Regarding the finger plate issue, my only concern would be whether someone with
a smaller finger would be missing some of the displayed text. Would it be
possible to adjust well enough for that so as to prevent the problem? I also
found the current size and shape of the plate to be entirely satisfactory.
Rejoice in Jesus always!--Ninette
On May 1, 2015, at 6:49 PM, C. Pond <cpond@xxxxxxxxx> wrote:to view the list archives, go to:
Thank you both for commenting on the finger plate shape. This is what I
need.—Feedback.
At this point I’m 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 optacon’s display’s 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 ra
tes.
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 won’t
work, nor does the stuff prove satisfactory of which circuit boards are made.
By next week I’ll have the proper material pinned down. Likely I’ll 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
won’t 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) won’t cover it.
Charles
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