| 摘要 |
<p>A colour registration adjusting method in an image forming apparatus includes the steps of (a) discriminating whether the detected pulse width for the edge of a photoreceptor belt is smaller than the expected pulse width therefor or not; (b) setting the detected pulse width to a scanning start signal (an edge signal mixed) if the detected pulse width is smaller than the expected pulse width in the step (a), and setting a value obtained by subtracting a predetermined value from the currently expected pulse width to the next expected pulse width; (c) setting the expected pulse width to a scanning start signal (an edge signal mixed) if the detected pulse width is greater than or equal to the expected pulse width in the step (a), and, to set the next expected pulse width, discriminating whether the counted value of a pulse is smaller than an offset value; (d) setting a value obtained by subtracting a predetermined value from the currently expected pulse width is set to the next expected pulse width if the pulse counted value is smaller than the offset value in the step (c); and (e) setting a value obtained by adding a predetermined value to the currently expected pulse width to the next expected pulse width if the pulse counted value is greater than or equal to the offset value in the step (c). The detected pulse width and the expected pulse width for the edge of a photoreceptor belt are compared to each other to set the result to a scanning start signal (an edge signal mixed). Particularly, since some of the next expected pulse widths are discriminated by comparing the pulse counted value and offset value, the mis-registration of colour in the main scanning direction of a laser beam can be adjusted quantitatively. <IMAGE></p> |
