Abstract: An electrophotographic printing device is provided with an exposure unit comprising light-emitting diodes which are light sources and means for transmitting the light beams emitted from the light-emitting diodes and converging or focusing them like converging lenses, whereby electrostatic latent images of characters and the like are formed on the surface of a photosensitive member.

Abstract: A printer head assembly for use in high speed printers of the dot-matrix type. The assembly includes a plurality of solenoids affixed to a bevelled rear wall of a bracket and arranged in such a manner that they are located equidistantly from one another on the circumference of the rear wall of the bracket and arranged at different heights in a vertical plane, and print wires of the same number as the solenoids extending diagonally inwardly from the associated solenoids at the same angle therewith and ultimately introduced into guide apertures formed in a lip guide so as to lie along an imaginary straight line in very closely spaced relationship. The print wires are each inserted in a conduit formed of material of a low coefficient of friction in the region between the bracket having a conduit support and a place slightly posterior to the entrance to the lip guide.