  The common interpretation of the Hawking radiation as quantum tunneling has
some ambiguity such as coordinate-dependence of tunneling rate and
non-invariance of the action under canonical transformations. It is shown that
the tunneling process of black holes can be successfully described by Rindler
coordinates in analogy with the Schwinger mechanism for pair production. We
study the tunneling process of a charged black hole and a BTZ black hole.
