Overview - Ricoh FT5233 Service Manual

PROCESS CONTROL
1.2 ID SENSOR CONTROL
Sensor
Pattern
ON OFF ON
A B C
RAM Clear
1 2 3 4 5
Toner Density Detection
1st

1.2.1 Overview

An ID (Image Density) sensor is used to control toner supply.
The sensor is located on the drum unit, under the cleaning unit. Placing the
sensor under the cleaning unit, instead of the development unit, reduces the
risk of scattered toner getting on the sensor.
The CPU checks toner density through the ID sensor by directly sensing the
image density on the drum. This is done every 10 copy cycles (every 5 copy
cycles for the color development unit). Turning the main switch off and on has
no effect because the count is stored in RAM. If the drum initialization is
performed (SP mode #66) or the RAM is cleared (SP mode #99), the CPU
starts counting for the toner density check from the beginning of the first copy
cycle.
The ID sensor pattern (black) is stuck on the operator side of the bottom of
the left scale bracket. During the check cycle, the ID sensor pattern is
exposed prior to exposure of the original.
Original Lead Edge
Original
OFF
Leading Edge Erase
D E
6 7 8 9 10 11
Detection
Toner Supply Clutch ON
ID Sensor
Pattern
12 13 14
Toner Density Detection
2nd
Low Toner Density
Toner Supply Timing
Toner Add
(10 times)
2-2
12 February 1992
Development
Bias
20 21 22
Toner Density
Detection
3rd
Detection