Dynamic magnetic information storage or retrieval – General processing of a digital signal – Head amplifier circuit
Reexamination Certificate
1998-06-26
2001-01-23
Kim, W. Chris (Department: 2753)
Dynamic magnetic information storage or retrieval
General processing of a digital signal
Head amplifier circuit
C360S067000, C327S108000, C327S538000
Reexamination Certificate
active
06178055
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to the field of disc drive storage devices, and more particularly, but not by way of limitation, to a high performance negative voltage regulator suitable for use in a disc drive.
BACKGROUND OF THE INVENTION
To operate properly, electrical circuitry often requires a supply of voltage at a negative potential with respect to ground (i.e., a negative voltage). Such is typically the case for a disc drive, which is a digital data storage device which enables a user of a computer system to store and retrieve large amounts of data in a fast and efficient manner.
A typical desktop computer disc drive requires a variety of operational voltage input levels, including negative five volts (−5V) and positive five and twelve volts (+5 and +12V). These voltages can be supplied externally by a computer power supply, or generated internally by appropriate circuitry of the disc drive. For example, some disc drives incorporate an inverting power supply to generate the requisite −5V from an externally supplied +5V input.
In a typical drive, data are magnetically stored using a plurality of read/write heads which controllably access recording surfaces of a plurality of corresponding, rotatable discs. The heads are moved relative to the discs by an actuator assembly and a closed-loop, servo control system. A preamplifier/driver circuit, typically mounted directly to the actuator assembly, facilitates the writing and reading of data by providing write currents to the heads during a write operation and read bias currents to the heads during a read operation.
A typical preamplifier/driver circuit utilizes a negative voltage (such as −5V) in the generation of both read bias and write currents. It is desirable that the negative voltage be provided at a nominally constant level, as noise and voltage fluctuations present in the negative voltage can adversely affect both the writing and reading of data.
A variety of negative voltage supplies have been disclosed in the prior art, including European Patent Application No. 91 120 787.6 (published Jun. 10, 1992 as Publication No. 0 489 412 A2) and International Patent Application No. PCT/US93/12178 (published under the Patent Cooperation Treaty on Jun. 22, 1995 as Publication No. WO 95/17036). These and other similarly constructed prior art negative voltage power supplies typically utilize a capacitor which alternatively stores a charge from a positive voltage source and then transfers the charge to generate the negative voltage across the load.
Although operative for some applications, the increasingly stringent requirements particular to disc drive applications such as faster current responses and significantly lower levels of ripple distortion over a variety of current loads limits the feasibility of such prior art sources. There is a need, therefore, for an improved negative voltage supply capable of outputting a low ripple, fast-response, constant negative voltage over a wide range of loads.
SUMMARY OF THE INVENTION
The present invention provides an apparatus and method for generating a low ripple negative voltage suitable for use in data transfer operations of a high performance disc drive.
As exemplified by a preferred embodiment, a negative voltage supply is provided which includes a pulse generator circuit which generates first and second analog driver signals (herein referred to as DR
1
, DR
2
) in relation to a load of the negative voltage supply. The first driver signal DR
1
comprises a series of periodically occurring first pulses and the second driver signal DR
2
comprises a series of periodically occurring second pulses. The first and second pulses are mutually exclusive in time so that at least a minimum delay of selected, nonzero length (herein referred to as t
D
) is provided between transitions of subsequently occurring first and second pulses.
The negative voltage supply further includes a regulator circuit, operably coupled to the pulse generator circuit, which generates the negative voltage in response to the first and second driver signals utilizing a pair of storage capacitors which alternately accumulate and transfer charge to an output capacitor.
These and various other features as well as advantages which characterize the present invention will be apparent from a reading of the following detailed description and a review of the associated drawings.
REFERENCES:
patent: 0257810A2 (1988-03-01), None
patent: 0489412A2 (1992-06-01), None
patent: WO 95/17036 (1995-06-01), None
Crowe & Dunlevy
Kim W. Chris
Seagate Technology LLC
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