1970's digitizer tablets

From: Fred Cisin <cisin_at_xenosoft.com>
Date: Mon Jul 14 13:58:00 2003

> Sellam wrote:
> >In the late 1970s, AT&T's Bell Labs invented the "electronic blackboard".
> >It was basically a digitizing tablet that allowed one to draw and transmit
> >images.
> >Might anyone know where one exists? How about similar products prior to
> >December 1979? When was the first digitizing tablet invented?
> >This is research I'm conducting for a client, so any useful leads will be
> >compensated.
> >Thanks!
On Mon, 14 Jul 2003, McFadden, Mike wrote:
> I know we had a graphics tablet at the Bioengineering Program at the University
> of Missouri in 1975. It was a GrafPen Model (SP?). It consisted of two arrays of

LOTS of digitizers existed back then.
Anyone familiar with anything prior to the Gerber Data Digitizer in 1970?
(about a meter square, horizontal and vertical crosshairs, output directly
into a 026 punch)
Anyone HAVE one? or something earlier?

The claim to have invented "electronic blackboard" has to be narrowed
SUBSTANTIALLY, as all that they did was enlarge existing digitizers to
produce one suitable for classroom/conference room wall. It was an issue
of engineering, not invention.

What about an under $10 one for a MICROCOMPUTER/PERSONAL COMPUTER?
I will lay claim to the dubious honor of inventing that. (even though
it was so obvious that MANY people must have done so)
In 1983, I wanted a digitizer for blackboards. As a "proof of
concept", I attached a one foot long piece of clear plastic (a
ruler) to the shaft of a potentiometer. At the other end of it
I attached another potentiometer, with another foot long piece
of clear plastic attached to the shaft of that one. That made
for an upper arm hinged at the edge of the board with a
potentiometer, and a forearm hinged at the end of that with a
potentiometer at the "elbow".

I connected the potentiometers and a "fire" button to a DA15,
and plugged that into the joystick board ("Analog Input Board")
of a PC. (actually, for a while, I had a DIN connector on it
for Coco).

I could read the resistance of the two pots to know the "shoulder"
and "elbow" angles, and with some trivial trigonometry in software,
knew the location of the "hand". (You know the angle of the shoulder,
the length of the upper arm, the angle of the elbow, and the length of
the forearm) At the hand end, I had a hole, so that it could be
used for digitizing existing materials, by lining up the hole and
pressing the fire button, or with a pen through the hole and
"sampling" in a loop, it could do a horrendously bad job of
digitizing handwriting.


I intended to redo it with yardsticks for blackboards (with a
chalk sized hole in the hand), but the mechanical issues of a
yardstick flopping around on the end of another yardstick were
a bit much. And a usable one would require better resolution
of the analog to digital circuitry than I could get out of the
6 bits per pot using the IBM joystick board.

--
Grumpy Ol' Fred     		cisin_at_xenosoft.com
Received on Mon Jul 14 2003 - 13:58:00 BST

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