Finnegan, Henderson, Farabow, Garrett & Dunner
Read/write amplifier power control device for a disk apparatus
 A power control device for a disk apparatus has first and second flip-flops respectively constituted by monostable multivibrators for latching STEP and MOTORON signals supplied from a floppy disk controller during execution of a seek instruction of a main processor. An output from the second flip-flop is disabled before the STEP signal is supplied thereto. A period of time T2 for which a final STEP signal is supplied to the second flip-flop and then the output from the first flip-flop is disabled is longer than a pulse width of the STEP signal. Q outputs from the first and second flip-flops are supplied to first and second transistors through a NOR gate. Collector outputs of the first and second transistors are supplied to the bases of third and fourth transistor whose emitters respectively receive voltages of +12 V and +5 V. An output from the NOR gate is kept low for a predetermined period of time until the rush current is eliminated after the spindle motor is started, and for a predetermined period of time after the step pulse is supplied to drive the stepping motor. The first and second transistors are kept off and then the third and fourth transistors are also kept off. Power supply voltages of +12 V and +5 V are not supplied to a read/write amp. 
Kabushiki Kaisha Toshiba
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Koji Masaki
Osafune Sano