Printers such as inkjet printers typically employ some type of platen to support the print medium during the printing process. One type of printer uses a rotating drum as the platen. The print medium, e.g. a sheet of paper, is secured to the periphery of the drum by a vacuum (or other attachment means, such as adhesive tape), and the drum rotated relative to a print cartridge carriage. The carriage holds one or more print cartridges, each having a printhead for ejecting droplets of ink in a controlled manner. The carriage is moved in two alternate ways as the drum is rotating. One way is to incrementally step or move the carriage from one swath to the next. The other is a continuous, very slow movement, so that the printhead moves in a spiral relative to the paper surface.
There can be a need to place an electronics package within the drum. This can be used for various purposes, e.g. to drive vacuum actuators, media clamps, drum temperature control for drum platen heaters, and drum temperature sensors. The printer will typically include a controller mounted in a fixed location relative to the printer chassis. However, the need to provide a communication link between the stationary controller and the electronics package located in a rotating drum presents problems. This invention provides a solution to these problems.