Data storage devices

Claim 3

A data storage device comprising: a base; a data storage disk; a motor mounted to the base for rotating the disk; at least one data transducer for reading data from and writing data to data tracks on a storage surface of the disk, a servo sector on the disk being prerecorded with two series of servo bursts; transducer carriage means for supporting the data transducer relative to the storage surface; actuator means for moving the carriage means to move the transducer between data tracks; optical encoder means including a housing, means mounted to the housing for emitting photons, a photodetector array mounted to the housing for receiving photons from the emitting means, a translucent scale having equally spaced-apart opaque regions movable between the emitting means and the photodetector array, the housing and the scale moving relative to each other as the carriage means moves relative to the base and the photodetectors providing output signals phase-shifted relative to each other peak detector means for measuring the peak amplitude of each servo burst read by the transducer as it passes over the servo sector; programmed digital computer means comprising analogue to digital converter means, processor means connected to the analogue to digital converter means, and digital to analogue converter means connected to the processor means, the peak detector means and the photodetectors being connected to the analogue to digital converter means so that the peak servo burst amplitudes and the output signals from the photodetectors are converted to digital values; analogue actuator driver means connected to the digital to analogue converter means for applying digitally commanded current values to the actuator means to move the transducer(s), the processor means being connected to command and control directly movement of the actuator means by determining and counting data track boundaries from the digitized photodetector output signals and by calculating track centreline offset correction values from the digitized peak servo burst amplitudes to move the transducer(s) between data tracks in accordance with commands from a user interface and to maintain the transducer(s) in alignment with the centreline of a selected data track(s) in accordance with the calculated offset correction values.

Claim 4

A data storage device according to Claim 2 or 3, wherein the motor is a brushless direct current motor mounted to the base and has internal" non-contacting commutation sensors and an index sensor and the actuator means comprises a pure torque generating rotary actuator assembly journalled to the base for rotating the transducer carriage; the device further comprising: a driver switching circuit means connected to drive the brushless direct current motor; and an electronic rotary actuator power driver circuit connected to operate the rotary actuator assembly, the analogue peak detector circuit being connected periodically to the transducer to receive each servo sector burst in sequence and to register an analogue value corresponding to the amplitude peak of each said burst, the processor means being connected for receiving data from the commutation sensors and the index sensor of the brushless direct current motor and calculating and providing binary commutation signals to the power switching circuit to operate the brushless motor, for receiving analogue data in the form of track boundary data from the photodetectors and track centreline data from the peak detector and converting the data to digital values, and for receiving track selection information from a user interface, calculating and putting out track selection values to the rotary actuator power driven circuit to cause the rotary actuator to move the transducer to a desired data track and to maintain the transducer in centreline alignment with the track during reading and writing operations and for. further measuring differences in the response characteristics of the photodetectors for calculating and sending light level correction values to the light source to compensate for the differences.

Claim 5

A data storage device comprising: a base; a brushless direct current motor mounted to the base and having internal non-contacting commutation sensors and an index sensor; at least one data storage disk directly mounted to the motor for rotation and having a plurality of concentric data tracks on a storage surface thereof and a servo sector containing two prerecorded sequential bursts equally offset radially from a centreline of each track; at least one data transducer for reading data from and writing data to the data tracks and for sequeritially reading the servo sector bursts; a rotatable transducer carriage for supporting the transducer; a pure torque generating rotary actuator assembly journalled to the base for rotating the transducer carriage; optical encoder means comprising a housing journalled to the base to enable rotational and axial alignment and containing a light source as a photon emitting means and an array of masked photodetectors, a scale mounted to the transducer carriage having alternating translucent and opaque regions which pass between the light source and the photodetectors, and wherein the photodetectors are phase-shifted relative to the translucent and opaque regions; an electronic motor driver power switching circuit connected to drive the brushless direct current motor; an electronic rotary actuator power driver circuit connected to operate the rotary actuator assembly; an analogue peak detector circuit connected periodically to the transducer to receive each servo sector burst in sequence and to register an analogue value corresponding to the amplitude peak of each said burst; and ponding to the amplitude peak of each said burst; and processor means for receiving data from the commutation sensors and the index sensor of the brushless direct current motor and calculating and providing binary commutation signals to the power switching circuit to operate the brushless motor, for receiving analogue data in the form of track boundary data from the photodetectors and track centreline data from the peak detector and converting the data to digital values, and for receiving track selection information from a user interface, calculating and putting out digital track selection values to the rotary actuator power driver circuit to cause the rotary actuator to move the transducer to a desired data track and to maintain the transducer in centreline alignment with the track during reading and writing operations and for further measuring differences in the response characteristics of the photodetectors and for calculating and sending light level correction values to the light source to compensate for the differences.

