Patent ID: 7621617

Claim:
An ink droplet detection apparatus comprising: a plurality of nozzle lines each containing multiple nozzles which eject ink droplets; a beam radiator which radiates a detection beam so as to cross a path of the ejected ink droplets and which forms a light path of the detection beam so as to be along at least two of the nozzle lines to be detected; at least two beam receivers corresponding to the nozzle lines being detected for receiving the detection beam radiated from the beam radiator and detecting the ink droplets ejected from each nozzle by determining whether the ink droplets ejected from each nozzle intercept the light path; an ejecting control circuit which controls ejection of the ink droplets from the nozzles; and a controller for controlling the ejecting control circuit by sending the ejecting control circuit first same ejecting start signals for each of the nozzle lines being detected so that an ejecting timing of the ink droplets to be ejected from each first nozzle of the plurality of the nozzle lines being detected is synchronized; wherein the controller sends the ejecting control circuit second same ejecting start signals for each of the nozzle lines being detected so that an ejecting timing of the ink droplets to be ejected from each second nozzle of the plurality of the nozzle lines being detected is synchronized at a time the ink droplets are detected from all the nozzle lines by the beam receivers before a fixed time has elapsed after the first same ejecting start signals were sent to the ejecting control circuit.