Tech alert! Apologies if the following may be too techy for most listers.
Wannes,
A point of clarification. The monomorph reeds for the original
Optacon were not already available off the shelf for phonograph
cartridges in the early 1970s. Clevite made the reeds custom for
Telesensory Systems, because they had to be long enough to have a
resonant peak at 250 hertz, to match the 250 hertz peak response of
the particular tactile sensors of the human finger tip.
The typical off-the-shelf ceramic phonograph cartridges of the early
1970's were using monomorph piezo reeds, but they were much shorter
than the 1.5 inch Optacon reeds.
In contrast to the Optacon's monomorph reeds, the piezo reeds
Telesensory Systems used in their braille displays are called
bimorphs, because they use two layers of piezo material. The reeds
used for braille displays have to be wider, more powerful, and are
not driven at resonance by an alternating signal.
Another significant difference between the Optacon reeds and braille
display reeds is that Optacon reeds had silver metal coatings, unlike
the braille cell reeds that use nickle metal coatings. The nickle
metal plating (sometimes with Parylene Conformal overcoating) was
required to solve the problems we had with silver ion
migration. Silver ion migration was not a problem for the Optacon
reeds because they were being driven with an alternating voltage,
rather than with DC voltages, as is the case for braille reeds.
I have something like a thousand of the original Optacon reeds, still
in their original shipping containers, if you need several hundred
for a prototype system.
If you are interested, feel free to contact me off list.
Cordially,
Noel
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Noel H. Runyan
Phone: 1-408-866-7564
Email: Noel@xxxxxxxxxxxxxxxxxxxxxxx
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At 12:33 PM 9/20/2020, you wrote:
Hi Charles,
When you say the vibrotactile display being "prototypable" easier and for
far less cost, can you elaborate?
As I understand it, in the 1970's the piezo reeds were available as off the
shelf parts for record cartridges.
Nowadays the smallest piezo reeds available are those for braille devices,
at 2mm wide.
The piezo reeds for the optacon are only 1mm wide. This creates a problem
for workholding the reeds when they are being machined.
The few manufacturers that I contacted quoted me several thousand dollars
for 500 piezo reeds.
Kind regards,
Wannes Sels
On Sun, Sep 20, 2020 at 7:59 PM CHARLES POND <dmarc-noreply@xxxxxxxxxxxxx>
wrote:
Aside from being computer compatible, and with room for development, and
a few other lesser details like a slightly bigger display and many more
tactile-actuators than the 144 pins of the R1C/D, and a smaller
footprint, the only real big advantages of the pre-pprototype technology
here is that one can build the vibrotactile displays easily and for far
less cost. Even so, a thousand mamoolian is beyond many blind people
because they do not have a whole lot of readily disposable income.
P.S. In the interest of full disclosure I acknowledge that I am not
photon-dependent.
Charles
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