Patent ID: 8687985

Claim:
A belt drive apparatus, comprising: an endless belt rotationally movable by being supported by a plurality of rollers; a moving speed signal output part configured to output a signal based on a rotational movement of said endless belt; a width direction position signal output part configured to output a position signal for which its value changes in response to a position of said endless belt in a direction of width of said endless belt; a width direction position control part configured to control a position of said endless belt in the direction of width of said endless belt; a process execution part configured to perform a predetermined process using said signal output from said moving speed output part based on said position signal output from said width direction position signal output part; a judgment part configured to judge whether said position signal from said width direction position signal output part falls within a predetermined range within a predetermined time from a start of the control of said width direction position control part, and subsequently judge whether an abnormality occurs in said predetermined process after the judgment part judges that said position signal falls within the predetermined range within the predetermined time, and an abnormality notification part configured to notify that there is an abnormality when said judgment part judges that said position signal does not fall within the predetermined range within the predetermined time.