Electrostatic printing apparatus including structure for delivering developer or toner particles to a printhead forming an integral part of the printing device. Alternatively, the toner particles can be delivered to a charge retentive surface containing latent images. The developer or toner delivery...http://www.google.de/patents/US4743926?utm_source=gb-gplus-sharePatent US4743926 - Direct electrostatic printing apparatus and toner/developer delivery system therefor
