Tracking apparatus for read/write head
US4405956A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 22, 1981 |
| Grant date | Sep 20, 1983 |
| Priority date | — |
| Expiry date | Apr 22, 2001 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B21/106
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A tracking apparatus for the read/write head of a recording disk. Positive and negative servo marks on the disk provide sine and cosine head position signals. A calculator generates sine and cosine signal approximations from the high frequency signal outputs of variable and fixed frequency oscillators. A comparator compares the sine and cosine head position signals with the sine and cosine signal approximations and generates a corrective signal where a difference exists. The corrective signal is used to set the frequency of the variable frequency oscillator until the corrective signal is brought to zero. The signal outputs of variable and fixed frequency oscillators are fed to the up and down inputs of a head actual position counter. A second comparator compares the count on the counter with the count on a head desired position register to provide a servo error signal for operating a servo motor which moves the head to the desired track. A feedback loop supplements the corrective signal with a signal derived from actuation of the servo motor to enhance response.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.