Image transferring device for image forming equipment

摘要

An image transferring device incorporated in an image forming apparatus and capable of surely preventing a sheet from wrapping around a photoconductive element and from being incompletely separated from a transfer belt. A transfer bias and discharge are effected to prevent changes in the resistances of the transfer belt and sheet ascribable to changes in environment from translating into changes in a current to flow to the photoconductive element, and to efficiently dissipate a charge deposited on the belt. Various members constituting the device are positioned relative to one another such that the discharging effect is achievable most effectively while preventing the transfer bias from causing dielectric breakdown in any constituent part. For example, if a discharge member is spaced from a transfer electrode by L3 and if the transfer electrode is spaced from a nip portion between the transfer belt and image bearing member by a distance L2, than L3>/=L2. Additionally, if the vokage applied to the transfer electrode is VO, than L2>/=a|VO|, where a is 1.0 (mm/kv); if a distance between the nip and an upstream roller entraining the belt is L1, than L1>/=a|VO|; and if the distance between to discharge members is L4, the transfer belt has a time constant of tau , and a process speed is nu , than tau