  Based on the recently introduced averaging procedure in phase space, a new
type of entropy is defined on the von Neumann lattice. This quantity can be
interpreted as a measure of uncertainty associated with simultaneous
measurement of the position and momentum observables in the discrete subset of
the phase space. Evaluating for a class of the coherent states, it is shown
that this entropy takes a stationary value for the ground state, modulo a unit
cell of the lattice in such a class. This value for the ground state depends on
the ratio of the position lattice spacing and the momentum lattice spacing. It
is found that its minimum is realized for the perfect square lattice, i.e.,
absence of squeezing. Numerical evaluation of this minimum gives 1.386....
