  to be tightened and loosened without turning the post  100 . As usual, a conventional shade bracket  16 A is held on the post  100  by a conventional finial  14 . 
   While both of the shade leveling rings  110  in  FIGS. 14A and 14B  are substantially dome-shaped, the shade leveling ring  110  of  FIG. 14B  has a raised edge at the uppermost portion of the dome, similar to the embodiment illustrated in  FIG. 7B . 
   The base  105 , the post  100 , and the shade leveling ring  110  may be manufactured from any number of conventionally known materials such as metals, plastics, ceramics, or wood. 
     FIGS. 15A-15C  are top, front, and side-view diagrams, respectively, that illustrate the components of the shade leveler of  FIG. 14A  after being assembled and affixed to the riser  22 . A flat, outer portion of the shade leveling ring  110  contacts the ridge on the base  105 . At this junction the shade leveling ring  110  may be permanently or detachably affixed to the base  105 . The contact point between the shade leveling ring  110  and the base  105  is analogous to the contact point between the shade leveling ring  110  and the harp  8  illustrated in  FIGS. 8A-8C . The shade leveling ring  110  holds the post  100  loosely against base  105 . In other words, no portion of the post is rigidly connected to the base  105 . The entire shade leveler  120 , once assembled, may be permanently or detachably affixed to the riser  22 . The shade leveling ring  110  may be permanently affixed to the base  105  by any number of conventional methods, such as spot welding. The shade leveling ring  110  may also be detachably affixed to the base  105  using any number of conventional methods, such as adhesive or screws. 
   While the embodiments of the invention described in  FIGS. 13 ,  14 , and  15  include an additional component (the base  105 ) compared to the other embodiments described in this disclosure, the operation of these embodiments is substantially the same as the operation explained above with respect to  FIGS. 10 and 11 . Thus, for the sake of brevity, the operation of the embodiments illustrated in  FIGS. 13 ,  14 , and  15  will not be duplicated here. 
     FIGS. 16A and 16B  are top-view diagrams illustrating an additional component for a shade leveler according to still other embodiments of the invention.  FIGS. 16A and 16B  illustrate a finial ring  115 . The finial ring  115  has a rectangular slot  116 . The slot  116  is configured to allow the post  100  to pass through the center of the finial ring  115 . 
     FIGS. 17A and 17B  are side-view diagrams corresponding to  FIGS. 16A and 16B , respectively, illustrating how the finial ring  115  of  FIGS. 16A and 16B  is assembled in relationship to other components of the shade leveler. The shade leveling ring  110  holds the post  100  against a harp (not shown). Unlike the embodiments illustrated in  FIGS. 6-11 , in this case the shade leveling ring  110  is rigidly affixed to the post  100 . That is, the shade leveling ring  110  and the post  100  cannot move in relation to each other. 
   Like the other embodiments described above, a finial  14  is threaded on the post  100  to hold a shade bracket  16 A against the dome-shaped portion of the shade leveling ring  110 . However, in this case the finial ring  115  is inserted between the shade bracket  16 A and the finial  14 . The finial ring  115  also has a dome-shaped profile. The dome-shaped profile of the finial ring may or may not be the same as the dome-shaped profile of the shade leveling ring  110 . 
   The finial ring  115  allows the shade bracket  16 A to pivot on top of the shade leveling ring  110  even when the post  100  is rigidly affixed to the shade leveling ring  110 . The rectangular slot  116  in the finial ring  115  allows the finial ring to move in relationship to the fixed post  100 . Without the finial ring  115 , the flat bottom surface of the finial  14  would otherwise contact the flat upper surface of the shade bracket  16 A, preventing it from sliding on the dome-shaped upper surface of the shade leveling ring  110 . 
