Eco-Drive
Powered by light
Eco-Drive is a proprietary CITIZEN technology that converts any kind of light, from bright sunshine to dim indoor lighting, into the energy necessary to power a watch. It runs for over six months off a single full charge. CITIZEN released the world's first light-powered analogue watch in 1976. As a pioneer, we continue to push the boundaries of the technology today.
Battery replacement?
Simply not necessary
Once upon a time, everyone just accepted that quartz watches needed regular battery replacement. At least, that was the case until light-powered technology came along to overthrow the conventional wisdom. Eco-Drive makes regular battery replacement unnecessary. There's no need to worry about your battery running out when you can charge your watch simply by pointing it at the light.
Any kind of light will do
Eco-Drive is designed to run on any kind of light, including
overhead lighting or desk lamps. You can go about your life
confident that your watch is not going to suddenly stop in
the course of your day.
*For best results, we recommend exposing the
watch to five or six hours of direct sunlight per
month.
Keeps Running
for
over
six months
Does my Eco-Drive watch need light to keep running? No, it
does not—because Eco-Drive can run for more than six months
on a single full charge.* The technology continues to
advance. There are now several Eco-Drive models with power
save function that have a running time of seven years.
Another model capable of running 365 days off a single
charge came out in 2023.
* Some models run for less than six
months.
Winning Eco Mark certification
In a first for a Japanese watchmaker, in 1996 Eco-Drive was awarded Eco Mark Certification in recognition of its contribution to sustainability. In another first for the watch industry, Eco-Drive went on to be awarded a Gold Prize at the 2014 Eco Mark Awards in recognition of its role in raising consumer awareness of environmental issues through watch sales.
About Eco-Drive
Explore the technologies
that go into Eco-Drive.
It's a miniature power station for watches
The Mechanism: “CONVERT: STORE: DRIVE.”
How Eco-Drive Works
Translucent but not transparent.
The finer points of Eco-Drive dials
In many Eco-Drive models, the solar cell sits underneath the dial. Eco-Drive, however, cannot generate electricity with an opaque dial because no light can get through to the solar cell. If, by contrast, the dial is over-transparent, the solar cell beneath becomes visible, which is not visually appealing. That's the reason we are so focused on developing dials that are translucent (in order to let light through) but not transparent (in order to conceal the solar cell). The goal of the dials we make is to generate power efficiently even from a small amount of light.
Two kinds of solar cells.
Many possible designs
We can create a wide variety of watch designs by using the type of solar cell that best corresponds to the character of the particular model.
Standard Solar
The solar cell is placed under the dial. Because a large quantity of light reaches the solar cell, standard solar has high conversion efficiency. That's the reason standard solar is used for so many models, including the more power-intensive ones like Satellite Wave GPS.
Ring Solar
A ring-shaped solar cell sits on the circumference of the dial. Because there is no need for the dial to be translucent, Ring Solar allows for greater latitude in dial materials and design.
Technology to make light power last longer
The amount of energy that can be generated from light is necessarily quite modest. In consequence, it is crucial to make that energy last as long as possible. CITIZEN is always refining and upgrading the IC programming, circuits and motors to reduce power consumption, particularly when it comes to models with advanced, power-intensive functions. The story of Eco-Drive's progress is a story of ever-lower power consumption.
POWER SAVE FUNCTION Your watch sleeps in the dark
The power save function is activated when the watch has not
been exposed to light for a certain length of time. The
hands stop moving to enable the system to save power. Even
when the power save function is in operation, the watch
continues to tell the correct time internally. Power
generation resumes as soon as the watch is exposed to light
and the hands start to move again.
*Not all models are equipped with the power
save function.
INSUFFICIENT CHARGE WARNING Advance notice of power running low
The insufficient charge warning function is activated when the watch is running low on charge. The second hand starts moving in two-second intervals to alert you to the need to charge the watch. The watch will nonetheless continue to tell the correct time. As soon as the watch is adequately charged, the second hand will resume moving at normal one-second intervals.
