Some novel ideas for disk drive spindle motors

The spindle motor is one of the most important elements in a disk drive, and in many ways determines the drive's capacity and performance. The motor relates the disk and media, for hard disk drive usually at 3600 rpm, but for floppy disks mostly at 300-360 rpm. However, the trend is to go for higher speeds, as this reduces the latency and improves the seek time and the rate of data transfer. Manufacturers are trying to pack more disks into their drives. Some 5.25 inch format drives already have more than 4 GB of memory, and small-format drives are getting increasingly smaller. Great efforts are being made to reduce the size of drives for new formats, portable and pcn-based computers. In both cases, there is an increased demand on the motor capability. It is also important to understand that the read/write heads, if not moving, tend to stick to the disk. As a result, designers are always looking for ways and means to increase the starting torque of the motor. Efforts are also made to achieve higher speeds and reduce the size of the spindle motor. Some of these requirements are conflicting and very difficult to meet. Unlike most industrial motors, disk drive spindle motors have to comply with a host of special requirements, like particle generation, very low spindle run-out, contamination and outgassing problems, etc.<>