LONGINES GEMINI II DUAL LCD LED 1975
The Gemini II is the first dual display digital wristwatch introduced by Longines in late 1975 and sold until 1978. The one of a kind module was developed by Hughes Aircraft for exclusive use by Longines-Wittnauer so it can also be found in some rarer steel versions by Wittnauer. The G-II was marketed as the first "day&night" wristwatch with a robust Field Effect LCD for daily use and a bright LED readout for dark environments. Check advertizement to the left.
Back in 1975 there were already a few LCD watches with backlit display but most were inefficient energy-wise and provided poor visibility. In result such an akward and expensive dual concept must have been chosen as a better alternative than fitting a light function for night viewing. If that would have happened the G-II would probably never become collectible... a full set with tags and original box is hard to find. There is even a dual ana-digi G-II (with separate movements) that hardly anybody knows about. The one I had went to Peter Wenzig so check his website. The common LED/LCD G-II has one module with all the circuitry fitted on a ceramic substrate. Both displays are driven separately by the chip by means of separate wirebonds thus missing segments in either display will have different sources.
The substrate is encapsuled in a red plastic carrier with the top part equipped with a flat magnifiying lense for the exposed wire-bonded LED display. The LCD is a common construction with zebra-conductor and is placed on top of a removable cover that secures the exposed circuitry. During assembly everything needs to be perfectly alligned and secured with a drop of glue or silicone to prevent the exposed wires from accidental damage. Please note the small piece of black or yellow tape placed on the right-hand edge of the LCD zebra-conductor that insulates a few traces supplying current to the LED section. Although both displays have separate drivers, missing LCD segments might also result from a damaged display or low pressure from a metal frame on top of the module. Broken wire-bonds can be repaired with silver epoxy after identifying and matching segments with correct traces.
Keywords: longines gemini, dual display, led+lcd
Market value: 100-450$ (condition, box)