Positioning apparatus for hard disk servowriter

Abstract

A servowriter positioning apparatus for hard disk drives comprises an optical read head 2 for directing three focussed light beams on grating sections formed at the end of a grating member 1 connected to the servo write head(s) 3 in order to indicate the position and movement of the head(s) 3. The optical read head 2 may be based on CD or DVD technology. The servo write head(s) 3 are mounted on an actuator arm 5 to which the grating member 1 is fixed for rotation therewith and which are both driven in rotation by a rotary actuator. The grating member 1 comprises two grating sections 11,12 separated by a smooth section 13 for generating a focus error correction signal. The apparatus of the invention can be used to sense and control the position and movement of the servo write heads, or of the read/write heads of the hard disk themselves, thus eliminating the need for any servo pattern.

Dependencies are inferred from the claim text.