Patent ID: 6682162
Filing Date: 2004-01-27
Classification: B41J

Abstract:
A printing apparatus comprising:at least one ink duct provided with an electromechanical transducer, a drive circuit provided with a pulse generator and operatively associated with the transducer to energize said transducer by providing an electrical pulse, a measuring circuit operatively associated with the transducer for measuring and characterizing an electrical signal generated directly by the transducer in response to said energizing by the pulse generator, means for breaking the circuits in such a manner so that when the drive circuit is open, the measuring circuit is closed in order to separate the electrical pulse from the electrical signal generated by the transducer, wherein measurement and characterization of the electrical signal takes place when the printing apparatus is in a printing mode such that in this printing mode, a deviation in the ink duct other than for an air bubble can be distinguished from the air bubble based on the characterization of the electrical signal.