Patent ID: 7756429

Claim:
An image forming apparatus including at least one image forming section, wherein the image forming section includes an image bearing body, a charging unit that charges an area on a surface of the image bearing body, and a developing unit that supplies a developer material to the charged area to form a developer image on the image bearing body, the image forming apparatus comprising: a transporting unit onto which the developer image is transferred from the image bearing body; a detector that detects a density of the developer image on said transporting unit; and a voltage controller that provides a test charging voltage for forming the developer image on the image bearing body and a normal charging voltage for performing a normal printing operation, to the charging unit; wherein the voltage controller is configured to perform a charging voltage correcting operation in which said voltage controller provides the test charging voltage to the charging unit, and then determine the normal charging voltage based on the density of the developer image detected by said detector; wherein the test charging voltage is variable in absolute voltage value stepwise from highest to lowest, and the developer image varies in density in accordance with a corresponding voltage value of the test charging voltage; wherein said voltage controller is configured to set the normal charging voltage based on a voltage value of the test charging voltage that causes the density to be greater than the reference value when the density detected by said detector is greater than a reference value; wherein said detector is configured to detect the density of the developer image formed by the corresponding voltage value of the test charging voltage before a next developer image is formed; and wherein the voltage controller is configured to terminate providing the test charging voltage to the charging unit when the density detected by said detector is greater than the reference value.