Greetings fellow LED watch aficionados!
The afore referenced patent number was stamped on the stainless steel case back of an unbranded early dot display sold on e-bay. Using the Google Patent Search, I was able to look up this 1974 patent for a LED watch circuit. In essence, the relatively low voltage batteries power the digital quartz time keeping circuitry, then output of said is ramped up for a short duty cycle to brightly illuminate the LED segments.
The coil in your car does much the same thing when you crank the starter using your 12V battery in the morning. The major difference here is that the alternator in your car’s engine compartment replenishes the battery with combustion energy.
https://www.google.com/patents/US381535 ... CB0Q6AEwAA Happy Collecting! Jason