Dial markings for clock face - are formed by overlying rasters providing interference pattern

摘要

The dial markings (6) for a clock face are ach formed as a transparent raster marked on the clock face and a further raster or reflective structure marked on a disc (5) positioned in front or behind the clock face. The disc (5) is movable relative to the clock face, so that interference between the two overlying rasters causes the dial markings (6) to appear to move or glimmer. The disc (5) may be coupled for rotation with the clock seconds hand (4) and is pref. of transparent glass, with spaced radial raster lines around its peripheral edge.