CHARACTERISTICS OF A PHOTOCONDUCTIVE AC-DRIVEN PICKUP TUBE AND ITS APPLICATION TO A SINGLE-PICKUP-TUBE COLOR CAMERA.

A photoconductive pickup tube, with ac potential difference between the target and the cathode, produces a signal current consisting of an ac component as well as a dc component. The amplitude and phase of the ac component are modulated by the incident light level. It is known, however, that as the current density of the scanning beam decreases, the phase of the ac component becomes independent of the light level. In this paper, a single-pickup-tube color camera is proposed as an application of the ac-driven pickup tube. The camera uses a tri-electrode vidicon with a tri-phase color subcarrier to generate the NTSC television signal directly.