When the differential rotation number ΔN is being converged to 0 (at the time of dΔN≤0), time constant τ (∝T) is determined based on a monotoneincreasingfunction f1 (m) in accordance with this degree of need. 差動回転数ΔNが0に収束しつつある場合(dΔN≦0の時)には、この必要度に応じて時定数τ(∝T)を単調増加関数f1(m)にて決定する。 - 特許庁