   It should be apparent that in the embodiments described in  FIGS. 16A ,  16 B,  17 A, and  17 B, the range of motion for the shade bracket  16 A is additionally limited by the shape of the rectangular slot  116 . In other embodiments of the invention, the shape of the slot  116  in the finial ring  115  may be different to allow for other desired ranges of motion. For example, the rectangular slot  116  could be replaced with a circular hole with a diameter larger than that of the post  100 . This would allow movement of the shade bracket  16 A in all directions. Alternatively, the opening in the finial ring  115  could be cross-shaped or star-shaped. 
     FIG. 18  is a side-view diagram illustrating a shade leveler  200  according to some other embodiments of the invention.  FIGS. 19 and 20  are side-view diagrams further illustrating the components of the shade leveler  200 , where some components are illustrated in cross-section. In  FIGS. 18 ,  19 , and  20 , conventional features such as a lamp, lampshade, and finial are not illustrated to avoid obscuring the inventive aspects of the illustrated embodiments. 
   Referring to  FIGS. 18 ,  19 , and  20 , the shade leveler  200  includes a ball head bolt  202 , a seat ring  204 , a tension spring  206 , a bracket  208 , and a harp rod  210 . As is more easily seen in  FIGS. 19 and 20 , the ball head bolt  202  (which is not shown in cross-section) has a threaded portion like a conventional bolt, but the head of the bolt is in the shape of a sphere or a ball. The bracket  208  is clamped to the harp rod  210  on either side of the ball head bolt  202  and holds the ball head bolt  202  against the top of the harp rod  210 . 
   Preferably, the portion of the harp rod  210  that is in contact with the ball of the ball head bolt  202  has a concave indentation to better support the convex surface of the ball head bolt  202 , but this feature is not required. The concave indentation may be formed by stamping the harp rod  210  or by some other conventional technique. 
   The seat ring  204  is structured to be threaded on the threaded portion of the ball head bolt  202 , and provides the surface upon which the conventional lampshade rests. The threaded portion of the ball head bolt  202  is also structured to accept a conventional finial, so that the conventional lampshade may be held firmly against the seat ring  204 . The tension spring  206  is arranged such that it is in contact with an upper surface of the spherical portion of the ball head bolt  202 , and in contact with a lower surface of the bracket  208 . 
     FIG. 21  is a side-view diagram illustrating the operation of the shade leveler  200  in conjunction with a conventional lampshade  212  and a conventional finial  214 . For clarity, only a portion of the lampshade  212  is shown in  FIG. 21 . According to preferred embodiments of the invention, the upper surface of the seat ring  204  may be dome or cone-shaped as seen in  FIGS. 18-21 , so that the lampshade  212  is automatically centered on the seat ring  204  as the finial  214  is tightened on the lampshade. 
   As is shown in  FIGS. 18 and 21 , the lamp shade leveler  200  is structured to tilt φ degrees away from a vertical axis. This tilt may occur at any angular position (i.e., 360°) around the vertical axis. The amount of tilt φ is determined by the interaction of the ball head bolt  202 , the seat ring  204 , and the bracket  208 . 
   The bracket  208  holds the ball head bolt  202  against an upper surface of the harp rod  210 , but does not maintain the ball head bolt in a rigid relationship with the harp rod. That is, the opening of the bracket  208  where the ball head bolt  202  passes through the bracket is preferably larger than the diameter of the shaft of the ball head bolt. This allows the entire ball head bolt  202  to be tilted relative to the vertical axis, and the ball head portion of the ball head bolt to rotate where it is cupped by the concave portion of the harp rod  210 . Of course, if the seat ring  204  were not threaded on the ball head bolt  202 , the shaft of the ball head bolt  202  would, at some point, contact the opening in the bracket  208  and prevent the ball head bolt  202  from tilting any further away from the vertical axis. This maximum tilt limit arising only from the contact between the ball head bolt  202  and the bracket  208  will be referred to as φ max1 . 
