Magnetic disk drive with compensation against disturbance
View Patent ↗A magnetic disk drive is to be provided wherein oscillations in thrust, conical and translational modes of a spindle caused by disturbance are to be damped to diminish a positioning error and thereby attain a high recording density and improved accessing performance. In one embodiment, there is provided a compensation circuit using acceleration or angular acceleration sensors, the sensors being disposed on a base, a cover or a PCB (printed circuit board) of a magnetic disk drive so that they can detect disturbance effectively, and wherein a mechanical system transfer characteristic of and other parameters in thrust, conical, or translational mode of a spindle are acquired or calculated by a processor and unnecessary oscillation in each mode is compensated. In another embodiment, to measure a transfer characteristic of the spindle in thrust mode and other parameters after installation of the magnetic disk drive in a case, piezoelectric elements are provided as one of oscillating means. The measurement may be made repeatedly at predetermined intervals.
1. A magnetic disk drive comprising:
a magnetic disk medium;
a spindle carrying said magnetic disk medium thereon rotatably;
a spindle motor configured to impart a rotational drive force to said spindle;
a magnetic head configured to write or read information to or from said magnetic disk medium;
a slider carrying said magnetic head thereon;
a suspension connected to said slider to support the slider;
a carriage connected to said suspension to support the suspension;
a coil supported by said carriage;
an electronic circuit configured to control said spindle motor, said magnetic head, or said coil;
a sensor to detect an acceleration having a component perpendicular to a surface of said magnetic disk medium; and
a processor configured to receive outputs of said electronic circuit and said sensor and to provide a compensation signal to the coil based on the outputs of the said electronic circuit and said sensor,
wherein a positioning error between the magnetic head and a target position is diminished using the output of said sensor.
2. A magnetic disk drive according to claim 1 , further comprising a bearing to guide said carriage movably in a radial direction of said magnetic disk medium.
3. A magnetic disk drive according to claim 1 , further comprising a base to support said spindle rotatably through a bearing.
4. A magnetic disk drive according to claim 3 , further comprising a magnetic circuit paired with said coil to drive said carriage, said magnetic circuit being supported by said base.
5. A magnetic disk drive according to claim 3 , further comprising a cover paired with said base to maintain a hermetically sealed condition.
6. A magnetic disk drive according to claim 5 , further comprising an FPC or substrate carrying said electronic circuit thereon.
7. A magnetic disk drive according to claim 6 , wherein said sensor is fixed to said base, said cover, or said FPC or said substrate.
8. A magnetic disk drive according to claim 1 , wherein the output of said sensor is inputted and subjected to transformation, then an electric current is added to said coil.
9. A magnetic disk drive comprising:
a magnetic disk medium;
a spindle carrying said magnetic disk medium thereon rotatably;
a spindle motor configured to impart a rotational drive force to said spindle;
a magnetic head configured to write or read information to or from said magnetic disk medium;
a slider carrying said magnetic head thereon;
a suspension connected to said slider to support the slider;
a carriage connected to said suspension to support the suspension;
a coil supported by said carriage;
an electronic circuit configured to control said spindle motor, said magnetic head, or said coil;
a sensor to detect an acceleration;
an oscillating mechanism configured to provide the acceleration; and
a processor configured to:
control said oscillating mechanism by sending one or more electrical signals to the oscillating mechanism to cause the oscillating mechanism to oscillate, thereby creating the acceleration;
receive outputs of said electronic circuit and said sensor while the oscillating mechanism is oscillating; and
calculate a transfer characteristic of the magnetic disk drive caused by the acceleration based on the outputs of said electronic circuit and said sensor.
10. A magnetic disk drive according to claim 9 , further comprising a bearing to guide said carriage movably in a radial direction of said magnetic disk medium.
11. A magnetic disk drive according to claim 9 , further comprising a base to support said spindle rotatably through a bearing.
12. A magnetic disk drive according to claim 11 , further comprising a magnetic circuit paired with said coil to drive said carriage, said magnetic circuit being supported by said base.
13. A magnetic disk drive according to claim 11 , further comprising a cover paired with said base to maintain a hermetically sealed condition.
14. A magnetic disk drive according to claim 13 , further comprising an FPC or substrate carrying said electronic circuit thereon.
15. A magnetic disk drive according to claim 14 , wherein said oscillating mechanism is fixed to said base, said cover, or said FPC or said substrate.
16. A magnetic disk drive according to claim 14 , wherein a part of said oscillating mechanism is interposed between said base, said cover, or said FPC or said substrate, and a case which carries the magnetic disk drive thereon.
17. A magnetic disk drive according to claim 9 , wherein a part of said oscillating mechanism has a counter mass on the side opposite to a fixed end portion of the oscillating mechanism.
18. A magnetic disk drive according to claim 9 , wherein the oscillating mechanism comprises one or more piezoelectric elements.
19. A magnetic disk drive according to claim 18 , wherein the one or more piezoelectric elements are mounted in the same position and direction as the sensor.
20. A magnetic disk drive comprising:
a magnetic disk medium;
a spindle carrying said magnetic disk medium thereon rotatably;
a spindle motor configured to impart a rotational drive force to said spindle;
a magnetic head configured to write or read information to or from said magnetic disk medium;
a slider carrying said magnetic head thereon;
a suspension connected to said slider to support the slider;
a carriage connected to said suspension to support the suspension;
a coil supported by said carriage;
an electronic circuit configured to control said spindle motor, said magnetic head, or said coil;
a sensor to detect an acceleration;
oscillating means for providing the acceleration; and
a processor configured to:
control said oscillating means by sending one or more electrical signals the oscillating means to cause the oscillating means to oscillate;
receive outputs of said electronic circuit and said sensor while the oscillating means is oscillating; and
calculate a transfer characteristic of the magnetic disk drive caused by the acceleration based on the outputs of said electronic circuit and said sensor.
21. A magnetic disk drive according to claim 9 , wherein the processor is further configured to calculate a transfer characteristic when the oscillating mechanism is activated.
22. A magnetic disk drive according to claim 9 , wherein the acceleration has a component perpendicular to a surface of said magnetic disk medium.