| 摘要 |
PURPOSE:To stably control an image density even if the characteristic values of a developer and photosensitive body change by constituting a power supply circuit in such a manner as to impress the output voltage which applies the potential larger than the potential on a light emitting element side to a light receiving element side. CONSTITUTION:An A/D converter 23 for outputting a detection signal is outputted to the terminal part on the other side of a phototransistor 15. A volume control 16 is subjected to resistance adjustment in such a manner that the detection output obtd. through an A/D converter 23 of the phototransistor 15 attains an adequate value. Such light reflection sensor 13 is held under control of a main CPU 25. This main CPU 25 has the function to maintain the specified toner concn. in the developer by operating a motor 26 for toner replenishment in accordance with the output signal from the light reflection sensor 13. |
