I recently noticed that in TNG, there are the three 'buttons' which need to be pulled all the way up/down to transport something/someone, just like in TOS. My question is, what do these three things control? Like, wouldn't one lever do just as well if it controls transporting, or do these three 'buttons' control three different things (and if so, why are they all pulled up and down equally and not independently)?
Because of the lack of answers, let me expand the question: Is there any instance where someone has used the Transporter (TOS onwards) with the three sliding-buttons and has NOT used all of them (ie they pushed on two or one rather than three, or didn't use all of them simultaneously)? And if so, why was this done (what was the Transporter operator trying to do at that time (I imagine it would be an abnormal transport))? One instance of a strange transportation was 'The Enemy Within' (TOS) where the transporter duplicated Kirk and the unicorn-dog splitting their personalities, but I don't think Scotty did anything special with the transporter sliding buttons at that point.