  We write the fermionic $q$-Fock space representation of $U_q(\hat{sl_n})$ as
an infinite extended braided tensor product of finite-dimensional fermionic
$U_q(sl_n)$-quantum planes or exterior algebras. Using braided geometrical
techniques developed for such quantum exterior algebras, we provide a new
approach to the Kashiwara-Miwa-Stern action of the Heisenberg algebra on the
$q$-fermionic Fock space, obtaining the action in detail for the lowest
nontrivial case $[b_{2},b_{-2}]=2({1-q^{-4n}\over 1-q^{-4}})$. Our R-matrix
approach includes other Hecke R-matrices as well.
