| 摘要 |
PURPOSE:To prevent a decrease of emissive capability as an electron tube, by automatically removing on a conveyer a foreign material of lint or the like staying between the first and the second grids, so as to prevent any possible damage of a cathode due to the next emission aging with such a foreign matter. CONSTITUTION:A cathode 27 and the second grid 29 in a color picture tube 21 are connected to each other, and voltage is applied through a resistor 35 and an ammeter 36 from one end of an about 500VDC power supply 34, then a foreign material of lint or the like staying between the first grid 28 and the second grid 29 is removed. Here the resistor 35 is arranged to limit an electric current flowing in the ammeter 36 to a value not more than 100mA when the first grid 28 and the second grid 29 are short circuited to each other. After the foreign material of lint or the like staying between the first grid 28 and the second grid 29 is removed from such a circuit, about 9V is applied from a DC power supply 31 to a heater 26, while about 10V is applied from a DC power supply 32 to the grid 28, and both the second grid 29 and the third grid 30 are connected to this circuit, then emission aging is performed by applying about 300V from a DC power supply 33. In such way, since the emission aging can be performed under a condition without any foreign material between the first grid 28 and the second grid 29, damage of a cathode is never caused, and an electron tube of good quality level can be obtained. |
