PURPOSE: To improve a breakdown voltage characteristic by increasing applied voltage to perform processing without giving damage to a built-in part, by periodically applying AC voltage of high/low voltage levels against a cathode- ray tube which must be processed.
CONSTITUTION: A pulse of about 1ms half value width as shown by A is output by a period of 16 to 20ms from a knocking voltage generating circuit. By switching this pulse in a voltage regulator comprising a variable resistor and a switching terminal, voltage of the pulse changes into two steps as shown by B. For instance, negative low voltage about V1=-60kV and negative low voltage about V2=-75 to 80kV are applied by setting respectively a period as t1=2sec, t2=3sec, to perform a knocking process. Thus by preventing damage from being given to an electrode, built-in resistor, etc., in an electron gun of a cathode-ray tube, leak start voltage between the electrodes can be decreased by a degree of about 5kV, to enable a discharge rate to 1/2 improve.
KAMIYA KENICHI
HAYASHI KAZUHARU
TESHIGAWARA SHIGERU
| JPH05151897A | 1993-06-18 |
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