Analog Quartz Calibers
Totally Swiss Rolex ignored microelectronics until the early 1970s; as a shareholder of CEH [Centre électronique Horloger] it obtained 320 Beta 21 calibers out of the 6,000 that were actually produced. What’s more, Rolex bought 650 pieces of the Beta 22 version produced by Omega; they are known as the Rolex Caliber 5100. Accordingly, Rolex Bienne was part of the consortium that financed the Neosonic-AFIF adventure with the known, sad end. Rolex Geneva was not involved.
After this easy beginning, it was quite clear to Heiniger that Rolex had to be independent in the realm of microelectronics too. In 1971 he hired René Le Coultre (b. 1918) who was then technical director of the Fédération Horlogère (FH). Le Coultre headed the technical department with a staff of 49, including 10 engineers. His first activity was to set up a top modern electronics lab with 13 people. He was then in a position to design quartz equivalents of Rolex’s mechanical calibers. This was not too difficult: at that time, Rolex only produced a ladies’ watch movement with two hands, a version with three hands, and a men’s watch caliber with sweep seconds hand and date or day/date.
The CMOS integrated circuit Rolex needed was supplied by ébauches électroniques Marin, while the anchor-type motor was purchased from FAR (Fabriques d’Assortiments Réunies). Silver oxide batteries were available from the Swiss Renata company as well as from American and German suppliers. Total production of the Caliber 5035/5055 is precisely known: 105,097 – not terribly much considering that the product life was 26 years! Each and every one of them was certified by COSC as an electronic chronometer. Those movements were decorated with Geneva stripes exactly like a mechanical Rolex movement; they featured 11 jewels. In the mid-1980s, the Rolex quartz movements were redesigned and modernized through and through. The result of this work was Caliber 5235 (with date) and 5255 (with day/date). Caliber 5235, with a diameter of 28.10 mm and a height of 5.40 mm, was equipped with a Faselec chip that included digital frequency tuning, a Lavet stepping motor from ETA and an 11.6-mm three-volt lithium battery. The same applied for the day/date Caliber 5255 (29.90 mm by 5.80 mm). These were among the best conventional quartz calibers that were ever designed – unluckily, they never saw mass production.
And the Rolex quartz caliber for ladies’ watches (Caliber 6035) with sweep seconds hand and date disk had the exact same dimensions as the Ladies’ Datejust (19.79 mm by 5.00 mm). The frequency of the 32 kHz Micro Crystal tuning fork quartz resonator was fine-tuned with a trimmer. The CMOS circuit was purchased from Faselec, the Lavet motor from Seiko. The energy source was a 7.90-mm silver oxide battery. Thirty prototypes of Caliber 6035 were built but there was no mass production. However, Cellini quartz models were equipped with Caliber 6620 (no seconds hand): this caliber was directly derived from Caliber 6035. In July 1983, 20 prototypes of Caliber 6620 were available for tests that took a long time; serial production started as late as 1987. The diameter was 8? lignes (19.80 mm); the height 2.5 mm. The parts were standard Rolex issue, as mentioned above. In 1990, production of Caliber 6621 started; this time the trimmer was replaced by an inhibition circuit. Production of this caliber continues to this day; total production so far is well over 100,000 pieces.
Rolex developed several technically advanced quartz movements that never got beyond the prototype stage. The most interesting of them certainly was a thermo-compensated quartz caliber that was developed in 1985. Design studies were made with incredibly stable high frequency (1.2 MHz and 2.4 MHz) quartz resonators with the ZT cut. The CEH produced those resonators and delivered 1,000 pieces in 1984. In 1986, Rolex built 50 prototypes whereas there was no production, although the yearly rate was just a few seconds. Another hugely ingenious quartz caliber with a perpetual calendar had the same fate. It was set in a certainly easy way;also it featured a 2.4 MHz quartz resonator with ZT cut as well as a standard 32 kHz resonator. As the ZT quartz and its divider circuit needed a lot of power, it was only switched on every 10 minutes for 10 seconds in order to set the 32 kHz frequency. An extraordinary rate and a battery life of 10 years were achieved with a three-volt lithium battery that measured 22.0 mm by 2.5 mm. The 30-mm caliber featured three motors for the seconds, the minutes and hour, and the day/date function, respectively. This design was patented; the patent became public domain in 2011. A test series of 400 pieces was assembled, however there was no production; none of those prototypes ever left the Rolex premises.