Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
1998-10-30
2001-08-14
Shoap, Allan N. (Department: 3729)
Metal working
Method of mechanical manufacture
Electrical device making
C029S609000, C029S607000, C335S284000
Reexamination Certificate
active
06272729
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to the fabrication of multipole permanent magnet rotors and, more particularly, to the fabrication of very high field magnetized micro-rotors for use in stepper motors, and the method of making same.
BACKGROUND OF THE INVENTION
Multipole cylindrical permanent magnets are widely used as rotors for conventional stepper motors. Conventional stepper motor rotors are as small as 0.2″ in diameter with 8 alternating magnetic poles around their circumference. These rotors can be fabricated and polarized using standard technology. Specifically, such rotors are fabricated from a cylinder of magnetic material and polarized using fixtures made by threading standard gauge wire through holes in a block of phenolic or other suitable insulating material. The threading of the wire through the holes is done in a serpentine pattern generating the alternating poles of the rotor when a high current pulse is fired through the wires. This method is applicable when the requirements for the number of poles and the pole pitch are modest. However, as the number of poles increase, for example a 20 pole roller having a diameter of only 0.13″, the pitch must be 0.2″; an increase by a factor of 10 in making the magnetized poles closer than that attained by use of the magnetizing fixtures known in the prior art.
SUMMARY OF THE INVENTION
The present invention is directed to overcoming one or more of the problems set forth above. In summary, one aspect of the present invention is directed to a permanent magnet micro-rotor comprising: a) a cylinder of magnetic material having a plurality of spaced-apart slots disposed around the periphery of said magnetic material; said magnetic material is magnetized by placing conductors in the spaced apart slots and energizing the conductors so that magnetic poles are formed between the spaced-apart slots.
These and other aspects, objects, features and advantages of the present invention will be more clearly understood and appreciated from a review of the following detailed description of the preferred embodiments and appended claims, and by reference to the accompanying drawings.
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Furlani Edward P.
Kenny Gary R.
Reznik Svetlana
Eastman Kodak Company
Shoap Allan N.
Smith Sean
Woods David M.
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