| 摘要 |
PURPOSE:To simplify the circuit constitution of a tracking controller by producing a drive pattern signal of a triangular wave whose average level is set at zero with the waveheight value corresponding to the reproduction speed by a drive pattern generating means and also changing the tape driving position in response to the reproduction speed by a tape position changing means. CONSTITUTION:The speed indicating signal given from a reproduction speed indicating part 19 is supplied to a triangular wave oscillator circuit 22 and a bias application circuit 23 which constitute a drive pattern generating circuit 21. The circuit 22 produces no triangular wave in a normal reproduction mode and delivers a signal of a earth level at all times to perform switching to fixed video heads 34 and 35. In a double speed reproduction mode a triangular wave which is set at OV and voltage -TT in the rise and fall modes of a head changeover pulse as shown by a solid line of the figure (B) is produced synchronously with the band changeover pulse shown in the figure (A) together with another triangular wave having a 180 deg. phase delay compared with the first triangular wave. |
