Patent Abstract:
An independent friction joint structure including: at least one plug part having a connection to a device, the device comprising a lamp head; at least one joint part holding the at least one plug part in place, the at least one joint part having at least one holding structure; at least one side part having the ability to generate frictional rotational resistance to keep the at least one plug part in a predetermined position; at least one electrical contact between the at least one side part and the at least one holding structure of the at least one joint part; and at least one screw to fit all the components of the independent friction joint structure together.

Full Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
     This application is a Divisional of U.S. application Ser. No. 13/565,686, filed Aug. 2, 2012, which claims priority to U.S. Provisional Application No. 61/646,220, filed May 11, 2012, each of which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     The present invention relates to joint structures for connecting two members for pivotal motion relative to each other and, in particular embodiments, to such joint structures that also provide one or more electrical connections between electrical conductors held by the two members and, in further particular embodiments, to such joint structures that also have a preset frictional resistance to pivotal motion. Further embodiments are directed to components of such joint structures and methods of making and using such joint structures. 
     SUMMARY OF THE DISCLOSURE 
     A joint structure according to particular embodiments of the present invention connects a first member and a second member, and allows pivotal motion of one or both members about a pivot axis. The first and second members may be, for example, an arm member and a leg member, respectively, where the arm member is coupled, by the joint device, to the leg member for pivotal motion. However, a joint structure according to other embodiments may be arranged to connect other members together, for pivotal motion. 
     A joint structure according to an example embodiment of the present invention is employed in a lamp, to allow easy and convenient manual adjustment of the pivot angle of an arm, lamp head or other component of the lamp. In particular embodiments, the joint structure includes one or more electrical connections that connect electrical wires or other conductors in the arm, lamp head or other component. Also in particular embodiments, the joint structure has a preset frictional resistance to pivotal motion that is set to a magnitude sufficient to maintain the pivotal position of the arm, lamp head or other component, once that member is manually moved to a selected pivot position. Also in particular embodiments, the joint structure is configured so as to allow the arm, lamp head or other component to rotate or turn 360 degrees about a rotational axis that is perpendicular to the pivot axis of the joint structure. 
     According to an aspect of the present disclosure, provided is an independent friction joint structure including: at least one plug part having a connection to a device, the device comprising a lamp head; at least one joint part holding the at least one plug part in place, the at least one joint part having at least one holding structure; at least one side part having the ability to generate frictional rotational resistance to keep the at least one plug part in a predetermined position; at least one electrical contact between the at least one side part and the at least one holding structure of the at least one joint part; and at least one screw to fit all the components of the independent friction joint structure together. 
     According to an aspect of the present disclosure, provided is a lamp structure including: a lamp head; a lateral body; an independent friction joint structure connecting the lamp head and the lateral body; a counter weight attached to the other end of the lateral body; a stand supporting the lateral body; a balance bar running parallel to the lateral body and connected to the independent friction joint structure and a connection portion located on the stand; and a base supporting the stand. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective exploded view of components of a joint structure, according to an embodiment of the present disclosure. 
         FIG. 2  is a perspective view of the assembled joint structure of  FIG. 1 , according to an embodiment of the present disclosure. 
         FIG. 3  is a perspective exploded view of components of a plug part of the friction joint structure of  FIG. 1 , according to an embodiment of the present disclosure. 
         FIG. 4  is a perspective view of the assembled plug part of  FIG. 3 , according to an embodiment of the present disclosure. 
         FIG. 5  is a cutaway view of the plug part of  FIG. 4 , according to an embodiment of the present disclosure. 
         FIG. 6  is a perspective exploded view of components of a friction-setting part of the joint structure of  FIG. 1 , according to an embodiment of the present disclosure. 
         FIG. 7   a  is a perspective view and  FIG. 7   b  is a cutaway view of the assembled friction-setting part of  FIG. 6 , according to an embodiment of the present disclosure. 
         FIG. 8  is a partially-exploded perspective view of a lamp that includes the assembled joint structure of  FIG. 2 , according to an embodiment of the present disclosure. 
         FIG. 9  is a side view of the assembled lamp of  FIG. 8 , illustrating a range of rotational positions of the lamp head, according to an embodiment of the present disclosure. 
