Dynamic magnetic information storage or retrieval – General processing of a digital signal – Head amplifier circuit
Reexamination Certificate
1998-04-30
2001-02-13
Kim, W. Chris (Department: 2753)
Dynamic magnetic information storage or retrieval
General processing of a digital signal
Head amplifier circuit
C360S066000
Reexamination Certificate
active
06188531
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
Embodiments of this invention relate generally to disk drives of the type generally used for storing digital data, and in particular to methods and devices for applying a temperature-compensated write current to read/write heads during disk drive write operations, and disk drive systems incorporating the same.
2. Description of Related Art
Modern computers require media in which digital data can be quickly stored and retrieved. Magnetizable (hard) layers on disks have proven to be a reliable media for fast and accurate data storage and retrieval. Disk drives that read data from and write data to hard disks have thus become popular components of computer systems.
FIG. 1
illustrates a conventional disk drive write system
2
comprising a disk drive microprocessor
4
, control logic
6
, read/write preamplifier
8
, coil
10
, read/write core
12
, and hard disk
14
. The read/write preamplifier
8
further includes a write current source
16
. During write operations, a computer
18
communicates through controller
20
with the disk drive microprocessor
4
. In response to commands from the controller
20
, the disk drive microprocessor
4
, by means of control logic
6
, provides a write signal
34
to the read/write preamplifier
8
. The read/write preamplifier
8
energizes the write current source
16
, which applies a write current
22
through coil
10
, inducing magnetic flux
24
to form within the read/write core
12
and fringe across a core gap
26
. The strength of the fringing magnetic flux
24
varies directly with the amount of write current
22
flowing through the coil
10
. The fringing magnetic flux
24
passes through magnetizable material
28
within the hard disk
14
located beneath the core gap
26
, causing that material to become magnetized and oriented in the direction of the magnetic flux
24
. As the hard disk
14
spins and the read/write core
12
passes over other magnetizable material during the course of a write operation, the direction of the write current
22
may be reversed, causing the fringing magnetic flux
24
to be oppositely oriented and reversing the polarity of the magnetizable material
28
. As the fringing magnetic flux
24
goes through a series of such reversals, a data pattern is formed within the hard disk
14
from the polarity sequence of the magnetizable material
28
.
In disk drive systems, the magnetizable material within the disk is “hard,” meaning that once the magnetizable material has been polarized and a data pattern established as described above, the polarity of the magnetized material and hence the data pattern will remain intact until a magnetic flux of sufficient magnitude reverses the polarity and changes the pattern. The measure of a magnetized material's hardness or ability to resist magnetic change is coercivity, H
c
, and a magnetized material's coercivity once a magnetizing flux has been removed is known as its residual or remnant coercivity, H
cr
. Another property of importance to consider is a magnetized material's intensity of magnetization, M, and its residual or remnant intensity of magnetization once a magnetizing flux has been removed, M
r
. Higher values of H
cr
and M
r
mean that a higher reverse-polarity magnetic flux is required to reverse the polarity of the magnetized material.
SUMMARY OF THE DISCLOSURE
Therefore, it is an object of embodiments of the invention to provide a system, method, or device for sensing temperature during the writing of information onto a hard disk and providing a sufficient write current for that temperature.
It is a further object of preferred embodiments of the invention to provide a system, method, or device for automatically sensing temperature during the writing of information onto a hard disk and automatically providing a sufficient write current for that temperature.
It is a further object of preferred embodiments of the invention to provide a system, method, or device for automatically sensing temperature during the writing of information onto a hard disk and automatically providing a sufficient write current for that temperature that can be easily manufactured at a low cost.
These and other objects are accomplished according to a system for sensing temperature during the writing of information onto a hard disk and providing a sufficient write current for that temperature, wherein the system is comprised of a head responsive to a write current for generating a magnetic flux used in writing data onto a hard disk, a write current source coupled to the head for receiving a write signal and providing write current to the head, and a temperature sensing device coupled to the write current source that senses temperature and provides the write signal whose magnitude is dependent on temperature.
These and other objects, features, and advantages of embodiments of the invention will be apparent to those skilled in the art from the following detailed description of embodiments of the invention, when read with the drawings and appended claims.
REFERENCES:
patent: 3708720 (1973-01-01), Whitney et al.
patent: 4207601 (1980-06-01), Desai et al.
patent: 5337012 (1994-08-01), Dijkmans
patent: 5408365 (1995-04-01), Van Doorn et al.
Chang James Lai Kein
Gan Kah Liang
Ngwe Myint
Quak Beng Wee
Kim W. Chris
Merchant & Gould P.C.
Neal Regina Y.
Seagate Technology LLC
LandOfFree
System method and device for generating a temperature... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with System method and device for generating a temperature..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and System method and device for generating a temperature... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2578913