Image forming apparatus and control method thereof

An image forming apparatus comprising:

• a plurality of photoconductor elements arranged in a movement direction of an intermediate transfer body, and corresponding to a plurality of colors, the plurality of colors including a first color and remaining colors;
• a light scanner which irradiates light onto the plurality of photoconductor elements to form electrostatic latent images;
• a developer which supplies toner to the plurality of photoconductor elements to form toner images on the plurality of photoconductor elements;
• the intermediate transfer body to which the toner images formed on the plurality of photoconductor elements are transferred;
• a first sensor, which is arranged between a first photoconductor element and a second photoconductor element among the plurality of photoconductor elements, and which senses the toner images transferred to the intermediate transfer body;
• a final sensor, which is arranged after a final photoconductor element among the plurality of photoconductor elements, and which senses the toner images transferred to the intermediate transfer body;
• and
• a controller which calculates fixed errors of the remaining colors, with respect to the first color corresponding to the first photoconductor element, based on output values of the final sensor before printing, which calculates a variable error based on an output value of the first sensor during printing, and which adjusts a scanning time of at least one color of the remaining colors in real time in consideration of the fixed errors and the variable error.