Image forming apparatus

摘要

Voltages are applied to an image bearing member using at least three application voltage values which are larger than a discharge start voltage value and which have different magnitudes, at least one of the application voltage values having a value at which a direction of a current corresponding to the one of the application voltage values is reverse to those of currents corresponding to the other application voltage values. A relation between the application voltage value and the detection current value in a discharge area is calculated based on at least three application voltage values Vd1, Vd2, Vd3 and at least three detection current values Id1, Id2, Id3 detected by a current detection portion in relation to at least three application voltage values Vd1, Vd2, Vd3 and a voltage value V0 at which the detection current value is zero is calculated based on the relation in the discharge area.

主权项

1. An image forming apparatus comprising:
an image bearing member that bears a toner image for forming an image on a recording material; a voltage application member that applies a voltage to the image bearing member; a current detection portion that detects a current value of current flowing through the image bearing member; a potential detection portion that calculates a voltage value V0 at which a detection current value detected by the current detection portion is zero based on the application voltage value applied by the voltage application member to the image bearing member and the detection current value detected when the application voltage value is applied; and a latent image forming portion that forms on a surface of the image bearing member a potential difference for forming an electrostatic latent image for forming the toner image on the surface of the image bearing member based on the voltage value V0 calculated by the potential detection portion, wherein the voltage application member applies voltages to the image bearing member using at least three application voltage values which are larger than a discharge start voltage value, which is a voltage value at which discharge starts occurring between the image bearing member and the voltage application member, and which have different magnitudes, at least one of the three application voltage values being a value at which a direction of a current corresponding to the one of the application voltage values is reverse to those of currents corresponding to the other application voltage values, the potential detection portion calculates a relation between the application voltage value and the detection current value in a discharge area in which the discharge occurs, based on the at least three application voltage values and at least three detection current values detected by the current detection portion in relation to the at least three application voltage values, and the potential detection portion calculates the voltage value V0 according to Expression (1) based on the relation in the discharge area, in which V1 is a voltage value corresponding to a predetermined current value I1 in the discharge area and V2 is a voltage value corresponding to a current value −I1:
V0=(V1+V2)/2  (1).