  The Higgs triplet model (HTM) predicts the existence of a pair of doubly
charged Higgs bosons $H^{\pm \pm}$. Single production of $H^{\pm \pm}$ via e
collision at the next generation e+e- International Linear Collider (ILC) and
the Large Hadron electron Collider (LHeC) is considered. The numerical results
show that the production cross sections are very sensitive to the neutrino
oscillation parameters. Their values for the inverted hierarchy mass spectrum
are larger than those for the normal hierarchy mass spectrum at these two kinds
of collider experiments. With reasonable values of the relevant free
parameters, the possible signals of the doubly charged Higgs bosons predicted
by the HTM might be detected in future ILC experiments.
