1. Normal Toner Density (Vsg: 4 V) Vsp is about 1/8 Vsg (=0.5 V) in the normal toner density condition. 2. Low Toner Density (Vsg: 4 V) If the toner density is low, the ID sensor pattern image on the drum is dimmed. Consequently, Vsp is higher and the toner is supplied until the next ID sensor check cycle (11 sheets � 20 sheets). Toner Supply Condition If Vsp > 1/8 Vsg, the toner supply signal is generated.
(Normal)
3. High Toner Density (Vsg: 4 V) When the toner is supplied, the toner density becomes higher and the ID sensor pattern image becomes darker. Consequently, Vsp is lower than the reference value and the toner is not supplied.
(Low)
(High)
4. Abnormal Vsg If Vsg becomes less than 2.5 volts four times continuously, the CPU determines that the detected value is abnormal. It then changes from the detect mode to the fixed supply mode. Even under the abnormal Vsg condition, the CPU continues the ID sensor check every 10th copy. If Vsg returns to the normal range, the copier returns to normal.
