9R Spring Drive Caliber

Spring Drive is Seiko’s exclusive movement that achieves an unprecedented level of accuracy (+/- 15 seconds per month on average, equivalent to +/- 1 second per day) by regulating a spring-driven watch with state-of-the-art electronic technology that functions without batteries or other external power source.

As in conventional mechanical watches, the sole power source of Spring Drive is a mainspring that can be wound by the motion of an oscillating weight or by winding the crown. And just as in mechanical watches, the mainspring drives a series of gears that rotate the hour, minute and second hands. A rotor, connected to the end of these gears, generate a small electrical charge that activates an electronic circuit and quartz oscillator.

The Tri-synchro regulator is a unique speed controller for Spring Drive that replaces the escapement, which is a mechanical speed control device used in almost all conventional mechanical watches. The Tri-synchro regulator moves the second hand in a smooth motion, without ticking and with extreme accuracy.

Some 80% of the components in a Spring Drive caliber are the same as those in a luxury mechanical watch. Spring Drive is a movement powered by a spring, just like a mechanical watch, with a different kind of regulator and combines the long-lasting autonomy of a mechanical watch with the precision that, until now, only electronic watches could provide.

To ensure reliable and accurate operation, all these parts need to be manufactured to the highest standards of precision, and assembling them requires superior craftsmanship.

The development of the Spring Drive movement caliber 9R was made possible because Seiko is one of the very few manufactures with expertise in both mechanical and quartz watches.

Since the first Grand Seiko Spring Drive in 2004, new movements have been created with even more complex mechanisms--including the GMT in 2005 and chronograph with GMT in 2007. Showing that with the Spring Drive caliber 9R, time never loses momentum.

The Grand Seiko story and development approach

Since its foundation, Seiko has pursued precision in order to bring accurate time to as many people as possible.
In the 1960s, Seiko challenged the highest watchmaking standards of the time with Japanese innovation and craftsmanship in mechanical watchmaking.

Seiko released the world’s first quartz wristwatch in 1969, miniaturizing a quartz mechanism that was originally the size of a filing cabinet and achieving a degree of accuracy totally unattainable with mechanical technology. In fact, Seiko’s relentless pursuit of highly precise timepieces accelerated the commercialization of quartz watches throughout the industry.

Thanks to Seiko’s mastery of both mechanical and electronic watchmaking, Seiko was able to continue its search for the ultimate practical watch, and, in 2004, Spring Drive was born. Combining a traditional mainspring with an electronic regulator, Spring Drive offered the best of both worlds; a watch powered by the wearer’s motion but a level of accuracy many times higher than that achievable with any mechanical technology.

To meet the high standards of Grand Seiko, Spring Drive needed to offer more than precision, and an extended power reserve was the goal the development team chose. They set the target at 72 hours so that the watch would still be precise even after a weekend away from the wrist. The challenge was to develop a more efficient automatic winding system. Only then could Seiko claim to have produced the ultimate in practical watches.

Through an extensive process of R & D lasting 28 years, Seiko was able to realize this dream, which required advances in both mechanical and electronic watchmaking that were only possible because Seiko was, and still is, one of the very few manufactures that produces, assembles and adjusts parts for both mechanical and quartz movements—a true and deep integration of technology and craftsmanship.

Detail

Why Spring Drive was adopted for Grand Seiko

Grand Seiko’s history is a story of uncompromising effort and evolution in pursuit of higher quality practical watches.

By the end of the 1960’s, Seiko had reached the pinnacle of accuracy in mechanical watchmaking and Grand Seiko offered the very best of Seiko in this arena. In 1993, Grand Seiko reached new heights in accuracy with the quartz caliber 9F. A new mechanical caliber 9S was introduced in 1998, integrating traditional craftsmanship with the latest in technology.

Grand Seiko has a passion to produce the very best practical watches—to produce remarkable timepieces that customers will cherish for years to come. To achieve this, Grand Seiko breaks through the barriers of ordinary thinking into new territories, redefining the boundaries of what is possible.

This is the story of Grand Seiko—a watch that embodies this pioneering, challenging spirit.
Spring Drive is a meeting of craftsmanship and technology that symbolizes the philosophy of Grand Seiko.

The Challenge: An efficient automatic winding system for modern life

The biggest hurdle to overcome in developing the Spring Drive for Grand Seiko was creating an efficient automatic winding system with a power reserve of 72 hours. In overcoming this challenge, Grand Seiko created a watch that is truly aligned with modern lifestyles.

The automatic winding mechanism is based on Seiko’s Magic Lever innovation, originally developed in 1959. This extremely reliable system provided superior winding efficiency, manufacturability, durability and ease of maintenance. Its winding efficiency is now so high that it needs only half the amount of movement the average person makes in a day.

A close connection to the wearer

The development of Spring Drive was a task that called for the readdressing of a fundamental question: what is the pinnacle of practical watches?