Claim 6

A device according to Claim 4 or 5, wherein the driver circuit means comprises a plurality of electronic switches each connected to a coil of the motor, the switches having a common voltage reference node, transconductance amplifier means having two opposed polarity inputs, with one input connected to the reference node, for outputting a signal to adjust the current passed by the electronic switches, the other input of the transconductance amplifier being connected to the processor means so that the operation thereof is responsive to the processor means as well as the voltage at the reference node.

Claim 7

A control device for a brushless direct current motor having a plurality of non-rotating field coils and including internal non-contacting commutation sensors, the motor being arranged to rotate at least one data storage disk, the device comprising: driver circuit means for switching drive current between the coils and for varying the drive current; programmed processor means for calculating switching commands in accordance with data provided by the commutation sensors and for putting out the switching commands to the driver circuit means for switching the drive current, and for monitoring motor speed and calculating speed correction values and putting the speed correction values out to the circuit means to adjust the drive current to maintain motor speed at a constant nominal value.

Claim 8

A data storage device according to any one of Claims 4 to 6 wherein the processor means comprises a plurality of programmed microprocessors, one microprocessor for receiving data from the commutation sensors and the index sensor and for calculating and providing binary commutation signals to the power switching circuit, and a second microprocessor for controlling the rotary actuator power driver circuit and the emitting means wherein the said one microprocessor generates an index signal from the index sensor which interrupts operation of the said second microprocessor to enable it to read the peaks of the servo sector bursts.

Claim 9

A device according to Claim 3 or 5, wherein the processor means is arranged to read peak light values from each photodetector in turn, to compare each read detected value with a predetermined nominal value and, calculate a difference value and output a signal to adjust the level of the photons emitted by the photon emitting means for each photodetector whenever its output signal is read so that each photodetector puts out a corrected signal.

Claim 11

II. A device according to Claim 10 wherein the processor means is arranged to enable the capacitance to be discharged before each amplitude peak is accumulated therein.

Claim 12

A data storage device comprising; a base; a data storage disk; a motor mounted to the base for rotating the disk; at least one data transducer for reading data from and writing data to data tracks on a storage surface of the disk; transducer carriage means for supporting the data transducer relative to the storage surface; actuator means for moving the carriage means to move the transducer between the data tracks; track boundary optical encoder means having a housing movably secured to said base and including a scale secured to said carriage means, the housing being two parts formed of an upper part and a lower part, having a common longitudinal axis of alignment and rotation and having interlocking structures for maintaining the common axis, a scale secured to the carriage, a single light emitting diode energy source mounted in an axially aligned open chamber of the upper housing part for directing photons toward the lower housing part, a lateral surface on the lower housing part facing the energy source, the lateral surface defining a recessed region therein and having a plurality of raised plateaux disposed about the periphery of the surface beyond the recessed region, a photodetector array secured in the recessed region, a photo-optical -mask aligned over the photodetector array and having corners resting upon and secured to the plateaux, the lower housing part having shelf means below and beyond the lateral surface, a printed circuit wafer secured to the shelf means and having a plurality circuit traces thereon connected to a connector cable, and connection wires bonded to the array and to the traces for connecting the array to the cable; and servo control means for controlling the actuator means from position information provided at least in part by the optical encoder means.

Claim 16

A device according to Claim 15, wherein the housing of the optical encoder means comprises a lower cylindrical portion defining a cylindrical chamber in axial alignment with the journal, and a cylindrical pin secured to and extending from'base provides the journal by seating in the cylindrical chamber.

Claim 17

A data storage device comprising a base, a data storage disk, a motor mounted to the base for rotating the disk, at least one data transducer for reading data from and writing data to data tracks on a storage surface of the disk; transducer carriage means for supporting the data transducer relative to the storage surface; actuator means for moving the carriage means to move the transducer between the data tracks; track boundary optical encoder means having a housing movably secured to the base and including a scale secured to the carriage means, the housing having a single longitudinal axis of alignment and rotation relative to the base and having a lower cylindrical portion defining a chamber, a pin secured to and extending from the base along the axis being seated in the said cylindrical portion, thereby enabling longitudinal and rotational alignment of the encoder relative to the base; and servo control means for controlling the actuator means from position information provided at least in part by the optical encoder means.

