Image forming apparatus and method for removing jam using the same

An image forming apparatus comprising:

• an apparatus body;
• a tray including a developing unit mounted thereon, the tray capable of being drawn in and out through an opening provided in the apparatus body and being movable to a received position where the whole tray is received at an inside of the apparatus body, a first exposure position where a part of the tray is exposed to an outside of the apparatus body, and a second exposure position where the whole tray is exposed to the outside of the apparatus body;
• a transfer unit installed in the apparatus body, the transfer unit comprising a paper transfer belt (PTB) for directly transferring a visible image formed on the developing unit to a recording medium;
• and
• a tray guide unit for guiding the drawing in and out of the tray with respect to the apparatus body, the tray guide unit including a 1-stage rail sliding-coupled with the tray and a 2-stage rail sliding-coupled with the 1-stage rail.