| 摘要 |
PURPOSE:To easily bring an ink jet printer to a multi-nozzle system, by arranging a pair of the detection plates of a drop sensor so that the connection center line of said detection plates forms a predetermined angle to the flight locus of an ink droplet. CONSTITUTION:The detection plates 7, 8 of the drop sensor of a ink jet printer are arranged so that the center line C of the gas (d) between both detection plates 7, 8 forms an angle alpha to the projection 10' of the flight locus of an ink droplet. The currents flowing to the detection plates 7, 8 corresponding to a detection charge amount are integrated by integration circuits 33, 34 and peak values Qmax1, Qmax2 are respectively hed to hold circuits 29, 30 while the output signal of a differential amplifier 31 comes to a level edelta after a definite time and a displacement amount delta is detected. When a detection region is set to + or -50mum in the vicinity of a detection point, max. charge QMAX is obtained at a point M. When detection can be performed up to 1% of max. charge QMAX as difference charge, the range (10mum) of the contact with the curve of difference charge outputted from a differential amplifier 31 comes to detection accuracy. |
