Developing Rotary Position Detection - Canon MF8100 Series Service Manual

Chapter 2
Photosensitive

2.3.4.4 Developing Rotary Position Detection

This printer has a function of detecting the rotary engaging position between the rotary and drum determined in the developing rotary engaging control.
This detection is performed by the DCNT Board monitoring the output of the engaging sensor (PS712). The DCNT Board determines either of three modes: print,
initial, and memory tag communication, from whether the engaging detection flag located on the end of the drive gear shaft interrupts the PS712.
1. Print mode
2. Initial mode
3. Memory tag
communication mode
When the power is turned on or the top cover is closed, the DCNT Board executes as follows based on the output of the PS712.
When the output of the PS712 is "H", the DCNT Board determines that the printer is in print mode (#1 in the table above) and rotates the engaging motor clockwise
for a specified period to switch the mode to initial mode in order to prepare for the next operation. When the output is "L", the DCNT Board cannot determine
whether the printer is in initial mode (#2 in the table above) or memory tag communication mode (#3 in the table above). In such a case, the DCNT Board rotates
the engaging motor counterclockwise for a specified period to switch the mode to print mode. Then it rotates the motor clockwise for a specified period to switch
the mode to initial mode. The DCNT Board detects mode the printer is actually in from the detection results of the PS712 and prepare for the next operation.
The DCNT Board determines a developing rotary engaging mechanism abnormality, stops the pirnter engine, and notifies it to the SCNT Board under the following
conditions in engaging failure detection:
1) The PS712 does not output "L" even if the engaging motor rotates counter clockwise for a specified period (0.2 seconds) at developing rotary disengaging.
2) The PS712 does not output "H" even if the engaging motor rotates clockwise for a specified period (0.2 seconds) at developing rotary engaging.
2-18
Photosensitive drum
Rotary engaging sensor
Developing cylinder
drum
<When rotary is disengaging>
Developing
Mode
rotary
Engaging
Disengaging
Disengaging
Developing rotary
Engaging detection flag
<When the developing rotary is at disengaging position>
Engaging cam
Pressure plate
<When rotary is engaging>
F-2-31
T-2-5
Status
Memory tag Rotary engaging
contact sensor (PS712)
Disengaging
SENSOR
FLAG
"H"
Disengaging
"L"
Engaging
Drive gear
Engaging motor
(PM704)
Rotary engaging cam
Pressure plate
Relationship between the
rotational direction of the
engaging motor and the
position of the sensor flag
2
3
CCW
CW
1
"L
0008-1709