Magnetic frictional coupler

Abstract

A coupler includes a first member having a first engagement surface and a second member having a second engagement surface disposed for relative positioning of the first and second members along a line of adjustment. One or more magnetic elements are arranged on the first and second members to establish a magnetic flux between the first engagement surface and the second engagement surface, and thereby establishing a frictional force tending to hold the relative positions of the first and second members. The magnetic flux varies as a function of relative position of the first and second members along the line of adjustment, and has peaks at a plurality of detent positions along the line of adjustment.

What is claimed is: 
     
         1 . A magnetic coupler for translational adjustment, comprising:
 a first member having a first engagement surface, and a second member having a second engagement surface, the second engagement surface disposed for translational movement relative to the first engagement surface of the first member along a line of adjustment to change a length of the coupler;   a first set of magnetic elements fixed on the first member, the first set of magnetic elements linearly arranged along the line of adjustment;   a second set of magnetic elements fixed on the second member,
 wherein at least one of the first set of magnetic elements is arranged to overlap with at least one of the second set of magnetic elements at a detent position of a plurality of detent positions, and 
 wherein the first set of magnetic elements and the second set of magnetic elements establish a magnetic flux attracting the first engagement surface to the second engagement surface,
 the magnetic flux varying as a function of relative position of the first member and the second member along the line of adjustment and having peaks at the plurality of detent positions along the line of adjustment; and 
 
   an elongated magnetic element disposed along the line of adjustment on the first member, and a complementary elongated magnetic element on the second member, wherein the elongated magnetic element is arranged to overlap with the complementary elongated magnetic element along the line of adjustment.   
     
     
         2 . The magnetic coupler of  claim 1 , wherein the elongated magnetic element is a magnetic strip. 
     
     
         3 . The magnetic coupler of  claim 1 , further comprising:
 a guide to confine relative movement of the first member and the second member to translational motion along the line of adjustment.   
     
     
         4 . The magnetic coupler of  claim 1 , wherein the first set of magnetic elements are arranged with a magnetic pole proximal to the first engagement surface and an opposite magnetic pole distal from the first engagement surface. 
     
     
         5 . The magnetic coupler of  claim 4 , wherein the magnetic poles, of the first set of magnetic elements, and proximal to the first engagement surface are disposed in a first pattern corresponding to detent positions in the plurality of detent positions along the line of adjustment. 
     
     
         6 . The magnetic coupler of  claim 5 , wherein:
 the second set of magnetic elements arranged with respective magnetic poles proximal to the second engagement surface and opposite magnetic poles distal from the second engagement surface, and   the respective magnetic poles of the second set of magnetic elements proximal to the second engagement surface are disposed in a second pattern to maintain the second member at one of the plurality of detent positions of the first pattern by engaging with at least one of the magnetic poles of the first set of magnetic elements.   
     
     
         7 . The magnetic coupler of  claim 1 , further comprising: a non-magnetic spacer disposed between the first engagement surface and the second engagement surface. 
     
     
         8 . A magnetic coupler comprising:
 a first member having a first engagement surface;   a second member having a second engagement surface, the second engagement surface disposed for rotational movement relative to the first engagement surface along a line of adjustment;   a pivot pin and bearing member coupled to the first member and second member and orthogonal to the first engagement surface and second engagement surface, and wherein the line of adjustment comprises an arc around the pivot pin;   a first set of magnetic elements on the first member are disposed in a first pattern corresponding to detent positions in a plurality of detent positions along the line of adjustment; and   a second set of magnetic elements on the second member including an arcuate magnetic element around the pivot pin, and a bar magnetic element disposed at an angular position around the pivot pin, wherein the second set of magnetic elements comprise magnetic poles disposed in a second pattern to maintain the second member at one of the plurality of detent positions of the first pattern,   wherein the first set of magnet elements and the second set of magnetic elements arranged to establish a magnetic flux between the first engagement surface and the second engagement surface, the magnetic flux varying as a function of relative position of the first member and the second member along the line of adjustment, and having peaks at the plurality of detent positions along the line of adjustment.   
     
     
         9 . The magnetic coupler of  claim 8 , wherein the first engagement surface and the second engagement surface are flat surfaces. 
     
     
         10 . The magnetic coupler of  claim 8 , wherein:
 the first set of magnetic elements are arranged with a magnetic pole proximal to the first engagement surface and an opposite magnetic pole distal from the first engagement surface, and   the magnetic poles of the second set of magnetic elements are arranged proximal to the second engagement surface and opposite magnetic poles distal from the second engagement surface.   
     
     
         11 . The magnetic coupler of  claim 8 , further comprising a guide coupled to the first member and the second member, and the line of adjustment comprises an arc along the guide. 
     
     
         12 . The magnetic coupler of  claim 8 , further including an elongated magnetic strip disposed along the line of adjustment on the first member. 
     
     
         13 . The magnetic coupler of  claim 8 , including a non-magnetic spacer disposed between, and in frictional contact with, the first engagement surface and the second engagement surface. 
     
     
         14 . The magnetic coupler of  claim 8 , wherein the first set of magnetic elements comprises a patterned magnetic film fixed on the first member having north and south poles in a pattern proximal to the first engagement surface. 
     
     
         15 . The magnetic coupler of  claim 8 , wherein the magnetic flux is an attracting force in some relative positions of the first member and the second member and a repelling force in at least one other relative position. 
     
     
         16 . A magnetic coupler comprising:
 a first member having a first engagement surface, wherein the first member comprises a base, and a protruding structure on the base having a cylindrical outside surface, wherein the first engagement surface is on the cylindrical outside surface;   a second member having a second engagement surface, the second engagement surface disposed for movement relative to the first engagement surface along a line of adjustment, wherein the second member comprises an opening having a cylindrical inside surface, and wherein the second engagement surface is on the cylindrical inside surface;   a first set of magnetic elements fixed on the first member; and   a second set of magnetic elements fixed on the second member,   wherein the first set of magnetic elements and the second set of magnetic elements are arranged to establish a magnetic flux between the first engagement surface and the second engagement surface, the magnetic flux varying as a function of relative position of the first member and second member along the line of adjustment, and having peaks at a plurality of detent positions along the line of adjustment, and   wherein the protruding structure has an opening inside the cylindrical outside surface.   
     
     
         17 . The magnetic coupler of  claim 16 , wherein the line of adjustment comprises an arc around the cylindrical outside surface. 
     
     
         18 . The magnetic coupler of  claim 16 , including a non-magnetic spacer disposed between the first and second engagement surfaces. 
     
     
         19 . The magnetic coupler of  claim 16 , wherein:
 the first set of magnetic elements comprises a plurality of magnets fixed on the first member, and arranged with a magnetic pole proximal to the first engagement surface and an opposite magnetic pole distal from the first engagement surface, and wherein the magnetic poles of the magnets proximal to the first engagement surface are disposed in a pattern corresponding to detent positions in the plurality of detent positions along the line of adjustment, and   the second set of magnetic elements comprises a complementary magnetic element on the second member, arranged to increase the magnetic flux at the plurality of detent positions.   
     
     
         20 . The magnetic coupler of  claim 16 , wherein one or more of the first set of magnetic elements comprise an elongated magnetic strip disposed along the cylindrical outside surface on the first member, and the second set of magnetic elements comprises a complementary elongated magnetic element on the second member.