Optical tape apparatus with a tracking control mechanism and/or a focusing control mechanism
US4970707A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 1, 1988 |
| Grant date | Nov 13, 1990 |
| Priority date | — |
| Expiry date | Sep 1, 2008 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/0925
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An optical tape apparatus having improved focus and tracking control. An optical head records, reproduces, or rewrites data on an optical tape by helically scanning the tape with a laser beam. A guide plate is disposed between the optical head and the tape to prevent the beam from becoming unfocused due to fluctuation of the tape cuased by an air film between the optical head and the tape. The optical head contains a semiconductor laser and an optical system exhibiting chromatic aberration for directing the laser beam onto the tape. The optical system includes a condenser lens for focusing the beam onto the tape. Fine focus control is achieved by changing the wavelength of the laser beam by directing part of the beam reflected from the tape back to the laser, thereby changing the focal point of the beam by virtue of the chromatic aberration of the optical system. Coarse focus control is achieved by mounting the condenser lens on a piezoelectric actuator which moves the consenser lens to focus the beam onto the tape. A recording head for recording timing marks and tracking signals on the tape is disposed in advance of the optical head. A reading head reads the timing marks and the o…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.