| 摘要 |
PURPOSE:To eliminate the need for any compensation circuit or the like and achieve cost reducion by disposing a means of responding to pressure fluctuations and a means of changing oscillation frequency according to its movement and making the total elongation or contraction quantity of members of both means approximately equal to that of a base. CONSTITUTION:Mountng parts 2, 3 are provided at both ends of a part mounting base 1 and one end of an extensible bellows 4 is secured to the mounting part 2 in such a manner as to elongate in response to pressure P. A core 5 is secured to its light end part and a bobbin 6 of cylindrical form is so disposed to the mounting part 3 that the core 5 moving along the elongation or contraction of the bellows becomes removable. A frequency changing coil 7 which changes the oscillation frequency of an oscillator 8 is wound to the outside of the bobbin 6. For example, the base 1 is constituted by aluminum, the bellows 4 by bronze, the core 5 by ferrite and the bobbin 6 by phenolic resin. The total elongation or contraction quantity of these bellows 4, core 5 and bobbin 6 is so set as to becomes equal to that of the base 1. Thereby, the need for temperature compensating drift compensating circuits, etc. is eliminated and considerable cost reduction may be achieved. |
