Image forming apparatus having control means to reduce an amount of the water vapor produced in a main assembly thereof or detecting unit configured to detect a value relating to an amount of water vapor in the main assembly

摘要

An image forming apparatus includes: a main assembly; an image bearing member; a transfer member cooperative with the image bearing member to form a transfer portion; a voltage source for applying a voltage to the transfer member; a heater for heating the sheet having a transferred toner image; a detector for detecting a value relating to an amount of water vapor in the main assembly; and a control unit for executing a moisture removing control for reducing an amount of water vapor produced in the main assembly, by heating the sheet by the heater on the basis of the amount of change, caused by passage of the sheet in an image forming operation, of the value detected by the detector.

主权项

1. An image forming apparatus comprising:
a main assembly; an image bearing member configured to carry a toner image; a transfer member cooperative with said image bearing member to form a transfer portion to transfer a toner image onto a recording material passing through said transfer portion; a transferring voltage source configured to apply a voltage to said transfer member; a heating unit configured to heat the recording material having a transferred toner image; a detecting unit configured to detect a value relating to the amount of water vapor in said main assembly; a fan configured to adjust a flow rate in said main assembly, and a control unit configured to control a humidity decreasing operation for decreasing the amount of vapor produced in said main assembly; wherein when said control unit increases the rotational speed of said fan to effect the humidity decreasing operation on the basis of the amount of change of the value detected by said detecting unit, the value corresponding to the amount of the vapor produced by heating the recording material by said heating unit.