Patent ID: 8454140
Filing Date: 2013-06-04
Classification: B41J

Abstract:
1. A valve unit having a plurality of pressure adjusting mechanisms, each of the pressure adjusting mechanisms comprising: a pressure chamber connected to a print head; a supply path connected to an ink tank; a valve disc able to open and close a communication between the pressure chamber and the supply path; a biasing member to urge the valve disc in a closing direction; and a flexible film to open the valve disc against the biasing force of the biasing member when a negative pressure in the pressure chamber exceeds a predetermined level, wherein a plurality of the valve units can be installed in the print head such that they adjoin each other in a first direction crossing a direction of their installation into the print head, wherein the flexible film in at least one of the plurality of the pressure adjusting mechanisms is disposed at one side surface, with respect to the first direction, of the valve unit and inflates outwardly from the one side surface in response to pressure in the associated pressure chamber, wherein the flexible film in at least one of the other of the plurality of the pressure adjusting mechanisms is disposed at another side surface, with respect to the first direction, of the valve unit and inflates outwardly from the other side surface in response to pressure in the associated pressure chamber, wherein the flexible films disposed at the one side surface and at the other side surface are so arranged that, when projected on a first plane extending parallel to the one side surface and the other side surface, their projected figures partly overlap each other, wherein, when the plurality of the valve units are installed in the print head so that the one side surface of one of two adjoining valve units, adjoining each other in the first direction, opposes the other side surface of the other valve unit, and when the flexible films of the plurality of the pressure adjusting mechanisms in the two adjoining valve units inflate outwardly to the greatest extent, the flexible film on the one side surface of the one valve unit and the flexible film on the other side surface of the other valve unit at least partly overlap each other in their projected figures on a second plane perpendicular to the first plane, wherein the flexible films are each shaped like a truncated cone, protruding outwardly, wherein a relationship P<D wherein a relationship L<2H holds where L is a distance between the one side surface of the one valve unit and the other side surface of the other valve unit and H is a height of each of the flexible films that have inflated outwardly to the greatest extent from the one side surface and the other side surface, wherein a relationship D