Patent ID: 8731420

Claim:
An image forming apparatus, comprising: an image carrier configured to carry a toner image thereon; a transferer configured to apply a bias that is controlled in a constant-current control method to a transfer medium to form a transfer electric field in a transfer area in which the image carrier and the transfer medium face each other to transfer the toner image onto the transfer medium; a constant-current source configured to apply an electrical current to the transferer; an electrical characteristic detector configured to detect an electrical characteristic value corresponding to a resistance in a conductor connecting the constant-current source to the transferer and through which the electrical current flows to the transferer; an environment detector configured to detect an environmental condition inside the image forming apparatus; a first corrector configured to correct a value of the electrical current based on a detection result produced by the electrical characteristic detector and a predetermined threshold; a second corrector configured to correct the value of the electrical current based on a detection result produced by the environment detector; and a third corrector configured to set the threshold based on the detection result produced by the environment detector, wherein when correction by the first corrector and correction by the second corrector are performed simultaneously, the first corrector corrects the value of the electrical current using the threshold set by the third corrector.