Patent ID: 7280129

Claim:
A pixel position specifying method in an image forming device which forms an image by scanning, in a given direction, a plurality of exposure heads which can selectively turn a plurality of pixels on and off, the method measuring positions of exposure beams of the respective exposure heads and specifying pixel positions of junctures of the exposure heads, the method comprising: measuring a position of an exposure beam by using a beam position detecting mechanism which is formed so as to be movable on a reference surface along a Y axis direction which is parallel to a scanning direction of the exposure device, and which has at least one pair of slit portions, which are disposed so as to be inclined relative to arrangements of pixels of the exposure heads, and a light amount measuring mechanism, which measures light amounts of exposure beams which pass through the slit portions; specifying a position of a first connecting pixel on the basis of a position of the beam position detecting mechanism and positions of the slit portions and an angle formed by the slit portions, at a time when the first connecting pixel in a vicinity of a juncture of an image at a first exposure head is turned on and the beam position detecting mechanism is moved along the Y axis direction and light amounts of exposure beams passing through one slit portion and another slit portion reach peaks; and specifying a position of a second connecting pixel on the basis of a position of the beam position detecting mechanism and the angle formed by the slit portions, at a time when the second connecting pixel in a vicinity of a juncture of an image at a second exposure head is turned on and the beam position detecting mechanism is moved along the Y axis direction and light amounts of exposure beams passing through the one slit portion and the other slit portion reach peaks.