What is the type of hinge used in fold-down car tv's?

These are not usually simple hinges - they are often designed with cams etc to give a specific movement - so are usually specific to the item.

Think of kitchen cupboard hinges - the simple ones are easy to replace, but some have extending movements so doors can move out to clear other doors...

You may find a hinge that does the movement you require and then you will need to re-manufacture it to cope with the load you will be applying...