Dynamic magnetic information storage or retrieval – Automatic control of a recorder mechanism – Controlling the head
Reexamination Certificate
1998-08-07
2002-03-19
Hudspeth, David (Department: 2651)
Dynamic magnetic information storage or retrieval
Automatic control of a recorder mechanism
Controlling the head
C360S059000, C369S013010, C369S014000
Reexamination Certificate
active
06359747
ABSTRACT:
BACKGROUND INFORMATION
Disk drives are information storage devices that use thin film magnetic media to store data. A hard disk drive includes one or more rotatable disk, each having closely spaced concentric data tracks. Each track is further subdivided into sectors wherein data is stored. As a disk rotates, a transducer (or “head”) is positioned by an actuator to magnetically read data from or write data to the various sectors within the tracks on the disk.
Prior to a disk drive's use in a computer, formatting information is written to disk surfaces in the drive. This formatting information can include, for example, the location of each data storage sector, sector number identification information, the start of a group of sectors, and servo pattern information. Disk formatting information enables essential drive operations and/or provides for improved disk drive operation or features. For example, as described below, servo pattern information can be used to maintain a drive's magnetic head alignment.
To accurately read or write data to a disk, the drive's magnetic head must remain closely aligned with the particular track being accessed. If the head deviates from the track, data may be read or written improperly. This can result in irretrievable data and damage to existing stored data.
To maintain alignment between the head and track, a closed-loop alignment system is used. In conventional head alignment systems, magnetic markers on one or more disk surfaces are used to guide the heads. These markers, known as servo patterns, provide dynamic head position feedback to. a head control mechanism. In response to detected servo pattern signals, the control mechanism can adjust head alignment while reading or writing data to the disk.
Magnetic servo patterns are typically written to a disk surface on a track-by-track basis during the final stages of disk drive assembly. A disk may have many thousands of tracks, consequently, “formatting” the disk with servo patterns and/or other formatting information can be a time-consuming process. Advantages in the manufacture of disk drives may be obtained by disk formatting methods allowing formatting information to be simultaneously created across an area of the disk surface. Such formatting methods may provide for an decrease in the total time required to format the disk.
SUMMARY
Magnetic disk formatting pattern are formed on disk surfaces during the manufacture of computer hard disk drives. Disk formatting systems may use a conventional magnetic read/write head to write formatting information to a spinning disk on a track-by-track and/or sector-by-sector basis. Such conventional systems may require a significant amount of time to complete the disk formatting process. According to the invention, advantages in the manufacture of disk drive media can be obtained by systems and methods allowing a region of a disk to simultaneously receive a magnetic disk formatting pattern. The disclosed systems and methods may allow many hundreds or thousands of bit or “dibit” positions to simultaneously receive disk formatting information. The transfer of the formatting information may be accomplished by raising the temperature of multiple bit or dibit positions on a disk surface pattern area using a projected image of the desired pattern and magnetically altering the properties of the raised temperature regions. Other features of implementations of the invention are described.
In general, in one aspect, the invention features a method of forming a pattern on magnetic disk media. The method includes elevating the temperature of a pattern area and exposing the area to a magnetic field. The magnetic field has a field strength sufficient to alter magnetic properties of the elevated temperature region, but insufficient to substantially alter magnetic properties of disk regions at the disk's ambient temperature.
Implementations of the invention may include one or more of the following features. The magnetic direction of disk surface particles may be altered by exposure to the magnetic field. The magnetic field may have a field strength greater than the coercivity of the media at the elevated temperature but less than the coercivity of the media at the media's ambient temperature. The magnetic disk may be rotated to a second position at which a second area of the disk is formatted.
Implementations may also include one or more of the following features. A substantially magnetically uniform disk surface may be established prior to exposing the pattern area to the magnetic field. The uniform disk surface may be established by exposing the magnetic disk surface to a conditioning field thereby causing disk surface particles to have a substantially uniform magnetic field strength and direction. Elevating the pattern area temperature may include projecting a pattern image on the disk surface. Projecting a pattern image may include directing a light beam through a pattern mask that has substantially opaque and substantially transparent regions or may include directing a modulated laser beam at the disk surface. An optical projection system may also be employed to project the pattern image.
In general, in another aspect, the invention features a magnetic disk patterning system. The system includes a light source assembly, a pattern mask, and a magnetic field source. The light source assembly is arranged to project a light beam toward a surface of a magnetic disk. The pattern mask is arranged in the path of the light beam to produce a pattern image on the disk surface, and the magnetic field source produces a magnetic field at disk surface regions receiving the pattern image.
Implementations of the invention may include one or more of the following features. The pattern image produced on the disk surface may elevate the temperature of the receiving disk surface. The magnetic field source may produce a magnetic field having a field strength greater than the coercivity of the media at the elevated temperature but less than the coercivity of the media at the disk's ambient temperature. The system may include control circuitry operative to regulate the strength and direction of the produced magnetic field. The light source assembly ma y include a modulated laser. The system may also include a motor assembly to alter the position of the magnetic disk surface with respect to the magnetic field.
In general, in another aspect, the invention features a magnetic disk patterning system. The system includes a magnetic field assembly for exposing a region of a magnetic disk to a magnetic field. The system also includes pattern production means to produce a pattern on the disk in the region exposed to the magnetic field.
In various implementations, the invention may provide an advantageous increase in disk formatting rate. Furthermore, improvements in formatting information positioning accuracy may be gained. Other advantages and features will become apparent from the following description and from the claims.
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Clifford Chance Rogers & Wells LLP
Davidson Dan I.
Hudspeth David
Mahon, Esq. James V.
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