Sheet type determining device and image forming device

An image forming device comprising:

• a sheet type determining device;
• and
• an image former that forms an image on a sheet after a sheet type is determined by the sheet type determining device, the image being formed according to an image forming condition determined by a determination result of the sheet type determining device, wherein
• the sheet type determining device comprises
• a guide that guides a sheet along a sheet conveyance path to a destination, the sheet conveyance path being between a first guide surface and a second guide surface disposed facing each other across an interval;
• a determiner that determines a sheet type when the sheet is in the sheet conveyance path, without having contact with the sheet in conveyance;
• and
• one or more regulators, each of the regulators regulating a displacement range of the sheet in a direction of the interval between the first and the second guide surfaces, at a determining position in the sheet conveyance path where the determiner determines the sheet type, wherein
• each of the regulators is a member that protrudes in an arc shape from the first or the second guide surface toward the guide surface opposite, and
• each of the regulators is spaced from the guide surface or another one of the regulators opposite in a direction perpendicular to a surface of the sheet;
• wherein
• the number of the regulators is two or more,
• the regulators protruding from the first or the second guide surface are disposed at both sides of the determiner in a width direction of the sheet in conveyance.