Method and circuit arrangement for electrically setting the height of the head wheel of video recording and replay devices

摘要

This method and circuit arrangement reduces the work required for setting the height of the head wheel, that is to say avoids time-intensive mechanical setting processes. According to Figure 1, this is achieved by the fact that the remaining mechanical wrap of the magnetic tape (2) around the head wheel (1) is increased, the mechanical wrap is selected to be greater than the electrical wrap (video heads switched on) for reliable tape/head contact. The video heads for recording and replaying are appropriately switched and the phase difference between the frame pulse during recording and the crystal reference during replaying (reference value) and head wheel tachogenerator pulses (controlled variable) is set for adjusting the centre of the recording height (5) of the video tracks. Due to the fact that there is no mechanical adjustment of the head wheel height, the invention results in an increase of operational reliability of the video recorder and a reduction in manufacturing costs, the appropriate video standard being accurately maintained. The measuring and adjusting process can be automated, in particular, by using a microcomputer. <IMAGE>