The invention relates to a parallel inverter system, in which each inverter includes a synchronized square wave generator, a voltage given generator, a voltage regulating unit and a power amplifier unit. One or more watermarks can be inserted into one or more of the color planes. The ultraphobic surfaces of the tray carrier cause liquids that may come in contact with the surface, such as may be used in cleaning, to quickly and easily \u201croll off\u201d without leaving a liquid film or substantial quantity of liquid droplets.