An optical drive system includes a computer that monitors the current in an improved bias coil assembly in conjunction with a magnetomotive field generator to determine when a predetermined current threshold is exceeded. The bias coil assembly includes a wire coil wrapped around a center bar contained...http://www.google.com.tw/patents/US6317391?utm_source=gb-gplus-share專利 US6317391 - Optical disc system having current monitoring circuit with improved bias coil assembly and controller for laser driver and method for operating same
