In an ink jet recording apparatus, when the time since a last head maintenance process was executed exceeds a second period of time but is less than a first period of time, the printing status of the apparatus is monitored. During this time frame, a non-print period is measured and if that period exceeds...http://www.google.com.tw/patents/US6398336?utm_source=gb-gplus-share專利 US6398336 - Ink jet recording apparatus and maintenance method therefor
