The engine section of Canon's color network digital MFPs employs a laser unit and drum unit for each CMYK color, arranged serially in tandem. The approach enables higher output speeds than the singledrum method of image creation.

The optical system employs a High-Definition 4-Beam Laser Unit that simultaneously emits four laser beams onto the photosensitive drum via a polygon mirror that scans beams horizontally. This compact mirror, which measures 20 mm diagonally and has four surfaces, controls laser beams by rotating at a speed of 37,000 rpm. Compact rotation motors and improved bearings reduce rotating noise. Laser units are L-shaped and positioned adjacent to the drum units to reduce overall dimensions.

Structure of 4-Beam Laser Unit and Writing on the Photosensitive Drum

Compared with single-drum systems, tandem systems are believed to be more susceptible to color blurring and variations in image density. Canon employed advanced sensing technologies to solve such problems. To eliminate color blurring, the engine measures each color pattern formed on the intermediate transfer belt with a photosensor to automatically correct the writing position of each color to the photosensitive drum. Variations in image density are automatically corrected by forming a patch of each color on the intermediate transfer belt and scanning it with an RRPS sensor capable of sensing image density with remarkable precision.

Registration Correction