| 摘要 |
PROBLEM TO BE SOLVED: To provide an image forming device which causes almost no image fog and soil in the device and can vary copying speed. SOLUTION: Around a freely rotatable photoreceptor drum 1 are an electrifying charger 2, erasure array 3, exposure part 4, developing unit 5, transfer charger 6, stripping charger 7, cleaner 8, and discharge lamp 9. A toner cassette 22 is mounted in the upper part of the developing unit 5, and, in its lower part, a toner sensor 21 is provided for detecting toner concentration. A cassette driving part 23 rotates the toner feed roller of the toner cassette 22 in response to a toner replenishment signal from a control part 24. When high copying speed is selected, the control part 24 makes correction in which 0.05 V is subtracted for the output of the toner sensor 21, and generates a toner replenishment signal based on the result of the subtraction. |
