Thermoelectric printing device esp. typewriter - has laser light source projecting onto charged ribbon which is electrostatically pulled towards paper

摘要

A thermoelectric printing device for producing symbols on a recording sheet, typically ordinary typing paper, uses a colour carrying strip (typewriter ribbon) composed of a coloured layer and support strip, this ribbon contains a dielectric which can be permanently polarised by a charging device; the light source used for projecting a beam through a template onto this ribbon is a laser diode. The source softens the coloured layer (ink) on the ribbon, while simultaneously or just afterwards a temporarily energised electrode pulls the ribbon, due to its charge, onto the paper. This arrangement operates noiselessly and, due to the use of a laser as light source, does not require any shielding from ordinary light. The dielectric may comprise either a thermoplastic, dielectric, permanently polarisable material such as carnauba wax in the ink layer, or polyethylene terephthalate in the support ribbon.