Patent ID: 8208826
Filing Date: 2012-06-26
Classification: G03B

Abstract:
1. An image forming device configured to form an image on a print sheet, comprising: a conveying member configured to convey the print sheet; a light source configured to irradiate light toward the conveying member; a photo-sensor configured to detect light irradiated from the light source and reflected by the conveying member; a shutter member configured to be movably disposed between a close position at which the shutter member shields the light irradiated from the light source and directed toward the conveying member, and an open position at which the shutter member does not shield the light directed from the light source toward the conveying member, the light incident on the conveying member being reflected and directed to the photo-sensor; a shutter driving unit configured to move the shutter member between the close position and the open position; a reflecting member provided on a photo-sensor side of the shutter member, the reflecting member being configured to reflect light emitted by the light source when the shutter member entirely or partially shields the light emitted by the light source, an intensity of light reflected by the reflecting member and detected by the photo-sensor varying depending on a position of the shutter member, wherein the reflecting member comprises a first reflecting member and a second reflecting member, the first reflecting member having a reflectivity that is greater than or less than the reflectivity of the second reflecting member; and a judging member configured to judge (1) whether the shutter member is located at the close position or the open position based on variation of the intensity of the light detected by the photo-sensor when the shutter member is being driven to move by the shutter driving unit, and (2) whether the conveying member is present or absent based on the intensity of the light detected by the photo-sensor when the judging member judges that the shutter member is located at the open position, wherein the judging member is further configured to judge that the shutter member is moving from the close position to the open position if a signal from the photo-sensor changes from a value corresponding to the reflectivity of the first reflecting member to a value corresponding to the reflectivity of the second reflecting member, and to judge that the shutter member is not moving from the close position to the open position if a signal from the photo-sensor does not change from a value corresponding to the reflectivity of the first reflecting member to a value corresponding to the reflectivity of the second reflecting member.