Vacuum tube

A vacuum tube comprising:

• a filament;
• two pairs of a grid and an anode;
• a getter ring for keeping a degree of vacuum in the vacuum tube;
• and
• a getter shield for masking the getter ring against the filament, the grids and the anodes;
• wherein
• the filament is tensioned linearly and emits thermoelectrons;
• both of the anodes are formed on a same face of a planar substrate;
• the filament is arranged parallel to the planar substrate at a position facing both of the anodes;
• each of the grids is arranged, such that the grid faces the anode of a same pair at a first predetermined distance from the anode and has a second predetermined distance from the filament, between the anode and the filament;
• the vacuum tube further comprises an intermediate filament fixing part fixing the filament at a position corresponding to an intermediate point between the anodes of the two pairs;
• and
• the getter ring is arranged at equal distances from each of the grids.

A vacuum tube comprising a filament and two pairs of a grid and an anode, wherein

• the filament is tensioned linearly and emits thermoelectrons;
• both of the anodes are formed on a same face of a planar substrate;
• the filament is arranged parallel to the planar substrate at a position facing both of the anodes;
• each of the grids is arranged, such that the grid faces the anode of a same pair at a first predetermined distance from the anode and has a second predetermined distance from the filament, between the anode and the filament;
• the vacuum tube further comprises an intermediate filament fixing part fixing the filament at a position corresponding to an intermediate point between the anodes of the two pairs;
• and
• a center of each of the grids faces a position corresponding to ¼ of the filament from one end of the filament, and the intermediate filament fixing part is at a position that divides the filament into two halves.