| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an offset adjustment circuit capable of automatically adjusting an offset voltage, and a toner residual quantity detector. <P>SOLUTION: A switch 50 is closed, and the offset voltage appearing in an output of an operational amplifier 41 is converted to a digital offset signal by an A/D converter 42 and is stored in a memory 43. When a toner residual quantity detecting operation is performed, the switch 50 is opened, and a light emitting diode 21 is lit, and light transmitted through toner is received by a photo transistor 22, and a light reception output signal is amplified by an operational amplifier 41, and the light reception output signal is compared with a threshold resulting from correcting the offset voltage stored in the memory 43 by a peculiar value, by a comparator 46, and a light reception signal exceeding the offset voltage, out of an amplified component of the light reception output signal is outputted to a CPU 47 as a toner residual quantity detection signal. <P>COPYRIGHT: (C)2007,JPO&INPIT |
