Magnetic recording disk drive with head positioning servo control system for disk surfaces with identical servo patterns

Abstract

A magnetic recording disk drive has disks with identical pre-patterned servo patterns on their front and back surfaces and a servo control system for positioning the read / write heads using the servo signals from the identical servo patterns. The servo sectors on the two disk surfaces form identical patterns of angularly spaced arcuate-shaped lines that extend generally radially across the data tracks. The arcuate-shaped lines on one surface, the front surface, generally replicate the path of the recording head as it is moved across the data tracks by a rotary actuator, so that there is a constant sampling rate of the servo sectors on the front surface regardless of radial position of the head. However, the arcuate-shaped lines on the other surface, the back surface, do not replicate the path of the recording head so the servo sampling rate is not constant but varies with radial position of the head. The disk drive servo control system implements a method to enable track seeking from one data track to another data track, regardless of whether the initial disk surface and the destination disk surface are front or back surfaces.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]This invention relates generally to a magnetic recording disk drive that has disks with pre-patterned servo patterns formed with a master template, and more particularly to a magnetic recording disk drive with a servo control system for positioning the read / write heads on the disk surfaces by using the servo patterns.[0003]2. Description of the Related Art[0004]Conventional magnetic recording hard disk drives use either horizontal recording wherein the magnetized regions that define the magnetically recorded data bits are oriented in the plane of the recording layer on the hard disks, or perpendicular recording wherein the magnetized regions are oriented perpendicular to the plane of the recording layer. Each recording surface on the disks is a continuous layer of magnetic material that becomes formed into concentric data tracks containing the magnetically recorded data bits when the recording head writes on the magneti...

AI Technical Summary

Benefits of technology

The invention is a magnetic recording disk drive with disks that have identical pre-patterned servo patterns on both surfaces. The servo patterns are pre-patterned with a single master template, resulting in the identical pattern on each disk surface. The servo sectors on the two disk surfaces form identical patterns of angularly spaced arcuate-shaped lines that extend generally radially across the data tracks. The arcuate-shaped lines on one surface, the front surface, generally replicate the path of the recording head so there is a constant sampling rate of the servo sectors on the front surface regardless of radial position of the head. However, the arcuate-shaped lines on the other surface, i.e., the back surface, do not replicate the path of the recording head so the servo sampling rate is not constant but varies with radial position of the head. The servo control system implements a method to enable track seeking from one data track to another data track, regardless of whether the initial disk surface and the destination disk surface are front or back surfaces. The servo signal from a front surface is used during a first seek phase and the servo signal from the destination surface, which is a back surface, is used during the last phase of the seek. The servo control system switches over to receive the servo signals from the destination surface during the second phase of the seek, i.e., when the head is within a predetermined number of tracks where variation in servo timing is small enough to be tolerated. The technical effect of this invention is to improve the accuracy and efficiency of the magnetic recording disk drive by using identical servo patterns on both surfaces and a servo control system to position the read / write heads using the servo signals from the identical servo patterns.

Problems solved by technology

However, the arcuate-shaped lines on the other surface, i.e., the back surface, do not replicate the path of the recording head so the servo sampling rate is not constant but varies with radial position of the head.

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