Pen puzzle pauses printer

摘要

Many years ago, I was working for a company that designed and manufactured desktop ink-jet printers. We had just released a model that used a new higher-resolution color pen, but we were having high infant mortality on the new printers. Management asked me to investigate the failures that were primarily occurring in the head drive's ASIC, which fired the pen. The ASIC contained switching FETs controlling the firing currents to the pens' nozzle resistors, which expelled the ink from the nozzles.