Patent ID: 10606288

Abstract:
A gas pressure within a treatment chamber 2 can be more accurately regulated to a predicted target pressure whereby there can be provided a pressure control apparatus which can easily and speedily regulate the gas pressure for various combination of the treatment chamber 2, a sanction chamber 3 and a valve 4. A required inflow rate (Qi) at which it is necessary for gas to flow into the treatment chamber 2 in order to reach a preset target pressure (Psp) within the treatment chamber is calculated on the basis of the expression of Qi=Qo+(P/□t)V and the thus calculated required inflow rate (Qi) is flown into the treatment chamber 2 to control the pressure within the treatment chamber 2 to the required pressure (Psp). In calculation of a current predicted outflow rate (Qo(n)) at which gas is discharged from the treatment chamber on the basis of the expression Qo(n)=P2*f1(P2), using a current pressure (P2) within the suction pump and a known characteristic suction rate (Sp=f1(P2)) of the suction pump under prescribed pressure, the current pressure (P2) within the suction pump is calculated according to the expression P2=P1−(Qo(n−1)/f2(θ, P)) from an accurate conductance (Cv(θ, P)=f2(θ, P)) calculated by adding the error between the current pressure (P1) actually measured within the treatment chamber and a known specified pressure (P) within the treatment chamber at the characteristic conductance (Cv=f2(θ)) of the valve at the opening/closing angle (θ) associated with the current position of the switching plate of the valve to the known characteristic conductance (Cv=f2(θ)) of the valve at the opening/closing angle (θ) associated with the current position of the switching plate of the valve, and the current predicted outflow rate Qo(n) at which gas is discharged from the treatment chamber is calculated.