Electric motor drive for variable sign prism positioner - uses roller pair mounted in two slots on rigid prism mounting

摘要

An electric motor drive mechanism is for positioning a prism within a variable illuminated sign, typically for use in traffic control, in which the prism position affects the displayed sign. The drive allows the prism to be positioned in one of many discrete positions accurately and rapidly. A geared electric motor drives a cog and chain pair which in turn drives a toothed wheel attached to a pair of rollers mounted at the circumference of the wheel parallel to its axis. These rollers engage in two slots in a rigid body on which the prism is mounted by an arrangement of bolts. Prisms with many different faces may be accommodated.