Patent ID: 7499667

Claim:
An endless belt drive controlling apparatus comprising: an endless belt; a drive roller that drives the endless belt; a drive unit that drives the drive roller; a plurality of driven rollers driven to follow up a movement of the endless belt, wherein an encoder is attached to one of the driven rollers, a desired control value is set so that an angular displacement of the encoder per unit time is constant, and the drive unit is controlled to attain the desired control value; the endless belt drive controlling apparatus further including: a belt mark indicating a reference position of the endless belt; a first detector that detects the belt mark; a second detector that detects a detected angular displacement error of the encoder generated due to a variation in a thickness of the endless belt; a first calculating unit that calculates a phase and a maximum amplitude of the endless belt at the belt mark based on the detected angular displacement error of the encoder obtained by the second detector; a nonvolatile memory that stores a calculation result of the first calculating unit; and a second calculating unit that calculates a position of the endless belt at which the detected angular displacement error of the encoder is a minimum from the phase stored in the nonvolatile memory, wherein the drive unit controls the endless belt so that a portion of the endless belt at which the detected angular displacement error of the encoder is the minimum is stopped at a position of one of the driven rollers at which a highest tension is applied to the endless belt when the drive unit issues a belt stop command.