| 摘要 |
PURPOSE:To measure a process value accurately without any flicker of light by specifying the value obtained by dividing the cubic value of the gravitational size of the space part of a diaphragm which is displaced when receiving pressure by the coefficient of kinematic viscosity of charged liquid with regard to a photosensor device which detects the applied process variable in terms of the quantity of light. CONSTITUTION:The pressure 7 is applied to diaphragm in a gravitational direction A. The gravitational side of a recessed part 4 and the coefficient of kinematic viscosity nu of the liquid 10 fill into the space part 6 are so set according to a constituent factor S<3>/nu of a Reileigh number so that no convection current is generated. The liquid 10 uses silicone oil of dimethyl polyisoloxane, etc.; the temperature conductivity K and coefficient B of cubical expansion are close to 0.001, so <=1.24X10<-2> S<3>/nu when calculated from the convection current limit value of 1,700 of the Reileigh number. Consequently, the liquid 10 has no convection current even if the ambient temperature rises and the quantity of light transmitted through an optical transmission line 2 is sent to an optial transmission line 8 as a photodetection signal of the quantity of light corresponding to the amount of displacement corresponding to the value of the pressure through a diaphragm 5. |
