Patent ID: 7496305

Claim:
An image forming apparatus configured to use a two-component developer including toner and carriers, the apparatus comprising: a sensor mechanism configured to detect a toner density of the developer; an image forming mechanism provided with at least two selectable process linear speeds and configured to produce a toner image at one of the selectable process linear speeds; a toner supply controller configured to control an amount of toner to be supplied to the image forming mechanism based on the toner density detected by the sensor mechanism; a memory configured to store data of an external input voltage for adjusting a variation in an output voltage of the sensor mechanism; an estimation mechanism configured to estimate, based on the data of the external input voltage stored in the memory, a difference between respective output voltages of the sensor mechanism before and after a selection of the at least two selectable process linear speeds is changed; and a correction mechanism configured to correct the output voltage of the sensor mechanism when the selection of the at least two selectable process linear speeds is changed, based on the estimated difference between the respective output voltages of the sensor mechanism before and after the selection, as estimated by the estimation mechanism.