| 摘要 |
PURPOSE:To execute stably an automatic beam optimizing (ABO) operation by a simple driving circuit, by applying a signal voltage for controlling a current quantity to not only the first lattice but also the second lattice. CONSTITUTION:An image pickup tube 100 is provided with a cathode 1, the first lattice 2, the second lattice and a photoconductive target 5. A signal obtained from a pre-amplifier PA and a signal generated by a cathode resistance 10 are inputted to a differential amplifier 6 and driving circuits 7, 8 convert the output of the differential amplifier 6 to a driving signal voltage, respectively, superpose it on DC voltage sources 20, 30 and apply it to the first lattice 2 and the second lattice 3. when the applied voltage of the second lattice rises, an acceleration electric field becomes strong and a beam current increases and the beam current dynamic range of the image pickup tube can be expanded.
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