Partial servo write fill in

Details Partial servo write fill in Partial servo write fill in

2001-07-13

2004-03-30

Sniezek, Andrew L. (Department: 2651)

Dynamic magnetic information storage or retrieval

Automatic control of a recorder mechanism

Controlling the head

Reexamination Certificate

active

06714376

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to servo information for magnetic storage devices and, more particularly, to writing servo information to disks during the manufacturing process.
BACKGROUND OF THE INVENTION
Magnetic heads are used to read data from and write data onto certain data regions of magnetic disks. To accurately perform these operations, it is important that the heads be properly positioned over the data regions. Servo-systems are conventionally used in an attempt to ensure the proper positioning of the heads relative to the data regions. Servo-systems sense the position of the heads and generate position error (“PES”) signals to adjust the position of the heads to their respective proper locations over the magnetic disks. The PES signal is generated from a predefined servo pattern which is located at certain points on the disk surface, and will be discussed in more detail below.
A standard disk drive, generally designated
10
, is illustrated in FIG.
1
. The disk drive comprises a disk
12
that is rotated by a spin motor
14
. The spin motor
14
is mounted to a base plate
16
. An actuator arm assembly
18
is also mounted to the base plate
16
. The actuator arm assembly
18
includes a head
20
mounted to a flexure arm
22
, which is attached to an actuator arm
24
that can rotate about a bearing assembly
26
. The disk drive
10
also includes a voice coil motor
28
which moves the head
20
relative to the disk
12
. The spin motor
14
, voice coil motor
28
and head
20
are coupled to a number of electronic circuits
30
mounted to a printed circuit board
32
. The electronic circuits
30
typically include a read channel chip, a microprocessor-based controller and a random access memory (RAM) device.
The disk drive
10
typically includes a plurality of disks
12
and, therefore, a plurality of corresponding actuator arm assemblies
18
. However, it is also possible for the disk drive
10
to include a single disk
12
as shown in FIG.
1
.
Referring now to
FIG. 2
, data is stored on the disk
12
within a number of concentric radial tracks
40
(or cylinders). Some tracks
40
may solely contain servo information, while other tracks may contain both servo information and data. Typically, however, tracks
40
contain both servo information and data. Each track
40
is divided into a plurality of sectors
42
. In tracks
40
which contain both servo information and data, each sector
42
is further divided into a servo region
44
and a data region
46
.
The servo regions
44
of the disk
12
are used to, among other things, accurately position head
20
(the head
20
is shown in
FIG. 1
) so that data can be properly written onto and read from the disk
12
. The data regions
46
are where non-servo related data (i.e., user data) is stored and retrieved. Such data, upon proper conditions, may be overwritten.
Each track
40
has a centerline
48
. To accurately write and read data from the data region
46
of the disk
12
, it is desirable to maintain the head
20
in a relatively fixed position with respect to a given track's centerline
48
during each of the writing and reading procedures. For simplicity and for purposes of demonstrating the invention, it will be assumed that the head
20
should be positioned on, or substantially on, a given track's centerline
48
to accurately read data from and write data to the data region
46
of that track
40
. It should be noted, however, that the invention described herein is equally applicable to those systems which incorporate a read or write offset from the track centerline, as will be understood by those skilled in the art.
To assist in controlling the position of the head
20
relative to the track centerline
48
, the servo region
44
contains, among other things, servo information in the form of servo patterns
50
comprised of groups of servo bursts A, B, C, D as shown in FIG.
3
. The servo bursts A, B, C, D are accurately positioned relative to the centerline
48
of each track
40
, are typically written on the disk
12
during the manufacturing process using a servo track writer (“STW”) and, unlike information in the data region
46
, may not be over-written or erased during normal operation of the disk drive
10
.
As shown in
FIG. 3
, the A and B burst pairs define what are conventionally known as the Norms. The difference in amplitude between the A and B bursts at a particular head position is defined as the Norms signal (in units of volts) and is represented by N=A−B. A Norms curve can be developed to represent Norms signals for head positions across an entire track. Likewise, the C and D burst pairs define what are conventionally known as the Quads. The difference in amplitude between the C and D bursts at a particular head position is defined as the Quads signal (in units of volts) and is represented by Q=C−D. A Quads curve can be developed to represent Quads signals for head positions across an entire track.
Traditionally, during the manufacturing process of the disk drive
10
, a servo-track writer (not shown) is used to write servo information, including servo bursts A, B, C, D onto each of the servo regions
44
of the disk
12
. The servo track writer includes its own write heads which are used to write the servo information to the disks prior to the disks being sealed within the disk drive. The servo track writer is a highly specialized, and high-priced piece of equipment which writes the servo bursts at precise locations on the disk surfaces. It would therefore be advantageous to use as few servo track writers in a manufacturing production line as possible in order to reduce capital costs of additional servo track writers.
As will be understood by those of skill in the art, disk drives are generally manufactured in clean rooms, which provide a manufacturing environment that is largely free of external contamination. Because disks may be exposed during the manufacturing process, it is important to reduce external contamination. External contamination on a disk surface can, in certain situations, damage or degrade the performance of a disk drive. As part of the manufacturing process, the servo-track writer is located in the clean room with the other manufacturing tools which require a clean room environment.
Clean rooms are generally very expensive to construct and operate. Constructing a clean room requires sophisticated manufacturing techniques which are more expensive than construction techniques used for standard, non-clean room construction. Additionally, clean rooms require sophisticated air handling and filtration hardware, which adds to the cost of construction as well as operating costs. Accordingly, it would be advantageous to minimize the size of a clean room, and thus reduce the capital costs of construction and operating costs.
As disk drive technology progresses, more and more information is able to be stored onto a single disk. Accordingly, the number of tracks per inch on a disk is continually increasing. As discussed above, tracks have associated servo information. Therefore, when additional tracks are included on a disk, additional servo information must be written to each disk. This requires additional time for each disk to be in the servo track writer. As a result, additional servo track writers are needed to support the same build rate of drives on a production line as track density increases. Additional servo track writers result in additional capital costs for both the additional equipment, and the additional clean room space required to house the additional equipment. Furthermore, the additional servo track writers may be difficult to fit into an existing facility, possibly resulting in a reduced output capacity for a facility as track density increases.
Some existing solutions to the problem of trying to reduce the number of servo track writers located in a production line are to pre-write disks prior to the manufacturing process which incorporates the disks into disk drives. Such pre-writing may be b

Affiliated with

Also associated with

Rating

Partial servo write fill in does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Partial servo write fill in, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Partial servo write fill in will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3208955