         FIG. 10  is another side view of the assembled lamp of  FIG. 8 , illustrating a range of pivot positions of the lamp head, according to an embodiment of the present disclosure. 
         FIG. 11  is yet another side view of the assembled lamp of  FIG. 8 , showing an example of a rotational position and pivot position of the lamp head, according to an embodiment of the present disclosure. 
         FIG. 12  is yet another side view of the assembled lamp structure of  FIG. 8 , showing an example of a pivot position of the arm of the lamp and a corresponding pivot position of the lamp head, according to an embodiment of the present disclosure. 
         FIG. 13  is a perspective exploded view of a joint structure, according to another embodiment of the present disclosure. 
         FIG. 14  is a perspective view of the assembled joint structure of  FIG. 13 . 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     In the following description of preferred embodiments, reference is made to the accompanying drawings which form a part hereof and in which are shown by way of illustration specific embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the preferred embodiments of the present disclosure. 
     Embodiments of the present invention relates to a joint structure for connecting two members and for allowing one or both of the members to pivot relative to the other member, about a pivot axis. Further embodiments of the present invention relate to components of such joint structures and devices and systems that include one or more of such joint structures. Yet further embodiments of the present invention relate to methods of making and using such joint structures, components, devices and systems. 
     A joint structure according to an example embodiment of the present invention includes one or more electrical connections that connect electrical wires or other conductors in the two members. Also in particular embodiments, the joint structure has a preset frictional resistance to pivotal motion that is set to a magnitude sufficient to maintain the pivotal position of the two members, once one or both member is manually moved to a selected pivot position. Also in particular embodiments, the joint structure is configured so as to allow one or both members to rotate or turn 360 degrees about a rotational axis that is perpendicular to the pivotal axis of the joint structure. 
     A joint structure according to embodiments of the present invention may be employed in a variety of useful applications, devices and systems, where two members are coupled together for pivotal motion. As a representative example, a joint structure  100  according to an embodiment of the present invention is shown in each of  FIGS. 8-12 , as connecting arm and leg members of an electrical lamp  110 . However, in other embodiments, the joint structure  100  may be configured for connecting other members in other devices or systems, such as, but not limited to connecting one or more tools, weapons, or other implement to an arm or other member, or connecting two arm sections of a complete arm or two leg sections of a complete leg. 
       FIG. 1  is a perspective exploded view of components of a joint structure  100 , according to an embodiment of the present disclosure.  FIG. 2  is a perspective view of the joint structure  100 , in an assembled form. Joint structure  100  includes plug part  102 , a pair of electrical contacts  103 , a pair of friction-setting parts  104 , a pair of screws  105  and bracket  106 . Plug part  102  connects to, for example, lamp head  114   a  (shown in  FIGS. 8-12 ) and provides electrical connections to connect electrical power to the electrical contacts  103 . While the plug part  102  in the embodiments of  FIGS. 8-12  connects electrical power to a lamp head  114   a , in other embodiments, the plug part  102  may be connected to another device or structure that uses electricity or that requires electric power. 
     Electrical contacts  103  are made of a suitable electrically conductive metal or other electrically conductive material, to conduct electrical current to or from electrical wires or other conductors (not shown) that are connected to a connection end  103 ′ of the electrical contacts  103 . For example, in the lamp embodiments of  FIGS. 8-12 , the connection ends  103 ′ of the pair of electrical contacts  103  may be connected to a corresponding pair of electrical wires that extend through hollow, interior channels of the lamp arm  112  and lamp leg  116 , and to a power source (such as, but not limited to, an electrical plug in a wall socket). 
     Friction-setting parts  104  provide a preset friction force against rotational motion about a pivot axis A of the joint structure, where the preset friction is sufficient to hold and maintain the position of the lamp head  114   a  (or other device) connected to the plug part  102  at any pivot angle within a range of pivotal motion. As described in more detail, below, with respect to  FIGS. 6  an  7 , each friction-setting part  104  is configured with a preset frictional resistance against rotation, which is set by the force by which components (components  104   a - d  of  FIG. 6 ) of the friction-setting parts are forced (squeezed) together during manufacture of the friction-setting parts  104 . 
