A Study of Jitter Caused by Head Impact on VCRs

In a VCR system, a magnetic tape vibrates owing to the head impact action when the magnetic heads collide with and depart from the magnetic tape. These vibrations cause jitter in the reproduced image. It is, however, difficult to evaluate and analyze the head impact action, because the magnetic heads rush into and out of the magnetic tape simultaneously. By measuring the longitudinal vibration of the magnetic tape caused by a single head and synthesizing the vibration waveforms, the methodology has been developed to analyze the head impact action and to estimate jitter. Using this technique, not only the head impact action can be evaluated, but also jitter can be predicted easily and accurately whatever the number of the heads the VCR has.