STUDY

Chinese scientists develop low-cost quartz 'super watch' technology

Low-cost quartz 'super-watch' technology could be used in a range of applications and may narrow the gap between China and the West

PUBLISHED : Sunday, 01 February, 2015, 8:12am
UPDATED : Thursday, 08 March, 2018, 6:04pm

Don't throw out your old quartz watch - with a slight tweak it could soon be accurate enough to guide a cruise missile, according to a new study by Chinese scientists.

An ordinary quartz watch, given a simple upgrade, can dramatically improve its timing accuracy - so much so that the margin of error would be less than a second over tens of thousands of years.

Accurate timing is crucial to precision-guided weapons, which use time differences to calculate speed and position.

Professor Lu Qingyou, the lead scientist of the study, said the technology was inspired by a new physical phenomenon they observed in quartz.

The clocking capability of quartz has been known for nearly a century. When applied with an alternating current, quartz crystal oscillators in the shape of a small tuning fork that are used in watches vibrate a stable frequency that provides accurate time measurement.

But even the remarkable stability of the compound is not permanent. Due to small but inevitable irregularities in the internal structure of quartz, the patterns of vibration shift over time, leading to errors.

Lu's team took a creative approach to address the issue and applied a stream of direct current over the alternating currents, causing an electrical "imbalance" of the vibrating quartz fork.

But it was the tiny frequency shift that would make a "super watch" out of quartz. With controlled application of direct currents, the previously uncontrollable frequency shift could be offset and the accuracy of a quartz watch could be improved to rival the atomic clock, but with only a fraction of the cost.

Details of new quartz-timing technology, developed at the Chinese Academy of Sciences' High Magnetic Field Laboratory in Hebei , was detailed in a paper in the international journal Sensors.

The new technology showed promise in a wide range of applications, Lu added. It could be used in any sector that required high-precision frequency control or timing measurements, from atomic-force microscopes to submarine sonar and satellite navigation systems. The United States and Britain have launched numerous projects to improve the precision of air strikes by developing chip-size atomic clocks that could installed on missiles and guided bombs.

A mainland radar expert said that it would "significantly narrow the gap" between China and Western countries if low-cost, quartz-based timepieces with high precision could be developed with the new technology.

"Western countries have erected strict trade embargos to prevent China getting the most precise clocks due to military concerns," the expert said. "The performance of a missile is significantly affected by the quality of its clock. If the missile clock can be as cheap as a quartz watch, China's missile production capability will increase significantly."

Lu's highly sensitive measurement devices recorded something that had never been reported before. With the change of direct current voltage, the frequency of quartz vibration subsequently shifted.

That meant the "wild" frequency change of quartz vibration could now be controlled and regulated by a simple and easy method, Lu said. "Applying direct current is more feasible than other methods, such as applying physical stress or changing the quartz's physical structure, which can also affect the frequency shift," he said.

The new phenomenon was not easy to detect. The frequency shift changed by the application of direct current could be as small as a few nanohertz, or one thousand-millionth of a hertz.

"We have developed some new monitoring technology and hardware in the lab, which helped us making the new observation," Lu said. "There are other timing devices, such as atomic clocks, that can measure down to the level of nanohertz, but they are all impossibly expensive.

"The quartz fork we used in the experiment was taken from an ordinary quartz watch. It can be as cheap as a few pennies. Even the most expensive forks made in Switzerland cost only a few hundred yuan each."

But Lu said the technology was still being tested in the laboratory, so it was still some way from industrial applications.

"We still need to develop some new algorithms to fully exploit the technology's potential," he said. "Without them, the timing errors cannot be fully offset."