Patent ID: 7997674
Filing Date: 2011-08-16
Classification: B41J

Abstract:
1. A liquid drop ejection apparatus comprising: a liquid drop ejection head having a plurality of liquid drop ejection nozzles on a liquid drop ejection surface; a light detection unit configured to emit two coplanar beams of light in different directions and detect said beams of light; a transfer unit configured to cause relative movement between the light detection unit and the liquid drop ejection head in a direction different from directions of the light beams; and a control unit configured to control the transfer unit to cause the light detection unit to move; a position detection unit configured to detect a position of the light detection unit with respect to the liquid drop ejection head; and a deviation amount calculating unit configured to calculate an amount of deviation in the direction of liquid drops ejected from one or more of said nozzles, wherein the control unit is configured to cause the liquid drop ejection head to cause a certain nozzle to eject liquid drops while it controls the transfer unit to cause the light detection unit and the liquid drop ejection head to move with respect to each other, wherein the position detection unit is configured to detect the position of the light detection unit with respect to the liquid drop ejection head when the light detection unit does not detect one of the light beams, and wherein the deviation amount calculating unit is configured to calculate the amount of deviation in the direction of liquid drop ejection by comparing the position of the light detection unit when it stopped receiving the one of the light beams with a predetermined position at which the one of the light beams was received during normal operation.