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April 14, 2020
Grand Seiko's 60th Anniversary: The Ultra-Long Power Reserve "Spring Drive 5 Days" | GRAND SEIKO
GRAND SEIKO | Grand Seiko
Introducing the "Spring Drive 5 Days," the next-generation movement carrying Grand Seiko's new history.
To commemorate Grand Seiko's 60th anniversary, a limited collection of two models, each equipped with a newly developed movement featuring the unique Spring Drive mechanism, is scheduled to be released sequentially in Japan and overseas starting August 1, 2020.
Text by OZAKI Sayaka | Edit by TSUCHIDA Takashi
A newly designed movement that is thin, long-lasting, highly accurate, and beautiful.
Since its inception in 1960, born from the pinnacle of contemporary technology and craftsmanship, Grand Seiko has built its tradition by relentlessly pursuing and achieving the essence of a wristwatch—accuracy, beauty, and legibility—at the highest level. In 2020, it finally marks its 60th anniversary. Just as a watch's second hand completes its sweep in 60 seconds to mark a new second, Grand Seiko releases an innovative collection to forge a new history at this milestone.
Carrying the brand's new history is the "Spring Drive 5 Days," an evolution of the 9R Spring Drive series. To achieve unprecedented wearability, this model features not only a thinner movement but also a lower center of gravity by positioning the crown as close to the case back as possible.
A key element was the "Magic Lever," the automatic winding mechanism. Traditionally positioned near the center of the movement to enhance winding efficiency, this mechanism has been offset from the center to achieve a thinner profile. Furthermore, improvements in component processing accuracy have enabled a new structure that maintains winding efficiency.
While pursuing thinness, robustness is ensured by arranging the gear train near the center of the movement and supporting multiple shafts with a single plate, such as the "one-piece center bridge." This design also provides shock resistance capable of withstanding diver's watch standards.
While the power reserve of conventional Spring Drive movements was approximately 72 hours (3 days) when fully wound, the Caliber 9RA5 achieves a significantly extended power reserve of approximately 120 hours (5 days) when fully wound by employing two mainspring barrels. To deliver the required duration and high torque within a limited space, two mainspring barrels of different sizes, "dual-size barrels," are used. The mainsprings within the barrels and the gear train connecting them have also been newly developed to achieve optimal torque.
Spring Drive, which previously achieved an accuracy of ±15 seconds per month by selecting superior quartz crystals, now achieves an average monthly accuracy of ±10 seconds with the Caliber 9RA5. To enhance precision, a newly developed IC with a built-in temperature sensor is used, along with a three-month aging process that artificially induces secular variation by applying a constant voltage, ensuring that only quartz crystals with stabilized performance are selected. Furthermore, a new structure called "Package IC" encloses the IC and quartz crystal in a single vacuum package.
This brings the temperature sensor in the IC and the quartz crystal extremely close, reducing temperature differences and improving temperature compensation accuracy. This new structure also maintains stable accuracy against humidity changes from the outside air. The shielding effect of the package also enhances reliability by making it more resistant to noise from static electricity and light.
Spring Drive, which is resistant to temperature variations and shocks, has repeatedly proven its high reliability in extreme environments such as outer space and Mount Everest. To showcase the true prowess of Spring Drive in these demanding scenarios, a professional diver's watch with a 600-meter saturation diving specification was chosen as the debut model for the new "Caliber 9RA5." The case, designed for disassembly and maintenance to ensure consistent operability even with prolonged use, has also been thinned, mirroring the new movement.
This collection includes a world-limited edition of 700 pieces featuring the brand's iconic "Grand Seiko Blue" dial, and a Japan-limited edition of 60 pieces with a beautiful deep green dial inspired by the rich nature of the region where Spring Drive was born. Both models come with a reinforced silicone strap, and the case back is engraved with "Limited Edition" and the serial number, signifying a collection celebrating the birth of the next-generation Spring Drive.
Furthermore, the "Caliber 9RA5" was designed with a refined and beautiful exterior, with designers and engineers collaborating from the initial concept stage, drawing inspiration from the natural beauty of Nagano Prefecture's Shiojiri City, the development site. The exterior of this model expresses the sparkle of the cold, clear starry sky glimpsed through the frost-covered landscape just before the first winter snow, where rime ice transforms the grasslands and trees into a white spectacle.
This collection will be available at Grand Seiko Boutiques, and the world-limited edition will also be available at Grand Seiko Salons and Grand Seiko Master Shops.
Spring Drive 5 Days
Ref. | SLGA001, SLGA003
Movement | Automatic (Caliber 9RA5)
Power Reserve | Approx. 120 hours (approx. 5 days)
Functions | Date display, Power reserve display
Case Material | Bright Titanium
Case Diameter | 46.9mm
Bracelet Material | Bright Titanium (comes with an interchangeable reinforced silicone strap)
Water Resistance | 600m saturation diving
Limited Edition | World limited to 700 pieces (SLGA001), Japan limited to 60 pieces (SLGA003)
Price | ¥1,150,000 (excluding tax)
Sales | Scheduled to be available from August 1, 2020, at Grand Seiko Boutiques / Grand Seiko Salons / Grand Seiko Master Shops
