What do the three controls on the Transporter operate?

Question

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)?

EDIT

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.

Answer 1

The semi-canon technical reference manual; the "Star Trek : Star Fleet Technical Manual" written and illustrated by Franz Joseph (used as a source and reference for various Star Trek films and episodes of TNG) indicates that the three sliders are for;

- Photon Ionization Control
- Neural Paralyzer Control
- Magnetic Field Control

It also stresses that under normal circumstances, all three sliders are intended to be operated simultaneously.

This isn't always the case, however since we see Scott moving one of the controls independently in the episode TOS : "The Enemy Within". This ties in nicely with the description above as there does indeed appear to be a malfunction relating to a magnetic substance. Presumably Scott needed to wiggle his slider in order to adjust the Magnetic Field Control in some fashion:

SCOTT: Right. Locked onto you. Energise. Coadjutor engagement.

WILSON: What happened?

FISHER: I took a flop.

WILSON: Onto what?

FISHER: I don't know. Some kind of yellow ore.

SCOTT: Magnetic. Decontaminate that uniform.

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As far as transporters from subsequent series are concerned, the TNG Technical Manual describes them simply as "Sequence Initiators" (with no further description of their function) however it does note that out-of-universe, they were included on the console as an homage to the prop from the original series:

The transporter console has three touch-sensitive light bars, which control the transport process. This was intended as an homage to the transporter in the original Star Trek series, which had three sliders that Scotty always used.

Answer 2

In the TNG Technical Manual page 106:

A transporter converts matter into energy and back again using the energizing coil to produce an energy field (the ACB or annular confinement beam), and the transition coil to phase the matter within it into energy.
The transition coil will only convert the matter at 162GHz and so has to be gently ramped up and down. This can be done manually with the sliders, or by the transporter controller computer.

De-Materialization: First, the ACB is energized up to 32MeV, creating the beam to hold the matter or energy. Then the phase transition coil is energized up to 162.9 GHz and held while the matter is converted into energy.
The beam is then transferred to the pattern buffer (a big holding tank underneath the transporter pad) before being sent to the emitter array for transmission to a planet, or elsewhere in the ship.

Materialization: Once the ACB is moved over its target, the materialization process then begins converting the energy back into matter, before the coils are ramped back down. The transport is then complete. Any disruption to this delicate sequence will result in a deadly energy discharge (ST:TMP) or a loss of pattern.

The sliders control the whole sequence rather than one component. The term 'energize' applies to the whole process rather than just the energizer coils.

The 3 touch-sensitive light sliders in TNG are an homage to the ones in TOS that Scotty would use (TNG Technical Manual, page 107, footnote)

Answer 3

I can't cite the episode, but I vaguely remember an episode of TNG where Barclay and O'Brien are discussing the safety of the transporters, and they mention that there is redundancy built into the pattern buffers. Perhaps each of those dials correlates to one pair of pattern buffers, meaning one would work in a bind (and possibly make the teleport faster?), but all three is the safest (and possibly slowest) way, with two being a happy medium.