Abstract: An information storage device includes a cradle which can removably receive a cartridge that contains a rotatable hard disk. A read/write head is supported for movement adjacent the disk by a pivotal actuator arm. The cradle controls alignment of the head with the disk using feedback servo tracking. Servo parameters needed by the cradle to perform this tracking may be stored in a special wide track which is on the disk, and which may be a read-only track. Alternatively, the track may store updated firmware that can be loaded into the cradle. One approach to reading this special wide track is to effect servo tracking using default servo parameters. A different approach is to bias the actuator arm against a mechanical stop.

Abstract: An actuator for a direct access storage device has a secondary actuator with discrete or distributed masses such that a mechanical nodal point is created. The nodal point does not move with respect to the primary actuator. The secondary actuator is attached to the primary actuator at a nodal point. No net forces are coupled to the primary actuator when the secondary actuator is activated in a vibratory movement by a piezo-electric element.

Abstract: A disk drive system that functions at various different power supply voltage levels includes a reset generator for resetting the disk drive in response to a predetermined reset condition dependent upon a drop in the power supply voltage. An adapter circuit coupled to the reset generator produces the reset condition by applying a multiplier to the supply potential of the system to establish a predetermined voltage at a reset node. The adapter circuit includes a switch for selecting the multiplier based upon the particular mode of operation desired. The mode of operation is selected based upon an expected operating range of the power supply potential. A logic device is coupled to the adapter circuit to determine the particular mode of operation and for monitoring the current operating supply potential. The logic device is coupled to the switch to change the multiplier in accordance with the particular mode of operation selected, as the supply potential varies through an expected operating range.

Abstract: A disk drive system that functions at various different power supply voltage levels includes a reset generator for resetting the disk drive in response to a predetermined reset condition dependent upon a drop in the power supply voltage. An adapter circuit coupled to the reset generator produces the reset condition by applying a multiplier to the supply potential of the system to establish a predetermined voltage at a reset node. The adapter circuit includes a switching means for selecting the multiplier based upon the particular mode of operation desired. The mode of operation is selected based upon an expected operating range of the power supply potential. A logic device is coupled to the adapter circuit to determine the particular mode of operation and for monitoring the current operating supply potential.

Abstract: A servo control system is presented that provides improved bandwidth. The improved bandwidth is achieved by dividing the differential portion of the servo control system into two components. One of the differential components experiences no delay thus improving the servo control system response. The differential component that experiences no delay is combined with the proportional portion of the control system and implemented as an analog circuit. The hybrid analog/digital loop compensation circuit provides even better response time as the analog circuit provides near instantaneous responses to changes in input.

Abstract: A control system employing a sample and early-off hold function implements the hold function in such a way as to effectively create a filter function. Instead of holding a constant value for the duration of a sample period, the control system turns the held sample value on and off multiple times during the sampling period. The notch filter is tunable by adjustment of the number, time and duration of the held sample intervals.

Abstract: An automatic digital control system includes a proportional integral derivative (PID) compensator in which the digital differentiator portion, with its associated zero-order hold, is implemented according to an algorithm that reduces phase loss as a function of frequency. The digital differentiator is based only on a present error sample so that the output of the digital differentiator (with its ZOH) is made to resemble an amplitude-balanced step function (i.e., a doublet) during a given sample period T. The step transition occurs at one-half of the period (i.e., at T/2). Another embodiment further reduces phase loss by confining the output waveform of the differentiator to some fraction of the total sampling period. During the remaining portion of the sampling period the digital differentiator (again, with its associated ZOH) is forced to some desired reference level.

Abstract: A device for coupling and aligning a rotatable disk with the motor used for rotating that disk is disclosed. The end of the motor drive shaft includes a drive spindle having a V shaped slot in its surface. This slot accepts an aligning pin which protrudes from the center of the disk. When the aligning pin is at the apex of the V slot, the disk to be rotated is concentric with the drive spindle. A drive pin, which is mounted eccentrically on the drive spindle, is in contact with a lip on the outer surface of the disk hub. Rotation of the drive spindle causes interference between the drive pin and the lip thereby imparting rotatational momentum to the disk as well as a centering force on the aligning pin.

Abstract: A magnetic storage device comprising a rigid apertured cartridge containing a flexible magnetic disk and a Bernoulli surface is disclosed. The cartridge contains a reference surface which is integral with the Bernoulli surface and serves to align and flatten the Bernoulli surface when the cartridge is inserted into a disk drive. The cartridge is configured such that the flexible magnetic disk is maintained in operative association with the Bernoulli surface. The aperture of the cartridge serves as an entry point for the motor spindle and transducer of the disk drive. The cartridge is partially enclosed by a slidable shutter which protects the Bernoulli surface and flexible disk when the cartridge is not in use.

Abstract: A cartridge has a flexible pad which is disposed between a Bernoulli plate and a record disk when the cartridge is inserted into the disk drive. The flexible pad prevents ringing as the record disk is rotated against the Bernoulli plate. The cartridge has a slider which is opened when the cartridge is inserted into the drive to expose the record disk for rotation. This slider has a locking mechanism which can be opened only when the cartridge is properly inserted into the drive.

