GRUEN TELETIME FIELD EFFECT LCD 1972
The "Teletime" is said to be the first LCD wristwatch with Field Effect display introduced to market in 1972 as mentioned in Pieter Doensen's book. That sounds quite unbelievable as it would be as early as the first batch of Optel DSM's that were a technical failure (Fortune article Oct'73). Those early Teletime's must have been either prototypes or sold in a very limited number otherwise such an invention in 1972 would be made more famous than the revolutionary Optels. Nevertheless everything is possible especially that both DSM and FE technologies were developed in parallel by different people and then applied by various industries. One 1972 ad shows a Teletime with DSM display but it's just an enhanced picture or maybe it's the prototype? Another 1973 ad presents the Teletime in the way it was produced.
Although advertized as Gruen the Teletime has got nothing in common with the once reputable American watch company. By the 1970's Gruen remained as a brand and all watches were outsourced. The Teletime module was solely created by American Microsystems Inc. (AMI) and also fitted to many other brands in 1973-75 according to codes on small stickers as well as the chip substrates. For some reason the inventors equipped these modules with a crown-setting function just like in the Optels yet the stem protrudes all the way inside the module and is secured with a tiny screw like in a mechanical watch. Time is advanced by turning the crown 45°: counterclockwise for hours and clockwise (when pulled out) to change the minutes.
The construction is smart and can be easily disassembled. The top green pertinax substrate contains basic electronic components and once removed reveals the display assembly. It is pressed together with two metal clamps and consists of a glass package, a polarizing filter and ceramic substrate with sealed microchip. A truly clean and sophisticated construction if compared to other digital watches from those years :) Based on my experience I can say that the most problematic component is the liquid crystal glass package thus if damaged it can be quite easily replaced from another AMI module found in many Westclox, Micronta and no-name watches. Btw. Compare the AMI logo on the chips with the Zenith Time Command LED
Keywords: gruen teletime, field effect lcd
Market value: 50-300$ (version, condition, box)