A biopsy device having a translating and rotating cutter is disclosed. The translational speed of the cutter is varied using a variable pitch member. The variable pitch member can include a shaft having a relatively coarse threaded portion for rapid cutter advance and a relatively finer threaded portion...http://www.google.com.hk/patents/US7025732?utm_source=gb-gplus-share專利 US7025732 - Biopsy device with variable speed cutter advance
