Permanent magnet bulk degausser

Abstract

One or more pairs of magnet assemblages ( 14 and 16 ) are provided with magnetized segments ( 21 - 30 ) arranged in a Halbach-like array. The magnet assemblages ( 14 and 16 ) define a gap ( 18 ) through which magnetic data storage media ( 12 ) pass in a direction ( 20 ) across the segments ( 21 - 30 ). The magnetized sides ( 36 ) of the magnet assemblages ( 14 and 16 ) face each other thereby creating strong magnetic fields which degauss the magnetic data storage media ( 12 ) passing through the gap ( 18 ).

1 . An apparatus for erasing magnetic storage media comprising: 
 at least one pair of magnet assemblages;    each magnet assemblage comprising at least three segments;    each segment having a direction of magnetization approximately perpendicular to the longest dimension of the segment;    at least one magnet assemblage arranged such that the segments are aligned adjacently with the direction of magnetization of each successive segment rotated by approximately 90 degrees relative to the previous segment wherein the direction of magnetization for a segment repeats every fifth segment if the magnet assemblage includes five or more segments; and    a gap defined by each pair of magnet assemblages such that a magnetic field created by each assemblage exists at least partially in the gap.    
   
   
       2 . The apparatus of  claim 1  wherein at least one segment is an integral piece.  
   
   
       3 . The apparatus of  claim 1  wherein at least one segment comprises a plurality of permanent magnets arranged in at least one row such that each permanent magnet in the segment has a direction of magnetization pointing in the same direction.  
   
   
       4 . The apparatus of  claim 3  wherein at least one permanent magnet includes a cross section in the shape of a square and a height that is one half of a length of a side of the square with the direction of magnetization in the direction of the height of the permanent magnet.  
   
   
       5 . The apparatus of  claim 3  wherein at least one permanent magnet is a neodymium-iron-boron block.  
   
   
       6 . The apparatus of  claim 3  wherein the direction of magnetization for each segment is either approximately perpendicular to or approximately parallel to the gap and each segment with a direction of magnetization substantially perpendicular to the gap includes at least two rows of permanent magnets and each segment with a direction of magnetization substantially parallel to the gap includes fewer rows of permanent magnets than the segments with a direction of magnetization substantially perpendicular to the gap.  
   
   
       7 . The apparatus of  claim 1  wherein the direction of magnetization for each segment is oblique relative to the gap.  
   
   
       8 . The apparatus of  claim 7  wherein at least one pair of magnet assemblages is aligned such that segments from each magnet assemblage line up across the gap and that each segment mirrors the direction of magnetization of the segment directly across the gap.  
   
   
       9 . The apparatus of  claim 1  wherein the direction of magnetization for at least one segment is either approximately perpendicular to or approximately parallel to the gap.  
   
   
       10 . The apparatus of  claim 9  wherein each pair of magnet assemblages includes the same number of segments.  
   
   
       11 . The apparatus of  claim 10  wherein each pair of magnet assemblages is aligned such that segments from each magnet assemblage line up across the gap and that each segment mirrors the direction of magnetization of the segment directly across the gap.  
   
   
       12 . The apparatus of  claim 10  wherein each pair of magnet assemblages is aligned such that segments from each magnet assemblage line up across the gap and that each segment with a direction of magnetization approximately perpendicular to the gap points in approximately the same direction as the segment across the gap.  
   
   
       13 . The apparatus of  claim 10  wherein at least one pair of magnet assemblages is aligned such that segments from each magnet assemblage line up across the gap and that each segment mirrors the direction of magnetization of the segment directly across the gap, at least one pair of magnet assemblages is aligned such that segments from each magnet assemblage line up across the gap and that each segment with a direction of magnetization approximately perpendicular to the gap points in approximately the same direction as the segment across the gap, and the gaps for each pair of magnet assemblages line up such that magnetic media storage may pass directly from one gap to the other.  
   
   
       14 . The apparatus of  claim 1  wherein at least one pair of magnet assemblages is aligned such that segments from at least one magnet assemblage are offset relative to the segments across the gap.  
   
   
       15 . The apparatus of  claim 1  wherein at least one magnet assemblage comprises a Halbach array across the segments.  
   
   
       16 . The apparatus of  claim 1  further comprising an adjustable frame structure securing the magnet assemblages such that the width of the gap between the magnet assemblages can be adjusted.  
   
   
       17 . The apparatus of  claim 1  further comprising a lateral adjustable frame structure securing the magnet assemblages such that the lateral position of the magnet assemblages can be adjusted.  
   
   
       18 . The apparatus of  claim 1  wherein the two magnet assemblages of at least one pair of magnet assemblages have different numbers of segments.  
   
   
       19 . An apparatus for erasing magnetic storage media comprising: 
 at least two pairs of magnet assemblages;    each magnet assemblage comprising at least three segments;    each segment having a direction of magnetization approximately perpendicular to the longest dimension of the segment;    each magnet assemblage arranged such that the segments are aligned adjacently with the direction of magnetization of each successive segment rotated by approximately 90 degrees relative to the previous segment wherein the direction of magnetization for a segment repeats every fifth segment if the magnet assemblage includes five or more segments;    a gap defined by each pair of magnet assemblages such that a magnetic field created by each assemblage exists at least partially in the gap; and    at least one of the at least two pairs of magnet assemblages arranged with the segments of the first magnet assemblage aligned at 90 degrees relative to the segments of the second magnet assemblage and with the segments of both magnet assemblages at a 45 degree angle relative to a magnetic storage media path through each gap defined by each pair of magnet assemblages.    
   
   
       20 . The apparatus of  claim 19  wherein the at least one of the at least two pairs of magnet assemblages are further arranged such that each of the magnet assemblages are arranged in repulsion.  
   
   
       21 . The apparatus of  claim 19  further comprising: 
 at least one additional pair of magnet assemblages disposed on the magnetic storage media path;    each magnet assemblage of the at least one additional pair comprising at least three segments;    each segment of the magnet assemblages of the at least one additional pair having a direction of magnetization approximately perpendicular to the longest dimension of the segment;    each magnet assemblage of the at least one additional pair arranged such that the segments are aligned adjacently with the direction of magnetization of each successive segment rotated by approximately 90 degrees relative to the previous segment wherein the direction of magnetization for a segment repeats every fifth segment if the magnet assemblage includes five or more segments; and    the at least one additional pair of magnet assemblages arranged in attraction.