For a recording apparatus capable of supplying a plurality of different color inks to a plurality of recording element substrates, when a condition for performing maintenance on a first recording element substrate is met, it is determined whether or not to perform maintenance on a second recording element...http://www.google.com.au/patents/US20050190226?utm_source=gb-gplus-sharePatent US20050190226 - Inkjet recording apparatus and maintenance method thereof
