| 摘要 |
PURPOSE:To inform automatically the time of filter replacement due to filter mesh clogging by providing an ink filtering filter with a pressure sensor consisting of a piezoelectric element. CONSTITUTION:Out of ink drops 27 jetted out of the head 1 a drop 27b that is not used for printing is recovered by a gutter 22, and resupplied to the head 1 through a filter 12. Here, the ink pressure in the head 1 is detected electrically by means of the pressure detection electrode 6 of a pizoelectricity oscillator 5 and inputted to an AND gate circuit 16. This circuit 16 displays abnormality by driving a display device 20 for displaying abnormality, if the input of the above mentioned electrode 6 is lower than the output of a piezoelectricity element sensor 13 that is arranged in the front section of the filter 12 by a specified value, and at the same time the circuit 16 controls as required a pressure pump 18 through a control circuit 19. |
