| 摘要 |
The invention relates to a method and apparatus for detecting the piercing of a cathode ray tube. The apparatus comprises a supply source 7 with a constant voltage, which is less than the standard voltage, a filament 2 of the cathode 1, a circuit 8 for measuring the intensity of the heating current, a threshold circuit 10 and a display device 11. The lamp of the display device 11 is illuminated when the intensity of the current, after having been decreased, rises back above a predetermined threshold, and indicates that the tube has been pierced. The invention is applicable to colour television tubes. <IMAGE>
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