   The seat ring  204  is structured to be threaded on the end of the ball head bolt  202 , and it should be apparent that the position of the seat ring on the ball head bolt may be adjusted by turning the seat ring counterclockwise or clockwise. Preferably, the seat ring  204  is positioned such that the bottom surface of the seat ring is parallel to an upper surface of the bracket  208 , but not in direct contact with the upper surface. Otherwise, the lamp shade leveler  200  could not achieve any tilt. Thus, the seat ring  204  is positioned on the ball head bolt  202  such that there is a non-zero separation between the seat ring and the bracket  208  when the bottom surface of the seat ring and the upper surface of the bracket are aligned parallel to each other. However, at one particular position of the seat ring  204 , the seat ring will begin to contact the bracket  208  when the ball head bolt  202  is at the maximum tilt position φ max1 . At this position of the seat ring  204 , the maximum tilt becomes limited by the contact between the seat ring and the bracket  208 , not by the contact between the ball head bolt  202  and the bracket. The maximum tilt limit arising only from the contact between the seat ring  204  and the bracket  208  will be referred to as φ max2 . In most cases, 
   As the distance between the parallel surfaces of the seat ring  204  and the bracket  208  becomes smaller, the amount of tilt φ that may be achieved by the shade leveler  200  becomes smaller as well. 
   In the illustrated embodiments, the threaded portion of the ball head bolt  202  is designed to limit the minimum separation between the parallel surfaces of the seat ring  204  and the bracket  208 . This minimum separation corresponds to a design tilt limit that will be referred to as φ des . Thus, in the illustrated embodiments, when the seat ring  204  is in its lowest position on the ball head bolt  202 , the amount of tilt φ that the shade leveler  200  can achieve is between 0° and φ des  (0°≦φ≦φ des ). In preferred embodiments of the invention, the design tilt limit φ des  is about 8°. In alternative embodiments, the design tilt limit φ des  may be smaller than 8°. Of course, a tilt that is greater than the design tilt limit φ des  may be achieved if the seat ring  204  is not placed in a position corresponding to the minimum separation between the parallel surfaces of the seat ring  204  and the bracket  208 . 
   As was indicated above, the tension spring  206  is arranged in contact with an upper surface of the spherical portion of the ball head bolt  202  and in contact with a lower surface of the bracket  208 . The tension spring  206  is structured such that it pushes against the lower surface of the bracket  208 , firmly seating the convex surface of the spherical portion of the ball head bolt  202  into the concave indentation on the harp rod  210 . However, the tension spring  206  is also structured such that the convex surface of the spherical portion of the ball head bolt  202  may slide against the concave indentation on the harp rod  210 . Preferably, the tension spring  206  does not provide a sufficient force to prevent a conventional lampshade attached to the shade leveler  200  from being placed in a desired position by applying an outside force to the shade leveler. This is what would occur, for example, if a person wished to change the position of the shade. On the other hand, the tension spring  206  does provide a sufficient force to prevent the conventional lampshade from moving due to the force of gravity. 
   Thus, using the shade leveler  200 , a person could tilt a conventional shade  212  attached to the shade leveler up to φ des  away from the horizontal plane, and the tilt may be in any direction (360°) around a vertical axis that is perpendicular to the horizontal plane. 
   Furthermore, because the shade leveler  200  allows a tilt of up to ides in all directions around the vertical axis, the shade leveler may prevent the lampshade  212  from being damaged or the lamp from being knocked over when a displacing force is applied. According to preferred embodiments of the invention, the tension spring  206  may include spring steel, although other flexible or semi-flexible materials may be used. 
   The use of the tension spring  206  is also advantageous in embodiments of the invention because it may prevent metal-to-metal contact between the spherical portion of the ball head bolt  202  and the bracket  208 . Without the tension spring  206 , the connection between the ball head bolt  202  and the bracket  208  would become increasingly loose, requiring constant re-adjustment of the lampshade  212  position or replacement of the lamp shade leveler. 
