Eco-Drive

Eco-Drive is Citizen's own name for its light-powered quartz watches, not a generic description of solar watches. Citizen states that "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". The energy is held in a secondary, rechargeable cell (Citizen's page names "a lithium secondary battery") and Citizen states that "Eco-Drive makes regular battery replacement unnecessary".

Every performance figure attached to Eco-Drive is Citizen's own stated figure. Citizen states that an Eco-Drive watch "runs for over six months off a single full charge", and its support pages put this as continuing "even in total darkness". Citizen further states that "there are now several Eco-Drive models with power save function that have a running time of seven years". No independent testing body publishes a rating for any of these numbers, and none was found for this entry.

Citizen dates the technology to its own earlier work: "in 1976, we invented the world's first light-powered analog quartz watch that runs using only light as a power source." That priority is not only Citizen's claim: the Seiko Museum separately records that "in 1976, Citizen launched the Crystron Solar Cell, the world's first analog solar-powered watch".

What this Codex does not do: cite a trademark register. Eco-Drive is treated here as Citizen's mark because Citizen describes it on its own site as "proprietary CITIZEN technology"; no register entry at WIPO, EUIPO or the USPTO was opened from this session, so no registration number or jurisdiction is stated.