A NUMERIC TIME INDICATION FOR DAY AND NIGHT.
Within a fraction of a second, the LANGE ZEITWERK switches from one minute to the next. The grand jump occurs at the top of the hour, when all three numeral discs instantaneously advance at the same time. To make the exciting time event visible in the dark, Lange’s master watchmakers performed intensive research and development. The result is a world debut: the first watch with a luminous jumping numerals display.
TAPPING LIGHT IN THE DARK.
In conventional watches that display the time at night, daylight is needed to “charge” the superposed phosphorescent hands and hour markers. However, the numerals of the LANGE ZEITWERK are mostly hidden in the dark beneath the dial. To make them glow at night, it was necessary to find a way to allow sunlight into the interior of the watch. The original solid-silver dial had to be replaced with a light-permeable one.
FUNCTIONAL PRINCIPLE OF SUNGLASSES REVERSED.
However, a totally transparent dial that fully exposes the movement would have negatively affected the unique clarity of the display. Lange’s master watchmakers took advantage of the principle that the phosphorescent coating of the numerals is charged for the greater part by high-energy UV rays. Hence, the sapphire crystal is coated with a substance that mainly allows UV light to pass through, but blocks most of the visible light – as opposed to sunglass lenses that block UV light and allow the passage of visible light. The attentive observer will just barely be able to discern the three numeral discs through the dial – an enigmatic design element of this watch.
