Patent ID: 7796902

Claim:
An image forming apparatus, comprising: a charge unit to charge a surface of a latent image carrier; an exposure unit to irradiate the charged surface of a latent image carrier using a light beam to form a latent image on the latent image carrier, the latent image being formed as a test pattern; an exposure voltage detector to detect a potential of the latent image formed on the latent image carrier; a development unit, including developer carrier carrying toner, to develop the latent image as a toner image by supplying the toner to the latent image on the latent image carrier using a potential difference between the latent image carrier and the developer carrier; a concentration detector to detect an image concentration of the test pattern developed as the toner image; an exposure power controller controlling an exposure power emitted by the exposure unit; an exposure ratio controller controlling an exposure duty per unit area exposed by the exposure unit; a charging voltage controller controlling a charge bias voltage applied to the charge unit to set a surface potential of the latent image carrier at a given charging voltage after a charging process; a development bias voltage controller controlling a development bias voltage, which is a surface potential of the developer carrier; and an image forming condition adjustment controller adjusting an image forming condition based on detection results of the exposure voltage detector and the concentration detector, wherein the charging voltage controller changes the charging voltage in two levels or more, the exposure power controller changes the exposure power in three levels or more, and the exposure ratio controller changes the exposure duty per unit area in two levels or more, wherein the test pattern is formed under image forming conditions using combinations set by 2×3×2 levels or more, to obtain a suitable combination of the charging voltage, the exposure power, and the development bias voltage.