The present invention relates to an improvement in a head drive mechanism for a disk apparatus.
First, the structure of a conventional head drive mechanism will be described, with reference to FIG. 1. FIG. 1 is a schematic exploded perspective view of coil assembly 1 and magnet section 2, which together constitute the main part of a rotary actuator for a conventional magnetic disk apparatus. Assembly 2 is arranged as follows:
Conductive wire 12 is wound into a coil, to thereby constitute coil 11. Coil bobbin 13 for holding coil 11 is mounted therearound. The outermost end 14 of wire 12 is soldered to conductive pin 15. The innermost end of wire 12 is guided along the upper surface of coil 11 and is soldered to conductive pin 17.
Magnet section 2 is arranged as follows:
A pair of yokes 23 and 26 are arranged so as to oppose each other. Four sector-shaped magnets 21, 22, 24, and 25 having an identical shape are mounted as pairs 21, 22 and 24, 25 on yokes 23 and 26, respectively. Magnets 21, 22, 24, and 25 and yokes 23 and 26 constitute a closed-loop magnetic circuit.
Coil assembly 1, shown in FIG. 1, is inserted in a space in magnet section 2. An actuator support (not shown) and a head arm are fixed on coil bobbin 13. A magnetic head is mounted at the distal end of the head arm, to perform data read/write accessing.
The operation of the structure shown in FIG. 1 will now be described below.
A drive current is supplied to coil 11 via pins 15 and 17. In response to the drive current, coil 11 generates a magnetic flux. The interaction between the magnetic flux generated by coil 11 and that generated by magnets 21, 22, 24, and 25 applies an electromagnetic force to coil assembly 1. Assembly 1 is then rotated about a shaft (not shown) at a predetermined angle. In this way, the heads are positioned at a predetermined track of a disk-like recording medium.
Along with an increase in the operating speed of magnetic disk apparatuses in recent years, demand has arisen for an increase in the seek speed of the actuators used in the magnetic disk apparatuses.