Harry I think that is just a fancy brush system.
Slip rings are quite simple, they are just a continuous band of conductive material, usually copper, that are mounted on, but insulated from, the rotor. There are usually 2 of these bands (or rings) and a conductor is connected to each of the slip rings and they go to whatever is to be powered on the rotor (usually a coil as in a motor or alternator). A brush rides along the band/ring as the rotor spins to conduct the current.
Both slip rings and commutators do the same basic thing but the difference is a commutator ring is made up of insulated segments of copper which switch the polarity of the current every time the brush pass over one segment on to another - thus on an electric motor a DC current is turned into an AC current to feed the rotor winding. In the case of Baird's matrix screen instead of alternating the polarity the same principle was used to switch the video signal to another lamp.
Slip rings are a much more reliable method of conducting current to a rotating device because the brush is always in contact with with the ring and therefore arcing is eliminated (in an ideal implementation).
The problem from an NBTV constructors point of view is that they, generally, have to be constructed from scratch and therefore suffer from the usual problems of "kitchen table engineering".
I think, however, that a slip ring system, for transferring power to a "fire wheel" is quite within the capabilities of most constructors - commutation is another kettle of fish altogether.
You must also learn to temper Steve's comments somewhat by appreciating that he has a horror of all things mechanical - in the near future when we are all being waited on hand and foot by robot servants he will refuse to have one insisting he will wait until the all electronic versions come out
On a final note I would say that power can be transferred to a disk by inductance thus eliminating the mechanical parts. In fact your generator idea is really just a form of that. Have a look at all those POV projects on YouTube - they all solve the same problem one way or another.