Learn more about Caliber 9F

A braking wheel that incorporates a hairspring
A braking wheel that incorporates a hairspring

The magic behind the beautiful motion of the seconds hand

Mechanisms using springs to reduce backlash are used in several industries, including in automobile engines. Several methods to reduce the inevitable occurrence of backlash were considered before the use of a hairspring was decided upon, with a major consideration being, of course, that Grand Seiko’s expertise in the making of these springs was unrivalled. It was an irony that Natori and his team enjoyed that a solution to a challenge in a quartz watch should come from the realm of mechanical watchmaking. The Backlash Auto-Adjust Mechanism chosen for Caliber 9F added an extra wheel with a hairspring, a braking wheel, to the gear train. Its purpose was to exert torque in the opposite direction from the rotation of the gear train. This minimized the play between the wheel teeth. The hairspring, which is central to the accuracy of every mechanical wristwatch, was thus given another mission, to enhance the precision of the motion of the seconds hand in a quartz timepiece.

The Independent Axis Structure. The three axes do not touch each other.
The Independent Axis Structure.
The three axes do not touch each other.

The Independent Axis Structure

The 9F caliber also incorporates an Independent Axis Structure which governs the behavior of the seconds hand when the time is being set. In conventional timepieces, when the crown is pulled out and turned to adjust the time, the force is transmitted through a different pathway from that used to move the hands when the watch is operating. This can result in a quivering of the seconds hand and a resulting impression of imprecision. Again, this was judged by the development team to be out of keeping with the high standards of Grand Seiko and so they designed Caliber 9F with each of the three hands on a truly independent axis, with the axes kept separate and therefore at no risk of interfering with each other. As the international traveler adjusts the watch for a different time zone, the precise motion of each hand is clear.

A new concept that made the impossible possible
A new concept that made the impossible possible

A Twin Pulse Control Motor allows the use of the long and elegant hands that are the Grand Seiko signature.

Because quartz movements produce less torque than mechanical movements, the hands must inevitably be narrower and lighter. Such was the conventional wisdom. The development team was determined by to use the same long, broad and graceful hands that were used on most Grand Seiko mechanical watches so they invented a new, more powerful motor to drive these heavier hands and so ensure that every 9F watch shared the signature Grand Seiko look and offered maximum legibility. The Twin Pulse Control Motor they conceived was based on a simple truth. A regular quartz movement moves the seconds hand once every second, a rotation of six degrees per second, but less torque would be required if the angle were to be smaller. The team decided that the seconds hand of Caliber 9F would move twice per second and therefore be able to move the longer, wider hands of Grand Seiko. This two-step motion was hardly visible to the naked eye but was central to the overall design of the watch and showed, once again, that Caliber 9F set a new standard for the quartz watch.