Low-profile spindle motor for 5-mm-height PCMCIA disk drive

Abstract

We d e v e l o p e d a n e w s p i n d l e m o t o r with a unique structure f o r PCMCIA Type-II magnetic disk drives. The m o t o r has extremely s m a l l d i m e n s i o n s and has t o be h i g h l y e f f i c i e n t . The magnetic circuit has radial g a p s , axial c o r e s , and a p o l e -a n i s o t r o p i c ring magnet. We found that the core material and the j o i n t s o f the core and y o k e s t r o n g l y influenced the m o t o r e f f i c i e n c y and the torque c o n s t a n t . We a c h i e v e d a m o t o r e f f i c i e n c y o f 5 t i m e s greater than the conventional axial gap m o t o r .