Renesas Technology Corp.

Hitachi Ulsi Systems Co., Ltd.

Kenji Yoshida

Hiroshi Sato

Kichiya Itagaki

Kenji Nishimura

Hiroshi Satou

A drive control device of a DC brushless multi-phase motor performs the speed control of the motor in place microprocessor, the burden on the microprocessor is relieved. The drive control device detects a zero crossing point of the back electromotive force in the non-energizing phase to perform the energizing switching to the coils by the PLL control, and includes a current detection circuit that detects currents flowing through the coils to perform the speed control of the motor based on the detected currents. The drive control device also, compares outputs from speed error detection circuit with outputs from the current detection circuit to determine the currents to be made to flow through the coils, and thereby controls the current output circuit.

Drive control device of motor and disk rotation system

In a magnetic disk storage apparatus, when power supply is stopped, a magnetic head can be retracted safely and quickly so as not to be damaged. There are provided a back electromotive a force detector that detects back electromotive forces developed in coils of a voice coil motor for moving a magnetic head when power a supply is stopped, and a brake controller that judges a movement speed of the magnetic head from the detected back electromotive forces, and brakes the voice coil motor when the movement speed is greater than a preset first limited speed.

Growing community of inventors

Maebashi, Japan

Kenji Yoshida