Image pickup apparatus

摘要

An image pickup apparatus designed to improve the amplitude modulation degree particularly at edge portions of an image comprises an image pickup tube and a yoke assembly. The image pickup tube includes a target, a focusing electrode and an electron beam limiting aperture for limiting the diameter of an electron beam. The yoke assembly comprises means for generating a focusing magnetic field and means for generating a deflection magnetic field. The distance between the electron beam limiting aperture and the target is at least 5.5 times the maximum diameter of the focusing electrode. The half width of the focusing magnetic field intensity distribution along the axis of the image pickup tube is at least 85% of the distance between the electron beam limiting aperture and the target. The focusing magnetic field intensity in the middle portion of the distribution having at least the half value of the focusing magnetic field intensity distribution is smaller than the focusing magnetic field intensity near the target.