A data storage device and a method of data storage

Claim 2

A data storage device comprising: a base; a plurality of data storage disks commonly journalled for rotation to the said base, a surface of one of the disks recorded thereon a plurality of first bursts offset from track centreline in a first direction for odd numbered tracks and offset from track centreline in a second direction for even numbered tracks and a plurality of second bursts interleaved with the first bursts and offset from track centreline in the second direction for odd numbered tracks and offset from track centreline in the first direction for even numbered tracks, the bursts being arranged in sectors, on the said surface and the first and second bursts being reodabte by the associated transducer; a plurality of read/write data transducers held in close proximity to the surfaces of the disks by the air-bearing effect; carriage means mounted to the base for moving the transducers in common, the carriage means being actuable by a mover; optical encoder means for providing a plurality of phase related signals indicating the position of a transducer relative to the base; peak detection means for detecting and out putting sampled peak amplitude values for each burst read by the associated transducer; analogue switch means connected to the optical encoder means and to the peak detection means for switching between the plurality of phase related position signals and the peak amplitude values of the bursts; analogue to digital converter means connected to the analogue switch means for converting each analogue signal received therefrom into a digital signal; user interface circuit means for receiving digital disk surface and track selection control data; means for generating signals indicating the boundaries of the sectors on the said one disk; control means connected to the generating means, the analogue to digital converter means, and the analogue switch means for receiving digital data from the analogue to digital converter means and the user interface circuit means so as to calculate therefrom digital control data, for commanding the carriage means to move from a departure track to a user defined destination track and to settle therat in accordance with the information from the optical encoder means during track seeking and for commanding the carriage means to maintain the transducers in track centreline alignment based on information from the peak detection means during track following; digital to analogue converter means connected to the microprocessor means for receiving and converting the digital control data into analogue signals; and amplifying means for amplifying the analogue signals and for supplying the amplified signals to control the carriage means during track following and during track seeking operations.

Claim 3

A device according to Claim 2, wherein lead-lag compensation means are connected to the digital to analogue converter means for providing phase compensation to the analogue signal values during track following operations.

Claim 4

A device according to Claim 2 or 3, wherein the carriage means mover comprises a flux return fixed base plate, a flux return top plate, a first generally annular permanent magnet means secured to the fixed base plate having an even number plurality of adjacently opposed field magnetic segments in which the north and south poles alternate at the major surfaces thereof, a second generally annular permanent magnet means secured to the flux return top plate and having the same arrangement of opposed field magnetic segments as the first magnet means and a generally annular, rotatable coil assembly placed between and closely spaced from the first and second magnets means, the coil assembly containing the same number plurality of coils as there are magnetic segments in the permanent magnets means, the coils being aligned adjacent the aligned magnetic segments at at least one position of rotation of the assembly, the coils being connected in two series of opposed interleaved windings adjacently disposed in said assembly, and said carriage mechanism being secured to said assembly.

Claim 5

A device according to Claim 4, wherein the amplifying means comprises a push-pull amplifier pair arranged as complementary constant voltage differential amplifiers wherein substantially no current flows through the coils of the rotary actuator when the associated servo transducer is aligned with the centreline of a selected track during track following.

Claim 6

A device according to Claim 2, 3, 4 or 5 wherein the base comprises an enclosed compartment for containing the carriage means mover and an external reinforced rib surface adjacent the compartment is provided to dissipate heat generated by the actuator.

Claim 10

A device according to Claim 9, wherein the control means commands track seeking by putting out the highest available integer to command acceleration in one direction and the lowest available integer to command acceleration in the other direction of the carriage means.

Claim 13

A device according to Claim 12, wherein the surface of the said one disk contains a different burst arrangement in the reference track than the burst arrangements of all other data tracks thereon and the control means includes means for testing for the presence of the said different burst arrangement.

Claim 15

A method according to Claim 14, further comprising providing reference track identification data for a reference track on the said surface of the said one disk as an additional burst within each sector, except at the reference track.

Claim 16

A method according to Claim 15, further comprising; moving the transducer associated with the said one disk to the reference track during an initial operation; setting a digital track counter to the reference value while the said transducer is located at the reference track, incrementing or decrementing the track counter in accordance with an initial count corresponding to departure track and with track location digital values derived from the phase related signals as the transducers are moved away from or toward the reference track during track seeking opoerations.

Claim 17

A method according to Claim 14, 15 or 16, comprising providing a took-up table with digital velocity profile data, commanding a velocity profile during track seeking operations referring to the look-up table and calculating and putting out digital values depending upon the magnitude of the seek and the actual measured positions of the transducers during the seeking operation as given by the plurality of phase related signals.

Claim 18

A method according to Claim 13, 14, 15, 16 or 17, wherein two phase related signals are provided and the method further comprises periodically measuring the amplitude of a first phase related signal as it varies in value from a minimum to a maximum and switching to measure the second of the phase related signals when the first signal reaches a zero point and then periodically measuring the amplitude of the second signal, switching back to measure the first signal when the second signal reaches a zero point and continuing to switch back and forth between the first and the second phase signals during track seeking operations to monitor transducer radial position relative to the disk surface.

Claim 19

A method according to Claim 14, wherein the further steps of settling near the vicinity of track centreline at the completion of a track seeking operation by: providing the phase signals in quadrature, providing a look-up table of digital arc tangent values in a predetermined range including the range between zero and unity; calculating an arc tangent angle from the quadrature phase signals by referring to the look-up table; calculating an angular displacement value from the arc tangent angle and putting the value out as a track centreline correction current value to the transducer mover to move the transducer to the vicinity of track centreline, and then correcting the transducers to actual track centreline alignment with the data from the servo sector bursts.

Claim 21

A method according to Claim 20, wherein track seeking includes the steps of putting out the highest available integer to command the transducer mover to accelerate in one direction, and putting out the lowest available integer to command the transducer mover to accelerate in the opposite direction.