EP0224378A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Means for parking read/write heads in a disc drive using the back-emf of the spindle motor to operate a stepper motor
Assignee: Seagate Technology International
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Filing: 1986-11-19
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Granted: —
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Expires: 2006-11-19
Abstract
Abstract Electronic circuitry is provided to position the read/write heads (10) in a designated landing zone when the electrical power is removed from the drive (27). when power is removed from the drive, the stored energy of the rotating spindle motor (27) is used as a source of electrical power and timing pulses to the stepper motor (30) which drives the actuator of the disc drive. The power generated by the spindle motor as it spins down is referred to as "back EMF". A sequencer circuit (50) is provided to couple the power and clock pulses to selected windings of the stepper motor (30) in an order that will cause the stepper motor to rotate in the direction necessary to move the transducer heads (10) to a predetermined park position at the inner diameter of the disc whenever power is removed from the disc drive. Since the location of the heads at power down may not be known, the timing of the pulses in such that a sufficient number of steps will be taken to move the transducer heads to the parking zone within the time allotted even if power down occurred when the heads were at the outermost track. Step pulses will continue to be generated until the back EMF of the spindle motor is insufficient to generate such pulses. After the transducer heads are at the predetermined parking location, any additional steps will cause the actuator to contact a mechanical "inner crash stop" designed to prevent damage to the transducer heads from contact with the clamp which retains the discs.
Inventors
- 👤 William E. Wevers
- 👤 James Norman Krause
- 👤 Ramgopal Battu
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 19:41
CPC Classifications
G; G11; G11B; G11B19/00; G11B19/20; G11B21/00; G11B21/02; G11B21/08
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
152 words
In a disc drive comprising a plurality of discs mounted for rotation within a disc drive housing, a spindle motor for driving said discs in rotation, an actuator for reciprocatably driving a transducer array relative to the discs, said actuator including a carriage for said transducer array and a stepper motor drivingly connected to the carriage for positioning the carriage and transducer array relative to the disc and circuitry for detecting removal of power, wherein means are provided for parking the transducer array at a defined position relative to the disc after power is removed from the drive comprising circuitry for disabling normal stepper motor control and enabling a stepper motor retract sequencer circuit coupled between the spindle motor and selected windings of the actuator stepper motor and responsive to the output of said spindle motor to energize the windings of the stepper motor to move the actuator to a defined position.
Claim 2
Dependent Claim
152 words
In a disc drive comprising a plurality of discs mounted for rotation within a disc drive housing, a spindle motor for driving said discs in rotation, an actuator for reciprocatably driving a transducer array relative to the discs, said actuator including a carriage for said transducer array and a stepper motor drivingly connected to the carriage for positioning the carriage and transducer array relative to the disc and circuitry for detecting removal of power, wherein means are provided for parking the transducer array at a defined position relative to the disc after power is removed from the drive comprising circuitry for disabling normal stepper motor control and enabling a stepper motor retract sequencer circuit coupled between the spindle motor and selected windings of the actuator stepper motor and responsive to the output of said spindle motor to energize the windings of the stepper motor to move the actuator to a defined position.
Claim 3
Dependent Claim
44 words
A disc drive as in Claim 1 wherein said sequencer comprises a clock circuit responsive to the output of a winding of the spindle motor to step said stepper motor a number of steps necessary to park said transducer array at a defined position.
Claim 4
Dependent Claim
59 words
A disc drive as in claim 1 or claim 2 wherein said spindle motor generates a back EMF when DC power to the drive is removed, said motor sequencer circuit comprising means for coupling said generated back EMF to selected phases of said stepper motor to cause said stepper motor to move said transducer array to said park position.
Claim 5
Dependent Claim
32 words
A disc drive as in Claim 3 wherein said sequencer circuit includes means for rectifying and filtering said back EMF and coupling said back EMF to the windings of the stepper motor.
Claim 6
Dependent Claim
72 words
A disc drive as in Claim 4 wherein outputs of said sequencer circuit coupling means are coupled to one end of said windings of said stepper motor, said sequencer means further including a clock circuit responsive to the output of said winding of said spindle motor to generate a sequence of clock pulses, the output of said clock circuit being coupled to the other end of said windings to energize said windings.
