Patent ID: 7611221

Claim:
A liquid ejection apparatus, comprising: a liquid ejection head having a plurality of ejection ports which eject droplets of liquid; a light emitting device which emits a determination light beam intersecting with flight paths of the droplets ejected from at least two of the ejection ports to be examined; a light receiving device which receives the determination light beam having passed through the flight paths of the droplets and outputs a determination signal corresponding to an amount of received light; a first ejection port selection device which selects the at least two of the ejection ports to be examined with respect to ejection failure so that a distance between the at least two of the ejection ports selected by the first ejection port selection device along the optical axis of the determination light beam is larger than a prescribed specific distance; a first ejection control device which performs ejection driving to eject the droplets at substantially same time from the at least two ejection ports selected by the first ejection port selection device; a first ejection state judgment device which judges whether or not the droplets are ejected from the at least two ejection ports to be examined with respect to ejection failure according to the determination signal outputted by the light receiving device when the droplets ejected due to the ejection driving performed by the first ejection control device pass through the determination light beam; a second ejection port selection device which selects the at least two of the ejection ports to be examined with respect to flight abnormality so that the at least two of the ejection ports are disposed on a line parallel to the optical axis of the determination light beam, and that a distance between the at least two of the ejection ports selected by the second ejection port selection device along the optical axis of the determination light beam is smaller than the prescribed specific distance; a second ejection control device which performs ejection driving to eject the droplets at substantially same time from the at least two ejection ports selected by the second ejection port selection device; and a second ejection state judgment device which judges a presence of an abnormality in at least one of a flight direction and a flight speed of the droplets ejected from the ejection ports to be examined with respect to flight abnormality according to the determination signal outputted by the light receiving device when the droplets ejected due to the ejection driving performed by the second ejection control device pass through the determination light beam.