Design opmization of a moving magnet disk drive actuator with minimized detrimental electromagnetic forces

Introduction Advances in map ti^ recording head and media over the last decade hate pushed recording rlen,tiy up io a poml uhcre funher improvement i s Itkcl) to hc impeded h) mechanical constrainti l'mently. the WYO bandwidth of most cnnvcnlional head positioning ,)stem i s lirmtcd by thr In-plane rcronance modes of the actuator mechanism For a typrcal 3 5-inch drive actuator, the lowest t n p l ~ ~ monance. referred a.. the QR mode (quai-rigid body mude). (X'CUIS between 3 10 5 MIL. This IS due to the ela5ticity of the pirot h n g and Ibe mass of the moving pans of the actuator Moi l IlDD today UVP a moiinp voicciod inutur IO drive he actuatnr arm carrying the readlwnte heads. Howcvcr. the driving lurcc produced b) the conventional moving voice coil motor has a large tn.planc component In the seek direction. This creates rubstanual reaction furcc at thr pivot k m n g which cm pnlcnually cxcitcs the QR mode of the actuator Ihe Q K made, i f exited. causes undesirable vibration of the arm in the data track acehng diwcuun. Thir csuccs difficulty in head positioning Juring mck following and l irmta the bandwidth of the servo system T h i r paper prrscnls a novel moving -et dctyillor which substantially solres the abow described d i s h a n t a g , and provides w improve actuator mechamism for high density recording rn hard disk dnves