Abstract: A light unit for use in lighted sign assemblies has a housing with a rear wall, upstanding opposed side walls, and shield elements extending inwardly from adjacent the upper ends of the side walls. Light arrays extending along the side walls have light emitting diodes disposed in spaced relationship above the rear wall and below the shield elements, and a diffuser extends across the housing above the shield elements. The rear wall is configured to reflect light emitted from the diodes relatively uniformly across the diffuser which further contributes to relative uniform transmission of light therethrough. The power supply may include a circuit to transform alternating current line voltage into a reduced direct current voltage for the diodes, and the power supply may also provide direct current to the diodes from a battery power source when power is interrupted.