Patent ID: 8663578

Claim:
A liquid droplet introducing tank, comprising: a tank body formed by mutually opposing first and second surfaces, and a side surface that spreads out in a direction in which the first and the second surfaces are spaced apart the tank body having a circular cross-section; and an injection hole that is opened in the first surface; wherein liquid droplets are introduced from the injection hole, wherein a center of the injection hole is closer to the side surface than a center of the first surface, wherein a plurality of hydrophilic regions that demonstrate hydrophilicity greater than that of other portions are formed on at least one of the first surface, the second surface and the side surface each of the plurality of hydrophilic regions as a whole being smaller in size than the injection hole, and wherein the plurality of hydrophilic regions include hydrophilic regions spaced apart from each other and disposed along the side surface.