Magnetic recording and reproducing system with tape-to-head speed control
US4003090A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 29, 1975 |
| Grant date | Jan 11, 1977 |
| Priority date | — |
| Expiry date | Jan 29, 1995 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B15/615
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Apparatus is provided for controlling the phase and speed of a motor for driving the rotary magnetic heads of a video tape recorder. An output of a signal generator, for example, a sawtooth wave, having a frequency corresponding to the rotational speed of the motor is compared with an external reference signal, for example, a 60 Hertz power line signal. A difference in frequency generates a varying error voltage whose polarity is indicative of the error direction. Relatively large or prolonged frequency errors result in an error voltage waveform having an abrupt and relatively large change. This error voltage is differentiated to create relatively large pulses of polarity depending on the direction of the error voltage. The relatively large pulses either charge or discharge a capacitor, the output of which changes the current to the motor so as to reduce the relatively large frequency error to a range suitable for handling by a conventional combined position and velocity servo system.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.