Detection of non-operating nozzle by light beam passing through aperture

摘要

The object is to provide a technique whereby a non-operating nozzle can be detected with higher accuracy. The present invention resides in a printer for printing images by ejecting ink droplets from a plurality of nozzles, wherein an optical path in which light from a light-emitting element 40a for emitting light is focused by a first focusing element 41, allowed to pass through a focusing aperture 43a that is smaller than the area illuminate by the light, and transmitted through the focusing aperture 43a to a light-receiving element 40b for receiving light is laid out according to a configuration in which an intersection is formed with the path described by the ink droplets ejected by the nozzles. The light-emitting element 40a is energized and caused to emit light. The nozzles are actuated and ink droplets are ejected in the direction of a space in which the intensity of light is greater than a prescribed level and which is part of the optical path between the focusing aperture 43a and the light-receiving element 40b. A non-operating nozzle is then detected based on the fact that the light received by the light-receiving element 40b is blocked by the ink droplets thus ejected.