Improvements in a system for controlling the position of a head carriage structure of a rotating disk data storage system are disclosed. The improvements include circuitry for generating a polyphase track boundary signal which compensates for drift, and which doubles or further increases the track density to increase storage capacity. A track centerline sensor circuit is greatly simplified by including the function thereof as microcode routines within a dedicated digital control processor. Error signals are measured periodically across the entire useful field of the disk, and they are constantly updated, so that improved compensation for drift, runout and offset of the disk relative to the data transducer is achieved. Track overshoot during track seeking movements of the transducer is accomodated, enabling reduced track average access time. Self contained diagnostic routines and a direct digital read out provide system status and error messages to operators and maintenance personnel, thereby facilitating maintenance and adjustment.
A magnetic storage disc 1 has a plurality of concentric data tracks, with circumferentially staggered servo centering signals B, C recorded flanking each track in a sector shaped region of the disc. A rotationally driven spindle 2 positionally clamps the disc such that an index mark on the spindle base is sensed by a pickup 5 immediately following the servo sector. The pickup signal is reliably supplied to a host computer via a timer 16, a microprocessor 12 and a R/W interface 15 to enable read/write operations on an accessed track. A delayed output from the timer, at the end of the data portion of the track and at the beginning of the servo sector, terminates such operations, enables the R/W head 3 to be stepped to a next addressed track by an actuator 4 with coarse positioning, and initiates the accurate centering of the head by an open loop servo.
A magnetic disk medium in which texture working is performed on surfaces of a substrate or on surfaces of subbing films provided on the substrate to attain circumferential worked-traces so that the contact start stop area thereof is different from the recording/reproducing area thereof in roughness of the worked surfaces.
A fixed disk memory subsystem connects to digital signal buses and a power supply of a host computer and includes a printed circuit board forming a subsystem mounting substrate for mounting and connecting a head and disk assembly and drive electronics. The head and disk assembly includes a radially positionable head transducer for flying in close proximity to a data storage surface of at least one rotating data storage disk, an actuator for positioning the data transducer at concentric data tracks defined on the surface, and a DC brushless spindle motor for rotating the data storage disk. The drive electronics includes a data transducer position control circuit for controlling operation of the actuator in relation to the concentric data tracks, read/write electronics connected to the transducer, a disk user data controller for obtaining digital control signals and digital data blocks from the host computer for storage in predetermined ones of said data tracks, and for supplying digital status signals and digital data blocks retrieved from predetermined ones of said data tracks to the host computer, and a programmed digital microcontroller connected for controlling operations of said data transducer position control circuit, the disk user data controller and the interface circuit.
A focus servomechanism control system in an optical disc is provided for controlling a light focusing unit to adjust a focus of light impinging on a track in a rotatable optical disc. The focus servomechanism control system includes: a unit for moving the light focusing unit in a direction perpendicular to a plane of the optical disc; a unit for producing a focus error signal; a unit for producing a track error signal; and a unit for controlling a position of the light focusing unit through the light focusing unit moving unit in response to the focus error signal and the offset parameter. The focus servomechanism control system further includes an offset setting unit for continuously setting, during an offset adjustment mode, a plurality of offset parameters to the position control unit, to determine a maximum amplitude of the track error signal, and to set the offset parameter producing the maximum amplitude of the track error signal to the position control unit. In a normal operation, the focus servomechanism control system effects varies the focus control in response to the set offset parameter and the focus error signal.
A method and apparatus are provided to compensate for the runout that commonly occurs during the reading from or writing of information on the surface of a disk medium using a read/write head. The runout relates to the distance the head is located away from a disk track center during the rotation of the disk. To maintain the head in alignment with the track center during the complete revolution of the disk, position information is obtained. This position information is used with discrete fourier transform techniques to provide a representation of the disk runout. From this representation, a compensating signal can be generated to provide movement of the head that compensates for the runout and keeps the head positioned in alignment with the track center at all times during the disk rotation.
