The invention provides methods of detecting a nucleic acid. By activating a piston, the underpressure retains the excess pressure release in its open position against the force of a spring, until a desired counter pressure from the filled air cushion stops the injector effect, whereby the excess pressure release is closed. An image modification unit generates modification image data corresponding to one of the left eye image data and the right eye image data. The translucent optical device reflects most of the laser beam. The gas, which is contained in the liquids in the ink inflow flow passages and the ink outflow flow passages, is discharged via the gas-permeating film to a gas discharge passage.