An electromagnetic relay including a contact switching unit having a pair of contacts. Accordingly, in the Inkjet head of an exemplary embodiment of the present invention, the floors of the inner storage space of the ink storage unit form a step, and the ceiling of the inner flow space of the head unit is inclined, thereby preventing the ink vapor from being confined inside the head unit. In this way if there is a pin hole type defect in either coating or sheet of dielectric material, in all probability it will not align with a similar defect in the other sheet or coating of the dielectric layer, thus preventing unwanted plating extending from one layer of circuitry to the underlying layer of circuitry. A housing contains the acid discharge unit and at least part of the pH control system. Embodiments include using a scanning electron microscope capable of collecting electrons emitted from a plurality of angular sectors to obtain an image of the defect and a reference image containing topographical and location information, then analyzing this information to classify the defect. The chunks are selectively sized from at least one page to an entire size of the print job in accordance with predetermined splitting factors for enhancing printer printing efficiency.