Patent ID: 9056465
Filing Date: 2015-06-16
Classification: B41J

Abstract:
1. An ink-jet printer for printing a substrate with graphic and/or functional inks the ink-jet printer comprising: a print head with ink-jet nozzles; an optical device at least partially integrated in the print head to monitor the correct functioning of the ink jet nozzles, the optical device illuminating drops ejected from the nozzles by means of light from a light source from a direction of the ink-jet nozzles through the print head by means of illumination signals which are either constant in time or changeable in time, the optical device comprising the light source, light sensitive sensors, a light-conducting element arrangement conducting light from the light source through at least one light-conducting element through the print head and through which light-conducting element arrangement light reflected by the drop ejected from the nozzle during the flight of the drop is conducted backwards in the direction of the nozzles onto the light-sensitive sensors; and an evaluation device to examine the correct form and the correct ejection of the drop, concluded from the specific timing of the sensor signal, wherein: the print head comprises ink channels which are limited by ribs, with the ribs being component parts of the optical device and being transparent for the light from the light source; and the light source and the light-sensitive sensors are arranged in such a way that the ribs conduct the light from the light source through the print head onto an ejected drop, or conduct the light reflected by an ejected drop through the print head to a photosensor.