High Torque Voice Coil Actuator for Hard Disk Drive
Original Publication Date: 1999-Oct-01
Included in the Prior Art Database: 2003-Jun-19
Published is a voice coil design for hard disk drive application. A saddle-shapped voice coil is proposed as opposed to the conventional flat coil used by the industry. The saddle-coil design avoids the penalties associated with the added inertia and resistance of the conductor that joins the outer ends of the two radial legs of the conventional flat coil. Therefore, the saddle- shaped VCM is able to achieve higher Kt/J (torque constant of VCM over mass moment of inertia) and improved access time. Figure 1 shows an isometric model of the saddle-shapped VCM. TheVCM consists of the saddle-shaped coil, permanent magnets, top and bottom steel plates, side plates and a center yoke. The saddle-shapped coil is placed at the air gap between magnets and the yoke. When controlled current flows through the coil, force is generated to move the suspension and head to a desired position. Figure 1. Schematic of the Saddle-Coil VCM Two cases are analyzed in Table 1 for comparison with the flat coil VCM. Case 1 is 15.5 mm VCM z-height with 3.5 inches disks. Case 2 has z-height of 31.7 mm and uses 3 inches disks.