Track deviation detecting apparatus
US4498159A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 10, 1983 |
| Grant date | Feb 5, 1985 |
| Priority date | — |
| Expiry date | Feb 10, 2003 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/0903
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A track deviation detecting apparatus for detecting a deviation of a recording light spot (A) from a track (15) on a recording medium (7) comprises two diffraction gratings (2, 18) for producing two auxiliary spots (B1, C1) being led along light paths (30b1, 30c1), optical means comprising a light source (1), a collimator lens (17) and a condenser (6), and two optical detectors (20, 21) adapted to detect the respective reflected light rays from the auxiliary spots (B1, C1) on the recording medium (7). A positional relationship of two diffraction gratings (2, 18) and the optical means is arranged so that one of two auxiliary spots (B1, C1) is located on an unrecorded portion of the track (15) and at a lower edge (13) of the track (15), and the other is located on the unrecorded portion of the track (15) and at an upper edge of the track (15). The reflected light rays from two auxiliary spots (B1, C1) are led to the optical detectors (20, 21) installed correspondingly thereto, without being influenced by the record pits (16) formed by the spot of light (A). Thus, outputs from the optical detectors (20, 21) are differentially amplified by a differential amplifier (14) connected theret…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.