Image forming apparatus featuring first and second peak-to-peak charging voltages, respectively, corresponding to first and second image bearing member speeds and voltage frequencies

摘要

An image forming apparatus includes an image bearing member and a charging member in proximity or in contact with the image bearing member. A frequency of an oscillating voltage is a first frequency when a peripheral speed of the image bearing member is a first peripheral speed, and the frequency of the oscillating voltage is a second frequency when the peripheral speed of the image bearing member is a second peripheral speed. A determining device determines a first peak-to-peak voltage of the oscillating voltage corresponding to the first peripheral speed and the first frequency and a second peak-to-peak voltage of the oscillating voltage corresponding to the second peripheral speed and the second frequency, based on first, second and third alternating currents flowing in the charging member in use of the first peripheral speed and the first frequency. The determined peak-to-peak voltages are applied to the charging member.