Dynamic magnetic information storage or retrieval – General recording or reproducing – Specifics of the amplifier
Reexamination Certificate
2001-03-07
2004-04-27
Hudspeth, David (Department: 2697)
Dynamic magnetic information storage or retrieval
General recording or reproducing
Specifics of the amplifier
C360S067000, C360S046000
Reexamination Certificate
active
06728057
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to data storage systems and, in particular, to a frequency range extension technique for flex-on-suspension (FOS) equipped magneto-resistive (MR) read/write head assembly.
BACKGROUND OF THE INVENTION
In disc drives and other data storage systems, digital data are written to and read from data storage surfaces. Read and write operations are performed through a transducer which is typically carried on a slider body. The slider and the transducer are sometimes collectively referred to as a head, and typically a single head is associated with each data storage surface. Data are stored by magnetizing the disc storage surface in one of two possible orientations to indicate either a logic 0 or a logic 1. This is referred to as a “write” operation. When writing data, the head (sometimes referred to as the write head) carries a current which creates a magnetizing force large enough to saturate the magnetic medium. This write current is provided by a write current source which is coupled to the head through an electrical interconnect path. The source, head and interconnect path together form a write circuit. The write circuit keeps the current constant when a logic 0 is written on the disc, and when writing a logic 1, the write circuit reverses the polarity of the current to switch the orientation of the magnetization on the disc.
In any transmission system such as the write circuit, a source sends energy to a load. Ideally, the transmission network should have impedances of the source, the transmission line and the load, all identical. Unfortunately, many real-world situations prevent the match from being perfect. Typically, a mismatch exists between the source impedance and the impedance of the head (load impedance) in the write circuit. Maximum power transfer occurs in a circuit when the load impedance equals the source impedance of the driving waveform. When the source and load impedance are not equal and there is distance between the two impedances, some portion of the energy intended to be delivered to the load will be reflected back toward the source causing signal distortion. This is a typical problem in digital circuit board design and the phenomenon exhibits itself more and more as signal bandwidths become significant relative to the circuit distances involved. As the data transfer rates in disc drives increase, the write waveform rise time will decrease. As the rise time decreases, the signal bandwidth occupied by the write waveform increases. The wave length of the higher order harmonics of the write waveform are now short enough, relative to the signal path length, that the reflected energy from the write head will have an opportunity to distort the write waveform. Energy is reflected back from the head due to an impedance mismatch from the head and through the impedance of the interconnect path to the source impedance.
One remedy to this problem is to place the source (read/write interface) closer to the head thereby shortening the distances involved such that the reflection phenomenon is negligible. However, this solution comes at the cost of one read/write interface per head and replication of the associated interconnect and support circuitry required for each read/write interface as opposed to a single multi-channel read/write interface mounted on a single supporting circuit addressing a multitude of heads as used in current products.
The present invention addresses these problems, and offers other advantages over the prior art.
SUMMARY OF THE INVENTION
The present invention relates to data storage systems that have a connection device which solves the above-mentioned problem.
A disc drive storage system and device is provided in which distortion in a drive signal due to a mismatch between a signal source impedance and a write head impedance is minimized. A write head that writes on a disc surface and a signal source that provides a drive signal to the write head are coupled by an electrical interconnect path. A connection device that minimizes the mismatch between the signal source impedance and the write head impedance is introduced in the electrical interconnect path. In addition, a method of coupling a signal source to a write head in a disc drive storage system is provided.
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Figueroa Natalia
Hudspeth David
Seagate Technology LLC
Westman Champlin & Kelly
LandOfFree
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