Abstract: An image developer using a one-component developer, Including a developing roller visualizing an electrostatic latent image formed on an image bearer with a pulverized toner; and a feed roller feeding the pulverized toner to the developing roller while contacting thereto, wherein the pulverized toner includes a parent toner; a wax; and an external additive comprising an additive having a number-average particle diameter of from 20 to 60 nm and adhering to the surface of the parent toner at an adherence strength of from 50 to 70%, and wherein the following relationships (1) to (3) are satisfied: 4.70<Log10 R<5.70??(1) 8.00<Log10 Z<10.70??(2) ?6.25*Log10 R+37.5<Log10 Z<?6.25*Log10 R+45.6??(3) wherein R represents a resistivity of the developing roller and Z represents an impedance of the pulverized toner.

Abstract: An image forming apparatus including a plurality of developing devices each having a plurality of guide parts on both lateral sides, a frame body having a plurality of guide members configured to receive the guide parts of the developing devices, a front door for receiving and removing the developing devices from the frame body, and a position regulating member having a plurality of regulating parts and a connecting part configured to connect each regulating part, the position regulating member having an L-shape to regulate movement of the plurality of developing devices, each end of the regulating part configured to be placed between the guide part and the guide member, and the connecting part configured to be placed between the developing devices and the front door.

Abstract: A method and apparatus for correcting a color registration are provided for improving the quality of images of an image forming apparatus. A surface condition is estimated of an intermediate transfer belt used to correct a color registration. A determination is made as to whether an abnormal section exists on the intermediate transfer belt. Location information is stored regarding the abnormal section on the intermediate transfer belt, if the abnormal section exists. A mark for color registration correction is formed on a normal section, other than the abnormal section. The color registration is corrected using the mark. Accordingly, if a partially inferior section appears in the intermediate transfer belt and a mark is not normally formed, the color registration is successfully corrected.

Abstract: A developing unit has a voltage-applicator (80) to apply a developing bias voltage to a developing roller (72). The voltage-applicator (80) applies the developing bias voltage for a first duration to apply an AC voltage having a rectangular waveform, and a second duration to stop applying the AC voltage. The AC voltage has a duty ratio of 50% or more in a direction for causing toner to develop an electrostatic latent image. The number of cycles of the AC voltage in the first duration is two or more, and the AC voltage has a voltage in a direction for pulling the toner back to the developing roller, just before transition to the second duration. The developing unit suppresses occurrence of image unevenness due to a fluctuation in developing gap. Thus, an image forming apparatus equipped with the developing unit forms a high-quality image while suppressing image unevenness.