Patent ID: 9025980
Filing Date: 2015-05-05
Classification: G03G

Abstract:
1. An image forming apparatus comprising: an image carrier; a charging unit that charges the image carrier; an exposure unit that exposes the image carrier charged by the charging unit to light and that forms an electrostatic latent image on the image carrier; a developing unit that develops the electrostatic latent image formed on the image carrier exposed by the exposure unit, so as to form a developed image; and a transfer unit that includes a bias power supply and that transfers the developed image onto a transfer body, the bias power supply including a first power supply unit, a second power supply unit, a threshold setting unit, a detector, and an output controller, the first power supply unit generating a transfer electric field for transferring the developed image onto the transfer body, the second power supply unit generating a non-transfer electric field having a polarity which is different from a polarity of the transfer electric field, the threshold setting unit having a first upper limit threshold and a second upper limit threshold, the first upper limit threshold corresponding to a first limit value for a current which is caused to flow by the first power supply unit, the second upper limit threshold corresponding to a second limit value which is larger than the first limit value in terms of an absolute value, the threshold setting unit performing a change from the first upper limit threshold to the second upper limit threshold when switching from the non-transfer electric field to the transfer electric field is performed, the detector detecting the current which is caused to flow by the first power supply unit, and the output controller controlling the first power supply unit so that a voltage output from the first power supply unit decreases in terms of an absolute value, when the current which is caused to flow by the first power supply unit becomes larger than or equal to the first limit value or larger than or equal to the second limit value in accordance with the first upper limit threshold or the second upper limit threshold set by the threshold setting unit.