PURPOSE: To provide a thin type getter device of which activation becomes possible again according to requirement and which can be arranged in a narrow space in a fluorescent character display tube.
CONSTITUTION: An envelope 5 is composed of an anode board 2, a cathode board 3 and a spacer member 4. A field emission element 8 having a gate electrode 12 and a conical emitter 14 exists on an inside surface of the cathode board 3. An anode electrode 15 exists on an inside surface of the anode board so as to be opposed to the field emission element. A getter device 20 composed of an emitter 21 as an electron supply part having a projecting part, a gate 22 and a getter material 23 being an anode exists in the corner of the cathode board. Voltage is impressed upon the getter material, and an electric field is applied to the emitter, and an electron is emitted. The electron collides in a projectile form with the getter material, and activates this. Activation can be carried out again according to requirement. With this getter, a characteristic that the envelope is formed in a thin type can be utilized efficiently in a fluorescent character display tube using the field emission element as an electron source.
ITO SHIGEO
WATANABE TERUO
