1. Field of the Invention
The present general inventive concept relates to an image forming apparatus to print a color image onto a printing medium.
2. Description of the Related Art
An image forming apparatus such as a printer, copier, facsimile or multi-function unit that integrates the above functions has a main function of printing an image onto a printing medium. A color image forming apparatus is also available, which prints images in multiple colors.
A color image forming apparatus generally includes a plurality of photosensitive media to form electrostatic latent images for color printing, a plurality of developing units to develop the electrostatic latent images into developed images in corresponding colors, a transfer unit to receive the developed color images on one another and transfer a composite image onto a printing medium, a fusing unit to fix the transferred image to the printing medium, and a discharge unit to discharge the printing medium outside.
The color image forming apparatus carries out auto color registration (ACR) to align images of each color exactly to intended locations. By the ACR, it is checked whether the color images are correctly printed on the printing medium, and if detected, an abnormality is corrected automatically. Accordingly, an ACR sensor is mounted, facing the transfer unit to sense the color images transferred onto the transfer unit.
The ACR sensor has to be kept clean, in order to perform precise sensing. In a conventional way, a user cleans the ACR sensor using a separate cleaning tool, or operates a separate member such as a sensor cover covering the ACR sensor to wipe contaminants off the ACR sensor.
The ACR sensor is cleaned only when the user notices that the sensor is contaminated. Therefore, the ACR sensor is left contaminated and thus has deterioration of sensing accuracy, if the user does not recognize it. As a result, a color image forming apparatus has a degradation of image quality.