  We report sub-arcsecond imaging of extended mid-infrared emission from a
proto-planetary nebula (PPN), \iras 22272+5435, performed at the MMT
observatory with its newly upgraded 6.5 m aperture telescope and at the Keck
observatory. The mid-infrared emission structure is resolved into two emission
peaks separated by $0\arcsec.5 - 0\arcsec.6$ in the MMT 11.7 $\um$ image and in
the Keck 7.9, 9.7, and 12.5 $\um$ images, corroborating the predictions based
on previous multi-wavelength morphological studies and radiative transfer
calculations. The resolved images show that the PPN dust shell has a toroidal
structure with the $0\arcsec.5$ inner radius. In addition, an unresolved mid-IR
excess appears at the nebula center. Radiative transfer model calculations
suggest that the highly equatorially-enhanced ($\rho_{\rm eq}/\rho_{\rm pole} =
9$) structure of the PPN shell was generated by an axisymmetric superwind with
${\dot M}_{\rm sw} = 4 \times 10^{-6} M_{\odot}$ yr$^{-1}$, which was preceded
by a spherical asymptotic giant branch (AGB) wind with ${\dot M}_{\rm AGB} = 8
\times 10^{-7} M_{\odot}$ yr$^{-1}$. These model calculations also indicate
that the superwind shell contains larger dust grains than the AGB wind shell.
The unresolved mid-infrared excess may have been produced by a post-AGB mass
loss at a rate of $2 - 6 \times 10^{-7} M_{\odot}$ yr$^{-1}$. While the central
star left the AGB about 380 years ago after the termination of the superwind,
the star seems to have been experiencing an ambient post-AGB mass loss with a
sudden, increased mass ejection about 10 years ago.
