Track seeking apparatus and method using sampled information
US4855977A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 27, 1987 |
| Grant date | Aug 8, 1989 |
| Priority date | — |
| Expiry date | Jul 27, 2007 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B21/083
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A track seeking method is provided which relies on sampled seek information. No external sensors are employed and the seek information is intermittently stored along the tracks provided on the disk surface. In determining the actual velocity of the seek actuator, at least two methods for counting crossed tracks are utilized. Preferably, a 1/2-count method is used at lower seek velocities and a 16-count method is used at higher seek velocities. The 178 -count method involves the receipt of two counts for each track that is crossed, while the 16-count method involves counting every sixteen tracks that are crossed. The selection of the 1/2-count and the 16-count methods for counting tracks crossed results in a velocity gap region. The velocity gap region is a range of seek actuator velocities in which the servo loop is underdamped for the 16-count method and where folding occurs for the 1/2-count method. To overcome the underdamping and folding problems, various solutions have been devised. In one embodiment, the velocity profile is configured so that the gap region is crossed in a relatively short amount of time and the 16-count method is used in providing velocity feedback.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.