Canon imageCLASS MF8450c, Service Manual

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Chapter 4
4-5
4.3 Various Control
4.3.1 Lamp Control
4.3.1.1 Overview
0020-0963
imageCLASS MF9170c / imageCLASS MF9150c / imageCLASS MF8450c
Advance lamp activation control
It takes 9 to 25 sec (which varies depending on the surrounding temperature) from when the cold-cathode tube lamp, which is used as a document lamp, is activated
to when the light intensity reaches the target intensity.
If the document lamp is deactivated immediately after the scan job is completed, it takes time until the light intensity becomes stable next time when the lamp is
activated, causing productivity to decrease.
The machine deactivates the document lamp when five minutes elapse after the scan job is completed.
If the next job is started within five minutes after the scan job is completed, reading can be performed immediately because the document lamp has been activated.
Even in the condition where the document lamp has been deactivated, if the next job is started within five minutes (within 10 minutes after the previous job is
completed), the temperature of the document lamp tube is relatively high, and the time required until reading is enabled can be reduced.
Even after five minutes elapse, the document lamp is activated in advance when any of the following operations is performed. The machine reduces the wait time
by activating the document lamp before the scan job is started.
- Pressing a button on the control panel
- Inserting a USB memory into the USB slot
- Inserting a memory card into the card slot
- Opening/closing the front cover or reverse assembly cover
- Opening/closing the cassette
- Setting paper in the empty cassette
- Setting paper in the empty manual feed tray
- Setting paper in the empty document tray
Overdrive control
When starting activation of the document lamp, the machine applies a voltage higher than the one applied at reading. The machine reduces the time required until
the light intensity of the document lamp reaches the target intensity (overdrive time) as much as possible by controlling the voltage.
The overdrive time varies depending on the tube temperature at the time when activation of the lamp is started. The tube temperature is affected by the previous
activation time, time that elapsed after deactivation, and temperature detected by the environment sensor (PCB28).
The wait time until the activation of the document lamp is completed is calculated by totaling the overdrive time and wait time until the light intensity becomes
stable.
F-4-7
0
0
In the case that the document lamp is activated when five minutes or more elapse after being deactivated.
Activation started
Five min or more
Deactivated
Overdrive time
Wait time
until the light intensity
becomes stable
Wait time
until the light intensity
becomes stable
Time
In the case that the document lamp is activated within five minutes after being deactivated.
Activation started
Five min or less
Deactivated
Overdrive time
Time
Target intensity
Activation completed
Activation completed
Lamp light
intensity
Lamp tube
temperature
Lamp light
intensity
Lamp tube
temperature
Target intensity