| 摘要 |
PROBLEM TO BE SOLVED: To provide an image forming apparatus which surely detects that a sensor such as a toner concentration sensor connected to an A/D converter is not connected to the A/D converter in such a case while achieving improvement in sensitivity of the sensor. SOLUTION: The image forming apparatus includes the A/D converter 62 including: a plurality of detection ports 72 connected to the sensor 24 outputting an analog signal; a capacitor 64 subjecting the analog signal to sample-and-hold; a comparator 66 converting the analog signal subjected to sample-and-hold by the capacitor 64 into a digital signal; and a switch 70 selectively connecting the capacitor 64 and the comparator 66 to the detection ports 72. When a potential difference between first output voltage detected when voltage is controlled to first input voltage and second output voltage detected when the input voltage is controlled to second input voltage different from the first input voltage is smaller than a predetermined value set in advance, it is judged as a situation that the sensor 24 is not connected to the A/D converter 62. COPYRIGHT: (C)2009,JPO&INPIT |