New materials for a range of handsome dials
CITIZEN has spent decades seeking to find dial materials that look fabulous while also letting through the light Eco-Drive needs. We have created a variety of characterful and expressive dials from materials including all-natural washi (Japanese paper); sturdy, beautiful sapphire glass just 150 micrometres thick; sumptuous mother of pearl; and structural inks with colours that change depending on the viewing angle. We are committed to exploring more exciting new possibilities for dial design in the future.
The Eco-Drive Story
Bold vision. Exciting innovations.
A new power source for watches
After the 1973 Oil Crisis, there was much discussion about the need to develop new sources of energy. Getting to grips with this problem in its role as a watchmaker, CITIZEN eventually launched the original light-powered watch: a watch that was powered by sunlight, an entirely new source of power in horology.
Battery-powered quartz watches established themselves as the mainstream watch type in 1970s Japan. However, they were not without their drawbacks. The need to change the batteries was annoying, while the old batteries just ended up in the garbage. Determined to solve these problems, CITIZEN set about developing a light-powered watch.
The world's first light-powered analogue watch.
A CITIZEN creation
Solar cells in the 1970s were thick and prone to crack, making them extremely difficult to incorporate into something as small as a watch. After a long process of trial and error, CITIZEN had a prototype ready by 1974. It was two years after that in 1976 that we released CRYSTRON SOLAR CELL, the world's first light-powered analogue watch.
An everyday watch that just keeps running
In the 1970s, when the CRYSTRON SOLAR CELL was released, neither the generative power of solar cells nor the durability of the secondary batteries where the energy was stored were adequate for a watch that could be a practical part of normal, everyday life. The engineers at CITIZEN were more aware of these technological limitations than anyone.
Enter the 1980s and CITIZEN light-powered watches progressed by leaps and bounds thanks to the appearance of thinner solar cells better suited to generating power from indoor lighting and secondary batteries with a longer battery life. While taking advantage of these new technologies, CITIZEN also made a whole series of incremental improvements, aiming to create a “watch that will not stop and can be a viable part of people's everyday lives.” Finally, in 1986, we released a model with a running time of 200 hours—more than eight days—on a full charge. It was another world first.
Targeting a running time of six months plus
If we can only extend the running time, even by a minute… We responded to that challenge by developing a model that could run for six months on a single full charge thanks to the use of a lithium secondary battery. This milestone model is a direct precursor of the Eco-Drive models of today.
One year earlier in 1994, we had created the name
“Eco-Drive” to differentiate our light-powered technology
from the technologies of other watch companies. The name
does more than just express the idea of powering a watch
using light for energy. The “Eco” element has clear
connotations of environment-friendliness, while “Drive”
implies that making use of the technology will help propel
individual users' eco-consciousness to a higher level.
Thinner. Smaller.
More functions
Continuous improvements to IC programming, motors and other
elements made the creation of a variety of designs possible.
Eco-Drive was no longer an isolated category. It had evolved
into a core CITIZEN technology that was used in a wide range
of watches, including Radio-Controlled, diver's watches,
chronographs and small, elegant women's watches.
In 2016, Eco-Drive's 40th anniversary, we released Eco-Drive
One. Eco-Drive One is fitted with the Caliber 8826, the
world's thinnest light-powered analogue movement at just
1.00mm thick.*
* For an analogue light-powered movement. As
of November 2023, according to Citizen Watch Co., Ltd.
research.
Achieving a 365-day running time
CITIZEN developed the Caliber E365, a light-powered movement capable of running for 365 days on a single full charge with the aim of “spearheading the new tomorrow.” The release of Eco-Drive 365, a model featuring this movement, represented a new and important chapter in Eco-Drive's history.
NOW
The innovation goes on
Inspired by our “Better Starts Now” philosophy, CITIZEN has created a whole series of Eco-Drive world firsts—ever more handsome light-powered watches that are smaller, thinner, lighter and offer more functions. Our commitment to offering higher levels of functionality, user-friendliness and aesthetics is as strong as ever. CITIZEN intends to keep innovating and improving Eco-Drive technology in the years ahead.
Some featured models are no longer in production or are unavailable outside Japan