Patent ID: 8554094

Claim:
An image forming apparatus comprising: a photoconductor operable to rotate; a latent image forming portion configured to electrically charge the photoconductor and forms an electrostatic latent image on a surface of the photoconductor; an image processing portion configured to generate image data or pattern data; a developer configured to develop the electrostatic latent image of the image data or the pattern data using toner; a transferred body configured to have a surface onto which a toner image on the photoconductor is transferred; a sensor configured to detect an image density of the toner image according to the amount of toner attached to the surface, and have a sensor characteristic in which a sensor output substantially monotonously decreases according to an increase in the amount of toner; a nonlinear amplifier configured to have a nonlinear amplification characteristic having one or more inflection points, and enlarge and correct a value read by the sensor in a range where the sensor output monotonously decreases with respect to the amount of toner by amplification; and an image quality control portion configured to control forming conditions of the electrostatic latent image by the latent image forming portion, using a correction value of a variation amount of the value read by the sensor, the value being output from the nonlinear amplifier, at a side where the amount of toner is large in the range.