| 摘要 |
PURPOSE:To prevent the application of a voltage due to the electric charging of toner and to eliminate malfunction and an error in detection by providing an insulating layer on a surface of a diaphragm which contacts the toner at a toner level detecting device which uses a piezoelectric ceramic plate. CONSTITUTION:Two divided electrodes 3 and 4 are stuck on one surface of the piezoelectric ceramic plate 1 and lead wires 5 and 6 are connected respectively. Further, the diaphragm 2 consisting of a conductive layer 7 and an insulating layer 8 is stuck on the opposite surface of the piezoelectric ceramic plate 1 to constitute the toner level detecting device. When a toner level is detected by using this detecting device, the detecting device is fitted on the wall 11 of a toner storage box so that the insulating layer 8 is on the side of the toner 13. Then, an AC voltage or pulse voltage is applied between the lead lines 5 and 10 and an output voltage is led out through other lead wires 6 and 10 to detect the amount of the toner. |
