RICOH AFICIO 550
Manual de Servicio

DEVELOPMENT AND TONER SUPPLY

June 30, 1998

V52 and V5/ detection
The ID sensor detects the following voltages. · VSG: The ID sensor output when checking the drum surface · VSP: The ID sensor output when checking the ID sensor pattern In this way, the reflectivity of both the drum and the pattern on the drum are checked. The ID sensor pattern is made on the drum with the charge corona and laser diode. VSP/VSG is detected every 50 copies (or at the end of a copy job of more than 50 pages) to update the TD sensor reference voltage (VREF). This interval can be changed using SP2-210. This compensates for any variations in the reflectivity of the pattern on the drum or the reflectivity of the drum surface.

V4-. Update
VREF is updated using VSP/VSG and VT. This is done every 50 copies (or at the end of a copy job of more than 50 pages), and during process control initial setting. See �VREF Update� in the Process Control section for details.

V6 detection
The toner density in the developer is detected once every copy cycle after the trailing edge of the image passes through the development roller.

Image pixel count
For each copy, the CPU adds up the image data value of each pixel and converts the sum to a value between 0 and 255. (The value would be 255 if the page was completely black.)

Gain Determination
GAIN is another factor in the toner supply clutch on time calculation. Its value can be 0, 1, 2, 3, or 4. It is calculated every copy using �VREF � VT�.

Toner Supply Clutch On Time Calculation
The toner supply clutch on time for each copy is decided using the following formula: (GAIN ´ Image pixel count ´ 0.7mg/cm /Toner Supply Rate) + 50ms The toner supply rate can be changed using SP2-209.

Image pixel count control
This mode should only be use as a temporary countermeasure while waiting for replacement parts, such as a TD sensor. This mode controls the toner supply using the same formula for the toner supply clutch on time. However, the GAIN value is fixed at 0.7.
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