公开(公告)号：JPH0460960A

公开(公告)日：1992-02-26

申请号：JP16811590

申请日：1990-06-26

Applicant: SONY CORP

Inventor： NISHIDA NORIO ,  YAMASHITA YOSHIHIDE

IPC: G11B19/28

Abstract: PURPOSE:To enable servo control with high accuracy by controlling the speed of a spindle motor based on error between a count value sampling the output of a counter and a prescribed reference value according to either the rotation detecting output of the spindle motor or the regenerative output of sector pulses recorded on a disk at prescribed intervals. CONSTITUTION:A counter 9 counts a clock signal as a continuous value and in a stage when the rotation of a spindle motor 7 starts, the output of the counter 9 is sampled by the rotation detecting output of the spindle motor 7. In the state of sufficiently starting the rotation of the spindle motor 7 and making it stable, the output of the counter 9 is sampled according to the regenerative output of sector pulses recorded on a disk 1 at prescribed intervals. Next, difference between the outputs of the counter 9 at the timings of two adjacent samplings is calculated and based on error formed by comparing the difference of this count value with a reference count value, the rotating speed of the spindle motor 7 is controlled. Thus, servo control is enabled with high accuracy.

公开(公告)号：JPH0192969A

公开(公告)日：1989-04-12

申请号：JP24937187

申请日：1987-10-02

Applicant: SONY CORP

Inventor： TAKAHASHI TADASHI ,  YANAGIMOTO KAORU ,  YAMASHITA YOSHIHIDE ,  TAGUCHI KEIICHI ,  KOBAYASHI YUKIO

IPC: G11B21/10 ,  G11B19/06 ,  G11B19/12

Abstract: PURPOSE:To simplify a circuit constitution for disk discrimination by selecting one frequency of a servo signal so as to be equal to a recording line density on a magnetic disk respectively in 1st and 2nd modes so as to decrease the number of band pass filters. CONSTITUTION:A signal from a reproducing amplifier 2 is fed to band pass filters 91-93 having three kinds of frequencies in a period of servo ID and servo data signal at recording and reproduction and signals from the filters 91-93 are fed to a circuit 10 detecting ID signal and the detected ID signal is fed to a CPU 11 for driving control. In obtaining a signal from a filter of a frequency 125kHz among the band pass filters 91-93, it is discriminated that the disk is a disk of a 1st or 2nd mode. Through the constitution above, the signal recorded in a line density equal to each other on a disk is reproduced by an equal frequency. Thus, the detection is implemented by using a single band pass filter so as to decrease the number of the band pass filters, thereby simplifying the circuit constitution for disk discrimination.