Patent ID: 7416074

Claim:
A belt conveying device comprising: (a) an endless belt capable of conveying an object to be conveyed; (b) at least three rollers about which the endless belt is entrained, which drive the endless belt, the three rollers including a single oscillation roller having a rotation shaft, one end of which representing a fixed edge is supported not to be moved and another end of which representing a movable edge is oscillatably supported; (c) an oscillator which oscillates the oscillation roller by moving the movable edge; (d) a belt detection sensor provided adjacent to a side edge of the endless belt, which detects a skew in a width direction of the endless belt; and (e) a skew controller which moves the movable edge of the oscillation roller for a predetermined distance to correct the skew in the width direction of the endless belt by controlling the oscillator using a preset control value in a predetermined range, wherein the oscillator moves a rotation center of the movable edge of the oscillation roller along a tangential line of an ellipse having elliptical focuses corresponding to rotation centers of rotation shafts of the two rollers, other than the oscillation roller, which are positioned respectively in upstream and downstream of and adjacent to the oscillation roller in a conveyance direction of the endless belt.