| 摘要 |
<p>An electrophotographic printing apparatus comprising a photoreceptor (12) and an electrically biassed developer roll (56). Means (66) are provided for sensing the current biassing the developer roll (56) and for generating a proportional control signal for regulating a processing station. Preferably it is the discharge of toner which is regulated. Before the control signal is applied, it is modified by a further signal sampled at selected intervals. The further signal may be generated by either (a) a densitometer (24) measuring the mass to area ratio of the developer deposited on a test area of the photoreceptor (12); or (b) a voltage probe adjacent the photoreceptor. In an alternative embodiment the main control signal is generated by the voltage probe and is modified at selected intervals by the signal from the current sensing means (66).</p> |