     Bracket part  106  is configured to hold and connect the joint structure  100  to a member, such as, but not limited to an arm member  112  of a lamp as shown in  FIG. 8 . Bracket part  106  may be configured in a manner to minimize or avoid contributing to frictional forces against rotation about the pivot axis A. Bracket part  106  includes a pair of ring-shaped extension portions  106 ′ and a frame portion  106 ″. When assembled (as shown in  FIG. 2 ), a portion of a friction-setting part  104  extends through an opening in each respective ring-shaped extension portion  106 ′. In particular, each ring-shaped extension portion  106 ′ has a circular opening that is sufficiently large so as to minimize frictional interaction with rotating components of the friction-setting parts  104  or the plug part  102 . More specifically, the diameter of the opening in each ring-shaped extension portion  106 ′ is selected to be larger than components of the friction-setting parts  104  that extend through those openings, when the joint structure is assembled, to allow free rotation of those components of the friction-setting parts  104  with minimal or no interference from the extension portions  106 ′ of bracket part  106 . Bracket part  106  may be made of any suitably rigid material including, but not limited to plastic, metal, wood, ceramic or composite materials. 
     Screws  105  are used to fix and secure components of the joint structure  100  together, with minimal or no contribution to the frictional resistance about the pivot axis A provided by the friction-setting parts  104 . In one embodiment, each of the screws  105  has a shaft that includes a length portion  105 ′ with no threads and an end length portion  105 ″ with threads. The diameter of the length portion  105 ′ may be slightly larger than the diameter of the threaded end portion  105 ″, such that a small shoulder is provided at the interface of the length portions  105 ′ and  105 ″. The shaft of each screw  105  is configured to extend through a central opening in a respective friction-setting part  104 , through a central opening in a respective electrical contact  103 , through a central opening in the extension portions  106 ′ of bracket part  106 , and partially into a threaded opening ( 108 ′ in  FIGS. 3 and 4 ) of the plug part  102 . The threaded portion  105 ′ of each screw  105  is configured to thread into and connect with a respective threaded opening ( 108 ′ in  FIGS. 3 and 4 ) in the plug part  102 , to secure a friction-setting part  104 , electrical contact  103  and extension portion  106 ′ of bracket part  106  with one side of the plug part  102 . The threaded portion  105 ′ of each screw  105  may be threaded into one of the threaded opening ( 108 ′ in  FIGS. 3 and 4 ) of the plug part  102 , until the shoulder (at the interface of the threaded portion  105 ′ and the non-threaded portion  105 ″ of screw  105 ) abuts a surface of the plug part  102 . In this manner, each screw  105  may be sufficiently tightened to secure components of the joint structure together, yet also be prevented from further rotation once the shoulder of the screw  105  comes into contact with the plug part  102 , to minimize or prevent each screw  105  from contributing to frictional resistance against rotary motion about the pivot axis A of the joint structure. 
       FIG. 3  is a perspective, exploded view of the plug part  102  of the joint structure  100 , according to an embodiment of the present disclosure.  FIG. 4  is a perspective view of the plug part  102 , in an assembled form.  FIG. 5  is a partial cutaway view of the assembled plug part  102  of  FIG. 4 . In particular embodiments, the plug part  102  is configured to allow selective connection and disconnection (mechanical and electrical) of the lamp head  114   a  to the joint structure  100 . In addition, the plug part  102  allows the lamp head  114   a  to rotate about an axis B perpendicular to the pivot axis A of the joint structure, when the lamp head  114   a  is connected to the joint structure  100 . 
     Plug part  102  includes plug part base  108  having a fitting part  108   a  on each side (one side shown in the orientation in  FIG. 3 ), a pair of contact plates  107 , and coaxial connector rod  109 . The coaxial connector rod  109  has an inner conductor  109   a , insulator  109   b , outer conductor  109   c , conducting head part  109   d  and an insulating end cap part  109   e . The inner conductor  109   a  is a shaft having a longitudinal dimension. One end of the inner conductor  109   a  extends through an inner channel in the base  108  (as shown in  FIG. 5 ) and extends a short distance out of one side of the base  108  (the right side in  FIG. 5 ). In that manner, the inner conductor  109   a  is connected to and supported by the base  108  of the plug part  102 . The other end (free end) of the inner conductor  109   a  extends out from the other side (the left side in  FIG. 5 ) of the base  108 . 
