| 摘要 |
A television camera tube comprising, in an evacuated envelope, an electron gun to generate an electron beam which during operation of the tube is focused to form a spot on a photosensitive target. On the target, a potential distribution is formed by projecting an optical image on it. By scanning the target with an electron beam, signals corresponding to the optical image are produced. The target is scanned in a line deflection direction and a frame deflection direction. According to the invention, the spot has an elongate shape, which shape is determined by a line at the edge of the spot which interconnects points having the same current density. The shape of the electron spot is such that the ratio, k, between the lengths of the long and short axes of the spot is 1.4</=k</=2. The long axis of the spot divides the acute angle between the line deflection direction and the frame deflection direction in such manner that 0 DEG </= beta </=60 DEG , where beta is the angle between the long axis and the frame deflection direction. A television camera tube is obtained in which the modulation depth is (a) larger than in comparable tubes having a circular spot, (b) less dependent on the orientation of the usual test pattern for the modulation depth, and (c) substantially symmetrical with rotation of the test pattern from the vertical position. |
