Kees,
A transflector is a transmissive reflector that is mounted on the back
of an LCD and it can work in two modes.

In the reflective mode light that passes through the front of the LCD
is reflected back out, allowing you to read the display. In the
transmissive mode it allows light from a back light, mounted behind the
LCD, to pass through it and out the LCD, so you can read the display.
If the transflector did not allow light to pass through it from the
back side you would not be able to use a back light, as the light would
never be able to pass through it and out the LCD. Every PDA uses a
transflector like this, and most have a back light that can be turned
on in low light applications.

A touch screen is mounted on the front of the display. It's only
function is for the inputting of data. It must be optically clear so as
to not distort, or dim, the image passing through it from behind.

John