     FIG. 22A  is a cross-sectional diagram illustrating a shade leveler  300  according to some other embodiments of the invention.  FIG. 22B  is a top-view and a side-view diagram further illustrating the tension spring of  FIG. 22A .  FIG. 22C  is a side view diagram illustrating the operation of the shade leveler  300 .  FIG. 23  is a side-view diagram illustrating the shade leveler  300  assembled in conjunction with a conventional lampshade and a conventional finial.  FIG. 24  is a side-view diagram illustrating the shade leveler  300  operating in conjunction with the conventional lampshade and the conventional finial. 
   In operation, the shade leveler  300  is very similar to the shade leveler  200  illustrated in  FIGS. 18-21 . One difference, however, is that the shade leveler  300  is structured to fit on the end of a pipe, for example, a pipe such as the riser  22  illustrated in  FIGS. 13A and 13B . Thus, the embodiments of the invention illustrated in  FIG. 22A  may be used in conjunction with a conventional S-cluster, for example, the S-cluster  20  of  FIGS. 13A and 13B . 
   Referring to  FIGS. 22A ,  22 B,  22 C,  23 , and  24 , the shade leveler  300  includes a ball head bolt  302 , a seat ring  304 , a tension spring  306 , and a threaded cap  308 . The shade leveler may further include a pipe coupling  310 . The pipe coupling  310  has an upper surface with a substantially concave indentation. The pipe coupling  310  has radially inward-facing threads that are configured engage radially outward-facing threads (not shown) on the end of a pipe or cylinder. The diameter of the hole containing the radially inward-facing threads in the pipe coupling  310  may vary to accommodate any size pipe. 
   Functionally, the threaded cap  308  serves a similar purpose as the bracket  208  of  FIGS. 18-21 . The threaded cap  308  has radially inward-facing threads arranged around an inner diameter of the threaded cap  308 . The radially inward-facing threads are structured to engage radially outward-facing threads arranged around an outer diameter of the pipe coupling  310 . When the threaded cap is  308  is screwed on to the pipe coupling  310 , it holds a spherical portion end of the ball head bolt  302  within the corresponding concave indentation at the upper end of the pipe coupling  310 . 
   As illustrated in  FIG. 22A , according to some embodiments of the invention the seat ring  304  may have a top surface that is substantially flat. 
   As illustrated in  FIG. 22C , the shade leveler  300  is structured to tilt φ degrees away from a vertical axis. This tilt may occur at any angular position (i.e., 360°) around the vertical axis. The amount of tilt φ is determined by the interaction of the ball head bolt  302 , the seat ring  304 , and the threaded cap  308 . 
   The threaded cap  308  holds the ball head bolt  302  against an upper surface of the harp rod  210 , but does not maintain the ball head bolt in a rigid relationship with the harp rod. That is, the opening of the threaded cap  308  where the ball head bolt  302  passes through the threaded cap  308  is preferably larger than the diameter of the shaft of the ball head bolt. This allows the entire ball head bolt  302  to be tilted relative to the vertical axis, and the ball head portion of the ball head bolt to rotate where it is cupped by the concave portion of the pipe coupling  310 . Of course, if the seat ring  304  were not threaded on the ball head bolt  302 , the shaft of the ball head bolt would, at some point, contact the opening in the threaded cap  308  and prevent the ball head bolt  302  from tilting any further away from the vertical axis. This maximum tilt limit arising only from the contact between the ball head bolt  302  and the threaded cap  308  will be referred to as φ max1 . 
   The seat ring  304  is structured to be threaded on the end of the ball head bolt  302 , and it should be apparent that the position of the seat ring on the ball head bolt may be adjusted by turning the seat ring counterclockwise or clockwise. Preferably, the seat ring  304  is not positioned such that the bottom surface of the seat ring is parallel to and in direct contact with an upper surface of the threaded cap  308 . Otherwise, the lamp shade leveler  300  could not achieve any tilt. Thus, the seat ring  304  is preferably positioned on the ball head bolt  302  such that there is a non-zero separation between the seat ring and the threaded cap  308  when the bottom surface of the seat ring and the upper surface of the threaded cap are aligned parallel to each other. However, at one particular position of the seat ring  304 , the seat ring will begin to contact the threaded cap  308  when the ball head bolt  302  is at the maximum tilt position φ max1 . At this position of the seat ring  304 , the maximum tilt becomes limited by the contact between the seat ring and the threaded cap  308 , not by the contact between the ball head bolt  302  and the threaded cap. The maximum tilt limit arising only from the contact between the seat ring  304  and the threaded cap  308  will be referred to as φ max2 . 
