19 Sep
2007
19 Sep
'07
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.