Patent ID: 7100520

Claim:
A theft-prevention ink pack device, comprising: an ink pack, consisting of a bag containing ink, that is placed inside a case having a front board on which an ink spout is formed; a spring that urges the ink pack and a knife edge to close in on each other, the spring thereby applying pressure to the ink pack; the knife edge that tears the ink pack, wherein the knife edge is a portion of the front board of the case and is formed by cutting and bending said front board at the rim of the ink spout; and an engaging structure that is engaged to support a state in which the ink pack and the knife edge are spaced apart from each other, and is disengaged when an outer force is applied; wherein: the ink pack and the knife edge close in on each other by means of a spring force of the spring when the engaging structure is disengaged so that the ink pack is torn by the knife edge, and the ink pack is pressured, resulting in the ink shooting out from the ink spout.