  The Ginzburg sandwich is a superconducting film coated with a dielectric
layer containing Bose-type exitations, i.e. exitons. Using spatially
inhomogeneous Eliashberg equations in the local interaction limit, an exact
result for the superconducting transition temperature of the Ginzburg sandwich
has been obtained in the first order in a/L (where a is interatomic distance
and L is the film thickness). The result has been found to be independent of
the exiton frequency. The exitonic mechanism appears only in the second order
in a/L since both partners of the Cooper pair should enter a layer of thickness
\sim a in order to interact through exchange of exitons. Numerical estimates
indicate that manifestations of the exitonic mechanism are practically
undetectable in systems with L>>a. Calculations for a narrow-gap and wide-gap
dielectric have been performed and compared to experimental data.
