Dynamic magnetic information storage or retrieval – Automatic control of a recorder mechanism – Controlling the head
Reexamination Certificate
2006-08-15
2006-08-15
Young, Wayne (Department: 2627)
Dynamic magnetic information storage or retrieval
Automatic control of a recorder mechanism
Controlling the head
C360S077020
Reexamination Certificate
active
07092197
ABSTRACT:
A positioning driver (32) for a voice coil motor (22) in a disk drive system (10) is disclosed. Pulse-width-modulated prestage drivers (46) are coupled to power transistors (50) arranged in an “H” bridge for driving the voice coil motor (22), biased with a power supply voltage (VM). The pulse-width-modulated prestage drivers (46) drive the power transistors (50) according to a comparison between an error signal from an error amplifier (36) and a ramp clock signal (RMP) generated by a ramp clock generator (46). The ramp clock generator (46) includes a control circuit (68) that modulates the high and low limits of the ramp clock signal (RMP) in response to variations in the power supply voltage (VM). This modulation of the high and low limits compensates for variations in the gain of the power transistors (50) resulting from variations in the power supply voltage (VM). The control circuit (68) may also modulate the slope of the ramp clock signal (RMP) according to variations in the power supply voltage (VM), for example to maintain a constant frequency.
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El-Sherif Alaa Y.
Plutowski Eugene F.
Ziemer Kevin W.
Brady W. James
Olson Jason
Telecky , Jr. Frederick J.
Texas Instruments Incorporated
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