| 摘要 |
PURPOSE:To prevent a toner density signal from being affected by a copying image density by forming a standard pattern image at the length proportional inversely with a set value of a copied image density, and using the value obtd. by integrating the optical density detection signal of the standard pattern image as the toner density signal. CONSTITUTION:A detecting circuit 1 for the set value of an image density detects the signal for adjusting the image density set by a copying density setter A and outputs the voltage signal of the level proportional inversely to the set density. A voltage-time transducing circuit 2 forms the pulse signal having the width proportional to the signal level from the circuit 1, outputs the same at the point of the time when a scanner starts moving, and disables an erasing lamp driver B during the time corresponding to the pulse width from the circuit 2 in a circuit 3 for putting out the erasing lamp. A detecting circuit 4 for a pattern density exposes a member C for a standard density pattern, samples the signal emitted from a photosensor E detecting the pattern image formed on a photosensitive drum D for a prescribed time, integrates the value and outputs the same to a controller F. |
