Patent ID: 8613513

Claim:
A sheet-medium conveying apparatus comprising: a conveying belt configured to adsorb a sheet medium with an electrostatic force by being electrically charged and convey the sheet medium; a charge-pattern forming unit configured to form a certain charge pattern on the conveying belt, wherein at least on positions to which a leading end and a trailing end of the sheet medium are to be adsorbed, the charge-pattern forming unit forms a charge pattern in which a polarity changes in a direction orthogonal to a conveying direction of the conveying belt; a measuring unit configured to measure an electrical characteristic of a sheet medium; and a setting unit configured to set an output voltage of the charge-pattern forming unit in accordance with the electrical characteristic measured by the measuring unit, wherein: an electrical resistance Rb of the conveying belt is compared with a threshold Rc, prior to measuring the electrical characteristic of the sheet medium, if the electrical resistance Rb is greater than the threshold Rc, the measuring unit starts to measure the electrical characteristic of the sheet medium, and if the electrical resistance Rb is smaller than the threshold Rc, a notice of a possibility of occurrence of bad quality image is given for allowing a user to determine whether to continue a print job.