Abstract: A carriage assembly for use with high track density flexible magnetic disk drive systems that comprises a base carriage, which supports a permanent magnet, driven by a stepper motor used to achieve course positioning of the carriage assembly. A fine position acutator is attached to the base carriage by a pair of flexible metal strips that permit movement of the actuator relative to the base carriage for fine positioning of a pair of magnetic heads. The fine position actuator comprises a voice coil bobbin, an upper arm which supports an upper magnetic read/write head, a lower arm which supports a lower magnetic read/write head and a hinge which connects the upper and lower arms. An optical servo tracking assembly mounted on the actuator senses optical servo tracking information on a surface of a magnetic disk and generates a signal which activates the voice coil bobbin causing movement of the actuator relative to the base carriage.

Abstract: A magnetic information storage medium, such as a floppy or rigid magnetic disk having a plurality of indelible grooves inscribed on a surface of the medium to function as optical servo tracks. The grooves can be in the form of a plurality of continuous or noncontinuous concentric circles. The grooves can also be a continuous spiral or a plurality of continuous concentric circles having non-constant widths and/or depths.