An ink cartridge is disclosed and includes a hollow ink tank body, a cover member connected to the body, a pressure regulator mounted on the bottom of the body, a tank disposed under the body and connected to the bottom thereof, and a hollow tube. A front contact plate contacting cardboard sheets is movable in a feed direction. 5 Ncm of the tensile behavior in the transverse direction of the film at an engineering strain of about 1. Because the internal heat exchanger performs heat exchange between high-pressure refrigerant and low-pressure refrigerant, performance of the internal heat exchanger is not degraded even if it is located at a part receiving less cooling air.