| 摘要 |
<p>1446938 Automatic control of speed SONY CORP 8 Nov 1973 [11 Nov 1972] 51887/73 Heading G3R A video tape recorder is provided with an adjustable delay circuit in the circuit used to control the head wheel speed on playback whereby the trailing of the heads can be adjusted so that tapes recorded on other machines can be replayed satisfactorily. The arrangement shown provides a normal recording circuit where the speed of the headwheel 2 is controlled by brake 9 in accordance with a comparison in comparator 21 of the actual speed detected by pick-off 13c and the desired speed signal which is the vertical sync. signal derived from the incoming video signal at point 16. The sync. signal also is applied to recording head 14 to record a control signal on the tape. For playback the switches 15c, 15d, 15e are switched to the P position so that comparator 21 now compares the head speed signal from pick-off 13c with the replayed control signal from head 14 and produces the brake control signal. If however the reproduced picture quality is poor indicating that heads 2 are not accurately aligned with the record track a switch 22 can be charged over to provide an actual head speed input to comparator 21 from pick-off 13b through monostable multivibrator 23 whose dwell time can be manually adjusted so that the actual speed signal is delayed by an adjustable amount to effectively charge the head speed until the individual heads scan the recorded track on the tape.</p> |
