Patent ID: 8326549

Claim:
A control device controlling a rotational speed of a rotated body, the control device comprising: a transmission unit configured to include a first gear rotating along with a motor shaft of a motor and a second gear rotating along with a rotating roller which drives the rotated body and to be formed by the first gear and the second gear, engaged to transmit rotation of the motor shaft; a speed detecting unit configured to detect the rotational speed of the rotated body or the rotating roller in association with time; a motor controlling unit configured to control the motor to have a constant motor shaft rotational speed based on the rotational speed; a converting unit configured to convert the rotational speed detected in association with the time to a relationship between a frequency contained in variation of the rotational speed in association with the time and a variation value indicative of magnitude of the variation of the rotational speed; a variation value recording unit configured to record the variation value of the past at the specified frequency in association with date information indicative of data when the variation value is acquired; a predicting unit configured to predict a date when the variation value exceeds a threshold value from the plural variation values of the past stored in a memory; and a wear detecting unit configured to detect a predictor of wear of cogs included in at least one of the first gear and the second gear when the variation value at a specified frequency, which is determined based on a number of the cogs of the first gear and the motor shaft rotational speed of the motor, exceeds the threshold value, wherein the wear detecting unit detects the predictor of wear when a number of residual days until the variation value exceeds the threshold value is less than a set value.