   As the distance between the parallel surfaces of the seat ring  304  and the threaded cap  308  becomes smaller, the amount of tilt φ that may be achieved by the shade leveler  300  becomes smaller as well. In the illustrated embodiments, the threaded portion of the ball head bolt  302  is designed to limit the minimum separation between the parallel surfaces of the seat ring  304  and the threaded cap  308 . This minimum separation corresponds to a design tilt limit that will be referred to as φ des . Thus, in the illustrated embodiments, when the seat ring  304  is in its lowest position on the ball head bolt  302 , the amount of tilt φ that the shade leveler  300  can achieve is between 0° and φ des  (0°≦φ≦φ des ). In preferred embodiments of the invention, the design tilt limit φ des  is about 8°, but in other embodiments the design tilt limit may be less than that. 
   Similar to the embodiments illustrated in  FIGS. 18-21 , the tension spring  306  is arranged in contact with an upper surface of the spherical portion of the ball head bolt  302  and in contact with a lower surface of the threaded cap  308 . The tension spring  306  is structured such that it pushes against the lower surface of the threaded cap  308 , firmly seating the convex surface of the spherical portion of the ball head bolt  302  into the concave indentation on the pipe coupling  310 . However, the tension spring  306  is also structured such that the convex surface of the spherical portion of the ball head bolt  302  may slide against the concave indentation on the pipe coupling  310 . Preferably, the tension spring  306  does not provide a sufficient force to prevent a conventional lampshade  312  attached to the shade leveler  300  from being placed in a desired position by applying an outside force to the shade leveler. This is what would occur, for example, if a person wished to change the position of the shade. On the other hand, the tension spring  306  does provide a sufficient force to prevent the conventional lampshade from moving due to the force of gravity. 
   Thus, using the shade leveler  300 , a person could tilt a conventional shade  312  attached to the shade leveler up to φ des  away from the horizontal plane, and the tilt may be in any direction (360°) around a vertical axis that is perpendicular to the horizontal plane. 
   Furthermore, because the shade leveler  300  allows a tilt of up to φ des  in all directions around the vertical axis, the shade leveler may prevent the lampshade  312  from being damaged or the lamp from being knocked over when a displacing force is applied (e.g., the lampshade is accidentally struck by another object). According to preferred embodiments of the invention, the tension spring  306  may include spring steel, although other flexible or semi-flexible materials may be used. 
   Referring to  FIG. 22B , it can be seen that the tension spring  306  has a circular opening. The diameter of the opening is large enough to allow the shaft portion of the ball head bolt  302  to pass through it, but is small enough to prevent the spherical portion of the ball head bolt from passing through it. The turned up edges of the tension spring  306  do not completely surround the opening, but are disposed on opposite sides of the spring and are substantially parallel to each other. 
   Other shapes for the tension spring  306  are anticipated. For example, the edge of the tension spring  306  that contacts the surface of the threaded cap  308  may be continuous, circular, and completely surround the opening. In other embodiments of the invention, the edge that contacts the threaded cap  408  may be continuous but have an irregular polygonal shape or a regular polygonal shape such as square, pentagonal, hexagonal, octagonal, etc. In other embodiments, the curved edges of the tension spring  306  may not be continuous but may have multiple curved edge portions that are separated by edges that are substantially flat. 
   According to preferred embodiments of the invention, the tension spring  306  consists of spring steel, but it is anticipated that other flexible materials may alternatively be used, either alone or in combination. 
