| 摘要 |
In a VTR for recording and/or reproducing video signals in parallel tracks extending obliquely on a magnetic tape which is wrapped helically on a guide drum, rotary magnetic heads are associated with the guide drum to move in respective circular paths which coincide with the guide drum surface and which are axially spaced apart on the latter so that the heads obliquely traverse respective longitudinal zones substantially equally dividing the width of the magnetic tape. The angular spacing between the heads and the angular extent of the guide drum surface about which the tape is wrapped are selected so that, when the heads are rotated for obliquely traversing the respective tape zones in a repeating cyclic order, the latter has at least one overlapping interval in which two of the heads simultaneously scan oblique tracks in the respective zones. In the reproducing mode of the VTR, signals reproduced by the heads from tracks in the respective zones and being scanned in the repeating cyclic order are sequentially combined and, during each overlapping interval, a comparator senses phase differences between signals reproduced by the two heads which are then simultaneously traversing the respective zones and provides a corresponding compared output. A head shift signal is generated in response to such compared output and is employed, for example, by application to a bimorph leaf mounting at least one of the heads, for displacing such head in a direction along the respective tracks scanned thereby so as to eliminate the phase differences.
|
