1. Field of the Invention
The present invention relates generally to an image pick-up tube and particularly to an image pick-up tube which can easily be manufactured and of which the characteristic such as aberration or the like can be improved.
2. Description of the Prior Art
FIGS. 1 and 2 respectively show examples of the prior art image pick-up tube. In FIGS. 1 and 2, reference numeral 1 designate an electron gun and 2 a glass envelope. In FIG. 1, reference characters G3, G4 and G5 respectively designate grid electrodes from which leads 3, 4 and 5 are respectively led out to apply predetermined voltages to the grid electrodes G3, G4 and G5. In FIG. 2, reference characters G3 and G4 respectively designate grid electrodes from which leads 6 and 7 are respectively led out to apply predetermined voltages thereto. In the image pick-up tube shown in FIG. 2, the electrode G4 is formed by, for example, depositing metal on the inner surface of the glass envelope 2.
Since the image pick-up tubes having the configuration shown in FIGS. 1 and 2 each employ the cylindrical electrodes, such prior art image pick-up tubes require a mechanical construction (not shown) to support the cylindrical electrodes and leads must be connected (welded) to the electrodes thereof, thus the manufacturing of the image pick-up tube being made difficult. In such prior art image pick-up tubes, electrostatic lenses are formed between the electrodes. In this case, since the image pick-up tubes having the configuration shown in FIGS. 1 and 2 employ the cylindrical electrodes apart from the inner surface of the envelope 2, the aperture of the electrostatic lens thus formed is smaller than the inner diameter of the glass envelope 2 so that distortion becomes serious and thus the characteristics such as aberration or the like are deteriorated.