Image forming apparatus, belt driving device, and belt driving device control method

A belt driving device comprising:

• a plurality of rollers including a driving roller;
• an endless belt stretched around the plurality of rollers;
• a driver, with one of the plurality of rollers as a tension control roller to control tension applied to the endless belt, that moves a position of the tension control roller in a vertical direction to an axis of another roller;
• a position detector that detects the position of the tension control roller;
• a pressure detector that detects pressure applied to the tension control roller with the endless belt;
• and
• a controller that controls movement of the tension control roller with the driver,
• wherein, to set the tension applied to the endless belt as a predetermined value, the controller controls the driver to bring the pressure detected with the pressure detector closer to a target pressure to be added to the tension control roller in the position of the tension control roller detected with the position detector.

A method of controlling a belt driving device comprising:

• a plurality of rollers including a driving roller;
• an endless belt stretched around the plurality of rollers;
• and a driver, with one of the plurality of rollers as a tension control roller to control tension applied to the endless belt, that moves a position of the tension control roller in a vertical direction to an axis of another roller, comprising:
• detecting the position of the tension control roller with a position detector;
• detecting pressure applied from the endless belt to the tension control roller with the pressure detector;
• and
• controlling, to set the tension applied to the endless belt as a predetermined value, the driver to bring the pressure detected with the pressure detector closer to a target pressure to be added to the tension control roller in the position of the tension control roller detected with the position detector, with the controller.