Claim 7
Dependent Claim
32 words
A disc drive as in Claim 5 wherein said generated back EMF and the outputs of said clock circuit are coupled to outputs of at least two windings of said stepper motor.
Claim 8
Dependent Claim
87 words
A disc drive as in Claim 2 or any of claims 3 to 6 when appendant to claim 2, and assuming an external DC power supply to said disc drive motors, wherein means are provided for generating a signal indicating the presence of said DC power supply, said sequencer circuit being responsive to said signal generating means to initiate the actuator movement to the defined park position,said defined position being generally at the inner portion of said discs and inside the diameter of the innermost data track.
Claim 9
Dependent Claim
34 words
A disc drive as in Claim 7 wherein said sequencer circuit is responsive to a change in state of an output of said signal generating means to initiate the defined movement of said actuator.
Claim 10
Dependent Claim
178 words
In a data storage device including a frame, a data storage disc supported on a spindle for rotation within a frame and rotationally driven by a spindle motor at constant velocity, the disc being characterised by a multiplicity of concentric tracks on a surface thereof, at least one data transducer head structure mounted in close proximity to said disc track surface, and an actuator assembly for positioning said transducer relative to the tracks comprising a carriage mounting said transducer at one end thereof and a stepper motor coupled to the carriage for positioning the carriage and transducer relative to the tracks, and a DC power supply for said motors, the improvement comprising a sequencer circuit coupled between the spindle motor and selected windings of the actuator stepper motor and responsive to the output of said spindle motor to energize the windings of the actuator stepper motor to move the actuator to a defined position, and a control signal generator responsive to the absence of an output from said DC supply to said motors to activate said sequencer circuit.
Claim 11
Dependent Claim
178 words
In a data storage device including a frame, a data storage disc supported on a spindle for rotation within a frame and rotationally driven by a spindle motor at constant velocity, the disc being characterised by a multiplicity of concentric tracks on a surface thereof, at least one data transducer head structure mounted in close proximity to said disc track surface, and an actuator assembly for positioning said transducer relative to the tracks comprising a carriage mounting said transducer at one end thereof and a stepper motor coupled to the carriage for positioning the carriage and transducer relative to the tracks, and a DC power supply for said motors, the improvement comprising a sequencer circuit coupled between the spindle motor and selected windings of the actuator stepper motor and responsive to the output of said spindle motor to energize the windings of the actuator stepper motor to move the actuator to a defined position, and a control signal generator responsive to the absence of an output from said DC supply to said motors to activate said sequencer circuit.
Claim 12
Dependent Claim
41 words
A data storage device as in Claim 9 wherein said sequencer circuit includes means for deriving a clock signal and a power signal from back EMF generated by said rotating spindle motor to selectively energize the windings of said stepper motor.
Claim 13
Dependent Claim
34 words
A device as in Claim 10 wherein said power signal generating means of said sequencer circuit comprises means for coupling the back EMF of said spindle motor to selected windings of said stepper motor.
Claim 14
Dependent Claim
58 words
A device as in Claim 11 wherein outputs of said power signal generating circuit are coupled to one end of said selected windings of said stepper motor, outputs of said clock signal generating circuit being coupled to the other end of said selected windings to selectively activate said windings and cause said stepper motor to position said carriage.
Claim 15
Dependent Claim
31 words
A device as in Claim 12 wherein said generated back EMF and the outputs of said clock circuit are coupled to outputs of at least two windings of said stepper motor.
Claim 16
Dependent Claim
32 words
A device as in Claim 13 wherein said sequencer circuit is responsive to a change in state of an output of signal generating means to initiate the defined movement of the actuator.
Claim 17
Dependent Claim
31 words
A device as in Claim 14 wherein said clock circuit comprises means for converting said back EMF signal to a digital clock signal for selectively activating windings of said stepper motor.
Claim 18
Independent Claim
32 words
A device as in any of claims 9 to 15 wherein said defined position is generally at the inner portion of said disc and inside the diameter of the innermost data track.
References Cited (Backward Citations)
No citation records indexed.
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