Claim 18

A device according to Claim 16 or 17, wherein a removable releasable clamp is provided for releasably securing the lower cylindrical portion to the pin.

Claim 20

A data storage device comprising: a base; a data storage disk; a motor mounted fo the base for rotating the disk; at least one data transducer for reading and writing data from and to a storage surface of said disk; rotary transducer carriage means for supporting the data transducer relative to the disk storage surface; rotary actuator means for rotating the carriage means; servo means for controlling the rotary driver means at least in part by servo data read by the transducer from the disk storage surface; a journal between the base and the rotary driver means; a lower ferromagnetic flux return plate lying on opposite sides of the journal and within a common plane normal to the journal; a plurality of lower permanent magnets secured to an upper face of the plate on opposed sides of the journal; rotor means rotatably secured to the base at the journal having a locus of rotation not in excess of 90 degrees and having a plurality of opposed coils, each of which overlies a lower magnet means on opposite sides of the journal and is so constructed that the mass of the rotor is balanced about the journal; an upper ferromagnetic flux return plate lying on opposite sides of the journal above the rotor means; and a plurality of upper permanent magnets secured to a lower face of the upper flux return plate on opposed sides of the journal, each upper magnet means being in alignment with a lower magnet means and having a magnetic field in alignment with the field of the lower magnet means.

Claim 21

A device according to Claim 19 or 20, wherein the upper plate and the lower plate are secured to the base at one end of the actuator means and are commonly secured to each other at another end of the actuator means opposite the one end and an attachment means is provided for securing the upper and lower plates to the base at the said opposite end for accommodating relative movement between the plates and the base.

Claim 22

A device according to Claim 20, wherein the plurality of upper and lower magnets comprise two commonly sized and magnetized pairs of annular segments lying on opposite sides of the journal, and wherein the actuator means comprises two coils, each coil being rotatably situated between a pair of segments.

Claim 23

A data device according to any preceding claim, wherein the base defines a continuous peripheral lip, and further comprises a gasket seated on the lip and a cover surrounding the disk and carriage and sealingly engaging the gasket.

Claim 24

A data storage device comprising: a base; at least one data storage disk; a motor mounted to the base for rotating the disk; at least one data transducer for reading data from and writing data to data tracks on a storage surface of the disk; rotary transducer carriage means for supporting the data transducer relative to the storage surface; rotary actuator means for moving the carriage means to move the transducer between data tracks; and servo control means for controlling the rotary actuator from position information provided at least in part from data stored on said storage surface, the base being, a unitary casting defining a disk region and a rotary actuator region, the motor being a brushless direct current motor mounted to the casting in a central opening in the disk region and directly driving the disk or disks on a common spindle, the rotary actuator region defining a generally rectangular well portion with an upwardly extending actuator journal centrally located therein, and the actuator means being generally right parallelopipedal in shape, and occupying the well portion surrounding the journal, the rotary carriage means being secured to the rotatable member, the arrangement being such that the base defines a continuous peripheral lip on which a gasket is seated and an airtight cover sealingly engages the gasket surrounding the disk or disks and carriage means.

Claim 25

A data storage device according to Claim 23 or 24, further comprising main circuit board means detachably mounted to the base outside the cover, auxiliary circuit board means detachably mounted to the base inside the cover and having an electrical connection providing portion extending through an opening in the base casting and mating with a plug on the main circuit board means, and sealing means for sealing the opening in the base casting when the auxiliary circuit board means is mounted to the base casting.

Claim 26

A data storage device according to Claim 25, wherein the main circuit board means includes heat generating electronic components which are thermally connected directly to the base.

Claim 27

A data storage device according to any one of Claims 23 to 26, comprising sealed window means in the cover adjacent the carriage means, and track position indicating means cooperating between the carriage means and the window means for providing a relative visual indication of track position of the transducer(s).

Claim 28

A data storage device according to any preceding claim, wherein carriage means comprises an arm having a circular portion for attachment to the actuator means and having an inwardly curved and tapered portion extending from the circular portion to an apex at or adjacently beyond the location of attachment of the transducer, a plurality of circular openings of diminishing diameter being disposed along the tapered portion between the circular portion and the apex.