     The insulator  109   b  is a tube-shaped member that has a longitudinal dimension and a hollow inner channel, through which the inner conductor  109   a  extends, when the plug part  102  is assembled. The insulator  109   a  and the insulator end cap part  109   e , each may be made of any suitable electrical insulating material, including, but not limited to plastic. The outer conductor  109   c  is a tube-shaped member having a longitudinal dimension and a hollow inner channel, through which the insulator  109   a  extends, when the plug part  102  is assembled. Each of the inner conductor  109   a , the outer conductor  109   c  and the conductive head part  109   d  is formed of or layered with an electrically conductive material, such as, but not limited to, one or more suitably conductive metals. 
     When assembled, the inner conductor  109   a  extends through the insulator  109   b , and the insulator  109   b  extends through the outer conductor  109   c , such that the free end of the inner conductor  109   a  extends out from an end of the insulator  109   b . In addition, that end  109   b ′ of the insulator  109   b  extends out from an end of the outer conductor  109   c , to provide an insulating separation between the conductive head part  109   d  and the outer conductor  109   c . The conductive head part  109   d  is provided over and in electrical contact with the extended free end of the inner conductor  109   a , and is separated from the outer conductor  109   c  by the end  109   b ′ of the insulator  109   b . The insulating end cap part  109   e  is connected to the extended free end of the inner conductor  109   a . Accordingly, when assembled, as shown in  FIG. 4 , the coaxial connector rod  109  includes the conductive head part  109   d  and outer conductor  109   c , each arranged in an exposed position, to come into electrical contact with a suitable conductor in a socket formed in the lamp head  114   a  (or other suitable device), when the lamp head  114   a  (or other suitable device) is mechanically connected to the connector rod  109 . In the illustrated embodiment the connector rod  109  is coaxial, in that it includes two conductors (the inner conductor  109   a  and the outer conductor  109   c ) arranged in a coaxial configuration. In other embodiments, more than two conductors may be employed in a coaxial arrangement. In yet further embodiments, the connector rod  109  may include one or more conductors arranged in linear or other non-coaxial arrangements. 
     Each fitting part  108   a  of the plug part base  108  is configured to engage with a correspondingly portion of the friction-setting part  104 . In particular embodiments, each fitting part  108   a  is configured with a particular shaped extension (generally rectangular shaped extension in  FIG. 3 ) that mates with a correspondingly shaped recess ( 104   e  in  FIG. 7   a ) in a portion of a friction-setting part  104 , to inhibit relative rotation between the plug part  102  and the friction-setting parts  104  (i.e., to lock those parts to rotate together), when the fitting parts  108   a  are mated with the friction-setting parts  104 , as shown in the assembled structure of  FIG. 4 . In the illustrated embodiment, the fitting part  108   a  has a rectangular-shaped extension that mates with a rectangular-shaped groove or recess in the friction-setting part  104 . However, in other embodiments, other suitable shaped extensions and grooves or recesses that inhibit relative rotation may be employed, instead of or in addition to the rectangular shapes shown in the drawings. Also, in other embodiments, the groove or recess may be provided on the fitting parts  108   a , while the mating extension may be provided on each of the friction-setting parts  104 . 
     Contact plates  107  serve to conduct electricity or electrical current to or from the coaxial connector rod  109 . Each of the contact plates  107  includes an extension portion  107 ′ that extends to a position in contact with a respective one of the inner and outer conductors  109   a  and  109   c . The extension portion  107 ′ on one of the contact plates  107  may have a different shape than the extension portion  107 ′ on the other contact plate  107 . The extension portion  107 ′ on one of the contact plates  107  extends into a channel formed in the base  108  to make electrical contact with the inner conductor  109   a ). The extension portion  107 ′ on the other contact plate  107  extends around one side of the base  108  (the right side in  FIG. 5 ) to make electrical contact with the exposed end of the outer conductor  109   c  (the end on the right side of  FIG. 5 ). In this manner, electrical connections can be made through contact plates  107  to the coaxial connector rod  109  and, in turn, to the lamp head  114   a  (or other device). When the joint structure  100  is assembled, the contact plates  107  are arranged in electrical contact with the contacts  103 , which are electrically connected to wires or other conductors (not shown), as discussed above. 
