Title:
PHASE SYNCHRONIZING CIRCUIT FOR DISK DEVICE
Document Type and Number:
Japanese Patent JPH0395772
Kind Code:
A
Abstract:
PURPOSE:To output the pulse of a frequency, which is N-fold to that of a synchronizing pulse, without erroneous detection from a voltage controlled oscillator (VCO) by keeping a reference signal at a zero level until the revolution a motor to rotate a servo disk reaches a prescribed revolution. CONSTITUTION:This device is provided with a synchronizing pulse generating circuit 1, phase comparator 2, VCO 5 and switch circuits 7 and 8. Since the switch circuits 7 and 8 keep the reference signal at the zero level until the revolution of the motor to rotate the servo disk reaches the prescribed revolution, phase difference between the reference signal and a synchronizing pulse to be compared in the phase comparator 2 obtains a polarity to lower the transmitting frequency of the VCO 5 for the pulse width of the synchronizing pulse. Thus, phase comparison in the phase comparator 2 is started from the low oscillation frequency of the VCO 5, and without the erroneous detection, the pulse of the N-fold frequency to that of the synchronizing pulse can be outputted form the VCO 5.
Inventors:
ITO KAZUHIKO
Application Number:
JP23205989A
Publication Date:
April 22, 1991
Filing Date:
September 07, 1989
Export Citation:
Assignee:
MITSUBISHI ELECTRIC CORP
International Classes:
G11B20/10; (IPC1-7): G11B20/10
Attorney, Agent or Firm:
Masuo Oiwa (2 outside)