Image forming apparatus

An image forming apparatus comprising:

• a rotatable photosensitive member;
• a charging device configured to charge a surface of the photosensitive member at a charging position;
• a charge bias applying portion configured to apply a charging bias, for charging the surface of the photosensitive member, to the charging device;
• a transfer device configured to transfer toner to a transferred member from the surface of the photosensitive member at a transfer position;
• a transfer bias applying portion configured to apply a transfer bias, for transferring the toner to the transferred member from the photosensitive member, to the transfer device;
• a cleaning blade in contact with the surface of the photosensitive member at a blade cleaning position downstream of the transfer position and upstream of the charging position with respect to a rotational direction of the photosensitive member and configured to remove the toner from the surface of the photosensitive member;
• a rotatable brush in contact with the surface of the photosensitive member at a brush cleaning position downstream of the transfer position and upstream of the blade cleaning position with respect to the rotational direction of the photosensitive member and configured to remove the toner from the surface of the photosensitive member;
• a cleaning bias applying portion configured to apply a cleaning bias to the brush;
• a detecting portion configured to detect a current flowing through the brush or a voltage applied to the brush;
• and
• a control portion, during non-image formation, configured to cause the cleaning bias applying portion to apply a plurality of test biases to the brush and to perform a setting operation in which a voltage to be applied by the cleaning bias applying portion is set based on a detecting result by the detecting portion when the plurality of test biases are applied.