System for correcting time base error of information reproducing apparatus
US4745494A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Jun 11, 1986 |
| Grant date | May 17, 1988 |
| Priority date | — |
| Expiry date | Jun 11, 2006 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B19/28
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A light emitted from a laser diode is reflected by a video disc which is rotated by a spindle motor. The reflected light is modulated by video information recorded on the video disc and converted to an electrical signal by a photodiode array. A signal generated by a trapezoidal generator is sampled with a horizontal synchronizing signal separated from the video information signal. The sampled signal is supplied to the spindle motor for correcting a time base error. A zero crossing point of the trapezoidal waveform is detected and is utilized for controlling the start of a rise portion of the trapezoidal waveform for compensating a DC offset. The trapezoidal waveform is controlled so as to vary an average power supplied to the spindle motor in accordance with a detected rotational speed difference so as to compensate a rotational speed of the spindle motor.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.