     The coaxial connector rod  109  is configured as a plug-like structure to plug into a correspondingly shaped socket in, for example, a lamp head  114   a  (or other device) that requires electric power. In other embodiments, the other device may include, for example, but not limited to, an audio device, speaker, solar panel, mobile charging device, electronic tool, electronic display or other communication device, or the like. Each fitting part  108   a  includes a threaded opening  108 ′ configured to receive the threaded end of a screw  105 , as described above. As can be seen in  FIG. 5 , two-pole electrical connections are made (via contact plates  107 ) to the inner and outer conductors  109   a  and  109   c  of the coaxial connector rod  109 . 
       FIG. 6  is a perspective exploded view of a friction-setting part  104  of the joint structure  100 , according to an embodiment of the present disclosure.  FIG. 7   a  is a perspective view of the friction-setting part  104 , in an assembled form.  FIG. 7   b  is a partial cutaway view of the friction-setting part  104  of  FIG. 7   a . Each friction-setting part  104  includes shaped part  104   a , friction inducing ring  104   b , linkage structure  104   c  and lathed part  104   d . Shaped part  104   a  has one end (leftwards facing in  FIG. 6 ) that has a groove or recess shaped to fittingly engage with the fitting part  108   a  of the plug part base  108  as described above. The other end of shaped part  104   a  (rightwards facing in  FIG. 6 ) has a tube like extension structure which extends through holes in inducing ring  104   b , linkage structure  104   c , and lathed part  104   d . The end of the tube structure on the rightwards-facing side of shaped part  104   a  may be flared out like a rivet to be secured with the lathed part  104   d , and to secure the components  104   a - d  of friction-setting part  104  together. 
     The friction inducing ring  104   b  translates rotational friction energy from the shaped part  104   a  to the linkage structure  104   c , and vice versa. This may be done by pressing the linkage structure  104   c  together with the friction inducing ring  104   b  (e.g., by flaring the end of the tube-like structure of the shaped part  104   a  enough to press the parts  104   b  and  104   c  together with enough pressure to allow those parts to rotate relative to each other, but also to impart a desired magnitude of frictional force against such relative rotation). In this manner, the frictional force against relative rotation of the parts  104   b  and  104   c  can be selected and set, for example, at the factory at the time of manufacturing the friction-setting part  104 . The magnitude of frictional force is selected, based on the weight of the member to be held by the joint structure (for example, the weight of the lamp head  114   a  in  FIG. 8 ). 
     The linkage structure  104   c  has a body portion  104   c ′ provided with a hole through which the tube-shaped portion of shaped part  104   a  extends. The linkage structure  104   c  also includes an extension portion  104   c ″ that includes a hole for connection to, for example, a balance rod  113   a  ( FIGS. 8-12 ), or any similar structure. When connected with the balance rod  113   a , the linkage structure  104   c  is held from rotating about axis A, at any given angular position of the arm  112  along a range of angular motion C shown in  FIG. 12 . As the angle C changes, the balance rod  113   a  rotates the linkage structure  104   c  by a corresponding amount, to maintain the orientation of the lamp head  114   a  in a manually set position (for example, a horizontal position, as shown in  FIG. 12 ). Accordingly, the lamp head  114   a  may remain in a preset orientation (e.g., horizontal orientation) while the arm  112  of the lamp is moved to change the angle C. 
     With the linkage structure  104   c  held from rotation (about axis A) by the balance rod  113   a , the shaped part  104   a  may be rotated relative to the linkage structure  104   c , against frictional force imparted by the friction inducing ring  104   b . The force by which the parts  104   a - d  are pressed together (and against the friction inducing ring  104   b ) by flaring the end of the tube-shaped portion of the shaped member  104   a , determines the amount of frictional force imparted against rotation of the shaped part  104   a  relative to the linkage structure  104   c . Accordingly, this force may be set at the factory, when the friction-setting part  104  is assembled. 
