Ricoh FT8680, Service Manual

Page: 71 / 389

7.2 TONER DENSITY DETECTION
7.2.1 ID Sensor Pattern Production
Drum sensitivity varies from copy to copy. Especially, drum rest time affects
drum sensitivity.
To compensate the sensitivity changes in the copy run, the ID sensor
development timing and development bias is controlled using two copy
counters.
Counter A:
Counts the copy number. Resets when the Start key is pressed.
Counter B:
Counts the copy number. Resets if the accumulated number is 10 or
above when the Start key is pressed, or when the ID sensor pattern is
made.
NOTE: Both counters are reset when the main switch is turned on or the
doors are opened.
The ID sensor pattern is made in the following conditions:
1) At the leading edge of the first copy cycle after the main switch is
turned on or when the doors are opened.
2) If A
≥
10
At the trailing edge of the copy cycle when;
A = 10n (n: any numeric number)
3) If A
<
10
When the last copy is finished and B
≥
10, then the pattern is
developed at the leading edge of the next copy cycle.
Counter A
Counter B
Main SW
ON
Start Key
Start Key Start Key
ID Sensor Pattern
A171D531.wmf
31 July 1995 TONER DENSITY DETECTION AND SUPPLY
2-47