19 Sep
2007
19 Sep
'07
6:25 a.m.
One thing I've always been really curious about is who invented the
seven segment display. Not a particular implementation of it, but
the graphic design concept that seven bars are all you need to
display the digits 0 - 9. I'd always assumed it was something that
originated from the creation of electronic calculators. The first
Friden EC-130 for example, uses seven segment patterns on a CRT
(machines prior to that used Nixie tubes).
Well, leave it to Don Knuth to dig up a much older reference. While
browsing his web pages, I noticed a reference to patent 974,943 by
F.W. Wood, issued in 1910(!). It describes an electro-mechanical
"Illuminated Announcement and Display Signal" with a segmented
display. Wood actually uses eight segments (so his "4" has a slanted
top), but other than that, it's exactly the same design as the digits
today's cheap watches and calculators.
Patent (you may need to register first):
http://www.freepatentsonline.com/0974943.pdf
Cheers,
jp
19 Sep
19 Sep
7:38 a.m.
On 18 Sep 2007 at 22:25, J. Peterson wrote:
Patent (you may need to register first):
http://www.freepatentsonline.com/0974943.pdf
...Or skip the registration and crank the patent number in here:
http://patft.uspto.gov/netahtml/PTO/srchnum.htm
--Chuck
"They're from the Government and they're here to help you..."
8:01 a.m.
"J. Peterson" wrote:
One thing I've always been really curious about is who invented the
seven segment display. Not a particular implementation of it, but
the graphic design concept that seven bars are all you need to
display the digits 0 - 9. I'd always assumed it was something that
originated from the creation of electronic calculators. The first
Friden EC-130 for example, uses seven segment patterns on a CRT
(machines prior to that used Nixie tubes).
Well, leave it to Don Knuth to dig up a much older reference. While
browsing his web pages, I noticed a reference to patent 974,943 by
F.W. Wood, issued in 1910(!). It describes an electro-mechanical
"Illuminated Announcement and Display Signal" with a segmented
display. Wood actually uses eight segments (so his "4" has a slanted
top), but other than that, it's exactly the same design as the digits
today's cheap watches and calculators.
Patent (you may need to register first):
http://www.freepatentsonline.com/0974943.pdf
I was similarly curious and had looked into it a little further back when we
were discussing the Apollo Guidance Computer and it's display. I too had been
surprised by the early patent. I had been wondering if the illuminated displays
of the AGC contributed to popularising the idea and helped kicked off the development
of those other forms (incand./vacuum-flourescent/LED/gas-discharge/etc.) which
came along late-60s/early-70s in calculators, but I forgot about the EC-130 which
pre-dates the AGC.
Don't have a ref or example but I think that one of the first practical uses
of segmented numeric displays was for large electro-mechanical or illuminated
sports/racetrack scoreboards back in the 30's or 40's. I could swear I've seen
them
in movies from the era.
10:37 a.m.
J. Peterson wrote:
Well, leave it to Don Knuth to dig up a much older
reference. While
browsing his web pages, I noticed a reference to patent 974,943 by F.W.
Wood, issued in 1910(!). It describes an electro-mechanical "Illuminated
Announcement and Display Signal" with a segmented display. Wood
actually uses eight segments (so his "4" has a slanted top), but other
than that, it's exactly the same design as the digits today's cheap
watches and calculators.
I could imagine there being an even older purely-mechanical analogue to be
honest; perhaps with segments that could rotate and were white on one side and
black on the other, against a black background.
It wouldn't be particularly complex to do (a few pushrods and a bunch 'o cams)
and would take up a lot less space than the 'reel of numbers + viewing window'
of the day. Not suitable for miniaturisation, but easily workable for large
display signs.
However, I'm not sure when the 'airport'-style displays with a reel of flaps
containing the digits (or letters) appeared; they'd be about as compact as a
mechanical seven-seg display, but with less maintenance requirement...
cheers
Jules
1:14 p.m.
I could imagine there being an even older
purely-mechanical analogue to be
honest; perhaps with segments that could rotate and
were white on one side and
black on the other, against a black background.
While definitely newer than the 1910 patent mentioned
earlier, I have a mechanical 7 segment clock. I think
it was made somewhere in the late 70's/early 80's
(woodgrain plastic). From the front, it resembles a
run of the mill digital clock, save for the fact that
the display is white-orange. Inside is a purely
mechanical contrivance with plastic cards with slots
cut in them. A light bulb shines through them and
"projects" the numbers onto the face.
It's really cool, if only for the fact that it's
unusual. Not only can you hear the motor changing the
numbers, but when the numbers change, they kinda
"melt" into one another, as segments don't instantly
flick off all at once. It was made by General
Electric. My assumption was that they wanted to get
the style of the then-expensive digital LED clock, but
make it cheap. (motors and mechanical stuff used to
actually be cheaper than electronics - remember
that?).
-Ian
11:54 p.m.
Well, leave it to Don Knuth to dig up a much older
reference. While
browsing his web pages, I noticed a reference to patent 974,943 by
F.W. Wood, issued in 1910(!). It describes an electro-mechanical
"Illuminated Announcement and Display Signal" with a segmented
display. Wood actually uses eight segments (so his "4" has a slanted
top), but other than that, it's exactly the same design as the digits
today's cheap watches and calculators.
Somewhat later, but still interesting :
I have a book here entitled 'Incandescent and Arc Lighting, Electric
Wiring, Headting and Signs' from International Correspondance Schools
Ltd. I can't find a copyright date on it, but I would estimate it's from
the 1930s.
It describes something called a 'Monogram Letter'/'Monogram Sign'. This
was a 21-segment (!) alphanumeic display. Each segment was illuminated by
a seprate electric light bulb, controlled by a mechancial rotating swtich
or by cards floating on a trough of mercury. The segment arrangement is a
bit difficult to show in ASCII, but here goes :
`- -'
|\|/|
-o-
|/|\|
'- - `
Where each ASCII character represents a segment of the display. It's like
the 14 segmetn 'starburst' display with the addition of 4 corner
segnements, a circlar 'segment' in the very center, and that the top and
bottom segmetns are split in half.
-tony
6328
days inactive
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