Method and device for displaying a moon image cycle, in particular for a watch

摘要

In order to display images true to the real appearance of the moon during a lunation, particularly in a watch, there is provided a rotating indicator disc (8) arranged behind a circular aperture of a dial and comprising an annular region (20) subdivided into alternatively light (21–25) and dark (26–30) fields by lines of separation (31–40) having different shapes, which can appear in succession in the aperture. The drive means impart primary movements on the indicator disc (8), each of which is large enough to replace one of the lines of separation by another in the aperture, and smaller secondary movements, to produce small movements of the line of separation inside the aperture. This allows a new image of the moon to be given every day, true to reality, with a restricted number of light and dark fields on the indicator disc and a particularly large aperture in relation to the size of the dial. A version with electric driving is disclosed and a version driven by a mechanical watch movement.