Orient Star's 70 Year History: A Sparkling Climax

The 46 series caliber has supported Orient Star since its launch in 1971. Its robust and highly accurate design makes it worthy of being called a core movement. In 2021, marking the 70th anniversary of Orient Star's birth, Epson has significantly revamped the 46 series caliber. By adopting silicon material for the escape wheel, performance has been dramatically improved.

The stars that shine for ages

　Epson's new Orient Star Classic Collection "Skeleton" watch features a silicon escape wheel, a first for a Japanese mechanical watch. Seiko Epson Chairman Minoru Usui once stated, "We want to innovate Orient by leveraging Epson's superior technology." Epson boasts high technological capabilities not only in printers but also in the world of precision machinery. While they are certainly adept at handling new materials and technologies, no one expected them to make the leap into a silicon escape wheel. The company first became interested in silicon as a material in January 2016. They began prototyping escape wheels using this material in mid-2018, and finally unveiled the watch in 2021, the 70th anniversary of the birth of Orient Star.

　The original purpose of using silicon was to improve escapement efficiency. Making the escape wheel out of a lighter material reduces its moment of inertia, extending the power reserve and improving timing accuracy. At the same time, improving processing precision can reduce drive loss. Epson considered a variety of materials, including processing methods. The final choice was silicon, a material that is becoming increasingly popular in the watch industry. Of course, the company did not choose silicon because it was trending in the watch industry. For many years, Epson has used MEMS technology to manufacture printer heads. Switching to silicon was an obvious choice for the company.

　The silicon escape wheel is processed as follows: a photosensitive resin patterned in the shape of an escape wheel is formed on the surface of a silicon wafer, and then processed with plasma. According to Epson, "The silicon surface processed with plasma has an uneven shape, which makes silicon's fragile nature more apparent. As is, it is not suitable for functional parts like escape wheels, but by smoothing the surface, its strength can be greatly increased." Therefore, by adding a process of repeated thermal oxidation treatment and removal to create a smooth surface, the strength of the silicon escape wheel has been increased and its wear resistance has also been improved compared to conventional nickel silver materials.

　However, even though silicon is strong and resistant to wear, it is a difficult material to handle. An escape wheel molded from silicon needs to be fixed to a steel pinion. If too much force is applied or the axis is misaligned, it can easily break. This is why the use of silicon escape wheels has been limited to some high-end models until now. Epson has found a solution by adding spring properties to the attachment point with the pinion.

　MEMS technology allows for processing at the micron level. Using this method, it was possible to give springiness to easily broken silicon. While silicon has a tendency to break, it also has the ability to bend when it is thin enough. Epson's engineers wondered if they could make use of this characteristic. If the attachment part of the escape wheel is given springiness, it can prevent damage during attachment, and even if there is some error in the dimensions of the pinion, the escape wheel can theoretically be fixed with high precision. Epson therefore prototyped several escape wheels with springiness in the center. By combining a fan-shaped attachment part with a new pinion with a slit on the side, it became possible to prevent breakage and fix the silicon escape wheel with precision.

　As a result, the silicon escape wheel brought amazing results to the 46 series movement. To extend the duration, the mainspring was made thinner and the torque was reduced, extending the power reserve from approximately 50 hours to approximately 70 hours, while the accuracy was reduced to within +15 to -5 seconds per day.

　However, even a silicon escape wheel would look dark if placed deep inside the movement. Epson therefore controlled the thickness of the multilayer film applied to the silicon material in nanometer increments. Additionally, by sandwiching a polysilicon film between two oxide films, they were able to give it a vibrant blue color. As an Epson representative said, a patent application is currently pending, this marks a new attempt to intentionally give color to silicon as a functional component.

A silicon escape wheel that combines Orient Star's history and Epson's technological expertise

　The movement's finish has also been improved. Previously, the finish was achieved with a rubber grindstone. However, the new 46 series calibers F8B62 and F8B63 now feature a machined wave pattern. The deliberately strong wave pattern, combined with the newly applied diamond-cut chamfering, gives the movement an even more luxurious appearance.

　The modifications to the exterior are also unique to Orient Star today. The case material has been changed from SUS304 to SUS316L, which has better corrosion resistance. The sapphire crystal used for the crystal has not only been changed from a single spherical surface to a double spherical surface, but also now has an anti-reflective coating on both sides. The adoption of a chrysanthemum-shaped crown, which takes into consideration the comfort of winding, is another thoughtful touch that is typical of Orient Star.

　Orient Star's new skeleton watch has significantly improved performance thanks to the adoption of a silicon escape wheel. The theme is "NOWHERE, NOW HERE (Something that doesn't exist anywhere. It's here now)." Indeed, Orient Star, celebrating its 70th anniversary, shows us a new horizon for Japanese-made watches that has never been seen before.