Image forming apparatus and curl detecting method

A curl detecting method of an image forming apparatus including a sheet conveyance path to guide a sheet in a sheet conveyance direction, a first sensor, a first sensor lever which rotates around a first rotation shaft substantially parallel to a surface perpendicular to the sheet conveyance direction and substantially parallel to a surface of the sheet conveyed in the sheet conveyance path, and rotates between a standby position where the first sensor lever crosses the sheet conveyance path obliquely from the first rotation shaft to a sheet conveyance direction downstream side of the first rotation shaft and the first sensor is turned one of ON and OFF and a retract position where the first sensor lever is retracted from the sheet conveyance path and the first sensor is turned the other of ON and OFF, a first urging section to urge the first sensor lever from the retract position side to the standby position side, a second sensor, a second sensor lever which rotates around a second rotation shaft substantially parallel to the surface perpendicular to the sheet conveyance direction and substantially parallel to the surface of the sheet conveyed in the sheet conveyance path, and rotates between a standby position where the second sensor lever crosses the sheet conveyance path obliquely from the second rotation shaft to the sheet conveyance direction downstream side of the second rotation shaft and the second sensor is turned one of ON and OFF and a retract position where the second sensor lever is retracted from the sheet conveyance path and the second sensor is turned the other of ON and OFF, and a second urging section to urge the second sensor lever from the retract position side to the standby position side, the curl detecting method comprising

• determining a curl state of the sheet conveyed in the sheet conveyance path based on detection results of the first sensor and the second sensor.