Patent ID: 8218400

Claim:
A clock comprising a static surface with a number of narrow apertures, each corresponding to a representation of an instant of time in a predetermined unit, and a rotatable shutter with a number of narrow apertures arranged so that light propagating through a selected one of the apertures in the rotatable shutter can also propagate through one of the apertures in the static surface so as to indicate said instant of time; wherein the number of apertures in the rotatable shutter differs from the number of apertures in the static surface; and further comprising means for rotating the rotatable shutter from a position in which said one of the apertures in the rotatable shutter is in alignment with one of the apertures in the static surface to a position in which the same one of the apertures in the rotatable shutter is in alignment with an adjacent one of the apertures in the static surface when incrementing the instant of time indicated by one unit.