Abstract: A device and process for stabilizing two coaxially joined flexible magnetic disks is disclosed. Two or more flexible magnetic disks are coaxially joined by a coaxially located spacer. One of the disks is juxtaposed to and rotated against a flat stable Bernoulli surface. A second disk spaced by the spacer from the first disk contains centrally located perforations into which air can flow. When the disks are rotated at high speed air flows into the perforations and radially out from between the disks, thus forming an air cushion or air bearing between the disks. The apparatus and process thus provides two floppy disks stabilized by a single Bernoulli surface.

Abstract: A device for aligning a disk contained in a cartridge with a motor and transducer of a disk drive is disclosed. A record disk contained within a rigid apertured cartridge is inserted into a disk drive for use with that disk drive. Insertion of the cartridge into the disk drive causes engagement of a reference surface of the cartridge with a reference surface of a spicule member contained within the disk drive. The spicule member carries the transducer and drive spindle of the disk drive. The spicule member also contains a clamping device which ensures proper engagement of the cartridge reference surface and the spicule reference surface. The result is the proper alignment between the disk contained in the rigid cartridge and the transducer and motor spindle carried by the spicule member.

Abstract: A cartridge has a flexible pad which is disposed between a Bernoulli plate and a magnetic disk when the cartridge is inserted into the disk drive. The flexible pad prevents ringing as the disk is rotated against the Bernoulli plate. The cartridge has a slider which is opened when the cartridge is inserted into the drive to expose the magnetic disk for rotation. This slider has a locking mechanism which can be opened only when the cartridge is properly inserted into the drive.

Abstract: An actuator for a magnetic disk drive includes a planar coil which is symmetrical with respect to the center of rotation and has substantially straight active sections extending from the center of rotation on opposite sides of the center of rotation. Four permanent magnets provide a magnetic field. When current is applied to the planar coil, magnetic forces rotate the coil, and an attached actuator arm, about the center of rotation. The symmetrical coil sections eliminate or reduce torsional forces thereby avoiding vibration, improving bearing life and reducing potential servo loop instability.

Abstract: A magnetic disk drive has a drive motor mounted on a yoke which is rotatable about a pivot in the drive. A bezel member mounted on the end of the yoke normally closes the opening in the disk drive through which a cartridge is inserted. As this bezel member is moved out of the cartridge, the motor is moved out of the position in which it engages the disk and when the bezel member is closed, the motor moves into the engagement position. The motor is mounted on the yoke with a movable connection so that it is guided in a linear movement into engagement with the motor. In one embodiment the motor is guided by a shaft extending from the drive base plate through a guide opening in the motor.

Abstract: A magnetic disk drive has a drive motor mounted on a yoke which rotatable about a pivot in the drive. A bezel member mounted on the end of the yoke normally closes the opening the disk drive through which a cartridge is inserted. As this bezel member is moved out of the cartridge, the motor is moved out of the position in which it engages the disk and when the bezel member is closed, the motor moves into the engagement position. The motor is mounted on the yoke with a movable connection so that it is guided in a linear movement into engagement with the motor.

Abstract: An improved Bernoulli plate for juxtaposition to a rotating flexible magnetic disk so that the disk is rendered substantially rigid by a vacuum formed by the air between the plate and the disk being urged outwardly under the influence of centrifugal force is disclosed. The plate is formed by coining a metal substrate and thereafter electroplating the coined substrate so that any sharp irregularities resulting from the coining operation are smoothed, while the surface is provided with a hard, wear-resistant coating.

Abstract: A cartridge for a flexible magnetic disk includes a rigid box with an opening on one side which is normally closed by a slider. When the cartridge is inserted into the drive, the slider moves to the open position in which the disk can be engaged to rotate it in read/write relationship with a magnetic head. As the cartridge is inserted, a fixed Bernoulli plate in the drive enters the cartridge through an edge thereof. The disk is rotated against the Bernoulli plate to provide stability.

Abstract: An improved disk drive for storage of digital data is disclosed featuring a servo circuit used to drive the read/write head back and forth with respect to the media, the motion of the head being controlled by a servo circuit reading position signal data from the disk. The position data is stored in a sample and hold circuit having a transfer function dropping to a minimum value at the sampling rate; by choosing the resonant frequency of the head and servo apparatus assembly to be substantially equal to the sampling frequency, the mechanical resonance appearing in the system is effectively damped out.

Abstract: A cantilevered beam assembly with a maximum resonance frequency is adaptable for supporting a transducer for use with a random access flexible disk file. The cantilevered beam assembly includes a first cantilevered member and a second elongated member coupled at one end by a flexible joint to the free end of the first cantilevered member. When used with a flexible disk file system, a magnetic transducer is seated on the second end of the elongated member while said elongated member is restricted to flex in one plane only. A relatively thin, tapered, elongated protective structure having a relatively sharp, elongated leading edge contiguous with a relatively sharp front edge is rigidly connected to the first cantilevered member and surrounds the second elongated member in a plane orthogonal to the plane of flex.