Thank you both for commenting on the finger plate shape. This is what I
need.âFeedback.
At this point Iâm looking for a material which is hopefully better than what
we now have so that mechanical vibrations between such densely packed
tactuators as these will be minimized through a well-designed finger plate.
Even though we cannot actually feel it, there is some mechanical cross-talk or
influence between our present optacon pins. You can detect this either by
empirical measuring, or yu can see it under a microscope and a strobe light in
sync with the optaconâs displayâs refresh rate of about 230-plusHz or so.
Also, the good old optacon display, although excellent for our decades-old use
does have inefficiencies in it which do take the edge of of its display
quality. There is some lateral (side to side) movement of each pin although
they do move up and down quite well as they should do, and because fine tuning
the display of the present decades-old optacons is a bit of a compromise, each
pin does not resonate at its ideal rate, let alone at the same rates.
If the tactile pins being used here for tests are between 0.005-inch and
0.007-inch diameter, and the vertically aligned holes in the finger plate are
about 0.01 to 0.015-inch diameter (and these are merely test parameters), this
means that a dense polymere or something must be used. Delrim wonât work,
nor does the stuff prove satisfactory of which circuit boards are made. By
next week Iâll have the proper material pinned down. Likely Iâll go with
the 0.005-inch diameter pins, and the holes for them in the finger plate will
be 0.008-inch in diameter.
On another note which came up last week: the power supply is most certainly not
a simple matter of dampening resonance by placing a very large capacitor beside
a very small one, bypassing near the actuators, and putting a small resistor in
series with a capacitor. These common measures are just the beginning. The
power supply for a well-designed optacon which has several hundred tactuators
and a lot going on inside it is a project in and of itself to be sure. If
anyone on the list is duplicating my work or doing something simular, then
simply take look at the power supply lines on an analyzer, or even listen to
them on a signal tracer. Conventional dampening measures wonât work. For
just one of several reasons: each tactuator can be considered almost like a
motor, so when they activate, an in-rush current happens, like it does with a
washing machine starting up. Also, the common mode rejection ratio of the
driver chips (cmrr) wonât cover it.
Charles
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