| 摘要 |
The blocking voltage of an electron gun is corrected by periodically removing an input video signal and driving a cathode with a DC stabilizing voltage. A pulse perturbation is impressed upon a control grid and the cathode momentarily conducts more heavily to exceed a predetermined threshold corresponding to the limit of a black CRT picture. A feedback loop detects a response signal from the perturbation of cathode current and stores the response signal in a memory, the latter determining the corrected blocking voltage during normal operation of the gun.
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