Image forming apparatus

An image forming apparatus configured to receive and convey a roll sheet to an image forming unit to record an image on the roll sheet, the image forming apparatus comprising:

• a pair of rotatable members for rotatably retaining flanges fixedly mounted to respective ones of opposite ends of the roll sheet;
• a roller for rotatably retaining the flanges together with the rotatably members;
• a pair of placement stages on which respective ones of the rotatable members are mounted and on which the roll sheet is to be placed, the placement stages being mounted for undergoing movement along a longitudinal direction of the roll sheet;
• a pair of racks mounted to respective ones of the pair of placement stages for undergoing movement to move the pair of placement stages relative one another to vary a distance between the pair of placement stages;
• a pinion arranged between the pair of racks for undergoing rotation to move the pair of racks;
• a potentiometer whose resistance value varies in accordance with a distance between the pair of placement stages undergoing movement with rotation of the pinion;
• voltage detecting means for detecting a voltage value in accordance with a resistance value of the potentiometer;
• and
• calculation means for calculating a width of the roll sheet based on the detected voltage value.