Grand Seiko believes that there are no limits to what can be achieved if the goal of making the best practical watch in the world is pursued with passion. Seiko’s advanced technologies hold the key to the future, but tradition and the technical achievements of the past are also crucial guides to the needs and expectations of watch lovers. Spring Drive fuses both of these ideas.

With the accuracy of the very best in electronic watches and the charm, durability and convenience of a mechanical watch, Spring Drive caliber 9R innovatively combines the advantages of both of the leading watch technologies, marking the steady passage of time in harmony with the steps of our lives.

The genius of Seiko, one of the world’s leading manufactures

Seiko is one of the world’s leading manufactures, meaning that the entire watchmaking process, from the manufacture of components through to assembly and adjustment is completed by Seiko’s own engineers and watchmakers in Seiko’s own facilities. This in-house approach has been a key element in the development of Grand Seiko’s unique identity. From the earliest stages of planning, our staff come together to share ideas. All are experts in their respective fields, and all are united in the goal of creating a better, more practical watch. Rather than relying on a single team leader, all development staff share their concepts and ideas and collaborate to create a single watch.

The unique Spring Drive mechanism could only have been made a reality through the craftsmanship of a manufacture working with both electronic and mechanical movements.

Spring Drive mechanism

Spring Drive is a unique Seiko movement that requires neither a battery nor an electric motor, making it a completely self-contained system. Its power is derived from a mainspring, just like a mechanical watch, and its accuracy is controlled by the precise signal of a quartz oscillator.

Spring Drive is truly the best of both worlds—a spring driven movement that delivers high accuracy.

Detail

Tri-synchro regulator: A perfect synthesis of traditional mechanical and quartz technology

The Tri-synchro regulator is the heart of Spring Drive.

Although Spring Drive derives its energy from the mainspring, it is an IC that measures precisely the rotation rate of the gear train, applying a magnetic force to control its speed and allow the watch hands to move at a constant speed.

The rotational energy of the rotor, which is driven by the mainspring, is converted to minute amounts of electric energy. This electricity powers the IC and quartz oscillator, which together generate a precise reference time signal. The reference signal is used to regulate the speed of the rotor.
In this speed control process, unlike an escapement, there is no friction.
As a result, the second hand of Spring Drive moves smoothly in a glide motion that reflects the natural and continuous flow of time itself. To see the hands move in this unique way is to experience the constant , continuous and beautiful passage of time.
The rotor, stator, coil block, IC and quartz oscillator are key electronic components of the Tri-synchro regulator, and are the result of Seiko’s many years of extensive experience in electronic watch technology.

Power sourceMainspringSpeed Control SystemMechanical powerElectrical powerElectromagnetic powerRotor speed control

Meeting the challenge of a 72-hour power reserve

The target for Grand Seiko was to develop a watch with a 72 hour power reserve—a watch that would still be working on Monday morning even if removed from the wrist on Friday evening.

It is easy to increase the power reserve by making a larger watch, but a larger watch would compromise its practicality and comfort on the wrist. The challenge was to achieve a longer power reserve without increasing the size of the watch. This meant developing an intricate power management system.

Every aspect of power management was addressed. Seiko reduced energy loss in the wheel train, and made technical breakthroughs with pinion tooth polishing, gear shaft coatings, ultra-low power ICs and new coil windings for the Tri-synchro regulator.

Seiko’s ultimate success in overcoming the 72 hour power reserve challenge was based on half a century of quartz technology development and a constant honing of skills in mechanical watch making.

Pinion teeth polishing and shaft coating

The traditional technique of polishing pinion teeth with beech tree twigs was revived to improve mainspring energy transmission efficiency. At the same time, a low-friction coating was applied to certain parts of the wheel train, which required special skills to achieve an even coating while ensuring strong adherence on the extremely slender gear shafts.
By combining traditional skills and modern technology, friction and wear among critical parts were greatly reduced.

Ultra-low power IC consumes only 1/300,000,000th that of an LED light

Over the course of more than 20 years of R&D, IC technological innovation has made a key contribution to the realization of Spring Drive.

Since commercializing the world’s first quartz watch, Seiko has developed low-power ICs for other innovative watch technologies such as Kinetic and Solar.
Seiko’s know-how in power management was essential in developing an ultra-low power consuming IC for Spring Drive. It runs on astonishingly low wattage.

New coil winding technique for Tri-synchro regulator

The amount of electricity generated is determined by rotor speed, magnet strength and total wire length. For the Tri-synchro regulator, Seiko developed a new 25,000-turn coil winding technique, maximizing power generation efficiency with tightly wound, precisely aligned wire.

Refined mainspring

The mainspring was reformed to advance its performance. The new mainspring was made longer, thinner and the shape was modified.

