Abstract: A rotational recording apparatus that comprises a shock sensor and that adaptively processes the output of the shock sensor to obtain a feed forward signal, so as to implement a stable operation within a practical range.

Abstract: A disk drive with the ability to detect errors caused by thermal asperities and assign alternate sectors is described. One of a plurality of error recovery procedures is executed after turning off a signal filter which normally removes a set of low frequencies from the output signal from the head. The unfiltered signal is used to judge whether a thermal asperity caused the error. If it is determined that a thermal asperity caused the error, the sector is marked as defective and an alternate sector is assigned even if other error recovery procedures are able to read the sector. The reliability of the drive is enhanced by removal of sectors from use which have temporarily recoverable errors caused by thermal asperities.

Abstract: A disk drive and a disk drive control method is described which reduces the number of one track seeks a drive performs. The one track seeks can operate the actuator bearing in a non-linear mode or can increase in the friction of the actuator bearing which leads to servo positioning inaccuracies. In the disk drive the logical block address (LBA) assignments are made so that when sequential addresses are allocated to two different tracks, the tracks are physically non-adjacent. Thus, when a sequential LBAs are read across a track boundary, the actuator is moved farther than would be required if the LBAs were assigned the adjacent tracks.

Abstract: A disk drive has a data recording medium such as a disk, a spindle motor for rotating the disk, disk rotation speed controlling logics for supplying a spindle current to the above described spindle motor to rotate the disk at a constant speed, a head unit for accessing the disk, an actuator for moving the head unit, and head position controlling logics for driving the actuator and controlling the position of the head unit.

Abstract: A rotating storage apparatus is provided for high recording reliability in an environment in which a shock or vibration exists. Provided are means for outputting a shock out signal (SO) if an output from an acceleration sensor exceeds a predetermined threshold, a latch circuit 21 for outputting a latch signal at high level during a predetermined write inhibit period after the shock out signal (SO) is input, and a write gate signal (WG) which goes high when a write is enabled. A write enable signal is generated by an AND circuit 23 having a NOT output of the latch signal as well as the write gate signal WG as its inputs.

Abstract: A method and apparatus for positioning a head over a track in an information recording medium to eliminate head positioning error. Data tracks are concentrically formed on a magnetic disk, and identification information for identifying each data track is recorded so as to correspond to each data track. The identification information consists of first and second gray codes, and the first gray code is of n-1 bits where n represents the number of bits of a track address and set for each block so that it has a value different among a plurality of blocks each consisting of a plurality of data tracks. The second gray code is of three bits, and set for each data track so that it represents a value which differs between data tracks contiguous in the radial direction of the disk and circulates for every three or more blocks continuous in the radial direction of the disk. Head positioning is determined based on reading the first and second gray codes by the head.

Abstract: A motor having enhanced transient characteristics during the acceleration time of the motor in a disk unit. The motor includes a motor controller having a phase-locked loop (PLL) or frequency-locked loop (FLL) for controlling the speed of a spindle motor in a disk drive. The PLL or FLL is coupled to a digital filter. The difference between a phase or frequency synchronized with the rotational speed of the motor and a target value is received by the digital filter. The digital filter output is added to the target value. The sum of the filter output and the target value is set in the PLL or FLL as an adjusted target value to perform PLL control or FLL control. With this arrangement, the time to shift from a low-speed rotation state to a high-speed rotation state can be shortened.

Abstract: The present invention determines whether a filter is used for reading and writing on a disk to correct repeatable runout. The invention estimates the magnitude of repeatable runout for each disk by measuring the maximum absolute value of a state variable of a filter when the disk is turned on or when the disk returns from a sleep mode, and compares the measured value to a predetermined criterion such as the track width. If the magnitude of the repeatable runout is less than or equal to the predetermined criterion, the filter is not used. If the magnitude of the repeatable runout exceeds the predetermined criterion, the invention reads and writes data using the filter.

Abstract: To achieve fast positioning of a head by determining an initial value dynamically from state variables of a system at a switching time of control modes. In a recording device having a head, a recording media including a plurality of tracks accessed by the head, and a motor for moving the head, in order to position the head to a target track by switching control modes and outputting a control signal value u(n) to drive the motor in response to an input signal value y(n) representing a difference between a current position of the head and the target track, the gain of a control system having the input and control signal values as state variables is changed only at a mode switching time.

