Patent ID: 7684742

Claim:
An image forming apparatus, comprising: an image forming mechanism configured to form a toner image, the image forming mechanism including a transfer unit configured to be electrically charged, said transfer unit including a bias roller; an image conveying member configured to convey the toner image on a surface thereof; a transport mechanism configured to transport the toner image from the image conveying member; a non-metallic scale provided around an entire perimeter of a surface of the transport mechanism, the scale including a transparent resin film covering an adhesive layer, the adhesive layer including a light colored adhesive with high reflectance and a deep colored adhesive with low reflectance forming a plurality of pitch lines of the deep color at predetermined intervals, the non-metallic scale being non-conductive and electrically isolated from the transfer unit by the transparent resin film so that electrical charge from the transfer unit does not leak to the non-metallic scale; and a scale reading mechanism arranged to face the non-metallic scale and configured to read the non-metallic scale optically.