| 摘要 |
PROBLEM TO BE SOLVED: To ideally remove noise mixed in an input signal from a differential amplifier. SOLUTION: Under the condition that the electrode 82 of the sensor 80 of an ink cartridge CR1 connected with a printer 20 is connected through an adjusting circuit 57 for calibrating the filter characteristics of an input route to the differential amplifier 54 with the differential amplifier 54. The electrode 81 of the sensor 80 is connected through a variable capacity circuit 53 consisting of n capacitors C1-Cn, one end of each of which is connected with the GND, and the other one end of each of which is connected through switches SW1-SWn with the input to the differential amplifier 54, and the n switches SW1-SWn, for further calibrating the filter characteristics with the differential amplifier 54, a sub-controlling circuit 52 can control the connecting conditions of the switches SW1-SWn so as to make the difference between the filter characteristics of two input routs to the differential amplifier 54 smaller. COPYRIGHT: (C)2010,JPO&INPIT |
