Increasing image forming method and apparatus therefor in led printer

摘要

A LED printer utilizing a low resolution print engine for forming high resolution images is disclosed, in which a virtual 2N dpi high density image (latent image) is formed on a photosensitive medium by effectively turn-on controlling an array of LED elements arranged at a pitch of N dpi on a line in the main scanning direction. For each scanning line, a plurality of divisional exposure lines are produced for turning on the LED elements 2 m times (for instance 2x4 times) in the auxiliary scanning direction. For the turn-on control of the LED elements, weighted arithmetic operation values are obtained by multiplying the center bit and one or more adjacent bits thereto in the main scanning direction of the 2N dpi high density image data by respectively corresponding constants, and they are summed up to obtain sum data. According to the sum data the number of times of turning on the LED elements on the divisional exposure lines is controlled to form 2N dpi high density image on the photosensitive medium.