A compact monochrome ink jet printhead having a staggered high-density arrangement of ink drop generators for high-performance printing. A row decoder 3 selects a word line connected to a memory cell to be read. Non-standard video signal having improper odd-even field sequencing is also processed and converted. Further, the negative pressure valve divides the interior of the exhalation unit into two chambers, one of which functions as a dead space that protects the user from exposure to any harmful contaminants at the end of exhalation. A fastening member connects and disconnects the elastic connecting member and the mounting member by fastening a socket of the mounting member.