A playard is movable between an open arrangement and a folded arrangement. In general, the modulator includes a polar converter that converts an input signal into an amplitude signal and a phase signal. The buried region can be made either with a development that is substantially uniform in its main direction of extension or so to present, at on part of its length, a structure of adjacent subregions in marginal continuity. The paper cartridge has a fixed front edge aligned with an inlet of the feeding path.