Abstract: Embodiments in accordance with the present invention ensure that the pitch of a servo write track is accurately controlled. According to one embodiment of the present invention, a Self Servo Write (SSW) uses different methods and sequences to identify read-write offsets (RWOs) and calculate target positions in inner and outer diameter sides of a magnetic disk. In the inner diameter-side area, the SSW controller uses the readout of a radial pattern written on a recording surface and a reference value to identify the RWO. The SSW controller uses the RWO value identified in the inner diameter-side area to anticipate an RWO value in the outer diameter-side area. In the outer diameter-side area, the SSW controller uses the anticipated RWO value to determine the target position of each servo write track.

Abstract: Embodiments of the invention provide an inexpensive magnetic head tester employing component parts of a production HDD and capable of exercising functions very close to those of a production HDD. In one embodiment, a magnetic head tester employs the VCM actuator and the control circuit of a production HDD and has a lightweight, simple HGA fixing mechanism mounted on an actuator arm. The HGA fixing mechanism fixes an HGA to the actuator arm by a method using a very light holding spring mounted on the arm, a method of mechanically clamping an HGA by using air pressure, or a method of fixing an HGA to the arm by elastically deforming a rubber clamping member by air pressure. Servo control is achieved by the actuator of a production VCM. An end part of the VCM actuator is stopped by a stopping mechanism and is held by a holding spring to prevent the runaway of the VCM actuator. Servo control is performed by balancing the driving force of the VCM and the resilience of the spring.

Abstract: A disk unit is capable of detecting a track, the track width of which deviates from a normal value, with high accuracy at high speed. A HDD includes a read head, a disk and defective-track detecting part. The disk has servo data including bursts A, B written thereon. The servo data is used to position the read head to a track center. The defective-track detecting part detects a defective track as below. The sum of the amplitude of bursts A and B, which have been read by the read head by one read operation, is divided by the amplitude of a burst C or D to obtain a compared value. If the compared value deviates from a criterion by a specified percentage or more, it is judged that the track width of a track is abnormal. Since bursts A through D are written without trimming, the size of bursts A through D in the track width direction are kept constant regardless of the track width. Accordingly, a gap G fluctuating in accordance with the track width is formed in the radial direction between bursts A and B.

Abstract: Embodiments in accordance with the present invention control pitch variations that are not observed in self servo write (SSW). According to one embodiment of the present invention, an outer radius side area of a magnetic disk is erased using an external magnetic field, and an inner radius side area is subjected to self erase using a head. The magnetization state in the base of the inner radius side area is different from that of the outer radius side area before pattern writing. Therefore, in the inner radius side area and the outer radius side area, even if a radial pattern of the same pitch is read, the different APCs are measured. With SSW of this embodiment, a reference APC used in the inner radius side area is different from that used in the outer radius side area. In this manner, the pitch variation is prevented.

Abstract: Embodiments in accordance with the present invention ensure that the pitch of a servo write track is accurately controlled. According to one embodiment of the present invention, a Self Servo Write (SSW) uses different methods and sequences to identify read-write offsets (RWOs) and calculate target positions in inner and outer diameter sides of a magnetic disk. In the inner diameter-side area, the SSW controller uses the readout of a radial pattern written on a recording surface and a reference value to identify the RWO. The SSW controller uses the RWO value identified in the inner diameter-side area to anticipate an RWO value in the outer diameter-side area. In the outer diameter-side area, the SSW controller uses the anticipated RWO value to determine the target position of each servo write track.

Abstract: Embodiments of the invention provide a disk device capable of writing highly accurate servo data using an extremely simple technique, and a manufacturing method therefor. According to one embodiment, a method for manufacturing a disk device includes: mounting a magnetic disk and each assembly for driving the magnetic disk, such as an SPM and a VCM, in a base and attaching a top cover so as to seal the enclosure (made up of the base and the top cover) with each assembly of the HDD therein; replacing the air within the hard disk assembly (HDA) with a gas having a lower density than air, such as He; writing servo data to the magnetic disk in a self servo track write operation; and replacing the gas within the HDA with air.

Abstract: Embodiments of the invention provide an inexpensive magnetic head tester employing component parts of a production HDD and capable of exercising functions very close to those of a production HDD. In one embodiment, a magnetic head tester employs the VCM actuator and the control circuit of a production HDD and has a lightweight, simple HGA fixing mechanism mounted on an actuator arm. The HGA fixing mechanism fixes an HGA to the actuator arm by a method using a very light holding spring mounted on the arm, a method of mechanically clamping an HGA by using air pressure, or a method of fixing an HGA to the arm by elastically deforming a rubber clamping member by air pressure. Servo control is achieved by the actuator of a production VCM. An end part of the VCM actuator is stopped by a stopping mechanism and is held by a holding spring to prevent the runaway of the VCM actuator. Servo control is performed by balancing the driving force of the VCM and the resilience of the spring.

Abstract: Embodiments of the invention provide a disk device capable of writing highly accurate servo data using an extremely simple technique, and a manufacturing method therefor. According to one embodiment, a method for manufacturing a disk device includes: mounting a magnetic disk and each assembly for driving the magnetic disk, such as an SPM and a VCM, in a base and attaching a top cover so as to seal the enclosure (made up of the base and the top cover) with each assembly of the HDD therein; replacing the air within the hard disk assembly (HDA) with a gas having a lower density than air, such as He; writing servo data to the magnetic disk in a self servo track write operation; and replacing the gas within the HDA with air.

Abstract: A disk unit is capable of detecting a track, the track width of which deviates from a normal value, with high accuracy at high speed. A HDD includes a read head, a disk and defective-track detecting part. The disk has servo data including bursts A, B written thereon. The servo data is used to position the read head to a track center. The defective-track detecting part detects a defective track as below. The sum of the amplitude of bursts A and B, which have been read by the read head by one read operation, is divided by the amplitude of a burst C or D to obtain a compared value. If the compared value deviates from a criterion by a specified percentage or more, it is judged that the track width of a track is abnormal. Since bursts A through D are written without trimming, the size of bursts A through D in the track width direction are kept constant regardless of the track width. Accordingly, a gap G fluctuating in accordance with the track width is formed in the radial direction between bursts A and B.