| 摘要 |
PURPOSE: A cathode for a CRT(Cathode Ray Tube) is provided to minimize loss of thermal electron and to realize high current density of cathode. CONSTITUTION: A vapor metal(3) is formed at upper end of a cathode sleeve(2) containing a heater(1). A thermal electron emitting material layer(4) is formed at upper end of the vapor metal. A potential barrier material(9) is coated on surface except effective area of the thermal electron emitting material layer. Herein, work function of the potential barrier is larger than work function of the thermal electron emitting material. Thus, the thermal electron flows along interface between the emitting material layer and the barrier material to prevent loss of thermal electron.
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