Brian.
I would say you are thinking of some kind of cavity toggle fixing that you drill a hole and the toggle goes in and expands if the space behind is clear.
Some of my clients use "LARGE" heavy plasma TV's in public so have to meet H&S and Insurance requirements.
In some places and on some mounting points they can not drill in so can not be bolted on.
Brackets are mounted using Automotive adhesives like
Sikaflex 221 and "BODYLINE" double sided automotive sticky tape for mountimg mirrors etc.
These adhesives are not like Your B&Q and Homebase types.
They will hold great weight, even 20 stone body weight from quite small single brackets.
If the surface you wish to mount to is sound, you could bond mounting plates.
It is possible to remove the plates later but with a lot of care and effort and elbow grease after using wires as cutters
and then solvents to loosen the adhesives.
If it is an option make sure surface is clean and any drying or curing times are met. That done, and you will be safe with your screen.