Patent ID: 7978213

Claim:
A focus adjustment method of an LED print head of an image forming apparatus, wherein the LED print head including an LED array which is structured of plural LEDs to form an electrostatic latent image on a photoconductor and is arranged in a longitudinal direction of the photoconductor, comprising: setting one end with respect to a longitudinal direction of the LED print head on a first position where a distance between the photoconductor and the LED print head becomes shorter than a designed focal length, and other end with respect to the longitudinal direction of the LED print head on a second position where the distance between the photoconductor and the LED print head becomes longer than the designed focal length; outputting a pattern image having a predetermined resolution, wherein a high resolution line and a low resolution line are formed by the step of setting one end and other end of the LED print head; and adjusting the position of the LED print head by moving each of the one end and the other end of the LED print head, based on information of the resolution of the outputted pattern image; wherein the pattern image is formed by lighting the LEDs in a repeating pattern of a lit pair of LEDs adjacent to an unlit pair of LEDs.