Motor drive semiconductor integrated circuit and magnetic disk storage apparatus

Abstract

The invention provides a motor drive semiconductor integrated circuit for driving and controlling a voice coil motor that can conduct a seek operation, a track follow operation and a settling operation through PWM control, has desired control accuracy and can be produced by a CMOS process. In a voice coil motor drive circuit for executing positioning control of a magnetic head by feedback-controlling a driving current of a voice coil motor for moving a magnetic head over a magnetic disk for reading information from a storage track on the magnetic disk driven for rotation while a read state of the magnetic head is being monitored, head movement control such as a seek operation, a track follow operation etc, of the magnetic head is executed by PWM driving on the basis of a command value from a controller.

Description

CROSS-REFERENCE TO RELATED APPLICATION [0001] The present application is a continuation of application Ser. No. 11 / 098,644, filed Apr. 5, 2005, which claims priority from Japanese patent application No. 2004-111817, filed on Apr. 6, 2004, the content of which is hereby incorporated by reference into this application.BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] This invention relates to a control technology of a magnetic disk storage apparatus and further to a control technology of a voice coil motor for moving a magnetic head for conducting read / write of information from and to a storage track on a magnetic storage disk that is driven and rotated. [0004] 2. Description of the Related Art [0005] A magnetic disk storage apparatus includes a magnetic head for executing read / write of information to and from a storage track on a magnetic storage disk driven and rotated, a voice coil motor for moving the magnetic head on the disk and a voice coil motor drive control...

AI Technical Summary

Benefits of technology

"The patent text describes a motor drive semiconductor integrated circuit for a voice coil motor used in a magnetic disk storage apparatus. The circuit can conduct both seek operation and track follow operation through PWM driving, but there are challenges in designing a control circuit that can achieve both high precision and low power consumption. The first invention aims to address these challenges by optimizing the control circuit design and using a digital circuit for the whole control system, which can reduce quantization noise and improve the S / N ratio. The second invention aims to further improve the precision of the control circuit by using a ΣΔ modulation circuit. Overall, the patent text describes a solution for designing a motor drive semiconductor integrated circuit with improved control accuracy and efficiency."

Problems solved by technology

In the system that switches PWM driving to linear driving at the shift of the seek operation to the track follow operation, however, switching must be conducted smoothly and quickly but precision switching control is difficult.

Because a control circuit for PWM driving and a control circuit for linear driving must be designed separately and optimally, a design load becomes great and the circuit scale increases.

Nonetheless, it is relatively difficult to fabricate the D / A conversion circuit having 16 or more bits by a CMOS process that is predominant in existing semiconductor fabrication technologies.

A system that detects a voltage occurring across both ends of a resistor connected in series with a coil has generally been employed in the past as a current detection system for the feedback control of the voice coil motor but it has been clarified that this system involves various problems such as a voltage loss in the sense resistor and a detection error resulting from jitter of a sampling clock.

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