What is the ideal source of power for a watch?
CITIZEN created the world's first light-powered analogue quartz watch in 1976.
We named the technology Eco-Drive in acknowledgement of its eco-friendly origins.
It converts any kind of light into energy to power a watch and stores the surplus on a power cell.
On a full charge, an Eco-Drive watch runs for months even in darkness with no need for regular battery replacement.
As a light-power pioneer, we continue exploring new possibilities.
In a first for a watchmaker, Eco-Drive products obtained Eco Mark certification, a label managed by the Japan Environment Association (JEA), in recognition of their contribution to environmental sustainability in 1996. Eco-Drive went on to be awarded a Gold Prize at the JEA's Eco Mark Awards 2014, a first in the watch business.
Once upon a time, everyone accepted that quartz watches had to have their batteries replaced at regular intervals. But the advent of Eco-Drive overturned the conventional thinking. Eco-Drive is a light-powered technology that drives watches by capturing light and converting it into energy using an inbuilt solar cell.
Suddenly the hassle of replacing batteries was a thing of the past.
Eco-Drive is designed to charge from ordinary everyday light sources like indoor fluorescent lighting and desk lights. You can go about your everyday life confident that your watch will never stop.
* To get the most out of your watch, set aside about five or six hours per month to charge it in sunlight.
Do you need light to generate power for your watch all the time? Not with Eco-Drive. A single full charge is enough to keep Eco-Drive working for over six months in total darkness. Indeed, some models equipped with power save function can run for as long as seven years.
* Some models run for less than six months.
Solar cells absorb light and convert it into energy. With Eco-Drive, we use different solar cells for different models to increase the range of designs we can offer.
As the name suggests, this is the most commonly used solar cell in our watches. It sits directly beneath the dial. Due to its excellent power-generation capabilities, it is used in many of our advanced-function models.
This ring-shaped solar cell sits above the dial, encircling it. With a ring solar cell, there is no need for the dial to be translucent, allowing for greater latitude in dial design.
How can we get the most out of the energy we generate from light? CITIZEN's relentless focus on reducing energy consumption has driven the creation of advanced functions and other value-added innovations. We redesigned the circuits and programming of the integrated circuit (IC) and optimised the motor with numerous subtle tweaks to achieve better energy performance.
CITIZEN was the first company in the world to build a Light-Level Indicator into its analogue quartz watches. The indicator detects the intensity of light striking the dial and displays the current level of electricity generation, allowing the wearer to gauge the amount of power being generated at any given moment.
The first oil shock of 1973 raised global awareness and interest in alternative sources of clean energy. CITIZEN responded to the challenge by starting to develop watches driven by a completely new energy source: light.
In the 1970s, battery-driven quartz watches were very much the mainstream in Japan. Their shortcomings, however, included the hassle of having to replace and dispose of dead batteries. The desire to solve these problems and come up with something new and better was what inspired CITIZEN to develop a light-powered watch.
In the mid-1970s, solar cells were bulky and prone to crack. Incorporating them into something so small as a watch was far from easy. But after much experimentation and not a few dead ends, CITIZEN unveiled a design prototype of a light powered analogue quartz watch in 1974. Two years later in 1976, we unveiled the CRYSTRON SOLAR CELL, the world's first commercial light-powered analogue quartz watch.
When the CRYSTRON SOLAR CELL debuted in the 1970s, neither the solar cell (which generated energy) nor the power cell (which stored it) had sufficient generating capacity or battery life for the watch to become a realistic part of anyone's everyday life. The engineers at CITIZEN were acutely conscious of these limitations.
But as the 1980s got under way, thinner solar cells capable of generating power from indoor light and power cells with longer battery life appeared. Thanks to these advances, CITIZEN's light-powered watches made a major leap forward. We made a series of improvements and innovations with a view to creating "a watch that never stops and integrates easily into everyday life." In 1986, we debuted a model that could keep running for eight days (roughly 200 hours) on a single charge.
In 1995, through the addition of a lithium-ion power cell, we were able to develop a model with a running time of six months on a single full charge. This was a landmark achievement that led directly to Eco-Drive of the present day.
* Model shown is from 1993
CITIZEN's proprietary light-powered technology Eco-Drive is an exceptional technological achievement that also reflects our concern for the natural environment. The name and logo display our commitment to building a brand for people all over the world.
light-powered analogue quartz
Light-powered analogue quartz watch
which absorbs light
from the sides of the case
analogue quartz watch
World's thinnest light-powered
with world time function
light-powered analogue quartz watch
In line with its "Better Starts Now" brand statement, CITIZEN has developed Eco-Drive watches that are smaller, thinner, lighter and have more functions. In fact, we have produced a whole series of world firsts. With our focus on functionality, convenience and beauty, CITIZEN will keep innovating and improving in the years ahead.
* Some models are no longer in production or are not available in certain countries.