Split rings on a dc generator

[shokstar]

Whats the purpose of a split-ring commutator which is connected to a dc generator? Is it:

'As the coil is moved mechanically, a generated current will be produced, as the coil is turning in a magnetic field. The current produced will be AC, and hence, a split ring is used to invert the output every half turn, similar to their purpose in a motor, however in this case, the split ring is converting AC current into DC current, the opposite to the case in a motor, thereby producing a DC output'

Im not 100% sure if that is correct. Thanks in advance 

[Chavi]

Check here: http://vcenotes.com/forum/index.php/topic,33285.0.html