The Cellar - 7 Segment display

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- - 7 Segment display (http://cellar.org/showthread.php?t=30988)

7 Segment display

I had limited contact with electronics, beyond consumer level, before the eighties. I'd seen Nixie tubes but I don't remember seeing seven segment displays before calculators and consumer electronics made them ubiquitous.
http://cellar.org/2015/segments.gif
Of course they're everywhere now but I was surprised they were patented in 1908. Seems they played out of town doing Summer Stock, Reparatory and maybe the Borsht Belt, paying their dues before they hit the big-time.

The OCR on the page for the 1908 patent is bad, but the scans are interesting. It was apparently intended as a military signaling device for artillery. The first digit couldn't be more than 1, and the last two could be 00 or 50.

It's confusing at Wiki....

Quote:

Seven-segment displays can be found in patents as early as 1908 (in U.S. Patent 974,943, F W Wood invented an 8-segment display, which displayed the number 4 using a diagonal bar). In 1910, a seven-segment display illuminated by incandescent bulbs was used on a power-plant boiler room signal panel.[5] They did not achieve widespread use until the advent of LEDs in the 1970s.

That link is to the patent for Wood's eight segment display which is clearly illuminated by incandescent bulbs. If the later boiler room seven segment display was also lit with incandescent bulbs, what the hell lit the earlier seven segment display? :confused: