Thanks, Reinoud. The function of the second stationary magnet positioned
below the moving magnet is to act as a kind of flux booster. It adds flux
density and intensity to the entire magnetic circuit, like a big second
battery adding power to a motor already connected to a first smaller
battery. The combination of the two coils, the moving magnet and this
stationary "power magnet" completely saturates the flux gap, so adding more
magnetism does nothing more. Adding this second magnet gave the tactuator
such a lot more power that it was shocking; like day and night. So, between
the two coils resonating and moving the "moving magnet" and the "power
magnet", the force generated by the actuator is very high. It can generate
more force than the R2 optacon's entire 100-pin bimorph-based display. and
each actuator is in overdrive when using 200mV. The impedance of each
actuator I haven't measured or calculated; their static resistance is
meaningless, but it is about 1.6 to 2 ohms. I think the electromagnetic
oscillating field does not move the moving magnet; it moves the flux, which
in turn moves whatever is in the flux field. Like waves of water in turn
moving a boat afloat upon the watery waves. The boat does not move itself;
the waves of water move the boat.
Charles
-----Original Message-----
From: reinoud
Sent: Monday, May 18, 2015 6:33 PM
To: optacon-l@xxxxxxxxxxxxx
Subject: [optacon-l] Re: Reinoud, how many coils and their relationship to
the permanent magnet?
Evening Charles,
The frame designs I have now actually support both coil configurations. In
my opinion there isn't all that much difference between these coil
configurations. Volumes and efficiencies are practically the same for
reasonable dimensions, and both can be packed at a similar pitch. As for
manufacturing cost, for a two-coil actuator the coil winding is a bit more
complicated, for a one-coil actuator the assembly is a bit more complicated.
The most suitable configuration will depend on frame design and available
manufacturing options.
I use typical optimum coil size ratios, this leads to the most efficient
coils, also at these tiny dimensions (tested it).
To get a one-coil actuator to work, the moving magnet obviously has to be
positioned off-center inside the coil.
Do I understand correctly that your actuator centers the moving magnet by
design, when it's driven? If so, that's very neat, but then what is the use
of the second (stationary) magnet? I had assumed it would function as a
spring.
- Reinoud
On 18/05/15 16:25, C. Pond wrote:
Reinoud:to view the list archives, go to:
Do you use one coil per actuator or two? If you use one coil, then what
is its size compared to the permanent magnet, or have I misunderstood your
design?
I’m using two coils in resonance, but I still have a sensse against
conventional experience and wisdom and education that but one coil need be
used. Still not sure, even though these two coils work fabulously.
I did try with one coil, but the magnet, as expected, stayed right in the
middle of the coil between the two poles. Each pole of the permanent
magnet was being held in place by the pole of the coil, and so the magnet,
rather than moving according to the AC waveform, stayed fixed in the
middle of the solenoid.
Thanks,
Charles
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