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Brushless DC Motor for Disc File Disclosure Number: IPCOM000040021D
Original Publication Date: 1987-Sep-01
Included in the Prior Art Database: 2005-Feb-01

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Dance, WG Jeram, R [+details]


In a brushless DC motor, Hall effect switches for commutation are normally mounted above stator laminations. Here, the Hall switches are lowered into a recess in the stator laminations to reduce the overall motor height while maintaining performance. A problem in a small compact disc file where space is at a premium is motor height. Fig. 1 shows the normal arrangement Magnets 1 are fixed to rotor hub 2. Hall switches 3 are mounted above stator laminations 4. In order to operate satisfactorily, Hall switches 3 need to receive sufficient levels of magnetic flux. Thus, the height of rotor magnet 1 must be sufficient to provide the flux levels required.