Canon ImageRunner iR8500 Series, Service Manual, Page: 344 / 1122

Chapter 8
8-4
F-8-3
8.1.4 Pre-Transfer Exposure LED
0006-9749
iR105i/iR105+
The machine uses a process speed of 500 mm/sec to support a copying speed of 105 pages/min (A4, Direct). To make up for the decrease in charging on
the photosensitive drum caused by the increase in the process speed, the machine uses a photosensitive drum with a high degree of charging capacity and
a pre-exposure lamp with a short wave length (660 nm), thus ensuring a specific degree of charging.
The higher process speed also decreases static charges used for separation; the pre-transfer exposure LED is used to compensate for the decrease:
MEMO:
Pre-Transfer Exposure
Function: In an initial phase of the transfer process, the charges on the photosensitive drum (background potential) are reduced in advance, thereby
weakening the stack bonding between the photosensitive drum and the transfer paper and ultimately encouraging separation.
Timing: The LED is turned on 100 msec before the leading edge of an image reaches a specific point until its trailing edge leaves it
8.1.5 Pre-Transfer Exposure LED
0009-0803
iR9070
The machine uses a process speed of 500 mm/sec to support a copying speed of 90 pages/min (A4, Direct). To make up for the decrease in charging on
the photosensitive drum caused by the increase in the process speed, the machine uses a photosensitive drum with a high degree of charging capacity and
a pre-exposure lamp with a short wave length (660 nm), thus ensuring a specific degree of charging.
The higher process speed also decreases static charges used for separation; the pre-transfer exposure LED is used to compensate for the decrease:
MEMO:
Pre-Transfer Exposure
Function: In an initial phase of the transfer process, the charges on the photosensitive drum (background potential) are reduced in advance, thereby
weakening the stack bonding between the photosensitive drum and the transfer paper and ultimately encouraging separation.
Timing: The LED is turned on 100 msec before the leading edge of an image reaches a specific point until its trailing edge leaves it
8.1.6 Pre-Transfer Exposure LED
0008-8683
iR85+
The machine uses a process speed of 450 mm/sec to support a printing speed of 85 pages/min (A4/LTR). To make up for the decrease in charging on the
photosensitive drum caused by the increase in the process speed, the machine uses a photosensitive drum with a high degree of charging capacity and a
pre-exposure lamp with a short wave length (660 nm), thus ensuring a specific degree of charging.
The higher process speed also decreases static charges used for separation; the pre-transfer exposure LED is used to compensate for the decrease:
Toner cartridge
Developing assembly
Hopper
Dust-collecting roller
Pre-transfer charging assembly
Transfer guide
Transfer charging assembly
Separation charging assembly
Cleaner unit
Pre-exposure LED
Primary charging assembly
Potential sensor
Pre-transfer exposure LED