Canon imagePROGRAF iPF8400, Service Manual

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Chapter 2
2-37
Multi sensor
The photo-reflection-type multi sensor is composed of four LEDs and four light-sensitive sensors. It detects the leading edge, skewing, and width of media and is
used for adjustment of the registration, head height, and color calibration.
During head adjustment, the light reflected by the GAP LED is detected by two light-sensitive sensors (GAP-Far, GAP-Near) )to calculate the head height from the
difference between the measurements.
When color calibration is executed, the light reflected from the printed color chart by the the three-colors LED (red, blue, green) is detected by the light-sensitive
sensor (COLOR-SNS), so the color correction is implemented on the basis of the readings.
During media detection, the light reflected by the diffuse reflection LED and regular reflection LED and the three-colors LED (red, blue, green) are detected by the
light-sensitive sensors (EDGE-SNS, COLOR-SNS).
Ink mist adhering to the sensor could deliver incorrect measurement readings when color calibration is executed. If the ink dot count exceeds a tolerance, the service
error (E194-4034) would occur. If it does, execute service mode: SERVICE MODE > ADJUST > GAP CALIB. after the multisensor has been replaced to clear
the dot count.
F-2-38
- Service mode: After SERVICE MODE > ADJUST > GAP CALIB. has been carried out, pass paper to make sure that it is detected properly.
- If performing the calibration in parallel with the "Head Posi Adj." of the main menu, perform the "Head Posi Adj." first for the sake of higher color calibration
accuracy.
GAP LED
Media detection
Head height detection
Color and media detection
Platen
Media
Light-sensitive sensor
(COLOR-SNS)
Light-sensitive sensor
(EDGE-SNS)
Light-sensitive sensor
(GAP-Far)
Light-sensitive sensor
(GAP-Near)
Diffuse reflection LED
Regular reflection LED
Three-colors LED
(red/green/blue)