Flow rate signal correction method and flow rate control device employing same

A flow rate signal correction method applicable to a pressure-type flow rate control device including a restriction part, a pressure sensor disposed upstream of the restriction part, and a control valve disposed upstream of the pressure sensor, and being configured to control a flow rate by controlling pressure existing upstream of the restriction part, wherein the control valve is controlled by a same feedback control based on a flow rate setting signal and an output of the pressure sensor both in a stable flow rate period and a transient change period, while a flow rate output signal externally displayed is generated in a different way between the stable flow rate period and the transient change period, the method comprising steps of:

• generating a primary signal of a digital flow rate output signal indicating a flow rate, in accordance with the output of the pressure sensor while the control valve is feedback controlled based on the flow setting signal, the primary signal including quantization error;
• and
• generating a secondary signal as a corrected signal of the primary signal such that a current value of the primary signal and a value including information regarding one or a plurality of past values of the primary signal are used to derive a current value corrected according to a predetermined relational expression, the secondary signal including less quantization error than the primary signal,
• wherein the secondary signal is output as the flow rate output signal during the stable flow rate period, and the flow rate setting signal generated in accordance with a predetermined ramp function having a target value to be reached over time is output as the flow rate output signal during the transient change period.