   According to the illustrated embodiments of the invention the tension spring is also advantageous in that it prevents metal-to-metal contact between the spherical portion of the ball head bolt  302  and the threaded cap  308 . Without the tension spring  306 , the connection between the ball head bolt  302  and the threaded cap  308  would become increasingly loose, requiring constant re-adjustment of the position of the lampshade  312  or replacement of the lamp shade leveler  300 . 
     FIG. 25A  is a cross-sectional diagram illustrating a shade leveler  400  according to some other embodiments of the invention.  FIG. 25B  is a top-view and a side-view diagram further illustrating the tension spring  406  of  FIG. 25A .  FIG. 25C  is a side view diagram illustrating the operation of the shade leveler  400 . 
   Referring to  FIGS. 25A ,  25 B, and  25 C, the shade leveler includes a ball head bolt  302 , a seat ring  304 , and a threaded cap  308 . These components are the same as those described for the embodiments illustrated in  FIGS. 22-24 , so a duplicate description will be omitted. 
   The shade leveler  400  also includes a tension spring  406  and a bolt coupling  410 . The bolt coupling  410  includes a hole with radially inward-facing threads that are configured to engage radially outward-facing threads (not shown) of a bolt or a screw. The diameter of the hole containing the radially inward-facing threads of the bolt coupling  410  may be varied to accommodate any size bolt or screw. Like the pipe coupling  310  of  FIG. 22A , the bolt coupling  410  has an upper surface with a concave indentation structured to match the convex surface of the spherical head portion of the ball head bolt  302 . 
   Referring to  FIGS. 25A and 25B , the tension spring  406  may be a washer with a substantially dome-shaped profile. A central hole in tension spring  406  is sized to allow the shaft of the ball head bolt  302  to pass through it, but is too small to allow the head of the ball head bolt to pass through. Although the shape of the tension spring  406  has a different construction compared to the tension spring  306  of the embodiments described above, functionally the tension spring  406  serves the same purpose. 
   That is, the tension spring  406  is arranged in contact with an upper surface of the spherical portion of the ball head bolt  302  and in contact with a surface of the threaded cap  308 . The tension spring  406  is structured such that it pushes against the surface of the threaded cap  308 , firmly seating the convex surface of the spherical portion of the ball head bolt  302  into the concave indentation on the bolt coupling  410 . However, the tension spring  406  is also structured such that the convex surface of the spherical portion of the ball head bolt  302  may slide against the concave indentation on the bolt coupling  410 . Preferably, the tension spring  406  does not provide a sufficient force to prevent a conventional lampshade attached to the shade leveler  400  from being placed in a desired position by applying an outside force to the shade leveler. This is what would occur, for example, if a person wished to alter the position of the shade. On the other hand, the tension spring  406  preferably provides a sufficient force to prevent an attached conventional lampshade from moving due to the force of gravity. 
   Over time, metal-to-metal wear between the tension spring  406  and the head of the ball head bolt  302  may require additional force to be applied to the tension spring  406 . This is easily accomplished by adjusting the position of the threaded end cap  308  on the bolt coupling  410 . 
   Thus, using the shade leveler  400 , a person could tilt a conventional shade attached to the shade leveler up to φ des  away from the horizontal plane, and the tilt may be in any direction (360°) around a vertical axis that is perpendicular to the horizontal plane. 
   Furthermore, because the shade leveler  400  allows a tilt of up to φ des  in all directions around the vertical axis, the shade leveler may prevent a conventional lampshade from being damaged or the lamp from being knocked over when a displacing force is applied (e.g., the lampshade is accidentally struck by another object). According to preferred embodiments of the invention, the tension spring  406  may include spring steel, although other flexible or semi-flexible materials may be used. 
   Having described and illustrated the principles of the invention in several exemplary embodiments, it should be apparent that the invention can be modified in arrangement and detail without departing from such principles. The inventor regards the subject matter of the invention to include all combinations and sub-combinations of the various elements, features, functions and/or properties disclosed herein. The inventor claims all modifications and variations falling within the spirit and scope of the attached claims.