| 摘要 |
A servo circuit for a magnetic disk apparatus having a target speed generating circuit (13a) for generating a target speed in accordance with an amount of movement; a speed signal producing circuit (14) for producing a real speed from a position signal from a servo object (11); and a speed error generating circuit (15) for controlling the speed of the servo object (1) based on an error between the target speed and the real speed; in accordance with the amount of movement, acceleration and then deceleration control being performed for positioning at the target position, wherein provision is made of an acceleration detection circuit (19) for detecting acceleration in progress from an output of the speed error generating circuit (15), and an acceleration-in-progress detection signal of the acceleration detection generating detection circuit (12) is used for changing a cutoff frequency of the speed error generating circuit (15) between acceleration in progress and deceleration in progress. Also, a servo circuit for a magnetic disk apparatus provided with a servo loop which supplies a seek current based on an error signal (DE) between a target speed (E1) and real speed (E2) to a voice coil motor (210) and performs speed control on a head carriage (212) toward a target track position, provided in the servo loop with an addition means for adding a predetermined addition value (Ecc) to the error signal (DE) at the stage of acceleration after a start of the speed control or provided, at an amplifier circuit (316) positioned at a latter stage of an amplifier circuit (314) for determining the frequency characteristics of the servo loop, with a gain switching means (318) which switches a preset gain (G1) to a larger gain (G2) between the start of a seek operation and the completion of acceleration. Further, a servo circuit for a magnetic disk apparatus which performs speed control over a servo object based on a speed error between a target speed and a real speed, provided with a speed signal generating circuit (414A) which generates the real speed of the servo object based on a position signal of the servo object, the speed signal generating circuit provided with a band changing circuit (4140) for changing the band of a speed signal producing circuit (414B) in accordance with a seek difference. |
