In an inkjet printer, print image data indicating a pattern of ejection and non-ejection nozzles is produced from print data received from a host computer and the print image data is searched in blocks for an effective block including data indicating at least one ejection nozzle to count effective blocks,...http://www.google.de/patents/US6145947?utm_source=gb-gplus-sharePatent US6145947 - Ink consumption detection method and system
