HP Color 9850mfp Service Manual - Page 102

Operation

Page 102 highlights

DEVELOPING UNIT 4.2 Operation hp Color 9850mfp 4.2.1 Flow of developer Developer in the developing unit, after being agitated by the agitator screw, is supplied to the developing sleeve by the conveyance screw. At this time, the bristles amount of the developer on the developing sleeve is regulated by the developing regulation plate. After completion of developing, the developer on the developing sleeve is collected by the scraper magnet roller to prevent the developer immediately after completion of developing from mixing with a new developer. This secures the developing follow-up at a high rate of printing. Collected developer is returned to the agitator screw by the collection screw. This allows developer to make a circulation along a defined path. [4] [5] [6] [7] II UNIT EXPLANATION [1] Agitator screw [2] Conveyance screw [3] Developing regulation plate [4] Drum [3] [2] [1] [5] Developing sleeve [6] Scraper magnet roller [7] Collection screw 4.2.2 Developing control For details of each operation timing related to developing, see "Image formation timing" in "3. Drum unit." 4.2.3 Toner supply control to the developing unit Each of the TDS Y, M, C and K (toner density sensors Y, M, C and K) uses the L detection method (permeability detection of the developer) to detect the toner density of the developer. A value thus obtained is compared with the reference value of the toner density stored in the CPU on the printer control board (PRCB) to see if the toner needs to be supplied. (For toner supply operation, see "6. Toner supply.") 2-28

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DEVELOPING UNIT
2-28
II
UNIT EXPLANATION
4.2
Operation
4.2.1
Flow of developer
Developer in the developing unit, after being agitated by the agitator screw, is supplied to the developing
sleeve by the conveyance screw. At this time, the bristles amount of the developer on the developing
sleeve is regulated by the developing regulation plate. After completion of developing, the developer on
the developing sleeve is collected by the scraper magnet roller to prevent the developer immediately after
completion of developing from mixing with a new developer. This secures the developing follow-up at a
high rate of printing. Collected developer is returned to the agitator screw by the collection screw. This
allows developer to make a circulation along a defined path.
4.2.2
Developing control
For details of each operation timing related to developing, see "Image formation timing" in "3. Drum unit."
4.2.3
Toner supply control to the developing unit
meability detection of the developer) to detect the toner density of the developer. A value thus obtained is
compared with the reference value of the toner density stored in the CPU on the printer control board
ply.")
[1]
Agitator screw
[5]
Developing sleeve
[2]
Conveyance screw
[6]
Scraper magnet roller
[3]
Developing regulation plate
[7]
Collection screw
[4]
Drum
[1]
[2]
[3]
[4]
[5]
[6]
[7]
hp Color 9850mfp
Each of the TDS Y, M, C and K (toner density sensors Y, M, C and K) uses the L detection method (per-
(PRCB) to see if the toner needs to be supplied. (For toner supply operation, see "6. Toner sup-