Alignment pattern detecting sensor, method of determining acceptance width of the alignment pattern detecting sensor, method of forming alignment pattern, and image forming apparatus

A method of forming an alignment pattern for an image forming apparatus, comprising:

• deriving a correlation between a line width of the alignment pattern, a writing density of the image forming apparatus, and an acceptance width of the alignment pattern detector;
• determining the line width based on the correlation derived;
• and
• forming the alignment pattern on a medium based on the line width determined.

An image forming apparatus comprising:

• an alignment pattern forming unit that forms an alignment pattern on a medium by superposing a line image of a reference color and a line image of a sample color other than the reference color;
• an alignment pattern detector that detects the alignment pattern;
• and
• a misalignment correcting unit that, based on output signals of the alignment pattern detector, determines an amount and a direction of a misalignment between the line images of the two colors, and corrects the misalignment, wherein
• an acceptance width of the alignment pattern detector, a line width of the alignment pattern, and a writing density of the image forming apparatus satisfy following inequality
• [acceptance width]>[line width]/(α×[writing density(dpi)]−β).