Apparatus for and method of forming image using oscillation mirror

An image forming apparatus, comprising:

• a latent image carrier which has an effective image region over a predetermined width along a main scanning direction;
• a latent image forming section which, using a deflection mirror surface which oscillates, makes a light beam from a light source reciprocally scan a second scanning area which is wider than a first scanning area which corresponds to the effective image region along the main scanning direction, and guides the scanning light beam in the first scanning area toward the effective image region, thereby forming a latent image in the effective image region;
• a detector which is disposed outside the first scanning area but within the second scanning area, outputs a first detection signal when a first light beam moves past the detector, and outputs a second detection signal when a second light beam moves past the detector, the first light beam being the scanning light beam traveling away from the effective image region, the second light beam being the scanning light beam traveling toward the effective image region;
• and
• a controller which controls a latent image forming operation based only on the first detection signal which is outputted from the detector and not on the second detection signal.