US Patent 10543040 Skin treatment device

The present invention is concerned with a skin treatment device, in particular a hair removal device, having a light emission unit comprising a substrate and a plurality of first LED dies mounted on the substrate on an area of at least 0.2 cm2, in particular of at least 1 cm2, wherein the skin treatment device is arranged to activate the first LED dies to emit a treatment light pulse having a pulse length in particular in the range of between 10 ms and 300 ms and the first LED dies have a radiant flux such that a radiant fluence on the skin of a user of at least 1 J/cm2 is achieved by application of the treatment light pulse, wherein the light emission unit has at least two selectable active areas of first LED dies, where the selectable active areas have different sizes, and at least three second LED dies are mounted on the substrate at locations suitable for visibly indicating each of the selectable active areas.