DEVELOPING DEVICE AND DEVICE FOR IMAGE FORMATION Russian patent published in 2018 - IPC G03G15/09 

FIELD: images forming devices.

SUBSTANCE: present invention relates to developing device effectively used as developing unit of image forming apparatus such as copier, fax machine and printer, and image forming apparatus including developing device. Claimed group of inventions includes variants of developing device and imaging device. Developing device comprises: developer that contains toner and carrier, and developer bearing member configured to have surface carrying developer and being infinitely moving, and display latent image on the surface of hidden image carrier of element by supplying developer toner to hidden image in developing area where developer bearing member faces latent image bearing member, carrier contains fine particles, and value of X in volume resistivity R (=10^x) (Ω • cm) of carrier is from 11.5 to 16.0, wherein developer bearing member comprises: magnetic field generating unit that comprises plurality of magnetic poles; and developing sleeve having cylindrical shape surrounding magnetic field generating unit and configured, to carry developer on outer circumferential surface of cylindrical shape by magnetic force of magnetic field generating unit and to perform movement of surface by rotation relative to body of developing device, wherein developing device comprises voltage applying unit to developing sleeve configured to apply voltage that includes alternating current component to developing sleeve, and wherein in application unit of voltage to developing sleeve, bias voltage in which AC component is superimposed on DC component has voltage swing ratio represented by formula below, between its maximum value (called Vpp1) and its minimum value (called Vpp2) on side of usual polarity of toner charge, |Vpp1-Vpp2|≤1,500 V.

EFFECT: technical result is to provide elimination cyclic changes in density by means of AC bias voltage for development, can reduce effects of bias voltage of positive side resulting from use of AC bias for development, and can prevent deterioration in development performance over long period.

12 cl, 6 tbl, 21 dwg