Automatic cleaning method for electrifier, and image forming apparatus

An image forming apparatus equipped with an electrifier which performs an electrifying operation for the purpose of forming an image on a medium, said apparatus comprising:

• a cleaning member for cleaning said electrifier;
• a drive mechanism for moving said cleaning member to clean said electrifier;
• an electrification time measuring section, initialized upon completion of each cleaning of said electrifier, for measuring an electrification time after the cleaning of said electrifier;
• a medium detecting section for discriminating whether or not a medium is located at an image forming station where an image is formed on the medium;
• and
• a control section for controlling said drive mechanism to move said cleaning member so as to clean said electrifier when said medium detecting section discriminates the absence of the medium at the image forming station after said electrification time measured by said electrification time measuring section reaches a first predetermined times,
• said control section being operative to render said cleaning member to clean said electrifier when it is detected that an image forming operation of said apparatus is stopped, after said electrification time reaches a second predetermined time subsequent to said first predetermined time without any detection of the absence of said medium by said medium detecting section, and
• said control section being operative, if said electrification time reaches a third predetermined time subsequent to said second predetermined time with said image forming operation kept continuing, to temporarily stop said image forming operation before rendering said cleaning member to clean said electrifier.

An image forming apparatus which forms an image on an image forming drum by electrifying with an electrifier and transfers the image onto a medium, and which has an electric potential control function to control an electrification potential of said electrifier in conformity to a target value in accordance with a surface electric potential of said image forming drum, said apparatus comprising:

• a cleaning member for cleaning said electrifier;
• a drive mechanism for moving said cleaning member to clean said electrifier;
• and
• a control section for controlling said drive mechanism to move said cleaning member so as to clean said electrifier when a difference between said target electrification potential, which is determined by said electric potential control function, and a predetermined reference potential exceeds a first predetermined value.

An image forming apparatus including an electrifier which performs an electrifying operation for the purpose of forming an image on a medium, said apparatus comprising:

• a cleaning member, located in an electrifier unit in which said electrifier is disposed for cleaning said electrifier;
• a drive mechanism, mounted on a frame of said image forming apparatus, for moving said cleaning member to clean said electrifier;
• and
• a joining unit attached to said drive mechanism at a position in which said drive mechanism moves said cleaning member, said joining unit being located to selectively assume a connecting position connecting to said cleaning member to prevent said cleaning member from being removed from said drive mechanism or a releasing position releasing from said cleaning member to allow said cleaning member to be removed from said drive mechanism,
• wherein said joining unit is locatable to assume said releasing position so that said cleaning member is removed from both the drive mechanism and said joining unit for replacement of said electrifier unit together with said cleaning member and said electrifier.