The secret behind Citizen Eco-Drive technology
Producing energy from light may eventually provide sufficient power for our daytime domestic and Industrial energy needs, but for watch enthusiasts, the demands of powering quartz timepieces has long been solvable by simply harnessing the light from our star.
Eco-Drive technology
The modern variation of Eco-Drive technology has been embedded in most Citizen Watches since 1995, although earlier varieties of the technology were first seen in the 1970’s and indeed even made it in to a series of children’s watches featuring cartoon characters during the mid-1980’s.
Eco-Drive watches
Most Eco-Drive type watches are equipped with a rechargeable battery known in the trade as secondary battery. This is due to their ability to reverse their electrochemical reactions to store new power. The basic technology in use in the charging system is rarely of watches is similar to that found in domestic battery charge.
The battery type in use is constructed from a mix of titanium and lithium ions. An amorphous silicon solar cell that is located behind the dial delivers the charge to the battery. The mix of metals in the battery protects it to a large degree from ‘memory effect’ where the continual charging and discharging of the battery causes a battery to lose capacity.
Lithium batteries
Batteries removed after a 10-year lifecycle from damaged watches have still been found to be able to hold around 80% of their optimum charge. As a fully charged battery can run with no further charging for around 30 days, a loss of 20% is unlikely to have a significant effect on the day-to-day wearer of the watch.
There are many movements used in watch making and few are manufactured in house. In the case of Citizen watches the timepieces are usually fitted with Japanese made movements from the company’s Miyota subsidiary.
In common with most user-powered timepieces, these watches go in to hibernation mode when they sense that their power supply is nearing its end. This enables the timepiece to conserve its power for its internal quartz mechanism rather than exerting this power on using the hands to display the time. Before entering the power saving mode, Citizen Watches will also switch to a mode where it moves the second hand every other second to indicate the problem of low charge.
It is not just the time keeping functions that can be operated from the rechargeable battery. Many models include chronographs; with other models, offering radio controlled atomic timekeeping. In those instances a small radio receiver is found nestled inside the watch and this is used to pick up the Long Wave signals of the time signal stations. This receiver is powered from the same battery and charging system as the rest of the movement.
Through the years, Citizen Watches have tried other methods of power generation, including exploiting the thermal difference between the air temperature and the body temperature of the wearer. The watch was unpopular with consumers and later withdrawn.
With few other methods of power generation for quartz watches, the Eco-Drive will be around for a number of years yet.
http://forums.watchuseek.com/f408/secre ... 06686.html
![[rimg]http://img838.imageshack.us/img838/8385/img1749vh.jpg[/rimg]](http://imageshack.us/photo/my-images/838/img1749vh.jpg/){kind=link}
![[rimg]http://img716.imageshack.us/img716/9458/1003957g.jpg[/rimg]](http://imageshack.us/photo/my-images/716/1003957g.jpg/){kind=link}
![[rimg]http://img6.imageshack.us/img6/3981/1003948ir.jpg[/rimg]](http://imageshack.us/photo/my-images/6/1003948ir.jpg/){kind=link}
![[rimg]http://img17.imageshack.us/img17/5301/img1753yi.jpg[/rimg]](http://imageshack.us/photo/my-images/17/img1753yi.jpg/){kind=link}