Abstract: A head position signal Y(N), which represents the size and direction of the deviation of the current position of a magnetic head to the target position in terms of a digital value, is input at intervals of sampling cycle TS. A main control section 68 generates and outputs a motor current control signal U(N) representative of a control amount of motor current in terms of a digital value. The main control section 68 is provided with a digital filter 86 so that the head position signal Y(N) is input. The digital filter 86 has a gain which becomes a peak with respect to the component of a frequency in a narrow band including a predetermined angular frequency .omega..sub.o and which becomes almost 0 with respect to the frequency components other than the narrow band.

Abstract: A position control method for use with a hard disk drive or other rotating body is provided. A radial position of a rotating body corresponding to an object to be controlled is detected as a current object position. Subsequently, a control operation signal is generated which is representative of a deviation between a target object position expressed in terms of the radial position of the rotating body and the current object position detected. In addition, an actuator manipulation-amount signal is output which is derived from the control operation signal. This actuator manipulation-amount signal is formed by selectively summing an integration signal with either a first or a second control signal. The first control signal is a function of the current object position. The second control signal is a function of a predicted object position at a second predetermined time after generation of the control operation signal.

Abstract: To achieve fast positioning of a head by determining an initial value dynamically from state variables of a system at a switching time of control modes. In a recording device having a head, a recording media including a plurality of tracks accessed by the head, and a motor for moving the head, in order to position the head to a target track by switching control modes and outputting a control signal value u(n) to drive the motor in response to an input signal value y(n) representing a difference between a current position of the head and the target track, the gain of a control system having the input and control signal values as state variables is changed only at a mode switching time.

Abstract: A method and apparatus for simply detecting the magnetic head position over a wide range. A magnetic disk has recorded thereon a plurality of data tracks 54 formed along the radial direction (arrow B), and burst pattern rows A, B, C, and D. Signal recording areas 50a and 50b of pattern rows A and B are arranged in a staggered manner, their end sides along the radial direction corresponding to respective widthwise central portions of tracks 54. Signal recording areas 50c and 50d of pattern rows C and D are also arranged in a staggered manner, their end sides along the radial direction corresponding to respective boundaries of tracks 54. Based on signals A, B, C, and D obtained by moving the magnetic head and reading each pattern row, data SA representing signal A/(A+B) and data SC representing signal C/(C+D) are generated.

Abstract: A method and apparatus for controlling the speed of a motor for a hard disk drive. The motor speed control apparatus includes a speed feedback controller which uses selected feedback coefficients. The feedback coefficients are suitable to the rotor assemblies having different moments of inertia. A driving force is applied to the motor to rotate the installed rotary assembly. A detector determines the period of rotation and a period of subsequent rotation at the initiation of the motor. An identification means identifies a rotor assembly installed on the motor from said detected period. The time constant of said motor is a function of the moment of inertia of the rotor assembly installed on the motor and can be obtained from the period of rotation and the period of subsequent rotation at the time said motor is started up. A selector chooses the appropriate feedback coefficients for the identified rotor assembly.

Abstract: A controlled variable is detected at each predetermined timing by a detecting section 2, and the controlled variable is compared with a target value by a comparator 3 to obtain a deviation. A manipulated variable is calculated, based on the deviation, by a compensating section 4, and a height H corresponding to the manipulated variable is calculated by a controlling section 5. A manipulated pulse having the height H and a predetermined width W is provided to a controlled system 6 by the controlling section 5.

Abstract: To achieve fast positioning of a head by determining an initial value dynamically from state variables of a system at a switching time of control modes. In a recording device having a head, a recording media including a plurality of tracks accessed by the head, and a motor for moving the head, in order to position the head to a target track by switching control modes and outputting a control signal value u(n) to drive the motor in response to an input signal value y(n) representing a difference between a current position of the head and the target track, the gain of a control system having the input and control signal values as state variables is changed only at a mode switching time.

Abstract: Disclosed is a rotating memory device or disk drive which includes a rotating media having tracks thereon and an actuator arm which includes a head for writing representations of data to the track on the rotating memory. The head also reads representations of data from the track of the rotating memory. The head is attached to the actuator arm. The actuator arm is used to move the head to a selected position over the rotating memory such as over the track in the rotating memory. Also disclosed is an apparatus that corrects for errors of low frequency. The device includes circuitry for producing a position error signal for integrating the position error signal to produce a control signal that is used to correct for any errors in the position of the head. The device also includes circuitry for detecting cross track head speed per sector which produces a signal used to control the integration of the position error signal.