Pocket watches may seem like kitschy remnants of a bygone age, but that didn't stop Citizen from using one to showcase its latest technology. Unveiled quietly at this year's Baselworld exhibition, the Citizen Caliber 0100 Eco-Drive is a solar-powered concept pocket watch that is accurate to within ± one second per year thanks to a new movement that incorporates self-correcting technology and the company's proprietary Eco-Drive power system.

Concept watches specially built to introduce technological advances to the market are nothing new, but using a pocket watch design in 2018 is a bit on the unusual side. However, there is an historical element to help explain the novelty. This year marks the centenary of the Citizen watch company and the 0100 was designed as a homage to the first Citizen pocket watch, which was released in 1924.

Solar-powered watches also aren't anything new. They've been around since the 1970s and Citizen has been in the game since its Citizen Crystron Mega was released in 1975. This had an accuracy of ±3 seconds per year, which was impressive when low-end watches could only manage ±15 seconds per month, and high-end quartz watches came in at ±10 seconds per year.

The handmade 0100 includes several advances. Though it may look like it came off the prop table for a touring production of Guys and Dolls, its white dial with index hour markers and seconds hand hides the amorphous silicon photocell for the Eco-Drive, which powers the movement and charges a special titanium lithium ion secondary battery. According to Citizen, the 0100 can run for six months even if you forget it in your pocket. This is because there are several energy-conserving functions, including a hibernation mode where the watch continues to mark time, but doesn't move the hands until it's exposed to light again, at which point it shifts them to the correct time.

But the centerpiece of the 0100 is the movement's replacement of the traditional tuning fork-shaped quartz crystal operating at 32,768 Hz with an original AT-cut quartz oscillator that has been cut at an angle of 35.25°. This provides the crystal with a specific set of characteristics, including the ability to vibrate at a frequency of 8.4 MHz (8,388,608 Hz) under temperatures of between -20° C and 60° C (-4° F and 140° F).

The upshot of this is that the quartz oscillator is much more accurate and is much more stable when exposed to temperature changes and movement. To make things even more accurate, the 0100 movement is self-monitoring and self-regulating. If it detects a shift in frequency, it automatically compensates and moves the hands to keep them on the precise time.

The new 2.92-mm-thick movement is sealed in a stainless steel case with sapphire crystals front and back to show off the mechanics. Citizen says that the Caliber 0100 prototype is not for sale, but that the technology will be included in future models beginning next year.

Source: Citizen via Hodinkee

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