2023 年 67 巻 228 号 p. 13-26
The authors developed the Cal. 9RA as the next generation of the Cal. 9R6, which has been the core caliber of automatic SPRING DRIVE since 2004, aiming for higher accuracy, lower profile, and longer duration time. The Cal. 9RA movement has a low-power temperature compensation circuit and a VACUUM PACKAGED IC to reduce the effects of temperature and humidity to ±10 s/month. Cal. 9RA also features a thickness of 5.0 mm and a duration of 120 hours thanks to the use of a DUAL SIZE BARREL and an OFFSET MAGIC LEVER.