Actuator retract circuit for dual speed hard disk drive
AssigneeHitachi Global Storage Technologies Netherlands B.V.
InventorsThomas Robert Albrecht, Satoshi Yamamoto
Life of this patent
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Abstract
A dual speed hard drive system with an actuator retract system capable of retracting the actuator at approximately the same speed and power in both speed modes. In one embodiment, the control of resistance is used to control the amount of back-emf current supplied to the voice coil motor. In another embodiment, the circuit selectively restrict which spindle motor winding is allowed to supply back-emf current to the voice coil motor. In yet another embodiment, a voltage or a current regulator is used to control the current flowing into the voice coil motor. In all three embodiments, the amount of back-emf current supplied to the voice coil motor is proportional to the power and speed at which the actuator is being retracted.
Claims44
A disk drive system comprising:
- one or more data disks;
- an actuator;
- a parking ramp for receiving said actuator;
- a spindle motor for rotating one or more data disks operable in two or more different speed modes, said spindle motor having windings for two or more phases;
- an actuator retract circuit electrically coupled to said actuator;
- wherein said actuator retract circuit retracts said actuator to said parking ramp during a power-off condition;
- wherein said actuator retract circuit utilizes back-emf generated by said spindle motor to retract said actuator;
- wherein said actuator retract circuit retracts said actuator at approximately the same speed in all of said two or more speed modes.
An actuator retract circuit system comprising:
- a transistor functioning as a switch responsive to the removal of power to the spindle motor and a plurality of paired bipolar transistors, each pair of transistors being associated with a different one of said windings, each transistor having its emitter-base junction connected in series between its associated winding and said switch and its emitter-collector junction connected in series between it associated winding and said voice motor coil;
- whereby in response to closing of the transistor functioning as a switch the freely rotating spindle motor generates back-emf current through successive windings to emitter-base junctions of associated transistors to successively turn on said transistors and thereby direct remaining back-emf current from said windings to said voice coil motor;
- a first resistor connected in series with said voice coil motor;
- a second resistor connected in series with said voice coil motor and in parallel with first resistor;
- a transistor connected in series with said second resistor;
- wherein when said transistor turns on, back-emf current from said windings will be allowed to flow through said second resistor and into said voice coil motor;
- a signal output from a main processor unit to a gate of said transistor;
- a capacitor with one terminal coupled with said signal output and the other terminal coupled to ground;
- wherein said capacitor is charged by said signal output;
- wherein said capacitor discharges when power is removed from said spindle motor;
- wherein said discharge to said gate of said transistor turns on said transistor when power is removed from said spindle motor;
- a resistor with one terminal coupled with said signal output and the other terminal coupled to ground, in parallel with said capacitor.
A phase selection retract circuit comprising:
- one or more transistors functioning as switches responsive to the removal of power to the spindle motor and a plurality of paired bipolar transistors, each pair of transistors being associated with a different one of said windings, each transistor having its emitter-base junction connected in series between its associated winding and said switch and its emitter-collector junction connected in series between it associated winding and said voice motor coil;
- whereby in response to closing of the transistor functioning as a switch the freely rotating spindle motor generates back-emf current through successive windings to emitter-base junctions of associated transistors to successively turn on said transistors and thereby direct remaining back-emf current from said windings to said voice coil motor;
- one or more output signals which control one or more of said transistors;
- one or more capacitors coupled with said output signals;
- wherein said capacitors supply voltage to one or more of said transistors during said power off condition.
A voltage regulator actuator retract circuit comprising:
- a rectifier circuit;
- wherein the current output of said rectifier circuit is supplied to said voice coil motor;
- an operational amplifier for comparing a voltage output from said rectifier circuit to a voltage reference;
- wherein an output of said operational amplifier is dependent on said comparison of voltages;
- a transistor coupled in series with said current output of said rectifier circuit;
- wherein said transistor acts as a switch to prevent said current output of said rectifier circuit from flowing to said voice coil motor;
- wherein said transistor is controlled by said output of said operational amplifier.
An apparatus to retract an actuator to a parking ramp with the same actuator speed regardless of the speed of the spindle motor, said apparatus comprises:
- a means to convert back-emf current from said spindle motor using a rectifier circuit and supplying said back-emf current to a voice coil motor;
- a means to control the amount of said back-emf current supplied to said voice coil motor.
A method to retract an actuator to a parking ramp with the same actuator speed regardless of the speed of the spindle motor, the method comprising the steps of:
- converting back-emf current from said spindle motor using a rectifier circuit and supplying said back-emf current to a voice coil motor;
- controlling the amount of said back-emf current supplied to said voice coil motor.
A computer system comprising a hard disk drive which operates in two or more speed modes, wherein an actuator retracts with the same power regardless of the selection of said speed mode when power is removed from said hard disk drive.
Dependencies are inferred from the claim text.