Some here may not have seen this as it was forwarded to GUI-Talk.
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>From: "Steve Pattison" <pattist@ozemail.com.au>
>Date: Thu, 09 Mar 2000 19:45:31 +1100
>Subject: Fwd: Another braille display method
>To: gui-talk@NFBnet.org (Multiple recipients of NFBnet GUI-TALK Mailing List)
From: David Dewhurst DavidDewhurst@compuserve.com
To: ACCESS-L access-l@icomm.ca
Greetings,
I was interested to read Martin McCormick's posting concerning how
surprisingly difficult the braille display problem is, and also Steve
Pattison's posting of Deane Blazie's presentation on recent
developments in refreshable displays. I was particularly interested in
the description of a tactile display that uses a "print head" to raise
dots - I came up with a very similar idea last year (I was going to
modify a dot-matrix print head to do the lifting) but hit many basic
problems. However while considering it I decided to look again at a
different approach that I devised a while back - this was outlined in a
posting back in January but got very little response - I'm going to
describe it differently to see if you think a) it's been done before or
b) you can see any fundamental problems...
Imagine a small coin, and around the outside rim (which is normally
flat or serrated) there are moulded braille dots (raised or
flat/"off"). If there were 16 or 19 of them then the order could be
0000101111010011(000), where 1 represents a raised dot and 0 represents
an unraised dot position. This arrangement allows all 16 possible
combinations of 4 raised or unraised dots to be found. Two such discs
can be positioned next to each other to produce any required 8-dot
braille cell (with the other dots masked off). Several such pairs could
be arranged as a cylinder to produce a braille display.
The pattern of dots around the edge of each disc is a minimum of 16
dot-positions long if joined at each end (there are 16 such patterns)
and a minimum of 19 dot-positions long if not joined. If you are using
6-dot braille then a single disc can be used for each cell, as 64 "dot
pairs" (i.e. 2 horizontally-arranged dots) can be moulded around a disc
that is just under two inches diameter.
A disadvantage of using discs is that they present a slightly curved
surface, so alternatively you can use flexible bands or rods instead.
Whichever method is used, they are positioned to form the pattern of
the required message (the bands are aligned in a row, so that the
characters on several bands form a line - like the wheels on an old-
style gambling "slot-machine" or "one-armed bandit").
The advantages of this approach is that 1) only one "actuator" is
needed per disc (or band); 2) the dots can be permanently moulded in
position i.e. do not have to rise and fall; and 3) non-braille tactile
characters such as Moon can also be presented.
The number of actuators can be reduced if serial updating is performed
(though this is slower and in some ways more complicated).
If there is any interest, I can put more info. up on my website to
explain the concept in more detail.
Best regards,
David Dewhurst
Regards Steve,
mailto:pattist@ozemail.com.au
-- This mailing list is sponsored by the National Federation of the Blind, NFB. For more information about the NfB, please call (410) 659-9314, point your internet browser to http://www.nfb.org or Telnet to nfbnet.org.===================END FORWARDED MESSAGE===================
Steve Jacobson E-mail: sojacobson@mmm.com National Federation of the Blind
The Opinions expressed do not necessarily reflect those of the 3M Company
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