| 摘要 |
1329787 Videotapes; recording and playback SONY CORP 24 June 1971 [26 June 1970] 29681/71 Heading G5R In a videotape recording/playback system usable for editing, an unwanted section of a recording is erased by a portion of the actual signals that are to be recorded in its place. In the embodiment shown, video signals which are desired to be added to a tape (6, Fig. 1, not shown) are fed from a modulator 8, Fig. 3, to two rotary recording heads 3a, 3b, and the high frequency portion of these signals, as selected by a high pass filter 19, is simultaneously fed as erase current to two similarly rotating erase heads 4a, 4b. Heads 4a, 4b are arranged to scan the same tracks as heads 3a, 3b, and in advance, as in Fig. 2, but their gaps are set obliquely to the normal recording field direction. Thus by suitably amplifying the erase currents at 14, Fig. 3, the erase fields can be made to saturate the recording medium in the oblique direction, i.e. to wipe out the previous recording, and by carefully choosing the values of the track width, the erase field offset angle, the frequencies, &c., it is possible to make the erase signal produced in normal replay of the edited tape very small. |
