Thermo transfer printer

In a thermo transfer printer having a printing head having a plurality of switch cells arranged in a two-dimensional field and controlled by the printing information, means for directing energy from energy sources via the switch elements onto respective matrix dots arranged in a grid which lie in a plane of an ink layer of a band-shaped carrier to locally melt due to energy absorption specific portions of the ink layer for transfer to a print medium pressed thereagainst, the improvements comprising the carrier being coated with a thermo plastic ink and being constructed as a circulating endless band, a heated inking means for regenerating a layer of ink on the band, the printing head in combination with a high energy radiation source being constructed as an optical character generator in which every switch cell comprises an optical switch element composed of a transparent ferro-electric ceramic substrate composed of lead zirconate titanate doped with lanthanum and has transparent surface electrodes for applying a pulse-shaped control voltage, each cell including a first optical element and a second optical element, said first optical element being positioned in the beam path preceding the optical switch element to couple a part of the energy output by a radiation source into the switch element as a parallel, expanded beam and the second optical element being arranged in the beam path following the optical switch element and at a predetermined distance from the carrier so that the second element focuses a received part of the beam into the allocated matrix dot.