     The lathed part  104   d  functions with the tube-shaped portion of the shaped part  104   a  to secure all the components of the friction-setting part  104  together—namely, once the tube portion of shaped part  104   a  extends through the holes of the friction inducing ring  104   b , the hole of linkage joint structure  104   c , and through the hole of lathed part  104   d , the tube portion is then flared out to act as a rivet to secure all the components  104   a ,  104   b ,  104   c  and  104   d  together. In one embodiment, after all components  104   a - d  are assembled in this manner, the narrower, tube-shaped end of shaped part  104   a  will be stamped or pressed, as shown in  FIG. 7   b , in order to flare out and act as a rivet to securely fasten all the components  104   a - d  to one another to form side part  104 . The friction-setting part  104 , therefore, is configured to provide a consistent friction force that is introduced between shaped part  104   a  and linkage joint structure  104   c  by pressing on the friction inducing ring  104   b , regardless of the strength of any external forces applied on the friction inducing ring  104   b  (such as, for example, from screws). 
     In one embodiment, the center of the friction-setting part  104  has an open channel along the axis A, to allow a screw to go through, for example. As described above, screws  105  have a shaft portion that is smooth, with no threads. When assembled, that smooth, threadless shaft portion of the screws  105  extends through the open channel in the friction setting part  104 , so that the screws do not affect the frictional rotational resistance about axis A. 
       FIG. 8  is a perspective view of the joint structure  100  being applied to a lamp structure  110 , according to an embodiment of the present disclosure. Lamp structure  110  includes joint structure  100 , lateral body or arm  112 , lamp head  114   a , horizontal rods or pins  111   a , vertical screws  111   b , balance rod  113   a , balance rod connector portion  113   b , counter weight  114   b , sensor switch  115  (such as, but not limited to a motion or proximity sensor switch that switches power off when no motion is sensed within the proximity of the sensor for a defined period of time), leg  116 , touch or sliding dimmer switch  117 , and base  118 . A portion of a power cord (electrical conductor for electrical power) is shown at  119 . Joint structure  100  has been described above in  FIGS. 1-7 . Arm  112  is the lateral body of the lamp structure  110 . The combined weight of the lamp head  114   a  and arm  112  is balanced via the counter weight  114   b . The joint structure  100  is connected to the lamp head  114   a  by horizontal pins  111   a , and the joint structure  100  is connected to the arm  112  by vertical screws  111   b.    
     The balance rod  113   a  is a structure that runs parallel to the arm  112  and that also connects to the joint structure  100 , as described above, in order to maintain the positioning of the lamp head  114   a , so that the lamp head  114   a  stays in a given position once the user has moved it to a given position. 
     Arm  112  and balance rod connector portion  113   b  are connected to leg  116  by any suitable pivot joint, to allow the arm  112  to pivot along a pivot path C shown in  FIG. 12 . The leg  116  supports arm  112  and the balance rod connector portion  113   b . One or more switches  115  may be connected along the electrical conductors (not shown) in the leg  116 , to control power to the lamp structure  100 . Leg  116  is supported by base  118 . 
       FIG. 9  is a side view of the lamp structure having a joint structure  100 , according to an embodiment of the present disclosure. In  FIG. 9 , the bottom surface of lamp head  114   a  can be seen—showing an array of LEDs (light emitting diodes) arranged in a zig-zag pattern. In one embodiment, the LEDs may be arranged in a zig-zag pattern to most efficiently conserve resources. In one embodiment, the LEDs may be arranged in multiple rows or other patterns that may be deemed efficient or power-saving. Also in  FIG. 9 , it is shown that the lamp head  114   a  can be rotated about the axis B of the connector rod  109 . Thus, the joint structure  100  allows the lamp head  114   a  to not only pivot up and down, but also rotate in any angle due to its robust configuration. 
