Abstract: According to one embodiment, a method of writing a target servo pattern constituting concentric servo tracks on a disk medium provided in a disk drive. In the method, a cumulative amplitude value of the waveform of each spiral servo pattern reproduced by the head of the disk drive is calculated, a slope of each spiral servo pattern is calculated from the cumulative amplitude value, and a pitch at which the head should be moved to write the target servo pattern is determined on the basis of the slopes of the spiral servo patterns.

Abstract: According to one embodiment, a disk drive having a disk medium on which servo data is recorded, and a control unit that controls the positioning of a head, moving the head to a target position on the disk medium in accordance with the servo data. The servo data contains servo-burst patterns written in units of servo-track pitches. A part of each servo-burs pattern is invalidated (trimmed).

Abstract: According to one embodiment, in a disk drive having a disk medium on which servo data is recorded, servo-write management information is recorded on the disk medium, in the form of binary data based on the 0 or 180 degrees out of phase pattern composed of the servo burst signals included in the servo data and being out of phase. The disk drive includes a servo-data reproducing unit that reproduces the servo data and the servo-write management information.

Abstract: According to one embodiment, a self-servo writing method for use in disk drives, which has a first process and a second process. In the first process, a base-servo pattern containing address codes and servo-burst patterns is recorded on a disk medium in units of one-track pitches. In the second process, a drive-servo pattern, which is a spiral servo pattern, is recorded on the disk medium, by using the base-servo pattern and the self-servo writing function of the disk drive.

Abstract: According to one embodiment, in a disk drive which performs positioning control of a head on the basis of a servo burst pattern recorded on a disk medium, a servo processor generates a tangent-equivalent value by using a burst value obtained from the servo burst pattern. Furthermore, the servo processor executes an arctangent transform process by an inverse function approximate expression structured on the basis of a relationship between an off-track position and the tangent-equivalent value to detect the off-track position.

Abstract: According to one embodiment, a servo information writing method for use in a disk drive, for recording the servo information, forming a continuous servo track such as a spiral track. In this servo information writing method, the head is stopped when a write error is detected while the servo information is being written, and the head is then moved again at a constant speed and starts writing the servo information again, at the position where the write error has occurred.

Abstract: According to one embodiment, there is to provide a data write method which is applied to a disk drive, for recording data on a disk medium by a head mounted on a rotary type actuator. The method carries out a track pitch conversion processing so that a track pitch of data track is set larger than a track pitch in an intermediate circumferential area based on an azimuth angle of the head in the case where the position of the data track is included in an inner circumferential area or outer circumferential area on the disk medium.

Abstract: According to one embodiment, a disk drive is provided which corrects already existing offset information according to a variation of a disk runout amount caused by an occurrence of a disk shift. The disk drive effects a head position adjustment at a head positioning control time with the use of offset information stored in a memory. A CPU measures a variation in the disk runout amount and phase caused by an occurrence of a disk shift resulting from an external shock involved and updates the existing offset information with a correction offset information based on a result of measurement.

Abstract: A method of writing servo information for use in head positioning control on a disk medium incorporated in a disk drive, including executing the head positioning control based on original servo information recorded on the disk medium, producing positioning correction information to correct a positioning error, and recording the positioning correction information in a correction information recording buffer.

Abstract: According to one embodiment, in a disk drive using a disk medium storing spiral servo information, a CPU generates virtual servo information having assumed virtual track centers corresponding to centers of concentric data tracks. The CPU performs control to position a head to the center of the concentric data track by using the virtual servo information.

Abstract: According to one embodiment, a servo write method for writing servo information to a disk medium used in a disk drive is disclosed. In the procedure of the servo write method, first servo information is spirally written to a disk medium in a clean room before the disk medium is incorporated into the disk drive, then, the disk medium is incorporated into the disk drive, and second servo information is concentrically written to the disk medium already incorporated in the disk drive.

Abstract: When a sub-track having burst data A and D, a sub-track having burst data A and C, a sub-track having burst data B and C, and sub-track having burst data B and D are repeatedly arranged in this order, in accordance with equations 1 and 2, a sub-track t included in a track T determines the value of a constant n within a range of 1.2 (inclusive) to 1.8 (inclusive) so as to obtain linearity between a position in a disc radial direction r and a head position P in a disc radial direction r in the sub-track t.

Abstract: According to one embodiment, in a disk drive which performs positioning control of a head on the basis of a servo burst pattern recorded on a disk medium, a servo processor generates a tangent-equivalent value by using a burst value obtained from the servo burst pattern. Furthermore, the servo processor executes an arctangent transform process by an inverse function approximate expression structured on the basis of a relationship between an off-track position and the tangent-equivalent value to detect the off-track position.

Abstract: When a sub-track having burst data A and D, a sub-track having burst data A and C, a sub-track having burst data B and C, and sub-track having burst data B and D are repeatedly arranged in this order, in accordance with equations 1 and 2, a sub-track t included in a track T determines the value of a constant n within a range of 1.2 (inclusive) to 1.8 (inclusive) so as to obtain linearity between a position in a disc radial direction r and a head position P in a disc radial direction r in the sub-track t.

Abstract: According to one embodiment, there is to provide a data write method which is applied to a disk drive, for recording data on a disk medium by a head mounted on a rotary type actuator. The method carries out a track pitch conversion processing so that a track pitch of data track is set larger than a track pitch in an intermediate circumferential area based on an azimuth angle of the head in the case where the position of the data track is included in an inner circumferential area or outer circumferential area on the disk medium.

Abstract: An additive self-servowriting method that records a servo pattern on a disk surface in a disk drive is disclosed. A servowriting method according to the present invention writes an initial servo pattern with a head moved to the inner circumference of the disk at the initial time. Then, additive servowriting operation is performed to write an additive servo pattern with the head positioned in the outer circumferential direction of the disk. When it is impossible to continue the additive servowriting operation in the middle of the operation, the head is set back to the previous additive servo pattern to resume the additive servowriting operation.

Abstract: There is disclosed a servo information writing method of writing servo information for use in head positioning control on a disk medium incorporated in a disk drive. The present method executes a procedure having a step of executing the head positioning control based on original servo information recorded on the disk medium, a step of producing positioning correction information to correct a positioning error, and a step of recording the positioning correction information in a correction information recording buffer.

Abstract: There is disclosed a servo information writing apparatus comprising a disk drive and an examination unit. The examination unit executes examination to select an adequate servo pattern as servo information from a plurality of types of servo patterns recorded beforehand in a disk medium incorporated in the disk drive. The selection unit executes an examination to select the adequate servo pattern by use of a control and signal processing system incorporated in the disk drive.

Abstract: There is disclosed a self-supporting-type servo writing apparatus in which a head of a disk drive is used to write a servo pattern on a disk. In the disk drive, the disk is incorporated in which a clock pattern is pre-written as a signal pattern for position detection in a rotation direction. The servo writing apparatus uses the servo pattern written on the disk by a write head device to successively add the servo pattern into the whole surface on the disk.

Abstract: An additive self-servowriting method that records a servo pattern on a disk surface in a disk drive is disclosed. A servowriting method according to the present invention writes an initial servo pattern with a head moved to the inner circumference of the disk at the initial time. Then, additive servowriting operation is performed to write an additive servo pattern with the head positioned in the outer circumferential direction of the disk. When it is impossible to continue the additive servowriting operation in the middle of the operation, the head is set back to the previous additive servo pattern to resume the additive servowriting operation.