Patent ID: 8052247

Claim:
A full-width image forming apparatus comprising: a multi-array head unit including a plurality of full-width head modules that extend across a width of a conveyed sheet, each of the plurality of full-width head modules including a plurality of short-length heads, each of the heads including nozzle rows arranged in a width direction of the conveyed sheet and which discharge liquid droplets; a base member to hold the heads of a first head module arranged thereon, the heads of the first head module being arranged in a single row on the base member; a liquid supply member provided on the heads of the first head module and that extends in a direction in which the heads of the first head module are arranged, and to form a common channel for distributing and supplying liquid to the heads; and a plate spring configured to cause the heads and the liquid supplying member to engage each other, wherein at least one of the heads includes a first circular supply opening port having a convex part, the first circular supply opening port including a first supply opening to receive ink from the liquid supply member and supply the ink to the head, wherein the liquid supplying member includes a plurality of second circular supply opening ports each having a concave part configured to engage the first supply opening port of the head, each second circular supply opening port having a second supply opening to supply ink from the common channel of the liquid supplying member to the head, and wherein an o-ring having a circular shape in a planar direction is provided between the liquid supply member and the head, the o-ring having a specific size configured to fit onto an outer peripheral portion of the first supply opening port, such that the o-ring protrudes above an upper surface of the convex part of the first supply opening port when the head and the liquid supplying member are not engaged, wherein when the plate spring causes the head and the liquid supplying member to engage each other, the o-ring is fit inside the concave part of the second circular supply ports, is pressed against a lower surface of the second supply opening port and is deformed to seal a connection portion between the liquid supply member and the head, such that the first supply opening and the second supply opening communicate with each other.