Patent ID: 7909426

Claim:
An apparatus for inspecting droplet discharge characteristics of an ink-jet printer head that subsequently discharges ink droplets, the apparatus comprising: a photographing means for operating a digital camera to generate an overlapped droplet image for a plurality of ink droplets at a predetermined photographing point before each of the subsequently discharged ink droplets hits a target point; a light emitting means for operating a speed light to give a light to an ink droplet that passes the photographing point after a predetermined delay time from a discharging time point of each ink droplet; and a droplet discharge characteristic inspecting means for calculating a signal-to-noise ratio distribution of each pixel of the overlapped droplet image, calculating an overlap rate of droplet images of each pixel from the calculated signal-to-noise ratio distribution to calculate a center coordinate of a predetermined number of droplet images, and quantitatively calculating and outputting deviation to droplet jetting velocity and direction using the calculated center coordinate of droplet image, a droplet jetting coordinate and the delay time.