| 摘要 |
PURPOSE:To prevent the deterioration in qualities of sound and inserted picture due to long time recording by recording a carrier of a sound signal by means of rotary heads having different azimuth angles and using the said sound rotary heads as erasing heads at insertion. CONSTITUTION:The sound signal is subject to modulation of a 1.3MHz carrier and applied to audio heads 5a, 5b. Since the azimuth angle of the heads 5a, 5b is tilted oppositely by serveral tens degrees respectively, the signal is recorded on tracks 6a, 6b as shown in the figure. The reproduced carrier from the heads 5a, 5b is selected by a switch circuit, demodulated and outputted. In this case, since the azimuth angle between the heads 5a, 5b and the video heads 2a, 2b is different largely, the mutual effect due to the difference of the carrier frequency is small. In case of insertion, an output of a modulator 9 is changed into about 3MHz by the switch circuit, the output level is nearly 1.5 times and applied to the heads 5a, 5b. Thus, the signal of nearly 3MHz is recorded at a saturation level to the tracks 6a, 6b and the sound carrier and the video signal are erased. Then, the signal is inserted to the tracks 4a, 4b. |