Spring Drive Chronograph 9R86

The most accurate spring driven chronograph in the world

In 1969, Seiko introduced the world’s first automatic winding chronograph with a vertical clutch. Nearly 40 years later, in 2007, the Spring Drive chronograph was born—the most accurate spring driven chronograph ever.

Developing a chronograph was always part of the plan. From the very first steps in developing an automatic winding Spring Drive, one of the goals for Grand Seiko was to develop a chronograph with high accuracy.

Using Spring Drive as a platform it became possible to create a chronograph with +/- 1 second per day accuracy, a level of accuracy unattainable by conventional mechanical chronographs.

Creating this kind of chronograph did not only add mechanical complexity to Spring Drive. It also required improvements to the basic performance of Spring Drive in order to create the best possible practical chronograph.

The end result is a Spring Drive chronograph worthy of Grand Seiko, with incredibly high accuracy, precise operation and a 72 hour power reserve.

Technologies for high accuracy

As well as displaying the current time accurately, Seiko’s Spring Drive chronograph measures precise elapsed time.

Error-free control with the column wheel system

The column wheel system ensures precise, error free control of the chronograph operation. The column wheel is designed to reduce stress on the clutch and lever, minimizing impact on the movement when the start/stop button is pushed.

Vertical clutch eliminates the jumping of the hand

In a mechanical chronograph, part of the power for the time display is diverted to drive the chronograph hands through a clutch system, such that the time display and chronograph share the same degree of accuracy.

To adapt the highly accurate Spring Drive movement for a chronograph function, a vertical clutch was adopted that eliminates the jumping of the second hand when the chronograph is activated. It was originally used for caliber 6139 in 1969, and numerous improvements since then have improved its functionality.

Master craftsmanship in the assembly of over 400 parts

Quartz watches generally consist of less than 100 parts, and mechanical watches—even complicated chronographs—comprise between 200 and 300 parts.
The Spring Drive chronograph has over 400 parts.

Spring Drive combines the best elements of both mechanical and quartz watches, and the assembly process is extremely complex.

Design plans for the watch are based on tolerances of 1/100th of a millimeter. The final adjustments and refinement of parts are completed not by a robot or computer, but by the human hands of our proud craftsmen and women.

Design meets function

Grand Seiko, as the pinnacle of practical watches, epitomizes high legibility, precise measurement and everlasting beauty.

Separating chronograph display from time display

On the right half of the dial, sub-dials for chronograph minutes and hours are positioned in a vertical layout. The left half features the second hand of basic time and a power reserve indicator.
This unique layout creates perfect legibility of the separate functions.

Maximum legibility of the chronograph hands

There is a small but calculated gap of exactly 0.15 millimeters between the tip of the chronograph second hand and the second markers around the dial. Extensive analysis has found this to be the ideal distance between hand and markers for human eyes to clearly and precisely read elapsed time.

Grand Seiko style

Grand Seiko’s distinctive design language, featuring long, bold hands and easy-to-read dial faces, is reflected in the development of Spring Drive. By combining sophisticated design with Seiko’s legendary legibility, Seiko has created perhaps the ultimate in functional elegance.

Comparison of four calibers

Movement Accuracy Power reserve
(when fully wound)
Jewels 24 hours hand
(GMT)*1
Stop watch function
Spring Drive 8 Day 9R01
(Manual winding)
Average monthly rate of ±10 seconds
(equivalent to daily rate of ±0.5 second)
Approximately 192 hours
(About 8 days)
56    
Spring Drive Chronograph GMT 9R96
(Automatic with manual winding mechanism)
Average monthly rate of ±10 seconds
(equivalent to daily rate of ±0.5 second)
Approximately 72 hours
(About 3 days)
50
(up to 12 hours)
Spring Drive GMT 9R16
(Automatic with manual winding mechanism)
Average monthly rate of ±10 seconds
(equivalent to daily rate of ±0.5 second)
Approximately 72 hours
(About 3 days)
30  
Spring Drive 9R65
(Automatic with manual winding mechanism)
Average monthly rate of ±15 seconds
(equivalent to daily rate of ±1 second)
Approximately 72 hours
(About 3 days)
30    
Spring Drive Chronograph 9R84
(Automatic with manual winding mechanism)
Average monthly rate of ±15 seconds
(equivalent to daily rate of ±1 second)
Approximately 72 hours
(About 3 days)
41  
(up to 12 hours)
Spring Drive GMT 9R66
(Automatic with manual winding mechanism)
Average monthly rate of ±15 seconds
(equivalent to daily rate of ±1 second)
Approximately 72 hours
(About 3 days)
30  
Spring Drive Chronograph GMT 9R86
(Automatic with manual winding mechanism)
Average monthly rate of ±15 seconds
(equivalent to daily rate of ±1 second)
Approximately 72 hours
(About 3 days)
50
(up to 12 hours)
※1 GMT (Greenwich Mean Time) function enables the display of two different time zones using the hour hand and a 24-hour hand.