Abstract: A high density detecting toner pattern is formed on a photosensitive body and a high density correction is effected by comparing a value detected by a reflection sensor with a high density reference value so as to maintain an image density at a specific level. An image density correcting section adopts a result of the preceding high density correction as the high density reference value, and compares the same with a result of a current high density correction. The image density correcting section effects the half-tone density correction only when a difference reaches or exceeds a preset difference reference value by forming a half-tone density detecting toner pattern on the photosensitive body and comparing a value detected by the reflection sensor with a half-tone reference value. Consequently, it has become possible to provide an image forming apparatus which can maintain a density output of an entire image at a specific level for any kind of images including solid, line, and half-tone, etc.

Abstract: An image forming apparatus having a carrier for carrying toner, a back electrode disposed with a space between the carrier and back electrode, a control electrode disposed between the carrier and back electrode, for forming an electric field capable of causing toner on the carrier to fly toward the back electrode from the carrier and for forming an image by causing selectively the toner to fly and adhere to a recording medium according to an image signal, and a voltage applying section for applying an oscillating voltage to the control electrode. In order to prevent resonance of the control electrode, the oscillating voltage to be applied to the control electrode is set so that minimum natural numbers m and n satisfying that m times a frequency of the oscillating voltage to be applied to the control electrode is equal to n times the characteristic vibration frequency of the control electrode are more than 10.