Gas flow controller

TL;DR: In this article, the authors propose a flow decision section 3 comprising a first comparing circuit 15, a current control circuit 16, and a second comparing circuit 17, which outputs a maximum allowable current Imax corresponding to the flow set signal VB.

Abstract: PURPOSE:To provide a gas flow controller in which flow control is effected correctly and a decision of abnormality can be made when the flow control is no effected correctly. CONSTITUTION:A flow decision section 3 comprises a first comparing circuit 15, a current control circuit 16, and a second comparing circuit 17. The first comparing circuit 15 compares a flow detection signal VA based on a detection result with a flow set signal VB and outputs a control current I required for equalization thereof. The current control circuit 16 is connected in parallel with the first comparing circuit 15 and outputs a maximum allowable current Imax corresponding to the flow set signal VB. The second comparing circuit 17 compares the control current I with the maximum allowable current Imax. If ¦I¦ ¦Imax¦, an abnormality is displayed and the supply of control current I to the flow control section 4 is interrupted.