       FIG. 10  is another side view of the lamp structure  110  using the joint structure  100 , according to an embodiment of the present disclosure. In  FIG. 10 , the lamp head  114   a  is shown as pivoted about the axis A (extending into and out of the page) to be angled upwards relative to the horizontal position of  FIG. 9 .  FIG. 11  is yet another side view of the lamp structure having the joint structure  100 , according to an embodiment of the present disclosure. In  FIG. 11 , the lamp head  114   a  is shown as being positioned slightly upwards at an angle, and rotated 90 degrees so that the bottom surface of the lamp head  114   a  with its LEDs is facing outwards from the page. In  FIG. 12 , the lamp head  114   a  is shown as being horizontal, but positioned in a relatively high position (with the counter weight  114   b  in a low position). Once the user positions the lamp head  114   a  in such a position, the joint structure  100  maintains the orientation of the lamp head  114   a , even if the angle C of the arm  112  is changed. 
     After the lamp head  114   a  is assembled to a lamp structure  110 , the lamp head  114   a  can be rotated with two axes, or stay at a desired angle without requiring cumbersome electrical wires to run through the independent friction joint structure  100 . The lamp head  114   a  angle is determined by the angle of the plug part  102 , which is engaged to the linkage structure  104   c  through the friction-setting parts  104 , but can still be rotated against one another when the friction force is overcome. 
       FIG. 13  is a perspective exploded view of a joint structure  120 , according to another embodiment of the present disclosure.  FIG. 14  is a perspective view of the joint structure of  FIG. 13 , in an assembled form. Joint structure  120  includes base portion  122 , contact plates  127 , electrical contacts  123 , side parts  124 , screws  125 , and coaxial connector rod  129  which in turn includes inner conductor  129   a , insulator  128   b , outer conductor  129   c , second conductive part  129   d  and head  129   e . Base portion  122  has ends that fit through and engage with contact plates  127  and also electrical contacts  123 , which deliver or transfer electricity from elsewhere (an electrical cord, such as cord  119  described above) on the device to the coaxial connector rod  129 . Base portion  122  has two rod shaped extensions that fit through openings in the contact plates  127  and electrical contacts  123 . The side portions  124  also having openings through which the rod-shaped extensions of the base portion extend. The side portions  124  also can be secured to the rod-shaped extensions of the base portion  122  with screws  125 . The contact plates  127  and electrical contacts  123  can be made of any electrically conductive material, such as, but not limited to, for example copper, gold, silver or other suitable conductive material. The side parts  124  allow the frictional rotation to occur by pressure being exerted on its flanges or wing-like structures, which may be connected to a portion of a lamp structure or other fixed part of the structure. Thus, frictional rotational force is generated when base portion  122  and side parts  124  are squeezed or pressed together in order to move the entire friction joint structure  120 , and to also position the coaxial connector rod  129  at a specific angular position. The frictional resistance force of the joint structure  120  is provided by the opening on side part  124  being slightly smaller than the rod-shaped part of base portion  122 . In another embodiment, the frictional rotational force can be adjusted by tightening or loosening the screws  125 . The material of the side parts  124  can be, for example, plastic or any such similar material. 
     According to one embodiment, the independent friction structure of the present disclosure may be a joint structure used to connect two parts of a lamp to allow both a rotation along the joint axis and a second rotation perpendicular to the joint axis. The joint structure also contains electrical contacts for allowing an electrical connection through the joint structure without the use of an external wire. Two ends along the axis of the joint may be equipped with two independent friction joint structures or side parts, which introduce force to the joint to hold up a second part of the lamp. In one embodiment, an advantage of the independent joint friction structure is that the friction force it generates is independent from how tightly other components in the joint, or how tightened they are by a screw or how hard they are pressed against each other. Furthermore, the electrical contacts, which may be sandwiched in the middle of the joint structure, may not be strongly pressured against each other so as to potentially damage the contacts during movement of the independent friction joint structure. With the independent friction joint structures, the electrical contacts need not be pressured strongly against each other while the joint still maintains the force that it needs to cause frictional rotational force. The present disclosure may become particularly useful in the case of a lamp with a linkage joint design. The angle of the second part of the lamp remains the same when the lamp is moved, but its angle can still be adjusted if desired due to the friction joint structure being independent of the rest of the components. And all the above-described functionalities and more may be achieved in a single compact and lightweight joint structure. 
     While particular embodiments of the present disclosure have been shown and described, it will be obvious to those skilled in the art that the present disclosure is not limited to the particular embodiments shown and described and that changes and modifications may be made without departing from the spirit and scope of the appended claims.

Technology Classification (CPC): 5