Monitoring of functioning of ink jet print head

摘要

The flow rate of ink transferred over a line 21 from a reservoir 2 to an ink jet print head 1 is monitored by a sensor 5 that generates a digital input to a processor 3. The actuation pulse signals applied by a control circuit 6 to the head are counted and the value fed as a digital value to the processor. The two values are compared. If their difference value deviates from a predetermined difference value, the printing process is interrupted and a cleaning process 4 for the head is initiated. and a difference value determined. During cleaning, the flow rate is measured. Changes in the rate are calculated as an indicator of the cleansing appts. functioning. After cleaning, the printing process is started and both values taken from the same starting point. During cleaning the flow rate value is compared with a stored value. If it differs from the stored value, the cleaning process is interrupted for an error correcting of the cleaning appts.