Permission to reproduce pages 262 to 265 of the book L'aventure de la montre à quartz by Max Forrer, René Le Coultre, André Beyner and Henri Oguey, Centredoc 2002, has been granted by the Centredoc. The authors of this chapter, "Calibre Delta et projet FAN" are R. Vuilleumier, R. Le Coultre. The research and development described in the chapter was executed by Centre Electronique Horloger SA, Neuchâtel, Switzerland, in partial collaboration with Montres Rolex SA, Geneva.
Figure 17.3.2 is a 1972 prototype of a unique solar powered watch developed by Centre Electronique Horloger (CEH) which had an analog LED display. Because of the limitations of the solar cell technology and power requirements of the LED, the LED “hands” flashed a high rate so that they appeared to be on constantly (Talbot’s law).
The other watch described in this chapter is a 1978 prototype of an LED watch (non-solar) that CEH collaborated on with Montres Rolex.