14. A line passing through the left focus $F_{1}$ of a hyperbola and perpendicular to the real axis of the hyperbola intersects the hyperbola at points $A$ and $B$. If there exists a point $C$ on the line of the imaginary axis of the hyperbola such that $\angle A C B=90^{\circ}$, then the range of the eccentricity $e$ of the hyperbola is . $\qquad$